Patent Publication Number: US-2021173382-A1

Title: Control device and recording medium encoded with program

Description:
This application is based on and claims the benefit of priority from Japanese Patent Application 2019-222314, filed on 9 Dec. 2019, the content of which is incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present disclosure relates to a control device and a recording medium encoded with a program. 
     Related Art 
     Conventionally, a machine tool has been known which machines a workpiece placed on a table using a tool. In the machine tool, the tool and the table are moved to machine a workpiece into a predetermined shape. The control device controls the movement of the machine tool. 
     Shortening of the cycle time for machining is important for the machine tool. Therefore, the speed of the movement of the table, exchange of tools, etc. is often set so as to be the fastest. For example, a tool holder which shortens the tool exchange time has been proposed (for example, refer to Patent Document 1). 
     Patent Document 1: Japanese. Unexamined Utility Model Application, Publication No. S62-153029 
     SUMMARY OF THE INVENTION 
     In relation to shortening of the cycle time, for example, it is useful to move the table in advance to the next machining position while exchanging tools. After exchanging tools, it is thereby possible to start machining of the workpiece immediately. On the other hand, rapid traversing the table at maximum speed may lead to heat generation of the motor. Since time is required to naturally cool the heat generation of the motor, it is desirable to avoid the heat generation. Therefore, it is suitable if possible to optimize the movement speed of the table during tool exchange. 
     A first aspect of the present disclosure relates to a control device which controls a machine tool so as to move a table during exchange of tools, the control device including: a movement distance acquisition unit which acquires a movement distance of the table during tool exchange; a movement time calculation unit which calculates a fastest movement time from an acquired movement distance, and a speed at which the table is caused to move fastest; a tool exchange time calculation unit which calculates a tool exchange time; a comparison unit which compares the tool exchange time calculated and the fastest movement time calculated; and a speed changing unit which changes the movement speed of the table, in a case of the fastest movement time being shorter than the tool exchange time, so that the movement time of the table becomes longer than the fastest movement time. 
     In addition, a second aspect of the present invention relates to a recording medium encoded with a program for causing a computer to function as a control device which controls a machine tool so as to move a table during exchange of tools, the program causing the computer to function as: a movement distance acquisition unit which acquires a movement distance of the table during tool exchange; a movement time calculation unit which calculates a fastest movement time from an acquired movement distance, and a speed at which causing the table to move fastest; a tool exchange time calculation unit which calculates a tool exchange time; a comparison unit which compares the tool exchange time calculated and the fastest movement time calculated; and a speed changing unit which changes the movement speed of the table, in a case of the fastest movement time being shorter than the tool exchange time, so that the movement time of the table becomes longer than the fastest movement time. 
     According to the present disclosure, it is possible to provide a control device and a recording medium encoded with a program which can optimize the movement speed of a table during tool exchange. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic configuration diagram showing a machining system including a control device according to a first embodiment of the present disclosure; 
         FIG. 2  is a block diagram showing the configuration of the control device of the first embodiment; 
         FIG. 3  is a flowchart showing the flow of operations of the control device of the first embodiment; 
         FIG. 4  is a conceptual diagram showing an example of changing the speed by the control device of the first embodiment; and 
         FIG. 5  is a conceptual diagram showing an example of changing the speed by a control device of a second embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Hereinafter, a control device  1  and program according to each embodiment of the present disclosure will be explained with reference to  FIGS. 1 to 5 . First, before explaining the control device  1  in each embodiment, a summary of the relationship between the exchange of a tool  21  of a machine tool  2  controlled by the control device  1  and movement of a table  22  will be explained. 
     The machine tool  2  is included in a machining system  100 , as shown in  FIG. 1 . The machine tool  2  machines a work piece  24 , while exchanging a plurality of tools  21  retained in a magazine  23 , according to the machining contents. In the exchange of the tools  21 , the time is required to mount the tool  21  retained in the magazine  23  to the spindle  25 , after removing the tool  21  mounted to a spindle  25  (hereinafter referred to as tool exchange time). It is possible to shorten the cycle time (machining time), by moving the table  22  (workpiece  24 ) in advance to the next machining position, during the tool exchange time. For example, in the case of moving the table  22 , it is possible to position the table  22  at the destination in the shortest time, by moving each axis at the maximum speed according to the destination. On the other hand, in the case of the tool exchange time being longer than the shortest time, it is possible to suppress heat generation of a motor (not shown) running the spindle, by changing (adjusting) the movement time of the table  22 . The control device  1  and program according to the following embodiment suppress heat generation of a motor, i.e. achieve optimization of the movement speed of the table  22 , by changing the movement speed of the table  22 . 
