Machine tool control device and machine tool control method

Abstract

To shorten a cycle time by performing different operations in parallel even when a control object is controlled by using an M code.SOLUTION: A control device of a machine tool includes a first control unit including a CentralProcessingUnit (CPU) that controls the entire device, and a second control unit including a ProgrammableMachineController (PMC) that controls the machine tool in accordance with a control program including an M code. When the control program is started, the CPU sequentially reads M codes included in the control program and sends the M codes to the PMC. The PMC sequentially stores the M codes received from the CPU in the M code table 32. When the storage of the M code is completed, the PMC sequentially executes the command content of each M code according to the order of the M codes stored in the M code table 32. While the PMC executes the command content of each M code, the CPU executes another program.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a control device and a control method for controlling the operation of an NC (Numerical Control) machine tool in accordance with a predetermined program. [Background technology]

[0002] It is known that in NC machine tools, machining cycle time can be shortened by executing different operations, such as jig operation and spindle movement, in parallel. For example, Patent Document 1 discloses a control method for an NC machine tool that shortens cycle time by performing a jig unclamping operation and a spindle movement to a standby position in parallel, and performing a jig clamping operation and a spindle movement to a machining position in parallel. Furthermore, Patent Document 2 discloses a control device for an NC machine tool that shortens cycle time by switching control of axis control from the NC control unit to a PMC (Programmable Machine Controller), starting axis movement under the control of the PMC, performing tool change under the control of the NC control unit in parallel with the axis movement, and returning control to the NC control unit when the parallel operations are completed.

[0003] In NC machine tools, methods for controlling jig operations include a control method using a sequence program (hereinafter referred to as the "sequence program method") and a control method using an M-code (hereinafter referred to as the "M-code method"). In the sequence program method, a series of jig operations is pre-programmed, and predetermined jig operations are executed in accordance with the program. However, this method has the problem of increasing the amount of design and debugging work required, as complex jig operations are programmed as a ladder program. Furthermore, when it becomes necessary to change the jig operation or the order of operations due to a change in jig or machining accuracy, the task of modifying the complex program is difficult for the user, and the user is forced to rely on specialized engineers.

[0004] In contrast, the M-code method avoids the problems of the sequence program method. An M-code is an element of an NC program and is represented by an M, which represents an address, followed by a two- or three-digit number. M-codes primarily serve the auxiliary function of turning operations on and off. For example, "M10" commands the operation of clamping the spindle or workpiece with a jig, while "M11" commands the operation of unclamping the spindle or workpiece with a jig. Because of their simple format, M-codes are easily recognized by users on the machine tool's control panel. Users can also easily understand the contents of each M-code by referring to an M-code table. Therefore, even if a need arises to change the jig operation or the operation sequence, users can edit the M-codes themselves (add, change, rearrange, etc.) using the control panel, without relying on a technician.

[0005] However, with the M-code method, other operations cannot be performed in parallel while an M-code command is being executed, which creates a problem in terms of machining cycle time. For example, consider a jig control program that controls the operation of three jigs. First, the program reads the M-code commanding the operation of the first jig and executes the processing according to the content of that M-code. Once this is complete, the program reads the M-code commanding the operation of the second jig and executes the processing according to the content of that M-code. Finally, once this is complete, the program reads the M-code commanding the operation of the third jig and executes the processing according to the content of that M-code. Because the jig control program continues to operate while these three processes are being performed serially, other programs cannot be executed in parallel during this time. Instead, other programs must wait for the jig control program to finish before they can be executed. This inevitably results in a long cycle time. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 4666936 [Patent Document 2] Patent No. 4549051 Summary of the Invention [Problem to be solved by the invention]

[0007] In view of the above-mentioned problems, an object of the present invention is to shorten the cycle time by enabling different operations to be performed in parallel even when an object to be controlled is controlled using an M-code. [Means for solving the problem]

[0008] The machine tool control device according to the present invention includes a first control unit consisting of a CPU (Central Processing Unit) that controls the entire control device in accordance with a system program, a second control unit consisting of a PMC (Programmable Machine Controller) that controls the machine tool in accordance with a control program including M-codes that command predetermined operations, and a storage unit that stores the system program and the control program. The second control unit is provided with an M-code table in which M-codes in the control program are sequentially stored. When the control program is started, the first control unit sequentially reads the M-codes included in the control program and sends the M-codes to the second control unit. The second control unit sequentially stores the M-codes received from the first control unit in the M-code table, and after storing the M-codes, sequentially executes the commands of each M-code according to the order of the M-codes stored in the M-code table. While the second control unit is executing the commands of each M-code, the first control unit executes another program.

