Classifying – separating – and assorting solids – Sifting – Endless belt sifters
Patent
1995-12-19
1999-01-19
Bollinger, David H.
Classifying, separating, and assorting solids
Sifting
Endless belt sifters
209382, 209386, 209421, 171 15, B07B 110
Patent
active
058605339
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a grader suitable for use in grading and separating potatoes at harvest but not exclusively.
Separators have long been used to separate smaller seed potatoes from larger potatoes as well as separating stones, earth and other debris collected during harvest. Grading, that is separating of potatoes more or less accurately on the basis of their size, is of considerable commercial importance for potato growers. For the producer of potatoes the value of ware potatoes which generally have a diameter greater than 55 mm, can be as little as one quarter of the value of seed potatoes which generally have a diameter within the range of from 35 to 55 mm--below 35 mm diameter potatoes are generally not considered suitable for use as seed. To the buyer of seed potatoes moreover the weight and hence cost of potatoes required for a given planting density will vary considerably with the size or diameter of the seed potatoes. There is accordingly a need for accurate grading of potatoes and not only between seed and ware but also for particular size ranges of seed potatoes e.g. 35 to 45 and 45 to 55 mm diameter. The sizing of seed potatoes is strictly controlled by the United Kingdom Department of Agriculture, and other national agricultural institutions.
Presently known graders generally use either continuous screens made of wire to form squares or sieve type screens which are both vibrated or oscillated vertically in an attempt to displace the potatoes thereon relative to the screen thereby to facilitate passage of smaller potatoes through the screen to be collected separately from larger potatoes which are carried further on by the screen to their own collecting point. Such violent agitation tends to cause the potatoes to jump up and down on the screen whereupon the potatoes may be damaged when they fall back onto the screen. Also such agitation is often of limited effectiveness insofar as the potatoes simply fall back into their original position in which they were held from passing through the screen, and/or the potatoes simply move up and down together with the screen so that there is little or no displacement of the potatoes relative to the screen. Damaged potatoes stored with sound potatoes can give rise to rot which can subsequently damage healthy potatoes and are significantly less attractive to prospective purchasers, be they wholesalers, shopkeepers, or ordinary shoppers, and it is therefore particularly important to avoid damage as far as possible.
It is an object of the present invention to avoid or minimise one or more of the above disadvantages.
The present invention provides an endless conveyor grader suitable for use in grading tubers or the like wherein the endless conveyor comprises an endless grid screen supported on endless drive transmission means at opposite sides of said endless grid screen, characterised in that there are provided at opposite sides of the endless grid screen pathway, endless drive transmission guide means formed and arranged so as to define at least one cascade or step in the endless grid screen pathway for tumbling, in use of the grader, tubers passing over said cascade or step thereby to provide the required movement of tubers on said grid screen to facilitate the grading process.
Various suitable guide means are known in the art but conveniently there are used guide means in the form of guide rollers or sprockets. These may simply be used as pairs of more or less closely spaced guide rollers or sprockets defining a generally `S`-shaped pathway for the drive transmission means. The latter may be in the form of a belt, chain, cable or other like flexible endless connector.
Thus by means of the present invention, movement of tubers on the new screen and thereby improved grading efficiency, especially for elongate potatoes, may readily be provided in an economic and effective manner with a significantly gentler action on the tubers.
A particular suitable form of endless grid screen for use in the grader of the present invention comprises a multiplicit
REFERENCES:
patent: 3348680 (1967-10-01), Mathews et al.
patent: 4174755 (1979-11-01), Siri
Bollinger David H.
Reekie Manufacturing Limited
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