JP6180240B2 - Laser cutting method - Google Patents

Description

  The present invention relates to a laser cutting method for cutting a material to be cut such as a metal material by laser processing.

  For example, in laser cutting (laser cutting) of a metal material using a CO2 laser or a YAG laser, the focused laser beam is irradiated to the metal material with a predetermined spot diameter (condensed diameter), and the irradiation is performed on the metal material. The cutting is performed while scanning (moving) along the planned cutting line at a predetermined speed and scattering (blowing off) the metal that is melted and evaporated by the heat generated by irradiation with the assist gas. In such laser cutting, since cutting can be performed with substantially the same width as the irradiation spot diameter, cutting with high precision can be obtained, and cutting speed can be easily increased by increasing the laser output. On the other hand, when cutting by increasing the laser output, for example, by a single scan, even when cutting by a pulse laser, the cutting part is likely to be excessively melted due to excessive heat input (concentration of heat). It is difficult for a cut surface having high smoothness (smoothness or surface roughness) to be obtained. For this reason, in order to obtain a high-precision cutting surface with high smoothness, a cutting groove extending in the scanning direction is formed on the surface of the workpiece (workpiece) by scanning with a small laser output, and this cutting is performed. A method of cutting the groove by repeating the scanning a plurality of times may be employed (see, for example, Patent Document 1 (FIG. 4) and Patent Document 2 (second page)). In such a case, for example, when the material to be cut is a noble metal material, in order to reduce the amount of material lost due to evaporation and blowing (material loss), the laser output is made as small as possible and the irradiation spot diameter is made as small as possible. I want to reduce the cutting width (cutting groove width). In particular, when the material to be cut is a small noble metal material (for example, a thin wire having a diameter of about φ1 mm or less), there is a strong demand for cutting with an extremely small cutting width of about 10 μm to about several tens of μm or less. is there. For this reason, in such a cutting | disconnection, the depth of the cutting groove obtained by one scan also becomes small, for example with a unit of several micrometers. Accordingly, in such cutting, if the thickness (or thickness) of the material to be cut is 1 mm, the number of scans may be about 100 times or several hundred times, and inevitably, it takes a long time to complete the cutting. Cost.

  By the way, for example, in the case of cutting a wire by repeating a plurality of scans of the irradiation spot by laser beam irradiation, when it is desired to increase the cutting efficiency or the cutting speed, the scanning is set to repeat the forward path and the backward path. In addition, the scanning is continuously repeated without providing a stop time. However, if such scanning is repeated, even if a pulse laser is used, heat energy is radiated and cooled by heat input of the laser light remaining in the cutting groove (surface) formed in the immediately preceding scan. In the stage where it is not known, the thermal energy is applied by the subsequent scanning. For this reason, at the end of the scanning in the forward path and the backward path, the heat radiation and cooling by the scanning are stopped (waiting for time), and the heat input due to laser light irradiation is excessive compared to the case of entering the next scanning. Tend to. As a result, the melt in the cut groove in the middle of cutting tends to be excessive, and the final smoothness of the cut surface tends to be lowered. As described above, as in the conventional laser cutting method, the scan surface obtained by repeating the scanning many times, gradually increasing the depth of the cutting groove, and finally cutting, has a smoothness. The (surface roughness) tends to decrease, and burrs and spatters are likely to occur at the periphery of the cut surface. Moreover, there also existed a problem that adhesion of the molten material (solidified lump of molten metal) generate | occur | produced in the periphery of the cut back surface side. This problem is easily manifested in the cutting of a thin wire having a small scanning stroke (short planned cutting line), for example.

JP 2012-11409 A JP 2002-103067 A

  Such a problem is apparent from the above, but after the thermal energy remaining in the cutting groove formed by the scanning of the laser beam immediately before is absorbed or cooled by the heat radiation. This can be improved by performing the next scan. For example, when scanning a laser beam a number of times by repeating the scanning of the forward path and the backward path, an idle time (stop time) is provided at the end of each stroke to release and cool the immediately preceding thermal energy. Is performed, and then the next scanning is performed. However, in this way, even if the idle time is 0.1 seconds, for example, if 100 scans are required before cutting, a loss time of 10 seconds occurs for one cutting. As a result, there is a problem that the cutting processing time is prolonged and the processing cost is increased, which is not suitable for a large amount of cutting processing. In addition, such a problem becomes a serious problem particularly when the idle time becomes relatively long with respect to one scanning time as in the case of cutting a thin wire rod. In addition, the more the scanning is performed so that the cut surface has a high degree of smoothness, the greater the influence.

