Laser processing apparatus, laser processing method, and program code generation apparatus

Abstract

The laser processing apparatus (100) comprises a processing head (13) that irradiates a workpiece (30) with a laser beam (1), a drive unit (14) that moves at least one of the workpiece (30) and the processing head (13), and a control unit (16) that controls the irradiation of the laser beam (1). The control unit (16) performs the following controls: irradiating the workpiece (30) with a first laser beam along a predetermined cutting path to form a cutting groove; stopping the irradiation of the first laser beam when the irradiation position of the laser beam (1) reaches a first endpoint; irradiating the workpiece (30) with a second laser beam on the end piece side of the already cut portion of the workpiece to form dross on the lower surface of the end piece; and, after the formation of dross, restarting the irradiation of the first laser beam from the first endpoint to irradiate the workpiece (30) with the first laser beam to the second endpoint, which is the end of the cutting path, to cut and separate the workpiece from the workpiece (30).

Description

Technical Field

[0001] The present disclosure relates to a laser processing apparatus, a laser processing method, and a program code generation apparatus that irradiate a processing object with a laser beam to cut the processing object.

Background Art

[0002] When producing a processed product by cutting a processing object with a laser processing apparatus, in order to prevent the processed product from separating and falling from the end material remaining on the outer peripheral portion of the processing object, or to prevent the processed product from rising due to the positional deviation between the fulcrum of the work support that supports the processed product from the back surface and the center of gravity of the processed product, at least one uncut portion may be left in the cutting groove portion on the outer periphery of the processed product. Such an uncut portion is called a joint and is a commonly used technique in sheet metal laser processing.

[0003] As a method of preventing the processed product separated from the end material from falling or the processed product from rising, in addition to the method of leaving an uncut portion, for example, Patent Document 1 discloses a method of irradiating a laser to the end material around the processed product and joining the processed product and the end material using the melt.

[0004] Further, Patent Document 2 discloses a method of leaving an uncut portion only at the lower part of the cut by instantaneously reducing the laser output or increasing the cutting speed during laser cutting, and imparting a micro-sized joint between the processed product and the end material. As an advantage of this method, since the joint is small, the processed product and the end material can be separated by hand without using a tool, and the cutting mark is also less noticeable.

[0005] Further, Patent Document 3 discloses a method of holding a processed product without leaving an uncut portion. This method presses and holds the processed product from the side by subjecting a part of the end material to slit processing and causing thermal deformation. Therefore, in this method, there is no uncut portion and no joint cutting mark occurs.

Prior Art Documents

Patent Documents

[0006] [Patent Document 1] Japanese Patent Application Publication No. 6-238475 [Patent Document 2] Special Publication No. 2024-533379 [Patent Document 3] Japanese Patent Publication No. 2024-22949 [Overview of the project] [Problems that the invention aims to solve]

[0007] When an automated sorting system is introduced that sorts processed products using a robotic arm or the like, if a joint is provided by joining the processed product and the scrap material, or by leaving an uncut portion, as disclosed in Patent Document 1 or Patent Document 2, there is a problem that the strong connecting force of the joint may prevent the processed product and the scrap material from being separated. On the other hand, with the method disclosed in Patent Document 3, the connecting force is weak and the processed product can be separated even when an automated sorting system is introduced, but when the processed product is picked up by the robotic arm, if the processed product is pushed below the scrap material, it may get caught in the slit and become impossible to separate.

[0008] This disclosure has been made in view of the above, and aims to provide a laser processing apparatus that suppresses the inability to separate the processed product from the scrap material. [Means for solving the problem]

[0009] To solve the above-mentioned problems and achieve the objective, the laser processing apparatus according to the present disclosure is a laser processing apparatus that performs a cutting process in which a workpiece is separated into a workpiece and scrap material by irradiating the workpiece with a laser beam and injecting an assist gas into the workpiece, and comprises a processing head that has a nozzle for injecting an assist gas into the workpiece and irradiates the workpiece with a laser beam, a drive unit that moves at least one of the workpiece and the processing head, and a control unit that controls the irradiation of the laser beam. The control unit performs the following actions: to form a cutting groove by irradiating the workpiece with a first laser beam along a predetermined cutting path that follows the outer shape of the workpiece on the upper surface of the workpiece, which is the surface on which the laser beam is irradiated; to stop irradiating the first laser beam when the irradiation position of the laser beam reaches a predetermined first endpoint in the middle of the cutting path; to irradiate the workpiece with a second laser beam different from the first laser beam, according to a predetermined program code, to pierce a hole for dross formation through at least one location in the end material on the end material side of the already cut part of the workpiece, and to form dross protruding toward the workpiece on the lower surface of the end material so as to hold the workpiece; and after the dross is formed, to restart the irradiation of the first laser beam from the first endpoint and irradiate the workpiece with the first laser beam until it reaches the second endpoint, which is the end of the cutting path, thereby cutting and separating the workpiece from the workpiece. [Effects of the Invention]

[0010] The laser processing apparatus described herein has the effect of preventing the processed product from becoming inseparable from the scrap material. [Brief explanation of the drawing]

