JP5308798B2 - Laser processing equipment - Google Patents

Description

  The present invention relates to a laser processing apparatus, for example, a laser processing apparatus that cuts or welds a workpiece along a desired contour line.

  In a laser processing apparatus, a condensing lens condenses laser light to form a spot at one point of a work, and a part of the work on which the spot is formed is melted or evaporated by heating. When the workpiece is moved in such a state, piercing or cutting is performed. Therefore, in actual machining, it is required that the spot diameter on the workpiece does not change due to unevenness, waviness and / or warpage (hereinafter referred to as “warpage or the like”) on the workpiece. Therefore, as disclosed in Patent Document 1, gap control is performed to keep the distance between the nozzle and the workpiece constant at the same time while executing the machining program.

  FIG. 4 is a schematic diagram of a laser processing apparatus in the prior art. As shown in FIG. 4, the numerical control device 100 (CNC) included in the laser processing apparatus includes a movement amount calculation unit 110 and a servo control unit 120. The movement amount calculation unit 110 is operated by the main CPU, and the servo control unit 120 is operated by a servo control dedicated CPU.

  The movement amount calculation unit 110 includes a machining program reading unit 310, a machining path command analysis unit 320, an interpolation processing unit 330, a movement command output unit 340, an A / D conversion processing unit 400, a gap control processing unit 410, and a switching unit. 300. The servo control unit 120 includes a position control processing unit 130, a speed control processing unit 140, and a current control processing unit 150.

  Further, the machining nozzle 24 that outputs laser light to the workpiece W is moved up and down by the Z-axis motor 22. As shown in the figure, a Z-axis motor position detector 23 that detects the position of the Z-axis motor 22 is attached to the Z-axis motor 22. A gap sensor 25 that detects a gap distance between the workpiece W and the machining nozzle 24 using the contact 26 is attached to the machining nozzle 24.

  The reading unit 310 and the analysis unit 320 of the movement amount calculation unit 110 read and analyze the machining program, respectively. Then, based on the command of the gap control operation mode described in the machining program, the switching unit 300 is driven, and the machining nozzle created by the gap control processing unit 410 from the movement command of the machining nozzle 24 created by the output unit 340 The movement command is switched to 24 so that the gap control is performed.

In the gap control operation, the gap sensor 25 detects the gap distance between the workpiece W and the machining nozzle 24 as a gap detection value. The gap detection value changes according to the warp on the workpiece W or the like. Then, the gap detection value is A / D converted in the A / D conversion processing unit 400 (external input interface device), and then taken into the movement amount calculation unit 110. Then, in the gap control processing unit 410, a movement command for the machining nozzle 24 corresponding to the gap detection value is created.
Japanese Patent No. 2528509

  In the prior art shown in FIG. 4, the gap detection value is A / D converted through an external input interface device and then input to the movement amount calculation unit 110. Although the time required for A / D conversion is short, the time until the gap detection value is taken into the movement amount calculation unit 110 is due to the communication cycle between the external input interface device and the numerical controller 100. It will be late.

  In the gap control processing unit 410, the calculation processing for creating a movement command for gap control from the gap detection value is performed at an interpolation cycle or a control cycle faster than the interpolation cycle. However, since this calculation process is considerably slow compared to the control cycle for servo control, the gap control processing unit 410 also has a delay.

  Further, in FIG. 4, a movement command for the gap control operation is commanded to the servo control unit 120 and is output to the servo amplifier 21 through the position control processing unit 130, the speed control processing unit 140 and the current control processing unit 150. Until then, there will be a delay.

  For these reasons, a considerable time is required from when the gap sensor 25 detects the gap distance until the shaft of the machining nozzle operates. When the feed speed for moving the workpiece W in the X-axis and Y-axis directions is large, the raising / lowering operation of the machining nozzle 24 cannot follow the warp of the workpiece W, and as a result, machining accuracy is lowered.

