JP4337537B2 - Laser cutting method for thick materials - Google Patents

Description

  The present invention relates to a laser cutting method for a thick material in which a thick material of a metal material is cut by pulse laser irradiation.

  In order to cut a thick plate-shaped metal material workpiece (for example, stainless steel having a thickness of several tens of millimeters) or a thick round bar-shaped metal material workpiece, a pulse laser combined with an assist gas is advantageous. As this assist gas, oxygen is generally used. Incidentally, when an inert gas is used as the assist gas, the thickness of the work that can be cut (hereinafter referred to as the cutting limit length) is less than half even when the same pulse laser is used.

  Considering the case of cutting a workpiece made of stainless steel using oxygen as an assist gas, in addition to the energy of a pulse laser, the oxidation heat generation reaction of iron in stainless steel by oxygen is also used in an overlapping manner, thereby increasing the cutting ability. Can do. The assist gas also plays a role of discharging and removing the melt generated by heating with the laser by the wind pressure.

Such cutting by a pulse laser will be described with reference to the drawings. FIG. 6 is an explanatory diagram for explaining cutting by a pulse laser and a cut surface. A cutting torch 1 is disposed on the surface of the workpiece 2, and a free space from which the metal melt is removed is on the back surface of the workpiece 2.
The cutting torch 1 has a space (not shown) in the interior thereof and a nozzle hole (not shown) formed at the tip thereof to inject assist gas. Further, a condensing lens (not shown) is provided in the internal space of the cutting torch 1, and the pulse laser beam emitted from the laser oscillator (not shown) is focused on the beam spot by the condensing lens, The work 2 is irradiated through a nozzle hole.

  When the thickness of the workpiece 2 is shorter than the cutting limit length of the pulse laser, the pulse laser penetrates the workpiece 2 and reaches the back surface. At this time, the metal melt flows out from the back surface of the workpiece 2 but is vigorously discharged by the assist gas so that the metal melt does not remain in the cut surface. Such cutting is performed by moving either the cutting torch 1 or the workpiece 2 to perform desired cutting.

  However, in such cutting by a pulse laser, there has been a problem when the thickness of the workpiece 2 is longer than the cutting limit length of the pulse laser. This point will be described with reference to the drawings. FIG. 7 is an explanatory diagram for explaining self-burning. FIG. 7A is a side view as viewed from the cutting start side toward the cutting progress direction when cutting normally, and FIG. It is the side view seen toward the cutting progress direction from the cutting start side at the time.

  When the workpiece 2 is thinner than the cutting limit length of the pulse laser, the pulse laser penetrates the workpiece 2 to form a linear cut surface as shown in FIG. However, when the workpiece 2 is thicker than the cutting limit length even if the pulse laser output is the same, the pulse laser cannot penetrate the workpiece 2 and self-burning occurs as shown in FIG. To do.

  This self-burning does not proceed to a greater depth even when the thick workpiece 2 is cut halfway in the thickness direction. As a result, the oxygen used as the assist gas, the metal melt, Remains excessive, and after explosive combustion has progressed, it is ejected backward (in the direction of returning to the original direction, upward in FIG. 7B). As a result, a large hole (cavity) is formed as shown in FIG. ) Occurs. As described above, the pulse laser cutting cannot cut a workpiece having a thickness exceeding the cutting limit length of the pulse laser.

However, in laser cutting, there has been a demand for cutting a thicker workpiece. Therefore, in the prior art, a pulse laser is irradiated from two directions to cut a thickness exceeding the capability limit. Hereinafter, the difference in the cutting method due to the difference in the cutting limit length will be described by taking as an example the case of cutting stainless steel having a diameter of 120 mm.
Although not particularly shown, when the cutting limit length of the pulse laser exceeds 120 mm, a workpiece having a thickness of 120 mm can be cut without any problem.
However, the cutting is devised when the cutting limit length of the pulse laser is 100 mm. This point will be described with reference to the drawings. FIG. 8 is an explanatory diagram for explaining cutting and cutting surfaces by irradiation from two directions with a pulse laser, and shows the entire procedure of a cutting method by repeated scanning of a metal round bar workpiece having a cutting capacity of 100 mm and 120 mm.

