JPS6325916B2 - - Google Patents

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention has two motors, a series-wound commutator motor for high-speed, low-torque use and a series-wound commutator motor for low-speed, high-torque use. -Related to bolt tightening machines that tighten nuts.

(Background of the Invention) Normally, when tightening bolts of an assembled structure, temporary tightening is not performed, and the bolts and nuts rotate idly several times and hit the tightening member to reach a predetermined tightening torque or rotation angle. Once this is reached, complete tightening of bolts and nuts. That is, the tightening work is performed from the state where the bolts and nuts are freely rotating. Moreover, the time required to tighten each bolt is minimized,
Work efficiency must be improved.

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 Let ω ₀ be the rotational speed of the output shaft of the bolt tightener, J be the inertia factor of the rotating part of the bolt tightening machine, k be the proportionality constant, and T be the final tightening torque acting on the bolt/nut, then T = √ ₀ ² + ₀ ² , the larger ω ₀ is, the greater the influence of inertia on the final tightening torque T is, and the smaller ω ₀ is, the smaller the influence of inertia on the final tightening torque T. The time required for tightening will be longer.
Therefore, in order to tighten bolts and nuts to the set tightening torque in a short time, it is necessary to rotate the bolts and nuts at high speed and low torque during free rotation (during light load).
When tightening (when the load exceeds a predetermined value), it is sufficient to rotate at low speed and high torque.

However, with conventional bolt tightening machines that connect a single prime mover to a reduction gear with a large reduction ratio and use it at low speed and high torque, even when bolts and nuts are freely rotating during bolt tightening work, Since the bolts and nuts are rotated at the same low speed and tightened with a set tightening torque or a set rotation angle, it takes a long time to tighten the bolts and nuts.

In addition, one prime mover is connected to a first-stage reduction gear, a friction clutch, a one-way clutch, and a second-stage reduction gear, and when the bolts and nuts are freely rotating, only the first reduction gear is used to drive the bolts and nuts at high speed and low torque. When the bolt/nut tightens against the tightening member and the tightening torque of the bolt/nut increases until it reaches a predetermined value, causing the friction clutch to slip,
There is also a conventional bolt tightening machine that automatically switches to low speed and high torque using a one-way clutch and a second stage reduction gear, and tightens bolts and nuts at a set tightening torque or a set rotation angle. This bolt tightening machine had the disadvantage that the friction clutch had a short service life because it slipped during low-speed tightening. There is also a method of tightening bolts and nuts using two motors (Japanese Patent Laid-Open No. 52-80599), but in this case, current is constantly flowing through the two motors, which is uneconomical. Additionally, since the final tightening uses bevel gears, there are drawbacks such as the power wrench itself being large.

(Purpose of the Invention) In view of the above points, the present invention provides a torque method in which two motors can be arbitrarily selected without using a friction clutch, and switching from high speed, low torque to low speed, high torque is automatically performed. The purpose of the present invention is to provide a bolt tightening machine that minimizes the time required to tighten bolts and nuts and improves work efficiency.

(Structure of the Invention) According to the present invention, the object is to provide a high-speed, low-torque electric motor that tightens bolts and nuts to a pre-tightening torque value at high speed and low torque when the load is light; a high-speed, low-torque motor current cutoff means for outputting a signal to cut off a gate of a thyristor circuit of the torque motor and operate the low-speed, high-torque motor; activated by a signal from the high-speed, low-torque motor current cutoff means; A low-speed, high-torque electric motor that tightens bolts and nuts to final tightening torque at low speed and high torque via a one-way clutch; when the tightening torque of this low-speed, high-torque electric motor reaches a preset final tightening torque value; This is achieved by a bolt tightening machine characterized by comprising a low-speed, high-torque motor current cutoff means for cutting off a gate of a thyristor circuit of the low-speed, high-torque motor.

(Example) Fig. 1 is a schematic diagram of the mechanical structure of the bolt tightening machine of the present invention, and Figs. 2 to 6 are block lines showing examples of the control circuit of the bolt tightening machine of the present invention. In the figures, the high-speed, low-torque motor current interrupting means in Figures 2, 3, and 5 is configured to set a current value corresponding to the current of the high-speed, low-torque motor and the pre-tightening torque value set in the torque setting device. a first comparator A that outputs a signal to operate the low-speed, high-torque electric motor when the two become equal; and a gate cutoff circuit that is energized by the signal from the first comparator A and outputs a stop signal. 23; and a phase control circuit 31 which shuts off the gate of the thyristor circuit 15 using a stop signal from the gate cutoff circuit 23. Also, the fourth
The high-speed, low-torque motor current cutoff means shown in Figs. Detector 32
and; a gate cutoff circuit 23 which is energized by the signal from the zero rotation detector 32 and outputs a stop signal;
A phase control circuit 3 that cuts off the gate of the thyristor circuit 15 with a stop signal from the gate cutoff circuit 23
It is composed of 1.

