JP7632345B2 - Laser Processing Equipment - Google Patents

Description

The present invention relates to a laser processing device that injects assist gas onto the workpiece to remove debris and cool the processing area.

For example, laser processing devices are known for cutting, drilling, welding, and surface marking of workpieces such as metals. This type of laser processing device includes a laser oscillator, an optical system, a processing head, etc., and guides the laser light output from the laser oscillator to the processing head via the optical system and irradiates the workpiece from the nozzle opening. At the same time, assist gas is sprayed from the nozzle opening of the processing head coaxially with the laser light to remove debris and cool the processed area (see, for example, Patent Document 1).

Incidentally, some laser processing devices, which perform marking or groove processing on workpieces, are equipped with a large-area optical system, for example, 20φ or more, which combines a galvanometer scanner and an fθ lens in the optical system. In this case, the opening diameter of the nozzle port at the tip of the processing head is also large, making it difficult to increase the flow rate of the assist gas sufficiently. For this reason, Patent Document 1 employs a so-called double nozzle at the tip of the nozzle, in which a separate port for gas ejection is provided around the port from which the laser light is output.

Japanese Patent Application Publication No. 7-223086

However, as described above, when a double nozzle is provided, the nozzle configuration becomes complex, and a negative pressure region is formed inside the nozzle due to the assist gas ejected at high speed. The formation of this negative pressure region generates an updraft from the processing point to the center of the nozzle injection, which can cause debris and other ejected material to be drawn into the nozzle. This ejection can cause problems such as damage to optical components and attenuation of laser output. There is also the problem of uneven flow speed at each injection position. Some systems inject auxiliary assist gas from the side around the main assist gas in addition to the main assist gas, but this leads to a decrease in processing quality compared to when assist gas is ejected at high speed coaxially with the laser light.

The present invention was made in consideration of the above circumstances, and its purpose is to provide a laser processing device that is capable of supplying assist gas at high speed with a simple configuration, even when the device is equipped with a large-area optical system and has a relatively large nozzle opening.

In order to achieve the above object, the laser processing device (1) of the present invention irradiates laser light (L) from a laser oscillator (2) through an optical system (4) from a nozzle opening (10) at the tip of a processing head (3), and injects assist gas (A) from the nozzle opening coaxially with the laser light by an assist gas supply mechanism (5). The processing head has a nozzle section (9) at the tip side whose inner wall section narrows toward the nozzle opening, and has an airtight gas purge area (11) at the base end side that opens toward the nozzle section, and is equipped with a slit-shaped nozzle (13) located at the base end of the nozzle section and flows gas at high speed along the inner wall surface of the nozzle section toward the nozzle opening. The assist gas supply mechanism includes a first gas supply section (12) that supplies a first assist gas to the gas purge area under positive pressure, and a second gas supply section (15) that supplies a second assist gas to the nozzle opening.

According to the above configuration, the laser light is irradiated from the laser oscillator through the optical system to the workpiece through the nozzle opening at the tip of the processing head. At the same time, the assist gas supply mechanism ejects assist gas from the nozzle opening coaxially with the laser light. At this time, the second assist gas supplied at relatively high pressure by the second gas supply unit of the assist gas supply mechanism is ejected at high speed from the slit-shaped outlet at the base end of the nozzle unit along the inner wall surface of the nozzle unit toward the nozzle opening. In addition, the first assist gas is supplied at positive pressure to the gas purge area by the first gas supply unit.

Here, when a large-area optical system is provided, the opening diameter of the nozzle port is also large, but the second assist gas flows at high speed through the inner part of the nozzle port near the outer periphery, causing the inner part to become negative pressure, and drawing in the first assist gas in the gas purge area that is connected to the nozzle part. By maintaining the first assist gas in the gas purge area at positive pressure, the first assist gas can be actively introduced into the negative pressure area. As a result, the assist gas in a state in which the first and second assist gases are mixed is ejected from the nozzle port at a relatively high speed coaxially with the laser light. This makes it possible to eliminate the unstable negative pressure area inside the nozzle while actively drawing in the first assist gas for stable ejection. As a result, the gas flow rate inside the nozzle is made uniform, and the above-mentioned problems associated with the formation of the negative pressure area can be eliminated. Therefore, even if a large-area optical system is provided and the nozzle port is relatively large, it is possible to supply high-speed assist gas with a simple configuration, and thus high-quality laser processing is possible.

