WO2001033938A1

WO2001033938A1 - Conveyor system

Info

Publication number: WO2001033938A1
Application number: PCT/GB2000/004204
Authority: WO
Inventors: David John Mountain
Original assignee: Harpley Engineering Limited
Priority date: 1999-11-06
Filing date: 2000-11-03
Publication date: 2001-05-17
Also published as: GB0210036D0; GB2371464A; AU1157201A; GB9926245D0; GB2371464B; WO2001033938B1

Abstract

A conveyor system has at least a pair of elongate rolls (13) having circumferential outer surfaces (15) and a respective helical conveying blade (16) projecting from each such surface. The rolls (13) are mounted with their axes substantially parallels, with a pre-defined gap between their outer surfaces (15). Power drive means (17) is arranged to effect simultaneous rotation of both rolls (13) whereby an article to be conveyed and resting on both rolls is advances along the length thereof by the action of the helical blades (16). There is a mounting arrangement (20, 30) for the entire outer surface, or possibly at least an axial section of the outer surface (Fig. 5), of at least one of the rolls which permits the entire surface, or just said section, resiliently to move away from the other roll.

Description

CONVEYOR SYSTEM

This invention relates to a conveyor system and in particular, but not exclusively, to a conveyor system suitable for use in the agricultural industry, for transporting agricultural produce through a produce processing machine such as a root crop cleaner. Further, this invention relates to a root crop cleaner whenever provided with such a conveyor system.

A known form of conveyor system has a pair of elongate rolls arranged side by side and with their axes parallel, but with a small gap between the outer surfaces of the rolls. Each roll has a helical blade projecting from its circumferential surface and extending from one end of the roll to the other. A power drive arrangement rotates the rolls so that the respective helical blades will convey an article placed on both rolls at one end to the other end of those rolls, for discharge to some other conveyor or processing equipment.

In the agricultural industry, there are various machines for cleaning root crops lifted from the ground. Often, such crops are encrusted with soil and it is desirable to clean that soil from the crops at the time of lifting so that the removed soil may be deposited back on the ground; if the cleaning operation is left until later and is performed by a fixed installation, there is the problem of disposing of the removed soil collected at the time of cleaning. A lifting machine cannot carry a large volume of water for the cleaning of the root crops, nor can a towed cleaning machine and so some other technique must be adopted for removing soil clinging to the lifted crops.

It has been proposed to employ a conveyor system of the kind described above for the purpose of cleaning lifted root crops. This has the advantage that the blades of the two rolls, on driving the crops along the conveyor system also fulfil the function of cleaning soil from the crops. This is found to work quite effectively, unless a large stone or similar hard object is clinging to a lifted item. In such a case, the blades are likely to remove the stone or other object and if that object is too large to fall through the gap between the two rolls, it is highly likely that the conveyor system will jam.

In view of the above problem, it is known to fit some kind of safety device to a conveyor system of the kind described above, when employed for the cleaning of lifted root crops. In view of the availability of hydraulic power on a tractor towing a mobile cleaner, the rolls are normally driven by a hydraulic motor. In this case, the safety device may comprise some kind of pressure relief valve in the hydraulic line to the motor. In the event that the motor stalls, the pressure is relieved and damage to the rolls and motor is obviated. It has been proposed to improve this safety device by reversing the flow to the motor, typically for a pre-defined period, on sensing staling of the motor, so that the object blocking rotation may be wound back to the inlet end of the conveyor system for manual removal before the motor is restarted in the conveying direction. Despite the above proposals, it is found in practice that damage still occurs to the rolls or the conveying blades, or even to the hydraulic system, in the event that a relatively large object is picked up by the crop lifter and is transferred to the conveying system within the cleaning machine. The present invention aims at improving the prior proposals for reducing damage to the conveying system, in the event of a jam caused by a relatively large, hard object being picked up by a crop lifter and transferred to the cleaning machine, though it will be understood that the proposed solution of this invention is applicable to such a conveying system used other than for the cleaning of lifted crops. According to the present invention, there is provided a conveyor system comprising a pair of elongate rolls having circumferential outer surfaces and mounted with their axes substantially parallel with a pre-defined gap between the circumferential surfaces, a respective helical conveying blade projecting from the circumferential surface of each of the rolls, and power drive means to effect simultaneous rotation of both rolls whereby an article to be conveyed and resting on both rolls is advanced along the length thereof by the action of the helical blades, in which system there is a mounting arrangement for the circumferential surface of at least one of the rolls which permits at least a section of the circumferential surface of said at least one of the rolls resiliently to move away from the other roll.

