JP2006346807A - Air impact wrench - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an air impact wrench freely changing and selecting a case required to control final fastening torque and a case not required to do so. <P>SOLUTION: This air impact wrench is furnished with an air motor part 17 and a hammer mechanism part 39 in a main body 1 and fastens, and loosens bolts and nuts by a tool installed on a head end of an anvil 29 by generating rotating torque by supplying compressed air to the air motor part 17 through a left and right change-over valve 81 by changing it in the normal rotating direction and in the reverse rotating direction. A direct passage 68 and by-pass passages 66, 67 are provided between an air inlet 14 of the main body 1 and the left and right change-over valve 81. There is provided a torque sensing mechanism TS devised free to close the by-pass passages 66, 67 and to change and adjust a set value of fastening reversal torque when the fastening reversal torque reaches the set value in the middle of the by-pass passages 66, 67. A torque control change-over valve to change the direct passage and the by-pass passage 67 over to each other is also provided on the upstream of the left and right change-over valve 81. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an air impact wrench used for operations such as tightening and loosening bolts and nuts.

This type of air impact wrench has an air motor part and a hammer part in the main body, supplies compressed air to the air motor part to generate rotational torque, transmits this rotational torque to the hammer part, and from this hammer part to the anvil It is configured to transmit the impact torque in the rotational direction and tighten or loosen bolts and nuts with a tool (socket-shaped or bit-shaped) attached to the tip of the anvil.
Conventionally, the anvil can be switched between forward and reverse by switching the compressed air supply path to the air motor, and the ON / OFF operation of the compressed air supply to the air motor can be performed. An air impact wrench having a stop valve that automatically stops the supply of compressed air to the air motor unit when the value is reached is known (see Patent Document 1).
Japanese Utility Model Publication No. 2-31673

The air impact wrench of Patent Document 1 has an advantage that the final tightening torque of bolts and nuts can be quantitatively controlled without depending on the experience and intuition of the operator. For example, the air impact wrench is firmly tightened. When the bolts and nuts are loosened, there is a case where the above management is not necessary, and even though a large torque is required at the beginning of the loosening, the stop valve operates and the loosening operation cannot be performed.
An object of the present invention is to provide an air impact wrench that can be freely switched between when the final tightening torque needs to be managed and when it is unnecessary.

In order to achieve the above object, the present invention includes an air motor portion and a hammer mechanism portion in a main body, and a rotational torque is supplied to the air motor portion by switching between a forward rotation direction and a reverse rotation direction via a left / right switching valve. This torque is transmitted to the hammer mechanism, the hammering torque is transmitted from the hammer mechanism to the anvil, and the bolts and nuts are tightened or loosened with a tool attached to the tip of the anvil. In air impact wrench,
A direct passage and a bypass are provided between the air inlet of the main body and the left / right switching valve, and when the tightening reverse torque reaches a set value in the middle of the bypass, the bypass is closed and the tightening reverse torque And a torque control switching valve for switching between the direct passage and the bypass route upstream of the left / right switching valve.

The left / right switching valve and the torque control switching valve are installed close to each other.
Further, the present invention is characterized in that a torque adjusting member for changing and adjusting the set value of the tightening reverse torque is provided at the rear part of the main body.
The torque sensing mechanism may be configured to sense a tightening reversal torque in both the forward direction and the reverse direction.

According to the present invention, when the tightening reversal torque reaches the set value by either the left or right rotation by the switching operation of the torque control switching valve, the operation method and the tightening reversal torque are automatically stopped. Regardless of the method of tightening / loosening, it is possible to freely switch and select.
Further, since the left / right switching valve and the torque control switching valve are installed close to each other, the configuration of the compressed air supply path can be simplified, and the switching operation can be made convenient.

