GB2134966A

GB2134966A - Double clamp

Info

Publication number: GB2134966A
Application number: GB08334204A
Authority: GB
Inventors: Lothar Walter; Walter Reith; Manfred Brandenstein; Manfred Krug
Original assignee: SKF Kugellagerfabriken GmbH
Current assignee: SKF GmbH
Priority date: 1982-12-24
Filing date: 1983-12-22
Publication date: 1984-08-22
Also published as: DE8236311U1; GB8334204D0; GB2134966B; FR2538473B1; FR2538473A1

Abstract

A clamp for preventing or allowing linear motion of a housing 1 on a shaft 11, comprises clamping bodies 4 arranged between the shaft 11, and the housing 1 to cooperate with tapered surfaces 7 of the housing 1 which guide them to positions in which they grip the shaft 11. The housing 1 is provided with two tapered bores having bore surfaces 7 inclined in opposite directions and spring 5 urges the bodies 4 apart, along these surfaces 7 into contact with the shaft 11. Pressing 2, 3 towards each other releases the clamping. In another embodiment (Fig. 6), the balls are replaced by sleeves 33. <IMAGE>

Description

SPECIFICATION Double free-running mechanism for linear motion The present inventoin relates to a double free running mechanism for linear motion of a housing or the like on a shaft, column or the like, wherein between the shaft, column or the like and the housing or the like there are arranged clamping bodies which cooperate with tapered surfaces of the housing or the like and the shaft, column or the like, and which mechanism is provided with means which enable the connection to be released.

Double free running mechanisms of this type for linear motion are already known. In these known free running mechanism, slotted sleeves are provided between the clamping bodies arranged in the cages and the shaft so that no direct force transmission to the shaft takes place.

The efficiency of the free running mechanism is thereby decreased because slip is relatively high.

The present invention is based on the object of devising a double free running mechanism for linear motion, which consists of only a few, easily assembled parts and wherein the forces are transmitted directly to the shaft.

According to the invention, the housing or the like is provided with two tapered bores having bore surfaces inclined in opposite directions and against which there are applied clamping bodies which are in contact with the shaft, column or the like, and between the clamping bodies of each bore surface there are disposed axially outwardly acting spring elements which abut indirectly or directly against the clamping bodies. This development brings about a free running mechanism with unlimited travel movement and which has a high degree of operating accuracy.

According to preferred features of the invention, clamping balls are provided between the shaft, column or the like and the tapered bore surfaces of an outer ring, which balls are inserted with clearance in radial bores of cage rings, between which rings are arranged, for example, conical springs which, under preloading, abut against the mutually facing end faces of the cage rings. This embodiment comprises only a few parts which can be easily assembled.

Moreover, it is advantageous for a radially inward directed rim, flange or the like to be provided in the bore of the outer ring and for conical springs to be provided between the rim and the cage rings, which springs abut against the end faces of the cage rings and those of the rim. It is thereby possible for the cage rings to be brought independently of one another into the disengaged position.

Furthermore, it is advantageous to insert the clamping balls in outwardly open recesses of cage rings, in which case between the rows of clamping balls there is arranged a split spring ring which under radial preloading abuts against the clamping balls below the pitch circle with surfaces extending tangentially to the balls.

According to further preferred features of the invention, instead of clamping balls, clamping sleeves are provided respectively with a tapered circumferential surface, which sleeves engage in the tapered bore surfaces of an outer ring, are arranged on the shaft, column or the like and, optionally, have axially extending slots. This structural unit has long service life and consists only of a few, easily produced parts.

In another aspect the invention provides a mechanism for linear movement along a shaft, the mechanism comprising an outer member having a bore with surfaces in the bore comprising two truncated conical surfaces fixed with respect to the member, which surfaces either both narrow or both widen in directions extending away from one another, bodies disposed in the bore and engaging one or the other of the conical surfaces, and spring means urging the bodies axially towards the narrower end of the respective conical surface.

Embodiments of the inventoin will now be described by way of example and with reference to the accompanying drawings, of which: Figure 1 shows in section a double free running mechanism for linear motion, in accordance with the invention; Figure 2 shows a section through a double free running mechanism in accordance with another embodiment of the invention; Figure 3 shows an end view of the double free running mechanism illustrated in Figure 2; Figure 4 shows the double free running mechanism according to Figure 2, wherein linear movement downwards is made possible; Figure 5 shows a double free running mechanism according to the invention, with a split spring ring between the rows of clamping balls; and Figure 6 shows a modified double free running mechanism which has tapered clamping sleeves.

