GB2116834A

GB2116834A - Machine for chopping straw

Info

Publication number: GB2116834A
Application number: GB08302941A
Authority: GB
Inventors: Gerald Priday Evans
Original assignee: Agri Tech Ltd
Current assignee: Agri Tech Ltd
Priority date: 1982-02-05
Filing date: 1983-02-03
Publication date: 1983-10-05
Also published as: GB2116834B; GB8302941D0

Abstract

A straw chopping machine designed to be driven by and supported from a tractor includes a rotary cutter 13 having a row of spaced discs 17 each carrying four pivoted blades 20, a corresponding row of stationary abutment ribs 25 interposed between the cutter blades and means for adjusting the ribs 25 inwards and outwards in relation to the blades. Each rib extends across the whole of the entry chute and is cranked at 27 providing two spaced cutting zones. The bales are fed at a controlled rate down the chute by a conveyor 40 and a star wheel 41 driven at a speed related to that of the cutter shaft 19. <IMAGE>

Description

SPECIFICATION Machine for chopping straw This invention relates to machines for cutting or chopping straw, hay, or like material and is particularly, though not exclusively applicable to a machine for chopping straw or hay in the bale.

Severai machines of this general type already exist, but in general they suffer from a variety of limitations and disadvantages. They are usually limited in the quantity of material which can be cut at any time, they are prone to internal clogging, they do not provide a free exit path which will allow the chopped material to be thrown out any appreciable distance, and they cannot be easily altered or adjusted to handle bales of different materials, packed to different densities and of different weights.

Accordingly it is an object of the invention to provide an improved power operated cutting machine which will meet some of the existing problems.

Broadly stated the invention consists in a machine for cutting straw or like material, comprising a rotary power driven cutter with a series of axially spaced projecting blades or cutters, and a series of interposed stationary abutments, and means for feeding bales of straw or the like against the rotary cutter such that material is chopped off and removed from the bale.

From one aspect the invention consists in a machine of the type referred to above in which the abutments are radially adjustable relative to the axis of the cutter to vary the projection of the cutter blades. Preferably the abutments are adjustable in unison, and in a particular preferred construction the abutments extend around an arc greater than a quadrant of the cutter. Conveniently the abutments are adjustable each at one end and are pivotally and/or slidably adjustable at the other end.

From yet another aspect the invention consists in a machine of the type referred to including two or more arcuately spaced chopping zones. According to a particular preferred feature of the invention there is a gap btween two such zones sufficient to prevent clogging. Thus, in one preferred construction each abutment extends over part of the periphery of the cutter and there is an interruption or gap between this arcuate part and an adjacent fixed abutment aligned with the said part. Preferably each abutment is stepped radially inwards or outwards to form a gap between first and second chopping zones.

The invention also resides in a machine of the general type referred to, including means for feeding material such as bales of straw towards the cutter, comprising a pair of power operated feed devices on opposite sides of a chute or entry path and means for driving the two feed devices in opposite directions.

In a preferred construction one of the feed devices is an endless conveyor. One or both of the feed devices may be a rotary toothed cog or sprocket.

From another aspect the invention consists in a machine of the type referred to designed to be mounted on a three poinrtractor linkage and to be coupled to a PTO (power take off shaft) on the tractor.

Thus in a particular preferred construction the machine has an upper entry chute for straw bales and a lateral discharge opening for chopped straw, and including gear transmission mechanism between the PTO and the rotary cutter arranged to drive the cutter at a speed sufficient to chop more than one bale a minute and to impel the chopped straw through say 30 feet.

The invention may be performed in various different ways and one specific embodiment with a number of modifications will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 is a general perspective side elevation of a tractor-mounted straw chopper attachment according to the invention, Figure 2 is a diagrammatic sectional side elevation illustrating the main functional components of the machine, Figure 3 is a diagrammatic side view of the rotary cutter, Figure 4 is a sectional view through the axis of the rotary cutter, and Figure 5 is a reverse side elevation of the whole attachment.

The machine in this example is designed to be mounted on a conventional three-point tractor linkage, and as shown in Fig. 5 it includes a triangular framework 9 with three attachment points 8. It can therefore be raised and lowered as required and can readily be placed on the ground and uncoupled. It is driven by a conventional rotary power take-off shaft 7, as provided on all agricultural tractors. The machine comprises a rigid combined case and frame comprising two side plates 10, 11 with interconnecting rigid cross struts, an inclined feed chute 1 2 leading forwardly and downwards towards a rotary cutter 1 3, and an exit opening 1 6 at the opposite lower end of the machine through which the chopped straw is ejected at high speed.If used for mulching strawberry fields there is an additional cowl attached over the exit, as indicated in chain lines at 5. The cowl is preferably formed with two staggered exit chutes 3 and 4, with laterally spaced exit arches 3A, 4A to form two parallel straw banks.

The rotary cutter comprises a series of seven or more thin metal discs 17, each with a square central aperture 1 8 fitted on a squared shaft 1 9. Spacers between the indivi dual rotor discs hold them at the required axial intervals. On the periphery of each cutter disc are mounted four pivoted cutter blades 20 each pivoted to the disc at 21 and having a sharpened cutting edge 22. The blades can swing outwards under centrifugal force, but can pivot inwardly if they meet an obstruction. Interposed between the disc 1 7 are a series of relatively stationary fixed abutment ribs 25. Each of these ribs includes a curved arcuate part 26, an inwardly kinked part 27, and a tail 28.The tail is attached to a pin 30 which can move along inclined slots 29 in the side walls and the opposite end of each rib is provided with a pivotal adjustment mounting 31. It will be seen that by moving the pivot 31 radially outwards in the direction of arrow P the inclined pin and slot 29, 30 will cause the tail of the rib to move in the direction of arrow Q, the net result being that the main arcuate part of the rib at 26 moves radially away from the periphery of the rotary cutter in the direction of arrow R. This adjusts the maximum potential "projection" of the tips of the cutter blade 20 as they pass around and between the ribs. This adjustment is very useful and of remarkable advantage in enabling the machine to handle materials and bales of different qualities. The adjustment is effected simply by turning an external manual eccentric shaft lever 33.

