Numerical Control Calculation System

Abstract

To achieve safe stop while shortening downtime at the time of occurrence of communication abnormality in a system for executing numerical control of a machine tool or the like with an external numerical control arithmetic device.SOLUTION: A numerical control arithmetic system includes: automated machines 9, 11, 13 and 15 corresponding to numerical control; numerical control arithmetic devices 1, 3 and 5 connected to the automated machines through a communication line 7 to calculate control data for operating the automated machines and transmit the control data to the automated machines; and communication monitoring units 2, 4, 6 and 8 for monitoring a communication state between the numerical control arithmetic devices and the automated machines. The communication monitoring units stop transmitting the control data to the automated machines up to a block satisfying a prescribed safe condition among blocks of the control data stored in an internal buffer when a communication abnormality is detected.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a numerical control calculation system. [Background technology]

[0002] In recent years, advances in communication technology have made it possible to stably communicate large volumes of data with low latency. For this reason, it has been considered to connect remote computer devices via communication lines to multiple automated machines that support numerical control, such as machine tools and robots, and to perform control that requires advanced calculations, such as synchronous control, prevention of interference between machines, and improvement of operation through machine learning (see, for example, Patent Document 1).

[0003] Real-time performance and safety are essential for the numerical control of machine tools and robots. Therefore, it is important to deal with communication abnormalities caused by communication interruption or abnormalities in the numerical control calculation device.

[0004] When a communication abnormality occurs, it is important not only to safely stop machine tools, robots, etc., but also to minimize downtime. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2016-71407 A Summary of the Invention [Problem to be solved by the invention]

[0006] The purpose is to provide a system in which numerical control of machine tools, etc. is performed by an external numerical control calculation device, where when a communication abnormality occurs, it is desirable to safely stop the machine tools, etc. while shortening downtime. [Means for solving the problem]

[0007] A numerical control calculation system according to one aspect of the present disclosure includes a numerical control-compatible automated machine, and is connected to the automated machine via a communication line and calculates control data for operating the automated machine. Number and a numerical control arithmetic device, and further comprising a communication monitoring unit interposed between the numerical control arithmetic device and the automated machine. The communication monitoring unit includes an internal buffer that stores the control data from the numerical control arithmetic device in units of blocks, a communication control unit that sequentially transmits the stored control data in units of blocks to the automated machine, a safety determination unit that determines whether or not each of the blocks satisfies a predetermined safety condition, and a normal / abnormal communication state of the communication line. Make a judgment on and a communication abnormality determination unit. The communication control unit is An abnormality was detected. When, When the block being executed at the time when the abnormality determination is made satisfies the safety condition, stopping the transmission of the control data to the automated machine to cause the automated machine to execute the operation of the block and then stop the operation; When the block being executed at the time when the abnormality determination is made does not satisfy the safety condition, the automation machine is caused to execute the operation of the block, and while sequentially executing the blocks stored in the internal buffer, if a block that satisfies the safety condition appears, the automation machine is caused to execute the operation of the block that satisfies the safety condition and then the automation machine is stopped by stopping the transmission of the control data to the automation machine after transmitting the block that satisfies the safety condition and switching the numerical control arithmetic device as the source of the control data to another numerical control arithmetic device, and while sequentially executing the blocks stored in the internal buffer, if no block that satisfies the safety condition appears, all the blocks stored in the internal buffer are executed, and then the automation machine is moved to a predetermined evacuation position and then evacuation control data is transmitted to the automation machine after transmitting all the blocks. . Effect of the Invention

[0008] According to this aspect, when a communication abnormality occurs, it is possible to safely stop a machine tool or the like while shortening downtime. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram showing the overall configuration of a numerical control calculation system according to an embodiment. [Diagram 2] FIG. 2 is a block diagram showing the configuration of the numerical control calculation system shown in FIG. [Diagram 3] FIG. 3 is a flowchart showing a processing procedure of the communication monitoring unit of FIG. [Figure 4] FIG. 4 is a diagram showing the flow of control data and feedback data in normal operation in this embodiment. [Diagram 5] FIG. 5 is a diagram showing the flow of control data and feedback data when a communication abnormality occurs in this embodiment. [Figure 6]FIG. 6 is a diagram for explaining the operation when a safety block is present and the operation when no safety block is present in this embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, a numerical control calculation system (also referred to as a production system) according to an embodiment of the present disclosure will be described with reference to the drawings. As shown in Fig. 1, the numerical control calculation system according to this embodiment has a plurality of automated machines compatible with numerical control, such as machine tools 9, 11, a robot 13, and an automatic guided vehicle (AGV) 15. The machine tools 9, 11, etc. are connected to a plurality of numerical control calculation devices 1, 3, 5 implemented as computer devices via a communication line network 7 constituting a wired or wireless in-house communication line network (LAN) or a public communication line network (Internet line network). The machine tools 9, 11 may be connected to the numerical control calculation devices 1, 3, 5 via other communication means such as serial port communication. Each of the plurality of numerical control calculation devices 1, 3, 5 is assigned in advance to one of the plurality of machine tools 9, 11, 13, 15. For example, the numerical control calculation device 1 is assigned to the machine tool 9.

