JPS5917582Y2 - Impact wrench with torque control - Google Patents

Description

[Detailed description of the invention] This invention is an impact wrench with torque control that can control the tightening torque of bolts and nuts in an impact wrench that is driven by a series commutator motor (hereinafter abbreviated as the motor). It is related to.

Conventionally, when using an impact wrench to fasten assembled structures with bolts and nuts, the tightening torque of the bolts and nuts was controlled to manage the axial force of the bolts by adjusting the tightening torque to a predetermined value. A method is used in which each torsion bar is used, or a method in which the operating time of the impact wrench is controlled by a timer.

However, the former method requires preparing a heavy torsion bar for each tightening torque and replacing it in the socket each time the tightening torque changes, and the latter method requires the preparation of a heavy torsion bar for each tightening torque. Depending on the tightening condition of the bolts and nuts, the no-load time also enters the timer setting time.
There is a drawback that the tightening torque when bolts and nuts are completed varies depending on the state of the bolts and nuts at the time the timer operates.

The present invention eliminates the drawbacks of the method using a timer, allows the tightening torque of an impact wrench to be set easily and arbitrarily, and enables highly accurate control of the tightening torque of bolts and nuts. A controlled impact wrench is provided.

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

Fig. 1 is a cross-sectional front view of essential parts of an impact wrench with torque control according to an embodiment of the present invention, Fig. 2 is a cross-sectional view taken along line A-A in Fig. 1, and Fig. 3 is a front view of an impact wrench with torque control according to the present invention. Block Diagram of Tightening Torque Control Device FIG. 4 is a block diagram of a tightening torque control device for an impact wrench with torque control according to another embodiment of the present invention.

In FIGS. 1 to 4, the same numbers indicate the same members.

As shown in FIGS. 1 to 3, the main parts of the torque-controlled impact wrench 1 of the present invention include an electric motor 2, a reduction gear mechanism 3, a striking mechanism 4, a drive shaft 5, and a socket for tightening bolts and nuts. 6 and a tightening torque control device 7.

The electric motor 2 was attached to a casing 9 with bolts 8, and a start/stop switch 10 and a cable 10a for connection to an external power source (not shown) or a tightening torque control device 7 were attached to the electric motor 2. A bundle 11 is provided.

The reduction gear mechanism 3 includes a sun gear 13 attached to the shaft end of the output shaft 12 of the electric motor 2 , a plurality of planetary gears 14 that mesh with the sun gear 13 and rotate and revolve around the sun, and the planetary gears 1
The output shaft 17 is connected to an internal gear 15 fixed to the casing 9 and the rotation shaft 16 of the planetary gear 14, and rotates as the planetary gear 14 revolves.

Therefore, the rotation of the output shaft 12 of the electric motor 2 is decelerated and transmitted to the output shaft 17, and the output shaft 17 is transmitted to the output shaft 1 of the electric motor 2.
Rotates in the same direction as 2.

In this embodiment, the planetary gear mechanism is used as the reduction gear mechanism as described above, but this may be used only as a normal reduction gear train or in combination with a planetary gear mechanism and a normal reduction gear train.

The striking mechanism 4 includes a camshaft 18 provided below the output shaft 17 of the reduction gear mechanism 3, a striking element 19, a steel ball 20, and an elastic body 21 such as a spring.

A pair of helical grooves 22 having a predetermined slope are symmetrically provided on the outer peripheral surface of the camshaft 18 .

Further, a projection 23 is provided at the lower end of the camshaft 18, and the projection 23 is loosely fitted into a recess 24 provided at the center of the upper end surface of the drive shaft 5.

The striker 19 has a hollow shape and is slidable in the axial direction on the camshaft 18.
It is loosely fitted.

Further, a torsion groove 25 having a predetermined inclination is provided on the inner circumferential surface of the striker 19, facing the pair of twist grooves 22 of the shaft 18, and a pair of symmetrical protrusions is provided at the lower end of the striker 19. A child 26 is provided.

