US3526686A

US3526686A - Method for shaping of granular substances

Info

Publication number: US3526686A
Application number: US675209A
Authority: US
Inventors: Gottfried Weinhold
Original assignee: Vereinigte Aluminium Werke AG
Current assignee: Vereinigte Aluminium Werke AG
Priority date: 1966-10-14
Filing date: 1967-10-13
Publication date: 1970-09-01
Anticipated expiration: 1987-09-01
Also published as: BE704878A; DE1558745A1; US3555599A; NL6713953A; CH487717A; NL153278B; GB1199975A; AT288045B; DE1584817B1; DE1558745B2

Description

p 1970 G. WE lNHOLD 3,526,686

METHOD FOR SHAPING OF GRANULAR SUBSTANCES Filed Oct. 13, 1967 5 Sheets-Sheet 1 Jill II II Ii Fig. I

P 1, 1970 G. WEINHOLD 3,526,686

METHOD FOR SHAPING OF GRANULAR SUBSTANCES Filed Oct. 13, 1967 5 Sheets-Sheet 2 Fig.2

1* A lnventar:

P 1970 G. WEINHOL .D 3,526,686

METHOD FOR SHAPING OF GRANULAR SUBSTANCES Filed Oct. 13, 1967 5 Sheets-Sheet 5 Fig.3

Sept. 1, 1970 G. WEINHOLD METHOD FOR SHAPING OF GRANULAR SUBSTANCES Filed Oct. 13, 1967 5 Sheets-Sheet 4 P 1970 G. WEINHOLD 3,526,686

METHOD FOR SHAPING OF GRANULAR SUBSTANCES Filed Oct. 13, 1967 3v Sheets-Sheet 5 I In veqtor;

United States Patent O 3,526,686 METHOD FOR SHAPING F GRANULAR SUBSTANCES Gottfried Weinhold, Norf-Derikum, Germany, assignor to Vereinigte Aluminium-Werke Aktiengesellschaft,

Bonn, Germany Filed Oct. 13, 1967, Ser. No. 675,209 Claims priority, application Germany, Oct. 14, 1966, V 32,125; July 1, 1967, K 62,705 Int. Cl. 1328b 1/08, 1/10 U.S. Cl. 26471 4 Claims ABSTRACT OF THE DISCLOSURE A form is adapted to accommodate a quantity of granular material and is suspended on a plurality of springs for movement in a plurality of directions, including a pair of mutually opposite directions. At least two imbalanced masses are mounted on the form for rotation in mutually opposite directions. Drive means rotates the imbalanced masses in said directions so that the vibratory stresses transmitted by the rotating masses to the form, and tending to cause movement of the same in the plurality of directions, are balanced whereby the form performs movements only on the mutually opposite directions.

BACKGROUND OF THE INVENTION The present invention relates to the shaping of granular masses in general, and more particularly to a method of effecting such shaping. The invention also relates to an apparatus for carrying out the method.

In a variety of applications it is necessary to compact granular materials into a predetermined shape so that they will form homogeneous bodies of uniform density. The materials used for this purpose are of sand-like consistency and of viscous character without, however, having a plastic character. In the aluminum-making industry with which the present invention is particularly concerned without, however, being limited thereto, such bodies are required as electrodes for electrical furnaces and consist of pole granules.

It is well known that in the aluminum industry the trend to ever larger furnaces requires the provision of even larger anodes. Such anodes may reach weights of 4 tons and, once they have been formed from coal granules, are baked before they are ready for use. Until comparatively recently shaped bodies of this type were manufactured by compacting the granular masses in effect manually, namely by hand-held compacting tools or rammers which were operated by compressed air. However, this is a time-consuming and expensive process and is economically feasible only for certain special applications. An alternate solution was found in manufacturing the electrodes in presses, specifically in extrusion presses. However, these are suitable only for the production of comparatively simple and small-dimensioned articles because they limit the cross-sectional area of the article which can be manufactured and in practice permit only the production of one standard-sizes article per extrusion press.

To manufacture larger dimensioned articles it has lately become known to use a stamping process where rammers are driven by eccentric shafts and stamp the granular mass for the purpose of compacting it into the desired shape. Machines of this type are relatively in expensive as compared to extrusion presses capable of producing similarly dimensioned shaped articles. However, the stamping produces very significant vibrations and it is therefore necessary to construct special foundations for the machines to prevent the transmission of these vibrations to the buildings in which they are housed. This is expensive and, furthermore, even with these machines the size of articles which can be produced is relatively limited. An additional drawback of this type of machine lies in the fact that if the shaped articles are to be flawless and homogeneous throughout, the granular mass must be stamped in several layers which requires that the manu facturing process be subdivided into several stages. These problems exist particularly if the shaped articles, which hereafter will be referred to as electrodes because of the particular utility of the present invention for the manufacture of such electrodes, but which are not limited in this sense, exceed weights of approximately 3000 kg.

