US2117965A - Grinding device - Google Patents

Description

May 17,1938. 5. KI'ESSKALT ET AL GRINDING DEVICE Filed June 18, i954 INVENTORS. W

I @K EZ W JJ 1 ATTORN E pension through a layer of sand which is agi- Patented May 17, 1938 GRINDING DEVICE Siegfried Kiesskalt, Frankfort-on-the-Main- Hochst, and Walther Mejer, Bad Soden, Germany, assignors to I. G. Farbenindustrie Aktiengesellschaft, Frankfort-on-the-Main, Germany Application June 18, 1934, Serial No. 731,172 In Germany July 1, 1933 that it may be caused to vibrate, and means causing the vessel to oscillate perpendicularly to the axis of the vessel. The vessel may rest on elastic bearings or it may be elastically suspended. The swing drive may be eifected in any desired manner, for instance electro-magnetically or mechanically. A device has been found suitable which comprises a shaft with relatively small unbalanced masses connected with the vessel and arranged parallel to the axis of the vessel. The shaft may be caused to rotate rapidly. By the rotation of such'a shaft the vessel and consequently the mixture contained therein and consisting of the material to be subdivided and the grinding elements is caused to oscillate, the curves of the oscillations being in planes perpendicular to the axis of the vessel. The vibration is preferably very rapid and amounts to about 1000 to 4000 oscillations per minute.

Instead of quartz sand of a uniform or different classification there may be used as grinding elements of the same range of size hard balls or polyhedrons from corundum, wastes from precious stones or semiprecious stones or sufliciently hard, if desired other soluble crystals.

In this process in which all unnecessary pressing and shocks and consequently noxious and uneconomical expenditures of energy are avoided, every particle of the material to be subdivided comes sufliciently oftenin consequence of the intimate mixing with the fine-grained grinding elements-between two grinding elements which pass one another; the material is thus extremely finely subdivided within a very short time. It has been found that the various sand or other particles acting as grinding elements pass through the entire mixture in intertwined paths. The vigorously vibrating rotations of every single grinding element are superimposed on these progressive movements. Hence there results a particularly intensive and rapid grinding action caused by the oscillating motion of the grinding particles in continuous curves.

The grinding process may also be carried out in a continuous manner by causing the material to be subdivided to run into a vibrating vessel filled with the sand bed. The outlet of the vessel is closed by suitable means, for instance a grate, a sieve or filter allowing only the finely subdivided material to pass, but retaining the grinding elements. Particularly suspensions may thus be finely subdivided in a continuous manner.

The finely subdivided dry substances may readily be separated in known manner from the grind- 3 Claims.

The present invention relates to a device for subdividing dry substances, suspensions, pastes and the like by means of quartz sand or similar hard, fine-grained grinding elements.

It is known finely to grind or subdivide particles suspended in liquids by pumping the sustated by a stirrer. This process involves the inconveniences that in the zones where the stirring effect is inferior the suspended particles are scarcely moved by the stirrer and that, furthermore, considerable power has to be applied for agitating the sand bed even when the speed of the stirring device is low and only slightly eifective. Moreover, the application of this power frequently causes the sand particles to break so that the material is spoiled by impurities.

We have now found that dry substances of all kinds, suspensions, pastes and the like can be subdivided extremely finely, without a particularly high expenditure of energy being required, by intimately mixing them with quartz sand or similar hard, fine-grained grinding elements, e. g. small porcelain globules, and causing this mixture rapidly to vibrate by mechanical means, so that the single particles of the material to be subdivided and the grinding elements are given an oscillating motion which is free from jerks and describe continuous, closed curves, an agglomeration of the mixture being thus avoided. This is obtained by introducing the mixture into a horizontal, preferably tubular container i. e. i a container whose longest axis extends horizontally and causing this container rapidly to vibrate, without jerks. It is adigsable to give the oscillating impulses such a direction that the various particles of the mixture in the container move in a plane perpendicular to the axis of the container. In order to increase as far as possible the output of the process, it is essential that there are numerous surface particles in contact with each other, in other words, that the grinding elements have not too coarse-grained a. size. A diameter of about 5 millimeters may be the upper limit of an efficacious granular size, if dry substances are to be subdivided; in the case of pastes, elements of a diameter of about 12 to 18 millimeters have been found to be suitable.

The desired oscillating motion of the mixture consisting of the material to be subdivided and the grindingelements may be obtained by means of a device with a known swing drive. Such a. device comprises a horizontal, preferably tubular vessel which is arranged in such a manner ing elements, for instance by the application of a wind sifter.

It may be advisable to augment the mixing motion already effected by the wandering of the grinding elements by causing the vessel itself to rotate.

In the accompanying drawing a pulverizing device according to the invention is diagrammatically illustrated. Fig. l is an automatically revolving vessel and Fig. 2 illustrates a device for continuously carrying out the process. Fig. 3'is a diagrammatic cross-section showing the elastic mounting of the vessel.

In Fig. 1 a is a bottle filled with the mixture consisting of the material to be subdivided and the grinding elements. The bottle is arranged to rotate in the trunnions c on the oscillating plate b. The wandering motion in the vessel started by the oscillation causes the bottle, drum or tube automatically to rotate slowly by the wall friction and the excentric displacement of the weight occurring simultaneously.

Fig. 2 illustrates the continuously carried-out process. The vibrating vessel ,f filled with the grinding elements 1' is subdivided into several chambers by means of cross walls. Each two chambers are connected with one another by the tubes h. The material to be subdivided is introduced into the vessel at 9, passes through the various chambers and leaves the vessel at l in a finely ground form. .When leaving one chamber and entering into the next the material may pass through sieves, grates formed by rods, or the like is by which the grinding elements are retained and only the material to be subdivided is allowed to pass. m is the shaft producing the oscillations. The shaft is placed parallel to the axis of each of the chambers. The out-of-balance body 11- is mounted on the shaft. Instead of one vessel subdivided by cross walls, there may, of course also be used single chambers lying parallel one beside the other. Each two of these chambers are connected with each other at the front side by means of tubes. The chamber situated at one outer side is provided with an inlet for the material to be subdivided and the chamber situated at the other outer side is provided with an outlet for the subdivided material.

Fig. 3 is a diagrammatic cross section through a simple construction of the entire device. 0 is a table which is suspended in an elastic manner by means of bent leaf springs. At the bottom part of this table a rapidly rotating shaft q with the out-of balance mass r is mounted which causes the entire system including the horizontal cylindric container sdestined for the receipt of the material to be ground and the grinding bodies to oscillate in a circular or nearly circular manner. In the oscillations the plane of the path curves is perpendicular to the rotating shaft and consequently to the horizontal axis of the container .9.

We claim:

1. A device for grinding dry substances, suspensions, pastes and the like mixed with hard, fine-grained grinding elements comprising a horizontal vessel, means for elastically mounting the vessel permitting movement thereof in every dimotion in a plane perpendicular to the axis of the vessel, and means for causing the vessel rapidly to vibrate in a closed curved path of small amplitude in said plane.

2. A device for grinding as defined in claim 1 in which the means for causing the vessel rapidly to vibrate comprises a shaft connected with the vessel and arranged parallel to the axis thereof, an unbalanced mass secured to the shaft and means for rotating the shaft.

3. A device for grinding as defined in claim 1 in which the vessel is divided into a plurality of parallel elongated horizontally disposed chambers connected in series for the passage of material, means for introducing material to be subdivided into an end chamber of the series and means for discharging subdivided material from the other end chamber of the series.

SIEGFRIED KIESSKALT. WALTHER MEJER.

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