EP0107752A1 - Process and device for producing variable grain size materials from mixtures - Google Patents

Abstract

1. Method of processing old foundry sand, particularly from hot, used foundry moulding mixtures bound with synthetic resin and reinforced with metal parts, which are vibrated on rising surfaces (12, 13), comminuted and coveyed from a higher input region, in the direction of the bottom (8) of a container (2), and then against their own weight on to a higher outlet region (18; 30), the old foundry sand being first comminuted inside the container (2), sifted and/or coarse-screened in the container to obtain fine, oversize and waste products before the material falling through is finely screened and the fine product is discharged from the circuit, characterised in that the oversize and waste products retained in the coarse and fine screening are returned on seperate spiral surfaces (11, 12, 13) to the input region of the container (2) for further comminution and renewed sifting and/or coarse and fine screening.

Description

The invention relates to a method and an apparatus for the production of substances, for. B. of foundry sand, different grain size from mixtures, z. B. from hot, previously used, bonded with resin and reinforced with metal parts foundry molding mixtures that vibrate on rising surfaces, crushed and separated from their gravity by promotion from a lower entrance area to a higher exit area.

In a known method of this type according to DE-OS 27 39 941, the substance mixture reaches a rising surface after a coarse sieving at the bottom of a container through a passage opening in a wall, above which bumpers are arranged at regular intervals to one another and to the inclined surface. The container, the rising surface and the bumpers are vibrated together by a vibration exciter. As a result, the mixture of substances climbs up the ascending surface, being crushed by the bumpers that have the shape of a comb, circulated and finally in an uncontrollable grain size is pressed over the exit area at the end of the rising surface and fed to a device connected to it for further treatment. In addition to a large expenditure on equipment, this method also requires a considerable amount of space, which can amount to a depth of 5 m and a length of 10 m and more from the zero level near the upper edge of the container. To produce the substances from the substance mixtures, several drives which are to be operated independently of one another and correspondingly high operating costs are also required.

Based on this prior art, the invention has for its object to provide a manufacturing method or an apparatus for performing this method of the type mentioned, which are characterized by a lower equipment costs and space requirements and a high efficiency of the crushing and Separation of mixtures of substances into finished products, intermediate products and waste products guaranteed.

This object is achieved in connection with the generic term mentioned at the outset in that the mixture of substances is first crushed in the interior of a container and sifted and / or coarsely screened and then the material which falls through is finely screened, the mixture of substances retained in the latter having oversize particles at the entrance to a helical surface and from there for further crushing as well as new sighting and / or coarse and fine sieving is returned to the entrance area of the container, whereas the material with fine grain size that falls through during fine sieving is withdrawn from the circuit. In this way, on the one hand, the mixture of oversize particles as an intermediate product is subjected to a recirculation process for further comminution and, on the other hand, the substance that falls through during the fine screening with the desired fine grain size is removed as a finished product from the manufacturing process. The invention thus follows a principle that deviates entirely from the prior art. While in the prior art several differently designed shredding sections of different vibrating devices are connected in series, the invention is characterized by a compact recirculation process of the intermediate product, so that in the end result only a finished product with the desired grain size and waste products remain. The process upstream of the fine screening is a mixing process between screening and coarse screening with the aim of reducing the size of the mixture and at the same time restraining mixtures that are well above the oversize. This mixing process, in turn, results in a strong circulation of the mixture of materials and thus a high level of abrasion and, in turn, considerable comminution. For this purpose, the mixture of substances before its coarse screening is advantageous in that with a large upper surface-roughened containers are exposed to strong friction, impact and shock forces.

A compact procedure with little investment is achieved in that the crushing, screening, coarse and fine screening and the separation and conveyance of the individual substances of the mixture of substances in intermediate, finished and waste products in and on the same container with only one vibration exciter is carried out. The intermediate and finished products can be cooled during their passage on the rising surfaces by means of natural or forced convection.

