METHODS FOR THE AUTOMATED DETERMINATION OF THE INFLUENCE OF A LASER PROCESSING PARAMETER ON A LASER PROCESSING OPERATION, LASER PROCESSING MACHINE, AND COMPUTER PROGRAM PRODUCT

Abstract

Methods, machines, and computer program products are disclosed for determining the influence of a laser processing parameter on a laser processing operation by means of a laser beam are described. The methods include conducting linear laser processing operations with different values of the laser processing parameter, the speed of advance of the laser beam, respectively, being increased in the laser processing operations at least to such an extent that a processing interruption occurs; and determining a relationship between the processing lengths, the associated processing times, or the associated interruption speeds of the laser processing operations and the laser processing parameter using the measured processing lengths, the associated processing times, or the associated interruption speeds of the laser processing operations.

Claims

1. A method for determining an influence of a laser processing parameter on a laser processing operation by a laser beam, the method comprising: conducting linear laser processing operations with one or more values of the laser processing parameter being increased in the laser processing operations at least to such an extent that a processing interruption occurs; and determining a relationship between processing lengths, associated processing times, or associated interruption speeds of the laser processing operations and the laser processing parameter using any one or more of the processing lengths, the associated processing times, or the associated interruption speeds of the laser processing operations.

2. The method of claim 1, wherein the method is automated.

3. The method of claim 1, wherein the laser processing parameter is a speed of advance of the laser beam.

4. The method of claim 1, wherein an influence of a cutting parameter on a workpiece processing operation by the laser beam is determined, the method comprising: conducting linear laser cuts on a workpiece with different values of the cutting parameter, wherein a cutting speed, respectively, is increased in the laser cuts at least to such an extent that a cutting interruption occurs; and determining a relationship between cutting lengths, associated cutting times, or associated cutting interruption speeds of the laser cuts and the cutting parameter using any one or more of the cutting lengths, the associated cutting times, or the associated cutting interruption speeds of the laser cuts.

5. The method of claim 1, wherein an influence of a welding parameter on a workpiece processing operation by the laser beam is determined, the method comprising: conducting linear laser penetration welds on a workpiece with different values of the welding parameter, wherein a welding speed, respectively, is increased in the laser penetration welds at least to such an extent that a penetration welding interruption occurs; and determining a relationship between penetration welding lengths, associated welding times, or associated penetration welding interruption speeds of the laser penetration welds and the welding parameter using one or more of the penetration welding lengths, the associated welding times, or the associated penetration welding interruption speeds of the laser penetration welds.

6. The method of claim 1, wherein an influence of a fusion parameter during a fusion of metal powder by the laser beam is determined, the method comprising: producing linear melting tracks with different values of the fusion parameter, wherein a speed of advance of the laser beam, respectively, is increased in the melting tracks at least to such an extent that a melting track interruption occurs; and determining a relationship between melting track lengths, associated fusion times, or associated melting track interruption speeds of the melting tracks and the fusion parameter using one or more of the measured melting track lengths, the associated fusion times, or the associated melting track interruption speeds of the melting tracks.

7. The method of claim 1, wherein the laser processing parameter is a laser beam-related parameter, wherein the laser beam-related parameter is at least one of wavelength, beam quality, intensity distribution, focal position in the beam direction (z), focal diameter, or laser power, and/or wherein the laser processing parameter is a gas-dynamic parameter for a predetermined gas composition determined by nozzle type, nozzle diameter, distance of the nozzle and the workpiece.

8. The method of claim 3, wherein the speed of advance is increased stepwise or continuously.

9. The method of claim 1, wherein the laser beam is turned off when reaching the processing interruption.

10. The method of claim 1, wherein the parameter value for which the processing length, or the associated processing time, or the associated interruption speed of the laser processing operations is maximal is determined as the optimal parameter value.

11. The method of claim 10, wherein the optimal parameter value is determined by interpolation of the processing lengths of the laser processing operations, of the associated processing times, or of the interruption speeds.

12. The method of claim 10, wherein the optimal parameter value is an optimal focal position of the laser beam in the beam direction, and wherein the laser processing operations are carried out with different focal positions of the laser beam in the beam direction.

