GB2173281A - Clamping arrangement for torsionally securing a shaft-and- hub connection - Google Patents

Abstract

The clamping arrangement is composed of an outer clamping ring (3) and an inner clamping ring (4) with cylindrical surfaces (7, 9) which move into contact with the shaft and the hub, respectively, as well as comprising opposed, oppositely inclined conical surfaces (8a, 8b, 10a, 10b) corresponding to those of two laterally arranged thrust rings (11, 12) which are furnished with through-bores (14) and threaded bores (15) for a rim of tightening screws (13), as well as with a reaction ring (18) forming a support for thrust screws for push out of the thrust rings (11, 12). The reaction ring (18) is designed as an independent intermediate ring which engages into oppositely disposed grooves (19, 20) in the clamping rings (3, 4) and which thereby provides positive engagement between them in an axial direction. <IMAGE>

Description

SPECIFICATION Clamping arrangement for a torsionally secured shaft-and-hub connection The present invention relates to a clamping arrangement for a torsionally secured connection of a hub with a shaft, composed of a slotted outer clamping ring with oppositely inclined inner cone surfaces and a cylindrical peripheral surface which gets into contact with a cylindrical bore surface of the hub, and comprising a slotted inner clamping ring which is arranged concentrically within the outer clamping ring and which includes oppositely inclined outer cone surfaces and a cylindrical bore surface which moves into contact with a cylindrical peripheral surface of the shaft, as well as comprising two preferably closed, double-conical thrust rings which engage from opposed sides between the mentioned clamping rings and which contain through-bores, that is bores for screwing in a rim of tightening screws, by which the thrust rings are axially movable towards its other for radially expanding or compressing the clamping rings, and comprising a reaction ring which is located between the said clamping rings and the thrust rings and which contains through-bores for the tightening screws, the said reaction ring engaging into circumferemtial recesses in the clamping rings designed between the cone surfaces.

Clamping arrangements of the type described permit to detachably connect shafts and hubs in a particularly straightforward manner. To this effect, the clamping arrangements must transmit high torques on a very small mounting space and ensure exact centering of shaft and hub.

To reach this aim, a known clamping arrangement (German patent specification 2 137 313) on which the present invention is based provides for the angle of the cone surfaces at the clamping rings and the thrust rings to be kept so small that it is within the limits of automatic locking. From this results a great ratio of transmission so that there occur comparatively great biassing forces and a high transmittable torque of the clamping arrangement in respect of a defined number of tightening screws. To be in a position to release the clamping arrangement, a reaction ring is inserted into dovetailed recesses of the clamping rings, on which reaction ring tightening screws may take support which are screwed into threaded bores for push-out in the one thrust ring, in order to enable release of the thrust ring from its clamping position by means of the tightening screws.In addition thereto, the reaction ring serves to provide positive engagement between the inner and the outer clamping ring to form an undetachable radially movable unit. However, the known clamping arrangement bears a great number of disadvantages which counteract its use in practical operations. E.g., the dovetailed recesses in which the reaction ring is supported do not achieve exact axial fixation between the inner clamping ring and the outer clamping ring. Instead, the expanding of the outer clamping ring and the compressing of the inner clamping ring causes an axial clearance in the support of the reaction ring so that axial shift may occur between inner and outer clamping ring during the clamping action. A like axial shift is extremely undesirable, since it may result in axial restraint in the hub member, for example.The machining of the dovetailed recesses in the clamping rings and the corresponding cone surfaces at the reaction ring entails much effort and permits only limited machining accuracy. Therefore, precentering and the attainable truth of running after the clamping action are insufficient in the known clamping arrangement. When releasing the clamping arrangement, the reaction ring may get jammed with its cone surfaces in the dovetailed recesses and consequently complicate the disassembly to a large degree. The same may take place during the assembly of the clamping arrangement, if the mounting tool engages only one of the clamping rings. Likewise the detachment of the rear thrust ring of the known clamping arrangements by hitting the screw heads of the released tightening screws is insufficient, since this may easily cause damage to the tightening screws and the screw-in thread.

