US2315229A - Apparatus for comminuting dry substances, pastes, and the like - Google Patents

Description

March 30, 1943- e. H. SCHIEFERSTEIN APPARATUS FOR COMMINUTI'NG DRY SUBSTANCES, PASTES, AND THE LIKE Filed Feb. 24, 1939 In renzor Patented Mar. 30, 1943 APPARATUS FOR COMMIINUTING DRY SUBSTANCES, PA-STES, AND THE LIKE Georg Heinrich Schieierstein, Flnowfurt, Eberswalde, Germany; vested in the Alien Property Custodian Application February 24,1939, Serial No. 258,326

3 Claims.

An apparatus has been proposed for grinding dry substances, pastes and the like by means of quartz sand or similar fine-grained grinding bodies with the aid of vibrations produced by unbalanced masses, characterised in that the grinding containers for receiving the material to be ground are arranged with their axes parallel to the shaft producing the vibrations and the containers are advantageously of tubular shape.

Also apparatus has been proposed for the grinding and comminution of such substances with employment of "mono-energetic vibrations in a I closed path (circle or ellipse).

The present invention depends upon the novel recognition that, in contradistinction to comminution by vibrations in a closed path (circle or ellipse) a comminution of dry substances, pastes and the like is more effective, simpler and cheaper to produce by employing apparatus which vibrate in an open path.

The point of view which first led to a comminution in a closed path was probably connected with the firmly rooted conception of grinding which is indeed connected with a comminution in a closed path.

The simplest formpf-the vibration process however is effected, as is known, in an open path, and vibrations in a closed path are derived from a combination of two vibrations which interact at a right-angle with a phase difference of 90.

Germany March 1, 1938 Figures 4, 5 and 6 show embodiments of the present invention as applied to masses supported upon mountings positioned at a low point thereof.

Figures 7 and 8 show forms of the invention in which the mounting is positioned at a high pointof the apparatus.

In Fig. l'a diagrammatic view is shown of the tube mill which consists of a large mass M and a small mass m.

The small mass is constructed in the form of one or two rotating unbalanced masses m and rotates about the central axis at.

During this rotation, there must of course be an equilibrium between the masses M and m and this is given on rapid rotation according to the Newton law by the equation Hereby an ideal common centre of gravity 0 is formed at a distance a from the central axis, about which common centre of gravitythe two masses carry out circular movements.

The circular movement of the small mass is a rotation about this point and the circular move- Since in the field of hard comminution, so far as vibrations are employed, the characteristic of known comminuting methods must be combined with the characteristic of the vibration process in some form, it therefore requires a thorough examination to determine what apparatus and what processes prove the simplest and most effective. I

In this case however it is an incontrovertible fact, that, as already mentioned, the vibrations in an open path are simple, per se, and may be realised more cheaply, and because of the combined grinding and impact effect which results are more effective and more adaptable.

Thus the subject of the present invention is a new hard comminuting process and new apparatus for carrying out the said process.

The principles of operation and illustrative forms of practice of the invention are set out on the accompanying drawing in which Figure 1 is a diagrammatic view showing the coupling forces in one type of vibration l paraitus.

Figures 2 and 3 are conventionalized views of forms of a vibrating apparatus.

ment of the large mass is a vibration in a closed path (a circular vibration).

As a result of this circular vibration, the auxiliary grinding bodies disposed in the interior are set in rotation in a direction opposite to the circular vibration and thus grind the material to be ground. The action is quite minimal, however, since the action force .A which acts upon the bearing :c is equal to the reaction force B, so that there is an amount of work lost which corresponds to this normal force multiplied by the coefl'icient of friction.

For the rest there only remains over for the grinding action an amount of work produced by the circularly vibratory movements of the large mass on travelling along a fraction of the small path 3. Since this travel frequentlyonly amounts to fractions of a millimetre, the yield and hence the efliciency is extraordinarily small. The yield becomes somewhat better when employing an apparatus according to Fig. 2 which is already novel in th sense of the invention. Th improvement is obtained because in this case slower vibrations with a larger amplitude in an open path can be produced by means of a larger crank.

In spite of all this however the efliciency in this case is the smaller, the higher is the frequency of vibration and the larger is the mass M which moves to and fro. The material to be ground is moved to and fro in the trough-shaped bodies, whereby the rollers or balls which are employed of the apparatus according to Fig. 2, if the hollow body M is prevented from carrying out circular vibrations by employment of rigid springs or ri i links 2. I, or is constrained to carry out vibrations in an open path, and the same effect is obtained as in Fig. 2.

Taking them all in all, apparatus in which'only mass elements, cranks and eccentrics are employed for constraining rigid mass elements to carry out vibrations in an open or closed p th.

show the common fault of a relatively or unduly intolerably bad. efficiency because in this type of movement only one kind of energy, in fact kinetic energy, is employed and the vibratory movement is limited to the exact maintenance of a predetermined amplitude. Just because of this limitation, these intolerable losses are caused mainly by hearing friction but also by internal hysteresis work disturbing the material, which losses make such systems incapable of employment per 'se in practice-in the art.

