JP6567794B1 - Laser processing method and laser processing machine - Google Patents

Abstract

The generation position of the shock wave in the assist gas (AG) freely ejected from the nozzle (2b) used for cutting the workpiece by the laser light is grasped. Among all the gap ranges (Ga) that can be set as the gap (G) that is the distance between the tip of the nozzle (2b) and the surface of the workpiece (W), there is an appropriate gap range (G1) that does not include at least the position where the shock wave is generated. Is set. The workpiece (W) is cut with the gap (G) set to a value within the appropriate gap range (G1).

Description

  The present disclosure relates to a laser processing method and a laser processing machine for cutting a workpiece using an assist gas.

  Patent Document 1 describes a laser processing machine that uses an assist gas to cut a workpiece with a laser. The laser processing machine described in Patent Document 1 includes a so-called copying apparatus, and cuts a workpiece while maintaining a gap, which is a distance between the workpiece and a nozzle tip, at a predetermined value. For example, when a laser beam machine cuts a stainless steel plate having a thickness of about 1 to 2 mm, the gap is generally set within a range of 0.3 to 0.5 mm.

JP 2017-131897 A

  From the viewpoint of increasing the efficiency of workpiece cutting, it is desired that a product with a good cut surface can be cut out from the workpiece in as short a time as possible. On the other hand, with the development of technology, the output of laser light is constantly increasing. In the cutting process of a workpiece by laser light, the higher the laser beam output, the faster the cutting becomes possible, and the processing time can be further shortened.

  However, when the relative speed between the machining head and the workpiece is increased for high-speed cutting, there may be a problem that gap maintenance control by the copying apparatus cannot follow.

  For example, the force received from the injected assist gas may cause the workpiece surface to vibrate in a direction that approaches or separates from the machining head, making it difficult to maintain the gap and causing the machining head to collide with the workpiece. is there. As another example, if there is a foreign substance on the surface of the workpiece, the machining head for avoiding the foreign substance may not rise in time, and a problem may occur in which the machining head collides with the foreign substance.

  A problem to be solved by one or more embodiments is to provide a laser processing method and a laser processing machine that are less likely to cause defects even when a processing head is moved at a high speed and can cut a workpiece. .

  According to the first aspect of the one or more embodiments, the generation position of the shock wave in the assist gas ejected from the nozzle used for cutting the workpiece by the laser beam is grasped in advance, and the tip of the nozzle And an appropriate gap range that does not include at least the shock wave generation position among all gap ranges that can be set as a gap that is a distance between the workpiece and the surface of the workpiece, and the gap is set to a value within the appropriate gap range. A laser processing method for cutting the workpiece is provided.

  According to the second aspect of the one or more embodiments, a condition set comprising a combination of a flow path shape of a nozzle used for cutting a workpiece with laser light and a gas pressure of an assist gas, and the nozzle The gap between the tip of the nozzle and the surface of the workpiece is appropriately determined according to the shock wave generation position in advance, and the correspondence relationship with the shock wave generation position in the assist gas freely ejected with the gas pressure from A range is set, an effective setting range of the gap is set according to the appropriate gap range, a table in which a plurality of the condition sets and the effective setting range are associated is created, and the table set in the table A laser processing method for setting a gap in cutting processing based on an effective setting range is provided.

  According to the third aspect of the one or more embodiments, a condition set comprising a combination of a flow path shape of a nozzle used for cutting a workpiece with laser light and a gas pressure of an assist gas, and the nozzle Based on the effective setting range set in the table, a storage unit storing a table in which the effective setting range set according to the shock wave generation position in the assist gas ejected freely from A laser processing machine including a gap setting unit that sets a gap that is a distance between the tip of the nozzle and the surface of the workpiece is provided.

  According to one or more embodiments, even if the machining head is moved at a high speed, it is difficult to cause defects, and the workpiece can be cut.

