US2170768A - Grinding and the like apparatus - Google Patents

Description

Aug. 22, 1939. s. H. SCHIEFERSTEIN GRINDING AND THE LIKE APPARATUS Filed Oct. 19, 1956 77: van for:

Patented Aug. 1939 GRINDING AND THE LIKE APPARATUS Georg Heinrich Schieferstein, Berlin- Charlottenburg, Germany Application October 19, 1936, Serial No. 106,464

. In Germany June 16, 1936 This invention relates-to grinding and the like apparatus for comminuting materials.

It is well known that material to be ground is mixed with balls, rollers or other rigid bodies 5 and the whole is placed in a hollow chamber and is then set in a rotating, swinging or rocking motion. This involves in all cases a device which is positively driven at a certain speed or with a limited stroke mechanism with a relatively poor efliciency.

It is further old to agitate such a mixture in mixture chambers which lie parallel to the axis of the swinging motion, which are positively driven by rotating masses, in such manner that a l rubbing motion is created betweenthe material to be ground and the grinding bodies. This grinding process gives poor mechanical efliciency, because the rotating motion is produced by forced high bearing pressure and a grinding operation results which is suflicient for grinding fine materials only, while comparatively little force is transmitted to the material to be ground. Consequently, it is impossible in using these methods to increase the size of the chambers 5 profitably, neither is it possible to increase the force or grinding output to any great extent.

Besides, in this method the mixture of the material to be ground and the grinding bodies are not evenly distributed over the entire chamber, since through the force of gravity the material to be ground forces its way downward through the circular rotations and thus accumulates in increasing quantities in the bottom of the chamber. According to the present invention the above disadvantages are eliminated by coupling a second body to the swinging body of the grinding chamber, which second body serves as counterweight and has the same heavy axis. This device operates by interposing elastic means between the bodies and swingingly motivating the inner chamber by means of a loose coupling. In this manner any necessary contact pressure between the material to be ground and the grinding bodies is obtained, which with 186 rotating motion against each other around the common axis in this two chamber system,guarantees a vibrationfree working, and a better-mixture of the material to be ground with the grinding bodies results aided by the elastic means on which the grinding chamber rolls. I

In order more clearly to understand the invention, reference is made to the accompanying drawings, which illustrate diagrammatically and 55 by way of example, various embodiments of grinding apparatus in accordance therewith, and in which:

Fig. 1 is an axial section of part of one embodiment;

Fig. 2 is on the line 2-4 of Fig. 1 and with parts of the outer cylinder a broken away and with but one of the supports j shown;

Fig. 3 is a detail; showing a modified resilient support between the outer and inner cylinders;

Fig. 4is an axial section through a second embodiment;

Fig. 4a is a vertical section taken on the line la-la of Fig. 4 with the receptacle I) removed;

Fig. 5 is an axial section through a third embodiment;

Fig. 6 is a fragmentary vertical longitudinal section showing a modified form of drive;

Fig. 7 is a fragmentaryvertical longitudinal section showing a modified form of drive;

Fig. 8 is a fragmentary vertical longitudinal section showing a modified form of drive;

' Fig. 8a' is an elevation partly in section of a detail of Fig. 8;

Fig. 9 is a fragmentary vertical longitudinal section showing a modified form of drive; and

Fig. 10 is a detail showing an adjustable resilient support between the outerand inner cylinders.1

In said drawing, like parts are denoted by like reference characters.

Referring to Fig. 1, a hollow receptacle b is disposed within a cylinder a closed at both ends.

