GB2092086A - Screw conveyor - Google Patents

Abstract

A forage harvester comprises a screw conveyor having multiple helices 1, 5, 6 and 3, 7, 8 respectively acting in opposite directions by which cut crop is compressed and fed to a chopping cylinder. The helices are of different lengths with the shortest helices 5, 6, 7, 8 located at or adjacent to the centre of the conveyor so as to compress the forage against a platform (18), not shown, and assist in conveying the forage to feed paddles 4 which further compress the forage while delivering it to spring loaded compression and feed rolls (13 to 16), not shown. <IMAGE>

Description

SPECIFICATION Improvements in or relating to forage harvesters This invention concerns improvements in or relating to forage harvesters and more particularly to apparatus of the kind known as precision chop or metered feed forage harvesters and which chop forage or other agricultural crop or the like raised from the ground into short lengths by a rotating set of knives generaily in the form of a cylinder with the knives projecting from the circumference, or a wheel with the knives mounted radially, which cut the forage against a counter knife, provisions being made either to cut the forage from the ground over a desired width in front of the machine or to provide a pick-up unit of desired width to raise pre-cut material from the ground or to provide a row crop (maize) harvesting unit.The raised material is fed to a screw conveyor designed to reduce the width of the material fed from either the cutter bar or pick-up unit or row crop unit to a width suitable for the feed roilers which feed the chopping cylinder. The chopped forage is then either thrown up a delivery chute by the chopping cylinder to a suitable collecting vehicle, or transferred by screw conveyor or direct to a fan of special type which throws the material through the delivery chute into the collecting vehicle. The apparatus of the above kind is normally built on a wheeled chassis, for towing over tha ground by an agricultural tractor which also drives it, but it can also be tractor mounted, self propelled or tractor towed with engine drive.

In particular the present invention concerns a development of the forage harvester described in our prior Patent Specification No. 1,570,781 according to which there is provided a forage harvester of the kind referred to that comprises in combination a screw conveyor, a pick-up unit for feeding crop to said screw conveyor, the latter comprising co-axial multiple helicles acting in opposite directions to precompress and feed the forage towards the centre or approximately the centre of the conveyor, a cutting or chopping cylinder adjacent to the feed position of the conveyor between the two sets of helices to which cylinder the compressed forage is directly fed by the conveyor.

Normal operating experience has shown that the multiple helix conveyor described in our said Patent Specification 1,570,781 gives improved metered feed and consequent control of chop length when using the described construction having triple right and left hand helices terminating in feed paddles. However in some crop conditions the triple helix adjacent to the outer ends of the screw conveyor have interrupted the smooth flow of material from the pick-up and the present invention is concerned with overcoming this interruption of flow whilst preserving the stated advantages which are the provision of an improved construction of screw conveyor for use with a forage harvester of the kind referred to which (a) gives an improved and direct feed, or alternatively an indirect feed by feed rollers, to the cutting cylinder of a metered feed forage harvester; (b) avoids the use of internal moving parts (c) is reliable in use and (d) less complicated and therefore less costly than conventional screw conveyors with retracting tines.

According to the present invention there is provided a screw conveyor for feeding cut crop to a chopping cylinder of a forage harvester, said screw conveyor having multiple helices acting in opposite directions to precompress and feed the forage towards the centre, or approximately the centre, of the conveyor, and which is characterised in that said helices are of different lengths and the shortest helices located at or adjacent to the centre of the conveyor so as to compress the forage still further. Such an arrangement results in the provision of a screw conveyor of increased feed capacity because of the open construction at each end of the conveyor combined with the improved control of feed and resulting length of chop effected by the shortest crop compressing helices located at or adjacent to the centre of the conveyor.

According to a preferred embodiment of the invention paddles are provided between the opposed inner ends of the multiple helices at or adjacent to the centre of the conveyor, these paddles yet further compressing the forage while delivering it to the chopping cylinder.

To enable the invention to be clearly understood and readily carried into effect a preferred embodiment thereof will now be described by way of example with reference to the accompanying drawings, wherein: Figure 1 is a perspective view of a screw conveyor constructed according to this invention, Figure 2 is a view of an apparatus constructed according to this invention looking from the front, and adapted for side mounting on an agricultural tractor, Figure 3 is a side view of Figure 2 looking towards the right hand side as viewed in a forward direction of travel, Figure 4 is a perspective view of an apparatus constructed according to this invention looking towards the front right hand side as viewed in a forward direction of travel and adapted to be towed and driven by an agricultural tractor.