  In such a case, in order to increase the cutting efficiency or cutting speed (to shorten the processing time), the laser output is increased to cut as a relatively rough cut surface, and, for example, the cut surface (cut end surface) is ground in post-processing. Alternatively, it is conceivable that a cut surface having a high smoothness is finally obtained by polishing. However, when cutting by increasing the laser output, the need for post-processing is not limited, and as described above, problems (material loss) due to metal melting and evaporation (cutting width, cutting groove width) are large. . Therefore, in particular, if such a method is adopted for cutting a noble metal accessory, the total cost will increase.

  In the laser cutting (machining), the present invention does not cause a long cutting time due to the setting of the idle time for cooling when cutting by a plurality of scans, and the smoothness. It is an object of the present invention to provide a laser cutting method capable of obtaining a high and clean cut surface.

The present invention according to claim 1 is a cutting groove extending in the scanning direction on the surface of the material to be cut by scanning the laser beam irradiated with a predetermined spot diameter along the planned cutting line of the material to be cut. In the laser cutting method of cutting the material to be cut by repeating the scanning a plurality of times on the cutting groove,
Along the planned cutting line in the material to be cut, within the range of the spot diameter, a plurality of virtual lines for scanning are set by shifting,
Scanning the laser beam with the center of the spot diameter passing through the scanning virtual line is sequentially performed for each of the plurality of scanning virtual lines, thereby forming a cutting groove extending in the scanning direction in each scanning virtual line, It is characterized in that the material to be cut is cut by including a laser processing step in which this one-step scanning process is repeated a plurality of times.

The present invention described in claim 2 is characterized in that the plurality of scanning imaginary lines are set to be shifted within a range of 10% to 90% of the spot diameter. This is a laser cutting method.
According to a third aspect of the present invention, in the scanning imaginary line, the number of the imaginary lines for scanning is two, and the scanning imaginary lines extend in parallel with each other or at equal intervals. 2. The laser cutting method according to item 1.

According to a fourth aspect of the present invention, a round of scanning process of the laser beam includes one of the two virtual scanning lines as an outward path and the other as a backward path, and includes movement of the shift amount. The laser cutting method according to claim 3, wherein the laser cutting method is a circular shape.
The invention according to claim 5 is the laser cutting method according to any one of claims 1 to 4, wherein the material to be cut is a noble metal wire.

  In the laser cutting method of the present invention, based on the above configuration, for example, when two scanning imaginary lines are set, the laser passes through the center of the spot diameter sequentially (alternately) with respect to the two scanning imaginary lines. After the light scanning (one round of scanning), the two cutting grooves are formed so as to extend on each scanning imaginary line so that at least a part thereof overlaps, and the surface of the material to be cut has a concave shape. It is formed. Then, by repeating a single round of scanning a plurality of times, the depth of each cut groove gradually becomes deeper and finally cut. By the way, in the process of repeating such a round of scanning of laser light, when scanning of laser light to deepen one cutting groove is performed, the side closer to the cutting surface on the other cutting groove side The groove wall surface (the groove wall surface including the groove bottom depending on the overlapping state of the cutting grooves) is not irradiated with laser light. Therefore, during the scanning process in one of the cutting grooves, the time for the heat energy remaining due to the previous laser light irradiation to the groove wall near the cutting surface among the other cutting grooves is removed. Will be granted. Therefore, during the scanning process in one cutting groove, the groove wall surface to which the time is given is radiated and cooled. In the process of repeating one round of scanning, alternate scanning is performed. Therefore, when laser scanning is performed on the other cutting groove which is performed next, after the heat radiation and cooling, Since scanning is performed, excessive melting due to excessive heat input at the groove wall surface near the cut surface is prevented in the scanning.

