Metal treatment – Process of modifying or maintaining internal physical... – Heating or cooling of solid metal
Reexamination Certificate
1999-06-28
2001-04-17
Ip, Sikyin (Department: 1742)
Metal treatment
Process of modifying or maintaining internal physical...
Heating or cooling of solid metal
Reexamination Certificate
active
06217677
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method for annealing stamped components, and more particularly to a method for locally annealing sharp radii in precision formed housings, the housings being formed by a stamping process and made from a carbon or HSLA steel.
DESCRIPTION OF THE PRIOR ART
In an automatic transmission, several components are formed from carbon steel or HSLA steel. Torque transmission members include a number of drums which are stamped and splines are rolled into the cup-shaped outer periphery. Normally, the stamping displaces the grain structure of the steel thereby work hardening the part. This work hardening causes high stresses at the radius and slivering may occur within such drums. Typically, such parts are annealed in a furnace, wherein the entire part is heated to the appropriate temperature and the entire part is annealed, although only the stress areas require such annealing. This process requires a long cycle time to heat the entire part and anneals portions of the part for which it is not desired to be annealed and therefore softened.
The work hardening creates further problems in that the hardened portion creates areas of high stress that may contribute the fatigue and/or failure such as cracking, splintering or slivering of the material. Methods to control these problems include additional die stations to control and minimize the amount of displacement in a particular stamping operation. Alternatively, a steel having a lower carbon content may be used. Or, alternatively, a nonselected stress relief process may be used to anneal the entire component in a furnace or oven. Each of the above may require additional cost or produce undesirable characteristics in the part.
One such component is a hub for a reverse and low gear, one-way clutch in the Ford CD4E automatic transmission. It would therefore be desirable to produce a precision stamped component and anneal the areas of high stress in the stamped component.
SUMMARY OF THE INVENTION
According to the present invention, a stamped component is locally annealed using a magnetic heating process. By doing so, stresses in the part are reduced so as to avoid splintering, slivering, or other defects during subsequent operations.
A process for forming a precision formed cup-shaped member is provided, including stamping a blank into a cup-shaped member. The cup-shaped member is positioned onto a magnetic heating machine. A magnetic core is positioned adjacent a radius of the cup-shaped part on both a top side and a bottom side of the cup-shaped part. The part is heated with the magnetic heating machine so as to anneal the cup-shape part at the radius.
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“Patented Heat treating System Uses Magnetic Field Technology for Through-Heating of Metal Parts” by D. Keith Patrick, Industrial Heating/Mar. 1998.
Kolodziej Dennis Raymond
Szuba Joseph A.
Ford Global Technologies Inc.
Ip Sikyin
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