JPH09192974A - Controller and control method for machine tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify control in returning to origin, so as to improve machining precision by arranging a friction force generating member to be brought in contact with a projecting member and for generating friction force or friction torque as a position recognizing signal of the origin of the absolute position of a moving part or near the origin on a fixed part. SOLUTION: A dog 13 is arranged on a moving part 14, and a friction force generating member 11 is arranged on a fixed part 12. Force or torque to act on the moving part 14 in returning to origin is monitored, a part on which driving force, force other than torque or torque to be generated by servo motor 17, namely, friction force or friction torque in the reverse direction to the advancing direction of the moving part 14 to be generated by the contact of the friction generating part 11 with the dog 13 is generated is determined as the origin or the vicinity of the origin, and returning to origin is performed by applying offset to a count value of an incremental method encoder 18 in form of a software.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a machine tool control apparatus and control method, and more particularly to a control apparatus for returning to the origin of a positioning apparatus such as a numerical control apparatus in a machine tool using a servo motor equipped with an incremental encoder. And a control method, it is suitable for simplification of a control device and a control method for origin recognition, and improvement of machining accuracy when using the simplified control device and control method for origin recognition. .

[0002]

2. Description of the Related Art Moving parts (motor shaft, etc.) in machine tools
In the feedback control of speed and position, the accuracy of the position and speed detection is important, and various methods have been put into practical use according to the purpose and application. One of those methods
There is an incremental encoder in the speed / position detection device that applies one of these, and it can handle not only speed signals but also position signals.It is also suitable for digital processing, so it is widely used in various applications. There is.

FIG. 9 is a schematic configuration diagram of a machine tool system equipped with an incremental encoder in which the control device and control method for returning to the origin in the conventional control device and control method for a machine tool are used.

A fixed portion 92 provided with the proximity detection switch 91 and a projection-shaped device 93 called a dog, which operates the proximity detection switch 91 when approaching the proximity detection switch 91, are provided. A movable part 94, a ball screw 96 provided on the servo motor 97 as a pivot,
The nut 95, which is provided in the movable portion 94 and axially supports the ball screw 96 to move the movable portion 94, the incremental encoder 98 for detecting the operation of the servomotor 97, and the detection signal from the incremental encoder 98 A numerical control device (servo amplifier or the like) 90 for controlling the servo motor 97 in response to the numerical control device 90 is provided with an input section to which a signal from the proximity detection switch 91 is input, and an output signal corresponding to the input signal is generated. It is composed of a sequencer 100 for transferring the data to a computer and a wiring 99 for properly connecting the respective parts.

In the machine tool system having the incremental encoder shown in FIG. 9, the incremental encoder 98 detects the operation of the servomotor 97,
With this, the speed and position of the movable portion are recognized and controlled.

Due to the rotational movement of the servo motor 97, the movable portion 94 is moved in the same direction as the axial direction of the ball screw 96, that is,
The encoder 9 moves in the direction of arrow A in FIG.
The speed and the position of the movable portion 94 are recognized by the detection by 8. The numerical controller 90 controls the servomotor 97 in response to the detection signal from the incremental encoder 98.

However, as described above, since the position of the movable portion 94 is recognized by the rotational movement of the servo motor 97 detected by the incremental encoder 98, only the relative position to the initial state can be recognized. The movable portion 9 is detected by the detection signal from the servo motor 97.
When the position control of No. 4 is performed, the movable unit 9 that is the control target
It is necessary to make the incremental encoder 98 recognize the absolute position of 4 in advance.

Therefore, in order to control the position of the movable portion 94 to be controlled, it is necessary to perform an operation called "origin return" before positioning and machining by the machine tool. Returning to the origin means that one point within the range of motion of the movable part 94 to be controlled is defined as the origin, the movable part 94 is appropriately moved by the servomotor 97, and the position defined as this origin is passed through. By making the encoder 98 recognize the absolute position, it is possible to determine and recognize the absolute position based on the recognition of the position of the origin.

Recognition of the origin by returning to the origin is usually called a dog, and a device for activating the proximity detection switch when approaching a predetermined proximity detection switch is provided in the movable part, and the fixed part is provided with the device. Proximity sensing switches are provided and the on / off operation of the proximity sensing switches is electrically detected.

FIG. 10 shows a proximity detection switch of a machine tool system having an incremental encoder in which the control device and control method for returning to the origin in the conventional machine tool control device and control method are used. It is explanatory drawing which represented typically only the movable part in which the fixed part and the dog were arrange | positioned, and has extracted only the said component part in FIG. The proximity sensing switch 101 is arranged on the peripheral portion of the fixed portion 102, and the dog 103 is arranged on the peripheral portion of the movable portion 104.

[0011]

However, as described above, in the control device and control method for returning to the origin in the conventional control device and control method for machine tools, the signal when the dog is recognized by the proximity detection switch or the like is used. However, the following problems have been encountered because of using as a position signal at or near the origin.

That is, outputs from at least (1) dog, (2) proximity detection switch, etc. (3) proximity detection switch, etc. are necessary for implementing the conventional control device and control method for return to origin. A detection device for detecting a signal (the input part of the sequencer), (4) a cable for connecting the proximity detection switch and the like to the detection device, and (5) a detection device and a numerical control device for positioning which are used as necessary. Mediating sequencer, (6) Servo motor, (7) Incremental encoder, (8) Numerical control device, (9)
A device such as a logic circuit that resets the counter of the incremental encoder is included, and its configuration is complicated, and the burden of cost such as equipment cost is large.

The present invention has been made in view of the above problems, and an object thereof is a control device at the time of returning to the origin of a positioning device such as a numerical control device and a control device for a machine tool having an incremental encoder. And a control method, a machine tool that simplifies a control device and a control method for origin recognition, and further improves machining accuracy when using the simplified control device and control method for origin recognition. To provide a control device and a control method thereof.