As shown in FIG. 8, the hatched thick arrow A1 indicates the irradiation direction of the pulse laser at the start of cutting (hereinafter referred to as the laser irradiation direction at the start), and the open thick arrow A2 indicates the pulse laser irradiation direction at the end of cutting (hereinafter referred to as the laser irradiation direction). The black thick arrow A3 indicates a pulse laser irradiation direction in the middle of cutting (hereinafter referred to as a laser irradiation direction in the middle of cutting), and all assume the position of the cutting torch. A thin arrow B indicates the moving direction of the cutting torch (hereinafter referred to as the torch moving direction). Here, the length of the A3 laser irradiation line T is 100 mm, which is the cutting limit length.
First, as shown by the cutting order N1, if the cutting torch is moved in the torch moving direction B to the end laser irradiation direction A2 while irradiating the pulse laser with the start laser irradiation direction A1 as the start of cutting, the cutting boundary A cut surface S1 such as a point-drawn surface is formed by cutting to the portion L1.
Subsequently, as shown in the cutting sequence N2, while the cutting torch is rotated by 90 °, the cutting laser is irradiated from the start laser irradiation direction A1 to the cutting start, and the cutting torch is extended to the end laser irradiation direction A2. If it is moved in the torch moving direction B, it is cut by the laser irradiation line T, and finally all the remaining surfaces are cut.
Thus, even if the cutting limit length of the pulse laser is 100 mm, a large number of cuttings are performed, and as a result, a round bar having a diameter of 120 mm can be cut by two scans.

However, if the cutting limit length of the pulse laser is set to 90 mm, there is a problem even if the method is similar to the method described above. This point will be described with reference to the drawings. FIG. 9 is an explanatory diagram for explaining cutting and cutting surfaces by irradiation from two directions with a pulse laser, and shows an example of a failure of cutting a metal workpiece by an overall procedure of a cutting method by repeated scanning of a metal round bar workpiece having a cutting capability of 90 mm and 120 mm. FIG. Here, the length of the laser irradiation line A3 is 90 mm, which is the cutting limit length.
If the cutting torch is moved in the torch moving direction B to the end laser irradiation direction A2 while irradiating the laser with the start laser irradiation direction A1 as the start of cutting as shown by the cutting sequence N1 in FIG. A cut surface S1 such as a point-drawn surface is created by being divided to the portion L1.
However, as shown by the cutting sequence N2, even when the laser is irradiated with the cutting torch rotated by 90 °, this cutting is a cutting exceeding the cutting limit length, and the laser irradiation line T is a cutting boundary portion. It does not reach L1. For this reason, the cutting torch is set outside the workpiece and the cutting condition of free space on the back side of the laser irradiation cannot be satisfied, and self-burning may occur, which is not a complete cutting method.

In the prior art of laser processing technology, for example, the invention described in Patent Document 1 (title of the invention: laser processing method and laser processing apparatus) is known.
However, Patent Document 1 does not disclose a technique for cutting a workpiece having a thickness longer than the cutting limit length of the pulse laser.

Japanese Patent Laid-Open No. 11-10380 (FIGS. 3 and 5)

  Therefore, the present invention has been made in view of the above-mentioned problems, and the purpose of the cutting limit length is a metal material having a portion longer than the cutting limit length of the pulse laser. The object is to provide a laser cutting method for thick materials that is cut by pulse laser irradiation as it is.

