AU2003204322A1 - Improved method and apparatus for cane cutting - Google Patents

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT IMPROVED METHOD AND APPARATUS FOR CANE CUTTING The following statement is a full description of this invention including the best method of performing it known to me: IMPROVED METHOD AND APPARATUS FOR CANE CUTTING FIELD OF THE INVENTION The present invention is concerned with a method and apparatus for cutting cane. A preferred embodiment of the invention is particularly concerned with an improved base cutter and cutting blades for a sugar cane harvester.

BACKGROUND TO THE INVENTION The present invention will be described in relation to sugar cane harvesters although it may also have application where other crops are processed and is also applicable to types of machinery other than harvesters, for example the invention may be useful in sugar mills.

Sugar cane harvesters generally incorporate a pair of base cutters comprising a pair of contra-rotatable bases typically in the form of discs.

Mounted to each disc are a number of blades radially projecting from each disc's periphery. Figure 1 shows a schematic underside view of an exemplary pair of base cutters 2 each having a base in the form of discs 4 and 8 with respective blades 6a,..,6e and 10a,..,10e bolted to the discs. In use a cane harvester incorporating the base cutters is moved in the direction indicated by arrow 12 while the discs are rotated as shown by arrows 14 and 16. As the blades pass over cane 13 they sever it and tend to propel it into a trailing portion of the harvester for further processing such as billeting.

A problem that affects disc cutters is that their blades tend to wear quite rapidly. For example, it is common to have to replace the blades every four hours due to wear. Changing the blades is a time consuming process.

Furthermore the cost of replacing the blades so frequently is not inconsiderable.

It is an object of the present invention to provide an improved cane cutting arrangement which addresses and reduces, the above problem.

SUMMARY OF THE INVENTION According to a first aspect of the present invention there is provided a base cutter for rotation in a first direction, the base cutter including a base and one or more blades projecting from the base, the one or more blades each having a cutting edge and arranged so that points along the cutting edge further from the base are located forward, relative to the first direction, of points located closer to the base.

Preferably the one or more blades are mounted so that each cutting edge makes an angle with a radial line defined by a centre of rotation of the base and an outer tip of the cutting edge, the angle being zero or positive relative to the first direction.

In a preferred embodiment the one or more blades are engaged by guides secured to the base.

The guides may be provided in pairs having opposing edges for engaging corresponding blades.

Preferably the one or more blades are secured to the base by a removable means such as bolts.

The one or more blades may include a number of boltholes to provide for positional adjustment relative to the base.

In a preferred embodiment the outer edge of each of the one or more blades makes an acute angle with the cutting edge so that the outer edge does not protrude beyond a circle described by the outer tip.

The one or more blades may each be in the shape of a parallelogram.

In which case each blade may include cutting edges disposed along opposite sides of the blade.

Alternatively, the one or more blades may each be in the shape of a trapezoid.

According to a further aspect of the present invention there is provided a method for processing a crop, for example sugar cane, where a number of cutting edges are rotated about a common centre of rotation in a first direction, the method including the step of: arranging each of the cutting edges so that each cutting edge makes an angle with a radial line defined by the centre of rotation and an outer tip of the cutting edge, the angle being zero or positive relative to the first direction.

According to a final aspect of the present invention there is provided a blade for cutting cane including: at least one cutting edge; an outer edge making an acute angle with the cutting edge whereby in use the outer edge lies entirely within a circle defined by rotation of a tip of the cutting edge about an axis.

The blade may include one or more features for securing the blade to a base of a base cutter.

The blade may be in the shape of a parallelogram.

Preferably the blade has cutting edges located on opposite sides of the blade for interchangeability between contra-rotating base cutters.

Alternatively the blade may be trapezoidal in shape.

Other preferred features of the invention will be discernible from the following detailed description, which will be made with reference to a number of figures as follows: BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic view of the underside of a pair of base cutters as known in the prior art.

Figure 2 is a schematic view of the underside of a pair of base cutters according to a preferred embodiment of the present invention.

Figure 3 is a schematic view of the underside of one of the pair of base cutters of Figure 2.

Figure 4 is a schematic view of the underside of one of the pair of base cutters shown in Figure 1.

