Improved Cutter

The present invention relates to an improved cutter blade for the shearing of wool or animal hair.

A shearing apparatus for the shearing of wool or animal hair typically includes a handset which is grippable by a user of the apparatus, a cutter blade and a comb. The comb is fixed to the handset, while the cutter blade is movable over the comb along a curved path. The handset may be provided with a motor and an internal power source or a motor connectable to an external power source, hi an alternative embodiment, the handset contain a mechanical linkage which is configured so as to be connectable to a rotary input means such as a drive shaft.

Figures 1 and 2 show a typical cutter blade generally designated 10. The blade 10 is formed by a forging operation from an appropriately shaped body of forgeable material such as steel, followed by appropriate machining operations. The blade 10 is formed so as to include a top plate 12 and a peripheral wall or skirt 14 extending therearound. The lower face 15 of the peripheral wall 14 is commonly termed the cutting face. As can be seen from figure 2, the top plate 12 and peripheral wall 14 define a recess 16 on the underside of the blade 10. The top plate 12 and the peripheral wall 14 are typically each of a uniform thickness.

The blade 10 includes four teeth 18 which project forward from a base portion 20 of the blade 10. A four toothed blade is commonly referred to as a wide cutter blade, while a three toothed blade (not shown) is commonly referred to as a narrow cutter blade). The leading edges 22 of the teeth 18 are defined by tooth wall portions 23 of the peripheral wall

14. These leading edges 22 are sharp and need periodic sharpening to maintain their cutting ability. The blade 10 is sharpened by grinding the cutting face of the peripheral wall 14. It will thus be appreciated that sharpening of the blade 10 reduces the height of the peripheral wall 14 and the overall thickness of the blade 10.

The top plate 12 is provided with a number of through apertures. The outermost teeth 18 are provided with tapered prong holes 24 which are utilised to retain the blade 10 in driving

engagement to the hand set. A pair of grinding holes 26 are provided in the top plate 12. The grinding holes 26 are utilised to position and retain the blade 10 on a grinding apparatus when sharpening the leading edges 22 of the teeth 18. The grinding holes 26 may also be utilised as a secondary location point for retaining the blade 10 to the handset. In the embodiment shown, the blade 10 is further provided with a pair of safety peg holes 28. The peg holes 28 may be utilised on some designs of handset to additionally retain the blade 10.

The portion of peripheral wall 14 which is on the opposite side of the base portion 20 to the teeth 18 is referred to as the heel 30. The portions of the peripheral wall 14 which extend between the teeth 18 are referred to as crown portions 32. The portion of the peripheral wall 14 which extends between the heel 30 and the outer tooth portion 23 is termed the rear side wall 34. Each rear side wall is provided with a clearance hole 36. Each clearance hole 36 has a height H which is less than the height of the peripheral wall 14.

In use, the blade 10 is fitted to a handset and secured thereto by the provision of appropriate fixings being inserted into some or all of the through apertures 24, 26, 28 of the top plate 12. The cutting face 15 rests against a toothed comb (not shown) which is fixed to the handset. The blade 10 is tensioned such that it is urged against the comb. The blade 10 is then reciprocated along a curved path over the comb. Wool or animal hair which is present between the teeth 18 of the blade 10 and the teeth of the comb is cut by the movement of the blade relative to the comb.

The effectiveness of the blade can be reduced, in use, by the accumulation of wool or hair, dirt, grease, lanolin and other debris associated with shearing in the recess 16 on the underside of the blade 10. This matter becomes compacted and can urge the blade 10 away from the comb. The clearance holes 36 on the rear side walls 34 of the blade 10 provide a route through which the accumulated matter can be ejected, however the reduced height H of the holes 36 compared to the height of the wall 14 can lead to matter being retained in the recess 16.

According to the present invention there is provided a cutter blade for an animal hair cutting apparatus, the blade having a plurality of teeth each of which extend from a base

portion of the blade, the blade having a plate substantially defining the shape of the base and teeth, and a wall projecting from an edge of the plate and extending at least partially around the periphery of the plate, wherein the plate and wall co-operate to define a recess on the underside of the blade, wherein the blade is further provided with an interior rib which extends across the recess.