Further, there is known a clamping arrangement comprising a double-conical inner clamping ring with a radial centering collar arranged centrically in the apex of the cone surfaces and with a radially spaced-away outer clamping ring assembly with opposed inner cone surfaces and with closed double-conical thrust rings inserted concentrically into the clamping rings on either side and including corresponding cone surfaces (German patent specification 26 11 201), wherein the radial centering collar is held with its cylindrical outer diameter in a centrically arranged circumferential groove of the slotted one-part outer clamping ring.

Thereby, the inner and the outer clamping ring are meant to form an undetachable unit, and it is meant to accomplish the transmission of high torques and good centering accuracy and truth of running. It is the shortcoming of this known arrangement, though, that it requires expensive manufacture. Thus, the inner clamping ring with the radial centering collar expediently permits but to be made as a forging, which method entails comparatively high costs. Besides, the machining of the inner clamping ring necessitates re-chuck at least one time. The consequence thereof being a reduction of manufacturing accuracy and increased machining efforts.The one-part design of the inner clamping ring with the centering collar-the inner clamping ring being in addition of unslotted design -furthermore is disadvantageous in that there occurs unfavourable distribution of the surface pressure in particular between inner clamping ring and shaft, what limits the ability of transmission of high torques. Release of the known clamping arrangement from automatic locking can be performed without additional tools, since the tightening screws can be supported on the radial centering collar which likewise contains threaded bores for the push-out of the rear thrust ring.

It is an object of the present invention to provide a clamping arrangement of the type initially referred to wherein the indicated shortcomings are avoided. More specifically, the instant invention is destined to provide a clamping arrangement which is economical in manufacture and the individual component parts of which do not necessitate long and costly machining operations. It is another object of the present invention to accomplish a maximum uniform distribution of the radial clamping forces over the entire length of the clamping rings, in order to thereby enable the transmission of a highest possible torque. It is finally aimed at that the clamping arrangement ensures exact precentering of shaft and hub already in the clamped condition.

This object will be achieved by the present invention in that the reaction ring comprises plane-parallel lateral surfaces and cylindrical concentrical inner and outer surfaces and that the recesses in the clamping rings are designed as grooves with rectangular cross-section, into which the reaction ring engages in a true-to-fit way.

In the inventive clamping arrangement, the inner clamping ring and the outer clamping ring are rigidly interconnected in axial direction by means of the reaction ring engaging into the grooves, without their ability to expand or compress in radial direction being limited thereby. This affords a number of advantages by which the inventive clamping arrangement distinguishes over prior-art arrangements. E.g., the inventive clamping arrangement affords particularly great ease of assembly because the clamping rings cannot displace relative to one another in axial direction and because there is no occurrence of radial spreading forces due to which the clamping arrangement may be jammed during the assembly.Furthermore, there is enabled precise axial positioning of the hub in relation to the shaft, since the clamping rings are not even during the clamping action allowed to move relative to one another in axial direction. Thus, the introduction of axial tensions into the hub member will be prevented reliably as well. In a radial direction, too, the inner clamping ring and the outer clamping ring are supported on one another by the cylindrical reaction ring already prior to clamping and are exactly centered relative to one another so that during insertion of the clamping arrangement between a shaft and a hub, the weight of the hub can be received and exact precentering can be obtained.Owing to the isolation of the clamping rings and the reaction ring, the radial deformability of the clamping rings will be maintained without restriction, thus allowing to attain a particularly uniform distribution of the radial forces during clamping. The inventive clamping arrangement is very favourable also in respect of its manufacture. This is because the clamping rings, the thrust rings and the reaction ring are simple turned pieces which permit to be manufactured easily and with great accuracy as tabbed pieces made from semifinished tubular products entailing little expenditure for material and cutting operation. The machining of all components can be performed in one single chucking operation.

The necessary rigidity needed by the reaction ring in order to be able to receive the axial forces occurring during the release action will be obtained owing to the present invention by arranging for the ratio of width to height of the rectangular cross-section of the reaction ring to be equal to or greater than 0.7.

Owing to the advantageous improvement disclosed in the subsequent subclaims, the inventive clamping arrangement can be released from automatic locking without the assistance of special tools by mere transposition of individual tightening screws, the said transposed tightening screws taking in each case support on the thrust ring to be detached and on the reaction ring. In doing so, the plane parallel design of the reaction ring and the rectangular cross-section of the grooves avoid the occurrence of radial jamming forces so that the clamping arrangement can be dismounted easily after detachment of the thrust rings.

