Control device and control method for non-contact processing machine

Abstract

The present invention suppresses excessive retraction operation and overshoot.　Provided is a control device for a non-contact processing machine that retracts a processing head from a processing position to a retraction position and returns the processing head from the retraction position to a processing start position at which non-contact processing is performed next when moving the processing head from a processing end position to the processing start position, the control device comprising a retraction height determination unit that determines a first retraction height at which retraction and return of the processing head can be completed within a movement time specified from a horizontal movement distance and movement speed of the processing head from the processing position to the processing start position, a second retraction height acquisition unit that acquires a preset second retraction height, and a retraction height selection unit that selects either the first retraction height or the second retraction height as the height of the retraction position.

Description

Control device and control method for a non-contact processing machine

[0001] This disclosure relates to a control device and control method for a non-contact machining machine, and more particularly to a control device and control method for a non-contact machining machine that controls the operation of a machining head based on a machining program command.

[0002] In laser processing, there is a technique in which, when moving from the end of processing to the start of the next non-contact processing, the processing head is moved horizontally to the next processing position while simultaneously retracting (raising) the processing head vertically, and then returning (lowering) the processing head as it approaches the next processing start position.

[0003] Patent Document 1 describes a laser processing apparatus that performs stable laser processing of a workpiece while avoiding collisions between the processing head and the workpiece. Specifically, Patent Document 1 describes a laser processing apparatus comprising an NC control unit that controls the relative position of the workpiece and the processing head, and a distance detection unit that detects the shortest distance between the processing surface of the workpiece and the processing head as distance information when the NC control unit moves the processing head from the retracted position to the next processing point. The NC control unit performs tracking control of the processing head based on the distance information detected by the distance detection unit when moving the processing head from the retracted position to the next processing point, and also describes using diagonal downward control to move the processing head diagonally downward from the retracted position to the next processing point during the approach.

[0004] Patent Document 2 describes a laser processing machine capable of preventing the processing head from colliding with a workpiece when the height direction of the workpiece being processed is different, or when processing a workpiece mounted on a rotating shaft. Specifically, Patent Document 2 describes a numerical control device for a laser processing machine in which the processing head position command calculation unit avoids collision with the workpiece by switching to gap control when the gap sensor detects the workpiece while the processing head is moving in the Z-axis direction to bring it closer to the workpiece. At this time, whether the movement of bringing the processing head closer to the workpiece is performed by gap control (detection value of the gap sensor) or to a position determined by parameters can be switched by adding a mode switching means to the processing head position command calculation unit.

[0005] Patent Document 3 describes a laser processing apparatus that can follow and move a laser processing head relative to a workpiece having an opening quickly and reliably. Specifically, Patent Document 3 describes that the apparatus includes a control unit that controls a head driving unit to move a laser processing head that irradiates a workpiece with laser light so as to follow and move relative to the workpiece. When the movement projection path, which is the projection of a predetermined movement path of the laser processing head onto the workpiece, crosses a plurality of openings, the control unit obtains the maximum hole-crossing distance from the hole-crossing distances at which the movement projection path crosses each opening, determines whether the laser processing head can pass through the opening that gives the maximum hole-crossing distance by following and moving, and controls the laser processing head to pass through all of the plurality of openings by following and moving when it is determined that the head can pass through by following and moving.

[0006] Japanese Patent Application Laid-Open No. 2008-110389, Japanese Patent Application Laid-Open No. 2016-47540, Japanese Patent Application Laid-Open No. 2017-131897

[0007] Generally, the retraction speed of the processing head in the vertical direction and the movement speed of the processing head in the horizontal direction are set as fast as possible according to the mechanical characteristics. The height during retraction in the vertical direction is generally set uniformly and so as not to collide with the workpiece that has bounced up, regardless of the horizontal movement distance to the processing start position. If the horizontal movement distance is short relative to the retraction height, an excessive retraction operation occurs in the operations of retracting and returning the processing head.

[0008] When it is determined that the horizontal movement distance is short relative to a preset retraction height and the retraction cannot be completed, the retraction operation can be interrupted. When the retraction operation is interrupted midway, an overshoot occurs between the interruption of retraction (ascending) and the start of the return (descending) operation. When an excessive retraction operation or an overshoot occurs, energy consumption increases.