Systems of this kind have been characterised by the applicant as limited-travel systems and still better by Dr. Traude Schieferstein in the Dissertationschrift of May 6, 1936, page 7, as "mono- ,energetic'. systems. a

The highest attainable effect in the sense of "theinvention is obtained when bi-energetic not in this case move with a phase difierence of 180' with respect to the mass M, but in the case which is to be' taken of maximum efflciency (approximately the position-of resonance) takes up a phase difference of about 90. That is the exciting and the vibrating forces have not the and the loss becomes minimal.

vibration mechanisms are employed, thatis apparatus in which the vibrating masses are mount ed between elastic means, so that the kinetic energy, starting from the mean position, is converted by the time the limiting position has been reached into potential energy, and vice versa the potential energy is reconverted again into kinetic energy by the time themean position has been regained.

With this conversion process, the losses in theinterior of the elastic means, so far as it is a matter of rubber bodies, amount only to a maximum of 3-5% as has been established by measurement, since no other losses are present, so that bi-energetic" systems in. contradistinction to mono-energetic" systems work with an efficiency a which amounts to more than 90% according to the frequency, since bearing friction does not arise at all and there is only air resistance to be overcome.

The principle of bi'-energetic types of vibrationaistobeseeninFigs.4,5and6.

In Figs. 4 and 5 mechanisms are shown which carry out bi-energetic vibrations.

In Fig. 4 the mass M vibrates about a rotary axis x upon the lever 71. The lever h terminates in an elliptical rubber mounting, the elastic part 9 of which is secured adhesively on the one hand to the internal pin 2 and on the other hand to the lever h itself which is constructed at its lower end as an elliptical annular body.

Hence the mass M can carry out vibrations as shown in broken lines about the elastic mounting an, and is excited to vibration by a loose couplin which may be constructed as an unbalanced mass in the same way as in Figs. 1 and 3.

It is remarkable that in the case of F18. 4 the loosocoupling, that is to say the mass m, does This effect is still more marked in Fig. 5.

In this case the masswhich is mounted in elliptical rubber springs 2, g, h, is excited by a coupling k which is likewise constructed in the form of an elliptical rubber spring and moves to and fro horizontally,

The only losseswhlch occur in this case are the hysteresis losses in the interior of the rubber I rings amounting to between 3 and 5%, according other hand with auxiliary grinding bodies, balls,

rollers or other hard means capable of grinding, a comminuting machine is produced in this case in which, as already stated, more than 90% of the energy supplied is'converted into useful work.

Naturally the grinding chambers of such systems may be constructed in known manner as simpleor multiple-trough chambers .and they may also be so constructed that the forces and mass displacements produced by the vibrating masses are entirely compensated in known manner (see German speciflcation No. 514,156) The grinding chambers may also be employed in" known manner in open or closed condition and they may be inclined at any desired angle to the horizontal etc.

These apparatus may also be driven in known manner at any desired frequency according to the number and resistance of the resilient assemblies z, a, h employed.

An example of an inclined trough-shaped chamber is shown in Fig. 6, in which M represents the vibrating mass divided into troughs. The troughs I 2, 3 may have sieve-like openings in their front walls similarly to the trough M of Fig. 5, through which the mass when it has been ground suitably line may flow from chamber l to chamber 2, from there-to chamber 3 and trough 2 is shown as being open and the trough 3 as being closed. The angle of inclination may be varied according to the material to be treated.

In Fig. 6 resilient assemblies h, 2, g ar employed which are disposed vertically so that the inclined sieve must also vibrate vertibally- Of course the resilient assemblies may also be inclined as shown in broken line so that the sieve vibrates at an inclination to the horizontal.

In Fig. 7, the mass M is represented as a trough suspended from elliptical rubber mountings 2, g, h, the trough being driven by a loose elastic cou pling consisting of two resilient heads 2, g and the shaft in, and by a suitable motor, through the intermediary of the connecting rod 9.

portions of the arm and pivot for elastically absorbing energy during relative movement of the same. grinding bodies in the grinding chamber in contact with the material therein, and means for applying force to the structure for moving it to and fro, said force applying means including a rockable driving arm having an oblong opening for receiving an oblong pin included in the driving connection and an elastic member positioned in said opening and around said pin and being effective for delivering energy to the structure at a non-linear rate.

3. Apparatus for the comminution of granular and pulverulent dry substances or pastes and the like materials, comprising a. hollow structure providing a grinding chamber, supporting means for said structure including an oblong pin and a wall of oblong=cross-section surrounding said pin and elastic material filling the space between said pin and wall and being secured thereto, a mass located within the grinding chamber and supporting means for the mass comprising a second oblong pin and a second wall of oblong cross-section surrounding said pin and also including elastic material filling the space between said second wall and said second pin and being secured thereto, and mean for applying force to said structure for moving the same to and fro about a fulcrum established by said first pin and first wall.

GEORG HEINRICH SCHIEFERS'I'EIN.

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