Trapezoidal thread valve rod processing technique

Abstract

The invention discloses a process of an acme thread valve stem, adopting the combination method of machining and cold extrusion. The valve stem is firstly processed with machining. The threaded portion of the valve stem is processed by a whirlwind milling, which ensures that the allowance of the acme thread is controlled to be 0.20-0.30mm higher than the proposed parameter. And then, cold extrusion and rolling should be processed. The threaded portion of the valve stem processed in the third step should be arranged between the two rolling moulds. When the two rolling moulds rotate in the same direction, the middle parts should be processed with cold extrusion and rolling through the pressure of a hydraulic machine. When the two rolling moulds are completely coincided, the processing of the valve stem thread is completed. The physical structure inside the metal of the threaded portion of the valve stem is basically not changed or the change degree is quite small. The uniformity of the whole metal interior stress of the valve stem is kept. The valve stem quality is improved. The service life of the valve stem is prolonged.

Description

technical field [0001] The invention relates to a valve manufacturing technology, in particular to a processing technology for a valve stem, the main part of a valve. Background technique [0002] There are two kinds of threads for existing valve stems, one is triangular thread and the other is trapezoidal thread. Due to the sealing requirements of valves, most valve stems adopt trapezoidal thread. The processing of existing valve stem trapezoidal thread One method is the traditional ordinary lathe flying knife processing, and then grinding, but the smoothness of the thread surface is still not good enough, it is easy to damage the seal in the valve, and it is laborious to lift. The other is to cold-extrude and roll the threaded part of the valve stem using a rolling die, and form a trapezoidal thread in one roll. The Chinese patent application number is: No. 200510134571.5 invention patent discloses a method of "valve stem forging and cold extrusion forming process", which...

AI Technical Summary

Problems solved by technology

The Chinese patent application number is: No. 200510134571.5 invention patent discloses a method of "valve stem forging and cold extrusion forming process", which is the one-time forming method of cold extrusion and rolling. The disadvantage of this method is that the When the stem is cold-extruded, the physical structure of the metal inside the threaded part of the valve stem is forcibly changed, resulting in a difference in the overall metal stress of the valve stem, which increases the brittleness of the valve stem and reduces the service life