An elastic body 21 such as a spring is provided between the camshaft 18 and the striker 19.
is provided, and the striking element 19 is normally pressed against the drive shaft 5.
The protrusion 26 of the striker 19 and the engaging portion 5a of the drive shaft 5 are made to engage with each other.

A pair of steel balls 20 are fitted between a pair of helical grooves 22 of the camshaft 18 and a pair of helical grooves 25 of the striker 19.

This steel ball 20 transmits the rotational force of the camshaft 18 to the striker 19, and when the load applied to the drive shaft 5 reaches a predetermined value, the steel ball 20 along with the striker 19 elastically moves along the torsion groove 22 of the camshaft 18. It rolls upward against the force of the body 21, releases the engagement between the drive shaft 5 and the striker 19, and as the striker 19 moves toward the drive shaft 5 due to the repulsive force of the elastic body 21, It rolls downward along the torsion groove 22, engages the protrusion 26 of the striker 19 with the engagement portion 5a of the drive shaft 5, and applies striking rotational force to the drive shaft 5.

A light shielding part 19a is provided at the upper end of the striker 19, and each time the striker 19 moves upward, the light shielding part 19a
blocks the light from a photointerrupter 39 of a hitting start time detection device 35, which will be described later, and converts the number of hits of the striking element 19 into an electric pulse signal.

The drive shaft 5 is rotatably supported by a bearing 27 fixed to the casing 9, and is removably engaged with a protrusion 26 of the striking element 19 at a retaining portion 5a provided at the upper part.

Further, a socket 6 is attached to the lower end of the drive shaft 5 via a pin 28 and an O-ring 29 for preventing the pin 28 from coming off, and when the drive shaft 5 is engaged with the striker 19, the camshaft The rotational force is transmitted from 18 to the socket 6 via the striker 19.

An oil seal 30 is provided adjacent to the lower end of the bearing 27 between the drive shaft 5 and the casing 9 to prevent dust from entering the machine body from outside and to prevent lubricating oil from entering the machine body. This is to prevent leakage.

Moreover, between the engaging portion 5a of the drive shaft 5 and the casing 9,
A sliding plate 31 is provided to receive the thrust applied to the drive shaft 5.

As shown in FIG. 3, the tightening torque control device 7 includes a thyristor circuit 32, a speed setting device 33, a phase control circuit 34, a photointerrupter 39 of a striking start point detection device 35, a timer 36, a timer setting device 37, and a gate. Breaking circuit 3
The thyristor circuit 32 is connected in series with the armature 2A of the motor 2, the series field winding 2F, and the switch 10, and is connected to an external power source via the switch 10.

As shown in FIGS. 1 and 2, the impact start point detection device 35 includes three photo interrupters, a mounting base 40, and a lead wire 4.
1 and cover 42.

The photo ink bumper 39 is made up of a light emitting diode 43 and a phototransistor 44, and as described above, the light shielding portion 19a of the striker 19 of the striking mechanism 4 causes the light emitting diode 43 to switch between the light emitting diode 43 and the phototransistor each time the striker 19 hits. It blocks the light sent to the phototransistor 44 and converts the number of strikes of the striker 19 into an electric pulse signal, and supplies power to the light emitting diode 43 and transmits the electric pulse signal from the phototransistor 44 to the timer 36. , and the Hinode Line 41.

The photo interrupter 39 is attached to the casing 9 by bolts 45.
A mounting base 40 fixed to a cover 42 attached by
It is attached to the casing 9 through the hole 46 provided in the casing 9, and is arranged so as to have the above-mentioned relationship with the light shielding part 19a of the striking element 19.

Now, in the tightening torque control device 7, when the switch 10 is turned on, the phase control circuit 34 is energized, the electric motor 2 is started via the thyristor circuit 32, and its rotation speed is set to the rotation speed set in the speed setting device 33. gradually rises to a number.

