EP0203360A1 - Apparatus for compacting and packaging pulverulent air-containing materials - Google Patents

Abstract

In an apparatus for compacting and packaging powdery materials containing air, there is a compacting piston arrangement with a compacting piston 18 which can be moved within a mould frame 14 for the purpose of compressing the powder introduced into the mould frame. The mould frame 14 is equipped with lower walls 40 which are widened conically in relation to the mould bottom (pallet 48) and which are connected rigidly to the adjoining upper cylindrical walls 42 guiding the piston. To release the pressed article surrounded by the lower walls, the mould frame 14 can be moved as a whole in the direction of the piston axis. Because of the conical inclination of the lower walls, there is no fear that this upward movement will cause the pressed article to crumble. <IMAGE>

Description

The invention relates to a device for compressing and packing powdery, air-containing substances, comprising a compression piston arrangement with a compression piston movable between a starting position and a compression position within a mold frame for compacting the powder in a pressing volume, which in the direction of the axis of the piston on the one hand from the piston and on the other is delimited by a mold base and in the radial direction by the mold frame and further comprises a transport device for transporting the press cake formed from the compacted powder and moved out of the mold frame on the mold base to a packaging device for enveloping the press cake with packaging material, the piston and / or the The mold frame and / or the mold base is air-permeable, but is essentially impermeable to the powder and a packaging material web is provided on the mold base that is movable relative to the mold frame, and the press body delimiting lower walls of the mold frame for releasing the pressing body can be moved all the way outward into a release position in which the lower walls have a clear distance from the mold base which corresponds at least to the axial height of the pressing body.

A device of this type is known from DE-OS 31 46 094. Here, the lower walls of the mold frame are connected to the adjoining upper walls via swivel joints with a horizontal swivel axis, in such a way that the lower walls can be pivoted all the way around to the outside to release the pressing body. In this way, the risk of crumbling of the compact when the mold is released from the mold is eliminated, which exists when the compact is conventionally pushed out of the cylindrical mold frame in the direction of the piston axis (e.g. DE-OS 28 10 244).

The object of the invention is to further simplify the construction of the device of the generic type, without the risk of the pressing body crumbling when the pressing body is released from the mold.

This object is achieved in that the lower walls are widened conically in the direction of the mold base and are rigidly connected to the subsequently cylindrical walls that guide the piston, and in that the mold frame as a whole relative to the mold base in the direction of the piston axis away from the mold base the release position is movable.

The mold frame thus now consists of a single rigid part which, in order to release the pressing body, only has to be moved away from the mold base relative to the mold base in the direction of the piston axis. The elimination of the hinges results in an increased reliability of the arrangement, since the sealing problems which may occur in the hinge area and between the other, adjacent edges of the lower mold walls, which are further exacerbated by the presence of powder material, are completely eliminated. Crumbling of the compact is generally not to be feared because, due to the taper, the lower walls at the same time remove radially outwards (and also upwards) from the correspondingly conically shaped compact when the mold frame is lifted. The crumbling strength of the compact is also improved from the outset due to this cone shape.

In the case of a large number of powdery substances, in particular in Neuburg Siliceous Earth, an angle of inclination of the inner sides of the lower walls with respect to the piston axis between 2 ° and 15 °, preferably between 3 ° and 10 °, and best about 5 °, has proven its worth.

The cross-sectional shape of the mold frame (upper walls cylindrical and lower walls flared) can be varied to a large extent. For example, cylindrical shapes with a circular or oval outline are conceivable for the upper walls. However, a rectangular shape is particularly preferred, the lower walls then also having an essentially rectangular outline in cross section perpendicular to the piston axis, which contour increases correspondingly due to the beveling of the lower walls towards the mold base. In order to avoid sharp, crumbling edges of the pressed body, it is proposed that the inner contour mentioned have chamfered or rounded corners. This chamfer continues in the upper walls, so that the piston accordingly has bevelled corners, as is known per se from DE-OS 31 46 094.

In order to accelerate the necessary escape of the enclosed air during the pressing process, it is proposed that the air-permeable piston end wall, which is essentially impermeable to the powder, be connected to an air suction device.

In order to prevent the powder from escaping through a possible gap between the lower walls and the mold base during the pressing process, it is proposed that the lower walls be sealed against the mold base, preferably by means of a profile seal inserted into an end wall groove of the walls.

