EP0155537B1 - Device for cleaning semolina - Google Patents

Abstract

In the case of an apparatus for cleaning grits, which has a plurality of superimposed screen layers, which can be vibrated by means of at least one unbalance exciter and with an inlet or outlet for the product inlet or screen discharge arranged at one end, collecting means with adjustable setting flaps for the screenings, as well as an air circulation through the screen layers over an air distribution chamber in a suction collecting channel adjustable by means of adjusting flaps, it is provided that the apparatus is constructed as a stand with a stand head, a stand base and a vertical intermediate support connecting said two parts, the screen layers being constructed as a dust box and being vibratably supported in the vicinity of the stand base, the stand top being formed by the upper air distribution chamber.

Description

The invention relates to a device for cleaning semolina, with vibrating, superimposed screen layers and each arranged on one end inlet or outlet for the product inlet or the screen rejection, and with collecting devices under the screen layers for screen diarrhea and a means Adjustable flaps adjustable air flow through the sieve layers and through an upper air distribution space in a suction channel.

In such devices for cleaning semolina z. B. AT-B-185667 are special machines that are used almost exclusively in grain milling. They are used to sort out semolina and dun and occasionally maize semolina from the product fed to the machine, with the aim of achieving the highest possible yield of clean semolina.

In the case of conventional semolina cleaning machines, the sieve diarrhea was previously thrown from the lower sieve layer directly into the collecting devices. The sifter air sucked in under the lowest sieve layer for cleaning the semolina influences the sieving diarrhea (semolina) trickling down there with regard to its falling behavior. B. a lateral blowing away of the sieve diarrhea, changes in the falling speed, turbulence or the like can occur. An increase in the cleaning performance, which causes an increase in the amount of air sucked in for the flow through the sieve layers, then at the same time leads to an increased disturbance of the falling diarrhea, so that an increase in the performance of the known cleaning devices has narrow limits if one does not make significant cuts in the Would like to accept the quality of the semolina obtained. In addition, the problem-free operation of the known semolina cleaning machines can be influenced noticeably and undesirably by the penetration of disturbing air from the machine environment into the area of the air intake and the trickling of the sieve diarrhea.

Proceeding from this, the object of the invention is now to develop a semolina cleaning machine which, compared to known semolina cleaning machines, permits a further increase in product performance and has an improved immunity to interference from external air disturbances from the machine environment.

According to the invention, this is achieved in a semolina cleaning machine of the type mentioned at the outset in that an oscillatingly mounted floor with a plurality of outlets directed toward the collecting devices is arranged between the bottom sieve layer and the collecting devices, forming a lower air distribution space for air intake.

With the solution according to the invention, a defined lower air distribution space is now created for the first time, and the individual fractions can be derived underneath this space and separated from it by the floor undisturbed. The invention thus enables a functional separation between the air intake and air distribution on the one hand and the collection and delivery of the sieve diarrhea on the other hand, which permits an optimized adjustability of the overall machine and an increase in performance in a wide range with very good grit quality and yield. The air supply on the one hand and the division of the fractions on the other hand are carried out in two spatially separate steps, thereby virtually eliminating the occurrence of undesirable influences from cross-air from the environment or the like.

In a device according to the invention, lateral air intake gaps are preferably formed between the bottom and the sieve layers, which are advantageously in the order of a few centimeters gap width. This can prevent possible interference from the outside, e.g. B. the occurrence of local strong air currents (draft) from the machine environment, be switched off, since these disturbances caused by such air intake gaps are practically no longer effective. In order to ensure the best possible and sharp separation into the individual fractions, in a further advantageous embodiment of the invention, the bottom is designed as an inwardly inclined conveyor trough which has product steering flaps assigned to the outlets in its central lower section. The floor is preferably provided with individual trough-shaped depressions corresponding to the number of product steering flaps, which open out into the outlets and can optionally be steered into different collecting devices by the product steering flaps. In this case, the product steering flaps are preferably designed as chutes that can be tilted about a pivot point. It is particularly advantageous here if the cross section of the outlet opening between the chutes and the floor is smaller than the cross section of the air intake gaps.

Since the air flow searches for the path of least resistance within the machine, a suitable air flow is always ensured in the solution according to the invention, the area of the product discharge remaining free of any disruptive air flow.

