JPH0123712Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a screw tightening device that can ensure that screws are tightened with a force exceeding a certain torque.

[Prior art]

Conventionally, a screw tightening device in which a screw tightening shaft is driven by an electric motor detects tightening torque based on a change in the current value of the electric motor being driven.

However, in the case of a screw tightening device in which the screw tightening shaft is driven by an air motor, the tightening torque cannot be detected during tightening, and therefore the tightening torque is checked after tightening.

[Problems with conventional technology]

Conventional methods of detecting tightening torque based on changes in current do not detect the actual torque that has been generated, so even if the current value increases due to an abnormality in the detection circuit or electric motor, the operator cannot generate the specified torque. There is a possibility of making a wrong judgment.

In addition, even if resistance occurs due to some abnormality in the reduction gear or transmission member that connects the electric motor and the screw tightening shaft, it is assumed that the screw tightening torque is normal even if the screw is not actually tightened. commit the wrong judgment.

When using an air motor, checking the torque is time consuming and inefficient. A device for setting the screw tightening torque in automatic screw tightening machines has been developed.
It is described in Publication No. 51-78499. As shown in FIG. 4, this device has a lever 70 protruding from the peripheral wall of the planetary gear reduction part 31 attached to the screw tightening shaft 4.
The tip of the lever 70 is pressed against the fixing member 72 by the spring 71, and the peripheral wall of the planetary gear reduction part 31 rotates due to the reaction when the screw tightening is completed, and the lever 70 resists the pressing force of the spring 71. The screw tightening is completed by detecting the point in time when the screw is separated from the fixing member 72.

The above device confirms that the screw is tightened to the set torque when the screw tightening reaction force exceeds the pressing force of the spring 71. However, in this device, in order to change the magnitude of the screw tightening torque, it is inconvenient that the spring 71 must be replaced or a spring force adjustment mechanism must be provided to reset the relationship between the spring and the torque. .

Moreover, the reaction force that acts on the lever 70 when screw tightening is completed acts as a bending force on the screw tightening shaft 4. Therefore, the bending force acting on the shaft 4 each time a screw is tightened causes asymmetric wear of the device and the shaft. This is not desirable as it may cause breakage.

[Means to solve the problem]

The present invention uses the reaction force that the screw tightening device receives when tightening the screw to ensure that the screw is tightened to a certain torque or higher.

A further object of the present invention is to provide a device that allows the set value of the screw tightening torque to be easily changed and that does not apply asymmetric bending force to the screw tightening shaft.

In the present invention, a screw tightening main body 1 configured by connecting a screw tightening shaft 4 to a drive device 11 is attached to a support member 5 so as to be movable up and down, and a plurality of upper and lower positions of the support member 5 are connected to a plurality of upper and lower positions of a guide member 8. We support
The support surfaces of the guide member 8 and the support member 5 are such that one member 5 has an arc-shaped slide member 7 centered on the screw tightening shaft 4, and the other member 8 has an arc-shaped slide member 7 that extends in the horizontal plane of the slide member 7. An air supply pipe 9 is connected to one of the slide member 7 and the guide member 8 via a pressure regulator 93.
A piston rod 92, which is removably fitted into the cylinder tube 91, is attached to the cylinder tube 91 of the air cylinder device 9 connected to the air cylinder device 4, and the piston rod 92 is fitted into the cylinder tube 91 so as to be retractable. When the screw tightening main body 1 rotates in the opposite direction to the screw tightening direction, the slide member 7 overcomes the resistance of the air cylinder device 9. A switch 95 is provided to detect rotation in the direction opposite to screw tightening.

[Effect]

When the screw is in the tightened state, the main body of the screw tightening device 1
A tightening reaction force is generated. That is, a force is applied to rotate the main body 1 in the opposite direction to the screw tightening direction, and the screw tightening device main body 1 rotates about the screw tightening shaft 4 against the resistance force of the air cylinder device 9.
At this time, the slide member 7 receives a force from the air cylinder device 9, but since the support member 5 is supported by the guide member 8 restraining the upper and lower portions of the support member 5, the inclination of the support member 5 and the screw tightening shaft 4 No bending occurs, and the slide member 7 can move smoothly in an arc.

The magnitude of the set screw tightening torque is determined by the air pressure of the air cylinder device 9, so by adjusting the pressure regulator 93, the air pressure changes, and the screw tightening set torque can be easily changed.

〔Example〕

The present invention will be specifically described below based on embodiments shown in the drawings.

The main body 1 of the screw tightening device is the same as that disclosed in Japanese Utility Model Application No. 160125/1983.

The main body 1 of the screw tightening device has a drive shaft 2 connected to a rotary drive device 11 capable of forward and reverse rotation. Connect to. The screw tightening shaft 4 is connected to the drive shaft through a second one-way clutch 3a that can transmit rotation in the same direction as the rotation transmission direction of the first one-way clutch 3, and a gear reduction mechanism 6 that rotates in the opposite direction to the rotation direction of the drive shaft 2. It is connected to 2.

There is a pipe 4 for screw suction on the outer periphery of the screw tightening shaft 4.
2 is fitted into the pipe 42, and a suction hose 43 is fitted to the pipe 42.
are connected.