In order to be able to use the device for different packaging sizes without major conversions, it is proposed that a lower frame part forming the lower wall is detachably attached to an upper frame part forming the upper walls. The lower frame part defining the outer contour and the height of the pressing body can, if necessary, be replaced quickly and easily by a differently shaped lower frame part.

In order to further improve the already mentioned sealing between the mold frame and the mold base, a device for pressing the mold frame against the mold base is proposed.

The pressing process can only be ended when the initially strongly compressed air is removed from the pressing volume. If compressed air were still contained in the pressed body when the mold was loosened, this would lead to a bursting of the pressed body. The work cycle is determined by this relatively long blow-off time. One measure for reducing the blow-off time is the suction of the air by the piston, as already described. In order to be able to abort the pressing process at the earliest possible time, it is proposed to use a pressure sensor for measuring the internal pressure in the pressing volume, which is preferably connected to a control for the piston movement.

In order to rule out damage to the compact during transport when using a roller conveyor, it is proposed that the packaging material web carrying the compact rests on a pallet.

In an alternative embodiment of the invention, instead of the conical designs of the lower walls, it is provided that the powder-side piston end wall is formed from an optionally flat central region, which may form a flat central region, with edge regions which are conically inclined radially outwards towards the mold base, and that Piston guided in the cylindrical mold frame rests in its lowest position on the mold base. The mold frame can then be designed to be continuously cylindrical (e.g. circular, oval or polyhedral outline). Due to the inclination of the edge areas of the piston end wall, it results on the one hand that in the lowest position of the piston with contact with the mold base between the mold bottom and the central region of the piston end wall a pressing volume is formed and on the other hand that when the piston is lifted off the pressing body thus formed, the risk of crumbling of the compact is practically eliminated. The control of the piston is further simplified since it is not to be stopped in an intermediate position (at the level of the transition between the lower walls and the upper walls in the embodiment described above), but rather in its contact position on the mold base. To release the pressing body, the mold frame must of course also be moved away from the mold base in addition to the piston.

In a further alternative embodiment, instead of the conical design of the lower walls, the mold base is now provided with a pressing body receiving trough, the piston guided in the cylindrical molding frame in its lowest position with its powder-side, possibly flat piston end wall, the receiving trough upward completes. The receiving trough can be provided with inclined side walls corresponding to the trough in the piston of the exemplary embodiment just described, which facilitates the molding by lifting the lower packaging material web that is first placed in the receiving trough and then provided with the pressing body.

The subsequent to the pressing process described packaging can be carried out in all the devices just described in the arrangements described in DE-OS 31 46 094. It is also possible to manufacture SKIN packaging in which a heated cover film is shrunk onto the body by vacuum and connected to the perforated underlay film.

Finally, the invention relates to a method for compressing and packaging powdery, air-containing substances with the aid of the devices just described. Many customers of the packaged powder materials use them in precisely predetermined quantities or masses. In order to save the user from having to weigh them, which is often not entirely unproblematic, it is proposed according to the invention that different amounts of powder are introduced into the mold frame in accordance with the powder quantity desired by the customer and pressed together to the same pressing volume. In the processing stages following the pressing process, in particular the wrapping in the packaging material web, pressing bodies of the same shape are then always (albeit ver different weight) to process, which facilitates the processing process. This then results in a different degree of compaction of the pressed bodies of different weights, which, however, essentially does not change the stability, in particular crumbling strength, of the pressed bodies. With silica, the degree of compaction can easily vary between 0.5 and 0.8.

• Fig. 1 einen Schnitt durch eine erfindungsgemäß ausgebildete Abfüll-und Verdichtungsstation;
• Fig. 2 eine Unteransicht des Formrahmens mit Kolben in Fig. 1 (Schnitt nach Linie ll-tt in Fig. 1);
• Fig. 3 bis 5
  eine schematische Darstellung aufeinanderfolgender Arbeitsschritte beim Preßen eines Preßkörpers mit Hilfe der Anordnung gemäß Fig. 1;
• Fig. 6 bis 8
  eine schematische Darstellung aufeinanderfolgender Arbeitsschritte ähnlich den Figuren 3 bis 5 unter Zuhilfenahme einer abgewandelten Abfüll-und Verdichtungsstation und
• Fig. 9 bis 11
  eine schematische Darstellung aufeinanderfolgender Arbeitsschritte unter Zuhilfenahme einer weiter abgeänderten Abfüll-und Verdichtungsstation.