Next, the timer 36 is activated by the first electric pulse signal transmitted from the photointerrupter 39 of the striking start point detection device 35 to the timer 36, and the operation time of the timer 36 is the same as the time set in advance in the timer setting device 37. When they match and become equal, a stop signal for the motor 2 is sent to the gate cutoff circuit 38, the gate cutoff circuit 38 is energized, and the gate of the thyristor circuit 32 is turned on by the gate cutoff signal from the gate cutoff circuit 38. The electric motor 2 is cut off and the electric motor 2 is stopped.

This tightening torque control device 7 may be incorporated into the impact wrench body of the impact wrench 1 with torque control, or
It may be provided separately from the impact wrench body.

Next, the operation of the impact wrench with torque control 1 having the above configuration will be explained.

FIG. 1 shows a case where the striking member 19 of the striking mechanism 4 and the engaging portion 5a of the drive shaft 5 are engaged.

Now, connect the cable 10a to the external power supply, set the predetermined rotation speed of the motor 2 to the speed setter 33, and set the predetermined rotation speed of the motor 2 to the speed setter 33.
7, set the operating time of the striking mechanism 4 corresponding to the allowable tightening torque of the bolt to be tightened, fit the socket 6 to the bolt/nut to be tightened, and turn on the switch 10, the phase control circuit 34 is energized. The electric motor 2 is started via the thyristor circuit 32, and its rotation is controlled by the speed setting device 33.
The rotation speed will gradually increase to the set speed.

The rotation of the electric motor 2 is decelerated by the reduction gear mechanism 3 from the output shaft 12, and is transmitted from the output shaft 17 of the reduction gear mechanism 3 to the camshaft 18 of the striking mechanism 4.

The rotation of the camshaft 18 is caused by the steel ball 20, the striking element 19, and the striking element 1.
The rotation is transmitted to the drive shaft 5 through the protrusion 26 of 9 and the engaging portion 5a of the drive shaft 5, and rotates the bolt/nut fitted in the socket 6 attached to the lower end of the drive shaft 5.

The bolt/nut rotates and descends from its free state,
When the steel ball 20 comes into contact with the object to be fastened and approaches the restrained state, the steel ball 20 moves upward along the torsion groove 22 of the camshaft 18 against the force of the elastic body 21, so that it engages with the steel ball 20. When the striking element 19 also rotates and moves upward together with the steel ball 20, the engagement between the striking element 19 and the drive shaft 5 is released, and the striking element 19
The rotational force is no longer transmitted to the drive shaft 5.

At this time, the light blocking portion 19a of the striking element 19 blocks the light from the photointerrupter 39 of the striking start time detection device 35.

In this state, due to the repulsive force of the elastic body 21, the striking element 19 rotates again and moves downward via the steel ball 20, returns to its original state, and applies a striking rotational force to the drive shaft 5.

At this time, the light blocking portion 19a of the striking element 19 no longer blocks the light from the photointerrupter 39 of the striking start point detection device 35, so the photointerrupter 39 returns to its original state and the first electric pulse signal is sent to the timer 36. The timer 36 is transmitted and the timer 36 is activated.

As described above, the impact mechanism 4 tightens the bolts and nuts while repeatedly applying impact rotational force to the bolts and nuts via the drive shaft 5 and the socket 6, and the operating time is determined via the timer 36. When the set time is compared with the set time set in the timer setter 37 and the two become equal,
A stop signal for the electric motor 2 is sent to the gate cutoff circuit 38,
The thyristor circuit 32 is gated off to stop the electric motor 2, the bolt/nut tightening is completed, and it is possible to move on to the next bolt/nut tightening work.

FIG. 4 is a block diagram showing a tightening torque control device 7' for an impact wrench 1' with torque control according to another embodiment of the present invention.

The main part of the impact wrench 1' with torque control is the electric motor 2.
, reduction gear mechanism 3, impact mechanism 4, drive shaft 5, socket 6
and a tightening torque control device 7', and the tightening torque control device 7 of the impact wrench 1 with torque control shown in FIG. 1 is replaced with a tightening torque control device 7'.

