JPH0244673B2 - INPAKUTORENCHINIOKERUDAGEKIKAITENSOCHI - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in the impact rotation device of an impact wrench used for tightening and loosening bolts, nuts, etc.

The impact wrench currently in use has a hammer part on a part of the rotating body connected to the rotor shaft, and when this rotating body is rotated by the rotor around the anvil, a cam action etc. is generated just before the impact point. The method forcibly and rapidly changes the attitude of the hammer to engage the hammer with the abutment surface of the anvil. Not only is this movement difficult to design because it occurs in an instant during high-speed movement just before striking, and the change in attitude of the hammer includes a free jump movement, but it is also difficult to perform this movement even within the tolerances of the manufactured parts. Variations are likely to occur, and even slight wear of parts can have a large effect on the effect of impact engagement. For this reason, conventional impact wrenches have had drawbacks such as insufficient tightening precision of screws, and early wear and tear of major parts.

In order to eliminate this problem, the applicant of the present invention has developed a hammerless method, in which the anvil piece is kept in sliding contact with the inner circumferential surface of the rotating cylinder in an inclined state against the spring force. A device held in a lockable position by a protrusion protruding from the inner circumferential surface (Japanese Unexamined Patent Publication No. 57
According to this device, a large spring force is applied just before the anvil piece comes into contact with the side surface of the protrusion, so there is a friction loss between it and the rotating cylindrical body. As a result, it was disadvantageous to be sufficiently accelerated by the rotor and to accumulate larger kinetic energy. In addition, when the anvil piece assumes a tilted position, the spring force is large, so a large motor torque is required, giving the worker a large reactionary force.
Moreover, at the moment when the anvil piece releases its sliding contact from the inner circumferential surface of the rotating cylindrical body and comes into contact with the protrusion, it rotates slightly due to the spring force, reducing the contact area with the protrusion, resulting in irregular contact. It was a mistake to generate a large impact rotational force.

In order to eliminate these drawbacks, the present invention reduces the spring force when the anvil piece slides on the inner circumferential surface of the rotating cylinder, and applies a large spring force when the anvil piece locks onto the protrusion of the rotating cylinder. The present invention provides an impact rotation device for an impact wrench that is adapted to act.

Embodiments of the present invention will be explained with reference to the drawings: 1
1 is a casing provided with a handle 2, and as is well known, compressed air supplied from the outside is allowed to flow in through an inlet (not shown) to operate an operating lever 3 and a switching valve (not shown). Accordingly, the air motor 4 provided in the rear part of the casing 1 is configured to rotate at high speed in the left or right direction.

Reference numeral 5 denotes a rotating cylindrical body in which the center of the circular rear wall 5b is spline-fitted to the tip of the rotor shaft 6 of the air motor 4 so that it rotates integrally with the rotor shaft 6. The inner peripheral surface 5a is formed into a perfect circular surface, and locking protrusions 7 are integrally formed in the lengthwise direction at appropriate positions on the inner peripheral surface 5a, and project from the inner peripheral surface in the radial direction. Inner peripheral surface 5
Arc-shaped grooves 8a, 8 recessed in the outer radial direction than a
b has been deleted.

Reference numeral 9 denotes the arc-shaped groove 8 on the inner circumferential surface of the front end of the rotating cylindrical body 5 by removing the locking protrusion 7.
This is a guide groove that communicates between the outer end portions of a and 8b, or between the outer end portions of the guide grooves a and 8b.

Reference numeral 10 denotes an anvil which is rotatably supported at the front end of the casing 1, and its tip protruding forward from the casing 1 is formed into a mounting angle shaft 10a of a socket body (not shown) for fitting a bolt or nut, etc. The anvil body 10b inserted into the rotating cylindrical body 5 is formed to have a large diameter, and the shaft portion 11 protruding from the center of the rear end face is connected to the circular rear wall portion 5b of the rotating cylindrical body 5.
It is rotatably fitted into the center hole of the

Reference numeral 12 denotes a support groove having a semicircular cross section carved in the outer peripheral surface of the anvil body 10b in the length direction, and supports the anvil piece 13 so as to be rotatable in the left and right direction.