FIG. 1 is a diagram showing an embodiment of a laser processing apparatus. Diagram showing the processing head part FIG. 3 is a cross-sectional view showing an internal configuration of the processing head;

(One embodiment)
An embodiment will be described below with reference to the drawings. In this embodiment, a specific example will be described in which a surface marking process is performed on a workpiece W made of, for example, a metal plate. FIG. 1 shows a schematic overall configuration of a laser processing device 1 according to this embodiment. This laser processing device 1 includes a known laser oscillator 2, a processing head 3, and an optical system 4 that guides a laser beam output from the laser oscillator 2 to the processing head 3. In addition, the laser processing device 1 includes an assist gas supply mechanism 5 that injects an assist gas G onto the workpiece W. Although not shown, a movement mechanism for moving the processing head 3 relative to the workpiece W is also provided.

The optical system 4 is equipped with a mirror 4a for bending the optical path of the laser light L, and is equipped with a galvanometer scanner 6 and an fθ lens 7 located at the upper part, which is the base end side, of the processing head 3. This makes the optical system 4 a large-area optical system. Note that a large-area optical system refers to an optical system in which the lens diameter is, for example, 20 mmφ or more. The galvanometer scanner 6 is controlled by a control device 8 that includes a computer. The control device 8 is also configured to control the entire laser processing device 1.

The processing head 3 will now be described in detail with reference to Figures 2 and 3. As shown in Figure 2, the processing head 3 has, for example, a cylindrical body 3a, and the galvanometer scanner 6 and fθ lens 7 constituting the optical system 4 described above are incorporated in the upper part of the body 3a. A nozzle section 9 is provided at the lower end, which is the tip part of the body 3a. A nozzle opening 10 for spraying the laser light L and the assist gas G is provided at the bottom part of the nozzle section 9. In this case, the nozzle opening 10 is also configured to be relatively large, for example with a diameter of 8 mmφ or more, in order to scan the laser light L.

Now, as shown in Figures 2 and 3, a gas purge area 11 is provided between the fθ lens 7 and the nozzle portion 9 in the body 3. This gas purge area 11 opens to the nozzle portion 9 side and has one or more supply ports 11a in its peripheral wall, and is configured to be airtight so that gas does not leak to any side other than the nozzle portion 9 side. As shown in Figure 1, the supply port 11a of this gas purge area 11 is connected to a first gas supply unit 12, and a first assist gas is supplied from the first gas supply unit 12 at positive pressure. As the first assist gas, an inert gas such as helium gas or argon gas is used.

As shown in FIG. 3, the nozzle portion 9 has an inner wall surface that tapers from the upper end toward the nozzle port 10 in the figure, in this case a tapered surface. The upper end of the nozzle portion 9 opens in a circular shape so as to communicate with the gas purge area 11. The nozzle portion 9 is provided with a slit-shaped nozzle 13 located on the base end side, i.e., near the upper portion, around the entire circumference for flowing the second assist gas at high speed into the nozzle portion 9. The nozzle 13 is provided facing downward along the taper of the inner wall surface of the nozzle portion 9, and communicates with supply ports 14 provided, for example, at two locations on the left and right ends in the figure.

As shown in FIG. 3, the nozzle portion 9 is constructed by butting together two parts 9a, 9b in the axial direction, i.e., in the vertical direction, and the nozzle 13 and supply port 14 are formed at the butted portion. As shown in FIG. 1, the two supply ports 14 are connected to a second gas supply unit 15, and a second assist gas is supplied from the second gas supply unit 15 at a high pressure, for example, a pressure of 0.1 MPa or more. As the second assist gas, an inert gas of a different type from the first assist gas, for example, nitrogen gas, is used.

The second assist gas is then supplied at high pressure from the second gas supply unit 15 to the supply port 14 and ejected from the slit-shaped nozzle 13 downward, i.e., in the direction of arrow A2 in FIG. 3, at high speed. The second assist gas flows at high speed along the inner wall surface of the nozzle unit 9 and is ejected from the nozzle port 10 toward the processing position of the workpiece W. The gas purge area 11, first gas supply unit 12, nozzle 13, second gas supply unit 15, etc. constitute the assist gas supply mechanism 5. Although not shown in detail, the laser oscillator 2, first gas supply unit 12, and second gas supply unit 15 are also controlled by the control device 8.

