Control device and method for controlling machine tool

Abstract

The control device (2) operates each of a plurality of systems independently according to NC programs (3-1, 3-2), which are a plurality of machining programs corresponding to each of a plurality of systems possessed by a machine tool, and is characterized in that it includes an axis feed speed determination unit (23) that, when one of the plurality of systems is set as a system to be monitored, adjusts the feed axis movement speed of the speed adjustment system, which is a system other than the system set as the system to be monitored.

Description

[Technical field]

[0001] The present disclosure relates to a control device for controlling a machine tool having a plurality of systems and a method for controlling the machine tool. [Background technology]

[0002] A numerical control device is a device that controls the operation of a machine tool according to a machining program. In a machine tool, vibrations of each part of the machine tool may affect the machining accuracy. For example, Patent Document 1 discloses a technique for synchronizing a feed rate command signal and a spindle speed command signal in order to suppress chatter vibrations caused by resonance between a tool attached to the machine tool and a workpiece. In the technique disclosed in Patent Document 1, when the feed rate command signal changes, the spindle speed command signal is changed in synchronization with the change in the feed rate command signal. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 11-300578 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the above-mentioned conventional technology, when machining using a machine tool equipped with multiple systems, while one system is machining, the movement of the feed axis in the other system causes vibration, which may result in a decrease in machining accuracy. In particular, in machining that requires high machining accuracy, such as finishing, the impact of vibration on machining accuracy is significant.

[0005] The present disclosure has been made in consideration of the above, and aims to provide a control device in a machine tool having multiple systems that is capable of reducing the effect of the operation of one system that executes machining commands on the operation of the other systems, thereby improving machining accuracy. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems and achieve the objective, the control device disclosed herein is a control device that operates each of multiple systems independently in accordance with multiple machining programs corresponding to each of the multiple systems possessed by a machine tool, and is characterized in that it has an axis feed speed determination unit that, when one of the multiple systems is set as a monitored system, adjusts the feed axis movement speed of a speed adjustment system other than the system set as the monitored system. Effect of the Invention

[0007] The control device according to the present disclosure has the effect of reducing the effect of the operation of one system executing a machining command on the operation of the other systems in a machine tool equipped with multiple systems, thereby making it possible to improve machining accuracy. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing an example of the configuration of a machine tool to be controlled in the first embodiment; [Diagram 2] FIG. 1 is a diagram showing an example of a configuration of a control device according to a first embodiment; [Diagram 3] A diagram showing an example of an NC program corresponding to a system to be monitored [Figure 4] A diagram showing an example of an NC program that corresponds to the speed adjustment system [Diagram 5] FIG. 1 is a diagram showing dedicated hardware for implementing the functions of a control device according to a first embodiment. [Figure 6] FIG. 1 is a diagram showing a configuration of a control circuit for implementing the functions of a control device according to a first embodiment; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] A control device and a method for controlling a machine tool according to an embodiment of the present disclosure will be described in detail below with reference to the drawings. Note that the technical scope of the present disclosure is not limited to the embodiments described below.

[0010] Embodiment 1 1 is a diagram showing an example of the configuration of a machine tool 1 to be controlled in the first embodiment. The machine tool 1 is, for example, a lathe. The machine tool 1 includes a tool 11 for machining the front surface of a workpiece, a tool 12 for machining the back surface of the workpiece, and a transport machine 14 for carrying the workpiece in and out of a machining chamber 13.

[0011] Here, front machining is an example of the main machining performed by machine tool 1, and the system that operates tool 11 is an example of a main system that performs the main machining of machine tool 1, and is called the first system. The system that operates tool 12 and the system that operates conveyor 14 are secondary systems that perform machining other than the main machining. The system that operates tool 12 is called the second system, and the system that operates conveyor 14 is called the third system. Machine tool 1 has multiple systems, namely the first system, the second system, and the third system.

