JP2021133475A - Screw fastening device - Google Patents

Abstract

To provide a screw fastening device capable of detecting output torque with high accuracy.SOLUTION: A screw fastening device 1 according to the present invention comprises a motor M that can be driven to rotate, a rotation transmission mechanism 10 connected to this motor M to transmit a rotational force of the motor M, a fastening tool 30 that is rotated by receiving the rotational force of the rotation transmission mechanism 10 and has a tip part 31 fitted to a bolt B to be fastened to a workpiece, and control means 40 for controlling the rotational driving of the motor M. Further, this screw fastening device 1 comprises a torque sensor 20 for detecting torque applied to the fastening tool 30. The torque sensor 20 is arranged on the downstream side of the rotation transmission mechanism 10.SELECTED DRAWING: Figure 1

Description

The present invention relates to a screw tightening device capable of detecting the output torque of a bit with high accuracy.

As shown in Patent Document 1 and FIG. 2, the conventional screw tightening device includes a motor M that can be driven to rotate, a torque sensor 20 that rotates in response to the rotation of the motor M and can detect torque, and the torque sensor. The first gear 11 connected to 20 and rotatably arranged, the second gear 12 arranged to mesh with the first gear 11 and extending parallel to the axis of the first gear 11, and the second gear 12 are integrated. It is composed of a socket 30 that rotates and fits into a bolt S that is fastened to a work (not shown), and a control means 40 that drives and controls a motor M based on a detection signal of the torque sensor 20. As described above, the conventional screw tightening device 100 is configured by arranging the torque sensor 20 on the upstream side at a position where rotation is input to the first gear 11 and the second gear 12 that mesh with each other.

The operation of the conventional screw tightening device will be described. The control means 40 commands the motor M to be driven to rotate. As a result, the rotational force of the motor M is sequentially transmitted to the torque sensor 20 and the first gear 11, and the second gear 12 that meshes with the first gear 11 rotates together with the socket 30 at a predetermined rotational speed. Further, at this time, since the socket 30 descends in the direction approaching the work, the bolt S fitted in the socket 30 is screwed into the work. Since the bolt S that has received the rotational force of the socket 30 is seated on the work, the torque applied to the socket 30 starts to increase sharply from the time when the bolt S is seated. The torque applied to the socket 30 is transmitted to the torque sensor 20 via the second gear 12 and the first gear 11, and a detection signal corresponding to the detected torque value is output from the torque sensor 20 to the control means 40. NS. The control means 40 determines whether the detection torque output from the torque sensor 20 has reached a preset set torque, and if so, stops the rotation of the motor M to end the screw tightening operation.

Japanese Patent No. 4329377

However, since the conventional screw tightening device 100 has a configuration in which the first gear 11 and the second gear 12 are meshed with each other, the rotation output from the second gear 12 with respect to the rotational force input to the first gear 11. The power decreases. Therefore, in the conventional screw tightening device 100, the detection torque detected by the torque sensor 20 located on the upstream side of the first gear 11 and the output torque of the socket 30 located on the downstream side of the second gear 12 Was different.

Further, in order to solve the problem that the detection torque and the output torque are different from each other, the rotation transmission efficiency of the first gear 11 and the second gear 12 is obtained in advance, and the obtained rotation transmission efficiency and the above-mentioned rotation transmission efficiency are obtained. It was necessary to calculate the output torque based on the detected torque and manage the torque. However, since the rotation transmission efficiency changes and varies each time, there is a problem that it is difficult to manage the output torque of the socket 30 with high accuracy by the torque management that calculates this as a fixed value.

The present invention includes a motor that can be driven to rotate, a rotation transmission mechanism that is connected to the motor and transmits the rotational force of the motor downstream, and a rotation transmission mechanism that receives the rotational force of the rotation transmission mechanism to rotate and fasten to a work. In a screw tightening device including a fastening tool having a tip portion to be fitted to a fastening component and a control means for rotationally driving and controlling the motor, a torque sensor for detecting torque applied to the fastening tool is provided. The torque sensor is characterized in that it is arranged on the downstream side of the rotation transmission mechanism. It is desirable that the torque sensor is connected to the rotation transmission mechanism and the fastening tool. Further, the control means compares the preset torque set in advance with the detection torque detected by the torque sensor, and stops the rotational drive of the motor when the detection torque reaches the set torque. It is desirable to order it. Further, the rotation transmission mechanism may be a gear transmission mechanism in which a plurality of gears are meshed with each other. Further, the rotation transmission mechanism includes an input shaft connected to the motor and an output shaft connected to the fastening tool, and the input shaft and the output shaft are arranged so that their respective axis lines are parallel to each other. May be done.