SUMMARY OF THE INVENTION The present invention overcomes the disadvantages discussed above.

More particularly, the present invention provides a method of manufacturing shaped articles from granular masses wherein the granular mass, whose consistency may range between a state of high viscosity-but not plasticityand actual crumbliness, is subjected to compacting forces of between 10,000 and 30,000 kg. by having transmitted thereto a low frequency preferably in the range of 20-30 Hz. In accordance with the invention this lowfrequency vibratory stress is transmitted by imbalanced masses which act upon the form in which the granular mass is accommodated and which stresses are so balanced by a spring mounting system for the form that the need for a special foundation is eliminated.

In accordance with one feature of my invention I provide a method which comprises suspension of the form-in which the granular material to be compacted is accommodated-for movement in a plurality of directions including a pair of mutually opposite directions. I transmit to the form vibratory stresses at a plurality of points, which causes the form to attempt movements in the plurality of directions. Further in accordance with the invention I balance these stresses so that the resultant stress causes the form to perform movements only in the aforementioned pair of mutually opposite directions so that the granular material contained in the form is compacted into a solid body while the influence of the stresses is substantially limited to the form and the need for providing a special foundation is obviated.

By providing my novel method, and an apparatus for carrying out the method, I make it possible to manufacture the electrodes at a significantly lower cost than in the aforementioned prior-art process, taking into account the maximum size of electrodes which can be produced. Elimination of the special foundation constitutes a significant saving and, furthermore, means that the machine can be moved rather than having to be stationary. The entire quantity of granular material required for producing a given electrode, regardless of the size of the finished body, can be worked upon in a single operating stage and the size and configuration of the electrode can be varied in a most simple manner by exchanging differently shaped and/or configurated forms. This makes it possible to manufacture rather small electrodes, which are preferably constructed in a relatively large form which is subdivided into a plurality of individual compartments each of which corresponds to the size of the desired electrode so that several of the electrodes can be manufactured at the same time, as well as to manufacture large electrodes having a weight of 4 tons and even more. Furthermore, the homogeneity of the articles produced in accordance with the present invention is significantly better than What has been known heretofore.

My invention is based on the fact that two oppositely rotated masses with an exciter frequency w produce the force m.r.w This causes vertical oscillations of the apparatus at a characteristic frequency w In view of the fact that the masses are rotated in mutually opposite directions the main vibration stress components do not act in outward direction in the horizontal. The vertical oscillation produces in the supporting springs which are utilized in accordance with the invention, forces P which can be calculated for small amplitudes and for a nondamped arrangement as follows:

(1': dynamic factor) P -r.m.w,,

Thus, if w is smaller than w r becomes smaller than 1, and in borderline cases r approaches 0.

This means that dynamic forces are practically eliminated in the springs and that a balance is established between exciter force and mass force so that no special foundations need to be erected for vibrating and compacting granular material into large-dimensioned bodies with an apparatus according to the present invention.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a somewhat schematic side view of an apparatus according to the present invention;

FIG. 2 is a front view of the apparatus illustrated in DESCRIPTION OF THE PREFERRED EMBODIMENTS Discussing now the drawing in detail, and firstly FIGS. 1 and 2 thereof, it will be seen thta the machine according to the present invention comprises a base or frame 1 on which there are mounted the coil springs 2 which support the form, including the vibratory support 3 thereof. FIGS. 1 and 2 clearly show that the vibratory support 3 is mounted in floating condition-that is for free movement in all direction-on the springs 4. Built into the support 4 are the imbalanced bodies 5 which are rotatable on the shafts 8 by having rotary movement transmitted thereto through the articulated shafts 7 from the drives 6. A suitable scale may he provided on the bodies 5 and permit adjustment of the vibratory force between zero and the maximum permissible range.