[0011] Each of the numerical control arithmetic units 1, 3, 5 calculates control data for operating the machine tools 9, 11, 13, 15 assigned to it. The control data includes NC programs designated by the user, NC parameters, tool offset data, pulse number information as machine control information generated using data specific to the machine, machine input control signals, etc., and is provided with a block code for identifying blocks constituting the NC program. Each of the numerical control arithmetic units 1, 3, 5 sequentially transmits control data to the machine tools 9, 11, 13, 15 assigned to it. Each of the machine tools 9, 11, 13, 15 receives control data from the corresponding numerical control arithmetic units 1, 3, 5, operates according to the pulse number information and machine input control signals, and transmits feedback data such as machine output control signals, servo delay amounts, position data, and servo / spindle load current values ​​to the numerical control arithmetic units 1, 3, 5. Each of the numerical control arithmetic units 1, 3, 5 calculates control data using feedback data received from the machine tools 9, 11, 13, 15 assigned to it, and transmits the control data to the machine tools 9, 11, 13, 15.

[0012] Although the numerical control arithmetic units 1, 3, 5 and the machine tools 9, 11, 13, 15 are typically assigned in advance in a one-to-one relationship, one numerical control arithmetic unit 1, 3, 5 may be assigned to two or more machine tools 9, 11, 13, 15.

[0013] In this system, a plurality of communication monitoring units 2, 4, 6, 8 that monitor the communication status between the numerical control arithmetic devices 1, 3, 5 and the machine tools 9, 11, 13, 15 are interposed between the numerical control arithmetic devices 1, 3, 5 and the machine tools 9, 11, 13, 15. The communication monitoring units 2, 4, 6, 8 are independent from the automated machines 9, 11, 13, 15 so that they can be retrofitted, but they may be built into the CPU of the automated machines 9, 11, 13, 15. A communication abnormality is defined as a situation in which control data cannot be received from the machine tools 9, 11, 13, 15 for a certain period of time or more. It is assumed that the main causes of communication abnormalities are failures of the communication equipment itself and failures of the numerical control arithmetic devices 1, 3, 5, as well as occurrences during maintenance work.

[0014] 2, the numerical control arithmetic device 1 has a CPU 17, a communication interface 19, and other components that are normally included in a computer device. The CPU 17 loads and executes a system program, an arithmetic program for calculating control data, a communication program, and the like, which are stored in a storage unit (not shown), and calculates and transmits the control data assigned to, for example, a machine tool 9. The other numerical control arithmetic devices 3 and 5 have a similar configuration.

[0015] The communication monitoring unit 2 includes a buffer 201 for temporarily storing the control data received from the numerical control arithmetic device 1, a communication abnormality judgment unit 203 for judging an abnormality in the communication state such as a communication interruption or a communication delay, a safety judgment unit 205 for judging whether a block of the control data satisfies a predetermined safety condition or not and attaching a safety flag to the block that satisfies the safety condition, a communication control unit 207 for controlling the transmission (transfer) of the control data in the buffer 201 to the machine tool 9 according to the communication state, and a connection switching unit 209 for switching the connection destination as the control subject from the numerical control arithmetic device 1 to another numerical control arithmetic device 3, 5 in the event of an abnormality. The communication abnormality judgment unit 203, the safety judgment unit 205, the communication control unit 207, and the communication control unit 209 are implemented by a CPU that loads and executes a program stored in a storage unit (not shown). The other communication monitoring units 4, 6, and 8 have the same configuration.