Next, the operation of the laser processing device 1 configured as described above will be described. When performing surface marking processing on the workpiece W in the laser processing device 1, the control device 8 drives the laser oscillator 2 and controls the galvanometer scanner 6. As a result, as shown in FIG. 1, the laser light L output from the laser oscillator 2 is irradiated onto the workpiece W from the nozzle opening 10 of the processing head 3 through the optical system 4, and a predetermined marking is performed. At the same time, the control device 8 drives and controls the first gas supply unit 12 and the second gas supply unit 15, and the assist gas supply mechanism 5 sprays assist gas A from the nozzle opening 10 coaxially with the laser light L.

As a result, assist gas A is sprayed onto the processed portion of the workpiece W, discharging any debris that has been generated and cooling the processed portion of the workpiece W. Specifically, as shown in FIG. 3, the second assist gas supplied at relatively high pressure to the supply port 14 of the processing head 3 by the second gas supply unit 15 flows at high speed from the slit-shaped outlet 13 of the nozzle unit 9 along the inner wall surface of the nozzle unit 9 in the direction of arrow A2, and is sprayed downward at high speed from the nozzle port 10. At the same time, the first assist gas is supplied at positive pressure from the first gas supply unit 12 to the gas purge area 11 in the processing head 3.

Here, when a large-area optical system 4 such as a galvanometer scanner 6 and an fθ lens 7 is provided, the opening diameter of the nozzle orifice 10 also becomes large. However, as shown in FIG. 3, the second assist gas flows at high speed in the direction of arrow A2 in the inner part of the nozzle orifice 10 near the outer periphery, creating a negative pressure in the inner part, and the first assist gas in the gas purge area 11 that is connected to the nozzle part 9 is drawn in the direction of arrow A1. Since the first assist gas in the gas purge area 11 is maintained at positive pressure, the first assist gas can be actively introduced into the negative pressure region.

As a result, assist gas A, a mixture of the first and second assist gases, is ejected from the nozzle opening 10 at a relatively high speed coaxially with the laser light L, and is sprayed at high speed onto the machined portion of the workpiece W. Therefore, the assist gas A effectively removes debris and cools the machined portion. In this case, stable ejection is possible by actively drawing in the first assist gas while eliminating the unstable negative pressure region inside the nozzle portion 9. As a result, the gas flow speed inside the nozzle portion 9 is made uniform, and problems such as the entrainment of ejected material such as debris into the inside of the nozzle portion 9 due to the formation of a negative pressure region can be eliminated.

According to this embodiment, the processing head 3 is provided with an airtight gas purge area 11 that opens onto the nozzle portion 9 side, and the first assist gas is supplied under positive pressure, while the second assist gas is caused to flow at high speed from a slit-shaped nozzle 13 provided in the nozzle portion 9 along the inner wall surface of the nozzle portion 9 toward the nozzle opening 10. This makes it possible to supply high-speed assist gas A with a simple configuration even in a case where the nozzle opening 10 is relatively large and equipped with a large-area optical system 4, thereby achieving the excellent effect of enabling high-quality laser processing.

In particular, in this embodiment, the nozzle portion 9 is configured such that the two parts 9a and 9b that make up the nozzle portion 9 are butted together to form the slit-shaped outlet 13. This makes it easy to form the slit-shaped outlet 13, and by replacing the parts 9a and 9b, it becomes possible to easily change the shape and gap dimensions of the outlet 13. In addition, by replacing the part 9b, it is also easy to change the shape of the inner wall surface of the nozzle portion 9, such as the taper angle. Adjusting the slit width of the outlet also makes it easy to adjust the flow rate of the assist gas.

In addition, in this embodiment, the first gas supply unit 12 and the second gas supply unit 15 are configured to be able to supply different types of assist gas. This configuration allows the first assist gas and the second assist gas to be used separately. In this embodiment, for example, relatively inexpensive nitrogen gas is used as the second assist gas, which is used more frequently, and helium gas, which is relatively expensive but has a high cooling effect, is used as the first assist gas. This makes it possible to perform high-quality processing while suppressing the overall cost of the assist gas.