  Further, the torque adjustment member for changing and adjusting the set value of the tightening reversal torque is provided at the rear part of the main body, thereby facilitating the torque adjustment operation.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 to 3, reference numeral 1 denotes a main body, the central portion is a motor case 2, the front portion is a hammer case 3, the rear portion is a control case 4, and each case is a central axis in the front-rear direction of the main body 1. The seal rings 5 and 6 made of an elastic material such as rubber are fitted to each joint portion along the longitudinal direction.
On one side of the control case 4 (on the left side for right-handed use in FIGS. 1 to 3, the main handle 7 is on the right side for left-handed use) with respect to the central axis S of the main body 1. It is formed in series between the projecting ends of the upper and lower leg portions 8 and 9 projecting obliquely rearwardly.

Further, an auxiliary handle 10 is attached to protrude from one side of the hammer case 3. The main handle 7 and the auxiliary handle 10 are attached to be offset to the same side with respect to the central axis S of the main body 1, and an operator operates the main handle 7 with the right hand and the auxiliary handle 10 with the left hand. I can do it.
On the lower surface of the control case 4, a left / right switching lever 11 and a torque control switching lever 12 have a range of 90 ° around axes T 1 and T 2 perpendicular to the central axis S of the main body 1 with the former in the front and the latter in the back. It is mounted so that it can be rotated.

A torque adjustment lever 13 is mounted on the rear end of the control case 4 so as to be rotatable around the central axis S.
An air inlet 14 is formed at the lower end of the main handle 7, and a start lever 15 is pivoted around the support shaft 16 so as to be rotatable within a certain angle range around the support shaft 16.
The internal structure of the main body 1 will be described with reference to FIG.
In the motor case 2, an air motor 17 is supported via a rotor shaft 18 so as to be rotatable about a longitudinal axis (center axis S) of the main body 1. As shown in FIGS. 4 and 7, the air motor 17 forms an eccentric cylindrical space 22 by a cylindrical cylinder 19 and end plates 20 and 21 before and after the cylinder 19, and a cylindrical body shape is formed in the space 22. The rotor 23 is rotatably supported in an eccentric state via the rotor shaft 18, and the rotor blades 24 are fitted in the circumferentially equidistant positions of the rotor 23 so as to be protruded and retracted radially outward. ing.

As shown in FIG. 7, the cylinder 19 is formed with a right rotation air introduction port 25, a left rotation air introduction port 26, and an exhaust port 27 penetrating inward and outward in the radial direction. On the other hand, the right rotation air introduction port 25 and the left rotation air introduction port 26 are formed symmetrically with each other.
As shown in FIG. 4, the front end portion of the rotor shaft 18 protrudes into the hammer case 3, and a screwdriver 28 is spline fitted to the front end portion of the rotor shaft 18. A flange portion is formed on the outer periphery of the front end portion of the driver 28, and an appropriate notch portion 37 is formed in the flange portion as shown in FIG. 4 and 6, reference numeral 29 denotes an anvil having a pair of blade portions 30 projecting radially outward and facing each other, and the rear end shaft portion of the anvil 29 is loosely connected to the front portion of the driver 28. The intermediate shaft portion is supported by fitting and supported by the bush body 31 supported by the hammer case 3 so as to be relatively rotatable.

  Further, as shown in FIG. 4, an attachment portion 32 to which a tool such as a socket wrench is detachably attached is formed on the front end protruding portion of the anvil 29. Reference numeral 33 denotes a cylindrical hammer frame. An end plate 34 integrally formed on the rear end side is loosely supported on the outer peripheral surface of the driver 28, and a separate end plate 35 is an intermediate shaft of the anvil 29 on the front end side. The part is loosely supported. A hammer 36 is fitted and supported between the front and rear end plates 34 and 35 of the hammer frame 33 through a pin portion 36a having an axis parallel to the front-rear direction. As shown in FIG. 6, the hammer frame 33 is formed with an engagement protrusion 38 that engages with a notch 37 formed on the flange of the driver 28, thereby the rotor shaft 18 of the air motor 17 and The hammer frame 33 is rotated by the rotation of the driver 28 for spline fitting, and the hammer 36 strikes the blade portion 30 of the anvil 29 to constitute a hammer mechanism portion 39 that transmits the impact torque in the rotational direction to the anvil 29. .

