SU801987A1 - Method of producing sintered shaped articles - Google Patents

Description

one

The invention is attributed to powder /: -g - ::, in particular to: methods for the manufacture of sintered fittings,

A known method of manufacturing sintered fittings, which involves pressing the powder in a mold with eccentric punches, moved at different speeds.

one.

The disadvantage of this method is the complexity of its instrumentation, requiring precise adjustment of the movement of the punches during pressing,

There is also known a method for the manufacture of shaped articles, which involves forming a composite preform from elements of different density, hydrostatic pressing, which and sealing 2,

The disadvantage of this method is that it does not provide uniform density in the manufacture of products with different transitions in height. In addition, the known method is inefficient and does not provide products of exact shape.

In order to ensure uniform density of products with different transitions in height and to simplify the process, a method has been proposed which differs from what is known in that blanks are molded from elements of different heights with a density of elements of greater height exceeding the density of elements of lesser height, and the density ratio elements F, their sizes are determined by the system of equations

H

L-. .

H

H

the density of the finished product; the density of the 1st element of the same height HEIGHT;

Claims (2)

the height of the L-th and j-th element, of the compacted product; height of the 1st and jth elements of the workpiece; MjLjMj is the height of the yy and J then the elements of the workpiece, calculated from the condition of equality of areas; 5, is the area of the i-th element of Sfji. - area L. of the th preparation element, while the ratio of the areas of the elements of the product and the workpiece W is greater than or equal to one. The method of manufacturing products is carried out as follows. The powder is mixed with a plasticizer or lubricant. The blanks work on the elements without transitions in height, then these elements are formed by any of the known molding methods, while ensuring the density of elements having a greater height, greater than the density of elements having a smaller height. The elements are molded either separately or together, but in any case, elements with a higher height are molded with a higher density than elements with a lower height. In order to more accurately calculate the density and dimensions of the billet elements, their density and size were determined using a system of equations. After forming, the blank G5 is sintered to free it from lubrication and increase in strength, and then placed in a die with one or two punches, where the blank is compacted. The drawing schematically shows an example of manufacturing an article of the glass type, where 1 is a matrix in which a seal is produced; 2.3 punches; The blank consists of 4 walls of canal and bottom 5 glasses, PJ is the density of the wall before compaction, p, is the density of the bottom before compaction p is the density of the product, M, is the height of the wall of the piece,. the height of the bottom of the product, H (- height of the wall before compaction height of the bottom before compaction, 5 ,, is the area of the wall of the product, 5iii is the area of the bottom and the local area, w is the wall area of the compaction area of the bottom before compaction, having the experimental data, the ratio S./Sjr i, i; 5.2 / SQj 1, To obtain a product of a given density p 7.8 g / cm (t, e, make the product from an iron-based material) the values of H, H, g are set as H, 50 mm 10 mm. The walls of the glass are made by pressing in a mold with a density of p, 6.5 g / cm, Then according to the system of equations, H2 is determined (-50 60.0 mm. 1.1. HZI 60-1.1 66 mm J II and I., .ll n -1. H Jo-I, r1, hence: HJ, - H ,, 66 - 50 10 Н И22, 26 mm P. - i 3,0 r / CNr, Thus, the shape of the preform and its density are calculated. Then the walls of the preform of the cup are pressed in a mold in the form of a sleeve with a height of 66 mm , wall thickness 5 mm. The bottom is formed as follows: The sleeve is placed on a plane, powder is poured inside with a bulk weight of 2.5 g / cm-,, the total weight equal to the mass of the bottom of a dense preform. The prepared billet of elements of different density is sintered at a temperature of 1200 s for 1 hour in an environment of dissociated ammonia. After sintering, sufficient adhesion of the bottom and the wall is provided. The height of the bottom after sintering is 25–26 mm, the density is about 3 g / cm, which corresponds to the calculations, then the molded billet is subjected to compaction in a matrix with two pans (upper and lower). As a result, the density of the product is obtained after compaction uniform and close to theoretical (7.8 g / cm). The oscillation density does not exceed 0.2 g / cm, which is usually acceptable by the current specifications of powder products. Forming a billet from elements of different densities can be done in various ways, so elements with greater height and density can be molded by pressing in a mold under isostatic conditions, and elements having a lower density can be formed by sintering loose powder and vibrating. slip casting. The workpiece can also be completely pressed into molds to provide different average density of elements, but in any case, the workpiece must be molded from elements of different density, and parts of it having a greater height should have a density greater than parts having a smaller height. The blank can be compacted in a cold or hot form. The proposed technical solution greatly simplifies the tooling and equipment and, in addition, provides for obtaining products of complex shape with different transitions in height, with a high uniform density. Claims The method of manufacturing sintered shaped articles, including the molding of a composite billet of elements of different density, sintering and subsequent compaction, characterized in that / in order to ensure a uniform density of products c. different transitions in height and simplification of the process, the preforms are molded from elements of different heights with a density of elements of greater height exceeding the density of elements of a smaller height, and the ratio of the densities of elements and their dimensions are determined by the system of equations P rn: rg. g / jР (is the density of the t -th element of constant height; is the height of t -To and j -th elements of the compacted {product; height of the 1st and jth 2.J elements of the workpiece; the height of the i-th and j-th elements of the workpiece, calculated from the condition of equality of the areas of the elements of the product and the workpiece; the area of the t-th element of the product; 9i2 - the area of the i - th element of the workpiece with the ratio of elements of the product and the workpiece is greater than or equal to one. Sources of information, e into account in the examination of the second certificate of the USSR 8, cl. In 22 F 3/02, 1972. F Technologists of machine building № 3, ЗБ288П, 1976 Y //////, . W / AU /. I I ///// L five