AU733437B2 - A cutting blade - Google Patents

Description

WO 99/31991 PCT/NZ98/00183 A CUTTING BLADE BACKGROUND TO THE INVENTION The present invention relates to a cutting blade but more particularly a blade for a knife as used in animal carcass processing subsequent to slaughter.

In the course of animal slaughter and carcass processing many of the operations are still performed by hand with the aid of a sharp knife. The use of a knife with a sharp tip has several disadvantages when used in certain operations. For example, when removing the pelt by cutting up the underside of the animal a sharp tip can score the carcass (through a protective membrane) and often result in the carcass being downgraded. Damaging the pelt, which goes on for further processing, also results in downgrading.

A sharp knife, in the hands of an unskilled worker, can lead to inaccuracy as the knife may easily wander and cut into unintended areas. The use of a sharp knife requires experience and a 'feel' for the knife as it moves into the animal as often the knife point will be out of sight. A knife once removed from the animal must be sterilised in order to restart a cut which results in the process taking longer than should be necessary.

Furthermore, when working up the carcass, insufficient separation of the pelt from the carcass can result in the pelt folding back and contacting the carcass. The carcass is WO 99/31991 PCT/NZ98/00183 2 then considered to be contaminated and may be unacceptable for human consumption. At the very least the carcass will require decontamination (washing and trimming etc.) which downgrades the carcass and lengthens processing time.

It is known to provide a blunt tip on a knife by incorporating a ball bearing or other protruberance with the tip. This aids in reducing damage but is only applicable to a limited number of operations. Furthermore sharpening of the blade is difficult and the cutting edge profile becomes misshapen over time as the ball bearing must be avoided. The most critical part of the blade, ie. the part behind the ball bearing which is required to be sharp, cannot be sharpened by a butcher's sharpening steel because of its proximity to the ball bearing.

SUIMMARY OF THE INVENTION It is an object of the present invention to provide a cutting blade for a knife which will, in use, minimise or eliminate damage to either pelt skin or carcass.

In one broad aspect of the invention there is provided a cutting blade including a cutting edge wherein an insert portion of docile material is embedded or inserted into said cutting edge such that the insert portion will not take a sharpened edge..

In a preferred embodiment of the cutting blade according to the present invention the portion of docile material will WO 99/31991 PCT/NZ98/001 83 conform to the contour of the blade during a sharpening process.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 illustrates a general view of a knife having a cutting blade according to one embodiment of the present invention, and Figure 2 is a view of the cutting blade before the docile material is inserted.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE

INVENTION

In one preferred form of the present invention as illustrated in Figure 1 the knife 10 is comprised of a handle 11, an upwardly curving blade 12 and a cutting edge 13.

The production of the plastic handle 11 and tempered steel blade 12 is in accordance with known methods and as such will not be described in any further detail.

The embedded docile material is provided (in this preferred embodiment) in the form of an insert 14 located at the distal end of the cutting edge 13. A 'docile' material will not take on a cutting edge when sharpened in conjunction with the cutting edge 13 and effectively remains blunt while still maintaining the contour of the blade 12.

WO 99/31991 PCT/NZ98/00183 4 In the preferred embodiment as illustrated the insert 14 occupies approximately 10% of the total blade length from the tip.

The knife 10 of the present invention can be used for operations such as removing the viscera where the distal end of the knife must not puncture the internal organs. The streamlined albeit blunt knife point 14 is capable of entering the carcass (by a stabbing action), but once inside the animal the blunt tip will not puncture the stomach or other internal organs thereby preventing contamination of the carcass. It is not uncommon for organs to be punctured by sharp knives when in the hands of less experienced workers.

When maintaining the blade 12, ie. sharpening, the insert 14 will wear away consistently with the cutting edge 13 and thereby provide uniform performance throughout the useable life of the knife. As opposed to alternatives (such as knives blunted by virtue of a ball bearing) the knife can also be sharpened to its required contour with a sharpening stone or grinder by the operator.

Insert 14 (formed from an appropriate docile material) is preferably inserted into the required position on blade 12 by a simple and cost-effective process. A basic method of producing a knife according to the present invention is hereinafter described.

The first step in producing the enhanced knife blade is removing a portion of metal from the blade which is to be WO 99/31991 PCTINZ98/00183 replaced. The profile of the blade with metal removed is best illustrated by Figure 2. In the preferred embodiment this means removing a (approx.) 10mm notch from the tip of the blade.

The pointed tip of the cutting blade must also be removed (as seen in Figure 2) so that during sharpening the hardened metal point of the cutting blade 12 is not uncovered. This would render the function of the docile material ineffective as the blade would have a sharp tip to puncture organs.

The notch or cavity 14a is thus ground into the blade preferably of a shape which will allow the insert 14 portion to be permanently retained in the blade once in place.

In further embodiments of the invention the 'notch' 14a may be formed by drilling into the cutting blade so as to provide a retention means for docile material at the tip.

Flux is then applied to the exposed cavity 14a portion of the blade and it is immersed in the molten form of the docile material (generally a metal or alloy). The molten docile metal may be retained in a recess in a fire brick proportionate to the modified area of blade (plus an excess) The blade with the new docile metal insert 14 is removed from the brick when the docile metal has sufficiently solidified.