[0009] Therefore, a control device and a control method for a non-contact processing machine that can suppress excessive retraction operations and overshoots and reduce energy consumption are desired.

[0010] A typical first aspect of this disclosure is a control device for a non-contact machining machine that controls the movement of a machining head based on a machining program command to perform non-contact machining on a workpiece, and when moving the machining head from the machining end position to the machining start position for the next non-contact machining, moves the machining head from the machining end position to a retracted position and returns the machining head from the retracted position to the machining start position, the control device comprising: a retracted height determination unit that determines a first retracted height that allows the retraction and return of the machining head to be completed within a movement time determined from the horizontal movement distance and movement speed of the machining head from the machining end position to the machining start position; a second retracted height acquisition unit that acquires a preset second retracted height; and a retracted height selection unit that selects the higher of the first retracted height and the second retracted height and sets it as the height of the retracted position.

[0011] A typical second aspect of this disclosure is a control method in which a computer controls a non-contact machining machine to perform non-contact machining on a workpiece by controlling the movement of a machining head based on a machining program command, and when the machining head moves from the machining end position to the machining start position for the next non-contact machining, the computer controls the machining head to be retracted from the machining end position to a retracted position and to return the machining head from the retracted position to the machining start position, the control method comprising: determining a first retracted height that allows the retraction and return of the machining head to be completed within a travel time determined from the horizontal travel distance and travel speed of the machining head from the machining end position to the machining start position; acquiring a preset second retracted height; and selecting the higher of the first retracted height and the second retracted height to be the height of the retracted position.

[0012] This is a block diagram showing an example configuration of a control device for a non-contact machining machine according to the first embodiment of this disclosure. This is a diagram illustrating the method of moving the machining head of a non-contact machining machine. This is a diagram illustrating the retraction and return operation when the first retraction height H1 is higher than the second retraction height H2. This is a diagram illustrating the retraction and return operation when the second retraction height H2 is higher than the first retraction height H1. This is a flowchart showing an example of a control method for a non-contact machining machine. This is a diagram showing the case where the horizontal movement distance is sufficiently long relative to the retraction height, and no excessive retraction operation occurs in the retraction and return operation. This is a diagram showing the case where the horizontal movement distance is short relative to the retraction height, and an excessive retraction operation occurs in the retraction and return operation. This is a diagram showing the case where the retraction operation is interrupted and an overshoot occurs. This is a diagram showing the case where the workpiece is supported by a pincushion on the machining table. This is a diagram showing how a part of the cut workpiece bounces up depending on the position of the pin tips of the pincushion when the workpiece is cut with a laser machining machine. This is a diagram showing the relationship between the horizontal movement distance and the retraction height when an upper limit value for the retraction height is set.

[0013] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. (First Embodiment) Figure 1 is a block diagram showing an example configuration of a control device for a non-contact processing machine according to the first embodiment of the present disclosure.

[0014] As shown in Figure 1, the control device 10 includes a program storage unit 101, a program analysis unit 102, a retraction height determination unit 103, a second retraction height acquisition unit 104, a retraction height selection unit 105, and an axis drive control unit 106. At least one of the program storage unit 101, the program analysis unit 102, and the axis drive control unit 106 may be provided outside the control device 10.

[0015] The non-contact machining center 20, in which the axis drive control unit 106 controls the axis drive for the movement of the machining head 200, is not particularly limited, but may include, for example, a laser machining center, a plasma electrical discharge machining center, or a water jet machining center. The configuration and operation of laser machining centers, plasma electrical discharge machining centers, and water jet machining centers are already known, so a description will be omitted.