In the screw tightening device according to the present invention, since the torque sensor is arranged on the downstream side of the rotation transmission mechanism, it is possible to detect with high accuracy without correcting the output torque applied to the fastening tool as in the conventional case. There are advantages. Further, in the screw tightening device according to the present invention, one end of the torque sensor is connected to the rotation transmission mechanism, while the other end is connected to a fastening tool that fits with the fastening component, so that the output torque applied to the fastening component is applied. There is also an advantage that can be detected directly. Further, the screw tightening device according to the present invention includes a control means for comparing a preset set torque with the detection torque detected by the torque sensor, and the control means has reached the set torque. There is also an advantage that it is not necessary to correct the detection torque as in the conventional case because the control is performed so as to stop the rotational drive of the motor. Further, in the screw tightening device according to the present invention, since the rotation transmission mechanism is a gear transmission mechanism in which a plurality of gears mesh with each other, there is an advantage that the rotational force of the motor can be increased or decreased and the reduction ratio can be easily set. There is also. Further, by arranging the input shaft and the output shaft of the rotation transmission mechanism in parallel, the motor mounting positions can be arranged so as to be close to the socket. This also has the advantage that the overall length of the screw tightening device can be made compact.

It is the schematic explanatory drawing of the screw tightening apparatus which concerns on this invention. It is the schematic explanatory drawing of the conventional screw tightening apparatus.

As shown in FIG. 1, the screw tightening device 1 according to the present invention is connected to a motor M capable of rotating at a predetermined rotation speed, a rotation transmission mechanism 10 connected to the motor M, and the rotation transmission mechanism 10. A torque sensor 20, a fastening tool 30 connected to the torque sensor 20, and a control means 40 connected to the motor M to rotate and control the motor M are provided, and are mounted on a robot (not shown) and mounted on a work. It is configured so that it can be fastened by screwing in a screw.

The motor M is a so-called AC servomotor, and includes an encoder that detects the rotation angle of the output shaft M1 thereof, and is configured to be able to appropriately transmit the rotation angle to the control means 40.

The rotation transmission mechanism 10 rotatably supports the drive gear 11 connected to the output shaft M1 of the motor M, the driven gear 12 that meshes with the drive gear 11, and the drive gear 11 and the driven gear 12. It includes a base plate 13 and a cover 14 fixed to the base plate and arranged so as to cover the driving gear 11 and the driven gear 12.

Further, the rotation transmission mechanism 10 is configured such that two gears of the drive gear 11 and the driven gear 12 are meshed with each other, but the present invention is not limited to this, and for example, three or more gears are meshed with each other. You may. Further, the rotation transmission mechanism 10 is configured to engage gears, but is not limited to this. For example, a belt is wound around a rotatable pulley to transfer the rotational force of the motor M to the torque sensor 20. It may be configured to transmit.

The torque sensor 20 includes a connecting shaft 21 having one end connected to the driven gear 12 and the other end connected to the fastening tool 30 and capable of integrally rotating the driven gear 12 and the fastening tool 30. It consists of. Further, the torque sensor 20 is connected to the control means 40, and is configured to detect the torque loaded on the connecting shaft 21 and appropriately transmit the detected detection torque to the control means 40.

The fastening tool 30 includes a tip portion 31 that can be fitted to a bolt B, which is an example of a fastening component, and a suction member 32 that is arranged at the tip portion 31 and sucks the bolt B. The tip portion 31 is formed in a shape that fits the head of the bolt B into the outer periphery, and is formed in a hexagonal hole shape in this embodiment. Further, the suction member 32 is a magnet arranged so as to be in contact with the crown portion of the bolt B, and is formed by sucking the bolt B fitted to the tip portion 31.

Further, the tip portion 31 of the fastening tool 30 is appropriately set according to the shape of the head of the fastening part, and the screw of the head having a cross hole from the fastening part having the hexagonal head of the present embodiment. If so, it is molded into a cross-shaped tip that fits into the cross hole.