In order to solve the above-described problem, a laser cutting method for a thick material according to claim 1 of the present invention includes:
Pulse laser is irradiated from the outer circumference side of the round bar-shaped thick material while moving the laser irradiation part or the thick material to the round bar-shaped thick material of the metal material having a diameter longer than the cutting limit length of the pulse laser. In the laser cutting method for thick materials, where the entire surface is finally cut,
So as to be parallel to the laser irradiation section or Thick material pulsed laser radiation is incident pulsed laser from the side of the thick matter material by starting cut to Rutotomoni incident direction of the incident direction cutting the beginning of while moving the cut into a pulse Thick material outside peripheral side from the thick material member center cutting limits and cutting the thick material material while moving in a direction length less straight line cut boundary the incident position of the laser while maintaining the Perform the linear movement cut surface formation to form the surface,
Hereinafter, a the cutting boundary, a line passing through the center axis of the rod-shaped thick matter material, the line passing through the intersection of the determined as a new cut boundaries perpendicular to the cutting boundary, this new The laser irradiation part or thick material is stopped after rotation so that the irradiation direction of the laser irradiation part is parallel to the line direction of the new cutting boundary part with respect to the cutting boundary part . parallel to further intersects the cutting boundary portions of the cut surface which is the formation there, the cutting restart to Rutotomoni the incident direction by the incidence of pulsed laser from the side of the thick matter material relative to the direction of cutting resumption initially and so as to the position of incidence of the pulsed laser while maintaining by irradiating a pulsed laser while moving from thick material material outside circumference side to the heavy weight material center direction new to the remaining connecting portion in the cutting plane the same plane a straight line of cutting the boundary portion of the following cleavage limit length Repeated linear movement cut surface forming for forming a sea urchin cut surface,
Finally, the laser irradiation part or the thick material is stopped after being rotated, and a linearly moving cut surface is formed to cut all remaining connection portions in the same plane as the cut surface formed immediately before, and cut into a flat shape. ,
It is characterized by that.

Further, the laser cutting method for thick material of the invention according to claim 2 of the present invention,
Pulse laser is irradiated from the outer circumference side of the round bar-shaped thick material while moving the laser irradiation part or the thick material to the round bar-shaped thick material of the metal material having a diameter longer than the cutting limit length of the pulse laser. In the laser cutting method for thick materials, where the entire surface is finally cut,
So as to be parallel to the laser irradiation section or Thick material pulsed laser radiation is incident pulsed laser from the side of the thick matter material by starting cut to Rutotomoni incident direction of the incident direction cutting the beginning of while moving the cut into a pulse Thick material outside peripheral side from the thick material member center cutting limits and cutting the thick material material while moving in a direction length less straight line cut boundary the incident position of the laser while maintaining the Perform the linear movement cut surface formation to form the surface,
Hereinafter, the laser irradiation part or the thick material is stopped after being rotated by 45 °, and from the side of the thick material so that it is in the same plane as the formed cut surface and further intersects with the cut boundary portion of the formed cut surface. be cut resumed by the incidence of pulsed laser Rutotomoni Thick material toward the center of the incident position of the pulse laser while maintaining to be parallel to the incident direction relative to the direction of cutting resumed beginning from thick material material outside peripheral side A linear moving cutting that forms a cutting surface so as to be a cutting boundary portion on a straight line that is not longer than the cutting limit length with respect to the remaining connection portion in the same plane as the cutting surface by irradiating a pulse laser while moving to Repeated surface formation,
Finally, the laser irradiation part or the thick material is stopped after being rotated, and a linearly moving cut surface is formed to cut all remaining connection portions in the same plane as the cut surface formed immediately before, and cut into a flat shape. ,
It is characterized by that.

  According to the present invention as described above, even for a thick material made of a metal material having a portion longer than the cutting limit length of the pulse laser, the thick material can be cut by pulse laser irradiation without changing the cutting limit length. A laser cutting method can be provided.