The invention is explained below using preferred exemplary embodiments with reference to the drawing. It shows:

• 1 shows a section through a filling and compression station designed according to the invention;
• Fig. 2 is a bottom view of the mold frame with the piston in Fig. 1 (section along line II-TT in Fig. 1);
• 3 to 5
  a schematic representation of successive steps in pressing a compact with the aid of the arrangement shown in FIG. 1;
• 6 to 8
  a schematic representation of successive work steps similar to Figures 3 to 5 with the aid of a modified filling and compression station and
• 9 to 11
  a schematic representation of successive work steps with the aid of a further modified filling and compression station.

The filling and compacting station shown in FIGS. 1 and 2 is part of a device, not otherwise shown, for compacting and packing powdery, air-containing substances, in which a packing station, e.g. 2 or 3 or Fig. 6 G of DE-OS 31 46 094 follows. Also omitted in FIG. 1 is a preheating container with a pouring trough 11, as indicated in FIG. 3, and the movement mechanism for moving the weighing container away from the area of the mold frame 14 after the powder to be compacted has been fed into the interior 16 of the mold frame 14. This mechanism is just like that appropriate mechanics for the subsequent introduction of a piston 18 retracting into the mold frame 14 of the aforementioned DE-OS 31 46 094, in particular FIGS. 2 and 3.

The molding frame 14 is formed in two parts with an upper frame part 20, to which a lower frame part 22 is detachably fastened, for example via screw connections 24 (not shown in more detail) which fix the outer peripheral flanges 26 of the two parts 20 and 22 to one another. The upper part of the frame consists of vertical walls in a rectangular arrangement with chamfered inner vertical edges. The inner contour shape of the upper frame part corresponds to the outer contour of the piston 18, which can be seen in FIG. 2. In FIG. 1, the narrow surfaces formed by the bevelled edges are designated by 28. The piston 18 has an air-permeable, but essentially impermeable to the powder 12, powder-side piston end wall 30, which, similar to FIG. 5 of DE-OS 31 46 094, can be provided with a gauze cover to prevent the powder from passing through prevent. The piston 18 is hollow. The likewise hollow piston rod 32 connects the piston interior 34 to an air suction device (not shown); the piston interior 34 is closed off at the top by a continuous piston wall 36, so that when the air suction device is in operation, air can be sucked out of the piston interior 34 and thus from the mold frame interior 38 closed off from the piston at the top.

The lower walls 40 of the mold frame 14, which form the lower frame part 22, are flared outwards in a cone shape, starting from the inner contour shape of the upper walls 42 adjoining at the top. The four flat lower walls 40, corresponding to the rectangular inner contour, are each inclined at an angle a from the vertical direction (corresponding to the direction of the piston axis 44). Corresponding to the upper walls, the edges between successive lower walls are also bevelled in the lower walls to form the narrow strips 46 recognizable in FIGS. 1 and 2.

The mold frame 14 lies on a pallet 48 corresponding in size to the lower mold frame outline with the interposition of a packaging material web 50, which is indicated by dashed lines in the figures. A roller conveyor, of which rollers 52 are indicated in FIG. 1, carries the pallet 48 and transports it after the production of the pressed body 62 in the filling and compacting station 10 to the packing station, not shown.

In order to seal the mold frame 14 against the web 50 and pallet 48, a receiving groove 56 for a profile seal 58, in particular a flat rubber seal, indicated in FIG. 1, is in the circumferential lower end wall 54 of the lower frame part 22 lying on the web 50. incorporated. In order to further improve the pressure of the mold frame 22 against the pallet 48 and thus the sealing between the two parts, a device (not shown) for pressing the mold frame 22 against the pallet 48 can be provided, in particular in the form of a corresponding lifting cylinder arrangement.

Finally, a pressure sensor (not shown) for measuring the internal pressure in the interior 38 can be provided in order to control the piston movement.

