EP0694341B1 - Device for cleaning screens - Google Patents

Abstract

The sieve box (1) and sieve frame (3) have matching strip dividers (12') pref. for a two-side fines discharge. The sieve frame can have additional transverse dividers (13) forming several fields, and a corresp. number of cleaning elements (6) are provided. The sieve frame pref. has the lowest possible height and is designed as a freely interchangeable insert frame, typically of metal. The sieve box can be made of wood forming an outer frame with 1 to 3 ducts. The surfaces, contacting the prod. are coated with plastics, and the base plate of the box can be made of metal or plastics. <IMAGE>

Description

The invention relates to a device for cleaning Seven, especially the sieves of plan sifters in mills, which in a sieve box with base plate and fine material discharge as well as an insert sieve frame as freely movable cleaning elements act.

A plansifter, especially the large plansifter or square plansifter, is a large cube shape with large flat elements and is a special separating device which is characteristic for the sighting of shot, semolina and flour-like products in milling technology, and for sorting different types of grains such as Wheat, rye, corn, barley, etc. is used.

With many separation techniques, for example in chemical process engineering, it is known the product moisture, if required to reduce so that the separators do not clog. In contrast, for processing from grain products, to flour, semolina, haze etc., Optimal grinding moisture should be sought Because repeatedly ground and sifted in a grain mill the moisture depends on the grinding and not for the best possible visual effect.

It is known that many grinding fractions because of the high humidity poor flow behavior or visual behavior have, as in connection with the flour sieves can also be experienced in the domestic kitchen.

In a plansifter all possible sizes of mesh sizes are shown used from the finest, for example 80 Micron to the coarsest. The same applies to everyone, without any sieve mesh clogging, the maximum visual performance to reach. It must have the greatest possible throughput as well the highest possible quality of the ground products can be achieved be. In contrast to the classic screening technique, the a closed view over the fabric covering Maintain product layer of up to several centimeters. This ensures that the finer, heavier parts a greater pressure down (gravity) acts against the fabric, which means a higher throughput or brings more screening performance. In contrast, more should flat shell parts as coarse material with the layer as sieve rejection swim above. This kind of "thick-film sighting" brings greater difficulties with the wet products and brings with it a strong tendency to screen fabrics to clog.

Over the past 100 years, systematically more powerful ones have been created Plansifter developed and screen cleaning constantly improved. He became innumerable variations of forms and materials tested and partly used in practice. Few forms have been preserved in large-scale plans interestingly for the screen fabric cleaning 5 - 10 centimeter long textile belt pieces with a metal button in the middle, the most widespread. The Sieve cloth cleaners are placed individually between the sieve cloth and inserted or locked a support grid. The bottom of the sieve frame is therefore with a Metal mesh covered, which is the job for the screen cleaner represents. The metal grid usually has one slight ripple so that the metal button from the metal grille receives strong impacts. The strap piece gets through the swinging or circular movement of the whole Plansifters a rattling and noise-generating intensive hiking movement. This way you keep the mesh openings with the frayed ends of the strap pieces free, respectively clean. Have the metal grille and the metal button an important function for the movement of the screen cleaner. The movement also creates a disadvantage as a disadvantage audible noise. There are also screen cleaning pieces out Plastic in various forms known in the same Work wisely.

Another problem in plansifters is the complete one Keep the base plate clear. What has fallen through the sieve mesh Fines (diarrhea) should be as low as possible Dwell time cleared from the bottom plate and through side slots are discharged. Here too, a separate category of cleaning elements, the so-called floor cleaners developed. Common shapes are triangular and quadrangular, Rhombus or polygon shapes.

Many factors influence the way the plansifters work. This is how a freshly covered sieve frame works better, because not only the wear of the covering but also the degree of tension of the screen fabric is important. The experience shows, however, that a plansifter is in excellent condition, natural performance limits are set. The intensity too the swinging motion, i.e. the maximum acceleration is limited, on the one hand by maximum permissible forces in the plan sifter housing, on the other hand also from the movement behavior of good. Impede excessive acceleration forces the free flow of the goods. Accelerating forces too strong hinder the free flow of the goods. Each according to the specific quality of the individual visual fractions given the performance data.

In a mill, the plan sifter is the machine that relates cleaning requires the greatest effort. In newer ones Time is increasingly important that the processing machines as self-cleaning as possible, if necessary but are easy to clean with little effort.

The sieve frames of plansifter sieves have a smooth today Floor on which the freely movable floor scraper lie on. Between the floor and the covering of the sieve are usually corrugated grids or support grids for support arranged by cleaning elements. But from EP-A-330 846 are already Corrugated grid-free designs are known.

