US2160150A - Impact wrench - Google Patents

Description

May 30, 1939. FTA. .nMERsoN ET AL 2,160,150

` IMPACT WRENCH Filed Oct. 2l, 1957 THEAR ATTORNEY,

Patented .May 30, 1939 IMPACT WRENCH Fronois A. .limer-son and Hoo-ola c. Reynolds,

Athens, Pa., assignors to Ingersoll-Rand Company, Jersey City, N. J.,

Jersey a corporation of New Applioation ootobor 2.1, 1937', serial No. 110,213

z claims. (cl. 1Qz.3o.5)

impact blows to the tool in order that the tool` may overcome the work resistance.

Devices of this type are usually provided with an anvil member adapted to4 engage the work and a hammer member through which the driving force of the motor is transmitted to the anvil. The connecting means between the motor and the hammer is so constructed that the motor will rotate the hammer and anvil so long as the work resistance is insuilicient to overcome the driving torque. However, when the torsion set up bythe work is greater than the driving torque and sufiicient to prevent movement of the anvil by the hammer, this connection is designed to dis-` e'ngage the hammer and the anvil.

While the hammer and the anvil are disengaging, theenergy supplied by the motor is stored in a spring or accumulator device, and as soon as these parts are completely disengaged the stored' energy is imparted to cause the hammer to reengage with and impact against the anvil jaws. v

Thus the stored energy is employed to impart an additional angular velocity to the hammer over that imparted by the motor during the time that the hammer and anvil are re-engaging and the kinetic energy of the hammer is transformed into work delivered to the anvil. A great many forms of such connections have been proposed, but they' connection which will disengage the clutch member completely upon a slight angle of rotation vof 5o the motor. y

It is still a further object to provide a device which is novel and which will overcome work resistance effectively and efiiciently.

A still further object is to provide a driving 55 connection which is of rugged construction and not subject to excessive wear requiring frequent repairs.

` These and further objects will be apparent from the following description of which the drawing is a part.

In the drawing, similar reference numerals refer to similar parts.

Figure 1 is an elevational view in section of a device constructed in accordance with the principles of the present invention, l

Figure 2 is a View in section taken along the line 2-2 of Figure 1,

Figure 3 is a view partly in section and partly in elevation of a portion of the device illustrated in Figure 1 showing the hammer and anvil disengaged, and

Figure 4 is a developed view of a portion of the device of Figure 1 illustrating the parts in operating position.

Referring to Fig. 1 the rotary impact device is generally imndicated at I and consists of a casing 3 secured to the motor 5 by means of the bolts 1. The motor 5 may be any suitably controlled reversible motor having a shaft 9 rotating in the bearing I I. A iiange I3 is formed'on the shaft 9 to prevent movement of the shaft 9 toward the motor. Thehexagonal portion I5 is formed on the shaft 9 in juxtaposition to th iiange I3. This hexagonal portion may, of course, be of any other desired construction so long as it will prevent relative rotation of the rotary driving head I1 with respect to the shaft 9 and Will permit the shaft 9 to rotate the head I1 which is surrounded by a cup-shaped hammer I9 extending into the casing 3.

On the bottom of the cup-shaped hammer are clutch teeth 2| which are adapted to engagewith corresponding clutch teeth 23 mounted on the upper face of the anvil member 25. These clutch teeth 2| and 23 provide a disengageable driving means between the hammer member I9 and the anvil member 25. 'I'he anvil 25 consists of a cylindrical portion 21 surmounted by a ange 29 on the upper surface of which are mounted the clutch teeth 23. A bearing 3l situated within the tool may be secured to the anvil, a shank 35,I

formed as an integral part of the anvil, extends from the cylindrical portion 21 of the anvil. The

wrench 33 is secured by any means, such as the set screw 31 to the shank 35, and is provided with a socket 39 adapted to engage the nut 4| in order that the nut may be secured to the bolt 43.

It is desirable that the hammer member I9 be maintained in axial alignment with the shaft 9 at all times, and for this reason an extension 45 is formed on the hexagonal portion I5 of the shaft 9. This extension is recessed in a guide rod 41 which passes through the bottom wall of the hammer I9 into a recess 49 formed in the upper part of the anvil member 25. Guide rod 41 acts as a spacer between drive head I1 and anvil 21 to hold the anvil down during disengagement of the clutch teeth 2| and 23. cient diameter to permit rotation of the guide member therein, and the guide member in turn permits free rotation of the extension 45 formed.

on the shaft I I.