[0014]

According to a control device for a machine tool of the present invention, a movable part on which an object to be machined is placed,
By contacting the protrusion member arranged on the movable portion with the protrusion member within a predetermined range within the movement range of the movable portion, a friction force or a friction torque as a position recognition signal of the origin of the absolute position of the movable portion or the vicinity of the origin is applied. A servo motor that has a fixed portion on which a frictional force generating member that is generated and a pivot that is axially supported by a movable portion, and that moves the movable portion by rotating the pivot shaft, and a driving force for the operation of the servo motor. Alternatively, an incremental encoder that detects torque or speed and friction force or friction torque, and generates a detection signal, and position information and speed information about the movable part based on the detection signal are generated, and the driving force of the servo motor operation or A numerical control device for controlling torque or speed is provided, and conventionally, a proximity detection switch or the like for detecting the approach of the projection member is provided. A frictional force generating member that generates a frictional force or frictional torque in the direction opposite to the moving direction of the movable part by contacting the protruding member is arranged at a location, and the frictional force or friction torque is the origin for returning to the origin. Since it is used for position recognition, a detection device (input of a sequencer) that detects an output signal from a component that has been conventionally required, that is, (1) proximity detection switch or the like, or (2) proximity detection switch or the like. Section), (3) a cable for connecting the proximity detection switch and the like to the detection device, (4) a sequencer that mediates between the detection device and the numerical control device for positioning, which are used as necessary, (5) an incremental encoder A device such as a logic circuit for resetting the counter is unnecessary, the configuration is simplified, and the cost such as equipment cost can be significantly reduced.

The movable part on which the object to be machined is placed, the projection member arranged on the movable part, and the projection member in contact with the projection member within a predetermined range within the range of motion of the movable part, are the origin of the absolute position of the movable part or The movable part has a fixed part on which a frictional force generating member that generates a frictional force or a frictional torque as a position recognition signal near the origin is arranged, and a pivot shaft supported by the movable part. The servo motor that makes the motor move, the incremental encoder that detects the driving force or torque or speed of the servo motor operation and the friction force or friction torque, and generates the detection signal, and the position information about the movable part based on the detection signal. And generate speed information,
Numerical control device that controls the driving force, torque, or speed of servo motor operation, and the origin return after the origin return operation that determines the origin or the position near the origin that serves as the position information reference by detecting the friction force or friction torque. Compensation torque for canceling and compensating for the frictional force or friction torque based on the position information or speed information when passing through a predetermined range of the movable part when performing an operation other than the above operation. Is provided with a friction torque compensator that outputs a compensating torque generation command to generate the friction torque or friction torque generated at or near the origin when moving parts other than the origin return operation are calculated in advance. And a friction torque compensator that controls the servo motor to generate a driving force or torque that offsets and compensates for this. So equipped, it is possible to prevent the disturbance of the velocity waveform and the force or torque waveform in advance, as a result, processing unevenness of the workpiece due to the disturbance of the velocity waveform and the force or torque waveform is prevented from occurring in,
It is possible to realize a numerically controlled machine tool with high accuracy of position control and speed control and high processing accuracy.

Since the form of the contact portion between the protrusion member and the frictional force generating member is assumed to be a point or a line segment orthogonal to the moving direction of the movable portion, the velocity waveform due to the contact between the frictional force generating member and the protrusion member is obtained. It is possible to easily control the driving force or torque required to keep the speed constant by removing the disturbance of the velocity, and as a result, the velocity waveform, force or torque waveform recognized by the numerical control device can be changed with time. It can be homogenized in sections along the axis into a simple pattern, which results in easier recognition and control by the numerical controller.

Since the projection member has a contact portion with the frictional force generating member in a unique form and generates a frictional force or a frictional torque in a unique pattern, the protrusional member is determined from the unique pattern of the frictional force or the frictional torque. The contact between the protrusion member and the frictional force generating member can be reliably identified.

In the case where a plurality of projecting members are arranged to generate frictional force or frictional torque as position recognition signals at a plurality of different reference positions including the origin or the vicinity of the origin, respectively, Since the shape of the contact portion of the protruding member is different from the shape of the contact portion of the other protruding member, each protruding member produces a unique pattern of frictional force or friction torque by contact with the frictional force generating member. It is possible to easily identify which of the protrusion members is in contact with the frictional force generating member by generating the frictional force.

Of the position information, the absolute position information is assumed to be the information generated on the basis of the signal for recognizing the position of the origin or the vicinity of the origin. Therefore, after the operation of returning to the origin, the absolute position of the movable part is always accurate. Can be recognized.

According to the method for controlling a machine tool of the present invention, the protrusion member provided on the movable portion on which the workpiece is placed and the frictional force provided on the fixed portion forming a pair with the movable portion. A first process of bringing the generating member into contact with the movable member within a predetermined range within the motion range of the movable member to generate a frictional force or a frictional torque, and a driving force of the operation of the servo motor that moves the movable member by the incremental encoder. Alternatively, the second process of detecting the torque or the speed and the friction force or the friction torque, and determining the position where the friction force or the friction torque occurs as the origin of the absolute position of the movable part or the vicinity of the origin, and the servo detected by the incremental encoder Based on the driving force or torque or speed of motor operation and the relative position of the movable part, and the determined origin or a position near the origin, the movable part A third process for generating position information and speed information for controlling the driving force or torque of the operation of the servomotor, or a speed, and detecting the approach of the protruding member, which has been conventionally used. Instead of a proximity detection switch, etc., a friction force generating member that generates a friction force or friction torque in the direction opposite to the moving direction of the movable part by contacting the protruding member is used, and the friction force or friction torque is used to return to the origin. Since it was decided to use it for recognition of the origin position when performing, the components required for the conventional method, namely, (1) proximity sensing switch, etc.
(2) A detection device (an input unit of a sequencer) that detects an output signal from the proximity detection switch, (3) A cable for connecting the proximity detection switch and the detection device, and (4) Used as necessary. A sequencer that mediates between the detection device and the numerical control device for positioning, and (5) a logic circuit that resets the counter of the incremental encoder is not required, so that the configuration is simplified and the cost such as equipment cost is greatly increased. Can be reduced.

