JP2002137148A - Tool state detector and atc automatic return system using the detector, and display system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an origin return system for a change arm for safely and easily changing of a tool. SOLUTION: A detecting body F to detect the clamp state of a tool and sensors A and B are set. A return to an origin of the change arm is automatically or manually effected according to its degree of a risk based on information thereof. Further, a tool clamp state is rapidly analyzed and processed by the occurrence of abnormality from the sensors and return of the change arm during the occurrence of abnormality is facilitated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a home return device for a tool-changing change arm of a machine tool, which can be returned in an optimum return sequence in a short time without imposing a burden on a machine or an operator. It relates to an ATC origin return system.

[0002]

2. Description of the Related Art In the field of machining parts by machine tools,
Although the processing steps have become complicated, shortening of the cycle time is strictly required. In order to machine a workpiece with a machine tool, it is necessary to change various machining tools for each machining process.
This tool change time is a very large loss time. Machine tool manufacturers are aiming to make products that reduce tool replacement time in order to reduce this loss time.However, problems that occur at the time of tool replacement under the conditions of high-speed and frequent tool replacement are approached. It is virtually impossible to zero out, and operators must deal with these troubles. However, since the recovery method differs depending on the timing of occurrence of a trouble, it is difficult for inexperienced workers to cope with the situation. With regard to recovery work, the basic policy is to return the ATC to the origin, and if the worker performs improper recovery, the ATC unit and tools may be damaged, but damage to these important parts is fatal to machine tools. In addition, there are many workers who stop production due to erroneous restoration work. Since inexperienced workers cannot cope with this trouble, they have to wait until a skilled person such as a maintenance person arrives, and the time loss during that time is also a big problem. Also, in a factory where there is no skilled person such as a maintenance person, the support of the machine tool maker is required, but much time is spent in exchanging inquiries etc. The machine tool cannot operate for a long time.

FIG. 12 shows a general machine tool 100.
The command to the machine tool is issued by the operator operating the operation panel 4, but not only the operation but also various information of the machine tool can be obtained from this control panel. It is performed by the operation panel.

With respect to the tool, a tool 6 mounted on the main shaft 5 and a tool 6 ′ at a standby position of the magazine 3 are located opposite to each other, and this is caused by the rotation of the change arm 2 by the ATC (automatic tool change) unit 1. , Both tools are exchanged. The magazine 3 is rotatable and can be any one of a plurality of pots arranged in the magazine.
The individual can be moved to the exchange position, but by changing the pot by rotating the magazine and exchanging the tool by ATC, it becomes possible to attach any one of various tools to the spindle.

FIG. 13 shows the details of the change arm 2.
The tools 6, 6 'are held at both ends of the change arm 2,
The claw 7 prevents the turning tool from dropping off, and makes a turning motion based on the rotation center 8.

FIG. 14 shows the movement of the change arm when the tool is replaced. The change arm 2 normally waits in the horizontal direction so as not to interfere with the main shaft or the like. When the tool exchange starts, the change arm rotates 90 degrees as shown in FIG. 14A, and the tool 6 housed in the magazine exchange pot 9 at both ends and the tool 6 'attached to the main shaft 5 are moved. grab. Next, the clamp of the tool mounted on the spindle is released (unclamped), and as shown in FIG.
The cylinder 10 of the change arm is extended, and the tool is withdrawn from the magazine pot and the main shaft. Next, FIG.
As shown in (c), when the change arm is rotated by 180 degrees and the cylinder of the change arm is returned to the original length, the tool is returned to the magazine exchange pot and the main spindle with each tool being exchanged, and The mounted tool is clamped. Finally, release the tool, rotate the change arm 90 degrees so that the change arm does not interfere with the main shaft, return the change arm to the original standby position, and complete the tool exchange.

FIG. 15 shows a state in which the tool 6 is mounted on the main shaft 5. When the tool is unclamped at the start of the ATC operation, when the tool is unclamped, the unclamping cylinder 17 is pushed out, so that the draw bar 18 is pushed in while being opposed to the flat spring 13, the collet is pushed out, and the collet releases the pull bolt, and the tool is taken out. Becomes possible. At the end of the ATC operation, the tool 6 is firmly and accurately attached to the main shaft by the protrusion of the pull stud bolt 11 at the end being gripped by the collet 12 and being pulled by the spring 13 as it is.
At this time, a dock 14 and a proximity switch 15 are provided to check whether the tool is properly clamped. The proximity switch is mounted at a fixed location, but the dock moves relatively the same as the drawbar or collet, so the collet position can be indirectly determined by examining the positional relationship between the dock and the proximity switch. It is possible to roughly check the mounting state of.