Next, the best mode for carrying out the present invention will be described with reference to the drawings. FIG. 1 and FIG. 2 are explanatory views of the laser cutting method for thick material of this embodiment, and the whole procedure of the method of repeatedly cutting a 120 mm diameter stainless steel round workpiece as a thick material with respect to a cutting capacity of 80 mm FIG.
The laser cutting method for thick material of this embodiment includes a cutting torch as described above with reference to FIG. 6 as a specific example of the laser irradiation unit, and a movable holding unit (not shown) that can rotate and move in the horizontal direction. Are cut by an apparatus provided with In this apparatus, the position of the cutting torch is not changed, and the workpiece is cut by rotating and moving in the horizontal direction so as to be in a predetermined position. The movement holding unit can be rotated and moved in the horizontal direction to a desired position with the work 2 attached thereto.
Instead of moving the workpiece 2, the cutting torch 1 may be gripped by a device that moves the cutting torch 1, for example, a robot arm, and the robot arm may be moved horizontally and rotated.
In any case, if the cutting torch 1 and the workpiece 2 are configured to be relatively rotated and horizontally moved, the laser cutting method for a thick material of the present invention can be implemented.

  The cutting torch outputs a pulse laser beam together with the assist gas, and performs cutting exceeding the cutting limit length. Specifically, a pulse YAG laser output is used as the pulse laser, and the ability to cut stainless steel with a thickness of 80 mm is secured as a cutting ability. This pulse laser output is transmitted through an optical fiber, the pulse laser is output from the cutting torch together with the assist gas, and a stainless steel round bar having a diameter of 120 mm is cut by the following method.

At this time, as shown in FIG. 1 and FIG. The diameter of the circle indicates a 120 mm stainless steel round bar as shown in FIG. Note that the cutting boundary lines L1 to L4 and the laser irradiation line T indicate 80 mm which is the cutting limit length.
Cutting starts from cutting sequence N1. As shown in FIGS. 1 and 2, a hatched thick arrow A1 outside the circle indicates the laser irradiation direction at the start, and a white thick arrow A2 indicates the laser irradiation direction at the end, indicating the position of the cutting torch. Cutting starts at a position in the laser irradiation direction A1 at the start and ends at a position in the laser irradiation direction A2 at the end.

As shown in FIG. 1, the thick material is cut by pulse laser irradiation while moving the cutting torch from the outside of the circle in the direction of the torch moving in the thin arrow B so as to include the cutting boundary portion L1 of the cutting limit length. A cut surface S1 is formed. This cutting boundary portion L1 has a length of 80 mm which is exactly the same as the cutting limit length, which means that it can be cut to that point in the first cutting order N1. Such a linearly moving cut surface is formed, and only the portion of the cut surface S1 in the circle is cut and removed as shown in FIG.
This is a cutting limit length as short as 80 mm, but it is the same cutting as the cutting sequence N1 shown in FIGS. 8 and 9, and within the range where the metal melt by laser irradiation is removed without causing self-burning. Will only cut off.

Next, as shown in FIG. 2, by the same cutting by forming the linearly moving cutting plane shown in the cutting sequence N2 in FIG. 1 (cutting by moving the cutting torch from the arrow A1 to the arrow A2 in the direction of the arrow B), A portion of the inner cut surface S2 is cut and removed. At this time, the cutting boundary line L2 is set so as to pass through the center a of the cutting boundary line L1. That is, the cutting end point of the cutting order N2 is the deepest part a cut in the cutting order N1.
The cutting direction is determined by determining a one-dot chain line α (common to the y-axis) that is perpendicular to the cutting boundary line L1 and passes through the center of the round bar, and this wavy line α and the cutting boundary line L1. It was determined to be a straight line of 80 mm from the circle end through the intersection a. This is a cutting method that can cut up to the point closest to the center. By this scanning, it is cut to the cutting boundary line L2.
At this time, the back surface of the portion cut by the cutting sequence N2 with respect to the laser irradiation has already been cut by the cutting sequence N1, so that it is free space, and the metal melt generated by the cutting of the cutting sequence N2 is removed. .