FIG. 1 is a diagram showing a schematic overall configuration of a laser beam machine according to one or more embodiments. FIG. 2 is a longitudinal sectional view of the nozzle 2 b attached to the laser processing machine 51. FIG. 3 is a table showing a relationship between the gap G and the processing speed V and the cutting ability in the cutting processing by the laser processing machine 51. FIG. 4 is a schematic diagram of the observation result of the free jet AGa from the nozzle 2b by the Schlieren method. FIG. 5 is a table showing a relationship example between the shock wave position of the assist gas AG and the inappropriate gap range G2 in the cutting process by the laser beam machine 51. FIG. 6 is a schematic diagram showing the relationship between the shock wave position of the assist gas AG and the inappropriate gap range G2. FIG. 7 is a flowchart showing an example of a procedure for setting the valid setting range Gy. FIG. 8 is a diagram illustrating an example of the gap table Tg used for setting the effective setting range Gy. FIG. 9 is a flowchart showing an example of a procedure for selecting the valid setting range Gy.

  A laser processing machine and a laser processing method according to one or more embodiments will be described with reference to a laser processing machine 51 of an example and a laser processing method performed using the same.

  FIG. 1 is a diagram showing a schematic overall configuration of a laser beam machine 51. The laser processing machine 51 moves at least one of the work table 1, the processing head 2 that irradiates the work W placed on the work table 1 with the laser light Ls, and the work table 1 and the processing head 2. Are provided with a drive unit 3 for changing the three-dimensional relative position, and a control device 5 for controlling operations of the machining head 2 and the drive unit 3.

  Further, the laser processing machine 51 includes a laser oscillator 6 that supplies a laser beam Ls to the processing head 2 and an assist gas source 7 that supplies an assist gas AG such as nitrogen to the processing head 2.

  The machining head 2 includes a cylindrical main body 2a having an axis CL2 extending in the vertical direction (vertical direction) as an axis, a nozzle 2b removably attached to the lower end of the main body 2a, and a tip 2b1 of the nozzle 2b. A sensor 2c that measures a nozzle gap G (hereinafter simply referred to as a gap G), which is a distance from the surface Wa of the workpiece W placed on the workpiece table 1, is provided.

  FIG. 2 shows an example of a vertical cross-sectional shape of the nozzle 2b. The nozzle 2b is a so-called Laval nozzle. A Laval nozzle is also called a critical nozzle. The nozzle 2b can be detachably attached to the lower portion of the main body 2a with screws. In FIG. 2, the outer shape of the main body portion 2a in a state where the nozzle 2b is screwed is indicated by a one-dot chain line.

  The nozzle 2b has a flow path Ra of the assist gas AG extending up and down around the axis line CL2 while being attached to the main body 2a. The nozzle 2b has a base tube portion 2b2 having an inner diameter Da as a part of the flow path Ra. A nozzle channel portion 2b3 having a throat portion 2bt is connected to the downstream side of the base tube portion 2b2.

  The nozzle channel portion 2b3 is formed with a smaller diameter than the inner diameter Da of the base tube portion 2b2. The nozzle channel portion 2b3 has a throat portion 2bt at an intermediate position in the vertical direction of the channel Ra, and the throat portion 2bt has a minimum diameter Db, that is, a minimum cross-sectional area. The nozzle flow path part 2b3 has a flow path whose flow path cross-sectional area expands on both the upstream side and the downstream side from the throat part 2bt. The lower end of the nozzle flow path part 2b3 is opened as the opening part 2b5 in the front-end | tip part 2b1.

  Returning to FIG. 1, the control device 5 includes a central processing unit (CPU) 11, a storage unit 12, a copying management unit 13, and a gap setting unit 14.

  The machining program PG and the gap table Tg for cutting the workpiece W are supplied from the outside via a communication interface (not shown) and stored in the storage unit 12. Details of the gap table Tg will be described later.

  In the cutting process, the CPU 11 controls the operations of the laser oscillator 6 and the drive unit 3 so that the laser beam Ls is irradiated onto the workpiece W along the cutting path defined by the processing program PG. The laser light Ls is emitted downward on the axis CL2 through the opening 2b5 of the nozzle 2b.

  When the workpiece W is cut using the assist gas AG, the CPU 11 also controls the supply operation of the assist gas AG by the assist gas source 7. The assist gas AG is injected downward as a flux having a predetermined cross-sectional shape including the axis CL2 (for example, a flux having a circular cross section).