Within the head I1, and surrounding the guide rod 41, is a thrust bearing 5| which permits the spring 53 to rotate with respect to the head I'I. A spring 53 rests against the thrust bearing 5| at one end thereof, and the other end rests in a well 55 formed in the bottom wall of the hammer member I9. The purpose of the spring is normally to hold the hammer clutch jaws 2| in engagement with the anvil clutch jaws 23, and to absorb and impart energy.v

The apparatus above described is an impact wrench of a conventional design and the driving connection between the head I1 and the hammer I9 will now be described.

On the side of the driving member I1, channels or races 51 are formed. These channels 51 are formed as shown in Figs. 3 and 4 with inclined surfaces 59'and 6| which meet at their lowermost point 63. Several of these doubly inclined channels are provided, and there is no intercommunication between the separate channels. The hammer member I9 is provided with grooves 65 which are so placed that they cooperate with the channels 51 formed on the driving head. 'Ihese grooves communicate with openings 61 which extend through the wall of the hammerbmember I9 and permit the insertion of the balls 13.

The arrangement of grooves 51 and 65 and ball members 13, which are guided in them, is to permit the hammer I9 to disengage the anvil member 29 upon encountering a predetermined resistance thereof to rotation, and to assist in storing in the spring 53 energy which is subsequently expended upon the anvil by the hammer.

Thus, when the torque of the shaft 9, transmitted through the jaws `2| and 23, is insuflicient to turn the anvil 29 due to the resistance of nut 4|, the jaws 2| and 23 disengage by raising the hammer I9 against the compression of spring 53 during which the balls 13 roll up grooves 51 and the grooves 55 correspondingly rise to lift the hammer I9. 'As soon as the jaws 2| rise to the height of jaws 23 they slide on top of the latter until rotated to a point of complete disengagement therewith. Jaws 2I are then free of jaws 23 and spring 53 tends to extend itself. In so doing, the hammer |9 is forced to move much faster than the driver 9 and because of this increased velocity, the kinetic energy thereof is increased as the square ofl the velocity. As the The recess 49 is of suflispring 53 extends, the grooves 65 cause the balls 13 to roll preferably almost down to the bottoms of the grooves 51 before the jaws 2| and 23 reengage so that the jaws strike each other with the maximum possible impact.

The arrangement above described provides the least possible friction in contacting parts. The bearing of balls 13 With the grooves 51 and 65 is substantially without friction and in addition the balls 13, as they roll, move a very slight distance in the grooves which enables the grooves to be made relatively short. Actually, the grooves may be made only half the `length of cam surfaces previously used in similar applications for impact Wrenches as is well known in the art. This permits the provision of a plurality of sets of grooves 51 and 65 to give suitable bearing and support for the hammer I9.

The number of jaws 2| or jaws 23 is optional. With two sets of such jaws, two blows are delivered to the anvil 29 at each revolution when the nut 4| is being set.

It is understood that in setting nut 4| the hammering of the hammer I9 upon anvil 29 continues as long as power is applied to shaft 9 and that it is this hammering that causes the nut 4| to be turned to its seat. A very important advantage of this wrench is `that the reaction upon the tool itself is negligible so that little effort is required by the operator to prevent the casing from turning. This property is in a large measure due to the frictionless structure provided by this invention.

We claim:

1. In a rotary impact tool having an anvil and a hammer for striking the anvil, clutch members on the hammer and anvil, a spring to normally hold the clutch members in engagement, driving means for the hammer, and means connecting the hammer and driving means comprising V-shaped channels on the driving means having the arms of the V inclined at an angle to the horizontal substantially less than ninety degrees, inverted V-shaped grooves on the hammer member having arms at the same angle to the horizontal as the arms of said channels, and ball members retained in said V-shaped channels by said 'inverted V-shaped groove.

2. In a rotary impact tool having an anvil and a hammer for striking the anvil, disengageable cooperating clutch members on. the hammer and anvil, a spring to normally hold said clutch members in engagement, driving means for the hammer, and means whereby the driving means may drive the hammer member when the clutch members are engaged and to disengage the clutch member when the driving means is incapable of driving the hammer member comprising V- shaped channels on the driving means having the arms of the V inclined at an angle to the horizontal substantially less than ninety degrees, inverted V-shaped grooves on the -hammer having the arms of the V at the-same angle to the horizontal as the armsy of said channels, and means guided by said channels and grooves.

FRANCIS A. JIMERSON. HAROLD C. REYNOLDS.

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