Flat sifter

Details Flat sifter Flat sifter

1999-08-23

2001-07-17

Nguyen, John Q. (Department: 3653)

Classifying, separating, and assorting solids

Sifting

Elements

C209S315000, C209S409000

Reexamination Certificate

active

06260710

ABSTRACT:

FIELD OF INVENTION
The invention relates to a plan sifter, in particular a square plan sifter and its structure with respect to the supporting elements.
BACKGROUND OF THE INVENTION
Plan sifters of this type are used, in particular, for sifting scrap, semolina- and/or flour-like products in mill process engineering and for sorting various types of vegetable grain such as wheat, rye or maize and generally for separating granular material into different grain sizes.
Plan sifters, in particular large and square plan sifters, belong to the current state of the art, for example for separating and sieving/sifting or classifying ground cereal products.
Operation of a plan sifter is influenced by many factors, natural limits to performance being imposed, even in the best condition. The intensity of the vibrating movement (maximum acceleration) is also restricted both by the moving behaviour of the ground product and by the maximum permitted forces in the housing. Performance data are therefore determined according to the specific quality of the individual fractions.
A square plan sifter is known from WO 93/16815, which has a swinging drive which forces the plan sifter and all sieves to perform a rotating movement, the plan sifter usually being suspended as a whole on rods as a freely vibrating screen.
With these plan sifters, horizontally arranged sieves having different mesh widths are superimposed vertically to form stacks. The sieves are assembled in the form of stacks and are pushed into cupboard-like sieve housings and fixed. The sieve housings are usually arranged symmetrically on either side of an unbalanced drive. The sieve housings form a supporting construction with the base plate and continuous cross bars. The sieve housings are rigidly connected at their front faces to the interposed drive housing via a connecting support. The unbalanced drive can have an unbalanced mass which is connected to the drive shaft at a variable distance as a function of speed (EP-A-491331). According to DE-PS 2823623, the frame of such a plan sifter is designed as a supporting housing which receives and laterally supports the stack of sieves, with a housing base which forms a supporting base for the stack of sieves and on the upwardly directed lateral walls thereof. In a different form, a plan sifter according to DE-PS 2256307 has stack fixing devices which produce vertical forces, the forces of the vibration generator being transmitted via top and bottom elements of rigid stack frames which are resistant to vibration. The stack frames are characterised by two respective vertical elements which are each arranged in a plane containing the centre of gravity of the stack and at right angles to the longitudinal plane extending through the stack and the vibration generator and which are rigidly connected to the top and bottom elements of the stack frames. The vertical elements form the vertical edges of a square vibrating frame, the vibrating bearings of the plan sifter being arranged on these vertical elements.
Although such constructions can sometimes be modular in design, they are expensive to produce.
SUMMARY OF THE INVENTION
It is accordingly the object of the invention to design a generic plan sifter such that its production of the supporting structure is discernibly simplified by a further developed modular construction. Furthermore, the dead weight is simultaneously to be reduced and sanitation and accessibility improved within the limits imposed in terms of vibration.
Since the flow of force can be effected via the supporting structure, further possibilities for modularisation are afforded. The force flows more gently overall and a greater proportion of the flow of force can be conveyed via the stack of sieves in a manner which is beneficial to operation. A supporting structure of this type can obviously be compared with the state of the art according to DE-PS 2256307 only with respect to the basic elements of base, vertical supports and cover, but its detailed design is not obvious as it is not covered by the principles of vibration. In particular, the production and assembly of the parts of the supporting structure are simplified. The supporting structure of the plan sifter according to the invention consists of several double compartments which are connected to one another at the sides and are suspended by vertical supports at the ends.
The double compartments consist of a cover and a base, which are connected by vertical profiles and form two (respective) compartments (sieve compartment) with lateral parts. A separate frame construction for base and cover is or can be dispensed with.
The lateral parts are fastened positively and non-positively in the vertical profiles, the positive fastening ensuring tightness and therefore sanitation. Cold and warm bridges can be avoided by further insulation. An air duct in the vertical profiles can cause heating of the profile surface due to permeation with warm air from the cover, so condensation is avoided. Such an option may be worthwhile, in particular in the case of delicate products. The warm air stream can be prepared by removal from the product stream or also separately.
The stacks of sieves can then be inserted and fixed, preferably purely positively, in the supporting structure. These stacks of sieves can be fixed both conventionally and, in a further embodiment of the invention, using pneumatic means. An elastic, inflatable element which ensures defined, uniform vertical fixing when filled with air and at the same time has a sound-damping effect is arranged in the space between stacks of sieves and cover. In contrast to conventional fixing which is effected from the exterior, fixing can be carried out more simply and compactly from the interior.
In a further embodiment of the invention, the external lateral parts and also the doors consist of sandwich constructions or foamed elements, these sandwich elements being known as such but not such an application. The doors are preferably inserted and fixed positively and non-positively between two vertical profiles and are therefore easy to use.


REFERENCES:
patent: 2455383 (1948-12-01), Pickard
patent: 2511885 (1950-06-01), Thompson
patent: 3980555 (1976-09-01), Freissle
patent: 4219412 (1980-08-01), Hassall
patent: 4347129 (1982-08-01), Rutherford
patent: 4383919 (1983-05-01), Schmidt
patent: 4728422 (1988-03-01), Bailey
patent: 4846352 (1989-07-01), Bailey
patent: 4950403 (1990-08-01), Hauff et al.
patent: 5045184 (1991-09-01), Arkles
patent: 5051171 (1991-09-01), Hukki
patent: 5137622 (1992-08-01), Souter
patent: 5266194 (1993-11-01), Chiodo
patent: 5385241 (1995-01-01), Bokor
patent: 5385669 (1995-01-01), Leone, Sr.
patent: 5417906 (1995-05-01), Chiodo
patent: 5527500 (1996-06-01), Specht
patent: 5538139 (1996-07-01), Keller
patent: 5598931 (1997-02-01), Hosogoshi et al.
patent: 5664686 (1997-09-01), Hosogoshi et al.
patent: 5755334 (1998-05-01), Wojcik et al.
patent: 5819952 (1998-10-01), Cook et al.
patent: 5851393 (1998-12-01), Carr et al.
patent: 6006923 (1999-12-01), Helmy et al.
patent: 359589 (1958-11-01), None
patent: 359589A (1962-02-01), None
patent: 1507716 (1966-07-01), None
patent: 2256307 (1973-07-01), None
patent: 2459285 (1976-06-01), None
patent: 2506981 (1976-06-01), None
patent: 2823623 (1979-11-01), None
patent: 3544752C1 (1987-05-01), None
patent: 3802799A1 (1989-08-01), None
patent: 0330846 (1989-01-01), None
patent: 491331 (1992-06-01), None
patent: 0584302 (1993-02-01), None
patent: 1503343 (1978-03-01), None
patent: WO 93/16815 (1993-09-01), None
English Translation of specification and claims of CH 359, 589.
International Search Report for PCT/CH 97/00227.

Affiliated with

Also associated with

Rating

Flat sifter does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Flat sifter, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Flat sifter will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2549487