[0016] As shown in Figure 2, the control device 10 controls the movement of the processing head 200 of the non-contact processing machine 20 from the processing end position of the workpiece 30 (which is not to be processed) to the processing start position (hereinafter referred to as the processing start position) where the next non-contact processing will be performed. Specifically, in Figure 2, the control device 10 first retracts (raises) the processing head 200 vertically from the processing end position, and then moves the processing head 200 horizontally while retracting (raising) it vertically to the retraction height. After that, the control device 10 moves the processing head 200 horizontally toward the processing start position at the retraction height. Furthermore, the control device 10 moves the processing head 200 horizontally while lowering it vertically toward the processing start position, and then stops the horizontal movement at the processing start position and returns (lowers) the processing head 200. In Figure 2, the movement path of the processing head 200 is shown by a dashed line. The movement path of the machining head 200 may be a triangular mountain shape as shown in Figure 3, or a rectangular mountain shape as shown in Figure 4, as will be described later. By retracting the machining head 200 vertically, collisions between the machining head 200 and obstacles can be avoided even if there are obstacles on the machining table surface.

[0017] The following describes each part of the control device 10 with reference to Figure 1. The program storage unit 101 stores a machining program for controlling the non-contact machining machine 20. The program analysis unit 102 reads and analyzes the machining program stored in the program storage unit 101, generates movement command blocks for the motors that drive each axis of the non-contact machining machine 20, and outputs them to the retraction height determination unit 103. The movement command block includes the horizontal movement distance L of the machining head 200 and the horizontal movement speed F. The movement speed F is the average speed because the horizontal speed of the machining head 200 is accelerated and decelerated.

[0018] The retraction height determination unit 103 calculates the travel time T based on the horizontal travel distance L and travel speed F commanded by the movement command block, and determines the first retraction height H1 within the travel time T that allows the machining head 200 to be retracted and returned, based on the retraction speed Fz of the machining head. The retraction speed Fz is also the average speed because the vertical speed of the machining head 200 is accelerated and decelerated. For example, the retraction height H1 can be calculated as H1 = Fz × T / 2, that is, H1 = Fz × (L / F) / 2.

[0019] The second retraction height acquisition unit 104 acquires a preset second retraction height H2. The second retraction height H2 is, for example, a height corresponding to the workpiece thickness. The second retraction height H2 may be set based on the workpiece thickness and the processing program. For example, when cutting a workpiece 30 that will not be processed with a non-contact processing machine 20, depending on the cutting shape and thickness of the workpiece 30, a part of the cut workpiece 30 may bounce up. For example, in the case of a laser processing machine, a part of the cut workpiece 30 may be pushed up and bounced up by an assist gas sprayed coaxially with the laser beam, and in the case of a water jet processing machine, by a water jet. The bounce height can be automatically estimated based on the workpiece thickness and the processing program, and the second retraction height H2 can be set based on the estimated value.

[0020] The second retraction height H2 may be set based on the shape and height of the pin cushion when the workpiece is supported by the pin cushion on the processing table. As shown in Figure 9, when the workpiece 30 is placed on the pin cushion, the second retraction height H2 depends on the height of the pin cushion. Also, when cutting the workpiece 30 with a non-contact processing machine, depending on the shape of the pin cushion, a part of the cut workpiece 30 may bounce up. Figure 10 shows how a part of the cut workpiece 30 bounces up when cutting the workpiece 30 with a laser processing machine, depending on the position of the pin tips of the pin cushion. Therefore, the second retraction height H2 is set based on the shape and height of the pin cushion.

[0021] The retraction height selection unit 105 compares the first retraction height H1 and the second retraction height H2 and selects the higher retraction height. The retraction height selection unit 105 then drives the shaft drive control unit 106 to perform an operation that includes retraction to the selected height and return from the retracted position to the machining start position.

[0022] The axis drive control unit 106 controls the motors that drive each axis of the non-contact machining center so that the operation includes retracting to a selected height and returning from the retracted position to the machining start position.

[0023] Figure 3 illustrates the retraction and return operations when the first retraction height H1 is higher than the second retraction height H2. The thick arrows in Figure 3 indicate the movement path of the machining head 200. The retraction height selection unit 105 selects the first retraction height H1 if it is higher than the second retraction height H2. The retraction height selection unit 105 then drives and controls the axis drive control unit 106 to perform an operation that includes retraction to the selected first retraction height H1 and return from the retracted position to the machining start position. Figure 3 shows the case where the machining head 200 moves vertically and horizontally simultaneously.