This anvil piece 13 is formed into a semicircular columnar cross section having the same diameter as the radius of curvature of the arcuate grooves 8a and 8b provided in the rotating cylindrical body 5, and its semicircular outer peripheral surface is in sliding contact with the support groove 12. When the straight line connecting the outer corner portions 13a and 13b is perpendicular to the diameter line of the rotating cylindrical body 5 passing through the center of the anvil piece 13, the outer surface 13c
is positioned further inward than the locking protrusion 7 of the rotating cylindrical body 5. Furthermore, a chevron-shaped protuberance 14 is provided at the center of the outer surface of the front end of the anvil piece 13 and protrudes in the outer radial direction. be.
When the chevron-shaped protrusion 14 passes through the guide groove 9, the anvil piece 13 is brought into sliding contact with the inner circumferential surface 5a of the rotary cylindrical body 5 by bringing its tip and either one of the outer end corner portions 13a or 13b into sliding contact. The side surface of the outer end corner portion 13a or 13b in sliding contact with the rotating cylindrical body 5 is brought into an inclined state.
The locking projection 7 is brought into contact with one side surface 7a or 7b of the locking projection 7.

Reference numeral 15 denotes a hole extending radially through the center of the bottom of the support groove 12 of the anvil body 10b, in which an anvil piece pressing member 16 and a spring receiving member 17 are slidably housed.

The anvil piece pressing member 16 has a concave arc shape in which a pressing protrusion 16b is integrally provided at the center of the outer surface of a flange 16a that slides into the hole 15, and the pressing protrusion 16b is cut out in the width direction at the center of the bottom surface of the anvil piece 13. The collar portion 16a is in sliding contact with the concave arc-shaped bottom surface 19 of the groove 18.
A guide shaft portion 16c is provided protruding from the center toward the spring receiving member 17.

Further, the spring receiving member 17 is integrally provided with a cylindrical portion 17b into which the guide shaft portion 16c of the anvil piece pressing member 16 is slidably fitted to the collar portion 17a which is in sliding contact with the hole 15, and also extends through the hole 15. A protruding shaft portion 17c is provided in a manner that slides on the inner circumferential surface of the rotating cylindrical body 5.

The inner circumferential surface of the rotating cylindrical body 5 with which the protruding shaft portion 17c comes into sliding contact is formed by a large-diameter inner circumferential cam surface 20 having a circumferential groove shape and a portion of the cam surface 20 protruding toward a small diameter, that is, in the inner diameter direction. This small-diameter cam surface 21 is provided facing the locking projection 7, and its circumference is such that both sides of the anvil piece 13 are similar to the locking projection 7.
This is the length between the positions of the protruding shaft portion 17c when it abuts both side surfaces of the shaft.

A coil spring 22 is press-fitted between the facing surfaces of the flange 16a of the anvil piece pressing member 16 and the flange 17a of the spring receiving member 17.

To describe the operation of the embodiment configured as described above, when the operating lever 3 and the switching valve are operated to rotate the air motor 4 clockwise, the rotating cylindrical body 5 fitted on the rotor shaft 6 is rotated from the anvil. Rotate clockwise relative to the piece 13 as shown in FIG.

At this time, the anvil piece 13 has its chevron-shaped protrusion 14
and one (left) outer end corner 13a are in an inclined state with their tips slidingly in contact with the inner circumferential surface 5a of the rotating cylinder 5, and if the rotating cylinder 5 rotates from this state by the angle formed, After one outer end corner 13a of the anvil piece 13 reaches the position of the arcuate groove 8a on the right side of the rotating cylinder 5, it passes through the arcuate groove 8b, and the chevron-shaped protrusion 14 enters the arcuate groove 8b. At the same time, as shown in FIG. 5, the side surface of the outer end corner 13a of the anvil piece 13 comes into contact with the right side surface of the locking protrusion 7 of the rotating cylinder 5, and the rotation of the rotating cylinder 5 is caused by the rotation of the anvil piece 13. is transmitted to the anvil 10 via.

At this time, until the anvil piece 13 comes into contact with the locking protrusion 7 of the rotating cylindrical body 5, the tip surface of the protruding shaft part of the spring receiving member 17 in the anvil body 10b is in contact with the large diameter cam surface 20 of the rotating cylindrical body 5. As a result of sliding, the spring receiving member 17 and the anvil piece pressing member 16 are further separated by the depth of the circumferential groove in which the large diameter cam surface 20 is provided, and the force of the spring 22 becomes extremely weak. Concave arcuate bottom surface 19 of anvil piece 13
Since the pressing force of the anvil piece pressing member 16 that is pressed against the spring force is weakened, the force that tries to rotate the anvil piece 13 becomes extremely small, and the anvil piece 13 maintains a predetermined degree of inclination. In this state, it comes into contact with the locking protrusion 7 of the rotating cylindrical body 5.
At the same time as this contact, the protruding shaft portion 17c of the spring receiving member 17 rides on the small diameter cam surface 21 and compresses the spring 22, and the anvil piece pressing member 16 strongly presses the concave arc-shaped bottom surface 19 of the anvil piece 13, causing the anvil piece 13 chevron-shaped protrusions 14 are rotated into a cylindrical body 5
The object is to be oriented in the diametrical direction of the object.