[0011] [Figure 1] Schematic diagram of the laser processing apparatus according to Embodiment 1 [Figure 2] A diagram showing an example of the cutting path of a processed product using a laser processing apparatus according to Embodiment 1. [Figure 3] A diagram showing an example of a piercing hole for dross formation in a laser processing apparatus according to Embodiment 1. [Figure 4]A diagram showing an example of the center of gravity of a processed product from a laser processing apparatus according to Embodiment 1. [Figure 5] Top view of dross formed by the laser processing apparatus according to Embodiment 1 [Figure 6] Side view of a dross formed by the laser processing apparatus according to Embodiment 1 [Figure 7] This figure shows the state in which dross is formed on a thin plate-thickness workpiece using the laser processing apparatus according to Embodiment 1. [Figure 8] This figure shows an example of a case in which the cutting groove for approaching the piercing hole is straight in the laser processing apparatus according to Embodiment 1. [Figure 9] This figure shows an example of a case in which the cutting groove for approaching the piercing hole is curved in the laser processing apparatus according to Embodiment 1. [Figure 10] This figure shows an example of a case in which the width of the cutting groove for approaching the piercing hole for dross formation and the cutting groove for dross formation change in the laser processing apparatus according to Embodiment 1. [Figure 11] This figure shows an example of a laser processing apparatus according to Embodiment 1 in which the portion that forms the dross is cut into a slit shape. [Figure 12] This figure shows an example of the offset shape extraction process by the program code generation device according to Embodiment 1. [Figure 13] This figure shows an example of the process by which the program code generation device according to Embodiment 1 decomposes the offset shape into a point cloud. [Figure 14] This figure shows an example of a process by the program code generation device according to Embodiment 1 to exclude the corners of a processed product from the candidates for dross formation locations. [Figure 15] This figure shows an example of a process by the program code generation device according to Embodiment 1 that uses only the point cloud of the convex hull as a candidate for the dross formation position. [Figure 16] This figure shows an example of a process by the program code generation device according to Embodiment 1 to exclude overlapping points between dross formation position candidates and work support pivot points from the dross formation position candidates. [Figure 17]A diagram showing an example of a triangle in which the shortest distance between the center of gravity of a processed product obtained by selecting three points from the point group of the candidate positions of the dross formation by the program code generation device according to Embodiment 1 and each side is maximized [Figure 18] A diagram showing an example of a polygon with the minimum number of vertices where the shortest distance between each side and the center of gravity extracted by the program code generation device according to Embodiment 1 is maximized [Figure 19] A diagram showing an example of the relationship between the polygon with the minimum number of vertices where the shortest distance between each side and the center of gravity extracted by the program code generation device according to Embodiment 1 is maximized, the shape of the processed product, and the position of the workpiece support fulcrum [Figure 20] A diagram showing an example when the program code generation device according to Embodiment 1 suppresses the number of dross formation points using the extracted workpiece support fulcrum [Figure 21] A diagram showing an example of the shape of a processed product in which the processed product separation position cannot be set inside the support base surface set by the program code generation device according to Embodiment 1 [Figure 22] A diagram showing an example of the code generated by the program code generation device according to Embodiment 1 for causing the laser processing device to perform a process of moving the injection position of the assist gas toward the support base surface immediately after cutting and separating [Figure 23] A diagram showing an example in which the center of gravity of the end material is located inside with respect to the dross formation position set so that the center of gravity of the end material inside the processed product is located outside the polygon connecting the dross formation positions set by the program code generation device according to Embodiment 1 with a straight line, and the workpiece support fulcrum enters inside the polygon [Figure 24] A diagram showing an example in which the center of gravity of the end material inside the processed product is located outside the polygon connecting the dross formation positions set by the program code generation device according to Embodiment 1 with a straight line, and the workpiece support fulcrum is located outside the polygon [Figure 25] A diagram showing an example of the code generated by the program code generation device according to Embodiment 1 for causing the laser processing device to perform a process of forming two drosses on a circular end material [Figure 26]This figure shows an example of code generated by the program code generation device according to Embodiment 1, which causes the laser processing device to perform a process to form two dross points on a circular piece of scrap material. [Figure 27] This figure shows an example of code generated by the program code generation device according to Embodiment 1, which causes the laser processing device to perform a process to form a single dross on a circular piece of scrap material. [Figure 28] This figure shows an example of code generated by the program code generation device according to Embodiment 1, which causes the laser processing device to perform a process to form a single dross on a circular piece of scrap material. [Figure 29] This figure shows an example of a hardware configuration for realizing the control unit of the laser processing apparatus according to Embodiment 1. [Modes for carrying out the invention]

[0012] Below, a laser processing apparatus, a laser processing method, and a program code generation apparatus according to an embodiment will be described in detail with reference to the drawings.

[0013] Embodiment 1. Figure 1 is a schematic diagram of a laser processing apparatus according to Embodiment 1. The laser processing apparatus 100 includes a laser oscillator 11 that emits a laser beam 1, an optical path 12 which is the path through which the laser beam 1 travels, a processing head 13 that changes the direction of travel of the laser beam 1 toward the workpiece 30, a drive unit 14 that moves the processing head 13 along the processing path, a detection unit 15 that detects the position of the processing head 13, and a control unit 16 that controls the relative movement of the processing head 13 and the workpiece 30, and the irradiation of the laser beam 1, according to a program code input from a program code generation device 40. The processing head 13 includes a lens 17 that focuses the laser beam 1 onto the surface of the workpiece 30, and a nozzle 18 that receives processing gas from a processing gas supply source 21 and injects assist gas. Here, a configuration in which the drive unit 14 moves the processing head 13 is used as an example, but the drive unit 14 only needs to be able to move the processing head 13 and the workpiece 30 relatively. In other words, the drive unit 14 only needs to be configured to move at least one of the machining head 13 and the workpiece 30.

[0014] The workpiece 30 is placed on a work support 50 and supported from the back. The optical axis 1a of the laser beam 1 is directed towards the processing point 30c on the surface of the workpiece 30. The assist gas 2 ejected from the nozzle 18 is blown onto the surface of the workpiece 30, centered on the processing point 30c.

[0015] Figure 2 is a diagram showing an example of the cutting path of a workpiece processed by a laser processing apparatus according to Embodiment 1. Figure 3 is a diagram showing an example of a piercing hole for dross formation in a laser processing apparatus according to Embodiment 1. Figure 4 is a diagram showing an example of the center of gravity of a workpiece processed by a laser processing apparatus according to Embodiment 1. The cutting path 211 is a processing path in which a laser beam 1 is irradiated onto the workpiece 30 to perform the cutting process of the workpiece 30. As shown in Figure 2, the cutting path 211 includes a first cutting path 21a, which is the path of the laser beam 1 in the process of cutting out the workpiece 33 from the workpiece 30, and a second cutting path 21b, which is the path of the laser beam 1 in the process of separating the cut-out workpiece 33 from the scrap material 31. The laser processing apparatus 100 starts cutting the workpiece 30 from the cutting piercing 39 and, when it reaches the first endpoint 211a set in the middle of the first cutting path 21a, it temporarily stops the irradiation of the laser beam 1 and performs the operation of piercing the dross-forming piercing holes 32 in the already cut portion where dross 34 is to be formed. The dross 34 protrudes toward the workpiece 33 on the lower surface of the scrap material 31 and holds the workpiece 33.

[0016] As shown in Figure 3, the piercing position of the dross-forming piercing hole 32 is set to an offset position of approximately 0.3 to 3.0 mm on the outer circumference of the workpiece 33 from the center line of the cutting groove of the first cutting path 21a, and the process is carried out by switching to the processing conditions set to form dross 34 on the back surface of the scrap material 31. Here, the laser beam 1 for the processing conditions to cut the workpiece 30 is called the first laser beam, and the laser beam 1 for the processing conditions to form dross 34 is called the second laser beam. Both the first and second laser beams are laser beams 1 output from the laser oscillator 11, but their oscillation conditions, such as output intensity, are different.

[0017] As shown in Figure 4, after forming the dross 34, the laser processing apparatus 100 resumes cutting the workpiece 30 from the first endpoint 211a and irradiates the workpiece 30 with the laser beam 1 along the second cutting path 21b to the second endpoint 211b, which is the end point of the cutting path 211, to separate the processed product 33. Since the formed dross 34 has already solidified by the time the processed product 33 is separated from the scrap material 31, it does not weld to the processed product 33, and the processed product 33 is held in place by the dross 34 from the back side. For this reason, in the sorting of the processed product 33, there is no need to cut any uncut parts such as joints, and the processed product 33 can be easily separated from the surface side, making it highly compatible with automatic sorting devices. Furthermore, the processed product 33 cut from the workpiece 30 using the above method does not have any marks left on the cut surface, such as joint cut marks.