[0016] The machine tool 9 comprises a machine tool main body 36, which is composed of a machine operation panel 35, a spindle amplifier / servo amplifier 37, a spindle motor / servo motor 39, a display 41, etc., and an intermediate processing unit (also called a control processing unit) 23 for controlling the machine tool main body 36 according to control data and displaying necessary information such as operating conditions. The intermediate processing unit 23 comprises a communication interface 25, a CPU 27, a buffer 29, a storage unit 32, a PLC (Programmable Logic Controller) 31, an axis control unit 33, a display circuit 34, etc. In addition to a system program, the storage unit 32 stores a program for realizing in the CPU 27 a means for controlling temporary storage and reading of control data and feedback data in the buffer 29, etc. The axis control unit 33 controls the spindle amplifier / servo amplifier 37 according to the control data, and generates feedback data based on pulses from a linear encoder or a rotary encoder (not shown). The other automated machines 11, 13, 15 have a similar configuration.

[0017] Next, the operation of this embodiment will be described. First, as an overview of the operation, when a communication abnormality is detected by the communication abnormality judgment unit 203 of the communication monitoring unit 2, 4, 6, 8, the communication control unit 209 transmits control data to the machine tools 9, 11, 13, 15 up to a block that satisfies a predetermined safety condition judged by the safety judgment unit 205 among the blocks of control data stored in the internal buffer 201 before the abnormality is detected, and then stops. Furthermore, when there is no block that satisfies the safety condition among the blocks of control data stored in the internal buffer 201, the communication control unit 209 continues transmission of all blocks of control data stored in the buffer 201 to the machine tools 9, 11, 13, 15, and after the transmission is completed, transmits predetermined control data for evacuation to the machine tools 9, 11, 13, 15 and displays a message indicating the communication abnormality. Note that it is also possible to display a message indicating the communication abnormality without transmitting the control data for evacuation.

[0018] A detailed description will be given below. Fig. 3 mainly shows the processing procedure of the communication monitoring unit 2. Fig. 4 shows the flow of control data and feedback data under normal circumstances. Fig. 5 shows the flow of control data and feedback data under abnormal circumstances. Note that for convenience, the operations of the numerical control arithmetic device 1, communication monitoring unit 2, and machine tool 9 will be explained here, but the operations of the other numerical control arithmetic devices 3, 5, communication monitoring units 4, 6, 8, and automated machines 11, 13, 15 are similar.

[0019] Control data is successively transmitted from the numerical control arithmetic device 1 and received by the communication monitoring unit 2 (step S1). The abnormality determination section 203 of the communication monitoring unit 2 determines whether or not the reception of the control data from the numerical control arithmetic device 1 is normal (S2). When the control data is not received for a certain period of time or longer, a "communication abnormality" is determined (NO), and a communication abnormality signal (switching signal) is transmitted to the machine tool 9. When the control data is received stably, or when the reception of the control data is interrupted but is restored within the certain period of time, "communication normal" is determined (YES).

[0020] If the answer is "YES" in step S2, the control data is temporarily stored in the buffer 201 (S3). In step S4, the safety determination unit 205 determines whether or not the control data satisfies predetermined safety conditions on a block-by-block basis. The predetermined safety conditions are appropriately set in advance according to the work content of the NC program, etc., such as that the tool is separated from the workpiece, that the spindle is not rotating, and that the position is within a predetermined range that does not interfere with other machine tools 11, 13, etc. A safety flag is attached to a block that is determined to satisfy the predetermined safety conditions (S5).

[0021] The control data is read from the buffer 201 under the control of the communication control unit 207 (S6) and transmitted (transferred) to the machine tool 9 (S7). The spindle amplifier / servo amplifier 37 drives the spindle motor / servo motor 39 under the control of the axis control unit 36. As a result, the operation described in the block is executed by the machine tool main body 36. Feedback data is acquired by the axis control unit 36 ​​based on the encoder pulse of the spindle motor / servo motor 39 (S8). The feedback data is normally transmitted to the numerical control arithmetic unit 1 via the communication monitoring unit 2, and is transmitted to the communication control unit 209 of the communication monitoring unit 2 in the event of an abnormality. Steps S1-S8 are repeated until the scheduled work is completed (S9).

[0022] If the result in step S2 is "NO" (a communication error has occurred), the control data is read from the buffer 201 to the communication control unit 207 (S11), and it is determined whether the block in question is safe or not, i.e., whether a safety flag is attached or not, based on the predetermined safety conditions and the NC program (S12). If the block in question is safe (YES), the control data for the next block is not supplied to the machine tool 9 upon completion of transmission of the control data for the current block. In other words, transmission of control data to the machine tool 9 is stopped up to the safety block. As a result, the machine tool body 36 of the machine tool 9 stops after the operation of the safety block is completed (S13). Since this block satisfies the safety conditions, the machine tool body 36 can be safely stopped.

