DRAWING INSTRUMENT Russian patent published in 2008 - IPC B21C3/06 

FIELD: technological processes.

SUBSTANCE: invention is designed for use in plastic metal working, mainly for thin-walled pipes. The drawing instrument has a case with an end wall, in which there is an opening for letting out the deformed pipe, and a drawing die installed in it with a working opening, the diameter of which reduces in the drawing direction. Increase in technological capabilities of the drawing instrument due to provision for obtaining an object with varying diameter and reduction of production expenses of the drawing process is provided by that, between the case and the drawing die, there is a bush screwed into the case with tapered hole, widening in the drawing direction. On the conical surface of the bush, there are through passing rectangular grooves at equal distance from each other. The drawing die is made from circular sectors of a trapezoidal section with projections, which enter corresponding grooves on the bush. The sectors are supported by the end wall of the case and are made with provision for radial displacement within the limits of the tapered hole of the bush with its longitudinal displacement with change in the area of the working hole of the drawing die. The maximum D and the minimum d diameters of the formed working hole of the draw die have the following ratios: D/d=1.4...1.6.

EFFECT: more technological capabilities of the drawing instrument due to provision for making an object with varying diameter and reduction of production expenses of the drawing process.

4 cl, 1 dwg, 1 ex