In addition, the low-speed high-torque motor current cutoff means shown in FIGS. a second comparator B that outputs a signal when the two become equal; a gate cutoff circuit 28 that is energized by the signal from the second comparator B and outputs a stop signal; and a gate cutoff circuit 28 that outputs a stop signal. and a phase control circuit 34 that shuts off the gate of the thyristor circuit 16 in response to a stop signal.

The low-speed, high-torque motor current cutoff means shown in FIGS. 5 and 6 includes a zero rotation detector 35 that detects when the rotation of the low-speed, high-torque electric motor reaches almost zero rotation and outputs a signal. ;This zero rotation detector 3
The gate cutoff circuit 28 is energized by the signal No. 5 and outputs a stop signal; and the phase control circuit 34 cuts off the gate of the thyristor circuit 16 with the stop signal from the gate cutoff circuit 28.

Note that in FIGS. 1 to 6, the same numbers represent the same members.

In FIG. 1, a bolt tightening machine 1 includes a high-speed, low-torque electric motor 3 (hereinafter abbreviated as electric motor 3),
A high-speed low-torque transmission section 5 consisting of a reduction mechanism 4, a gear 11 attached to the output shaft of the reduction mechanism 4 and meshing with a gear 12 fixed to a socket shaft 9, and a low-speed high-torque electric motor 6 (hereinafter referred to as electric motor 6). ) and a reduction mechanism 7, a socket shaft 9, a socket 10 detachably attached to the socket shaft 9, and the socket shaft 9.
A socket drive unit 13 consisting of a gear 12 fixed to the output shaft of the reduction mechanism 4 and meshing with a gear 11 attached to the output shaft of the reduction mechanism 4, a one-way clutch 14, a control device 2 and a bolt tightening machine 1 are connected to an external power source (not shown). The high-speed low-torque transmission section 5 is connected to the socket drive section via the gear 12 meshing with the gear 11, and the low-speed high-torque transmission section 8 is connected via the one-way clutch 14 to the socket drive section. It is connected to 13. Further, FIG. 2 shows an embodiment of the control circuit of the bolt tightening machine of the invention, and in the figure, the motor 3 and the motor 6 have armatures 3A, 6A and series field windings 3F, 6F, respectively. However, they are connected in series to thyristor circuits 15 and 16, respectively, and connected to a plug 37 via a common switch 17. The control circuit of the electric motor 3 includes a speed setting device 18, a soft start circuit 19, a thyristor circuit 15, and a current detector 2.
0, a high-speed and low-torque motor current cutoff means consisting of an amplifier 21, a temporary tightening torque setter 22 (hereinafter abbreviated as torque setter 22), a first comparator A, a gate cutoff circuit 23, and a phase control circuit 31; The control circuit for the motor 6 includes a foot start circuit 24, a thyristor circuit 16, and a current detector 2.
5. Amplifier 26, main tightening torque setting device 27 (hereinafter abbreviated as torque setting device 27), and second comparator B
, a gate cutoff circuit 28, and a low speed, high torque motor current cutoff means consisting of a phase control circuit 34. Now, connect the plug 37 to an external power source, fit the socket 10 into the bolt/nut to be tightened, and turn on the switch 17. The soft start circuit 19 will be energized, and the motor 3 will be connected to the thyristor circuit 15, phase A soft start is performed via the control circuit 31, and the rotation speed gradually increases to the rotation speed set in the speed setting device 18, and the rotation is transferred from the high-speed low torque transmission section 5 to the socket drive via the gears 11 and 12. Socket 1
Rotate 0 at high speed. This rotation is blocked by the one-way clutch 14 and is not transmitted to the low speed high torque transmission section 8. Therefore, the bolt/nut rotates freely at high speed, and when the bolt/nut comes into close contact with a tightening member (not shown), the current of the motor 3 increases. The current of this motor 3 is detected by a current detector 20,
It is taken out via the amplifier 21 and compared with the pre-tightening torque value set in advance in the torque setter 22 by the first comparator A, and the current of the electric motor 3 becomes equal to the current value corresponding to the pre-tightening torque value. When
A signal is sent to the gate cutoff circuit 23 to energize the gate cutoff circuit 23, a stop signal from the gate cutoff circuit 23 is outputted to the phase control circuit 31, the gate of the thyristor circuit 15 is cut off, and the motor 3 is stopped. Further, the signal from the first comparator A is simultaneously sent to the soft start circuit 24 of the control circuit of the motor 6, and the soft start circuit 24 is energized. When the soft start circuit 24 is energized, the motor 6 is soft-started via the phase control circuit 34 and the thyristor circuit 16, and at the same time, the low-speed high-torque transmission section 8 engages with the one-way clutch 14 to stop the rotation of the motor 6. is transmitted to the socket drive unit 13, and the bolts and nuts are tightened at low speed and high torque. The current of the motor 6 is detected by the current detector 25, taken out via the amplifier 26, and compared with the final tightening torque value set in advance in the torque setting device 27 by the second comparator B, so that the current of the motor 6 is When the current value becomes equal to the set final tightening torque value, a signal is sent to the gate cutoff circuit 28, and the gate cutoff circuit 28
is energized, a stop signal from the gate cutoff circuit 28 is output to the phase control circuit 34, the gate of the thyristor circuit 16 is cut off, and the motor 6 is stopped. Therefore, the bolts and nuts are correctly tightened with the final tightening torque value set in the torque setting device 27. Next, when the switch 17 is turned off, all the circuits are reset, and by fitting the socket 10 of the bolt tightening machine 1 into the next bolt/nut and repeating the above operation, the bolt/nut can be tightened continuously. Able to carry out attachment work. In this case, speed setting device 1
8 may be removed.