A protrusion member provided on the movable portion on which the object to be machined is placed and a frictional force generating member provided on the fixed portion forming a pair with the movable portion are provided in a predetermined range within the movement range of the movable portion. By the first process of contacting in a range and generating frictional force or frictional torque, and the incremental encoder,
The drive force or torque or speed of the operation of the servo motor that makes the movable part movable is detected, and the frictional force or frictional torque is detected, and the position where the frictional force or friction torque is generated is defined as the origin of the absolute position of the movable part or near the origin. Position information about the movable part based on the second process, the driving force or torque or speed of the operation of the servo motor detected by the incremental encoder, and the relative position of the movable part, and the determined origin or a position near the origin. And the speed information is generated, the driving force or torque or speed of the operation of the servo motor is controlled, and the origin or the position near the origin that serves as the position information reference is determined by detecting the friction force or friction torque. When the movable part passes a specified range when performing operations other than the home return operation after the operation, And a third step of generating a compensation torque for compensating for the frictional force or the frictional torque so as to set the moving speed of the movable part to a predetermined value, based on the report or speed information. Since the frictional force or frictional torque generated at or near the origin is calculated in advance during the operation of the movable part of, and the compensating torque for canceling and compensating for this is generated, the disturbance of the speed waveform and force or torque waveform As a result, it is possible to prevent machining unevenness of the object to be machined due to the disturbance of the speed waveform and the force or torque waveform, and the accuracy of position control and speed control is high. It is possible to realize highly accurate control of the machine tool.

Since the contact between the protrusion member and the frictional force generating member in the first step is made as a contact point or a line segment orthogonal to the moving direction of the movable part, the frictional force generating member is contacted. The disturbance of the velocity waveform due to the contact between the protrusion and the protrusion member can be removed, and the control of the driving force or torque required to keep the velocity constant can be facilitated, and as a result, the recognized velocity waveform, The force or torque waveform can be made uniform for each part along the time axis to form a simple pattern, which can be more easily recognized and controlled.

The first step is a step including a step of generating a frictional force or a frictional torque having a peculiar pattern by the projection member having a contact portion with the frictional force generating member in a peculiar form. Therefore, the contact between the protrusion member and the frictional force generating member can be reliably identified from the unique pattern of the frictional force or the frictional torque.

In the case where a plurality of projecting members are arranged as a unit for generating a frictional force or a frictional torque as position recognition signals at a plurality of different reference positions including the origin or the vicinity of the origin, respectively, The unique pattern of the friction force or torque generated by the protruding member is
Since it is assumed that the pattern is different from the peculiar pattern of the frictional force or the frictional torque generated by the other protrusion member, it is easy to identify which protrusion member is in contact with the frictional force generation member. be able to.

Since the absolute position information of the position information is the information generated based on the position recognizing signal at or near the origin, the absolute position of the movable part is always accurately measured after the origin return operation. Can be recognized.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a control device and a control method for a machine tool according to the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram of a machine tool system equipped with an incremental encoder for implementing a first embodiment of a control device and a control method at the time of returning to origin in a control device and method for a machine tool according to the present invention. It is a block diagram.

The feature of the first embodiment of the control device and control method at the time of returning to origin according to the present invention is that the dog and A frictional force generating member that generates a frictional force or a frictional torque in the direction opposite to the moving direction of the moving part by contact, such as rubber, is provided, and the frictional force or friction torque is set to the origin position when the origin is returned. It is used for recognition.

A movable portion 14 provided with a dog 13 and a fixed portion 12 provided with a frictional force generating member 11 for generating a frictional force in a direction opposite to the traveling direction of the movable portion 14 by coming into contact with the dog 13. And a ball screw 16 provided as a pivot for the servo motor 17 and the movable part 14 and
4, a nut 15 for axially supporting the ball screw 16 to make the motor 4 movable, an incremental encoder 18 for detecting the operation of the servo motor 17, and a servo motor 17 according to a detection signal from the incremental encoder 18.
A numerical control device (for example, a control device such as a servo amplifier) 10 for controlling the controller, a numerical control device 10 and a servo motor 17
And an interconnection 19 for connecting to the incremental encoder 18.

As described above, in the configuration of the first embodiment of the control device and control method for returning to the original point according to the present invention, the dog 13 disposed on the movable portion 14 and the conventional dog 13 are provided. A frictional force generating member 11 that generates a frictional force in a direction opposite to the traveling direction of the movable portion 14 by contacting the dog 13 is provided at a position on the fixed portion 12 where a proximity detection switch or the like for detecting the approach is arranged. Arrange. As the material of the frictional force generating member 11, an appropriate material can be used according to the case, and examples thereof include a material such as rubber.

As described above, by disposing the dog 13 in the movable portion 14 and the frictional force generating member 11 in the fixed portion 12, respectively, the movable portion 14 can be moved to the origin or near the origin during the operation of returning to the origin. Frictional force generating member 1 when moving
1 and the dog 13 come into contact with each other, and a frictional force or a frictional torque in a direction opposite to the traveling direction of the movable portion 14 is generated.