13. The method of claim 12, wherein the optimal focal position of the laser beam in the beam direction is respectively determined for different laser powers, and wherein a power-dependent focal shift is determined therefrom.

14. The method of claim 10, wherein the optimal parameter value to be determined is a focal diameter of the laser beam, and wherein the laser processing operations are carried out with different focal diameters of the laser beam.

15. The method of claim 10, wherein with a nominally equal laser power and nominally equal focal diameter, the method is carried out for different values of the laser processing parameter focal position of the laser beam in the beam direction at two different instances in time, and wherein either a variation of the laser power impinging on a processing plane or a variation of the focal diameter in the processing plane of the laser beam is established by comparison of the respectively determined relationships between the processing lengths, the associated processing times, or the associated interruption speeds of the laser processing operations and the laser processing parameter focal position of the laser beam in the beam direction.

16. A laser processing machine comprising a laser beam generator that produces a laser beam; a laser processing head, from which the laser beam emerges; a workpiece base or powder base, both of which are movable relative to one another; and a machine controller programmed to increase a speed of advance of the laser beam in the laser processing operations at least to such an extent that a processing interruption occurs.

17. The laser processing machine of claim 16, further comprising an interruption detector for detecting a processing interruption.

18. The laser processing machine of claim 16, further comprising a data memory in which a processing length, a processing time, or an interruption speed, as well as an associated value of a laser processing parameter, are stored as stored data.

19. The laser processing machine of claim 18, wherein the machine controller is programmed to determine a relationship between the processing length, the associated processing time, or the associated interruption speed and the laser processing parameter in an automated fashion using the stored data.

20. A computer program product comprising a computer readable media including one or more computer programs configured to carry out all steps of the method of claim 1 when the computer programs run on a machine controller of a laser processing machine.

Description

DESCRIPTION OF DRAWINGS

[0032] Further advantages and advantageous configurations of the subject matter of the invention may be found in the description, the claims, and the drawing. Likewise, the features referred to above and those yet to be mentioned below may respectively be used independently or jointly in any desired combinations. The embodiments shown and described are not to be understood as an exhaustive list, but rather have an exemplary nature for the presentation of the invention. In the drawings:

[0033] FIG. 1 is a schematic that shows a laser processing machine suitable for carrying out the methods disclosed herein.

[0034] FIG. 2 is a schematic illustration of a workpiece showing the cutting lengths of laser cuts, respectively, carried out up to the cutting interruption speed for different values of a cutting parameter.

[0035] FIG. 3 is a graph that shows the relationship between the cutting lengths/cutting times/cutting interruption speeds of laser cuts, respectively, carried out up to the cutting interruption speed and the cutting parameter “z focal position of the laser beam.”

[0036] FIG. 4 is a graph that shows the relationship between the cutting lengths/cutting times/cutting interruption speeds of laser cuts respectively carried out up to the cutting interruption speed and the cutting parameter “z focal position of the laser beam”, respectively for two different laser powers for the case of a focal shift.

[0037] FIG. 5 is a graph that shows the relationship between the cutting lengths/cutting times/cutting interruption speeds of laser cuts respectively carried out up to the cutting interruption speed and the cutting parameter “z focal position of the laser beam”, respectively for different laser powers.

[0038] FIG. 6 is a graph that shows the relationship between the cutting lengths/cutting times/cutting interruption speeds of laser cuts respectively carried out up to the cutting interruption speed and the cutting parameter “z focal position of the laser beam”, respectively for different focal diameters.

[0039] FIG. 7 is a schematic illustration of a workpiece that shows the penetration welding lengths of laser penetration welds respectively carried out up to the interruption speed for different values of a welding parameter.

[0040] FIG. 8 is a graph that shows the relationship between the penetration welding lengths/welding times/interruption speeds of laser penetration welds respectively carried out up to the interruption speed and the welding parameter “z focal position of the laser beam.”

[0041] FIG. 9 is a schematic illustration of a workpiece that shows the melting track lengths of melting tracks respectively produced up to the interruption speed for different values of a fusion parameter.