[0023] Following step S13, the connection switching unit 209 of the communication monitoring unit 2 executes a process of switching the connection destination to the other numerical control arithmetic device 3 by referring to the connection information of the other numerical control arithmetic device 3 stored in advance (S14). Note that the process of switching the connection from the original numerical control arithmetic device 1 to the other numerical control arithmetic device 3 may be started immediately when a communication abnormality is detected, but in order to perform a smooth switching that does not affect the control operation and in consideration of the possibility that the communication with the original numerical control arithmetic device 1 may be restored while the buffer 201 is being read, it is preferable to start the process after the operation is stopped.

[0024] When the connection with the other numerical control arithmetic unit 3 is completed (S15, YES), the process returns to step S6, the control data for the next block is read from the buffer 201 and supplied to the machine tool 9 (S7), and operation is resumed from the next block. After passing through steps S8 and S9, the process returns to step S1, and the subsequent control data is received from the other numerical control arithmetic unit 3. Since the stop position is a position specified in the NC program, the operation of the next block can be immediately started directly from the stop position in accordance with the flow of the NC program. In other words, since no evacuation operation is performed and preparatory operations to detour around the evacuation position are not required, there is no effect on the control operation and downtime can be shortened.

[0025] If the block of control data currently in operation is not safe in step S12 (NO), step 21 is executed. In step 21, communication control unit 207 judges whether or not control data for the next block is stored in buffer 201. If control data for the next block is stored in buffer 201 (S21, YES), the process returns to step S6, where the control data for the next block is read from buffer 201 and supplied to machine tool 9 (S7), and the operation of the next block continues.

[0026] When the control data for the next block is not stored in buffer 201, that is, when no unoperated control data is stored in buffer 201 (S21, NO), a CPU on a communication monitoring unit (not shown) or CPU 27 calculates control data for evacuation for executing an evacuation operation to move from the position of the current block to a safe, predetermined evacuation position that has been stored in advance, and supplies this to machine tool 9. As a result, machine tool main body 36 executes the evacuation operation and stops at the safe evacuation position (S22).

[0027] After the machine tool main body 36 has stopped at a safe retreat position in step S22, a message is displayed on the display 41 or on the display of a communication monitoring unit (not shown) to inform the user that a communication abnormality has occurred and to prompt the user to perform a recovery operation, and other status display devices such as lamps and buzzers are activated (S23). Having confirmed the message or status display, the user identifies the cause as the abnormality in communication with the numerical control arithmetic unit 1 and performs work to restore communication, and issues an instruction to resume operation once this is completed. When an instruction to resume is input, the process returns to step S1 and waits for the reception of the next control data.

[0028] After the machine tool body 36 has stopped at a safe retreat position in step S22, the process may shift to step S14 to switch the connection destination to another numerical control arithmetic unit 3.

[0029] Next, this operation will be described with reference to a specific example. As shown in Fig. 6(a), control data is sequentially transmitted from the numerical control calculation device 1 to the machine tool 9 via the communication monitoring unit 2 in the order of blocks "N101", "N102", ..., and operations are executed in that order. The safety judgment unit 205 judges whether or not the safety conditions are satisfied for each block, and attaches a safety flag to the control data of the block that satisfies the safety conditions. Here, it is assumed that the block "N105" satisfies the safety conditions.

[0030] For example, when a communication error occurs during reception of the control data of block "N106", the machine tool 9 operates according to the control data of block "N103" at this time. Since the safety flag is not attached to this block "N103", the result is determined as "NO" in step S12, and since the reception of the control data of the next block "N104" is completed and stored in the buffer 201 in the next step S21, the result is determined as "YES", and the process returns to step S6, and the machine tool 9 operates according to the control data of the next block "N104" in step S7. If the communication is not restored to normal at this time, the process returns to step S1 via steps S8-S9, and steps S6-S9 are executed via steps S11, S12, and S21, and the operation of the machine tool 9 continues according to the control data of the next block "N105". Furthermore, the machine tool body 36 operates according to the control data of the block "N105" to which the safety flag is attached via steps S1, S2, S11, and S12, and then stops.

[0031] In this way, when a safety block exists, the operation of the machine tool 9 continues up to the safety block stored in the buffer 201, and stops after the operation of the safety block is completed. This allows the machine tool 9 to be stopped at a safe position without damaging the workpiece or tool, and without interfering with other automated machines 11, 13, etc. When a communication abnormality occurs, operation continues up to the safety block, so that when communication is restored after the communication abnormality, normal operation can be restored, preventing damage to the workpiece or tool and avoiding downtime. Since the operation stops at a block of the NC program, when communication is restored, a return operation is not required, and operation can be resumed directly from the stopped position according to the control data of the next block, thereby minimizing downtime.