A forming plate 9 is supported on the support 3 and a form 10 is carried on the forming plate 9 and is rigidly but releasably connected with the vibratory support 3 and thus with the forming plate 9 by the hold-down arrangements 11. A suitable metering arrangement fills the interior of the hollow form 10 with the requisite quantity of granular material and, when a cover plate has been placed onto the granular material in the form 10 in a manner which will be subsequently discussed in more detail, vibratory movement is initiated. By guiding the cover plate within the form 10 I assure that the body which is being produced receives a smooth, straight upper surface.

While FIGS. 1 and 2 show the bodies 5 connected to the support 3 it is to be understood that the vibratory force could also be transmitted through the aforementioned cover plate in which case the bodies 5 would have to be mounted for rotation on or in the cover plate in a manner which will be readily understood by those skilled in the art. Coming now to FIGS. 3-5, which illustrate an embodiment of the invention in more detail, it will be seen that the vibration apparatus comprises a vibratory support 12 which may be vibrated for instance by two oppositely rotating imbalanced masses or bodies in the manner illustrated in FIGS. 1 and 2. These bodies are rotated by respective electromotors 13 via two shafts 14 and suitable couplings or gears, which are not illustrated because they are conventional. A forming plate 15 is provided with fields and a form 16 is supported on the forming plate 15. A cover plate or weight 17 is provided and, to permit removal of the cover plate 17 and of the form 16 individually upon completion of the compacting process, a frame 18 is provided on which electrically operated lifts 19 and 20 in form of pulleys or the like are arranged. The cover plate 17 is supported on a traverse ,21 Whose upper portion 22 is held by grippers 23 in the rest position, and these grippers may be hydraulically operated. It will be understood that, if a plurality of relatively small finished bodies are to be produced rather than a single large body, the form 16 may be subdivided internally into a plurality of compartments. In that case the cover plate 17, which rests on the granular material within the form 16 to weight this material, may be similarly subdivided in that it comprises a plurality of portions each of which extends into one of the compartments and rests on the granular material therein. This assures that the weight is equally distributed to the material in all of the compartments.

The traverse 21 is connected to the lift 19 by means of cables 24 and pulley wheels 25. FIG. 3 shows that glides 26 are provided on the traverse which engage guide rails 27 on opposite sides. Inasmuch as the guide rails are connected to the frame 18 the cover plate 17 is thus reliably guided for straight movement. It is advantageous that the guide rails 27 be so configurated that their profile tapers in downward direction in such a manner that during the actual vibration the glides 26 will have no contact with the guide rails.

In view of the fact that the cover plate 17 is intended to be usable both under circumstances where a single body is to be produced and under circumstances where a plurality of relatively small bodies are to be produced in the form 16, it is advantageous that a plurality of projecting rams 17" be provided which are mounted on a replaceable bottom plate 17' so that a simple exchange sufiicies to convert the plate 17 to the desired mode of operation.

The lift 20 is provided for lifting the form 16 and to this purpose counterweights 28 (compare FIG. 4) are connected to the cables of the lift 20 at opposite sides of the frame 18. Once the form 16 has been lifted off the forming plate 15 it is secured by hydraulically operated grabbers 29.

A weighing arrangement 30 is provided adjacent the frame 18 and includes a plurality of containers whose number may correspond to the number of compartments in the form 16. Advantageously the containers, which at their undersides are provided with discharge openings, are so constructed that the closure for these discharge openings will expose the entire cross section of the opening when discharge is being effected so that the granular mass, which has a tendency to clump together, will be discharged into the form 16 without danger of residual quantities remaining in the containers. Adjustable chutes (not illustrated because known in the art) feed a distributor device 31 which distributes the granular mass to the containers.

Located at the other side of the vibrating apparatus is a transporting arrangement for the finished compacted bodies. In the illustrated embodiment, which is only exemplary and by no means to be considered exhaustive, this arrangement consists of a driven belt which is supported by the supporting rollers 32 and which leads to an inclined roller conveyor 33 of known construction. Of course, grippers can be used to replace the driven belt and they can be so connected with the vibrating apparatus itself that they will automatically remove the finished electrodes from the apparatus and convey them to a given location.

