JP2998517B2 - Processing head and laser processing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser processing apparatus, and more particularly to a laser processing apparatus. In this specification, laser cutting will be described as an example of laser processing.

[0002]

2. Description of the Related Art Cutting performance in laser processing depends on operating conditions such as the output of a laser beam, the focal position of the laser beam on the surface of the material to be cut, the assist gas pressure, and the distance between the surface of the material to be cut and the tip of the laser beam nozzle. Depends on
It also depends on the material conditions such as material type, surface condition, quality, composition, thickness, and the like. The laser processing apparatus is required to have a wide tolerance to such operating conditions and material conditions and to obtain stable processing quality. In particular, when cutting steel, etc., the oxygen jet used as an assist gas not only melts the material to be cut by direct heating with a laser beam and blows away the molten metal, but also cuts the material with a strong combustion oxidation reaction. Is sublimated or melted to significantly improve the cutting efficiency. Therefore, the quality of the cut surface of the material to be cut is largely determined by the combustion oxidation rate on the surface of the cut surface. In other words, as the combustion oxidation rate increases, the roughness of the cut surface decreases, and the supplied oxygen is continuously consumed. Therefore, self-burning due to oxygen excess (explosive strong self- The phenomenon that combustion occurs and the cut surface quality is impaired) is less likely to occur. Further, since the cutting speed increases, higher-speed cutting can be performed. Therefore, it is very important to optimize the gas supply conditions to improve the combustion oxidation rate. In view of the above, various improvements have been made to the nozzle for gas supply.

FIG. 46 shows, for example, Japanese Patent Publication No. 61-60575.
FIG. 1 is a schematic vertical cross-sectional view showing a laser beam nozzle provided in a processing head in a conventional laser processing apparatus disclosed in Japanese Unexamined Patent Publication (Kokai) No. H10-15095. In the drawing, 1 is a main assist gas nozzle, 2 is an auxiliary assist gas nozzle, 3 is a cutting plate surface, and 10 is an assist gas supply source.

Next, the operation will be described. The laser beam nozzle provided in the processing head in the conventional laser processing apparatus is configured as described above, and this nozzle has a multiplex structure, a gas flow path on the central axis, and a concentric multiplex to surround the gas flow path. Having a flow path formed in The oxygen supplied to the cutting material from the flow path on the central axis has a relatively high pressure and a high flow rate. This oxygen mainly flows into the cut groove, part of which is consumed in the oxidative combustion reaction, and the rest is
It is used to blow down and remove molten and oxidized metal. The gas supplied from the flow path at the outer peripheral portion has a relatively low speed, has a role of preventing entrainment of ambient air, stabilizing the flow near the central axis, and maintaining a high oxygen concentration. Furthermore, the ejection direction of each auxiliary assist gas outlet is provided in parallel with the ejection direction of the main assist gas outlet, so that the gas is ejected in a laminar flow, and the boundary between the main assist gas outlet and each auxiliary assist gas outlet is provided. Has a thick wall and interference with the main assist gas is suppressed as much as possible, so that the main assist gas is also kept in a laminar flow state.

[0005]

In laser processing, an assist gas (oxygen gas) is supplied to a metal cutting surface heated to a high temperature by the energy of a laser beam to cause an oxidative combustion reaction. It is necessary to always supply a necessary amount of assist gas (oxygen gas) into a narrow cut groove width of less than mm. In addition, combustion products (gas or molten metal) are generated in the vicinity of the cut surface by the oxidation reaction. If the assist gas (oxygen gas) jet is in a laminar state, the assist gas must diffuse into the combustion product (gas component) atmosphere to reach the metal surface. Therefore, in order to increase the oxidation rate, the assist gas jet is made turbulent to disturb the boundary layer of the combustion reaction zone near the cut surface, and the surface of fresh assist gas and combustion products (gas components) is renewed. It is effective to perform

A laser beam nozzle provided in a processing head in a conventional laser processing apparatus is provided with a jetting direction of each auxiliary assist gas jet in parallel with a jet direction of a main assist gas jet, and jets in a laminar flow. Since the interference with the main assist gas is suppressed as much as possible, the main assist gas is also kept in a laminar flow state, the flow is stabilized, and the assist gas purity (oxygen purity) in the center is maintained at a high level. Although it works, the main assist gas supply pressure must be increased in order to supply the assist gas (oxygen gas) effectively within a narrow cut groove width because the flow at the center is stable. In addition, the velocity fluctuation amount (turbulence intensity) at the center of the nozzle flow
Is small, a boundary layer having a low assist gas concentration (oxygen concentration) is formed on the metal oxidation reaction surface, and it is difficult for fresh assist gas (oxygen gas) to reach the reaction surface directly.
Therefore, there is a problem that the supplied assist gas (oxygen gas) does not effectively contribute to the oxidation reaction. Also,
In this case, depending on conditions such as the flow rate, there is a problem that oxygen that is not consumed effectively may remain in the dents and the like inside the cut groove, which causes self-burning. In addition, a thick partition wall exists at the boundary between the main assist gas outlet and each auxiliary assist gas outlet, and the assist gas ejection pressure or the ejection speed distribution from the tip of the laser beam nozzle does not change continuously. Therefore, separation occurs at the boundary between the main assist gas jet, the auxiliary assist gas jets, and the surrounding air in the thick portion, which promotes diffusion mixing of the main assist gas and the auxiliary assist gas, and ultimately There is also a problem that the effect of blocking the outside assist gas from the surrounding air is reduced and the purity (oxygen purity) of the main assist gas is reduced.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems. For example, it is possible to achieve a reduction in roughness of a cut surface and a suppression of self-burning, a high purity with a small amount of ambient air entrainment, and a turbulence. The purpose of this processing head is to obtain a processing head of a laser processing apparatus capable of supplying an assist gas (oxygen gas) having a large diameter to a processing surface, promoting an oxidation reaction, and stably performing high speed and high quality processing. It is an object of the present invention to obtain a laser processing apparatus that can stably and accurately process laser light.

[0008]

According to the present invention, there is provided a machining head comprising:
The main assist gas nozzle laser beam in a central portion of the laser beam nozzle passes provided, this makes it an annular auxiliary assist gas nozzles surrounding the main assist-gas nozzle provided singlet above, reed toward the workpiece from the both nozzles
In the processing head that blows out the strike gas,
Flow rate of main assist gas at the outlet of the gas nozzle
The auxiliary assist gas at the ejection port of the auxiliary assist gas nozzle.
The flow rate of the assist gas is made larger than that of the auxiliary assist gas nozzle, and the inner diameter of the innermost ejection port of the auxiliary assist gas nozzle is made larger than or equal to the inner diameter of the ejection port of the main assist gas nozzle. The assist gas nozzle is provided on the upstream side of the gas flow from at least one of the ejection ports, and the outer wall of the main assist gas nozzle is configured such that the thickness of the tip portion gradually decreases toward the downstream side of the gas flow. Things.

In order to increase the pressure fluctuation and flow velocity fluctuation values of the main assist gas flow, there is provided a swirl flow forming means for making at least a part of the main assist gas flow blown out from the main assist gas nozzle jet into a swirl flow.

[0010]

[0011]

The swirling flow forming means is a spirally twisted stationary blade or groove provided on the inner wall surface of the main assist gas nozzle.

The swirling flow forming means has a nozzle port provided on the inner wall surface of the main assist gas nozzle, and is composed of a main assist gas sub-flow nozzle for jetting gas in parallel with the circumferential direction of the main assist gas nozzle.

Further, a static pressure converting means for converting a dynamic pressure of the auxiliary assist gas flow flowing from the auxiliary assist gas supply port into a static pressure is provided in the auxiliary assist gas nozzle.

In addition, a static pressure conversion surface is provided to face the auxiliary assist gas flow flowing from the auxiliary assist gas supply port, and a return wall surface forming a gas retaining space is formed at the end of the static pressure conversion surface to protrude. I have.

Furthermore, an auxiliary assist gas nozzle supply port capable of adjusting the flow rate of the auxiliary assist gas is provided around the main assist gas nozzle supply port, and both supply ports are connected to the same gas supply source.

Further, an opening area adjusting means for adjusting an opening area of the auxiliary assist gas nozzle supply port is provided.

Further, a fluid resistor is provided at the auxiliary assist gas nozzle supply port.

Further, there is provided means for adjusting the flow velocity distribution at the auxiliary assist gas nozzle ejection port. For example, means for changing the flow velocity distribution asymmetrically with respect to the center axis in the cross section in the nozzle radial direction, specifically, means for changing the flow velocity distribution and flow rate of the gas in front and rear in the processing progress direction are provided.

A plurality of gas supply ports for the auxiliary assist gas nozzle are provided at least on the inner wall of the auxiliary assist gas nozzle, or the inside of the auxiliary assist gas nozzle is divided into small rooms in the radial direction by partition walls, and the flow velocity distribution at the auxiliary assist gas nozzle ejection port is adjusted. are doing.

Further, the apparatus has means for individually adjusting the flow rate of gas supplied into each small room.

Further, an auxiliary assist gas supply port is formed, an annular partition for partitioning the inside of the auxiliary assist gas nozzle in the axial direction, and is provided rotatably in contact with the downstream side surface of the annular partition. An annular flat plate which is shielded and partially cut away, which is attached to both ends of the flat plate, radially partitions the inside of the auxiliary assist gas nozzle downstream of the annular partition wall, and rotates in cooperation with the flat plate. A partition plate, a driving device for driving the flat plate, and a control device for operating the driving device are provided.

