GB2171583A - Comminuting straw and the like stalks of agriculture material - Google Patents

Abstract

Apparatus for pulverising and crushing straw and stubble left on a tract of land after grain harvesting and returning the comminuted produce back onto the land for subsequent incorporation into the soil comprises a pair of relatively moving members (14, 22) which define a gap (26) therebetween. The straw is drawn into the gap and in passing therethrough is crushed and pulverised by first (15) and second (24) bars which are inclined one to the other. <IMAGE>

Description

SPECIFICATION Improvements in and relating to comminuting straw and the like stalks of agricultural material This invention relates to a method of, and to apparatus for reducing the length of stalk-like agricultural produce. The invention has particular application to the treatment of grain stalks (herein referred to as straw) as a precursortothe incorporation of the straw into the soil.

Traditionally, waste straw, left on a land tract after grain harvesting, has been disposed of by burning in situ, the post-burnt material then being ploughed into the soil. Powerful anti-burning lobbies have imposed restrictions on straw burning which makes this traditional disposal method difficult to perform.

This invention seeks to provide an alternative to straw burning which avoids such problems.

According to one aspect of the invention there is provided a method oftreating stalk-like agricultural produce left on a tract of land which comprises lifting the stalk-like produce from the land and feeding it into a gap between relatively moving members so that the produce is pulverised in the gap to reducethe length of stalks in the produce and simultaneously crush the stalks and depositing the thus pulverised and crushed produce back onto the land.

Suitably the method is conducted shortly after combining and preferably after combining with a combine harvester equipped with a straw spreader to spread the straw discharged from the combine harvester substantially uniformly over the land tract.

Conveniently the gap is created between an endless surface moving below an overlying cowl, the endless surface and the cowl each having spacedapart crushing bars protruding into the gap, which bars on one of the members are inclined with respect to the bars on the other member. The endless surface can be a rollerwith part-helical bars thereon extending from end to end. Coacting with part-helical bars on a roller can be further bars on the cowl which further bars are generally parallel to the axis of rotation ofthe roller.

The method can pulverise and crush notonlythe loose straw lying on the ground but can also uproot and crush the stubble leaving a layer of treated straw which is in suitable form for ploughing under. Since the method, in its preferred embodiments, returns the straw to the land closeto where it removed it from the land for pulverising and crushing,the method ofthe invention can be used to rapidlytreata uniform layer of straw and stubble and leave a uniform layer of pulverised and crushed strawfor ploughing under.

Where a roller with part-helical bars is used, it may be mounted in a wheeled carriage and can be driven so that its circumferential speed substantially matches the speed of advance of the carriage over the land, the direction of rotation of the roller being such that its surface closest to the land is moving in the direction of advance of the carriage.

The cowl can be spring-urged towards the roller and subtends an angle of between 90 and 180 atthe centre of the roller.

According to a further aspect of the invention, straw comminuting equipment comprises a frame, a first member defining an endless surface rotatably mounted in the frame, a second member partially overlying the first member to define therewith a gap which extends substantially from side to side ofthe frame, straw comminuting bars spaced-apart on each ofthefirstand second members, which bars project into the gap, the bars on one ofthe members being skew with respect to the bars on the other member, pressure-generating means to urge the bars on the respective members within the gap towards one another and drive means for rotating the first member relative to the second to draw straw into and throughthe gap where itcan be subjected to shearing and grinding forces as it passes the relatively moving bars.

Suitably the frame is provided with groundengaging wheels which are adjustable to enable the rotating axis of the first memberto be set at a desired heightabovetheground.

Conveniently the frame is designed to be connected to a tractor (normally atthe rearend thereof), the drive means forthefirst memberthen suitably being connected to the power take off ofthe tractor.

The frame is conveniently designed so that the rotating axis of the first member is parallel to the ground but inclined to the direction of advance ofthe frame across the tract of land.

The invention will how be further described, by way of example, with reference to the accompanying drawing, in which: Figure lisa plan from above of straw comminuting equipment according to the invention, Figure 2 is a partially sectioned side elevation of the equipment of Figure 1 ,and Figure 3 is a partially sectioned end elevation of the left-handendoftheequipmentofFigure 1.

The equipment shown in Figure 1 is trailed by a tractor (not shown) connected to a tow bar 10. The equipmentcomprisesaframe 11 provided with idler wheels 12,13 of adjustable height.

Rotatably mounted in the lower part of the frame 11 is a heavily constructed circular cylindrical roller 14 having rectangularsection bars 15 fixed to its surfaceinpart-helicaldisposition.The roller 14is driven by a ch.ain (or belt) drive 16, via drive wheels (sprockets are illustrated) 17,18, a drive shaft 19 and a gear box 20. The input shaft 21 ofthe gear box is connected to a powertake off of the tractor.

Sprung mounted within the frame 11 is a cowl 22 (two of the springs are shown at 23) which supports, on its underside, further rectangular section bars 24, these bars being straight (parallel to the axis ofthe roller 14) and thus skew to the bars 15 on the roller 14.

A suitable stop means can be provided on the frame 11 to prevent the bars 15,24 actually contacting each other.

The cowl 22 is shown (Figure 2) to subtend an angle of some 115 atthe centre ofthe roller 14, but is provided with an inlet guide plate 25which effectively increases this angle in the forward direction.

The cowl can be extended at the rear end also, should this be necessary.

In use, the roller 14 is driven so that its peripheral speed matches (to within 10% or so) the advance speed of the equipment over the land in the direction of the arrow A in Figure 1. Straw (which can be lying on the ground and/or still standing) is led into the gap 26 between the roller 14 and the cowl 22 and because of the at ieast substantial match between the speed of the contra-rotating roller 14 and the advance speed of the frame 11,is drawn up into the gap where it is "minced" (i.e.

crushed and pulverised) between the skew bars 15, 24. The springs 23 allow the cowl to ride upwards and downwards as the volume of straw in the gap 26 increases and decreases while maintaining strong shearing forces on the straw in the gap.

