Method of tube-necking spinning and apparatus therefor

Abstract

A two-step method and apparatus therefor provide cost-effective processing of tube-necking spinning for Superconducting Radio Frequency (SRF) cavities. A metal tube as a work piece may be rotated round its longitudinal axis; the target shape is obtained gradually in two steps by driving specially profiled rollers along roller paths moving in radial and axial directions. Alternatively, the rollers may rotate around a stationary work piece. To spin one cell, in the first step, a primary forming roller moves along a roller path to form a partial necking shape; then, in a second step, a secondary forming roller moves along a roller path to continue necking processing; and finally, the full cell is formed. To spin multi-cells, this two-step method is repeated for each cell. No additional equipment is required as rollers are mounted the same as in conventional spinning The cost is reduced by applying a rapid feeding rate, greatly shortening the length of the roller path, accurately controlling the spun profile and eliminating a complicated mandrel.

I claim: 
     
         1 . A two-step tube-necking spinning processing method, comprising:
 providing spinning apparatus;   providing a work piece of metal tube;   providing a primary forming roller having a selected profile;   radially driving the primary forming roller on the work piece by means of a driving mechanism of the spinning apparatus and then moving the primary forming roller along the axial direction by means of a driving mechanism of the spinning apparatus while rotating the work piece, thereby drawing the metal tube to form a section of reduced diameter and the first part of a necking shape.   providing a secondary forming roller having a selected profile, the profile including   a nose; and   radially driving the secondary forming roller on the work piece by means of a driving mechanism of the spinning apparatus and then moving the secondary forming roller along the axial direction by means of the driving mechanism of the spinning apparatus while rotating the work piece, thereby drawing the metal tube to form a section of further reduced diameter and the second part of the necking shape.   
     
     
         2 . The method of  claim 1  wherein the profile of the primary forming roller includes a plurality of noses. 
     
     
         3 . The method of  claim 1  wherein the profile of the secondary forming roller includes a nose having a shape adapted to form a selected iris area. 
     
     
         4 . The method of  claim 3  wherein the selected iris area is determined by the desired shape of the cells of a SRF cavity. 
     
     
         5 . The method of  claim 1  further providing a plurality of primary forming rollers disposed radially around the work piece, each of said primary forming rollers having a rim with a specially profiled section shape and being spaced apart around the work piece and being mounted on fixtures of the spinning equipment. 
     
     
         6 . The method of  claim 5  further providing a plurality of secondary forming rollers disposed radially around the work piece, each of said secondary forming rollers having a nose, with a specially profiled section shape and being mounted on fixtures of the spinning equipment. 
     
     
         7 . The method of  claim 1  wherein the primary and secondary rollers are mounted on the same spinning apparatus. 
     
     
         8 . The method of  claim 1  wherein the primary and secondary rollers are mounted on different spinning apparatus. 
     
     
         9 . The method of  claim 6  wherein the profile of the secondary forming rollers includes a nose having a shape adapted to form a selected iris area. 
     
     
         10 . The method of  claim 9  wherein the selected iris area is determined by the desired shape of the cells of a SRF cavity. 
     
     
         11 . A two-step tube-necking spinning processing method, comprising:
 providing spinning apparatus;   providing a work piece of metal tube;   providing a primary forming roller having a selected profile;   radially driving the primary forming roller on the work piece by means of a driving mechanism of the spinning apparatus and then moving the primary forming roller along the axial direction by means of a driving mechanism of the spinning apparatus while the primary roller rotates around the work piece and the work piece is stationary, thereby drawing the metal tube to form a section of reduced diameter and the first part of a necking shape;   providing a secondary forming roller having a selected profile, the profile including   a nose; and   radially driving the secondary forming roller on the work piece by means of a driving mechanism of the spinning apparatus and then moving the secondary forming roller along the axial direction by means of the driving mechanism of the spinning apparatus while the secondary roller rotates around the work piece and the work piece is stationary, thereby drawing the metal tube to form a section of further reduced diameter and the second part of the necking shape.