[0023] The laser machining apparatus of the present invention, the
It has a processing head. Further, the processing head is provided with information detecting means for detecting information such as the temperature of the surface of the workpiece, the width of the cut groove, and the amount of spark light during the processing, and the processing head is provided in accordance with a signal from the information detecting means. The gas type, flow rate or pressure of the assist gas ejected from the nozzle is adjusted.

According to another aspect of the present invention, there is provided a laser processing apparatus including the above-described processing head and an operation control device, wherein the type, flow rate, or pressure of the assist gas ejected from the processing head is programmed and controlled by the operation control device. It is like that.

Further, a thickness measuring means for detecting the thickness of the workpiece is provided, and the flow rate or pressure of the assist gas ejected from the machining head is controlled by an operation control device according to the output of the thickness measuring means. It is something to do.

The processing head according to the present invention has a main assist gas nozzle.
The flow rate of the main assist gas at the nozzle
Auxiliary assist gas at the outlet of the cyst gas nozzle
It is formed so that the inner diameter of the innermost auxiliary assist gas outlet is larger than or equal to the inner diameter of the main assist gas nozzle, and the position of the outlet of the main assist gas nozzle is Since the outer wall of the main assist gas nozzle is provided upstream of at least one of the jet ports and the outer wall of the main assist gas nozzle is configured such that the thickness of the tip gradually decreases toward the downstream side of the gas flow, In the assist gas flow, a sufficient distance between the injection port and the processing surface can be ensured, so that turbulence develops sufficiently downstream, and a large flow velocity fluctuation can be obtained near the processing surface. On the other hand, the auxiliary assist gas flow flows along the outer wall surface where the thickness of the tip portion of the main assist gas nozzle gradually decreases, and in the vicinity of the tip portion of the main assist gas nozzle, the flow direction with the main assist gas flow is almost the same. At the tip of the gas nozzle, it smoothly contacts the main assist gas flow without causing large-scale turbulence due to flow separation, flows downstream while maintaining the speed difference with the main assist gas flow, and the main assist gas is discharged at the auxiliary assist gas outlet Form a continuous flow velocity distribution with the gas flow. As described above, a large flow velocity fluctuation of the main assist gas flow can be obtained in the vicinity of the processing surface, and the auxiliary assist gas flow forms a continuous flow distribution with the main assist gas flow at the ejection port.
The entire gas flow is not disturbed, and the entrained amount of ambient air is small, and high-purity and highly disturbed assist gas can be supplied to the processing surface.

By providing the swirl flow forming means, a swirl flow is generated in the gas flowing inside the main assist gas nozzle, the degree of turbulence on the central axis increases, and the pressure fluctuation and flow velocity fluctuation values of the main assist gas flow increase. .

[0028]

[0029]

Further, by providing a spirally twisted stationary blade or groove on the inner wall surface of the main assist gas nozzle, a swirling flow can be easily formed.

Further, a nozzle port is provided on the inner wall surface of the main assist gas nozzle, and a main assist gas sub-flow nozzle for jetting gas in parallel with the circumferential direction of the main assist gas nozzle is provided.
Thus, the swirling flow can be easily formed by ejecting the main assist gas.

Further, the static pressure converting means for converting the dynamic pressure of the auxiliary assist gas flow into a static pressure recovers the static pressure of the gas introduced into the auxiliary assist gas nozzle to make the flow of the auxiliary assist gas uniform, The flow velocity fluctuation is reduced to prevent the entrainment of external air.

Further, by providing a static pressure conversion surface and projecting a return wall forming a gas retaining space at the end of the static pressure conversion surface, the gas introduced into this space can be recovered from the static pressure and rectified. To further stabilize the peripheral flow and prevent air entrainment.

Further, an auxiliary assist gas nozzle supply port capable of adjusting the flow rate of the auxiliary assist gas is provided around the main assist gas nozzle supply port, and both supply ports are connected to the same gas supply source. Since the auxiliary assist gas is branched, for example, by appropriately setting the area and the number of small holes of the auxiliary assist gas nozzle supply port, the flow rate of the auxiliary assist gas is adjusted, and the main assist gas flow rate, The auxiliary assist gas flow rate is set to an appropriate value.

Further, the flow rate and pressure of the main assist gas and the auxiliary assist gas can be easily and individually adjusted automatically or manually by the opening area adjusting means provided at the auxiliary assist gas nozzle supply port. In the case of manual operation, an appropriate flow rate and flow rate ratio can be obtained without nozzle replacement, and in the case of automatic operation, the appropriate flow rate and flow rate ratio are controlled according to constant or changing conditions during cutting.

The flow rate of the auxiliary assist gas can be easily adjusted by a flow path resistor provided at the auxiliary assist gas nozzle supply port, for example, made of a mesh or a porous material. Also, the auxiliary assist gas flow is made more uniform,
The flow velocity fluctuation is reduced to prevent the entrainment of external air.

Means is provided for adjusting the flow velocity distribution at the auxiliary assist gas nozzle ejection port. For example, the flow velocity distribution is changed asymmetrically with respect to the center axis in the cross section in the nozzle radial direction. Since the flow velocity distribution and flow rate of the gas can be changed between and behind, the gas can be effectively supplied into the groove according to the processing progress direction, the type of processing, the conditions, and the like.

Further, at least a plurality of gas supply ports for the auxiliary assist gas nozzle are provided on the inner wall of the auxiliary assist gas nozzle, or the inside of the auxiliary assist gas nozzle is divided into small rooms by partition walls. By appropriately setting the number, the size, the position, and the number of the partition walls, the assist gas flow distribution at the outlet of the auxiliary assist gas nozzle can be freely set.

Furthermore, since there are means for individually adjusting the flow rate of the supply gas into each small room, for example, a separate gas supply source and a flow control device, the flow rate distribution at the outlet of the auxiliary assist gas nozzle can be freely adjusted according to the processing conditions. For example, since the assist gas can always be supplied from the back of the groove in accordance with the processing progress direction, gas supply to the inside of the groove is efficiently performed, and the processing speed and the processing quality are improved.

Further, an auxiliary assist gas supply port is formed, an annular partition for partitioning the inside of the auxiliary assist gas nozzle in the axial direction, and is provided rotatably in contact with the downstream side surface of the annular partition. An annular flat plate which is shielded and partially cut away, which is attached to both ends of the flat plate, radially partitions the inside of the auxiliary assist gas nozzle downstream of the annular partition wall, and rotates in cooperation with the flat plate. Since a partition plate, a driving device for driving the flat plate, and a control device for operating the driving device are provided, the outlet flow rate distribution of the auxiliary assist gas nozzle can be freely controlled in accordance with processing conditions. In addition, since the assist gas can always be supplied from the back of the groove, the gas is efficiently supplied to the inside of the groove, and the processing speed and the processing quality are improved.

In the processing apparatus using the processing head, the entire gas flow is not disturbed,
Air with a small amount of air entrapment and high purity and large turbulence
As a result of supplying cyst gas to the processing surface, stable and accurate
Can be processed. Further, information processing means for detecting information such as the temperature of the surface of the workpiece, the width of the cutting groove, and the amount of spark light during the processing is provided, and the assist gas ejected from the processing head according to the output of the information detecting means is provided. Since the gas type, flow rate or pressure is adjusted, abnormal processing can be avoided.

Further, since the gas type, flow rate or pressure of the assist gas ejected from the processing head is controlled by the operation control device according to the processing conditions, more stable processing can be performed. .

Further, a thickness measuring means for detecting the thickness of the workpiece is provided, and the flow rate or pressure of the assist gas ejected from the machining head is controlled by an operation control device according to the output of the thickness measuring means. Therefore, the machining can be performed stably without the operator setting the gas flow rate or the like according to the plate thickness.

[0044]

[Embodiment 1] FIG. 1 is a schematic longitudinal sectional view showing a processing head of a laser processing apparatus according to a first embodiment of the present invention. A main assist gas nozzle _{1 having} a diameter D1 located at the innermost periphery and a main assist gas nozzle duct 1b connected to the main assist gas nozzle 1b, through which a laser beam passes.
And the inner diameter D ₂ (D ₂
≧ D _1, multi-layered structure having an auxiliary assist-gas nozzle 2 composed of the auxiliary assist-gas nozzle jet outlet 2a and the duct 2b which connects thereto in this case D _2> D _1), in this case 2
Has a heavy structure. The ejection port 1a of the main assist gas nozzle 1 is disposed on the upstream side of the assist gas flow from the ejection port 2a of the auxiliary assist gas nozzle 2, and
The thickness of the outer wall of the nozzle 1 is directed toward the downstream side of the gas flow.
It is configured so that it gradually becomes thinner . The assist gas (oxygen gas) is supplied to the cut plate surface 3 of the workpiece along the path shown by the arrow in the figure.

The outline of the distribution of the pressure fluctuation on the cutting plate surface 3 of the assist gas flow in this embodiment is shown in FIG. The vertical axis represents pressure fluctuation p / P (%) (p: pressure fluctuation amount, P: absolute value of pressure), and is shown in correspondence with the assist gas ejection port. Since the flow rate of the assist gas flowing through the main assist gas nozzle 1 is large, the pressure fluctuation value immediately below the ejection port 1a of the main assist gas nozzle is large, and is suppressed to a small value immediately below the ejection port 2a of the auxiliary assist gas nozzle. By the pumping action due to the fluctuation of the pressure, the required gas flow rate can be supplied to the cut groove without increasing the original pressure.

