US 7,066,000 B2Granted

Forming tool apparatus for hot stretch-forming processes

AssigneeGeneral Motors Corporation

InventorRichard Harry Hammar

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Abstract

A tooling assembly for hot stretch-forming of a sheet metal workpiece. A forming tool is attached to a plate and includes a shell having a forming surface, and support walls that extend away from the shell, that terminate in a rearward surface of the forming tool, and that define open cells between the support walls. Heating elements are embedded within the forming tool for integral and uniform heating thereof. To limit conductive thermal losses from the forming surface, through the forming tool, and to the plate and surrounding environment, the open cells are provided in the forming tool and insulative support posts are disposed between the forming tool and the plate within deep counterbores in the rearward surface of the forming tool. To limit radiative and convective thermal losses, thermal insulation is disposed within the cells and between the forming tool and plate.

Claims10

Dependent claims

A tooling assembly for hot stretch-forming of a heat-softened sheet metal workpiece, said tooling assembly being adapted for attachment to a plate, said tooling assembly comprising:

a forming tool formed of an integral body of metal and including:
a layer of predetermined thickness, said layer having a forwardly disposed forming surface thereon against which said workpiece is formed;
and
a plurality of structures extending rearwardly from said layer and terminating in a rearward surface of said forming tool, said plurality of structures being adapted to support said layer, said plurality of structures defining at least one open cell therebetween to reduce thermal losses emanating away from said forming surface due to at least one of thermal conduction and thermal radiation;
a plurality of electrical resistance heating elements embedded within said layer for integrally heating said forming surface to enable hot stretch-forming of said workpiece;
thermal insulation disposed within said at least one open cell of said forming tool to reduce thermal losses emanating away from said forming surface due to at least one of thermal radiation and thermal convection;
and
a plurality of insulative support posts disposed between said forming tool and said plate to establish a gap therebetween, said insulative support posts having greater resistance to thermal conductivity than said forming tool.

5 more elements

Dependencies are inferred from the claim text.