JPS6057997B2 - Electric bolt tightening machine for shear bolts - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electric bolt tightening machine that can efficiently temporarily tighten shear bolts.

A shear bolt is a bolt that has a threaded part (tip), and when a torque exceeding a predetermined value is applied, the tip breaks off and the member is tightened with a predetermined torque.Due to the characteristics of the bolt, it can be tightened using the torque method.

FIG. 1 is a cross-sectional view showing how this shear bolt is tightened, in which reference numeral 1 indicates an object to be fastened, 2 indicates a shear bolt, and 3 indicates a nut.

The shear bolt 2 has a tip 4 at its tip. 5
is an outer socket which engages with the nut 3.

6 is an isoazoget, and this isoazoget 6 is located within the outer socket 5 and engages with the chip 4.

Reference numeral 7 is a pin for ejecting the chips 4, and has the function of ejecting the chips 4 remaining in the isoazoget 6 after the final tightening is completed.

Such a shear bolt 2 tightening machine is made so that the tightening reaction force of the outer socket 5 is applied to the isoazoget 6, and when a predetermined tightening torque is reached during final tightening, the tip 4
is sheared from its roots.

As a result, the tightening torque during final tightening becomes constant. However, if this shear bolt 2 is temporarily tightened, that is, if the motor is stopped before the tip 4 is screwed off, since the connections are strong between the outer socket 5 and the nut 3 and between the isoazoget 6 and the tip 4, It becomes difficult to remove the tightening machine.

In particular, in shear bolts, the diameter of the isoazoget that receives the tightening reaction force becomes smaller, so the force applied between the tip and the isoazoget becomes extremely large, and the tip and the isoazoget are tightly engaged. For this reason, when a tightening reaction force is applied to the outside of the outer socket like in a normal bolt tightening machine, the engagement between the bolt and the tightening machine becomes stiff. As a result, when shear bolts are used, temporary tightening work cannot be performed using conventional bolt tightening machines for shear bolts. Temporary tightening of bolts is essential for adjusting the hadas between each member, especially in construction-related work and bridge-related work, and until now, ordinary bolt tightening machines without inner sockets have been used was used for temporary tightening.

For this reason, there was a problem in that separate tightening machines had to be prepared for temporary tightening and final tightening. This invention was made in view of these circumstances, and it is possible to temporarily tighten and permanently tighten shear bolts with one machine, and in addition, during temporary tightening, it is extremely easy to use the tightening machine after the temporary tightening is completed. An object of the present invention is to provide an electric bolt tightening machine for shear bolts that can be removed from bolts and nuts.

According to the present invention, this purpose is to develop an electric shear bolt using a series-wound commutator motor in which the tightening reaction force of an out socket that engages with a nut is received by an inner socket that engages with a tip at the tip of the shear bolt. A type bolt tightening machine is provided with a main tightening means, a temporary tightening means, and a final tightening/temporary tightening switching means for switching between these two means, and the temporary tightening means is used when a motor current reaches a temporary tightening setting value. a torque detecting means for detecting this, a means for cutting off the motor current based on the output of the torque detecting means and terminating the temporary tightening operation, and an energizing direction of either the field or armature of the motor. forward/reverse switching means for switching between the forward and reverse rotations; and a reversal control means for outputting an output to the forward/reverse switching means based on the output of the torque detecting means to reverse the motor for a predetermined period of time; This is accomplished by an electric bolt tightening machine for shear bolts, which is characterized in that, while the electric motor is rotated in the reverse direction, the main tightening means rotates the electric motor in the normal direction regardless of the output of the torque detection means.

The present invention will be explained below based on the drawings. In the figure, reference numeral 10 is an AC power supply, 11 is a trigger switch, 12 and 1
3 is a field and an armature forming a series commutator motor.

Note that this motor is an AC/DC motor. First, the temporary tightening means will be explained.

The temporary tightening means includes means 62 for temporarily tightening (normal rotation) the electric motor;
61, a torque detection circuit 20 for detecting that the motor current has reached the temporary tightening setting value, a gate cutoff circuit 63 for stopping the temporary tightening by this torque detection circuit 20, and a field 12.
The motor is provided with a forward/reverse switching circuit 30 for switching the energization direction of the motor, and a reversal control circuit 40 for outputting the output to the forward/reverse switching circuit 30 based on the output of the torque detection circuit 20 to reverse the motor for a predetermined short period of time. The torque detection circuit 20 includes a shunt resistor 21 connected in series to the armature 13;
It includes an amplifier 22 that amplifies the voltage change of the shunt resistor 21 corresponding to the armature current, a timer 23, a comparator 24, and a torque setting device 25.

