Gm Global Technolgoy Operations, Inc.

Mircea M Ghiran

Spyros Pete Mellas

Bruce Steven Shimanovski

David R Jensen

George Thomas Winterhalter

Romuald Gmurowski

Benjamin D Kaufman

Glenn Mark Krcek

Paul C Oberski

Paul D Larsen

Terry Andrew Kent

Gerry A Harmon

Method and apparatus are disclosed wherein a hydroformed part remains in a hydroforming die cavity under hydroforming pressure while an attachable fastener nut is operated to pierce and form a collar in the part by forced insertion of the nut into the part and wherein the nut is fastened to the collar by friction welding, friction skip welding or mechanical locking depending on the form of the fastener nut.

Method and apparatus for attaching a fastener nut to a hydroformed part

An in-die hydropiercing device comprises a punch with an annular shearing blade which is operated by a hydraulic cylinder and is received in a ring-shaped die button mounted in one of the dies that form a die cavity for the hydroforming of a part, a center support member that is received in the center of the punch and supports the wall of the part inward of the shearing blade during the hydroforming of the part and also during the piercing of the part with the shearing blade, a slug collector, and a slug retainer that is mounted on the center support member and provides for retention of a slug produced from the piercing operation against the center support member and later releases the slug onto the slug collector for disposal following the opening of the dies and insertion of the slug collector between the open dies and then retraction of the slug collector with the slug for slug disposal.

In-die hydropiercing device for piercing holes in hydroformed parts

A fastener nut for hydroformed parts comprises a nut body for receiving a threaded fastener and a locking ring with depending fingers that is received on the nut body. The nut body is adapted to pierce and then form a collar thereabout in a hydroformed part while the part remains in a die cavity under hydroforming pressure. The nut body and the collar formed thereby have a configuration that prevents turning of the locking ring while permitting turning of the nut body relative to the locking ring on full insertion of the nut in the collar, and a cam surface on the nut body that on partial turning of the nut body then forces the locking ring into locking engagement with the collar to thereby attach the fastener nut to the hydroformed part.

Fastener nut for hydroformed parts

A hydrotapping power unit is disclosed that is operable to hold a hydrotapping tool in a home position adjacent a part while the latter is being hydroformed in a die cavity, to then advance the tool to pierce a hole in the hydroformed part while the part remains in the die cavity and under pressure and then continue to advance the tool to inwardly extrude the part about the hole, to then further advance while also rotating the tool at a feed rate equal to the thread pitch of the tool to thereby form a thread in the pierced hole, and finally retract while also rotating the tool but in the reverse direction and at the same feed rate to release the tool from the threaded hole. The power unit for performing these operations includes a linearly moveable shaft for holding the tool, a powered device for rotating the shaft, another powered device connected to the shaft by a lead screw connection having a thread pitch equal to that of the tool, and a third powered device that is adapted to intercept and prevent shock loading on the tool from the piercing operation and thereby on the shaft from reaching the lead screw connection.

Hydrotapping power unit

Method and apparatus are disclosed wherein a required threaded hole is formed in a hydroformed part with a single tool while the part remains in a hydroforming die cavity. In forming the threaded hole, a hole is first pierced in the wall of the part and then an annular region of the part extending about the hole is extruded inwardly to form an integral tubular neck defining a hole of predetermined depth. The hole is then expanded in a sizing operation to a diameter determined by the required thread to be formed therein by material displacement and the required thread is then formed in the wall of the hole in a material displacing manner.

Method and apparatus for forming a threaded hole in a hydroformed part

A hydrotapping power unit is disclosed that is operable to position and hold a hydrotapping tool in a home position adjacent a part while the part is being hydroformed in a die cavity, to then advance the tool to pierce a hole in the hydroformed part while the part remains in the die cavity and under pressure and then continue to advance the tool to inwardly extrude the part about the hole, to then further advance while also rotating the tool so that the tool is fed at a feed rate equal to the thread pitch of the tool to thereby form a thread in the pierced hole, and finally to retract while also rotating the tool but in the reverse direction and at the same feed rate to release the tool from the threaded hole. The power unit performing these operations includes a linearly moveable shaft for holding the tool, a powered device for rotating the shaft, a powered device for linearly moving the shaft, and a lead screw connection between the latter powered device and the shaft having a thread pitch equal to that of the tool.

Hydroforming apparatus is provided with retractable part locators that are adapted when extended to receive and hold end portions of a tubular part to be hydroformed and thereby support and hold the part between the hydroforming dies when the dies are open. Seal units mounted on separate elevators have a retractable seal carrier and the seal carriers are adapted when the seal units are elevated to advance and initially engage the respective tubular part end portions while the part is being so held. The part locators are adapted to release the end portions of the part and retract out of the way of the seal carriers to permit the seal carriers to then further advance on the respective end potions of the part to a position closely adjacent the end faces of the dies while also centering the part lengthwise with respective to the dies prior to die closure. The seal unit elevators are adapted to lower the seal units with the tubular part to a position aligning the end portions of the part with open ends of the die cavity when the dies close. And the retractable part locators, following the hydroforming of the part and elevation of the part with the seal units by the seal unit elevators, are adapted to again extend and clamp the now hydroformed part to the part locators prior to disengagement of the seal carriers from the part.

