Benefits of Using Three Dies Rolling Machines

Three-die, cylindrical, hydraulic thread rolling technology yields higher-precision threading as well as a more efficient operation that results in higher-quality parts.

The choice of three-die cylindrical hydraulic thread rolling machine is due to the following factors:
•Precision of threading operation because the three rolls automatically balance the forces and maintain the part in a central position.
•Higher part quality because there is no work rest blade to hold the workpiece that can damage the thread lead.
•Higher productivity because it is possible to work at a 30% higher speed compared to a two-die thread rolling machine.
•Better penetration factor because the pressure is automatically balanced within the three dies and the strength necessary to form the material is divided on three dies instead of two dies.
•The workpiece always stays in its axial position, so in the case of long parts it is not necessary to move or adjust the loading/ unloading system.
•Metallographic studies of the cold forming process involving threads from bar using a three-die cylindrical rolling machine in a thru feed operation show a large flow of material in the first stages of the forming process. As the forming process proceeds, the material flows further inside the workpiece, while the height of the forming area remains at almost the same level.

The closed shape of the lead of the thread shows that the material has flown uniformly. The forming process with a three-die thread rolling machine can be divided into three stages:
-Stage 1- Dies enter into the material for 25% of the nominal depth of thread; the material on the thread root reaches the highest strength.
-Stage 2 – Dies enter into the material for 50% of the nominal depth of thread; the material on the thread sides reaches the highest strength.
-Stage 3- Also as the dies enter into the material for 50% of the nominal depth of thread, the material flows to reach the desired thread shape and the strength of the material remains unchanged.

As a matter of fact, with three-die thread rolling technologies it is possible to form dedicate components