GB2308993A

GB2308993A - Web Grader

Info

Publication number: GB2308993A
Application number: GB9705193A
Authority: GB
Inventors: John Clarke Hooley
Original assignee: Tickhill Engineering Co Ltd
Current assignee: Tickhill Engineering Co Ltd
Priority date: 1993-03-11
Filing date: 1994-03-11
Publication date: 1997-07-16
Anticipated expiration: 2014-03-11
Also published as: GB2308993B; GB9705193D0

Abstract

A web grader comprising an endless grading web having a plurality of grading openings therein, the grading web being trained around spaced apart first and second web return means to provide a grading web upper run and a lower run disposed below the upper run, drive means for driving the web to advance articles to be graded along the upper run, a receiving means disposed below the upper run to receive articles which have passed through the openings of the web during passage along the upper run and agitating means 173 to agitate the upper run to facilitate grading wherein the agitating means comprises means to slacken and tighten the web so as to cause the upper run to oscillate up and down.

Description

Title: "Web grader" Description of Invention This invention relates to a web grader comprising an endless grading web having a plurality of grading openings therein, the grading web being trained around spaced apart first and second web return means to provide a grading web upper run and a lower run disposed below the upper run, drive means for driving the web to advance articles to be graded along the upper run, a receiving means disposed below the upper run to receive articles which have passed through the openings of the web during passage along the upper run and agitating means to agitate the upper run to facilitate grading.

Such a web grader is commonly used in agricultural fields for grading potatoes, onions, beet, carrots, turnips and the like.

Hitherto, the web has been agitated by providing at least one and generally more than one agitating assembly, the or each of which comprises at least one agitating element carried on a shaft which is mounted for rotation beneath the upper run. As the or each shaft is rotating the or each agitating element engages the web and causes it to be raised and lowered, thus agitating the web and hence the articles to be graded.

This arrangement suffers from two disadvantages. The first disadvantage arises because the agitators are disposed directly under the upper run of the grading web so that any article which passes through the web falls onto the revolving agitating element or its shaft, thus causing damage to the article.

The second disadvantage is because the or each agitator assembly is disposed between the upper run of the web and the receiving means, this sets a minimum distance between the upper run of the web and the receiving means and consequently this distance is always relatively large so that damage to articles can occur as they fall onto the receiving means.

An object of the present invention is to provide a new and improved web grader whereby the above mentioned disadvantages are overcome or are reduced.

According to the present invention we provide a web grader comprising an endless grading web having a plurality of grading openings therein, the grading web being trained around spaced apart first and second web return means to provide a grading web upper run between said return means and a lower run disposed below the upper run, drive means for driving the web to advance articles to be graded along the upper run, a receiving means disposed below the upper run to receive articles which have passed through the openings of the web during passage along the upper run and agitating means to agitate the upper run to facilitate grading wherein the agitating means comprises means to slacken and tighten the web so as to cause the upper run to oscillate up and down, said agitating means comprising at least member, additional to said return means, having a surface which engages with the web only at a position spaced from said upper run.

The additional member maybe rotatable and be at least one of noncircular and eccentric to the axis of rotation of the member.

The additional member may have a surface of square, hexagonal, octagonal or other polygonal cross-section or may be of non-circular curved crosssection such as elliptical or may be of circular cross-section but disposed eccentrically to the axis of rotation of the member.

The at least one additional member may be oscillated in a direction towards and away from the web.

The or each additional member may be mounted on a shaft which is guided for oscillation in a guide means.

The additional member may be caused to oscillate by an oscillator drive means.

The oscillator drive means may comprise a cam means as hereindefined.

The additional member may be caused to oscillate by an oscillator arm connected at one end to the additional member shaft and be driven to oscillate at the other end by the oscillator drive means.

The additional member may comprise a drive shaft which is adapted to be rotated by a motor and the drive shaft having said cam means to cause oscillation of the oscillator arm.

The cam means may be disposed longitudinally outwards of the web and the oscillator arm extending from said cam means, to be connected to the additional member shaft, in a direction which extends generally horizontally and towards the web.

