US2566661A - Power-operated impact wrench - Google Patents

Description

P 1951 F. T. HAMLIN 2,566,661

POWER-OPERATED IMPACT WRENCH Filed Oct. 9, 1948 21 i 'gh 40 3 as h d 44 25 an 22 I9 39 4 2G l5 lNVENTOR FREDE RIG T. HAMLIN.

HIS ATTORNEY Patented Sept. 4, 1951 POWER-OPERATED IMPACT WRENCH Frederic T. Hamlin, Stewartsville, N. J., assignor to Ingersoll-Rand Company, New York, N. Y., a corporation of New Jersey Application October 9, 1948, Serial No. 53,620

5 Claims.

This invention relates to impact wrenches and more particularly to wrenches utilized to rotate relatively large nuts, as for example, around 5 inches outside diameter.

Heretofore, in order to tighten or loosen nuts of the size referred to, it was necessary to resort to the wrench sledge hammer method or, in lieu of a sledge hammer, a ram supported from the ceiling by cables or ropes and swung back and forth by two or more men was used to hammer the wrench. Such an arrangement has several obvious disadvantages, other than its inefficiency-as for example, the high linear stresses developedin the bolt on which the nut is being tightened. It is, accordingly, one object of my invention to develop torque free of linear stresses for tightening nuts and bolts and the like.

Another object of my invention is to utilize the rotational energy of a body, relatively massive compared to the body to be rotated, in a device of the character referred to.

A further object of my invention is to construct an impact wrench in such a manner that the driving force or prime mover for the wrench is not subject to undue strain at the instant of impact of the wrench.

Other objects will become obvious hereinafter.

In the drawing accompanying the specification and in which similar reference characters refer to similar parts,

Figure l is a vertical elevation, partly in section, of an impact wrench constructed in accordance with the practice of the invention,

Figure 2 is a top view, partly in section, of the impact wrench arranged to rotate a body in the clockwise direction.

Figure 3 is a top view of the impact wrench arranged to rotate a body in the counterclockwise direction, and

Figure 4 is a vertical elevation, partly in section, of the clutch arrangement for the impact wrench for obtaining counterclockwise rotation of the body to be rotated.

Referring to the drawing and more particularly to Figure 1, l designates, in general, a preferred form of the impact wrench supported in its operative position for tightening a nut II on a bolt 12 by a cradle I! which in turn is supported by cables 20 depending from an overhead construction (not shown). In the main, the wrench l0 comprises a torque producing member or wheel l3 of relatively massive size, compared to the nut II, rotated by an air motor l4 slidably mounted on a wrench member l which intermittently engages the wheel 13 to transmit torque therefrom to the nut H. To this end, the wrench member 15 at one end grips the nut II and is provided on the other, or opposite, end with a pair of cams it having engaging faces I! spaced degrees apart and positioned coaxially with a similar pair of cams [8 on the wheel l3 for engagement therewith.

More specifically, the cradle l9 comprises a horizontally disposed plate 2| having radial arms 22, in this instance three, of such a length that the vertically extended ribs 23 mounted on the ends of the arms 22 clear the periphery of the wheel l3 mounted in a horizontal position above the plate 2|, and it is to these ribs 23 that the cables 20 are secured by means of eye bolts 24 threaded in the upper ends of said ribs. Encircling a central perforation 25 in the plate 2| through which loosely extends the wrench member I5, is a groove 26 of slightly greater diameter than a flared portion or flange 21 on the member l5 which rests therein. With this arrangement, the wrench member i5 is permitted to rotate freely relative to the cradle i9, and

the groove 26 serves to maintain proper alignmentlbetween the wrench member l5 and the nutl slidably mounted in a groove 28 in the periphery of the flange 21 is a support 29 for the air motor M which serves as a means for rotating the torque producing member, or wheel l3, and is accordingly provided with a driving connection, such as the gear 30 keyed to the motor shaft 3|, which engages gear teeth 32 on the rim of the wheel 13. In the preferred form of the invention, the motor I4 is designed to reach its maximum speed, from rest, in the time required to rotate the wheel I3 180 degrees. Thus, the wheel 13 reaches its maximum speed at the instant the cams l8 engage the cams ii.