  Thus, according to the present invention, for example, the scanning of the laser light is alternately and repeatedly performed for two cutting grooves. Therefore, while the scanning is repeated, the next time the laser beam is scanned on the cutting groove, the time required for the scanning of the laser beam on the cutting groove is the heat dissipation and cooling. Will be given as time. As a result, when scanning of the laser beam is performed on the cutting groove, the scanning is always performed after heat dissipation and cooling in a given time period. Therefore, the cutting groove in which the scanning is performed is cut. Excessive melting due to excessive heat input at the groove wall surface near the surface is prevented. For this reason, when finally cut | disconnected, generation | occurrence | production of melt | disassembly is prevented in the both cut surfaces which were the groove | channel wall surfaces of the side side part which makes a cut surface among each cut groove, respectively. Thereby, high smoothness is obtained at the cut surface.

  That is, as in the prior art, when scanning continuously over a single cutting groove until it is finally cut, the thermal energy from the scanning of the last laser beam is dissipated and cooled. The laser beam irradiated with the same spot diameter is repeatedly scanned over the remaining cutting groove (surface). For this reason, there is a problem in that heat input is excessive, melting tends to occur, and the smoothness of the final cut surface is liable to be lowered. On the other hand, in the present invention, as described above, since the same cutting groove is not continuously scanned, for example, when two scanning virtual lines are used, one scanning time is automatically set. This is the cooling time for releasing (cooling) the thermal energy remaining on the groove wall surface on the side of the cut surface of the other non-scanned cut grooves. Therefore, the effect of preventing the occurrence of such a problem can be obtained.

  On the other hand, in the case where the same cutting groove is repeatedly scanned as in the conventional cutting method, in order to obtain heat dissipation and cooling time, for example, when scanning with laser light is performed by repeating the forward path and the backward path Since it is necessary to stop scanning at the end (end point) of each stroke and to provide a predetermined stop time, the cutting time is increased. On the other hand, according to the present invention, even if the scanning of the forward path and the backward path is continuously repeated without providing such a stop time, the scanning is performed on the cutting grooves at different (shifted) positions. Therefore, the cooling time for releasing (cooling) the thermal energy remaining on the groove wall on the side forming the cut surface of the other cutting groove not being scanned is automatically secured. Can do. Therefore, since the scanning can be repeated continuously while ensuring the cooling time without providing a stop time, the cutting of the cut surface with high smoothness can be obtained without increasing the time. In the present invention, the laser beam is scanned so that the center of the spot diameter passes through the three or more scanning virtual lines in order, and the material to be cut is obtained by repeating this round of scanning steps. You may make it cut | disconnect.

  It can be said that the plurality of scanning imaginary lines are preferably set to be shifted (different) within a range of 10% to 90% of the spot diameter, as described in claim 2. If it is desired to obtain a cooling effect, it is better to reduce the overlap of spot diameters (cutting grooves) (increase the center distance between spots). As described above, there is no limit on the number of virtual lines for scanning, and therefore, it is possible to perform scanning of three or more. However, as described in claim 3, setting the number to 2 reduces the number of scans. , Cutting efficiency is increased. Even if the number of virtual lines for scanning is 3 or more, after cutting, there are two members with the cut surface interposed therebetween, and each member has a cut surface. For this reason, it is clear that the same operation and effect as described above can be obtained by looking at the two cutting grooves at the side portion forming the cut surface among the cutting grooves before cutting. When the number of the virtual scanning lines is 2, when the planned cutting lines are straight lines as in the third aspect of the present invention, they are preferably set parallel to each other. If not, it should extend at equal intervals.

  For example, if the number of scanning imaginary lines is set to 2 and the overlap of the spot diameters (cutting grooves) is reduced (the center distance between the spots is increased), the entire width of the cutting groove is increased accordingly. Further, since the depth of the entire cutting groove is reduced by the amount of overlap of the cutting grooves, the number of scans until cutting is increased. On the other hand, if the number of virtual scanning lines is set to 2 and the overlap of the spot diameters is increased, the reverse is true. Therefore, in consideration of these factors, the overlap is determined based on various conditions such as the required smoothness of the cut surface, the material of the material to be cut, the size of the location of the cut surface, and appropriate conditions for laser cutting such as laser output. Find it.