  The laser processing machine 51 can satisfactorily perform laser cutting even in a wide gap region where the gap G is 1 mm or more. Therefore, in the laser processing machine 51, the gap G is set based on the effective setting range Gy obtained in advance so that good cutting can be performed in the wide gap region.

  The examination based on the experiment by the inventor has revealed the existence of a fact that a gap range that cannot be satisfactorily cut may occur in the wide gap region due to the influence of the shock wave of the assist gas AG. Based on this fact, a procedure for setting the gap G that can be cut satisfactorily and a configuration that realizes the procedure (detailed later) are obtained.

  The laser processing machine 51 obtains in advance a gap range that can always be satisfactorily cut without being affected by the shock wave as the effective setting range Gy, and the gap G is basically maintained within the effective setting range Gy in laser cutting processing. It is comprised so that.

  Next, a method for obtaining the effective setting range Gy will be described including the concept (background) that led to obtaining the effective setting range Gy.

  First, in order to obtain the knowledge of the cutting ability when the workpiece W made of iron-based material is cut with the gap G set to a wide gap region of 1 mm or more, the inventor conducted a cutting experiment described below. Specifically, in the laser processing machine, the conditions other than the gap G were set to the same conditions, and the gap G was changed stepwise in the wide gap region for cutting. And the cutting property for every gap G was evaluated.

  More specifically, the workpiece W was made of a stainless steel plate having a thickness of 1.0 mm, and the nitrogen assist gas AG was ejected from the nozzle 2b at a nozzle internal pressure Pn of 0.6 MPa to cut the workpiece W.

As the laser oscillator 6, a fiber laser capable of supplying a laser beam Ls with an output capable of sufficiently cutting a stainless steel plate having a thickness of 1.0 mm was used even when the gap G was 6.5 mm in a wide gap region. However, the laser type is not limited to the fiber laser, and may be a direct diode laser or a CO ₂ laser. Further, the gap G is changed stepwise at a pitch of 0.5 mm in the range of 0.5 to 6.5 mm, and cutting is performed at different processing speeds V between the lowest speed Va and the highest speed Vh in each gap. Then, the cutting property was evaluated. The processing speed V is a relative speed between the processing head 2 and the workpiece W.

The cutting performance was evaluated by the dross height (the dross protrusion height from the surface) generated on the surface opposite to the machining head 2 at the cut portion of the workpiece W. The evaluation stage was set to the following four stages from the lowest in height, including the inability to cut.
◎: Dross height low: Very good cutting possible ○: Medium dross height: Good cutting ability △: Dross height height: Slightly bad but can be cut ×: Uncuttable Figure 3 shows the cutting process. It is the table | surface which showed the cutting property evaluation result, Comprising: It is the matrix which expand | deployed the processing speed V in the column (horizontal) and the gap G in the row (vertical).

  From the results shown in FIG. 3, an appropriate gap range G1 that can be cut substantially satisfactorily regardless of the processing speed V, and cutting is generally possible regardless of the processing speed V, but the cutting ability is inferior to that of the appropriate gap range G1. It became clear that there was an appropriate gap range G2.

  Specifically, when the gap G, which is a wide gap region, is in the range of 1.0 to 6.5 mm, the appropriate gap range G1 is the range G1a in which the gap G is 1.0 to 2.5 mm, and 4.0 to 4.0. There are two ranges with a range G1b of 5.5 mm. In addition, as the inappropriate gap range G2, there are two ranges, a range G2a in which the gap G is 3.0 to 3.5 mm and a range G2b in which the gap G is 6.0 to 6.5 mm.

  In this result, it is understood that the two inappropriate gap ranges G2 appear with a pitch of approximately 3.25 mm. For this reason, it is inferred that there is a shock wave that is known to be generated by a high-speed jet of the assist gas AG ejected from the tip 2b1 of the nozzle 2b.

  Therefore, using the nozzle 2b, the assist gas AG is set to the same internal pressure Pn of 0.6 Mpa as the above conditions, and the free jet AGa that is freely ejected without the workpiece W is observed by the Schlieren method to confirm whether or not a shock wave is generated. did. Hereinafter, this test is referred to as a shock wave generation confirmation test.

