SCHUMACHER, Wilfried (Mausweg 115, Elsdorf, 50189, DE)
SCHMITT, Monique (Barbarastr. 44, Koln, 50735, DE)
NAGEL, Hardy (Bitterfelderstr. 2, Bruhl, 50321, DE)
SCHUMACHER, Wilfried (Mausweg 115, Elsdorf, 50189, DE)
SCHMITT, Monique (Barbarastr. 44, Koln, 50735, DE)
| Vibrating machine for producing molded bodies by means of compacting C l a i m s 1 . A vibrating machine for producing molded bodies by means of compacting granular raw mixtures, in particular for producing anodes and/or cathodes for the electrolytic smelting process to produce aluminium, said vibrating machine having a vibrating table (10), which is mounted on springs so as to be able to oscillate, onto which a molding box (12), where applicable with cover (15), can be placed and clamped, and once the raw mixture has been filled into the molding box, a cover weight (13) can be introduced into the molding box, wherein the clamping device is produced by at least two clamping closures which are arranged at the sides outside the molding box (12) and in each case include the components - pivot bracket (17), double- acting hydraulic pivot cylinder (18), two-armed rocker arm (19) and resilient element (20), characterized by the following features of the clamping closure: a) the pivot bracket (17), which is pivotally mounted by way of the lower end thereof on the vibrating table (10), has on the upper end thereof a cranking (21 ) which is directed outward and faces away from the molding box (12) b) at a spacing below the cranking (21 ) of the pivot bracket (17), the two-armed rocker arm (19) is pivotally connected to said pivot bracket, wherein the rocker arm has an inner part (19a) that cooperates with the molding box/the cover and an outer part (19b), with which the piston rod (22) of the double-acting hydraulic pivot cylinder (18) pivotally mounted on the vibrating table (10) cooperates a compression spring (20) is inserted in the space between the cranking (21 ) of the pivot bracket (17) and the top side of the outer part (19b) of the two-armed rocker arm (19), said compression spring releasing the rocker arm (19) from its position closing the clamping closure when the pressure in the hydraulic pivot cylinder (18) is relieved. The vibrating machine as claimed in claim 1 , characterized in that the compression spring (20) is a mechanical spring of short design and/or is produced from resilient material and/or is a pneumatic rubber pad spring / air bellows spring with, where applicable, modifiable spring constants. The vibrating machine as claimed in claim 1 , characterized in that the pivot bracket (17), below the joint thereof for the two- armed rocker arm (19), has a stop member (23) for the rocker arm outer part (19b) directed outward in the direction of the pivot bracket cranking for defining the rocker arm pivot angle when the clamping closure is opened. The vibrating machine as claimed in claim 1 , characterized in that the inner part (19a) of the two-armed rocker arm (19) has at the end thereof, when seen in cross section, a nose-shaped projection (24) which engages in a corresponding recess (25) of the molding box/ the cover (15) placed in position thereon in the closed position of the clamping closure. |
D E S C R I P T I O N
The invention relates to a vibrating machine for producing molded bodies by means of compacting granular raw mixtures in a vibratory manner, in particular for producing anodes and/or cathodes for the electrolytic smelting process to produce aluminium, said vibrating machine having a vibrating table, which is mounted on springs so as to be able to oscillate, onto which a molding box to be filled in each case with a raw mixture charge can be clamped by means of clamping closures as claimed in the preamble of claim 1 . In the case of vibrating machines of the abovementioned type, a charge of a hot mixture that is produced from petroleum coke and pitch as binding agent poured in the molding box that is to be fastened on the vibrating table is molded by means of vibratory compacting to form an anode block, namely to form the so-called raw green anode which is then baked in a furnace. In this case, the density and height of the block anode to be molded are subject to narrow tolerance limits. Once the molding box has been filled with the raw mixture charge, a cover weight is introduced, as a rule, into the molding box, said cover weight impacting or stamping at a certain impact frequency and impact intensity from above onto the mixture to be compacted. A fixed cover or vacuum cover, which surrounds the cover weight, is placed onto the top side of the filled molding box. Once the block anode has been molded in the space between the top side of the vibrating table and the bottom side of the cover weight, the system of molding box/cover/cover weight, which is mounted so as to be able to oscillate and is exposed to the vertical oscillations of the vibratory drive, is lifted up from the vibrating table after the drive has been switched off and the pre-molded green block anode is pushed off the top side of the vibrating table to the side.