From DE-OS 14 56 805 a device is known with a rotationally symmetrical container to be loaded with mixtures of substances from above, which has a coarse sieve in its interior that extends over its cross-sectional area and is inclined from the center towards the inner wall, and one from the edge of the coarse sieve on the Has inner wall of the container rising internal spiral surface, which leads to the upper edge forming the exit region of the container. This known device is for the sorting of crumbly or brittle goods, for. B. waffles, cookies or confectionery pieces, which are provided with a slightly crumbling coating. This device is therefore only suitable for separating finished products and waste products and for further conveying the finished products out of the container. To carry out a recirculation process this device is not suitable and does not suggest such a device, since it only has the task of correctly feeding finished products into a helical winding ramp, whereby only the finished products are to be cleaned of dust and crumbs. A reduction of substances with this device is even undesirable and the production of an intermediate product from a mixture of substances of different grain sizes is not possible.

Starting from such a device, the problem underlying the invention is solved in that a fine sieve is arranged below the coarse sieve and above the edge line of the fine sieve there is a through opening in the container wall, to which is attached a rising outer spiral surface attached to the outer wall of the container, which connects with it ¢ rem end is guided above the coarse screen through a second through opening into the interior of the container. This creates a device with which a screening and effective reduction and, at the same time, a recirculation process can be achieved for the intermediate product drawn off above the coarse sieve, although this can be achieved by a compact arrangement, but nevertheless by a relatively long one, which is desired because of the comminution effect Path distinguished.

Between the coarse and the fine sieve is a conically inclined towards the middle, with a central one arranged opening funnel, which has both a beating and a guiding function of the falling mixture. Because the fine sieve is advantageously provided on its surface with a guide spiral in the form of a logarithmic spiral, the origin of which is arranged in the region below the central opening of the funnel and the end of which is guided approximately tangentially into the passage opening to the outer spiral. Depending on the number of turns of this guide spiral, the sifted and coarsely sieved material falling through the central opening of the funnel can be guided over a considerable distance on the fine sieve, as a result of which not only a sieving process but also a comminuting viewing process takes place. At the same time, this arrangement desirably increases the throughput of the recirculation process of the intermediate product with a nevertheless compact arrangement before the intermediate product returns to the passage opening to the outer coil and from there to the container space above the coarse screen.

According to an advantageous development of the invention, a closed base plate is arranged below the fine sieve in the container and a second through opening in the container wall is arranged at the edge thereof, which is followed by a second, rising outer spiral surface attached to the container wall, which leads to an exit area for the finished product is led. As a result, the transport route of the finely screened finished product is arranged in a clever arrangement the device is integrated without an additional conveying unit and thus an additional drive with the resulting operating costs being required for the upward conveyance of this finished product, for example into a classifier with subsequent conveyor and silo.

An adjustable tensioning device that tightens the fine sieve is advantageously detachably attached to the closed base plate. The outer spiral surfaces are designed as channels known per se, under the bottom surfaces of which cavities are arranged for heat transfer. Such channels suitable for heat transfer, for example for a cooling process, are known from DE-PS 1 080 927 both in a side-by-side arrangement and in a top-down arrangement.

In contrast, according to an advantageous development of the invention, the inner spiral surface consists of a flat steel, the surface of which is inclined toward the inner wall of the container, for example by approximately 5 °. In terms of conveying technology, this inner helix surface is ultimately only suitable for the upward transport of waste products that are inaccessible to size reduction through screening and coarse screening. Waste products of this type are conveyed out to an exit area via the inner helix surface. With regard to the separation of the mixture of substances, the inner helix also has the function of a comminution or refraction element. For this purpose, the width of the inner spiral surface increases in the direction of it Slope, and it is on its free edge with rough projections, for. B. with the mixture of grinding teeth. As a result, in connection with the oscillation process of the material mixture located above the coarse sieve, strong comminution and refraction on the rough protrusions on the one hand and the protruding edges of the widening inner helix surface on the other hand are achieved during the circulation process.

In order to leave the fine grain constituents adhering to the coarse waste products in the recirculation process, the waste products are cleaned shortly before leaving the container in that the inner helix surface near its exit area from the container is designed as a sieve and in front of it a locking flap which blocks the inner helix surface and can be actuated from the outside is arranged .

