JPS5819431B2 - Nejishimetsukesouchi - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION If the axes of the male thread and the female thread that are screwed together do not match, biting will occur during tightening.

Even if you ignore this biting and continue screwing in, it is unlikely that the biting will be released, and in many cases the screw thread will break.

If biting occurs, rotate the male or female thread to some extent in a direction that will unscrew it, release the biting, and screw it in again.

SUMMARY OF THE INVENTION An object of the present invention is to provide a screw tightening device that automatically detects the occurrence of biting and automatically releases the biting.

That is, in the present invention, a prime mover for rotating the screw is provided.

This prime mover may be a hydraulic motor, a pneumatic motor, or an electric motor.

A detection means is provided to detect the magnitude of the load applied to the prime mover.

As this detection means, if a hydraulic motor or pneumatic motor is used as the prime mover, one that responds to the pressure in the hydraulic or pneumatic transmission path can be used, or if an electric motor is used, one that responds to the pressure in the hydraulic or pneumatic transmission path can be used. You can use one that responds to the current flowing through the motor.

It is also possible to provide a torque meter between the prime mover and the runner and use this torque meter as a detection means.

A switching means is provided which reverses the rotation of the prime mover when the load exceeds a certain value based on the operation or output of the detection means.

Needless to say, the direction of this reversal is the direction of releasing the biting.

As the switching means, a switching valve can be used if a hydraulic or pneumatic motor is used as the prime mover, and an electric switching switch can be used if an electric motor is used.

For example, if a three-phase induction motor is used as the prime mover, any two phases may be switched.

Further, the prime mover is not limited to one prime mover per runner, but a tightening prime mover and an injection release prime mover may be provided, and these may be switched by a switching means in accordance with the operation of the detection means. It is possible.

Now, once the biting is released, the switching means is returned to its original position to perform the tightening operation.

Whether or not the jamming has been released can be determined based on the operation or output of the detection means, but it can be considered that the jamming has been canceled when the prime mover has reversed about 0.5 to 2 times.

In many cases, when tightening is completed, the detection means operates in the same way as when injection occurs.

Therefore, it is required to determine whether the operation of the detection means is due to the occurrence of injection or the completion of tightening.

Various means for this determination are conceivable.

For example, since biting often occurs in the early stages of tightening, the number of revolutions of the runner from the start of tightening is counted, and if this count is below a certain level and the detection means operates, it is determined that the operation is due to injection. If the detection means operates at a certain level or more, it can be assumed that the operation is due to completion of tightening.

Needless to say, when the runner is reversed, the count should be subtracted by the number of revolutions.

In addition, if the runner approaches the workpiece in response to tightening, a limit switch is installed at the tip of the runner, and when this limit switch and the detection means operate together, tightening is complete, and only the detection means operates. In such a case, it may be considered that an injection occurs.

The figure shows an embodiment of the present invention, and is an example in which a screw tightening device is constructed using a pneumatic motor.

This example will be explained below.

A valve 3 for starting and stopping is provided between the air pump 1 and the pneumatic motor 2.

In the valve 3, the spool 4 is always pushed toward the left side in the figure by the force of the spring 5, so that the air supply to the pneumatic motor 2 is cut off, and when the solenoid 6 is energized, the spool 4 overcomes the force of the spring 5. moves to the right in the figure so that air is supplied to the motor 2.

The solenoid 6 is energized from the start of tightening until the signal indicating completion of tightening is issued.

A tightening completion detection means for issuing a signal indicating completion of tightening is not shown.

Reference numeral 7 denotes a control valve provided between the valve 3 and the motor 2, which integrates a detection means 8 and a switching means 9.

The switching means 9 includes a spool 10, a hole 11 housing the spool 10, and a normal rotation port 12 and a reverse rotation port 13 that communicate the hole 11 and the motor 2.

Hole 11 communicates with valve 3 via port 14.

The detection means 8 includes a check valve 15 that responds to the pressure within the normal rotation port 8, and a spring 16 that acts on the spool 10 so that the port 14 and the normal rotation port 12 are connected.

When the pressure inside the port 12 exceeds a certain value, the check valve 15 operates, and the spool 10 resists the force of the spring 16.
is moved to the right side of the figure so that port 14 and reverse port 13 are connected.

A runner 17 is connected to the motor 2.

Turn the nut 18 using the runner 17 and screw it onto the bolt 19.

Note that 20 is an exhaust port.

Next, the operation of the device configured as described above will be explained.

First, the nut 18 is held by the runner 17, and the axis of the nut 18 and the axis of the bolt 19 are substantially aligned.

Next, the solenoid 6 is energized and the spool 4 is moved to the right side in the figure against the spring 5.

When the spool 10 is removed, the spool 10 is in the state shown in the figure due to the force of the spring 16, so the pump 1 and the motor 2 are connected via the port 14 and the normal rotation port 12.

Therefore, the motor 2 rotates in a direction to screw the nut 18 onto the bolt 19.

If biting occurs, the pressure within the normal rotation port 12 will increase.

Therefore, the check valve 8 opens and the spool 10 moves to the right in the figure against the force of the spring 16.

Therefore, the connection between the pump 1 and the motor 2 through the forward rotation port 12 is broken, and the pump 1 and the motor 2 are connected through the reverse rotation port 13 instead.

Accordingly, the runner 17 is rotated in the opposite direction, and the biting between the nut 18 and the bolt 19 is released.

When the supply of air to the normal rotation port 12 is cut off, the pressure therein gradually decreases, so the check valve 15 closes and the spool 10 returns to the state shown in the figure by the force of the spring 16.

When the runner 17 is released, the runner 17 rotates in the direction to tighten the nut 18 against the bolt 19 again.

When the tightening is completed, the solenoid 6 is de-energized by the signal from the tightening completion detection means, so that the valve 3 enters the state shown in the figure and the supply of air from the pump 1 to the motor 2 is cut off.

[Brief explanation of drawings]

The figure is a pneumatic circuit diagram showing an embodiment of the screw tightening device of the present invention. 2...Pneumatic motor showing an example of a prime mover, 8...
...Detection means, 9...Switching means.

Claims (1)

[Claims] 1. A prime mover that rotates a screw, a load detecting means that detects the magnitude of the load applied to the prime mover, a tightening completion detecting means that outputs a signal indicating completion of tightening of the screw, and an operation or output of the load detecting means. a screw tightening device 6 comprising switching means for reversing the prime mover when the load is above a certain value and the tightening completion detection means does not output a tightening completion signal based on