The operation from the start of rotation of the rotating cylindrical body 5 until the locking protrusion 7 is locked to the anvil piece 13 is performed instantaneously while the rotating cylindrical body 5 rotates once.

In this state, the anvil piece 13 is moved by the force of the spring 22 to direct the chevron-shaped protrusion 14 in the diametrical direction of the rotating cylindrical body 5. However, the elastic force of the spring 22 is larger than the static frictional force between the side surface of the locking protrusion 7 and the side surface of the anvil piece 13, and this frictional force and the rotating cylindrical body 5 The locking protrusion 7
and the anvil piece 13 maintain a locked state, and the rotating cylindrical body 5 and anvil 10 rotate integrally, and a bolt, nut, etc. is rotated by a socket body (not shown) attached to the tip of the anvil 10. It is something to do.

When the resistance from the anvil side increases due to screwing of bolts, nuts, etc., the anvil 10 will not move unless the engagement between the locking protrusion 7 and the anvil piece 13 is released.
approaches a stop while decreasing its rotational speed. Therefore, the centrifugal force acting on the anvil piece 13 becomes smaller, and when the centrifugal force is reduced, the restoring force of the spring 22 overcomes the static friction force between the locking protrusion 7 and the anvil piece 13, causing the anvil piece 13 to move counterclockwise. Rotate the anvil piece 13 to remove it from the locking protrusion 7, and as shown in FIG.
The rotating cylindrical body 5 performs free running while passing through the guide groove 9.

The protrusion 14 of the anvil piece 13 passes through the guide groove 9 and enters the other arcuate groove 8a of the rotating cylindrical body 5,
When the tip end comes into contact with the outer end of the arcuate groove 8a, the anvil piece 13 returns to the above-mentioned inclined state. Immediately before entering this inclined state, the protruding shaft portion 17c of the spring receiving member 17 moves to the large diameter cam surface 20 to weaken the spring force.

In this way, the anvil piece 13 is inclined so that its one end corner 13a and the tip of the chevron-shaped protrusion 14 are brought into sliding contact with the circular inner peripheral surface 5a of the rotating cylinder 5 as shown in FIG. The rotating cylindrical body 5 freely runs and its locking protrusion 7 again comes into contact with one side of the anvil piece 13 and locks therein.

At this time, if there is a resistance torque on the anvil 10 side that is greater than the rotational torque of the motor 4, the rotating cylindrical body 5
Even if the engagement between the locking protrusion 7 and the anvil piece 13 occurs, the centrifugal force that sustains the engagement is generated only momentarily, and the engagement is immediately released and the rotating cylindrical body 5
After making one rotation again, the two engage, and as the resistance torque increases, the engagement between the two becomes more impactful.

By repeating this impact, the screw is completely tightened.

When loosening the screw, the air motor 4 may be rotated in the opposite direction to engage and disengage the other side surface of the anvil piece 13 from the other side surface of the protrusion 7 of the rotating cylindrical body 5.

FIG. 8 shows the movement of the rotating cylindrical body 5 described above, the influence of the anvil piece 13 on the spring 22, and the factors caused by the cam surfaces 20 and 21 of the rotating cylindrical body 5, respectively, with lines a, b, and c. The operation of the spring 22 resulting from the combination of factors b and c is shown by line d.

In this figure, until the impact is performed, the rotating cylinder 5 rotates in the same direction, and during that time, the acting force of the spring 22 (indicated by A in the figure) is small and the effect on the anvil piece 13 and the rotating cylinder 5 is small. When the impact is performed, the rotating cylindrical body 5 rebalances and the force exerted by the spring 22 momentarily increases, causing the projection 7 of the rotating cylindrical body 5 to separate from the anvil piece 13 due to the impact reaction force. While the anvil piece 13 passes through the guide groove 9 (indicated by C in the figure), the force exerted by the spring 22 is small (indicated by C in the figure).
The acting force increases, and the state returns to state A and free running is performed.