To further increase the abrasion and comminution process above the coarse sieve, the latter is designed as an abrasion plate with longitudinal slots running perpendicular to the conveying direction of the material mixture and / or sharp-edged ridges, knobs, crescent-shaped, sharp-edged notches or the like, similar to a grater or rasp.

In order to be able to convey the substance mixture itself into the container without an additional conveying or deflecting device, the container is advantageously designed as a hollow cylinder and above the exit area of the inner and outer spiral surfaces covered by a perforated grate detachably connected to it.

• Fig. 1 die Seitenansicht der erfindungsgemäßen Vorrichtung mit daneben angeordnetem Sichter und Förderer,
• Fig. 2 die Ansicht von Fig. 1 mit einer Schnittansicht durch den Behälter,
• Fig. 3 einen Schnitt nach der Linie III/III von Fig. 2 auf das Feinsieb mit der darauf angeordneten Führungsspirale,
• Fig. 4 eine Draufsicht in Richtung des Pfeiles IV von Fig. 2 auf den Behälter mit dem Grobsieb und der Innenwendelfläche und
• Fig. 5 eine Schnittansicht in Richtung V/V von Fig. 2 auf das geschlossene Bodenblech mit der Durchgangsöffnung zur Außenwendelfläche für das Fertigprodukt.

The method according to the invention is described below using a new device for carrying out this method, which is shown in the drawings. Show:

• 1 is a side view of the device according to the invention with sifter and conveyor arranged next to it,
• 2 shows the view of FIG. 1 with a sectional view through the container,
• 3 shows a section along the line III / III of FIG. 2 on the fine screen with the guide spiral arranged thereon,
• Fig. 4 is a plan view in the direction of arrow IV of Fig. 2 on the container with the coarse screen and the inner spiral surface and
• Fig. 5 is a sectional view in the direction V / V of Fig. 2 on the closed bottom plate with the through opening to the outer spiral surface for the finished product.

According to FIGS. 1 and 2, the new device 1 for carrying out the method according to the invention essentially consists of a cylindrical container 2, in which a coarse sieve 3, a funnel 4 with a central opening 5, a guide spiral 6, a fine sieve 7 and a final bottom plate are arranged with one another 8 are arranged. In the base plate 8, a clamping device 10 for the fine sieve 7, which can be adjusted via the nuts 9, is detachably attached. Furthermore is located on the inner wall 2 'of the container 2, an inner helix surface 11 which rises from the edge 3' of the coarse screen 3 inclined from the center to the inner wall 2 'to the upper edge forming the exit region 2 "of the container 2.

Arranged on the outer wall of the container 2 "'is a first outer helical surface 12 for receiving the oversized grain mixture retained by the fine sieve 7 and underneath a second outer helical surface 13 for accommodating the finished product with fine grain size let through the fine sieve 7. The first outer helical surface 12 conveys and retains the fine sieve 7 from the guide spiral 6 to the outlet opening 14 above the coarse sieve 3 through a second through opening 15 back into the interior of the container 2, this creates from the interior of the container 2 via the coarse sieve 3, the funnel 4 with the central opening 5 and from there A recirculation circuit for the material mixture with an oversize particle size via the fine sieve 7 and the guide spiral 6 and finally via the first outer spiral surface 12. In the present case, an oversize particle size is understood to mean a particle size that is larger than the sieve openings 7 ′ of the fine sieve 7.

Above the base plate 8, a third through opening 16 is arranged in the container wall at its edge 8 '. The second, rising outer spiral surface 13 for the upward conveyance of the fine sieve 7 is connected to this third passage opening 16 let through finished product. This second outer helical surface 13 is provided on its base 13 'with a cavity 17 for the flow of a heat transfer medium. As a result, for example, the finished product picked up by the second outer helical surface 13 can be cooled on the way to the exit region 18, from there into a sifter 19 and finally via a z. B. pneumatic, conveyor 20 in the direction of arrow 21 to a silo not shown.