[0024] Figure 4 illustrates the retraction and return operations when the second retraction height H2 is higher than the first retraction height H1. The thick arrows in Figure 4 indicate the movement path of the machining head 200. The retraction height selection unit 105 selects the second retraction height H2 if it is higher than the first retraction height H1. In this case, as shown in Figure 4, it is desirable for the retraction height selection unit 105 to drive the shaft drive control unit 106 to drive the axis of the machining head so that the machining head 200 is retracted directly upward to avoid collision with the workpiece 30 on the machining table, then moved horizontally, and then lowered after the horizontal movement is completed. The retraction height selection unit 105 drives the shaft drive control unit 106 so that the operation includes retraction to the selected second retraction height H2 and return from the retracted position to the machining start position. In Figure 4, the vertical and horizontal movements of the machining head 200 are performed independently. However, in order to suppress excessive retraction, the vertical retraction height is determined within the travel time specified by the horizontal travel distance and speed of the machining head.

[0025] Figure 5 is a flowchart showing an example of a control method for a non-contact machining center. In the following description, an example in which the control method of this disclosure is executed by a control device 10 will be described, but the control method for a non-contact machining center of this disclosure can also be executed by a configuration other than the control device 10.

[0026] In step S1, the retraction height determination unit 103 calculates the travel time T based on the horizontal travel distance L and travel speed F commanded by the travel command block output from the program analysis unit 102, and determines a first retraction height H1 within the travel time T that allows the machining head 200 to be retracted and returned, based on the retraction speed Fz of the machining head.

[0027] In step S2, the second evacuation height acquisition unit 104 acquires a preset second evacuation height H2.

[0028] In step S3, the retraction height selection unit 105 compares the first retraction height H1 and the second retraction height H2 and selects the higher retraction height. The retraction height selection unit 105 then drives the shaft drive control unit 106 to perform an operation that includes retraction to the selected height and return from the retracted position to the machining start position.

[0029] In step S4, the retraction height selection unit 105 controls the drive axis of the machining head 200 via the axis drive control unit 106 so that the operation includes retraction to the selected height and return from the retracted position to the machining start position.

[0030] In step S6, a decision is made as to whether or not to continue processing. If the decision is not to continue processing ("NO"), the process ends; if the decision is to continue processing ("YES"), the process returns to step S1.

[0031] As described above, the control device and control method for the non-contact processing machine of this embodiment suppress excessive retraction and overshoot, and allow the processing head to be retracted to the set position. Furthermore, by suppressing excessive retraction or overshoot, energy consumption can be reduced.

[0032] The following describes in detail the effects of suppressing excessive retraction and overshoot. As shown in Figure 6, if the horizontal movement distance is sufficiently long relative to the retraction height, excessive retraction does not occur during the retraction and return operation. However, as shown in Figure 7, if the horizontal movement distance is short relative to the retraction height, excessive retraction occurs during the retraction and return operation. The thick arrows in Figures 6 and 7 indicate the movement path of the machining head 200. The dashed arrows in Figure 7 indicate the movement path of the machining head 200 when there is no excessive retraction. In this embodiment, the movement time T is calculated based on the horizontal movement distance and the movement speed, and a first retraction height is determined within the movement time that allows the machining head to retract and return, based on the retraction speed of the machining head. Since the retraction height can be set considering the horizontal movement distance, excessive retraction can be suppressed.

[0033] As shown in Figure 8, if it is determined that the horizontal movement distance is shorter than the preset retraction height and retraction cannot be completed, the retraction operation may be interrupted. However, in this case, an overshoot occurs between the interruption of retraction (upward movement) and the start of the return (downward movement) operation. The thick arrows in Figure 8 indicate the movement path of the machining head 200. In this embodiment, the movement time T is calculated based on the horizontal movement distance and the movement speed, and a first retraction height is determined within the movement time that allows the machining head to be retracted and returned, based on the retraction speed of the machining head. Since the retraction height can be set considering the horizontal movement distance, the interruption of the retraction operation can be avoided and overshoot can be suppressed.