The fastening or clamping of the system of molding box/cover to the vibrating table, which can exert vertical oscillations at an amplitude of, for example, 4 to 5 mm during the vibrating operation, is exposed to enormous loads. As evidenced by the publication TMS published by Barry J. Welch of the Minerals, Metals & Materials Society, on the occasion of the 127th TMS Annual Meeting, San Antonio, Texas held on 15th - 19th February 1998 a lecture/paper by authors M. Beilstein and M. Spangehl was published, pages 746 and 747 of which showing a vibrating machine, the molding box and cover of which are to be detachably connected to the vibrating table by means of two clamping closures which are arranged at the sides opposite each other outside the molding box, in the following manner:
The known clamping closures are essentially assembled from the four components of pivot bracket, double-acting hydraulic pivot cylinder, two-armed rocker arm and resilient element. The pivot bracket which is pivotally mounted by way of its lower end on the vibrating table stands upright in its closed position. A two-armed rocker arm is pivotally connected to the upper end of the pivot bracket, the inner part of said rocker arm then pressing onto an outer part of the molding box or of the cover placed in position thereon, when the piston rod of the double-acting hydraulic pivot cylinder is extended and presses from underneath against the outer part of the two-armed rocker arm. In order to hold the clamping closure securely in the closed position thereof, it has been known to allow the inner part of the two-armed rocker arm to lock on the molding box or on the cover thereof. To release the clamping closure it is necessary to move the rocker arm out of its locking position by means of its own retaining mechanism and to pivot the pivot bracket outward away from the molding box at an angle to the vertical, the piston rod of the associated hydraulic pivot cylinder being retracted in the open position of the clamping closure. The rocker arm retaining mechanism has been realized up to now by a long steel spiral tension spring which is arranged between pivot lever and associated hydraulic pivot cylinder, the upper end of which tension spring cooperates with the outer part of the two-armed rocker arm. It has been shown, however, that the oscillations, introduced by means of the vibratory drive and the vibrating table into the system of the vibrating machine that is held so as to be able to oscillate, can pass into the characteristic frequency range of the long tension springs, as a result of which strong oscillations are transmitted to the clamped tension springs and these can impair the service life of the tension springs.
The object underlying the invention is to create a clamping closure for a vibrating machine of the aforementioned type for clamping the molding box including cover on the vibrating table, it being possible to open and close said clamping closure in an operationally reliable manner and, even at varying excitation frequencies, the components of said clamping closure withstanding the high forces and vibratory stresses introduced by means of the vibrating table.
This object is achieved as claimed in the invention with a vibrating machine with the features of claim 1 . Advantageous developments of the invention are provided in the sub claims. In the case of the vibrating machine as claimed in the invention, the clamping closure has in each case a pivot bracket, which is pivotally mounted by way of the lower end thereof on the vibrating table and has on the upper end thereof a cranking which is directed outward and faces away from the molding box. At a spacing below the cranking of the pivot bracket, a two-armed rocker arm is pivotally connected to the pivot bracket and has rocker arm inner part and rocker arm outer part. In the closed position of the clamping closure, where the pivot bracket stands approximately upright, the rocker arm inner part cooperates with the molding box or with the cover placed in position thereon and depresses it by the piston rod of a double-acting hydraulic pivot cylinder, which is also pivotally mounted on the vibrating table, being extended and pressing from underneath against the rocker arm outer part. A short, compactly designed compression spring is inserted in the space between the cranking of the pivot bracket and the top side of the rocker arm outer part, said compression spring releasing or tipping the rocker arm out of its position closing the clamping closure when the pressure in the hydraulic pivot cylinder is relieved.
The use of the short-design compression spring excludes the risk of the vibrating table oscillation excitation frequencies overlapping in an unwanted manner with the characteristic frequency range of the compression spring, as a result of which the long service life of the com- pression spring and correct functioning of the opening and closing process of the clamping closure are ensured.
The compression spring of the clamping closure can be a mechanical spring, a spring produced from a material with elasticity of compres- sion or a pneumatic rubber pad spring such as, for example, an air bellows spring with, where applicable, modifiable spring constants. At any rate, such compression springs are able to withstand the high os- cillation stresses introduced by means of the vibrating table during the vibrating operation.
