Patent ID: 7137197

Claim:
A method of manufacturing a piston using a swaging tool, wherein the swaging tool has an opening formed therethrough, and the opening comprises a first inner portion extending from a first end of the swaging tool, wherein an inner diameter of the first inner portion is substantially constant; and a second inner portion extending from a second end of the swaging tool, wherein the second inner portion is tapered and is formed integrally with the first inner portion, such that an inner diameter of the second inner portion at the second end of the swaging tool is greater than an inner diameter of the second inner portion at the first inner portion, wherein the piston comprises a first member comprising a first ring portion having an outer diameter which is greater than the inner diameter of the first inner portion; a second ring portion connected to the first ring portion, wherein the second ring portion has an outer diameter which is about equal to the diameter of the first inner portion; and a third ring portion connected to the second ring portion; and a second member comprising an end portion having an outer diameter which is about equal to an inner diameter of the second ring portion; and a reduced diameter portion connected to the end portion, wherein the reduced diameter portion has an outer diameter which is less than the outer diameter of the end portion, the method comprising the steps of: positioning at least one portion of the first member within the second inner portion via the second end of the swaging tool; positioning at least one portion of the second member within the second inner portion via the second end of the swaging tool, such that the end portion contacts the second ring portion and the reduced diameter portion is substantially aligned with the first ring portion to create an annular space adjacent to the first ring portion and the reduced diameter portion wherein an end surface of the end portion contacts a receiving surface of the third ring portion, such that the annular space is a groove formed between the first ring portion and the reduced diameter portion; and subsequently swaging the first ring portion by moving the first ring portion in a direction toward the first end of the swaging tool, such that at least a portion of the first ring portion is positioned within at least a portion of the annular space to fix the first member to the second member and such that a third portion of said second member has an outer diameter substantially equal to the outer diameter of said second ring portion of said first member.