JPS5988265A - Method and device for clamping screw - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] Kinei FfA relates to a screw tightening method and device in which the screw tightening torque is controlled by the drive current of a motor with a reducer connected with a screw tightening tool. The purpose of tightening is to complete the work in a short time while maintaining torque accuracy at a good level.

Screw tightening takes advantage of the fact that the current of the motor that drives the device is proportional to the load torque.For screw tightening, the motor current is set in advance and compared with the current value corresponding to the torque, and the motor current reaches the set value fJtJ. A screw tightening device is known that terminates the tightening operation u1 by detecting an increase. If the rotational speed of the motor is increased in order to shorten the working time in such screw tightening equipment, the tightening torque may vary due to the influence of the inertia of the motor's armature, or the torque may be insufficient for small tightening operations. The same point was observed that even when attempting to tighten a screw, the tightening torque would overshoot.

The present invention is an addition to the conventional screw 1117 method and apparatus.
The main object of the present invention is to provide a new screw tightening method and device that solves the above-mentioned problems.

That is, in the present invention, the motor rotation speed is maintained at the maximum speed within a range where the torque does not overshoot the target torque until the screw is seated, and after the first seating is detected, the motor rotation speed is reduced to the inertia. By switching to a low degree of tension that can avoid the influence, screw tightening time can be shortened and tightening accuracy can be improved at the same time.

In view of this objective, the present invention provides a screw tightening method in which the load torque is detected by the motor current and torque control is performed, the motor is rotated at high speed until the screw is seated, and the motor is rotated at a low speed after the screw is seated. A screw tightening method is characterized in that the motor rotation speed at high speed is controlled to a value proportional to the target torque, and a voltage control is applied to the power input section.
A screw tightening device is connected to a motor with a speed reducer connected to a tool, and a current detector is used to detect the motor current. Setting the motor current to the seating torque level
A first comparator for comparing the motor current with the first comparator, a funshot timer that emits a pulse No. 4R for a predetermined time by the circle of the third comparator, and a self-tightening motor current that is detected by the current generator L11. The gist of the invention is a screw tightening device characterized in that a second comparator is connected to the output of the target torque setting device, and a delay timer is connected to the second comparator, which uses the output of the second comparator as an input signal. be.

Hereinafter, the present invention will be described in detail based on the illustrations of the accompanying drawings. In the drawings, Figure 1 is a block diagram showing the structure of the screw tightening device, and Figure 2 is a characteristic diagram of each part of the device to explain the screw tightening operation. As shown in Fig. 1, device A connects a power input section consisting of a starting switch 0) and an input device (2) with a screw tightening tool (not shown) via a voltage controller (3) and a direction switch (4). After deceleration (61
A motor current detector (7) is connected to a screw tightening device that is connected to a motor (5), and the motor current detected by the current detector (7) is outputted as a seating torque level setting gain (8). a first comparator (9) for comparison with the first comparator (9);
)° output for a predetermined period of time, and the motor current detected by the current detector (7) is compared with the output of the target torque setting device (6) for tightening. A second comparator (Ill) and a delay timer 0 which uses the output of the second comparator (II) as an input value are connected.Hereinafter, the screw tightening work procedure using the above screw tightening device will be explained. Explanation 1. First, when you press the activation switch (ll), @L Oppression Sen 1 device (3) is activated & 11 via the input device (2).

The direction changer (4) connected in series to the voltage controller (3) rotates the motor (6) in the direction of screw tightening, and is attached to the output shaft of the deceleration 4ff4 +5'l. The subsequent tightening of the screw (not shown) also causes a rotation Mu1.

Voltage controller (3) #'i', target torque i can be set freely for tightening with lfr
Using the output voltage (V) of the t' regulator (6) as a reference, a voltage (v2) proportional to the reference output voltage (V) is generated as an output to drive the motor (6). In this way, the motor (
5) The torque for screw tightening is determined by the output voltage (V) of the target torque setting device (6) for fqW', and the output voltage (
Since the rotation speed of the motor (6) is proportional to the voltage (v2) of the voltage controller (3), which is determined by the V engineering), the tightening speed can maintain a proportional relationship with the target torque. can. In this way, when tightening electricity is collected in advance, the screw tightening work proceeds at the motor rotation speed according to the target torque, so the torque accuracy is maintained at a good level and the screw tightening process is maintained at a good level. The working time required is also significantly reduced compared to conventional equipment.