Further, a large variation in the flow velocity indicates that the turbulence of the oxygen gas flowing into the cut groove is greatly turbulent. In the vicinity of the cut surface where the combustion reaction is occurring, the oxide and oxygen generated by the reaction form a mixed layer,
Since the oxidation reaction rate depends on the rate at which oxygen gas moves inside the mixed layer by diffusion and reaches the reaction surface, turbulence of the flow and destabilization of the mixed layer increases the oxidation rate. It is effective for. Therefore, by using a processing head having the nozzle configuration of the present embodiment and making the flow of oxygen gas turbulent, the mixed layer is destabilized as schematically shown in the explanatory view of FIG. Can be transported directly to the vicinity of the reaction surface, and at the same time, a mixed gas having a high oxide concentration can be removed from the vicinity of the reaction surface. Becomes possible. Further, since the supplied oxygen gas is continuously and effectively consumed, self-burning caused by an imbalance between the temperature rise by the laser and the oxidation reaction speed can be prevented, and stable processing can be performed.

Further, the assist gas (oxygen gas) flowing out from the auxiliary assist gas nozzle prevents the entrainment of the surrounding air, so that the purity of the oxygen in the central flow (ie, the main assist gas) flowing into the cut groove is maintained. More stable cutting becomes possible.

FIG. 4 is an explanatory view showing an outline of the flow velocity distribution on the surface of the cutting plate, and the vertical axis represents the jet gas flow velocity u (m / s).
, Corresponding to the assist gas outlet. According to the present embodiment, as shown in FIG. 2 and FIG. 4, the distribution of the ejection gas pressure and the ejection gas flow velocity at the assist gas ejection port is higher at the center of the nozzle and changes continuously, thereby achieving Since there is no separation between the assist gas flow and each auxiliary assist gas flow and at the boundary with the surrounding air, the air shutoff effect of the auxiliary assist gas is reduced, and the purity (oxygen purity) of the main assist gas is reduced. Is also solved.

FIG. 5 is a characteristic diagram showing the relationship between the pressure fluctuation value and the cut surface roughness. The horizontal axis represents the pressure fluctuation value (%), the ratio p / P of the fluctuation component p to the pressure P on the cutting plate surface just below the central axis of the main assist gas nozzle, and the vertical axis represents the cut surface roughness Rmax (μ).
m). The cut material is mild steel SS400, plate thickness 12mm, processing conditions are laser power 1400W, processing speed 0.7m /
min. The figure clearly shows that the larger the pressure fluctuation value is, the smaller the surface roughness is, and therefore the processing quality is improved. In other words, this indicates that high-quality high-speed cutting can be performed by processing with the processing head having the nozzle configuration according to the present embodiment. Further, the properties of the cut surface processed by the processing head of the present embodiment and the cut surface processed by the processing head having the conventional nozzle configuration are compared and shown by cross-sectional photographs. Cut material is mild steel SS400, plate thickness 12mm
The processing conditions are laser power 3000W, processing speed
1.5 m / min. The result of cutting by the processing head of the conventional nozzle is shown in Reference Photo 1, and the result of cutting by the processing head having the nozzle configuration of the present embodiment is shown in Reference Photo 2. The pressure fluctuation value of the processing head of this embodiment is p / P = 1.0%, and the pressure fluctuation value of the processing head of the conventional example is p / P = 0.1%. From this photograph, by using the processing head of this embodiment,
It can be seen that the processing quality of the cut surface has been improved.

The graphs of FIGS. 6A and 6B show the laser output value and the tolerance with respect to the processing speed in the laser cutting test using this embodiment and the conventional processing head. The vertical axis is the processing speed (m / min), and the horizontal axis is the laser output (kW). Material is S
S400, 12mmt thick. FIG. 6A shows the machining allowance of the processing head of the conventional nozzle (pressure fluctuation value 0.1%), and FIG. 6B shows the machining allowance of the processing head of the present embodiment. Indicates the range that can be cut normally. It is clear that high-speed cutting is possible with the working head of this embodiment.

Next, the relationship between the pressure and flow velocity fluctuation of the main assist gas flow in this embodiment, the positional relationship between the assist gas nozzle outlets 1a and 2a, and the distance between the cutting plate surface 3 and the nozzle lower end (inlet). Will be described with reference to the schematic sectional view of FIG. In the drawing, l ₁ is the distance between the ejection port 2 a of the auxiliary assist gas nozzle 2 and the ejection port 1 a of the main assist gas nozzle 1 located on the upstream side of the assist gas flow, H is the cutting plate surface 3 and the nozzle lower end (the ejection port ). In the characteristic diagram of FIG. 8, the distance between the cutting plate surface 3 and the lower end of the nozzle is Hmm, and when this H is changed, the pressure fluctuation value p / P% just below the nozzle center axis and the distance l ₁ between the injection ports are changed.
The relationship is shown below. The test was performed under the conditions of a diameter D ₁ = 1.5 mm and D ₂ = 5 mm. The vertical axis indicates the pressure fluctuation value p / P (%), and the horizontal axis indicates the distance l ₁ (mm) between the injection ports.
The characteristic curve of 4 mm, the characteristic curve marked with △ indicates the characteristic of H = 2 mm,
The characteristic curve indicated by the mark indicates the characteristic of H = 1 mm. From this figure, the condition that the pressure fluctuation becomes 0.8% or more is H + l ₁ ≧ 5 × D ₁ , and if l ₁ ≧ 5 × D ₁ , the machining allowance with respect to the nozzle height H is improved. Large pressure fluctuations can be obtained with a simple structure.

Embodiment 2 FIG. In the first embodiment, the processing head is composed of the main assist gas nozzle 1 and one auxiliary assist gas nozzle 2. However, as shown in a schematic vertical sectional view of FIG. Needless to say, it may be. In this case, the same effect as that of the first embodiment can be obtained if the main assist gas nozzle 1a is located on the upstream side of the assist gas flow from at least one of the plurality of auxiliary assist gas nozzles 2a.

Embodiment 3 FIG. FIGS. 10 (a), (b) and (c) show the claims of the third embodiment of the present invention.
2 shows a processing head of a laser processing apparatus corresponding to 2 and 3 .
In this embodiment, a plurality of spirally twisted stationary vanes of the swirling flow forming means are provided as another specific means for increasing the pressure and flow velocity fluctuations of the main assist gas flow. FIG.
FIG. 10A is a schematic longitudinal sectional view of the processing head of the third embodiment, and FIG.
(b) is a perspective view showing the main assist gas nozzle as seen through. In this embodiment, a plurality of stationary blades 4 that are spirally twisted are provided in a straight portion of the inner wall of the duct of the main assist gas nozzle 1. The stationary vanes 4 generate a swirling flow in the gas flowing inside the main assist gas nozzle 1. If the jet has a swirl component at the time of jetting the nozzle, the turbulence intensity in the center axis shape is large. When the distance between the nozzle and the cutting plate surface is about the same as the nozzle diameter,
The degree of disturbance reaches 10% or more. Therefore, an oxidative combustion reaction occurs effectively, the oxidation speed is increased, and the processing quality and stability are enhanced, and at the same time, high-speed cutting can be performed.

In the method in which at least a part of the main assist gas flow is swirled in this embodiment, the position of the lower end of the main assist gas nozzle (ie, jet port 1a) and the position of the lower end of the auxiliary assist gas nozzle (ie, jet port 2a) are determined. Even if the relative distance l _{1 is set} to 0, the flow rate fluctuation can be given to the main assist gas. In the above embodiment, in order to bring the main assist gas closer to the processing lens side than the conventional nozzle, the laser beam diameter at the lower end position of the main assist gas nozzle is large, and the adjustment is performed so that the laser beam optical axis and the nozzle center axis are aligned. While it is relatively difficult to adjust the distance between the focal point and the surface of the workpiece, in this embodiment, even if the relative distance l ₁ between the nozzle outlet positions is set to 0, it is not possible to apply a flow velocity variation to the main assist gas. Since it is possible, there is an advantage that the adjustment work is facilitated.

Further, the stationary vane may be provided in a contraction portion downstream of the main assist gas nozzle 1 as shown in a perspective view of the main assist gas nozzle which shows the inside of FIG.

Embodiment 4 FIG. FIGS. 11 (a) and 11 (b) are perspective views showing a main assist gas nozzle of a processing head corresponding to claim 3 of the fourth embodiment of the present invention. In the fourth embodiment shown in FIG. 11A, a plurality of spirally twisted grooves 5 are provided in the straight portion of the inner wall of the duct of the main assist gas nozzle 1 as a swirl flow forming means. Due to the spiral groove 5, a part of the assist gas (oxygen gas) flowing in the main assist gas nozzle 1 flows along the spiral flow path formed by the groove 5, so that a swirling flow is generated.
Turbulence intensity at the center of the main assist gas jet increases.
Therefore, also in this case, the oxidation speed is promoted, and the cutting speed and the cutting quality can be improved.

The spiral groove 5 may be provided in a contraction section downstream of the main assist gas nozzle 1 as shown in FIG.

