JPH1080831A - Positioning device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a positioning device which corrects a positioning error produced by distorsion caused by a load applied on a ball screw mechanism to carry out positioning with an excellent accuracy. SOLUTION: A first nut 5 which mounts a table 3 to a ball screw 2 and a second nut 6 which is coupled with the table 3 through a guide 9 are engaged with each other by threading, the relative distance between the second nut 6 and the first nut 5 is detected by a relative distance detection sensor 7 attached to the second nut 6, and any change of the position of the end part of the ball screw is detected by a position detection sensor 8. When distorsion is produced in a ball screw mechanism by a load applied by a work 12 placed on the table 3, a movement lag is produced for the first nut 5 to produce a positioning error. However, when the positioning command data in a control part 10 is corrected by the detected values of the relative position detection sensor 7 and the position detection sensor 8, the error produced by distorsion of the mechanism is corrected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positioning device using a ball screw mechanism, and more particularly to a positioning device capable of correcting a positioning error when a mechanical distortion occurs due to a load.

[0002]

2. Description of the Related Art FIG. 2 is a front view showing the configuration of a conventional positioning device using a ball screw mechanism. In FIG. 2, a positioning device 20 detects the position of a ball screw 22 that is rotationally driven by a motor 21, a nut 23 screwed to the ball screw 22, a table 24 fixed on the nut 23, and the nut 23. A sensor 25;
The control unit 26 controls the rotation of the motor 21 by feedback control based on the detection output of the sensor 25.

In the above configuration, when the ball screw 22 is rotated by the rotation of the motor 21, the nut 23 screwed to the ball screw 22 moves linearly along the ball screw 22. Since the moving distance of the nut 23 with respect to the rotation speed of the ball screw 22 is known, if the rotation speed of the motor 21 is controlled by the control unit 26, the table 2 fixed on the nut 23
4 can be positioned at a predetermined position. However, since a positioning error occurs due to the influence of the moment of inertia and friction of the ball screw 22, the position of the nut 23 is determined by correcting the error and positioning the nut 23 with high accuracy.
, And the detected value is input to the control unit 26, and the rotation of the motor 21 is controlled by correcting the positioning command data. Since the work 28 to be positioned is placed at a predetermined position on the table 24, the work 28 can be positioned at a predetermined position by positioning the table 24.

[0004]

In the above conventional construction, a work 28 is placed on a table 24,
When the motor 21 is rotated with a load applied to the motor 4, the ball screw 22 and the nut 23 or the support bearing 27 of the ball screw 22 are distorted due to the motor output, causing a delay in the movement of the table 24 with respect to the motor output. There was a problem that required time. In addition, the sensor 25
In order to detect the entire stroke of the nut 23, the size of the sensor 25 is increased, and the cost is increased.

[0005] The present invention was conceived to solve the problems of the conventional configuration, and regardless of the rigidity of the ball screw mechanism,
It is another object of the present invention to provide a positioning device that can accurately perform positioning without increasing costs.

[0006]

According to a first aspect of the present invention, a table mounted on a nut screwed to a ball screw driven and rotated by a motor is positioned at a predetermined position by controlling the rotation of the motor. In the positioning device, a first nut mounted with the table and screwed to the ball screw, a second nut screwed to the ball screw at a predetermined distance from the first nut, a second nut and the first nut A relative distance detection sensor that detects a change in relative distance to the nut, and a control unit that corrects positioning command data based on a detection value of the relative distance detection sensor and controls rotation of the motor. Features.

According to the configuration of the first invention, the first nut is affected by the load from the table, causing a movement delay, whereas the second nut is not affected by the load from the table. Therefore, by detecting the movement delay amount of the first nut with respect to the second nut as a relative distance and correcting the positioning command data based on the detected value, it is possible to perform control in which the position of the table that is delayed due to the load is corrected.

According to a second aspect of the present invention, there is provided a positioning device for positioning a table mounted on a nut screwed to a ball screw driven by a motor at a predetermined position by controlling the rotation of the motor. A nut mounted on the table and screwed into the ball screw;
A position detection sensor that detects a change in the axial position of the ball screw; and a control unit that corrects positioning command data based on a detection value of the position detection sensor and controls rotation of the motor. And

According to the configuration of the second aspect of the present invention, the axial position of the ball screw changes due to the distortion generated in the ball screw and its bearing due to the load applied to the table, causing an error in the table position. When the change in the axial position of the ball screw is detected and the positioning command data is corrected based on the detected value, control can be performed to correct the table position that is delayed due to the load.