The semolina cleaning machine according to the invention is preferably designed as a double machine.

An advantageous embodiment of the invention also consists in the provision of a collecting device which is capable of oscillating in the same direction as the sieve layers and is designed as a double conveyor trough and which is supported so that it can oscillate independently of the sieve layers, which makes it possible for this double conveyor tine to oscillate to choose which does not coincide with the swinging movement of the sieve layers, ie is different from that of the sieve layers vented or directed. It is particularly advantageous if the sieve layers and the bottom are designed as an oscillatable structural unit. This assembly of sieve layers and base is expediently supported on the two end sides so that it can vibrate. The measure already described is particularly advantageous here, namely that the sieve layers and the double vibrating conveyor trough are driven by a common unbalance exciter, which is firmly connected to the sieve layers and whose direction of force can be set. The double vibrating conveyor trough can advantageously be driven by the oscillatable unit via a lever joint in order to increase the oscillation stroke, in that the double conveyor trough can be set in vibration by means of a drive lever and a support from an end support of the sieve layers, the articulation points of this lever both on the end support as on the support to adjust the throwing distance can be changed. As a result, the swing deflection of the double conveyor can be selected independently of the swinging movement of the sieve layers, although this is done with the same unbalance exciter.

The device according to the invention allows a clean guidance of the product as well as an excellent distribution of the air, whereby not only the quality of work, but also the product performance of the device compared to previously known. Semolina cleaning machines can be increased significantly.

In the device according to the invention, the process of diverting the individual sieve diarrhea fractions into the corresponding collecting devices is relocated to a machine area which is completely separate from the area of the incoming working air and the swinging stroke and therefore cannot be undesirably disturbed or influenced by it.

The structure of the stand of a semolina cleaning device of the type mentioned above is further described in the parallel application EP-A-0155 527.

• Figur 1 eine Längsansicht einer erfindungsgemäßen Vorrichtung ;
• Figur 2 den Schnitt li-11 aus Fig. 1 ;
• Figur 2a eine Detail-Prinzipdarstellung für eine gegenüber Fig. 2 geänderte Ausbildung von Schwingboden und Luftzuführung ;
• Figur 3 die kombinierte Abstützung der Sieblagen auf Federn und des Schwingbodens auf einem Hebelgelenk (in prinzip ieller Darstellung) ;
• Figur 3a eine prinzipielle Detaildarstellung eines Abschnitts eines Schwingbodens mit Produktauslässen ;
• Figur 4 eine schematische Darstellung der variierbaren Möglichkeiten einer Kraftübertragung von den Sieblagen an den Schwingboden (Schwingförderrinne) bei einer erfindungsgemäßen Vorrichtung ;
• Figur 5 eine schematische Darstellung des oberen Luftteilraumes bei einer erfindungsgemäßen Vorrichtung, und
• Figur 6 eine Schnittdarstellung durch die Stellschrauben in Fig. 5.

The structure of the suction hood for the air suction system is further described in the parallel application EP-A-0155 556. The invention is explained in more detail below in principle with reference to the drawing. Show it :

• 1 shows a longitudinal view of a device according to the invention;
• Figure 2 shows the section li-11 of Fig. 1;
• FIG. 2a shows a detailed representation of the principle for a design of the oscillating floor and air supply that has been changed compared to FIG. 2;
• FIG. 3 shows the combined support of the sieve layers on springs and the vibrating base on a lever joint (in a basic illustration);
• FIG. 3a shows a basic detailed illustration of a section of an oscillating floor with product outlets;
• Figure 4 is a schematic representation of the variable possibilities of power transmission from the sieve layers to the vibrating floor (vibrating conveyor trough) in a device according to the invention;
• Figure 5 is a schematic representation of the upper air compartment in a device according to the invention, and
• 6 shows a sectional view through the set screws in FIG. 5.

First of all, reference is made to FIGS. 1 and 2, in which (as also in the other figures) a so-called “double machine is shown, which consists of two semolina cleaning machines that are completely separate in terms of working technology, as shown in FIG. These two semolina cleaning machines are arranged on the left and right with respect to a central stand construction.