  FIG. 4 is a schematic diagram showing an observation result of the shock wave generation confirmation test. As shown in FIG. 4, a plurality of shock waves At were observed in the free jet AGa of the assist gas AG. Looking at the range of the distance from the tip 2b1 of the nozzle 2b to 12 mm, three shock waves At1 to At3 were observed in this example.

  Each of the shock waves At1 to At3 is generated at positions of a distance Lt1, a distance Lt2, and a distance Lt3 downward from the distal end portion 2b1. In this example, the pitch Pt in the direction of the axis CL2 of each of the shock waves At1 to At3 is substantially constant 4 mm. That is, the shock waves At1 to At3 appear downward from the front end portion 2b1 at positions of approximately 4 mm, 8 mm, and 12 mm.

  By comparing the result of FIG. 3 with the result of FIG. 4, the vertical position of the tip 2b1 of the nozzle 2b is set as a reference 0 (zero). It is confirmed that the lower position substantially corresponds to the position where the shock wave At1 is generated in the free jet AGa. More specifically, it is understood that a range from the position where the shock wave At is generated to several mm (1 to 2 mm) on the nozzle 2b side corresponds to the inappropriate gap range G2.

  That is, the presence / absence and generation mode of the shock wave of the assist gas AG in the cutting process of the workpiece W can be estimated by the generation presence / absence and generation mode of the shock wave in the free jet AGa of the assist gas AG without the workpiece W. It was revealed.

  Based on this result, when the output of the laser beam Ls is so large that the maximum value Gm of the gap G that can be cut can be set in a wide gap region exceeding 1 mm, the gap G to be specified in actual machining is determined. It is derived that the effective setting range Gy should be set as follows. The range from the reference 0 to the maximum value Gm is defined as the entire gap range Ga. The effective setting range Gy may be set based on a range obtained by removing the inappropriate gap range G2 from the entire gap range Ga, that is, the appropriate gap range G1.

  Specifically, the effective setting range Gy is set to be the same as or included in the appropriate gap range G1. In other words, the effective setting range Gy is a range of the gap G that should be set in order to obtain good cutting performance even in high-speed machining.

  That is, the generation position of the shock wave At when the assist gas AG is freely ejected is preliminarily grasped with the nozzle 2b and the nozzle internal pressure Pn used for the actual cutting process, and the effective setting range Gy is determined based on the generation position of the shock wave At. Therefore, it is possible to perform a favorable cutting process even in a wide gap region.

  In this case, since the gap G is set to a wide gap of 1 mm or more, even if the relative movement speed of the machining head 2 and the workpiece W is increased, the machining head 2 is vibrated finely in the vertical direction or the workpiece W. There is almost no possibility of colliding with foreign matter adhering to the surface Wa. Therefore, there is almost no problem caused by moving the machining head 2 at high speed, and the work W can be cut at high speed with good cutting performance.

  As described above, since there is a relation between the vertical position and range of the inappropriate gap range G2 and the vertical direction position of the shock wave generation, only the shock wave generation mode in the free jet AGa is observed and understood in advance. The effective setting range Gy may be set directly from the generated shock wave generation position.

  For example, the effective setting range Gy can be set to a range obtained by excluding a predetermined vertical range including a position where a shock wave is generated from the entire gap range Ga. As another example, the effective setting range Gy may be set to a range excluding a predetermined vertical range in which the position where the shock wave is generated is the far end side. Here, the position where the shock wave is generated may be the far end, or a position close to the position where the shock wave is generated may be the far end.

  In the above other example, the case where the shock wave generation position is the far end will be specifically described. As shown in FIGS. 5 and 6, for example, the vertical width of the inappropriate gap range G2 is estimated to be α (mm) from other experimental results. Then, let Ltk be the distance from the tip 2b1 of the nozzle 2b to the position of the kth (k is an integer equal to or greater than 1) shock wave, and the range to be an inappropriate gap range G2 is based on the tip 2b1 of the nozzle 2b. The position of Ltk (mm) is in the range from the position of (Ltk−α) mm to Ltk (mm) with the far end as the position.