The rib is provided in the recess in order to manage the build up and accumulation of debris such as, for example, wool or hair, dirt, grease, lanolin and other debris associated with the cutting of animal hair. The rib may prevent the migration of debris across the recess to certain portions of the recess. The rib may further encourage the movement of debris in a desired direction as a result of the reciprocal movement along a curved path, in use, of the blade relative to a comb of a cutting apparatus.

The wall may extend fully around the periphery of the plate. In an alternative embodiment, the wall may be discontinuous. Preferably, the wall has a substantially uniform height.

The wall may define tooth wall portions which project from the edges of the plate around the periphery of the teeth. The wall may further define crown wall portions which are provided between the teeth and which extend between tooth wall portions. The wall may further define a heel wall portion which extends around the periphery of the plate to the rear of the base portion of the blade and rearwardly of the teeth.

The interior rib extend across the recess from a crown wall portion of the wall. Alternatively, the interior rib may extend across the recess from the junction of a crown wall portion with a tooth wall portion. The rib may extend fully or partially across the recess. Where the rib extends fully across the recess, the rib may meet and merge into a portion of the wall defining a heel wall portion. The rib preferably has a height that is substantially equal to that of the wall. The rib may be straight, curved, or comprise both straight and curved portions. The rib may be aligned such that it is substantially parallel to a notional centreline of the blade or of an individual tooth of the blade. The rib may alternatively be aligned with a wall portion of a tooth. The rib may project substantially perpendicularly with respect to the plate. Alternatively, the rib may project at an angle to the plate.

The blade may preferably be provided with an aperture or clearance hole in the wall to the rear of at least one of said teeth. The rib is preferably positioned across the recess such that, in use, debris is directed by the rib in the direction of the clearance hole. The clearance hole is preferably provided in the heel wall portion of the wall. In a preferred embodiment, the clearance has a height which is substantially equal to that of the peripheral wall.

The recess provided in the underside of the blade may be inclined. In such an embodiment, the recess may taper in the direction of the teeth with the result that the height of the recess decreases in the direction of the tips of the teeth. Consequently, the height of the recess may increase in the direction of the rear edge of the plate. The tapering of the recess may be achieved by varying the thickness of the plate. In a preferred embodiment, the height of the recess increases in the direction of an aperture provided in the interior wall. The tapered nature of the recess thus, in use, encourages debris to migrate in the direction of the clearance hole and thus exit the recess.

The taper of the recess may be uniform, which is to say that the recess may taper in a straight line. The taper of the recess may be in the region of between 1 to 15 degrees. More preferably, the taper may be in the region of 1 to 5 degrees. In an alternative embodiment, the taper of the recess may be non-uniform. For example, the recess may taper in a curved manner.

Apertures may be provided in the plate, which apertures are in communication with the recess on the underside of the blade. Apertures may be provided to facilitate the connection of the blade to a cutting apparatus or a blade sharpening device. One or more further apertures may be provided in the plate to facilitate the manual clearance of debris from the recess. For example, during a break in the operation of the cutting apparatus a user may remove debris from the recess, or move it in the direction of a clearance hole, by the insertion of an appropriately shaped tool into the aperture.

The blade may be provided with a plurality of interior ribs extending across the recess. The blade may further be provided with a plurality of rear clearance holes.

Embodiments of the present invention will now be described with reference to the accompanying drawings in which:

Figure 1 shows a top perspective view of a prior art cutter blade; Figure 2 shows a bottom perspective view of the cutter blade of figure 1 ;

Figure 3 shows a bottom perspective view of a cutter blade according to an embodiment of the present invention;

Figure 4 shows a bottom plan view of the cutter blade of figure 3 with section X-X marked; Figures 5 to 7 show alternative sectional views along section X-X of figure 4;

Figure 8 shows a bottom plan view of the cutter blade of figure 3 with section Y-Y marked;

Figures 9 and 10 show alternative sectional views along section Y-Y of figure 8; and Figures 11 to 16 show bottom plan views of cutter blades according to embodiments of the present invention.

Referring firstly to figure 3 there is shown a cutter blade according to an embodiment of the present invention and generally designated 40. Features common to the blade 10 described with reference to figures 1 and 2 are identified with like reference numerals.