In the tool exchange process, the operation and timing of the clamp / unclamp of the change arm and the tool and the timing thereof are very important.
It is shown in FIG. A pull stud bolt 11 is added to the end of the tool 6 mounted on the main shaft, and the pull stud bolt is pulled by the collet 12 so that the tool can be firmly integrated with the main shaft. Drawbar 18
The drawbar is always pulled by the spring, and the tool is pulled together with the collet at the tip of the drawbar. Since the inner diameter of the collet increases when it is extruded and decreases when it retracts, the tool can be easily attached and detached. When the collet is pushed out, hydraulic pressure is applied to the hydraulic hose for unclamping 34 and the cylinder is pushed to push out the drawbar and the collet. Conversely, when clamping the tool, the hydraulic hose for clamping 3
Hydraulic pressure is applied to 5, the cylinder is pushed back, and the tool is fixed by the restoring force of the spring. The clamp / unclamp check is performed by the proximity switch 15 and the dock 14, but only a simple operation check such as whether the cylinder is in the unclamped state or in other states.

FIG. 16 is an enlarged view of the vicinity of the proximity switch. If the positional relationship is between the proximity switch 15 and the solid line portion of the dock 14, an ON signal is sent to the control portion of the machine tool via the signal line 16. Conversely, if the positional relationship is between the proximity switch 15 and the broken line portion of the dock 14, an OFF signal is sent to the control portion of the machine tool via the signal line 16. Depending on the type of the proximity switch, there are various variations in how the ON / OFF information is output, and an appropriate proximity switch is used depending on the situation.

As described above, in the prior art, the AT
The ATC portion, as typified by the automatic home return of C, has not been made sufficiently intelligent, and the specific ideas and requirements for it have been scarce.

[0011]

SUMMARY OF THE INVENTION The present invention has been developed in order to improve the problem associated with the above-mentioned conventional home return of the tool change arm. An object of the present invention is to provide an ATC automatic return system for safely and easily performing a home return of a tool changing change arm.

[0012]

According to a first aspect of the present invention, there is provided a tool status detector comprising: a detector provided on an operating body for controlling a tool clamp; and a plurality of sensors for fixing the position of the detector on a fixed member. Then, the clamp state of the spindle is determined stepwise based on the combination of the detection information.

According to a second aspect of the present invention, there is provided a tool status detector.
, Wherein one object to be detected installed on the outer periphery of a tool unclamping piston serving as an operating body is detected by two sensors, and the tool clamp state can be detected in four stages.

According to a third aspect of the present invention, there is provided a tool status detector.
In one of the embodiments, three or more sensors detect one detection object installed on the outer periphery of a tool unclamping piston serving as an operating body, and a tool clamping state can be detected in four stages.

According to a fourth aspect of the present invention, there is provided a tool status detector according to the first aspect.
In the above, one object to be detected, which is installed on the outer periphery of a tool unclamping piston serving as an operating body, is detected by one sensor, so that the tool clamping state can be detected in a stepwise manner.

According to a fifth aspect of the present invention, the ATC automatic return system analyzes and processes by software processing based on the position information from the tool status detector, and automatically selects and executes an optimal home return path. It is characterized by.

According to a sixth aspect of the present invention, in the fourth aspect, in a state where the change arm is stopped during the tool change, the current position of the change arm and what operation path is used to return the change arm.
It is characterized in that the change arm can be returned to the origin manually or automatically by performing analysis and processing by software and displaying the result on a monitor in a status display or a guide display.

[0018]

According to the first aspect of the present invention, the determination is made based on a combination of the shape of the detection body provided on the operating body which moves up and down to clamp the tool and a plurality of sensors provided on the surrounding fixed member. Thus, by detecting the position of the operating body in stages, it is possible to consistently check from the start to the end of the operation. Further, even when the moving distance of the operating body is short, it can be detected by a combination of the shape of the detecting body and the sensor.

