Method of induction weld forming with shear displacement step

A welding method for joining metal parts, said method comprising the steps of:

• (a) providing first and second metal work pieces, each work piece having a contact surface adapted for substantially mating engagement with the contact surface of the other work piece;
• (b) bringing the contact surfaces into substantially mating contact;
• (c) heating the work pieces so as to raise the temperature in a hot layer of metal adjacent to each contact surface to within the hot working range of the base metal of the work pieces;
• (d) applying axial compressive load across the contact surfaces, said compressive load being sufficient to substantially prevent relative sliding between the contact surfaces in response to the imposition of transverse shear strain sufficient to induce plastic flow in the hot layers adjacent to the contact surfaces of the first and second work pieces;
• and
• (e) imposing transverse shear displacement between the work pieces, said shear displacement being sufficient to induce plastic shear strain within the hot layers to induce bonding of the work pieces in the interfacial region;
• such that the contact surfaces remain in substantially mating contact throughout the imposition of transverse shear displacement between the work pieces, without substantial relative transverse displacement between the contact surfaces.

A welding method for joining generally axi-symmetric metal parts, said method comprising the steps of:

• (a) providing first and second generally axi-symmetric metal work pieces, each work piece having at least one axi-symmetric contact surface adapted for substantially axially-aligned mating engagement with the contact surface of the other work piece;
• (b) heating the work pieces so as to raise the temperature in a hot layer of metal adjacent to each contact surface to within the hot working range of the base metal of the work pieces;
• (c) bringing the contact surfaces into substantially axially-aligned mating contact while still in the hot working temperature range;
• (d) applying axial compressive load across the contact surfaces, said compressive load being sufficient to substantially prevent relative sliding between the contact surfaces in response to the imposition of rotational transverse shear strain sufficient to induce plastic flow in the hot layers adjacent to the contact surfaces of the first and second work pieces;
• and
• (e) imposing rotational transverse shear displacement between the work pieces, said shear displacement being sufficient to induce plastic shear strain within the hot layers to induce bonding of the work pieces in the interfacial region;
• such that the contact surfaces remain in substantially mating contact throughout the imposition of transverse shear displacement between the work pieces, without substantial relative transverse displacement between the contact surfaces.

Apparatus for use in association with shear-assisted solid state welding of two metal work pieces, each work piece having a contact surface adapted for substantially mating engagement with the contact surface of the other work piece, said apparatus comprising:

• (a) a main body having a first and second end;
• (b) first gripping means associated with the first end of the main body, said first gripping means being adapted for releasably holding a first work piece in fixed relation to the main body;
• and
• (c) a dual-axis hydraulic actuator at the second end of the main body;
• wherein:
• (d) the hydraulic actuator includes an actuator body having a first end and a second end
• (e) the actuator body has a double-acting, hollow bore intermediate forge piston and a double-acting, hollow bore inner rotary piston;
• (f) the intermediate forge piston and the inner rotary piston are concentrically disposed within the actuator body, with the intermediate forge piston acting as a cylinder for the inner rotary piston;
• (g) each of the intermediate forge piston and the inner rotary piston has a first end and a second end corresponding to the ends of the actuator body;
• (h) second gripping means is provided in association with the first end of the intermediate forge piston, said second gripping means being adapted for releasably gripping a second work piece;
• (i) the first end of the actuator body is rigidly attached to the second end of the main body and arranged such that the second gripping means is aligned in opposition to the first gripping means, thus providing means to orient the contact surfaces of the work pieces for mating engagement;
• and
• (j) the second ends of each of the nested actuator body, the intermediate forge piston, and the inner rotary piston are respectively attached to a similarly nested and close-fitting assembly comprising:
• j.1 an outer sleeve with a plurality of largely axial slots;
• j.2 an intermediate cam profile sleeve with helical slots distributed circumferentially to match with the largely axial slots provided in the outer sleeve;
• and
• j.3 an inner spider flange carrying outwardly radial shafts provided with cam followers that pass through and independently engage each of the helical and largely axial slots, thereby linking axial motions or the actuator body, the intermediate forge piston, and the inner rotary piston with relative axial movement of the inner rotary piston, causing rotation of the intermediate forge piston largely independent of the intermediate forge piston's axial position relative to the actuator body.