  This procedure is also executed for two or more k to estimate the inappropriate gap range G2 shown in FIG. 5, and an effective setting range Gy considering the shock wave generation position where k is 2 or more is set.

  Thus, the effective setting range Gy that is desirable as the setting range of the gap G in the cutting process may be set as follows. The effective setting range Gy is a range from the total gap range Ga to the inappropriate gap range G2 from the position of Ltk (mm) to the position of (Ltk−α) mm with reference to the tip 2b1 of the nozzle 2b. It is good to set it as the range corresponding to the suitable gap range G1 excepted, or the range included in the suitable gap range G1.

  A specific procedure example for obtaining the above-described effective setting range Gy will be described with reference to a flowchart shown in FIG. First, the assist gas AG is freely ejected using the nozzle 2b used for the cutting process in a state where there is no workpiece W and under the same conditions as the cutting process of the workpiece W. The same condition is that the components of the assist gas AG and the nozzle internal pressure Pn are matched. Then, the free jet AGa is observed by the Schlieren method (Step 1).

  Whether or not shock waves are generated in the observation is determined (Step 2). If it is determined that no shock waves are generated (NO), the entire gap range Ga is set to the effective setting range Gy (Step 3). This is because the shock wave is not generated in the free jet AGa, and therefore it is estimated that the entire gap range Ga corresponds to the appropriate gap range G1, and it is determined that good cutting is possible in any gap within the entire gap range Ga. By being done.

  When it is determined in (Step 2) that a shock wave is generated (YES), it is determined whether or not a shock wave is generated in the entire gap range Ga (Step 4). If it is determined NO (NO) in (Step 4), the process proceeds to (Step 3). This is because no shock wave is generated in the entire gap range Ga that can be set as the gap G, and it is determined that the same setting as (Step 3) is possible.

  If it is determined in (Step 4) that a shock wave is generated (YES), the distance Lt from the tip 2b1 of the nozzle 2b to the generation position is measured for the shock wave in the entire gap range Ga (Step 5). When there are a plurality of shock waves, each distance Lt is measured.

  Based on the measured distance Lt, the inappropriate gap range G2 is estimated and set (Step 6). An upper and lower range including the distance Lt, or a range from the distance (Lt−α) to the distance Lt with the distance Lt as the far end using the preset width value α described above is an inappropriate gap range. Set to G2. In order to set the inappropriate gap range G2 with higher accuracy, not the estimation but the performance of the cutting performance described with reference to FIG. 3 is obtained, and the performance is compared with the distance Lt. Is desirable.

  Next, a range obtained by excluding the inappropriate gap range G2 set in (Step 6) from the entire gap range Ga is set as an appropriate gap range G1. Then, the effective setting range Gy is set within the appropriate gap range G1 in accordance with the appropriate gap range G1 (step 7). Specifically, the effective setting range Gy is set to be the same as the appropriate gap range G1 or set to be included in the appropriate gap range G1. In other words, the effective setting range Gy is set so as not to exceed the appropriate gap range G1.

  As a result, the gap G within the effective setting range Gy set in the actual cutting process is always included in the appropriate gap range G1, so that good cutting performance can be obtained.

  Further, as a result of conducting the above-described shock wave generation confirmation test by the inventor with the nozzle 2b and the nozzle internal pressure Pn having different flow path shapes, the shock wave generation position and the generation interval at the time of generation of the shock wave are the same nozzle internal pressure Pn. However, it was confirmed that when the flow path shape is different, the mode is different. Here, the different channel shapes mean that at least one of the channel cross-sectional area, the channel cross-sectional shape, the channel vertical cross-sectional shape, and the channel length is different.

  Further, it was confirmed that even if the nozzles 2b have the same flow path shape, the nozzles 2b generally have different modes when the nozzle internal pressure Pn is different.

  That is, it has been found that the presence / absence and generation mode of the shock wave depend independently on at least the flow path shape of the nozzle 2b and the nozzle internal pressure Pn of the assist gas AG.