  Further, when the number of virtual lines for scanning is two, as described in claim 4, the scanning process of one cycle of the laser light is performed in one of the two virtual lines for scanning. It is preferable that the other is a return stroke and has a circular shape including the shift amount. This is because the scanning direction (traveling direction) may be the same, and two scannings (one round of scanning) may be performed, but in this case, the process of returning from the progressing end of scanning to the start of traveling becomes the loss time. Because. That is, as described in claim 4, when the laser is scanned in a circular manner, such a loss time can be eliminated, so that the cutting efficiency is improved, which is preferable.

  In addition, in the case where one member after cutting is a product and the other member is not a product but is processed (or reclaimed) as a remaining material (for example, chip or scrap), A cut surface with high smoothness is required only for the cut surface on the product side. Therefore, in such a case, the scanning of the laser beam that directly affects the cut surface on the product side and the laser beam that is irradiated and scanned on the portion of the remaining material that does not directly affect the cutting surface side are scanned under the same conditions. Not necessary. Further, for example, the laser beam irradiated to the portion of the remaining material closer to the cut surface may be scanned even if the planned cutting line is a straight line, and therefore may be a zigzag, for example.

  The laser cutting method to which the present invention can be applied is apparent from the above description, but is not limited to the case of cutting the material to be cut in a straight line. The present invention can also be applied to a drilling process in which a circular hole is cut into a flat plate in order to make a circular hole or to obtain a circular plate from the flat plate. Moreover, the case where it cut | disconnects in arbitrary curved shapes, and the case where it cut | disconnects by the arbitrary cutting plan lines which a straight line and a curve continue may be sufficient. Further, the present invention is not limited to these one-dimensional cutting and two-dimensional cutting (scheduled cutting line), and can also be applied to three-dimensional cutting. As is clear from this, in the present application, the smoothness (smoothness) of the cut surface means the smoothness of the cut surface when the cut line is a straight line. Further, the cutting material to which the cutting method of the present invention can be applied is not limited to metals, and can be applied to materials that can be widely used for laser cutting, but is particularly suitable for cutting noble metals. Precious metals are required to minimize the cutting width that will disappear due to evaporation, etc. due to their high cost, and for this purpose, the smoothness of the cut surface is also highly required. This is because it is possible to respond without causing a long cutting time.

The schematic diagram explaining two scanning virtual lines set in the cutting location of the to-be-cut | disconnected material seen from the incident side of the laser beam explaining the embodiment which actualized the laser cutting method of this invention. The schematic diagram explaining the scanning of the laser beam in which the center of the spot diameter passes two virtual lines for scanning in FIG. In FIG. 2, the schematic diagram seen from the arrow X1 direction explaining the process of the repeated scanning until a cutting groove is formed by the scanning of the laser beam which passes through the two virtual lines for scanning, and it reaches a cutting | disconnection. The schematic diagram explaining the state of the groove wall surface of the site | part close | similar to the cut surface of the other cutting groove in the scanning of one cutting groove in the laser processing process of FIG.

  Embodiments embodying the laser cutting method according to the present invention will be described in detail with reference to schematic views (FIGS. 1 to 4) for explaining a cutting state (laser processing step). As shown in FIG. 1, in this example, when the cut portion in the workpiece 100 is viewed in plan, two parallel scanning imaginary lines (straight lines) are parallel to the surface 103 at a predetermined interval (shift amount) K1. ) L1 and L2 are provided so as to be shifted with respect to a planned cutting line (not shown). However, this interval K1 is half the spot diameter (circle diameter) of the laser (pulse laser) to be irradiated. In this example, as shown in FIG. 2, the spot diameter (the pulse shown in FIG. 2) is placed on the upper scanning virtual line L1 in FIG. 1 among the two scanning virtual lines L1 and L2. The laser beam is scanned at a predetermined speed from the left end to the right end so that the center of S) passes through the center of S. Subsequently, as shown in FIG. 2, the laser beam is transmitted from the right end to the left end of the scanning virtual line L2 in the lower part of FIG. Scan at speed. The scanning process (trajectory) is such that the start and end positions of scanning are both located outside the workpiece 100 so as to surely scan the entire length of the scanning virtual lines L1 and L2. Is set. Further, in this example, by scanning the laser light in a rectangular loop shape (clockwise in FIG. 2) including the movement stroke of the mutual interval (shift width) K1 between the two scanning virtual lines L1 and L2, The two scanning virtual lines L1 and L2 are scanned sequentially (alternately). That is, this rectangular circuit-like process is used as a scanning process for one round of laser light, and a cutting groove is formed along each planned cutting line L1, L2, and this laser processing step is repeated a plurality of times continuously. It is said.

