GB2159207A

GB2159207A - Ball member for a ball joint

Info

Publication number: GB2159207A
Application number: GB08512715A
Authority: GB
Inventors: Agustin Morales Arnaez
Original assignee: Industria Auxiliar Alavesa SA
Current assignee: Industria Auxiliar Alavesa SA
Priority date: 1984-05-24
Filing date: 1985-05-20
Publication date: 1985-11-27
Also published as: FR2564917B3; FR2564917A1; DE3518615A1; ES279461U; ES279461Y; GB8512715D0

Abstract

A ball member for a ball joint comprising a ball head and a stem made of metal, at least a part of the surface of the ball member being covered with a layer (5) of plastics material. The entire ball member may be covered. <IMAGE>

Description

SPECIFICATION Ball member for a ball joint This invention relates to a ball members for a ball joint, which is particularly intended for working in the open air or in corrosive atmospheres.

At the present time, ball member for ball joints intended for such purposes are made of carbon steels, which results in a lack of resistance to atmospheric and chemical agents. In consequence, there is surface oxidation of the ball members, thus swiftly reducing or even destroying their ability to operate.

The idea was originally conceived of making these parts of stainless steels, but this gave rise to two basic problems. The first of these problems was of a technical nature since, although the material served its purpose and had the required life, it was not feasible to assemble the different parts of the ball joints by normal riveting methods, because of the risk of cracking. The second problem was of an economic nature, in that both the raw material, i.e. the stainless steel, and the manufacturing process which had to be employed were so expensive that it was preferable to modify the entrie design of the ball joints to permit liquid tight operation of the latter.

Another solution which was attempted was to coat areas exposed to weather with a polytetrafluoroethylene paint. This solution, however, did not make it possible to meet the required dimensional tolerances, so that this solution was rejected.

Another possible solution to the problem described above is based on making the ball member of two different materials. This was originally done by inserting a metal rod into a ball head of plastics material. This procedure involves two fundamental disadvantages, however, one of which is the difficulty of continuously achieving the required dimensions of the balls, because of the contraction of the plastics material, while the other is the limited strength of the connection between the two parts.

The present invention seeks to provide a ball member which will overcome the problems mentioned above and which will be resistant to chemical and atmospheric attack and at the same time have the required mechanical strength.

According to the present invention, there is provided a ball member for a ball joint comprising a ball head and a stem made of metal, at least a part of the surface of the ball member being covered with a layer of plastics material.

Preferably the said layer is a film.

With a construction of this kind, the mechanical strength is provided by the metal part of the ball member, while resistance to friction and to chemical and atmospherical action is provided by the plastics film, so that an assembly is obtained which has mechanical strength and chemical resistance.

The metal part of the ball member can preferably be machined on an automatic lathe. It can then be coated with plastics material in an injection moulding machine, this plastics material being provided in the areas where resistance to friction and to chemical and atmospheric agents is required.

The metal part of the ball member will have dimensions and a configuration close to the final dimensions and configuration of the finished ball member, both as regards the ball head and as regards the stem.

The said layer of plastics material preferably covers the whole of the surface of the ball head and of the stem.

The stem may extend to a rear plate and the ball member may comprise an end rod which extends to the rear plate. In this case, the arrangement may be that the surfaces of the rear plate and end rod are not covered by the said layer.

The invention is illustrated, merely by way of example, in the accompanying drawings, in which: Figure 1 is a side view of a ball member according to the present invention, and Figure 2 is a section on the line ll-il in Fig.

1.

Referring to the drawings, a ball member according to the present invention comprises a ball head 1 and a stem 2 extending to a rear plate 3.

The ball member is composed of a metal body 4 (Fig. 2) comprising the ball head 1 and the stem 2, which body can be machined on an automatic lathe. Around the metal body 4 there is disposed a thin sheet-like layer 5 of plastics material which can be formed by injection moulding.

The layer 5 of plastics material is constituted by a thin film which covers the entire area of the body 4 which is subjected to friction and which is also subjected to the action of atmospheric or chemical agents. The covering 5 could be continued over the rear plate 3 and over an end rod 6 if these parts were also exposed to the action of atmospheric or chemical agents.

With the construction described, a ball member is obtained in which mechanicai strength is provided by the metal body 4, while resistance to friction and to atmospheric and chemical attack is provided by the covering 5 of plastics material.

The thickness of the plastics covering 5 may vary in dependence on the use to which the ball member is put, and it may in addition vary in different parts of the ball member.

The nature of the invention and the manner in which it can be put into practice having been sufficiently described, it should be stated that the arrangements indicated above are capable of modifications in respect of details provided that the fundamental principle, as defined in the claims, is not changed.

Claims

1. A ball member for a ball joint comprising a ball head and a stem made of metal, at least a part of the surface of the ball member being covered with a layer of plastics material.

2. A ball member as claimed in claim 1 in which the said layer is a film.

3. A ball member as claimed in claim 1 or 2 in which the layer of plastics material has been injection moulded.

4. A ball member as claimed in any preceding claim in which the said layer of plastics material covers the whole of the surface of the ball head and of the stem.

5. A bail member as claimed in any preceding claim in which the stem extends to a rear plate.

6. A ball member as claimed in claim 5 in which the ball member comprises an end rod which extends to the rear plate.

7. A ball member as claimed in claim 6 in which the surfaces of the rear plate and end rod are not covered by the said layer.

8. A ball member for a ball joint substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

9. Ball member for ball joints, characterised in that it comprises a ball body and a stem of metal, with a configuration and dimensions close to those of the part which is to be obtained, and a covering of plastics material of slight thickness, which is applied by injection moulding to the areas exposed to friction and to the action of atmospheric or chemical agents.

10. Any novel integer or step, or combination of integers or steps, hereinbefore described and/or shown in the accompanying drawings irrespective of whether the present claim is within the scope of, or relates to the same or a different invention from that of, the preceding claims.