, The cylindrical hollow receptacle 1) having closed ends is pierced axially by a tube e, so that the re-' sulting hollow space in the cylinder 1) is of annular cross-section. A shaft y rotates two eccentries :01, only one of which is shown and which are mounted on said shaft 1 adjacent the ends of the hollow receptacle b. The shaft .11 passes through the tube e. The eccentrics x1 are mounted in annular bearings as which are connected to the outer jacket ofthe hollow receptacle b by any desired number of radially mounted resilient members I. If the shaft y be rotated, circular oscillations are imparted to the hollow body b, through the eccentrics x1, bearings x2 and resilie'nt members .1. Such oscillations are transmitted through a plurality of interposed andsubstantially hemispherical elastic members 0 to the outer hollow cylinder a. In Fig. 3, instead of a plurality of members 0 an elastic cylinder The elastic cylinder d functions in the same manner as do the members 0. Y

In each embodiment illustrated, the outer hold is positioned between the cylinders a and b.

low cylinder a is fastened to resilient suspension members h in such a way that it is able to perform small oscillations but is unable to turn freely around the axis 3 On the other hand, the

inner hollow receptacle b, when the eccentrics .m are rotated in the clockwise direction in bearings 3:2, rotates slowly in the anti-clockwise direction. This is caused by the fact that the resilient members c are slightly compressed radially by the eccentric agitation, so that the hollow receptacle b being ofsmaller radius must roll over the supporting resilient members, between which there is a space of greater radius. This action is in the nature of. that of a pinion gear rotated on the end of a crank arm and in engagement with the inner teeth of a ring gear.

speed of rotation of the inner drum b in that.

direction and also setting up in harmonic vibrations which are transmitted to drum'b' and which are helpful in the grinding. The result of thisacion is to produce a certain loss of travel for every revolution of the eccentrics, i. e., a revolution in the opposite direction to that of the rotation of the eccentrics.

If such a tube mill be charged in known manner through closable openings, not shown, with -material to be ground 11. and grinding bodies 0,

which latter may consist of cylindrical metal rollers, metal balls or other suitable material (quartz sand or the like), and if the whole system be agitated in the manner described in the foregoing so as to perform circular oscillations, then both the hollow receptacle b and also all the auxiliary bodies in the interior thereof will perform circular oscillations, i. e., each individual auxiliary body describes a circle corresponding to the amplitude of the circular oscillations and is thus caused to roll over the surrounding material.

Since material to' be ground is now between the individual spherical or cylindrical grinding bodies, said material is ground under very favourable conditions by the aforesaid rolling process.

In such a device, it is possible through the throw of the circular oscillations (the amplitude), which is variable within wide limits, or through the frequency, which can also be readily varied to a. large extent, to vary the contact pressure of the grinding bodies against each other, i. e., the grinding itself, to an extreme degree. This produces a grinding machine which is not merely extremely adaptable to the materials to be treated, but in which it is possible to determine the optimum efliciency for each size of machine and kind of material.

Apart from this, however, owing to the fact that the grinding chamber rotates slowly during the grinding process together with all the auxiliary bodies, the grinding machine of the present invention affords an excellent mixing and distribution of the material to be ground, said material being constantly conveyed from the lower layers to the top and after passing between the grinding bodies rolling over each other being again subjected to the grinding process.

Instead of using the loose coupling described in the foregoing, the agitation of the grinding cylinder with circular oscillations can be carried out with the aid of any other desired coupling device. Thus for example, in the embodiment shown in Fig. 4, the driving shaft 3 can be passed through a hollow tube e in the middle of the grinding cylinder b. At both ends of the latter (b') are disposed cranks In and k2, the pins 21 and 22 of which engage cranks kg and k4 respectively on the driving shaft 1 The cranks I01 and 702 are rotatably mounted on the tube e' and the inner ends of the pins 21 and 22 are rotatably secured in said cranks. The outer ends of the pins 21 and 22 are rigidly secured in the outer ends of the cranks its and k4. The cranks kg and k4 are rigidly mounted at their inner ends on the shaft 1 This arrangement permits the inner drum b to travel in a clockwise path and rotate in a counterclockwise direction as does the drum b of Figs. 1 and 2. If the shaft 1 be rotated, the resiliently mounted grinding cylinder b will at first lag behind somewhat owing to its inertia and to the fact that it gives to the forces acting on the crank pins 21 and 22, i. e., it will move eccentrically around the shaft y owing to the fact that its gravitational axis describes a cylindrical path around the axis of the shaft 3 see Fig. 4a. The radius of this path increases in length as the frequency of the circularoscillations increases and consequently the centrifugal force acting on the grinding cylinder also increases.

