Papers by Keyword: Drawing

Abstract: To improve the quality of human life, sometimes, surgical interventions are required to replace or retain damaged tissue during reparative regeneration. Titanium and titanium alloys are well-proven biocompatible materials. The methods of modeling the phase composition of the titanium alloy can be used to predict the chemical and physical-mechanical properties of implants and suture material. In this research, the features of the titanium drawing process are investigated, recommendations are given for thermo-mechanical processing and the choice of a lubricant. Modeling the structure and phase composition of alloys allows predicting their properties and choosing the optimal technological parameters for all drawing transitions. Drawing must be performed in a friction mode close to the hydrodynamic regime with intermediate annealing to control the phase composition of titanium, restore the plasticity resource, and heal crystal structure defects. The composition of atmospheric gases during annealing makes it possible to control the phase composition and properties of the alloy. The use of exfoliated graphite is proposed as a lubricant applied to the anodized titanium surface.

Abstract: This paper presents constructions of roller dies have been proposed, which make it possible to produce wire of simple and shaped profiles with a diameter of 0.5 to 12.0 mm. Technological solutions for the production of a hex profile S = 2.2 mm from a billet of hard-to-form alloys AISI 316, AISI 304, Ti3Al5Mo5V of various diameters are shown. To increase the service life of the dies, the rollers made of heat-treated steel of the X162CrMoV12 grade are recommended to be strengthened by applying a functional coating made of WC-10Co-4Cr alloy on the working surface by detonation sputtering followed by melting of this layer with a laser. Studies carried out on the samples showed a sevenfold increase in wear resistance in comparison with similar ones subjected only to the traditional for X162CrMoV12 heat treatment in the form of quenching and tempering.

Abstract: The article presents an overview of possible technological schemes to produce an overhead contact wire for railways. Pilot experiments were carried out on the manufacture of a contact wire made of CuMg0.3, CuMg0.4 and CuMg0.5 alloys and having a nominal cross section of 100 mm². The contact wire was obtained from a continuously cast rod with small section, which was subjected to plastic deformation using the Conform technology and cold drawing of the extruded rod. In the casting process, we encountered the formation of cracks on the cast rod surface and the rods breakage. The inner surface of the graphite bushings of the mold after casting the rod was studied and a thin gray layer was found on the inner surface of the graphite bushings. Areas of the graphite bushing with gray layer were studied by scanning electron microscopy and element-by-element mapping was performed with the selection of a spectrum in the sediment layer area. In order to determine the phase composition of the sediment layer it was analyzed by the method of full-profile analysis of the X-ray diffraction pattern according to Rietveld. X-ray phase analysis showed the CuMg₂ and Cu₂Mg phases presence. This allowed us to assume a possible mechanism for the formation of the sediment layer. Ultimate tensile strength, elongation and electrical resistivity was determined. Analysis showed that the overhead wires made of CuMg0.3, CuMg0.4, CuMg0.5 alloys meets the requirements of GOST R 55647-2018 for wires made of the second conditional group bronze.

Abstract: Plastic forming, in many cases, includes the drawing of hollow cylindrical products as the main operation. For the manufacture of such products, round blanks are used as semi-finished products. However, during the blank production from strips or tapes, their geometry causes a very significant metal loss. A very effective way to reduce metal loss is to replace round billets with square ones. The use of square blanks gives an additional increase in the height of the products. In this regard, the article investigates the drawing of a square blank into a cylindrical die. The research was carried out on the basis of the analysis of experimental work and computer modeling. According to the results of the research the rational ratios of the geometric dimensions of the tool and workpieces are found.

Abstract: Cu-14Fe-0.05C alloy was prepared by using the vacuum melting process and then multipass drawing deformation was performed. The results showed that with rise of drawing strain, iron-rich phases in the Cu-14Fe-0.05C alloy gradually change from irregularly distributed coarse dendritic phases in the as-cast state to slender fibrous ones distributed parallel along the drawing direction. The higher the strain is, the slender and denser the fibers are and the more uniform the distribution is. Moreover, more interfaces are found between copper matrix and iron-rich phases and the hardness and resistivity of the alloy become higher.