[0018] In this manner, the laser processing apparatus 100 irradiates the workpiece 30 with a first laser beam along a first cutting path 21a that follows the outer shape of the workpiece 33 on the upper surface which the laser beam 1 is irradiated, thereby forming a cutting groove 35. When the irradiation position of the first laser beam reaches the first endpoint 211a, the irradiation of the first laser beam is stopped, and according to a predetermined program code, a piercing hole 32 for dross formation is made through at least one location in the end material 31 on the end material 31 side of the already cut portion of the workpiece 33, and a second laser beam is irradiated to form dross 34 on the lower surface of the end material 31.

[0019] The dross 34 needs to be formed in a position suitable for holding the workpiece 33, that is, a position closer to the workpiece 33. To control this, it is necessary to set the piercing position and processing conditions according to the plate thickness of the workpiece 30. For example, when cutting a 2.3 mm thick cold-rolled steel plate (Steel Plate Cold Commercial, SPCC) with a nozzle 18 having a gas injection hole diameter of φ2.5 mm, the assist gas pressure is normally set to 1.0 to 1.5 MPa during cutting. However, if dross 34 is formed under the same conditions, the gas pressure is too strong and the formed dross 34 will scatter before it can solidify. Therefore, the conditions for dross formation are set to about 0.1 MPa, which is about 1 / 10 of the value during normal cutting.

[0020] Figure 5 is a top view of the dross formed by the laser processing apparatus according to Embodiment 1. Figure 6 is a side view of the dross formed by the laser processing apparatus according to Embodiment 1. The high-temperature area 81 between the dross-forming piercing hole 32 and the cutting groove 35 has a small heat capacity and is prone to melting due to high temperature caused by laser heating during piercing. Therefore, if the dross-forming piercing hole 32 is formed at a position offset by a distance A from the cutting groove 35 toward the scrap material 31, the dross 34 is pulled toward the cutting groove 35 by surface tension. At the same time, the dross 34 is pushed toward the cutting groove 35 by the gas pressure of the assist gas 2 and pops out slightly, forming and solidifying in a position suitable for holding the processed product 33.

[0021] In other words, if the workpiece 30 has a plate thickness that allows for piercing, it is theoretically possible to form a dross 34 for the purpose of holding the workpiece 33, and this method is applicable to workpieces 30 with thicker plate thicknesses compared to a joint that leaves an uncut portion.

[0022] Figure 7 shows the state in which dross is formed on a thin plate-thickness workpiece using the laser processing apparatus according to Embodiment 1. Furthermore, in the case of a thin plate-thickness workpiece 30 in which the amount of dross 34 generated is small, as shown in Figure 7, after piercing the dross-forming piercing hole 32, a cutting groove 37 for dross formation is formed along the cut surface for about 1.0 to 3.0 mm to increase the melting area of ​​the scrap material 31, thereby forming dross 34 of the size necessary to support the processed product 33. At this time, if the cutting speed of the workpiece 30 is fast, the formed dross 34 will scatter before it can solidify, so the dross 34 is formed at a low speed of about 100 to 300 mm / min.

[0023] Under the above processing conditions, if the assist gas pressure is set low when piercing the dross-forming piercing hole 32, spatter scattering may contaminate the optical system inside the processing head 13. As a countermeasure, when piercing the dross-forming piercing hole 32, the same normal processing conditions as when cutting are used, and when forming the dross 34, the processing conditions are changed from the control used when forming the cutting groove 35 to generate the dross 34.

[0024] If spatter scattered during piercing of the dross-forming piercing hole 32 adheres to the surface of the workpiece 33, a processing path is required that pierces the dross-forming piercing hole 32 at a position away from the workpiece 33 and approaches the workpiece 33 while cutting. Figure 8 shows an example in which the cutting groove for approaching from the piercing hole is straight in the laser processing apparatus according to Embodiment 1. As shown in Figure 8, if a bend occurs in the processing path consisting of the cutting groove 36 for approaching from the dross-forming piercing hole 32 and the cutting groove 37 for dross formation, a high-temperature area 81 is generated not only between the cutting groove 37 and the cutting groove 35 for dross formation, but also at the inner corner of the bend, causing dross 34 to concentrate. Here, a bend refers to a situation where the connection between the cutting groove 36 for approaching from the dross-forming piercing hole 32 and the cutting groove 37 for dross formation has a radius of curvature smaller than a preset value. Figure 9 shows an example in which the cutting groove for approaching from the piercing hole is curved in the laser processing apparatus according to Embodiment 1. As shown in Figure 9, by making the cutting groove 36 approaching from the dross-forming piercing hole 32 a curved trajectory and bringing it closer to the workpiece 33, a high-temperature area 81 can be formed only between the cutting groove 37 and the cutting groove 35, so that no bends occur in the processing path consisting of the cutting groove 36 approaching from the dross-forming piercing hole 32 and the cutting groove 37 for dross formation. If the radius of curvature of the curved trajectory of the cutting groove 36 approaching from the dross-forming piercing hole 32 is small, the dross 34 concentrates towards the center of curvature of the curve. Conversely, if it is large, the solidification position of the dross 34 is dispersed between the cutting groove 37 and the cutting groove 35 for dross formation and towards the center of curvature of the curve, and the size of the dross 34 becomes smaller. Therefore, the radius of curvature of the cutting groove 36 approaching from the dross-forming piercing hole 32 is set in the range of 1 to 10 mm depending on the processing conditions and plate thickness.

[0025] Figure 10 shows an example of a case in which the width of the cutting groove for approaching from the dross-forming piercing hole and the cutting groove for dross formation change in a laser processing apparatus according to Embodiment 1. As shown in Figure 10, if the groove width of the cutting groove 37 for dross formation changes drastically from the groove width of the cutting groove 36 for approaching from the dross-forming piercing hole 32, a high-temperature area 81 will be generated in the part where the groove width changes. For this reason, processing conditions are set so that the groove width of the cutting groove 37 for dross formation does not change drastically from the groove width of the cutting groove 36 for approaching from the dross-forming piercing hole 32.

[0026] Thus, when forming dross 34 at a distance greater than a preset distance from the dross-forming piercing hole 32, the first laser beam is irradiated along the path the processing head 13 moves from the dross-forming piercing hole 32 to the dross-forming position to cut the workpiece 30 and form a cutting groove 36 for approaching from the dross-forming piercing hole 32. After the processing head 13 reaches the dross-forming position, the laser beam is switched to a second laser beam, making the path the processing head 13 moves to the dross-forming position a curved path with a radius of curvature greater than or equal to a preset value, and suppressing abrupt changes in groove width between the cutting groove 36 for approaching from the dross-forming piercing hole 32 and the cutting groove 37 for dross formation.

[0027] Figure 11 shows an example of a laser processing apparatus according to Embodiment 1 in which the portion to be formed of dross is cut into a slit shape. If the width of the cutting groove 35 is wider than a preset width and the workpiece 33 cannot be held even if the size of the dross 34 is increased, after the dross 34 is formed, the portion to be formed of dross 34 is cut into a slit shape with the first laser beam as shown in Figure 11, and thermal strain is used to bring the dross 34 closer to the workpiece 33. In the method of supporting the workpiece 33 with dross 34, in principle there is no need to press the workpiece 33 from the side, so even if the cutting groove 38 for slit formation is formed to be long and narrow, there is no problem in supporting the workpiece 33 as long as it can withstand the load of the workpiece 33.Therefore, the method of supporting the workpiece 33 with dross 34 has the advantage of being less constrained by the groove width of the cutting groove 35.