By the way, in order to control the position and speed of the movable portion 14, the numerical controller 10 for controlling the servo motor 17 actually controls the driving force or torque generated by the servo motor 17. Therefore, unless there is an external factor that exerts an external force on the movable portion 14, the servo motor 17
The driving force or torque generated by the moving part 14 is known in advance, and the numerical control device 10 determines the speed and acceleration of the moving part 14 and the moving part 14 from the position of the moving part 14 with respect to time.
It is possible to obtain the force, torque, etc. acting on the.

Therefore, the force or torque acting on the movable portion 14 at the time of returning to the origin is monitored, and the force or torque other than the driving force or torque generated by the servo motor 17 which is grasped in advance, that is, the frictional force generating member 11 is detected. Dog 1
The point where the frictional force or friction torque in the direction opposite to the moving direction of the movable portion 14 due to the contact with the contact point 3 is defined as the origin or the vicinity of the origin, and the count value of the incremental encoder 18 is offset by software to return to the origin. Is possible.

As described above, according to the configuration of the first embodiment of the control device and control method at the time of returning to the original point according to the present invention, by contacting the dog 13, the direction opposite to the traveling direction of the movable portion 14 is reached. By using the frictional force generating member 11 that generates the frictional force of (1), detection for detecting an output signal from a component that has been conventionally required, that is, (1) proximity sensing switch, etc. (2) proximity sensing switch, etc. Device (input part of sequencer), (3) cable for connection between proximity detection switch and the like and detection device, (4) sequencer for mediating detection device and positioning numerical control device used as necessary, 5) A device such as a logic circuit for resetting the counter of the incremental encoder is not required, the configuration is simplified, and the cost such as equipment cost can be significantly reduced.

In the above-described control device or control method at the time of returning to the origin using the frictional force or the frictional torque generated by the dog and the frictional force generating member as the detection signal near the origin or near the origin, the dog and the frictional force are generated. Velocity waveforms, force or torque waveforms of various shapes are generated depending on the contact form caused by the shape of the member.

FIG. 2 is a diagram showing a dog and a friction provided on a movable part and a fixed part in the first embodiment of the control device and the control method at the time of returning to the origin in the control device and the control method of the machine tool according to the present invention. It is explanatory drawing which represented the shape of the force generation member typically.

The fixed part 22 and the movable part 24 include the movable part 2
4, a frictional force generation member 21 and a dog 23 having trapezoidal cross-sectional shapes in a direction perpendicular to the facing surfaces of the fixed portion 22 and the movable portion 24 are arranged in parallel with the movement direction of the movable member 24. The shape of a surface parallel to the facing surfaces of the fixed portion 22 and the movable portion 24 of the frictional force generating member 21 and the dog 23 is usually circular or quadrangular.

FIG. 3 is a graph showing a velocity waveform, a force or a torque waveform when the frictional force generating member 21 and the dog 23 having a trapezoidal sectional shape as shown in FIG. 2 are arranged.

The graph of the force or torque waveform is shown at time t1.
At time t2, the contact between the frictional force generating member 21 and the dog 23 is started, and the contact area becomes maximum at time t2.
3 shows that the contact between the frictional force generating member 21 and the dog 23 is completed.

In the graph of the velocity waveform, the disturbance of the waveform appears due to the delay of the velocity control with respect to the increase of the contact area immediately after the contact between the frictional force generating member 21 and the dog 23 in the vicinity of the symbol 31, but the symbol 32 In the vicinity of the part, the waveform returns to a flat waveform by constant speed control. But,
In the vicinity of the reference numeral 33, the waveform is disturbed due to the delay of the speed control with respect to the reduction of the contact area between the frictional force generating member 21 and the dog 23.

As described above, in the control device or control method at the time of returning to the origin using the frictional force or the frictional torque generated by the dog and the frictional force generating member as the detection signal at the origin or near the origin, the shapes of the dog and the frictional force generating member are used. Depending on the contact form caused by, the velocity waveform, force or torque waveform is non-uniform along the time axis, and unnecessary disturbance of the velocity waveform occurs.

The second control device and control method for returning to the origin in the control device and control method for a machine tool according to the present invention
In the embodiment of the present invention, the non-uniform and unnecessary disturbance of the velocity waveform is eliminated, and the generated velocity waveform, force or torque waveform has a simple shape, and the improved implementation is performed to simplify the recognition by the numerical control device. It is a form.

The feature of the second embodiment of the control device and control method at the time of returning to the original point according to the present invention is to improve the shapes of the dog and the frictional force generating member so as to be used as a detection signal at or near the original point. A velocity waveform recognized by the numerical controller by removing unnecessary disturbance of the velocity waveform caused by the frictional force or friction torque generated by the dog and the frictional force generating member,
The force or torque waveform is made uniform for each part along the time axis to form a simple pattern.

FIG. 4 is a diagram showing a dog and a friction disposed on a movable part and a fixed part in the second embodiment of the control device and the control method at the time of returning to the origin in the control device and the control method of the machine tool according to the present invention. It is explanatory drawing which represented the shape of the force generation member typically.

The fixed portion 42 has a hemispherical frictional force generating member 4
1 is provided, and a dog 43 having a trapezoidal sectional shape in a direction parallel to the moving direction of the movable portion 44 and perpendicular to the facing surfaces of the fixed portion 42 and the movable portion 44 is provided in the movable portion 44. . In addition, the frictional force generation member 41 disposed on the fixed portion 42
May be semi-cylindrical in cross section in a direction parallel to the moving direction of the movable portion 44 and perpendicular to the facing surfaces of the fixed portion 42 and the movable portion 44. The shape of the surface parallel to the facing surfaces of the fixed portion 42 and the movable portion 44 of the dog 43 is usually circular or quadrangular.