[0032] 6(b), we will explain the operation in a situation where none of the blocks "N101"-"N105" of the control data that have been completely received at the time when the communication abnormality occurs meets the safety conditions. When the communication abnormality occurs during the operation according to the control data of the block "N103", the reception of the control data up to the block "N105" is completed and stored in the buffer 201, and since none of these have the safety flag, the loop of steps S1, S2, S11, S12, S21, S6-S9 circulates, and the operation of the block "N105" is followed by the evacuation operation in step S22, and the operation stops at a safe position.

[0033] In this way, when no safety block exists, the operation of the machine tool body continues up to the block stored in buffer 201, and stops after the evacuation operation is completed. This allows the machine tool to be stopped at a safe position. When a communication abnormality occurs, operation continues up to the block remaining in buffer 201, and then the evacuation operation is performed. Therefore, when communication is restored during the period in which the control data remaining in buffer 201 is being transmitted to the automated machine tool, normal operation can be restored, and downtime can be avoided.

[0034] According to this embodiment, when a communication abnormality occurs, the operation can be continued as much as possible and the machine tool body can be stopped at a safe position. Even after communication is restored, the operation can be automatically resumed, and even if a communication disturbance occurs, the malfunction can be minimized. In addition, by sharing information on multiple machine tools, automated machines such as robots, and assigning a high-performance numerical control calculation device without updating the hardware of the machine tool, advanced calculations such as synchronous control, prevention of interference between machines, and improvement of operation by machine learning can be easily realized. Even when an abnormality occurs or during maintenance, the machine can be driven as safely as possible without stopping.

[0035] In the above explanation, the operation of the communication monitoring units 2, 4, 6, and 8 attached to the automated machine tools 9, 11, 13, and 15 has been described. However, the functions equipped in each communication monitoring unit (communication abnormality judgment unit, safety judgment unit, communication control unit, connection switching unit) may be implemented in the automated machine tools 9, 11, 13, and 15, and the processing procedure of Figure 3 may be executed by the intermediate processing unit 23 of the machine tool 9.

[0036] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope of the invention and its equivalents described in the claims, as well as in the scope and spirit of the invention. [Explanation of symbols]

[0037] 1, 3, 5...numerical control arithmetic unit, 2, 4, 6, 8...communication monitoring unit, 7...communication line network, 9, 11...machine tool, 13...robot, 15...automatic guided vehicle.

Claims

1. Numerical control compatible automated machines, a numerical control arithmetic unit connected to the automated machine via a communication line and configured to calculate control data for operating the automated machine; A communication monitoring unit is provided between the numerical control arithmetic unit and the automated machine. The communication monitoring unit includes: an internal buffer for storing the control data from the numerical control arithmetic unit in units of blocks; a communication control unit that sequentially transmits the stored control data in units of blocks to the automated machine; a safety determination unit that determines whether each of the blocks satisfies a predetermined safety condition; a communication abnormality determination unit that determines whether a communication state of the communication line is normal or abnormal; When an abnormality is determined in the communication state of the communication line, the communication control unit: a numerical control arithmetic system which, when the block being executed at the time the abnormality determination is made satisfies the safety condition, stops transmission of the control data to the automated machine to have the automated machine execute the operation of the block and then stop the automated machine, when the block being executed at the time the abnormality determination is made does not satisfy the safety condition, causes the automated machine to execute the operation of the block, and, when a block that satisfies the safety condition appears while sequentially executing the blocks stored in the internal buffer, stops transmission of the control data to the automated machine after transmitting the block that satisfies the safety condition in order to have the automated machine execute the operation of the block that satisfies the safety condition and then stop the automated machine, and switches the numerical control arithmetic system as a source of the control data to another numerical control arithmetic system, and, when no block that satisfies the safety condition appears while sequentially executing the blocks stored in the internal buffer, transmits evacuation control data to the automated machine after transmitting all the blocks in order to move the automated machine to a predetermined evacuation position and then stop the automated machine.

2. 2. The numerical control calculation system according to claim 1, wherein the automated machine is a machine tool, a robot, or an automated guided vehicle (AGV).

3. 2. The numerical control arithmetic system according to claim 1, wherein the transfer of the control data to the automated machine is resumed upon completion of the switching of the connection to the other numerical control arithmetic device.

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