JPH1029167A - Bolt fastening machine - Google Patents

Abstract

(57) [Summary] [Purpose] It is an object of the present invention to provide a bolt fastening machine which has no variation in fastening force when fastening with low torque and can fasten in a short time when fastening with high torque. . A motor for generating a rotational torque, a motor driving unit for driving the motor, a control power supply unit,
A torque setting unit 10 for adjusting the tightening torque, a drive control unit including a microcomputer 8 or the like in which a soft start holding time parameter suitable for each set torque is input in advance, and a current value of the power supply lines 3 and 4 And the current detection unit 6 for detecting the torque change, the holding time of the soft start is automatically changed when the setting of the tightening torque is changed. Therefore, in the case of fastening with a high torque, the bolt can be fastened in a short time, and when fastening with a low torque, the tightening force is constant.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the control of a bolt fastening machine using the rotational torque of a motor.

[0002]

2. Description of the Related Art A bolt fastening machine is used for fastening bolts and nuts, and drives a series motor to perform fastening by utilizing this rotational torque. An appropriate value is determined for the tightening torque depending on the size of the bolt or nut, and a torque setting dial is provided on the operation box or the tightening machine main body to adjust the tightening torque. In this tightening machine, inertia (inertia) occurs when the socket mounted on the socket mounting part rotates rapidly during tightening.
, The tightening torque varies. In particular, when tightening with a low torque, the variation becomes large. To prevent this, a soft start function is provided that rotates at a low speed at the beginning of rotation.

[0003] The soft start function of the conventional bolt fastening machine is such that the soft start holding time of the motor is constant regardless of whether the tightening is performed at a low torque or at a high torque. Can not. Therefore, a bolt tightening machine that sets the soft start holding time to a long time takes a long time to tighten, and a bolt tightening machine that sets the holding time to a short time requires a low torque due to the effect of inertia. In the fastening force at the time.

[0004]

When a nut or the like is tightened with a bolt fastening machine having a long soft start holding time, the time required for soft start is long, so that it takes a long time to tighten. However, when a small diameter screw is tightened with a low torque in a fastening machine in which the soft start holding time is set to a short time, there is a problem that the fastening force of the screw varies due to the influence of inertia.

[0005] The present invention has been made in view of such circumstances, and when a large-diameter screw is tightened by a high torque, the screw can be fastened in a short time. It is an object of the present invention to provide a bolt fastening machine that does not vary in fastening force when fastening.

[0006]

A motor for generating a rotational torque, a motor driving unit for driving the motor, a control power supply unit, a torque setting unit for adjusting a tightening torque, and software suitable for each set torque By providing a drive control unit composed of a microcomputer or the like in which the start retention time parameter is input in advance, and a current detection unit that detects the current value of the power supply line, software can be changed by changing the setting of the tightening torque. The holding time of the start is automatically changed, and in the case of tightening nuts and the like with high torque, it is possible to tighten in a short time, and when fastening with low torque,
The problem is solved by providing a bolt fastening machine with a fixed fastening force.

[0007]

When the switch of the fastening machine is turned on, the motor built in the main body rotates, and the rotation is reduced by the speed reducer, and the socket mounting portion rotates. By mounting the socket on this socket mounting part and rotating the socket,
Nuts and the like are tightened.

In terms of electricity, when the power switch is turned on, a current flows through the control power supply unit, the microcomputer and the trigger circuit to the power control element, so that the current of the power supply line is reduced. Through the motor to the motor. As a result, the rotor of the motor rotates and the bolts and nuts are fastened. The current flowing in the motor is detected by a current detection unit and fed back to the microcomputer, and the current value detected in the microcomputer is compared with the set current value set in the torque setting unit to determine whether the current value is excessively large or small. . If the current flowing through the motor is too small relative to the set current value, the current continues to flow and the tightening proceeds. If the current value becomes excessive with respect to the set current value due to the continuation of the tightening, the microcomputer determines and turns off the trigger circuit. As a result, the current from the trigger circuit stops, the power control element turns off, the rotation of the motor stops, and the tightening is completed.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described based on an embodiment. FIG.
3 to 3 show embodiments of the present invention. FIG. 1 is a block diagram showing an electrical configuration of a bolt fastener according to an embodiment of the present invention, FIG. 2 is a side view of the bolt fastener according to an embodiment of the present invention, and FIG. It is a flowchart which shows an operation.

Hereinafter, the structure of the bolt fastening machine will be described with reference to FIG. The fastening machine 1 includes a main body 17 having a substantially cylindrical outer shape, a socket mounting section 19 mounted on one end of the main body, and a mechanical section 1 integrally formed on the other end of the main body.
6. The mechanism 16 includes a grip 25, and a motor and a speed conversion mechanism (both not shown) are built in the main body 17. The grip 25 is formed so that an operator can grip it with his / her hand, and a trigger-like power switch 20 is disposed at a position where a finger is located in a gripping state. In the vicinity of the power switch 20, there is provided a lock switch 21 for fixing the trigger-shaped power switch 20 in a pulled state. When the switch is turned on, the motor built in the main body is rotated, the rotation is reduced by the speed reducer, and the socket mounting portion is rotated. A nut or the like is tightened by mounting the socket on the socket mounting portion and rotating the socket.