That is, in the second embodiment of the control device and control method at the time of origin return according to the present invention, the velocity waveform, force or torque waveform recognized by the numerical control device is made uniform for each part along the time axis. In order to form a simple pattern, the contact portion between the frictional force generating member 41 and the dog 43 arranged on the fixed portion 42 and the movable portion 44 is changed to a point or a movable portion 44.
The line segment is orthogonal to the movement direction of the.

FIG. 5 is a velocity waveform, force or torque when a frictional force generating member and dog of a predetermined shape are arranged in the second embodiment of the control device and control method for returning to origin according to the present invention. It is a graph which shows a waveform.

The change in speed at the portion indicated by reference numeral 51 indicates a state in which the speed of the movable portion is accelerated up to the speed at the time of returning to the origin, and the waveform of force or torque at the portion indicated by reference numeral 55 is generated due to this acceleration. Indicates the force or torque exerted. The reference numeral 56 indicates a state in which the force or torque is stable after being stabilized at the speed at the time of returning to the origin.

At the portion 52, the waveform slightly changes due to the start of contact between the frictional force generating member and the dog. The reference numeral 57 indicates the force in the reference numeral 56 in order to remove the disturbance of the velocity waveform due to the contact between the frictional force generating member and the dog under the control of the numerical controller detecting the change in the reference numeral 52 and keep the velocity constant. Or, a force or torque larger than the torque is generated.

In the second embodiment of the control device and control method at the time of returning to the original point according to the present invention, the contact portion between the dog and the frictional force generating member provided in the fixed portion and the movable portion is set to a point or a movable portion. Since the line segment is orthogonal to the movement direction of the part, the force or torque necessary to remove the disturbance of the velocity waveform due to the contact between the friction force generating member and the dog and to keep the velocity constant is indicated by reference numeral 57. It is constant during the contact period as shown. As a result, the speed is kept constant as indicated by the reference numeral 53.

At the reference numeral 54, the waveform slightly changes due to the end of contact between the frictional force generating member and the dog. The reference numeral 58 indicates the force in the reference numeral 56 so as to remove the disturbance of the velocity waveform due to the contact between the frictional force generating member and the dog under the control of the numerical controller which has detected the change in the portion 54 and to keep the velocity constant. Alternatively, the same force or torque as the torque is generated.

As described above, according to the second embodiment of the control device and control method for returning to the original point according to the present invention, the frictional force generating member and the dog disposed in the fixed portion and the movable portion are connected to each other. Since the contact part is a point or a line segment orthogonal to the moving direction of the movable part, the force necessary to maintain the speed constant by eliminating the disturbance of the velocity waveform due to the contact between the friction force generating member and the dog. The torque can be controlled easily, and as a result, the velocity waveform, the force or the torque waveform recognized by the numerical control device can be made uniform for each part along the time axis,
It can be a simple pattern. The simple pattern of the velocity waveform, force or torque waveform makes the numerical controller easier to recognize and control.

FIG. 6 is a perspective view showing another example of the shape of the frictional force generating member applicable to the second embodiment of the control device and control method for returning to the original point according to the present invention.

As shown in FIG. 6, a prismatic frictional force generating member such as a triangular prism has a contact portion between the frictional force generating member and the dog.
By using a line segment that is orthogonal to the moving direction of the movable portion, it is possible to similarly obtain the effect of the configuration of the second embodiment. The frictional force generating member may have any other shape as long as the contacting portion between the frictional force generating member and the dog can be a point or a line segment orthogonal to the moving direction of the movable portion.

In the second embodiment of the control device and control method for returning to the original point according to the present invention as described above, the contact portion between the dog and the frictional force generating member disposed in the fixed portion and the movable portion, By forming a point or a line segment orthogonal to the moving direction of the movable part, a simple patterned velocity waveform, force or torque waveform can be obtained, but when a plurality of dogs are arranged, the velocity waveform, Since the force or torque waveform is simply patterned, it is difficult to identify each dog.

Third Embodiment of Control Device and Control Method at Return to Origin in Machine Tool Control Device and Control Method According to the Present Invention
The embodiment of 1 is an embodiment improved so that each dog can be easily identified by giving a unique pattern to the shape of each dog when a plurality of dogs are arranged.

FIG. 7 is a schematic diagram showing the shape of the dog to be arranged on the movable part in the third embodiment of the control device and control method for returning to the origin in the control device and control method for a machine tool according to the present invention. FIG.

FIG. 7 shows a dog 70 to be arranged on the movable part.
2 shows the end face shape. The dog 70 is composed of a first member 71, a second member 72, and a third member 73. That is, the first member 71, the second member 72, and the third member 73 form one dog 70. When arranging multiple dogs, the velocity waveforms obtained when each dog contacts the frictional force generating member by making the arrangement pattern of the members that make up each dog different from each other. , The force or torque waveform is unique, and it is possible to easily identify which dog is currently in contact with the dog from the velocity waveform, the force or torque waveform.

Each member constituting one dog is divided into several parts as shown in FIG. 7, or is composed of a single member, but contact points are separated into a plurality of parts. In such a case, it is possible that the lengths of the contact portions formed at the dogs formed of one member are different from each other. Further, the identification of a plurality of dogs according to the third embodiment of the control device and the control method at the time of returning to the origin in the control device and control method for a machine tool according to the present invention can be realized at an extremely low cost.

In each of the embodiments described above, by detecting the frictional force or the frictional torque generated by the contact between the dog disposed in the movable portion and the frictional force generating member disposed in the fixed portion, This enables origin return and absolute position control.