As shown in FIG. 4, a cam clutch 40 is fitted on the rear end portion of the rotor shaft 18 so as to be slidable in the axial direction. The cam clutch 40 has an inclined cam surface 41 formed of a V-shaped recess on the front surface, and a clutch pin 42 corresponding to the inclined cam surface 41 is attached to the rear end portion of the rotor shaft 18 so as to penetrate in the radial direction. The clutch pin 42 is prevented from coming off in the radial direction by a clutch sleeve 43.
The inclined cam surface 41 is not limited to the V-shaped recess, and may be an arc-shaped recess or a parabolic recess. In short, the inclined cam surface 41 is formed as an inclined cam surface symmetrical with respect to the rotational direction so that the cam clutch 40 can be moved and converted rearward in the axial direction with respect to either the forward or reverse rotational direction of the rotor shaft 18. It only has to be done.

The cam clutch 40 is provided with a slide ball receiver 44 at the rear end surface, and a torque control spring 46 is interposed between the slide ball receiver 44 and the axial step 45 on the inner periphery of the control case 4. The spring 46 is pressed forward toward the clutch pin 42.
Behind the cam clutch 40, a cylindrical stop valve 47 is fitted and disposed in the cylindrical hole 48 of the control case 4 so as to be slidable in the axial direction on the same axis as the rotor shaft 18. The stop valve 47 is connected at its rear end to a torque adjusting lever 13 provided at the rear end of the control case 4 via a connecting body 49. The connecting body 49 has a male screw portion formed on the outer periphery thereof. The stop valve 47 can be moved in the axial direction with respect to the control case 4 by being screwed into a female thread portion formed on the rear end side of the four cylindrical holes 48 and rotating the torque adjusting lever 13. Has been.

An annular valve seat 50 and a steel ball 51 are provided inside the rear end side of the stop valve 47 so as to partition in the axial direction. On both front and rear sides of the valve seat 50, communication ports 52 and 53 that pass through in the radial direction perpendicular to the axial direction are formed, and annular grooves 54 and 55 are formed on the outer periphery of the communication ports 52 and 53. ing.
The steel ball 51 is disposed on the rear side of the valve seat 50 and is urged by a valve spring 56 in a direction to close the valve seat 50. The valve spring 56 is compressed and interposed between the front surface of the connecting body 49 and the rear surface of the steel ball 51, and the retraction dimension of the steel ball 51 with respect to the valve seat 50 is set and regulated by the protrusion at the front center portion of the connecting body 49. is doing.

  A pilot pin 57 facing the steel ball 51 is fitted inside the front end side of the stop valve 47 so as to be slidable in the axial direction, and is always urged rearward in the axial direction by a return spring 58. . The return spring 58 has a stronger spring force than the valve spring 56. An annular groove 59 is formed on the outer periphery of the front end portion of the pilot pin 57, and a lock ball 60 corresponding to the annular groove 59 has a diameter in a ball holding hole 61 formed so as to penetrate inside and outside in the radial direction of the stop valve 47. It is held so that it can protrude and retract in and out of the direction. The pilot pin 57 is configured to have a positional relationship such that the lock ball 60 is fitted into the annular groove 59 when being pressed against the axially rear end by the return spring 58.

  A torque sensing sleeve 62 for restricting the protrusion and retraction of the lock ball 60 in and out of the radial direction is fitted on the outer peripheral surface of the front end side of the stop valve 47 so as to be slidable in the axial direction. Is urged forward in the axial direction and is brought into contact with the stopper 64 at the outer peripheral portion of the front end of the stop valve 47. In this state, the lock ball 60 is pushed inward in the radial direction by the inner diameter surface of the rear end of the stop valve 47. It is configured to hold the state. An annular recess 65 for allowing the lock ball 60 to escape radially outward is formed in the axially central inner diameter surface of the torque sensing sleeve 62.