As claimed in a further feature of the invention, in the case of the clamping closure the pivot bracket, below the joint thereof for the two- armed rocker arm, can have a stop member for the rocker arm outer part directed outward in the direction of the pivot bracket cranking for defining the rocker arm pivotability when the clamping closure is opened. The stop member defines the opening angle of the clamping closure in the open position thereof. For the secure clamping of molding box and cover on the vibrating table during the entire vibrating operation, the inner part of the two-armed rocker arm of each clamping closure has at the end thereof, when seen in cross section, a nose-shaped projection which engages in a corresponding recess of the molding box / the cover placed in position thereon in the closed position of the clamping closure.
The invention and the further features and advantages thereof are explained in more detail by way of the exemplary embodiment repre- sented schematically in the drawing.
The drawing shows a vertical section of the vibrating machine as claimed in the invention with two particular clamping closures shown in side view, of which the left-hand clamping closure is shown in the closed position and the right-hand clamping closure is shown in the opened position. The clamping closures are fastened on the vibrating table 10, which is mounted so as to be able to oscillate by means of springs 1 1 , the vibrating oscillating drive connected to the vibrating table 10 with the rotating unbalanced shafts thereof having been left out.
The vibrating machine serves for the molding of anode blocks produced from granular raw mixtures. To this end, a molding box 12, which is open at the bottom and at the top, for example having a rectangular cross section, is placed onto the vibrating table 10, said molding box is filled with a charge of the raw mixture to be compacted, after which a cover weight 13 is introduced into the molding box 12, said cover weight being guided by at least one guide rod 14, which is guided through an opening in a fixed cover 15, which is placed onto the top side of the molding box 12 and closes said molding box from above like a cover. With the vibrating machine in operation, in the space between the top side of the vibrating table 10 and the bottom side of the cover weight 13, utilizing the impact energy of the cover weight 13 that stamps from above at a certain impact frequency, the raw mixture charge is vibrocompacted to form the anode block 16, which has reached its particular density and height dimension after a certain period of vibration, after which the vibrating operation is switched off, molding box 12, cover 15 and cover weight 13 are removed upward and the anode block 16 is pushed off the top side of the vibrating table 10 to the side.
The at least two clamping closures, which are arranged opposite each other at the sides outside the molding box, are in each case essentially assembled from the four components of pivot bracket 17, double-acting hydraulic pivot cylinder 18, two-armed rocker arm 19 and compression spring 20. The pivot bracket 17 is pivotally mounted by way of the lower end thereof on the vibrating table 10 and in the closed position of the clamping closure it stands approximately upright (on the left-hand side of the molding box in the drawing). On the upper end thereof, the pivot bracket 17 has a cranking 21 which faces outward away from the molding box 12. At a spacing below the cranking 21 of the pivot bracket 17, the two-armed rocker arm 19 is connected to the bracket 17 by means of a pin joint, said rocker arm having an inner part 19a that cooperates with the outside of the cover 15 placed in position and an outer part 19b, with which the piston rod 22 of the hydraulic pivot cylinder 18 cooperates.
The compact compression spring 20 is inserted in the space between the cranking 21 of the pivot bracket 17 and the top side of the outer part 19b of the two-armed rocker arm 19, said compression spring detaching the rocker arm 19 from its position closing the clamping closure when the pressure is relieved from the hydraulic pivot cylinder 18 with the retracting of the piston rod 22 (on the right-hand side of the molding box in the drawing).
The vibrating oscillations introduced by means of the vibrating table 10 during the vibrating operation, the amplitudes of which can be within a range of approximately 4 to 5 mm, are absorbed by the clamping closures used as claimed in the invention by way of the compression springs 20 thereof without damaging the same.
As can also be seen from the drawing, the pivot bracket 17, below the joint thereof for the two-armed rocker arm 19, has a stop member 23 for the rocker arm outer part 19b directed outward in the direction of the pivot bracket cranking 21 for defining the rocker arm pivotability when the clamping closure is opened, demonstrated on the right-hand side of the moulding box 12 in the drawing. It can also be seen that the inner part 19a of the two-armed rocker arm 19 has at the end thereof, when seen in cross section, a nose-shaped projection 24 which, in the closed position of the clamping closure, engages in a corresponding recess 25 in the outside of the cover 15 placed in position, thereby strengthening the clamping of the oscillating unit that is subjected to the vibratory movements on the vibrating table during the vibrating operation.