THE ROLLING PROCESS FOR EXTERNAL THREAD OF DRILL ROD

The factors having effect on the quality of external thread of drill rod are rolling machine and rolling technique.Two shortcomings are existent in designing of the present thread rolling machine.The first is that the thread rolling die and drill rod slip somewhat in the rolling process.Secondly there is error between the thread roll angles of thread rolling die and drill rod.Based on two basic rolling conditions,eight parameters needed by design and seven theoretical calculating formulas,the new design of the thread rolling die has overcome the above two shortcomings.About rolling technology,the hot rolling is of simple process but easy to change the shape of the rolled thread,while the cool rolling is on the contrary.A new rolling technique,i.e. multiple rolling,is illustrated which is the synthesis of hot rolling and cool rolling.