JPH0639330U - AC servo motor for driving nutrunner - Google Patents

Abstract

(57) [Summary] [Object] The present invention relates to an AC servomotor for driving a nutrunner, and by using a non-contact potentiometer as a means for detecting the rotation angle and position of the motor,
An object of the present invention is to provide an AC servomotor for driving a nutrunner, which is small, lightweight, inexpensive, and does not require position indexing at the time of starting. [Structure] AC servomotor 4 for driving nutrunner 1
Of the non-contact type potentiometer 3 at one end of the drive shaft 4a of the
Attach. This potentiometer 3 has a drive shaft 4
a permanent magnet 30 fixed to a and a pair of magnetic flux sensor members 31, 3 arranged and fixed such that the permanent magnet 30 is sandwiched and the phases of the output signals of the permanent magnet 30 are deviated from each other by 90 °.
It has 2 and 2, and enables 0 ° -360 ° full circumference detection.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a nutrunner driving AC servomotor, and more particularly to a nutrunner driving AC servomotor that facilitates detection of a rotation angle and a position of a drive shaft.

[0002]

[Prior art]

 In recent years, servo motors have been widely used in machine tools, industrial robots, general industrial machines, etc., and have become indispensable for promoting automation and labor saving. In particular, AC servomotors are superior to DC servomotors in terms of maintenance performance, high-speed and high-frequency operation performance, and therefore, recently, servomotors are rapidly becoming AC.

In the manufacturing process of machines and the like, the AC servo motor described above is also used as a drive source for a nut runner that automatically tightens bolts and nuts. In such a nutrunner driving AC servo motor, it is necessary to detect the rotation angle and position of the drive shaft of the motor and feed them back. However, an encoder or resolver is generally used as the detection means. Target.

[0004]

[Problems to be solved by the device]

 However, in such a conventional nutrunner driving AC servomotor, since the encoder and the resolver are used as the detection means of the rotation angle and the position, the mechanical size of the detection means becomes large and the installation location and There were problems such as restrictions on the range of movement. In addition, the mechanical weight becomes large, and the weight load of other machines supporting the nut runner also increases. Furthermore, these detection means are also expensive in terms of cost. Furthermore, in the incremental encoder for relative position measurement, it is necessary to perform position indexing at startup, and the indexing operation becomes complicated.

Therefore, in the present invention, a non-contact type potentiometer is attached to the drive shaft of an AC servomotor, and the rotation angle and position of the drive shaft are detected to make the device compact, lightweight and inexpensive, and at the time of startup. It is an object of the present invention to provide an AC servo motor for driving a nut runner which does not require position indexing.

[0006]

[Means for Solving the Problems]

 In order to solve the above problems, the invention of claim 1 is an AC servomotor for driving a nut runner, comprising a drive shaft connected to a screw tightening portion of a nut runner, wherein a non-contact type potentiometer is attached to the drive shaft. The rotation angle and position of the drive shaft are detected based on the output signal of the potentiometer.

In order to solve the above-mentioned problems, a device according to a second aspect of the present invention is, in addition to the structure of the first aspect, the non-contact potentiometer described above, wherein the permanent magnet is fixed to the drive shaft, and the permanent magnet. And a pair of magnetic flux sensor members that are arranged and fixed so that the output signals are out of phase with each other.

[0008]

[Action]

 According to the first aspect of the invention, the rotation angle and the position of the AC servo motor required for operating the nut runner are detected by the non-contact type potentiometer attached to the drive shaft of the AC servo motor. Therefore, the cost, size, and weight of the encoder and resolver can be reduced as compared with the conventional one that uses the encoder and the resolver as means for detecting the rotation angle and the position.

According to the second aspect of the invention, in addition to the action of the first aspect, the pair of magnetic flux sensor members can share one permanent magnet, and the axial length of the nut runner is further shortened. Further, by shifting the phases of the pair of magnetic flux sensor members, the 0 ° -360 ° full circumference detection structure can be provided with a simple structure.

[0010]

【Example】

 Hereinafter, the present invention will be described with reference to the drawings. 1 to 4 are views showing an embodiment of an AC servomotor for driving a nut runner according to the present invention. First, the configuration will be described.

In FIG. 1, reference numeral 1 denotes a nut runner, and the nut runner 1 is fixed to, for example, a bracket 2 connected to a moving mechanism (not shown). The nut runner 1 is provided with a non-contact type potentiometer 3, an AC servomotor 4, a speed reducer 5, a torque sensor 6, a speed reducer output shaft 7 and a screw tightening portion 8. The nut runner 1 is driven by signal processing. It is composed of a unit 9, a motor control unit 10 and a screw tightening control unit 11.

The AC servomotor 4 includes a drive shaft 4a, a rotor 4b, a stator 4c, and a case 4d. A screw tightening portion 8 is connected to one end of the drive shaft 4a through a speed reducer 5 and a torque sensor 6, and the tightening torque of the screw tightening portion 8 is detected by the torque sensor 6. On the other hand, a contactless potentiometer 3 is attached to the other end of the drive shaft 4a, and the rotation angle and position of the drive shaft 4a are detected based on the output signal of the contactless potentiometer 3. It has become so.

The contactless potentiometer 3 has a permanent magnet 30 and a pair of magnetic flux sensor members 31, 32. The permanent magnet 30 is fixed to the drive shaft 4a of the AC servomotor 4, and the pair of magnetic flux sensor members 31 and 32 sandwich the permanent magnet 30 so that their output signals are out of phase by 90 °. Further, the arrangement is fixed, and in this embodiment, it is fixed to the bracket 2 via the sensor support bracket 12. The rotation angle (relative angle from a certain starting point) and position (absolute position) of the drive shaft 4a are detected by the output signals from the pair of magnetic flux sensor members 31, 32.

