Use of Finite-Element Modeling to Improve the Piercing Operation on a Piercing Mill

Abstract

The authors evaluate the degree of agreement between results obtained from piercing continuous-cast semifinished products on a cross-rolling piercing mill and the indices of this process determined by finiteelement modeling. New piercing-mill equipment has been developed to make thin-walled hollows. Computer software is used to evaluate the optimality of the mill's settings.One of the main priorities of the Severskii Pipe Plant at present is to reduce the cost of producing the pipes that it makes. The company's success in achieving this goal will depend largely on the efficiency of the manufacturing technology used at the plant and the amount of time needed to successfully introduce new products.In order to make new products, the plant is rebuilding the cross-rolling piercing mill (made by the Elektrostal Heavy Engineering Works, EZTM) it uses to obtain hollows and is also installing an FQM mill in pipe-rolling shop No. 1. However, it is difficult to conduct experiments on the piercing mill because it is currently being run at its maximum allowable load. Thus, as is done at most companies in Russia and abroad, we decided to use recently developed computer programs that make it possible to accurately model the deformation of metal and the stress and strain distributions in semifinished products undergoing deformation and production equipment (rolls, mandrel, and guides) that is subjected to substantial loads.The use of such systems is especially important for the Severskii Pipe Plant because of the ongoing reconstruction of its pipe-rolling complex.One of the main objectives in the reconstruction project is to modify the piecing mill so that the hollows can be rolled on a continuous mill.The following had to be done in order to be able to combine these pieces of equipment: 1) design the pass system of the new mill; 2) select the values of the parameters for making adjustments to the piercing mill; and 3) identify the bottlenecks in the rolling of hollows on the piercing mill in order to ensure that the continuous mill reaches its contractual level of productivity.To model operations performed in pipe production, the factory acquired a license for the use of the software package QForm 7. This software has proven to be a valuable tool for industry both in Russia and abroad. The following models were constructed in order to evaluate the extent to which the results obtained by using QForm 7 to model the rolling of continuous-cast semifinished products on the piercing mill agree with the actual parameters of this process in the hot-rolled pipe section of pipe-rolling shop No. 1 at the Severskii plant: 1) a model to predict nonstandard situations in the piercing of continuous-cast semifinished products;