JPS6141713B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention has two electric motors, a high-speed, low-torque electric motor and a low-speed, high-torque electric motor, and these two electric motors are rotated simultaneously to reduce the load during free rotation of bolts and nuts. This relates to an electric bolt tightening machine that tightens bolts and nuts using one of the electric motors according to fluctuations in the torque.

Generally, when tightening bolts and nuts using a bolt tightening machine, when the tightening torque of the bolt or nut reaches the set tightening torque T ₀ and the power of the bolt tightening machine is cut off, the bolt tightening machine The rotational angular velocity of the output shaft of is ω ₀ , the inertia rate of the rotating part of the bolt tightening machine is J, the spring constant of the bolt being tightened is k,
If the final tightening torque acting on the bolt/nut is T, then There is _a relationship _between the The time required will be longer.
Therefore, in order to tighten bolts and nuts at the set tightening torque in a short time, the bolts and nuts should be rotated at high speed and low torque during free rotation until they come into contact with the tightening member.
When tightening the bolt/nut after the bolt/nut contacts the tightening member, the bolt/nut may be rotated at low speed and high torque.

Therefore, conventionally, two electric motors are used: a high-speed, low-torque electric motor and a low-speed, high-torque electric motor, and when the bolts and nuts are rotating freely, the high-speed, low-torque electric motor rotates the bolts and nuts at high speed and low torque. ,
When the bolt/nut comes into contact with the tightening member and the current of the high-speed, low-torque motor becomes equal to the set value, the high-speed, low-torque motor is stopped, the low-speed, high-torque motor is rotated, and the bolt/nut is moved to a low speed. An electric bolt tightening machine has been proposed that tightens bolts and nuts with high torque, and when the current becomes equal to the current value corresponding to the set predetermined tightening torque value, the low-speed, high-torque electric motor is stopped and the bolts and nuts are tightened. has been done. However, with this type of electric bolt tightening machine, the threaded part of the bolt or nut may become galled, or the threaded part may become deformed or cracked before the bolt or nut comes into contact with the tightening member. If there is rust, the load on the high-speed, low-torque motor increases, and when the current reaches the set value, the high-speed, low-torque motor stops and switches to the low-speed, high-torque motor. Free rotation of the bolts and nuts is performed by a low-speed, high-torque electric motor. Therefore,
The drawback was that it took time to tighten bolts and nuts, and the longer the bolt, the greater the effect, which significantly reduced work efficiency.

In view of the above points, the present invention provides a high-speed, low-torque electric motor that transmits high-speed, low-torque to a socket drive unit via a high-speed, low-torque transmission unit, and a socket drive unit that transmits a high-speed, low-torque electric motor to a socket drive unit via a low-speed, high-torque transmission unit and a one-way clutch. In an electric bolt tightening machine that has a low-speed, high-torque motor that transmits low-speed, high-torque motors to parts, the high-speed, low-torque motor and the low-speed, high-torque motor are simultaneously rotated to reduce load fluctuations when the bolts and nuts rotate freely. Automatically switches between a high-speed, low-torque electric motor and a low-speed, high-torque electric motor depending on When the current of the high-speed, low-torque motor reaches the set value, it automatically switches to the low-speed, high-torque motor, tightens bolts and nuts at low speed and with high torque, and when the tightening torque reaches the set tightening torque, automatically switches to the low-speed, high-torque motor. The present invention provides an electric bolt tightening machine that cuts off and stops the current of a high-speed, low-torque electric motor and a low-speed, high-torque electric motor, shortens the time required for tightening, and improves work efficiency.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram of the mechanical structure of an electric bolt tightening machine according to an embodiment of the present invention, and FIGS. 2 and 3 are block diagrams of an embodiment of a control device.

In FIG. 1, an electric bolt tightening machine 1 includes a high-speed and low-torque electric motor 2 (hereinafter abbreviated as electric motor 2), a high-speed and low-torque transmission section 3, and a low-speed and high-torque electric motor 4 (hereinafter abbreviated as electric motor 4). 1), a low-speed high-torque transmission section 5, a one-way clutch 6, a socket drive section 7, a control device 8, and a plug 9 connected to an external power source (not shown).