The cleaning elements can e.g. braided strap material, which on the underside is provided with a metal button and the when moving over the corrugated mesh start to vibrate so that it is slightly against the wire mesh beat and clean them like this. This also causes a significant one Noise level.

However, other forms of cleaning elements are also known, such as Screen cleaner in the form of simultaneous triangles (US-PS 2086199) u. Like. According to EP-A-330 Such screen cleaners can also be used with 846, without the use of corrugated mesh Have the basic shape of a three-armed star and are made of elastic material. Furthermore, these screen cleaners are supported with a stem-like foot tiltable on the smooth sieve bottom. Through the cantilevered arms of the star becomes a high moment of inertia with a relatively low total weight reached during the tilting movement, so that sufficiently violent blows on the Screen covering can be exercised. The arms of these screen cleaners are with depressions provided that clog quickly and an additional cleaning effort require.

The invention was based on the object, a device for cleaning of sieves, especially the sieve frame - so-called sieve cleaners - see above to design that the disadvantages of the prior art described avoided be, the handling and especially the cleaning performance as well as the self-cleaning of the screen cleaner should be improved.

The solution according to the invention is characterized in that the arms of the screen cleaner have a square cross-sectional shape with a roof-shaped elevation.
This roof-like elevation in turn has a triangular cross section.

Knowledge of the solution according to the invention is also known Obvious advantages. The roof-shaped elevation of the arms prevents ground material from sticking to the screen cleaner (Sanitation) and also improves cleaning performance. Furthermore, the bending behavior of the arms can Adapted to requirements and kept constant. This alone shows that such a solution is not obvious the previous development of screen cleaners, which cannot be compared recognize simple and reliable solutions leaves.

The screen cleaner is lying on the base plate in the Clear fields can be inserted. The screen cleaner is with a wobble foot provided, which is preferably made of non-metal material is made in the area of the vertical axis of gravity the screen cleaner is arranged for the purpose that due to the corresponding wobbling movements a permanent one Alternation of screen fabric cleaning and floor clearing takes place.

According to a first embodiment, the screen cleaner is a Boomerang with two cantilever arms, which after have the above cleaning agents for the screen fabric, preferably on the screen cleaner, opposite to a floor and slot clearing nose are arranged on the projecting arms becomes.

According to a second embodiment, it has three arms, with detergent on at least two arms are arranged for the screen cloth, and one arm one after has elongated bottom and slot clearing nose on the outside.

According to a further embodiment, it is 4-armed, wherein at least one arm has an elongated bottom and Has slot clearing nose.

With all configurations, however, it is very important that he made of resilient material, preferably plastic is made without metal. This ensures that at every impact of an arm on the side parts of the sieve box or on the web strips, via the corresponding spring force, the screen cleaner is thrown in any direction becomes. Through correspondingly continuous movements, with inclusion the wobble, statistically speaking, each Lot, be it the base plate or the screen mesh, with cleaned with great frequency. Even the smallest quantities of fine goods are carried away. The screen cleaner should be chosen as large that it has a certain mass and with its largest horizontal dimension more than 50% of the corresponding smallest dimension of the individual clearing fields. A optimal cleaning effect has also been found in all tested Shapes emerge when the clearing fields formed in the floor plan if possible have a square shape, because then the Optimally clean screen cleaner in really all directions or quickly clear out the product.

The previous optimal function arose when the arms have a cross section with a roof-shaped cant, with the top up and the broad part down. This supports not just the product movement over the bottom plate, but helps that the screen cleaner itself without product buildup stays clean. The arms preferably point upwards various cleaning agents such as bristles or knobs and / or cleaning ribs. The floor cleaning takes place optimal if a sliding foot is only arranged on one arm becomes.

The screen cleaner should be built a little lower than that free height between the floor and the screen covering. In order to nevertheless the bottom and screen fabric are processed in the same way, is the screen cleaner in the middle area with a wobble foot provided so that the extreme ends of the arms next to the horizontal movement of the screen cleaner above the floor a constant interplay of up and down movements, up and down, edit both levels.

Another particularly advantageous embodiment lies in that the arms at their extreme ends with a Baffle head made of plastic. On the one hand, this serves as protection for the fabric detergent in the form of On the other hand, pimples or brushes make it possible low design of the screen frame, and it supports the Jumping movement of the screen cleaner so that the element does not Takes damage.