Next, as shown in FIG. 2, by cutting by the same linear movement cutting plane formation shown in the cutting sequence N <b> 3 of FIG. 1 (cutting by movement of the cutting torch from arrow A <b> 1 to arrow A <b> 2 in the direction of arrow B), The portion of the inner cut surface S3 is cut and removed. At this time, the cutting boundary line L3 is set so as to cut through the point b of the cutting boundary line L2.
The cutting direction is determined by determining a wavy line β that is perpendicular to the cutting boundary line L2 and passes through the center of the round bar, and passes through the intersection b of the wavy line β and the cutting boundary line L2. It was determined to be a straight line of 80 mm from the end of the circle. This is a cutting method that can cut up to the point closest to the center. By this scanning, the cutting is performed up to the cutting boundary line L3.
Since the back surface of the portion cut by the cutting sequence N3 with respect to laser irradiation has already been cut by the cutting sequences N1 and N2, it is free space, and the metal melt generated by the cutting of the cutting sequence N3 is removed. .

Next, as shown in FIG. 2, by cutting by the same linear moving cutting plane formation shown by the cutting sequence N <b> 4 in FIG. 1 (cutting by movement of the cutting torch from arrow A <b> 1 to arrow A <b> 2 in the direction of arrow B), The inner cut surface S4 is cut and removed. At this time, the tip of the cutting torch is outside the stainless round bar, and the cutting boundary line L4 is set so as to cut through the point c of the cutting boundary line L2.
The cutting direction is determined by determining a wave line γ that is perpendicular to the cutting boundary line L3 and passes through the center of the round bar, and passes through the intersection c between the wave line γ and the cutting boundary line L3. It was determined to be a straight line of 80 mm from the end of the circle. By this scanning, it is cut to the cutting boundary line L4.
Since the back surface of the portion cut by the cutting sequence N4 with respect to the laser irradiation has already been cut by the cutting sequences N2 and N3, it is free space, and the metal melt generated by the cutting of the cutting sequence N4 is removed. .

Next, as shown in FIG. 2, by cutting by the same linear movement cutting plane formation shown in the cutting sequence N5 in FIG. 1 (cutting by moving the cutting torch from the arrow A1 to the arrow A2 in the direction of arrow B), as shown in FIG. A portion of the inner cut surface S5 is cut and removed. At this time, since the remainder is within the cutting limit length as shown by the straight line 80 mm of the laser irradiation line T, all can be cut. This cutting sequence N5 is the longest cutting length.
Since the back surface of the portion cut by the cutting sequence N5 with respect to laser irradiation has already been cut by the cutting sequences N3 and N4, it is free space, and the metal melt generated by the cutting of the cutting sequence N5 is removed. .

  The above-described situation of being sequentially cut is shown in FIG. 2 by color-coding the cut portion (shaded portion), the already cut portion (white portion), and the uncut portion (drawing portion). Shown in With each cutting scan, the hatched portion is cut and removed. As a result, even if the thickness of the cutting ability is 80 mm, a round bar having a diameter of 120 mm can be cut by repeated scanning five times.

  In this cutting method, as described with reference to FIG. 1, the cutting is basically performed so as to form a cutting boundary line that passes through the vicinity of the center at the end of each cutting. Each angle at which the workpiece is rotated can be calculated by a computer or the like, and the workpiece is positioned by moving the moving holding unit based on the calculation result.

  Here, if each of the similar angles in FIG. 1 is rotated by 45 °, the laser irradiation direction can be easily set. This point will be described with reference to the drawings. FIG. 3 is an explanatory diagram of a simple laser cutting method for thick materials. As shown in FIG. 3, the same cutting method as in FIG. 1 is shown with rotation by 45 °, but the cutting torch is outside the circle and the straight cutting end is already cut and removed. You can see that Therefore, it can be seen that a round bar having a diameter of 120 mm can be cut with a cutting ability of 80 mm as in the method of FIG.