  In general, in laser machining, the switching unit 300 may be frequently activated depending on the part or shape of the workpiece W and the command method of the machining program. For example, in the case of performing piercing, since the gap sensor 25 malfunctions due to the influence of plasma generated during laser beam irradiation, a command not to perform gap control during piercing may be included in the machining program. In the conventional gap control method, it is necessary to switch between the movement command output from the output unit 340 of the movement amount calculation unit 110 and the movement command output from the gap control processing unit 410 to operate. If such a switching operation is frequently performed, a waiting time associated with the switching operation occurs. This is also one of the factors that increase the tact time.

  The present invention has been made in view of such circumstances, and a laser processing apparatus that shortens the time required to start and end the gap control operation, and enables higher accuracy and improved responsiveness of the gap control operation. The purpose is to provide.

In order to achieve the above-mentioned object, according to the first invention, the machining nozzle and the workpiece are processed based on a machining program while condensing the laser beam emitted from the machining nozzle and irradiating the workpiece. In a laser processing apparatus that processes the workpiece by moving the workpiece relative to each other, a control shaft to which the processing nozzle is attached, and the processing nozzle is moved forward and backward from the workpiece. A drive unit that drives the control shaft, a servo control unit that controls the drive unit, a position detection unit that detects the position of the drive unit, and a gap between the machining nozzle and the workpiece. A gap sensor that detects the gap detected by the gap sensor, the servo control unit detecting the position of the driving unit detected by the position detection unit. Change based on, whereby the processing nozzle and the have to perform the gap control for maintaining the gap constant between the workpiece, in the servo control unit, detected by the position detection unit A position control loop is formed by the position of the drive unit and the gap detection value detected by the gap sensor, and the gap detection value is added to the position of the drive unit to A laser processing apparatus is provided in which position control is performed, and speed control and current control are performed on the drive unit by feedforward processing of the gap detection value .

That is, in the first invention, it is not necessary to perform a calculation related to the control axis in the movement amount calculation unit at the time of gap control as in the prior art. Further, it is not necessary to input the gap detection value to the movement amount calculation unit through the external input interface device. For this reason, the responsiveness with respect to a control axis is improved at the time of gap control, and gap control can be performed with high precision. Furthermore, it is not necessary to perform a switching process by the switching unit during gap control, and therefore the time required for starting and ending the gap control operation can be shortened. Furthermore, since the feedforward process is performed, there is no need to wait for the position control process to end. Therefore, the delay in control can be eliminated and higher responsiveness can be ensured.

According to a second aspect, in the first aspect, further comprising a moving amount calculation unit for calculating a movement amount of the processing nozzle on the basis of the machining program, the movement amount calculated by the movement amount calculating section When the movement command of the machining nozzle is output based on the above, the servo control unit interrupts the gap control.
That is, in the second invention, the movement command from the machining program can be output to the control axis without completely ending the gap control operation. Therefore, it is possible to easily avoid the processing nozzle from colliding with foreign matter accumulated on the workpiece or the workpiece itself.

According to a third aspect , in the second aspect , when the movement command of the machining nozzle is output based on the movement amount calculated by the movement amount calculation unit when performing the gap control, The position of the drive unit detected by the position detection unit is notified to the servo control unit without adding the gap detection value.
That is, in the third aspect of the invention, the movement amount that the control axis has moved by gap control is notified to the movement amount calculation unit, and coordinate update processing is performed there. Therefore, the coordinate value in the movement amount calculation unit and the actual position of the machine can be matched.

Embodiments of the present invention will be described below with reference to the accompanying drawings. In the following drawings, the same members are denoted by the same reference numerals. In order to facilitate understanding, the scales of these drawings are appropriately changed.
FIG. 1 is a schematic diagram of a laser processing apparatus according to the present invention. As shown in FIG. 1, a numerical controller 10 (CNC) included in the laser processing apparatus 1 includes a movement amount calculation unit 11 that generates a movement command for the processing nozzle 24 and a servo control unit that controls the Z-axis motor 22. 12 and so on.

  The movement amount calculation unit 11 is operated by a main CPU, and the servo control unit 12 is operated by a servo control dedicated CPU. The numerical control device 10 includes a display unit that displays the position, speed, laser state, processing conditions, and the like of a machine such as a processing nozzle, such as a CRT or a liquid crystal display. Further, the numerical control device 10 includes a laser output condition and an input unit for inputting various data, such as a keyboard and a mouse.