3 shows the end of the filling phase. The previously precisely weighed powder 12 has been poured into the interior 38 of the mold frame 14 via the filler trough 11 up to a fill level just below the upper edge of the upper frame part 20. Then the trough 11 is moved away and the piston 18 is brought in and into the upper frame part 20 used. The piston 18 is then moved downward (arrow A in FIG. 4) until it assumes its lowest position shown in FIG. 4. In this position, the porous piston end wall 30 is located precisely in the kink region between the upper and lower frame parts 20 and 22. In the case of a compression ratio in the case of Neuburg Siliceous Earth which lies between approximately 0.5 and 0.8, an overpressure in momentarily results in the upper, through the end wall 30, down through the web 50 and to the sides through the lower walls 40 limited pressure volume 60 in the atmospheric area, which, supported by the pumping through the hollow piston rod 32 after some time (e.g. about 90 seconds ) is dismantled. 4, the suction of the air through the hollow piston 32 is indicated by a dashed arrow B. 5, the mold frame 14 is then raised upwards (arrow C) to such an extent that the compact 62 obtained from the correspondingly compressed powder 12 obtained by the pressing process is completely released from the mold frame 14 and moved under the raised mold frame to the next station (movement arrow D) can be. The shape of the pressing body 62 corresponds to the outer circumference of the pressing volume 60 with a horizontal top and bottom and with bevelled flat side surfaces.

In the further embodiment shown in FIGS. 6 to 8, the molding frame 114 is continuously cylindrical (e.g. round, oval or polyhedral outline). According to FIGS. 7 and 8, the pressing volume 160 is now formed by a corresponding bulging of the piston 118. The lower, perforated piston end wall 130 consists of a flat central region 164, from the periphery of which conical edge regions 166 extend, which for example can be oriented in accordance with the lower walls 40 of the mold frame 14 according to FIGS. 1 to 5. At the bottom, the pressing volume 160 is in turn limited by the packaging material web 150 located on a pallet (not shown). The piston 118, like the piston rod 132, can be hollow in order to enable pumping (dashed arrow B in FIG. 7). 6 shows the end of the filling phase corresponding to FIG. 3. The interior 138 of the mold frame 114 is filled with powder 112 to just below the edge. Since, just as in the embodiment according to FIGS. 1 to 5, the compression ratio can be varied within a relatively wide range without the shape stability of the compact being impaired, a lower fill level in the mold frame 114 can accordingly be provided if the quantity of powder desired is lower be.

After the powder 112 has been poured in (direction of insertion arrow D in FIGS. 3, 6 and 9), the channel 111 is removed and the piston 118 is brought in. The piston 118, which is sealed against the continuous inner circumference of the mold frame 114, is then moved downward with compression of the powder-air mixture. In its lowermost position shown in FIG. 7, the piston 118 touches the web 150. When compressing, the molding frame 114 seals the pressing volume 160 against the web 150 with the aid of a seal, corresponding to the seal 58 in FIG. 1.

After the compressed air has been removed from the press volume 160, the press body 162 now formed is dimensionally stable; 5, the piston 118 together with the mold frame 114 can then be lifted upwards (arrow C) to such an extent that the pressing body 162 can be transported away in the direction of the arrow D (FIG. 8).

In the further embodiment of the filling and compacting station shown in FIGS. 9 to 11, the depression defining the pressing volume is not formed in the piston as in FIGS. 6 to 8, but in a mold base 270. The mold trough 272 in the mold base 270 is expediently again provided with conically tapered (widening upwards) side surfaces 274 which facilitate the molding of the finished pressed body 262.

9 again shows the end of the filling phase. The powder 212 fills both the mold trough 272 and the interior 238 of the mold frame 214, the latter being continuously cylindrical in accordance with the mold frame 114 in FIGS. 6 to 8 and being adapted to the outer circumference of the piston 218. The opening cross-sectional area of the mold depression 272 is congruent with the cross-section of the interior 238 of the mold frame 214. Accordingly, the perforated piston end wall 330 of the piston 218 in FIG. 10 closes the lowest position after corresponding compression of the powder 212, sealing the receiving recess toward the top from. In this position, the piston end wall 330 is located at the level of the lower end of the mold frame 214. In order to assist the escape of the air compressed in the press volume 260, air can again be sucked out through the hollow piston 218 and the hollow piston rod 232 (dashed arrow B ).