However, in the numerically controlled machine tool or the like to which each of the embodiments according to the present invention is applied, the velocity waveform and the force or the force waveform are generated every time the frictional force generating member and the dog come into contact with each other during machining of the workpiece. A certain degree of turbulence in the torque waveform is unavoidable, and as a result, there may be an inconvenience that uneven machining appears on the workpiece.

The fourth embodiment of the machine tool control apparatus and control method according to the present invention described below is simplified by applying each of the above-described control apparatus and control method for origin return. The present invention relates to a machine tool control device and control method that are improved to improve machining accuracy when using a control device and control method for returning to the origin.
That is, in a control device and a control method for a machine tool using the control device and control method at the time of returning to the origin, which recognizes the origin or a position near the origin from the friction force or the friction torque generated by the contact between the friction force generating member and the dog. The disturbance of the velocity waveform and the force or torque waveform caused by the friction force or the friction torque generated by the contact between the friction force generating member and the dog in the operation other than the origin return operation is canceled and compensated.

Machine tool control device and control method using the control device and control method at the time of returning to the origin for recognizing the origin or the position near the origin from the friction force or friction torque generated by the contact between the friction force generating member and the dog. At once,
After the origin return operation is performed to determine the origin or the position near the origin, it is possible to recognize the absolute position of the moving part, and the friction force generating member and dog are The position where the frictional force or frictional torque is generated by the contact is grasped and recognized in advance by the numerical controller. Therefore, when moving parts other than the home-return operation, calculate the frictional force or frictional torque generated at or near the origin in advance, and use the servo motor to generate a driving force or torque that offsets and compensates for this. By performing the control for giving the command, it is possible to prevent the disturbance of the velocity waveform and the force or torque waveform.

FIG. 8 is a control block diagram in the fourth embodiment of the machine tool control apparatus and control method according to the present invention.

The torque command from the numerical controller is the node 8
1 is input to the current controller 82, and the current command generated by the current controller 82 is given to the servo motor 83 in response to the input. The servo motor 83 operates based on this current command, and the position control and speed control of the movable portion are performed.

The feature of the fourth embodiment of the machine tool control apparatus and control method according to the present invention is that the position control signal based on the operation of the servo motor 83 is fed back to the friction torque compensator 84 at this time. That is.
Since the friction torque compensator 84 recognizes in advance at which position the friction torque for the origin return operation is generated, the movable part is moved to the origin or a position near the origin based on the position control signal fed back. When the vehicle moves, a compensation torque generation command for canceling the friction torque for the origin return operation and generating a compensation torque for compensating is output.

This compensating torque generation command is added to the normal torque command from the numerical controller via the node 81 and input to the current controller 82. In response to this, the current controller 82 gives a current command including a compensation torque generation command to the servo motor 83, and the servo motor 83
A torque is generated by adding a torque for canceling the friction torque for the home-return operation to the torque required for the normal operation.

Therefore, according to the fourth embodiment of the machine tool control apparatus and control method of the present invention, the speed in operations other than the home-return operation due to the friction force or friction torque for the home-return operation. Disturbances in the waveform and force or torque waveform can be canceled and compensated. As a result, it is possible to prevent machining unevenness of the workpiece due to the disturbance of the velocity waveform and the force or torque waveform, and to realize a numerically controlled machine tool with high position control and speed control accuracy and high processing accuracy. be able to.

[0069]

As described above, according to the machine tool control apparatus of the present invention, the protrusion member is brought into contact with the location where the proximity detection switch or the like for detecting the approach of the protrusion member is conventionally arranged. By arranging a frictional force generating member that generates a frictional force or a frictional torque in the direction opposite to the moving direction of the movable part, the frictional force or the frictional torque is used to recognize the origin position when performing origin return. Therefore, the components that have been conventionally required, that is, (1) proximity detection switch, etc., (2) detection device for detecting the output signal from the proximity detection switch (sequencer input section), (3) proximity Cable for connection between sensing switch etc. and detection device,
(4) A sequencer that mediates between the detection device and the positioning numerical control device that are used as necessary, (5) a logic circuit that resets the counter of the incremental encoder, and other devices are not required, and the configuration is simplified. It is possible to significantly reduce costs such as equipment costs.

When a movable part other than the home-return operation is operated, a frictional force or a frictional torque generated at or near the origin is calculated in advance, and a servomotor is generated so as to generate a driving force or torque that cancels the frictional force or frictional torque. Since it is equipped with a friction torque compensator that gives a command to, it is possible to prevent disturbance of the velocity waveform and force or torque waveform, and as a result, the disturbance of the velocity waveform and force or torque waveform is caused. It is possible to realize a numerically controlled machine tool in which machining unevenness of the machining target is prevented, the position control and speed control are highly accurate, and the machining accuracy is high.

Since the form of the contact portion between the protrusion member and the frictional force generating member is assumed to be a point or a line segment orthogonal to the moving direction of the movable portion, the velocity waveform due to the contact between the frictional force generating member and the protrusion member is obtained. It is possible to easily control the driving force or torque required to keep the speed constant by removing the disturbance of the velocity, and as a result, the velocity waveform, force or torque waveform recognized by the numerical control device can be changed with time. It can be homogenized in sections along the axis into a simple pattern, which results in easier recognition and control by the numerical controller.

The projection member has a contact portion with the frictional force generating member in a unique form and generates a frictional force or a frictional torque in a unique pattern. The contact between the protrusion member and the frictional force generating member can be reliably identified.

When a plurality of constituent units are arranged so that the projection members respectively generate frictional force or frictional torque as position recognition signals at a plurality of different reference positions including the origin or near the origin, Since the shape of the contact portion of the protruding member is different from the shape of the contact portion of the other protruding member, each protruding member produces a unique pattern of frictional force or friction torque by contact with the frictional force generating member. It is possible to easily identify which of the protrusion members is in contact with the frictional force generating member by generating the frictional force.