1 shows an inlet 1 at the top left for the product to be fed to the device and outlet 2 at the bottom right for the screen rejection. Furthermore, three screen layers 3 arranged one above the other are provided, an inner collecting device 4 and an outer collecting device 5 being arranged beneath them (FIG. 2), in which the sieve diarrhea is collected. As a rule, each individual collecting device 4 or 5 has two processes 6 or 7. The sieve layers 3 are combined to form a cleaning box 8 (FIG. 2), so that each cleaning box 8 is assigned two outlets 2 for the screen rejection and four outlets 6 and 7 for the screen diarrhea in accordance with the illustrated embodiment. Each cleaning box 8 is supported by an end support 12 (FIG. 1) via oscillating elements or hollow rubber springs 13 on a stand base 10 of a stand 9 so that it can vibrate. An unbalance exciter 14 is fixedly connected to the end support 12, the direction of impact (cf. arrow 15 in FIG. 1) can be adjusted by rotating the unbalance exciter 14 on a raw cross-connection 1ft. Likewise, what is known can regulate the strength of the unbalance forces by appropriate adjustment of the unbalance weights 17. At the cross connection 16, two unbalance exciters 14 are attached and electrically connected so that they rotate in opposite directions. This eliminates their lateral unbalance components and there is a purely linear longitudinal vibration in the direction of arrow 15. A cover 18 is attached above the unbalance exciters 14, which is designed as part of the vibrating system for structural simplification.

The collecting device 4 is designed as a vibrating conveyor trough, which rests on both end sides on a support 19 mounted in rubber (FIG. 1). The oscillation drive of the collecting device 4 takes place via a lever 20 which connects the oscillating end support 12 to the support 19. Depending on the height of the point of application of the lever 20 on the support 19 (this height can be adjusted), the Vibration stroke of the collecting device 4 can be selected or set independently of the vibration stroke of the cleaning box 8. The stand 9 carries all non-vibrating components directly, the vibrating elements being mounted above the lower part of the stand. The stand 9 also has a vertical support 21 on each end side (FIG. 2), which merges into a foot construction at the bottom via an extension. According to the illustration in FIG. 2, the vertical support 21 extends a little beyond the uppermost sieve position and supports the stand head 11, which essentially forms the upper air distribution space 22. This upper air distribution space 22 has an upwardly tapered shape and is divided over its length by bulkheads 23 into sixteen separate air guiding chambers 24. The bulkheads 23, as can be seen in FIG. 1, are brought close to the uppermost sieve layer, the distance being chosen so that it is somewhat larger than the greatest layer thickness of the material that ever occurs.

The upper inclined surfaces of the air distribution space 22 have transparent windows 25 over their entire length (FIG. 2), so that with an electrical light source from the outside of the device, the flow behavior of the material over the uppermost sieve layer. can be controlled. 5 shows between the upper end of the air distribution space 22 and an exhaust manifold 27 adjusting flaps 28 which, as can be seen in FIGS. 5 and 6, can be adjusted according to the respective air requirement via a head 29.

As can be seen from FIG. 2, between the cleaning box 8 and the drains 6 and 7 there is provided a base 32 which is supported on the stand base 10 and which can oscillate and which has a plurality of depressions 33 with outlets 36 along its length, each of which has a longitudinal product flap at the bottom or chute 34 (FIGS. 2 and 2a) can be aligned with the inner or outer collecting device 4 or 5, so that the screen rejection, depending on the request, can be derived either into one or into the other collecting device below the sieve layers 3 . The number of product longitudinal flaps 34 is preferably selected to be approximately the same size as the corresponding number of air guiding chambers 24. From Fig. 2 it can also be seen that the working air flows through air intake gaps 35 provided on both sides, but which, as shown in Fig. 2a, can also be provided only on the outside of the floors 32. These measures bring various advantages: on the one hand, the guidance of the air flow is completely separate from the product discharge, which is located below each floor 32, where there is no more air flow. On the other hand, the air flowing in from the side causes the product stream falling onto the bottom 32 to be deflected towards the center of the bottom, where the chute 34 is arranged, thus “concentrating” towards the inside. In addition, the product flow has a certain self-cleaning effect in the device. In the prior art, namely, the deflection flaps are mounted directly on the collecting device 4 or 5. whereby one half of the collecting device in question is constantly covered, which leads to the fact that sealed-off dirt corners can form underneath it, which in turn cannot occur in the case of the invention, since there is no cover there. Yet another noticeable advantage of the device according to the invention is that the sieve diarrhea can be divided very precisely into the desired fractions, because disturbing air flows in the longitudinal direction are virtually eliminated.