According to the second aspect of the present invention, the collet for gripping the tool is integrated with the draw bar, so that the position of the collet can be indirectly known even if the collet is not close to the tool. Therefore, the object to be detected is attached to the outer periphery of the tool unclamping piston, which is an operating body, and this is detected by two independent sensors, and the timing of signal generation sent from each sensor and the combination judgment of sensor information are determined. In addition, the clamp state of the tool can be detected in four stages, and it can be consistently determined whether the tool is normal or abnormal.

According to the third aspect of the present invention, by using three or more sensors, it is possible to detect the position in more stages and to increase the signal generation timing information of each sensor. The state can be determined at a higher altitude.

According to the fourth aspect of the present invention, the use of one sensor capable of generating position information in multiple stages in an analog manner makes it possible to perform detailed position detection of the operating body. It is also possible to detect a subtle displacement, and to detect an initial state of trouble.

According to a fifth aspect of the present invention, based on the information on the tool clamping status obtained from the first, second, third and fourth aspects, position information from a servo amplifier for driving a change arm is added, and Appropriate ATC origin return is possible by hardware. In other words, trouble occurred during ATC,
When stopped at an arbitrary position, based on the signal of each sensor and the change of the signal and the position information of the change arm, pattern analysis and inference are performed by software to automatically return the origin of the change arm according to the degree of danger. Thus, it is possible to appropriately and automatically select manual origin return accompanied by confirmation of an operator.

According to the sixth aspect of the present invention, the position information of the change arm is added based on the operation of the first, second and third aspects, and the information is subjected to pattern analysis and inference by software. By displaying the tool clamp status on the operation panel of the machine tool,
By observing the objective recognition result of the software, the operator is safely prompted to return to the origin of the change arm regardless of automatic operation or manual operation, and prompt recovery is possible.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described with reference to the drawings with respect to a tool status detector, an ATC automatic return system and a display system using the same. First, a first embodiment of the detector will be described with reference to FIGS.

As shown in FIG. 1, the detectors are the detectors F and 2
It is composed of sensors A and B. Although there is a considerable distance from the tool at the lower end of the main spindle, since it operates integrally via a collet, draw bar, etc., even if the sensor is near the upper end of the main spindle, it is possible to detect a change in the position of the collet holding the main spindle.

FIG. 2 shows an example of the positional relationship between the sensors A and B and the detection object F and the output of sensor information. When the sensor is a general proximity switch, the sensor generates ON information when facing the detection object, and generates OFF information otherwise. FIG. 2A shows a state in which the tool is unclamped and the collet is pushed out by the unclamping cylinder and the tool is detachable. FIG. 2B shows a state in which the hydraulic pressure in the cylinder is released after the tool is clamped. The tool is pulled and held by the restoring force of the spring. FIG. 3C shows a state in which the tool clamp has failed. FIG. 3D shows a state in which preparation for spindle rotation has been completed after tool clamping. By grasping the four phenomena in this way, a consistent tool clamp state is confirmed. Hereinafter, details of each situation are shown in FIGS.
Regarding the shape of the unclamping cylinder 17, there is a case in which the shape of the unclamping cylinder 17 arranged on the outer periphery as shown in the figure is often used due to recent demand for space saving.

FIG. 3 shows an unclamped state, in which the hydraulic pressure for unclamping is supplied to the unclamping cylinder 17, which moves downward in the figure. The draw bar is extruded as it is, and the collet 12 is also extruded with it. When the collet is extruded, the inner diameter of the collet 12 is opened to grasp the pull bolt of the tool 6 and the tool 6 can be detached. When the tool is in the unclamped state and the tool can be attached and detached, both the sensors A and B generate ON signals. By checking this signal, irregular attachment and detachment of the tool is prevented, and the collet 12 and the pull bolt 11 etc. Can be prevented beforehand.

FIG. 4 shows a state in which the tool is inserted from the state shown in FIG. 3 and is normally clamped. Since the hydraulic pressure of the unclamping cylinder 17 is released, the draw bar 18 is pushed back by the restoring force of the spring 13, but when the clamping of the tool is completed in a normal state, the sensor A is turned off.
Since N and the sensor B are OFF, if this signal is not output, it can be known at this point that the tool clamp has failed.

