STUDY OF THE AXIAL FORCE IN A THREE-ROLL HELICAL ROLLING

摘要

In previous works, this authors developed the idea of obtaining subultrafine metal structure by implementing a combination of processes helical rolling and ECAP in one continuous process. A key factor in this combination is the axial force at the helical rolling, which should be enough for continuous extrusion mill after standing in the matrix. The study can also be useful in improving the process of piercing tube bars. The study was made on a three-roll helical rolling mill with conical rolls with diameter 71 mm. For measurement of the maximum axial rolling force, which in essence is the reserve of friction forces, was applied strain measurement (tensometrical) equipment. It was been designed and manufactured like a measuring instrument with 2 working strain gage connected by the scheme provides temperature compensation. The instrument was calibrated on a hydraulic tensile testing machine. Standard error of measurement, relative to the value of the instrument measuring range (40 kN) on the results of 42 tests was 0.2%. Experimental measurements of force were carried out in 3 series by 8 tests is each. The force was measured for conditions of the hot rolling of ordinary steel bars, diameters 16 mm, 20 mm and 25 mm with a diameter reduction of 6%; temperature 1000°C. Values of force was 15-38 kN for different diameters. The results were statistically processed. In addition, the graph data was obtained and to generalize about the nature of change in the axial force by the time.