SU1623836A1 - Apparatus for continuous molding of products from powders - Google Patents

Abstract

The invention relates to powder metallurgy, in particular, to devices for continuously forming articles from powders. The goal is to expand the technological capabilities by providing the molding of products from hardly compressed powders and increasing the mechanical properties of the products. In the bunker I, the powder is fed, filling the cavity 8 between the end surfaces of the disks 6

Description

The invention relates to powder metallurgy, in particular, to devices for the continuous molding of articles from powders.

The purpose of the invention is the expansion of technological capabilities by ensuring the molding of products from hard-pressed powders and an increase in the mechanical properties of the products.

Fig. 1 shows an apparatus for continuously forming articles from powders; in Fig.2, section A-A in Fig.1; on f g.Z - section BB in Figure 1; Fig. A shows a section B-B in Fig. 5 shows a diagram of the effect of forces on a powder in a compaction zone in one of the planes.

In Figure 5, the following notation is accepted: Pd and F are the forces of friction of the powder on the end surfaces of the disks; N and N Ј are the shear transverse forces; R. and P are the resultant effects of the forces of friction and shear shear forces; P is the pressing pressure; F., F,,

fill

N (, N, P (, P2 and P) is the same in the narrower part of the cavity formed by the end surfaces of the disks.

The device for continuous molding of products from powders contains a hopper 1, mounted in supports 2 and 3, drive shafts 4 and 5, on which disks 6 and 7 are fixed, respectively. A cavity 9 and a mouthpiece 10 are installed in the cavity 8 formed by the face surfaces of the disks. The disks 6 and 7 are installed at an angle of about 4-6 ° to the axis of the mouthpiece with eccentricity e so that their axis of rotation is spaced from the axis of the mouthpiece neither

The device works as follows.

In the feed hopper 1, powder is continuously fed, filling the cavity

0

five

0

35

40

45

50

55

8 between the face surfaces of the discs 6 and 7. The discs 6 and 7 are rotated in opposite directions with the same speeds. The powder is rubbed and the end surfaces of the discs 6 and 7 are carried into the narrowing part of the cavity 8. As the powder moves in the direction of pressing there is a convergence of particles in the longitudinal and in the transverse directions and the powder mass is compacted. The compaction of the powder occurs due to the action of the friction forces F, and F and the shear forces N and NЈ. These forces are components of the pressing pressure P. The pressing pressure increases as the powder compresses due to the increase in the shear forces N and NЈ. The tangential and normal stresses increase. This leads to an increase in internal friction forces between particles. As a result of the effect of external friction of the powder on the end surfaces of the disks 6 and 7 and the increasing forces of internal friction between the particles, the temperature of the powder increases. As a result of an increase in the temperature of the compacted powder, together with an increasing pressing pressure, intense packing of powder particles occurs with simultaneous removal of oxide films. The dense packing of the powder particles under such conditions ensures a strong metallic contact between the powder particles. In the state of the pre-compacted mass, the powder enters the inlet of the matrix 9, in the cavity of which further compaction and shaping takes place. The final shape and size of the powder takes in the cavity of the mouthpiece 10, from the opening of which comes out in the form of the finished product.

The dependences of the pressing pressure and the temperature of the powder on the angle between the end surfaces of the disks and the direction of pressing were determined by molding square products of 5x5 mm from powders PMSN and iron powders PZMZZ. For this purpose, a set of discs with central holes, the axes of which form with longitudinal axes of symmetry, have an angle of c (/). When changing discs, the angle of inclination of the end surfaces to the direction of pressing is changed. A 400 mm disc. The angular rotational speed of the discs for each experiment remained unchanged at 15.

The measurement results are presented in Table. I

Analysis of experimental data

i)

from the table it shows that with p (. 6 the pressing pressure reaches a higher value when molding from both copper powder and iron powder. When the angle угла changes within the range, the temperature of the copper powder changes to 608 680 ° C, and iron powder in the range of 794 902 ° C. The ratio of the measured temperatures to the melting temperature is 0.55 0.62 C n for copper powder, 0.61 0.69 C for iron powder, d, where t 1300 ° C is the melting point of iron, ta 1100 ° C, the melting point of copper.

Samples of square sections 5x5 mm and 100 mm long were molded from powders, copper, bronze, iron ПЗЗМЗ and stainless steel ПХЗО on the test and on the described device. The production of powders ПЖЗМЗ and ПЖЗО on the known device was not possible. Tilt angle over face

each disk to the matrix axis was 6 °. After molding and following sintering, the thickness gauge, ultimate strength, tensile strength, and hardness of each OO sample were performed.

The measurement results (average according to several experiments for each material) are given in Table. 2

As follows from the, product samples obtained on the proposed device have a higher

5 mechanical characteristics compared with samples obtained on a known device. The tensile strength of copper powder samples increased by 22%, and

0 for samples of bronze powder - by 28.6%, and their hardness is higher by 27 and 40%, respectively.

Pa described device obtained samples of iron powders

5 and stainless steel, which could not be obtained on a known device.

The application of the proposed device allows to expand the technology

In addition, it is possible to increase the capabilities of the company by expanding the range of formable powders and improve the mechanical properties of the molded products.

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Claims (1)

Invention Formula A device for the continuous formation of products from powders, containing a hopper, driven shafts with discs fixed on them, a matrix and a mouthpiece, so that, in order to expand technological capabilities by ensuring the formation of Deals from difficult-to-pressable powders and increase of mechanical properties of nzdelin, disks are installed at an angle to the axis of the matrix. Table I Indicators Material iianinilllillLn Pressing pressure P, MPa Powder temperature t PM01 40 100 170 240 280 300 300 210 210 PZHZMZ 55 130 193 264 305 350 245 222 186 Indicators . The known device of the material PMS-1 95 . j BrO 10-78 94 Angle ten table 2 The proposed device from the material PMO1 BrO-78 PZHZMZ I PCHO 96 95 94 92 240 400 215,420 xvi Figure 4 Fm.5