GB2160935A

GB2160935A - Preventing movement of a component along the bore of a housing

Info

Publication number: GB2160935A
Application number: GB08511364A
Authority: GB
Inventors: Stig Hallerback
Original assignee: SKF AB
Current assignee: SKF AB
Priority date: 1984-05-04
Filing date: 1985-05-03
Publication date: 1986-01-02
Also published as: SE8402412D0; SE437413B; GB2160935B; GB8511364D0; DE3514142A1; DE3514142C2

Abstract

A component 13 eg the outer ring of a roller bearing is disposed in the bore 11 of a plastics housing 10. A metal reinforcing element 14, embedded in the plastics, surrounds the bore 11. A locking element 16 also disposed in the bore 11 includes a plurality of radially outwardly extending elastically bendable teeth 17. The bore 11 has longitudinal grooves 15 which expose part of the reinforcing element 14 sufficiently to allow at least some of the teeth 17 to engage in recesses of the reinforcing element. <IMAGE>

Description

SPECIFICATION Preventing movement of a component along the bore of a housing The invention relates to preventing movement of a component along the bore of a housing.

Housings for mounting components such as bearings or other machine elements are commonly made from cast iron or other durable and hard materials. The performance of such housings is usually quite satisfactory but during recent years there have moves to make housings of other materials such as plastics.

There are a number of reasons for this but an important one for using plastics is that the manufacturing process is simplified leading to a relative cheap product.

A drawback to the use of plastics for housings is that the component disposed in the housing is often made of steel and the coefficient of thermal expansion of plastics is greater than that of steel. Because of that and because of the softness of plastics, problems arise with retaining a component, particularly with large temperature variations.

Patent Specifications SE 383 554, GB 1502996 and GB 1585721, disclose a construction of a plastics housing which has a bore and a longitudinally extending steel helix which surrounds the bore. This steel helix reinforces the bore and overcomes the problems relating to radial changes but still leaves the problem relating to longitudinal movement.

In a known construction, a component or machine element has been axially locked in position in the bore, that is prevented from moving along the bore of the plastics housing by providing an annular groove in the bore next to the component. A locking ring, for example a Seeger ring, is inserted into the groove and holds the component in place.

This is a reliable and effective way of axially locking the component in position. However, to produce the annular groove by a process step such as turning is an undesirable complication and negates a big advantage of using plastics, which is that once the article has been formed no further process steps are required.

Components are often held in position in the bores of cast metal housings by locking washers. Such a washer has radially outwardly extending teeth and when it is pushed into the bore up to the component, the teeth dig into the bore and prevent movement along the bore in the opposite direction. However such a washer is not suitable for a plastics housing because the plastics is too soft and after a while it will give way.

The invention provides an assembly comprising a housing having a bore, a component which is disposed in the bore and a locking element, which is also disposed in the bore and prevents movement of the component in one direction along the bore, the housing being of plastics and having a metal reinforcing element which is embedded in the plastics of the housing and surrounds the bore, wherein the locking element has aa plurality of radially outwardly extending elastically bendable teeth and the bore has a plurality of longitudinally extending grooves which expose part of the reinforcing element sufficiently to allow at least some of the teeth of the locking element to engage in recesses of the reinforcing element.

Preferably, the reinforcing element is a longitudinally extending helix.

An embodiment of the invention will now be described by way of example and with reference to the accompanying drawings, of which: Figure 1 is part of alongitudinal section through an assembly according to the invention; and Figure 2 is part of a view from the left hand side of the assembly shown in Fig. 1.

The drawings show a plastics housing 10 having a bore 11 with a cylindrical surface 1 2. The bore surface 1 2 provides a seating surface for a machine element or component 1 3 disposed in the bore 11, such as the outer ring of a rolling bearing.

Embedded in the plastics of the housing 10 is a longitudinally extending steel helix 14, which surrounds the bore 11 and acts as a reinforcing element.

The bore 11 has a plurality of longitudinally extending grooves 1 5 which expose part of the helix 14.

Also disposed in the bore 11 is a locking washer 1 6 which has a plurality of radially outwardly extending elastically bendable teeth 1 7. The teeth 1 7 are arranged one in each groove 1 5. The central body of the washer 16 is shown abutting the component 1 3 with the teeth 1 7 being inclined away from the component and engaging in the recesses of the helix 14 between the individual coils to prevent longitudinal movement of the component along the bore 11 in the direction from the component to the washer.

During assembly, the locking washer 1 6 is pushed into the bore 11 of the housing 10 in the direction of arrow A. The grooves 1 5 of the bore 11 expose the helix 1 4 sufficiently for the teeth 1 7 to indent the plastics in the recesses between the coils. Each tooth 17, as the washer 1 6 is pushed further into the bore 11, elastically bends, as indicated by the broken lines, to pass each coil, and then recovers to indent the plastics in the next recess. In the final position as shown the teeth 1 7 indent the plastics in the recesses between adjacent coils of the helix 14 and abut one of the coils so preventing movement out of the bore 11.

The number of the teeth 1 7 and grooves 1 5 is not critical but six is satisfactory. In some circumstances not all of the teeth 1 7 will abut the coils of the helix 14. Washers 1 6 can be used having a smaller member of teeth 1 7 than there are grooves 1 5. Also washers 1 6 can be used having a greater number of teeth 1 7 that there are grooves 1 5.

The teeth 1 7 which then do not extend into the grooves 1 5 will dig into the plastics between the grooves and provide a similar but less effective action.

The reinforcement element 14 need not be a helix and can be of some other design, for example a tubular member having internal annular ridges.

Claims

1. An assembly comprising a housing having a bore, a component which is disposed in the bore and a locking element, which is also disposed in the bore and prevents movemetn of the component in one direction along the bore, the housing being of plastics and having a metal reinforcing element which is embedded in the plastics of the housing and surrounds the bore wherein the locking elernent has a plurality of radially outwardly extending elastically bendable teeth and the bore has a pluraltiy of longitudinally extending grooves which expose part of the reinforcing element sufficiently to allow at least some of the teeth of the locking element to engage in recesses of the reinforcing element.

2. An assembly as claimed in Claim 1, wherein the reinforcing element is a longitudinally extending helix.

3. An assembly substantially as herein described with reference to and as shown in the accompanying drawings.

4. A means for axially fastening a machine element such as a bearing, in a preferably cylindrical seat, mainly consisting of a plastics or other soft material, and incorproating reinforcement in the form of a steel helix or the like within the surface thereof, characterised thereby, that axial grooves are provided in the plastics material, which grooves expose the reinforcement, and that a locking washer provided with teeth is pressed towards the machine element, whereby some of the teeth will be brought to engagement against the reinforcement thereby locking the washer and the machine element against axial displacement.