The container 2 is arranged on a central base 22, to which two vibration exciters 24, spaced 90 ° apart with their longitudinal axes 23, and several feet 27 having supports 26 which are elastic toward the bottom surface 25 are fastened. The vibration exciter 24 can be designed both electromagnetically, electrodynamically and as a resonance oscillator.

The container 2 is covered above the inner and outer helical surfaces 11, 12, 13 by a perforated grating 28 which is detachably connected to it and indicated by dash-dotted lines.

As can be seen from FIG. 3 in connection with FIG. 2, the origin 6 'of the guide spiral 6 consisting of a sheet metal strip is arranged below the central opening 5 of the funnel 4, while the end 6 "of the guide spiral is approximately tangential in the Through opening 14 ends in the container 2, which in turn connects to the first outer helical surface 12.

As can be seen from FIG. 4 in connection with FIG. 2, the inner spiral surface 11 consists of a flat steel, the surface of which is inclined to the inner wall 2 'of the container by an angle α of, for example, 5 °. The width B of the inner spiral surface 11 increases in the direction of its slope and is on its free edge 11 'with rough projections 29, z. B. with the mixture of grinding teeth. In the vicinity of the exit region 30 of the inner spiral surface 11 from the container 2, the spiral is designed as a sieve 31 and in front of it a blocking flap 32 which locks the inner spiral surface 11 and can be actuated from the outside is arranged. For rapid interchangeability, the inner helical surface 11 and the outer helical surfaces 12, 13 are detachably fastened to the container 2 or provided with detachable, not shown wear pads.

As can also be seen from FIG. 4, the coarse screen 3 is designed as an abrasion plate, similar to a grater or rasp. The abrasion effect can be increased on the one hand by longitudinal slots 34 running perpendicular to the conveying direction in the direction of arrow 33 and / or with sharp-edged ridges or knobs 35 and / or with crescent-shaped, sharp-edged notches 36. In principle, any configuration of the coarse sieve 3 is suitable which increases the abrasion effect of the mixture of substances that is constantly circulated by the vibrations. In this respect, the coarse sieve 3 must be considered not only as a sieve device, but also as a viewing device which crushes the mixture of substances.

5 shows the top view of the floor panel S. along the section line V / V of FIG. 2. The finished product located on it is guided by the oscillating and vibrating movements of the device 1 along a guide plate 37 to the third passage opening 16 into the container 2, from where it rises to the second outer spiral surface 13 whose output area 18 and from there is conveyed into the classifier 19.

The new process for producing substances of different grain sizes from mixtures of substances works as follows:

The mixture reaches the interior of the container 2 via the perforated grate 28. Since the container 2 is set into oscillating and vibrating movements by means of the vibration exciters 24, the comminution of the mixture of substances begins at the penetration grate 28 without an additional conveying device for introducing the mixture of substances is required. In the interior of the container 2, the mixture is circulated above the coarse sieve 3 by constant circular and pushing movements and broken at the prong-like projections 29 of the inner helix surface and on the underside 11 "of the helix 11 widening in the direction of the exit area 30. For an additional abrasion provides the coarse sieve 3 with its longitudinal slots 34 as described in Fig. 4, sharp-edged elevations 35 and sharp-edged notches 36, similar to a grater or a rasp. The material mixture falling through the coarse sieve 3 falls on the trimmer 4, from where it passes through the central opening 5 reaches the fine screen 7. The finished product falling through the fine screen 7 reaches the second outer helix 13 via the base plate 8, on which it is conveyed upwards in the direction of the exit region 18 by the vibrations originating from the vibration exciters 24 and from there into the classifier 19. On the way from the third through opening 16 to the exit area 18 of the second outer spiral surface 13, the finished product can be cooled by a heat transfer medium flowing through the cavity 17 at the bottom 13 '. The latter applies, for example, to foundry sand made from a mixture of foundry materials. The oversize material mixture remaining on the fine sieve 7 is conveyed along the guide spiral 6 described in FIG. 3 as long as possible to the first passage opening 14. The guide path effected by the spiral 6 is therefore deliberately designed to be long enough to subject the mixture of oversize particles on the fine sieve 7 to a friction effect on this fine sieve 7. As a result, not only a pure screening process, but also an additional rubbing and therefore screening process is forced. The mixture of oversize particles reaches the second passage opening 15 from the first outer spiral surface 12, from where it returns to the interior of the container 2. This creates a recirculation cycle for the oversized grain mixture. The tensioning device 9, 10 is used for retensioning the fine screen 7.