[0012] FIG. 2 is a diagram showing an example of the configuration of the control device 2 according to the first embodiment. The control device 2 is a numerical control device that controls the machine tool 1 according to NC (Numerical Control) programs 3-1 and 3-2. Specifically, the control device 2 can control the operation of the machine tool 1 by outputting commands to a drive unit 6 provided in the machine tool 1 according to the NC programs 3-1 and 3-2. The NC programs 3-1 and 3-2 are also called machining programs. The control device 2 can acquire information input from an operation panel 4 via a PLC (Programmable Logic Controller) 5. The control device 2 has a program analysis unit 21, a parameter storage unit 22, an axis feed speed determination unit 23, and a control unit 24.

[0013] Incidentally, the driving unit 6 is an object to be controlled by the control device 2, and although omitted in Fig. 1, it is provided in the machine tool 1. Although the driving unit 6 is shown as one functional unit in Fig. 2, the driving unit 6 includes a plurality of amplifiers, motors, etc. corresponding to each of a plurality of systems that the machine tool 1 has.

[0014] The control device 2 controls the operation of each system according to a plurality of NC programs 3-1, 3-2 corresponding to each of the multiple systems of the machine tool 1. As a result, the feed axes of each system of the machine tool 1 operate independently. The control device 2 also has a function of adjusting the feed axis movement speed of one of the multiple systems of the machine tool 1 according to the operating status of the other system. This function is called the "inter-system speed override mode." In addition, in the inter-system speed override mode, the system that commands the other system is called the "monitored system," and the system whose speed is adjusted is called the "speed adjustment system." The speed adjustment system is a system other than the monitored system. When the machine tool 1 has three or more systems, all of the multiple systems of the machine tool 1 other than the monitored system may be the speed adjustment system, or some of the systems other than the monitored system may be the speed adjustment system.

[0015] The NC programs 3-1 and 3-2 are examples of machining programs describing the operation of the machine tool 1. The NC program 3-1 corresponds to the main system, and describes commands that instruct, for example, the cutting feed rate, the amount of movement of each axis, the start and end of the inter-system speed override mode, the designation of the monitored system mode, the inter-system override mode section, etc. Here, the cutting feed rate is a command value for the movement rate of the feed axis of the main system during cutting, the amount of movement of each axis is a command value for the movement amount of each axis of the main system, the monitored system mode is an operation mode in which the system operates as the monitored system while operating in the inter-system speed override mode, and the inter-system override mode section is a section in which the system is operated in the inter-system override mode.

[0016] The NC program 3-2 corresponds to the secondary system, and describes commands for instructing, for example, the axis feed speed, the amount of movement of each axis, the start and end of the inter-system speed override mode, the designation of the speed adjustment system mode, the speed override set value, etc. Here, the axis feed speed is a command value for the movement speed of the feed axis of the secondary system, the amount of movement of each axis is a command value for the movement amount of each axis of the secondary system, the speed adjustment system mode is an operation mode in which the system operates as a speed adjustment system while operating in the inter-system speed override mode, and the speed override set value is a speed override set value used while operating in the inter-system override mode. The NC program 3-2 is input to the control device 2 in the same number as the number of secondary systems of the machine tool 1.

[0017] The program analysis unit 21 analyzes the NC programs 3-1, 3-2 and outputs the analysis results to the axis feed speed determination unit 23. Specifically, the program analysis unit 21 distinguishes between the inter-path speed override mode command, the monitored path mode command, the speed adjustment path mode command, and the like described in the NC programs 3-1, 3-2, and outputs the distinguished results as the analysis results to the axis feed speed determination unit 23. In addition, the program analysis unit 21 outputs the amount of movement of each axis, the cutting feed speed, the axis feed speed, and the override setting value in the inter-path speed override mode commanded by the NC programs 3-1, 3-2 to the axis feed speed determination unit 23 as the analysis results.

[0018] The parameter storage unit 22 stores a fast-forward speed, which is an axial feed speed when a fast-forward command is issued in the NC programs 3-1 and 3-2 and is set by an NC parameter, and outputs the fast-forward speed to the axial feed-speed determination unit 23. The parameter storage unit 22 can store, for example, a fast-forward speed input in advance from outside the control device 2.

