GB1562061A - Means for releasably coupling a member in or aon a rotatably coupling body - Google Patents

Description

(54) MEANS FOR RELEASABLY COUPLING A MEMBER IN OR ON A ROTATABLE BODY (71) We, FEDERAL-MOGUL WESTWIND AIR BEARINGS LIMITED, a British Company of Dalling Road, Branksome, Poole, Dorset BH12 1LG, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to an improvement in or modification of the invention set forth in Patent No. 1,213,201, according to which means for releasably coupling a member in a rotatable body comprises at least one bore extending diametrically through the axis of rotation of the body, a pair of substantially identical locking pieces arranged in overlapping relationship within the bore and eleastic means within the bore for connecting the locking pieces together; the arrangement being such that when the body revolves about its axis of rotation one locking piece experiences a centrifugal force in one direction in said bore, and the other locking piece experiences a centrifugal force in the other direction in said bore. According to Claim 2 of the said patent, the body in the form of a shaft is provided at one end with an axial bore which communicates with the diametrical bore, the axial bore being adapted to receive the shank of a drill, tap, reamer or like tool, each locking piece being provided with a hole sufficient to receive said shank when said holes are aligned with the axial bore, the edges of the holes gripping said shank on rotation of the shaft.

In the specification of the aforesaid patent, the registering holes in the locking pieces are shown as simple cylinders. In many applications of the invention such circular holes provide satisfactory results. However, as the centrifugal forces on the locking pieces and hence the grip on the tool shank, are proportional to the square of the speed of rotation, it has been found that, in some applications where the coupling means are required to be effective at low speeds as well as at high speeds, the shank is liable to rotate in the coupling. The main object of the present invention is to eliminate this disadvantage.

According to the present invention, coupling means according to Claim 2 of Patent No.

1,213,201 is provided with locking pieces having holes shaped so as to permit said locking pieces to move, or tend to move, radially with respect to the shaft axis to a limited extent under the centrifugal forces, in combination with a tool shank, the holes and the tool shank having mating surfaces that prevent relative rotation between the shank and the locking pieces.

Very conveniently the holes may be formed with opposed flat sides for engaging opposite flat faces on the shank.

In order that the invention may be clearly understood and readily carried into effect coupling means in accordance therewith will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a side elevation of an assembly of locking pieces; Figure 2 is a section on the line II-II in Figure 1; Figure 3 is a side elevation of part of a tool shank; and Figure 4 is a section on the line IV-IV in Figure 3.

The assembly of locking pieces shown in Figures 1 and 2 is essentially the same as the prior assembly described with reference to Figures 1 and 2 of the aforesaid specification, except that two registering holes 1, respectively in semi-cylindrical portions 2, 2A of two locking pieces, have opposed flat sides 3 joined by arcuate sides 4.

The portions 2, 2A are reduced at each end and the reduced end of one locking piece at one end is formed with a circular head 5, while at the other end the reduced end of the other locking piece is formed with a similar circular head SA. Thus a circular groove is formed between each head 5 or 5A and the pair of semi-cylindrical portions 2, 2A lying face to face as shown in Figure 2. An Wring 6, 6A is fitted into each groove.

The assembly of Figure 1 is mounted in a diametrical bore in a shaft (not shown) which is also formed with an axial bore to receive a drill shank 7 (Figures 3 and 4). The shank 7 has opposite flat faces 8 that bear on the flat sides 3 of the holes 1. When the shaft is rotated at a comparatively low speed, the flat sides 3 prevent any rotation of the shank in the locking pieces and when the shaft rotates at a comparatively high speed, the centrifugal action causes the two locking pieces to move, or tend to move radially outwards in opposite directions (arrows 9) locking the tool very firmly to the shaft.

In one example the dimensions A and B (Figure 1) of the registering holes 1 are 0.125 and 0.110 inches.

WHAT WE CLAIM IS: 1. Coupling means according to Claim 2 of Patent No. 1,213,201 provided with locking pieces having holes shaped so as to permit said locking pieces to move, or tend to move, radially with respect to the shaft axis to a limited extent under the centrifugal forces, in combination with a tool shank, the holes and the tool shank having mating surfaces that prevent relative rotation between the shank and the locking pieces.

2. Coupling means according to Claim 1, in which the holes are formed with opposed flat sides for engaging opposite flat faces on the tool shank.

3. Coupling means according to Claim 2, of Patent No. 1,213,201 and substantially as hereinbefore described.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (3)

**WARNING** start of CLMS field may overlap end of DESC **. other locking piece is formed with a similar circular head SA. Thus a circular groove is formed between each head 5 or 5A and the pair of semi-cylindrical portions 2, 2A lying face to face as shown in Figure 2. An Wring 6, 6A is fitted into each groove. The assembly of Figure 1 is mounted in a diametrical bore in a shaft (not shown) which is also formed with an axial bore to receive a drill shank 7 (Figures 3 and 4). The shank 7 has opposite flat faces 8 that bear on the flat sides 3 of the holes 1. When the shaft is rotated at a comparatively low speed, the flat sides 3 prevent any rotation of the shank in the locking pieces and when the shaft rotates at a comparatively high speed, the centrifugal action causes the two locking pieces to move, or tend to move radially outwards in opposite directions (arrows 9) locking the tool very firmly to the shaft. In one example the dimensions A and B (Figure 1) of the registering holes 1 are 0.125 and 0.110 inches. WHAT WE CLAIM IS:

1. Coupling means according to Claim 2 of Patent No. 1,213,201 provided with locking pieces having holes shaped so as to permit said locking pieces to move, or tend to move, radially with respect to the shaft axis to a limited extent under the centrifugal forces, in combination with a tool shank, the holes and the tool shank having mating surfaces that prevent relative rotation between the shank and the locking pieces.

2. Coupling means according to Claim 1, in which the holes are formed with opposed flat sides for engaging opposite flat faces on the tool shank.

3. Coupling means according to Claim 2, of Patent No. 1,213,201 and substantially as hereinbefore described.