[0042] FIG. 10 is a graph that shows the relationship between the melting track lengths/fusion times/interruption speeds of melting tracks respectively produced up to the interruption speed and the fusion parameter “z focal position of the laser beam.”

DETAILED DESCRIPTION

[0043] The laser processing machine 1 represented in perspective in FIG. 1 comprises for example a CO.sub.2 laser, diode laser or solid-state laser as a laser beam generator 2, a (laser) processing head 3 displaceable in the X and Y directions, and a workpiece base or powder base 4 configured in this case as a workpiece base. A laser beam 5 (CW or pulsed operation) is generated in the laser beam generator 2 and is guided by a light-guide cable (not shown) or deflecting mirrors (not shown) from the laser beam generator 2 to the processing head 3. A plate-shaped workpiece 6 is arranged on the workpiece base 4. The laser beam 5 is directed onto the workpiece 6 by means of focusing optics arranged in the processing head 3. The laser cutting machine 1 is furthermore supplied with cutting gases 7, for example oxygen and nitrogen, and for an LMD process with helium or argon. The use of the respective cutting gas 7 is dependent on the workpiece material and on quality requirements for the cutting edges. Furthermore provided is a suction device 8, which is connected to a suction channel 9 that is located below the workpiece base 4. The cutting gas 7 is delivered to a cutting gas nozzle 10 of the processing head 3, from which it emerges together with the laser beam 5. The laser processing machine 1 furthermore comprises a machine controller 11.

[0044] With the energy of the laser beam 5, a particular melt volume, or a particular melting rate, may be produced in the workpiece 6. If the energy of the laser beam 5 is increasingly deposited transversely with respect to the direction of advance of the laser beam 5 during the laser cutting, for example because of a larger focal diameter or beam diameter on the workpiece 6, the maximum possible cutting speed decreases. FIG. 1 also shows an interruption detector 14, e.g., a photodiode in the laser beam generator 2 arranged to detect a cutting interruption and switches off the laser beam 5, and data memory 15.

[0045] To determine the influence of a cutting parameter, for example, the cutting parameter “z focal position F of the laser beam 5,” during the laser cutting of the workpiece 6, the following procedure is adopted:

[0046] As shown in FIG. 2, a plurality of laser cuts 12 are carried out on the workpiece 6 in the direction of advance 13 at the start point x.sub.0—while being controlled in a fully automated fashion by the machine controller 11—specifically in this case for five different values W.sub.1 to W.sub.5 of the cutting parameter. In this case, during the laser cuts 12, the cutting speed v of the laser beam 5 is respectively increased at least to such an extent that a cutting interruption respectively occurs at the end points x.sub.1,max to x.sub.5,max. An interruption detector 14, for example, a photodiode in the laser beam generator 2, detects the cutting interruption and turns the laser beam 5 off.

[0047] Subsequently—while being controlled in a fully automated fashion by the machine controller 11—the relationship between the cutting lengths L of the laser cuts 12, the associated cutting times t or the associated cutting interruption speeds v.sub.A and the cutting parameter is determined with the aid of the measured cutting lengths L.sub.1 to L.sub.5, the associated cutting times t.sub.1 to t.sub.5 or the associated cutting interruption speeds v.sub.A,1 to v.sub.A,5 of the laser cuts 12.

[0048] By the variation of the z focal position, different amounts of energy are deposited transversely with respect to the direction of advance, which leads to different cutting interruption speeds, i.e., the laser cuts 12 or the cutting times t are of different length. The cutting times t between the start of cutting and the cutting interruption are detected with the aid of the interruption detector 14. As an alternative, the cutting speed existing at the instant of the cutting interruption may be established by the machine controller 11 as a cutting interruption speed v.sub.A and assigned to the respective value of the cutting parameter.

