SU1161243A1 - Apparatus for pressing bulky work - Google Patents

Abstract

DEVICE FOR PRESSING LARGE-SIZED PREPARATIONS, mainly from carbon-graphite powder materials, containing a stand, a mold with a punch, having a slot, and a matrix installed rotatably, and; Vibration node, I distinguish, in that, in order to expand technological capabilities and increase the uniformity of the density distribution, it is equipped with an eccentric drive connected to the punch with a connecting rod, the slots in the punch are filled with radial, different cross sections that cross each other, and the vibration node is made in the form of electro-magnetic vibrators installed in the upper and lower parts of the matrix.

Description

The invention relates to powder metallurgy, in particular, to devices for compacting large-sized blanks, mainly from carbon and carbon powder materials of coke-baking compositions.

The aim of the invention is to expand their technological capabilities by compressing large-sized blanks not only from bulk (metal) powders, but also from more viscous compositions of carbon-graphite materials, and increasing the uniformity of density distribution by eliminating residual stresses inside the particles, reducing their coagulation. and creating the possibility of applying additional vibrations of forces etched away perpendicular to the axis of rotation of the matrix.

FIG. 1 shows the device, a general view; in fig. 2 shows section A-A in FIG. one; in fig. 3 shows a section BB in FIG. one.

Device for pressing foot-sized blanks consists of a frame 1, a mold containing a matrix 2, mounted on a thrust 3 and radial 4 bearings, fixed in the holder 5, and a punch 6 ..

The matrix 2 is a dream. Bzhena electromagnetic vibrators 7, rigidly fixed in its upper and lower parts. Vibrators are connected to a three-phase AC source by means of current-collecting rings (not shown). The matrix is also provided with a pulley 8, which is connected to the electric motor 9 by the belts 10, and the feed hopper 11 :.

The punch 6 is made with radial slits of a small 12 and a large 13 section, which cross over into each other, and with a notched notch 14 in the end part. The punch 6 is connected to the eccentric drive 15 by means of a connecting rod 16. The eccentric drive 15 is mounted on the press slide 17 and consists of a shaft 18 with bearings 19 and a ring 20, an eccentric sleeve 21 with an eccentricity is mounted on the shaft 18. An eccentric 22 is mounted on the sleeve 21. A bronze sleeve 23 is pressed into the ring 20 with free sliding relative to the shaft 18 of the eccentric 22. The eccentric 22 is fixed to the shaft 18 by a sleeve 23 with the cams 24 mounted on the shaft 18 through the sliding key 25 capable of escaping from engagement when adjusting the stroke of the punch 6. The shaft 18 is provided with a pulley 26 and a flywheel 27. The sleeve 5 with bearings is fixed in the plate

28 pages 1 press. A hydraulic cylinder 29 with a key 30 is intended to push out the finished products.

The device works in the following way.

Pre-punch 6 is inserted into the empty matrix 2 and powder is poured into the feed hopper 11. Through the radial Cuts of the small 12 and large 13 sections, the powder from the feed hopper 11 enters the matrix 2 during the entire pressing cycle. From electric motor 9, through wired belts 10 and pulley 8, matrix 2, rotational movement is reported at a constant global speed of 186 rpm, and from eccentric drive 15, punch 6 is transmitted in reciprocating motion with a frequency of 25 Hz and an amplitude of movement of 5 mm.

The compaction of the powder in the matrix 2 is carried out in layers by the reciprocating movement of the punch 6 o The forming surface of the matrix 2, in which the slider 17 leaves the matrix 2 together with the punch 6 at a speed of m / s. At the same time, a three-phase voltage of 380 V is applied to the electromagnetic vibrators 7 through the collector rings and terminals A, 6, C. At the same time, the powder particles are affected by vibration forces directed perpendicularly to the axis of rotation of the matrix, and the powder is evenly distributed throughout the volume,

At the moment of contact of the end part of the punch 6 with the forma- tion of the surface of the matrix 2, the matrix is rotated by 180, while the corrugated notch punch 6 aligns the irregularities and conicities along the entire forming surface. After the extrusion cycle is completed, when the desired height of the product is reached, the punch 6 is retracted to the extreme upper position and 30 from the hydraulic cylinder

29 of the die 2, push the finished billet out. Then the cycle is repeated.