In the present invention, at least one of the rolls of the conveyor system includes a mounting arrangement whereby the gap between the two rolls may increase, so as to permit a relatively large object (such as a large stone picked up with an item of produce) to drop between the rolls. It will be appreciated that the present invention in effect offers two, but very closely related, solutions to this problem. In one solution, the circumferential surface of at least one of the rolls may be divided into a plurality of axial sections each of which carries a part of the overall helical conveying blade and each section is mounted on a core for the roll in such a way that each section may move in a radial direction independently of the other sections. Thus, an object which otherwise might jam the rotation of the two rolls may force the section engaged by that object away from the other roll so increasing the gap and allowing the object to fall through. In the alternative solution, at least one of the rolls may be mounted for resilient movement generally in the plane containing the axes of the two rolls. That roll may thus move as a whole, away from the other roll, so increasing the gap between the rolls and permitting the object to fall through.

With either solution discussed above, both rolls may be similarly arranged for movement away from the other roll. Thus, in the first solution both rolls may be divided into a plurality of axial sections and each section of each roll may move away from the other roll. In the second solution, each roll may be mounted for resilient movement away from the other roll.

For the case where a roll is divided into a plurality of axial sections, the mounting arrangement for those sections may take a variety of forms. For example, an elastomeric carrier may be provided between a shaft for the roll and each section, which carrier has a plurality of vanes each of which is of a greater radial length than the gap between the shaft and the inner surface of each section, when concentric with the shaft. Each vane will thus take up a curved form, which will allow any one section to move in the radial direction whilst the vanes still fully support that section. Though a separate carrier could be provided for each section, conveniently a single carrier extends for the entire length of the roll and each of the sections is slid on to the carrier at the time of assembling the roll. Another possibility would be to fill the space between the roll core and each outer section with a resilient foamed elastomeric material, whereby radial movement of any one or more sections is permitted by resilient deformation of that foamed material. For the case where each roll has a unitary circumferential surface, the mounting arrangement should permit the entire roll to move away from the other roll. Conveniently, the mounting arrangement permits movement of each end of the roll independently, whereby the roll may move out of parallel with the other roll, for example if a relatively large object is to pass between the rolls at or adjacent one end thereof. This may be achieved by supporting the two ends of the roll on respective swinging arms, and biasing means being arranged to urge the swing arms to a rest position where the axis of the roll is substantially parallel to the axis of the other roll, with the pre-defined gap between the circumferential surfaces thereof.

The biasing means may comprise mechanical springs, such as helical compression springs acting on the swinging arms. Alternatively, a block of elastomeric material may fulfil this function, or a pneumatic or hydraulic actuator appropriately disposed to act on the mounting for the roll. In any of these case, it is advantageous to allow at least one of, but possibly both, of the spring rate and the spring force to be adjusted to suit the particular operation to which the conveyor system is to be put.

Particularly in the case of the cleaning of root crops, the conveyor system may have three or more similar rolls all arranged with their axes substantially parallel. For a three roll system, at least the central roll should have a mounting arrangement permitting it to move away from either of the two rolls. For a system having three or more rolls, at least one of the rolls defining in association with another roll a gap through which an object is to pass should have a mounting arrangement permitting that roll to move away from said another roll. Conveniently, however, all of the rolls of the conveyor system may be similarly arranged, so that each may have its circumferential surface moveable away from its adjacent rolls.