FIG. 5 shows a state in which the hydraulic pressure for clamping is supplied to the unclamping cylinder 17 from the state shown in FIG. 4, and the draw bar 18 and the unclamping cylinder 17 are separated by moving the cylinder upward in FIG. This shows a state where rotation is enabled. When the operation is completed, the sensor A is turned off and the sensor B is turned on.

FIG. 6 shows a state in which the state shown in FIG. As an actual situation, when the tool 6 is dropped or the ATC operation is delayed, the tool 6 is closed in a state where the collet 12 is closed.
Is inserted. In this case, the sensor A is turned off and the sensor B is turned off.

FIG. 7 also shows a state in which clamping of the tool has failed. However, the timing is slightly different from the case shown in FIG. 6, and it is noted that the pull stud bolt 11 is in a state of being half-clamped by the collet 12. Show. In this case, the sensor A is turned on and the sensor B is turned on, and this signal itself is the same as the unclamped state shown in FIG. If it does not change, it is easy to see that it is in a half-grasped state.

As described above, not only the simple detection of the position on the working body, but also the completion signal is obtained in each work step, so that a reliable check can be performed. It is possible to prevent the occurrence of subsequent damage. Such a reliable and accurate check of each state in the tool clamp is an important information source for performing the automatic return of the change arm in the present invention.

The above is the configuration of a typical detector for tool clamping with one detector and two sensors.
Various forms can be taken by devising the detection body or adding the number of sensors, and several embodiments of the detector are shown in FIGS.

FIG. 8 shows an embodiment in which two sensors are arranged for one detection object. 8 (a) to 8 (d) show FIG.
(A) to (d) are functionally equivalent to each other, but by arranging the sensor 15 so as to face the detection body 14 as described above, it is necessary to identify a problem of an installation space and a small moving distance. If not, it is possible to deal with the problem of the location of the identification part and the like.

FIG. 9 shows examples of various detectors. FIG. 9 (a)
Is a third embodiment in which the number of sensors is three or more,
By arranging the sensors three-dimensionally, it is possible to reliably detect even a short distance moving object,
It is also possible to install sensors for each function or purpose. Further, by increasing the number of sensors, it is possible to identify a state change exceeding four stages, and it is possible to supply more detailed information.

FIG. 9 (b) shows the use of a sensor 15 'for generating analog information instead of an ON / OFF type sensor, so that a single sensor can detect the position of the movement detector 14' in multiple stages. Becomes In addition, since a subtle change in position can be grasped, troubles can be detected early depending on the operation method.

FIG. 9C shows an embodiment in which an ON / OFF type sensor and an analog sensor 15A are combined. ON / O with high reliability and reliable operation
FIG. 9B shows a configuration example in which the reliability during operation can be improved by combining an FF-type sensor and an analog-type sensor capable of multi-stage position detection. The above is the description of the detector for detecting the tool clamp state.

Next, an ATC automatic return system for automatically returning the change arm based on the information of the detector will be described. FIGS. 10 and 11 are flowcharts for returning the change arm based on the position information of the change arm, various sensor information, and the like. In FIG. 10, the input / output calculation unit calculates the ATC current position of the change arm 2 based on information from the servo amplifier SA, and calculates the cylinder position and the collet position based on sensor information from the sensors A and B, unclamped cylinder information. Performed by The error processing unit S takes in the input / output operation unit E, the machining program execution status K, and the error history R, and executes the current status determination, pattern recognition, error processing, and risk evaluation. The above-described execution is performed by selecting one of three modes: automatic return to the change arm 2, manual return, and forced termination. Also, FIG. 11 shows that the sensor, AT
The abnormality processing 111 based on the C coordinate, the unclamping cylinder, and various IO information is performed, and the operation is interrupted 112. Here, the risk check 113 is performed, and the risk A, the risk B, and the risk C are ranked. Each of the above danger levels A, B, C
, Status displays 114, 115, and 116 and guide displays 117, 118, and 119 are performed. At risk A,
Perform a forced stop. In the case of the risk B, the manual return display 120, the process manual operation 121, and the confirmation of the completion of the return work 1
22 and operation restart 123 are performed. Also, for the degree of risk C, an automatic return display 124, a normal processing lock 125, and an automatic return execution 126 are performed. Regarding the automatic return of the change arm, besides detection of the tool clamp state, AT
The angle coordinates of the C change arm and the operation information of the unclamping cylinder are also important factors, and it is important to capture these in a complex manner, perform an accurate situation analysis, and select the optimal ATC return procedure. . Each piece of information is converted into a numerical value by an input / output operation, and a situation analysis is performed. The various phenomena of each trouble exist in a pre-patterned and organized state, the above and the status of each related part are used as an information source, a corresponding status is obtained from the patterned status, and according to a pre-registered procedure. Return the ATC origin. In addition,
It is also possible to perform the original return of the change arm automatically by judging the current danger level, selection of automatic return / manual return, and recovery by program operation.