It will be seen from Figs. 3 and 4 that each blade 20 is twisted at 23 such that its inner part lies parallel with the supporting disc 1 7 while its outer extremity is twisted out of this plane and more fully spans the gap between adjacent ribs 17, while yet presenting a sharp leading cutting edge 22. The blades are arranged in alternate pairs as seen in Fig. 4. It will also be noted that the inward projection or kink 27 in each rib 1 7 provides a gap 35 between the knuckle joint 36 and the part 37 of the tail which intersects the circular path of the cutters. This gap allows any straw which is knocked through between a pair of ribs at the kinks 36 to become realigned before the cutters reach the next chopping zone 37. This is found to be most effective in avoiding clogging.Furthermore, the machine also includes a row of spaced stationary abutment blades 38, aligned with the ribs 1 7 or somewhat offset and spaced arcuately from the tail end of each finger. These provide a third chopping zone, which is spaced from 37 for the same reason given above. The net result is that straw from a blade can be chopped swiftly and without risk of clogging and will leave the machine through the exit 1 6 at high velocity.

The machine also includes power operated means for feeding the bales up against the rotary cutter. As shown in Fig. 2, there is a generally horizontal endless conveyor 40 on the lower wall of the entry chute 12, and two or more spaced rotary feed star wheels 41 with prongs projecting into the path of bales moving down the chute. The conveyor 40 and the star wheels 41 are driven in opposite directions so as to pinch and grip the lower end of a bale and feed it downwards at a controlled speed against the abument fingers 25 where the bale will be engaged and chopped by the flail blades of the rotary cutter.

The drive mechanism includes an input shaft 50 having a coupling for connection to the tractor PTO, a belt drive 51 to a step-up gear 52, and a second belt drive 53 to a reversing gearbox 54 having two pulley wheels 55, 56 rotating in opposite directions.

From pulley wheel 55, a belt 57 drives the cog wheels 41 and from the pulley wheel 56 a belt 58 drives the endless conveyor 40. The rotary cutter 1 3 is driven at high speed by a further belt 59 engaging around a large diameter pulley 60 attached to the input shaft 50. In a typical example the input shaft 50 may have a speed of 540 r.p.m., the rotary cutter shaft a speed of 1815 r.p.m., with a cutter blade diameter of 58.6 cm, and a blade tip velocity of 55 meters/sec., the rotary speed of the star wheels 41 is 7 r.p.m. with a diameter of 22 cm, and the linear speed of the conveyor 40 is 357 cm/minute. The linear feed speed of the bale is thus related to the speed of the cutter, but all speeds can be increased proportionally by increasing the speed of the PTO shaft from the tractor.

Claims

1. A machine for cutting and distributing straw or like material, comprising a rotary power driven cutter with a series of axially spaced projecting blades, and a series of interposed stationary spaced abutments, and means for feeding bales of straw or the like against the rotary cutter such that material is chopped off and removed from the bale.

2. A machine according to Claim 1, in which the abutments are radially adjustable relative to the axis of the cutter to vary the relative projection of the cutter blades.

3. A machine according to Claim 2, in which the abutments are adjustable in unison relative to the cutter axis.

4. A machine according to any of Claims 1 to 3, in which the abutments extend around a substantial arc of the cutter.

5. A machine according to Claim 4 in which the abutments extend across the entry path of the bales.

6. A machine according to any of the preceding claims, in which the abutments are adjustable each transversely to the cutter axis at one end, and are pivotally and/or slidably adjustable at the other end.

7. A machine according to any of the preceding claims in which the cutter and abutments are arranged to provide two or more arcuately spaced chopping zones around the periphery of the cutter.

8. A machine according to Claim 7, including a gap between two such zones sufficient to prevent or reduce clogging.

9. A machine according to Claim 7 or Claim 9, in which each abutment extends over part of the periphery of the cutter, and there is an interruption or gap between this arcuate part and an adjacent fixed abutment aligned with the said part.

10. A machine according to any of the preceding claims, in which each abutment is cranked or stepped radially inwards or outwards to form a gap between first and second chopping zones.

11. A machine according to any of the preceding claims, including means for feeding material such as bales of straw towards the cutter, comprising a pair of power operated feed devices on opposite sides of a chute or entry path and means for driving the two feed devices at a controlled speed.

1 2. A machine according to Claim 11, in which one of the feed devices is an endless conveyor.

1 3. A machine according to Claim 11 or Claim 12, in which one of the feed devices is a rotary toothed sprocket.

14. A machine according to any of the preceding claims, designed to be mounted on a three-point tractor linkage and to be coupled to a power take off shaft on the tractor.

15. A machine according to Claim 14 having an upper entry chute for straw bales and a lateral discharge opening for chopped straw, and a platform on which an operator can stand to load bales into the chute.

1 6. A machine for chopping baled straw, substantially as described with reference to the accompanying drawings.