Hydroforming apparatus with retractable part locators

Hydroforming apparatus includes in-die hydropiercing apparatus with easy and precise adjustment of the positioning of a backup plunger that is received in a die button and is positioned in a hydroforming position, a prepiercing position, a piercing position, and a slug ejecting position that may be outside the plunger or may be the hydroforming position. Wherein the plunger is required to be precisely positioned and held in the prepiercing position in the die button in order to obtain a desired prepiercing action without prematurely piercing the hydroformed part. The in-die hydropiercing apparatus has a plunger actuating hydraulic cylinder that moves the plunger to the different positions and a cam actuating hydraulic cylinder that positions a cam in determining the prepiercing position of the plunger. The cam actuator includes an adjusting device that provides for easily adjusting positioning of the plunger with the cam in the required prepiercing position and the cam with its hydraulic actuator also acts to hold the plunger in the prepiercing position thereby relieving the plunger actuating hydraulic cylinder of this duty.

In-die hydropiercing apparatus with prepiercing adjustment

A punch for piercing and sealing hydroforming parts has a roll forming surface that produces an internal rolled edge portion in a formed part immediately following the punch piercing the part wherein the rolled edge portion acts to effect a tight high pressure seal between the part and the punch as the punch continues to form a required hole in the part. The roll-forming surface extends either partially or completely about the punch in determining the extent of the rolled edge portion in the part that it produces and is located between an end portion that effects the piercing operation and a larger finishing portion that completes the formation of the required hole.

Punch for piercing and sealing hydroformed parts

The seal units that form part of a hydroforming apparatus that further includes dies for hydroforming parts are each provided with a tubular part locator for locating and clamping a tubular part in alignment with the seal unit. The part locator basically comprises a locator member, a pair of pivot arms and a backup member wherein the locator member and the pivot arms together with the seal unit are supported by an elevator that aligns the seal unit and the locator member with the hydroforming dies when the latter close on the tubular part. The locator member has a concave surface and guide surfaces wherein the concave surface has a shape conforming to the outer surface of the part and the guide surfaces are adapted to guide an end portion of the tubular part onto the concave surface of the locator member and thereby into alignment with the seal unit. The pivot arms each have a concave surface also conforming to the outer surface of the part and are adapted on pivoting to clamping positions to clamp the end portion of the part on the concave surface of the locator member. The backup member is adapted to hold the pivot arms in their clamping position during hydroforming of the part and may also include a concave surface that is adapted to clamp the end portion of the tubular part on the concave surface of the locator member in cooperation with the concave surface of the pivot arms.

Tubular part locator for hydroforming apparatus

A pair of self-aligning non-pinching hydroforming dies have fingers and slots which are operable during closure of the dies on a tubular part to effect precise alignment of the dies as they are pressed together to form a hydroforming cavity about the part so that the part is not pinched between mating surfaces of the dies during their closure on the part. The fingers are further capable of mechanically straightening and/or bending the part, if need be, to prevent pinching of the part during die closure. The fingers are also capable of mechanically forming a round tubular part to a non-round cross-section region of the die cavity as the dies close to help form the part as well as prevent pinching of this section. With all such mechanical forming operations by the action of the fingers on the part performed prior to the hydroforming of the part in the die cavity.

Self-aligning non-pinching hydroforming dies

A die button flush mounted in the cavity surface of a lower one of two hydroforming dies has a backup plunger received therein that forms a part of this surface when the plunger is in a hydroforming position. A slug ejector received in the lower die also forms a part of this surface and with a tubular part enclosed in the cavity formed by the dies, hydroforming fluid under pressure is supplied to the interior of the part and also to separately act on the plunger. The fluid pressure moves and holds the plunger in its hydroforming position while forming the part to the die cavity surface. The fluid pressure on the plunger is then exhausted allowing the fluid pressure in the part to stretch a portion of the part into the die button while also forcing the plunger to a position that limits this stretching to prevent piercing. The fluid pressure in the part is then reduced to a pressure just sufficient to pierce the stretched portion and the plunger is then allowed to further retract to a position allowing the reduced pressure to pierce a slug onto the plunger. The part is then removed from the die cavity and the plunger is returned to its initial position with the slug thereon where the slug is then ejected from the lower die through an opening in the lower die cavity surface.

Hydroforming, in-die hydropiercing and slug-ejecting method and apparatus

Method and apparatus for forming unobstructed holes in a hydroformed metal part employs a punch having a peripheral side conforming to the desired hole shape and an end face having a central cutting edge with a high point that contacts on closure of a hydroforming die with an unsupported wall section of the part initiating a stress riser therein. During forming of the part, the hydraulic pressure forces the above wall section outward against this high point increasing the magnitude of the stress riser. The punch is advanced while maintaining the hydraulic pressure causing the above high point to fracture this wall section at the stress riser and the above cutting edge to then split and cut this wall section to form oppositely facing cut edges in this section. Simultaneously, oppositely angled cutting edges at opposite ends of the central cutting edge and at the punch end face periphery then cut this wall section in directions away from the oppositely facing cut edges to form oppositely extending slugs. As the punch continues to be advanced, contoured portions of the punch end face with the aid of the hydraulic pressure contact the slugs to provide a seal to maintain the hydraulic pressure while bending the slugs as they are being cut into the interior of the part. The peripheral side of the punch with further punch movement engages the slugs with an interference fit to maintain the hydraulic pressure and forces the slugs into positions forming an unobstructed hole in the part while remaining integral therewith.

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Lake Orion, MI, United States of America

Mircea M Ghiran