Figure 5 is a schematic view of the underside of a base cutter according to a further embodiment of the present invention.

Figure 6 is a perspective view of the top of one of the blades of Figures 2 and 4.

z 4 Figure 6a is a perspective view of the reverse side of the blade of Figure 6.

Figures 7a,..,7d are views of a blade according to a further embodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT Referring now to Figure 2, there is depicted the underside of a pair of contrarotating base cutters 3 and 5 each according to a preferred embodiment of the present invention. With reference to base cutter 3, five blades 18a,...,18e are provided. Obviously other numbers of blades, for example four or six, might also be used. Each blade is secured to disc 22 by bolting through one of boltholes 20 and thence through a hole in disc 22. The degree to which a blade protrudes beyond the perimeter of disc 22 may be adjusted by changing the bolthole 20 that is used to secure the blade. The blade is prevented from rotating about the securing bolt by means of guides 24 which are welded to disc 22 and which are spaced to engage the blade.

With reference to Figure 3, which is a magnified view of base cutter 5 of Figure 2, it will be noted that the blades are arranged so that points further out along each cutting edge are located forward, relative to the direction of rotation of the base cutter, in comparison to points along the edge located closer-in to the base. In particular, the guides 24 for each blade are orientated so that the blades' cutting edge 26a, and also the inner edges of the guides, makes an angle 25 of about 90 relative to line 23. Angle 25 is positive in the sense that it is in the same direction, about tip 17, as the intended direction of rotation 14, of the base cutter. Line 23 is a radial line defined by the centre of rotation 19 of the disc cutter and the tip 17 of cutting edge 26a. The positive angling of the cutting edge is in contrast to the arrangement that has been used in the past as will now be explained.

With reference to Figure 4, it will be seen that the cutting edge of each of the blades 6a,..,6e makes a negative angle 27 relative to radial line 23. The angle is said to be "negative" in that it is in the opposite direction, about the cutting edge's tip, to the intended direction of rotation 14. The inventor has found that by positively angling the blade as shown in Figures 2 and 3 the blade tends to chop straight across the cane, or gather it slightly towards the disc, rather than slicing the cane outward along the cutting edge. (An angle of is presently preferred however the size of the angle may be settled upon through trial.) Accordingly the cutting action of the arrangement depicted in Figure 2 differs from the prior art arrangement of Figures 1 and 4 wherein the cutting edges tended to centrifugally hurl cut cane out along the edge of each blade, thereby wearing the blade and making the slicing action increasingly pronounced as the tip of the blade became more and more worn.

Referring again to Figure 3, the outer edge 30 of each of the blades makes an acute angle 17 of approximately 750 with cutting edge 26a. This is so that outer edge 30 does not impact on cane as the base cutter rotates. Rather the outer edge is at all times within a circle described by the tip of cutting edge 26a as it rotates.

It is known to make base cutters that do not use a disc shaped base.

Figure 5 shows a base cutter according to a further embodiment of the present invention incorporating a non-disc shaped base 13. Once again, each of the blades is positively angled as described in relation to Figure 3.

Several unexpected advantages have been found to result from the arrangement depicted in Figures 2 and 3. Firstly the time taken for the blades to wear out is roughly doubled thereby saving in the number of blades that must be replaced and also in the man-hours taken to make the replacements.

Secondly, the hydraulic pressure used to rotate the base cutters has been found to be reduced which indicates that the cutting is more efficient.

Accordingly fuel and mechanical wear is reduced. Furthermore, cleaner cuts are believed to result which in turn produce less juice spray at the base of the stalk with an associated reduction in the amount of dirt adhered to the stalks and consequently introduced into sugar mills.

Figures 6 and 6a are perspective views of the top and underside of one of blades 18a,..,18e of Figure 2. Overall the blade is parallelogram shaped with the opposing sides parallel and with the outer sides 30a and 30b making an acute angle of about 750 with the cutting edges 26a and 26b. The cutting edges 26a and 26b are each bevelled with each about half the length of the blade and disposed on opposite sides and surfaces of the blade.