When the semolina cleaning machine shown is started up, the vibrator is switched on, so that the cleaning box 8, the bottom 32 and the collecting devices 4 and 5 carry out the preselected oscillating movement in the longitudinal direction of the device. Likewise, the entire device is placed in a slight negative pressure via the suction collecting duct 27 or an aspiration associated therewith. Depending on the separation task, all slides and flaps are provisionally adjusted, after which the product can be fed into inlet 1. The product immediately falls on the top sieve layer 3. Due to the shaking movement which is imprinted on the material, as well as through the sieve layers which are deliberately inclined downwards from the inlet 1 to the outlet 2 and the air flow through the sieve layers 3, the product behaves like a liquid (fluidized ). The central task of the semolina cleaning machine lies in the actual sieving process. So the air flow must not be adjusted so much that the entire product layer could be lifted off the sieve layers. Rather, the air primarily serves the function of loosening up the product and distributing it evenly over the entire surface.

Depending on the task, it is required that the product should be fractionated into coarse, medium and fine size or into cooking size and medium size etc. In the second case, e.g. B. the first six chutes can be directed into the collecting device 4, the subsequent eleven chutes into the collecting device 5. In this case, the two sieve passes are finished products that can be delivered to the corresponding storage cells or to the consumers. The screen rejects at the outlets are partially regrinded or crushed and then transferred to a second, appropriately set, grit cleaning machine.

The specific sieve mesh sizes suitable for the respective task must be selected in each semolina cleaning machine.

Once the semolina cleaning machine is in full operation, the miller's actual task begins, namely the assessment of the functioning of the device and the quantitative and qualitative assessment of the fractions obtained.

For this purpose, the light source 26 (FIG. 2) is switched on, so that the entire space within the air distribution space is illuminated. Through the The flow behavior of the product within the individual air guiding chambers 24 can be observed over the entire length of window 25. If an image similar to the boiling water is shown within one or more air guiding chambers 24, the amount of air in the relevant air guiding chambers 24 is throttled via the adjustment flaps 28. Conversely, a congestion can also occur at individual points: here the local air volume must be increased accordingly. If the flow behavior of the product is flawless and if there are no portions in the mixed product (outlets) that belong to sieve diarrhea, the quality of the sieve diarrhea is checked again and the chute 34 is adjusted to the correct collecting devices 4 and 5, respectively.

As can be seen from FIG. 1, two different processes 6 and 7 can be selected from each collecting device 4 or 5, so that four different fractions can be separated from each cleaning box 8.

FIGS. 6 and 6 show an advantageous embodiment with respect to the adjustment flaps 28 used; which are designed as a slide. These sliders allow more precise adjustment of the air requirement in all slider positions. A proportional change in cross-section of the slide opening is caused in accordance with the revolutions of the head 29. If a flap were used instead of a slider, a similar, proportional cross-sectional change would no longer occur here, since in such a case the effective opening cross-section would no longer change in proportion to the rotation of the head 29. The slide solution also has the further advantage that the free cross section of the suction collecting duct 27 is not influenced by the different open positions of the slide.

In the solution according to FIGS. 5 and 6, it has been shown that the suction collecting duct 27 can be designed with a constant cross section in the air flow direction.

In Fig. 3, the support of the vibrating unit is shown on a rubber joint 42, which is embodied by a spring system 40.

The unbalance exciter 14 can, as can be seen from FIG. 1, be rotated about a transverse axis 16, so that the direction of force 41 can optionally be set, as indicated by the arrows in FIG. 3. If the direction of the force action passes through the center of gravity of the vibrating unit, a uniform vibration of the entire sieve stack is generally achieved. However, if the direction of force 41 does not run through the center of gravity, then - depending on the special requirements - an actual vibration can be set in the area of the inlet 1 according to an angle and at the outlet 2 according to another angle.