  Therefore, a gap table Tg is created in which the effective setting range Gy of the gap G obtained in the above-described procedure is obtained and associated in advance for each condition of the flow path shape of the nozzle 2b and the assist gas AG in the laser cutting process. The storage unit 12 of the laser processing machine 51 stores a gap table Tg. The laser processing machine 51 reads the effective setting range Gy corresponding to the laser cutting processing conditions from the gap table Tg, and controls the gap G at the time of cutting based on the read effective setting range Gy.

  FIG. 8 shows a configuration example of the gap table Tg. The gap table Tg is a table in which one effective setting range Gy is associated according to the combination of the type of nozzle 2b and the nozzle internal pressure Pn, and the effective setting range Gy can be determined. Specifically, nine types of combinations of three types (N1 to N3) of different flow channel shapes of the nozzle 2b used for laser cutting and nozzle internal pressures Pn1 to Pn9 are associated with the effective setting ranges Gy1 to Gy9, respectively. ing.

  Of course, the table may be combined with parameters other than the type of nozzle 2b and the nozzle internal pressure Pn (work material, work thickness, etc.). In the gap table Tg shown in FIG. 8, the nozzles N1 to N3 have different types (flow path shapes and the like), and the plurality of nozzle internal pressures Pn applied to the same nozzle 2b have different values.

  On the other hand, the same value may exist regarding the nozzle internal pressure Pn between different nozzles N1-N3. For example, the nozzle internal pressure Pn5 and the nozzle internal pressure Pn8 may be equal. Moreover, the same range may exist in the effective setting ranges Gy1 to Gy9.

  Based on the gap table Tg shown in FIG. 8, the selection procedure of the effective setting range Gy performed by the laser processing machine 51 in the actual cutting process will be described with reference to the flowcharts shown in FIGS.

  The gap setting unit 14 of the control device 5 grasps the parameter set defined in the gap table Tg from the cutting conditions specified by the machining program PG stored in the storage unit 12 (Step 11). In the example shown in FIG. 8, the parameter group is a condition group composed of a combination of the flow path shape of the nozzle 2b and the nozzle internal pressure Pn.

  The gap setting unit 14 refers to the gap table Tg stored in the storage unit 12 and reads the effective setting range Gy associated with the grasped parameter set (Step 12). The read effective setting range Gy is set as a range that the gap G can take in the cutting processing to be executed (Step 13).

  During the cutting process, the copying management unit 13 manages the vertical drive control by the drive unit 3 so that the gap G is maintained within the set effective setting range Gy.

  The CPU 11 controls the above series of operations. Further, when the copying management unit 13 is not provided or when the copying operation is turned off, the gap G is set to an arbitrary numerical value within the effective setting range Gy by a user input or an instruction by communication from the outside. Then, the CPU 11 controls the operation so as to maintain the value.

  According to the laser processing method using the laser processing machine 51 described in detail above, even if the gap G is set wide, the influence of the shock wave generated in the assist gas AG is avoided and a good cutting property is obtained. A gap G is set. As a result, even if the machining head 2 is moved at a high speed, collision between the machining head 2 and the workpiece W or foreign matter is avoided, and cutting with good cutting performance can be performed with almost no problems.

  The present invention is not limited to the above-described one or more embodiments, and various modifications can be made without departing from the scope of the present invention.

  As described above, the cutting process is not limited to a process involving copying control. Cutting may be performed with the copying control turned off. The laser beam machine 51 can perform cutting by setting the gap G to 1 mm or more, which is larger than the conventional one, regardless of whether the scanning control is on or off. It is avoided and high-speed and high-quality cutting can be performed.

  The control device 5 may not be provided in the laser processing machine 51. For example, the control device 5 may be arranged separately from the laser processing machine 51 in the vicinity of the laser processing machine 51 or at a remote position so that it can communicate with the laser processing machine 51 wirelessly or by wire. Although the nozzle internal pressure Pn is described as the pressure of the assist gas AG, the pressure of the assist gas AG is not limited to the pressure in the nozzle 2b. For example, the pressure of the assist gas AG may be managed by the internal pressure of the main body 2a.

  The type of nozzle 2b (flow path shape type) is not limited to the Laval nozzle. A so-called tapered nozzle whose diameter on the downstream side of the flow path is reduced in a tapered shape may be used. Moreover, even if it is any type, you may have the part where a flow-path cross-sectional area becomes constant with the same shape along a flow path.