[0009] A method for controlling a machine tool according to the present invention is a control method for the above-mentioned control device, and includes the following steps. (1) When the control program is started, the second control unit sequentially reads the M codes included in the control program and sends the M codes to the second control unit. (2) The second control unit sequentially stores the M codes received from the first control unit in an M code table. (3) When the storage of the M codes is completed, the second control unit executes the command contents of each M code in sequence according to the order of the M codes stored in the M code table. (4) A step in which the first control unit executes another program while the second control unit executes the command contents of each M-code.

[0010] In the present invention, M codes read from the program are sequentially stored in an M code table, and the commands of each M code are executed using this M code table. Since the time required to read and store an M code is extremely short, the second control unit can immediately start an operation corresponding to each M code once the M code has been stored in the M code table. Furthermore, while the second control unit is executing the commands of an M code, the first control unit can execute another operation in parallel. [Effects of the Invention]

[0011] According to the present invention, even when an object to be controlled is controlled using an M-code, different operations can be performed in parallel, so that the cycle time can be significantly reduced compared to the conventional method. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a block diagram showing the overall configuration of a control system for an NC machine tool. [Figure 2] FIG. 2 is a front view showing an example of a control panel. [Figure 3] FIG. 2 is a schematic diagram illustrating an example of a jig. [Figure 4] FIG. 10 is a schematic diagram showing another example of the jig. [Figure 5] FIG. 10 is a schematic diagram showing another example of the jig. [Figure 6] FIG. 1 is a diagram showing the basic mechanism of the present invention. [Figure 7] 7 is an example of a program corresponding to T1 to T7 in FIG. [Figure 8] 1 is an example of an M-code table in which data is stored. [Figure 9] FIG. 10 is a diagram showing an example of changing a program on the control panel. [Figure 10] 4 is a flowchart showing the operation of the control device of the present invention. [Figure 11] 10 is a flowchart showing the operation of a conventional control device. [Figure 12] 10 is an example of a program according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0013] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings. The same reference numerals are used throughout the drawings to designate the same or corresponding parts.

[0014] 1 shows the overall configuration of an NC machine tool control system 100. Control system 100 is made up of a machine tool control device (hereinafter simply referred to as the "control device") 10 according to the present invention, an NC machine tool 50 controlled by this control device 10, an operation panel 60 attached to this NC machine tool 50, and a PC (Personal Computer) 70 connected to control device 10.

[0015] The control device 10 includes a CPU (Central Processing Unit) 1, a storage unit 2, a PMC (Programmable Machine Controller) 3, an axis control circuit 4, a servo amplifier 5, an I / O unit 6, an interface 7, and an interface 8.

[0016] The CPU 1 constitutes the first control unit of the present invention and includes a program processing unit 11, an auxiliary function command unit 12, and an axis control command unit 13. The storage unit 2 is made up of semiconductor memory and includes a ROM (Read Only Memory) 21 and a RAM (Random Access Memory) 22. The PMC 3 constitutes the second control unit of the present invention and includes an auxiliary function processing unit 31 and an M-code table 32.

[0017] The axis control circuit 4 is a circuit that outputs an axis control signal to the servo amplifier 5 based on a command from the axis control command unit 13 of the CPU 1. The servo amplifier 5 is a circuit that drives the servo motor 51 of the NC machine tool 50. The I / O unit 6 is a signal input / output device provided between the PMC 3 and the NC machine tool 50. The interface 7 is a circuit that connects the CPU 1 and the operation panel 60, and the interface 8 is a circuit that connects the CPU 1 and the PC 70.

