RU2529345C1 - Method to produce cylindrical forged piece from compact sintered blanks of metal powders - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: heated initial cylindrical blank is upended in a closed mould. The ready forged piece is removed from the mould by a pusher and is cooled. The blank is deformed accounting for the condition expressed in the stated mathematical expression including the relative percentage reduction of a blank, its relative radial deformation, relative density of the blank and relative density of the forged piece.

EFFECT: production of cylindrical forged pieces with prespecified density ensuring the required set of physical and mechanical properties of the parts manufactured from them.

1 dwg, 1 ex

Description

Technical field

The invention relates to the field of powder metallurgy and can be used to produce cylindrical forgings of a given density from compacted sintered blanks of metal powders.

State of the art

There is a method of hot stamping of forgings, which includes heating the original billet, stamping in a closed stamp with draft at the end, removing the forgings from the stamp and cooling [Forging and stamping: Reference. In 4 volumes - M.: Mechanical Engineering, 1986. - T. 2. Hot Stamping / Ed. E.I. Semenova, 1986. - P.171].

A method for hot stamping cylindrical forgings, including heating the original cylindrical billet, stamping in a closed stamp with a draft at the end face, removing the forgings from the stamp using a pusher and cooling [Okhrimenko Y.M. Forging technology. - Ed. 2nd. - M .: Mechanical Engineering, 1976. - S. 261-262, 279-280].

A disadvantage of the known methods are as follows.

The dimensions of the initial monolithic billet are determined from the condition of constant volume. However, this condition does not apply when using a porous powder billet, as it does not provide forgings with the required density.

This drawback does not allow to determine the deformation conditions of stamping, guaranteeing the receipt of forgings with a given density, which does not provide the necessary structural strength of the parts made from such forgings.

Description of the invention

The technical task of this invention is the production of cylindrical forgings using compacted sintered cylindrical billets from metal powders with a given density.

The technical result of the invention is achieved by preliminary determination of the necessary pairwise values of the height and radial relative deformations of the cylindrical workpiece during stamping in a closed stamp by upsetting at the end face.

The drawing shows a diagram of the production of forgings, where 1 is the original billet, 2 is the stamp, 3 is the forging, 4 is the ejector.

Features

The method differs from the known one in that for the process of plastic deformation of composite sintered powder materials in a closed stamp, the condition of maintaining constant mass is used:

V _i · ρ _i = const,

$$$$

- относительная плотность заготовки или поковки; $${\gamma }_i$$

- плотность заготовки или поковки; $${\gamma }_m$$

- плотность металла, из которого изготовлен порошок.where V _i - the volume of the workpiece or forgings; $${\rho }_i\frac{{\gamma }_i}{{\gamma }_m}$$

$$$$

- the relative density of the workpiece or forgings; $${\gamma }_i$$

- the density of the workpiece or forgings; $${\gamma }_m$$

- the density of the metal of which the powder is made.

The method works as follows.

The heated original cylindrical billet 1 is stamped in a closed die 2 by upsetting in the end face. In this case, the deformation condition of the stamping process is determined by the expression:

, $$\left(\mathrm{one}-\epsilon \right){\left(\mathrm{one}+{\epsilon }_r\right)}^2={\frac{{\rho }_0}{{\rho }_{\mathrm{one}}}}_{}$$

,

- относительное торцевое обжатие заготовки,Where $${\epsilon }_r={\frac{h_0-h_{\mathrm{one}}}{h_0}}_{}$$

- relative end compression of the workpiece,

h _0, h ₁ - the height of the original billet and forgings, respectively;

- относительная радиальная деформация заготовки, $${\epsilon }_r=\frac{d_{\mathrm{one}}-d_0}{d_0}$$

- relative radial deformation of the workpiece,

d ₀ , d _{1 the} diameter of the initial billet and forgings, respectively;

$$$$

- относительная плотность заготовки,ρ _{0 =} $$\frac{{\gamma }_0}{{\gamma }_m}$$

$$$$

- relative density of the workpiece,

γ ₀ is the density of the workpiece;

- относительная плотность поковки,ρ _{1 =} $$\frac{{\gamma }_{\mathrm{one}}}{{\gamma }_m}$$

the relative density of the forgings,

γ ₁ is the density of the forging.