Further details of the present invention can be gathered from the following description of a referred embodiment illustrated in the accompanying drawings. In the drawings, Fig. 1 is a longitudinal cross-section through an inventive clamping arrangement, Fig. 2 is a cross-section taken along the axis 2-2 in Fig. 1, Figs. 3 and 4 are partial cross-sectional views of the clamping arrangement according to Fig. 1 displaying further details of the pushout of the thrust rings for the purpose of release of the clamping arrangement, and Fig. 5 is a graph depicting the distribution of the radial pressures or the radial forces alongside of a longitudinal cross-section of the clamping arrangement according to Fig. 1.

As is shown in the drawings, the clamping arrangement serves to connect a shaft 1 with any rotating member desired, the hollow hub 2 of which can be partly seen. The clamping arrangement is placed between the cylindrical outer surface 1a of the shaft 1 and the cylindrical inner surface 2a of the hub 2. It comprises an outer clamping ring 3 and an inner clamping ring 4 which is located coaxially to the latter. Both clamping rings 3, 4 in longitudinal direction are slotted at 5 and, respectively, at 6, in order to enable expanding and compressing of their diameters.

The outer clamping ring has a cylindrical peripheral surface 7 which gets into contact with the cylindrical inner surface 2a of the hub 2, as well as opposed and oppositely conical surfaces 8a, 8b which converge relative to the plane of the transverse centre line of the clamping arrangement. Corresponding thereto, the inner clamping ring 4 comprises a cylindrical bore surface 9 moving into contact with the cylindrical outer surface 1 a of the shaft 1, and comprises also oppositely conical surfaces 10a, 10b on its oppositely lying outer side, the inclination thereof extending opposite to that of the conical surfaces 8a, 8b of the outer clamping ring 3.

Two conical pressure rings 11 and 12 being of conical design on either side corresponding to the design of the surfaces 8a, 8b, 10a and 10b are arranged opposite to one another laterally between the clamping rings 3 and 4.

Tightening screws 13, merely one thereof being illustrated in Fig. 1, are arranged along a rim of through-bores 14 in one of the thrust rings, for instance in thrust ring 11, and are screwed with their threaded stem into corresponding threaded bores 15 in the other thrust ring 12.

Inside of the clamping rings 3, 4 and in a layer between the thrust rings 11, 12, a reaction ring 18 is located which is apt as a support for thrust screws 16 and 17 in the fashion shown in Figs. 3 and 4. The reaction ring 18 comprises plane parallel lateral surfaces and cylindrical, concentrical inner and outer surfaces and is received with its radially inner and radially outer edge in precise fit in grooves 19, 20 of rectangular cross-section which are indented by machine operation into the two clamping rings 3 and 4 in the plane of the centre line between the opposed conical surfaces 8a, 8b and 10a, 10b, respectively.This way, the reaction ring 18 is with its outer diameter positively engaged in the groove 19 in the clamping ring 3 and with its inner diameter positively engaged in the groove 20 in the clamping ring 4, whereby it couples the two clamping rings 3, 4 to one another undisplaceably in axial direction, without impairing their deformability in radial direction, though.

The reaction ring 18 contains through-bores 21 at the level of the tightening screws 13 of the clamping arrangement, and it disposes of a solid wall in at least two substantially diametrally opposite locations 22 for the purpose of supporting the ends of the screws 16 which, for push-out of the thrust ring 11, can be screwed into threaded bores 23 in the thrust ring 11 that are in alignment with the locations 22 (Fig. 4). Furthermore, said reaction ring 18 is furnished with two threaded bores 23a which are spaced at a distance from the locations 22 previously referred to and into which screws 17 can be screwed for push-out of the thrust ring 12 after the thrust ring 11 has been pushed out and removed.

To this effect, the ends of the screws 17 bear against a solid wall portion of the thrust ring 12 (Fig. 3).

Handling of the described clamping arrangement is easy. During mounting, the pre-assembled clamping arrangement that is loosely held together by the tightening screws 13 is slid into the annular space between the outer surface la of the shaft 1 and the inner surface 2a of the hub 2. In this operation already, the hub weight is received through the outer clamping ring 3, the reaction ring 18 and the inner clamping ring 4, and exact precentering of the hub 2 relative to the shaft 1 is accomplished already.