  This laser processing step will be described with reference to FIG. In this example, as shown in FIGS. 3A to 3D, the laser beam La is alternately irradiated on the surface 103 of the material to be cut 100 along two planned cutting line lines (scanning directions) L1 and L2. By scanning, two cutting grooves 111 and 112 are formed. The cut grooves formed in this way are overlapped with each other at a width that is about ½ of the spot diameter (diameter) S of the irradiated laser beam La. The depths of the cutting grooves 111 and 112 from the surface 103 of the material to be cut 100 gradually become deeper as shown in FIG. 3A-C, forming one deep cutting groove made of both cutting grooves. Finally, the material to be cut 100 is cut as shown in FIG. The cut surfaces 121 and 122 after being cut in this way are repeatedly scanned with a laser beam passing through the center of the spot diameter on a predetermined cut line as in the past. A cut surface with a higher smoothness than the cut surface obtained by cutting and deepening the cut groove.

  Here, with reference to FIG. 4, a process of obtaining such cut surfaces 121 and 122 with high smoothness will be described. As shown in FIG. 4, in the scanning stroke of the laser beam La along the left (one) cutting groove 111, a cutting surface (FIG. 4) which becomes a cutting surface after cutting out of the right (other) cutting groove 112. The region of the groove wall surface 112a indicated by double hatching is not irradiated with the laser beam La at the portion near the broken line 122 in FIG. For this reason, in the scanning process of the laser beam La along the left (one) cutting groove 111, the groove wall surface 112a near the cutting surface 122 out of the right (other) cutting groove 112 has the previous laser beam. It is possible to dissipate and cool the remaining heat given by irradiation. Therefore, next, when the laser processing is performed to deepen the cutting groove 112 by scanning the laser light along the right (other) cutting groove 112, the groove wall surface 112a near the cutting surface 122 may have excessive heat input. It is possible to prevent excessive melting.

  In this example, since the left and right two cutting grooves (scanning imaginary lines) 111 and 112 are alternately scanned with the laser beam La, such an effect is obtained by the two right and left cutting grooves 111 and 112. It is alternately repeated at 112 and finally leads to cutting. For this reason, the smoothness of the cut surfaces 121 and 122, which are the groove wall surfaces near the cut surface in the cutting process, is the same as that of the conventional cutting groove (scanning imaginary line). It becomes high compared with the case where it cut | disconnects by repeating scanning. That is, when the same scanning is performed continuously and repeatedly along the same cutting groove as in the conventional laser cutting method, the time for heat radiation and cooling of the heat energy remaining on the groove wall surface is reduced. Cannot be positively granted. On the other hand, in the above-described example in which the present invention is embodied, the scanning of the laser beam is performed continuously and repeatedly, but in the scanning process, as described above, the groove wall surface at the portion near the cut surface alternately. In addition, since the time for heat dissipation and cooling can be automatically given, the smoothness of the cut surface when finally cut is higher than the conventional one.

  Also in the conventional laser cutting method, if the stop time is provided at the end of the forward path and the return path of the laser beam scanning, the cooling time can be positively provided. However, if this is done, the cutting time will be lengthened. And in the cutting of precious metals (for example, Pt wire, Pt alloy wire) that require ultra-precise cutting along with reduction of material loss, for example, it is a thin wire rod of φ0.3 mm, and at the cut surface (end surface), In order to secure the smoothness required to perform advanced positioning by abutting with other members after the fact, scanning of laser light about 100 times was required before cutting. For this reason, if an idle time of 0.1 seconds is provided at the end of each scanning process, it takes an extra 10 seconds for one cutting, resulting in a long cutting time. As will be understood from this, in the precision cutting of such a precious metal material, a significant effect can be obtained according to the present invention. Incidentally, the outline of the conditions (parameters such as laser output) when the Pt line of φ0.3 mm is laser-cut by 100 times of scanning by the conventional laser cutting method is as follows. The laser is a pulse laser with a wavelength of 532 nm, the output is 12 W, the laser beam irradiation spot diameter (irradiation condensing diameter) is 10 μm, and the scanning speed is 200 mm / sec. On the other hand, in the above-described example in which the present invention is embodied, in the above-described example in which there are two scanning virtual lines, the shift amount (interval) K1 between the scanning virtual lines L1 and L2 is 5 μm. In addition to the absence of stop time, it was confirmed that cutting was achieved with about 50 scans (about 25 scans performed alternately). This is considered to mean that the heat radiation and cooling of the cut portion by the scanning of the laser light greatly contributes not only to the smoothness of the cut surface but also to the improvement of the cutting efficiency.

