RU2364468C1 - Method of complex configuration thin-walled products compression moulding - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to powder metallurgy particularly dealing with production of complex configuration thin-walled products. It is to be utilised for manufacture of products having spherical and/or cylindrical surfaces. The fusion mixture is charged into the cavity of the compression mould formed by the matrix walls, the lower thin plug and the central rod through the throughhole arranged in the upper plug. After that the throughhole is stopped with the pusher plug and the compression mould is upturned. Compression moulding is done with the help of the lower plug and the central rod. Compression moulding completed, the compression mould is upturned once again and the product is released with the help of the pusher plug.

EFFECT: proposed method enables improvement of complex configuration compacts equidensity and facilitation of the release process.

3 dwg, 1 tbl

Description

The invention relates to powder metallurgy and can be used for pressing complex products having spherical and / or cylindrical surfaces.

Known methods for producing products of complex configuration, an example of such an invention is the pressing of parts with a hemispherical contact / Molds for powder metallurgy. Calculation and design. Radomyselsky I.D., Pechentkovsky E.L., Serdyuk G.G. - K .: Technique, 1970, p. 63-64 /. Contact pressing was carried out due to the movable lower punch, which was moved relative to the lower stationary forming punch. The pressure on the powder was created by the upper forming punch, which simultaneously performs the role of the matrix in the final stage of pressing, and the lower stationary punch. In the process of pressing, simultaneously with compaction, a hemispherical cavity was filled with powder in the upper punch.

The disadvantage of this method of pressing is the presence of a spring under the movable punch, which can jam due to the ingress of powder between the lower movable and stationary punches. It is difficult to carry out a volumetric dosage of the powder into the backfill chamber, since the movable punch can rise to different heights. In addition, this method does not provide equal density of the upper and lower parts of the compact due to the lack of a "thin" punch forming the lower part of the compact ("leg").

As the closest analogue, the pressing scheme proposed in the USSR author's certificate No. 1694343, IPC B22F 3/02, 30.11.91 (Antsiferov V.N., Maslennikov N.N., Kornienko A.I., Zyryanov A.V. ., Shatsov A.A. Mold for the manufacture of products of complex shape). The mold contains a matrix, a lower punch and an upper composite punch made in the form of a movable element with a forming conical cavity and a through hole with an ejector located in this hole. The upper punch is made with a buffer, which is compressed during pressing to form a cavity being filled with a charge. The ejector is used to extrude the product. The disadvantage of this scheme is the instability of the buffer, which does not provide an accurate dosage of the powder and does not always work when pressing out. This makes it necessary to apply other methods of filling the mold with a charge and pressing out when pressing thin-walled and critical parts.

The purpose of the invention is to obtain equal-density compacts of complex configuration, easily removable from the mold.

To solve this problem, the pressing and extrusion of the product was carried out with two flips of the mold.

1. Using the installation tool 1 (Fig. 1), a thin lower punch 2 and a central rod 3 were “exposed”, the charge was poured into the mold through the hole in the upper punch 4. The hole was closed with the punch-ejector 5, the mold was turned over together with installation device 1, while the initial position of the central rod 3 did not change with respect to the upper punch 4, the mixture flowed down and filled the backfill chamber formed by the central rod 3, the upper punch 4 with the punch-ejector 5 and the walls of the mat Itza. The installation tool 1 was removed.

2. Applied pressure and molded the mixture (figure 2) with a thin lower punch 2 and the central rod 3, which plays the role of the second additional punch, the movement went to the stop ring 6. The mold was again turned over (figure 3), the product was pressed out 7 by the punch ejector 5.

The use of another filling method in this pressing scheme is impossible, because small differences in the diameters of the central rod and the thin lower punch. If the difference in the diameters of the central rod and the thin lower punch is about 2-3 mm, then with a relatively large movement of the thin punch (about 30-50 mm), obtaining an equal-density product is excluded, because the friction force of the charge on the wall is great and there is a cross-dressing of the charge under a thin punch. In this case, the revolution of the mold allows filling the filling chamber of a predetermined shape, which significantly improves the pressing conditions, minimizes the stroke of the thin punch.

The proposed method, in contrast to the prototype, allows to obtain equal-density thin-walled parts of complex configuration, and therefore, meets the criterion of "significant differences".

Pressing is carried out according to a scheme other than that proposed in the prototype method, with double turning of the mold and pressing from above with a central core and a “thin” punch, that is the invention meets the criterion of "novelty."

Below we offer an example of the invention for pressing the “Facing” part:

- set the mold;

- filled the charge through the hole for the punch-ejector;

- set the punch-ejector and turned the mold, while the mixture moved down with the filling of the backfill chamber;

- a thrust ring was mounted on top and pressed;

- the mold was turned over and the product was pressed out.

By changing the molding pressure, the results presented in the table were obtained.

Table. The influence of molding pressure on the density and density of compacts Chem. the composition of the mixture, wt.% The molding pressure, tf / cm ² Density, g / cm ³ Density, g / cm ³ Cu - 54.4 four 7.0 0.3 W - 35 6 9.6 0.20 Sn - 10 8 10.0 0.15 C - 0.6 Prototype, 8 tf / cm ² 8.8 0.70

As can be seen from the table, the proposed method allows to obtain at the same pressing pressure of higher density and lower density.

Claims (1)

A method of pressing thin-walled products of complex configuration, including filling the charge into the mold, moving the charge into the cavity of the upper punch having an opening in which to install the punch-ejector, pressing and extruding the product from the cavity of the upper punch by the punch-ejector, characterized in that the charge is poured into the cavity formed by the lower thin punch, the walls of the matrix and the central rod placed in it, through the hole for the punch-ejector, after installing the punch-ejector they turn the mold and carry out pressing by moving the lower thin punch and the central rod, and before pressing out, the mold is again turned over.

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