GB2053463A - Sorting objects according to colour with optical element cleaning - Google Patents

Abstract

Machine for separating solid products according to colour comprising a sorting zone 3 illuminated by bulbs or lamps 6 each surrounded by a sleeve 8 to define an annular space which is around part of the bulb and into which ventilating and cleaning air is discharged from a nozzle 14. The sorting arrangement comprising photoelectric cells 15 and screen plates 16 is equipped with a cell-ventilation system comprising air ejectors 19. <IMAGE>

Description

SPECIFICATION Improved machine for sorting solid products according to colour This invention comes within the field of the separation of solid products by sorting the latter according to their colour. It is concerned with an improved machine designed to be used for products in particulate form, of which the maximum dimension is of the order of a half to two centimetres.

Machines are known which are used for sorting solid products, such as dehydrated vegetables, follicles, seeds, bulbs, etc., for the particular purpose of eliminating therefrom the impurities and the dust, or those of said products of which the appearance does not correspond to a set colour criterion.

In such machines, the products to be sorted travel into a generally strongly illuminated space, so as to intercept the paths of light between photoelectric cells and uniformly tinted screen plates. Each time an individual solid product intersecting one of these paths does not correspond to a set colour, the passage thereof releases a jet or air originating from a nozzle fed with compressed air, the said jet projecting the product out of the flow of the products conforming to this colour.

These machines have the disadvantages of requiring frequent maintenance and a replacement of parts and, as a consequence, a large and specialised staff. The generally spherical electric bulbs illuminating the sorting space have to be regularly removed and cleaned, because they receive a deposit of dust and impurities. It is proved by experience that this maintenance always has to be carried out at intervals of about 8 hours. The effective life of these bulbs is also relatively short, this being particularly because of the overheating thereof, due to being used in a closed space. On the other hand, the screen plates which are bombarded by eliminated solid particles quickly deteriorate. It is apparent from tests that the coloured coating with which they are provided has practically disappeared after about 60 hours.

The invention is concerned with an improved machine for sorting solid products of the type such as those which are described above, which machine provides advantages over the prior art machines.

According to the present invention, an improved machine for sorting solid products according to colour comprises a sorting space, an entry zone for products to be sorted, a zone for discharging the conforming products, a discharge zone for non-conforming products, means for illuminating the sorting space, a sorting device comprising photoelectric cells and screen plates, and means for ejecting non-conforming products by a jet of air emitted through a nozzle, and wherein the means for illuminating the sorting space comprises at least one electric bulb, at least one holder or socket receiving the cap of the bulb, the said holder or socket being enclosed by a sleeve defining an annular space around the socket, and a bulb-ventilation device discharging into the annular space.

According to a particular feature of the invention, the bulb-ventilating arrangement comprises an inlet for fresh air under pressure, an air-distribution pipe and at least one sleeve-type nozzle.

The fresh air is preferably produced at low pressure, in the range from 50 mm to 100 mm/cm2 by a fan fitted to the machine. This air circulates around the cap and the base of the bulb and continues its path around the cylindrical part, thus assuring simultaneously a cooling and ventilation effect.

According to another feature of the invention, the machine incorporates a second ventilation means, which latter is intended for ventilating the objectives of the photoelectric cells. This latter means is separate from the first means and it comprises an air inlet, a distribution pipe and a pair of air ejectors of small section discharging in the immediate vicinity of each objective. The air emitted by this second ventilation means is preferably at high pressure, in the range from 1 to 2 kg/cm2, and is produced by a compressor.

According to another feature of the invention, the nozzle of the means for ejecting nonconforming products has a downwardly directed nozzle, in this way ensuring that the eliminated products do not strike and erode the screen plates.

As a result of the invention, the time between two successive maintenance operations on the bulbs is multiplied by a factor which is of the order of ten and the life of the bulbs is multiplied by a factor which is of the order of five. This result is obtained by a cooling and a continuous ventilation of the bulbs.