Another type of loose coupling is obtained by enlarging the inner tubes e", e' of the grinding device at their ends, as shown respectively in 'Figs. 5 and 6, and allowing a cylindrical or conical body kn, kl2 to roll in the resulting enlarged space .at both ends over elastic members 0' through the rotation of the shaft y and of an eccentric shaft w. If this be done on both sides of the grinding machine, the latter will be agitated so as to perform circular oscillations in planes which may be regarded as passing vertically through the grinding machine or the driving shaft 1 Figure 7 shows a modificationwhich illustrates an actuation of the device by means of loose coupling which. is formed by mounting an eccenthe shaft 1 which can be accomplished in any manner, such as by a belt pulley (Fig. 4) or by means of a flexible shaft, the force created by the rotating swinging mass m1 is transferred to the hollow cylinder 1) with a 90 phase displacewise direction. The force aforesaid is relayedwith a 180 phase displacement to the outer swingingly mounted cylinder a which acts as a counterweight, by which a mass adjustment takes place between the hollow cylinder b and the cylinder a.

Figs. 8 and 8a show another actuation of the device by means of a loose coupling. This loose coupling is formed by providing a disk g on both outer ends of the shaft 1 on which is mounted a diametrical slide-guide u which receives a sliding shoe s that is provided on the free end with a ball socket. In this ball socket is received the ball-shaped end 212 of a lever arm 1621 which is connected to the counter-weight mass a by a double cardan joint. The double cardan'joint is formed in a known manner. It comprises pins v and e which are arranged at right angles to each other and which are mounted on the outer end of the lever arm 1621. The ends of the pins resistance to any yielding in the axial direction.

In contrast to the cardanic mounting with round plugs and frictionless beds as is known in the art, the pins 0' and v and their bearings 11 and 12 are shaped elliptically and are'provided with a similar shaped rubber filling between plug and hearing, which creates a resistance to each devi ation of the leverarm I021 fromthe axial direction, which resistance is reflected in the counterweight mass a. Cardan joints of this kind thus transmit elastic forces between the two oscillating masses, just like other loose couplings. These forces increase with the deflection (amplitude), so that the energy transmitted per oscillation, i. e., the output per second also varies with the deflection of the coupling.

As the degree of .the deflection is in turn dependent on the frequency, it is at once evident that in the present embodiment and in those described in the foregoing the transmitted power and thus also the effective grinding output increases with the frequency on account of the increase of the centrifugal force.

It will also be seen that" the sliding track It in the present embodiment is not absolutely essential because asymmetry of the hollow recepe tacle b, necessary for the rotation, can be expected in all cases, on account of the weight of the receptacle 1) and the distortion thereof by centrifugal force so that the coupling (Fig. 8)-can also be set in motion without an eccentric sliding track. The eccentric sliding track merely affords the advantage that the starting up or the transmission of power is immediately and more energetically established by the coupling.

Finally,Fig. 9 illustrates a loose coupling that can be used to drive the apparatus of the present invention. The sliding track it, the sliding shoe s and the eccentric lever R131. correspond exactly to the loose coupling described in Fig. 8.

On the other hand, the lever 7 31 is not connected to the outer mass a by an elastic universal joint but is connected rigidly thereto. Consequently relative displacement of the masses a and b can occur only in the direction of the sliding track u, whereas the loose coupling described in Fig. 8

permits phase displacements in every direction.