The high-speed low-torque transmission section 3 consists of a reduction mechanism 10 connected to the output shaft of the electric motor 2 and a gear 11 attached to the output shaft of this reduction mechanism 10. Transmits high speed and low torque.

The low-speed high-torque transmission section 5 is a reduction mechanism connected to the output shaft of the electric motor 4, and the output shaft is connected to a one-way clutch 6.
Low speed and high torque is transmitted to the socket shaft 13 of the socket drive section 7.

The one-way clutch 6 is provided between the low-speed high-torque transmission section 5 and the socket drive section 7, so that the rotation of the output shaft of the low-speed high-torque transmission section 5 is higher than the rotation of the socket shaft 13 of the socket drive section 7. Only in this case, the output of the low speed high torque transmission section 5, that is, the low speed high torque is directly transmitted to the socket shaft 1 of the socket drive section 7.
3.

The socket drive unit 7 has one end connected to a one-way clutch 6.
A socket shaft 13 is connected to the socket shaft 13 and has a socket 12 removably attached to the other end, and a gear 14 is fixed to the socket shaft 13 and meshes with the gear 11 of the high-speed low torque transmission section 3. The output of the high-speed low-torque transmission section 3 or the low-speed high-torque transmission section 5 is transmitted to the bolt/nut that has been tightened, depending on the tightened state.

As shown in FIG. 2, the control device 8 includes a high-speed, low-torque electric motor control section 15 (hereinafter abbreviated as the control section 15) and a low-speed, high-torque electric motor control section 16.
(hereinafter abbreviated as a control section 16), and a gate cutoff circuit 17 as a current cutoff circuit. Further, the electric motor 2 and the electric motor 4 have armatures 2A and 4A and series field windings 2F and 4F, respectively, and are connected in series to thyristors 19 and 20, respectively, and are connected through a common switch 21 and a plug 9. connected to an external power source. In addition, the switch 21 is
It may be provided in the control device 8, the main body of the electric bolt tightening machine 1, or other easy-to-operate locations. Control unit 1
5 is a thyristor 19, a current detector 22 that detects the current of the motor 2, an amplifier 23 that amplifies and outputs the current detected by the current detector 22,
A current limit setting device 24 for setting the current limit value of the motor 2, the current difference between the current limit value set in the current limit setting device 24 and the output of the amplifier 23 is inputted, and the current of the motor 2 is set as the current limit setting device. As the value approaches the value, the phase of the thyristor 19 is reduced and the motor 2
The motor 2 is comprised of a phase control circuit 25 that gradually reduces the rotation of the motor 2 and maintains the motor 2 at approximately zero rotation when the current difference becomes approximately zero. The control unit 16 includes a thyristor 20, a current detector 26 that detects the current of the motor 4, and an amplifier 2 that amplifies and outputs the current detected by the current detector 26.
7. Torque setting device 28 for setting the current value corresponding to the predetermined tightening torque of the bolt/nut to be tightened
The current difference between the current value set in the torque setting device 28 and the output of the amplifier 27 is output to the gate cutoff circuit 17. The gate cutoff circuit 17 inputs the current difference, operates when this current difference becomes zero, outputs a gate cutoff signal to the thyristors 19 and 20, cuts off the gates at the same time, and shuts off the motor 2 and the electric motor. 4. Cut off the current and stop it. FIG. 3 shows another embodiment of the control device, in which a soft start circuit 18 is added to the circuit shown in FIG.
When the current value corresponding to the predetermined tightening torque value of the bolt/nut to be tightened, which is set in the torque setting device 28, is smaller than the starting current value of the electric motor 4, the starting current of the electric motor 4 causes the gate cutoff circuit 1 to be activated.
This is provided to prevent 7 from operating.

Next, the operation of the electric bolt tightening machine 1 having the above configuration will be explained with reference to FIGS. 1 and 2.