The cost of the bulbs and their supports is lowered at least to a quarter of the average cost, by using more resistant and less troublesome novel supports and commercially available bulbs.

The use of these latter is made possible as a consequence of their permanent ventilation.

The effective life of the screen plates is practically unlimited. This result is obtained by eliminating the danger of the said plates being bombarded by the eliminated products.

A machine according to the invention is hereinafter described in detail by reference to the accompanying figures.

Figure 1 is a transverse section of a machine according to the invention, Figure 2 is a partial view along the line Il-Il of the casing in Figure 1, Figure 3 is a sectional view along the line Ill-Ill of Figure 2, and Figure 4 is a sectional view and to a larger scale of a bulb holder or socket.

The machine comprises a sorting space 2, an arrival zone for products 3 which are to be sorted and with an inlet opening 31 (Figure 3), a discharge zone 4 for products which conform and a discharge zone 5 for non-conforming products.

The sorting space or chamber 2 is illuminated by a lighting arrangement, which here comprises four cylindrical electric bulbs or lamps 6 each having a cap 23. The lamps are mounted by means of their caps 23 in supports which are formed by holders or sockets 7 enclosed by a sleeve 8 which defines an annular space 9 around each socket. The machine is covered by a reflector hood 10.

Fixed on the hood so as to be capable of being detached is a support 11 of a first means for ventilating and cooling the lamps or bulbs. The said means comprises an inlet 12 for fresh air at low pressure, a distribution pipe 13 and sleevetype nozzles 14.

Three photoelectric cells have objectives which are represented diagrammatically at 1 5. Opposite each cell is located a screen plate 16, the position of which is adjustable by using a conventional system which has not been illustrated here.

A second ventilation arrangement comprises a high-pressure air inlet 17, a distribution pipe 1 8 and small-section ejectors 1 9 so distributed that each objective is ventilated by a pair of ejectors.

As the machine comprises three cells, it therefore has six ejectors. For convenience in reading Figure 2, these ejectors are only represented by their apertures 24 on the pipe 1 8.

Represented in Figure 3 is a nozzle 20 for the ejection by an air jet of the non-conforming products which are identified during their passage through the path from a photoelectric cell objective 1 5 to a screen plate 1 6. This nozzle 20, fed with air under pressure by means of a pipe 21, has a nozzle 22 which is directed obliquely downwards. The direction of emission of the air jet, from the nozzle 22, is represented in broken lines. This inclination which is given to the nozzle 22 ensures that the non-conforming products are not projected on to the screen plates.

Claims (5)

1. Improved machine for sorting solid products according to colour comprises a sorting space, an entry zone for products to be sorted, a zone for discharging the conforming products, a discharge zone for non-conforming products, means for illuminating the sorting space, a sorting device comprising photoelectric cells and screen plates, and means for ejecting non-conforming products by a jet of air emitted through a nozzle, and wherein the means for illuminating the sorting space comprises at least one electric bulb, at least one holder or socket receiving the cap of the bulb, the said holder or socket being enclosed by a sleeve defining an annular space around the socket, and a bulb-ventilation device discharging into the annular space.

2. Machine according to claim 1, wherein the bulb-ventilation device comprises an air inlet, an air distribution pipe and at least one sleeve-type nozzle, the ventilation air is at a pressure of the order of 50 to 100 mm/cm2.

3. Machine according to claim 2, including a high pressure means for ventilating the photoelectric cell objective, formed of an air inlet, a distribution pipe and at least one ejector of small section discharging in the immediate proximity of the objective, and wherein the air of the objective ventilation arrangement is at a pressure of the order of 1 to 2 kg/cm2.

4. Machine according to claim 3, wherein the nozzle of the ejection device using an air jet for the non-conforming products has an outlet directing this air jet in a downwardly oblique direction.

5. A machine for sorting solid products according to colour substantially as hereinbefore described with reference to the accompanying drawings.