US 3756762 A
The present invention discloses a method and apparatus for compacting artificial carbon bodies for use as electrodes in aluminum electrolysis and for lining the cathode portions of an electric furnace and using them as anodes in such furnace, wherein the artificial carbon mass to be compacted is placed into a mold and becomes jarred from below by a freely movable bottom member and at the same time it is loaded from above through a freely movable cover member by a gradually increasing pressure which may be accompanied by additional jarring through the cover member and through the side walls of the mold.
Claims available in
Description (OCR text may contain errors)
Unite States Patent Maugweiler [451 Sept. 4, 1973 75 inventor: Gottfried Maugweiler, Chippis,-
Switzerland  Assignee: Swiss Aluminium Ltd., Chippis,
Switzerland 221 Filed: Feb. 2, 1970 211 Appl.No.:7,513
 Foreign Application Priority Data McElroy 25/41 J 3,041,701 7/1962 Gates 425/415 FOREIGN PATENTS OR APPLICATIONS 532,218 8/1931 Germany 1. 25/91 532,497 8/1931 Germany 25/91 1,160,066 2/ 1958 France 425/421 Primary Examiner-Robert D. Baldwin Att0rney-'-Ernest F. Marmorek  ABSTRACT The present invention discloses a method and apparatus for compacting artificial carbon bodies for use as electrodes in aluminum electrolysis and for lining the cathode portions of an electric furnace and using them as anodes in such furnace, wherein the artificial carbon mass to be compacted is placed into a mold and becomes jarred from below by a freely movable bottom member and at the same time it is loaded from above through a freely movable cover member by a gradually increasing pressure which may be accompanied by additional jarring through the cover member and through the side walls of the mold.
9 Claims, 6 Drawing Figures Pmmm m3 sum1or3 PATENTEU SHEET 3 UP 3 APPARATUS FOR COMPACTING CARBON BODIES Field of the Invention The present invention relates generally to apparatus for producing artificial carbon bodies and, more particularly it relates to apparatus for producing artificial carbon bodies which are used as electrodes in alumi- Background of the Invention The above-described carbon bodies are conventionally made even today on billet, extrusion or stamping presses.
As a result of the progress made by the aluminum industry bigger and bigger electrolysis furnaces are required, which of course require also large artificial carbon bodies. The devices for the making of such large molded bodies require similarly large investments which fact makes them uneconomical. In addition to the above-mentioned conventional methods a jarringforming has been long known and successfully used to make blanks in conventional or in increased dimensions.
The making of blanks or molded bodies by jarring or vibration has been used in different areas, such as, in the construction industry for making concrete bodies, in the casting industry for compacting the molding sand, or in the ceramics industry. Such methods offer the advantage of simple installations in addition to easy form changes.
For the making of artificial carbon electrodes as early as in the 1920s several jarring methods had been proposed, such as, the use of vibrations or beating at low or higher frequencies. There has been, for example, a beating device described in which the bottom and the shell of the mold for purposes of heating or cooling are constructed with a double wall and on top of the mass a heatable cover is placed. Throughsuch cover a considerable pressure can be applied on the mass under compaction.
Recently'another proposal became known which retains the basic features of the older method, that is, the.
shell is fixedly connected with the jarring table. The oscillations having a frequency of -30 Hz are produced through an eccentric member built into the jarring tahle. The covering weight is loosely placed on the mass.
Such devices possess a disadvantage in that they re quire a high energy consumption and exhibit strong wear as soon as larger units are made. The high energyv consumption can be explained by the fact that the entire mold has to be jarred. The wear of the mold is caused by the cover weight, which due to its relatively high lying center of gravity, it has a high degree of free-- dom and as a result of the intensive jarring process it moves back and forth over the mass between the shell walls. In addition, the cover weight applies a constant pressure on the mass throughout the jarring process which pressure must be sufficiently large in order to obtain the desired density and compaction by the end of the jarring process and which pressure, however appears to prevent the escape of the trapped gases at the beginning of the process.
SUMMARY OF THE INVENTION It is, therefore, an object of the present invention to provide a novel apparatus for making the artificial carbon bodies of the above-described type, which apparatus does not possess the described shortcomingsof known methods and apparatus.
The invention in one aspect thereof provides apparatus for making carbon electrode bodies according to which the artificialcarbon mass to be compacted is jarred from below and at the same time it is loaded from above by a gradually increasing pressure which can be static or dynamic. Preferably both types of pressure are superimposedly applied. When according to the invention jarring is applied from below and as well as above, then the oscillations applied from below have different characteristics from those applied from above.
