Method of cold forming blanks from powder materials and device for its implementation

 

(57) Abstract:

Method of cold forming includes unilateral application of axial force, multilateral efforts lateral compressive and shear normal to the axial and unilateral application of axial force, opposite to the initial one. Device for cold forming blanks contains a matrix, made for example of four stacked forming elements, which are installed in the same plane and mounted in the holder. The yoke has a conical surface associated with the corresponding conical surfaces on the forming elements of the matrix. In the Central holes of the clamping plates are upper and lower punches. The holder is provided with a drive reciprocating movement along the axis of the matrix. Each forming the matrix element is spring-loaded relative to the clip elastic element. The positive effect of achieving high-density workpieces up to 90% of theoretical, elimination of raznorodnosti blanks mainly from trudnoponimaemyh fragile powder materials. 2 S. p. f-crystals, 2 Il.

The invention relates to powder technology, namely the pressing of products and the in of the hard powder materials, such as ceramics, cermet and ceramics.

There is a method of cold forming of workpieces from a powder material in a closed mold, including unilateral efforts [1]

The disadvantage of this method is single and unilateral application of effort that leads to uneven compaction of the powder in height and the diameter of the workpiece and does not provide a sufficient density. The highest densities are areas adjacent to the end plug and the wall of the matrix.

Known apparatus for forming blanks from a powder material including the matrix, the punch and the bottom plate.

The disadvantage of this device is also single and unilateral application of effort, which gives an uneven seal blanks height and cross-section and does not provide them with sufficient density.

Closest to the present invention is a method including the application of bilateral axial compression of the powder in a cold state.

In this way the density of the layers of the powder adjacent to the upper and lower punches, becomes the same, but still different height and cross-section and is insufficient in the whole volume of the workpieces. The appreciation is wow, bilateral application of force in one direction is more intense seal blanks at the ends of the punches. The middle portion of the workpiece at a height of less dense section baseplate. After application of bilateral axial forces there is some optimization packaging original fractional composition of the powder due to abrasion and crushing of particles of brittle ceramic materials. This is especially true of pieces of oxide, carbide and nitride ceramics.

The main disadvantage of this method is the low frequency and the side of the effort, not providing an adequate optimization of the packing fraction composition powders, and as a result, the uneven density of the produced workpieces height and cross-section and insufficient density by volume.

Closest to the present invention is a device for pressing items from a powder, comprising a matrix made in the form of six forming elements coupled between a and provided with a drive of their radial movement, an upper annular punch, punch, kick. Punches mounted in the Central hole of the clamping plates.

In this device, pressing the/P> The disadvantages of this device are also uneven density workpiece height and cross-section and insufficient density by volume.

The purpose of the invention, the increase in density and increase in uniformity in height, cross-section when receiving the blanks from powders of hard materials, mainly metal, cermet and ceramics.

The aim is achieved in that in the method of cold forming blanks from powder materials, including bilateral application of the axial forces in the beginning put unilateral axial force is then applied to the workpiece multilateral compressive and shear lateral efforts in the direction of the normal axis, and, finally, apply the opposite of the initial axial force.

What to powder and powder to the cake mix make multiple axial, lateral normal and shear forces with multiple changes of directions of their application leads to optimising packaging original fractional composition of the powder material, the optimal change in the fractional composition of the powder material through the crushing of brittle particles and abrasion of plastic particles. All this allows Popo section billets. This particularly applies to ceramics, cermet and cermet.

The purpose of the proposed device is achieved in that the device for cold forming blanks from powder materials containing matrix, made in the form of stacked forming elements mounted in the same plane and provided with a drive of their radial movement, a clamping plate with a Central hole, in which there are upper and lower punches, forming elements are mounted in a housing made with wedge surfaces associated with the respective wedge surfaces on the forming elements of the matrix, the yoke is equipped with a drive reciprocating movement along the longitudinal axis of a matrix, with each forming element is spring-loaded relative to the adjacent element and the shell.

This enables the unit to carry out the sequential application to the powder initially unilateral axial forces, then multilateral efforts, normal to the axial force, and, finally, unilateral axial force of the opposite direction of the initial axial force, i.e., as in the proposed method to implement the fractional nature of develica uniformity of the density and height of the section.

The method is as follows.

The powder is fed into the matrix. Then, for example, the upper punch compresses the powder in the axial direction. Then to the powder put side multilateral compressive and shear forces in directions normal to the axial force. Then begin to apply, for example, the lower punch of the axial force, opposite to the initial force of the upper punch.

In Fig. 1 shows the proposed device; Fig.2 section a-a in Fig.1.

The device comprises a matrix 1, made for example of four stacked forming elements, which are installed in the same plane and mounted in the holder 2. The yoke 2 has a conical surface 3 associated with the respective conical surfaces 4, made on the forming elements of the matrix 1. Matrix 1 is installed between the clamping plates 5, 6, interconnected columns 7 and screw 8. In the Central holes of the clamping plates 5, 6 are the upper punch 9 and the lower punch 10. The yoke 2 is provided with actuator 11 reciprocating movement along the axis of the matrix 1. Each forming the matrix element 1 is spring-loaded relative to the elastic holder 2 e the/P> Powder 13 is poured into the working cavity formed work surfaces forming elements of the matrix 1 and the working surface of the lower punch 10. Include the press drive (not shown). The upper punch moving down, compact powder 13. After that, include the drive 11 of the reciprocating movement of the holder 2, which is moving up, their conical surfaces 3 acts on the conical surface 4 forming elements of the matrix 1 by sliding them in the radial direction. Is multilateral normal compression and shear powder in the direction perpendicular to the axial efforts. Then, the punch 10 is moved in the axial direction up. Then return to the top position of the punch 9 and the actuator 11 in the initial position of the holder 2. Forming elements are returned to the initial position under the action of springs (item 12). The distance between the clamping plates 5 and 6 is adjusted by the screw 8 and the columns 7. After removal of the workpiece to its original position returns the punch 10.

The proposed method were made square articles of ceramic powder hard magnetic material ferrite composition BaO.6Fe2O3. Axial force IRS method was made device according to the present invention. The conical surface of the shroud and forming elements of the matrix angled 15about.

Studies have shown that the density of the obtained square billets HH mm was 90% of theoretical with a uniform distribution along the height and cross-section.

The proposed method and device are useful for fragile ceramic powder materials: ferrites, oxide (Al2O3, ZrO2and others), carbides (SiC, TiC, etc.), nitride (Si3N4and others) ceramics, carbide powders (type VC and TC), the cermet powders based on titanium carbide and other high-temperature compounds.

1. Method of cold forming blanks from powder materials, including bilateral application of the axial forces, characterized in that the first powder make unilateral axial force is then applied to the workpiece multilateral lateral compressive and shear forces in directions normal to the axis, then apply the opposite of the initial axial force.

2. Device for cold forming blanks from powder materials containing matrix, made in the form of stacked forming elements, lname holes, equipped with upper and lower punches, characterized in that the forming elements are mounted in a housing made with wedge surfaces associated with the respective wedge surfaces on the forming elements of the matrix, and the holder is provided with a drive reciprocating movement along the longitudinal axis of a matrix, with each forming element is spring-loaded relative to the holder.

 

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