RU2116155C1 - Method for plastic structurization of high-strength materials - Google Patents

Abstract

FIELD: mechanical engineering; may be used in plastic metal working. SUBSTANCE: method includes multiple extrusion and upsetting of blank with preservation of its initial shape and sizes after each cycle of deformation. In each deformation cycle, first, one part of blank is extruded through die working parallel and after stopping of extrusion, extruded part of blank is upset; then extrusion and upsetting are alternately repeated until the whole blank is deformed. In this case, the length of extruded part of blank amounts to not more than 2.5 diameters of the die working parallel. EFFECT: extended potentialities of the method for deformation of blanks of high-strength alloyed steels and alloys. 1 cl, 5 dwg

Description

 The invention relates to mechanical engineering and can be used in the processing of metals by pressure.

 A known method [1] of metal forming, by which, when upsetting each billet, it is extruded through a deforming tool by a subsequent billet, while the rear end of the previous and the front end of the subsequent billets are upset.

 A known method of plastic structure formation [2], according to which multiple pressing of the workpiece through two intersecting channels is carried out, while plastic deformation occurs by shifting the transverse layers of the workpiece relative to each other in the area of the intersection of the channels. In each subsequent processing cycle, the workpiece is placed in the first channel and it is informed of an additional degree of deformation.

 The disadvantages of the methods include high stresses on the tool, which do not allow deformation of high-strength steels and alloys.

 Closest to the proposed is the method of structure formation [3], in which the preform is repeatedly deformed by extrusion with simultaneous settlement of the extruded part of the preform, while maintaining its original shape and size after each deformation cycle. In each subsequent deformation cycle, the extrusion direction is reversed relative to the previous cycle.

 A disadvantage of the known technical solution is the inability to deform alloyed and structural steels and alloys. Sediment of the extruded part of the workpiece, carried out simultaneously with extrusion, acts as a support and significantly increases the voltage on the tool during extrusion. It is this factor, together with high mechanical properties and low ductility at room temperature of alloyed and structural steels and alloys that makes the process of deformation of these materials impossible.

 The objective of the invention is to expand the capabilities of the method of plastic structure formation for deformation of workpieces of high strength alloy steels and alloys.

 The problem is achieved by the method of plastic structure formation, including repeated deformation of the workpiece while maintaining its original shape and size after each deformation cycle. The direction of extrusion in each subsequent cycle is reversed relative to the direction of extrusion in the previous cycle. In each cycle of deformation, a small part of the workpiece is extruded through the working belt of the matrix, the extrusion is stopped, the extruded part of the workpiece is deposited with a second punch in the second part of the matrix, then the part of the workpiece and its draft are repeated alternately until the entire workpiece is deformed. The length of the part of the workpiece extruded through the working belt should not exceed 2.5 diameters of the working belt of the matrix.

 The method of plastic structure formation is illustrated by figures, where the left part of the figure is the position before deformation, the right is the position after deformation.

 In FIG. 1 shows the initial stage of extrusion of the initial preform; in FIG. 2 - sediment extruded part of the workpiece; in FIG. 3 - subsequent extrusion of part of the workpiece; in FIG. 4 - sediment extruded part of the workpiece; in FIG. 5 - removal of the workpiece from the matrix.

 A device for implementing the method comprises a matrix 1 having two channels of the same cross section, a punch 2 is installed in one of the channels, a second punch 3 in the second channel, and a workpiece 4 is laid between them.

 An example of a specific implementation.

 The method is as follows. The initial workpiece 4 is placed in the matrix 1, the punch 2 extrudes a small part of the workpiece through the working belt in the lower part of the matrix (Fig. 1). Then, the second punch 3 sags the extruded part of the preform (Fig. 2). Further deformation is carried out by alternately performing operations of extruding part of the workpiece by the punch 2 through the working belt of the matrix (Fig. 3) and precipitating the extruded part by the second punch 3 (Fig. 4). The extraction of the deformed workpiece from the matrix is carried out using a graphite chamotte washer (Fig. 5).

After removing the preform, it can again be placed in the matrix for subsequent deformation. Deformation cycles - extrusion and sediment can be repeated repeatedly until the desired degree of accumulated deformation is obtained. To improve the quality of structure formation when repeating deformation cycles, the workpiece is placed in a matrix with a 180 ^° tilt to change the direction of deformation. The repetition of deformation cycles makes it possible to form a given structure of the metal, and hence the required level of its mechanical properties. The shape and dimensions of the workpiece are not changed. To prevent the loss of stability of the part of the workpiece extruded through the working belt, its length should not exceed 2.5 diameters of the working belt of the matrix.

где
F₀ - площадь поперечного сечения канала матрицы при D=35 мм;
F₁ - площадь поперечного сечения рабочего пояска матрицы при d=28 мм.As a starting material, a bar of steel P6M5 with a diameter of 40 mm was taken in the delivery state. The carbide heterogeneity score was 36 points (according to GOST 19265-73). Billets with a diameter of 34 mm and a length of 60 mm were machined from the bar. The deformation was carried out under isothermal conditions at the temperature of the α-γ phase transition at the point Ac1. The billets were heated to a temperature of 830 ^o C and were placed in a snap, heated to the same temperature. The temperature control of the matrix was carried out using a control thermocouple, with an accuracy of ± 5 ^o C. The deformation was carried out on a hydraulic press at a low speed for two cycles, with a total integral strain index e = 3. The integral degree of deformation in one cycle was determined by the formula:

Where
F ₀ is the cross-sectional area of the matrix channel at D = 35 mm;
F ₁ is the cross-sectional area of the working belt of the matrix at d = 28 mm

 As a result of deformation, the carbide structure of the metal was destroyed. Carbides more evenly distributed over the cross section of the workpiece. The size of carbides decreased, the score of carbide heterogeneity (according to GOST 19265-73) was 1 point. A tool made of these blanks for cold heading of bolts and nuts showed a higher fatigue resistance of 15-20% compared to the starting material.

Claims (1)

 The method of plastic structure formation of high-strength materials, including repeated extrusion and draft of the workpiece with preservation of its original shape and size after each deformation cycle, in each subsequent cycle, the extrusion direction is opposite to the extrusion direction in the previous cycle, characterized in that each deformation cycle is first produced extruding part of the preform through the working belt of the matrix, extruding is stopped, the extruded part of the preform is deposited, for thereby repeating alternately extruding part of the preform and its draft until the entire preform is deformed, while the length of the extruded part of the preform is no more than 2.5 diameters of the working belt of the matrix.

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