The invention in another aspect thereof provides an apparatus according to which the bottom of the mold for receiving the artificial carbon mass for compaction is formed as a jarring table and supporting the mass, while such table being freely moveable within the shell of the mold. The shell is supported in a manner decoupling it from the jarring oscillations. The mold is covered by a cover member which is freely movable but closely fitting within the shell and on which pressure producing means are operative.
As pressure producing means, mechanical, hydraulic or pneumatic devices are considered according to the invention. The force reactions of such devices are received in a frame construction which extends around and above the mold. Furthermore, according to the invention dynamic devices are also considered as pressure producing means which can be in the form of oscillators and mounted on the cover. Such oscillators can be used in combination with the afore-mentioned pressure producing devices.
Brief Description of the Drawings The invention will become more readily apparent from the following description of preferred embodi ments thereof shown in the accompanying drawings, in which: a FIGS. 1 and 2 illustrate an embodiment of the compacting apparatus according to the invention in which the shell is supported on its sides and the pressure ap-. plied from above is produced by a pressure cylinder, FIG. 1 showing the apparatus during the process, while FIG. 2 illustrating the apparatus after the completion of the jarring process with the cover and shell lifted off;
FIG. 3 illustrates another embodiment of the apparatus according to the invention in which the shell is suspended freely floating; I
FIG. 4 illustrates a further embodiment of the apparatus according to the present invention'in which the Description of the Preferred Embodiments In the embodiment shown in FIGS. 1 and 2 the mold used for compacting the artificial carbon mass therein comprises a shell 1 and a jarring table 2 which is independent and freely movable with respect to the shell 1. The jarring table 2 is mounted on spring means 3 and carries on its underside an oscillation producing means 4. This oscillation producing means 4 may be in the form of electromagnetic vibrators, pneumatic jarring devices or eccentertype motors, or eccenter elements driven by a side-mountd motor. In the embodiment illustrated the shell 1 sits on a pedestal 5 through an intermediately mounted oscillation damper 6.
In the event it becomes necessary, the invention provides for guides in order to center the shell 1 with respect to the table 2.
The mold as formed by the shell 1 and jarring table 2 receives the artificial carbon mass 7 for compaction. On the mass 7 a cover 8 is laid which is freely movable within the shell 1. The cover 8 is secured to the lower end of a rod 9 of a two-way operable pressure cylinder 10, which is constructed with a length permitting the lifting of the cover 8 sufficiently high enough to allow for the filling of the form and for the lifting of the shell 1 above the blank 11 as shown in FIG. 2 after the completion of the compacting process. For the purpose of lifting the shell 1 is provided on its sides with hooks 12 which can be pivoted into engagement with the cover 8. The cylinder is secured to a portal tower-like frame structure 13. According to the size of the cover several such pressure producing and lifting systems can be provided on the frame. The entire molding apparatus is built on a base frame 14 which by means of intermediate oscillation dampers 15 rests on the ground 16.
In order to avoid that the oscillations of the mass 7 which affect the cover 8 from being carried over onto the piston rod 9, it is preferred to mount an oscillation damper 17 between the cover 8 and the rod 9. According to the invention the cover 8 itself can also be provided with oscillating devices 18 for imparting oscillations to the mass 7 from above.
The embodiment shown in FIG. 3 differs from the embodiment shown in FIGS. 1 and 2 in that the shell 1 is not supported by a pedestal as in FIGS. 1 and 2, but it is suspended from a cable 19 or from a Gall chain which is passed over a guide roller 20 and at its free end is loaded with a counter-weight 21. A locking device 22 is provided for fixing the shell 1 at a height required for the filling of the mass. After filling the locking device 22 can be released and the shell I may assume a height during the jarring process as determined by the friction forces developed between the shell 1 and the mass 7.
In the embodiment shown in FIG. 4 the upper pressure operating on the cover 8 is produced solely by means of an oscillation generator 18. For the lifting and lowering of the cover 8 a cable or chain train 19' is provided. The weight of the cover 8 is compensated by eounterweights 2| The operation of the above-described embodiments is as follows:
With the cover 8 lifted high the mold is filled with an accurately measured plastic mass consisting of coke powder, additives and binding agents, such as, tar, at a temperature of about l00 to 180C. Then the cover 8 is lowered on the top of the mass 7 and the oscillation generator 4 mounted on the jarring table 2 is turned on.