Embodiment 5 FIG. FIGS. 12A and 12B show a main assist gas nozzle of a processing head corresponding to claim 4 of the fifth embodiment of the present invention,
FIG. 12A is a top view, and FIG. 12B is a schematic longitudinal sectional view. In the fifth embodiment, the swirl flow forming means has a nozzle port 6a on the inner wall surface of the main assist gas nozzle 1 and ejects gas in parallel with the circumferential direction of the main assist gas nozzle 1 (that is, in the tangential direction of the outer circumference of the main assist gas main flow). A main assist gas sub-flow nozzle 6 for ejecting the main assist gas sub-flow is provided symmetrically, and a part of the main assist gas is jetted from the main assist gas sub-flow nozzle 6 to give a turn to the main assist gas. I have. Thereby, the same effects as in the third and fourth embodiments can be obtained.

Embodiment 6 FIG. Figure 13 is a schematic longitudinal sectional view showing a processing head of a laser machining apparatus corresponding to claim 5 of Example 6 of the present invention. Static pressure conversion means for converting the dynamic pressure of the auxiliary assist gas flow into a static pressure at a position where the gas flow in the duct 2b of the auxiliary assist gas nozzle 2 flowing from the auxiliary assist gas supply port 2c is blocked, in this case, static pressure conversion A surface 7 is provided. The dashed arrow indicates the assist gas flow. The gas guided into the auxiliary assist gas nozzle duct 2b collides with the static pressure conversion surface 7 and once recovers the static pressure. Therefore, a uniform flow downstream of the static pressure conversion surface 7 results in the auxiliary assist gas nozzle outlet 2a. Is discharged from Accordingly, the gas flow at the outer peripheral portion of the nozzle becomes a uniform flow with little turbulence, and the effect of preventing surrounding air from being entrained is improved.

In this embodiment, as the static pressure converting means, the static pressure converting surface 7 which is a flat portion parallel to the lower surface of the nozzle outlet 2a is shown. Needless to say, the same effect can be obtained as long as the static pressure is restored by colliding with the gas guided to the flow path of the peripheral flow nozzle (that is, the auxiliary assist gas nozzle).

Embodiment 7 FIG. FIG. 14 is a schematic vertical sectional view showing a processing head of a laser processing apparatus according to a sixth embodiment of the present invention. In this embodiment, an annular return wall surface 8 protrudes from the end of the static pressure conversion surface 7 provided inside the auxiliary assist gas duct 2b described in the sixth embodiment.
The height of the return wall surface 8 is adjusted so as to have an appropriate gap between the upper end thereof and the inner peripheral nozzle, in this case, the outer wall of the main assist gas nozzle 1, thereby forming a gas retaining space 8a. The broken arrows in the figure indicate the gas flows. The gas guided to the duct 2b of the auxiliary assist gas once fills the gas retaining space 8a formed by the return wall surface 8, the inner wall of the auxiliary assist gas nozzle 2, and the static pressure conversion surface 7, and recovers the static pressure. Thereafter, the gas flows out from the upper end of the return wall surface 8 into the duct 2b of the auxiliary assist gas nozzle at a uniform flow rate, and is discharged to the outside from the outlet 2a. Therefore, the flow at the outer peripheral portion is a stable and uniform flow with little turbulence, and the effect of preventing air entrapment is further improved.

FIG. 15 is a characteristic diagram showing the distribution of the amount of pressure fluctuation on the cutting plate surface of the assist gas flow by the working heads of the sixth, seventh and conventional examples. The vertical axis is the pressure fluctuation value p / P (%), and the horizontal axis is the distance r (mm) from the center of the nozzle.
The characteristic curve of the solid line represents the characteristic of the seventh embodiment, the characteristic curve of the broken line represents the characteristic of the sixth embodiment, and the characteristic curve of the one-dot chain line represents the characteristic of the conventional example. From this figure, the pressure fluctuation value of the auxiliary assist gas flow on the cutting plate surface shows that Example 7 has the smallest pressure fluctuation value and a uniform and stable flow. Thereby, the amount of entrained ambient air is reduced, and the oxygen purity is kept at a high level.

Embodiment 8 FIG. FIG. 16 is a schematic vertical sectional view showing a processing head of a laser processing apparatus according to Embodiment 8 of the present invention.
In this embodiment, the cross-sectional area of the flow passage at the tip of the auxiliary assist gas nozzle 2 is the auxiliary assist gas nozzle ejection port 2a.
An expansion channel 9 that gradually expands toward is formed.
By doing so, the auxiliary assist gas nozzle 2
The assist gas (oxygen gas) ejected from the nozzle is not accelerated and flows parallel to the central axis of the nozzle, and does not separate from the inner wall of the nozzle. This reduces the entrapment of ambient air into the ambient flow immediately after the nozzle outlet. Thus, the oxygen purity can be maintained, and stable processing can be performed. In this embodiment, the channel area is gradually increased, but the same effect is obtained even if the channel area is constant.

Embodiment 9 FIG. FIG. 17 is a schematic vertical sectional view showing a processing head of a laser processing apparatus according to Embodiment 9 of the present invention.
In the present embodiment, the outermost wall of the multi-nozzle, that is, the wall of the auxiliary assist gas nozzle 2 has a truncated cone shape, and the virtual apex angle θ is 45 degrees or less. Thus, the amount of assist gas that stays between the laser beam nozzle and the surface of the workpiece can be reduced, and self-burning can be prevented. Also,
Ambient flow nozzle, that is, it is possible to suppress the amount of entrainment of the surrounding air immediately after the auxiliary assist gas nozzle is ejected,
Oxygen purity is maintained and stable processing can be performed.

Embodiment 10 FIG. Figure 18 is a partially broken schematic perspective view showing a machining head of the laser processing apparatus corresponding to claim 8 of Example 10 of the present invention. In this embodiment, the same (common) upstream of the nozzle
The assist gas (oxygen gas) supply source 10 is provided, and a portion for branching the gas from the assist gas supply source 10 to the auxiliary assist gas nozzle 2 is a main assist gas nozzle 1 at the center of the nozzle, that is, a main assist gas nozzle supply port 1c.
Has a structure in which an auxiliary assist gas supply port including a plurality of small holes 11 is provided in an annular portion around the. The assist gas (oxygen gas) passes through the small holes 11 and flows into the auxiliary assist gas nozzle duct 2b. In this embodiment, the central flow nozzle, that is, the main assist gas nozzle 1 depends on the set value of the area of the small holes 11 and the number of the small holes 11.
The flow rate of the main assist gas (oxygen gas) blown from the nozzle and the flow rate of the auxiliary assist gas (oxygen gas) blown from the surrounding flow nozzle, that is, the auxiliary assist gas nozzle 2 change. Therefore, by selecting an appropriate nozzle depending on the quality of the material to be processed, the plate thickness, etc., that is, a nozzle having an appropriate area and quantity of small holes 11, the desired main assist gas flow rate and auxiliary assist gas flow rate can be easily obtained. Is obtained.

The processing head nozzle according to the present embodiment exhibits a particularly great effect when cutting a thick plate. Normally, in the case of a mild steel plate that cuts using oxygen gas as an assist gas, the material temperature is lower at the lower part of the cutting groove, the viscosity of the oxide increases and the discharge rate decreases, and the combustion reaction is also suppressed, A delay occurs in the processing front surface, and the amount of the delay increases as the plate thickness increases. Therefore, in order to perform processing at high speed and stably, it is necessary to supply oxygen gas having a high flow rate to the delayed portion to discharge oxides and accelerate the oxidation reaction. The above conditions can be satisfied by appropriately setting the flow rate of the auxiliary assist gas nozzle using the processing head nozzle of the present embodiment.

FIG. 19 is a characteristic diagram showing the total pressure distribution in the direction along the groove of the gas discharged from the lower part of the groove when the gas is supplied into the cutting groove by using the processing head nozzle of this embodiment. . The horizontal axis is the distance x (mm) from the front of the groove, and the vertical axis is the total gas pressure P (kg / cm ² ) at the lower end of the groove. Thickness is 25 mm, the dimensions of the nozzle, the auxiliary assist-gas nozzle inside diameter D ₂ = 4 mm,
The main pressure gas nozzle has an inner diameter D ₁ = 1.5 mm, the inner diameter of the small holes 11 is 1 mm, and the total pressure when the number of the introduced small holes is 8 is a solid line characteristic curve. Shown by a curve. According to this, it can be seen that when the number of small holes is large, the flow rate and flow velocity of the auxiliary assist gas are large, and a high pressure can be obtained over a wide area under the groove corresponding to the delay portion under the groove.

Further, the graph of FIG. 20 shows the difference in the machining allowance with respect to the laser output and the machining speed due to the difference in the number of introduced small holes. The vertical axis is the processing speed (m / min), and the horizontal axis is the laser output
(kw). The material is SS400 having a plate thickness of 25 mm, and the dimensions of the nozzle are the same as in FIG. 19, ie, the auxiliary assist gas nozzle inner diameter D ₂ = 4 mm and the main assist gas nozzle inner diameter D ₁ = 1.5.
mm, the inner diameter of the small hole 11 is 1 mm, and the case where the number of introduced small holes is 8 and the case where the number of introduced small holes is 24 is shown in comparison. Area A
Is a good processing range when the number of introduced small holes is 8, and a good processing range when the region B is 24 introduced small holes. It turns out that it becomes possible. Actually, if the flow rate and flow rate of the assist gas are excessive, local self-burning occurs on the cut surface and the scratch is likely to occur, so that the appropriate flow rate and flow rate of the assist gas can realize high quality processing. A range exists.