If automatic return is not possible due to the degree of danger, guidance is displayed on the operation version display panel of the machine tool, and work for returning to the home position of the change arm is sequentially performed with manual operation by the operator. Such a guidance display can prompt a worker's manual operation safely and smoothly, and can promptly restore the operation of the machine. Regarding the guidance display, even if the change arm can automatically return to the origin, it is necessary to make it clear to the surrounding workers that it is performing a special operation, and to perform the operation for returning the change arm to the origin. This is an important element in this system in order to prevent the risk of being misunderstood as an abnormal operation.

【The invention's effect】

According to the first aspect of the present invention, the movement amount of the component relating to the tool clamp is recognized stepwise by identifying and determining the shape of the detection object in cooperation with a plurality of sensors for one detection object. can do. This makes it possible to detect an analog intermediate state in the measurement result by using a highly reliable ON / OFF binary sensor. Further, by adopting a layout in which a plurality of sensors are opposed to the detection object, it is possible to detect a smaller moving amount with respect to the size of the sensors. As for this detector and sensor, if it operates in conjunction with the collet, drawbar, etc. related to the tool clamp, it can be easily installed due to its simple structure, and its application range is widely applicable to all machine tools. It is possible. Also, if you use analog sensors such as differential transformers, variable resistors, and ultrasonic rangefinders instead of sensors that return ON / OFF binary values,
It is obvious that the position detection of the moving body in the tool clamp is the same and can be included in the gist of the present invention because multi-stage position detection is possible with one sensor. However, when an analog sensor is used, it is necessary to calibrate for a shift during long-term use, so it is considered to be positioned for special applications. In addition to the simple position detection, by detecting the position corresponding to the completion signal of each operation, the reliability and safety of the ATC system itself can be greatly improved.

According to the second aspect of the present invention, one detector is supplemented with the operating body by two sensors to obtain four-stage position information on the tool clamp, which is the simplest of the present invention. And it is a basic configuration, and it is the configuration that is most easily applied to it. Even with the minimum configuration, it is possible to obtain necessary and sufficient tool clamp information for performing the ATC automatic home position return of the present invention. In addition, a combination of sensors having different properties, for example, an ON / OFF type sensor and an analog sensor, a multi-stage detection exceeding four stages, and a certain detection of a certain reference point, the weakness of the analog sensor of the analog sensor. , The operability of the ATC return system can be improved.

According to a third aspect of the present invention, the second aspect is provided.
This is a configuration that is applied when the four-stage identification by the above configuration is not sufficient, when higher safety is desired, or when it is desired to separate and use the sensor functionally. This is achieved by using a sensor. Since each sensor can be arranged three-dimensionally with respect to the detection object, it is possible to avoid the enlargement of the detection device itself due to the number of sensors, and if each sensor information is linked as the position information of the moving object, it can be moved. It is possible to increase the resolution regarding the position of the body. In addition, the added sensor can be assigned not only to the position information but also to the detection of a specific event, and can be operated to increase the reliability of the ATC system itself.

According to a fourth aspect of the present invention, the multi-stage position of the tool clamp is achieved by supplementing one detecting object with one analog sensor, thereby supplementing the working body with minimum space. Get information

According to the fifth aspect of the present invention, the first aspect is provided.
The angle information of the unclamping cylinder and the ATC change arm, together with the information from the detectors described in 4 to 4 above, are program-processed by the control unit of the machine tool to analyze the state of the tool clamp, tool, and change arm, and perform ATC.
In addition to promptly detecting the occurrence of a trouble, when a trouble is detected, it is possible to independently determine the degree of danger, selection of automatic return / manual return, and recovery by a program operation, according to pattern processing registered in a program in advance.