The circumferential surface of each roll may be truly cylindrical, or could be polygonal, in cross-section. Moreover, the surface could be defined by sheet material, and so be continuous in the circumferential direction, or could be defined by a framework of frame members - for example circumferential ribs spaced along the roll axis and carrying bars extending parallel to the roll axis. This invention extends to a root crop cleaning machine or a root crop harvester when incorporating an integral cleaning machine, whenever provided with a cleaning conveyor system of this invention as described above.

By way of example only, one specific embodiment of conveyor system of this invention and certain modifications thereof will now be described in detail, reference being made to the accompanying drawings, in which:-

Figure 1 is a plan view on the embodiment of conveyor system;

Figure 2 is an end view on the conveyor system of Figure 1;

Figure 3 is a detail view on one end of a roll used in the conveyor system of Figures 1 and 2;

Figure 4 is a detail view on a mounting pin for the other end of a roll;

Figure 5 is a detail view on an alternative form of roll for use in the conveyor system of Figure 1;

Figure 6 is a detail view on a further alternative form of roll; Figure 7 diagrammatically illustrates a part of a root crop cleaning machine incorporating the conveyor system: and

Figure 8 is a diagrammatic end view on the machine of Figure 7.

Referring initially to Figures 1 and 2, there are shown the important parts of a conveyor system constructed and arranged in accordance with this invention. The conveyor system comprises a frame 10 having cross members 11 and 12 at its two ends, on which are supported four rolls 13, each of a similar construction. Each roll 13 has a shaft 14 and a cylindrical outer shell 15 to which is secured a helical conveyor blade 16, extending from one end of the roll to the other. Adjacent rolls have their respective blades 16 wound with oppositely-handed helixes, as can be seen from Figure 1. Each roll has an hydraulic motor 17 arranged at one end thereof, to effect rotation of the roll.

Each roll is supported on a pair of swing arms 19 and 20, disposed one at each end of the roll. At the motor drive end of the roll, the swing arm 19 is carried at its lower end on a universal coupling 21 , secured to cross member 11. The upper end of the swing arm 19 carries the motor 17 with also provides a bearing for one end of the roll shaft. At the other end of the roll, the swing arm 20 is mounted on a mounting pin 22 (Figure 4) journalled to cross member 12 and bolted to the swing arm itself. At the upper end of each swing arm 20, there is a mounting plate 23 carrying a bearing 24 for the roll shaft.

Between adjacent hydraulic motors 17, there is provided a rubber buffer 26, arranged to urge apart the adjacent motors. Similarly, between the motors 17 of the outer swing arms 19 and the adjacent frame members 27, there are further buffers 28 arranged to urge the two outer swing arms inwardly. The buffers are located in receptors 29 provided on the opposed faces of each motor 17, to hold the buffers in position despite swinging movement of the arms 19, with consequent deformation of the buffers. In a similar way, buffers 30 are provided between adjacent mounting plates 23, to urge apart the adjacent mounting plates. Also, between the mounting plates 23 of the two outer swing arms 20 and the adjacent frame members 27, there are further buffers 31 arranged to urge the two outer swing arms inwardly. The spring forces and the spring rates of all of the buffers 26, 28, 30 and 31 are selected so that when relaxed, all of the swing arms 19,20 extend substantially vertically from the respective lower cross members 11 and 12 and with a pre-determined gap between the rolls. However, any one roll may move away from the other rolls, by deformation of the buffers associated therewith, in effect so increasing the gap between that roll and an adjacent roll. As will be appreciated, the hydraulic motors are appropriately powered so that adjacent rolls are rotated in opposite senses. An article deposited at the correct end of the rolls so as to be carried by two adjacent rolls will then be threaded along the length of the conveyor system by the blades 16 on the rolls and be discharged from the further end of the conveyor system. Should however a relatively hard body (such as stone 33 shown in Figure 2) drop partially between the rolls, so tending to jam the rolls against rotation, the two rolls may move apart against the resilient bias provided by the buffers associated with those rolls and the body may then drop through the increased gap, as shown in Figure 2. In this way, the conveyor system displays a high resistance to jamming by an unwanted hard object falling within a particular size range and which otherwise could cause serious damage to the conveyor system or component parts thereof, or the hydraulic drive system. ln the arrangement of Figures 1 to 4, each roll is a unitary structure having an integral shaft 14, which shaft is carried on the swing arms 19, 20 whereby the entire roll may move away from an adjacent roll against the spring bias of the buffers. As an alternative, the roll may have a shaft 35 which is supported in bearings fixed to the frame 10, the roll having a cylindrical outer shell 36 assembled from a plurality of similar cylindrical sections 37 (Figure 5). Each such section carries a part only of the helical blade but the sections are disposed with respect to one another so that the helical blade is essentially continuous from one end of the roll to the other. In Figure 5, the helical blade is shown as a series of short strips 38 each secured to the outer surface of the cylindrical section but with the sections so disposed that the strips 38 make up the helical blade.