In order to .prevent the motor H from walkme, or propelling itself, around the wheel l3 when the wheel is engaged with the wrench member l5, or otherwise prevented from rotat- 'ing, a yieldable means, such as the spring 33, is

connected between the arms 34 and 35 mounted, respectively, on the wrench member I5 and the support 29. Thus, any tendency of the motor to move relative to the wheel 13 is resisted by the nut through the member l5-that is, rotation in this direction would tend to unscrew the nut II. This arrangement requires, of course, that nut ll be initially tightened enough to resist this unscrewing action. The spring 33 serves, further, to reduce the shock to which the motor is subject at the instant of impact of the mating of cams I6 .and I 8, resulting from the tendency of the wrench member IE to rotate the motor support 29. However. dueto the floating or sliding relation between the wrench member II and the motor support 29, at impact the spring 33 will stretch and permit the motor, as a whole, to reach an equilibrium position without rotating, relative to the bolt I2 or other stationary objects, at the highspeed imparted to the member I by the wheel I3. The equilibrium .position is, of course, dependent on the strength of the spring 33 and the power of the motor-that is, whenever the wheel I3 is held against rotation and the motor is supplied with power, the motor tends to travel around the wheel I3 and thereby stretch the spring 33 until the motor stalls.

As previously mentioned, the motor I4 is, in this instance, air driven and is accordingly supplied with a motive fluid or air by means of the conduit 36 from a source (not shown). A branch 31 of the conduit 36 passes through a three-way valve 38, which, for the sake of simplicity, is shown as being manually operated, and thence to the member I5 for supplying motive fluid to the wrench for disengaging the cams I6 and I3. To this end, the wrench member I5 is provided with a central bore 39 into which extends a rod or piston member 40 mounted coaxially on the wheel I3 and having a pressure surface 44 on the lower end thereof exposed to the motive fluid delivered to the lower end of the bore 39 by the conduit 37. Thus, whenever the three-way valve 33 is positioned to allow motive fluid to flow to. the bore 39, the torque producing member I3 will be moved vertically along its axis and thereby disengage the cams I6 and I8. The upward movement of the wheel I3 is limited by an exhaust port M for the bore 39 and positioned in such wise as to permit the cams I6 and I8 to clear each other before the pressure fluid is exhausted from the bore 39. Reverse longitudinal, or downward, movement of the wheel I3 is attained by either exhausting the pressure fluid from the bore 39 through the valve 39 or by cutting of! the pressure supply to the bore 39 by means of the valve 38 and permitting the air in the bore 39 to leak past the piston rod 40 and escape through the port 4I thereby permitting the weight of the wheel, or gravitational force, to move the wheel I3 into a position to align the cams I8 and I3.

Proper alignment between the wrench member I5 and the wheel I3 during disengagement of the cams I6 and I8 is maintained by providing a groove 42 in the hub of the wheel I3 and encircling the piston member 40, into which flts a sleeve 43 extending from the axis of the member I5. The length of the sleeve 43 is of such, dimension as to permit the sleeve 43 to remain in contact with the inner surface of the cams I8 at all times, and the groove 42 is of such a depth as to permit the mating faces on the cams I6 and I8 to be in full engagement at the instant of impact.

When reverse rotation of the nut is desired, it is merely necessary to replace the wrench member I5 with the wrench member 45 (shown in Figure 4) having oppositely disposed cams 46 relative to the cams I6; mount the spring 33 and associated arms 34 and 35 on the opposite side of the motor I4, in that direction of rotation of the motor and wheel I3 are reversed; and turn over the wheel I3 so that the cams 41 provided for this purpose on the opposite side of the wheel and having oppositely disposed mating faces, relative to the cams I8, engage with the cams 46. There is, of course, a' piston member 40 provided on the same side of the wheel I3 as the cams 41, for imparting longitudinal movement to the wheel I3 for disengaging the clutch or cams 46 and 41. A protective cap 43 is provided which fits over either of the members 40 and is secured thereto by bolts or screws 49 threaded through the cap 43 and extending into a groove 50 in the periphery of the member 40. This cap serves to protect the end or pressure surface of the member 40 from possible damage from an external source during the period it is not in use, i. e., when it is not inserted in the bore 39.

