GB2252493A - Vegetable washers - Google Patents

Abstract

The washer e.g. for beet, has a drum (10) rotatable about a horizontal axis and comprised by a cylindrical array of longitudinally extending spaced slats (12) carried by external supporting rings (14, 15, 16, 18, 20), the drum also having an internal helical ribbon (40) for beet conveyance and internal spray nozzles wherein the slats (12) have curved external faces (22) to match the curved surface of the supporting rings to which said slats are secured. The slats (12) are of general rectangular cross-section rod form. <IMAGE>

Description

Improvements in Vegetable Washers This invention relates to a vegetable washer, and in particular although not exclusively to a beet sample washer.

Conventionally, when sugar beet arrives at a factory for processing, a sample batch is weighed, washed, sorted from stones and re-weighed before passing to an analyser which determines the sugar content. This analysis is critical to the price to be paid for the beet, and it is therefore also essential that the preceding sample treatment steps should not affect the result of the analysis. In this respect, the washing step can have the most significant influence.

A beet sample washer typically comprises a drum in the form of a cylindrical array of spaced slats carried by external supporting rings, the drum being mounted for rotation about a generally horizontal axis and having firstly an internal helical ribbon for conveying beet along the rotating drum and secondly a number of internal spray nozzles from which washing water can be jetted on to the beet as it passes along the drum. Such a beet sample washer is hereinafter referred to as a beet sample washer of the kind described.

The beet sample will typically contain many broken pieces of beet of various sizes, and selection of the spacing between the drum slats is critical to the passage of these beet pieces out of the drum during washing, which is in turn critical to the result of the final analysis of the beet.

Not only is the initial selection of the spacing critical, but the selected spacing must be maintained throughout usage of the drum and vibrations of the slats which may vary the spacing must be minimised. This has been a problem with known beet sample washers and it is an aim of the present invention to provide a solution to this problem.

According to the present invention, in a beet sample washer of the kind described, the outer faces of the slats of the drum are radiused in the direction of their width to match the inside curvature of the supporting rings to which said slats are secured.

Hitherto, the slats of known beet washers have been formed by channel-section members with flat bases which have engaged the interior surfaces of the supporting rings along two spaced lines. Resultant wear has thus rapidly led to loosening of the fixings of the slats to the supporting rings, with the result that the selected spacing between the slats has not been maintained, and that this cause of variation in the spacing between the slats has been aggravated by vibration.

It is an important further feature of the invention, for the further minimisation of vibration, that the slats are formed of solid rod, preferably generally of rectangular cross-section excepting the radiused outer face.

Additionally, the rods preferably have rounded inner corner edges. Extruded-rods of solid aluminium alloy are preferred.

The supporting rings preferably include an inlet ring at the end of the drum into which beet is introduced, and an outlet ring at the other end of the drum where washed beet emerges. It will be appreciated that, during the washing process, mud and small stones, as well as small pieces of broken beet, are washed out between the slats of the drum.

Small stones can possibly become wedged between two adjacent slats, and if this occurs can tend to widen the slats apart and thus alter the selected spacing between them. This effect is predominantly noticeable at the ends of the slats, i.e. where the slats are secured to the inlet and outlet rings. For this reason, where the slats are secured to the inlet and outlet rings, filler blocks are incorporated between the slats to prevent the entry of stones.

The importance of maintaining the selected spacing between the slats to prevent wastage of beet has to be emphasised.

In a preferred embodiment, the spacing between the slats is precisely maintained, along the length of the drum, by seven supporting rings. These rings comprise, in addition to the inlet and outlet rings, two track rings positioned towards the ends of the drums and which are supported on rollers, external to the drum, and on which the drum rotates, a centrally positioned gear ring through which the drum is externally driven in rotation, and two tie rings, respUtively intermediate the gear ring and the two track rings.

It is also important to avoid damage to the beet during washing within the rotating drum. It is for this reason that the slats have rounded inner corner edges. However, a further feature important in this respect concerns the internal helical ribbon which drives the beet along the drum during rotation of the latter. This ribbon is secured to the internal surface of the drum, i.e. the slats, by means of cleats located wholly behind the ribbon with respect to the surface of the ribbon which drives the beet. Moreover, the fillet formed between the ribbon and the inlet ring is blocked off to prevent pieces of beet becoming trapped.

A practical example of beet sample washer in accordance with the invention is exemplified with reference to the accompanying drawings, in which: Figure 1 is a side elevational view of the washer, with the near side of the drum cut away; Figure 2 is a perspective view of the drum, also in part cut away; and Figures 3, 4, 5 and 6 show details of the drum assembly.

A beet sample washing machine is shown in Figure 1. The principal component of the machine is the drum shown in Figure 2, which is mounted for rotation about a horizontal axis.

The drum, generally referenced 10, comprises a large plurality, in fact forty one, of spaced apart slats 12, mounted parallel to and around the drum axis to define the periphery of the drum, by means of a number, in fact seven, of supporting rings 14, 15, 16, 18 and 20, external to the slats.

Each slat 12 is of extruded aluminium and has a solid generally rectangular cross-section. However, as will be clear from Figure 4, each slat 12 has a radiused outer face 22 matching the internal radius of the supporting rings 14 to 20 so that, as shown in Figure 5, the slat seats solidly against the inside face of the ring, to which it is secured by a bolt fixing 24. As also shown in Figures 4 and 5, the inner corner edges 25 of the slats are rounded.

Relative dimensions of the cross-section of one of the slats are also shown in Figure 4. The series of slats 12 around the drum define uniform elongate spacings or gaps 26 between them (see Figure 3), the width of said gaps being preselected.