The cylindrical sections 37 are supported on the shaft 35 by a foamed elastomeric material 39 which preferably is formed in situ, when the sections have been assembled around the shaft. Thus, any one cylindrical section 37 may move radially out of alignment with the other sections as shown in Figure 5, should for example a stone or similar hard object 40 jam between adjacent rolls.

Figure 6 shows an alternative mounting arrangement for the cylindrical sections 37. In this arrangement, there is an elastomeric extrusion 41 having a hub 42 bonded to the shaft 35, there being six resilient vanes 43 projecting generally radially from the hub. Each vane has a greater radial length than the gap between the hub 42 and the inner surface of the cylindrical section, so that the vanes take up a curved profile, as shown in Figure 6, when the cylindrical section is fitted over the extrusion 41. By straightening of the vanes on one side of the shaft and further curving of the vanes on the other side of the shaft, the cylindrical section may move out of a position concentric with the shaft, as shown in long chain lines 44, in Figure 6.

A single extrusion 41 may be provided for a complete roll, which extrusion supports all of the sections of the roll, side by side. In this case, movement of one section in the radial direction will affect the adjacent sections to some extent. In the alternative, the extrusion could be divided along the length of the roll with the divisions aligned with the inter aces between adjacent sections.

In all of the above embodiments of roll, the outer surface is shown as being continuous and of circular cross-section. It would be possible to use rolls of a polygonal cross-section, such as square or octagonal cross-section.

Moreover, the outer surface could be defined by spaced bars extending parallel to the roll axis and supported on axially-spaced ribs mounted on the roll shaft.

Figures 7 and 8 diagrammatically illustrate a part of a root crop cleaner which includes the conveyor system described above to assist with the cleaning function. This cleaner has a frame 45 carried on ground wheels 46, the frame being provided with a tow bar 47 for connection to a tractor. A root crop lifter, arranged for the lifting of a particular root crop such as sugar beet, discharges the lifted crop on to an input conveyor 48, which discharges the crop into a pre- cleaner 49, arranged to break off the crop large clumps of soil still adhering thereto. The pre-cleaner deposits the crop on to the conveyor system 50 of this invention as described above. As the crop moves along the conveyor system, the conveying blades 16 further clean the crop and break away most of the remaining soil adhering to the crop. At the output end 51 of that conveyor system, the crop is fed to a loading conveyor 52 which lifts the crop up for discharge into a suitable receptacle such as a trailer towed behind another tractor.

