GB2053025A

GB2053025A - An agitator element for a grinding or dispersing mill

Info

Publication number: GB2053025A
Application number: GB8004628A
Authority: GB
Original assignee: Oliver and Batlle SA
Current assignee: Oliver and Batlle SA
Priority date: 1979-05-03
Filing date: 1980-02-12
Publication date: 1981-02-04
Also published as: ES243038U; GB2053025B; ES243038Y; JPS63164944U; JPS55145544A

Abstract

An agitator element for a grinding or dispersing mill has a shaft carrying discs. There are discs 2 of a first kind interdigitated with discs 3 of a second kind. The former have holes therein, and the holes have a periphally outer boundary wall 4 Fig. 1A inclined at an acute angle to the axis of the shaft 1 as seen in a plane containing the shaft axis. The discs of the second kind are plain circular discs unapertured except for a central hole for the shaft. <IMAGE>

Description

SPECIFICATION An agitator element for a grinding or dispersing mill The invention relates to an agitator element for a grinding or dispersing mill.

Various designs of agitator element for a grinding or dispersing mill have been proposed in the prior art, and it would be desirable if the design of agitator element was available in which, in use, advantageous flows of material are produced in order to improve the dispersion of solid products into liquids.

In accordance with the present invention, there is provided an agitator element for a grinding or dispersing mill which includes a shaft carrying a plurality of discs of a first kind interdigitated with discs of a second kind, the former being discs having a plurality of holes therein, at least some of the holes having a periphally outer boundary wall at a predetermined radius, the wall being inclined at an acute angle to the axis of the shaft as seen in a plane containing the shaft axis, and the discs of the second kind being plain circular discs unapertured except for a central hole for the shaft and having a radius not less than the predetermined radius.

Such an agitator element may be used in a dispersing mill with its axis either horizontal or vertical. In use of such an element, counter flows of material are produced which assist in improving the dispersion of solid products into liquids.

In accordance with an advantageous embodiment of the invention, the radius of the discs of the second kind may substantially equal the predetermined radius.

In accordance with a preferred embodiment of the invention, successive discs of the first kind have the angled outer walls of their holes inclined in opposite axial directions.

Other preferred features of the invention are defined in the subsidiary claims herein.

The invention will be better understood from the following description of illustrative embodiments thereof, given with reference to the accompanying drawings in which: Figurg 1A is a front view of a disc of a first kind for use in an agitator according to the invention; Figure 1B is a front view of a plain circular disc of the second kind; Figure 1C is a front view of a second type of disc of the first kind in which the hole placing differs from that in the disc shown in Fig. 1A; and Figure 2 is an axial vertical section of part of an agitator element in accordance with the invention, indicating the circulatory path of ground material.

The illustrated agitator element has a shaft 1 upon which are fitted a plurality of discs.

Discs 2 are discs of the first kind and these are interdigitated with discs 3 of the second kind. One of the discs 3 of the second kind is seen at the middle of Fig. 2 and it is a plain circular disc unapertured except for a central hole 7 for the shaft. It will be seen that this hole has opposed flats.

The discs of the first kind are shown at the left hand and right hand sides of Fig. 1. Each has a plurality of kidney shaped holes defined by walls fortherein, and these holes possess tilted or angled outer boundary walls 4, 5 the angling of the walls 4 being seen in Fig. 2.

Each inclined wall 4 may be located at an angle between 27 and 36 degrees to the shaft axis. In other words, the walls 4 may be angled at an angle of between 63 and 54 degrees to the plane of the disc, and the curved walls 5 of the holes may be similarly angled to the plane of the disc. As seen, the radially outer and inner walls of the holes in the first kind of disc are each defined by the locus of the arc of a circle centered on the shaft axis whose diameter increases as it is moved in the direction of the shaft axis.

Alternate discs 2 have their inclined walls facing in opposite axial directions and interposed between these discs 2 are the plain circular discs 3. There may be three holes in each disc of the first kind but obviously the invention is not regarded as limited to 3-hole discs. As seen in Figs. 1A and 1C, the outer periphery of each disc 2 of the first kind is cylindrical except for two flats at opposite ends of a diameter. The discs may be equally spaced along the length of the shaft and suitable sleeves may be provided to achieve this.

The agitator element shaft may have a disc of the first kind at each end of the series of discs thereon.

The radially outer wall of each hole may be located at a radial distance from the axis which is from 70% to 80% of the radius of the disc of the first kind. Each hole may be substantially of kidney shape. Its end walls 5 may be angled similarly to the walls 4.

As shown, the radius of each of the discs 3 of the second kind is substantially equal to the distance of the walls 4 from the shaft axis.

The inner wall of each hole in the discs 2 is preferably at from 1 5 to 40% of the disc radius. Each flat on a disc 2 of the second kind is preferably located at a distance from the axis of the shaft which is from 90 to 96% of the disc radius.

As is seen from the diagrammatic representation of material fiow in Fig. 2, the interposition of the plain circular discs 3, between the apertured discs 2 prevents or minimizes the passing of non-ground particles axially of the milling chamber, and, instead a circulatory motion is imparted to these particles within the spaces defined between adjacent discs.

This arrangement has been found to be favourable to a good dispersion of solids into liquids. Promotion of a circulatory motion is assisted by the alternate directions of angling of the outer walls 4.

The invention as particularly disclosed herein is intended for dispersing pigments of considerable hardness into suitable solvents, particularly in the preparation of paints. Instead of 3 holes in each disc of the first kind, there may be any different number of holes, for example four holes centred upon two diameters at right angles to each other.

Claims

1. An agitator element for a grinding or dispersing mill which includes a shaft carrying a plurality of discs of a first kind interdigitated with discs of a second kind, the former being discs having a plurality of holes therein, at least some of the holes having a periphally outer boundary wall at a predetermined radius, the wall being inclined at an acute angle to the axis of the shaft as seen in a plane containing the shaft axis, and the discs of the second kind being plain circular discs unapertured except for a central hole for the shaft and having a radius not less than the predetermined radius.

2. An element according to claim 1 in which the radius of the discs of the second kind substantially equals the predetermined radius.

3. An element according to claim 1 or 2 in which the radially outer and inner walls of the holes in the first kind of disc are defined by the locus of the arc of a circle centred on the shaft axis whose diameter increases as it is moved in the direction of the shaft axis.

4. An element according to claim 3 in which each disc of the first kind has a central shaft hole and three holes equally angularly spaced around the shaft axis.

5. An element according to any preceding claim in which the outer periphery of each disc of the first kind is cylindrical except for two flats at opposite ends of a diameter.

6. An element according to any preceding claim in which the shaft has a disc of the first kind at each end of the series of discs thereon.

7. An element according to any preceding claim in which the discs are equally axially spaced from one another.

8. An element according to claim 3 in which the inner wall of each hole is located at a radial distance from the axis which is from 40 to 50% of the disc radius.

9. An element according to claim 8 in which the outer wall of each hole is located at a radial distance from the axis which is from 70 to 80% of the disc radius.

10. An element according to claim 5 in which each flat is located at a distance from the axis of the shaft which is from 90 to 96% of the disc radius.

11. An element according to any preceding claim in which the inclined wall of each disc of the first kind is inclined at an angle between 27 and 36 to the shaft axis.

1 2. An element according to any preceding claim in which successive discs of the first kind have the angled outer walls of their holes inclined in opposite axial directions.

1 3. An agitator element substantially as herein described with reference to and as illustrated in the accompanying drawings.