The above-described suspending devices 9, 10 and 17 of the cover 8 permit there to be imparted a relatively small initial pressure by the cover at the beginning of the jarring process. As a result the air and tar vapors trapped in the mass 7 can freely escape. Due to the effect of the oscillations coming from below the mass 7 collapses relatively fast. Right at the beginning, that is,
during the first few seconds of the jarring process, a gradually increasing pressure is applied to the cover 8 by means of the pressure producing devices, such as the cylinder 10 in FIGS. 1-3, and thereby onto the mass 7, until it reaches a few kg/cm. The jarring process is continued until a desired density of the blank is obtained.
In the case when relatively high blanks are produced, the oscillations produced by the jarring table may not be able to pass through the entire height of the carbon mass. In such a case it becomes advantageous to impart oscillations on the mass also through the cover. It is preferred that the oscillations produced from above have different characteristics then the ones produced from below. As a result mixed or resonance oscillations take place which pass through the entire volume of the blank.
The compacting can be further improved according to the present invention by imparting substantiallyhorizontally directed oscillations onto the mass through the walls of the shell 1. With longer blanks the side vibrators (not shown) can be placed in the middle region on both sides of the shell wall.
Upon completion of the jarring process the shell 1 is lifted upward as shown in FIG. 2 whereupon the blank can be ejected sideways. In the event the blank is stuck in the shell 1, the pressure on the cover 8 should be continued while the shell is being lifted. An auxiliary device (not shown) can be provided to impart a light lifting to the shell 1 in such a case.
The embodiment shown in FIG. 4 makes it possible that a lower initial pressure could be followed up with a higher cover pressure for the compacting. At the beginning of the jarring process the relatively light cover is placed on the mass. A few seconds later the vibrators are turned on.with gradually increasing imbalance, that is, jarring. As a result, the pressure produced by the weight of the cover becomes superimposed by an increasing dynamic pressure. In the event only a slight pressure is required at the beginning, the weight of the cover 8 can be compensated partially by the suspension system.
The embodiments shown in FIGS. 5 and 6 are much more mechanized than the previously described embodiments. The jarring table 2 is placed so high above the ground that the shell 1 after completion of the jarring process can be lowered below the jarring table. (FIG. 6). Such lowering of the shell 1 can be accomplished by means of corresponding mechanical, hydraulic ,or pneumatic devices such as shown at23. At the height of the jarring table 2 and adjoining it a conveyor 24 is provided for the removal and delivery of the completed blanks.
On the frame structure at a necessary height over the jarring table one or more rails 25 are provided on which a movable aggregate can travel as caused to move by appropriate means 28, shown illustratively as being a hydraulic means. The movable aggregate comprises a charging container 26, a hydraulically operated up and down movable blank ejecting device 27 and an up and down movable cover 8 which is similarly constructed as in FIGS. 1 and 2.
Above the movable aggregate the frame structure 13 carriessecured thereto a weighing container 29-and "abacking hea'd 30 thefunction of which will be hereinafter described. As'soon as the weighing container is filled with a mass having-ade'sired weight, it is emptied into the charging container 26 which at this time is located below it. The backing head'30 functions asa backing for the mechanism 9 and 10 operating the cover 8 during the jarring processand translates the reaction forces developed during such process onto the frame structure. In order to provide for unimpeded back and forth movement of the movable aggregate, in the rest position when there is no jarring, the backing head 30 and the upper front surface of mechanism 9, 10 moving the cover 8 up and down are separated by a gap as seen in FIG. 5. In order to avoid that the end of the movable aggregate carrying the driving mechanism 9, 10 from lifting when the pressure is set by the cover 8 on the mass, the driving mechanism 9, 10 of the cover 8 is movably mounted along its longitudinal axis in the frame 32 of the movable aggregate by means of a spring 31. In the rest position, when the cover 8 exerts no pressure on the carbon mass, a spring 31 permits a light sinking of the cover together with its driving mechanism under its own weight, whereupon the abovementioned gap is formed between the backing head 30 and the mechanism 9 and 10. As soon as the cover is placed onto the mass and the piston rod 9 starts to press the cover downward, the cylinder 10 starts to move upward until its upper front surface comes into engagement with the backing head 30 and thereby the further pressure exerted on the mass by the cover finds its backing on the frame. As soon as the pressure is discontinued and the cover is lifted up, the cover 8 together with its driving mechanism 9, l sink downward as far as the spring 31 permits and the contact between the backing head 30 and the driving mechanism 10 is released.