The blade 40 differs from the blade 10 of figures 1 and 2 in a number ways. Firstly, the heel 30 of the blade 40 is provided with a plurality of rear apertures or clearance holes 42, 44. The rear clearance holes 42, 44 are separated by a plurality of interior ribs or walls 46 which extend across the recess 16 on the underside of base portion 20 of the blade 40. The presence of the rear clearance holes 42,44 renders the peripheral wall discontinuous. The interior ribs 46 extend across the recess 16 from the junction 48 of the tooth wall portions 23 of the peripheral wall 14 with the crown portions 32 of the peripheral wall 14. The recess 16 on the underside of the blade 14 is thus divided into recesses 16a provided behind the teeth 18, and recesses 16b provided behind the crown portions 32. The interior ribs 46 have a height which is substantially the same as that of the peripheral wall 14

The clearance hole 36 in each rear side wall 34 has been enlarged compared to the clearance hole 36 of the blade 10 of figures 1 and 2. The clearance hole 36 furthermore has a height which is equal to the height of the peripheral wall 14.

The rear clearance holes 42, 44 have a height which is equal to the height of the peripheral wall 14. The size and shape of the rear clearance holes 42,44 are such that the heel 30 is defined by the remaining portions of the peripheral wall 14 which correspond to the rearmost edges of the interior ribs 46 and the portions of the peripheral wall 14 extending from the outermost interior ribs 46 and the clearance holes 36.

The provision of the rear clearance holes 42,44. the enlargement of the rear side wall clearance holes 36, and the division of the blade underside recess 16 by the interior ribs 46 serves, in use, to reduce the possibility of debris accumulating in the recess 16. The rear clearance holes 42,44 provide additional paths for the evacuation of debris from the underside of the blade 40. The interior ribs 46 prevent the lateral migration of debris across the underside recess 16 and serve to channel debris towards the clearance holes 36,42,44.

It will be appreciated that, in use, the lower face 15 of the peripheral wall rests against and slide over the comb of the cutting apparatus. The corresponding lower faces of the interior ribs 46 also rest against and slide over the comb. The presence of the ribs 46 thus increases the stability of the blade 40 both during cutting and sharpening.

Referring now to figures 4 to 10 there is shown a blade generally designated 50. The blade 50 is similar to the blade 40 described with reference to figure 3 and common features are identified with like reference numerals. As can be seen from the cross-sectional views, the thickness of the top plate 12 is not uniform, with the result that tooth recess 16a decreases in height in the direction of the tooth tip 52. Alternatively, it can be said that the tooth recess 16a tapers in the direction of the tooth tip 52. Consequently, the top plate 12 thickens in the direction of the tooth tip 52. The increase in height of the tooth recess 16a in the direction of a rear clearance hole 44, in use, urges debris in the direction of the rear clearance hole 44.

As can readily be seen from figures 5 to 7, the tooth recess 16a may have different longitudinal configurations. The tooth recess 16a of the blade 50 figure 5 has a relatively shallow tapered portion 54 which extends from the rear clearance hole 44 in the direction of the tooth tip 52 for most of the length of the tooth , followed by a terminal steeply tapered portion 56. The tooth recess 16a of the blade 50 of figure 6 has a uniform straight line taper in the direction of the tooth tip 52. The tooth recess 16a of the blade 50 of figure 7 has, on the other hand, has a curved taper in the direction of the tooth tip 52. It will be appreciated that other longitudinal configurations which, in use, encourage debris to move in the direction of the of the rear clearance holes 44 may be employed. The crown portion recesses 16b may similarly be tapered in the direction of the crown portions 32 so as to encourage debris to move in the direction of the crown portion rear clearance holes 42.

In the embodiments shown, the blade tips 52 are relatively sharp. The blade tips 52 may, however, be provided with any desired shape ranging from a sharp point to any determined radius.

Figures 9 and 10 show that the tooth recess 16a may have different cross-sectional configurations. Figure 9 shows a tooth recess 16a having a substantially pentagonal cross- sectional shape. Figure 10 shows a tooth recess having substantially semicircular cross- sectional shape. It will be appreciated that other cross-sectional shapes may be utilised.

