SU1217576A1 - Isostatic pressing process - Google Patents

Description

The invention relates to powder metallurgy, in particular, to the methods of an isos-static pressor or products from poropzh, and can be used in the manufacture of long thin-walled bushings.

The purpose of the invention is the quality of products.

The method is as follows. A conventional mold in the mold is pre-molded or a paraffin billet is cast (100% density), the dimensions of which (d and b) satisfy the condition

BLHlMOD 2i., J (,)

5 () n -1) bn)

h -D

6n

(2

gdeDgts is the inner diameter of a long thin-walled sleeve;

) c - outer diameter of long thin-walled bushings |

H height of a long thin-walled sleeve.

FIG. and 2 shows a mold by means of which extrusion is carried out.

The obtained paraffin billet (forming body 1) is placed inside the matrix 2 on the lining 3. In the cavity formed by the matrix 2 and the forming body 1, the charge is poured {the height of the filling of the charge should be equal to the height of the forming body).

Thereafter, a punch 4 is inserted into the matrix 2 and a pressing force is applied simultaneously to both the forming body and the pressing bodies. In this case, the movement of the punch 4 by the required distance along the axis of the mold is provided by the limiter 5, whose height is equal to the difference h-H. As a result, this is a simultaneous pressing of the mixture in both axial and radial directions.

The pressing in the radial direction occurs due to the fact that the paraffin forming body, decreasing in height, increases its diameter. Moreover, this increase is uniform in height.

dry billet as paraffin

It has high ductility and flowability, and is also in direct contact with the compression sleeve.

Moreover, moving in the axial direction together with the pressurized material, it helps to reduce the loss of pressing force arising from friction of the charge on the forming

body.

After pressing, the pressing of the billet is performed together with the forming body from the mold, and then heated to. Wherein

the paraffin melted impregnates the compacted billet and its current is removed. The billets are made of strong, having a uniform density distribution in height with

high dimensional and geometric accuracy.

Example. The pressing is carried out by the proposed method of long thin-walled bushings made of hard-

For the alloy VN20G2 TU 88USSR ISM 818- 84. The dimensions of the sleeve are as follows: outer diameter DH 40 mm; internal diameter T) nf 36 mm; height 50 mm. Molding body (paraffin wax)

molded in a mold. Its initial dimensions, determined on the basis of formulas (l) and (2), are as follows: diameter d 32.4 mm; height h 61.7 mm. The size of the limiter is L – H 61.7–50 11.7 mm. The dimensions of the compressed sleeve in different parts of it are measured by a caliper and have the meanings given by

in tab. one.

The given data characterize high dimensional and geometrical accuracy of the pressed blanks.

To determine the degree of uniformity of the density distribution over

the height of the blanks is carried out the following experiment. Billets Nos. 1-4 are cut horizontally into five parts; The density of each part of the bollard is determined by the hydrostatic method.

  weighing. The results are shown in Table. 2

The data show that the uneven distribution of density over the height of the pressed workpiece

55 ki does not exceed 3%. After sintering, the blanks have a regular geometric shape, there are no cracks, splits.

3

For comparison, the size and density of the sleeves obtained by the prototype method are determined. The results are shown in Table. 3 and 4.

In tab. And shows the density of the sleeves pressed according to the method of the prototype.

f

The unevenness of the density distribution over the height of the compression stock is 22-28%.

40,136.20.

40,036,10

40,136.00

40,036.20

40,036,15

40,136.0

40 "I36.05

40.0 35.95

40,136.00

Upper 5.86

Upper average 5.80

Average 5.78

Lower average 5.76

Bottom 5.76

Upper 5.86

Upper average 5.82

Average 5.80

Lower average 5.78

Bottom 5.75

17576

On the basis of the experimental data presented, it can be concluded that the use of the proposed method, compared with prototype 5, shows the quality of the pressed blanks. This makes it possible to assign allowances for their further mechanical processing in the range of 0.2–0.3 mm, and also to save JQ a deficient hard alloy based on tungsten carbide. . ,

CHAOLSHTs I

Upper part40,136,20

Middle part 40,036,10 Lower part 40,135,95 Upper part 40,

The middle part is 40,136,10 & 1 part 40,136,05

Upper part40,036,05

Average part 40,036,00 lower part 40,136,00

table 2

Upper

Upper

average

Average

Lower average

Bottom

Upper

Upper middle

Average

Lower average

Bottom

average

redn

average

redn

A, 1 4.8

5 .7 3.9

4.1

4.7

5.3 4.6 3.9

Table 3

Upper

Upper middle

Average

Lower average

Bottom

Upper

Upper middle

Average

Lower average

Bottom

Claims (3)

1. METHOD FOR ISOSTATIC PRESSING OF PRODUCTS, mainly long-length thin-walled bushings, including installation in a matrix with a gap along its axis of the forming body, filling the charge into the formed working cavity and applying compressive forces to the forming body in the axial direction, characterized in that, in order to increase As for the quality of the products, the molding body is taken in the form of a paraffin preform, and simultaneously with the application of a pressing force to the molding body in the same direction, a pressing force is applied to the charge. 2. The method of pop. ^ characterized in that the filling of the charge is carried out flush with the forming body, and the dimensions of the latter are selected based on mathematical dependencies 5 (Dh-D _6m ) where d is the diameter of the molding body; h is the height of the molding body; N is the height of the pressed thin-walled sleeve; Dj _H is the inner diameter of the long thin-walled sleeve; Ί) _Η is the outer diameter of the sleeve. SU .... 1217576