The waste product not falling through the coarse sieve migrates to that of the edge 3 'of the coarse sieve 3 rising inner spiral surface 11 upwards in the direction of the exit area 30. In the case of a foundry material mixture, for example, the metal parts serving for reinforcement would be conveyed up on the inner spiral surface 11. However, since these metal parts are at least partially reusable, the term "waste product" is not to be taken literally, but to be understood to include substances whose grain size is larger than the largest sieve opening of the coarse sieve 3.

During the comminution process in the interior of the container 2, the blocking flap 32 shown in FIG. 4 assumes the blocking position shown therein. As a result, the exit region 30 of the inner helical surface 11 is blocked. As soon as the coarse components that do not fall through the coarse sieve 3, called waste products for short, are to be conveyed out of the container 2, the locking flap 32 is pivoted in the direction of the arrow 38 according to FIG. 4 and the path from the inner helix surface 11 to its exit region 30 is thus cleared . However, before the waste product conveyed up on the inner spiral surface 11 reaches the exit area 30, it is forced to pass through the sieve surface 31, on which it is cleaned of adhering fine constituents. From the exit area 30, the waste product falls onto the slide 39 indicated in FIGS. 1 and 2 and from there in the direction of the arrow 40 to a designated depot. It is to support the conveying effect of the waste product on the inner spiral surface 11 of advantage if this is inclined at an angle to the inner wall 2 'of the container, so that it forms a groove with the latter despite its flat design. An angle of approximately 5 ° to 10 ° is particularly advantageous.

The new process and the new device are characterized by a particular compactness, a small space requirement and by a high efficiency with regard to the comminution of substance mixtures. In addition, since the entire method and the entire device are operated by only a single vibration source, namely the vibration exciters 24, considerable savings in operating costs can be achieved, which must also be provided for comparable conveyor methods for additional conveying devices.

It goes without saying that the above device also permits various modifications, depending on the type of substance mixture to be treated therein. For example, in the case of a material mixture consisting of only two components, the fine sieve 7 can be replaced by the base plate 8 and the second outer helical surface 13 can cease to exist. In the case of more than three fabric components, however, the device according to the invention also permits the arrangement of a plurality of screens 7, which may possibly be designed like the coarse screen 3, as well as additional outer helix surfaces arranged with one another and next to one another. The angle of inclination of the outer helical surfaces 12, 13, which generally increase in the same direction, can likewise be the grain sizes of the individual Components of the intermediate and finished products are adjusted.

"Method and device for producing substances of different grain sizes from mixtures"

Parts list :

Claims (20)

