Wire Straightening and Molding for Wire Spring Relays

The basic design of the wire spring relay departs from conventional relay design in many ways. Translation of some of these design departures into commercial relay manufacture has necessitated the development of new machines and new methods because those available were incapable of producing to the new design requirements. Two developments in this category involved the straightening of large quantities of small diameter wire and the molding of a multiplicity of straightened wire inserts into phenolic resin blocks. The manner in which these developments were reduced from problems to practice is the subject of this paper. PART I -- AUTOMATIC WIRE STRAIGHTENING Ordinarily wire is received from suppliers on spools or reels. In the spooling operation a spiral bend is placed in the wire which persists when it is unspooled. For use as a wire spring in the wire spring relay this spooling bend must be removed if the wire is to be positioned with the precision required for the desired functioning of the relay. It is necessary, also, to have the wire free of bends if automatic manufacturing methods are to be employed. For these reasons, it is important that the nickel silver and silicon copper wire used in the wire spring relay be straightened as the initial operation in the manufacture of wire block assemblies or "combs" for these relays. Wire straightening can be accomplished by cold working the wire under controlled conditions until sufficient stress has been built up, particularly at the surface, to make the wire resist bending efforts.