Justification for using resourcesaving banding technology in renovative production

The article substantiates the expediency of applying the basics of resource saving in the development of innovative technologies for strengthening serial parts and restoring worn ones. At the same time, the main task is the rational use of available material resources in the conditions of a decline in production, when it becomes profitable to restore metal-intensive parts worn out to a critical level. In capital repair of machines, the main problems are associated with the energy intensity of the process and a significant number of rejected parts that cannot be restored. Currently, most of the worn-out metal-intensive cast iron and steel body parts that have exhausted the resource are subjected to energy-intensive melting. For the reuse of metal-consuming parts in operation, a technology has been proposed for multilayer banding of a worn surface, in which steel tape is used instead of traditional banding rings. Winding the tape occurs under an interference in several layers. In this case, a multilayer bandage with interturn stresses is formed, which is not inferior in strength to a whole banding ring. The use of a steel “bandage” for the “treatment” of parts reduces the metal consumption for its manufacture by 2.5 times in comparison with the well-known one-piece ring made of round steel. As an example, the article substantiates the possibility of carrying out the banding process in relation to the restoration and strengthening of the seat under the bearing of the housing part. A multilayer bandage can also be used in the recovery of metal-intensive rolling rolls written off in scrap used on broadband cold rolling mills.

Efficient 3D Model to Predict Time History of Structural Dynamics in Cold Rolling Mills

Introduced is a new physics-based 3D mathematical model capable of efficiently predicting time histories of the nonlinear structural dynamics in cold rolling mills used to manufacture metal strip and sheet. The described model allows for prediction of transient strip thickness profiles, contact force distributions, and roll-stack deformations due to dynamic disturbances. Formulation of the new 3D model is achieved through combination of the highly-efficient simplified-mixed finite element method with a Newmark-beta direct time integration approach to solve the system of differential equations that governs motion of the roll-stack. In contrast to prior approaches to predict structural dynamics in cold rolling, the presented method abandons several simplifying assumptions and restrictions, including 1D or 2D linear lumped parameter analyses, vertical symmetry, continuous and constant contact between the rolls and strip, as well as inability to model cluster-type mill configurations and accommodate typical profile/flatness control mechanisms used in industry. Following spatial and temporal convergence studies of the undamped step response, and validation of the damped step response, the new model is demonstrated for a 4-high mill equipped with both work-roll bending and work-roll crown, a 6-high mill with continuously-variable-crown (CVC) intermediate rolls, and finally a complex 20-high cluster mill. Solution times on a single computing processor for the damped 4-high and 20-high case studies are just 0.37 seconds and 3.38 seconds per time step, respectively.

Improvement of methodology and development of software calculation of routes production of pipes by sink drawing taking into account accuracy

For designing routes of sink drawing pipes a certain assortment it is necessary to choose correctly the initial sizes of preparation, to calculate admissible deformations on diameter and a wall. Sink drawing to pipes after short-drawing drawing or rolling on cold rolling mills, ie pipes having a certain difference.When designing routes to drawing it is necessary to predict in advance the size and direction of change wall thickness. The analysis of influence and its character for each parameter on change of wall thickness is carried out. Taking into account the analysis and the nature of the identified dependences, tested the construction of multiple linear and nonlinear regression to determine the wall thickness of the workpiece by , , , , .To order to assess the accuracy of the pipes after sink drawing, technological routes of pipes production from carbon steel grades were developed and investigated. According to the developed routes by the production technology, batches of tubes were drawn, samples were taken from each batch and wall thickness measurements were made at equally distant points of pipe cross-section.According to the results of measurements, correlation-regression analysis was performed, factors influencing the variation of difference were determined and regression models were built.With a small diversity of the workpiece (less than 3%) the diversity of the finished pipes increases, with a diversity of the workpiece 3 ... 4% the diversity of the finished pipes changes little and > 4% the diversity of the finished pipes decreases.The intensity of the correction ( <1) depends on the compression ratio in diameter : the larger the value , the more intense the correction of the difference. That is, to correct the difference ( >4%) in the sink drawing, it is necessary to increase the coefficient of extraction.The results of research are introduced into the calculations of routes and technological maps of production in order to predict the diversity of finished pipes during drawing and supplemented the software for determining the size of the workpiece when designing routes for drawing carbon cold-formed pipes by sink drawing.