The front end portion of the torque sensing sleeve 62 is opposed to the slide ball receiver 44 on the rear surface of the cam clutch 40 with a predetermined axial gap G formed therebetween. The axial gap G can be adjusted through a male and female screw fitting portion between the connecting body 49 and the control case 4 by rotating the torque adjusting lever 13.
The torque sensing sleeve 62 moves rearward in the axial direction against the return spring 63 when the cam clutch 40 is displaced rearward in the axial direction beyond the axial gap G by the clutch pin 42, and thereby the annular recess 65. Reaches the position of the lock ball 60 and allows the lock ball 60 to move radially outward, and the pressure of the compressed air acting on both sides of the valve seat 50 causes the pilot pin 57 to move forward in the axial direction. The steel ball 51 can be pressed against the valve seat 50 to block the air flow, and thereby, the torque sensing mechanism TS is configured.

Detours 66 and 67 are connected to annular grooves 54 and 55 formed on the outer peripheral surface of the stop valve 47 on both sides of the valve seat 50. The detours 66 and 67 intersect the cylindrical hole 48 of the control case 4 into which the stop valve 47 is fitted (the right angle is illustrated, but it may not be a right angle), and the back and forth below the main body 1 In each case, the lower part is bent forward and is formed in parallel with the central axis S of the main body 1.
Below the control case 4, the bypass routes 66 and 67 and the direct passage 68 are partitioned so as to be switched by a torque control switching valve 69.

  The torque control switching valve 69 has a columnar shape that is rotatably fitted to the cylindrical body 70, and the cylindrical body 70 is switched to two upper and lower positions (cross-section indicating lines CC and DD). A part is formed. As shown in FIGS. 8A and 8B, the upper switching portion (cross-section indicating line CC) has two window holes 71 and 72 that are orthogonal to the axis of the cylindrical body 70 facing each other in the diameter direction (circumferential A linear hole 73 corresponding to this is formed so as to penetrate the switching valve 69 in the radial direction to form a two-way switching cock structure. As shown in FIGS. 8C and 8D, the lower switching portion (cross-section indicating line DD) has three window holes 74, 75, 76 in the circumferential direction perpendicular to the axis of the cylindrical body 70. L-shaped holes 77 corresponding to this are formed in the switching valve 69 and have a three-way switching cock structure.

The three window holes 74, 75, 76 of the three-way switching cock structure are connected to an air supply path 78 through which the central window hole 75 communicates with the air inlet 14, and the remaining two window holes 74, 76 are direct paths. 68 and a detour 66. Further, the two window holes 71 and 72 of the two-way switching cock structure are connected in the middle of the detour 67.
The torque control switching valve 69 is connected to the torque control switching lever 12 and can be rotated 90 ° left and right.
As shown in FIG. 5, the air supply path 78 that leads to the air inlet 14 is formed so as to communicate with the inside of the control case 4 from the lower leg portion 9 of the main handle 7. A start valve 79 is formed, and this start valve 79 is controlled to be opened and closed by the start lever 15 via the throttle pin 80.

As shown in FIG. 4, the straight passage 68 and the bypass 67 merge downstream, and a left / right switching valve 81 is installed downstream thereof. As shown in FIGS. 9 and 10, the left / right switching valve 81 is installed to switch between the right rotation air passage 82 and the left rotation air passage 83, and is rotatable to the cylindrical body 84. It is set as the cylindrical body shape fitted by.
The right rotation air passage 82 and the left rotation air passage 83 communicate with the right rotation air inlet 25 and the left rotation air inlet 26 formed in the cylinder 19 of the air motor 17.
As shown in FIGS. 9 and 10, the cylindrical body 84 is formed with three window holes 85, 86, 87 at intervals of 90 ° in the circumferential direction. It is formed in the valve 81 and has a three-way switching cock structure. Of the three window holes 85, 86, 87, the central window hole 86 is connected to the junction of the straight passage 68 and the bypass 67, and the other two window holes 85, 87 are connected to the right. The rotation air passage 82 and the left rotation air passage 83 are connected.

