JPS6234514B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a bolt tightening machine that tightens a bolt by controlling the rotation angle of the bolt.

Generally, as shown in FIG. 1, a bolt tightening machine includes a drive motor 1, a reduction mechanism section 2 connected to the drive motor 1, and an output shaft driven by the drive motor 1 via the reduction mechanism section 2. A bolt tightening machine body consisting of a socket 3 that engages with a bolt or nut to be attached and tightened, and a reaction force receiver 5 having a claw 4 that receives a reaction force when tightening the bolt, and a drive motor 1 for the bolt tightening machine body. and a control section 6 that controls the. Then, as shown in FIG. 2, the claw 4 of the reaction force receiver 5 is brought into contact with the adjacent bolt 8 which has been completely tightened, and while the reaction force is applied thereto, the tightening bolt 7 Tighten. In this case, in order to prevent damage due to over-tightening of the bolts, the control section 6 needs to manage the tightening of the bolts.

Conventionally, in this type of bolt tightening machine, a rotation control method has been implemented as a means of bolt tightening management, in which the rotation angle of the bolt is controlled and the tightening date is determined.

Normally, in a bolt tightening machine that uses this rotation angle control method, the rotation angle of the output shaft of the drive motor is detected by a rotation angle detector, and the detected rotation angle and the reference set in advance by a setting device are detected. Compare with the rotation angle,
Comparison control is performed in which the input current to the drive motor is cut off when these two become equal.
However, in conventional bolt tightening machines that use rotation angle control, the voltage supplied to the drive motor is always constant, and the speed immediately after the input current is cut off depends on the magnitude of external forces such as friction (each Since the torque coefficient of each bolt varies depending on the torque coefficient (each bolt has a different torque coefficient), the increase in the rotation angle of the bolt due to inertia after the input current of the drive motor is cut off varies from bolt to bolt, and therefore the final tightening force of the bolt changes. cannot be kept constant,
The drawback was that the bolt tightening accuracy deteriorated.

The present invention has been made in consideration of these points, and in the rotation angle control method, when performing a comparison calculation between the actual rotation angle of the bolt and the reference rotation angle, the reference rotation angle and the actual rotation angle of the bolt are The speed of the drive motor is automatically reduced as the deviation from The company provides a bolt tightening machine.

The bolt tightening machine according to the present invention converts the rotation angle of its output shaft into pulses and digitally detects them, and sequentially counts the deviation between the detected pulse number and a preset reference pulse number, This is amplified by a D/A converter, and the drive motor is driven by the amplified output.

Hereinafter, one embodiment of the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIG. 3, the bolt tightening machine according to the present invention has an output on the side of the bolt tightening machine main body 9, which consists of a drive motor 1, a reduction mechanism section 2, a socket 3, etc. as shown in FIG. A rotation angle detection pulse generator 10 provided to generate a pulse signal according to the rotation of the shaft, and a standard for outputting a number of reference pulse signals Ps corresponding to a preset reference rotation angle of the output shaft. A pulse generator 11 and a deviation counter that reads the reference pulse signal Ps from the reference pulse generator 11, presets the number of reference pulses, and reads the rotation angle detection pulse signal P from the pulse generator 10 to perform subtraction counting. 12, and a D/A that converts the output of this deviation counter 12 into an analog signal.
a converter 13, and a servo amplifier 1 that amplifies the output of the D/A converter 13 and operates the drive motor 1 of the bolt tightening machine main body 9 using the amplified signal.
It is composed of 4 and 4. In this embodiment, in order to stabilize the speed of the drive motor 1, the output frequency f of the rotation angle detection pulse generator 10 is converted into a voltage signal V by an f/V converter 15. However, although a loop control system is provided that negatively feeds back a voltage signal corresponding to the speed to the input side of the servo amplifier 14, such a loop control system is not particularly required.

In the bolt tightening machine of the present invention configured in this manner, the rotation angle detection pulse signal P of the output shaft by the pulse generator 10 is subtracted and counted from the reference pulse signal Ps set in advance in the reference pulse generator 11. Accordingly, the drive motor 1 is driven until the amount of droop pulses in the deviation counter 12 becomes zero. At this time, the rotation angle control system of the drive motor 1 is directly used as a drive system, and the rotation angle detection pulse signal P
The output of the deviation counter 12 that subtracts and counts Ps from the reference pulse signal Ps is processed as appropriate via the D/A converter 13 and the servo amplifier 14, and the signal is used as the drive signal for the drive motor 1. As the rotation of the shaft progresses, the output of the deviation counter 12 becomes smaller. Therefore, when the input voltage of the drive motor 1 decreases and its rotation speed decreases, and the rotation angle detection pulse signal P and the reference pulse signal Ps become equal, the rotation speed of the drive motor 1 becomes almost zero. Therefore, the bolt can be tightened at a predetermined rotation angle without being over-shrinked due to inertia.

Further, as another embodiment of the present invention, when the tightening torque acting on the bolt to be tightened reaches a preset predetermined value, the control unit 6 is provided with a torque detector that detects this and outputs a detection signal. The deviation counter 12 may be operated by the detection signal of the torque detector. That is, in FIG. 4, a torque detector is installed at a part of the bolt tightening machine main body 9 shown in FIG. Torque detection switch (e.g. strain gauge, etc.) that detects when the reaction force reaches a predetermined torque value
16 is shown.

