The paper demonstrates that as the energy industry develops, there is a continuous process of improving the designs of contact electrical connections. Bimetallic contacts are becoming more common. Their performance depends on the morphology and strength of the connection layers. Clad workpieces with various heat treatment modes were researched. The strength of the joint of the laminated compound was also determined. With increasing temperature and heat treatment time, the concentration as well as the amount of intermetallic compounds in the weld zone increases. When the layer of intermetallic compounds reaches a certain value, the effects of increasing temperature and increasing time are weakened. Observations show that a low annealing temperature with a short heat treatment time can significantly improve the strength of the clad compound joint.

The Research of the Morphology and Mechanical Characteristics of Electric Bimetallic Contacts

Questions of experimental study regarding the stress-strained state in the radial rotary method of producing the steel rims of wheels are examined. The physical simulation of the process of profiling the rims is performed on the installation, designed especially for these purposes. The models of the narrow-profile and wide-profile rims of wheels were tested. The grids method was applied for conducting the experiments. The obtained information was processed by the methods of mathematical statistics and probability theory. The results of experimental data made it possible to arrive at a conclusion about the most dangerous sections of the profiles of the rims of wheels, which, in the process of deformation, obtain compressive radial deformations, which confirms the studies conducted previously. The largest deformations occur in the places of radius couplings of the profile, deformations increase from one transition to the next and their total magnitude can exceed the permitted by 20 % of the initial thickness of the workpiece. No essential difference between the two schemes of profiling the rims of wheels was revealed.

http://journals.uran.ua/eejet/article/download/76225/72367

Determining experimentally the stress-strained state in the radial rotary method of obtaining wheels rims

The paper deals with the analysis of the possibility of intensifying the process of drawing sheet workpieces by changing the design of equipment It is shown that this method of sheet stamping is characterized by the introduction of non-waste technologies and the production of parts that do not require final processing However, the task of developing rational technological processes of drawing, requiring the minimum labor input and the cost of manufacturing specified parts with the best quality, is still particularly urgent Modern enterprises operating in conditions of frequent changes in the range of manufactured parts seek to minimize the cost of tools and equipment to reduce the cost of the process Therefore, the unification of the tool, simplification of the design of die tooling in the conditions of flexible serial production will make it possible, with minimal loss of time, to switch to the release of new products A method of pressure-free stamping using a telescopic punch is proposed Also, the fundamental possibility of drawing by the proposed method is confirmed based on the performed research A method for calculating the punch lock springs is developed The demonstrated technological calculations make it possible to proceed to the design and calculation of die tooling and punch power springs, which contributes to the manufacture of high-quality parts, reducing labor intensity and eliminating the use of a double-acting press As a result, the proposed technical measures will reduce the technological cost of the product

The Manufacture of Cylindrical Parts by Drawing Using a Telescopic Punch

The stress-strain state has been studied for a flange of a semiproduct made of an aluminum–copper bimetal under drawing boxes rectangular in plan. These studies are carried out using a grid method, assuming that the material is isotropic and incompressible; the deformation within each cell is uniform; the deformation occurs monotonically; and the stressed state is plane and the deformed state is bulk, but the elastic deformations are negligible. In order to minimize the measurement errors of coordinate grids and reduce the time required for processing information, a CAD software package is used for simulation The billets are rectangles with explosion-welded A4 aluminum and a M4 copper layers subjected to preliminary heat treatment before the operation of drawing. The rectangular billets have been successively drawn to a height of 10 mm; after drawing, the grid and the thickness of the sample under study are measured. The samples of billets have been photographed at an identical focal length and loaded into the application program. In the program, coordinate points are applied to the grid nodes to measure the distances and coordinates of these points before and after deformation. The measurement results show that the greatest deformation is experienced by the corner zones of the billet, where the compressive stresses exhibit an increase from the angle bisector to the walls. These stresses lead to bimetallic billet delamination, as well as to occurring corrugations throughout the copper layer. The drawing is performed for 20 billets and, in each case, the corrugation on the flange surface is observed. Varying the clamping pressure in the range from 0.25 to 0.5 MPa does not lead to any positive results. The end part of the box flange experiences the greatest strain rate, whereas, when approaching the matrix hole, the strain rate exhibits a 20% decrease. The action of angular shear stresses leads to transition-zone discontinuity, which is characterized by the presence of an intermetallic layer having reduced plastic properties.

Experimental Studies on the Stress-Strain State under Drawing Aluminum–Copper Bimetal Parts Rectangular in Plan

The paper deals with the results of the finite-element simulation of the process of the tubular workpiece expansion The operability of the criteria of the stability and ultimate strain during the expansion by conical punches is verified The expansion coefficient is limited by the destruction of the workpiece in the form of a longitudinal crack along the weld joint in the heat-affected zone or in the solid metal, which mainly starts at the workpiece end, and also by the loss of the stability of the rigid part of the workpiece, causing the occurrence of a transversal circumferential fold It is demonstrated that the criteria used in production, which are obtained based on various hypotheses and assumptions of experimental information, correlate with numerical models, and their results practically coincide The expansion of the isotropic workpiece is compared with the workpiece with cylindrical anisotropy at the equal conditions of strain It enabled the determination of the initial anisotropy influence on the distribution of stresses and strains during the expansion It is shown that an increase in the anisotropy parameter in the axial direction, as compared with the cylindrical plane, makes it possible to increase the coefficient of the expansion in comparison with the isotropic model of the workpiece The performed development does not exclude the possibility of using the proposed simulation method to solve engineering problems concerning production optimization

Finite-Element Simulation of the Process of the Tubular Workpiece Expansion in the Manufacture of Automotive Parts

There considered questions concerning determination of stress field during form alteration of wheel crowns from steel cylindrical works at the first pass of radial- rotary profiling. There also fulfilled process analysis of drawing process of cylindrical pieces made of sheet metal. Determination of stresses at bending radius of profiling roll while shaping and on stretching edge of die body while drawing is of great interest, as coupling areas of various profile elements of crown are the most loaded and on the value of meridian stress depends the possibility of getting of high-quality piece per stretching pass. Results of theoretical research allow to analyze stresses, which arise while deforming, and determine group of technological and constructional parameters of profiling and stretching process, which affect greatly the value and distribution of normal and shear stresses.

Distribution analysis of stresses across the stretching edge of die body and bending radius of deforming roll during profiling and drawing of cylindrical workpiece

Dmitrii Savelov

Papers

Distribution analysis of stresses across the stretching edge of die body and bending radius of deforming roll during profiling and drawing of cylindrical workpiece