[0028] Assist gas 2 can be oxygen, nitrogen, air, or mixtures thereof. However, when oxygen is used, the dross 34 oxidizes, resulting in a lower intensity compared to when nitrogen is used. Therefore, if the intensity of the dross 34 is required, the gas should be switched to an oxygen-free gas or air or a mixture with a low oxygen ratio during the formation of the dross 34. In other words, if the first gas, which is assist gas 2 injected simultaneously with the irradiation of the first laser beam, is a gas that promotes the oxidative combustion reaction of the workpiece 30, the second gas, which is assist gas 2 injected when the second laser beam is irradiated, should be switched to a gas that does not oxidize or burn, or a mixture with an oxygen ratio that is less prone to oxidative combustion. After the formation of the dross 34, when resuming irradiation of the first laser beam from the position where irradiation of the first laser beam was stopped, the assist gas 2 should be switched back to the first gas.

[0029] Under processing conditions where the cutting area becomes hot, especially when oxygen is used as the assist gas 2, the area between the cutting groove 35 and the dross-forming piercing hole 32 is prone to melting during piercing, and it may not be possible to form dross 34 in a position suitable for holding the workpiece 33. As a countermeasure, the elapsed time after the formation of the cutting groove 35 at the dross 34 formation location is recorded, and dross 34 formation is carried out after a time has elapsed when it is estimated that the temperature has decreased to a certain extent and stabilized. In other words, although normally the shortest path is followed to each dross 34 formation location, it is better to follow the path from the position with the longest elapsed time first to form the dross 34. Alternatively, the workpiece 30 may be forcibly cooled by spraying water, or the offset distance between the cutting groove 35 and the dross-forming piercing hole 32 may be changed according to the time elapsed after the cutting groove 35 was formed. Furthermore, multiple of the above methods may be combined. Furthermore, it is also effective to use pulsed output for the second laser beam after piercing the dross-forming piercing hole 32, and to suppress the temperature rise between the cutting groove 35 and the dross-forming piercing hole 32 when forming the dross 34.

[0030] If the workpiece 33 sinks lower than the scrap material 31 due to thermal distortion caused by the irradiation of the laser beam 1 onto the workpiece 30, it becomes impossible to form dross 34 in a position suitable for holding the workpiece 33. Therefore, if the workpiece 30 has a plate thickness that is prone to thermal distortion, or if the shape of the workpiece 33 is such that it is prone to thermal distortion, a threshold is set for the cutting distance, and the cutting distance is reset by interrupting the cutting before thermal distortion occurs, generating a path in which the process of forming dross 34 is repeated alternately. In other words, if the cutting groove exceeds a preset threshold for the cutting distance, and there is a location in the already cut section where dross 34 can be formed, the laser processing apparatus 100 interrupts the cutting before the laser beam 1 reaches the first endpoint 211a, moves to the dross 34 formation position to form the dross 34, and after the dross 34 is formed and the cutting distance is reset, the irradiation of the laser beam 1 is resumed from the position where the irradiation of the laser beam 1 was stopped.

[0031] Similarly, if the nozzle 18 that injects the assist gas 2 passes directly over other processed parts 33 after cutting and separation, there is a risk that the processed parts 33 may fall or stand up. Therefore, it is desirable to move the nozzle 18 along a path that does not pass directly over the processed parts 33 after cutting and separation. If it is unavoidable for the nozzle 18 to pass directly over the processed parts 33 after cutting and separation, the injection of the assist gas 2 should be stopped, or the nozzle 18 should be moved upward to a distance where the processed parts 33 will not move due to the injection of the assist gas 2, before the nozzle 18 passes over the processed parts.

[0032] In a method of holding a workpiece 33 by hooking it with dross 34, if the center of gravity CG1 of the workpiece 33 is outside the polygon formed by connecting the formation positions of the dross 34 with straight lines, that is, if the center of gravity of the workpiece 33 is outside the support base surface 331, the moment around the workpiece 33 is unstable and the workpiece 33 cannot be properly held. Therefore, as shown in Figure 4, the number and position of the formation points of the dross 34 are determined so that the position of the center of gravity CG1 of the workpiece 33 is inside the support base surface 331, and then the laser processing program code is generated.

[0033] Figure 12 shows an example of the offset shape extraction process by the program code generation device according to Embodiment 1. First, as shown in Figure 12, an offset shape 61 is extracted on the outer circumference of the workpiece 33 by the distance between the cutting groove 35 and the piercing hole 32 for dross formation. In Figure 12, the outer shape of the workpiece 33 is shown with a dashed line, and the offset shape 61 is shown with a solid line. Figure 13 shows an example of the process of decomposing the offset shape into a point cloud by the program code generation device according to Embodiment 1. As shown in Figure 13, the program code generation device 40 decomposes the extracted offset shape 61 into a point cloud 63. Here, we take the example of dividing each straight line portion of the offset shape 61 into four parts of five points. Among the point cloud 63 shown in Figure 13, the corners of the workpiece 33 are highly likely to have the dross 34 come loose due to thermal distortion. Figure 14 shows an example of the process of excluding the corners of the workpiece from the candidate dross formation positions by the program code generation device according to Embodiment 1. As shown in Figure 14, the program code generation device 40 prevents the dross 34 from becoming loose due to thermal distortion by excluding the corners of the workpiece 33 from the candidate positions for dross 34 formation.

[0034] Figure 15 shows an example of the process by the program code generation device according to Embodiment 1 in which only the point cloud of the convex hull is used as a candidate for the formation position of the dross. If the number of points in the point cloud 63 is large, the computational load described later will increase, so as shown in Figure 15, the program code generation device 40 may use only the point cloud 63 of the convex hull as a candidate for the formation position of the dross 34.

[0035] Figure 16 shows an example of the process by the program code generation device according to Embodiment 1 for excluding overlapping points between candidate dross formation locations and work support pivots from the candidate dross formation locations. If the position information of the work support pivot 62 that contacts the workpiece 33 is known, the program code generation device 40 adds a process to exclude overlapping points 85 between candidate dross formation locations 34 and work support pivot 62 from the candidate dross formation locations 34, so that the dross formation location 34 does not overlap with the position of the work support pivot 62, as shown in Figure 16.

[0036] Furthermore, the position information of the work support pivot point 62 is added to the candidate formation positions of the dross 34 to calculate the support base surface 331 for the workpiece 33, and the center of gravity CG1 of the workpiece 33 is set inside the support base surface 331.

[0037] The support base surface 331 is a polygon formed by connecting the formation locations of the dross 34 and the positions of the work support pivots 62 with straight lines. Ideally, the number of dross formation points 34 should be kept to a minimum, and the moment around the workpiece 33 should be more stable. Therefore, a process is performed to determine the polygon formed by connecting the formation locations of the dross 34 and the positions of the work support pivots 62 with straight lines such that the shortest distance between each side and the centroid CG1 is maximized, and the number of vertices is minimized.