In the bolt tightening machine configured in this way, until a predetermined tightening torque is applied to the bolt when tightening the bolt, that is, until the torque detection switch 16 is activated, the deviation counter 12 shows the rotation angle as described above. Deceleration counting for determining the difference between the detection pulse signal P and the reference pulse signal Ps is not performed, and instead, a constant pulse signal is output from the deviation counter 12 to cause the drive motor 1 to rotate at a constant speed. . Next, when the torque detection switch 16 is activated, the detection signal causes the deviation counter 1 to be activated.
2 is reset, the reference pulse signal Ps is input from the reference pulse generator 11 to the deviation counter 12, and the deviation counter 12 performs the above-mentioned subtraction counting. Therefore, in the bolt tightening machine according to this embodiment, the starting point for controlling the rotation angle of the bolt is when the bolt tightening torque reaches a predetermined value (snapping torque), and thereafter the bolt tightening is managed. Since this is done by controlling the rotation angle, there is an advantage that the bolt can be tightened with higher precision.

Although not particularly shown, since the tightening torque of the bolt is proportional to the load current of the drive motor 1,
In place of the torque detector, a current detector is provided which detects the load current of the drive motor 1 and outputs a detection signal when the detected value reaches a predetermined current value set in advance. Deviation counter 12
It is also possible to make it work.

As mentioned above, the bolt tightening machine according to the present invention has the following features:
A pulse generator that generates a pulse signal according to the rotation is attached to the output shaft of the main body, and the difference between the counted value of the rotation angle detection pulse signal and the reference pulse signal preset by the pulse setting device is calculated as a deviation counter. The output of the deviation counter is D/A converted and further amplified to become the driving voltage of the drive motor.As the bolts are tightened, the voltage of the drive motor increases. The speed is automatically reduced and the bolts are not over-tightened due to the inertia of the drive motor when the input current is interrupted.The simple structure prevents external forces such as friction that act on the bolts after the input current of the drive motor is interrupted. Regardless of the situation, it has the excellent advantage of being able to always tighten the bolt at the desired angle.

In addition, regarding the bolt tightening machine according to the present invention,
It is not limited to those in each of the above embodiments,
For example, various modifications are possible, such as using a pulse motor as the drive motor 1, amplifying the output of the deviation counter 12 with a pulse signal amplifier, and configuring the pulse motor to be driven by the amplified output. be.

[Brief explanation of the drawing]

Fig. 1 is a front view showing the appearance of a general bolt tightening machine, Fig. 2 is a diagram showing the operating state of a reaction force receiver, and Fig. 3 is a block diagram showing a bolt tightening machine according to an embodiment of the present invention. FIG. 4 is a block diagram showing another embodiment of the present invention. 1... Drive motor, 2... Reduction mechanism section, 3...
Socket, 4...Claw, 5...Reaction force receiver, 6...Control unit, 7...Tightening bolt, 8...Adjacent bolt, 9
... Bolt tightening machine body, 10 ... Pulse generator for rotation angle detection, 11 ... Reference pulse generator (pulse setting device), 12 ... Deviation counter, 13 ...
D/A converter, 14... Servo amplifier, 15...
f/V converter, 16... Torque detection switch.

Claims (1)

[Scope of Claims] 1. A drive motor, a deceleration mechanism connected to the drive motor, and a bolt and nut that are attached to an output shaft driven by the drive motor via the deceleration mechanism and are to be tightened. A bolt tightening machine body consisting of a matching socket; a pulse generator that outputs a rotation angle detection pulse signal according to the rotation of the output shaft of the bolt tightening machine body; and a pulse generator that outputs a preset number of reference pulse signals. A reference pulse generator that outputs, a deviation counter that reads the number of output pulses of this reference pulse generator and starts subtraction counting according to the pulse signal output from the pulse generator, and an analog signal that outputs the output of this deviation counter. a control unit consisting of a D/A converter that converts the analog signal into a D/A converter; and an amplifier that amplifies and outputs the analog signal converted by the D/A converter, and uses this output to drive the drive motor of the bolt tightening machine main body. A bolt tightening machine characterized by comprising: 2. A drive motor, a deceleration mechanism connected to the drive motor, a socket attached to an output shaft driven by the drive motor via the deceleration mechanism and engaged with a bolt or nut to be tightened, and a bolt. A bolt tightening machine body consisting of a reaction force receiver that receives a reaction force during tightening; a pulse generator that outputs a rotation angle detection pulse signal in accordance with the rotation of the output shaft of this bolt tightening machine body; a reference pulse generator that outputs a number of reference pulse signals;
When the tightening torque of the bolt tightening machine body reaches a preset predetermined value, a torque detector detects it and outputs a detection signal, and the torque detector is reset by the detection signal of the torque detector. a deviation counter that reads the number of output pulses from a reference pulse generator and starts subtraction counting according to the pulse signal output from the pulse generator; and a D/A converter that converts the output of the deviation counter into an analog signal. , and a control section comprising an amplifier that amplifies and outputs the analog signal converted by the D/A converter, and uses this output to drive the drive motor of the bolt tightening machine. Bolt tightening machine. 3. The bolt tightening machine according to claim 2, wherein the torque detector is a torque detection switch. 4. The bolt tightening machine according to claim 2, wherein the torque detector is a current detector.