The last-described embodiment operates as follows:
The movable aggregate assumes alternately the two positions shown in FIGS. and 6. In the operating position of FIG. 5 the compacting takes place through jarring. The cover 8 is lowered onto the carbon mass filling the mold and the jarring begins. During this time the charging container 26 is located under the weighing container 29 which empties its contents into the former. After completion of the jarring process the cover is lifted up, the shell 1 is lowered and the ejector 27 lowers itself to one side of the blank. The movable aggregate travels to the left end of the apparatus into its position shown in FIG. 6 wherein the ejector 27 is shown pushing the blank onto the conveyor 24. The shell 1 and the ejector 27 are again lifted back to their initial position whereupon the charging container is emptied into the mold. The aggregate moves again into its operating position of FIG. 5 and the operating cycle described above repeats itself.
In all the described embodiments the invention provides for a light conicity of the shell 1, such as, 0.1 1 percent. The narrower side of the cone is turned then in the direction in which the shell is removed from the ready blank. The conicity improves the removal of the shell.
The method according to this invention has been shown to exemplify the advantages over known methods in that the jarring table does not have to be vibrated together with the mold shell. As a result the jarring table can be made lighter then if it were to be vibrated together with the shell. Consequently, vibrators with considerably smaller driving capability can be used in accordance "with the invention. Also, since the jarring table and the shell are separate entities with no solid connection between them which could give rise to a fatigue br'eak,- the apparatus according to the present invention is exposed to less wear.
The pressure of the cover 8 can be adjusted as desired.
By'arr'anging the vibrators on the cover and alongside of'the shell,various oscillating frequencies can be produeed to obtain an optimum density of the carbon mass.
The embodiments according to FIGS. 3 and 4 having the freely suspended shell have the additional advantage mar the frictional forces developing between the shell and the carbon mass can be considerably reduced since the shell can assume freely a height as the magnitude of the frictional forces of compaction may require.
The embodiments according to FIGS. 5 and 6 due to the fact that their shell can be removed downwardly, allow for the production of blanks having a conicity similar to blanks made by pure pressing. This is important in the case when the blocks are transferred to and from the baking oven by automatic fangs. In addition,
the several operational steps like filling of the weighing container with subsequent filling of the charging container and the compaction of the blanks can be carried out simultaneously. This considerably increases the capacity of the molding apparatus.
From the above, it is apparent that although the invention has been described hereinbefore with respect I to a specific method and certain specific embodiments for carrying out the method thereof, it is evident that many modifications and changes may be made without departing from the spirit of the invention. Accordingly, by the appended claims, it is intended to cover all such modifications and changes as fall within the true spirit and scope of this invention.
1. Apparatus for compacting a mass, especially artificial carbon mass for use as electrodes in aluminum electrolysis furnaces comprising in combination a mold shell movable in a vertical direction, a stationary bottom member arranged for free jarring movement within said shell and capable of supporting said mass, means for imparting a jarring movement to said bottom member, lifting means operable for moving said shell between a working position and a discharging position with respect to said bottom member, a movable support member arranged for movement in a horizontal direction above said shell between a first position opposite saidshell and a second position away from saidshell, pressure means disposed on said movable support member and expandable in a vertical direction towards the interior of said shell when moved into said first position, a cover member mounted on said pressure means and operable for substantially closing said mold shell at an end thereof opposite said bottom member and arranged for free movement within said shell.
2. The apparatus as claimed in claim 1, further including fixed frame means constructed for surrounding said mold shell and said movable support member and for receiving the force reactions resulting from the operation of said jarring producing and pressure producing means.
3. The apparatus as claimed in claim 1, wherein oscillation jarring producing means are provided and coupled to said cover member.
4. The apparatus as claimed in claim 3, wherein means are provided between said pressure producing means and said cover member for damping the effect of said oscillation jarring producing means on said pressure producing means.
5. The apparatus as claimed in claim 1, said pressure producing means including means for lifting said cover member upward and away from said mass after completion of the compacting process.
6. The apparatus as claimed in claim 1, wherein said lifting means includes means for removing said shell means downwardly away from said mass and below the level of said bottom member.
7. The apparatus as claimed in claim 1, said movable support member including resilient means for mounting said pressure producing means, said resilient means being arranged to move said pressure producing means along an axis transverse to the direction of movement of said movable support member.
8. The apparatus as claimed in claim 2, said fixed frame means including a backing member for translating force reactions from said pressure producing means to said fixed frame means.
9. The apparatus as claimed in claim 1, wherein said movable support member includes a device for pushing said mass after completion of said compacting process and after displacing said mold shell, off from said bottom member, said movable support member also including charging means for charging said mass into said shell means.