With reference to Figure 2, after a cutting edge of a blade,'for example blade 18c has worn out the blade can be removed from base cutter disc 22, turned over and rotated for fitting to base cutter disc 23 with cutting edge 26b protruding. Consequently a blade with the configuration shown in Figure 5 may be used with either clockwise or counter-clockwise rotating base cutters and is intended to swapped from one to the other in order that both cutting edges be used until worn out.

A blade according to a further embodiment of the present invention is depicted in Figures 7a,..,7d which are respectively perspective, top plan, bottom plan and side views of the blade. Overall the blade is of a trapezoidal shape with a bevelled cutting edge 29 and six bolt holes 31. Obviously other numbers of bolt holes, or other features for attaching the blade, may be used. With reference to Figure 7b the cutting edge makes an acute angle 17 of about 750 with outer edges 33b and 33a. The configuration of the blade makes it suitable for interchanging it between each of the base cutter discs 22 and 23 of Figure 2.

While the invention has been described in relation to base cutters for sugar cane harvesters it will be realised that the invention is not limited to that application and may also be used to process other crops and in other types of crop processing machinery.

The embodiments of the invention described herein are provided for purposes of explaining the principles thereof, and are not to be considered as limiting or restricting the invention since many modifications may be made by the exercise of skill in the art without departing from the scope of the invention.

Claims (19)

1. A base cutter for rotation in a first direction, the base cutter including a base and one or more blades projecting from the base, the one or more blades having a cutting edge and arranged so that points along the edge further from the base are located forward, relative to the first direction, of points located closer to the base.

2. A base cutter according to claim 1, the one or more blades are mounted so that each cutting edge makes an angle with a radial line defined by a centre of rotation of the base and an outer tip of the cutting edge, the angle being zero or positive relative to the first direction.

3. A base cutter according to claim 1 or claim 2, wherein the one or more blades are engaged by guides secured to the base.

4. A base cutter according to claim 3, wherein the one or more guides are provided in pairs having opposing edges for engaging corresponding blades.

A base cutter according to any one of the preceding claims, wherein the blades are secured to the base by a removable means such as bolts.

6. A base cutter according to claim 5, wherein the one or more blades includes a number of bolt holes to provide for positional adjustment relative to the base.

7. A base cutter according to any one of claims 2 to 6, wherein the outer edge of the one or more blades makes an acute angle with the cutting edge so that the outer edge does not protrude beyond a circle described by the outer tip as the base cutter is rotated.

8. A base cutter according to any one of the preceding claims wherein the one or more blades are each in the shape of a parallelogram.

9. A base cutter according to claim 8, wherein the one or more blades includes cutting edges disposed along opposite sides of the blade.

A base cutter according to any one of claims 2 to 7, wherein the one or more blades are each in the shape of a trapezoid.

11. A method for processing a crop, for example sugar cane, where a number of cutting edges are rotated about a common centre of rotation in a first direction, the method including the step of: arranging each of the cutting edges so that each cutting edge makes an angle with a radial line defined by the centre of rotation and an outer tip of the cutting edge, the angle being zero or positive relative to the first direction.

12. A blade for cutting cane including: at least one cutting edge; an outer edge making an acute angle with the cutting edge whereby in use the outer edge lies entirely within a circle defined by rotation of a tip of the cutting edge about an axis.

13. A blade for cutting cane according to claim 12 including one or more features for securing the blade to a base of a base cutter.

14. A blade for cutting cane according to claim 12 or claim 13, wherein the blade has the shape of a parallelogram.

A blade for cutting cane according to any one of claims 12 to 14, wherein the blade has cutting edges located on opposite sides of the blade for interchangeability between contra-rotating base cutters.

16. A blade for cutting cane according any one of claims 12 to 14 wherein the blade is trapezoidal in shape.

17. A base cutter substantially as described herein with reference to Figures 2 and 3.

18. A base cutter substantially as described herein with reference to Figure

19. A blade for cutting cane substantially as described herein with reference to Figures 6 and 6A. A blade for cutting cane substantially as described herein with reference to Figures 7A-7D. DATED this 26th day of May 2003 PAUL H. HENKE by my attorneys EAGAR NEWCOMB BUCK