Abstract A mold assembly including an externally-tapered lower core member with an annular garter-spring-holding groove near its smaller-diameter top and an annular shoulder and seat near its larger-diameter bottom and an internally-tapered upper cavity mold member cooperatively form an annular die cavity having the shape desired for the elastomeric annular seal to be formed therein. Prior to molding the seal, the upper cavity mold member is retracted and moved out of alignment with the core member and replaced temporarily by a cylindrical loading device having an annular groove for receiving a pre-tensioned annular hollow helical tension spring and below it a cylindrical end portion adapted to receive an annular charge of elastomer. In carrying out the method of this invention, an annular mounting case is placed on the seat and a collar on the loading device is moved downward so as to push the spring and the annular elastomeric charge from the loading device onto the core member until the spring snaps into the annular groove of the core-member. The loading device is then retracted and moved out of alignment with the core member and the mold cavity member moved into alignment therewith and then moved downward into telescoping relationship with the core member, moving the spring downward out of the annular core groove and at the same time expanding it by circumferentially stretching it to open up spaces between its convolutions. As the spring is pushed downward, it pushes the elastomeric charge ahead of it into the mold chamber which shapes the seal and totally encloses the spring therein. Excess elastomer is ejected upward through the clearance between the mold and core members. Simultaneously therewith, the elastomer is pushed between the now-spaced convolutions of the expanded spring into the hollow of the spring, completely and uniformly filling it with elastomer. The upper mold cavity is then moved downward to the end of its stroke and an annular nose portion thereof cooperates with the shoulder as a fulcrum to bend the periphery of the case upward into a frusto-conical flange which enters the mold chamber and becomes bonded to elastomer flowing against its opposite sides. The end of the stroke ordinarily cuts off any flash adhering to the upper end of the seal, forming a sharp sealing lip thereon. The elastomer of the seal is then cured in the mold cavity by heating the mold assembly, after which the completed seal is ejected from the core member by a conventional stripper as the mold cavity member is retracted upward.
An apparatus for molding an elastomeric annular seal while enclosing an expanded annular hollow spring therein and completely filling the hollow thereof with elastomeric material, said apparatus comprising a mold core member having a tapered side surface, and a mold cavity member having a tapered mold cavity therein configured to mate with said core member, one of said members being movable axially toward and away from the other member whereby to close and open a mold chamber thereby formed between said members, said cavity having an enlargement therein with a configuration corresponding to the external configuration desired for the seal, said core member having a surface portion with a configuration corresponding to the internal configuration desired for the seal, said tapered mold core member having a smaller-diameter upper end and a larger-diameter lower end, said core member near said smaller-diameter upper end having an annular depression therein disposed remote from said larger-diameter lower end and configured to temporarily hold the spring before the expansion thereof by said core member.
Claim 2
Independent Claim
169 words
An apparatus for molding an elastomeric annular seal while enclosing an expanded annular hollow spring therein and completely filling the hollow thereof with elastomeric material, said apparatus comprising a mold core member having a tapered side surface, and a mold cavity member having a tapered mold cavity therein configured to mate with said core member, one of said members being movable axially toward and away from the other member whereby to close and open a mold chamber thereby formed between said members, said cavity having an enlargement therein with a configuration corresponding to the external configuration desired for the seal, said core member having a surface portion with a configuration corresponding to the internal configuration desired for the seal, said tapered mold core member having a smaller-diameter upper end and a larger-diameter lower end, said core member near said smaller-diameter upper end having an annular depression therein disposed remote from said larger-diameter lower end and configured to temporarily hold the spring before the expansion thereof by said core member.
Claim 3
Dependent Claim
70 words
An apparatus, according to claim 1, wherein said mold cavity member is movable out of alignment with said mold core member, and wherein a spring-loading device is movable into alignment with said mold core member and has a spring-holder with an annular spring-receiving recess and also has a spring-feeding element movable relatively to said spring holder to eject the spring from the spring-receiving recess thereof onto said mold core member.
Claim 4
Dependent Claim
39 words
An apparatus, according to claim 2, wherein said spring-receiving recess is spaced axially away from the end of said spring holder and thereby provides an annular elastomeric-charge-holding portion between said spring-receiving recess and the end of said spring holder.