[0018] The NC machine tool 50 includes a servo motor 51, a jig 52, and a tool changer 53. The servo motor 51 is driven by a servo amplifier 5 of the control device 10. The rotation of the servo motor 51 causes a spindle (not shown) that cuts the workpiece, a jig 52 that grips the workpiece, and the like to perform predetermined operations. The tool changer 53 is a device that automatically changes the tool attached to the spindle.

[0019] 1 shows only one axis control circuit 4, one servo amplifier 5, and one servo motor 51, but in reality, the same number of these are provided as the number of axes provided in NC machine tool 50. In addition to the above, NC machine tool 50 is also equipped with a hydraulic device, an actuator, various sensors, etc., although not shown.

[0020] Next, the control device 10 of the present invention will be described in more detail.

[0021] The program processing unit 11 of the CPU 1 (first control unit) reads out the system program stored in the ROM 21 of the storage unit 2 via the bus 40, and controls the overall operation of the control device 10 in accordance with this system program.

[0022] The auxiliary function command unit 12 of the CPU 1 generates commands to cause the NC machine tool 50 to perform operations in accordance with the contents of the M code (auxiliary functions) contained in the control program described below, and sends the commands to the PMC 3 via the bus 40.

[0023] The axis control command unit 13 of the CPU 1 generates commands for controlling the reference axes (X-axis, Y-axis, Z-axis) and rotation axes (A-axis, B-axis, C-axis) of the NC machine tool 50, and sends these commands to the axis control circuit 4 via the bus 40. The axis control circuit 4 receives these commands, generates an axis control signal, and outputs this signal to the servo amplifier 5. Based on this axis control signal, the servo amplifier 5 generates and outputs a drive voltage for rotating the servo motor 51.

[0024] In addition to the system program described above, the ROM 21 of the storage unit 2 stores a control program required for controlling the NC machine tool 50. The ROM 21 also stores parameters required for the control operation of the CPU 1.

[0025] Various data such as calculation data and display data are temporarily stored in the RAM 22 of the storage unit 2. Data input from an external operation panel 60 or PC 70 is also temporarily stored in the RAM 22 via interfaces 7 and 8, respectively.

[0026] An auxiliary function processing unit 31 of the PMC 3 (second control unit) executes the processing required for the NC machine tool 50 to operate in accordance with the contents of the M-code, based on commands from the auxiliary function command unit 12 of the CPU 1. This will be explained in detail later.

[0027] The M code table 32 of the PMC 3 is a storage area for storing M codes read from the control program. This M code table 32 will also be explained in detail later.

[0028] Next, the peripheral devices of the NC machine tool 50 will be described. An operation panel 60 is installed near the NC machine tool 50 and is connected to the CPU 1 via the interface 7 and the bus 40. The operation panel 60 is equipped with an operation unit 61 and a display unit 62. Figure 2 shows an example of the operation panel 60. The operation unit 61 is made up of a keyboard having many keys 61a. The display unit 62 is made up of, for example, a liquid crystal display. The operation panel 60 is a manual data input device, and commands and data input by operating the operation unit 61 are displayed on the display unit 62 and sent to the CPU 1 via the interface 7 and the bus 40.

[0029] The PC 70 is a general-purpose personal computer, and is connected to the CPU 1 via the interface 8 and the bus 40. The PC 70 stores programs and various parameters used to control the NC machine tool 50. These programs and parameters are loaded into the control device 10 by performing predetermined operations on the PC 70.

[0030] Next, the jig 52 of the NC machine tool 50 will be described. Figures 3 to 5 show examples of jigs used in this embodiment. All of these jigs are clamping devices for positioning and fixing a workpiece at a predetermined position, and perform a clamping operation to tighten the workpiece and an unclamping operation to loosen the workpiece.

[0031] 3 is a link clamp type clamp device. This clamp device operates from the unclamped state shown in (a) as indicated by the arrow in (b) to clamp the workpiece W in the vertical direction.

[0032] 4 is a side clamp type clamp device. This clamp device operates from the unclamped state shown in (a) as indicated by the arrow in (b) to clamp the workpiece W in the horizontal direction.

[0033] 5 is a positioning pin type clamping device that can expand and contract its diameter inside a hole h formed in the workpiece W. This clamping device expands its diameter from an unclamped state with a contracted diameter as shown in (a) as indicated by the arrow in (b), clamping the workpiece W in the radial direction of the hole h.