[0038] Specifically, first, calculations are performed by brute force for all combinations of selecting 3 points from the point cloud of candidate dross formation locations 34, and the triangle that maximizes the shortest distance D1 between each side and the centroid CG1 of the workpiece 33 is found. Figure 17 shows an example of a triangle that maximizes the shortest distance between the centroid of the workpiece and each side, selected from the point cloud of candidate dross formation locations by the program code generation device according to Embodiment 1. If there are multiple triangles that satisfy this condition, the comparison point is changed to the second shortest, third shortest, and so on, until one triangle is finally determined. Next, one point is added to the point cloud 63 of candidate dross formation locations 34, and the same calculation is performed for a quadrilateral.

[0039] By repeating this process, the polygon with the minimum number of vertices that maximizes the shortest distance D1 between each side and the centroid CG1 can be obtained. Figure 18 shows an example of the polygon with the minimum number of vertices that maximizes the shortest distance D1 between each side and the centroid, extracted by the program code generation device according to Embodiment 1. Figure 19 shows an example of the relationship between the polygon with the minimum number of vertices that maximizes the shortest distance D1 between each side and the centroid, extracted by the program code generation device according to Embodiment 1, the shape of the workpiece, and the position of the work support pivot point. The workpiece 33 can be held stably because the shortest distance D1 between each side and the centroid CG1 of the workpiece 33 is greater than the distance D2 between the workpiece separation position 88 and the centroid CG1 of the workpiece 33. However, this process may result in an excessive number of dross formation points. Therefore, to suppress the number of dross formation points, an upper limit may be set on the number of vertices, or the number of vertices may not be increased if the change in the shortest distance D1 between each side and the centroid CG1 does not exceed a specified rate even when the number of vertices is increased. Figure 20 shows an example of a case in which the program code generation device according to Embodiment 1 suppresses the number of dross formation points by utilizing the extracted work support pivots. If the change in the shortest distance between each side and the centroid CG1 in a polygon including the work support pivots 62 does not exceed a specified percentage compared to the case where the shortest distance is not the distance between the side connecting the work support pivots 62 and the centroid CG1, then processing such as prioritizing the suppression of the number of dross formation points 34 by utilizing the work support pivots 62 may be added, as shown in Figure 20.

[0040] Furthermore, the program code generation device 40 simultaneously determines the polygon that will serve as the support base surface 331 and selects the position for cutting and separating the workpiece 33 from the point cloud 63. When cutting and separating the workpiece 33, there is a risk that the workpiece 33 may fall or stand up due to the injection of assist gas 2. By setting the cutting and separation position inside the polygon, the workpiece 33 can be separated in a state where the moment around the workpiece 33 is stable. Therefore, the program code generation device 40 selects the point inside the support base surface 331 that is closest to the center of gravity CG1 as the workpiece separation position 88. Figure 21 shows an example of a workpiece shape in which the workpiece separation position cannot be set inside the support base surface set by the program code generation device according to Embodiment 1. Examples of cases where the program code generation device 40 cannot set the workpiece separation position 88 inside the support base surface 331 include cases where the program code generation device 40 limits the number of vertices of the polygon, or cases where the workpiece 33 is circular in shape with no recesses on its outer surface, as shown in Figure 21, and the separation position of the workpiece 33 cannot be set inside the support base surface 331.

[0041] In this case, a workpiece separation position 88 is set around the support base surface 331, and a process is added to move the injection position of the assist gas 2 toward the support base surface 331 by the shortest distance immediately after cutting and separation, thereby preventing the workpiece 33 from falling and rising. Figure 22 is a diagram showing an example of code generated by the program code generation device according to Embodiment 1, which causes the laser processing device to perform a process to move the injection position of the assist gas toward the support base surface immediately after cutting and separation. In Figure 22, the movement of the injection position of the assist gas 2 toward the support base surface 331 immediately after cutting and separation is indicated by arrow A. After that, the nozzle 18 is raised to a height where the effect of the assist gas 2 on the moment around the workpiece 33 can be ignored, or the injection of the assist gas 2 is stopped and the next operation is performed.

[0042] If the processed product 33 is heavy, or if a strong downward load is applied to the surface of the processed product 33 due to the use of an automatic sorting device, the dross 34 may not be able to withstand the load and may break. Therefore, the load applied to each dross 34 is calculated by combining the position and weight of the center of gravity CG1 of the processed product 33 with the downward load applied to the processed product 33 by the injection of assist gas 2 and the automatic sorting device, etc., against the load capacity of each dross 34, and the formation position and number of dross 34 are set so as not to exceed the load capacity. In principle, although the processing time increases as the number of dross 34 formation points increases, no resistance is generated when sorting the processed product 33, and there is no impact on sorting workability or the automatic sorting device.

[0043] If there is a risk that the scrap material 311 inside the processed product 33, such as a punched hole, will rise up and come into contact with the processing head 13 and other operating equipment such as an automatic sorting device, causing it to stop, then dross 34 will be formed to prevent the scrap material 311 from rising up. In this case, contrary to the case of the processed product 33, the shape of the scrap material 311 offset to the inner circumference is decomposed into a point cloud 63, and dross 34 is formed at the vertices of a polygon formed by connecting the points of the convex hull from the point cloud 63, excluding the corners, as in the case of holding the processed product 33. If the centroid CG2 of the scrap material 311 and the work support pivot point 62 are inside this polygon, the scrap material 311 will be held without rising up. However, since the number of points for forming dross 34 may be excessive, processing may be added to limit the number of points for forming dross 34, allowing for an increased risk of the scrap material 311 rising up, or not increasing the number of vertices if the rate of change in the area overlapping between the polygon and the scrap material shape does not reach a specified percentage.

[0044] Figure 23 shows an example in which the center of gravity of the scrap material inside the workpiece is located outside a polygon formed by connecting the dross formation positions set by the program code generation device according to Embodiment 1 with straight lines, and the work support pivot point is located inside the polygon. As shown in Figure 23, if three points of dross 34 are formed in a circular shape, and the formation positions of the dross 34 are set so that the center of gravity CG2 of the scrap material 311 inside the workpiece 33 is located inside the polygon, the scrap material 311 inside the workpiece 33 will be held without falling or standing up if the work support pivot point 62 is located inside the polygon.

[0045] Figure 24 shows an example in which the center of gravity of the scrap material inside the workpiece is located outside a polygon formed by connecting the dross formation positions set by the program code generation device according to Embodiment 1 with straight lines, and the workpiece support pivot point is located outside the polygon. As shown in Figure 24, if the position of the center of gravity CG2 of the scrap material 311 inside the workpiece 33 is outside the polygon formed by connecting the dross formation positions 34 with straight lines, the scrap material 311 cannot be held and will fall.