The loose couplings as illustrated in Figs. 1, 2, 5, 6; '7 and 8 can yield in the'direction of both .the space axes applicable to the, circular oscillations and thus represent the best possible working systems, while the couplings shown, in Figs. 4 and 9 are prevented from yielding in respect of one axis. In the case of circular oscillations of the present kind, however, the loose couplings 1 shown in Figs. 4 and 9 can also be used with good results. a

Fig. 10 illustrates a mechanism foradjusting.

the resilient members 0. The resilient spherical buffer 011 is in this case secured toa lever-like support 11, which is pivoted to a bearing q. By adjusting the screws t the resilient member se cured to the outer mass a. is brought near to the l 75 inner mass 1), i. e., the initial elastic tension isand 12. The space between- In contradistinction to the increase ing a rotary movement by tangential forces, for

'example by the suspension-means h or resilient supports acting in a similar manner, while the grinding chamber b may perform a slow rotary movement facilitating the grinding process, in addition to the circular oscillation, for the purpose of loosening and mixing the material under treatment. h

Moreover, the invention also includes the case second mass is secured on elastically yielding supporting devices, and where the counter or second mass a consists not of a cylinder jacket but of separate rings or other composite constructional arrangements. I

Although the shapeof the auxiliary bodies used for the grinding may affect the grinding operawhere the non-rotating hollow body acting as the tion to some extent depening on whether they are of cylindrical, oval or spherical shape, and similarly the curved surfaces ceptacle, depending 'on how. they vary between the cylindrical and prismatic form, such variations are immaterial for the purpose of the present invention.

I claim: 1

of the hollow rea 1. A device for grinding material including a swingable receptacle for containing loose grinding bodies having their axes parallel to the axis of said receptacle, a swingable body surrounding said receptacle and having its axis parallel to that of said receptacle, means mounting said body for limited swinging movement, said mounting means causing said body to serve as a counter- -weight for the said receptacle, said' receptacle being positioned withinsaid body and elastic means spacing said receptacle and body apart.

2. The structure of claim 1, elastic means for preventing'the rotation of said body, and means for moving said receptacle in a circle within said body.

3. The structure of claim 1, a rotatable shaft arranged axially of said body and said receptacle,

cranks carried by said receptacle and freely rotatable on the same at eitherend thereof, cranks on said shaft and rotatable therewith, a rigid connection between each crank on said shaft and the corresponding crank on said receptacle whereby to swing said receptacle in a circle around said shaft.

4. The structure of claim l, a rotatable shaft arranged axially of said body andsaid receptacle,

cranks carried by said receptacle and freely rotatable on the same at either end thereof; cranks on said shaft and rotatable therewith, a rigid connection between each crank on said shaft and the corresponding crank on said receptacle whereby to swing said receptacle in a circle around said shaft, and elastic means for preventing the rotation of said body. a

5. The structure of claim 1, elastic means for preventing the rotation of said body, a rotatable crank shaft arranged axially of said receptacle and said body, and a resilient connection between said shaft and said receptacle, said shaft being freely rotatable in said connection.

6. The structure of claim 1, elastic means for preventing the rotation of said body, a rotatable crank shaft arranged axially of said receptacle and said body, and a resilient connection between said shaft and said receptacle, said shaft being freely rotatable in said connection, said connection comprising circular members freely rotatable on said shaft adjacent said receptacle, and resilient bufler members carried by said receptacle and engaging the peripheries of said circular members.

7. The structure of claim 1,a rotatable shaft arranged axially of said receptacle and said body, means for preventing the rotation of said ,body, means for swinging said receptacle in a circle within said body, of plates fixed on said shaft adjacent each end of said receptacle, sliding tracks on said plates,

shoes adapted to slide in said tracks, and meanssaid means comprising a pair carried by said body eccentrically of said shaft and engageable with said slides.

8. The structure of claim 1, a rotatable shaft arranged axially of said receptacle and said body,'

means for preventing the rotation of said body,

means for swinging said receptacle in a circle within said body, said means comprising a pair of plates fixed on said shaft adjacent each end of said receptacle, sliding tracks on'said plates, shoes adapted to slidein said tracks, and means carried by said body eccentrically of said shaft and engageable with said slides, said means connecting said body to said slides and comprising a Cardan joint.

9. The structure of claim 1, means for preventing the rotation of said body, means for swinging said receptacle in a circle within said body, and the stretching of said elastic means during said swinging being variable.

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