In the proposed device, the use of an eccentric drive allows the reciprocating movement of the punch 7 with a frequency of 25 Hz and a stem of 5 mm to be imparted, the powder pressed in small layers and the billet to obtain the required height. Density of the received preparations reaches 90%. The application of additional vibrational forces directed perpendicularly to the axis of rotation of the dies makes it possible to obtain a billet with uniform density when compacting the powder. The coefficient of unevenness does not exceed 2%. The radial slits of a large cross section at the end of the punch allow the powder to be evenly distributed over the forming surface of the die, i.e. powder, passage through small cross section radial tears, accumulates in large cross sections and when the matrix is rotated by an angle of 180, it rubs with a face grooved notch punch at the time the forming surface of the matrix contacts the face of the punch, excluding the conicity and depression at the surface blanks. The device was tested during the molding of graphite and metal powders. On a prototype device with a matrix volume of 275 cm by pressing a powder by reciprocating a punch against the forming surface of the matrix with layers for pressing cylindrical billets (height 70 mm, diameter 70 mm), experimental samples from a carbon-graphite material of fine-grained coke-making material were obtained, with this effort the punch on the pressed powder remained constant and equal to 100 kg / cm in all experiments. Different volumes of the powder were filled in the loading funnel with a density equal to 1.72 cm. These samples were subjected to sintering for 20 minutes. The results of the tests are given in Table. 1. The unevenness of the density distribution was determined by comparing the densities of cylinders with a volume of 1: 100 taken in different parts of a different cross section of the workpiece. The determination of the density was carried out by the method of displacing the volume of liquid from the vessel determined depending on the density of the substance. As follows from the data obtained, the highest density of blanks with the lowest unequal-density coefficient of 2% was obtained at a frequency. reciprocating motion. punch, equal to 25 Hz, and frequency of additional vibrational oscillation, directed perpendicular to axis of rotation of matrix 50 Hz. In the case of pressing of blanks of metal powder on a prototype device with a matrix volume of 275 cm, pressing samples of metal powder ШК4М2 were obtained by pressing the powder by reciprocating the punch against the forming surface of the matrix with layers for pressing cylindrical blanks (height 70 mm, diameter 70 mm) GOST 9849-74, with the force of the punch on the powder to be pressed, remained constant and equal to 4 kN in all experiments. A constant amount of powder of the same density equal to 2.740 kg / m was filled into the loading funnel in each experiment. The frequency of additional vibration oscillations directed perpendicular to the axis of rotation of the matrix varied in each experiment from 200 to 600 Hz. One-time) The obtained samples were subjected to testing and mechanical strength for bending and breaking. The obtained samples were subjected to sintering for 30 minutes. The results of the tests are given in table. 2. The density of the blanks was determined by the pycnometric method. Bulk density was determined based on the volume and weight of the blank. The unevenness of the density distribution was determined by comparing the densities of 1:50 cylinders taken in different parts. The use of the invention makes it possible to increase the uniformity of the density distribution by 15.8%, the density by 25% and reduce the scrap by 20-25%, upon receipt of blanks from metal powders and by 30-40% upon receipt of blanks from carbon-fiber powders.

The described device, in contrast to the known, allows pressing not only loose (metal) 5 but also more viscous composite carbon-graphite materials.

Table 1

Note; f is the frequency of the reciprocating movement of the punch; the frequency of additional vibration oscillations directed perpendicular to the axis of rotation of the matrix; P is the pressing force; A is the amplitude of the reciprocating motion; t is the time of the pressing process; K is the compaction coefficient; V., - the volume of the pressed blank; Vo is the volume of powder before pressing; K - inequality coefficient.

Note. - pressing force | And - the amplitude of the mechanical.

the unbalance vibrator and the reciprocating motion of the eccentric drive transmitted to the punch for the prototype and the proposed installation, respectively; And the amplitude of the electromagnetic vibrators installed on the matrix for the proposed installation; f is the frequency of the mechanical unbalance vibration and reciprocating motion of the eccentric drive; the frequency of electromagnetic vibrators mounted on the matrix for the proposed installation; Gp is mechanical tensile strength; GUS mechanical flexural strength; K - inequality coefficient by. the volume of the workpiece; P - the porosity of the workpiece; picnometric density of pressed blanks; Jg is the bulk density of the powder before pressing.

, Table2g

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Claims (1)

DEVICE FOR PRESSING LARGE-SIZED Billets, mainly from carbon-graphite powder materials, containing a bed, a mold with a punch having slots, and a matrix mounted for rotation, and; the vibration unit, I distinguish, moreover, in order to expand technological capabilities and increase the uniformity of the density distribution, it is equipped with an eccentric drive connected to the punch by a connecting rod, the slots in the punch are made radial, of different cross sections, turning into each other, and the vibration unit is made in the form of electromagnetic X® vibrators installed in the upper and lower parts of the matrix. £ ω oo With 1 1161243 2