In operation of the apparatus illustrated in FIGS. 3-5 the engagement portions 34 provided on the member engage into chains 35 located at opposite sides of the member 15 so that, when the form 16 has been fillled with material as illustrated in broken lines at the righthand side of FIG. 3, the form is conveyed into its operative position over the vibratory support 12. It is advantageous if the vibratory support is surrounded by a frame which is vertically movable and which is provided with rails for the rollers of the forming plate 15. The frame is identified in FIG. 3 with reference numeral 36 and can be raised and lowered together with the form 16 by means of four hydraulic cylinders 37 which are connected at the four corners of the frame 36. By means of the frame 36 the forming plate 15 can be so lowered that it will rest with its underside on the vibratory support 12 so that the rollers of the forming plate need not carry any load. In accordance with the illustrated embodiment the projections 34 will disengage from the chains when the lowering occurs. It is advantageous that the piston rods of the hydraulic cylinders be so connected with one another that they will be maintained at identical elevation and can thus be controlled with a single regulating valve. This assures that no tilting of the frame 36 occurs. In accordance with the invention it is further advantageous that, as the frame 36 is lowered, the plate 17' of the cover plate 17 is sprayed with a suitable emulsion, for instance an oil emulsion, from several nozzles 41 which are actuated by such lowering via a suitable control device many of which are known in the art and which does not constitute a part of the invention. The oil emulsion is provided for the purpose of facilitating separation of the plate 17 from the compacted body and excess emulsion is allowed to drip into the form 16.

It will be understood that the form 16 and the vibratory support 12 must be rigidly connected with one another for operation of the device. It is therefore advantageous to effect such connection by means of hydraulic cylinders which act upon a force-magnifying lever arrangment being that the use of the lever arrangement permits advantageous dimensioning of the hydraulic cylinders as far as size and force are concerned.

In operation of the device it is advantageous that the plate 17 is lowered into the upper open end of the form 16 while the latter is being releasably coupled to the vibratory support 12. Of course it will be understood that the plate 17 must rest loosely on the mass in the form 16 so that, as the volume of the mass decreases during compaction, the plate 17 will continue to rest on the upper surface of the mass and will exert pressure at all times. The actual vibration procedure in the apparatus according to the present invention will last approximately 4 minutes and, when it is completed, the form 16 is first lifted slightly which will ease separation of the electrode from the form, and thereupon the plate 17 and the form 16 are lifted completely and withdrawn so that the shaped body, namely the completed electrode, now rests exposed on the plate 15. The electrode is now conveyed to the transport arrangement 32, advantageously by means of the chain 35 and by being conveyed over the lowered forming plate 15. When this is completed the forming plate is restored to its position, the form 16 lowered onto the forming plate 15, and the form conveyed on the forming plate 15 below a spraying device 42 which is diagrammatically illustrated in FIG. 3 and which sprays an oil emulsion into the intetrior of the form 16. How this-is accomplished, and the control of the spraying device 42 are well known in the art and need not be further described. Once the interior of the form 16 has been sprayed, the form is conveyed to the spraying arrangement 30 where it is filled with new granular mass,'and it is then returned to the vibratory support. In view of the fact that all operating components of the apparatus illustrated in FIGS. 3-5 are arranged in close association with one another it is advantageous to connect the entire apparatus to a control or program device so that all steps of the operation will be automatically carried out, thus eliminating the danger of wrong operation by an operator, it being understood that, if an operator were to control the manifold steps by manual actuation of switches or the like, errors could not be avoided.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of arrangements differing from the types described above.

While the invention has been illustrated and described as embodied in an apparatus for shaping of granular substances, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims:

1. A method of compacting granular material in a form, comprising the steps of suspending the form for movement in a plurality of directions, including a pair of mutually opposite directions; and transmitting to the form vibratory stresses of a force between substantially 10,000 and 30,000 kg. and a frequency ranging between 20 and 30 Hz. at a plurality of points in such a manner as to balance said stresses so that the resultant stress causes said form to perform movements only in said pair of mutually opposite directions, whereby granular material contained in the form is compacted into a solid body and the influence of the stresses is substantially limited to the form.

2. A method as defined in claim 1, wherein the step of transmitting said vibratory stresses comprises transmitting to said form stresses produced by rotation of unbalanced masses.

3. A method as defined in claim 2, wherein the step of balancing said stresses comprises adjusting the rotation of said masses with reference to one another in such a manner as to balance the stresses produced by rotation of each individual mass.

8,526,686 7 8 4. A method as defined in claim 3, wherein the step 2,407,168 9/1946 Lindkvist. of adjusting the rotation of said masses comprises rotat- 2,636,719 4/1953 OConnor.

ing said masses in mutually opposite directions of rotation. ROBERT F. WHITE, Primary Examlner References Cited 5 R. H. SHEAR, Assistant Examiner UNITED STATES PATENTS US. Cl. X R' 2,353,492 7/1944 OConnor 25--41 25 41 1,922,168 8/1933 Lowell 2541