     First Embodiment 
     Next, the control device  1  and program according co the first embodiment of the present disclosure will be explained with reference to  FIGS. 1 to 4 . The control device  1  is included in a machining system  100 , as shown in  FIG. 1 . The control device  1  is configured to be able to control a machine tool  2 . In the present embodiment, the control device  1  controls the machine tool  2  so as to move the table  22  during exchange of the tools  21 . The control device  1  includes: a machining program storage unit  11 , a detection unit  12 , a movement distance acquisition unit  13 , a movement time calculation unit  14 , a tool exchange time calculation unit  15 , a comparison unit  16 , a speed changing unit  17 , and a control execution unit  18 , as shown in  FIG. 2 . 
     The machining program storage unit  11  is a secondary storage medium such as a hard dish, for example. The machining program storage unit  11  stores a machining program indicating the movements of the tool  21  and table  22 . In addition, the machining program storage unit  11  stores various setting information such as the movement speed of the axes of the table  22 , or retaining positions of tools  21  in the magazine  23 . 
     The detection unit  12 , for example, is realized by a CPU operation. The detection unit  12  detects commands for conducting tool exchange and movement of the table  22  simultaneously, in relation to a machining program stored in the machining program storage unit  11 . The detection unit  12  causes the movement distance acquisition unit  13  and tool exchange time calculation unit  15  to move according to the detection. 
     The movement distance acquisition unit  13  is realized by the CPU operation, for example. The movement distance acquisition unit  13  acquires the movement distance of the table  22  during tool exchange. The movement distance acquisition unit  13  acquires the movement distances of the X axis and Y axis from the start to the end of tool exchange, from the machining program storage unit  11 , for example. In addition, the movement distance acquisition unit  13  acquires the highest speed of each of the X axis and Y axis, from the machining program storage unit  11 . 
     The movement time calculation unit  14  is realized by a CPU operation, for example. The movement time calculation unit  14  calculates the fastest movement time, from the acquired movement distance, and the speed at which the table  22  is caused to move fastest. The movement time calculation unit  14 , for example, calculates the fastest movement time, based on the movement distance, and the highest speed of each axis. 
     The tool exchange time calculation unit  15  is realized by a CPU operation, for example. The tool exchange time calculation unit  15  calculates the exchange time of the tools  21 . The tool exchange time calculation unit  15 , for example, acquires the retaining position of the tools  21  in the magazine  23 , from the machining program as setting information. The tool exchange time calculation unit  15  calculates the tool exchange time based on the retaining position of the acquired tool  21 . 
     The comparison unit  16  is realized by a CPU operation, for example. The comparison unit  16  compares the calculated tool exchange time with the calculated fastest movement time. More specifically, the comparison unit  16  compares whether the calculated tool exchange time is longer than the calculated fastest movement time. 
     The speed chancing unit  17  is realized by a CPU operation, for example. In the case of the fastest movement time being shorter than the tool exchange time, the speed changing unit  17  changes the movement speed of the table  22 , so that the movement time of the table  22  is longer than the fastest movement time, with the tool exchange time being made as the limit. The speed changing unit  17 , for example, recalculates the rapid-traverse time constant of the X axis and Y axis, and changes the movement time during tool exchange to be longer. The speed changing unit  17 , for example, changes the movement speed of the table  22 , so that the movement time becomes 95% relative to the tool exchange time. 
     The control execution unit  18  is realized by a CPU operation, for example. The control execution unit  18  causes the table  22  to actually move at the changed movement speed of the table  22 . In addition, the control execution unit  18  causes the tool  21  to be exchanged in accordance with the machining program. 
     Next, operation of the control device  1  of the present embodiment will be explained using the flowchart of  FIG. 3 . First, the detection unit  12  detects a command for simultaneously conducting tool exchange and movement of the table  22 , in relation to the machining program stored in the machining program storage unit  11  (Step S 1 ). The detection unit  12  causes the movement distance acquisition unit  13  and tool exchange time calculation unit  15  to operate, when detecting the corresponding command. 
     Next, the movement distance acquisition unit  13  acquires the movement distance of the table  22  (Step S 2 ). The movement distance acquisition unit  13 , for example, acquires the movement distance of the table  22  included in the detected machining program. 
     Next, the movement time calculation unit  14  calculates the movement time from the movement distance of the table  22  and the fastest movement speed of each axis (Step S 3 ). Next, the tool exchange time calculation unit  15  calculates the exchange time of the tool  21  (Step S 4 ). 