After the compressed air has been completely extracted, the arrangement of the mold frame 214 and the piston 218 can be lifted up again (arrows C and E), the piston 218 being able to be moved upwards at a higher speed in order to accelerate the cycle. The molding frame 270 is then conveyed in the direction of arrow D to the next station, in which only an upper packaging material web is to be connected, in particular welded, to the web 250 located between the pressing body 262 and the receiving trough 272 along the outer contour of the pressing body 262. For this purpose, the web 250 was placed on the mold base 270 before the powder 212 was filled in.

Claims (13)

Device for compacting and packaging powdery, air-containing substances, comprising a compacting piston arrangement with a compacting piston movable between a starting position and a compacting position within a mold frame for compacting the powder in a press volume, which in the direction of the axis of the piston on the one hand from the piston and on the other hand from a mold base and is delimited in the radial direction by the mold frame and further comprises a transport device for transporting the compact formed from the compacted powder and moved out of the mold frame on the mold base to a packaging device for enveloping the compact with packaging material, the piston and / or the mold frame and / or although the mold base is permeable to air, it is essentially impermeable to the powder and a packaging material web is provided on the mold base which is movable relative to the mold frame, and the lower walls delimiting the press body the mold frame for releasing the press body can be moved all the way outward into a release position in which the lower walls are at least a clear distance from the mold base corresponding to the axial height of the press body, characterized in that
that the lower walls (40) are widened conically in the direction of the mold base (pallet 48) and are rigidly connected to the adjoining upper cylindrical walls which guide the piston 18, and that the mold frame (14) as a whole is relative to the mold base in the direction of Piston axis (44) is movable into the release position. 2. Device according to claim 1,
characterized,
that the angle of inclination (a) of the inner sides of the lower walls (40) with respect to the piston axis - (44) is between 2 ° and 15 °, preferably between 3 ° and 10 °, preferably about 5 °. 3. Device according to claim 1 or 2,
characterized
that the lower walls (40) in cross section perpendicular to the piston axis (44) have a substantially rectangular inner contour with chamfered or rounded corners (strips 46). 4. Device according to one of the preceding claims,
characterized,
that the breathable, but for the powder in essentially impermeable, powder-side piston wall (30) is connected to an air suction device. 5. Device according to one of the preceding claims,
characterized,
that the lower walls (40) are sealed against the mold base, preferably by means of a profile seal (58) inserted into an end wall groove (50) of the walls (40). 6. Device according to one of the preceding claims,
characterized,
that a device for pressing the mold frame (14) against the mold base is provided. 7. Device according to one of the preceding claims,
characterized,
that a lower frame part (22) forming the lower walls (40) is detachably attached to an upper frame part (42) forming the upper walls (42). 8. Device according to one of the preceding claims,
marked by
a pressure sensor for measuring the internal pressure in the press volume (38), which is preferably connected to a control for the piston movement. 9. Device according to one of the preceding claims,
characterized,
that the packaging material web (50) rests on a pallet (48). 10. Device according to one of the preceding claims,
characterized,
that instead of the conical design of the lower walls, the powder-side piston end wall (130) is formed from an optionally flat central region (164) forming the upper side of the compact, with edge regions (166) which are conically inclined radially outwards towards the mold bottom, and that in the cylindrical mold frame (114) guided piston (118) rests in its lowest position on the mold base (Figures 6 to 8). 11. Device according to one of the preceding claims,
characterized,
that instead of the conical design of the lower walls, the mold base (270) is provided with a pressing body receiving trough (272), and that the piston (218) guided in the cylindrical mold frame (214) in its lowest position with its powder-side, possibly flat piston end wall (330) closes the receiving trough (272) towards the top (FIGS. 9 to 11). 12. A method for compacting and packaging powdery, air-containing substances with the aid of the device according to one of the preceding claims,
characterized,
that different powder quantities are filled into the mold frame according to the powder quantity desired by the customer and pressed together to the same pressing volume. 13. A method for compacting and packaging powdery, air-containing substances with the aid of the device according to claim 12,
characterized,
that, in the case of silica or the like, the powder is compressed with a degree of compaction between 0.5 and 0.8, depending on the desired amount of powder.

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