A methodology of roll pass design calculation for rails rolling using regression equations

In process of shaped profiles experimental rolling, it is often necessary to make adjustments to new roll pass design to ensure their physical filling, control between gaps in the values of real broadenings and reductions. In order to reduce number of possible adjustments in roll pass design process and mastering new profiles, the task of developing a model for calculating roll passes becomes actual. A model for calculating roll pass design for rolling railway rails presented. This model based on roll pass design for rolling R65 rails. The regression equations of deformation logarithmic degree were derived using example of two pre-finishing and finishing roll passes, which were used to calculate UIC60E1 rail roll pass design. A high degree of convergence of the geometry of the calculated and operating roll pass has been established. The maximum deviations from geometry of existing roll pass and calculated ones according to proposed method did not exceed 1-2 mm on each of them. It was shown that the developed model calculates exact roll pass geometry, which can be loaded into the program of a processing machine. The proposed calculation methodology can be used at roll pass design of shaped profiles of the same type of different profile sizes of the same mill, resulting in significant reduction of roll pass designed development time and number of adjustments.

THE CONCEPT OF OPTIMAL BAR ROLL PASS DESIGN. REPORT 3. SPACE OF ROLL PASS DESIGN SCHEMES

Based on the system approach and on the experience accumulated at theoretical data, design and industrial development of bar rolling, the Chair “Metal Forming” of Ural Federal University develops the universal “Concept of optimum calibration”. The general ideology of roll pass design optimization is stated in article “The concept of optimal bar roll pass design. Report 1. Basic statements”. In the article “The concept of optimal bar roll pass design. Report 2. Calibers space” the structure, appointment and maintenance of the information block reflecting so-called “calibers space” are considered. According to the general concept of optimization, the following task that needs to be solved is the problem of creation of information block so-called “space of schemes of roll pass design” which will be used further as the first space of optimization. The concept “space of schemes of roll pass design of a bar-rolling mill” is considered as the space containing all possible virtual schemes of rolling of a concrete profile on the concrete rolling mill. For formation of the space of schemes of rail calibrations it is necessary to generate separate virtual schemes and to consistently fill this space with them. Thus, the space of calibrations schemes is formed of separate unique calibrations schemes. For formation of this space from separate calibers, it is offered to use the specialized algorithms which are “generators of schemes of roll pass design”. As an example, the structure of the generator prepared for creation of such space for rolling of railway rails is considered. It is revealed that all known rail calibrations can be presented in the form of essentially the same block structure which is used as the central element of the schemes generator of rail calibrations. Usage of described and similar generators in relation to rolling process of a concrete profile on the concrete rolling mill allows obtaining spaces of acceptable schemes of calibrations. Such spaces are necessary for the subsequent optimizing procedures for search of the best calibration scheme from all possible calibrations. The considered approach for creation of calibrations schemes space can be used during creation of computer-aided engineering systems and optimization of calibrations of rolling rolls.

Calibration of ball-rolling rollers with continuously variable pitch

Presented is the state of ball rolling production, review of existing techniques for roll pass design ball-rolling today development. Possibilities of roll pass design with regard to the existing metal cutting equipment and variation of pitch parameters. The priority is set for the use of rolling rolls with a continuously varying pitch, in comparison with rolls with discretely varying pitch. Possibility of using 5-axis milling equipment for obtaining a given profile, with several variable values, is shown. Model is developed for calculating the roll pass design for rolls with a continuously varying pitch, the save constant amounts of metall of workpiece between the rolls in every moments. Pitch change functions for roll pass design of ball rolling with a constant and variable flange width are derived, using which it is possible to determine the theoretical pitch at any rolls rotation angle. Technique for constructing a 3-D model is developed, based use on obtained curve of the 2nd order, which is the basis helical surface with a continuously varying pitch. Production of profile on a 5-axis machining center, according to the the 3D models suggest. Roll pass design was used ob the experience practical, with production example ball with a diameter of 120 mm, which were calculated from the deduced function for rolls with a constant width of the flange. He was tested in the conditions of the newly introduced ball-rolling mill of JSC "EVRAZ-NTMK". After introduction of a new roll pass design, were resived technical results: the reduction in force rolling, in contrast at use operating rolls with discretely varying pitch, by 25–30%, obtaining ball sizes that are as close to nominal values GOST standard, decreased of defects, uniformity forge along entire length of the rolls forming-part obtaining.The analytical solutions presented in this article, in combination with industrial approbation, make it possible to use a new method roll pass design rolls of a ball rolling mill with a continuously changing pitch for educational and production purposes.

Increasing the Durability of Separating Rolls During Rolling Ribbed Bars in the Three-Strand Technology

The paper presents the results of investigations aimed at enhancing the durability of slitting passes in the process of three-strand rolling of 16 mm-diameter ribbed bars. Using the Forge2011® computer program, numerical modelling of the rolling process was carried out in order to examine the variations in band shape in individual rolling passes, to verify the correctness of the designed new slitting pass system, to determine the local strains in the rolled band, and then to determine the distribution of unit friction force work on the roll groove surface. From the obtained investigation results it was found that the application of the new roll pass design in stands 13-16 increased their durability in the rolling process by approx. 30%. The wear of the roll sets for the stands under examination after rolling out the annual 16 mm-diameter bar production volume was determined in the study. The obtained numerical modelling results were verified in experimental tests.