[0019] The axial feed rate determination unit 23 determines the feed axis movement speed and outputs an axial feed rate command indicating the determined feed axis movement speed to the control unit 24. The axial feed rate determination unit 23 can determine the feed axis movement speed by multiplying a predetermined set value of the feed rate or a command value described in the NC programs 3-1 and 3-2 by an axial feed rate override set value. The axial feed rate determination unit 23 can adjust the feed axis movement speed of the speed adjustment system by changing the axial feed rate override set value. The axial feed rate determination unit 23 receives the axial feed rate override set value input from the operation panel 4 via the PLC 5 and acquires the fast traverse speed from the parameter storage unit 22. The axial feed rate determination unit 23 also acquires the analysis result from the program analysis unit 21. The axial feed rate determination unit 23 can determine the feed axis movement speed based on the acquired information. Specifically, the axial feed rate determination unit 23 can determine the feed axis movement speed in different ways depending on whether or not the system is in the inter-system speed override mode based on the analysis result. When not in the inter-path speed override mode, the axis feedrate determination unit 23 can determine the final axis feedrate based on the axis feedrate override setting value acquired from the PLC 5 and the axis feedrates commanded from the NC programs 3-1 and 3-2. When in the inter-path speed override mode, the axis feedrate determination unit 23 determines the axis feedrate of the speed adjustment system using the axis feedrate override setting value and axis feedrate commanded from the NC program 3-2, not the axis feedrate override setting value from the PLC 5.

[0020] The control unit 24 calculates a position command per control time unit from the axial feed speed and the amount of movement of each axis output by the axial feed speed determination unit 23, and outputs the calculated position command to the drive unit 6.

[0021] The program analysis unit 21, the axial feed speed determination unit 23, and the control unit 24 each perform the above-mentioned operations for each system to be driven. A position command is output for each object to be driven.

[0022] Here, the operation of the control device 2 will be described using specific examples of the NC programs 3-1 and 3-2. Here, Fig. 3 is a diagram showing an example of an NC program corresponding to a system to be monitored. Fig. 4 is a diagram showing an example of an NC program corresponding to a speed adjustment system.

[0023] Here, the first system, which is the main system described above, is the system to be monitored, and the third system, which is the secondary system and operates the conveyor 14, is the speed adjustment system. In Figs. 3 and 4, "N01" at the beginning of a line is a sequence number and indicates the line number of the block. In each NC program, the commands written in the block are executed in the order of the sequence number. Although the time required to process each block differs for each system, "N05" in Figs. 3 and 4 is a waiting command, so even if the processing time from "N01" to "N05" differs for each system, the command "N06" in Fig. 3 and the command "N06" in Fig. 4 are executed simultaneously. "G177 P1" in "N06" in Fig. 3 is a command to start the inter-system speed override mode, and "P1" sets the own system as the system to be monitored. "G177 P2 J1 D20" of "N06" in Fig. 4 is also a start command for the inter-system speed override mode, and "P2" sets the own system as the speed adjustment system, "J1" sets the first system as the monitored system, and "D20" sets the axis feed speed override setting value to 20%. "G177 P0" of "N16" in Fig. 3 is an end command for the inter-system speed override mode. "G177 P0" of "N19" in Fig. 4 is also an end command for the inter-system speed override mode. In the speed adjustment system, after the start command for the inter-system speed override mode is executed, the axis feed speed of the speed adjustment system operates at the speed determined using the axis feed speed override setting value specified in "N06" in Fig. 4 until the end command for the inter-system speed override mode is executed in the monitored system or the own system. In the illustrated example, in "N07" and "N08" in Fig. 4, the speed override setting value is changed from the normal 100% to 20%, and at the time when "N16" is executed, the end command of the inter-system speed override mode of "N16" in Fig. 3 has been executed in the monitored system, so the fast-forward command of "N16" in Fig. 3 is executed with the speed override setting value returned to 100%. In other words, in the speed regulating system, when the end command of the inter-system speed override mode is executed in the monitored system, the inter-system speed override mode is ended even before the end command is executed in the speed regulating system.Therefore, in "N16" in Fig. 4, operation will be performed at the fast-forward speed x 100% even before the end command of the inter-path speed override mode in "N19" in Fig. 4. Note that, depending on the processing time of each block, the command of "N16" in Fig. 3 may not be executed at the time the command of "N16" in Fig. 4 is executed. In this case, the fast-forward command of "N16" in Fig. 4 is executed using "20%" as the speed override setting value.