     Next, the comparison unit  16  compares the tool exchange time with the movement time of the table  22  (Step S 5 ). In the case of the tool exchange time being longer than the movement time of the table  22  (Step S 5 : YES), the processing advances to Step S 6 . On the other hand, in the case of the tool exchange time being shorter than the movement time of the table  22  (Step S 5 : NO), the processing advances to Step S 7 . 
     In Step S 6 , the speed changing unit  17  changes the movement speed of the table  22 . The speed changing unit  17 , for example, changes so as to make the movement speed of the table  22  longer, with the tool exchange time being made as a limit. 
     Next, in Step S 7 , the control execution unit  18  actually executes the exchange of tools  21  and the movement of the table  22 . The processing according to the present flow thereby ends. 
     Next, the program of the present disclosure will be explained. Each configuration included in the control device  1  can be realized by way of hardware, software or a combination thereof. Herein, being realized by software means being realized by a computer reading and executing a program. 
     The program can be stored using various types of non-transitory computer readable media, and supplied to the computer. Non-transitory computer readable medium includes various types of tangible storage media. Examples of non-transitory computer readable media include magnetic recording media (e.g., flexible disk, magnetic tape, hard disk drive), magneto-optical recording media (e.g., magneto-optical disk), CD-ROM (Read Only Memory), CD-R, CD-R/W and semiconductor memory (e.g., mask ROM, PROM (programmable ROM), EPROM (Erasable PROM), flash ROM, RAM (random access memory)). In addition, the display program may be supplied to the computer by way of various types of transitory computer readable media. Examples of transitory computer readable media include electrical signals, optical signals and electromagnetic waves. Transitory computer readable media can supply programs to the computer via wired communication paths such as electric wires and optical fiber, or wireless communication paths. 
     Next, Examples of the present embodiment will be explained with reference to  FIG. 4 . As shown in  FIG. 4 , the movement start time of the table  22  and the tool exchange start time are denoted as t 0 . Then, the exchange end time of the tool  21  is denoted as t 1 . In the case of moving the table  22  the fastest, the table  22  moves up to the target position, during the time from t 0  to t 2  (movement time TB 1 ) (one-dot dashed line M 1  in  FIG. 4 ). In contrast, in the case of delaying the movement speed of the table  22  according to the tool exchange time, the table  22  moves to the target position (two-dot dashed line M 2  in  FIG. 4 ), during the time from t 0  to t 3  (movement time TB 2 ). Herein, time t 3  is later than time t 2 , and earlier than t 1 . In the exchange end time of the tool  21  (time t 1 ), it is thereby possible to move the table  22  to the target position, and possible to slow the movement speed of the axis. It should be noted that it is ideal for the movement of the table  22  to be completed at the exchange end time t 1  of the tool  21 . Therefore, the time t 3  at which the movement of the table  22  is completed is preferably set at a time close to time t 1 , while not being the same time as time t 1 . Compared to the case of being the same time, it is thereby possible to give a margin in the machining of the workpiece  24 . 
     According to the control device  1  and program in the first embodiment above, the following effects are obtained. (1) The control device  1  which controls the machine tool  2  so as to make the table  22  move during exchange of the tools  21 , includes: the movement distance acquisition unit  13  which acquires the movement distance of the table  22  during tool exchange; the movement time calculation unit  14  which calculates the fastest movement time from the acquired movement distance and the speed at which the table  22  is caused to move the fastest; the tool exchange tool calculation unit  15  which calculates the exchange time of the tool  21 ; the comparison unit  16  which compares the calculated tool exchange time with the calculated fastest movement time; and the speed changing unit  17  which changes the movement speed of the table  22 , in a case of the fastest movement time being shorter than the tool exchange time, so that the movement time of the table  22  becomes longer than the fastest movement time, with the tool exchange time being made as a limit. In addition, a program causes a computer to function as the control device  1  which controls the machine tool so as to move the table  22  during exchange of the tools  21 , the computer being caused to function as: the movement distance acquisition unit  13  which acquires the movement distance of the table  22  during tool exchange; the movement time calculation unit  14  which calculates the fastest movement time from the acquired movement distance and the speed at which the table  22  is caused to move the fastest; the tool exchange tool calculation unit  15  which calculates the exchange time of the tool  21 ; the comparison unit  16  which compares the calculated tool exchange time with the calculated fastest movement time; and the speed changing unit  17  which changes the movement speed of the table  22 , in a case of the fastest movement time being shorter than the tool exchange time, so that the movement time of the table  22  becomes longer than the fastest movement time, with the tool exchange time being made as a limit. It is thereby possible to change the movement speed of the table  22  during the tool exchange. Therefore, it is possible to suppress heat generation of the axis moving the table  22 . In addition, it is possible to suppress electrical consumption, and suppress operating costs. In other words, it is possible to optimize the movement speed of the table  22 . 