Because of the skew disposition of the bars 15 on the roller 14, the position of closest approach between any given bar 15 and a confronting bar 24 will move axially along the roller 14 as the latter turns in the direction of the arrow B (Figure 2), and the pitch of the part-helical bars 15 is chosen so that one end of a given bar 15 is confronting the next upstream bar 24 before the other end has passed belowthe next downstream bar24. Four bars 15 are shown on the roller 14 and three bars 24 are shown on the underside of the cowl 22, but these numbers are not thought to be critical.

As the straw leaves the gap 26 at its downstream end, it drops back onto the land surface broken down into pieces a few centimetres in length in which state it can easily be ploughed under by a following plough, or in a subsequent ploughing operation.

From Figure 1 it can be seen that the axis of the roller 14 is inclined somewhat to the direction of travel A. This is an advantageous arrangement, since it allows excess straw at one position ahead of the equipment to be spread across the front of the roller and allows stones or other uncrushable objects to be pushed out of the path of the equipment past the wheel 13.

Existing straw choppers either combine mounted or separate tractor mounted or trailed machines use high speed flails or a similar system to chop straw between a bank of static knives using a fair amount of power to maintain speed. The equipment described here pulverises and crushes the straw over a substantial width (e.g. up to 4 metres) using a comparatively slow moving rotor 14 heavily constructed, and having part helical bars 15 welded round its circumference. This rotor, running close to the ground, contra rotates against the line of travel creating a lifting tearing action forcing the straw under the sprung cowl 22 having its opposing bars 24 against which the straw is crushed and sheared.

The frame 11, being mounted on adjustable height wheels 12, 13, allows ease in setting the optimum heightforeach comminuting operation and is drawn over the ground at an angle to a line of travel A to ensure that both loose straw and stubble over the whole land surface is treated in a series of adjacent passes.

It is expected that the greatly reduced power required to comminute straw by a mincing and crushing action (compared with the known chopping action) will permit advance speeds of around 5 mph (8 kph) to be achieved thus permitting something in excess of 4 acres of a stubble-strewn land tract to be prepared for ploughing in each hour.

Since the equipment described does not effect any significant transport of the straw it receives (transversely or in the direction of travel of the equipment) it works best on a freshly harvested tract where the combined harvester has been fitted with a straw spreader. The uncut stubble and the uniformly laid loose straw are drawn up together into the gap 26 and are redeposited as a substantially even layer of crushed and pulverised straw (with the roots and some earth drawn up into the gap as the stubble is torn up) suitable for early ploughing back into the soil.

Claims (15)

1. A method of treating stalk-like agricultural produce left on a tract of land which comprises lifting the stalk-like produce from the land and feeding it into a gap between relatively moving members so that the produce is pulverised in the gap to reduce the length of stalks in the produce and simultaneously crush the stalks and depositing the thus pulverised and crushed produce back onto the land.

2. A method as claimed in claim 1, in which the gap is created between an endless surface moving below an overlying cowl, the endless surface and the cowl each having spaced-apart crushing bars protruding into the gap, which bars on one of the members are inclined with respect to the bars on the other member.

3. A method as claimed in claim 2, in which the endless surface is a milerwith part-helical bars thereon extending from end to end.

4. A method as claimed in claim 3, in which coacting with part-helical bars on the roller are further bars on the cowl which further bars are generally parallel to the axis of rotation of the roller.

5. A method as claimed in claim 3 or claim 4, in which the roller with part-helical bars is mounted in a wheeled carriage and is driven so that its circumferential speed substantially matches the speed of advance of the carriage over the land, the direction of rotation of the roller being such that its surface closest to the land is moving in the direction of advance of the carriage.

6. A method as claimed in any preceding claim, in which stubble and straw are treated together, the stubble being torn out of the land as the gap passes over it.

7. A method as claimed in any of claims 2 to 6, in which the cowl is spring-urged towards the roller and subtends an angle of between 90 and 180O at the centre ofthe roller.

8. A method as claimed in any preceding claim, in which the comminuted produce deposited back onto the land is reduced to a few centimetres in length.

9. A method as claimed in any preceding claim, in which the gap into which the produce is fed is advanced at speeds of up to 5 mph (8 kph).

10. A method of treating stalk-like agricultural produce substantially as hereinbefore described with reference to the accompanying drawing.

11. Straw comminuting equipment comprising a frame, a first member defining an endless surface rotatably mounted in the frame, a second member partially overlying the first member to define therewith a gap which extends substantially from side to side of the frame, straw comminuting bars spacedapart on each of the first and second members, which bars project into the gap, the bars on one of the members being skew with respect to the bars on the other member, pressure-generating means to urge the bars on the respective members within the gap towards one another and drive means for rotating the first member relative to the second to draw straw into and through the gap where it can be subjected to shearing and grinding forces as it passes the relatively moving bars.

12. Equipment as claimed in claim 11, in which the frame is provided with ground-engaging wheels which are adjustable to enable the rotating axis of the first member to be set at a desired height above the ground.

13. Equipment as claimed in claim 11 or 12, in which the frame is designed to be connected to a tractor, the drive means for the first member being connected to a power take-off shaft of the tractor.

14. Equipment as claimed in claim 11, 12 or 13, in which the frame is designed so that the rotating axis of the first member is parallel to the ground but inclined to the direction of advance of the frame across the tract of land.

15. Strawcomminuting equipment substantially as hereinbefore described with reference to and as illustrated in the accompanying drawing.