GB2075813A - Cutters - Google Patents

Abstract

A cutter arrangement for a harvester comprises two rotating, mutually overlapping toothed cutting discs 1, 2 with teeth 6, 7 having tooth points 10, 11 and leading edges 8, 9. To prevent the teeth 6, 7 from gripping stones or other hard objects, they are so shaped that, during rotation, the leading edges 8, 9 of the toothed discs 1, 2 will not pass a position perpendicular to a line 14 interconnecting the axes of rotation of the cutting discs before the toothed points 10, 11 pass the intersection of the paths of movement of the tooth points 10, 11 of the two toothed discs 1, 2 so that the leading edges 8, 9 tend to push hard objects away from the cutting discs and the drive trains therefor. <IMAGE>

Description

SPECIFICATION A cutter arrangement for a crop harvester This invention relates to a cutter arrangement for a crop harvester, said cutter arrangement comprising two rotatable, mutually overlapping toothed cutters.

The cutter arrangement is particularly, though not exclusively, suitable for use in a maize harvester.

The invention has been developed primarily with a view to eliminating, or at least reducing, the risk of stones or other hard objects getting jammed between the teeth of the cutters, which would damage the cutters or their drive means.

According to the invention there is provided a cutter arrangement for a crop harvester comprising two toothed cutters each rotatable about a respective axis and arranged so that the paths of motion of the teeth of the cutters partly overlap, the teeth of the cutters each comprising a tooth point and a leading edge extending forwardly of the tooth point with respect to the intended direction of rotation of the respective cutter;; in which the arrangement of the cutters and the teeth thereon is such that, for each tooth, an angle (B) is defined between the general direction of the leading edge of the tooth and a line extending through the tooth point of the tooth and tangentially to the path of movement of the tooth point, which angle is smaller than or equal to an angle (a) which is defined between a radius-extending from the axis of rotation of the respective cutter and through a point of intersection of the paths of motion of the toothed points of the cutters and a line interconnecting the axes of rotation of the cutters.

The arrangement of the cutters ensures that, during rotation, the leading edges of the teeth will not reach a position in which the angle between a leading edge of one cutter tooth and a leading edge of another cutter tooth is zero before the cutters begin overlapping each other. Therefore, these leading edges of the teeth of the cutters will essentially push hard objects away, so as to obviate, or minimise any risk of serious damage to the cutters.

According to one preferred construction, each tooth has curved sides, and to fulfill the requirements as above defined, the position of a theroetical tooth point is determined by location on a point of intersection between a radius through an apex of the tooth, and-the tangent to the leading edge of the tooth which forms the greatest angle with a tangent to the apex in the path of motion thereof.

The invention will now be described in more detail, by way of example only, with reference to the accompanying drawings in which: Figure lisa plan view illustrating the partly overlapping regions of two toothed discs of a cutter arrangement according to the invention; and Figure 2 illustrates a modified construction for a toothed disc of the cutter arrangement shown in Figure 1.

Figure 1 shows, in plan view, mutually partly overlapping parts of two toothed cutting discs 1 and 2 arranged to rotate in the direction indicated by the arrows 3 and 4. Mounted in a harvester, this cutter arrangement is intended to be advanced in the direction indicated by the arrow 5, to cut crops.

The toothed discs 1 and 2 are provided with teeth 6 and 7, respectively, having leading edges 8 and 9 which extend forwardly (with respect to the intended direction of rotation of the respective discs) of respective tooth points 10 and 11. A tangent to the path of motion ofthetooth points 10 is designated 12, while a radius for the toothed disc 1 through the intersection of the paths of motion of the tooth points 10 and 11 is designated 13. A connecting line between the centres of the two toothed discs 1 and 2 is designated 14, and the angle a between this line and said radius 13 is, in the embodiment shown, just equal to the angle ss between the leading edge 8 and the tangent 12. This means that the two leading edges 8a and 9a just meet when they are parallel with each other.If the angle B is made smaller than the angle a, the tooth edges 8a and 9a will diverge when they reach the position shown, which will also provide a satisfactory performance as regards guiding stones and hard objects away from the cutting discs and the drive trains therefor.

Figure 2 shows a section of a toothed disc 15 having teeth 16 whose leading edges 17 are curved.

By adapting such toothed discs according to the rule provided in the foregoing, a theoretical tooth point 18 is determined as the intersection between a radius 19 through the apex 20 of the tooth and a tangent 21 to the tooth edge 17 which forms the greatest angle with a tangent 22 to the path of motion 23 of the theoretical tooth point 18.

1. A cutter arrangement for a crop harvester comprising two toothed cutters each rotatable about a respective axis and arranged so that the paths of motion of the teeth of the cutters partly overlap, the teeth of the cutters each comprising a tooth point and a leading edge extending forwardly of the tooth point with respect to the intended direction of rotation of the respective cutter;; in which the arrangement of the cutters and the teeth theron is such that, for each tooth, an angle (p) is defined between the general direction of the leading edge of the tooth and a line extending throughthetooth point of the tooth and tangentially to the path of movement of the tooth point, which angle is smaller than or equal to an angle (a) which is defined between a radius extending from the axis of rotation of the respective cutter and through a point of intersection of the paths of motion of the toothed points of the cutters and a line interconnecting the axes of rotation of the cutters.

