Process for manufacturing electrical contact pin

Claim 2

A process for manufacturing an electrical contact pin having a fixing part to be fitted into a through hole of a circuit board for fixing without using any solder, said fixing part having a substantially rectangular cross section, a pair of alternating substantially triangular recesses provided on a pair of opposite sides of said rectangular section, a pair of sharp corners adjacent to said triangular recesses extending beyond said sides to form a pair of resilient projected sharp corners, characterized by the step of pressing a metal work having a substantially rectangular cross section to form said fixing part in a pair of metal dies, a pair of alternating substantially triangular projections provided on the bottoms of said dies to form said substantially triangular recesses, a pair of opposite sides of said dies arranged so that there may be first small spaces between said pair of sides and the opposite sides of said work before pressed, and a part of said bottom of each die made deeper than the rest of said bottom to form a second small space between said part of said bottom and a top of said rectangular work, which communicates with said first space so as to form said resilient projected sharp corner when said work is squeezed between said metal dies.

Claim 3

A process for manufacturing an electrical contact pin having a fixing part to be fitted into a through hole of a circuit board for fixing without using any solder, said fixing part having a substantially rectangular cross section, a pair of alternating substantially triangular recesses provided on a pair of opposite sides of said rectangular section to form a substantially N-shaped cross-section, with four sharp corners, a pair of corners adjacent to said triangular recesses extending beyond said sides to form a pair of resilient projected corners, said process comprising the steps of: stamping from a sheet of metal a contact pin element with a fixing part section having a substantially rectangular cross-section; subjecting said rectangular fixing part section to a single pressing operation between a pair of upper and lower metal dies, each having a generally L-shaped cross-section consisting of a lateral base portion and a vertical leg portion; an inside surface of said base portion consisting of a first die surface adjacent to said vertical leg portion and a second die surface adjacent to a free end of said lateral base portion and a substantially triangular projection between said first and second die surfaces; the distance between said first die surfaces of said upper and lower dies is substantially equal to the height of said rectangular fixing part section; the distance between said second die surface of said upper or lower die and said first die surface of said lower or uppper die is made greater than the distance between said first die surfaces so as to form a first die cavity portion for receiving said projected corner; and the distance between inside surfaces of said leg portions of said upper and lower dies is greater than the width of said rectangular fixing part section so as to form a second die cavity portion for receiving a substantial portion of material replaced by said triangular projection during said pressing operation.

Claim 4

A process for manufacturing an electrical contact pin having a fixing part to be fitted into a through hole of a circuit board for fixing without using any solder, said fixing part having a substantially rectangular cross section, a pair of alternating substantially triangular recesses provided on a pair of opposite sides of said rectangular section to form a substantially N-shaped cross-section, with four sharp corners, a pair of corners adjacent to said triangular recesses extending beyond said sides to form a pair of resilient projected corners, said process comprising the steps of: stamping from a sheet of metal a contact pin element with a fixing part section having a substantially rectangular cross-section; subjecting said rectangular fixing part section to a single pressing operation between a pair of upper and lower metal dies, each having a generally L-shaped cross-section consisting of a lateral base portion and a vertical leg portion; an inside surface of said base portion consisting of a first die surface adjacent to said vertical leg portion and a second die surface adjacent to a free end of said lateral base portion and a substantially triangular projection between said first and second die surfaces; the distance between said first die surfaces of said upper and lower dies is substantially equal to the height of said rectangular fixing part section; the distance between said second die surface of said upper or lower die and said first die surface of said lower or uppper die is made greater than the distance between said first die surfaces so as to form a first die cavity portion for receiving said projected corner; and the distance between inside surfaces of said leg portions of said upper and lower dies is greater than the width of said rectangular fixing part section so as to form a second die cavity portion for receiving a substantial portion of material replaced by said triangular projection during said pressing operation.