Other Embodiments
Below, several other embodiments will be described, although illustrations are omitted. In the above embodiment, the first assist gas and the second assist gas are different types of gas, but the first gas supply unit and the second gas supply unit can be configured to supply the same type of gas. In this way, only one type of assist gas is required, and the configuration can be simplified compared to the case where two types of gas are used. As the type of assist gas, various inert gases such as carbon dioxide can be adopted in addition to those mentioned above.

The first assist gas cooled by an air cooler or the like can also be supplied to the gas purge area, which can further enhance the cooling effect of the machining area. If the supply port 14 that supplies the second assist gas to the nozzle 13 is configured to supply gas from a tangential direction, the second assist gas flowing from the nozzle 13 can be sprayed while rotating in a spiral shape. The shape of the nozzle port is not limited to a circle, and can be other shapes, such as a square. The nozzle port can be a so-called Laval shape to change the flow direction and flow speed. By surrounding the space between the tip of the machining head and the machining surface of the workpiece with, for example, a shielding plate, machining can be performed in a gas purged state.

Furthermore, by adding a suction mechanism that sucks up debris from the area between the processing head and the processing surface of the workpiece, it becomes possible to more reliably remove debris. The workpiece W may be made of something other than metal, such as plastic, and may be processed other than marking, such as cutting, drilling, or groove processing. It is not limited to those equipped with a galvanometer scanner and fθ lens, but can be generally applied to those equipped with a large-area optical system such as a large lens.

The overall configuration of the laser processing device described in the above embodiment is merely one example, and various modifications are possible, such as a device that involves relative movement between the processing head and the workpiece by a robot device. Although the present disclosure has been described in accordance with the embodiment, it is understood that the present disclosure is not limited to the embodiment or structure. The present disclosure also includes various modified examples and modifications within the equivalent range. In addition, various combinations and forms, and even other combinations and forms that include only one element, more than one element, or less than one element, are also within the scope and concept of the present disclosure.

The control unit and the method described in the present disclosure may be realized by a dedicated computer provided by configuring a processor and memory programmed to execute one or more functions embodied in a computer program. Alternatively, the control unit and the method described in the present disclosure may be realized by a dedicated computer provided by configuring a processor with one or more dedicated hardware logic circuits. Alternatively, the control unit and the method described in the present disclosure may be realized by one or more dedicated computers configured by combining a processor and memory programmed to execute one or more functions with a processor configured with one or more hardware logic circuits. Furthermore, the computer program may be stored in a computer-readable non-transient tangible recording medium as instructions executed by the computer.

In the drawings, 1 is the laser processing device, 2 is the laser oscillator, 3 is the processing head, 4 is the optical system, 5 is the assist gas supply mechanism, 6 is the galvanometer scanner, 7 is the fθ lens, 8 is the control device, 9 is the nozzle section, 10 is the nozzle port, 11 is the gas purge area, 12 is the first gas supply section, 13 is the injection port, 14 is the supply port, 15 is the second gas supply section, W is the workpiece (processed object), L is the laser light, and A is the assist gas.

Claims (4)

A laser processing device (1) in which a laser beam (L) from a laser oscillator (2) is irradiated from a nozzle opening ( 10 ) at the tip of a processing head ( 3 ) through an optical system (4), and an assist gas (A) is sprayed from the nozzle opening coaxially with the laser beam by an assist gas supply mechanism (5),
The processing head has a nozzle portion (9) at a tip end side, the inner wall portion of which narrows toward the nozzle opening, and has an airtight gas purge area (11) at a base end side which opens toward the nozzle portion, and is provided with a slit-shaped nozzle (13) located at the base end of the nozzle portion for flowing gas at high speed along the inner wall surface of the nozzle portion toward the nozzle opening,
the assist gas supply mechanism includes a first gas supply unit (12) that supplies a first assist gas under a positive pressure to the gas purge area, and a second gas supply unit (15) that supplies a second assist gas to the nozzle ;
The assist gas injected from the nozzle opening is composed of a mixture of the first assist gas and the second assist gas.
Laser processing equipment. The laser processing device according to claim 1, wherein the nozzle outlet is formed by butting together two of the components that make up the nozzle section. The laser processing device according to claim 1 or 2, wherein the first gas supply unit and the second gas supply unit are configured to be capable of supplying different types of gas. The laser processing device according to claim 1 or 2, wherein the first gas supply unit and the second gas supply unit are configured to supply the same type of gas.

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