Since the absolute position information of the position information is the information generated on the basis of the signal for recognizing the position of the origin or the vicinity of the origin, the absolute position of the movable part is always accurately measured after the origin return operation. Can be recognized.

According to the machine tool control method of the present invention, the moving direction of the movable part can be changed by contacting the protrusion member instead of the proximity detection switch or the like which is used conventionally for detecting the approach of the protrusion member. Since a frictional force generating member that generates a frictional force or frictional torque in the opposite direction was used and that frictional force or friction torque was used to recognize the origin position when performing origin return, it is necessary for the conventional method. Components, that is, (1) proximity sensing switch, etc.
(2) A detection device (an input unit of a sequencer) that detects an output signal from the proximity detection switch, (3) A cable for connecting the proximity detection switch and the detection device, and (4) Used as necessary. A sequencer that mediates between the detection device and the numerical control device for positioning, and (5) a logic circuit that resets the counter of the incremental encoder is not required, so that the configuration is simplified and the cost such as equipment cost is greatly increased. Can be reduced.

Since the frictional force or the frictional torque generated at or near the origin is calculated in advance during the operation of the movable part other than the return-to-origin operation and the compensating torque for canceling and compensating for this is generated, the velocity waveform And it is possible to prevent disturbance of the force or torque waveform,
As a result, it is possible to prevent machining irregularity of the machining target due to the disturbance of the velocity waveform and the force or torque waveform, and realize the control of the machine tool with high accuracy of position control and speed control and high processing accuracy. be able to.

Since the contact between the protrusion member and the frictional force generating member in the first step is a contact made with a point or a line segment orthogonal to the moving direction of the movable part as the contacting part, the frictional force generating member is contacted. The disturbance of the velocity waveform due to the contact between the protrusion and the protrusion member can be removed, and the control of the driving force or torque required to keep the velocity constant can be facilitated, and as a result, the recognized velocity waveform, The force or torque waveform can be made uniform for each part along the time axis to form a simple pattern, which can be more easily recognized and controlled.

The first step is a step including a step of generating a frictional force or a frictional torque having a peculiar pattern by the projection member having a contact portion with the frictional force generating member in a peculiar form. Therefore, the contact between the protrusion member and the frictional force generating member can be reliably identified from the unique pattern of the frictional force or the frictional torque.

In the case where a plurality of constituent units are provided as the projection members for respectively generating the frictional force or the frictional torque as the position recognizing signals at the plurality of different reference positions including the origin or the vicinity of the origin, The unique pattern of the friction force or torque generated by the protruding member is
Since it is assumed that the pattern is different from the peculiar pattern of the frictional force or the frictional torque generated by the other protrusion member, it is easy to identify which protrusion member is in contact with the frictional force generation member. be able to.

Since the absolute position information of the position information is the information generated based on the position recognizing signal at or near the origin, the absolute position of the movable part is always accurately measured after the origin return operation. Can be recognized.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a machine tool system including an incremental encoder that implements a first embodiment of a control device and a control method when returning to a home position in a machine tool control device and control method according to the present invention.

FIG. 2 is a diagram showing a dog and a frictional force generating member provided in a movable part and a fixed part in the first embodiment of the control device and the control method at the time of returning to the origin in the control device and the control method for the machine tool according to the invention. Explanatory drawing which represented the shape of FIG.

FIG. 3 is a graph showing a velocity waveform, a force waveform, or a torque waveform when a frictional force generating member having a trapezoidal cross section and a dog are arranged.

FIG. 4 is a diagram showing a dog and a frictional force generating member provided in a movable part and a fixed part in a second embodiment of the control device and the control method at the time of returning to the origin in the control device and the control method for a machine tool according to the present invention. Explanatory drawing which represented the shape of FIG.

FIG. 5 shows a velocity waveform, a force or a torque waveform in the case where a frictional force generating member and a dog having a predetermined shape are arranged in the second embodiment of the control device and control method for returning to origin according to the present invention. Graph.

FIG. 6 is a perspective view showing another example of the shape of the frictional force generation member applicable to the second embodiment of the control device and control method for returning to the original point according to the present invention.

FIG. 7 is a schematic view showing the shape of a dog to be arranged on a movable part in the third embodiment of the control device and the control method at the time of returning to the origin in the control device and the control method of the machine tool according to the present invention. The explanatory diagram.

FIG. 8 is a control block diagram according to a fourth embodiment of a machine tool control apparatus and control method according to the present invention.

FIG. 9 is a schematic configuration diagram of a machine tool system including an incremental encoder in which the control device and the control method for returning to the origin in the conventional machine tool control device and control method are used.

FIG. 10 is a perspective view showing a conventional machine tool control device and method, wherein a home position control device and control method are used in the machine tool system including an incremental encoder. Explanatory drawing which represented typically only the movable part with which the dog was arrange | positioned.