2. A cutter arrangement according to claim 1, in which the leading edges of the teeth are curved, and the theoretical tooth point for each tooth is located on a point of intersection between a radius through an apex of the tooth and a tangent to the leading edge of the tooth which forms the greatest angle with a tangent to the path of motion of the theoretical tooth point.

3. A cutter arrangement according to claim 1 or

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (6)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION A cutter arrangement for a crop harvester This invention relates to a cutter arrangement for a crop harvester, said cutter arrangement comprising two rotatable, mutually overlapping toothed cutters. The cutter arrangement is particularly, though not exclusively, suitable for use in a maize harvester. The invention has been developed primarily with a view to eliminating, or at least reducing, the risk of stones or other hard objects getting jammed between the teeth of the cutters, which would damage the cutters or their drive means. According to the invention there is provided a cutter arrangement for a crop harvester comprising two toothed cutters each rotatable about a respective axis and arranged so that the paths of motion of the teeth of the cutters partly overlap, the teeth of the cutters each comprising a tooth point and a leading edge extending forwardly of the tooth point with respect to the intended direction of rotation of the respective cutter;; in which the arrangement of the cutters and the teeth thereon is such that, for each tooth, an angle (B) is defined between the general direction of the leading edge of the tooth and a line extending through the tooth point of the tooth and tangentially to the path of movement of the tooth point, which angle is smaller than or equal to an angle (a) which is defined between a radius-extending from the axis of rotation of the respective cutter and through a point of intersection of the paths of motion of the toothed points of the cutters and a line interconnecting the axes of rotation of the cutters. The arrangement of the cutters ensures that, during rotation, the leading edges of the teeth will not reach a position in which the angle between a leading edge of one cutter tooth and a leading edge of another cutter tooth is zero before the cutters begin overlapping each other. Therefore, these leading edges of the teeth of the cutters will essentially push hard objects away, so as to obviate, or minimise any risk of serious damage to the cutters. According to one preferred construction, each tooth has curved sides, and to fulfill the requirements as above defined, the position of a theroetical tooth point is determined by location on a point of intersection between a radius through an apex of the tooth, and-the tangent to the leading edge of the tooth which forms the greatest angle with a tangent to the apex in the path of motion thereof. The invention will now be described in more detail, by way of example only, with reference to the accompanying drawings in which: Figure lisa plan view illustrating the partly overlapping regions of two toothed discs of a cutter arrangement according to the invention; and Figure 2 illustrates a modified construction for a toothed disc of the cutter arrangement shown in Figure 1. Figure 1 shows, in plan view, mutually partly overlapping parts of two toothed cutting discs 1 and 2 arranged to rotate in the direction indicated by the arrows 3 and 4. Mounted in a harvester, this cutter arrangement is intended to be advanced in the direction indicated by the arrow 5, to cut crops. The toothed discs 1 and 2 are provided with teeth 6 and 7, respectively, having leading edges 8 and 9 which extend forwardly (with respect to the intended direction of rotation of the respective discs) of respective tooth points 10 and 11. A tangent to the path of motion ofthetooth points 10 is designated 12, while a radius for the toothed disc 1 through the intersection of the paths of motion of the tooth points 10 and 11 is designated 13. A connecting line between the centres of the two toothed discs 1 and 2 is designated 14, and the angle a between this line and said radius 13 is, in the embodiment shown, just equal to the angle ss between the leading edge 8 and the tangent 12. This means that the two leading edges 8a and 9a just meet when they are parallel with each other.If the angle B is made smaller than the angle a, the tooth edges 8a and 9a will diverge when they reach the position shown, which will also provide a satisfactory performance as regards guiding stones and hard objects away from the cutting discs and the drive trains therefor. Figure 2 shows a section of a toothed disc 15 having teeth 16 whose leading edges 17 are curved. By adapting such toothed discs according to the rule provided in the foregoing, a theoretical tooth point 18 is determined as the intersection between a radius 19 through the apex 20 of the tooth and a tangent 21 to the tooth edge 17 which forms the greatest angle with a tangent 22 to the path of motion 23 of the theoretical tooth point 18. CLAIMS

1. A cutter arrangement for a crop harvester comprising two toothed cutters each rotatable about a respective axis and arranged so that the paths of motion of the teeth of the cutters partly overlap, the teeth of the cutters each comprising a tooth point and a leading edge extending forwardly of the tooth point with respect to the intended direction of rotation of the respective cutter;; in which the arrangement of the cutters and the teeth theron is such that, for each tooth, an angle (p) is defined between the general direction of the leading edge of the tooth and a line extending throughthetooth point of the tooth and tangentially to the path of movement of the tooth point, which angle is smaller than or equal to an angle (a) which is defined between a radius extending from the axis of rotation of the respective cutter and through a point of intersection of the paths of motion of the toothed points of the cutters and a line interconnecting the axes of rotation of the cutters.

2. A cutter arrangement according to claim 1, in which the leading edges of the teeth are curved, and the theoretical tooth point for each tooth is located on a point of intersection between a radius through an apex of the tooth and a tangent to the leading edge of the tooth which forms the greatest angle with a tangent to the path of motion of the theoretical tooth point.

3. A cutter arrangement according to claim 1 or 2, in which each cutter comprises a circular cutter disc.

4. A cutter arrangement according to claim 1 and substantially as hereinbefore described with refer pence to, and as shown in the accompanying drawing.

5. Acrop harvester incorporating a cutter arrangement according to any one of the preceding claims.

6. A crop harvester according to claim 5 and in the form of a maize harvester.