  Further, in the above example, since one round of scanning alternately performed on the two scanning imaginary lines (cutting grooves) L1 and L2 is a circular shape along the rectangular side including the shift amount K1, Not only can a cut surface with high smoothness be obtained, but also the cutting time can be shortened. However, the scanning of the laser beam La passing through the two scanning imaginary lines L1 and L2 may be, for example, a repetition of the forward path (the rightward path in FIG. 2). This is suitable when the length of the imaginary scanning line is short, such as a minute member, or when a high degree of smoothness is required by the cut surface. In addition, the drive control of the laser beam scanning may be a drive control that moves either the laser beam side, the workpiece side, or both by known means.

  In the above example, the two scanning imaginary lines L1 and L2 are shifted in parallel by a half of the spot diameter (diameter of the circle) S, that is, the dimension of the radius. That is, it may be set in consideration of cutting conditions such as a material to be cut (for example, its thickness) and laser output within a range where smoothness (or surface roughness) required for the cut surface is obtained. However, the shift amount K1 is preferably in the range of 10% to 90% when the spot diameter (diameter) is 10 μm. As described above, depending on the material to be cut, the number of scanning virtual lines may be three or more.

  In addition, when only the improvement of the smoothness (or surface roughness) of the cut surface of only one member sandwiching the cutting line is required and the cutting surface of the other member sandwiching the cutting line is not required, As is the case, the scanning of the laser beam that scans the cut surface of the other member may be a zigzag instead of a straight line. Further, the laser conditions may be varied such that the scanning speed need not be the same.

  The present invention can be widely applied to a laser cutting method (use of a laser cutting machine) using a CO2 laser, a YAG laser, and other known various lasers. In the above example, the case of using a pulse laser has been described. However, the present invention can also be applied to a continuous wave laser, and has higher smoothness than the conventional case where scanning is repeatedly performed on the same planned cutting line (cutting groove). A cut surface is obtained. In the above example, the case of cutting along a straight line has been described. However, as described above, the present invention can also be applied to the case of cutting along a curved line.

100 Material to be cut 103 Surface 111, 112 of cut material 121, 122 Cut surface S Spot diameter La Laser light L1, L2 Virtual line for scanning

Claims (5)

A laser beam irradiated at a predetermined spot diameter is scanned along the planned cutting line of the material to be cut to form a cutting groove extending in the scanning direction on the surface of the material to be cut, and the scanning is performed on the cutting groove. In a laser cutting method of cutting a material to be cut by repeating a plurality of times,
Along the planned cutting line in the material to be cut, within the range of the spot diameter, a plurality of virtual lines for scanning are set by shifting,
Scanning the laser beam with the center of the spot diameter passing through the scanning virtual line is sequentially performed for each of the plurality of scanning virtual lines, thereby forming a cutting groove extending in the scanning direction in each scanning virtual line, A laser cutting method characterized by cutting a material to be cut by including a laser processing step in which the scanning process performed in this order is repeated a plurality of times.   2. The laser cutting method according to claim 1, wherein the plurality of scanning imaginary lines are set to be shifted within a range of 10% to 90% of the spot diameter.   3. The laser cutting method according to claim 1, wherein the number of scanning imaginary lines is two and extends in parallel with each other or at equal intervals.   One round of the scanning stroke of the laser light is one of the two imaginary lines for scanning, which is an outward path, the other is a backward path, and has a circular shape including the shift movement. The laser cutting method according to claim 3.   The laser cutting method according to claim 1, wherein the material to be cut is a noble metal wire.

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