FIG. 3 is a block diagram of another embodiment of the control circuit for the bolt tightening machine of the present invention, in which the electric motor 3 of FIG.
In the control circuit, the soft start circuit 19 is removed, a phase control circuit 31 and a speed setter 18 are provided between the thyristor circuit 15 and the gate cutoff circuit 23, and a dead zone is provided between the current detector 20 and the amplifier 21. A circuit 29 is provided, and the other configurations are completely the same as in FIG. 2. That is, when the switch 17 is turned on, the rotation speed of the motor 3 rapidly increases to the speed set in the speed setting device 18 via the thyristor circuit 15, but due to the starting current of the motor 3, the gate cutoff circuit 23 is turned on. The current of the motor 3 detected by the current detector 20 is set at the torque setting device 22 for a certain period of time from the start of the motor 3 so as to prevent the motor 3 from being overloaded.
A dead band circuit 29 is provided in order to prevent the first comparator A from comparing the temporary tightening torque value of . Other functions and effects are the same as in the case of FIG. Note that in this case, the speed setter 18 may be removed.

FIG. 4 is a block diagram showing another embodiment of the control circuit for a bolt tightening machine according to the present invention.
In the figure, the electric motor 3 and the electric motor 6 have armatures 3A, 6A and series field windings 3F, 6F, respectively, and are connected in series to thyristor circuits 15, 16, respectively, and are connected via a common switch 17. 37
It is connected to the. The control circuit of the electric motor 3 includes a thyristor circuit 15, a current detector 20, an amplifier 21, a first comparator A, and a current limit setting device 30 for temporary tightening torque.
(hereinafter abbreviated as current limit setting device 30), and high-speed, low-torque motor current cutoff means consisting of a zero rotation detector 32, a gate cutoff circuit 23, and a phase control circuit 31, The configuration is exactly the same as that of the electric motor 6 shown in FIG. Now, connect the plug 37 to the external power supply and connect the socket 10.
Fit the bolt or nut to be tightened,
When the switch 17 is turned on, the electric motor 3 is started via the thyristor circuit 15, and its rotation is transmitted from the high-speed low-torque transmission section 5 to the socket drive shaft 13 via the gears 11 and 12, causing the socket 10 to operate at high speed and low torque. Rotate with . Therefore, the bolt/nut rotates freely at high speed, and if the bolt/nut contacts the tightening member (not shown) and still tries to rotate,
As the tightening torque acting on the bolts and nuts increases, the current in the motor 3 increases, tightening the bolts and nuts. The current of this motor 3 is detected by a current detector 20, taken out via an amplifier 21, matched with a set current value set in advance in a current limit setting device 30 by a first comparator A, and then The thyristor circuit 15 is controlled by the thyristor circuit 15. As a result, the bolts and nuts are tightened, and when the current of the motor 3 reaches the set current value of the current limit setting device 30, the phase control circuit 3
1, the rotation of the motor 3 gradually decreases, the rotation state of the motor 3 is detected by the zero rotation detector 32, and when the rotation of the motor 3 reaches almost zero rotation, a signal is generated. is sent to the gate cutoff circuit 23, the gate cutoff circuit 23 is energized, and a stop signal from the gate cutoff circuit 23 is outputted to the phase control circuit 31, the gate of the thyristor circuit 15 is cut off, and the motor 3 is stopped. Further, the signal from the zero rotation detector 32 is simultaneously sent to the soft start circuit 24 of the control circuit of the motor 6, and when the soft start circuit 24 is energized, the motor 6 is soft started via the phase control circuit 34. In exactly the same manner as in the case shown in FIG. 2, the bolts and nuts are properly tightened using the final tightening torque value set in the torque setting device 27.