Figure 5 is a diagram (on the centre line seen from the right hand side as viewed in a direction of travel) showing the relationship of a pick-up unit, the screw conveyor of this invention and a chopping cylinder, to which forage may be directly fed by the conveyor, Figures 6 to 8 are views of portions of the screw conveyor showing the helices thereof in different positions assumed during rotation of the conveyor, Figure 9 is a sectional side view showing how forage may be fed indirectly from the screw conveyor to the cutting cylinder by means of feed rolls and Figure 10 is a transverse cross section taken .through the centre of the conveyor indicating positions of feed paddles and the helices attached to them.

Referring to said drawings, the screw conveyor comprises, as viewed in Figure 1, a helix 2 at the right hand side and a helix 3 at the left hand side, the helices extending from a tube and being so arranged that the opposite inner ends of the helices at the feed position 1 of the conveyor are alternately from right and left and are at 1 800 to each other. The opposed inner ends of the helices at the feed position 1 will normally be on the centre line of the feed position but they can however be terminated before or past this centre line to suit the apparatus, and can be either plain or provided with six or any other appropriate number of feed paddles 4. These paddles 4 can be permanently welded into position or detachable mounted by bolts and can, with advantage, be replaceable by paddles of varying heights and widths to adjust and suit the machine for varying crop conditions.

This invention is characterised by the screw conveyor additionally comprising short helices 5, 6, 7 and 8, these said helices preferably extending 1 800 around the circumference of the screw conveyor and preferably being positioned to trail the main helices 2 and 3 at 1200 intervals and are alternately from left and right at 1 800 to each other. The opposed inner ends of the helices 5, 6, 7 and 8 at the feed position 1 will normally be on the centre line of the feed position but they can however be terminated before or past this centre line to suit the apparatus and can be either plain or provided with feed paddles. The opposed inner ends of helices 2, 3, 5, 6, 7 and 8 at the feed position are alternately from left and right at 600 intervals.

This design of screw conveyor thus comprises single helices starting from the outer ends and has a second and third helix on both the left and right hand side of the feed position of only 1800 length.

This arrangement improves the flow of material at the ends of the pick-up unit, particularly on wide units and still retains the pre-compression of the material at the feed position 1.

During operation the agricultural crop can easily flow from the outer ends of the pick-up into the area bounded by the main helix 2 or 3 and the centre tube of the conveyor. Guide plates and stripper bars of known design are placed behind the screw conveyor to prevent the agricultural crop from passing around the conveyor and as the conveyor rotates the short helices 5, 6, 7 and 8 compress the crop against the machine platform and assist in conveying the crop to the feed paddles 4 which further compress the crop whilst delivering it to the chopping cylinder.

Satisfactory results have been obtained by making the screw conveyor of this invention of the following dimensions but it is to be appreciated that these dimensions may be varied to suit requirements.

Length 1 800 mm Centre tube diameter 260 mm Diameter over helices 500 mm Projection of helix 120 mm Pitch of each helix 400 mm Inter-helix pitch 133.5 mm Length of short helix 1 800 arc From the foregoing it will be appreciated that the screw conveyor of this invention comprises multiple e.g. triple, conveying helices of different lengths at each side of its centre that act in opposite directions so as to pre-compress and feed the forage to the centre of the length of the conveyor and so gives an improved feed to the cutting and chopping cylinder and eliminates the use of any internal moving parts.

Due to the fact that the helices are, according to this invention, made of different lengths with the shortest helices located at or adjacent to the centre of the conveyor, no interruption of the smooth flow of material from the pick-up at the outer ends of the conveyor occurs.

The conveyor of this invention also gives a controlled metered feed that is adjustable by incorporating an interchangeable drive ratio between the cutting cylinder and the screw conveyor when the forage is fed directly from the conveyor to the cutting cylinder as illustrated diagrammatically by Figure 5, the chopped forage from the cutting cylinder being discharged through a chute 10, if necessary assisted by a fan.