FIG. 21 is a graph showing an appropriate total flow rate according to the thickness of the material to be processed at the time of cutting a thick plate. The abscissa represents the thickness of the workpiece (mm), and the ordinate represents the total flow rate N (l / min) of the assist gas. The range indicated by oblique lines is the range recommended for good cutting. Further, the graph of FIG. 22 shows an appropriate flow velocity of the main assist gas nozzle flow at the ejection port at the time of cutting a thick plate. The range indicated by hatching is the range recommended for good cutting.
Further, the graph of FIG. 23 shows an appropriate flow velocity of the auxiliary assist gas nozzle flow at the ejection port at the time of cutting a thick plate. The range indicated by hatching is the range recommended for good cutting. When the processing head nozzle according to the present invention is used, high-quality cutting without scratches and dross adhesion is possible within the range of the flow rate and the flow velocity shown in FIGS. According to FIGS. 21 to 23, a small hole diameter and a small hole number may be selected so as to realize a flow rate and a flow velocity suitable for the plate thickness.

The range of the number of small holes 11 necessary for realizing the flow rate and the flow velocity using the nozzle shown in this embodiment is as shown in the graph of FIG. The vertical axis is the number of small holes (pieces), and the horizontal axis is the plate thickness (mm). Various dimensions of the nozzle similar to FIG. 19, an auxiliary assist-gas nozzle inside diameter D ₂ = 4m
m, inner diameter of main assist gas nozzle D ₁ = 1.5 mm, small hole 11
1 mm inside diameter. Needless to say, if dimensions other than these conditions are selected so as to satisfy the flow rate / flow velocity conditions shown in FIGS. 21 to 23, high-quality cutting without scratches and dross can be performed.

FIG. 18 shows the case where the shape of the small hole 11 is circular. However, as shown in the schematic plan views showing the gas branch portion of the nozzle in FIGS. ,
It goes without saying that any shape has the same effect.

Embodiment 11 FIG. FIG. 26 is a partially cutaway perspective view showing a processing head of a laser processing apparatus according to a ninth embodiment of the present invention. In the tenth embodiment, a plurality of small holes 11 serving as auxiliary assist gas supply ports are provided in an annular portion around the main assist gas nozzle supply port 1c, and a gas inflow portion into the auxiliary assist gas nozzle 2 to adjust the flow path. However, in this embodiment, as shown in FIG. 25, a mesh-shaped fluid resistor 12 is disposed at the above-mentioned annular portion, thereby adjusting the flow rate of the auxiliary assist gas. The fluid resistor 12 may be a porous material. In this case, the gas flow flowing into the auxiliary assist gas nozzle 2 is uniform, and a stable flow with little disturbance can be realized by appropriately selecting a mesh or a porous material.

Embodiment 12 FIG. Figure 27 is a schematic longitudinal sectional view showing a processing head of a laser machining apparatus corresponding to claim 8 of Example 12 of the present invention. In this embodiment, an opening area adjusting means 13 is provided at the auxiliary assist gas supply port of the auxiliary assist gas nozzle 2, which is movable, and the opening area is changed manually or automatically by a driving device. With such a structure, the assist gas flow rate and the flow rate ratio between the main assist gas and the auxiliary assist gas can be adjusted without exchanging the nozzles, so that work efficiency can be improved.

Embodiment 13 FIG. FIG. 28 is a schematic plan view showing an opening area adjusting means in a processing head corresponding to claim 8 of Embodiment 13 of the present invention.
FIG. 4 is a view of a branch portion of a main assist gas flow and an auxiliary assist gas flow of a nozzle as viewed from an upstream side of a processing head. This embodiment shows a specific method of the opening area adjusting means 13 of the twelfth embodiment. An annular disk 14 having a small hole 15 similar to the annular portion is installed in contact with the annular portion having a plurality of small holes 11 of the supply port for guiding the assist gas to the auxiliary assist gas nozzle, and is connected to the annular disk 14. A knob 15 that can manually rotate the annular disk 14 is provided outside the nozzle. In this opening area adjusting means, which is constituted by an annular disk 14 having a small hole 15 and a knob 16, the small hole 11 provided in the nozzle and the small hole 15 provided on the annular disk 14 overlap. The portion serves as a gas inlet for guiding the assist gas to the auxiliary assist gas nozzle. Therefore, by rotating the annular disk 14,
By changing the gas inlet area, the assist gas flow rate to the auxiliary assist gas nozzle can be easily adjusted.

In this embodiment, the annular disk 14
Is manually operated by the knob 16 outside the nozzle, but needless to say, it may be automatically connected to a driving device.

Embodiment 14 FIG. FIG. 29 is a schematic plan view showing an opening area adjusting means in a processing head corresponding to claim 8 of Embodiment 14 of the present invention.
FIG. 4 is a view of a branch portion of a main assist gas flow and an auxiliary assist gas flow of a nozzle as viewed from an upstream side of a processing head. This embodiment shows another specific method of the opening area adjusting means 13 of the twelfth embodiment. A throttle mechanism 17 is provided in contact with the annular portion having a plurality of small holes 11 of the supply port for guiding the assist gas to the auxiliary assist gas nozzle, and is connected to the throttle mechanism 17 to manually adjust the degree of throttle from outside. Knob 16. Aperture mechanism 17 and knob 16
The aperture area adjusting means 13 is formed by adjusting the throttle mechanism 17, whereby the area of the supply port to the auxiliary assist gas is changed, and the supply gas flow rate can be adjusted.

In this embodiment, the aperture mechanism 17
Is manually operated by the knob 16 outside the nozzle, but needless to say, it may be automatically connected to a driving device.

Embodiment 15 FIG. FIG. 30 shows Embodiment 15 of the present invention.
FIG. 4 is a schematic vertical cross-sectional view showing a processing head of the laser processing apparatus of FIG. In this embodiment, gas (oxygen gas) supply sources for the main assist gas nozzle 1 and the auxiliary assist gas nozzle 2 are separately provided. With this configuration, oxygen can be supplied at an appropriate assist gas flow rate and an appropriate flow rate ratio between the main assist gas and the auxiliary assist gas.

Embodiment 16 FIG. FIG. 31 is a partially cutaway perspective view showing a laser processing nozzle corresponding to claim 12 of the sixteenth embodiment of the present invention. One assist gas supply port 30 is provided on the inner wall of the auxiliary assist gas nozzle 2.
The inside is divided by a plurality of partition walls 31 to form a small room 32. After the assist gas flows into the auxiliary assist gas nozzle 2 from the assist gas supply port 30, the partition wall 31
While reducing energy by the resistance of each small room 32
Distributed to Therefore, the flow velocity distribution in the circumferential direction at the auxiliary assist gas nozzle outlet is uniform, and it is possible to prevent the flow rate imbalance at the auxiliary assist gas outlet due to the uneven distribution of the assist gas supply port.

In this embodiment, the number of gas supply ports is one and the partition walls having the same dimensions are arranged axially symmetrically. However, the area and height of the partition walls depend on the position and number of the gas supply ports. By setting the interval, etc. individually for each partition,
The flow distribution at the outlet of the auxiliary assist gas nozzle can be freely set. For example, as shown in a partially cutaway perspective view of FIG. 32, the height of the partition wall near the gas supply port is reduced, and the height of the partition wall is increased as the distance from the gas supply port increases. By reducing the distance between the partition walls, the effect of homogenizing the outlet flow rate of the auxiliary assist gas nozzle flow is increased.

Embodiment 17 FIG. FIG. 33 (a) according to claim 11 of Example 17 of the present invention, 12
14 is a longitudinal sectional view showing a laser processing nozzle corresponding to FIGS. FIG. 2B is a cross-sectional view of the nozzle taken along line BB in FIG. A plurality of, in this case, four, assist gas supply ports 30 for the auxiliary assist gas nozzle 2 are provided radially on the inner wall of the auxiliary assist gas nozzle, and are divided into the same number of small chambers 32 by the partition walls 31 as the number of the assist gas supply ports 30 of the nozzle. ing. Each assist gas supply port 30 is connected to a separate assist gas supply source 18 as shown in the schematic diagram of FIG. 34, and the gas flow rate from each supply source 18 is controlled by a flow control device 20.
Is controlled by Alternatively, as shown in the schematic diagram of FIG. 35, each assist gas supply port 30 is connected to the same supply source 18.
Through a valve 33, and the opening and closing of the valve is performed by the operation control device 21.

According to this embodiment, by adjusting the flow rate of gas supplied to each small room, it is possible to freely adjust the assist gas flow rate distribution at the ejection port of the auxiliary assist gas nozzle flow. For example, as shown in the schematic explanatory view of FIG. 36, by supplying gas to the small chamber 32 located on the rear side in the processing progress direction, the flow velocity in the nozzle progress direction is large, and the flow velocity in the front direction is small. If it is adjusted to, the assist gas can easily enter the inside of the groove and a high pressure can be obtained up to the lower part of the groove. In addition, since there is a directional component of the flow velocity toward the front surface of the processing surface, the separation phenomenon of the gas flow at the front surface of the processing surface is suppressed, and the combustion reaction is promoted, thereby improving the processing quality.

In this embodiment, the embodiment in which the number of the small rooms 32 is four is shown. However, it goes without saying that the same effect can be obtained with four or more or less rooms. Needless to say, the same effect can be obtained even if the number of assist gas supply ports 30 to each small room 32 is two or more. Further, in the present embodiment, the gas supply to the gas supply port is the same supply source or separate supply sources, but a plurality of supply sources
Each may be connected to a plurality of gas supply ports.