     Second Embodiment 
     Next, a control device  1  and program according to a second embodiment of the present disclosure will be explained with reference to  FIG. 5 . Upon explanation of the second embodiment, the same reference symbols are assigned to constituent elements which are identical to the aforementioned embodiment, and explanations thereof are omitted or abbreviated. The control device  1  and program according to The second embodiment are made taking consideration of the movement time of a brake mechanism (clamping, unclamping operation) of the axis, in addition to the control device  1  and program in the first embodiment. 
     More specifically, the control device  1  and program according to the second embodiment differ from the first embodiment in that the movement time calculation unit  14  adds the clamping time and unclamping time of the table  22  to the fastest movement time to calculate the actual movement time. In addition, the control device  1  and program according to the second embodiment differ from the first embodiment, in that the speed changing unit  17  changes the movement speed of the table  22  in order to make the actual movement time of the table  22  longer than the fastest movement time, with the tool exchange time being made as a limit, in the case of the actual movement time being shorter than the tool exchange time. 
     Next, Examples of the control device  1  and program according to the second embodiment will be explained with reference to  FIG. 5 . As shown in  FIG. 5 , the movement start time of the table  22  and the tool exchange start time are denoted as t 1 . Then, the exchange end time of the tool  21  is denoted as t 1 . In the case of moving the table  22  at the fastest speed, the table  22  moves up to the target position from time t 0  to time t 7  (movement time TB 1 ) (one-dot dashed line M 3  in  FIG. 5 ). At this time, the actual movement time TB 1  is comprised of the unclamping time TD 2  (end time t 4 ), movement time TC 1  (end time t 6 ), and clamping time TD 1  (end time t 7 ). 
     In contrast, in the case of slowing the movement speed of the table  22  according to the tool exchange time, the table  22  moves to the target position (two-dot dashed line M 4  in  FIG. 5 ) from time t 0  to time t 3  (movement time TB 2 ). At this time, the actual movement time TB 2  is configured by the unclamping time TD 2  (end time t 4 ), movement time TC 2  (end time t 5 ), and clamping time TD 1  (end time t 3 ). Herein, time t 3  is later than time t 7 , and earlier than time t 1 . At the exchange end time of the tool  21  (time t 1 ), it is thereby possible to make the table  22  move to the target position, and slow the movement speed of the axis. 
     According to the control device  1  and program in the second embodiment above, the following effects are obtained. (3) The movement time calculation unit  14  adds the clamping time and unclamping time of the table  22  to the fastest movement time to calculate the actual movement speed. Even if being an axis having a brake mechanism, it is thereby possible to realize a change in speed. Therefore, it is possible to improve the versatility of the control device  1 . 
     (4) The speed changing unit  17 , in the case of the actual movement time being shorter than the tool exchange time, changes the movement speed of the table  22 , so that the actual movement time of the table  22  becomes longer than the fastest movement time, with the tool exchange time being made as a limit. It is thereby possible to improve the versatility of the control device  1 , by changing the actual speed. 
     Although the respective preferred embodiments of the control device and program of the present disclosure have been explained above, the present disclosure is not to be limited to the aforementioned embodiments, and modifications are possible as appropriate. For example, in the above embodiments, the speed changing unit  17  may store the changed movement speed of the table  22  as an item among the various settings in the machining program storage unit  11 . The control execution unit  18  may be configured so as to control movement of the table  22 , by reading a stored item, upon executing a machining program. 
     In addition, in the above embodiments, the speed changing unit  17  is not limited to a change in speed, and may be configured so as to change the acceleration of the axis. In addition, the speed changing unit  17  may be configured so as to change the movement speed of the table  22 , by adopting the time constant of the speed by a sequence decided in advance. 
     In addition, in the above embodiments, the control device  1  is explained as being independent from the machine tool  2 ; however, it is not limited thereto. The control device  1  may be configured integrally with the machine tool  2 . 
     EXPLANATION OF REFERENCE NUMERALS 
     
         
           1  control device 
           2  machine tool 
           13  movement distance acquisition unit 
           14  movement time calculation unit 
           15  tool exchange time calculation unit 
           16  comparison unit 
           17  speed changing unit 
           21  tool 
           22  table