According to the sixth aspect of the present invention, the result of the ATC-related situation analysis as described above and the return procedure for the ATC-related situation are displayed on the operation panel of the machine tool as a guide, so that the manual return is possible. Allows the worker to perform appropriate return work, and even in the case of automatic return, displays the status on the operation panel to clearly indicate to the surroundings that the worker is returning, Prevent interruption work.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view of a first embodiment using one detection body and two sensors.

FIG. 2 is an operation diagram showing transition states of signals of one detection object and two sensors.

FIG. 3 is a sectional view of a main shaft in an unclamped state when a tool is attached and detached.

FIG. 4 is a cross-sectional view of the main shaft when the tool is in a clamped state.

FIG. 5 is a cross-sectional view of the spindle in a state where preparation for spindle rotation has been completed.

FIG. 6 is a cross-sectional view of the main shaft in a state where ATC has failed.

FIG. 7 is a cross-sectional view of the main shaft in a state where ATC has failed.

FIG. 8 is an operation diagram of the second embodiment using one detection body and two sensors.

FIG. 9 is an operation diagram of the third, fourth, and fifth embodiments using a detection body and a sensor.

FIG. 10 is a block diagram showing a system configuration for performing ATC automatic home position return.

FIG. 11 is a flowchart of ATC automatic home position return processing.

FIG. 12 is an external view of a general machining center.

FIG. 13 is an external view of a general change arm.

FIG. 14 is an operation diagram of a change arm.

FIG. 15 is a cross-sectional view showing an example of installation of a conventional sensor for checking a tool clamp.

FIG. 16 is an external view of a conventional detector and sensor.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ATC (automatic tool change) unit 2 Change arm 3 Magazine 4 Operation panel 5 Main shaft 6, 6 'Tool 7 Claw 8 Rotation center 9 Magazine pot 10 Cylinder 11 Pull stud bolt 12 Collet 13 Sara spring 14 Dock 15 Proximity switch 16 Signal line 17 Unclamp cylinder 18 Drawbar 32 Contact surface between unclamping cylinder and drawbar 33 Analog sensor 34 Hydraulic supply hose for unclamping 35 Hydraulic supply hose for clamping 100 Machine tools A, B, 15, 15A Sensors F, 14, 14 'Detector SA Servo amplifier E Input / output operation unit K Machining program execution status S Error processing unit R Error history

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Junki Hara 4888 Takatsuka-cho, Hamamatsu-shi, Oka F-term in Enshu Co., Ltd. (reference) 3C002 HH06 3C029 EE05 3C032 FF04

Claims (6)

[Claims] 1. An apparatus provided with an operating body for controlling a tool clamp.
A tool status detector characterized by detecting one detecting object and a plurality of sensors fixing the position of the detecting object on a fixed member, and judging a clamping state of the spindle in a stepwise manner based on a combination of the detected information. 2. The apparatus according to claim 1, wherein one object to be detected installed on the outer periphery of the tool unclamping piston serving as an operating body is detected by two sensors, and the tool clamp state can be detected in a stepwise manner. A tool status detector. 3. An apparatus according to claim 1, wherein one or more detection objects disposed on the outer periphery of the tool unclamping piston serving as an operating body are detected by three or more sensors, and the tool clamping state can be detected stepwise. A tool status detector, comprising: 4. The apparatus according to claim 1, wherein one object to be detected installed on the outer periphery of the tool unclamping piston serving as an operating body is detected by one sensor, and the tool clamping state can be detected stepwise. A tool status detector. 5. An ATC automatic return system characterized by analyzing and processing by software processing based on position information from the tool status detector, and automatically selecting and executing an optimal origin return path. . 6. The software according to claim 5, wherein in a state where the tool is stopped during the tool change, the current position of the change arm and an operation path for returning the change arm are analyzed by software.
A display system characterized in that the change arm can be returned to the origin manually or automatically by processing and displaying the result on a monitor in a status display or a guide display.