IE47535B1 - Pot-shaped or roll diaphragm - Google Patents

Abstract

A pot-shaped or roll diaphragm made of rubber or rubber-like plastics material having a thickened outer edge 4 forming a clamping bead and textile reinforcing plies 1 extending through the clamping bead, has an open circular ring groove 6 formed in the clamping bead to extend in or substantially in an axial direction towards the side forming the frusto- conical pot-shaped part 2.

Description

The present invention relates to a pot-shaped or roll ' diaphragm made of rubber or rubber-like plastics materials having a thickened outer edge forming a clamping bead apd textile reinforcing plies extending through the clamping bead.

The utility value of such diaphragms used in pressure medium control and operating devices, cylinders, valves and the like largely depends upon the nature and arrangement of the reinforcing plies. The embedding of reinforcing elements constructed mainly as a coherent fabric, provides such diaphragms with protection against mechanical or corrosive influences. To maintain this state in all parts, however, necessitates accurate alignment of the plies during the production of the diaphragms in the pressing moulds provided therefor; yet in this respect different requirements exist lb at different parts of the diaphragm. Thus, for example, in ' acute arcs of curvature and other .abrupt changes of direction of the diaphragm walls, the undesired phenomena occurs that the ply fabrio tends to be drawn towards the inner fold side and in extreme cases assumes a position on the surface thereof.

This danger, the effects of which results In leakages and also premature destruction of the diaphragms conoemed during use, to a particular extent consists in the transition bend from the clamping bead towards the cylindrical or conical pot -3part set at an obtuse angle thereto. The unilateral reductions in the wall thicknesses caused by the positional changes in the fabric in the pressing mould particularly in this region subject to constant bending lead to the fabric becoming detached and to thread breakages which causes the whole diaphragm to fail. Hence it is an object of the invention to ensure the accommodation of the fabric plies within the diaphragm walls and as direct result of this to maintain them in their original undamaged state over longer periods of time and thereby enable same to be subjected to more frequent stress changes than hitherto.

According to the present invention there is provided a pot-shaped or roll diaphragm made of rubber or rubber-like plastics materials having a thickened outer edge forming a clamping bead and textile reinforcing plies extending through the clamping bead, wherein an open circular ring groove is formed in the clamping bead in or substantially in the longitudinal axial direction of the diaphragm from the outer surface of the frusto-conical pot-shaped part.

Said groove preferably extends up to the reinforcing plies. The plies are normally centrally embedded in the walls of the diaphragm and the ring groove has a depth corresponding to half the thickness of ths bead in the region of its outer periphery. Its cross-sectional shape is expediently substantially rectangular having a width corresponding in order of magnitude to a fraction of the thickness of the diaphragm wall. In accordance with an alternative embodiment of the invention, the ring groove instead may be provided with an outwardly flared cross-section.

The invention makes provision for supporting the reinforcing plies during the manufacture of the diaphragm within the pressing moulds from the outside end to retain them in the critical guiding regions spaced from the mould wall defining the smaller radius of curvature. The adverse contact of the reinforcing plies vrith the mould wall surface is thereby prevented. Also, the elastomeric material supporting the fabric increases the resistance of the completed diaphragm to fatigue fissures in the tending regions. Any adverse influences on the behaviour of the diaphragms during use cannot emanate from the open ring groove, because the latter does not directly participate in the static clamping between the associated rigid housing parts or flanges in the bending deformations and does not exert any direct effect on the movement course. It may thus prove expedient to edge the ring groove on both sides by surface elevations drawn up beyond its edge faces. In the installed state, these elevations are displaced into the ring groove, so that the ring groove itself at least partly is filled and sealed towards the outside.

The present invention will be further illustrated, by way of 'example, with reference to the accompanying drawing, in which the single Figure shows a segment of a pot-shaped diaphragm in axial section.

The diaphragm shown is made of natural or synthetic rubber and has an embedded textile reinforcing ply 1.

According to shape and function the diaphragm has a frustoconical pot-shaped part 2, a clamping bead 4 eet with a transition arc 5 and an inner base 5 abutting against a rigid diaphragm disc or alternate piston member, not shown further. -5The movements of the diaphragm extend in the form of space changes between inner base 5 and clamping bead 4 substantially only within the pot-shaped part 2. In the clamping bead 4 · extending from the surface facing the pot-shaped part 2, an open ring groove 6 of substantially rectangular cross-section is formed. The ring groove in depth extends to the reinforcing ply 1, which, in the embodiment shown, corresponds to about half the bead thickness in ite circumferential region. Its width is determined by the moulding tool supporting the reinforcing fabric within the pressing mould during the production of the diaphragm and in comparison with its depth may be of lesser order of magnitude. The edge faces of the ring groove are drawn up in the shape of surface elevations 16.

Claims (7)

1. CXAIMS

1. A pot-shaped or roll diaphragm made of rubber or rubber-like plastics materials having a thickened outer edge form j ng a clamping bead and textile reinforcing plies 5 extending through the clamping bead, wherein an open circular ring groove is formed in the clamping bead in or substantially in the longitudinal axial direction of the diaphragm from the outer surface of the frusto-conical pot-shaped part.

2. A diaphragm as claimed in claim 1, in which the ring 10 groove extends substantially to the reinforcing plieB.

3. · A diaphragm according to claim 1, in which the ring groove has a depth corresponding substantially to half the bead thickness in the region of its outer periphery.

4. · A diaphragm as claimed in claims 1, 2 or 3, in which 15 the ring groove is edged by*surface elevations raised above its edge faces.

5. · A diaphragm as claimed in any one of claims 1 to 4» in which the ring groove has a substantially rectangular cross-sectional shape and a width corresponding to a fraction 20 of the wall thickness of the diaphragm.

6. , A diaphragm as claimed in any one of claims 1 to 4, in which the ring groove has an outwardly flared cross-section. -7

7. i. pot-shaped diaphragm substantially as hereinbefore described with reference to and as illustrated in the accompanying drawing.