Axial force in helical rolling

The article shows that a key factor for the practical realization of the idea of the combined process “helical rolling-pressing” is the axial force during the helical rolling, which should provide continuous compression in the matrix behind the rolls. To measure the maximum axial force, which is in fact a reserve of friction forces, a special strain gauge was designed. The work was carried out at a three rolls mill with helical rolling “10-30” for hot rolling of steel bars with a diameter of 16-25 mm at reduction of 6 % in diameter and the temperature of 1000 °C. Results are presented based on 24 experiments. The research shows that the main danger in helical rolling and extrusion is not an effort lack, but rather the possibility of bending the work piece between rollers and the matrix. The possibility of raising efforts by means of using rolls with a notch at maximum compression is substantiated. The results are compared with the research of the firmware of similar profiles at three rolls mills. The article shows the prospects of optimizing the process of continuous firmware blanks into the sleeve by the use of research results, especially when the information about reserve forces (friction forces) of the helical rolling is concerned.