METHOD OF CALCULATION OF THE SETTING PARAMETERS OF THREE-ROLL RILING MILLS
The purpose is substantiation of the methodology for analytical determination of the parameters of the initial setting and correction during pipe rolling in three-roll riling mills by developing a mathematical model of the process.
Methods. When performing the research, the equations connecting the geometric dimensions of the initial workpiece, the finished pipe, and the diameter of the roll caliber were used, as well as a mathematical model of the process of deformation of the pipe in a three-roll riling mill, which allows, for given geometric parameters of the rolls and mandrels, to determine the change in wall thickness and diameter of the workpiece along the length of the deformation zone.
Results. It is proposed to conduct rolling of pipes for the entire production range of TPA-140 at feed angles equal to 6° instead of 9…12°. Taking into account that at the same time, the maximum possible diameter of the rolled pipes is reduced, to compensate for this decrease, it is proposed to make the exit section of the roll two-conical; the taper of the first section along the direction of rolling is 1,6…1,7°, the second section 2,4…2,6°.
Taking into account that increase in relative reduction along the workpiece wall in the range 0,02…0,10 reduces the difference in wall thickness of rolled pipes; it is proposed to design deformation modes, focusing on the value 0,10, reducing the value in cases where this is due to the need to avoid excessive rolling (diameter rise) of the workpiece, or to prevent exceeding the permissible loads on the mill drive.
It has been established that when 9…12° it is possible to limit the length of the conical section of the mandrel to the value 80…100 mm, and for feed angles 6…7°– to the value 60…80 mm. At the same time, the possibility of adjusting the thickness of the pipe wall will be preserved in the range of ±1 mm due to axial movement of the mandrel.
Originality. The method for calculating the parameters of the initial setting of the riling mills and their adjustment during rolling is substantiated. A mathematical model of the process of rolling pipes in a three-roll rolling mill has been developed, which links into a single system the equations describing the geometric parameters of the tool (rolls and mandrel), the dimensions of the workpiece and pipe, as well as the technological parameters of the mill setting (feed angle, diameter of the caliber, diameter and position of mandrels relative to the pinch of the rolls). The principles underlying the selection of the parameters of the deforming tool and the determination of the settings of the mill are formulated.
Practical implications. A number of changes in the calibration of rolls and mandrels of the riling mills were substantiated, as well as their settings. The effectiveness of the proposed technical solutions and the developed method for adjusting the rolling parameters have been successfully tested in industrial conditions.
Burjanov, V. F., Rokotjan, E. S., Gurevich, А. Е. (1962). Raschet moshnosti dvigatelei glavnih privodov prokatnih stanov. Moskva: Metallurgizdat
Ostrenko, V. Ja., Rohman, D.Е. (1954). Davlenie metalla na instrument i moshnost’ processa pri raskatke trub na raskatnih mashinsh. Trudi VNITОМ, Vol. 2, Мoskva: Metallurgizdat, 74-84
Gulyaev, Yu. G. (1978). Kompleksnoye issledovaniye processa prokatki trub v trehvalkovom raskatnom stane i vibor optimal’nogo rezima deformacii. Dis. … cand. techn. nauk. Dnepropetrovsk: DMetI