Uniformity of the widths of the gaps 26 along the length of the drum is maintained by the seven supporting rings to which the slats are secured, which rings comprise an inlet ring 14 at the end of the drum into which in use sugar beet is introduced, an outlet ring 15 at the end of the drum from which washed beet emerges, a central gear ring 18, two track rings 16, and two tie rings 20 intermediate the gear ring 18 and the track rings 16.

Each track ring 16 has a flanged outer periphery 27 by means of which the drum is supported on fixed position rollers 28, one pair for each track ring, and on which the drum is able to rotate about its horizontal axis.

The central gear ring 18 has a toothed outer periphery 30, cooperating with a fixed position pinion 32 drivable by an electric motor 34 (see Figure 1).

The inlet and outlet rings 14 and 15 and the tie rings 20 are present accurately to maintain uniformity of the preselected gap between the slats. However, the inlet ring 14 carries a drum end plate 36 for retaining beet introduced into the drum and for minimising clearance between the end of the drum 10 and a washer casing 38.

Fixed to the interior of the drum, i.e. to the slats 12, is a helical flight or ribbon 40 which drives beet along the drum from the inlet end to the outlet end as the drum is rotated.

Suspended within the rotary drum by end mountings 42, one constituted by an inlet feed pipe, are a pair of perforated water pipes 44 defining a series of spray nozzles along the major part of the length of the drum, whereby water can be jetted on to the beet tumbling along the bottom of the drum from the inlet end to the outlet end.

In use, the drum is rotated at a speed between 8 and 18 r.p.m. A beet sample is introduced through the inlet end of the drum and, as said sample passes through the drum, the water jets impinge on the beet, washing off dirt and small stones. Spent water, dust, small stones and also small broken pieces of beet fall between the drum slats 12 into a collecting tank 46. The gap 26 between the slats 12 is pre-selected so that the loss of beet is'reduced as far as possible without compromising the washing action. The size of the gap is critical to the price ultimately to be paid for the beet, and it is therefore also critical to maintain the precisely selected gap width unformly along the drum during use and wear of the drum. The slats 12, supporting rings 14 to 20 and fixings which secure the slats and supporting rings together are therefore all parts manufactured with precision.The solid crosssection of the slats and the solid seating of the slats against in the inside of the supporting rings are especially important in this respect. In particular, these features reduce vibration of the slats during use, and avoid loosening of appreciated the slat fixings as the drum wears.

It will be appreciated that small stones are liable to become wedged between the slats during use, and if this happens at the ends of the drum, there is a risk that the critical gap 26 between the affected slats can be disturbed.

For this reason, as is also shown in Figure 5, at the inlet and outlet rings 14, 15, filler blocks 47 are secured in position by screws 48 between the slats, so as to prevent the entry of small stones. The fillet between the inlet ring and the adjacent end of the helical ribbon is also blocked off.

It is also important that, during the washing process, the beet should not be damaged. For this reason, the internal surfaces of the drum are all smooth finished and, in particular, all sharp edges are removed. It is for this reason that the inside edges of the slats 12 are rounded, as previously mentioned.

Additionally however, as shown in Figure 6, the helical ribbon 40 is fixed in position by cleats 50 secured by fixing screws 52 to the slats 12 and welded, as indicated at 54, to the surface of the ribbon behind the face of said ribbon which in use drives the beet through the rotating drum. Thus, no part of the fixing interrupts the smooth front face of the ribbon.

It will be appreciated that various modifications of the above-described and illustrated beet sample washer are possible within the scope of the invention hereinbefore defined. Moreover, the machine may readily be adapted for washing vegetables other than sugar beet.

Claims (11)

Claims

1. A beet sample washer comprising a drum in the form of a cylindrical array of spaced slats carried by external supporting rings, the drum being mounted for rotation about a generally horizontal axis and having firstly an internal helical ribbon for conveying beet along the rotating drum and secondly a number of internal spray nozzles from which washing water can be jetted on to the beet as it passes along the drum, wherein the outer faces of the slats of the drum are radiused in the direction of their width to match the inside curvature of the supporting rings to which said slats are secured.

2. A beet sample washer according to claim 1, wherein the slats are formed of solid rod.

3. A beet sample washer according to claim 2, wherein the rod is generally of rectangular cross-section excepting the radiused outer face.

4. A beet sample washer according to claim 3, wherein the rods have rounded inner corner edges.

5. A beet sample washer according to any of claims 2 to 4, wherein the rods are extruded rods of solid aluminium alloy.

6. A beet sample washer according to any of claims 1 to 5, wherein the supporting rings preferably include an inlet ring at the end of the drum into which beet is introduced, and an outlet ring at the other end of the drum where washed beet emerges.

7. A beet sample washer according to claim 6, wherein, where the slats are secured to the inlet and outlet rings, filler blocks are incorporated between the slats to prevent the entry of stones.

8. A beet sample washer according to any of claims 1 to 7, wherein the spacing between the slats is precisely maintained, along the length of the drum, by at least seven supporting rings comprising, in addition to inlet and outlet rings, two track rings positioned towards the ends of the drums and which are supported on rollers, external to the drum, and on which the drum rotates, a centrally positioned gear ring through which the drum is externally driven in rotation, and at least two tie rings, respectively intermediate the gear ring and the two track rings.

9. A beet sample washer according to any of claims 1 to 8, wherein the internal helical ribbon which drives the beet along the rotating drum is secured to the internal surface of the drum, i.e. the slats, by means of cleats located wholly behind the ribbon with respect to the surface of the ribbon which drives the beet.

10. A beet sample washer according to claim 9, wherein the fillet formed between the ribbon and the inlet ring is blocked off to prevent pieces of beet becoming trapped.

11. A beet sample washer substantially as hereinbefore described with reference to the accompanying drawings.