[0024] As described above, the speed override setting value is changed until an end command of the inter-system speed override mode is executed in the monitored system or the speed adjustment system. Therefore, in the monitored system, a start command and an end command may be written in the corresponding NC program so that the system is in the inter-system speed override mode during a period in which an operation that is caused by the operation of the speed adjustment system and that requires reduction, such as finishing, is performed. In addition, in the speed adjustment system, a start command and an end command may be written in the corresponding NC program so that the system is in the inter-system speed override mode during a period in which an operation that affects the monitored system, such as an operation that generates vibration, such as movement of the feed axis, is performed. At this time, by setting the speed override setting value in the inter-system speed override mode to a value smaller than the normal 100%, it is possible to reduce the impact on the monitored system caused by the operation of the speed adjustment system by lowering the feed axis movement speed of the speed adjustment system.

[0025] The end command of the inter-system speed override mode of "N16" in Fig. 3, together with the start command of "N06", is a command that specifies the period during which the system operates in the inter-system speed override mode. If the speed of the speed-adjusted system is reduced by the inter-system speed override mode compared to periods other than the mode, productivity will decrease, but by specifying a specific period and operating in the inter-system speed override mode, it is possible to suppress the decrease in productivity.

[0026] In the example shown in FIG. 4, one system to be monitored is specified in the speed adjustment system, but multiple systems to be monitored can also be specified from the NC program. Here, the system to be monitored does not necessarily have to be the main system, and a secondary system other than the system itself can be specified as the system to be monitored. Also, the speed adjustment system does not necessarily have to be a secondary system, and the main system can be the speed target system. For example, if it is desired to adjust the axial feed speed of the other system using the axial feed speed override setting value during back surface finishing, the system to be monitored can be set as the second system, and the first and third systems can be set as the speed adjustment systems.

[0027] In this embodiment, the axis feed speed override setting value of the speed adjustment system during the inter-system speed override mode is valid only for the command value from the NC program. In other words, when the axis feed speed determination unit 23 determines that the system is in the inter-system speed override mode based on the analysis result of the NC program, it determines the feed axis movement speed using the axis feed speed override setting value described in the NC program, and even if an operation to change the axis feed speed override setting value is performed on the operation panel 4 during the inter-system speed override mode, values ​​other than the axis feed speed override setting value described in the NC program, such as the axis feed speed override setting value input from the operation panel 4 obtained via the PLC 5, are not used. Therefore, the operator does not need to change the axis feed speed override setting value during the inter-system speed override mode, and even if the operator erroneously changes the axis feed speed override setting value using the operation panel 4, the axis feed speed of the speed adjustment system will not change. This eliminates the need for the operator to determine the axis feed speed override setting value and to input the determined value, and also prevents the occurrence of a situation in which machining accuracy is reduced due to erroneous operation.

[0028] In addition, in the dedicated command for realizing the function described in this embodiment, it is possible to select whether the system corresponding to the NC program operates in the monitored system mode or the speed adjustment system mode by the "P address". When the speed adjustment system mode is selected, the monitored system can be specified by the "J address" and the axial feed speed override setting value during the inter-system speed override mode can be specified by the "D address". In this case, by specifying multiple systems in the "J address", such as "J1J2", multiple systems can be specified as monitored systems. "J1J2" means that the first system and the second system are specified as monitored systems. In this way, by providing a dedicated programming command that can change the axial feed speed override setting value of the other systems, it is possible to improve the machining accuracy and suppress the decrease in productivity while reducing the burden on the operator of speed adjustment.

[0029] Next, a hardware configuration of the control device 2 according to the first embodiment will be described. The program analysis unit 21, the parameter storage unit 22, the axial feed speed determination unit 23, and the control unit 24 of the control device 2 are realized using processing circuits. The processing circuits may be realized by dedicated hardware, or may be control circuits using a CPU (Central Processing Unit).

