METHOD FOR MAKING SCREW PARTS AND APPARATUS FOR PERFORMING THE SAME Russian patent published in 1998 - IPC

FIELD: plastic metal working, namely manufacture of elongated screw parts of stainless steel used in oil and gas production industry branches. SUBSTANCE: method allows to make elongated screw parts of thin-wall tubular blanks having high surface degree of n-start screw surfaces without additional working. It is achieved due to shaping screw profile by means of successive plastic deformation at constant rotation of tubular blank inside which mandrel with shape corresponding to necessary screw profile is arranged and at synchronized reciprocation motion of profiling members in the form of rolling bodies mounted in rolling out head along axis of part. Apparatus includes rolling out head whose body has cover with helical cams. In radial grooves of head body spring-loaded shoes are mounted. Shoes engage with helical surface of cams and support rollers mounted on pins with possibility of rotation and inclined by angle α equal to angle of helix. Number of rollers is equal to that of profiled grooves. EFFECT: enhanced strength, increased useful life of parts made by such method. 2 cl, 5 dwg