  The following was further clarified by observation and examination of the assist gas AG freely ejected from the nozzle 2b by the Schlieren method performed by the inventor. When the nozzle 2b is a Laval nozzle, the internal pressure Pn is increased or the nozzle flow path portion 2b3 is lengthened as compared to the case of a tapered nozzle, so that the first shock wave generation position from the tip 2b1 of the nozzle 2b is increased. When the distance Lt1 and a plurality of shock waves are generated, the second and subsequent intervals Pt1 tend to be longer.

  It is preferable that the distance Lt1 is long because the proportion of the appropriate gap range G1 in the entire gap range Ga is increased and the degree of freedom in setting the gap G is increased. Further, it is preferable that the distance Lt1 is long because the vertical width of one appropriate gap range G1 is large, so that the setting and control of the gap G is facilitated.

  Therefore, regardless of the type difference such as whether the nozzle 2b is a Laval nozzle or a tapered nozzle, when the shock wave generation position is grasped from the free jet AGa of each of the plurality of nozzles 2b having different flow channel shapes, the entire gap range Ga The number of generated shock waves Ns is confirmed, and when the number of generated Ns is plural, the interval Pt (corresponding to the pitch Pt1 described above) may be measured with high accuracy. Then, when there are a plurality of types of nozzles 2b that can satisfactorily cut a workpiece W having a certain plate thickness, a nozzle with a small number of generated Ns is selected. In the case where there are a plurality of nozzles 2b having the same generation number Ns among the plurality of types of nozzles 2b, the nozzle 2b having the longest interval Pt may be selected.

  As a result, the optimum nozzle 2b having the largest occupation ratio in the gap range G1 and having a wide vertical width can be selected and used from the nozzles 2b that can perform cutting well under desired conditions.

The disclosure of the present application is related to the subject matter described in Japanese Patent Application No. 2017-202405 filed on Oct. 19, 2017, the entire disclosures of which are incorporated herein by reference.
It should be noted that various modifications and changes may be made to the above-described embodiments without departing from the novel and advantageous features of the present invention other than those already described. Accordingly, all such modifications and changes are intended to be included within the scope of the appended claims.

Claims (6)

Preliminarily grasp the generation position of the shock wave in the assist gas ejected freely from the nozzle used to cut the workpiece by laser light,
Of all the gap ranges that can be set as a gap that is the distance between the tip of the nozzle and the surface of the workpiece, set an appropriate gap range that does not include at least the generation position of the shock wave,
A laser processing method for cutting the workpiece by setting the gap to a value within the appropriate gap range. For each of the plurality of nozzles, grasp in advance the number of shock waves generated in the entire gap range,
The laser processing method according to claim 1, wherein a nozzle that generates the smallest number is selected and used.   3. The laser processing method according to claim 2, wherein, among the plurality of nozzles, when there are a plurality of nozzles having the same number of generations, the nozzle having the widest interval between the generation positions of the shock waves is selected and used. .   The said appropriate gap range is set as a range except the predetermined range which makes the generation | occurrence | production position of the said shock wave the far end side from all the gap ranges which can set the said gap. Laser processing method. A condition set consisting of a combination of the flow path shape of the nozzle used to cut the workpiece with laser light and the gas pressure of the assist gas, and a shock wave generation position in the assist gas that is freely ejected from the nozzle at the gas pressure To understand the relationship
According to the shock wave generation position, set an appropriate gap range of the gap that is the distance between the tip of the nozzle and the surface of the workpiece,
According to the appropriate gap range, set an effective setting range of the gap,
Create a table associating a plurality of the condition sets and the valid setting range,
A gap in cutting is set based on the effective setting range set in the table. According to the condition set consisting of the combination of the flow path shape of the nozzle used for cutting the workpiece with the laser beam and the gas pressure of the assist gas, and the generation position of the shock wave in the assist gas ejected freely from the nozzle A storage unit storing a table in which the set valid setting range is associated;
Based on the effective setting range set in the table, a gap setting unit that sets a gap that is a distance between the tip of the nozzle and the surface of the workpiece in cutting processing;
A laser processing machine.

Images