Finally the blade may be reheated to blue and then crash cooled in oil. The resulting 'composite' blade is not welded WO 99/31991 PCT/NZ98/00183 6 (ie. the metal is not blended) but is held together by virtue of the insert shape within the blade and the surrounding docile metal.

The critical heating steps performed on the blade are preferably conducted in one systematic operation to ensure a consistent result. The insert 14 may then be worked to the required shape to conform with the cutting edge 13.

In an alternative method of producing a cutting blade according to the present invention a Gas Tungsten Arc Welder (GTAW or "TIG" welder) may be employed to bond the docile insert 14 to the cutting blade. This method is particularly favourable because of the associated toxicity and therefore undesirability of flux used in the previous process.

The TIG welder may be used as a heat source to melt the docile metal and place it into the cavity 14a (within the recess of an aluminium block). The high concentrated temperatures involved are thought to cause some absorption of the docile metal into the blade. The subsequent bond is very strong (more so than the previous method described) It will be appreciated by those skilled in the art that more sophisticated techniques may be employed to produce the blade according to the present invention (particularly on a commercial scale). The methods described are by way of example only.

WO 99/31991 PCT/NZ98/00183 7 Insert 14 is preferably in the form of bronze, nickel or silphos which are metal alloys with known docile properties and also have sufficient durability to provide a product with a reasonable service life.

The insert 14 is preferably a docile metal or alloy as described above but other materials may be suitable or become available which will provide the required properties to work the invention as it is intended.

The blunted portion of blade 12 represented by insert 14 is a relatively small section of the cutting edge. It is this critical tip portion which leads the knife in its cutting operations and hence previously had the most potential to cut into unintended parts of the animal causing quality to suffer.

The blunt insert 14 portion allows the point of the knife to follow a membrane layer without cutting through it and therefore avoids damage when separating the layers. The knife 10 of the present invention is quite suited to following the contours of individual animals (which may include scar tissue) and their different body shapes and fat layers while in the hands of a less skilled operator.

Overall the knife according to the present invention allows more accurate and efficient sectional removal at particular portions of the animal's skin pelt and internal organs. The knife enhances the quality of lead up work to the robotics which generally complete processing by providing the ability WO 99/31991 PCTINZ98/00183 8 to clear stress points which cause pelts to stretch and are then downgraded considerably.

The broad concept of replacing a portion of the cutting edge with a blunt portion can be applied to any section of the blade. Further embodiments include knives with docile inserts (of a form substantially similar to insert 14) which are positioned midway along the cutting edge 12. Blades of this type are suited to specialist operations such as when a long knife is required but only the leading portion is required to cut. An insert of the type described located midway along the blade thereby acts as a depth guide and the blunt portion prevents damage to unintended areas.

Inserts of varying thickness which still conform to the general contour of the blade are also possible for adaptation to different end uses and personal preferences.

A knife 10 of the type illustrated in the drawings is intended for the specialised operations involved in commercially processing animal carcasses but it will be appreciated that the invention can be applied to other uses without departing from the scope of the invention as it is intended. Such other uses include recreational hunting or fishing.

The knife of the present invention can be utilised by unskilled labour (relative to previous requirements where an experienced worker was employed who had a good 'feel' for WO 99/31991 PCT/NZ98/00183 9 specific cuts) and still minimise or eliminate damage to either the pelt skin or carcass.

Generally, the cutting blade of the present invention is multifunctional and a worker does not require a number of specialised knives for different cuts. Particularly, the cutting blade of the present invention may be used for 'flaying' cuts which are not possible when using a ballbearing tipped blade.

In addition, tip performance does not alter during the constant sharpening operations the knife blade must undergo in use.

Claims (10)

1. A cutting blade including a cutting edge (13) wherein an insert portion (14) of docile material is embedded or inserted into said cutting edge (13) such that the insert portion (14) will not take a sharpened edge.

2. The cutting blade of claim 1 wherein the insert portion (14) may be shaped during a sharpening process and generally conforms to the contour of the cutting blade (12).

3. The cutting blade of claim 1 or 2 wherein the insert (14) is located at a distal end of the cutting edge (13).

4. The cutting blade of claims 1 or 2 wherein the insert (14) is located at a mid point on the cutting blade (13). The cutting blade of any one of the preceding claims wherein the insert (13) is a contrasting colour to the remainder of the blade (12).

6. The cutting blade of any one of the preceding claims wherein the blade (12) includes a handle means (11)

7. The cutting blade of any one of claims 1 to 5 wherein the cutting blade (12) is adapted for use with an automated machine. WO 99/31991 PCT/NZ98/001 83 11

8. The cutting blade of any one of the preceding claims wherein the insert portion (14) of docile material is in the form of bronze, nickel or silphos.

9. A method of modifying a cutting blade including removing a section (14a) of a cutting edge (13) of the blade (12) and inserting in the section (14a) a docile material.

10. A method as claimed in claim 9 wherein the method includes removing a section (14a) of a cutting edge (13) of the blade (12) and immersing the section (14a) in a molten form of docile material.

11. The method of claim 10 wherein the cutting blade is re- heated and then crash cooled.