As described above, the present invention provides a locking protrusion at a suitable location on the circular inner circumferential surface of a rotating cylindrical body connected to the rotor shaft of a motor, and a locking protrusion is provided on the outer circumference of the base end of the anvil so as to be swingable from side to side. In an impact wrench in which the rotation of a rotating cylindrical body is transmitted to the anvil by detachably engaging anvil pieces, the anvil includes an anvil piece pressing member and a spring receiving member internally, and these anvil pieces A spring is press-fitted between the facing surfaces of the pressing member and the spring receiving member, and the tip of the anvil piece pressing member is pressed against the concave arc-shaped bottom surface of the anvil piece, and the spring receiving member is attached to the inner peripheral surface of the rotating cylindrical body. In an impact wrench, the impact wrench is configured to be brought into sliding contact along the formed large-diameter inner circumferential surface and a cam surface having a smaller diameter than the large-diameter inner circumferential surface and provided opposite to the locking protrusion. Since it is related to a striking rotation device, all the momentum of the cylindrical body rotating at the outermost periphery can be directly transmitted to the anvil piece, and a large rotational striking force can be obtained, and the lubricating oil is transferred to the rotating cylindrical body by the rotational centrifugal force. Of course, the anvil piece is integrated on the inner circumferential surface of the rotary cylindrical body, and the sliding and locking operations of the anvil piece relative to the rotating cylindrical body are performed smoothly. Since the spring receiving member, which is disposed opposite to the anvil piece pressing member that presses the concave arc-shaped bottom surface of the piece through a spring, is in sliding contact with the large-diameter inner peripheral cam surface of the rotating cylindrical body, the pressing force against the anvil piece is reduced. As the anvil piece becomes smaller, its side surface can be engaged with the locking protrusion of the rotating cylindrical body while maintaining an accurate angle of inclination without being affected by the spring force. By minimizing friction loss between the rotor and the rotor, sufficient acceleration can be achieved by the rotor, and greater kinetic energy can be stored.

Furthermore, when the anvil piece is disengaged from the locking protrusion and assumes the tilted position again, this can be done with a small motor torque and hardly any reaction force is applied to the user.

Furthermore, when the anvil piece engages with the locking protrusion of the rotating cylindrical body, the spring receiving member slides into contact with the small diameter inner circumferential cam surface of the rotating cylindrical body and the spring is compressed, so that the pressing force of the pressing member against the anvil piece becomes large, and therefore, the acting force that tries to disengage the anvil piece from the locking protrusion along the locking protrusion works effectively, and the engagement and disengagement between the anvil piece and the locking protrusion of the rotating cylindrical body is smooth and reliable. It generates light, strong, and stable impact rotational force, enabling highly accurate screw tightening, resulting in minimal fatigue for workers and a long life for the machine.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a longitudinal sectional side view thereof, FIGS. 2 and 3 are sectional views taken along lines A-A and B-B in FIG. 1, and FIGS. FIG. 7 is a sectional view for explaining the action, and FIG. 8 is an action line diagram of each component. 1 is a casing, 4 is an air motor, 5 is a rotating cylindrical body, 5a is an inner peripheral surface thereof, 7 is a locking projection, 9 is a guide groove, 10 is an anvil, 13 is an anvil piece, 1
4 is a chevron-shaped protrusion, 16 is an anvil piece pressing member, 1
7 is a spring receiving member, 20 is a large diameter cam surface, 2
1 is a small diameter cam surface, 22 is a spring.

Claims (1)

[Claims] 1 A locking protrusion is provided at an appropriate position on the circular inner circumferential surface of a rotating cylindrical body connected to the rotor shaft of the motor, and an anvil piece provided on the outer periphery of the base end of the anvil so as to be swingable from side to side can be freely engaged and detached from the locking protrusion. In an impact wrench that transmits the rotation of a rotating cylindrical body to an anvil by engaging the anvil, an anvil piece pressing member and a spring receiving member are installed inside the anvil, and the anvil piece pressing member and the spring receiving member are arranged inside the anvil. A spring is press-fitted between opposing surfaces of the anvil piece, and the tip of the anvil piece pressing member is pressed into contact with the concave arc-shaped bottom face of the anvil piece, and a spring receiving member is formed on the inner circumferential surface of the rotating cylindrical body. and a cam surface having a smaller diameter than the large-diameter inner circumferential surface and provided opposite to the locking protrusion.