From this condition, the dimensions of the obtained forgings are determined: height h _{1 =} (1-ε) · h ₀ and diameter d ₁ = (1 + ε _r ) · d.

Then, the forging 3 using the ejector 4 is removed from the stamp 2 and cooled.

This production method provides the production of cylindrical forgings with a given density, which guarantees the necessary set of physico-mechanical properties of parts made from them.

The method can be implemented on an industrial unit, for example, a hydraulic press equipped with a heating furnace and a closed stamp with an ejector.

Implementation example.

, полученные компактированием и спеканием из медного порошка ПМС-1, имели массу m=117,5 г и плотность $${\gamma }_0=\frac{m}{v_0}=\mathrm{7,4189}г/с{м}^3$$

. При известной плотности меди γ_m=8,96г/см³ относительная плотность заготовки составила $${\rho }_0=\frac{{\gamma }_0}{{\gamma }_m}=\frac{\mathrm{7,4189}}{\mathrm{8,96}}=\mathrm{0,828}$$

.Initial cylindrical workpieces of height h₀= 13.9 mm, diameter d₀= 38.1 mm and volume $$V_0=\frac{\pi \cdot d_0^2}{\mathrm{four}}\cdot h_0=\mathrm{15839,241}m{m}^3=\mathrm{15,839}\mathrm{from}{m}^3$$

obtained by compaction and sintering of PMS-1 copper powder had a mass m = 117.5 g and a density $${\gamma }_0=\frac{m}{v_0}=7.4189g/\mathrm{from}{m}^3$$

. At a known copper density γ_{m =}8.96g / cm³ the relative density of the workpiece was $${\rho }_0=\frac{{\gamma }_0}{{\gamma }_m}=\frac{7.4189}{8.96}=0.828$$

.

. Тогда деформационному условию удовлетворяет значение относительного обжатия ε=0,260:To obtain a cylindrical forgings with a diameter of d ₁ , = 42.5 mm by stamping in a closed die by draft at the end with a given relative density ρ ₁ = 0.900, the radial relative deformation will be $${\epsilon }_r=\frac{42.5-38.1}{38.1}=0.115$$

. Then the deformation condition is satisfied by the value of the relative compression ε = 0.260:

. $$(\mathrm{one}-0.260){(\mathrm{one}+0.115)}^2=\frac{0.828}{\mathrm{0,900}}=0.92$$

.

Stamping with restriction of the height and diametric dimensions of the forgings in the closed die was carried out on a universal hydraulic testing machine RM-20 at a deformation rate of 3 mm / s. Received ten cylindrical forgings with a height of h ₁ = 10.3 mm and a diameter of d ₁ = 42.5 mm. The average density of forgings was γ ₁ = 7.9744 g / cm ³ and its relative value ρ ₁ = 0.89 (with a difference of 1.1% from the set value).

Due to the deformation condition of stamping in a closed stamp, compacted sintered cylindrical billets of metal powders are used to produce cylindrical forgings with a given density, which ensures that parts with the necessary complex of physico-mechanical properties are obtained from them.

Claims (1)

A method for the production of cylindrical forgings from compacted sintered preforms from metal powders, comprising heating the initial cylindrical preform, stamping it in a closed die by upsetting to the end face, extracting the obtained forging from the die using an ejector and cooling, characterized in that the stamping is carried out in compliance with the following ratio:

,
Where

- relative compression of the workpiece, h _0, h ₁ - the height of the original workpiece and forgings, respectively;

- the relative radial deformation of the workpiece, d ₀ , d ₁ - the diameter of the original workpiece and forgings, respectively;

- the relative density of the workpiece, γ ₀ , γ _m - the density of the workpiece and metal powder, respectively;

is the relative density of the forgings, γ ₁ is the density of the forgings.