The term "cam means" is used herein to include an eccentric or crank.

At least one return means may comprise a rotatable member and preferably each return means comprises a rotatable member.

The invention will now be described by way of example with reference to the accompanying drawings in which: FIGURE 1 is a side elevation of part of a web grading apparatus; FIGURE 2 is an end elevation of the apparatus of Figure 1; FIGURE 3 is a plan view of the apparatus of Figure 1; FIGURE 4 is a side elevation of a modification of the apparatus of Figures 1-3; FIGURE 5 is an end elevation of the apparatus of Figure 4; FIGURE 6 is a fragmentary section to an enlarged scale on the line 6-6 of Figure 4; FIGURE 7 is a fragmentary section to an enlarged scale on the line 7-7 of Figure 4; FIGURE 8 is a fragmentary section to an enlarged scale on the line 8-8 of Figure 4; and FIGURE 9 is a diagrammatic side elevation of a further modification embodying the invention.

Referring to Figures 1-3, there is illustrated a web grading apparatus comprising a main frame 10 carried on uprights 11. The main frame and the uprights are, in the present example, made of mild steel, but may be made of any other suitable material if desired. First and second web return means 12, 13 respectively are mounted on the frame 10 and an endless grading web 14 is trained around the return means 12, 13 to provide a grading web upper run 15 and a lower run 16 disposed below the upper run. Additional guides, which may comprise rollers or fixed guides, are provided at 12a 13a for the lower run 16.

The grading web 14 comprises a flexible endless steel web provided with square holes. The web may be of any desired construction and the holes may be of any other desired shape or size. The upper run is inclined upwardly from the return means 13 towards the return means 12.

A receiving means 17 for articles which have been graded by passing through the apertures of the upper run 15 of the web 14 is provided between the upper and lower runs 15, 16. In the present examp]e the receiving means 17 comprises a rubber endless belt-type cross conveyor but, if desired, can be a chute or a vibrating conveyor, or a receptacle which is emptied from time to time. The cross conveyor 17 is supported on members 18 which extend between the uprights 11 and comprises channel section side members 19 between which an upper run 20 and a lower run 21 of the rubber belt extend, the belt being trained around first and second belt return means disposed at opposite ends of a bed 22. The return means comprise rollers 23, one of which is driven by a motor 24 to drive the cross conveyor.

The first belt return means 12 comprises a drive roller 25 which is covered in rubber to increase the friction between it and the web. The roller 25 is fixed to a shaft 26 which is mounted, at its ends, in bearings 27 carried by the main frame 10. At one end the shaft 26 carries a drive sprocket 28 which is driven by a chain 29 from a sprocket 30 rotated by a drive motor 31 mounted on the main frame 10.

The other return means 13 comprises a reciprocating tail roller 32 which may also be rubber covered if desired. The tail roller 32 is fixed to a shaft 33 and at opposite ends the shaft 33 is mounted in bearings 34. Inwardly of the bearings 34 the shaft 33 is provided with a roller 35 which is slidably mounted in a horizontally extending guide slot 36 so that the shaft 33, and hence the roller 32, is guided for oscillating movement in a horizontal plane towards and away from the other roller 25.

Each bearing 34 is carried by an oscillator arm 37 which carries at its other end a pair of bearings 38 which receive eccentrics 39 carried by an oscillator shaft 40 mounted for rotation in bearings 41 carried by the main frame 10. The oscillator shaft 40 has a drive sprocket 42 fixed thereto which is driven via a chain 43 from a sprocket 44 driven by an oscillator drive motor 45.

If desired, the oscillator arms may be caused to oscillate by any other suitable means, for example by providing the oscillator arm with a cam follower which can engage a cam of suitable configuration, such as elliptical, the cam being rotated by a suitable means.

In the present example the motor 45 is a variable speed motor and, as mentioned before, the drive is a chain and sprocket drive. If desired, however, the oscillator shaft 40 may be driven in other ways, for example a chain and sprocket drive from the motor 31, or the motor 45 could be arranged to drive the shaft 40 directly, or via a gear drive, belt drive, or in any other suitable way.