[0034] In the case of a workpiece having a complex shape, various jigs are used to accurately position and secure a workpiece to the jig, depending on the shape of the workpiece. The optimal order in which these jigs should be operated, and whether jig operations need to be changed or added, are then verified through trial and error, and the best operation sequence and operation modes are determined through this process. Therefore, it is desirable that the program for controlling jig operations be one that allows for easy changes and additions to the operation sequence and operation modes. For this reason, in the present invention, the jig control program, including the M-code, can be freely edited on the screen of the display unit 62 of the operation panel 60 (details will be described later).

[0035] Next, the basic mechanism of the present invention will be described with reference to Fig. 6. In Fig. 6, the left side shows the operation of CPU1, which is the first control unit, and the right side shows the operation of PMC3, which is the second control unit. Here, it is assumed that four jigs A to D are used.

[0036] After the program processing unit 11 starts the program (T1), the CPU 1 starts reading and storing the M-codes that represent the jig operations (T2). Then, the auxiliary function command unit 12 of the CPU 1 reads the M-codes that represent the operations of jigs A to D from the jig control program in order (T3 to T6) and sends the read M-codes to the PMC 3. In the PMC 3, the auxiliary function processing unit 31 stores the M-codes received from the CPU 1 in the M-code table 32. The M-codes that correspond to the operations of jigs A to D are stored in the M-code table 32 in the order described in the jig control program.

[0037] Then, when the CPU 1 confirms the completion of reading and storing the M codes (T7), in the PMC 3, the auxiliary function processing unit 31 reads the M codes from the M code table 32 in the order in which they were stored, and executes the jig operation commanded by each M code (T8-T11). Meanwhile, on the CPU 1 side, while the PMC 3 is executing the jig operation, another program is executed in parallel (T12). In this case, an axis position correction program is executed as the other program. The axis position correction program is a program for correcting the axis position of an axis in which a position error has occurred due to the influence of heat or the like.

[0038] When the axis position correction is completed, the CPU 1 confirms that all jig operations in the PMC 3 are completed (T13), and then performs machining on the workpiece according to the machining program (T14). Then, when machining is completed, the program ends (T15).

[0039] Fig. 7 shows an example of a program for executing the processes T1 to T7 in Fig. 6. Fig. 8 shows an example of the M code table 32 in which data is stored.

[0040] In Figure 7, the first "O00001" is a program start command, which corresponds to T1 in Figure 6. "M330" is an M code that commands the start of reading and storing M codes that represent jig operations, which corresponds to T2 in Figure 6. "M98P9800" is an M code that commands the call of a subprogram, and when this is read, it transitions to the subprogram enclosed by the dashed line. This subprogram is a jig control program, which corresponds to T3 to T6 in Figure 6.

[0041] In the subprogram, the "O9800" at the beginning indicates that the program in question is a jig control program. The next block, "M160 M162 M164," is an M code that commands the operation of three jigs A to C. For example, "M160" commands the tightening of jig A, "M161" commands the tightening of jig B, and "M164" commands the tightening of jig C. The following block, "M170," is an M code that commands jig A to be in the neutral position.

[0042] The "#1134=500" block is a command expressed as a macro variable, and is a code that commands a 500 millisecond primary pause. The next "M332" block is an M code that commands storing the previous #1134 value, 500, as the timer value (pause time). Note that "#1134=500" has the same meaning as "G04P500" when using the G code, which is a command code for the preparation function.

[0043] The "M166" block is an M code that commands the tightening of jig D. The "M167" block is an M code that commands the loosening of jig D. The next "M166" block is an M code that commands the tightening of jig D again. The final "M160" block is an M code that commands the tightening of jig A and the release of neutral.

[0044] When the subprogram ends, the M-code "M99" indicating this is read, and the program moves to "M331" which commands the end of M-code reading and storage. This M-code "M331" corresponds to T7 in Figure 6.

