Page 27 - ITAtube Journal 1 2019

Technical Papers
Non-steady-state deformation conditions of the end sections of the workpiece are represented by the model very realistically from a qualitative point of view. Formation of shape deviations from a regu- lar-shaped cylinder at cross-roll piercing like flare and sink mark on the front and rear ends of the hollow shell is shown on Fig. 6. An imperfection like a “snout” appears in the model when the plug exits from the shell
Conclusions
1. The simulation of piercing solid billets of diam- eter 190 and 250 mm to hollow shells ø 270 x 44.7 and ø 200 x 31.8 at two-high screw rolling mill TPA 70-270 JSC VMZ using the QForm soft- ware package was carried out. Piercing was made by one pass instead of the two passes, normally used at this mill. The advantages of this mode are obvious, but the risk of exceeding energy and force parameters of deformation also increases as well as the likelihood of producing shells with unsatisfactory geometry. Metal forming simula- tion allows estimating such risks.
2. The calculated and actual values of energy and force parameters of the piercing operation, geometrical parameters of the shells and its deviations are compared. It is found that the systematic deviations of geometrical parame- ters and their tolerances are of the same order. The value of the systematic deviations has to be determined in trial rolling and should be taken into account while determining the final tech- nological regime. The estimated values of energy and force parameters for the observed cases are approximately 20% higher than actual values. Such error is acceptable, and more especially it provides a safety factor.
3. The main reason for these errors is the uncer- tainty of the model input data that are unlikely to be diminished at the existing conditions. The typical finite element size must be of the same order as the tolerance for the linear dimensions of pipes.
4. Using the QForm software for verifying technolog- ical settings in seamless pipes production looks reasonable. This approach to the development of the production technology allows avoiding eco- nomic losses while designing new technological tools, testing new piercing regimes in order to implement them at the present production facil- ities.
References:
1. http://www.qform3d.com/.
2. Kalmykov, V.V., Ananyev, I.N., Bayramov, O.F., 1984. Calculation of energy and force parameters and formability at rolling in the roughing stands of hot strip mills by finite element method. Moscow: Bauman Moscow State Technical Uni- versity Proceedings, # 412, Machines and aggre- gates of the metallurgical production, pp. 57–67.
3. Voskanyanc, A.A., Ivanov, A.V., 2004. Investiga- tion of screw cross rolling by a three-dimensional finite element model. Proceedings of all–Russian scientific and technical conference devoted to the 100th anniversary of the member of the Academy of Sciences A.I. Tselikov (Moscow, April 14-15, 2004), Edited by Voskanyanc, A.A. Moscow: Bauman Moscow State Technical Univer- sity, pp. 332–340.
4. Aleshchenko, A.S., 2010. Research and develop- ment of the methods for designing technological tools for cross-roll piercing of hollow shells and pipes: Ph.D. thesis, technical sciences, Moscow, 147 p.
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ITAtube Journal No1/February 2019
27