The invention finds particular application in one application Plansifter, whose housing has several sieve stacks, which each from a larger number of sieve boxes with base plates, Sieve frames and sieve channels exist and a have a rectangular or square shape, the with Sieve mesh covered sieve frame in relation to the sieve box are interchangeable and the sieve boxes above the base plate free diarrhea and product discharge areas together with the sieve frames form, in the screen cleaner, on the flat bottom plate lying on top, can be inserted, the sieve frame are designed to be rust-free to reduce the sound pressure from the source noise.

After it had not been possible until now, the noise of a large plansifter has been surprisingly significantly reduced a noise level in a plan sifter according to the invention of just over 72 dB (A), compared to 84 dB (A) with comparable plansifters of the prior art. An important measure is the choice of the special one Screen cleaner preferably made of non-metal material and the Sieve frame without the previous metal support gratings for the screen fabric cleaners seen. There are no more relative movements from metal to metal.

In the following, the invention will be explained using exemplary embodiments spelled out with further details.

Fig. 1

einen Siebrahmen in einer Auflegebewegung auf einen Siebkasten ;

Fig. 2

ein Grundriss eines Siebkastens mit eingelegtem Siebrahmen, teilweise ohne Siebgewebe ;

Fig. 3

einen Schnitt a - a der Figur 2 ;

Fig. 4

einen Schnitt b - b der Figur 2 ;

Fig. 5

einen einzelnen Einlege-Siebrahmen ;

Fig. 6

einen Schnitt c - c der Figur 5, wobei mehrere Einlege-Siebrahmen gestapelt sind ;

Fig. 7

einen Stapel von Siebkasten mit Auflegebewegung des obersten Einlege-Siebrahmens ;

Fig. 8

einen Grossplansichter mit eingebautem Siebstapel ;

Fig. 9

zeigt einen Siebreiniger mit Bumerang-Form im Grundriss :

Fig. 9a

eine Ansicht gemäss Pfeil a ;

Fig. 9b

eine Seitenansicht gemäss Pfeil b und

Fig. 9c

den selben Siebreiniger im Einsatz bei der Schlitzreinigung ;

Fig. 10

zeigt einen 3-armigen Siebreiniger im Grundriss

Fig. 10a

den 3-armigen Siebreiniger bei der Schlitzreinigung

Fig. 10b

einen Schnitt J-J der Figur 10 ;

Fig. 10c

einen Schnitt H-H der Figur 10 ;

Fig. 11

zeigt einen 4-armigen Siebreiniger im Grundriss in einer Eckreinigungsposition ;

Fig. 11a

in einer Reinigungsposition im Schlitz- sowie am Siebgewebe ; und

Fig. 11b

in Siebreinigungsposition.

Show it :

Fig. 1

a sieve frame in a laying motion on a sieve box;

Fig. 2

a floor plan of a sieve box with an inserted sieve frame, partly without sieve fabric;

Fig. 3

a section a - a of Figure 2;

Fig. 4

a section b - b of Figure 2;

Fig. 5

a single insert screen frame;

Fig. 6

a section c - c of Figure 5, wherein a plurality of insert screen frames are stacked;

Fig. 7

a stack of sieve box with laying movement of the top insertion sieve frame;

Fig. 8

a large plan sifter with built-in sieve stack;

Fig. 9

shows a sieve cleaner with boomerang shape in the floor plan:

Fig. 9a

a view according to arrow a;

Fig. 9b

a side view according to arrow b and

Fig. 9c

the same screen cleaner used for slot cleaning;

Fig. 10

shows a 3-arm screen cleaner in the floor plan

Fig. 10a

the 3-arm screen cleaner for slot cleaning

Fig. 10b

a section JJ of Figure 10;

Fig. 10c

a section HH of Figure 10;

Fig. 11

shows a 4-arm screen cleaner in the floor plan in a corner cleaning position;

Fig. 11a

in a cleaning position in the slit and on the screen mesh; and

Fig. 11b

in screen cleaning position.

In the following, reference is now made to FIGS. 1-4. A sieve box 1 has several discharge channels, two discharge channels for the screen rejection, or for the coarse goods, 2A and 2A 'and a discharge channel 2F for the sieve diarrhea or the fine goods.

A screen frame 3 is drawn in Figure 2 in a slightly inclined position and provides a laying movement of the sieve frame 3 on the sieve box 1. The inner surface of the sieve box 1, below the sieve frame, is with a flat bottom plate 4 closed so that the fine goods respectively the sieve diarrhea only through side slit openings 5 from the bottom plate 4 can be cleared (Figure 3). On the Bottom plate 4, screen cleaners 6 or 6 'are already placed, before the sieve frame 3 is inserted. The screen cleaners 6, respectively 6 'have a double function, with a scraper foot 7 should the sieve diarrhea on the flat base plate 4 be cleared. According to the example in FIGS Fine material is only discharged via the discharge channel 2F, so that Fine goods in a corresponding longitudinal direction arrow 9 above the entire floor length can be moved against the slot openings 5 got to. The sieve box 1 points directly above the floor Web strips 12 'on which the surface of the base plate 4 in divide three longitudinal fields. These web strips 12 'serve primarily increasing the stability of the bottom plate 4. The sieve frame 3 also has web strips 12 which are exactly above the web strips 12 of the base plate are arranged.