When the motor (5) is started via the 1111 voltage distribution controller (3) and the direction switch (41), the motor current is detected by the current detector (7) and the current is passed to the first comparator (
In step 9), it is compared with the output of the seating torque level setter (8).

When the screw is tightened by the rotation of the motor (6) and the screw is seated on the seat (not shown), the load torque increases as shown in the second section (e), and accordingly, as shown in Fig. 2). The motor current increases. When the motor current reaches the seating level indicated by the symbol 'jJ (L) in Figure 1), the first comparator generates an output corresponding to the motor current increased by 91. The output of (9) is transmitted to the open shot timer (10,.
4) is reversed, and during this period the rotational speed of the motor (5) is decreased.

On the other hand, the output #i of the first comparator (9) voltage controller (3)
It is also transmitted to Therefore, after the screw is seated, the voltage controller (3) drives the motor (5) with a reduced output voltage to achieve a controlled low speed rotation in which the inertia of the armature etc. of the motor does not substantially affect the torque accuracy. Create candy. From now on, Figure 2 (
As shown in (b), a constant motor voltage is maintained and the motor (
5) Rotate and apply additional feed to the seated screw. Thereafter, the output of the current detector (7) and the output of the target torque setter (6) for tightening are compared in the second comparator (Ill), and the motor current is determined as shown in Figure 2. For tightening indicated by symbol (L2), the direction indicator (4) is reversed by the output of the target torque level comparator (II) to brake the motor (6J), and the second comparator (
The output voltage of the voltage controller (3) is made zero by the output of the tiller timer θ2), which uses the output of the motor (11) as an input signal, and the power supply to the motor (6) is cut off, thereby completing the screw welding operation.

As is clear from the above explanation, Kinori 1 rotates the motor at high speed to increase the screw entry speed until the motor current reaches the preset f1' level, and the motor current reaches the M level. After detecting that the motor speed has been reached, the motor rotation speed is switched to a low speed and the screw is tightened, thereby achieving the two different purposes of shortening the screw tightening time and improving torque accuracy when tightening the K screw. And,
It has an extremely high utility value.

In addition, as a preferred application example of the present invention, 'C1 voltage controller has Beniwaki 11',! One example of implementation is to connect the I mechanism and control the initial current when starting the motor to avoid the difference in torque output.

[Brief explanation of the drawing]

Figure 1 is a block diagram showing the overall structure of the screw tightening device;
Figure 2 shows screw tightening! It is a characteristic line diagram of each part of the apparatus explaining lσ1 operation. ill...Start switch, (2)...Input device, (3)...
・'Voltage controller, (4)... Direction switch, (5)... Motor, (6)... Target torque setting device for tightening, (7)...
Motor current detector, (8)... Seating torque level setter, f91... First comparator, (10.1... One-shot timer, (1s...%.2 comparator, θ' 4-・Delay timer.

Claims (1)

[Scope of Claims] ill In a screw tightening method in which torque control is performed by detecting load torque using motor current, the motor is rotated at high speed until the screw is seated, and after the screw is seated, the motor is rotated at low speed, A screw tightening method characterized by controlling the motor rotation speed at high speed to a value proportional to the target torque. (2) A current detector for detecting the motor current is connected to the screw tightening device, which consists of a motor with a speed reducer connected to a screw tightening tool via a voltage controller and a direction switch to the power input section. , a seventh comparator that compares the motor current detected by the current detector with the output of the M seat torque level setter;
a one-shot timer that emits all pulse signals for a predetermined period of time based on the output of the first comparator; and a second comparator that compares the motor current detected by the current detector with the output of the target torque setting device for tightening. , and a delay timer that uses the output of the second comparator as an input signal.