1. Process for the preparation of substances, for. B. of foundry sand, different grain size from mixtures, z. B. hot from already been used once, bound with synthetic resin and reinforced with metal parts foundry mold material mixtures, the offset on ramped surfaces to vibrate, crushed and ent _- are separated from each other against their gravity by promoting a deeper gelgenen input range to a higher output range, characterized characterized in that the substance mixture is first crushed in the interior of a container and sifted and / or coarsely sieved therein and then the material falling through is finely sieved, the substance mixture with oversize particles retained in the latter being fed onto the entrance of a spiral surface and from there for further comminution and renewed screening and / or coarse and fine screening is returned to the entrance area of the container, whereas the fine grain size material that falls through the fine sieving is withdrawn from the circuit. 2. The method according to claim 1, characterized in that the mixture of substances is subjected to strong friction as well as impact and shock forces before its coarse screening in the container provided with a large surface roughness. 3. The method according to claim 1 or 2, characterized in that the comminution, screening, coarse and fine screening and the separation and promotion of the individual substances of the mixture of substances in intermediate, finished and waste products in and on the same container with only one vibration exciter is carried out. 4. Process according to claims 1 to 3, characterized in that the intermediate and finished products are cooled during their passage on the rising surfaces by means of natural or forced convection. 5. Apparatus for carrying out the method according to claims 1 to 4 with a rotationally symmetrical container to be loaded from above with mixtures of substances, in its interior a coarse sieve extending over its cross-sectional area and inclined from the center towards the inner wall and one from the edge of the coarse sieve of the inner wall of the container has a rising inner helix surface which leads to the upper edge forming the exit region of the container, characterized in that a fine sieve (7) below the coarse sieve (3) and a through opening (14) above the edge line of the fine sieve (7) ) is arranged in the container wall, which is followed by a rising outer spiral surface (12) attached to the outer container wall (2 "'), the end of which extends above the coarse sieve (3) through a second through opening (15) into the interior of the container (2) is performed. 6. The device according to claim 5, characterized in that between the coarse (3) and the fine sieve (7) a conically inclined towards the center, with a central opening (5) provided funnel (4) is arranged. 7. Device according to claims 5 and 6, characterized in that the fine screen (7) is provided on its surface with a guide spiral (6) in the form of a logarithmic spiral, the origin (6 ') in the region below the central opening (5 ) of the funnel (4) and the end (6 ") of which is guided approximately tangentially into the through opening (14) to the outer helical surface (12). 8. The device according to claim 7, characterized in that the guide spiral (6) consists of an upright on the fine screen (7) arranged sheet metal strip. 9. Device according to claims 5 to 8, characterized in that below the fine sieve (7) in the container (2) a closed bottom plate (8) and at the edge (8 ') a third through opening (16) is arranged in the container wall , which is followed by a second, rising outer spiral surface (13) attached to the outer wall of the container (2 '"), which leads to an exit area (18) for the finished product. 10. The device according to claim 9, characterized in that a sifter (19) with a subsequent conveyor (20) and silo are arranged below the exit region (18) of the second outer spiral surface (13). 11. Device according to claims 5 to 10, characterized in that an adjustable, the fine sieve (7) tightening clamping device (9, 10) is releasably attached to the closed base plate (8). 12. Device according to claims 5 to 11, characterized in that the outer helical surfaces (12, 13) are formed as channels known per se, under whose bottom surfaces cavities (17) are arranged for a heat transfer medium. 13. Device according to claims 5 to 12, characterized in that the inner helical surface (11) consists of a flat steel, the surface of which is inclined towards the inner wall of the container by an angle (α), for example by approximately 5 °. 14. The apparatus according to claim 13, characterized in that the width (B) of the inner helical surface (11) increases in the direction of its slope and at its free edge with rough projections (29), for. B. is provided with the material mixture grinding teeth. 15. The apparatus according to claim 14, characterized in that the inner helical surface (11) in the vicinity of its exit region (30) from the container (2) is designed as a sieve (31) and in front of it a locking flap which locks the inner helical surface (11) and can be actuated from the outside ( 32) is arranged. 16. Device according to claims 5 to 15, characterized in that the inner helix surface (11) and the outer helix surfaces (12, 13) releasably attached to the container (2) or provided with detachable wear pads. 17. The device according to claims 5 to 16, characterized in that the coarse screen (3) as an abrasion plate with perpendicular to the conveying direction (33) of the mixture of longitudinal slots (34) and / or sharp-edged ridges, knobs (35), crescent-shaped, sharp-edged notches (36) or dd., Similar to a grater or rasp. 18. Device according to claims 5 to 17, characterized in that the container above the exit area (30, 18) of the inner (11) and the outer spiral surfaces (12, 13) is covered by a detachable grate (29) connected to it . 19. Device according to claims 5 to 18, characterized in that the container (2) is arranged on a central base (22) on which two with their longitudinal axes (23) by 90 ° spatially offset vibration exciter (24) and several , feet (27) having elastic supports (26) toward the bottom surface (25) are fastened. 20. The device according to one or more of claims 5 to 19, characterized in that the container (2) is designed as a hollow cylinder.

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