Embodiment 18 FIG. FIGS. 37 (a) and 37 (b) show a laser processing nozzle corresponding to a fourteenth embodiment of the present invention, wherein FIG. 37 (a) is a partially cutaway perspective view, and FIG. FIG. A portion that contacts the downstream side surface of the annular partition wall provided with the small hole 11 of the auxiliary assist gas supply port and has a function of blocking a part of the small hole 11 of the auxiliary assist gas supply port and blocking the flow of the auxiliary assist gas is cut off. Chipped annular flat plate, in this case sector plate 35a
Is provided. Further, partition plates 35b are fixed to both ends of the fan-shaped plate 35a and are integrally formed. This partition plate 35b is the same as the partition wall 31 in the above-described Embodiments 16 and 17.
And a small room is formed inside the auxiliary assist gas nozzle 2. The fan-shaped plate 35a and the partition plate 35b are
It is formed so as to be rotatable with respect to the nozzle central axis. Further, a drive device 36 for driving the fan-shaped plate 35a and the partition plate 35b and a control device 37 for operating the drive device 36 are provided. The auxiliary assist gas is supplied to the partition plate 35b through the gas supply port 11 which is not shielded by the fan-shaped plate 35a.
Then, the air flows into the small room 32 formed by the inner wall of the auxiliary assist gas nozzle and the outer wall of the main assist gas nozzle 1, and is ejected from the outlet of the auxiliary assist gas nozzle. Therefore, by controlling the small room to be located behind the processing direction in accordance with the processing direction, the same effect as that of the seventeenth embodiment can be obtained.

Embodiment 19 FIG. FIG. 38 is a configuration diagram showing a laser processing apparatus corresponding to claim 16 of the nineteenth embodiment of the present invention. Using a processing head having a nozzle configuration shown in FIG. 30 having an assist gas (oxygen gas) supply source 18 separately, as shown in FIG. Detecting means, in this case, a sensor 19, and a flow control device 20 for adjusting the flow rate and pressure of the main assist gas and the auxiliary assist gas ejected from the nozzle in accordance with the information obtained from the sensor 19. Provided. Thereby, machining abnormalities are avoided, and more stable machining can be performed.

In this embodiment, a processing head having a nozzle configuration having a separate assist gas supply source was used. However, the same assist gas supply source was used.
It goes without saying that the same effect can be obtained even when the opening area adjusting means for the auxiliary assist gas supply port as shown in FIG. 14 is provided and applied to a processing head having a nozzle configuration for adjusting the main assist gas flow rate and the auxiliary assist gas flow rate. No.

Embodiment 20 FIG. FIG. 39 is a configuration diagram showing a laser processing apparatus corresponding to claim 16 of the twentieth embodiment of the present invention. A sensor 19 for predicting or detecting self-burning is provided. When a signal from the sensor 19 predicts or detects the occurrence of self-burning, the pressure and flow rate of at least one of the main assist gas and the auxiliary assist gas are reduced. It is controlled so as to make it. Thereby, the occurrence of burning is suppressed, and more stable processing can be performed.

Embodiment 21 FIG. FIG. 40 is a configuration diagram showing a laser processing apparatus corresponding to claim 17 of Embodiment 21 of the present invention. In this embodiment, the operation control device 21 of the laser processing device and the flow control device 20 of the assist gas supply source 18 are connected. As initial conditions for processing, for example, according to the type of material, processing speed conditions, and sheet thickness conditions, the operation control device 21 controls the gas flow rate and gas pressure of each of the main assist gas nozzle and the auxiliary assist gas nozzle by programming control. ing. Also, depending on the process being processed, for example,
Main assist during machining according to the angle at the time of piercing, linear cutting, obtuse corner cutting, curvature at the time of curve cutting, or diameter at the time of cutting such as circular, semicircular, elliptical shape etc. The gas flow rate and the gas pressure of the gas and the auxiliary assist gas are programmed and controlled by the operation control device 21. As a result, the labor for the operator to directly input the appropriate flow rate can be saved, the efficiency can be improved, and the processing quality can be stabilized and the reliability can be increased.

Embodiment 22 FIG. FIG. 41 is a configuration diagram showing another embodiment corresponding to claim 17 of Embodiment 21 of the present invention. In this embodiment, a gas supply source A18a of gas type A and a gas supply source B18b of gas type B are prepared as supply sources of the main assist gas and the auxiliary assist gas, and the inlets from these supply sources 18a, 18b to the processing head. Is provided with a switching valve 23, and the switching of the switching valve is controlled by the operation control device 21. With such a configuration, for example, at the time of piercing, at the time of straight line cutting, according to the angle at the time of cutting an obtuse angle, according to the curvature at the time of curve cutting,
Alternatively, depending on the diameter at the time of cutting, such as circular, semicircular, elliptical shapes, etc., the gas type of the main assist gas or auxiliary assist gas is switched from oxygen gas to nitrogen gas, for example, to suppress combustion and prevent self-burning Therefore, more stable processing can be performed. In this embodiment, an example in which there are two types of gas is shown, but it goes without saying that the apparatus may be configured to switch among three or more types.

Embodiment 23 FIG. FIG. 42 is a configuration diagram showing a laser processing apparatus corresponding to claim 18 of the twenty-second embodiment of the present invention. A thickness detecting means for detecting the thickness of the workpiece to be machined, in this case, a thickness measuring sensor 40 is installed in the machining head, and detects the thickness of the workpiece before machining and operates the operation control device. 21. An appropriate flow rate and flow rate according to the plate thickness of the main assist gas and the auxiliary assist gas output from the operation control device 21 are realized by the flow control device 20. This eliminates the need for the operator to set the gas pressure according to the plate thickness, and can provide an efficient and highly reliable processing apparatus. In this embodiment, the sheet thickness measuring sensor 40 is installed on the processing head. However, it goes without saying that the sheet thickness measuring sensor 40 may be installed anywhere as long as the sheet thickness can be measured.

Embodiment 24 FIG. FIG. 43 shows Embodiment 24 of the present invention.
FIG. 4 is a schematic vertical cross-sectional view showing a processing head of the laser processing apparatus of FIG. In this embodiment, the main assist gas nozzle 1,
The auxiliary assist gas nozzles 2 are separately formed, and have a structure in which an inner wall of the auxiliary assist gas nozzle 2 has a locking portion for fixing and locking the main assist gas nozzle 1, in this case, a projection 22. Thereby, each nozzle becomes detachable, for example, a small hole area serving as an assist gas supply port,
It is possible to freely select a combination of nozzles having different conditions such as the number and the like, and select an appropriate flow rate and an appropriate flow rate ratio of the main assist gas nozzle 1 and the auxiliary assist gas nozzle 2 depending on the material, the plate thickness, and the like.

In the above-described embodiment, the case of the nozzle having the double ring structure has been described. However, the same applies to the multiple ring nozzle. The nozzles are separately formed, and the inner wall of each nozzle is formed by the inner nozzle. What is necessary is just to provide the locking part which fixes and locks, and the same effect is produced. Also,
The locking portion for locking and fixing the nozzle to the outer nozzle inner wall may not be a protrusion, and may be a step 22a as shown in a schematic vertical sectional view of FIG. 44 (a) or a schematic vertical sectional view of FIG. 44 (b). As shown in the figure, the tapered portion 22b may be used.

Embodiment 25 FIG. FIG. 45 shows Embodiment 25 of the present invention.
FIG. 4 is a schematic vertical cross-sectional view showing a processing head of the laser processing apparatus of FIG. In this embodiment, the main assist gas nozzle 1 and the auxiliary assist gas nozzle 2 are not made of the same material, the main assist gas nozzle 1 is made of a metal (for example, brass) which is easy to process, and the auxiliary assist gas nozzle 2 at the outermost periphery has a high melting point. It is formed of a high hardness metal. In this case, in the outer peripheral portion, when high-temperature oxide or molten metal generated at the time of cutting is scattered, it is not easily damaged by sputtering or the like, and serves to protect the internal nozzle,
The life of the nozzle is improved.

Although the laser cutting has been described in the above embodiment, it goes without saying that the same effect can be obtained for laser welding having the same structure as a laser processing apparatus.

Further, the laser processing apparatus and the processing head of the present invention are not limited to the above-mentioned embodiment, and various configurations and forms can be considered. For example, in the processing head, the position of the ejection port of the main assist gas nozzle and the position of the ejection port of the auxiliary assist gas nozzle are the same, and a swirl flow forming means is provided, and a swirl flow forming means and a static pressure conversion means are provided. Well,
A similar effect is achieved. Workpiece (material type, plate thickness),
Depending on processing conditions such as drilling and cutting, processing applications, and the like, various types of processing heads and processing apparatuses that employ various means according to the processing conditions are used.

[0096]

Since the present invention is configured as described above, it has the following effects.

