Manufacture of article having undercut internal surface

Details Manufacture of article having undercut internal surface Manufacture of article having undercut internal surface

1984-05-10

1986-09-09

Gilden, Leon

Metal deforming

By use of closed-die and coacting work-forcer

Forcing work into or within closed die; e.g., forging

72359, B21D 2200

Patent

active

046101551

DESCRIPTION:

BRIEF SUMMARY
This invention relates to manufacture of a hollow article having an internal surface of which at least part is undercut.
The invention is particularly applicable to the manufacture of an outer member of a constant velocity ratio universal joint, the joint comprising an outer member, having a closed end and affording an internal cavity with the internal circumferential surface thereof having axially extending grooves formed therein; an inner joint member disposed within the outer joint member and having an external surface having grooves therein which face the grooves in the outer member; a plurality of balls disposed one in each pair of grooves in the joint members for torque transmission therebetween; and a cage of annular form disposed between the joint members and having apertures in which the balls are located. The internal circumferential surface of the outer joint member between the grooves thereof is part-spherical, as is the external surface of the inner joint member, and the cage has external and internal part-spherical surfaces which engage the part-spherical surfaces of the joint members, and the shape of the grooves and/or the part-spherical surfaces of the cage and joint members is such that when the joint is articulated the balls are caused to occupy a plane which bisects the angle between the rotational axes of the joint members.
In such a universal joint, the grooves in the outer joint member may be undercut, by which we mean that the base of each groove is, at a position away from the free open end of the joint member, a greater radial distance from the rotational axis of the joint member than it is at the end of the member. The part-spherical internal surface of the outer joint member is undercut.
Because of the undercut of the part-spherical interior surface of the outer joint member, and possibly of the grooves, the joint member cannot be completely formed by a forging or extrusion process involving a forming tool inserted axially into the joint member, if the tool is in one piece. This is because a one piece forming tool cannot be withdrawn once the undercut configuration has been established. A one piece tool can be used to form the internal shape of the joint member adjacent the closed end thereof, but it is then necessary to produce the undercut shape by removal of material, usually by milling followed by a grinding process to give the required surface finish. It is also known to produce the undercut shape in a cold, warm or hot forming operation, not involving removal of material, by use of a forming tool which is made of many components and is collapsible for removal from the joint member after the undercut surfaces have been shaped. Ideally the outer joint member would then require no further treatment whatsoever, but in practice grinding is usually still required to produce the necessary surface finish.
Such collapsible forming tools as proposed hitherto have been made of a relatively large number of components. This means that the manner in which the tool collapses and is reassembled is complex, and it is difficult to ensure consistantly repeatable dimensional accuracy in the assembled tool and the resulting components. Wear in use adds to these difficulties.
It has also been proposed, for example in EP 0013545A, to use a tool which has relatively few parts, but does not define an external surface corresponding to the complete internal surface of the outer joint member. Gaps exist between the parts of the tool, into which material can flow during the extrusion process. Such material then has to be removed subsequently.
It is an object of the present invention to overcome or reduce such problems.
According to one aspect of the invention, we provide a tool for use in manufacture of a hollow article having an internal surface at least part of which is undercut, said tool comprising a plurality of elements having portions together adapted to define a substantially complete external surface having a configuration corresponding to that required in said internal surface, said elements

REFERENCES:
patent: 4406146 (1983-09-01), Suguli

Affiliated with

Also associated with

Rating

Manufacture of article having undercut internal surface does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Manufacture of article having undercut internal surface, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Manufacture of article having undercut internal surface will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-1010168