Bimetallic snap disc and method and apparatus for making same

Claim 2

A pair of tools for forming a snap disc comprising a punch formed with radially extending ridges extending from a center location, said punch being formed with relief sections between said ridges, and a die formed with a plurality of radially extending working surfaces extending toward said center, said die having relief sections between said working surfaces proportioned to receive said ridges, said ridges being inclined from a reference plane perpendicular to the central axis of said punch and said working surfaces being inclined from said reference plane in the same direction.

Claim 3

A pair of tools for forming a snap disc as set forth in claim 1 wherein the angle of inclination of said ridges with respect to said reference plane is less than the angle of inclination of said working surfaces with respect to said reference plane.

Claim 4

A pair of tools for forming a snap disc as set forth in claim 2 wherein said working surfaces are triangular in shape with greatest width adjacent to the periphery of the die.

Claim 5

A pair of tools for forming a snap disc as set forth in claim 3 wherein the width of said working surfaces adjacent the periphery of said die is substantially greater than the width of said ridges.

Claim 6

A pair of tools for forming a snap element having a dished portion which is substantially symmetrical around a center comprising a punch formed with radially extending ridges extending from and joined at a center location, said punch being formed with relief sections between said ridges, and a die formed with a plurality of support surfaces extending toward but terminating at locations spaced from said center location adapted to engage and support said element adjacent the periphery of said portion between said ridges, said die having relief sections between said support surfaces proportioned to receive said ridges.

Claim 7

A pair of tools for forming a snap element having a dished portion which is substantially symmetrical around a center comprising a punch formed with radially extending ridges extending from and joined at a center location, said punch being formed with relief sections between said ridges, and a die formed with a plurality of support surfaces extending toward but terminating at locations spaced from said center location adapted to engage and support said element adjacent the periphery of said portion between said ridges, said die having relief sections between said support surfaces proportioned to receive said ridges.

Claim 8

A pair of tools for forming a snap element as set forth in claim 5 wherein said ridges are inclined with reference to a plane perpendicular to the central axis of said punch.

Claim 9

A pair of tools for forming a snap element with at least a circular portion which is dished to render such element bistable comprising a punch formed with a central part operable to engage a sheet of deformable material such as metal or the like on one side at the center of its circular portion and applying deforming forces thereto, and a cooperating die operable to support the other side of said sheet substantially adjacent to the periphery of said circular portion, said tool and die being formed with cooperating surfaces operable to form stiffening convolutions in said sheet substantially symmetrical with respect to said center of said portion, said tool operating to form a shallow dished shape in said circular portion and said stiffening convolutions wherein both the depth of said dished shape and the stiffness provided by said convolutions is a direct function of the amount of deforming movement of said punch into said die.

Claim 10

A pair of tools for forming a snap element with at least a circular portion which is dished to render such element bistable comprising a punch formed with a central part operable to engage a sheet of deformable material such as metal or the like on one side at the center of its circular portion and applying deforming forces thereto, and a cooperating die operable to support the other side of said sheet substantially adjacent to the periphery of said circular portion, said tool and die being formed with cooperating surfaces operable to form stiffening convolutions in said sheet substantially symmetrical with respect to said center of said portion, said tool operating to form a shallow dished shape in said circular portion and said stiffening convolutions wherein both the depth of said dished shape and the stiffness provided by said convolutions is a direct function of the amount of deforming movement of said punch into said die.

Claim 13

A method of forming a snap element as set forth in claim 8 wherein such sheet is formed of bimetal.

Claim 14

A method of forming a snap element as set forth in claim 8 wherein said stiffening scallops and said shallow dished shape are simultaneously formed in said sheet.

Claim 17

A method of forming a bimetal snap element as set forth in claim 11 wherein said sheet of metal is circular and said peripherally spaced locations are located around the edge of said sheet.