Method of gripping tubular members during forming operations and associated apparatus

A method of gripping a metal tubular member during a forming operation comprising

• providing an outer tool having a recess structured to receive an end of said tubular member,
• inserting a resilient mandrel into said end of said tubular member, the resilient mandrel employing a first resilient material having a first durometer hardness in the end portions of said resilient mandrel and a second resilient material having a second durometer hardness less than the durometer hardness of said first resilient material in the portions of said resilient mandrel disposed between said mandrel end portions,
• inserting said tubular member into said recess and applying a compressive force to said resilient mandrel in a direction aligned generally axially of said tubular member to establish transverse expansion of said resilient mandrel to clamp said end between said mandrel and said outer tool recess, and
• forming said tube while maintaining said clamping of said end.

A method of gripping a metal tubular member having multiple hollow extrusion during a forming operation comprising

• providing an outer tool having a recess structured to receive an end of said tubular member,
• inserting a resilient mandrel into each of said end of said multiple hollow metal extrusion,
• inserting said tubular member into said recess and applying a compressive force to each of said resilient mandrels in a direction aligned generally axially of said tubular member to establish transverse expansion of said resilient mandrel to clamp said end between said mandrels and said outer tool recess, and
• forming said tube while maintaining said clamping of said end.

A method of gripping a tubular member during a forming operation comprising

• providing an outer tool having a recess structured to receive an end of said tubular member,
• inserting a resilient mandrel into said end of said tubular member,
• inserting said tubular member into said recess and applying a compressive force to said resilient mandrel in a direction aligned generally axially of said tubular member to establish traverse expansion of said resilient mandrel to clamp said end between said mandrel and said outer tool recess, and
• forming said tube by stretching said tubular member substantially at or beyond its yield point and then bending said tubular member while maintaining said clamping of said end.

A method of gripping a metal tubular member during a forming operation comprising

• providing an outer tool having a recess structured to received an end of said tubular member,
• inserting a resilient mandrel into said end of said tubular member,
• inserting said tubular member into said recess and applying a compressive force to said resilient mandrel in a direction aligned generally axially of said tubular member to establish traverse expansion of said resilient mandrel to clamp said end between said mandrel and said outer tool recess,
• inserting a mechanical lock to maintain the applied compressive force to said resilient mandrel until the forming operation is substantially complete, and
• forming said tube while maintaining said clamping of said end.

Apparatus for gripping a tubular member during a forming operation comprising

• an outer tool having a recess with lateral walls of generally complementary configuration to the outer surface of said tubular member,
• a resilient mandrel receivable within said end of said tubular member to be gripped,
• force applying means for applying a compressive force to said resilient mandrel in a direction generally axially of said tubular member to establish responsive transverse expansion of said resilient mandrel to clamp said tubular member within said recess between said resilient mandrel and said lateral wall, and
• a mechanical lock for locking the force applying means and maintaining said compressive force so long as the mechanical lock is in the locked position.

The method of making a structural component of a vehicle from a tubular member comprising

• providing a pair of outer tools each having a recess structured to receive and clamp an end of said tubular member,
• inserting a resilient mandrel into each end of said tubular member,
• inserting said tubular ends into said outer tool recesses,
• applying compressive forces in a generally axial direction to each resilient mandrel in order to urge the same transversely outwardly so as to clamp said tubular member ends between said resilient mandrel and said outer tool recess with the compressive force sufficient to urge the tubular member into intimate contact with the outer tool recess,
• applying tensile force to said tubular member to stretch it beyond the yield point and subsequently forming said tubular member, and
• withdrawing said compressive force to unclamp the ends of said tubular member.

A method of gripping a metal tubular member during a forming operation comprising

• providing an outer tool having a recess structured to receive an end of said tubular member,
• inserting a resilient mandrel into said end of said tubular member,
• inserting said tubular member into said recess and applying a compressive force to said resilient mandrel in a direction aligned generally axially of said tubular member to establish transverse expansion of said resilient mandrel with sufficient compressive force to urge the tubular member into intimate contact with the outer tool recess, to clamp said end between said mandrel and said outer tool recess with sufficient retaining force to support the tubular member against axial loading,
• maintaining the compressive force on said resilient mandrel until the forming operation is complete, and
• forming said tube over an area peripheral to the end of the tubular member received within the recess of the outer tool while maintaining said clamping of said end.

A method of gripping a metal tubular member during a forming operation comprising

• providing an outer tool having a recess structured to receive an end of said tubular member,
• inserting a mandrel into said end of said tubular member,
• inserting said tubular member into said recess and applying a compressive force to a resilient component of either said outer tool or said mandrel, in a direction aligned generally parallel to the axis of the tubular member to establish transverse expansion of said resilient component with sufficient compressive force to urge the tubular member into intimate contact with the outer tool recess, to clamp said end between said mandrel and said outer tool recess with sufficient sustained force to retain the end of said tubular member in said recess and support said tubular member against axial loads during the forming operation, and
• forming said tube over an area peripheral said outer tool while maintaining said clamping of said end.