[0097] The main assist-gas nozzle laser beam passes is provided in the central portion of the laser beam nozzle, the annular auxiliary assist gas nozzles surrounding the main assist-gas nozzle singlet least provided Ri Na, to the workpiece from the both nozzles
In the machining head ejecting an assist gas toward,
Main assist at the outlet of the main assist gas nozzle
The gas flow rate to the auxiliary assist gas nozzle
Larger than the flow velocity of the auxiliary assist gas in the auxiliary assist gas nozzle, the inner diameter of the innermost ejection port of the auxiliary assist gas nozzle is larger than or equal to the inner diameter of the ejection port of the main assist gas nozzle, the position of the ejection port of the main assist gas nozzle The auxiliary assist gas nozzle is provided on the upstream side of the gas flow from at least one of the ejection ports, and the outer wall of the main assist gas nozzle is formed such that the thickness of the tip portion gradually decreases toward the downstream side of the gas flow. With this configuration, the main assist gas flow can sufficiently secure the distance between the ejection port and the processing surface, so that turbulence develops sufficiently downstream and a large flow velocity fluctuation can be obtained near the processing surface. On the other hand, the auxiliary assist gas flow flows along the outer wall surface where the thickness of the tip portion of the main assist gas nozzle gradually decreases, and in the vicinity of the tip portion of the main assist gas nozzle, the flow direction with the main assist gas flow is almost the same. Smooth contact with the main assist gas flow without causing large-scale turbulence due to flow separation at the gas nozzle tip, flows downstream while maintaining the speed difference with the main assist gas flow, and main assist at the auxiliary assist gas jet Form a continuous flow distribution with the gas flow. In this way, a large flow rate fluctuation of the main assist gas flow is obtained near the processing surface ,
In addition, since the assist assist gas flow forms a continuous flow velocity distribution with the main assist gas flow at the outlet, the entire gas flow is not disturbed, and the amount of entrained ambient air is small, high-purity assist with large turbulence Since gas can be supplied to the processing surface and the oxidation reaction is promoted, stable processing can be performed,
Processing quality and processing speed can be improved.

By providing a swirl flow forming means for swirling at least a part of the main assist gas flow blown out from the main assist gas nozzle jet, a swirl flow is generated in the gas flowing inside the main assist gas nozzle, and the swirl flow is generated on the central axis. The turbulence of the main assist gas flow can be increased, and the pressure fluctuation and the flow velocity fluctuation of the main assist gas flow can be increased.

[0099]

[0100]

In addition, a swirling flow can be easily formed with a simple configuration in which a spirally twisted stationary blade or groove is provided on the inner wall surface of the main assist gas nozzle.

Further, a nozzle port is provided on the inner wall surface of the main assist gas nozzle, and a main assist gas sub-flow nozzle for jetting gas in parallel with the circumferential direction of the main assist gas nozzle is provided.
Thus, the swirling flow can be easily formed by ejecting the main assist gas.

Further, by providing static pressure converting means for converting the dynamic pressure of the auxiliary assist gas flow flowing from the auxiliary assist gas supply port into the auxiliary assist gas nozzle into a static pressure, the gas guided into the auxiliary assist gas nozzle is provided. To restore the static pressure of
The flow velocity fluctuation can be reduced to prevent the entrainment of external air, the oxygen purity is maintained, and stable processing can be performed.

Further, a static pressure conversion surface is provided to face the auxiliary assist gas flow flowing from the auxiliary assist gas supply port, and a return wall forming a gas retaining space is protruded from an end of the static pressure conversion surface. Since the gas introduced into this space can be recovered by static pressure and rectified, the outer flow can be further stabilized, air entrapment can be prevented, oxygen purity can be maintained, and stable processing can be performed. .

Further, an auxiliary assist gas nozzle supply port capable of adjusting the flow rate of the auxiliary assist gas is provided around the main assist gas nozzle supply port, and both supply ports are connected to the same gas supply source. And the auxiliary assist gas are branched, for example, by appropriately setting the area and quantity of the small holes of the auxiliary assist gas nozzle supply port, the main assist gas flow rate and the auxiliary assist gas flow rate are set to appropriate values. Can be set.

Since the auxiliary assist gas nozzle supply port is provided with an opening area adjusting means for adjusting the opening area thereof, the flow rate and the pressure of the main assist gas and the auxiliary assist gas can be individually or automatically adjusted manually. Adjustment can be easily performed, and the appropriate flow rate and flow rate ratio can be controlled according to the processing conditions.

Further, a flow path resistor made of, for example, a mesh or a porous material is provided at the auxiliary assist gas nozzle supply port, and the flow rate of the auxiliary assist gas can be easily adjusted by appropriately setting the flow path resistor. In addition, the flow of the assist gas is made more uniform,
Entrapment of external air can be prevented, and stable processing can be performed.

Since means for adjusting the flow velocity distribution at the auxiliary assist gas nozzle ejection port are provided, for example, the flow velocity distribution and flow rate of the gas can be changed in front and rear in the processing progress direction. Gas can be supplied effectively.

In addition, since a plurality of gas supply ports for the auxiliary assist gas nozzle are provided at least on the inner wall of the auxiliary assist gas nozzle, or the inside of the auxiliary assist gas nozzle is divided into small chambers in the radial direction by partition walls, ie, the position of the gas supply port By appropriately setting the number, the size, the position, and the number of the partition walls, the assist gas flow distribution at the auxiliary assist gas nozzle ejection port can be freely set.

Further, since means for individually adjusting the flow rate of the supply gas into each small room is provided, the outlet flow rate distribution of the auxiliary assist gas nozzle can be freely controlled according to the processing conditions, so that the gas supply is efficient. The processing speed and processing quality are improved.

Further, an auxiliary assist gas supply port is formed, an annular partition partitioning the inside of the auxiliary assist gas nozzle in the axial direction, provided rotatably in contact with the downstream side surface of the annular partition, and a part of the gas supply port. An annular flat plate partially shielded, attached to both ends of this flat plate, radially partitions the inside of the auxiliary assist gas nozzle downstream of the annular partition wall, and rotates in conjunction with the flat plate By providing a partition plate, a driving device for driving the flat plate, and a control device for operating the driving device, the outlet flow distribution of the auxiliary assist gas nozzle can be freely controlled according to processing conditions,
Gas supply is performed efficiently, and processing speed and processing quality are improved.

In the processing apparatus using the processing head, the entire gas flow is not disturbed,
Air with a small amount of air entrapment and high purity and large turbulence
As a result of supplying cyst gas to the processing surface, stable and accurate
Can be processed. Further, information processing means for detecting information such as the temperature of the surface of the workpiece, the width of the cutting groove, and the amount of spark light during the processing is provided, and the assist gas ejected from the processing head according to the output of the information detecting means is provided. Since the gas type, flow rate or pressure is adjusted, abnormal processing can be avoided.

Further, an operation control device is provided, and the kind, flow rate or pressure of the assist gas ejected from the processing head is programmed and controlled by the operation control device according to the processing conditions, so that the operation control device is more stable. Processing can be performed.

Further, a thickness measuring means for detecting the thickness of the workpiece is provided, and the flow rate or pressure of the assist gas ejected from the machining head is controlled by the operation control device according to the output of the thickness measuring means. Since the control is performed, the operator does not need to set the gas flow rate and the like according to the plate thickness, so that work efficiency is improved and processing reliability is increased.

[Brief description of the drawings]

FIG. 1 is a schematic vertical sectional view showing a processing head of a laser processing apparatus according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a pressure fluctuation distribution of an assist gas flow on a cutting plate surface according to the first embodiment of the present invention.

FIG. 3 is a schematic explanatory view for explaining the principle of improving cutting characteristics according to the first embodiment of the present invention.

FIG. 4 is an explanatory diagram showing a flow velocity distribution on the surface of a cutting plate according to the first embodiment of the present invention.

FIG. 5 is a characteristic diagram showing a relationship between a pressure fluctuation value of an assist gas flow and cut surface roughness according to the present invention.

FIG. 6 is a graph showing a margin of a processing speed with respect to a laser power according to the first embodiment of the present invention, together with a comparative conventional example.

FIG. 7 is a schematic vertical sectional view showing a positional relationship of a jet port in the processing head according to the first embodiment of the present invention.

FIG. 8 is a characteristic diagram illustrating a relationship between a pressure fluctuation value of an assist gas flow and a distance between injection ports according to the first embodiment of the present invention.

FIG. 9 is a schematic longitudinal sectional view showing a processing head corresponding to claim 1 of a second embodiment of the present invention.

FIG. 10 is a perspective view showing a processing head corresponding to claim 2 of the third embodiment of the present invention as seen through the inside;

FIG. 11 is a perspective view showing a main assist gas nozzle of a processing head according to a third embodiment of the present invention.

FIG. 12 is a top view showing a main assist gas nozzle of a processing head according to a fourth embodiment of the present invention.

FIG. 13 is a schematic longitudinal sectional view showing a processing head corresponding to claim 5 of Embodiment 6 of the present invention.

FIG. 14 is a schematic longitudinal sectional view showing a processing head corresponding to claim 6 of the seventh embodiment of the present invention.

FIG. 15 is a characteristic diagram showing a comparison between pressure fluctuation values of an assist gas flow on a cutting plate surface in Examples 6 and 7 of the present invention and a conventional example.

FIG. 16 is a schematic longitudinal sectional view showing a working head according to an eighth embodiment of the present invention.

FIG. 17 is a schematic longitudinal sectional view showing a working head according to a ninth embodiment of the present invention.

FIG. 18 is a partially broken schematic perspective view showing a processing head corresponding to an eighth embodiment of the present invention.

FIG. 19 is a characteristic diagram showing a difference in a total pressure distribution at a gas discharge portion below a groove depending on the number of small holes for introducing auxiliary assist gas according to the tenth embodiment of the present invention.

FIG. 20 is a graph showing a difference in machining allowance according to the number of small holes for introducing auxiliary assist gas according to the tenth embodiment of the present invention.

FIG. 21 is a graph showing an appropriate total flow rate of an assist gas with respect to a plate thickness of a workpiece according to the present invention.