When tightening a screw, when the drive shaft 2 is rotated in the tightening direction, the screw tightening shaft 4 rotates at high speed via the first one-way clutch 3, thereby tightening the screw S at high speed.

At this time, the second one-way clutch 3a idles in the anti-tightening direction, and there is no problem with the high-speed rotation of the screw tightening shaft 4 in the tightening direction.

Just before tightening the screw, if the rotation of the rotary drive device 11 is switched and the drive shaft 2 is rotated in the opposite direction, the second one-way clutch 3a is activated via the gear reduction mechanism 6.
The rotational force in the tightening direction is transmitted to the screw tightening shaft 4, and the rotation is transmitted to the screw tightening shaft 4.

At this time, the first one-way clutch 3 on the drive shaft 2 idles in the anti-tightening direction, and there is no problem with the rotation of the screw tightening shaft 4 in the tightening direction.

The input to the second one-way clutch 3a is decelerated by the gear reduction mechanism 6, so the screw tightening torque is large and the screw can be strongly tightened.

A slide block 12 is provided protruding from the distal end side of the rotary drive device 11 of the screw tightening device main body 1 to the base end side of the screw tightening shaft 4. Vertical axis 51, 51
The screw tightening device main body 1 is vertically driven by a vertical drive device 52 on the support member 5 .

A pair of arc-shaped slide members 7, 7 having the screw fastening shaft 4 as the radial center are disposed on the support member 5 to face each other vertically.

A fixed stand 81 is provided on the outside of the support member 5,
The slide members 7, 7 are attached to the upper end of the stand 81.
A guide member 8 is fitted between the guide members 8 and 8, and is curved to the same curvature as the slide member 7 to guide the slide member 7. A rolling ball 82 is provided between the guide member 8 and the slide member 7 to smooth the sliding movement.

Attachment arms 70 and 80 are provided outwardly protruding approximately at the center of the slide member 7 and at one end of the guide member 8, and between the two attachment arms 70 and 80, the guide member 8 and the screw tightening device main body 1 are inserted in the screw tightening direction. It is connected by an air cylinder device 9 which provides resistance to rotation and has cushioning properties.

In the air cylinder device 9 of the embodiment, a cylinder tube 91 is pivotally supported on the mounting arm 70 of the slide member 7, and a piston rod 92 is pivotally supported on the other mounting arm 80.

An air supply pipe 94 is connected to the cylinder tube 91 via a pressure regulator 93, and urges the piston rod 92 in the retracting direction.

A micro switch 95 is provided in the cylinder tube 91, and a detection piece 95a of the switch 95 is placed against the mounting arm 80 on the guide member 8 side.

However, as described above, the screw tightening is performed by the screw tightening device main body 1. The slide member 7 is pushed in the thread cutting direction by the air cylinder device 9, and is pressed against a fixed member such as the guide member 8. When the screw S is tightened, the main body of the screw tightening device 1
When a tightening reaction force acts on the slide member 7 and this reaction force overcomes the resistance force of the air cylinder device 90, the slide member 7
The main body 1 of the screw tightening device including the screw tightening device rotates in the anti-screw tightening direction.

This ensures that the screw S is tightened with a torque greater than the torque corresponding to the biasing force of the cylinder.

By adjusting the pressure of the air cylinder device 90, the screw tightening torque can be freely adjusted.

When the screw tightening device main body 1 is displaced, the detection piece 95a of the micro switch 95 separates from the mounting arm 80 and the switch 95 is activated, so that the screw tightening device main body 1
displacement can be reliably detected. Further, the rotation drive device 11 of the screw tightening device main body 1 is stopped by the signal from the switch 95, and the vertical drive device 52 is activated to raise the screw tightening device main body 1 and engage the screw tightening shaft 4 and the screw S. It is also possible to remove the match.

Furthermore, if an electric motor is used as the rotary drive device 11, the tightening torque can be double checked based on the change in the current value of the motor during screw tightening and the displacement of the screw tightening device main body 1.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway front view of the screw tightening device, FIG. 2 is a plan view, FIG. 3 is a sectional view of a one-way clutch portion, and FIG. 4 is a schematic diagram of a conventional device. 1...screw tightening device main body, 11...drive device, 4...
Screw tightening shaft, 8...Guide member.

Claims (1)

[Scope of utility model registration request] A screw tightening main body 1 configured by connecting a screw tightening shaft 4 to a drive device 11 is attached to a support member 5 so as to be movable up and down, and the support member 5 is supported at a plurality of upper and lower locations on a guide member 8 at a plurality of upper and lower locations. The supporting surfaces of the guide member 8 and the support member 5 are such that one member 5 has an arc-shaped slide member 7 projecting around the screw tightening shaft 4, and the other member 8 has a slide member 7 protruding from the slide member 7. It forms a bearing surface that allows arcuate movement in a horizontal plane, and an air cylinder device 9 connected to an air supply pipe 94 via a pressure regulator 93 is installed between the slide member 7 and the guide member 8. Part 7
is pressed against the fixing member in the screw tightening direction to create resistance when the screw tightening main body 1 rotates in the opposite screw tightening direction. The screw tightening device is characterized in that it is equipped with a switch 95 that detects rotation in the anti-screw tightening direction by overcoming the resistance of the screw tightening device.