Further, a third invention of the present application relates to a positioning device for positioning a table mounted on a nut screwed into a ball screw driven by a motor at a predetermined position by controlling the rotation of the motor. A first nut mounted on the table and screwed into the ball screw; a second nut screwed into the ball screw at a processing distance from the first nut; and a relative position between the second nut and the first nut. A relative distance detection sensor that detects a change in distance, a position detection sensor that detects a change in the axial position of the ball screw, and corrects positioning command data based on detection values of the relative distance detection sensor and the position detection sensor. A control unit for controlling rotation of the motor.

According to the configuration of the third aspect, the first nut is affected by the load from the table and causes a movement delay, whereas the second nut is not affected by the load from the table. The amount of delay in movement of the first nut with respect to the second nut is detected as a relative distance, and furthermore, the axial position of the ball screw changes due to the distortion generated in the ball screw and its bearing due to the effect of the load applied to the table, resulting in a change in the table position. When the positioning error is detected by the position detection sensor and the positioning command data is corrected using the detected value of the movement delay amount of the first nut and the detected value of the position change of the ball screw, a delay occurs due to the load. Control with corrected table position can be performed.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings to provide an understanding of the present invention.
The following embodiments are examples embodying the present invention and do not limit the technical scope of the present invention.

FIG. 1 is a front view showing the configuration of the positioning device according to the present embodiment. The positioning device 1 includes a ball screw 2, a motor 4 that rotationally drives the ball screw 2,
A first nut 5 screwed to the ball screw 2, a second nut 6 also screwed to the ball screw 2, a table 3 mounted on the first nut 5, and a relative distance attached to the second nut 6 The detection sensor 7 and the ball screw 2
A guide 9 for connecting the second nut 6 to the table 3 so as to be slidable in the direction of movement of the table 3, a first sensor 7 and a second The control unit 10 is configured to correct the positioning command data based on the value detected by the sensor 8 and control the rotation of the motor 4.

In the above configuration, in order to position the work 12 placed on the table 3 at a predetermined position, the first nut 5 on which the table 3 is mounted may be moved linearly by rotating the ball screw 2. Since the moving distance of the first nut 5 with respect to the rotation speed of the ball screw 2 is known, the controller 1
If the moving distance from the origin position of the table 3 to the positioning point is input to 0 as command data, the control unit 10 controls the driving of the motor 4 at the number of revolutions corresponding to the moving distance. When the ball screw 2 rotates at a predetermined number of rotations by the rotation of the motor 4, the first nut 5 linearly moves a predetermined distance, and can move the mounted table 3 to a predetermined position.

However, the work 12 is placed on the table 3.
When the motor 4 is rotationally driven in a state in which a load due to is applied, the ball screw 2 and its bearing 11,
The first nut 5 is distorted, causing a delay in the movement of the first nut 5 and causing an error in the positioning of the table 3. In the above configuration, means for correcting this positioning error is provided.

The first means for correcting the positioning error of the table 3 includes a second nut 6 shown in FIG. 1, a relative position detecting sensor 7 attached to the second nut 6,
The second nut 6 is configured to be connected to the table 3 by a guide 9 so that a load from the table 3 is not applied to the nut 6.

As shown in FIG. 1, the guide 9 has a guide plate 9a formed on the back surface of the table 3 in a long and convex shape in the moving direction of the table 3, and a guide nut 9 formed on the second nut 6. The table 3 and the second nut 6 do not directly contact each other, and are configured so that the weight from the table 3 is not applied to the second nut 6. Therefore, the second nut 6 has the table 3
When the first nut 5 affected by the load applied to the table 3 has a movement delay, the relative distance between the first nut 5 and the second nut 6 varies by ΔL1. Occurs. A relative position detection sensor 6 is attached to the second nut 6 so as to face a distance detection plate 5 a attached to the first nut 5, and measures a relative distance between the first nut 5 and the second nut 6. The amount of change ΔL1 in relative distance when a movement delay occurs in one nut 5 is detected. When the detected relative distance change amount ΔL1 is input to the control unit 10 and the positioning command data is corrected, positioning can be performed with the movement delay of the first nut 5 corrected.