Referring now to figure 11 there is shown a bottom plan view of a blade generally designated 58. Features common to the blades 40, 50 described with reference to figures 3 to 10 are identified with like reference numerals. The blade 58 of figure 11 differs from the blade 40 of figure 3 in that the crown portions 32 of the peripheral wall 14 are omitted. The blade 58 is thus provided with channels 60 which are interspersed between the tooth recesses 16a. The channels 60 extend between crown holes 62 and the rear clearance holes 42. Additionally, the remaining portions of the heel 30 which are present in the blade 40 of figure 3 are omitted. The rear side wall clearance holes 36 are thus larger compared to the rear side wall clearance holes 36 of the blade 40 of figure 3. It will be appreciated that the blade 58 of figure 11 will be more flexible than the previously described blades due to the omission of the crown portions 32.

Referring now to figure 12 there is shown a bottom plan view of a blade generally designated 64. Features common to the blades 40, 50, 58 described with reference to figures 3 to 11 are identified with like reference numerals. The blade 64 differs from the blade 40 described with reference to figure 3 in that it is provided with fewer interior ribs 46 and in that said walls 46 do not fully across the recess 16 to the rear edge 66 of the top plate. The blade 64 is thus provided with a single rear clearance hole 68 which extends between the rear side walls 34. It will be appreciated that the rear side walls 34 are not provided with clearance holes. The blade 64 is provided with a central interior wall 46a which extends rearwardly from approximately the centre of the crown portion 32 provided between the inner two teeth 18. The blade 64 is further provided with and two outer interior ribs 46b each of which extends rearwardly from the interface of the outer tooth wall portion 23 of the inner teeth 18 with the crown portion 32 provided between the inner and outer teeth 18. The position of the interior ribs 46a,46b is such that the tooth recesses 16a include at least a portion of the crown portion recess 16b described with reference to figure 3.

Referring now to figure 13 there is shown a bottom plan view of a blade generally designated 70. Features common to the blades 40, 50, 58, 64 described with reference to figures 3 to 12 are identified with like reference numerals. The blade 70 is provided with a heel 30 which extends between the rear side wall clearance holes 36. The blade 70 is provided with two interior ribs 46, each of which extends from the intersection 72 of the central crown portion 32 with the inner tooth wall portions 23 of the inner teeth 18 to the heel portion 30. Each wall 46 is curved in the direction of a respective rear side wall clearance hole 36. The blade 70 is further provided with a centrally positioned hole 74 in the top plate 12. The hole 74 is bounded by the interior ribs 46, the central crown portion 32 and a central portion of the heel 30. The hole 74 permits the manual clearance of debris which may become trapped in this region of the blade during use.

Figure 14 shows a bottom plan view of an alternative blade generally designated 76. Features common to the blades 40,50, 58,64, 70 described with reference to figures 3 to 13 are identified with like reference numerals. The blade 76 is similar to that described with reference to figure 3 with the exception that the crown portion recesses 16b are not provided rear clearance holes 42. Instead, sections of the heal 30 extend between the

interior ribs 46 across the crown portion recesses 16b. Thus only the tooth portion recesses 16b are provided with rear clearance holes 36,44. While the outer interior ribs 46 are substantially perpendicular to the top plate 12, the inner interior ribs 46 are inclined with respect to the top plate 12. In the embodiment shown, the inclination of the innermost interior ribs 46 mirrors that of the tooth wall portions 23.

Figure 15 shows a bottom plan view of an alternative blade generally designated 78. Features common to the blades 40,50, 58,64, 70, 76 described with reference to figures 3 to 14 are identified with like reference numerals. The blade 78 is similar in configuration to the blade 76 of figure 14 with the exception that the blade 78 is provided with a central hole 74 in the top plate 12 similar to that of the blade 70 of figure 13.

Figure 16 shows a bottom plan view of an alternative blade generally designated 80. Features common to the blades 40,50, 58,64, 70, 76,78 described with reference to figures 3 to 15 are identified with like reference numerals. The interior ribs 46 are curved in the direction of the respective rear side wall clearance holes 36. The blade 80 may further be provided with laterally extending handles 82 indicated by broken lines. The handles 82 extend from laterally from the outer tooth wall portions 23 of the outermost teeth 18. The handles 82 may be incorporated into the blade 80 to provide a user with a readily grippable portion to assist in the removal and replacement of the blade 80. In an alternative embodiment, the outer tooth wall portions 23 of the outermost teeth 18 maybe textured so as to provide a gripping surface.