Hereinafter, an electrical configuration of the fastening machine 1 will be described with reference to FIG. The fastening machine 1 is connected to a commercial AC power supply (hereinafter, power supply) 2 via a power cable 15 and outputs a control power supply unit 5 that outputs a drive voltage of a predetermined fixed voltage level.
It has. The power supply lines 3 and 4 also include a motor 27 for generating a rotational torque, a power control element 14 for controlling power supplied to the motor 27, and
And a current detector 6 for detecting the current value of the current.
Further, a torque setting dial 10 for setting a tightening torque, a microcomputer 8 for comparing a set current value with a current value flowing through the power supply lines 3 and 4 and controlling ON / OFF of the current control element 14 and a trigger circuit 9 And The microcomputer 8 is input with a soft start holding time parameter suitable for each torque setting in advance.

In such a configuration, the power switch 2
By inputting 0, the current is controlled by the control power supply unit 5 and the microcomputer 8
And flows to the power control element 14 via the trigger circuit 9.
Accordingly, the current of the power supply lines 3 and 4 flows to the motor 27 via the power control element 14, and the rotor rotates to fasten the bolts and nuts. The current flowing through the motor 27 is detected by the current detector 6 and fed back into the microcomputer 8. The current value detected in the microcomputer 8 is compared with a set current value set in the torque setting unit 10 to determine whether the current value is excessively large or small. Motor 2
If the current flowing through 7 is too small with respect to the set current value, the current continues to flow, and the tightening proceeds. If the current value becomes excessive with respect to the set current value due to the continuation of the tightening, the microcomputer 8 determines and turns off the trigger circuit 9. As a result, the current from the trigger circuit 9 stops, the power control element 14 turns off, the rotation of the motor 27 stops, and the tightening is completed.

Hereinafter, the operation of the fastening machine according to the present embodiment will be described with reference to FIGS. Prior to the work of fastening the bolts and nuts, an appropriate torque is set by a torque setting dial 10 provided on the main body or the control box in accordance with the size of the screw to be fastened. After setting the torque, by turning on the switch 20 of the motor 27, the set value set by the torque setting dial 10 is set to 000a1.
The search is sequentially performed in the direction of the step of the setting 100a5 from the step of (a). This is shown in steps a1, a3, and a5 of the flowchart of FIG. For example, when the set value is set to 050 by the torque setting dial, the microcomputer 8 outputs a NO signal because the value is smaller than the set value 050 in the setting 000 in step a1.
Thereafter, the data is sequentially searched up to just before the setting 050a3, a NO signal is output, and the data is lowered. Since step a3 of setting 050 is the value set by the torque setting dial, a YES signal is output in step a3 and the signal shifts to step a4 of "soft time setting at setting 050". The phase control starts a7 by setting the soft start holding time in this step, and the rotor of the motor 27 starts rotating. The rotation of the rotor starts tightening of the bolts and nuts.

The current value of the motor 27 gradually increases due to the tightening of the screws. This current value is detected by the power detection unit 6 and fed back to the microcomputer 8. In the microcomputer, this value is compared with the current value when the torque is set. If the current flowing through the motor 27 is lower than the set torque, a NO signal is output, and the motor 27 rotates as it is to continue the tightening. If the tightening is continued as it is, the current value of the motor 27 becomes equal to the current value of the set torque at a certain point, and the microcomputer determines YES.
Is output, the current flow from the trigger circuit 9 to the power control element 14 is stopped, and the current flow in the power control element 14 is cut off. As a result, the rotation of the motor 11 stops, and the bolts and nuts are tightened with an appropriate tightening torque.

As described above, the bolt fastening machine of the present patent application
Since the holding time parameter of the soft start suitable for each torque is previously input into the microcomputer 8 for each torque setting, the holding time corresponding to the torque is automatically set by the torque setting. Therefore, when tightening with a low torque, the soft start time is set to be long, and there is no variation in the tightening force, and the bolts and nuts can be tightened with a constant torque. Further, when tightening with a high torque, the soft start time is set short, so that the tightening can be performed in a short time.

[0016]

As described above, the bolt tightening machine of the present invention can automatically change the soft start time by the tightening torque, so that there is no variation in the tightening at a low torque, and a constant tightening force. Can be used to tighten bolts and nuts, and can be tightened in a short time when tightening with high torque. In this way, the reliability of screw tightening is improved and work efficiency is improved.

[0017]

[Brief description of the drawings]

FIG. 1 is a block diagram showing an electrical configuration of a bolt fastening machine according to one embodiment of the present invention.

FIG. 2 is a side view of a bolt fastening machine according to an embodiment of the present invention.

FIG. 3 is a flowchart showing an operation of the bolt fastening machine.

[Explanation of symbols]

 1 ... fastening machine 2 ... commercial AC power supply (power supply) 3, 4 ... power supply line 5 ... control power supply unit 6 ... current detection unit 8 ... ··· microcomputer 9 ···· drive control circuit 10 ··· torque setting unit 14 ··· power control element 15 ··· power cable 20 ··· power switch 27 ··· ··motor

Claims (1)

[Claims] 1. A bolt fastening machine capable of adjusting a tightening torque and having a soft start function, a motor for generating a rotating torque, a motor drive unit for driving the motor, a control power supply unit, and a tightening unit. A torque setting unit for adjusting the torque, a drive control unit composed of a microcomputer or the like in which a soft start holding time parameter suitable for each set torque is input in advance, and a current detection unit for detecting a current value of the power supply line. The holding time of the soft start is automatically changed when the setting of the tightening torque is changed by providing the bolt tightening machine.