Subsequently, the tightening screws 13 distributed in a rim will be tightened evenly, thus causing the thrust rings 11, 12 to move between the conical surfaces 8a, 10a and 8b, 10b and to bring about expanding of the outer clamping ring 3 as well as compressing of the inner clamping ring 4. Thereby, corresponding to the tightening torque of the tightening screws 13 there is obtained radial pressure between the shaft 1, the clamping arrangement and the hub 2, which radial pressure generates the friction force required to transmit a high torque. During clamping, it is the purpose of the reaction ring 18 to prevent axial displacement between the outer clamping ring 3 and the inner clamping ring 4. Therefore, the hub 2 permits to be positioned on the shaft 1 accurately in axial direction, and impairment of the truth of running due to axial dislocation of the clamping rings is avoided.

Release of the clamping arrangement takes place in a simple manner, without requiring any special tools therefor. First of all, the tightening screws 13 will be removed. Then, one after the other, as is shown in Figs. 3 and 4, the thrust ring 11 and then the thrust ring 12 will be pushed out. The radial pressure between the shaft 1, the hub 2 and the clamping arrangement will thereby be removed completely so that the hub can be taken from the shaft 1 easily.

Fig. 5 of the drawings displays the distribution of the radial pressures, that is the radial forces, alongside any peripheral line of the described clamping arrangement. The curve A in the upper diagram of this Figure shows the radial pressure P1 by which the outer clamping ring 3 acts on the hub 2. As can be taken from the illustration, the pressure P1 substantially is of a constant value which slightly decreases only in the area of the reaction ring 18. A like uniform pressure distribution enables to make good use of the resistance to pressure of the material and thus to transmit correspondingly high torques. The curve B in the lower diagram shows the pressure P2 at the inner clamping ring 4 which has a similarly favourable course.

For the sake of comparison, the furthermore drawn dotted curves C and D display the distribution of the radial pressure as it results in the priorly known clamping arrangement according to German patent specification 26 11 201. In this clamping arrangement, the stiffness of the centering collar arranged at the inner clamping ring prevents the development of a radial pressure in the intermediate area of the inner clamping ring, as is shown in the two curves D. Accordingly, comparatively too high an amount of pressure will arise at the intermediate area of the outer clamping ring which will decrease markedly towards the fringe areas of the outer clamping ring. In consequence of the uneven distribution of pressure and friction force lacking as a result, this known clamping arrangement affords to transmit a smaller torque only.

Claims (5)

1. A clamping arrangement for the torsionally-secured connection of a hub with a shaft, composed of a slotted outer clamping ring with oppositely inclined inner cone surfaces and with a cylindrical peripheral surface which gets into contact with a cylindrical bore surface of the hub, and comprising a slotted inner clamping ring which is arranged concentrically within the outer clamping ring and which includes oppositely inclined outer cone surfaces and with a cylindrical bore surface which moves into contact with a cylindrical peripheral surface of the shaft, as well as comprising two double-conical thrust rings which engage from opposed sides between the mentioned clamping rings and which contain through-bores, that is bores for screwing in a rim of tightening screws, by which said thrust rings are axially movable towards its other for radially expanding or compressing the clamping rings, and comprising a reaction ring which is located between the said clamping rings and the thrust rings and which contains through-bores for the tightening screws, the said reaction ring engaging into circumferential recesses in the clamping rings designed between the cone surfaces, in which the reaction ring includes plane parallel lateral surfaces and cylindrical concentrical inner and outer surfaces and in which the recesses are designed as grooves of rectangular cross-section into which the reaction ring engages in a trueto-fit way.

2. A clamping arrangement as claimed in claim 1, in which the ratio of width to height of the rectangular cross-section of the reaction ring is equal to or greater than 0.7.

3. A clamping arrangement as claimed in claim 1 or claim 2, in which the reaction ring comprises a solid wall in areas being in alignment with at least two threaded bores provided for thrust screws in a lateral thrust ring.

4. A clamping arrangement as claimed in any one of the preceding claims, in which the reaction ring contains threaded bores for at least two thrust screws which are in alignment with one solid wall area of a lateral thrust ring.

5. A clamping arrangement for the torsionally-secured construction of a hub with a shaft substantially as described herein with reference to the accompanying drawings.