Cold-forming of toothed wheels from sheet steel

Abstract

A method of forming a toothed wheel comprising the steps of cold-forming a circular piece of sheet metal of predetermined thickness into a preform, rotating (1) a rotary holding unit with the preform secured thereto about the preform axis and with a control surface of the holding unit underlying at least a portion of an annular section of the preform and (2) a tooth-forming tool unit in a predetermined rotational relation wherein the axes of rotation are parallel and the rotational speeds are synchronized, and while in the predetermined rotational relation affecting a relative movement between the units and the axes thereof in a direction toward one another to engage a tooth-forming periphery of the tooth-forming tool unit in cooperating metal-deforming relation with the annular section inwardly of the exterior periphery thereof until the sheet metal of the annular section is cold-formed into the series of teeth, the peripheries of which are cold-formed by rolling contact with the tooth-forming periphery of the tooth-forming tool unit and portions of the sides of which are smooth and cold-formed by contact with smooth tooth-side forming surfaces so that an amount of sheet metal which would otherwise uncontrollably flow axially outwardly of the smooth tooth-side forming surfaces is concentrated within the teeth and/or the radially inward back-up therefor and the toothed wheel made thereby.