The timer 23 is used to send the output of the amplifier 22 to the comparator 24 after a certain period of time has elapsed since the trigger switch 11 is turned on.The timer 23 is used to send the output of the amplifier 22 to the comparator 24 after a certain period of time has elapsed since the trigger switch 11 is turned on. It has the effect of preventing The torque setter 25 sends a voltage corresponding to the pre-tightening setting torque at the end of the pre-tightening to the comparator 24. Comparator 2
4 compares the output voltage of the timer 23 and the set voltage of the torque setting device 25 and outputs an on signal when the former becomes larger than the latter, and then outputs an on signal until the trigger switch 11 is turned off. Continue outputting. Note that in a series commutator motor, the armature current is approximately proportional to the tightening torque, so as the tightening torque increases as the nut is tightened, the armature current also gradually increases and is input to the comparator 24. The output voltage of the timer 23 also gradually increases. The forward/reverse switching circuit 30 includes parallel thyristors 31 and 32 whose cathodes are connected to the armature 13, and a thyristor 33 which is connected in series to the anode of one of the thyristors 31.

The anode of this thyristor 33 is connected to the trigger switch 1.
1 and a thyristor circuit 60 described later.
Further, the anode of the thyristor 32 is similarly connected to the cathode side of the thyristor circuit 60. Reference numerals 50 and 51 indicate final tightening and temporary tightening changeover switches that operate in conjunction with each other, and the switches 50 and 51 are normally returned to connect both ends of the field 12 to the anodes of the thyristors 31 and 32, respectively.

In addition, in Fig. 2, when the motor rotates in the normal direction, the thyristor 31
However, when the rotation is reversed, the thyristors 32 and 33 are turned on. The reversal control circuit 40 reverses the motor for a predetermined short time based on the ON signal of the comparator 24.
A gate signal is sent to the forward/reverse switching circuit 30.

That is, in a state where there is no ON signal from the comparator 24, in other words, in a state where temporary tightening is in progress, this reversal control circuit 40 operates as follows.
A gate signal is sent to the gate of the forward rotation thyristor 31 to turn on only the forward rotation thyristor 31, and when there is an ON signal from the comparator 24, the reverse rotation thyristor 32,
Send a gate signal to these gates to turn on 33. Note that this reversal control circuit 30 is a thyristor 3.
The gate signals sent to 2 and 33 are of a very short duration and have a rotation angle sufficient to release the jamming between the outer socket 5 and the nut 3 and between the inner socket 6 and the tip 4 in FIG. It is designed to reverse the electric motor only. After that, no gate signals are output, all thyristors 31, 32, and 33 are turned off, and the motor stops rotating. 60 is a thyristor circuit for temporarily tightening operation control, and is interposed between the trigger switch 11 and the anode of the thyristor 32.

This thyristor circuit 60 is phase-controlled by a gate signal output from a phase control circuit 61, and guides only the positive half wave of the AC power source 10 to the motor with a conduction rate determined by the gate signal. Reference numeral 62 denotes a speed setting device, and this speed setting device 62 inputs a constant voltage to a phase control circuit 61, and this phase control circuit 61 controls the conduction rate, which changes in accordance with the set voltage of this speed setting device 62. Outputs gate signal.

Therefore, by changing the set voltage of this speed setting device, the voltage applied to the electric motor can be changed, and the rotational speed of the electric motor during temporary tightening can be adjusted. Reference numeral 63 denotes a gate cutoff circuit, which stops the operation of the phase control circuit 61 based on the ON signal of the comparator 24, and brings the thyristor circuit 60 into a cutoff state.

Next, the main tightening means will be explained.

The final tightening means is the aforementioned final tightening/temporary tightening changeover switch 50, 51.
Consisted of. The changeover switches 50 and 51 are connected to disconnect the field 12 and the anodes of the thyristors 30 and 31 and apply the voltage of the AC power supply 10 directly to the direct circuit of the field 12 and armature 13. ing.
At this time, it goes without saying that a voltage is applied to the field 12 in the direction in which the armature rotates in the normal direction. Next, the operation of this embodiment will be explained.