Note that an integrator is incorporated in the zero rotation detector 32 so that the zero rotation detector 32 does not operate at the moment the electric motor 3 is started.

FIG. 5 is a block diagram showing another embodiment of the control circuit for a bolt tightening machine according to the present invention.
In the figure, the electric motor 3 and the electric motor 6 have armatures 3A, 6A and series field windings 3F, 6F, respectively, and are connected in series to thyristor circuits 15, 16, respectively, and are connected via a common switch 17. 37
It is connected to the. The configuration of the control circuit of the electric motor 3 is exactly the same as that of the electric motor 2 shown in FIG. Current limit setter 33 (current limit setter 3
3), a switch 36, a zero rotation detector 35, a gate cutoff circuit 28, and a phase control circuit 34. Now, as in the case of Figure 2,
When the switch 36 of the control circuit of the electric motor 6 is closed by the signal from the first comparator A, the electric motor 6 is started via the phase control circuit 34 and the thyristor circuit 16, and at the same time, the low-speed high-torque transmission section 8 is activated by the one-way clutch. 14, the rotation of the electric motor 6 is transmitted to the socket drive section 13, and tightening of bolts and nuts is started, and the current of the electric motor 6 increases. Further, the electric motor 6 tends to stop at the point where the output torque of the socket drive section 13 and the tightening torque of the bolt/nut are balanced, and the current of the electric motor 6 increases more and more. The current of this motor 6 is detected by a current detector 25,
The set current value taken out via the amplifier 26 and set in advance in the current limit setting device 33 and the second comparator B
The thyristor circuit 16 is controlled by the phase control circuit 34. As a result, the bolts and nuts are tightened, and when the current of the motor 6 reaches the current value set by the current limit setting device 33, the phase is restricted by the phase control circuit 34.
Therefore, the rotation of the electric motor 6 gradually decreases, and the rotation state of the electric motor 6 is detected by the zero rotation detector 35, and when the rotation of the electric motor 6 reaches almost zero rotation,
A signal is sent to the gate cutoff circuit 28 to energize the gate cutoff circuit 28, a stop signal from the gate cutoff circuit 28 is outputted to the phase control circuit 34, the gate of the thyristor circuit 16 is cut off, and the motor 6 is stopped. In this case, if the set current value of the current limit setting device 33 is set to a current value corresponding to the final tightening torque value of the bolt/nut, the bolt/nut can be properly tightened with the final tightening torque.

Note that an integrator is incorporated in the zero rotation detector 35 so that the zero rotation detector 35 does not operate at the moment the electric motor 6 is started.

FIG. 6 is a block diagram showing another embodiment of the control circuit for a bolt tightening machine according to the present invention.
In the figure, the electric motor 3 and the electric motor 6 have armatures 3A, 6A and series field windings 3F, 6F, respectively, and are connected in series to thyristor circuits 15, 16, respectively, and are connected via a common switch 17. 37
It is connected to the. The configuration of the control circuit of the electric motor 3 is exactly the same as that of the electric motor 3 shown in FIG. 4, and the configuration of the control circuit of the electric motor 6 is exactly the same as that of the electric motor 6 shown in FIG. When the zero rotation detector 32 of the control circuit of the electric motor 3 detects that the rotation of the electric motor 3 has reached almost zero rotation, this signal is output to the gate cutoff circuit 23, and at the same time, the control circuit of the electric motor 6 is activated. Forced. Other functions and effects are the same as in the case of the control circuit of the electric motor 3 and the case of FIG. 4, and the control circuit of the electric motor 6, respectively.