The left / right switching valve 81 is connected to the left / right switching lever 11 and can be rotated 90 ° left and right.
The torque control switching valve 69 and the left / right switching valve 81 are close to each other, and the left / right switching valve 81 is disposed at a front position in the axial direction, and the torque control switching valve 69 is disposed at a rear position in the axial direction. An exhaust hole 89 is formed in the upper part of the control case 4.
The embodiment of the air impact wrench of the present invention has the above configuration, and the operation will be described next. The air inlet 14 of the main body 1 is connected to a compressed air supply source such as a compressor through a connection hose. Then, the left / right switching lever 11 is switched to the right side, and the torque control switching lever 12 is switched to the bypass 66 side. In this state, when the start lever 15 is operated to open the start valve 79, the compressed air passes from the bypass 66 through the valve seat 50, and from the bypass 67 to the left / right switching valve 80, the right rotation air passage 81, and the air motor 17. The air is supplied into the air motor 17 through the air inlet 25 for right rotation, and discharged from the exhaust port 27 through the exhaust hole 88 to the outside of the main body 1. The anvil 29 is rotated to the right via, and bolts and nuts are tightened via a socket wrench attached to the anvil 29.

  As the tightening of the bolts and nuts proceeds, the hammering torque of the hammer 36 of the hammer mechanism 39 increases and the rebound rotation angle also increases. This repulsive force, that is, the tightening reverse torque, acts on the inclined cam surface 41 by the clutch pin 42 of the rotor shaft 18 and tries to move the cam clutch 4 rearward in the axial direction. Since the elastic force of the torque control spring 46 acts on the cam clutch 40 toward the front in the axial direction, the clutch pin 42 and the inclined cam surface 41 are caused by the tightening reversal torque generated in the rotor shaft 18. When the axial force in the rearward direction of the cam clutch 40 generated during this time becomes equal to or greater than the elasticity of the torque control spring 46, the cam clutch 40 moves backward and comes into contact with the front end of the torque sensing sleeve 62. The sleeve 62 is retracted, the annular recess 65 is moved to the position of the lock ball 60, and the restraint of the pilot pin 57 by the lock ball 60 is released. As a result, since the pressure of the compressed air acts on the rear end of the pilot pin 57, the pilot pin 57 is pushed forward in the axial direction, and the steel ball 51 is pressed against the valve seat 50 to bypass the detours 66 and 67. Close automatically. As a result, the air motor 17 stops, the bolts and nuts are tightened with a predetermined tightening torque, the tightening operation is completed, and the pressing of the start lever 15 is released.

  The start valve 79 has a check valve structure, and when the start lever 15 is released, the start valve 79 self-closes with air pressure, whereby the residual pressure between the valve seat 50 and the steel ball 51 and the start valve 79 is reduced. The pilot pin 57 is discharged from the hole 90 in the center portion of the throttle pin 80 and is moved rearward in the axial direction by the return spring 58 to push back the steel ball 51 and open the valve seat 50. On the other hand, when the air motor 17 stops, the cam clutch 40 returns to the front in the axial direction by the torque control spring 46, and the torque sensing sleeve 62 also returns to the front in the axial direction by the return spring 63. The pilot pin 57 is pushed in and fitted into the annular groove 59 of the pilot pin 57 to lock the movement of the pilot pin 57 in the axial direction. This state is maintained until the tightening reverse torque exceeds the set value described above by the next tightening operation.

In the above tightening operation, the retraction amount of the cam clutch 40 is proportional to the magnitude of the tightening reversal torque generated in the rotor shaft 18 of the air motor 17, and the axial clearance G at the front end of the torque sensing sleeve 62 is changed and adjusted. Thus, the set value of the tightening reverse torque can be changed. In the present invention, this adjustment is performed by the torque adjustment lever 13.
In the above operation, the anvil 29 is rotated to the right to tighten the right-hand screw type bolts and nuts. Switching to the left side may be performed in the same manner as described above.