The double free running mechanism according to Figure 1 comprises an outer ring 1, two cage rings 2, 3 each with a plurality of clamping balls 4 and conical springs 5 which are disposed axially between the cage rings 2, 3. Starting from the end faces 6, the outer ring 1 has two conical bores with bore surfaces 7 inclined in opposite directions. In this case the cone angles, at which the bore surfaces 7 are inclined, are so chosen that self-locking occurs when the free running mechanism is blocked. The cage rings 2, 3 for the clamping balls 4 are provided axially outwards with an abutment flange 8 and, in an axially extending annular portion 9, have a plurality of radially extending bores 10 arranged spaced apart circumferentially, the clamping balls 4 being retained radially movably in these bores.Upon assembly of the double free running mechanism, firstly a cage ring 2 with the clamping balls 4 is inserted into the bore of the outer ring 1; next the conical springs 5 are introduced and then the second cage ring 3 with the clamping balls 4 is installed. In order to fit the shaft 1 the cage rings 2, 3 are pressed inwardly against the pressure of the conical springs 5 so that the balls 4 are situated in the vicinity of the largest diameter of the conical bore surfaces 7 and the diameter of the circle on which the balls 4 lie in the bore is greater than the diameter of the shaft 11. After fitting the shaft 11, the cage rings 2, 3 are displaced axially outwards by the pressure of the conical springs 5, so that the clamping balls 4 are pressed against the conical bore surfaces 7 and against the shaft 11 and the free running mechanism is blocked.By displacing the two cage rings 2, 3 axially inwards, movement of the free running mechanism in both axial directions is made possible. For example, the cage rings 2, 3 are connected in the bores with plain bearings 12 which are mounted slidably on the shaft 11 so that, when the free running mechanism is released, satisfactory guidance of the free running mechanism on the shaft 11 is ensured.

Figures 2 to 4 illustrate a free running mechanism which, in principle, is similar in construction. Here the displacement of the cage rings 13, 14 with the clamping balls 15 is effected by U-shaped release members 17 whose arms 18 are guided radially displaceably in recesses 19 of the outer rings 20. On the side facing the outer cage end faces 21, the arms 18 are each provided with surfaces 22 which are directed obliquely to the axis and which abut against corresponding surfaces 23 in the outer end faces 21 of the cage rings 13, 14. By radially depressing the upper or lower release member 17, the cage ring 13 or 14 with the clamping balls 15 is pressed axially inwards (Figure 4) and thus axial displacement of the free running mechanism is possible in one or the other direction.If both release members 17 are pressed in, the free running mechanism can thus be displaced in both axial directions.

Figure 5 shows a double free running mechanism which has substantially the same construction as the above-described embodiments. In this embodiment the cage rings 24, 25 are provided at the mutually facing end sides with outwardly open recesses 26, in which the clamping balls 27 are so arranged that they protrude from the recesses 26. Between the cage rings 24, 25 there is provided a split, radially compressible spring ring 28 which is disposed between the rows of clamping balls 27 and, under radial preloading, abuts against the clamping balls 27 below the pitch circle with tangentially extending surfaces 29. Upon axially depressing the cage ring 24, the balls 27 of the upper ciamping-ball row are displaced axially inwards, whereupon the split ring 28 is reduced in diameter and the clamping balls 27 of the upper ball row are released from the conical bore surface 30.Upon downward movement of the free running mechanism, the balls 27 of the lower row are also disengaged so that the free running mechanism can be displaced.

Figure 6 illustrates a similarly acting free running mechanism which comprises a two-part outer ring 31 A, held together by a ring 31, with two conical bore surfaces 32 inclined in opposite directions and two clamping sleeves 33 with tapered outer surfaces 34, which are pressed by a spring 35 against the conical bore surfaces 32 of the outer ring 31 A. The clamping sleeves 33 are provided with axially extending slots 36 so that, upon being pressed against the conical bore surfaces 32 of the outer ring 31 A, they are radially compressed and pressed on to the shaft 11. In the case of this free running mechanism, release of the blocking action is effected by displacing the clamping sleeves 33 axially inwards.