The sieve frames also have transverse web strips 13. So does not result here in the example of FIGS. 1-4 only clearing fields B, D and F, as they are due to the Web strips 12 'of the base plate 4, but through the additional subdivision of the sieve frame 3 with the cross bars 13 additional clearing fields A, C and E. The number of The clearing fields (A ... F) are separated by the corresponding subdivisions of the insert sieve frame. Crucial is now that in every common thus formed Räumfeld a screen cleaner 6 is inserted, which combines both keeps the screen mesh free at the top and clears the bottom down. Figures 3 and 4 each show a section of Figure 2, there are two screen boxes 1 on top of each other placed. There is a sieve frame in each of the sieve boxes 1 3 inserted so that between the screen fabric 10 and the bottom plate 4 a free product drop-through and discharge area 11 is formed in which the screen cleaners 6, 6 'etc. free can move. The clearing foot 7 of the screen cleaner 6, 6 'has here in addition the function, the fine goods of each Cleaning area B to A resp. D to C resp. To promote F to E, which is easily possible because the cross bars 13 only on the sieve frame 3 and not arranged on the base plate are so that at the appropriate location above the floor slab a slot 5 'is created. With protruding upwards Nubs or brushes are the sieve 10 over the whole Screen surface cleaned continuously. The screen cleaner points in its central area on a wobble 14 so that alternately the screen cleaner by slight tilting movements once up and then down the corresponding one Function fulfilled and apart from friction and inertia forces, can move freely over the flat base plate 4.

A multi-arm design of the screen cleaners 6, 6 'has the great advantage that every area of the screen mesh is accurate as with the base plate, right down to the far corners is kept clean. The screen cleaners ensure a optimal cleaning effect in all room directions. The relative large mass of the screen cleaner 6, 6 ', as well as the low-friction base plate support a very intensive Movement of the screen cleaners 6, 6 '. Even during longer periods The sieve cleaner is particularly capable of operating periods Keep screen mesh and base plate clean.

Figure 5 shows an almost ideal square clearing or Cleaning field division with 9 fields, there is the screen fabric 10 is shown only over half the screen frame 3. The length of a cleaning field is with Län and the Width marked with Bre. Considerable for the screen covering Poor. Another key point of the new invention is that the screen frame made of thin and lightweight metal strips are made, which in particular the frame profiles 13, 13 'and 14 relates. As well as can be seen from Figure 6, the screen frame 3 only on one side is a covering namely the mesh fabric tension on. On the opposite side, the sieve frame is open, so that Sieve cloth 10 now for the first time with insertion or replacement sieve frames equally freely accessible on both sides and is easy to clean.

The whole light metal frame can be made in one piece in metal die casting or preferably as a welded construction getting produced. It is very important that the framework minimal deflection in the elastic range, as a result the tensile forces from the fabric covering, which in operation maintaining tension in the mesh supported. The deflection is with line 15 (Figure 5) indicated symbolically. For a screen change, one must Larger number of reserve sieve frames 3, each with different coverings be kept ready. Because of the sieve frame sufficient inherent rigidity with very thin frame profiles own, and compared to the known screen frame only have about half the thickness D, they need little Space for replacement storage as can be seen in Figure 6 is. However, the web strips 12, 12 'made from a corresponding metal profile, which can be a solid or hollow profile. To be particularly advantageous the use of an all-metal frame has been proven. Such a frame is extremely rigid if a corresponding elasticity value is preferred becomes. The screen frame can also be used as a metal, wood or metal-plastic composite can be formed.

FIG. 7 shows a stack of 8 stacked one on top of the other Sieve box 1, 3-arm sieve cleaners are inserted.

FIG. 8 shows an entire square plan sifter, with the door 18 removed for a sieve compartment and an entire one Sieve stack 16 is visible. The sieve stack 16 has one known square plan sifter 24 sieve box 1. With the Sieve box, the number of sieve boxes and sieve frames Increase by at least 10% while maintaining the spaces for product conveyance above the sieve and at the same height of the plan sifter housing. The entire plan sifter 17 has one Not shown momentum drive, of all seven one forcing circular motion, the plan sifter 17 hung on bars 19 as a cantilever chair. The good is about Inlet connection 20, 20 'etc. fed to the sieve stacks and The sorted goods are discharged via discharge ports 21, 21 'etc.