FIG. 22 is a graph showing an appropriate flow rate of a main assist gas nozzle flow with respect to a plate thickness of a workpiece according to the present invention.

FIG. 23 is a graph showing an appropriate flow rate of an auxiliary assist gas nozzle flow with respect to a plate thickness of a workpiece according to the present invention.

FIG. 24 is a graph showing an example of an appropriate number of small holes of a processing nozzle according to Embodiment 10 of the present invention in relation to a plate thickness.

FIG. 25 is a schematic plan view showing another example of the shape of the small hole serving as the auxiliary assist gas supply port according to the tenth embodiment of the present invention.

FIG. 26 is a partially cut-away schematic perspective view showing a working head corresponding to claim 9 of the eleventh embodiment of the present invention.

FIG. 27 is a schematic longitudinal sectional view showing a processing head corresponding to claim 8 of the twelfth embodiment of the present invention.

FIG. 28 is a schematic plan view showing an opening area adjusting means in a processing head corresponding to claim 8 of Embodiment 13 of the present invention.

FIG. 29 is a schematic plan view showing an opening area adjusting means in a processing head corresponding to claim 8 of Embodiment 14 of the present invention.

FIG. 30 is a schematic longitudinal sectional view showing a processing head of a laser processing apparatus according to Embodiment 15 of the present invention.

FIG. 31 is a partially broken schematic perspective view showing a working head corresponding to claim 12 of the sixteenth embodiment of the present invention.

FIG. 32 is a partially broken schematic perspective view showing another example of the working head of Embodiment 16 of the present invention.

FIG. 33 is a sectional view showing a processing head corresponding to claims 11 to 13 of Embodiment 17 of the present invention;

FIG. 34 is a schematic diagram illustrating an example of an assist gas supply unit to a processing head according to Embodiment 17 of the present invention.

FIG. 35 is a schematic view showing another example of the means for supplying assist gas to the processing head according to Example 17 of the present invention.

FIG. 36 is a schematic explanatory diagram showing a gas supply state in a gas flow control example using a processing head according to Embodiment 17 of the present invention.

FIG. 37 is a partially broken schematic perspective view showing a working head corresponding to claim 14 of the eighteenth embodiment of the present invention.

FIG. 38 is a configuration diagram showing a laser processing apparatus corresponding to claim 16 of the nineteenth embodiment of the present invention.

FIG. 39 is a configuration diagram showing another example of the laser processing apparatus corresponding to claim 16 of Embodiment 20 of the present invention.

FIG. 40 is a configuration diagram showing a laser processing apparatus corresponding to claim 17 of Embodiment 21 of the present invention.

FIG. 41 is a schematic diagram showing a configuration of a laser processing apparatus corresponding to claim 17 of Embodiment 22 of the present invention.

42 is a schematic diagram showing a configuration of a laser machining apparatus corresponding to claim 18 of Example 23 of the present invention.

FIG. 43 is a schematic longitudinal sectional view showing a processing head of a laser processing apparatus according to Example 24 of the present invention.

FIG. 44 is a schematic longitudinal sectional view showing another example of the processing head of the laser processing apparatus according to Example 24 of the present invention.

FIG. 45 is a schematic longitudinal sectional view showing a processing head of a laser processing apparatus according to Embodiment 25 of the present invention.

FIG. 46 is a schematic longitudinal sectional view showing a processing head of a conventional laser processing apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Main assist gas nozzle, 1a Main assist gas nozzle ejection port, 1c Main assist gas nozzle supply port, 2 Auxiliary assist gas nozzle, 2a Auxiliary assist gas nozzle supply port, 2c Auxiliary assist gas nozzle supply port, 3 Cutting board surface of workpiece, 4 Stationary blade 5 spiral groove, 6 main assist gas side flow nozzle, 7 static pressure conversion surface, 8 return wall surface, 10, 18, 18a, 18b assist gas supply source, 11 small hole of auxiliary assist gas nozzle supply port, 12
Fluid resistor, 13 opening area adjusting means, 14 annular disk forming opening area adjusting means, 15 small hole of annular disk, 17 throttle mechanism forming opening area adjusting means, 19
Sensor for information detection means, 21 Operation control device, 30
Assist gas supply port, 31 partition, 32 small room, 3
3 valves, 35a fan-shaped plate, 35b partition plate, 36 drive unit, 37 control unit, 40 plate thickness measurement sensor.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yu Kanaoka 5-1-1, Yadaminami, Higashi-ku, Nagoya-shi Nagoya Works, Mitsubishi Electric Corporation (72) Inventor Atsushi Murai 5-1-1, Yadaminami, Higashi-ku, Nagoya No. Mitsubishi Electric Corporation Nagoya Works (56) References JP-A-57-130791 (JP, A) JP-A-63-171290 (JP, A) JP-A-64-87713 (JP, A) 60-255295 (JP, A) JP-A-2-263585 (JP, A) JP-A-58-185383 (JP, U) JP-A-62-199286 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) B23K 26/00-26/14

Claims (18)

(57) [Claims] 1. A main assist gas nozzle through which a laser beam passes is provided at a central portion of a laser beam nozzle, and at least one annular auxiliary assist gas nozzle surrounding the main assist gas nozzle is provided. In the processing head that ejects the assist gas toward the auxiliary assist gas nozzle, the flow rate of the main assist gas at the ejection port of the main assist gas nozzle is set to be larger than the flow rate of the auxiliary assist gas at the ejection port of the auxiliary assist gas nozzle. The inner diameter of the inner outlet is larger than or equal to the inner diameter of the outlet of the main assist gas nozzle, and the position of the outlet of the main assist gas nozzle is upstream of the gas flow from at least one of the outlets of the auxiliary assist gas nozzle. Side of the main assist gas nozzle A processing head characterized in that the outer wall is configured such that the thickness of the tip portion gradually decreases toward the downstream side of the gas flow. 2. The processing head according to claim 1, further comprising a swirling flow forming means for turning at least a part of the main assist gas flow blown out from the main assist gas nozzle jet port into a swirling flow. 3. The processing head according to claim 2, wherein the swirling flow forming means is a spirally twisted stationary blade or groove provided on the inner wall surface of the main assist gas nozzle. 4. The swirling flow forming means according to claim 2, wherein a nozzle opening is provided on an inner wall surface of the main assist gas nozzle, and the swirl flow forming means comprises a main assist gas sub-flow nozzle which jets gas in parallel with the circumferential direction of the main assist gas nozzle. The processing head to be characterized. 5. A static pressure conversion means for converting a dynamic pressure of an auxiliary assist gas flow flowing from an auxiliary assist gas supply port into a static pressure is provided in the auxiliary assist gas nozzle. 3. The processing head according to 2. 6. A static pressure conversion surface is provided so as to face an auxiliary assist gas flow flowing from an auxiliary assist gas supply port, and a return wall surface forming a gas retaining space is protruded from an end of the static pressure conversion surface. The processing head according to claim 5, wherein: 7. An auxiliary assist gas nozzle supply port capable of adjusting the flow rate of the auxiliary assist gas is provided around the main assist gas nozzle supply port, and both supply ports are connected to the same gas supply source. The processing head according to claim 1. 8. The processing head according to claim 7, wherein an opening area adjusting means for adjusting an opening area of the auxiliary assist gas nozzle supply port is provided. 9. The processing head according to claim 7, wherein a fluid resistor is provided at the auxiliary assist gas nozzle supply port. 10. The processing head according to claim 1, further comprising means for adjusting a flow velocity distribution at an auxiliary assist gas nozzle ejection port. Especially 11. providing a plurality of gas supply ports to the auxiliary assist-gas nozzle to the auxiliary assist-gas nozzle inner wall
11. The processing head according to claim 10, wherein the flow velocity distribution at the auxiliary assist gas nozzle ejection port is adjusted. 12. A partition inside the auxiliary assist gas nozzle.
By dividing into small rooms in the radial direction,
Adjusted the flow velocity distribution at the gas nozzle nozzle
The processing head according to claim 10, wherein: 13. A flow rate of a supply gas into a divided small room.
Characterized by having means for individually adjusting the
12. The processing head according to item 12 . 14. An auxiliary assist gas supply port is formed,
An annular partition partitioning the inside of the auxiliary assist gas nozzle in the axial direction,
It is provided rotatably in contact with the downstream side surface of this annular partition,
Partially cut out annular part that shields part of the above gas supply port
Flat plate, attached to both ends of this flat plate,
Partition the downstream auxiliary assist gas nozzle in the radial direction, and
Two partition plates that rotate in conjunction with the plate,
Driving device and a control device for operating the driving device
11. The processing head according to claim 10, wherein
De. 15. according to any one of claims 1 to 14
Laser processing device equipped with a processing head . 16. The temperature of the surface of the workpiece during processing,
An information detecting means for detecting information such as the width and the amount of spark
Injection from the processing head according to the output of the information detection means
Adjust the gas type, flow rate or pressure of the assist gas to be output.
The laser processing apparatus according to claim 15, wherein the laser processing apparatus is adjusted . 17. An operation control device, comprising :
Check the gas type, flow rate or pressure of the assist gas
Programming control by the above operation controller
The laser processing device according to claim 15, wherein 18. A hand for measuring a thickness of a workpiece to detect the thickness of the workpiece.
It has a step, and according to the output of the thickness measuring means,
To control the flow rate or pressure of the assist gas
Characterized by being controlled by a rotation control device
The laser processing device according to claim 17 .