[0045] As can be seen from Fig. 7, the subprogram contains seven blocks each containing an M code, and seven indexes i (i = [0] to [6]) are assigned to correspond to these seven blocks, respectively. Then, while the subprogram is being executed, the numerical values ​​of the M codes of each block are stored in the M code table 32 in the order of the index i, as shown in Fig. 8.

[0046] 8, the M code table 32 includes an index area In, code areas R7000 to R7200, and a timer area R7300. In the index area In, index numbers are assigned to each block of the M code in accordance with the number of blocks. The code areas R7000 to R7200 are areas where the numerical values ​​of the M code corresponding to each index number are stored. The timer area R7300 is an area where the timer value defined by the macro variable is stored.

[0047] Figure 9 shows an example of changing the jig control program on the control panel 60 of Figure 2. As mentioned above, for workpieces with complex shapes, the operating sequence and operating modes are verified using various jigs, and in this case, it becomes necessary to change the order of M-codes in the program or add new M-codes. As an example, Figure 9 shows the procedure for adding a new M-code "M160."

[0048] First, as shown in Figure 9(a), move cursor K to the location where you want to add an M code on the screen of display unit 62, where the program is displayed. Next, operate keys 61a (see Figure 2) of operation unit 61 of operation panel 60 to input "M160;" in input field 62a at the bottom of display unit 62, as shown in Figure 9(b). This adds the M code "M160" at the position of cursor K, as shown in Figure 9(c).

[0049] In this manner, in this embodiment, the jig control program including the M-codes is displayed on the display unit 62 of the operation panel 60, and since the M-codes have a simple format, the user can easily identify the M-codes in the program on the screen. Furthermore, by referring to the M-code list, the user can easily understand the function of each M-code. Furthermore, if it becomes necessary to change the operating sequence or operating mode of the jig, the program can be easily edited by operating the operation unit 61, so the user can handle the change themselves without relying on a specialized engineer.

[0050] FIG. 10 is a flowchart showing the operation of the control device 10 of the present invention. In step S1, the machining program is started (corresponding to T1 in FIG. 6). In step S2, reading and storing of M-codes representing jig operations is started (corresponding to T2 in FIG. 6). In step S3, the jig control program, which is a subprogram, is called. In step S4, M-codes in the jig control program are read sequentially and stored in the M-code table 32 (corresponding to T3 to T6 in FIG. 6). In step S5, the subprogram ends. In step S6, reading and storing of M-codes ends (corresponding to T7 in FIG. 6).

[0051] In steps S7 and S8, the tightening operation of jig A is performed. In steps S9 and S10, the tightening operation of jig B is performed. In steps S11 and S12, the tightening operation of jig C is performed. In steps S13 and S14, the tightening operation of jig D is performed (corresponding to T8 to T11 in FIG. 6).

[0052] While the operations of steps S7 to S14 are being performed on the PMC 3 side, on the CPU 1 side, in step S15, the axis control circuit 4 performs position correction for the reference axes X-axis, Y-axis, and Z-axis (corresponding to T12 in FIG. 6). Then, when this axis position correction process is completed, in step S16, the tool changer 53 changes the tool attached to the spindle.

[0053] In step S17, it is determined whether the tightening operation of jigs A to D has been completed (corresponding to T13 in FIG. 6). If the determination result is YES, in step S18, machining of the workpiece based on the machining program is started (corresponding to T14 in FIG. 6). In step S19, it is determined whether the machining has been completed, and if the determination result is YES, the series of operations ends (corresponding to T15 in FIG. 6).

[0054] 11 is a flowchart showing the operation of a conventional control device. For convenience, steps that perform the same processing as in FIG. 10 are given the same reference numerals as in FIG.

[0055] As can be seen by comparing Fig. 10, steps S2, S4, and S6 from Fig. 10 do not exist in Fig. 11. Furthermore, in steps S7 to S14 in Fig. 11, each time an M code in the subprogram is read, the operations of jigs A to D corresponding to that M code are executed sequentially. For this reason, other programs such as steps S15 and S16 cannot be executed between steps S7 to S14.

