RU2457069C1 - Method of punching axially symmetric thin-wall parts from powder materials - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to metal forming and may be used for producing round articles with fine-grain structure. Punching is performed in one slide stroke in die heated to billet material recrystallisation point and comprises two steps. At first step, punching is made with process force of 0.35-0.4 of that required for punching with no twisting and developed by male die translating in time required for billet to reach die temperature. At second step, male die translates and rotates simultaneously with liner-to-angular speed ratio varying with the length of generatrix of v/ω=kL_i, where k is coefficient depending upon finite length of part generatrix L_i and its thickness S_i.

EFFECT: decreased deformation force, higher quality of parts, rules out porosity.

3 dwg, 1 tbl, 1 ex

Description

The method of stamping axisymmetric thin-walled parts from powder materials relates to the processing of metals by pressure and is intended to produce round in terms of products with a fine-grained structure.

A known method of processing metals, which consists in placing the workpiece in a stamp, consisting of a punch and a matrix located coaxially to one another, and its subsequent deformation by a punch that performs translational movement with speed (ν) and rotates with angular speed (ω). When the punch rotates, the workpiece is subjected to a torque that changes the contact friction conditions between the workpiece and the tool, facilitating the radial flow of metal, and also causes tangential shear deformations inside the workpiece (Subich V.N. Plastic flow of materials in a thin layer under combined loading. - Forging and stamping production. 1986. No. 10. S. 5-7). This method is adopted as a prototype.

The disadvantage of using the known method for the production of parts from sintered powder billets is the significant energy consumption of the process for heating the billet, low quality of parts due to oxidation of the pore space and insufficient thermomechanical conditions.

The proposed method of stamping axisymmetric thin-walled parts from powder parts provides a reduction in the technological force of deformation, an increase in the quality of the parts, a decrease in the grain size of the workpiece and the elimination of porosity.

где k - коэффициент пропорциональности, находящийся в зависимости от конечной длины образующей L_i и ее толщины S_i (табл.1).The technical result, which the claimed method is aimed at, is ensured by the fact that during stamping of axisymmetric thin-walled parts from powder materials, the process is carried out in a die heated to the temperature of the onset of recrystallization of the workpiece material in one stroke of the press slider, which includes two stages. At the first stage, stamping is carried out with a technological force equal to 0.35 ... 0.4 of the force required for torsion-free stamping, created by a punch that performs only translational motion for the time necessary to reach the stamp temperature. At the second stage, the translational and rotational motion are simultaneously with the ratio of linear (ν) and angular (ω) velocities proportional to the length

where k is the coefficient of proportionality, depending on the final length of the generatrix L _i and its thickness S _i (Table 1).

The essence of the proposed technical solution is illustrated by a drawing and photographs:

- figure 1 shows a device for implementing the proposed method;

- figure 2 shows pre-sintered blanks of powder material before stamping;

- figure 3 is the appearance of the products after stamping.

The implementation of the method is carried out in the device (figure 1), containing the upper die holder 1, having two dowels 2 to prevent the rotation of the punch during stamping. A punch 3 is fixed in the die holder. A die 8 is fixed in the lower die holder 6. A plug 5 is provided for pushing the product out. A backing plate 4 and bolts 7 are used to fix the die.

где k - коэффициент пропорциональности, находящийся в следующей зависимости от конечной длины образующей L_i и ее толщины S_i (табл.1).The method is as follows. The stamp before stamping is heated to the temperature of the onset of recrystallization of the workpiece material. A pre-compacted and sintered preform of powder material (Fig. 2) is placed in a matrix and deformed with a punch in one stroke of the press slide, which includes two stages: at the first stage, stamping is carried out with a technological force equal to 0.35 ... 0.4 of the force, required for torsion-free stamping, created by a punch that performs only translational motion for the time required to reach the workpiece temperature of the stamp, and in the second stage, both translational and rotational motion with the line ratio hydrochloric (ν) and angular (ω) speed proportional to the length of the generatrix,

where k is the proportionality coefficient, which depends on the final length of the generator L _i and its thickness S _i (Table 1).

Thus, in this mode of torsion precipitation, it is possible to achieve the required grain size of the product, reduce porosity and reduce axial force while increasing the energy required to consolidate fragments of the powder material.

An example of a specific implementation of the method

The composite powder 30% W-3% Ni-42% Cu was pre-compacted in a special die, sintered in a furnace in a hydrogen medium at a temperature of 960 ° C for 12 hours. Stamping was carried out on special equipment, providing both translational and rotational movement of the punch. Sintered blanks were placed in a die heated to a temperature of 450 ° C. To equalize the temperature over the cross section of the workpiece, it was pressed with a punch with a force of 50 kN and kept in the pressed position for 30 s. During stamping, the deformation force was 1.25 MN, and the torque was 10 kN · m. Stamping was carried out in one stroke of the press, while the angle of rotation of the punch was varied within 5.5-6 rad, after which the product (Fig. 3) was removed from the matrix using an ejector and blacksmith mites. Then they laid a new blank, and the process was repeated.

Table 1 The dependence of the coefficient of proportionality k on the finite length of the generatrix L _i and its thickness S _i

Proportionality coefficient k ≤5 0.12-0.08 15-20 0.044-0.034 5-10 0.08-0.058 20-30 0,034-0,028 10-15 0.058-0.044 ≥30 0.028-0.02

Claims (1)

A method of stamping axisymmetric thin-walled parts from powder materials, comprising placing a pre-compacted and sintered billet in the matrix and deforming with a punch that can translate with linear velocity ν and rotate with angular velocity ω, characterized in that the stamping is carried out at a temperature of the onset of recrystallization the workpiece material for the stamp in one stroke of the press slider, which includes two stages, while the first stage is stamping force equal to 0.35-0.4 of the force required for torsion-free stamping, created by a punch that performs only translational motion for the time required to reach the workpiece temperature of the stamp, and in the second stage, with a punch that performs both translational and rotational movement with a ratio of linear and angular velocity proportional to the length of the generatrix ν / ω = kL _i , where k is the proportionality coefficient, which depends on the final length of the forming part L _i and its thickness S _i .

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