Özet:

The work is devoted to researching a new method of hot direct-reverse extrusion of hollow conical products from high-carbon steel and determinated parameters for technological design. The considered method makes it possible to obtain in one step hollow products with different wall thickness in height, while the wall thickness in the upper part of the product can be greater than the thickness in the bottom part. The dimensions of the initial workpiece are determined by modeling using the finite element method, which ensures the simultaneous flow of metal in the forward and reverse directions during the process of forming the product, which reduces the deformation force. The use of this method also leads to a decrease in the heating of the deforming tool due to a decrease in the contact area of the deformed workpiece with the tool. The strain rate is determined to ensure the temperature interval of extrusion. The dependencies of the force of extrusion, removal of the punch from the deformed workpiece, pushing the product out of the matrix on the movement of the corresponding tool are established. The final shape and dimensions of the product with the distribution of temperature and deformations were found. For the maximum amount of extrusion force, the distributions of specific forces on the contacting surfaces of the punch, matrix, ejector and stress on the volume of the deformed workpiece were found. According to the obtained data, the technology of direct-reverse extrusion can be developed and implemented on universal press equipment, which has high productivity due to the reduction of the number of stamping steps. The design of the stamp for extruding products of certain sizes with forced cooling of the matrix is given.  

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