SU1759512A1 - Method of upsetting cylindrical blanks from low-ductile materials - Google Patents

Abstract

Use: metal forming. SUMMARY OF THE INVENTION: The preform is placed in an annular casing. Carry out a joint draft of the workpiece with the shell and the subsequent removal of the shell. At the first stage, the draft is drained to the degree of shear deformation, which allows to deform the blank without a sheath, in the second stage, until the sheath breaks, at the third stage, to a given degree of deformation. The shell is made of a material with a relative elongation determined by the proposed dependency. The height of the shell is prescribed equal to the height of the workpiece after precipitation, and the removal of the shell is carried out by bending. 6 Il.

Description

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The invention relates to the processing of metals by pressure precipitation methods.

Methods are known for deforming blanks of low-plastic materials, in which the sediment is carried out with application of lateral pressure either from the side of the container walls filled with high-pressure medium or from the side of the deformable shells placed also in the container. The methods are difficult to implement, since they require the presence of special devices that limit the flow of the medium that creates lateral pressure: containers, dies, dies, etc.

There is also known a method of settling cylindrical billets of low-plastic materials, including placing the billet in an annular casing covering the middle part of its lateral surface, slumping the billet by applying a compressive force to its ends while simultaneously stretching the casing and then removing it. According to the prototype, the draft is carried out without breaking the shell; a rather ductile metal is chosen for its manufacture. During subsequent slumping, due to the effect of friction stresses on the contact surface with the strikers, barrel formation occurs, as a result of which it becomes quite difficult to remove the curved shell from the workpiece. The use of turning or etching the shell leads to an increased labor intensity and energy intensity of the process. In addition, the draft of the workpiece during the entire period of deformation is associated with high energy consumption due to the need to overcome significant backwater stresses on the shell side.

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The aim of the invention is to reduce the labor intensity and energy intensity of the process.

To do this, initially the draft of the workpiece is carried out to achieve a degree of shear deformation not exceeding its limiting Lo value during the draft of the workpiece without the shell. In the process of subsequent precipitation, a discontinuity of the shell is produced by its breaking, observing the condition

10o (eAo№-l) "5 10ofv a

 T I

Ј / 100

(one)

where d is the relative elongation of the shell material;

e- total degree of deformation of the workpiece,

Complete the draft when the height of the workpiece, corresponding to the height of the shell. The removal of the shell from the surface of the workpiece is carried out by its bending,

During hot precipitation of cast billets, the ductility of the metal increases due to the influence of two factors. Firstly, the structure of the litta is destroyed, grain refinement occurs. Secondly, the height of the cylinder decreases due to precipitation, which increases the level of compressive stresses in the volume of the workpiece. The increase in the plasticity of the metal leads to the fact that at a certain stage of the precipitation the functions of the shell turn from harmful into harmful, because the shell has to be precipitated along with the workpiece, although the role of the first as an element of the backwater has already been exhausted, However, it is precisely in the final stages of the precipitation that the energy consumption is large, since they are determined by the size of the contact surface (it is enlarged by the shell) and the geometrical factor: the ratio of the diameter of the workpiece D to the height H (it is enlarged by the shell).

In connection with the foregoing, it is advisable that after purchasing a billet of sufficient ductility, the shell will be torn off and further sediment should be carried out without backwater. The shell is put on the side surface of the workpiece under the influence of the pressure of this surface is in the state of linear stretching,

The degree of deformation Ј- | characterizes the state of the shell

 100

D2 -DO

Do

(2)

where lo and g are the shell length before deformation and after rupture;

Do and D2 are billet diameters before deformation and after rupture. 5Using the condition of constant volume

HoDo2 H2D22.

will get

ten

Јi yuo / fea -1 yuo (-. V HI / v / i -eTioo

(3)

where Ho and H2 are the height of the workpiece before deformation (FIG. 1) and after breaking the shell (FIG. 3);

Ј 100 (No-On) / But - the degree of deformation of the workpiece after the break.

To ensure the rupture of the workpiece, the degree of deformation of the shell must exceed the relative elongation of the workpiece material d. or using (3)

25

(

one

Y1 -Ј / 100

which is the right side of inequality (1).