These embodiments merely represent examples of a free running mechanism for linear motion in accordance with the invention Modifications to the design of the individual components are possible within the scope of the invention. For example, in the embodiment shown in Figure 1, in the bore of the outer ring 1 a radially inwardly directed rim, flange or the like can be provided, while between the rim and the cage rings conical springs can be provided which abut against the end faces of the cage rings and against those of the rim. Moreover, it is possible for each clamping ball to be arranged in axially directed grooves of the outer ring and/or of the shaft. These free running mechanisms for linear motion may be used, for example, for the clamping and displacement of appliances on columns and shafts, as well as for couplings and the like.

The mechanism may be constructed so that the conical bore surfaces narrow towards one another and spring means are provided urging the clamping bodies towards one another. The spring means may be a spring under tension or two springs under compression at opposite ends of the housing.

Claims

1. Double free running mechanism for linear motion of a housing or the like on a shaft, column or the like, wherein between the shaft, column or the like and the housing or the like there are arranged clamping bodies which cooperate with tapered surfaces of the housing or the like and the shaft, column or the like, and which is provided with means which enable the connection to be released, wherein the housing or the like is provided with two tapered bores having bore surfaces inclined in opposite directions and against which there are applied clamping bodies which are in contact with the shaft, column or the like, and between the clamping bodies of each bore surface there are disposed axially outwardly acting spring elements which abut indirectly against the clamping bodies.

2. Double free running mechanism according to Claim 1, wherein the bore surfaces are designated to be inclined at an angle to the axis of the free running mechanisms ensuring selflocking when the free running mechanism is blocked.

3. Double free running mechanism according to Claim 1 or 2, wherein clamping balls are provided between the shaft, column or the like and the tapered bore surfaces of the outer ring, which balls are inserted with clearance in radial bores of cage rings.

4. Double free running mechanism according to Claim 3, wherein between the cage rings there are arranged, for example, conical springs which abut under preloading against the mutually facing end faces of the cage rings.

5. Double free running mechanism according to Claim 3, wherein a radially inward directed rim or the like is provided in the bore of the outer ring and, for example, conical springs are provided between the rim and the cage rings, which springs abut against the end faces of the cage rings and those of the rim.

6. Double free running mechanism according to Claim 1 or 2, wherein clamping balls are provided between the shaft, column or the like and the tapered bore surfaces, which balls are inserted with clearance in outwardly open recesses of cage rings, and between the clamping-ball rows there is arranged a split spring ring which, under radial preloading, inwardly abuts against the clamping balls below the pitch circle.

7. Double free running mechanism according to Claim 6, wherein the surfaces of the spring ring abutting against the clamping balls are arranged extending tangentially to the clamping balls.

8. Double free running mechanism according to any one of Claims 1 to 7, wherein, for example, the cage rings are connected with bearings which are slidably arranged on the shaft.

9. Double free running mechanism according to Claim 1 or 2, wherein between the shaft, column or the like and the outer ring there are provided clamping sleeves each with a tapered outer surface and a cylindrical bore, which engage in the tapered bore surfaces of the outer ring and are arranged on the shaft, column or the like.

10. Double free running mechanism according to Claim 9, wherein the clamping sleeves are provided with axially extending slots.

11. Double free running mechanism according to Claim 9 or 10, wherein the outer ring comprises two annular portions which are joined by corresponding means.

12. Double free running mechanism according to any one of Claims 1 to 11, wherein radially displaceable U-shaped release members are arranged in recesses of the outer ring or the like, the arms of which release members are provided, on the sides facing the outer end sides of the cage rings or the like, with surfaces which are directed obliquely to the axis and which abut against corresponding inclined surfaces of the cage rings.

13. Mechanism for linear movement along a shaft, the mechanism comprising an outer member having a bore with surfaces in the bore comprising two truncated conical surfaces fixed with respect to the member, which surfaces either both narrow or both widen in directions extending away from one another, bodies disposed in the bore and engaging one or the other of the conical surfaces, and spring means urging the bodies axially towards the narrower end of the respective conical surface.

14. A mechanism substantially as herein described with reference to and as shown in Figure 1, or with reference to and as shown in Figures 2, 3 and 4, or with reference to and as shown in Figure 5, or with reference to and as shown in Figure 6 of the accompanying drawings.