FIGS. 4 and 4 overall represent a very particularly advantageous exemplary embodiment in principle: the cleaning box 8 is mounted here as an actual cantilever on a spring system 40 or a steel spring 42 so as to be able to oscillate. The unbalance vibrator 14, which is adjustable with respect to the direction of the force action, is fastened to the end support 12 and, by using two counter-vibrating vibrators, brings about an essentially purely linear oscillating movement analogously to the illustration in FIG. 1. The collecting device 4, 5 is independent of the cleaning box 8 on a support 19 swinging mounted. The end support 12 is connected to the support 19 by means of a lever 20, so that the vibrations of the unit which is supported to oscillate transversely via the spring system 40 can be transmitted to the collecting device 4, 5 via the lever 20. The lever 20 can be attached to the support 19 at different heights X1, X2, ... X6 (see FIG. 4). This creates the possibility, starting from the drive of the unbalance vibrator 14, to trigger or force different lateral oscillation deflections of the collecting device 4, 5 via a correspondingly selected and adjustable lever path, as a result of which a surprisingly simply constructed oscillating structure is obtained. The sieve stack performs a short-lived oscillation for the “sieving” task, while the collecting device carries out a long-lasting oscillating throwing movement in accordance with the function of a vibrating conveyor trough, which is supported by the correct articulation of the lever 20 on the support 19. The work result of this combined cantilever lever arm has proven to be surprisingly good.

FIG. 2a shows a shape of the vibrating floor for the left half of a double machine, modified from FIG. 1, in which the lowermost sieve layer 3 is designed with the vibrating floor 32 as a structural unit. The air intake gap 35 is provided only on the outside of the machine (thus in FIG. 2a: left). The lowest of the sieve layers 3 is attached directly to the upper edges of the bottom 32. The lower part of the base 32 converges towards an outlet 36, at which a pivotable chute 34 is arranged, by means of which the goods arriving there can optionally be discharged onto collecting devices (not shown) arranged underneath.

The detail section of FIG. 3a shows an enlarged section of the device from FIG. 3 in the area of the oscillating floor. Here, a plurality of trough-shaped outlets 36, which are arranged next to one another, are shown at the bottom of the oscillating floor 32, to each of which a chute 34 is pivotally attached in the manner already described. Above the outlets 36, the air intake gap 35 is shown, which extends over the entire length of the bottom 32.

Claims (9)

1. An apparatus for cleaning semolina, the apparatus comprising : vibratable screen layers (3) disposed one above another ; a product entry (1) at one end and an oversize discharge (2) at the other end ; collecting means (4, 5) below the screen layers (3) for the undersize ; and an air passage which is adjustable by means of flaps (28) and which extends through the screen layers (3) and by way of a top air distribution chamber (22) into an extraction main (27), characterised in that an oscillatable base (32) formed with a number of outlets (36) directed towards the collecting means (4, 5) is so disposed between the bottom screen layer (3) and the collecting means (4, 5) as to bound a bottom air distribution chamber (22') for air intake.

2. An apparatus according to claim 1, characterised in that lateral air intake gaps (35) are present between the base (32) and the screen layers (3).

3. An apparatus according to claim 1 or 2, characterised in that the base in an inwardly inclined conveying through (32) having in its central bottom part product-deflecting flaps (34) associated with the outlets (36).

4. An apparatus according to claim 3, characterised in that the base (32) is formed with discrete through-like recesses (33) to the number of product-deflecting flaps (34), the recesses (33) extending into the outlets (36) and being empti- able at choice into different collecting means (4, 5) by means of the product-deflecting flaps (34).

- 5. An apparatus according to claim 3 or 4, characterised in that the product-deflecting flaps are in the form of chutes (34) each tiltable around a pivot.

6. An apparatus according to claims 1-5, characterised in that the screen layers (3) and the base (32) are an oscillatable unit.

7. An apparatus according to claim 6 having an eccentric mechanism (14) to oscillate the screen layers (3), characterised in that the screen layers (3) and the base (32) are rigidly connected to the mechanism (14) and the direction (41) in which the force of the mechanism (14) is operative is adjustable.

8. An apparatus according to any of claims 1-7, characterised in that collecting means oscillatable in the same direction as the screen layers (3) and taking the form of a double conveying through (4, 5) are provided and are borne independently of the screen layers (3).

9. An apparatus according to claim 8, characterised in that the double conveying through (4, 5) is oscillatable from an end support (12) of the screen layers (3) by way of a driving lever (20) and a support (19), the places where the lever (20) is pivoted to the end support (12) and to the support (19) being variable for adjustment of the eccentric throw.

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