In use, the articles to be graded are loaded onto the upper run 14 adjacent the tail roller 32. The articles are transported towards the drive roller end and articles smaller than the apertures in the grading web fall therethrough onto the cross conveyor 17. Larger size articles are discharged from the drive roller end of the upper run.

As the articles are being transported towards the drive roller end they are agitated by lifting and lowering the upper run 15 of the grading web as a result of oscillation of the tail roller 32 towards and away from the drive roller 25 under the guidance of the guide slot 36. This oscillating movement shortens and lengthens the distance between the tail roller and the head roller, which has the effect of slackening and tightening the web, thus agitating the crop, the upper run moving from the position shown at A in Figure 1 to B and back again repeatedly.

The magnitude and frequency of oscillation can be adjusted by varying the extent of movement of the tail roller by adjusting the offset of the eccentric or suitable adjustment of other drive means when provided, or by varying the speed of the oscillator shaft.

If desired, instead of the tail roller 32 being arranged to be oscillated, the drive roller 25 may be arranged to oscillate and further, if desired, both the tail roller and the drive roller may be arranged to oscillate.

Further alternatively, the or each return means may be a non-rotatable member, oscillatable or not. Where each return means is non-rotatable a separate drive means may be provided. For example, a suitably adapted drive means positioned as illustrated for the guide means 13a or 14a may be arranged to drive the web.

In an alternative, not shown, at least one of the drive and tail rollers may be provided with a surface which is of non-circuij'r shape, for example, square shape, hexagonal, octagonal, other polygonal shape, or of non-circular curved shape such as elliptical and/or an eccentrically disposed circular or other shape.

Referring now to Figures 4-8 wherein the same reference numerals have been used for corresponding parts as are used in Figures 1-3 and the description of these similarly numbered parts with reference to Figures 1-3 is also applicable to Figures 4-8.

The other return means 13 comprises a reciprocating tail roller 32 which may also be rubber covered if desired. The tail roller 32 is mounted on a "return means" shaft 33 by bearings 134. At opposite ends the shaft 33 is provided with bearings 135 which pivotally connect the shaft 33 to a pair of oscillator arms 136. Inwardly of the bearings 135 the shaft 33 is provided with rollers 137 which are slidably mounted in horizontally extending guide means 138 provided on a sub-assembly 10a of the frame 10 so that the shaft 33 is guided for oscillating movement in a horizontal plane towards and away from the other roller 25.

Each bearing 135 is carried by an oscillator arm 136 which carries at its other end a pair of bearings 138 which receive eccentrics 139 carried by an oscillator shaft 140 mounted for rotation in bearings 141 carried by the main subassembly 10aof the frame 10. The oscillator shaft 140 is driven directly from an output shaft of a gear box associated with an oscillator drive motor 143 mounted on the main frame 10 as shown in Figure 5.

In this specification the term "cam means" is used to include not only an external cam such as an elliptical cam, but also an internal cam, and an eccentric and a crank. Any such "cam means" may be used to provide oscillation of the oscillator arm in either of the described embodiments.

In the present example the motor 45 is a variable speed motor. If desired, however, the oscillator shaft 40 may be driven in other ways, for example a chain and sprocket drive from the motor 31, or the motor 143 or other motor could be arranged to drive the shaft 140 via a gear drive, belt drive, or in any other suitable way.

A quick release tensioning device 150 is provided to permit of rapid slackening and subsequent tensioning of the belt. This facilitates replacement of a belt by permitting slackening of the belt by uncoupling of opposite ends of the belt in known manner to enable the belt to be removed and replaced by another belt for repair or to change grading size.

The device 150 comprises a manually engageable lever 151 at one end of a shaft 152 which extends transversely of the apparatus and is rotatable relative to bearings 153 carried on the sub-assembly 10a of the frame 10. The shaft 152 carries adjacent opposite ends arms 154 having a roller 155 at their free ends which are engageable with angle section members 156 fixed to the frame 10.

The sub-assembly 10a comprises a carrier having abutment flanges 10b which engage guide surfaces lox of the main frame 10 so as to be slidable relative to the frame 10 in a horizontal direction.