(Effects of the Invention) As described above, when the bolt tightening machine of the present invention is used, when the load is light, the bolts and nuts are rotated at high speed and low torque by the high speed and low torque electric motor, and the bolts and nuts are tightened. , the tightening torque of the bolts and nuts increases, and when this reaches the temporary tightening torque, the high-speed and low-torque motor current cutoff means automatically cuts off the current of the high-speed and low-torque motor.
At the same time, a low-speed, high-torque electric motor is operated via a one-way clutch to tighten bolts and nuts to the set final tightening torque at low speed and high torque, which not only saves energy but also tightens bolts and nuts.
Nuts can be correctly tightened with the set final tightening torque. In addition, since two electric motors, a high-speed, low-torque electric motor and a low-speed, high-torque electric motor, can be arbitrarily selected, the time required for tightening bolts and nuts using the torque method can be minimized.
Work efficiency improves. Further, since a friction clutch or the like is not used, there are no disadvantages caused by a friction clutch. Furthermore, since the output shaft of the low-speed, high-torque electric motor and the socket shaft are on the same axis, power transmission loss is reduced, so the electric motor can be made smaller than the conventional two-motor system, which has great effects.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of the mechanical structure of a bolt tightening machine according to the present invention, and FIGS. 2 to 6 are block diagrams each showing an embodiment of a control circuit for the bolt tightening machine according to the present invention. DESCRIPTION OF SYMBOLS 1... Bolt tightening machine, 2... Control device, 3... Series commutator motor for high speed and low torque, 4, 7... Reduction mechanism,
5... High speed low torque transmission section, 6... Low speed high torque series commutator motor, 8... Low speed high torque transmission section, 9...
Socket shaft, 10... Socket, 11, 12... Gear, 13... Socket drive section, 14... One-way clutch, 15, 16... Thyristor circuit, 18... Speed setting device, 19, 24... Soft start circuit, 20,
25...Current detector, 21, 26...Amplifier, 22...
Temporary tightening torque setting device, 23, 28... Gate cutoff circuit, 27... Final tightening torque setting device, 29... Dead band circuit, 30... Current limit setting device for temporary tightening torque, 3
1, 34... Phase control circuit, 32, 35... Zero rotation detector, 33... Current limit setting device for final tightening torque, A
...first comparator, B...second comparator.

Claims (1)

[Claims] 1. A high-speed, low-torque electric motor that tightens bolts and nuts to a temporary tightening torque at high speed and low torque during light loads; High-speed, low-torque motor current cutoff means outputs a signal to shut off the gate and operate the low-speed, high-torque electric motor; A low-speed, high-torque electric motor that tightens bolts and nuts to the final tightening torque with high torque; When the tightening torque of this low-speed, high-torque electric motor reaches a preset final tightening torque value, the low-speed, high-torque electric motor A bolt tightening machine comprising a low-speed, high-torque motor current interrupting means for interrupting a gate of a thyristor circuit. 2. The high-speed, low-torque motor current cutoff means compares the current of the high-speed, low-torque motor with the current value corresponding to the temporary tightening torque value set in the torque setting device, and when the two become equal, the low-speed, high-torque motor current is cut off. a comparator that outputs a signal to operate the motor; a gate cutoff circuit that is energized by the signal from this comparator and outputs a stop signal; and a phase that cuts off the gate of the thyristor circuit with the stop signal from this gate cutoff circuit. A bolt tightening machine according to claim 1, comprising a control circuit. 3. A zero rotation detector for detecting when the rotation of the high speed low torque electric motor reaches almost zero rotation and outputting a signal for operating the low speed high torque electric motor; Claim 1 comprising: a gate cutoff circuit that is energized by a signal from the zero rotation detector and outputs a stop signal; and a phase control circuit that cuts off the gate of the thyristor circuit with the stop signal from the gate cutoff circuit. Bolt tightening machine described in section. 4. The low-speed, high-torque motor current cutoff means compares the current of the low-speed, high-torque motor with the current value corresponding to the final tightening torque value set in the torque setting device, and outputs a signal when the two become equal. A claim consisting of a comparator; a gate cutoff circuit that is energized by a signal from the comparator and outputs a stop signal; and a phase control circuit that cuts off the gate of the thyristor circuit with the stop signal from the gate cutoff circuit. The bolt tightening machine described in item 1. 5. The low-speed, high-torque electric motor current interrupting means includes a zero-rotation detector that detects when the rotation of the low-speed, high-torque electric motor reaches almost zero rotation and outputs a signal; 2. The bolt tightening machine according to claim 1, comprising: a gate cutoff circuit that outputs a stop signal when the gate cutoff circuit is activated; and a phase control circuit that cuts off the gate of the thyristor circuit using the stop signal from the gate cutoff circuit.