[0049] FIG. 3 represents the interpolated relationship between the cutting lengths L/cutting times t/cutting interruption speeds v.sub.A of laser cuts 12 respectively carried out up to the cutting interruption speed and the cutting parameter “z focal position F of the laser beam 5”. The manipulated variable is thus the z focal position F of the laser beam 5. This is varied and a laser cut 12 is carried out with a continuous acceleration up to the cutting interruption. The z focal position is then varied, the machine axis travels to the next position, and the laser cut 12 is repeated on the workpiece 6 with the same continuous acceleration up to the cutting interruption. That z focal position of the laser beam 5 for which the cutting length L, or the associated cutting time t, or the associated cutting interruption speed v.sub.A of the laser cuts 12 is maximal is determined by the machine controller 11 in an automated fashion as the optimal focal position F.sub.opt, and the machine controller 11 adjusts the focal position of the laser beam 5 automatically to this optimal focal position F.sub.opt.

[0050] If, as shown in FIG. 4, the relationship between the cutting lengths L/cutting times t/cutting interruption speeds v.sub.A of laser cuts 12 and the z focal position F is respectively recorded for two different laser powers L.sub.1 and L.sub.2 (L.sub.1>L.sub.2) and the respective optimal focal positions F.sub.opt,L1 and F.sub.opt,L2 are determined, a power-dependent focal shift ΔF=F.sub.opt,L1−F.sub.opt,L2 may be determined therefrom.

[0051] FIG. 5 shows the relationship between the cutting lengths L/cutting times t/cutting interruption speeds v.sub.A of laser cuts 12 as a function of the z focal position F of the laser beam 5, respectively for different laser powers L.sub.1, L.sub.2, L.sub.3 (L.sub.1>L.sub.2>L.sub.3). With a lower power, there is a decrease (negative offset) of the respective cutting lengths, cutting times or cutting interruption speeds over the entire value range of the z focal position F in relation to the cutting lengths, cutting times or cutting interruption speeds at a higher power.

[0052] FIG. 6 shows the relationship between the cutting lengths L/cutting times t/cutting interruption speeds v.sub.A of laser cuts 12 as a function of the z focal position F of the laser beam 5, respectively for different focal diameters d.sub.1, d.sub.2, d.sub.3, d.sub.4 (d.sub.1>d.sub.2>d.sub.3>d.sub.4) of the laser beam 5. The individual curves respectively intersect at a high focal position and a low focal position. In comparison with a larger focal diameter, the cutting lengths, cutting times, or cutting interruption speeds for a smaller focal diameter have a negative offset in the region between the two points of intersection and a positive offset outside this region.

[0053] To be able to establish a power loss occurring in the course of time or a beam expansion occurring in the course of time, with a nominally equal laser power and nominally equal focal diameter, the relationships between the cutting lengths L/cutting times t/cutting interruption speeds v.sub.A and the z focal position F of the laser beam 5 are determined at two different instants. The curves determined are compared with one another to establish either a power loss or a beam expansion with the aid of the different curve profiles of FIGS. 5 and 6.

[0054] The machine implementation may, for example, be carried out as follows: [0055] 1. The actual status of the respective laser processing machine 1 is determined by detecting the cutting length L/cutting time Δt/cutting interruption speed v.sub.A as a function of the z focal position F. [0056] 2. The values determined are stored as a reference in a data memory 15 of the machine controller 11. [0057] 3. The machine controller 11 checks the current values with the stored values independently, unmanned, and fully automatically at the arbitrary instant freely defined by the customer. [0058] 4. The machine controller 11 evaluates the results based on the interpolated relationship between the cutting lengths L/cutting times Δt/cutting interruption speeds v.sub.A of laser cuts, respectively, carried out up to the cutting interruption speed and the cutting parameter z focal position F of the laser beam, e.g., as shown in FIG. 3. [0059] 5. Depending on the requirement and possibility, a restricted readjustment (laser power, focal position, etc.) is carried out with advice or a handling recommendation. [0060] 6. After the defined limits are exceeded, warning advice is overlaid or servicing intervention is recommended. [0061] 7. The machine status is displayed in a traffic light function.

[0062] As a result, the described method makes it possible to collect digitized data by means of a cutting pattern, whereupon the laser processing machine 1 adjusts itself independently where possible.