In operation, assuming clockwise rotation (as viewed in Fig. 2) of the wheel I3, air is valved to the motor I4 which immediately moves around the periphery of the wheel l3 until the tension of the spring 33 is suflicient to stall the motor. The operator then shifts the three-way valve 33 to permit motive fluid to flow into the bore 39 to disengage the cams I6 and I8, in the manner previously described. When the cams I6 clear the cams I3, the three-way valve 38 is placed in position, by the operator, to exhaust fluid from the bore 39- to permit the wheel I3 to slide into its mating position as it is rotated by the motor I4. At the instant of impact. the wrench member I5 is fully engaged or clutched to the wheel I3 and the kinetic or rotational energy of the wheel is dissipated in turning the nut II against frictional resistance. The above cycle'is then repeated until the desired tightness of the nut is attained.

Itis now obvious from the previous discussion that an impact wrench constructed in accordance with the practice of the invention provides a relatively simple yet highly effective means for tightening nuts and bolts and the like and which may readily be adapted for loosening the same and, further, in both instances, torque is developed that is relatively free of linear forces.

Still further, such a mechanism is provided with a means for preventing undue strain in any of its parts and more particularly to the prime mover at the instant of impact of the cams or other clutch arrangement.

While I have shown and described a specific form of my invention, it is to be understood that various changes and modifications may be made without departing from the spirit of the invention as set forth in the appended claims.

I claim:

1. An impact wrench comprising, a torque producing member, means for rotating said member, means engaging the torque producing member for transmitting rotary movement therefrom to the member to be rotated. means for disengaging the first said member from the second said means, a support for the first said means slidably mounted on the second said means, and yieldable means for limiting relative movement between the support and the second said means. I I

2. An impact wrench comprising, a wheel shaped torque producing member, a motor for rotating said torque producing member, a driving connection between the motor and the' periphery of said member, means engaging said torque producing member for transmitting torque therefrom to the member to be rotated and having a chamber therein, means attached to the first said member extending into said chamber and having a pressure surface on the end there- 5 of, and means for conveying pressure fluid to said pressure surface.

3. An impact wrench comprising, a wheel shaped torque producing member, a motor for rotating said member, a driving connection between the motor and said member, a wrench coaxial with said member for transmitting torque therefrom to the member to be rotated and having a central bore, cams on the remote end of said wrench, cams on the first said member engaging the first said cams, a rod attached to the first said member and extending slidably into said bore, and means for imparting longitudinal movement to said rod for disengaging said cams.

4. An impact wrench comprising, a wrench member having a, bore, a, wheel shaped member horizontally mounted on said wrench member and of relatively massive size compared to the member to be rotated, cams on an end of the wrench member, oppositely disposed cams on the wheel engaging the first said cams, a support rotatably mounted on said wrench member, a motor mounted on the support for rotating said wheel shaped member, and yieldable means connected between said support and said wrench member.

5. An impact wrench comprising, a torque producing member, a wrench adapted to be periodically engaged by such member for transmitting a rotational force be a, member to be rotated, a motor slidably mounted on said wrench and pro-A vided with means to engage and rotate the torque producing member, and yieldable means yieldably connecting said wrench to said motor for limiting rotational movement oi! the motor relative to the torque producing member and to limit the shock, transmitted to the motor from said wrench on impact of said torque producing member with the wrench.

FREDERIC T. HAMLIN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,219,883 Amtsberg Oct. 29, 1940 2,285,639 Amtsberg June 9, 1942' 2,484,471 Shinn Oct. 11, 1949 FOREIGN PATENTS Number Country Date 546,372 Great Britain July 9, 1942 851,047 France Sept. 25, 1939

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