When the lever 151 is manipulated to turn the arms 154 clockwise in Figure 4, the reaction with the angle section members 156 causes the subassembly lOato slide to the left in Figure 4 and so tension the web. The web is slackened by moving lever 151 in the opposite direction.

The apparatus is provided with a presentation belt conveyor 160 driven by a further motor 161 carried by the frame 10 which drives a return roller 162 whilst the other return roller 163 idles. The presentation conveyor permits articles to be consistently presented to the grading web irrespective of how articles are delivered to the apparatus.

An unplugging roller 164 is provided upstream of the return roller 25 to push any product which has become trapped in a grading aperture out of the web. The roller 164 is driven by a chain, driven from a sprocket rotatable with the roller 25.

In Figure 9, a grading web 14 is trained around return means 12 and 13 which are cylindrical and rotated about fixed axes. The web is also trained around idler rollers 170. An agitating means 171 comprises a pair of agitating members 172 mounted for rotation by an arm 173 carried on a shaft 174. The shaft 174 is rotated by a suitably driven means from a motor, not shown. As the members 172 engage the web 14 they deflect it to the full line position from the dotted line position as shown in Figure 9, thereby repeatedly tensioning and slackening the upper run of the web 14.If desired, the agitating means may have one, or more than three, agitating members and may engage the web at another position to that shown in Figure 9. if desired, other means for moving one or more agitating members into and out of tensioning relationship with the web 14 may be provided including for example, a rectilinearly reciprocating arrangement driven by a "cam means" as hereindefined such as one of the reciprocating means for a return means described hereinbefore.

The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in the terms or means for performing the desired function, or a method or process for attaining the disclosed result, may, separately or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims

CLAIMS:

1. A web grader comprising an endless grading belt having a plurality of grading openings therein, the grading web being trained around spaced apart first and second web return means to provide a graded web upper run between said return means and a lower run disposed below the upper run, drive means for driving the web to advance articles to be graded along the upper run, a receiving means disposed below the upper run to receive articles which have passed through the openings of the web during passage along the upper run and agitating means to agitate the upper run to facilitate grading wherein the agitating means comprises means to slacken and tighten the web so as to cause the upper run to oscillate up and down, said agitating means comprising at least one member additional to said return means, having a surface which engages with the web only at a position spaced from said upper run.

2. A grader according to claim 1 wherein additional member is rotatable and at least one of non-circular and eccentric to the axis of rotation of the member

3. A grader according to claim 2 wherein the additional member has a surface of square, hexagonal, octagonal or other polygonal cross-section or is of non-circular curved cross-section such as elliptical or is of circular cross-section but disposed eccentrically to the axis of rotation of the member.

4. A grader according to claim 1 wherein the at least one additional member is oscillated in a direction towards and away from the web.

5. A grader according to Claim 4 wherein the or each oscillating additional member is mounted on a shaft which is guided for oscillation in a guide means.

6. A grader according to Claim 5 wherein the additional member shaft is caused to oscillate by an oscillator drive means.

7. A grader according to Claim 6 wherein the oscillator drive means comprises a cam means as hereindefined.

8. A grader according to Claim 6 or Claim 7 wherein the additional member shaft is caused to oscillate by an oscillator arm connected at one end to the additional member shaft and is driven to oscillate at the other end by the oscillator drive means.

9. A grader according to any one of Claims 6 to 8 wherein the oscillator drive means comprises a drive shaft which is adapted to be rotated by a motor and the drive shaft having said cam means to cause oscillation of the oscillator arm.

10. A grader according to any one Claims 7 to 9 wherein said cam means is disposed longitudinally outwards of the web and the oscillator arm extending from said cam means, to be connected to the additional member shaft, in a direction which extends generally horizontally and towards the web.

11. A grader according to anyone of the preceding claims wherein at least one return means comprises a rotatable member.

12. A grader according to Claim 11 wherein each return means comprises a rotatable member.

13. A grader substantially as hereinbefore described with reference to and as shown in Figure 9 or Figure 9 and Figures 1-3, or Figure 9 and Figures 4-8.