[0034] (Second Embodiment) In the first embodiment, the retraction height determination unit 103 determines the first retraction height H1 using the horizontal travel distance L, so that the retraction height is set higher when the travel distance L is longer. However, if the retraction height is too high, the travel time required for the machining head to retract to the retraction height and return from the retraction height position to the machining start position becomes longer. Therefore, in this embodiment, the retraction height determination unit 103 determines the first retraction height H1 so that the retraction operation and return operation can be completed within a specified travel time.

[0035] The configuration of the control device in this embodiment is the same as the configuration of the control device 10 in the first embodiment. The retraction height determination unit 103 sets the first retraction height H1 to be less than or equal to the upper limit of the avoidance height H1up so that the retraction operation and return operation can be completed within the specified travel time. The upper limit H1up is the upper limit threshold. Figure 11 is a diagram showing the relationship between the horizontal travel distance and the retraction height when the upper limit of the retraction height is set. If the horizontal travel distance is L1, the retraction height H11 is generated, and if the travel distance is L2, which is greater than the horizontal travel distance L1, a retraction height H12 higher than the retraction height H11 is generated. When the retraction height H12 exceeds the upper limit of the avoidance height H1up, the retraction height H12 is generated so that it is less than or equal to the upper limit of the avoidance height H1up.

[0036] According to the control device and control method for the non-contact processing machine of this embodiment described above, in addition to the effects of the first embodiment, an upper limit value for the retraction height is set, so that the retraction and return operations can be performed within a specified travel time.

[0037] In order to realize the functional blocks included in the control device in each embodiment described above, the control device can be implemented by hardware, software, or a combination thereof. Similarly, the access information output method can also be implemented by hardware, software, or a combination thereof. Here, implementation by software means that it is implemented by a computer reading and executing a program.

[0038] To implement the components included in the control device through software or a combination thereof, the control device is equipped with an arithmetic processing unit such as a CPU (Central Processing Unit). The arithmetic processing unit functions as the execution unit. The control device is also equipped with auxiliary storage devices such as an HDD (Hard Disk Drive) that store various control programs such as application software or an OS (Operating System), and main memory such as RAM (Random Access Memory) for storing data temporarily required for the arithmetic processing unit to execute programs.

[0039] The control unit then reads application software or an operating system from the auxiliary storage device, expands the read application software or OS into the main memory, and performs calculations based on this application software or OS. Furthermore, it controls various hardware components based on these calculation results. This realizes the functional blocks of this embodiment. The control method can also be implemented with a configuration similar to that of the control unit.

[0040] The components included in the control device can be realized by hardware, including electronic circuits. When the control device is configured as hardware, some or all of the functions of each component included in the control device can be implemented using integrated circuits (ICs) such as ASICs (Application Specific Integrated Circuits), gate arrays, FPGAs (Field Programmable Gate Arrays), and CPLDs (Complex Programmable Logic Devices).

[0041] Programs can be stored and supplied to a computer using various types of non-transitor computer-readable media. Non-transitor computer-readable media include various types of tangible storage media. Examples of non-transitor computer-readable media include magnetic recording media (e.g., hard disk drives), magneto-optical recording media (e.g., magneto-optical disks), CD-ROMs (Read Only Memory), CD-Rs, CD-R / Ws, and semiconductor memory (e.g., mask ROMs, PROMs (Programmable ROMs), EPROMs (Erasable PROMs), flash ROMs, and RAMs (random access memory)). Furthermore, the program may be supplied to the computer by various types of temporary computer-readable media.

[0042] According to the control device and control method of this disclosure, including the embodiments described above, the retraction height can be set according to the travel distance, thereby suppressing excessive retraction and allowing the machining head to be retracted to its maximum height. Furthermore, energy consumption can be reduced by suppressing excessive retraction or overshoot.

[0043] While the embodiments described above are preferred embodiments of the present invention, the scope of the present invention is not limited to these embodiments, and various modifications can be made to implement the invention without departing from the spirit of the invention.