[0046] If the position information of the work support pivot point 62 that contacts the scrap material 31 is known, the necessary and sufficient formation positions and number of dross 34 can be set based on the position information. Figure 25 shows an example of code generated by the program code generation device according to Embodiment 1 that causes the laser processing device to perform a process to form 2 dross points on a circular scrap material. For example, as shown in Figure 25, if there is one work support pivot point 62 that contacts the circular scrap material 311, the program code generation device 40 generates code to form 2 dross points 34. In that case, the program code generation device 40 sets the position of each dross 34 such that the work support pivot point 62 does not overlap with the straight line passing through the position of each dross 34, and the distance D3 between the two straight lines passing through the position of each dross 34 and the work support pivot point 62 and the center of gravity CG2 of the scrap material 311 inside the processed product 33 is maximized, and the scrap material separation position 89 is located within the first region 86. Here, the first region 86 is the region that does not include the location of each dross 34 among the two regions formed on the end material 311 by the two straight lines. In Figure 25, the region corresponding to the first region 86 is shown with shading.

[0047] In addition, by setting the end material separation position 89 of the end material 311 to the position where the distance D4 between the position of each dross 34 and the work support pivot point 62 is maximized, the moment around the end material 311 is stabilized, and the upward movement of the end material 311 can be prevented. Figure 26 is a diagram showing an example of code generated by the program code generation device according to Embodiment 1, which causes the laser processing device to perform a process to form two dross points on a circular end material. As shown in Figure 26, when there are multiple work support pivot points 62 in contact with the circular end material 311, and other work support pivot points 62 also coincide on a line passing through the work support pivot point 62 and the center of gravity CG2 of the end material 311 inside the processed product 33, the program code generation device 40 considers only one of the overlapping work support pivot points 62 as an effective pivot point and generates code to form two dross points 34, similar to the case when there is only one work support pivot point 62 in contact with the circular end material 311.

[0048] Figure 27 shows an example of code generated by the program code generation device according to Embodiment 1, which causes the laser processing device to perform a process to form a single dross on a circular piece of scrap material. As shown in Figure 27, when there are two work support pivot points 62 that contact the circular piece of scrap material 311, the program code generation device 40 generates code to form a single dross 34. In this case, the program code generation device 40 sets the position of the dross 34 such that the position of the dross 34 does not overlap with the straight line passing through each work support pivot point 62, and the scrap material separation position 89 is located within the second region 87. Here, the second region 87 is the region that is on the side of the center of gravity CG2 of the scrap material 311 inside the processed product 33, rather than the region that does not include the position of the dross 34, among the two regions formed on the scrap material 311 by the position of the dross 34 and the two straight lines passing through each work support pivot point 62 and the straight line passing through each work support pivot point 62. Note that in Figure 27, the region corresponding to the second region 87 is shown with shading. By setting the end piece separation position 89 at the position where the distance D4 between the position of the dross 34 and the two lines passing through each work support pivot point 62 is maximized, the moment around the end piece 311 can be stabilized, preventing the end piece 311 from rising.

[0049] If there are three or more work support pivot points 62 in contact with the scrap material 311 and the center of gravity CG2 of the scrap material 311 inside the processed product 33 is inside the polygon formed by connecting each work support pivot point 62 with a straight line, and the moment around the scrap material 31 does not become unstable due to the injection of assist gas 2 when the scrap material 31 is cut and separated, then it is naturally not necessary to form dross 34. Figure 28 is a diagram showing an example of code generated by the program code generation device according to Embodiment 1 that causes the laser processing device to perform a process to form dross at one point on a circular scrap material. As shown in Figure 28, if there are three or more work support pivot points 62 in contact with the scrap material 311 and the center of gravity CG2 of the scrap material 311 inside the processed product 33 is outside the polygon formed by connecting each work support pivot point 62 with a straight line, the program code generation device 40 divides the cases into combinations of extracting two points from the work support pivot points 62 that are in contact with the circular scrap material 311, and performs similar calculations to set the position of dross 34 at one point. Furthermore, even if the center of gravity CG2 of the scrap material 311 inside the processed product 33 is inside the polygon formed by connecting each work support pivot point 62 with a straight line, if the moment around the scrap material 311 becomes unstable due to the injection of assist gas 2 when the scrap material 311 is cut and separated, the program code generation device 40 sets the position of the dross 34 to one point, similar to the case where the center of gravity CG2 of the scrap material 311 inside the processed product 33 is outside the polygon formed by connecting each work support pivot point 62 with a straight line. By having the laser processing device 100 execute a code that satisfies these conditions, the moment around the scrap material 311 can be stabilized, and the rising of the scrap material 311 can be prevented.

[0050] If dross 34 is formed on the scrap material 311 side, the processed product 33 and the scrap material 311 are separated when the processed product 33 is lifted up during sorting, so the sorting work required for the scrap material 311 does not increase separately.

[0051] Thus, the laser processing apparatus 100 according to Embodiment 1 can prevent the processed product 33 from becoming inseparable from the scrap materials 31 and 311.

[0052] Next, the hardware configuration of the control unit 16 of the laser processing apparatus 100 according to Embodiment 1 will be described. Figure 29 is a diagram showing an example of the hardware configuration for realizing the control unit of the laser processing apparatus according to Embodiment 1. The control unit 16 of the laser processing apparatus 100 is realized as a computer system by a processing circuit that includes a processor 91 that performs various processes, a memory 92 which is the main memory, and a storage device 93 that stores information.

[0053] The processor 91 may be a computing device such as an arithmetic unit, microprocessor, microcomputer, CPU (Central Processing Unit), or DSP (Digital Signal Processor). The memory 92 may be a non-volatile or volatile semiconductor memory such as RAM (Random Access Memory), ROM (Read Only Memory), flash memory, EPROM (Erasable Programmable Read Only Memory), or EEPROM (Electrically Erasable Programmable Read Only Memory). The storage device 93 stores a program for executing processes related to the relative movement of the processing head 13 and the workpiece 30, and laser processing using the laser beam 1 and assist gas 2. The processor 91 reads the program stored in the storage device 93 into the memory 92 and executes it. The functions of the control unit 16 are realized when the processor 91 reads the program stored in the storage device 93 into the memory 92 and executes it.

[0054] The program code generation device 40, like the control unit 16 of the laser processing device 100, can also be realized as a computer system using the processing circuit shown in Figure 29.

[0055] The configurations shown in the above embodiments are merely examples of the content, and can be combined with other known technologies. It is also possible to omit or modify parts of the configuration without departing from the gist of the invention. [Explanation of symbols]

[0056] 1 Laser beam, 1a Optical axis, 2 Assist gas, 11 Laser oscillator, 12 Optical path, 13 Processing head, 14 Drive unit, 15 Detection unit, 16 Control unit, 17 Lens, 18 Nozzle, 21 Processing gas supply source, 21a First cutting path, 21b Second cutting path, 30 Workpiece, 30c Processing point, 31, 311 Scrap material, 32 Piercing hole for dross formation, 33 Processed product, 34 Dross, 35, 36, 37, 38 Cutting groove, 39 Piercing for cutting, 40 Program code generation device, 50 Work support, 61 Offset shape, 62 Work support pivot point, 63 Point cloud, 81 High temperature area, 86 First region, 87 Second region, 88 Processed product separation position, 89 Scrap material separation position, 91 Processor, 92 Memory, 93 Storage device, 100 Laser processing apparatus, 211 cutting path, 211a first endpoint, 211b second endpoint, 331 support base.