  As shown in the figure, the movement amount calculation unit 11 includes a machining program reading unit 31, a machining path command analysis unit 32, an interpolation processing unit 33, a movement command output unit 34, and a coordinate value update processing unit 35. . The servo control unit 12 includes a position control processing unit 13, a speed control processing unit 14, and a current control processing unit 15. As can be seen from FIG. 1, the servo control unit 12 inputs a movement command to the servo amplifier 21.

  Further, the machining nozzle 24 that outputs laser light to the workpiece W is moved up and down along the control axis 29 by the Z-axis motor 22. As illustrated, the control shaft 29 extends substantially perpendicularly to the upper surface of the workpiece W. A Z-axis motor position detector 23 that measures the rotation amount of the Z-axis motor 22 and outputs a pulse corresponding to the rotation amount is attached to the Z-axis motor 22.

  Further, a gap sensor 25 that detects a gap G between the workpiece W held on the movable table 40 and the machining nozzle 24 by a contact 26 is attached to the machining nozzle 24. The contact 26 moves up and down according to warpage on the workpiece W, and the lifting operation is converted into a rotational motion by the conversion mechanism 28. Then, the position detector 27 outputs a number of pulses corresponding to the converted rotational motion. The position detector 27 is assumed to have the same configuration as the Z-axis motor position detector 23. As shown in FIG. 1, the pulse output from the position detector 27 is output to the position control processing unit 13.

  Instead of using the contact 26, a conversion circuit for converting the output into the same type as the output of the Z-axis motor position detector 23 using a capacitance type gap sensor (not shown) may be provided. .

  When the workpiece W is laser processed by the laser processing apparatus, laser light is emitted from the processing nozzle 24 through a laser oscillator (not shown). The laser beam irradiates the workpiece W while being condensed by a condenser lens (not shown).

  Then, the machining program for the workpiece W stored in the storage device of the numerical controller 10 or an external storage device (both not shown) is read by the reading unit 31. Next, the contents of the machining program are analyzed by the analysis unit 32, and movement commands in the X-axis and Y-axis directions are output from the output unit 34 through the interpolation processing unit 33. The movable table 40 that holds the workpiece W is moved in the X-axis and Y-axis directions by a movement command in the X-axis and Y-axis directions. Thereby, the workpiece W is processed along a desired contour line.

  FIG. 2 is a flowchart showing the gap control operation of the laser processing apparatus according to the present invention. FIG. 2 shows a case where the laser processing apparatus 1 cuts the workpiece W as one embodiment. However, even when the laser processing apparatus 1 welds the workpiece W, the same is assumed.

  As shown in FIG. 2, first, in step S <b> 1, the output of the Z-axis motor position detector 23 every predetermined cycle is once taken into the servo control unit 12 at the time of laser cutting. Assume that the output value M of the Z-axis motor position detector 23 is a number of pulses corresponding to the amount of rotation of the Z-axis motor 22.

  Next, in step S2, it is determined whether or not a gap control operation is commanded in the machining program being executed. If it is not determined that the gap control operation is being performed, the process proceeds to step S4. On the other hand, if it is determined that the gap control operation is being executed, the process proceeds to step S3.

  By the way, normally, the cutting process program includes movement information regarding the X-axis and Y-axis directions in order to cut the workpiece W along a desired contour line. Based on such movement information, a movement command for the X-axis and Y-axis directions is created. However, in order to keep the focal position of the machining nozzle 24 constant, the machining program does not include movement information regarding the Z-axis direction. For this reason, during gap control, the movement command in the Z-axis direction calculated by the movement amount calculation unit 11 is zero, and the control shaft 29 does not normally move up and down. That is, at the time of laser processing, the processing nozzle 24 remains at a predetermined height.

  However, when warpage or the like exists on the surface to be processed of the workpiece W, the distance between the processing nozzle 24 and the surface to be processed of the workpiece W changes along the contour line during laser processing. In such a case, the machining nozzle 24 collides with the workpiece W, and these are damaged. Alternatively, there is a possibility that the focal position of the laser beam deviates from the work surface of the workpiece W, so that the workpiece W cannot be processed satisfactorily.