[Explanation of reference numerals] 10, 90 Numerical control device 11, 21, 41 Friction force generating member 12, 22, 42, 92 Fixed part 13, 23, 43, 70, 93 Dog 14, 24, 44, 94 Movable part 15, 95 Nuts 16, 96 Ball Screws 17, 97 Servo Motors 18, 98 Incremental Encoders 19, 99 Wirings 71, 72, 73 Dog Components 91 Proximity Sensing Switches 100 Sequencer A Moving Direction of Moving Parts

Claims (12)

[Claims] 1. A movable part on which an object to be machined is placed, a protrusion member arranged on the movable part, and a movable part which comes into contact with the protrusion member within a predetermined range within a movement range of the movable part. Of the absolute position of the origin or near the origin of the fixed portion having a frictional force generating member for generating a frictional force or a frictional torque as a position recognition signal, and the movable portion has a pivot shaft, A servo motor that makes the movable part movable by rotating a pivot, and an incremental encoder that detects the driving force or torque or speed of the operation of the servo motor and the friction force or friction torque, and generates a detection signal, A numerical value that generates position information and speed information about the movable part based on the detection signal and controls the driving force or torque or speed of the operation of the servo motor. Control device for a machine tool, characterized in that a control device. 2. A movable part on which an object to be machined is placed, a protrusion member disposed on the movable part, and a movable part which comes into contact with the protrusion member within a predetermined range within a movement range of the movable part. Of the absolute position of the origin or near the origin of the fixed portion having a frictional force generating member for generating a frictional force or a frictional torque as a position recognition signal, and the movable portion has a pivot shaft, A servo motor that makes the movable part movable by rotating a pivot, and an incremental encoder that detects the driving force or torque or speed of the operation of the servo motor and the friction force or friction torque, and generates a detection signal, A numerical value that generates position information and speed information about the movable part based on the detection signal and controls the driving force or torque or speed of the operation of the servo motor. Control device and the movable part in the case of performing an operation other than the operation of returning to the origin after the operation of returning to the origin to determine the origin or the position near the origin which becomes the reference of the position information by detecting the frictional force or the friction torque. When passing through the predetermined range, a compensating torque generation command for compensating by canceling the frictional force or frictional torque based on the position information or speed information to generate a compensating torque that makes the moving speed of the movable portion a predetermined value is generated. A machine tool control device comprising: a friction torque compensator for outputting. 3. The machine tool control device according to claim 1, wherein the form of the contact portion between the protrusion member and the frictional force generating member is orthogonal to the point or the moving direction of the movable portion. A machine tool control device characterized by a line segment. 4. The machine tool control device according to claim 1, wherein the protrusion member has a contact portion with the frictional force generating member in a unique form, and has a unique pattern. A machine tool control device characterized by generating a frictional force or a frictional torque. 5. The machine tool control device according to claim 4, wherein the protrusion member respectively applies a friction force or a friction torque as a position recognition signal at a plurality of different reference positions including the origin or the vicinity of the origin. When a plurality of structural units are arranged to generate, the form of the contact portion of one protrusion member is different from the form of the contact portion of another protrusion member. Machine tool control device. 6. The machine tool control device according to claim 1, wherein the absolute position information among the position information is information generated based on a signal for position recognition near the origin or near the origin. A machine tool control device characterized by the following. 7. A motion of the movable part, comprising: a protrusion member arranged on the movable part on which a workpiece is placed; and a frictional force generating member arranged on a fixed part which makes a pair with the movable part. A first process of generating a frictional force or a frictional torque by bringing them into contact with each other within a predetermined range within the range, and the driving force or torque or speed of the operation of the servomotor that moves the movable part by the incremental encoder and the frictional force. Alternatively, the friction torque is detected, and the position where the friction force or the friction torque is generated is defined as the origin of the absolute position of the movable part or the vicinity of the origin.
And the relative position of the driving force or torque or speed of the operation of the servomotor detected by the incremental encoder and the movable portion, and the position of the determined origin or the vicinity of the origin of the movable portion, And a third step of controlling the driving force or torque or speed of the operation of the servo motor by generating position information and speed information. 8. A motion of the movable part, comprising a protrusion member arranged on a movable part on which a workpiece is placed, and a frictional force generating member arranged on a fixed part forming a pair with the movable part. A first process of generating a frictional force or a frictional torque by bringing them into contact with each other within a predetermined range within the range, and the driving force or torque or speed of the operation of the servomotor that moves the movable part by the incremental encoder and the frictional force. Alternatively, the friction torque is detected, and the position where the friction force or the friction torque is generated is defined as the origin of the absolute position of the movable part or the vicinity of the origin.
And the relative position of the driving force or torque or speed of the operation of the servomotor detected by the incremental encoder and the movable portion, and the position of the determined origin or the vicinity of the origin of the movable portion, Generates position information and speed information, controls the driving force or torque or speed of the operation of the servomotor, and determines the origin or a position near the origin, which is the reference for the position information, by detecting the friction force or friction torque. In the case of performing an operation other than the operation of returning to the origin after the operation of returning to the origin, the moving speed of the moving portion is set to a predetermined value based on the position information or the speed information when the moving portion passes through the predetermined range. And a third step of generating a compensation torque for canceling and compensating for the friction force or friction torque. Characteristic machine tool control method. 9. The method of controlling a machine tool according to claim 7, wherein the contact between the protrusion member and the frictional force generating member in the first step is a point or a movement of the movable portion. A method for controlling a machine tool, characterized in that the contact is made with a line segment orthogonal to the direction as a contact portion. 10. The method of controlling a machine tool according to claim 7, wherein in the first step, the protrusion member has a contact portion with the friction force generating member in a unique form. By the above, the method of controlling a machine tool is a step including a step of generating the frictional force or frictional torque having a unique pattern. 11. The method of controlling a machine tool according to claim 10, wherein the protrusion member respectively applies a friction force or a friction torque as a position recognition signal at a plurality of different reference positions including the origin or the vicinity of the origin. When a plurality of structural units are arranged to generate, the unique pattern of the friction force or friction torque generated by one protrusion member is the friction force or friction torque generated by another protrusion member. The machine tool controller is different from the above-mentioned unique pattern. 12. The method of controlling a machine tool according to claim 7, wherein the absolute position information of the position information is information generated based on a signal for position recognition near the origin or near the origin. A method for controlling a machine tool characterized by being present.