[0044] Regarding the above embodiment, the following additional remarks are further disclosed. (Supplementary Note 1) When controlling the operation of a processing head based on a machining program command to perform non-contact machining on a workpiece (30), and moving the processing head from a machining end position to a machining start position where non-contact machining is to be performed next, the control device (10) of a non-contact machining machine (20) that retracts the processing head from the machining end position to a retracted position and returns the processing head from the retracted position to the machining start position, a retraction height determination unit (103) that determines a first retraction height at which the retraction and return of the processing head can be completed within a movement time specified by the horizontal movement distance and movement speed of the processing head from the machining end position to the machining start position; a second retraction height acquisition unit (104) that acquires a preset second retraction height; a retraction height selection unit (105) that selects the higher retraction height between the first retraction height and the second retraction height and sets it as the height of the retracted position. A control device comprising these components.

[0045] (Supplementary Note 2) It includes a shaft drive control unit (106) that controls the drive shaft of the processing head. The retraction height selection unit (105) controls the shaft drive control unit so that the operation includes the retraction of the processing head to the height of the retracted position and the return from the height of the retracted position to the machining start position. The control device according to Supplementary Note 1.

[0046] (Supplementary Note 3) The retraction height determination unit (103) determines the first retraction height within the range of an upper limit threshold. The control device according to Supplementary Note 1 or 2.

[0047] (Supplementary Note 4) The non-contact machining machine (20) is a laser machining machine, a plasma discharge machining machine, or a water jet machining machine. The control device according to Supplementary Note 1 or 2.

[0048] (Supplementary Note 5) When a computer controls the operation of a machining head based on a machining program command to perform non-contact machining on a workpiece (30) with respect to a non-contact machining machine (20), and moves the machining head from the machining end position to the machining start position where non-contact machining is to be performed next, the machining head is retracted from the machining end position to a retracted position, and is controlled to return from the retracted position to the machining start position. The control method is as follows: The computer determines a first retraction height at which the retraction and return of the machining head can be completed within the movement time specified by the horizontal movement distance and movement speed of the machining head from the machining end position to the machining start position; A step of acquiring a preset second retraction height; A step of selecting the higher of the first retraction height and the second retraction height and setting it as the height of the retracted position, and executing the control method.

[0049] 10 Control device 20 Non-contact machining machine 30 Workpiece 101 Program storage unit 102 Program analysis unit 103 Retraction height determination unit 104 Second retraction height acquisition unit 105 Retraction height selection unit 106 Axis drive control unit 200 Machining head

Claims

1. A control device for a non-contact machining machine that controls the movement of a machining head based on a machining program command to perform non-contact machining on a workpiece, and when moving the machining head from the machining end position to the machining start position for the next non-contact machining, moves the machining head from the machining end position to a retracted position and returns the machining head from the retracted position to the machining start position, comprising: a retracted height determination unit that determines a first retracted height that allows the retraction and return of the machining head to be completed within a movement time determined from the horizontal movement distance and movement speed of the machining head from the machining end position to the machining start position; a second retracted height acquisition unit that acquires a preset second retracted height; and a retracted height selection unit that selects the higher of the first retracted height and the second retracted height and sets it as the height of the retracted position.

2. The control device according to claim 1, comprising an axis drive control unit for controlling the drive axis of the machining head, wherein the retraction height selection unit controls the axis drive control unit so that the operation includes retracting the machining head to the height of the retraction position and returning it from the height of the retraction position to the machining start position.

3. The control device according to claim 1 or 2, wherein the retraction height determination unit determines the first retraction height within the range of an upper threshold.

4. The control device according to claim 1 or 2, wherein the non-contact processing machine is a laser processing machine, a plasma discharge machining machine, or a water jet processing machine.

5. A control method in which a computer controls a non-contact machining machine to perform non-contact machining on a workpiece by controlling the movement of a machining head based on a machining program command, and when the machining head moves from the machining end position to the machining start position for the next non-contact machining, the computer controls the machining head to be retracted from the machining end position to a retracted position and to return the machining head from the retracted position to the machining start position, the control method comprising: determining a first retracted height that allows the retraction and return of the machining head to be completed within a travel time determined from the horizontal travel distance and travel speed of the machining head from the machining end position to the machining start position; obtaining a preset second retracted height; and selecting the higher of the first retracted height and the second retracted height to be the height of the retracted position.

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