As described above, when a round bar having a diameter of 120 mm is cut, if the cutting capability is 80 mm, the round bar can be cut by five repeated scans. Incidentally, when the cutting ability is 90 mm, the cutting can be performed by repeating the scanning three times, and when the cutting ability is 70 mm, the cutting can be performed by repeating the scanning 11 times.
In addition, although demonstrated as a prior art, when the cutting capability is 100 mm, as shown in FIG. 8, it can cut | disconnect by 2 times of repeated scanning.
By using such a method, if the cutting ability exceeds half the diameter of the round bar, the cutting can be performed by repeating the sequential cutting so that the cutting end line is as close to the center as possible.

  Further, as another cutting method, a cutting method of square bars will be described with reference to the drawings. FIG. 4 is an explanatory diagram of a laser cutting method for thick material of square bars. This is a cutting method assuming a square square member having a cutting ability of 80 mm and a side of 120 mm. Here, the same cutting as described above is performed according to the cutting order N1 to N7, and it is shown that the cutting can be performed by repeated scanning seven times. In addition, each line of N1-N6 corresponds with the cutting | disconnection boundary line, and N7 represents the laser irradiation line in the middle of cutting | disconnection.

As described above, in this embodiment, a linear moving cutting is performed in which a cutting surface is formed so as to include a cutting boundary portion on a straight line that is equal to or shorter than the cutting limit length by cutting the work by pulse laser irradiation while moving the cutting torch or the work. Surface formation is performed (for example, the cutting order N1 of this embodiment),
After that, the cutting torch or workpiece is stopped after rotating, and the remaining connection in the same plane as the cut plane is irradiated by irradiating the pulse laser so that it is in the same plane as the formed cut plane and crosses this cutting boundary. A linearly moving cut surface is repeatedly formed to form a cut surface so as to include a cut boundary portion on a straight line that is not longer than the cutting limit length (for example, cutting order N2, N3, N4 in this embodiment),
Finally, the cutting torch or the work is stopped after rotating, and a linearly moving cut surface is formed to cut all remaining connecting portions in the same plane as the formed cut surface and cut into a planar shape (for example, this embodiment) Therefore, a laser cutting method for a thick material that can cut even a thick material exceeding the cutting limit length can be obtained.

Next, another best mode for carrying out the present invention will be described with reference to the drawings. FIG. 5 is an explanatory view of a laser cutting method for a thick material in another form. It is a figure which shows the whole cutting | disconnection procedure by cutting | disconnecting the thick metal workpiece | work beyond a cutting capability from an outer periphery sequentially.
Also in this case, the cutting ability on the laser side is 80 mm, the workpiece has a diameter of 120 mm, the respective arrows and symbols are the same as those described above, and duplicate descriptions are omitted.

  First, the cutting torch (or workpiece) is moved in the cutting order N1 to cut to the cutting boundary portion L1, thereby forming a linearly moving cut surface that cuts and removes the portion of the cut surface S1 in the circle. This is exactly the same as the cutting of the cut surface S1 in FIG. At the end of this final state, while maintaining the laser irradiation direction, the workpiece (or cutting torch) is rotated as in the cutting order N2 to form the circular cutting boundary portion L2. As a result, a rotationally moving cut surface is formed to cut and remove the doughnut-shaped cut surface S2 in the circle.

Hereinafter, similarly, the cutting torch (or workpiece) is moved in the cutting order N3 to cut to the cutting boundary portion L3 to form a linearly moving cutting surface that cuts and removes the portion of the cutting surface S3 in the circle. At the end of the final state, the laser irradiation direction is maintained and laser irradiation is performed, and then the workpiece (or cutting torch) is rotated as in the cutting order N4 to form the cutting boundary L4, and the donut shape in the circle A rotationally moving cut surface is formed to cut and remove the cut surface S4.
Subsequently, the cutting torch (or workpiece) in the cutting order N5 is moved to be cut to the cutting boundary L5 to form a linearly moving cut surface that cuts and removes the portion of the cut surface S5 in the circle. This final state While irradiating with the laser irradiation direction maintained, the workpiece (or cutting torch) is rotated as in the cutting sequence N6 to form the cutting boundary L6, and the donut-shaped cutting in the circle A rotationally moving cut surface is formed to cut and remove the surface S6.