Claims

1. A laser processing apparatus that performs a cutting process in which a workpiece is separated into a workpiece and scrap material by irradiating the workpiece with a laser beam and spraying an assist gas onto the workpiece, A processing head having a nozzle for injecting the assist gas onto the workpiece, and irradiating the workpiece with the laser beam, A drive unit for moving at least one of the workpiece and the machining head, The system includes a control unit that controls the irradiation of the laser beam, The control unit, Control to form a cutting groove by irradiating the workpiece with a first laser beam along a predetermined cutting path that follows the outer shape of the workpiece on the upper surface which is the surface irradiated with the laser beam, Control to stop the irradiation of the first laser beam when the irradiation position of the laser beam reaches a first endpoint predetermined in the middle of the cutting path, The control system, according to a predetermined program code, involves drilling a piercing hole for dross formation through at least one location in the end material on the end material side of the already cut portion of the workpiece, and irradiating it with a second laser beam different from the first laser beam to form dross protruding toward the workpiece on the lower surface of the end material so as to hold the workpiece, and A laser processing apparatus characterized by performing the following control: after the formation of the dross, the irradiation of the first laser beam is restarted from the first endpoint and the first laser beam is irradiated onto the workpiece up to the second endpoint, which is the endpoint of the cutting path, thereby cutting and separating the workpiece from the workpiece.

2. The control unit, When forming the dross at a distance greater than a predetermined distance from the piercing hole for dross formation, Control for cutting the workpiece in the path along which the processing head moves from the piercing hole for dross formation to the position where the dross is formed, Control to switch to the second laser beam after the processing head reaches the dross formation position, The laser processing apparatus according to claim 1, characterized in that the path for moving the processing head to the dross formation position is a curved path with a radius of curvature greater than or equal to a preset value, and control is performed to suppress abrupt changes in the groove width of the cutting groove when switching to the second laser beam.

3. The control unit, The laser processing apparatus according to claim 1, characterized in that, if the width of the cutting groove is wider than a preset width, a slit is formed with the first laser beam after the dross is formed, and the dross is controlled to move closer to the workpiece side by thermal strain.

4. The control unit, If the first gas, which is the assist gas that is injected simultaneously with the irradiation of the first laser beam, is a gas species that promotes the oxidative combustion reaction of the workpiece, Control to switch the second gas, which is the assist gas injected when irradiating with the second laser beam, to a gas species that does not undergo oxidative combustion, or a mixed gas with an oxygen ratio that is less susceptible to oxidative combustion, The laser processing apparatus according to claim 1, characterized in that, after the formation of the dross, when the irradiation of the first laser beam is restarted from the position where the irradiation of the first laser beam was stopped, control is performed to return the assist gas to the first gas.

5. The control unit, When the second laser beam is irradiated to multiple locations, The laser processing apparatus according to claim 1, characterized in that it performs either one of the following: a control that moves the irradiation area of ​​the second laser beam along the shortest path to form the dross, or a control that moves the processing head along a path that sequentially follows the irradiation area with the longest elapsed time since cutting by the first laser beam to form the dross.

6. The control unit, When irradiating with the second laser beam, The laser processing apparatus according to claim 5, characterized in that it performs at least one of the following: control to make the second laser beam a pulse output; control to spray water onto the workpiece; and control to adjust the offset distance between the cutting groove and the dross-forming piercing hole according to the elapsed time.

7. The control unit, If the cutting groove exceeds a predetermined threshold for the cutting distance, and there is a location in the already cut portion where the dross can be formed, After interrupting the cutting before reaching the first endpoint, the control moves to the dross formation position and irradiates with the second laser beam to form the dross, After the formation of the dross and the reset of the cutting distance, control is performed to restart the irradiation of the first laser beam from the position where the irradiation of the first laser beam was stopped. The laser processing apparatus according to claim 1, characterized in that it repeatedly performs the formation of the cutting groove and the formation of the dross on a single processed product.

8. The control unit, When the nozzle passes directly over the processed product after cutting and separation, The laser processing apparatus according to claim 1, characterized in that it performs any of the following: control to stop the injection of the assist gas; control to raise the processing head to a distance where the workpiece does not move due to the injection of the assist gas; and control to change the movement path of the processing head to a path where the nozzle does not pass directly over the workpiece after cutting and separation.

9. The laser processing apparatus according to any one of claims 1 to 8, characterized in that the control unit performs the following actions: irradiate the second laser beam onto at least one predetermined location of the scrap material inside the processed product to form the dross; and, after the dross is formed, restart the irradiation of the first laser beam from the first endpoint to cut and separate the scrap material inside the processed product.

10. A laser cutting method is used to perform a cutting operation on a workpiece supported from the back by a work support, by irradiating the workpiece with a laser beam from a processing head having a nozzle for injecting assist gas into the workpiece, thereby separating the workpiece into a workpiece and scrap material. A process of forming a cutting groove by irradiating the workpiece with a first laser beam along a predetermined cutting path that follows the outer shape of the workpiece on the upper surface which is the surface irradiated with the laser beam, A process to stop the irradiation of the first laser beam when the irradiation position of the laser beam reaches a first endpoint predetermined in the middle of the cutting path, The process involves, according to a predetermined program code, drilling a piercing hole for dross formation through at least one location in the end material on the end material side of the already cut portion of the workpiece, and irradiating it with a second laser beam different from the first laser beam to form dross protruding toward the workpiece on the lower surface of the end material so as to hold the workpiece, A laser processing method characterized by comprising the steps of: after the formation of the dross, resuming irradiation of the first laser beam from the first endpoint and irradiating the workpiece with the first laser beam up to the second endpoint, which is the endpoint of the cutting path, thereby cutting and separating the workpiece from the workpiece.

11. When forming the dross at a distance greater than a predetermined distance from the piercing hole for dross formation, The processing head has a nozzle for injecting the assist gas onto the workpiece, and controls the cutting of the workpiece in a path from the dross-forming piercing hole to the dross formation position. The process of switching to the second laser beam after the processing head reaches the dross formation position, The laser processing method according to claim 10, characterized in that the path for moving the processing head to the dross formation position is a curved path with a radius of curvature greater than or equal to a preset value, and a process is performed to suppress abrupt changes in the groove width of the cutting groove when switching to the second laser beam.

12. The laser processing method according to claim 10, characterized in that, when the width of the cutting groove is wider than a preset width, a slit is formed with the first laser beam after the dross is formed, and the dross is brought closer to the workpiece side by thermal strain.

13. When the first gas, which is the assist gas that is injected simultaneously with the irradiation of the first laser beam, is a gas species that promotes the oxidative combustion reaction of the workpiece, A process to switch the second gas, which is the assist gas injected when irradiating with the second laser beam, to a gas species that does not undergo oxidative combustion, or a mixed gas with an oxygen ratio that is less susceptible to oxidative combustion, The laser processing method according to claim 10, characterized in that, after the formation of the dross, when resuming irradiation of the first laser beam from the position where irradiation of the first laser beam was stopped, the assist gas is returned to the first gas.