Abstract: Cu-14Fe-0.05C alloy was prepared by using the vacuum melting process and then multipass drawing deformation was performed. After that, the alloy in the as-drawn state was annealed. Based on this, the influence of annealing temperature on microstructure, mechanical performance and electrical conductivity of the alloy was studied. The results showed that the speed of recovery and recrystallization of the as-drawn Cu-14Fe-0.05C alloy accelerates and iron-rich fibers gradually become slender, bend and fracture, with the increase of annealing temperature. The tensile strength of the alloy constantly decreases, while elongation continuously rises and resistivity gradually reduces. With the extension of annealing time, tensile strength and resistivity of the Cu-14Fe-0.05C alloy gradually decreases, while elongation gradually increases.

Abstract: The manufacture of tubes by a fixed mandrel drawing is one of the technologies in the manufacture of seamless tubes. This is the oldest tube drawing method. It uses a mandrel at the end of the die to shape the internal diameter of the tube. This process is slow and the area reductions are limited (lengths of tubes are limited), but it gives the best inner surface finish of any of the processes. The use of a fixed mandrel by the drawing of small-diameter tubes makes it possible to increase the accuracy of the inner surface and improve the quality. The paper presents the results of solving a partial task in this area. It deals with the reconstruction of the microgeometry of the inner surface of a tube drawn by a fixed mandrel. Tubes (STN 41 1353) were drawn through dies with different reduction angles. There were grounds the straight and spiral grooves on used fixed mandrels. On the inner surface of the tube were formed grooves after drawn that had a different surface roughness compared to the mandrel surface. The paper graphically presents the morphology of obtained surfaces under various conditions (reduction angles, straight/spiral grooves on the fixed mandrel) as well as measured surface roughness values. At the end of the paper, the knowledge gained through experimental research are summarized.

Abstract: This article present the results of studies of the process of wire drawing from the PdNi-5 alloy, performed using computer simulation in the DEFORM 3D software package. В качестве материала для исследований использовали сплав с содержанием 95% палладия и 5% никеля. An alloy with a content of 95% palladium and 5% nickel was a material for research. The patterns of changes in the stress-strain state for the current processing mode determined, and a more rational drawing mode with a redistribution of drawing coefficients along transitions proposed. For the proposed regime, using the created model, the values of drawing stresses, drawing forces and Cockcroft-Latham criterion determined. It was found that the stress distribution in the deformation zone corresponds to the generally accepted laws of their change, and their maximum values are realized in the metal located in the calibrating zone of the drawing die. In addition was revealed that the stresses in the current mode have limit values at the second and fourth passes. The redistribution of deformation indicators in the proposed mode allowed reduce the magnitude of these stresses and, thereby, reduce the likelihood of wire breaks. The maximum value of the Cockcroft-Latham criterion is achieved in the last transitions, but at the same time, destruction will not occur, since they do not exceed the limit value. The drawing force also decreases with the implementation of the proposed mode and does not exceed the permissible values regulated by the technical characteristics of the equipment. Since it is the proposed mode of wire drawing, it is characterized by a decrease in energy power indicators and the likelihood of wire breakage in the process of metal deformation it can be recommend it for implementation in existing production.

Abstract: On the basis of the fluid flow hydrodynamic theory, the problem of obtaining a given thickness metallic coating on long metallic articles is solved. The process of forming the coating thickness includes applying it from the molten metal, followed by deformation together with the product. Theoretically, the dependence of the coating thickness on the speed of the product movement in a liquid metal environment, as well as the degree of product deformation during drawing, is determined. Experimental verification showed good convergence of theoretical results with experimental data. The practical result of solving the task is the ability to control the process of forming the metal coating thickness by the movement speed of the product in a liquid metal environment and the degree of its deformation during drawing. A diagram of an industrial plant for applying various thickness coatings on lengthy products is presented. The results are used in the production of brass pipes, coated with tin, for car radiators.

Abstract: This paper presents an efficient analytical method for design of streamline dies driven by fracture. The method is based on Bernoulli’s theorem relating pressure and velocity along any streamline extended to ideal flows in plasticity. The Cockroft-Latham criterion is adopted to predict the initiation of ductile fracture. In order to apply the method developed, it is not necessary to know the solution to the boundary value problem of plasticity. The final result is a simple relation between geometric parameters of the process and the constitutive parameter involved in the fracture criterion. Since the latter is supposed to be known for a given material, the relation determines a safe domain for drawing without fracture.