Therefore, the mechanical part of the impact wrench 1' with torque control is the same as the impact wrench 1 with torque control shown in FIG. It is exactly the same as Impact Wrench 1.

As shown in FIG. 4, the torque control device 7' includes a thyristor circuit 32, a speed setting device 33, a phase control circuit 34, a striking start point detection device 35', a timer 36, a timer setting device 37, and a gate cutoff circuit 38. The thyristor circuit 32 is composed of the armature 2A of the motor 2 and the series field winding 2F.
, a current detector 47 of a striking start point detection device 35', which will be described later.
and a switch 10, and are connected to an external power source via the switch 10.

The striking start point detection device 35' consists of a current detector 47, a dead band circuit 48, an amplifier 49, and a current setting device 50,
The current of the motor 2 detected by the current detector 47 is taken out via the amplifier 49, and compared with the set current value set in the current setting device 50. When the two become equal, a signal is emitted, and the signal is sent to the timer 36. to be transmitted.

Note that a dead band circuit 48 is provided to prevent the current detected by the current detector 47 from matching the set current value of the current setting device 50 for a certain period of time after the motor 2 is started.

Now, in the tightening torque control device 7', the switch 10 is
When the motor 2 is turned on, the phase control circuit 34 is energized, the electric motor 2 is started via the thyristor circuit 32, and its rotational speed gradually increases to the rotational speed set in the speed setting device 33.

Next, when the current detected by the current detector 47 becomes equal to the set current value set in the current setting device 50, the timer 36 is activated by a signal from the striking start point detection device 35'. The time is compared with a set time set in advance in the timer setter 37, and when the two become equal, a stop signal for the motor 2 is sent to the gate cutoff circuit 38, and the gate cutoff circuit 38 is energized.
In response to a gate cutoff signal from the gate cutoff circuit 38, the gate of the thyristor circuit 32 is cut off and the motor 2 is stopped.

This tightening torque control device 7' may be incorporated into the impact wrench body of the impact wrench 1' with torque control, or may be provided separately from the impact wrench body.

Next, the operation of the impact wrench with torque control 1' having the above configuration will be explained.

1 and 4, the cable 10a is connected to an external power source, the speed setter 33 is set to a predetermined rotational speed of the electric motor 2, and the timer setter 37 is set to a striking mechanism corresponding to the allowable tightening torque of the bolt to be tightened. 4, the current setting device 50 is set to a current value slightly higher than the no-load current of the motor 2.

After that, when the socket 6 is fitted to the bolt/nut to be tightened and the switch 10 is turned on, the phase control circuit 34 is energized, the motor 2 is started via the thyristor circuit 32, and its rotation is controlled by the speed setting device. The rotation speed gradually increases to the set speed of 33.

The rotation of the electric motor 2 is decelerated by the reduction gear mechanism 3 from the output shaft 12 and transmitted from the output shaft 17 of the reduction gear mechanism 3 to the camshaft 18 of the striking mechanism 4.

The rotation of the camshaft 18 is caused by the steel ball 20, the striking element 19, and the striking element 1.
The drive shaft 5 is connected to the drive shaft 5 through the protrusion 26 of No.
is transmitted to rotate the bolt nut I fitted in the socket 6 attached to the lower end of the drive shaft 5.

The bolt/nut rotates and descends from its free state,
When the steel ball 20 comes into contact with the object to be fastened and approaches the restrained state, the steel ball 20 moves upward along the torsion groove 22 of the camshaft 18 against the force of the elastic body 21, so that it engages with the steel ball 20. When the striking element 19 also rotates and moves upward together with the steel ball 20, the engagement between the striking element 19 and the drive shaft 5 is released, and the striking element 19
The rotational force is no longer transmitted to the drive shaft 5.

In this state, due to the repulsive force of the elastic body 21, the striking element 19 rotates again and moves downward via the steel ball 20, returns to its original state, and applies a striking rotational force to the drive shaft 5.

In this manner, when the bolt or nut to be tightened approaches the locked state, the torque-controlled impact wrench 1' starts to perform a striking action, and the load current of the motor 2 increases beyond the no-load current.

