| 摘要 |
A method of forming a cylindrical opening in a metal sheet, for example the end wall of a container drum, involves piercing, pressing and drawing the metal sheet to provide a raised cylindrical section partly closed at one end by an annular flange. The annular flange is then bent into the cylindrical section while rolling the flange so as to permit its enlargement as necessary. The flange is provided with an internal screw thread by rolling a peripherally screw-threaded cylindrical roller of diameter less than the flange continuously over the flange surface in orbital relationship with the flange cylinder axis until the surface is deformed into a complementary screw configuration. The thread forming method may be used for any internal cylindrical surface. |