[0030] When the above processing circuits are realized by dedicated hardware, they are realized using a processing circuit 90 shown in Fig. 5. Fig. 5 is a diagram showing dedicated hardware for realizing the functions of the control device 2 according to the first embodiment. The processing circuit 90 is a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or a combination of these.

[0031] When the above processing circuit is realized by a control circuit using a CPU, the control circuit is, for example, a control circuit 91 having a configuration shown in FIG. 6. FIG. 6 is a diagram showing a configuration of the control circuit 91 for realizing the functions of the control device 2 according to the first embodiment. As shown in FIG. 6, the control circuit 91 includes a processor 92 and a memory 93. The processor 92 is a CPU, and is also called a processing device, an arithmetic device, a microprocessor, a microcomputer, a DSP (Digital Signal Processor), or the like. The memory 93 is, for example, a non-volatile or volatile semiconductor memory such as a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, an EPROM (Erasable Programmable ROM), or an EEPROM (registered trademark) (Electrically EPROM), a magnetic disk, a flexible disk, an optical disk, a compact disk, a mini disk, or a DVD (Digital Versatile Disk).

[0032] When the above processing circuit is realized using the control circuit 91, it is realized by the processor 92 reading and executing a program corresponding to the processing of each component, which is stored in the memory 93. The memory 93 is also used as a temporary memory for each process executed by the processor 92. The program executed by the processor 92 may be provided in a state stored in a storage medium, or may be provided via a communication path such as the Internet.

[0033] As described above, the control device 2 according to the first embodiment is a control device 2 that operates each of the multiple systems independently according to the NC programs 3-1 and 3-2, which are multiple machining programs corresponding to each of the multiple systems possessed by the machine tool 1, and includes an axis feed speed determination unit 23 that adjusts the feed axis movement speed of the speed adjustment system, which is a system other than the system set as the monitored system, when one of the multiple systems is set as a monitored system. With such a configuration, the control device 2 can adjust the feed axis movement speed of the other system according to the operating status of one of the multiple systems possessed by the machine tool 1. In the machine tool 1 having multiple systems, the feed axis movement speed of one of the multiple systems may affect the operation of the other systems. For example, while one system is performing machining that requires machining accuracy, such as finishing machining, if the other system is performing feed axis movement, for example, transportation of a workpiece by a gantry loader, the machining accuracy may decrease due to vibration during transportation. For example, by reducing the feed axis movement speed of the other system during the period in which finishing machining is performed compared to the period other than the period in which finishing machining is performed, the occurrence of vibration can be suppressed and the machining accuracy can be improved. Furthermore, when performing operations that do not affect machining accuracy, productivity can be improved by increasing the feed axis movement speed.

[0034] If the operation of the other system is stopped at this time, the vibration will not be caused, but the productivity will decrease. Therefore, it is desirable to set the feed axis movement speed of the speed adjustment system to a positive value and to be slower during the period when the system is operating in the inter-system speed override mode than during other periods. This makes it possible to suppress the decrease in productivity.

[0035] The axis feed speed determination unit 23 determines the feed axis movement speed by multiplying a predetermined set value of the feed speed or a command value described in the machining program by the axis feed speed override set value, and adjusts the feed axis movement speed of the speed adjustment system by changing the axis feed speed override set value. The axis feed speed determination unit 23 can adjust the feed axis movement speed of the speed adjustment system by using the axis feed speed override set value described in the machining program. By describing the axis feed speed override set value used during the inter-system speed override mode in the NC program 3-2, the operator can adjust the feed axis movement speed of the speed adjustment system without taking the time and effort of adjusting the axis feed speed override set value.

[0036] When a start command for instructing the start of an inter-path speed override mode, which is an operation mode for adjusting the feed axis movement speed of the speed adjustment path according to the operation state of the monitored path, is written in a machining program corresponding to one of the multiple paths, the axis feed speed determination unit 23 adjusts the feed axis movement speed of the speed adjustment path using the override setting value written in the machining program in response to the start command. Also, when a command for specifying a period for operating in the inter-path speed override mode is written in the machining program corresponding to the monitored path, the axis feed speed determination unit 23 adjusts the feed axis movement speed of the speed adjustment path for the period specified by the command. This makes it possible to specify a period for operating in the inter-path speed override mode from the NC program and adjust the speed only for a specific period. Therefore, it becomes possible to reduce the speed only for the minimum necessary period, thereby suppressing unnecessary decline in productivity.