This load current is taken out via the amplifier 49 and compared with the set current value set in the current setting device 50. When the two are equal, a signal is transmitted to the timer, and the timer 36
make it work.

As described above, the impact mechanism 4 tightens the bolts and nuts while repeatedly applying impact rotational force to the bolts and nuts via the drive shaft 5 and the socket 6, and the operating time is determined via the timer 36. , when the set time set in the timer setter 37 is compared with the set time, and when the two become equal,
A stop signal for the electric motor 2 is sent to the gate cutoff circuit 38,
The thyristor circuit 32 is gated off to stop the electric motor 2, the bolt/nut tightening is completed, and the next bolt/nut tightening work can be started.

As described above, the impact wrench with torque control of the present invention allows you to replace the I-version bar every time you change the tightening torque, unlike the conventional method of controlling the tightening torque using a torsion bar. There is no need to prepare several types of heavy torsion bars.

In addition, the impact wrench with torque control of the present invention operates a timer by detecting the start point of the impact of the impact mechanism, so the timer operates like a conventional method that uses a timer to control tightening torque. The tightening torque does not vary depending on the initial condition of the bolts and nuts.

In addition, in the impact wrench with torque control of the present invention, the relationship between the bolt tightening torque allowed by the bolt dimensions, material, etc. and the impact time of the impact mechanism is determined in advance, and the impact time is set in the timer setting device. This allows you to easily and arbitrarily set the tightening torque, and automatically detects the start point of the striking mechanism, operates the timer, and sets the operating time of the striking mechanism to the timer setting device via the timer. It matches the set time and when the two become equal, it automatically stops the motor and completes the tightening of bolts and nuts, making it very easy to operate and with high accuracy of bolts and nuts. Tightening torque can be managed.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional front view of essential parts of an embodiment of the present invention, Fig. 2 is a cross-sectional view taken along line A-A in Fig. 1, Fig. 3 is a block diagram of the tightening torque control device, and Fig. 4 is the main part of the present invention. FIG. 3 is a block diagram of another embodiment of the invention; 1.1'...impact wrench with torque control, 2...
・Series commutator motor, 3... Reduction gear mechanism, 4...
Impact mechanism, 5... Drive shaft, 6... Socket, 7, 7
'...Tightening torque control device, 10...Switch, 1
7... Output shaft, 18... Camshaft, 19... Striker, 19a... Light shielding part, 20... Steel ball, 21... Elastic body, 22.25... Twisting Groove, 32... Thyristor circuit, 33... Speed setting device, 34... Phase control circuit, 35.35'... Hitting start point detection device, 36.
...Timer, 37...Timer setting device, 38...
Gate cutoff circuit, 39...f 1st interrupter, 4
7... Current detector, 48... Dead band circuit, 49...
・Amplifier, 50...Current setting device.

Claims (3)

[Scope of utility model registration request] (1) In an impact wrench driven by a series-wound commutator electric motor, a striking start time detection means for detecting the start time of a strike of a striker of a striking mechanism, and a timer that operates according to a signal from the striking start time detection means; a time setting device for setting the operating time of the striking mechanism; and a current interrupting means for cutting off the current of the series-wound commutator motor when the operating time of the timer becomes equal to the time set in the time setting device. An impact wrench with torque control. (2) The striking start point detection means uses a light shielding part provided on the striker of the striking mechanism and movement of the light shielding part in the axial direction.
An impact wrench with torque control according to claim 1, which is a striking start point detecting device which is a striking start point detection device that is operated by a photo-interrupter that emits an electric pulse signal by blocking and passing light. (3) The impact start point detection means includes a current detector that detects the current of the series commutator motor, a current setting device, and an amplifier;
a matching means that matches the detected current of the current detector taken out via the amplifier with a set current value set in the current setting device and issues a signal when both become equal; and the series commutator motor. An impact wrench with torque control according to claim 1, which is a striking start point detection device comprising a dead band circuit for a starting current.