Now, connect the plug 9 to the external power source, set the current limit value of the motor 2 in the current limit setting device 24, set the predetermined tightening torque of the bolts and nuts to be tightened in the torque setting device 28, and tighten the socket 12. When the bolts and nuts are fitted and the switch 21 is turned on, the electric motor 2 is started via the thyristor 19.
At the same time, the electric motor 4 is also activated via the thyristor 20. Then, until the bolt/nut comes into contact with the tightening member, the power of the electric motor 2 is transmitted to the socket shaft 1 of the socket drive unit 7 via the high-speed low-torque transmission unit 3.
3, and allows the bolt/nut to freely rotate at high speed and low torque via the socket 12. In this case, the rotation of the output shaft of the low-speed high-torque transmission section 5 is much lower than the rotation of the socket shaft 13, so that it is blocked by the one-way clutch 6 and is not transmitted to the socket shaft 13. Normally, the rotational speed of the socket shaft 13 is about 200 rpm when driven by the high speed low torque transmission section 3, and about 10 rpm when driven from the low speed high torque transmission section 5. Next, bolt
When the nut comes into contact with the tightening member and enters the tightened state,
When the current of the motor 2 increases and the current value detected by the current detector 22 approaches the current limit value set in the current limit setting device 24, the rotation of the motor 2 is gradually controlled by the control section 15. decreases,
When the detected current value of the electric motor 2 becomes approximately equal to the set current limit value, the electric motor 2 reaches approximately zero rotation and maintains this state. On the other hand, this decreased rotation of the electric motor 2 is transmitted to the socket shaft 13 of the socket drive section 7 from the high speed low torque transmission section 3. When the rotation of this socket shaft 13 becomes lower than the rotation of the output shaft of the low-speed high-torque transmission section 5, the power of the electric motor 4 is transferred from the low-speed high-torque transmission section 5 to the socket shaft of the socket drive section 7 via the one-way clutch 6. 13, and tightens bolts and nuts via the socket 12 at low speed and high torque. In this case, a current difference between the current value of the motor 4 detected by the current detector 26 and the current value corresponding to the predetermined tightening torque of the bolt/nut set in the torque setting device 28 is determined by the control unit 16 to shut off the gate. It is output to the circuit 17. The gate cutoff circuit 17 operates when the input current difference becomes zero, and the thyristors 19 and 20
The gates of the motors 2 and 4 are cut off at the same time, and the currents of the motors 2 and 4 are cut off and stopped. Therefore, the bolt/nut is tightened with a predetermined tightening torque set in the torque setting device 28. Next, when the switch 21 is turned off, all the electric circuits are reset, and by fitting the socket 12 of the electric bolt tightening machine 1 to the next bolt/nut and repeating the same operation as described above, This allows you to tighten bolts and nuts. In addition, in the bolt/nut tightening work described above, when the bolt/nut is freely rotated at high speed and low torque by the electric motor 2 via the high speed/low torque transmission section 3 and the socket drive section 7, the bolt/nut is tightened. If the threaded part is galled, or there is a deformed or rusted part in the threaded part, the load on the motor 2 increases, and the detected current value of the motor 2 becomes equal to the setting value of the current limit setting device 24. Then, the electric motor 2 is held at zero rotation by the control unit 15, and the bolt/nut is freely rotated at low speed and high torque by the electric motor 4 via the low speed and high torque transmission unit 5, the one-way clutch 6, and the socket drive unit 7. be rotated. Then, when the threaded part of the bolt/nut stops galling, or the bolt/nut has escaped the deformed or rusted part of the threaded part, and the load becomes lighter as before, the bolt/nut will be reactivated by the electric motor. 2, it can be rotated at high speed and low torque via the high speed low torque transmission section 3 and the socket drive section 7. Therefore, the bolts and nuts are automatically switched to high speed, low torque or low speed, high torque according to the fluctuation of the load during free rotation, so that after the bolts and nuts start free rotation, The time required for free rotation until it comes into contact with the tightening member and enters the tightened state can be greatly reduced.

Further, another embodiment of the control device shown in FIG.
When the motor 4 is started, the starting current causes the motor 4 to be soft-started by the soft-start circuit 18 so that the gate cutoff circuit is not activated.
It has the same effect as shown in the figure.

In addition, the electric motor 4 is used instead of the soft start circuit.
The current value of the motor 4 detected by the current detector 26 for a certain period of time from the start of the torque setting device 28
In order to avoid matching with the setting value of
It is obvious that a dead band circuit may be provided between the current detector 26 and the amplifier 27.