Subsequently, by moving the cutting torch (or workpiece) in the cutting order N7, a straight moving cut surface is formed that cuts and removes the cut surface S7 in the circle by cutting to the cutting boundary L7. While performing laser irradiation while maintaining the laser irradiation direction at the end, the workpiece (or cutting torch) is then rotated as in the cutting order N8 to form the cutting boundary L8, and the donut-shaped cutting surface in the circle A rotationally moving cut surface is formed that S8 cuts and removes.
Finally, the remaining part as in the cutting order N9 is cut by forming the linearly moving cut surface, and the cutting is finished.
Finally, a round bar having a diameter of 120 mm can be cut and separated with a performance of a cutting ability of 80 mm in nine scans. Note that the cutting torch is outside the workpiece, and the limit surface corresponding to the laser irradiation back surface has already been cut and removed, so that it is free space and can be seen to be safe for cutting.

In such a cutting method according to the present embodiment, the cutting surface is formed so as to include a cutting boundary portion on a straight line that is equal to or shorter than the cutting limit length by cutting the work by pulse laser irradiation while moving the cutting torch or the work. A linear moving cut surface is formed (for example, the cutting order N1 of this embodiment),
Thereafter, a rotationally moving cut surface is formed to form a cut surface including a circular cutting boundary by pulse laser irradiation while rotating the workpiece by pulse laser irradiation (for example, cutting sequence N2 in this embodiment).
Hereinafter, a new linearly moving cut surface is formed (for example, cutting sequence N3, N5, N7 in this embodiment) and a rotationally moving cut surface is formed (for example, this book) with respect to the remaining connection portion in the same plane as the previously formed cut surface. The cutting sequence N4, N6, N8) of the embodiment is alternately repeated a plurality of times (for example, the cutting sequence N3 → N4 → N5 → N6 → N7 → N8 of the present embodiment),
Finally, a linearly moving cut surface is formed that cuts all remaining connecting portions in the same plane as the cut surface formed immediately before, and is cut into a flat shape (for example, the cutting order N9 of this embodiment), so that the cutting limit Even if it is a thick material exceeding length, it can be set as the laser cutting method for thick materials which can be cut | disconnected.

The laser cutting method for thick material of the present invention described above has been described. In these cutting methods, the cutting ability of the pulse YAG laser having a high peak power is further improved. Moreover, since the YAG laser can transmit laser energy through an optical fiber, it can be cut in a special environment. In particular, in the field of radioactive waste treatment, only a part of the optical fiber and only the cutting torch and its control unit need be installed in the radiation management area, so that the effectiveness is increased.
As a result, the above-described cutting method by repetitive scanning with a pulse laser can be cut by repetitive scanning as long as it has a cutting ability for a thickness exceeding the radius of a metal workpiece. Naturally, the cutting torch can be set outside the workpiece, and the back side satisfies the conditions that allow the molten material to flow out and be removed. As a result, it can be applied to various workpieces and is highly versatile.

It is explanatory drawing of the laser cutting method for thick materials of the best form for implementing this invention. It is explanatory drawing of the laser cutting method for thick materials of the best form for implementing this invention. It is explanatory drawing of the simple type laser cutting method for thick materials. It is explanatory drawing of the laser cutting method for thick materials of a square. It is explanatory drawing of the laser cutting method for thick materials of the other best form for implementing this invention. It is explanatory drawing explaining the cutting | disconnection by a pulse laser, and a cut surface. 7A and 7B are explanatory diagrams for explaining self-burning, in which FIG. 7A is a side view viewed from the cutting start side toward the cutting progress direction when cutting normally, and FIG. 7B is a view when self-burning occurs. It is the side view seen toward the cutting progress direction from the cutting start side. It is explanatory drawing explaining the cutting | disconnection by the irradiation from two directions using a pulse laser, and a cut surface. It is explanatory drawing explaining the cutting | disconnection by the irradiation from two directions using a pulse laser, and a cut surface.

