RU2308346C2 - Cast-iron ball-type grinding bodies shaping method - Google Patents

Abstract

FIELD: metallurgical industry branches, possibly manufacture of ball type grinding bodies of cast iron.

SUBSTANCE: method comprises steps of producing cast semi-finished product in the form of cylinder with hemispherical ends by forming crystallized metal in multi-seat die set of double -action press; keeping temperature of cast semi-finished product during forming process no less than 950°C; after separating remainder of billet, squeezing produced semi-finished product in additional squeezing die set while providing non-uniform all-side compression. Diameter of cylinder of cast semi-finished product and its height are determined according to given mathematical expressions. Remainder of billet is removed at forming protrusion for centering semi-finished product in squeezing die set.

EFFECT: enhanced efficiency of method.

4 cl, 7 dwg

Description

The invention relates to the metallurgical industry and allows at the modern technological level to produce ball grinding media from cast iron.

A known method for the production of cast iron grinding bodies (RU 2082530 C1, 06.27.1997, B21H 1/14), which consists in the fact that cast iron is melted with its alloying, bars of the desired diameter are cast from it, balls are rolled from the bars and subjected to quenching and tempering . Smelted cast iron is modified with a magnesium-containing modifying mixture containing graphite. Before rolling, the rods are heated to 950-1080 ° C; the balls are obtained by rolling on a cross-helical rolling mill. The resulting balls are subjected to isothermal hardening and subsequent tempering at 280-320 ° C. However, the strength and durability of the balls is insufficient and high energy costs.

The problem to which the claimed invention is directed, is to increase the strength and wear resistance of the obtained products and reduce energy consumption.

To solve the problem in a known method of forming spherical grinding media from cast iron, including obtaining a cast semi-finished product and applying pressure to it, in accordance with the invention, a cast semi-finished product is obtained in the form of a cylinder with hemispheres at the ends by stamping crystallizing metal in a multi-cavity stamp on a double-action press, pressostat is separated, after which the obtained cast semifinished product is crimped in an additional die for crimping by means of comprehensive non-uniform compression, at this in the process of stamping maintain the temperature of the cast semi-finished product at least 950 °.

Use a multi-slot stamp with at least two slots.

A molded semi-finished product is formed, the diameter of the cylinder B and the height A of which is determined from the following expressions:

B = 2r, r = (0.9-0.95) R, A = (1.05-1.1) D, D = 2R,

where: R is the radius of the ball;

D is the diameter of the ball.

The separation of the pressostatic is carried out with the formation of a residual protrusion for centering the semi-finished product in the stamp for crimping, while the height of the specified protrusion is not more than 0.1R.

The advantage of this method is the absence of intermediate heating of the metal necessary for the final shaping operation, instead of which the residual heat of the non-cooled metal is used (up to 950 ° C), due to which plastic deformation occurs immediately after separation of the semi-finished products by a shift from the hot forgings. Therefore, the proposed method does not require additional heating. The metal balls made in accordance with this method has a finer structure than that observed for cast balls made in accordance with TU 1173-02984032-402-94, according to which local shrinkage shells with a diameter and depth of up to 12% conditional are allowed the diameter of the ball. According to the same specifications, a protrusion or depression of not more than 6 mm is allowed on the surface of the ball.

Balls obtained by the proposed method, no shrink shells, which increases their density, strength and durability.

The invention is illustrated by graphic materials, where

figure 1 shows a cross section of the semi-finished product;

figure 2 shows a diagram of a multi-cavity die for crystallization under pressure, section;

figure 3 is the same, a top view;

figure 4 and 5 show the separation of the pressure switch;

Figures 6 and 7 show the crimp of the cast semi-finished product in an additional stamp.

The positions in figure 2-7 are indicated: 1 - the punch of a multi-socket stamp; 2 - movable half-matrix; 3 - fixed semi-matrix; 4 - ejector: 5 - semi-finished product: 6 - pressostat, arrows P, P1, P2 show the direction of pressure application, 7 - punch for separating the pressostat, 8 - clip; 9 - knife bush; 10 - counter-pusher-ejector, arrows T show the direction of movement of semi-finished products 5, 11 - die punch for crimping, 12 - die die for crimping, 13 - packet of Belleville springs; 14 - support, 15 - counter-punch-ejector stamp for crimping, t - thickness of the residual protrusion, s - gap, d - distributed compression forces, K - the direction of movement of the punch 11.

The method of forming ball grinding media from cast iron is as follows.

A semi-finished product is obtained in the form of a cylinder with hemispheres at the ends (Fig. 1) by stamping crystallizing metal in a multi-cavity stamp (up to 8 or more pieces in one complete forging) (Figs. 2, 3) on a double-action press. The diameter of the cylinder B and the height A of the semi-finished product is determined from the expressions: B = 2r, where r = (0.9-0.95) R, A = (1.05-1.1) D, where D = 2R. The resulting pressostat is separated (FIGS. 4, 5). After separation of the pressure switch is crimped in an additional stamp for crimping (6, 7) according to the scheme of comprehensive non-uniform compression. The temperature of the semi-finished product during stamping is maintained at least 950 ° C.

Claims (4)

1. A method of forming spherical grinding media from cast iron, including the production of a cast semi-finished product and applying pressure to it, characterized in that the cast semi-finished product is obtained in the form of a cylinder with hemispheres at the ends by stamping a crystallizing metal in a multi-cavity stamp on a double-action press, the pressostat is separated, after which the obtained cast semi-finished product is crimped in an additional die for crimping by means of comprehensive non-uniform compression, while the temperature of the lit is kept during stamping prefabricated at least 950 °. 2. The method according to claim 1, characterized in that use a multi-slot stamp with at least two sockets. 3. The method according to claim 1 or 2, characterized in that they form a cast semi-finished product, the diameter of the cylinder B and the height A of which is determined from the following expressions: B = 2r, r = (0.9-0.95) R, A = (1.05-1.1) D, D = 2R, where R is the radius of the ball; D is the diameter of the ball. 3. The method according to claim 1 or 2, characterized in that the separation of the pressure switch is carried out with the formation of a residual protrusion for centering the semi-finished product in the die for crimping, while the height of the specified protrusion is not more than 0.1R.

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