[0037] In addition, the axis feed speed determination unit 23 can adjust the feed axis movement speed of each of the multiple speed adjustment systems according to the operating status of the system to be monitored. By making it possible to specify multiple systems for which speed adjustment is to be performed, it becomes possible to appropriately adjust the speed even in a machine tool 1 having three or more systems.

[0038] Furthermore, when the system set as the monitored system is affected by the operation of the speed adjustment system, the speed determination unit can reduce the feed shaft movement speed of the speed adjustment system, thereby making it possible to reduce the effect on the monitored system caused by the operation of the speed adjustment system.

[0039] The configurations shown in the above embodiments are merely examples, and may be combined with other known technologies. Parts of the configurations may be omitted or modified without departing from the spirit of the invention.

[0040] For example, while the machine tool 1 has three systems in the above example, the number of systems in the machine tool 1 may be any number, and may be two, four or more. Also, while the control device 2 is described above as a device separate from the machine tool 1, the control device 2 may be built into the machine tool 1. [Explanation of symbols]

[0041] 1 machine tool, 2 control device, 3-1, 3-2 NC program, 4 operation panel, 5 PLC, 6 drive unit, 11, 12 tool, 13 machining room, 14 conveyor, 21 program analysis unit, 22 parameter storage unit, 23 axis feed rate determination unit, 24 control unit, 90 processing circuit, 91 control circuit, 92 processor, 93 memory.

Claims

1. A control device for independently operating a plurality of systems in a machine tool in accordance with a plurality of machining programs corresponding to each of the systems, comprising: an axis feed speed determination unit that, when one of the multiple systems is set as a monitored system by a command written in the machining program corresponding to that system, and when that system is set as a speed adjustment system that adjusts a feed axis movement speed in accordance with an operating state of the monitored system by a command written in the machining program corresponding to that system other than the system set as the monitored system, adjusts the feed axis movement speed of the speed adjustment system by multiplying a feed speed by an override setting value written in the machining program corresponding to that speed adjustment system Equipped A control device comprising:

2. The axis feed speed determination unit determines the feed axis movement speed by multiplying a predetermined set value of the feed speed or a command value described in the machining program by the override set value, and adjusts the feed axis movement speed of the speed adjustment system by changing the override set value. The control device according to claim 1 .

3. When a start command for instructing the start of an inter-path speed override mode, which is an operation mode for adjusting the feed axis movement speed of the speed adjustment path in accordance with the operation state of the monitored path, is described in the machining program corresponding to any one of the multiple paths, the axis feed speed determination unit adjusts the feed axis movement speed of the speed adjustment path using the override setting value described in the machining program in response to the start command. The control device according to claim 1 .

4. When a command specifying a period during which the system is to operate in the inter-system speed override mode is described in the machining program corresponding to the system to be monitored, the feed axis moving speed of the speed adjustment system is adjusted for the period specified by the command.

4. The control device according to claim 3.

5. The axis feed speed determination unit adjusts the feed axis movement speed of each of the multiple speed adjustment systems in accordance with the operating status of the monitored system. The control device according to claim 1 .

6. The axis feed speed determination unit reduces the feed axis movement speed of the speed adjustment system when the system set as the monitored system is affected by the operation of the speed adjustment system. The control device according to claim 1 .

7. A method for controlling a machine tool, in which a control device controls a machine tool, the control device causing a plurality of systems to operate independently in accordance with a plurality of machining programs corresponding to each of the systems, the control device comprising: a step of adjusting a feed axis moving speed of the speed adjustment system by multiplying a feed speed by an override setting value described in the machining program corresponding to the speed adjustment system when the system is set as a monitored system by a command described in the machining program corresponding to the system other than the system set as the monitored system, and the system is set as a speed adjustment system for adjusting a feed axis moving speed in accordance with an operating state of the monitored system by a command described in the machining program corresponding to the system, Includes A method for controlling a machine tool comprising:

Images