At the same time, the shell should not break earlier than the metal of the workpiece becomes sufficiently ductile, i.e. before the shear strain rate for the metal of the workpiece reaches Lo

35

Lo v5 inHo / Hi,

where Hi is the height of the workpiece at which the workpiece can be deformed without the shell 40 (figure 2).

From the condition of constant volume

Lj0lo

 2ytln (1+),

(four)

where DI is the diameter of the workpiece corresponding to HI;

h is the shell length corresponding to Hi;

Ј0 100 -d degree of deformation

ten

shell, in which the workpiece can be precipitated without shell. From (4) it follows that

Юo SO (eLo / -1), (5)

and since at this stage the shell must be plastically deformed, then, or taking into account (5)

d

100 (e

A0 / 2

-one)

which is the left side of inequality (1).

After deformation, the shell in the form of an open ring (FIG. 4) is unbendled, for example, with a lever with the extension force T (FIG. 5), which reduces the complexity of the process.

The graph (Fig. 6) shows the dependence of the precipitation force P on the degree of deformation Ј during the draft, the dashed lines A and B, respectively, for the precipitation with and without a shell. Naturally, curve A is located higher than the curve of the VIS in terms of lower energy consumption, it is more advantageous to settle the blank without a shell, but this is prevented by low ductility of the metal. Therefore, it was proposed (indicated by arrows) that part of the deformation path should be followed along path A, and, with sufficient plasticity, break the shell and deform the workpiece without the shell with less effort.

Figure 1 shows the workpiece 1 with the shell 2 at the initial moment of deformation; 2 - the same, at the moment of reaching the height of the Nc on Fig. 3 - the moment of sheath rupture; figure 4 - stage deformation with a broken shell; Figure 5 is a shell removal circuit; Fig. 6 is a graph of sediment stress versus strain rate and loading path.

The invention is illustrated by the following examples.

PRI me R 1. At 710 ° C, the billet was made of a low-plastic MnAIC alloy with dimensions of 0 15.5 x 20 mm in an annular shell of 021.4-5.8 mm to a height of 5.8 mm. For the cladding material: StZh steel (, process parameters: e 71%, Lo 0.9, ei 85%, i.e. inequality (1) is fulfilled. In the first stage, the draft was drained to the degree of Lo shear deformation, in the second stage the shell broke and at the end of the process received a predetermined degree of deformation, and revealed a decrease in force at the moment of shell rupture by 100 kN.The shell was removed by bending it for 10 minutes against removing the shell using the grinding method for 90 minutes, labor costs decreased by 89%.

Example 2. Under the same conditions, a blank without a shell was set up. Due to the low ductility, the cracks penetrated to a depth of half the radius.

Example 3. Draft was made in

prototype conditions using the initial parameters of example 1 with the exception of the final height of the workpiece, which was assumed to be 12 mm. In this case, e 40%,

Ј1 29%. Since d 29%, the shell is not broken, it had to be ground for 90 minutes.

EXAMPLE 4 The conditions of the experiment of Example 1 were used with the exception of the shell material, which was L90 brass with D 19%. Since it turned out that d 30%, then condition (1) does not hold, which in practice led to a premature rupture

Claims (1)

shell and the destruction of the metal billet. When using the method, the labor intensity and energy intensity of the process is reduced. DETAILED DESCRIPTION OF THE INVENTION Method for precipitating cylindrical billets of low-plastic materials, including placing the billet in an annular casing covering the middle part of its lateral surface, slumping the billet by applying a compressive force to its ends. with simultaneous stretching of the shell and its subsequent removal, characterized in that, in order to reduce the labor intensity and energy intensity of the process, the draft is initially deposited until a degree of shear deformation is reached that does not exceed its limit value Аb during the draft of the blank without a shell, during subsequent precipitation causes a discontinuity of the shell by breaking it, respecting the condition 100 (eAo / 2 -1) "J 100 one Y1 -Ј / 100 one where d is the relative elongation of the shell material; Ј is the total degree of deformation of the blank; and complete the draft when the height of the workpiece reaches the height of the shell, while the latter is removed from the surface of the workpiece by its bending. Phage. four P i FIG 5 Fa.B