  For this reason, in the present invention, the contact 26 of the gap sensor 25 is placed on the processing surface of the workpiece W. When the movable table 40 moves, the contact 26 moves up and down according to the warp of the workpiece W or the like. The ascending / descending operation of the contactor 26 is converted into a rotational motion by a conversion mechanism unit 28, for example, a rack and pinion. Then, the position detector 27 outputs a number of pulses corresponding to the rotational motion transmitted from the conversion mechanism unit 28 every predetermined period. This number of pulses is called an output value M ′ of the gap sensor 25.

  In step S3, the output value M ′ of the gap sensor 25 is added to the output value M of the Z-axis motor position detector 23 and updated as a new output value M (M ← M + M ′). Thereby, the change of the gap G based on the curvature etc. on the workpiece | work W is correctable. The new output value M is input to the position control processing unit 13 of the servo control unit 12. Then, based on the output value M, the servo control unit 12 controls the Z-axis motor 22 so as to maintain the gap G between the machining nozzle 24 and the workpiece W constant.

  As described above, in the present invention, it is not necessary to perform calculation related to the control axis 29 in the movement amount calculation unit 11 during gap control as in the prior art. Further, it is not necessary to input the gap G to the movement amount calculation unit 11 through the external input interface device. For this reason, the responsiveness with respect to the control axis | shaft 29 can be improved and gap control can be performed with high precision. Further, since it is not necessary to perform the switching process by the switching unit as in the prior art, the time required for starting and ending the gap control operation can be shortened in the present invention.

  Normally, an error occurs because the Z-axis motor position detector 23 follows the output command for the Z-axis motor 22 with a delay. The servo control unit 12 performs processing at a faster cycle than the movement amount calculation unit 11, thereby suppressing errors. However, in the present invention, the gap G detected by the gap sensor 25 is converted into the same unit as the output value M of the Z-axis motor position detector 23 and added to it. For this reason, in the present invention, it is possible to calculate the drive amount of the Z-axis motor 22 that maintains the gap G constant without performing processing at a faster cycle than the movement amount calculation unit 11.

  Next, in step S4, position control is performed based on the output value M input to the position control processing unit 13. In step S5, the speed control processing unit 14 determines whether to apply the feedforward process to the gap control speed.

  If it is determined that the feedforward process is to be enabled, the first FF processing unit 16 performs the speed feedforward process on the gap G in step S6, and the speed control processing unit 14 performs the speed control process in step S7. To implement.

  Further, in step S8, the current control processing unit 15 determines whether or not to apply the feedforward process to the gap control current. If it is determined that the feedforward processing is to be enabled, the second FF processing unit 17 performs current feedforward processing on the gap G in step S9, and in step S10, the current control processing unit 15 Perform control processing.

  Thus, since the speed feedforward process and the current feedforward process are performed, there is no need to wait for the processes in the position control processing unit 13 and the speed control processing unit 14 to end. Therefore, it will be understood that in the present invention, delay in control can be eliminated and high responsiveness can be secured. Thereafter, the current command processed by the position control processing unit 13 is output to the Z-axis motor 22 through the servo amplifier 21 (step S11).

  By the way, as described above, the Z axis movement command for the control shaft 29 is normally not output during laser processing, and the control shaft 29 is raised and lowered according to the warp of the processing surface of the workpiece W by the gap control operation. Is processed along the desired contour line.

  However, when the machining nozzle 24 is moved to another position on the workpiece W after the laser machining is finished, the machining nozzle 24 is prevented from colliding with the foreign matter accumulated on the workpiece W or the workpiece W itself. Therefore, there is a case where a movement command for raising the machining nozzle 24 along the control axis 29 is included in the machining program.

  When the control shaft 29 is raised during the gap control operation based on such a movement command, the gap G is increased, so that a movement command for lowering the machining nozzle 24 is newly output. As described above, when the machining nozzle 24 repeats the lifting and lowering operation, a situation occurs in which the machining nozzle 24 cannot operate normally. For this reason, it is preferable to temporarily stop the gap control operation when a movement command for the control shaft 29 is output by the movement amount calculation unit 11 during the gap control operation.

