SU1219251A1 - Apparatus for isostatic pressing of continuous apparatus for from powder - Google Patents

Description

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The invention relates to powder metallurgy, in particular, devices for the isostatic pressing of long hollow powder articles.

The purpose of the invention is to reduce the energy costs of the pressing process and to increase the quality of products by ensuring uniform density distribution along the length of the product.

FIG. 1 shows a diagram of the device; in fig. 2-4 are the stages of the pressing process.

The device consists of a matrix 1, an elastic insert 2, an integral body rotation in one piece with metal washers 3 and an integral cylindrical through hole, an upper and lower movable metal punches 4, two guide bushings 5, having annular or threaded grooves 6, elastic stand 7. The elastic shell 8 and the forming rod 9 with a mortar are installed in the through cylindrical hole of the liner 2. The cavity between the shell and the rod is filled with powder 10. The forming rod is centered relative to the shell by two elastic washers 11 and pressed by a washer 12 with a nut 13. To ensure stability, the device is mounted on an elastic stand 7.

The elastic liner is made by casting liquid polyurethane into the matrix 1e, which is a mold for casting the liner, and then a mold for carrying out the pressing process. The inner surface of the matrix is made in the form of a body of revolution. Before pouring, it is coated with a lubricant to prevent polyurethane from sticking. Then, the lower punch 4, two metal washers 3, having for the strength of the connection with polyurethane a series of cylindrical threaded holes and a metal rod equal to the outer diameter of the elastic shell and intended to obtain a through cylindrical hole in the elastic insert, are inserted into the matrix. Metal washers are pressed on both sides by guide sleeves 5, which are fixed to the die through 92512

threaded connection. The bottom punch and metal rod are pre-coated with a lubricant, and metal washers are defatted for bonding with polyurethane. During the polymerization process, polyurethane is strongly bonded with washers, since it has a high adhesion to metal. At the expense of the lubricant layer, the outer surface of the elastic liner does not adhere to the inner surface of the die, i.e. the liner after curing retains its mobility in the 15 matrix. Metal rod

after curing, the polyurethane is extracted from the elastic liner.

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The device works in the following way.

An elastic sheath 8 is mounted on the forming rod 9 and it is centered with an elastic washer 11. The cavity between the sheath and the rod is filled with powder 10. An elastic washer 11 is also installed on top and pressed with a washer 12 with a nut 13. Then the elastic sheath with the forming rod and powder is inserted into through the cylindrical hole of the elastic liner 2 and set in the extreme position (figure 2). In the future, compression of the insert by moving punches 4, moving along the axis of the matrix 1 from the power unit, occurs. The elastic liner redistributes the pressure on the elastic shell evenly from all sides within the level A – A due to the geometrical shape and the thickness of the walls. This causes radial compression of the shell and compaction of the powder within the specified limits. Further than this level of significant pressure transfer from the liner to the shell and, therefore, the powder does not condense due to the geometric shape of the liner and pinching its end surfaces with metal washers. At the extreme points of the elastic insert, the pressure tends to zero, which is facilitated by the implementation of the insert in one piece with the metal washers. The annular or threaded grooves in the guide bushes will absorb the axial deformation of the elastic sheath. After removing the external load, the elastic insert

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under the action of elastic forces, it returns to its initial position (Fig. 4). The elastic shell is elastically elongated and takes on its former dimensions and shape. In this case, a gap is formed between the pressed billet and the inner surface of the shell. Then, the billet pressed together with the casing, which is pressed onto the forming core, is moved from the deformation zone by a certain step smaller than level A-A. Thereafter, the pressing process is repeated, i.e. an external load is applied to the elastic liner and the powder located below level A-A is compacted to form the next part of the previously pressed billet. The pressing process is completed after the passage of the entire elastic shell through the cylindrical hole of the elastic insert. Thus, when pressing the blanks in this device, the powder is compacted not in the entire volume of the product at once but sequentially in parts across the shell movement, i.e. across the longitudinal axis of the compact.

Example. The billet is pressed with a length Lj of 600 mm with an inner diameter of 34 mm and an outer diameter of d 40 mm. PMS-1 copper powder (GOST 4960-75) is selected as the starting material for pressing the blanks. The elastic liner and elastic sheath are made of injection-molded polyurethane of the brand Adipren L-167 with the following dimensions: the diameter of the insert hole Dg is 65 mm, the outer diameter of the shell D c 64.5 mm inner - Vbc 45 mm, the length of the shell LO 630 mm. The pressing process was carried out as follows.

zones. A formula rod with a diameter D of 34 mm is inserted into the elastic shell, which corresponds to the internal diameter of the finished product.

and center it with an elastic washer. The cavity between the shell and the rod is filled with powder. From above establish the second elastic washer and press a washer with a nut. Then, the elastic shell with the forming core and the powder is introduced into the through cylindrical hole of the plastic liner and set to the extreme position. Pressing produced

on a hydraulic press. At a pressing pressure of 12 kN, a compact is obtained with a relative density of 0.5. Uneven distribution of density over the length of the compact 0.5-1%.

The table shows data showing the reduction of energy and power costs and the improvement of the quality of products when pressing them on the proposed

device compared to the known.

As follows from the table, the proposed device allows reducing power costs by 60% and increasing

uniform density distribution along the length of the product by 1.3 times.

Thus, the proposed device allows to obtain long products with a uniform density distribution in the transverse direction.

and longitudinal directions and provides reduction of energy and power costs. In addition, it allows you to mold products not only annular cross-section

but also a more complex profile, and can also be used to apply a powder layer to the surface of compact products and to obtain multilayer porous tubes.

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Claims (1)

DEVICE FOR ISOSTATIC PRESSING OF LONG-DIMENSIONAL PRODUCTS FROM POWDER, containing a matrix, upper and lower punches, an elastic shell with a forming rod placed in it, characterized in that, in order to reduce energy and cost costs and improve the quality of products, it is equipped with an elastic liner, guide bushings and washers, and the liner is located between the punches, made in the form of a body of revolution in one piece with the washers and has a through cylindrical hole equal to the outer diameter of the elastic rings, and the guide bushings are made with annular or threaded grooves on the inner surface and are rigidly connected to the matrix.