[0063] In order to determine the influence of a welding parameter, for example the welding parameter “z focal position F of the laser beam 5”, during the laser welding of the workpiece 6, the following procedure is adopted:

[0064] As shown in FIG. 7, a plurality of laser penetration welds 22 are carried out on the workpiece 6 in the direction of advance 23 at the start point x.sub.0—while being controlled in a fully automated fashion by the machine controller 11—specifically in this case for five different values W.sub.1 to W.sub.5 of the welding parameter. In this case, during the laser penetration welds 22, the welding speed v of the laser beam 5 is respectively increased at least to such an extent that a penetration welding interruption respectively occurs at the end points x.sub.1,max to x.sub.5,max. The interruption detector 14 detects the penetration welding interruption and turns the laser beam 5 off.

[0065] Subsequently—while being controlled in a fully automated fashion by the machine controller 11—the relationship between the penetration welding lengths L of the laser penetration welds 22, the associated welding times t or the associated penetration welding interruption speeds v.sub.A and the welding parameter is determined with the aid of the measured penetration welding lengths L.sub.1 to L.sub.5, the associated welding times t.sub.1 to t.sub.5 or the associated penetration welding interruption speeds v.sub.A,1 to v.sub.A,5 of the laser penetration welds 22.

[0066] FIG. 8 represents the interpolated relationship between the penetration welding lengths L/welding times t/penetration welding interruption speeds v.sub.A of laser penetration welds 22 respectively carried out up to the penetration welding interruption speed and the welding parameter “z focal position F of the laser beam 5”. That z focal position of the laser beam 5 for which the penetration welding length L, or the associated welding time t, or the associated penetration welding interruption speed v.sub.A of the laser penetration welds 22 is maximal is determined by the machine controller 11 in an automated fashion as the optimal focal position F.sub.opt, and the machine controller 11 adjusts the focal position of the laser beam 5 automatically to this optimal focal position F.sub.opt. The determination of the focal position may be carried out once with a low laser power and once with a high laser power. The difference of the two focal positions corresponds to the power-dependent focal shift.

[0067] To determine the influence of a fusion parameter in the LMD process, for example the fusion parameter “z focal position F of the laser beam 5,” during the fusion of metal powder by the laser beam 5, the following procedure is adopted:

[0068] As shown in FIG. 9, a plurality of melting tracks 32 are carried out in a powder bed 36 of the powder base 4 (as an alternative, a powder jet is also possible) in the direction of advance 33 at the start point x.sub.0—while being controlled in a fully automated fashion by the machine controller 11—specifically in this case for five different values W.sub.1 to W.sub.5 of the fusion parameter. In this case, during the melting tracks 32, the cutting speed v of the laser beam 5 is respectively increased at least to such an extent that a melting track interruption respectively occurs at the end points x.sub.1,max to x.sub.5,max. The interruption detector 14 detects the melting track interruption and turns the laser beam 5 off.

[0069] Subsequently—while being controlled in a fully automated fashion by the machine controller 11—the relationship between the melting track lengths L of the melting tracks 32, the associated fusion times t or the associated melting track interruption speeds v.sub.A and the fusion parameter is determined with the aid of the measured melting track lengths L.sub.1 to L.sub.5, the associated fusion times t.sub.1 to t.sub.5 or the associated melting track interruption speeds v.sub.A,1 to v.sub.A,5 of the melting tracks 32.

[0070] FIG. 10 represents the interpolated relationship between the melting track lengths L/fusion times t/melting track interruption speeds v.sub.A of melting tracks 32 respectively carried out up to the melting track interruption speed and the fusion parameter “z focal position F of the laser beam 5”. That z focal position of the laser beam 5 for which the melting track length L, or the associated fusion time t, or the associated melting track interruption speed v.sub.A of the melting tracks 32 is maximal is determined by the machine controller 11 in an automated fashion as the optimal focal position F.sub.opt, and the machine controller 11 adjusts the focal position of the laser beam 5 automatically to this optimal focal position F.sub.opt. The determination of the focal position may be carried out once with a low laser power and once with a high laser power. The difference of the two focal positions corresponds to the power-dependent focal shift.

OTHER EMBODIMENTS

[0071] It is to be understood that while the invention has been described in conjunction with the detailed description thereof, the foregoing description is intended to illustrate and not limit the scope of the invention, which is defined by the scope of the appended claims. Other aspects, advantages, and modifications are within the scope of the following claims.