  FIG. 3 is a flowchart showing stop processing during the gap control operation of the laser processing apparatus. In FIG. 3, when the gap control operation is being performed, it is determined whether or not to continue the operation.

  In step T1 in FIG. 3, the reading unit 31 reads the machining program, and then in step T2, the analysis unit 32 determines whether there is a gap control command in the machining program. If there is a gap control command, the process proceeds to step T3. In step T3, it is determined whether or not the movement amount calculation unit 11 has created a movement command for the control axis 29 in the Z-axis direction when the gap control operation is being performed.

  When it is determined that a movement command for the control shaft 29 in the Z-axis direction has been created during the gap control operation, the output value M ′ of the gap sensor 25 is added to the output value M of the Z-axis motor position detector 23. And only the output value M of the Z-axis motor position detector 23 is notified to the servo control unit 12. By such control, the gap control operation is temporarily interrupted (step T5).

  In such a case, the machining nozzle 24 temporarily rises based on a movement command in the Z-axis direction during the gap control operation. Accordingly, it is possible to avoid the machining nozzle 24 from colliding with foreign matter accumulated on the workpiece W or the workpiece W itself without completely ending the gap control operation.

  The output value M of the Z-axis motor position detector 23 is input to the coordinate value update processing unit 35 of the movement amount calculation unit 11 through the position control processing unit 13. In the coordinate value update processing unit 35, coordinate update processing is performed based on the output value M. Therefore, it is possible to match the coordinate value in the movement amount calculation unit 11 with the actual position of the machine.

1 is a schematic view of a laser processing apparatus according to the present invention. It is a flowchart which shows the gap control operation | movement of the laser processing apparatus shown by FIG. It is a flowchart which shows the process at the time of the gap control operation | movement of a laser processing apparatus. 1 is a schematic diagram of a laser processing apparatus in the prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laser processing apparatus 10 Numerical control apparatus 11 Movement amount calculation part 12 Servo control part 13 Position control process part 14 Speed control process part 15 Current control process part 16 1st FF process part 17 2nd FF process part 21 Servo amplifier 22 Z axis Motor (drive unit)
23 Z-axis motor position detector (position detector)
DESCRIPTION OF SYMBOLS 24 Processing nozzle 25 Gap sensor 26 Contactor 27 Position detector 28 Conversion mechanism part 29 Control axis 31 Reading part 32 Analysis part 33 Interpolation processing part 34 Output part 40 Movable table W Workpiece (workpiece)

Claims (3)

A laser processing apparatus for processing the workpiece by moving the processing nozzle and the workpiece relative to each other based on a processing program while condensing and irradiating the workpiece with laser light emitted from the processing nozzle In
A control shaft to which the machining nozzle is attached;
A drive unit that drives the control shaft to move the processing nozzle forward and backward from the workpiece;
A servo control unit for controlling the drive unit;
A position detection unit for detecting the position of the drive unit;
A gap sensor for detecting a gap between the processing nozzle and the workpiece,
The servo control unit changes the position of the driving unit detected by the position detection unit based on a gap detection value detected by the gap sensor, and thereby, between the processing nozzle and the workpiece. Gap control is performed to maintain a constant gap.
In the servo control unit, a position control loop is formed by the position of the drive unit detected by the position detection unit and the gap detection value detected by the gap sensor, and the position of the drive unit is Position control for the drive unit is performed by adding the gap detection value,
A laser processing apparatus in which speed control and current control are performed on the drive unit by feedforward processing of the gap detection value. Furthermore, it comprises a movement amount calculation unit for calculating the movement amount of the processing nozzle based on the processing program,
2. The laser according to claim 1, wherein when the machining nozzle movement command is output based on the movement amount calculated by the movement amount calculation unit, the servo control unit interrupts the gap control. Processing equipment. When the movement control of the machining nozzle is output based on the movement amount calculated by the movement amount calculation unit when performing the gap control, the position detection is performed without adding the gap detection value. The laser processing apparatus according to claim 2 , wherein the position of the driving unit detected by the unit is notified to the servo control unit.

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