Cool-wrought pressing forming method for slotted headless screws
OwnerWen-Lung Chenginventor
Life of this patent
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Abstract
A cool-wrought pressing forming method for slotted headless screws includes five steps of using five different molds and five pressing heads for processing a unit of screw material cut from linear material for forming an unfinished screw with a slot in an upper end. A clamping member is provided for clamping a screw material for moving it from a first mold in a first step to a second mold in a second step after pressed by a first pressing head and then from a second step to a third mold in a third step, and so forth. The slot of a screw is formed by pressing to make the slot neat and without any hairy sides and look very flat, enhancing production effect and lowering cost.
Claims9
A cool-wrought pressing forming method for slotted headless screws comprising:
- a first step of cutting linear material into many units of a certain length just for one screw, each said unit screw material placed in a first mold, said first mold having an outer cylindrical shape and an inner cylindrical hollow, said inner cylindrical hollow having an annular curved guide angle in its bottom, a first pressing head having a flat end surface, said first pressing head pressing said unit material placed in said first mold to form a first-stage unfinished screw;
- a second step of taking out and placing said first-stage unfinished screw in a second mold, said second mold having an outer cylindrical shape and an inner cylindrical hollow with a bottom provided with an annular curved guide angle, a second pressing head of a conical shape pressing on said first-stage unfinished screw in said second mold, said first-stage unfinished screw becoming a second-stage unfinished screw having a V-shaped recess formed in an upper end surface;
- a third step of taking said second-stage unfinished screw out of said second mold, said second-stage unfinished screw inverted for 180 degrees and then placed in a third mold, said third mold having an outer cylindrical shape and an inner cylindrical hollow with a bottom provided with an annular curved guide angle, a third pressing head of a rectangular shape pressing on said second-stage unfinished screw, said second-stage unfinished screw becoming a third-stage screw having the conical bottom recess with an annular curved guide angle and a rectangular recess formed in an upper end of the inverted second-stage unfinished screw;
- a fourth step of taking said third-stage unfinished screw out of said third mold and inverted for 180 degrees, said inverted third-stage unfinished screw placed in a fourth mold, said fourth mold having an outer cylindrical shape and an inner cylindrical hollow with a bottom provided with a rectangular projection extending upward, a fourth pressing head of a conical shape pressing down on said third-stage unfinished screw in said fourth mold, said third-stage unfinished screw becoming a fourth unfinished screw having a rectangular groove formed in the bottom and a V-shaped recess formed in an upper end of said inverted third-stage unfinished screw;
- a fifth step of taking said fourth-stage unfinished screw out of said fourth mold, said fourth-stage unfinished screw inverted for 180 degrees and placed in a fifth mold, said fifth mold having an outer cylindrical shape and an inner cylindrical hollow with an annular curved guide angle and a through hole formed in a bottom, a fifth pressing head of a rectangular shape pressing down on said fourth-stage unfinished screw, said fourth-stage unfinished screw becoming a fifth-stage screw having a slot formed in an upper end and the V-shaped recess and the annular curved guide angle;
- said fifth-stage unfinished screw cut with threads by means of a thread forming machine to become a completed slotted headless screw.
Dependencies are inferred from the claim text.