SU1447568A1 - Arrangement for mixing and mincing pulverulent materials - Google Patents

Abstract

The invention relates to powder metallurgy, in particular to installations for the mechanical mixing and grinding of materials. The purpose of the invention is to increase the service life of the attriter by reducing the wear rate of the wear surfaces. The source material, grinding balls and grinding fluid are loaded into the working chamber 3 through the nozzle 7. After the air is pumped out of the working chamber, it is filled with an inert gas. With the aid of actuator 2, the agitator is introduced into the mixer. The grinding of the material occurs under the influence of the abrasive and percussive actions of the grinding balls, the maximum frequency of collisions between themselves and the walls of the working chamber 3 is provided by a rotating mixer, which is a vertical shaft 4 with horizontal beams 5 and an impeller 6. The impeller is a two-blade rotor combining a number of structural elements, namely, the curvature in the direction of rotation of the blades along the radius, 5D, where D is the diameter of the impeller, the presence of wedge-shaped elements at the ends of the blades, the concavity of the upper surface of the blade, the transition of the lower surface of the blade to the face with a radius, and the side wall of the working chamber in the bottom c, where b is the gap between the impeller and the bottom, moreover .. These design differences reduce the moment of resistance of the impeller when it is embedded in the working mass. 1 h. the item of f-ly, 4 ill. but

Description

 to |

CTi

00

The invention relates to powder metallurgy, in particular, to devices for mechanical mixing and grinding of powder materials.

The purpose of the invention is to increase the service life by reducing the intensity of wear of scuff, their surfaces.

FIG. 1 shows an attritor; in fig. 2 - impeller, top view; in fig. 3 is a section A-A in FIG. 2 (impeller blades in the middle part); in fig. 4 is a section BB in FIG. 2 (impeller and its location relative to the side wall and the bottom, and the working chamber).

The attritor consists of a frame 1 (Fig. 1), an electromechanical actuator 2, a working chamber 3, a shaft 4 of a mixer with beaters 5, which are separated from the inner surface of the working chamber for a distance of at least three melyusha diameters and their balls. At the lower end of the mixer there is an impeller (two-bladed rotor) 6, which has, in relation to the bottom, at the side wall of the working chamber gaps of not more than 0.1 mm. The working chamber is equipped with a charging nozzle 7, an air extraction system valve 8 (not shown) and a valve 9 for venting inert gas from the working volume of chamber 3.

The device works as follows.

The starting material for grinding, grinding-up balls and grinding liquid for loading into the working chamber 3 through pipe 7 (Fig. 1). The air is pumped out of the working chamber 3 with a forepump pump when the valve 8 is opened. After the air has been pumped out, the working volume of chamber 3 is filled with an inert gas with an overpressure. Then the valve 9 opens, after which the electromechanical actuator 2 is started, the drive w, at the opposite of the stirrer. The grinding of the material occurs under the influence of the abrasive and percussive actions of the grinding balls, the maximum frequency of collisions between themselves and the walls of the working chamber 3 is provided by a rotating stirrer, which is a vertical shaft 4 with horizontal beams 5 and an impeller 6.

The layer of the working mass, which settles on the bottom of the chamber, rises up and is included in the general circulation with the help of an impeller 6, which is a two-blade rotor, which combines a series of self-bound structural elements. Thus, the curvature in the direction of rotation of the blades along the radius, 5D, where D is the diameter of the impeller, is attached to the blades in order to reduce the resistance when the blades penetrate into the working mass, as the resistance decreases. The wedge-shaped elements (flg. 2 and 3) at the ends of the blades, protruding E. the side of rotation when the impeller is working, knocking out corner balls, break in front of the front edge of the blade of the pack0

balls, pressed by centrifugal force to the side wall of the working chamber 3, reduce the moment of resistance of the impeller when it is inserted into the working mass. The concave surface of the blade (Fig. 4), 4D, deprives the balls moving along the bottom under the action of centrifugal force from the center to the periphery, the emphasis in the side wall of the working chamber. Due to this, the entire flow of the working mass when moving in a direction perpendicular to the blade has an unstable position, as a result, concentrated intensive wear of the working surfaces of the impeller and the side wall of the working chamber in the form of grooves, which

5 is observed when the blades are flat.

The radius (Fig. 4) at the transition of the bottom surface to the end surface of the blade ends is necessary for installation with a minimum clearance from the side

0 by the wall of the working chamber and the bottom, the transition of which to each other is made along a radius equal to b, where b is the impeller gap between the bottom and the side wall of the working chamber, moreover. In this case, the radius of the transition of the bottom to the side wall (Fig. 4) excludes the presence of a two-iK support on the corner slots (about the bottom and the side surface), which is observed in the corner slots when the bottom passes into the side wall at a right angle. Due to the presence of two points of support (on the bottom and side wall), the moving ball must simultaneously rotate around two perpendicular axes of rotation, which is impossible. Therefore, the moving angles are not cut, but dragged by the general packing of the balls under the action of the impeller relative to the bottom and to the side. This is one of the reasons for the most intense wear of the bottom and side wall in the corner, when the bottom passes into the side wall at the right angle. The gap between impel.yurom, d ;; we are looking for and more0

forged wall of the working chamber no more

0.1 mm with a diameter of grinding balls mm provides self-sharpening of the working edges of the impeller on the working mass. This eliminates the need for a 1 b periodic periodic impeller point before operation, which inevitably with gaps greater than 0 mm.

When testing, the mixture with the standard composition of a tungsten-free solid TN-20 alloy was used as the grinding material, containing its titanium carbide TiC 80 vol.% With a 20 vol.% Nickel-molybdenum bond with a Ni-Mo 3 ratio: L The grinding balls are made of VK8 hard alloy with a diameter of 8 mm. Milled liquid alcohol. The rotation speed of the stirrer is 700 and iOOO rpm. After every 100 hours of work, when grinding the carbide mixture, an inspection of the working surfaces of attriters was carried out with wear measured at control points evenly distributed over all working surfaces.

After 1000 hours of operation, the prototype attriter was twice damaged and the bearing assembly of the agitator shaft, and the concentrated wear of the bottom, the working chamber in the impeller zone and the impeller itself reached a value that leads to the appearance of seizures. After 500 hours, the prototype tests were discontinued due to the need for a major overhaul. At the same time, in the NG 4015 Oe attritor for 1000 hours, no visible concentrated wear was found. The impeller, the bottom and the working chamber in the area of the impeller wear evenly with an intensity of 0.15 mm per 100 hours of operation. The sealing surfaces kept clean with a wear of 0.2 mm.

Thus, the average resource of the proposed attriter before overhaul when working on grinding the carbide mixture at 1000 rev / min is 1500 hours, which is 3 times more than the prototype resource.

Claims (2)

1. An attritor for mixing and grinding powdered materials containing 0 a vertical cylindrical working chamber with grinding balls and a stirrer made in the form of a rotating hermetically sealed shaft in the housing with located on it along a helical line at an angle to each other with a two-blade impeller fixed to its lower end, characterized in that services by reducing the wear rate of the rubbing surfaces, the impeller blades are curved in the direction of rotation along the radius, 5D, where D is the impeller diameter, their upper working surfaces are made in bent, radius of transition of the bottom surface of the flap to the end face, where d is the diameter of the grinding ball, radius of the transition of the inner side wall of the cylindrical chamber in the bottom, where b is the gap between the lower surface of the impeller and the bottom, but equal to the gap between the end surface of the impeller and the inner surface of the side wall. 2. The attritor according to claim I, characterized in that the end portions of the impeller blades are wedge-shaped. 0 FIG. 2 Fig.z Figm