The second means for correcting the positioning error of the table 3 is constituted by a position detecting sensor 8 for detecting the end position of the ball screw 2 shown in FIG.

The ball screw 2 and its bearing 11 are distorted by the influence of the load from the table 3, and the ball screw 2 changes its position by ΔL2 in the axial direction. Since the position detection sensor 8 is arranged on the end side of the hole screw 2 and measures the position change of the end position of the ball screw 2, the position change amount ΔL2 in the axial direction due to the distortion can be detected. When the detected position change amount ΔL2 is input to the control unit 10 to correct the positioning command data, the positioning error of the table 3 due to the distortion of the ball screw 2 can be corrected.

By using both the first means and the second means for correcting the positioning error of the table 3, more accurate positioning can be performed. That is, two change amounts ΔL1 and ΔL2 that hinder positioning accuracy are detected in real time, the change amount ΔL1 + ΔL2 is input to the control unit 10, and the motor 4 is rotationally driven by data obtained by correcting the positioning command data by the change amount ΔL1 + ΔL2. Then, positioning can be performed more accurately.

[0021]

As described above, according to the first aspect of the present invention, the first nut is affected by the load from the table to cause a movement delay, whereas the second nut is affected by the load from the table. Not affected. Therefore, by detecting the movement delay amount of the first nut with respect to the second nut as a relative distance and correcting the positioning command data based on the detected value, it is possible to perform control in which the position of the table that is delayed due to the load is corrected.

According to the second aspect of the present invention, the axial position of the ball screw changes due to the distortion generated in the ball screw and its bearing due to the load applied to the table, causing an error in the table position. When a change in the axial position of the ball screw is detected by the sensor and the positioning command data is corrected based on the detected value, control can be performed to correct the table position that is delayed due to the load.

Further, according to the third aspect of the present invention, the first nut is affected by the load from the table, causing a movement delay, whereas the second nut is not affected by the load from the table. The amount of delay in the movement of the first nut with respect to the second nut is detected as a relative distance, and the axial position of the ball screw changes due to the distortion generated in the ball screw and its bearing due to the effect of the load applied to the table. The resulting error is detected by the position detection sensor,
When the positioning command data is corrected using the detected value of the movement delay amount of the first nut and the detected value of the change in the position of the ball screw, control can be performed in which the table position that is delayed due to the load is corrected.

As described above, according to the first to third aspects of the present invention, the table can be quickly and accurately positioned at low cost without using a large-sized and expensive sensor in the conventional example.

[Brief description of the drawings]

FIG. 1 is a front view showing a configuration of a positioning device according to an embodiment of the present invention.

FIG. 2 is a front view showing a configuration of a positioning device according to a conventional configuration.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Positioning device 2 Ball screw 3 Table 4 Motor 5 1st nut 6 2nd nut 7 Relative position detection sensor 8 Position detection sensor 9 Guide 10 Control part

Claims (3)

[Claims] 1. A positioning device for positioning a table mounted on a nut screwed into a ball screw rotationally driven by a motor at a predetermined position by controlling the rotation of the motor. The first screwed into the ball screw
A nut, a second nut screwed into the ball screw at a predetermined distance from the first nut, a relative distance detection sensor for detecting a change in a relative distance between the second nut and the first nut, And a control unit for controlling the rotation of the motor by correcting the positioning command data based on the value detected by the relative distance detection sensor. 2. A positioning device for positioning a table mounted on a nut screwed into a ball screw driven and rotated by a motor at a predetermined position by controlling the rotation of the motor. A nut screwed into the ball screw, a position detection sensor for detecting a change in the axial position of the ball screw, and a control unit for controlling the rotation of the motor by correcting the positioning command data based on the detection value of the position detection sensor. A positioning device, comprising: 3. A positioning device for positioning a table mounted on a nut screwed to a ball screw driven and rotated by a motor at a predetermined position by controlling the rotation of the motor. The first screwed into the ball screw
A nut; a second nut screwed into the ball screw at a predetermined distance from the first nut; a relative distance detection sensor for detecting a change in a relative distance between the second nut and the first nut; A position detection sensor that detects a change in the axial position of the motor, and a control unit that controls the rotation of the motor by correcting the positioning command data based on the detection values of the relative distance detection sensor and the position detection sensor. A positioning device characterized by the above-mentioned.