14. When the second laser beam is irradiated to multiple locations, The laser processing method according to claim 10, characterized in that it performs either one of the following steps: moving the irradiation area of ​​the second laser beam along the shortest path to form the dross; or moving the processing head, which has a nozzle for injecting the assist gas onto the workpiece, along a path that sequentially follows the irradiation area from the irradiation area with the longest elapsed time since cutting by the first laser beam to form the dross.

15. When irradiating with the second laser beam, The laser processing method according to claim 14, characterized by performing at least one of the following: a process of converting the second laser beam into a pulse output; a process of spraying water onto the workpiece; and a process of adjusting the offset distance between the cutting groove and the dross-forming piercing hole according to the elapsed time.

16. If the cutting groove exceeds a predetermined threshold for the cutting distance, and there is a location in the already cut portion where the dross can be formed, After interrupting the cutting before reaching the first endpoint, the process involves moving to the dross formation position and irradiating it with the second laser beam to form the dross, After the formation of the dross and the reset of the cutting distance, the irradiation of the first laser beam is restarted from the position where the irradiation of the first laser beam was stopped. The laser processing method according to claim 10, characterized in that the formation of the cutting groove and the formation of the dross are repeated for one of the processed products.

17. When the nozzle passes directly over the processed product after cutting and separation, The laser processing method according to claim 10, characterized by performing one of the following: stopping the injection of the assist gas; raising the processing head to a distance where the workpiece does not move due to the injection of the assist gas; or changing the movement path of the processing head to a path where the nozzle does not pass directly over the workpiece after cutting and separation.

18. A laser processing method according to any one of claims 10 to 17, characterized by: irradiating the second laser beam onto at least one predetermined location of the scrap material inside the processed product to form the dross; and, after the formation of the dross, restarting the irradiation of the first laser beam from the first endpoint to cut and separate the scrap material inside the processed product.

19. A program code generation device that generates program code to instruct a cutting path for a laser processing device that performs a cutting process in which a workpiece supported by a work support from the back surface is irradiated with a laser beam and an assist gas is sprayed onto the workpiece to separate the workpiece into a workpiece and scrap material, The aforementioned program code is: A code for setting a path to form a cutting groove by irradiating the first laser beam along the outer shape of the workpiece on the upper surface, which is the surface to which the laser beam is irradiated, of the workpiece to be processed, A code that sets the center of gravity of the workpiece within a support base, which is a polygon formed by connecting the positions where dross is formed on the lower surface of the already cut end of the workpiece by irradiating the end piece with a second laser beam, and if the position information of the work support pivot point that contacts the end piece inside the workpiece is known, then calculates the support base by adding the position information of the work support pivot point to the work support pivot point, after ensuring that the dross formation position does not overlap with the position of the work support pivot point, and sets the center of gravity of the workpiece within the support base, and A program code generation device characterized by including a code for determining the number of dross formation points and formation positions necessary for the processed product to withstand the load.

20. The aforementioned program code is: A code that sets the support base surface in a shape that allows for setting a position inside which the workpiece is cut and separated from the workpiece, The program code generation device according to claim 19, characterized in that, if the position for cutting and separating the workpiece cannot be set inside the support base surface, or if the position for cutting and separating the workpiece is intentionally not set inside the support base surface, the program code generation device includes a code that adds control to move the injection position inside the support base surface by the shortest distance if the moment around the workpiece, taking into account the injection pressure of the assist gas, becomes unstable immediately after cutting and separating the workpiece from the workpiece.

21. The code for determining the number and location of dross formations necessary for the aforementioned processed product to withstand the load is: The program code generation device according to claim 19, characterized in that it includes a code that calculates the load applied to each of the dross by combining the center of gravity position and weight of the workpiece with the downward load applied to the workpiece by the injection of the assist gas or sorting device, against a pre-set load capacity per dross location, and sets the formation position and number of dross locations so as not to exceed the load capacity per dross location.

22. The program code generation apparatus according to claim 19, characterized in that the program code includes a code that sets the dross formation position while avoiding the corners of the workpiece.

23. If there is one work support pivot point that contacts the end material inside the workpiece, two dross points are formed, and the positions of the dross are set such that the work support pivot points do not coincide with the straight lines passing through the positions of each dross, the distance between the two straight lines passing through the positions of each dross and the work support pivot points and the center of gravity of the end material inside the workpiece is maximized, and the end material separation position is located in a first region that is closer to the center of gravity of the end material inside the workpiece than the two straight lines passing through the positions of each dross and the work support pivot points, and the workpiece separation position is set at a position where the distance from the straight lines passing through the positions of each dross is maximized, and the code is generated. If there are two work support pivot points inside the workpiece that contact the end material, and another work support pivot point lies on a straight line passing through the work support pivot point and the center of gravity of the end material inside the workpiece, then only one of the overlapping work support pivot points is treated as the valid work support pivot point, and the code is generated in the same way as when there is one work support pivot point inside the workpiece that contacts the end material. If there are two work support pivot points inside the workpiece that contact the end material, and no other work support pivot points lie on a straight line passing through the work support pivot point and the center of gravity of the end material inside the workpiece, then a code is generated to set the position of the dross so that the distance between the position of the dross and each of the work support pivot points and the center of gravity of the end material inside the workpiece is maximized, and the end material separation position is located in a second region which does not include the position of the dross, among the two regions formed in the end material inside the workpiece by the two straight lines passing through the position of the dross and each of the work support pivot points and the straight line passing through each of the work support pivot points, and to set the workpiece separation position at a position where the distance between the position of the dross and each of the two straight lines passing through each of the work support pivot points is maximized. If there are three or more work support pivot points inside the workpiece that contact the scrap material, and the center of gravity of the scrap material inside the workpiece lies inside a polygon formed by straight lines connecting the work support pivot points, and the moment around the scrap material inside the workpiece does not become unstable due to the injection of the assist gas when the scrap material is cut and separated inside the workpiece, then a code that does not form dross is generated. A program code generation device according to any one of claims 19 to 22, characterized in that, if there are three or more work support pivot points inside the workpiece that contact the scrap material and the center of gravity of the scrap material inside the workpiece is outside the polygon formed by straight lines connecting the work support pivot points, or even if the center of gravity of the scrap material inside the workpiece is inside the polygon formed by straight lines connecting the work support pivot points, the moment around the scrap material becomes unstable due to the injection of the assist gas when the scrap material is cut and separated, the device divides into combinations of extracting two of the work support pivot points, sets the position of the dross such that the distance between the position of the dross and each of the work support pivot points and the center of gravity of the scrap material inside the workpiece is maximized, and the dross is located within a second region enclosed by the two straight lines passing between the position of the dross and each of the work support pivot points and the straight line passing through each of the work support pivot points, and generates a code that sets the workpiece separation position at the position where the distance between the position of the dross and each of the two straight lines passing through each of the work support pivot points is maximized.

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