The control means 40 is connected to the motor M and the torque sensor 20, and stores the rotation speed of the motor M in advance and stores the set torque to be compared with the detection torque detected by the torque sensor 20. .. Further, the control means 40 is configured to be able to command to stop the rotation of the motor M when the detected torque reaches the set torque. Further, the control means 40 is configured to be able to transmit a situation in which the rotation of the motor M is controlled to the robot.

The operation of the screw tightening device 1 configured in this way will be described. The control means 40 receives a command from the robot, reads out the rotation speed stored in the command, and controls the rotation drive of the motor M based on the rotation speed.

As a result, the rotational force of the motor M is sequentially transmitted to the rotation transmission mechanism 10, the torque sensor 20, and the fastening tool 30, and the bolt B attracted to the fastening tool 30 starts rotating at a predetermined rotational speed. Since the robot moves the fastening tool 30 that rotates by the rotational drive of the motor M toward the work, the bolt B starts to be screwed into the work.

The rotation of the fastening tool 30 causes the head of the bolt B to gradually approach the upper surface of the work, and eventually the head is seated on the work. At this time, since the motor M is rotationally controlled at the rotational speed, the torque applied to the bolt B suddenly increases after the bolt B and the work are seated. The torque sensor 20 appropriately transmits the torque applied to the bolt B as a detection torque to the control means 40.

The control means 40 compares the detected torque with the set torque, and when the detected torque reaches the set torque, immediately stops the rotation of the motor M and completes the fastening of the bolt B. Upon completion of this fastening, the robot moves the fastening tool 30 so as to be positioned above the work and completes the screw tightening operation.

As described above, the screw tightening device 1 according to the present invention includes a rotation transmission mechanism 10 having poor rotation transmission efficiency due to meshing of gears or a belt and a pulley, but the torque sensor 20 is more than the rotation transmission mechanism 10. Since it is arranged on the downstream side, the torque applied to the bolt B can be detected without being affected by the rotation transmission efficiency of the rotation transmission mechanism 10. Therefore, the screw tightening device 1 according to the present invention has an advantage that the tightening torque of the fastening component to be fastened to the work can be detected and managed with high accuracy, and moreover, the detection torque detected by the torque sensor 20 is corrected as in the conventional case. Since there is no need, there is an advantage that torque management can be facilitated.

Moreover, since the screw tightening device 1 according to the present invention can manage the detection torque detected by the torque sensor 20 as it is as the tightening torque of the bolt B as described above, the rotation transmission of the rotation transmission mechanism 10 is performed in advance as in the conventional case. There is no need to seek efficiency. Therefore, it is not necessary to periodically inspect the rotation transmission efficiency, which has an advantage of improving productivity.

1 ... Screw tightening device 10 ... Rotation transmission mechanism 20 ... Torque sensor 30 ... Fastening tool 31 ... Tip 40 ... Control means B ... Bolt M ... Motor

Claims (5)

A motor that can be driven to rotate, a rotation transmission mechanism that is connected to this motor and transmits the rotational force of the motor downstream, and a fastening part that rotates by receiving the rotational force of this rotation transmission mechanism and is fastened to the workpiece. In a screw tightening device provided with a fastening tool having a matching tip and a control means for rotationally driving and controlling the motor.
A torque sensor for detecting the torque applied to the fastening tool is provided.
The torque sensor is a screw tightening device characterized in that it is arranged on the downstream side of the rotation transmission mechanism. The screw tightening device according to claim 1, wherein the torque sensor is connected to the rotation transmission mechanism and the fastening tool. The control means compares the preset torque set in advance with the detection torque detected by the torque sensor, and commands the rotation drive of the motor to be stopped when the detection torque reaches the set torque. The screw tightening device according to claim 1 or 2, wherein the screw tightening device is made of the above. The screw tightening device according to any one of claims 1 to 3, wherein the rotation transmission mechanism is a gear transmission mechanism in which a plurality of gears are meshed with each other. The rotation transmission mechanism includes an input shaft connected to the motor and an output shaft connected to the fastening tool.
The screw tightening device according to any one of claims 1 to 4, wherein the input shaft and the output shaft are arranged so that their respective axis lines are parallel to each other.

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