As described above, the electric bolt tightening machine of the present invention includes a high-speed, low-torque electric motor that transmits high-speed, low-torque to the socket drive part via the high-speed, low-torque transmission part, and a unidirectional connection with the low-speed, high-torque transmission part. A low-speed, high-torque electric motor that transmits low-speed, high-torque to the socket drive unit via the clutch is simultaneously rotated, and the bolt and nut rotate freely according to load fluctuations.
Since the high-speed, low-torque electric motor and the low-speed, high-torque electric motor are automatically switched and used, the time required for free rotation of bolts and nuts can be greatly reduced, and work efficiency can therefore be significantly improved. can.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a mechanical structure of an embodiment of the present invention, and FIGS. 2 and 3 are block diagrams of an embodiment of a control device. 1... Electric bolt tightening machine, 2... High speed low torque electric motor, 3... High speed low torque transmission section, 4...
Low-speed, high-torque electric motor, 5...Low-speed, high-torque transmission unit, 6...One-way clutch, 7...Socket drive unit, 8...Control device, 9...Connection, 10...Reduction mechanism, 11, 14 ...Gear, 12...Socket,
13...Socket shaft, 15...High speed, low torque motor control unit, 16...Low speed, high torque motor control unit, 17...Gate cutoff circuit, 18...Soft start circuit, 19, 20...Thyristor, 21 …
...Switch, 22, 26...Current detector, 23,
27...Amplifier, 24...Current limit setting device, 25
...Phase control circuit, 28...Torque setting device.

Claims (1)

[Scope of Claims] 1. A high-speed, low-torque transmission section driven by a high-speed, low-torque electric motor, a low-speed, high-torque transmission section driven by a low-speed, high-torque electric motor, fitted with bolts and nuts to be tightened; A socket drive unit driven by the low speed high torque transmission unit via a high speed low torque transmission unit or a one-way clutch, the high speed low torque electric motor and the low speed high torque electric motor are simultaneously rotated, and the bolt and nut are rotated. When the bolt/nut rotates freely until it comes into contact with a tightening member and starts tightening the tightening member, the high-speed, low-torque transmission section and the low-speed, high-torque transmission section are automatically operated in accordance with changes in the load. When the bolt and nut are brought into contact with the tightening member and enter a tightening state, the high-speed and low-torque electric motor is brought to a state of almost zero rotation. holding the bolt and nut, and tightening the bolt and nut by the one-way clutch and the low-speed and high-torque transmission unit by the low-speed and high-torque electric motor via the socket drive unit, and the tightening torque of the bolt and nut reaches a predetermined tightening torque. Then, the electric bolt tightening machine includes a control device that simultaneously interrupts the currents of the high-speed, low-torque electric motor and the low-speed, high-torque electric motor. 2. The control device detects the current of the high-speed, low-torque electric motor, and when the detected current value becomes equal to a set current control value, maintains the high-speed, low-torque electric motor at approximately zero rotation. The currents of the high-speed, low-torque electric motor control unit and the low-speed, high-torque electric motor are detected, and the current between the detected current value and the current value corresponding to the predetermined tightening torque value set for the bolts and nuts to be tightened is calculated. A current difference between the outputs of the low-speed, high-torque motor control section that outputs the difference and the low-speed, high-torque motor control section is input, and when the current difference becomes zero, the high-speed, low-torque motor and the low-speed, high-torque motor control section output the difference. The electric bolt tightening machine according to claim 1, comprising a current interrupting circuit that simultaneously interrupts the current of the torque motor. 3. The control device detects the current of the high-speed, low-torque electric motor, and when the detected current value becomes equal to a set current control value, maintains the high-speed, low-torque electric motor at approximately zero rotation. The currents of the high-speed, low-torque electric motor control unit and the low-speed, high-torque electric motor are detected, and the current between the detected current value and the current value corresponding to the predetermined tightening torque value set for the bolts and nuts to be tightened is calculated. A current difference between the outputs of the low-speed, high-torque motor control section that outputs the difference and the low-speed, high-torque motor control section is input, and when the current difference becomes zero, the high-speed, low-torque motor and the low-speed, high-torque motor control section output the difference. The electric type according to claim 1, comprising a current interrupting circuit that simultaneously interrupts the current of the torque motor, and a circuit that prevents the current interrupting circuit from being activated by the starting current of the low-speed high-torque motor. Bolt tightening machine.