Production method of a spinning ring for a ring spinning machine

A production method for making a non-reversible spinning ring, having a shape which is dissymmetric in the direction of an axis thereof, by clamping and pressing a ring blank made of steel between a mandrel and a forming roll;

• wherein an inner and an outer peripheral surface of said ring blank is deformed by cold rolling into a ring body having a ring flange portion at a first end, a neck portion continuing from said ring flange portion, a support flange portion continuing from said neck portion and a fit-in portion at a second end continuing from said support flange portion;
• said forming roll having a pair of radial walls on both sides of an outer peripheral surface thereof in an axial direction, a ring flange forming groove continuing from one of said radial walls, a neck forming protuberance continuing from said ring flange forming groove, a support flange forming groove continuing from said neck forming protuberance and a fit-in portion forming peripheral surface continuing from said support flange forming groove;
• and
• said mandrel having a ring flange forming groove corresponding to said ring flange forming groove of said forming roll, a neck forming step portion corresponding to said neck forming protuberance of said forming roll, a support flange forming protuberance, the sectional shape of which is a wedge shape having an included angle of from 80.degree. to 95.degree., corresponding with said support flange forming groove of said forming roll and a fit-in portion forming step portion corresponding with said fit-in portion forming peripheral surface of said forming roll;
• said method comprising the steps of;
• clamping and pressing said ring blank in said mandrel and said forming roll so that said ring is first pressed and deformed from the inner peripheral surface thereof by said support flange forming protuberance of said mandrel wherein said ring is deformed in a gap between said support flange forming protuberance and said support flange forming groove of said forming roll;
• thereafter, pressing and deforming said ring substantially simultaneously from the outer peripheral surface thereof by said neck forming protuberance of said forming roll to deform said ring in a gap between said neck forming protuberance and said neck forming step portion of said mandrel,
• thereafter, clamping and pressing a first side end portion of said ring by said ring flange forming groove of said forming roll and said ring flange forming groove of said mandrel to deform said ring in a gap between said ring flange forming groove of said forming roll and said mandrel, and a second end portion of said ring being clamped and pressed substantially simultaneously by said fit-in portion forming peripheral surface of said forming roll and said fit-in portion forming step portion of said mandrel to deform said ring in a gap between said fit-in portion forming peripheral surface of said forming roll and said fit-in forming step portion of said mandrel;
• wherein a direction of a thickness, the diameters of said ring are expanded and deformed to fill gaps between each portion of said forming roll and said mandrel, thereby producing said ring flange portion, said neck-portion, said support flange portion and said fit-in portion into a predetermined size.