The process of cleaning and temporarily tightening will be explained. trigger switch 1
1 is turned on, the speed setting device 6 is output from the phase control circuit 61.
A gate signal having a conduction rate corresponding to the pre-tightening speed set by 2 is sent to the thyristor circuit 60. On the other hand, since the forward rotation thyristor 31 is turned on, current flows through the field 12 in the direction of the solid line arrow in the figure, causing the motor to rotate forward. Since the motor is stopped before the trigger switch 11 is turned on, the back electromotive force of the armature is zero, and therefore a large current flows at the moment the trigger switch 11 is turned on. However, due to the action of the timer 23, the comparator 24 does not output an on signal depending on this input current. When the electric motor is started and temporary tightening progresses, and the armature current corresponds to the temporary tightening setting torque, the comparator 24 outputs an on signal. Therefore, the phase control circuit 61 stops generating the gate signal, and the thyristor circuit 60 becomes cut off. On the other hand, the reverse rotation control circuit 40 stops generating the gate signal to the forward rotation thyristor 31, and sends a gate signal to the reverse rotation thyristors 32 and 33 for a short time to fire them. As a result, a current flows through the field 12 for a short time in the direction of the broken line arrow in the figure, and the motor reverses direction for a short time and then stops. In this state, outer socket 5 and nut 3
The engagement between the inner socket 6 and the tip 4 is loosened, and the tightening machine body can be easily removed from the nut 3 and the tip 4. When performing final tightening next time, after setting the inner socket 6J and outer socket 5 to the state shown in FIG. The electric motor rotates in the normal direction with a large torque, and the tip 4 of the shear bolt 2 is finally sheared, completing the tightening process.

In the embodiment described above, when the temporary tightening is completed, the AC power supply 1
The voltage of The speed can be regulated and the reverse rotation angle can be easily adjusted.

It goes without saying that the same effect can be obtained by connecting a series resistor to the reversing thyristors 32, 33 instead of controlling the phase of the reversing thyristors 32, 33.
Further, in this embodiment, the final tightening/temporary tightening changeover switches 50 and 51 are used as the final tightening means, and the alternating current from the AC power source 10 is directly applied to the motor. The desired effect can also be obtained by stopping the operation of the motor 63 and operating the phase control circuit 61 regardless of the output of the torque detection circuit 20 to rotate the electric motor in the normal direction.

It is also obvious that a slight delay circuit is provided between the signal of the comparator 24 and the reversal control circuit 40 to ensure control when necessary. Also omit timer 23 and use 6 instead.
It is also obvious that a cushion start circuit can be provided between 1 and 62 to keep the current low when the trigger switch 11 is turned on, thereby eliminating malfunctions of the torque detection circuit 20. As described above, this invention is configured to automatically reverse the motor for a short period of time at the end of temporary tightening. The engagement is released and the tightening machine body can be removed from the bolts and nuts very easily.

Therefore, the efficiency of temporary tightening work is significantly improved. Furthermore, since the present invention allows switching between the temporary tightening means and the final tightening means, one tightening machine can perform both final tightening and temporary tightening, which further improves work efficiency and is economical.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing how a shear bolt is tightened, and FIG. 2 is a circuit diagram showing an embodiment of the present invention. 12... Field, 13... Armature, 20... Torque detection circuit, 30... Forward/reverse switching circuit, 40... Reverse rotation control circuit, 50, 51... Final tightening, temporary closing. exchange switch.

Claims (1)

[Claims] 1. An electric bolt tightening machine for shear bolts that uses a series commutator motor and receives the tightening reaction force of an outer socket that engages a nut with an inner socket that engages a tip at the tip of a shear bolt, The temporary tightening means includes a final tightening means, a temporary tightening means, and a final tightening/temporary tightening switching means for switching between these two means, and the temporary tightening means has a torque detection means for detecting that the motor current has reached the temporary tightening set value. a means for cutting off the motor current based on the output of the torque detecting means to terminate the temporary tightening operation; and a forward/reverse switching means for switching the current direction of either the field of the motor or the armature. , a reverse rotation control means for outputting an output to the forward/reverse switching means based on the output of the torque detecting means to reverse the electric motor for a predetermined period of time, and the temporary tightening means reverse the electric motor for a predetermined period of time after completion of temporary tightening. On the other hand, the electric bolt tightening machine for shear bolts is characterized in that the main tightening means rotates the electric motor in the normal direction regardless of the output of the torque detection means.