In the event that a relatively large stone or some other foreign body is not removed by the pre-cleaner, it will be deposited on the conveyor system 50. Should that body be sufficiently hard and of a size too large to fall through the gap between the rolls but still smaller than the expected smallest item of crop, there is the possibility that the body will tend to jam the conveyor. However, by allowing the rolls to separate in the manner described above, or allowing a cylindrical section of at least one of the rolls to separate, that body which otherwise might jam the conveyor may harmlessly fall through to the ground, without interrupting the action of the conveyor.

Claims

1. A conveyor system comprising a pair of elongate rolls having circumferential outer surfaces and mounted with their axes substantially parallel with a pre-defined gap between the circumferential surfaces, a respective helical conveying blade projecting from the circumferential surface of each of the rolls, and power drive means to effect simultaneous rotation of both rolls whereby an article to be conveyed and resting on both rolls is advanced along the length thereof by the action of the helical blades, in which system there is a mounting arrangement for the circumferential surface of at least one of the rolls which permits at least a section of the circumferential surface of said at least one of the rolls resiliently to move away from the other roll.

2. A conveying system as claimed in claim 1 , wherein the circumferential surface of said at least one of the rolls is divided into a plurality of axial sections each of which carries a part of the helical conveying blade and the mounting arrangement supports each section on a roll core for resilient movement away from the other roll, independently of the other sections.

3. A conveying system as claimed in claim 2, wherein each axial section of said at least one of the rolls is supported on a plurality of resilient arms secured to the roll core. 4. A conveying system as claimed in claim 2 or claim 3, wherein the roll core comprises a rotatably mounted shaft which supports all of the sections.

5 . A conveying system as claimed in any of claims 2 to claim 4, wherein both of the rolls are divided into a plurality of axial sections, each of which sections carries a part of the helical conveying blade of the respective roll and each of which sections is resiliently mounted on a respective roll core for movement away from the other roll.

6 . A conveying system as claimed in claim 1 , wherein each roll has a respective unitary circumferential surface, and the mounting arrangement for the circumferential surface of said at least one of the rolls permits the entire roll to move away from the other roll.

7. A conveying system as claimed in claim 6, wherein each end of said at least one of the rolls is supported on a respective swing arm, biasing means being provided to urge the swing arms to a rest position where the axis of the roll is substantially parallel to the axis of the other roll, with a pre-defined gap between the circumferential surfaces of the two rolls.

8. A conveying system as claimed in claim 6 or claim 7, wherein spring means is provided to urge the circumferential surface of one roll towards the circumferential surface of the other roll.

9. A conveying system as claimed in claim 8, wherein the spring means comprises one of a block of an elastomeric material or a mechanical spring.

10. A conveying system as claimed in claim 8, wherein the spring means comprises a pneumatic or hydraulic actuator acting on the mounting for the roll. 11. A conveying system as claimed in any of claims 8 to 10, wherein at least one of the spring force and the spring rate of the spring means is adjustable. 12. A conveying system as claimed in any of claims 6 to 11 , wherein the mounting arrangement supports both of the rolls for resilient movement away from the other roll. 13. A conveying system as claimed in any of the preceding claims, wherein there are three or more rolls mounted with their axes substantially parallel, and the circumferential surface the or each roll having a further roll to each side thereof having a mounting arrangement which permits at least a section of that circumferential surface to move resiliently away from the rolls to each side thereof.

14. A conveying system as claimed in claim 13, wherein all of the rolls are mounted for resilient movement towards and away from the adjacent rolls.

15. A conveying system as claimed in claim 14, wherein spring means is arranged between adjacent rolls to act thereon, so that the forces resiliently biasing the rolls are balanced across the rolls thereby maintaining the rolls in a rest position but away from which any one or more rolls may move in a resilient manner.

16. A conveying system as claimed in claim 15, wherein there are three or more rolls arranged with their axes substantially parallel, the mounting arrangement supporting all of the rolls for movement towards and away from the others.

18. A root-crop harvester whenever provided with a conveying system as claimed in any of the preceding claims.