Further, when loosely tightened bolts and nuts are loosened or when it is not necessary to manage tightening torque, the torque control switching lever 12 may be switched to the direct passage 68 side and operated. In this case, since the compressed air supply path to the air motor 17 does not pass through the detours 66 and 67 and reaches the left / right switching valve 80, the maximum compressed air pressure is maintained as long as the start lever 15 is kept pressed. The hitting torque in the rotation direction can be continuously applied to the anvil 29 by the energy.
The configuration and operation of the embodiment of the present invention are as described above. However, the present invention is not limited to this embodiment, and various modifications may be made within the meaning and scope described in the claims. For example, the air motor 17 and the hammer mechanism 39 may adopt other configurations, and the cam clutch 40 and the clutch pin 42 are composed of a ball and a spiral groove. An axial displacement sensing structure may be used. In addition, the exhaust hole 88 may be opened rearward, or may be provided with a sound deadening structure by providing an appropriate sound deadening material. Furthermore, it is not limited to a portable type. Moreover, although the case where the starting lever 15 is provided in the outer upper part (rear side upper part) of the main handle 7 is illustrated, it may be provided in the inner upper part (front side upper part).

It is a side view of the air impact wrench concerning the embodiment of the present invention. It is the bottom view seen from the bottom of FIG. It is the end elevation seen from the right side of FIG. It is a vertical side view of FIG. It is a vertical side view of the main handle part of the right end of FIG. It is the sectional view on the AA line of FIG. It is the BB sectional view taken on the line of FIG. (A) and (B) show two switching states in the CC sectional view of FIG. 4, and (C) and (D) show the two switching states in the DD sectional view of FIG. Yes. The cross-sectional view taken along the line EE in FIG. 4 shows the switching state during normal rotation. The cross-sectional view taken along the line E-E in FIG. 4 shows the switching state during reverse rotation.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Main body 2 Motor case 3 Hammer case 4 Control case 7 Main handle 10 Auxiliary handle 11 Left / right switching lever 12 Torque control switching lever 13 Torque adjustment lever 14 Air inlet 15 Start lever 17 Air motor 18 Rotor shaft 28 Driver 29 Anvil 33 Hammer frame 36 Hammer 39 Hammer Mechanism 40 Cam Clutch 41 Inclined Cam Surface 42 Clutch Pin 46 Torque Control Spring 47 Stop Valve 50 Valve Seat 51 Steel Ball 57 Pilot Pin 60 Lock Ball 62 Torque Sensing Sleeve 66, 67 Detour 68 Direct Path 69 Torque Control Switching Valve 78 Air supply path 79 Start valve 80 Throttle pin 81 Left / right switching valve

Claims (4)

An air motor part and a hammer mechanism part are provided in the main body, and compressed air is supplied to the air motor part via a left / right switching valve so as to generate rotational torque, and this rotational torque is generated by the hammer mechanism part. In the air impact wrench that transmits the impact torque in the rotational direction from this hammer mechanism to the anvil, and tightens or loosens the bolts and nuts with the tool attached to the tip of the anvil,
A direct passage and a bypass are provided between the air inlet of the main body and the left / right switching valve, and when the tightening reverse torque reaches a set value in the middle of the bypass, the bypass is closed and the tightening reverse torque The air impact wrench is provided with a torque sensing mechanism capable of changing and adjusting the set value, and further provided with a torque control switching valve for switching between the direct passage and the detour upstream of the left / right switching valve.   The air impact wrench according to claim 1, wherein the left / right switching valve and the torque control switching valve are installed close to each other.   The air impact wrench according to claim 1, wherein a torque adjusting member for changing and adjusting a set value of the tightening reversal torque is provided at a rear portion of the main body.   The air impact wrench according to claim 1, wherein the torque sensing mechanism is configured to sense a tightening reversal torque in both a forward direction and a reverse direction.

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