Explanation of symbols

1: Cutting torch 2: Workpiece

Claims (2)

Pulse laser is irradiated from the outer circumference side of the round bar-shaped thick material while moving the laser irradiation part or the thick material to the round bar-shaped thick material of the metal material having a diameter longer than the cutting limit length of the pulse laser. In the laser cutting method for thick materials, where the entire surface is finally cut,
So as to be parallel to the laser irradiation section or Thick material pulsed laser radiation is incident pulsed laser from the side of the thick matter material by starting cut to Rutotomoni incident direction of the incident direction cutting the beginning of while moving the cut into a pulse Thick material outside peripheral side from the thick material member center cutting limits and cutting the thick material material while moving in a direction length less straight line cut boundary the incident position of the laser while maintaining the Perform the linear movement cut surface formation to form the surface,
Hereinafter, a the cutting boundary, a line passing through the center axis of the rod-shaped thick matter material, the line passing through the intersection of the determined as a new cut boundaries perpendicular to the cutting boundary, this new The laser irradiation part or thick material is stopped after rotation so that the irradiation direction of the laser irradiation part is parallel to the line direction of the new cutting boundary part with respect to the cutting boundary part . parallel to further intersects the cutting boundary portions of the cut surface which is the formation there, the cutting restart to Rutotomoni the incident direction by the incidence of pulsed laser from the side of the thick matter material relative to the direction of cutting resumption initially and so as to the position of incidence of the pulsed laser while maintaining by irradiating a pulsed laser while moving from thick material material outside circumference side to the heavy weight material center direction new to the remaining connecting portion in the cutting plane the same plane a straight line of cutting the boundary portion of the following cleavage limit length Repeated linear movement cut surface forming for forming a sea urchin cut surface,
Finally, the laser irradiation part or the thick material is stopped after being rotated, and a linearly moving cut surface is formed to cut all remaining connection portions in the same plane as the cut surface formed immediately before, and cut into a flat shape. ,
A method for laser cutting for thick materials. Pulse laser is irradiated from the outer circumference side of the round bar-shaped thick material while moving the laser irradiation part or the thick material to the round bar-shaped thick material of the metal material having a diameter longer than the cutting limit length of the pulse laser. In the laser cutting method for thick materials, where the entire surface is finally cut,
So as to be parallel to the laser irradiation section or Thick material pulsed laser radiation is incident pulsed laser from the side of the thick matter material by starting cut to Rutotomoni incident direction of the incident direction cutting the beginning of while moving the cut into a pulse Thick material outside peripheral side from the thick material member center cutting limits and cutting the thick material material while moving in a direction length less straight line cut boundary the incident position of the laser while maintaining the Perform the linear movement cut surface formation to form the surface,
Hereinafter, the laser irradiation part or the thick material is stopped after being rotated by 45 °, and from the side of the thick material so that it is in the same plane as the formed cut surface and further intersects with the cut boundary portion of the formed cut surface. be cut resumed by the incidence of pulsed laser Rutotomoni Thick material toward the center of the incident position of the pulse laser while maintaining to be parallel to the incident direction relative to the direction of cutting resumed beginning from thick material material outside peripheral side A linear moving cutting that forms a cutting surface so as to be a cutting boundary portion on a straight line that is not longer than the cutting limit length with respect to the remaining connection portion in the same plane as the cutting surface by irradiating a pulse laser while moving to Repeated surface formation,
Finally, the laser irradiation part or the thick material is stopped after being rotated, and a linearly moving cut surface is formed to cut all remaining connection portions in the same plane as the cut surface formed immediately before, and cut into a flat shape. ,
A method for laser cutting for thick materials.

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