Here, the detection principle of the contactless potentiometer 3 will be briefly described. 2A, 2 </ b> B, and 2 </ b> C respectively show a cross section taken along the line AA, a cross section taken along the line BB, and a cross section taken along the line CC of FIG. 1. As can be seen from (b), the magnetoresistive elements 31a and 32a are adhered to the facing surfaces of the magnetic flux sensor members 31 and 32 on the permanent magnet 30 side, and the magnetoresistive elements 31a and 32a are 90 ° apart from each other. The lead wires 31b and 32b are arranged so as to be offset from each other and are connected to each other.

When the drive shaft 4a makes one rotation, the output voltage ratio of the magnetoresistive elements 31a, 32a becomes a curve close to one cycle of a sine wave due to the magnetoresistive effect, for example, as shown in FIG. In each curve, as shown by the solid line in the graph, there are two linear regions of 90 ° width at 90 ° intervals, and the phases of the magnetoresistive elements 31a and 32a are shifted by 90 °. If only the linear portion is taken out, 0 ° -360 ° can be constituted by only the linear portion as shown by the solid line portion of the graph. In the present embodiment, the signal processing unit 9 discriminates each linear portion of the output signals of the magnetoresistive elements 31a and 32a and performs a predetermined signal processing, so that as shown in FIG. It outputs a voltage that increases linearly with one rotation (0 ° -360 °). From the output voltage characteristic shown in FIG. 4, the relative rotation angle and absolute position of the drive shaft 4a are detected.

The output signal of the signal processing unit 9 is input to the motor control unit 10 and the screw tightening control unit 11. The motor controller 10 includes a servo driver and controls the rotational position and speed of the drive shaft 4a. The screw tightening control unit 11 sets a screw tightening torque value, and sends a signal to the motor control unit 10 to stop the AC servomotor 4 when the set torque value is input from the torque sensor 6. Torque management and tightening position management. Specifically, when fitting a bolt or a nut to the screw tightening portion 8, it is necessary to align the bolt side and the screw tightening portion side with each other, and the motor control unit 10 determines the origin of the screw tightening portion. The output signal of the contactless potentiometer 3 is used for recognition. The motor controller 10 also uses this output signal for speed control of the AC servo motor. Then, the screw tightening control unit 11 adjusts the rotation angle (about 20 °) from when the bolt or the like is screwed into the fastening member and brought into contact with the seating surface until the tightening is completed. Determine from the output signal of to determine whether the tightening was successful.

As described above, in this embodiment, since the non-contact type potentiometer 3 is used as the means for detecting the rotation angle and position of the drive shaft 4a of the AC servomotor 4, an encoder or resolver is used. Compared with the conventional one, the nut runner 1 can be made cheaper, lighter, and smaller, and the position indexing at the time of starting can be eliminated. In particular, the weight reduction can reduce the weight burden on the machine in which the nut runner 1 is mounted, and the downsizing can reduce the axial length of the nut runner 1, thus making the nut runner 1 narrower. It can also be installed in place.

Further, in the present embodiment, since the pair of magnetic flux sensors 31 and 32 are arranged on both sides of one permanent magnet 30 so that the magnetic flux sensors 31 and 32 share the permanent magnet 30, The axial length of the nut runner 1 can be further shortened. Furthermore, since the pair of magnetic flux sensors 31 and 32 each having two linear portions each having a 90 ° width at 90 ° intervals are shifted by 90 ° from each other, 0 ° -360 ° full circumference detection is realized. The configurations of the contactless potentiometer 3 and the signal processing unit 9 can be simplified.

[0019]

[Effect of device]

 According to the present invention, the contactless potentiometer is attached to the drive shaft of the AC servomotor, and the rotation angle and position of the drive shaft are detected from the output signal of the contactless potentiometer. The nut runner can be made small, lightweight and inexpensive, and the position indexing at the time of start can be eliminated.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of an embodiment of an AC servomotor for driving a nut runner according to the present invention.

2A and 2B are views for explaining the configuration of the non-contact potentiometer, where FIG. 2A is a sectional view taken along the line AA in FIG. 1, and FIG. 2B is a sectional view taken along the line BB in FIG. FIG. 3C is a sectional view taken along the line C-C in FIG. 1.

FIG. 3 is a diagram showing an output voltage ratio characteristic of each magnetic flux sensor member of the contactless potentiometer.

FIG. 4 is a diagram showing an output voltage characteristic of the signal processing unit.

[Explanation of symbols]

 1 Nutrunner 3 Non-contact Potentiometer 4 AC Servo Motor 4a Drive Shaft 8 Screw Tightening Part 30 Permanent Magnet 31 32 A Pair of Magnetic Flux Sensor Members

Claims (2)

[Scope of utility model registration request] 1. An AC servomotor for driving a nut runner, comprising a drive shaft connected to a screw tightening portion of a nut runner, wherein a non-contact type potentiometer is attached to the drive shaft.
An AC servomotor for driving a nut runner, wherein a rotation angle and a position of the drive shaft are detected based on an output signal of the potentiometer. 2. The non-contact type potentiometer is arranged and fixed so as to sandwich the permanent magnet fixed to the drive shaft and the output signals from each other in phase. The AC servomotor for driving a nut runner according to claim 1, further comprising a pair of magnetic flux sensor members.