[0056] In contrast, in the case of Figure 10, in step S4, which is the greatest feature of the present invention, the M codes in the subprogram are read sequentially and the read M codes are stored sequentially in the M code table 32. The time required for reading and storing the M codes is extremely short and does not affect the cycle time. Then, once the M codes have been stored, they are read sequentially from the M code table 32, and the processing of steps S7 to S14 (operation of jigs A to D) is executed sequentially according to the command content of each M code. In other words, in step S4, only the reading and storage of the M codes to create the M code table 32 is performed, and the M codes themselves are not executed. The M codes are executed based on the M code table 32, which is created to resemble the execution environment of the M codes.

[0057] Therefore, in the case of the present invention, when reading and storing of the M-code is completed, the PMC 3 side can immediately start the operation of jigs A to D (steps S7 to S14), and the CPU 1 side can immediately execute other operation programs, such as axis position correction (step S15) and spindle tool replacement (step S16), in parallel with the operation of jigs A to D. Therefore, the cycle time can be significantly reduced compared to the conventional case of FIG.

[0058] Fig. 12 shows an example of a program according to another embodiment of the present invention. Here, macro variables are used instead of M-codes as operation commands for the jigs (the part enclosed in a bold frame). A macro variable consists of a # symbol followed by a number, and is expressed as #800. For example, "#800=160" indicates that the number 160 is substituted for variable #800, and, like "M160," commands the tightening operation of jig A. By using such macro variables, a table similar to that in Fig. 8 can be created, and the same effect as when M-codes are used can be obtained.

[0059] In the above-described embodiment, an example has been given of controlling the operation of a jig, but the present invention can also be applied to controlling operations other than a jig, such as spindle rotation, tool replacement, and coolant discharge. [Explanation of symbols]

[0060] 1 CPU (first control unit) 2 Storage section 3 PMC (2nd control section) 10 Machine tool control device 11 Program Processing Section 12 Auxiliary function command section 13-axis control command unit 31 Auxiliary function processing section 32 M Code Table 50 NC machine tools 52, 52a, 52b, 52c Jigs 60 Control panel 61 Operation section 62 Display section 100 NC machine tool control system

Claims

1. A control device for controlling the operation of an NC (Numerical Control) machine tool, a first control unit including a CPU that controls the entire control device in accordance with a system program; a second control unit comprising a PMC (Programmable Machine Controller) that controls the machine tool in accordance with a control program including M-codes that command predetermined operations; a storage unit in which the system program and the control program are stored, the second control unit is provided with an M code table in which M codes in the control program are sequentially stored, The first control unit When the control program is started, the M-codes included in the control program are read in order and sent to the second control unit; The second control unit is The M-codes received from the first control unit are sequentially stored in the M-code table; When the storage of the M codes is completed, the command contents of each M code are executed in order according to the order of the M codes stored in the M code table. The first control unit A control device for a machine tool, characterized in that while the second control unit is executing the command contents of each of the M-codes, another program is executed.

2. the control program is a jig control program for controlling the operations of a plurality of jigs, and includes a plurality of M-codes for instructing the operations of the respective jigs; 2. The control device for a machine tool according to claim 1, wherein the second control unit controls the operation of each of the plurality of jigs in accordance with the order of the M-codes stored in the M-code table.

3. The M code table is an index area in which index numbers corresponding to the number of blocks of M code in the control program are assigned; a code area indicating a numerical value of an M code, the code area being provided corresponding to each of the index numbers; The second control unit is 2. A machine tool control device according to claim 1, wherein the command contents of each M-code in said code area are executed sequentially in accordance with the order of said index numbers.

4. The control program is displayed on a display unit of an operation panel attached to the NC machine tool, 2. The control device for a machine tool according to claim 1, wherein said M-code can be edited on the screen of said display unit by performing a predetermined operation on said operation panel.

5. 2. The machine tool control device according to claim 1, wherein a macro variable is used instead of the M code.

6. A control method for the machine tool control device according to claim 1, comprising: When the control program is started, the first control unit sequentially reads the M-codes included in the control program and sends the M-codes to the second control unit; the second control unit sequentially storing the M-codes received from the first control unit in the M-code table; when the storage of the M-codes is completed, the second control unit sequentially executes the command contents of each M-code in accordance with the order of the M-codes stored in the M-code table; a step in which the first control unit executes another program while the second control unit executes the command contents of each of the M-codes.

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