In the figure 9, 9a and 9c is a screen cleaner as a boomerang 30 formed, with two typical, angled to each other Cleaning arms 31, respectively. 31 '. The two arms are provided with knobs 32 at the top, which the function of Have screen fabric cleaning. The boomerang 30 is in the vertical Center of gravity S provided with a wobble foot 14, which by a dimension "X" of a few millimeters compared to the two support feet 33 respectively. 33 'protrudes. Furthermore, the boomerang 30 opposite to the two arms 31 resp. 31 'a Bottom and slot clearing nose 34, which projects as far as that the corresponding part of the fine material through the slot 5 can push through, as expressed in Figure 9c. So that the necessary bumps of the side parts 35, for example the sieve frame 3, is the boomerang 30 in the direction of the bottom and slot clearing nose 34 a push arch 36. For perfect function the cleaning element, it is very advantageous if only the wobble foot 14 protrudes, the support feet 33, 33 'and the lower floor clearing edge 37 of the slot and floor clearing nose 34 are of identical height. This creates a free one Interplay between the operational elements, and it result statistically, with very high accuracy, accordingly approximately the same number of work assignments each. In the figure 9c, at the same time the knobs 32 are used for cleaning of the screen cloth 1 and the bottom and slot clearing nose 34 for cleaning the slot 5.

FIG. 10 shows a 3-star 40, in which three Arms 41, 41 'and 41' 'are offset from each other by 120 °. To protect the screen fabric cleaning agents, for example for the knobs 32 are each of the arms outwards as a baffle 42 trained who the actual abutment part for the screen cleaner represents. As from the two sectional drawings H-H and J-J emerges, the arms 41, 41 'and 41' 'in the Cross section each have a roof-like shape. The two arms 41, 41 'are identical, but the arm 41' 'has an additional one a bottom and slot clearing nose 34.

Figures 11-11b show a 4-star 50. The are Arms 51 and 51 'are identical, he arm 51' 'is similar, but has a cleaning rib instead of the cleaning knobs 52 on. Arm 51 '' 'is analogous to the 3-star 40 additionally a bottom and slot clearing nose 34. In 11a the knobs 32 are in use for cleaning of the screen fabric, whereas in FIG. 11b bristles which on the arm 51 '' ', clean the screen fabric 10. FIG. 11 shows the 4-star cleaner 50 in the phase cleaning a corner of the bottom of the sieve box 4. A pile 53 is directly in the slot opening according to arrow B-G 5 pushed by the relative movement B-S between the 4-star cleaner 50 and the plansifter or the Soil 4 according to arrow B-P. It is possible to use screen cleaners to build even more poor, but these have in relation to the Cleaning intensity no longer benefits.

Claims (6)

1. Device for cleaning sieves such as sieves of plan sifters in which the cleaning element is combined, is designed as a sieve fabric cleaner at the top and as a base rake at the bottom and has a tumbling foot in the region of its vertical axis through the centre of gravity and in which the cleaning element is designed with arms and comprises cleaning means for the sieve fabric which are arranged at the outer ends of the arms, the arms having resilient behaviour owing to their configuration and owing to the material, characterised in that the arms (31, 41) of the sieve cleaner (6, 6') have a square cross-sectional shape with a roof-shaped camber, the roof-shaped camber itself having a triangular cross section.
2. Device according to claim 1, characterised in that the sieve cleaner is designed as a boomerang (30) with two cantilever arms (31) which have upwardly projecting cleaning means for the sieve fabric (10), a base and slot raking nose (7, 34) preferably being arranged on the sieve cleaner (6, 61) opposite to the cantilever arms (31).
3. Device according to claim 1, characterised in that the sieve cleaner is designed as a three-pointed star (40), cleaning means for the sieve fabric (10) being arranged at the top at least on two arms (41) and an outwardly lengthened base and slot raking nose (7, 34) being arranged on one arm (41).
4. Device according to claim 1, characterised in that the sieve cleaner is designed with four arms (50) and at least one arm (31, 41) comprises a lengthened base and slot raking nose (7, 34).
5. Device according to one of claims 1 to 4, characterised in that the sieve cleaner (6, 61) comprises two or more arms (31, 41) and comprises base raking means and with its maximum horizontal dimension preferably amounts to more than 50% of the correspondingly smallest dimension of the individual raking fields.
6. Device according to one of claims 1 to 5, characterised in that the arms each have various cleaning means such as bristles or knobs (32) and or cleaning ribs at the top.

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