It will also be understood from the foregoing that the screw conveyor may comprise six helices 2, 3, 5, 6, 7, 8 (Figure 1) or any greater number of helices and built to any reasonable dimensions with normally the feed position 1 to the chopping or cutting cylinder in approximately the centre of the conveyor, but this is not an essential feature and the feed position can be arranged to suit the particular forage harvester to which the conveyor is to be fitted.

The forage harvester to which the apparatus of this invention is fitted may of course be provided with a pick-up unit 9 as shown in Figures 1, 2, 3, 4 and 5 for raising pre-cut forage, or alternatively with a cutter bar for harvesting a crop, or row crop (maize) harvesting unit.

The various angles referred to above are given as examples of suitable arrangements and may of course be varied as required.

According to a further modification, not illustrated, retracting tines may be fitted in the feed position between multiple helices.

The invention also embraces a forage harvester that is a maize harvester for one or more rows, said machine including a screw conveyor constructed as hereinbefore previously described.

As previously explained the forage may be fed directly from the screw conveyor to the chopping cylinder, or alternatively, indirectly by means of feed rolls. This alternative arrangement is illustrated by Figure 9. During operation the agricultural crop "C" can easily flow from the outer ends of the pick-up 9 into the area of the screw conveyor bounded by the main helix 2 or 3 and the centre tube of the conveyor.Guide plates and stripper bars of known design are placed behind the screw conveyor to prevent the agricultural crop from passing around the conveyor and as the conveyor rotates the short helices 5, 6, 7 and 8 compress the crop against the machine platform 1 8 and assist in conveying the crop to the feed paddles 4 which further compress the crop whilst delivering it to spring loader compression and feed rolls, 13, 14, 1 5 and 1 6. A scraper 1 7 is fitted to clean the smooth roll 15 and guide the crop over the counter knife 12 whilst delivering it to the chopping cylinder.

Referring lastly to Figure 10 that illustrates still further the arrangement of the helices of the screw conveyor, this view shows the position of the feed paddles 4 against which have been indicated the reference numerals of the helices 2 to 8 attached to said paddles.

The said cutting cylinder is preferably, although not essentially, fitted with knives 11 (Figure 5) made in accordance with the invention described in our prior Patent Specification No. 1 559322.

Briefly according to our said Patent Specification No. 1 559322 there is provided a cutting or chopping cylinder for a forage harvester of the kind referred to wherein each knife 11 is made so as to yield and deform and bend backwards away from its counter knife 12 and casing in the event of a foreign body, e.g. a stone passing into the cylinder and becoming wedged between said parts whereby any damage is limited to the actual knife and does not extend to adjacent parts of the mechanism.

The length of the chop may be varied to suit requirements by changing the drive ratio between the chopping cylinder and the screw conveyor.

Claims (8)

1. A screw conveyor for feeding cut crop to a chopping cylinder of a forage harvester, said screw conveyor having multiple helices acting in opposite directions to precompress and feed the forage towards the centre, or approximately the centre, of the conveyor, and which is characterised in that said helices are of different lengths and the shortest helices located at or adjacent to the centre of the conveyor so as to compress the forage still further.

2. A screw conveyor according to Claim 1, wherein paddles are provided between the opposed inner ends of the multiple helices at or adjacent to the centre of the conveyor, these paddles yet further compressing the forage while delivering it to the chopping cylinder.

3. A screw conveyor according to Claim 2, wherein said feed paddles are permanently affixed to said helices.

4. A screw conveyor according to Claim 2, wherein said feed paddles are detachably secured to said helices.

5. A screw conveyor according to Claim 4, including the provision of paddles of varying heights and widths by which said detachabie paddles can be replaced so as to adapt the harvester to suit varying crop conditions.

6. A screw conveyor according to any of the preceding claims, including the provision of retracting tines fitted in the crop feeding position between the multiple helices.

7. A scew conveyor for feeding cut crop to a chopping cylinder of a forage harvester constructed and adapted to function substantially as hereinbefore described with reference to and as illustrated by the accompanying drawings.

8. A forage harvester fitted with a screw conveyor for compressing and feeding crop to a chopping cylinder, as claimed in any of the preceding claims.