SHEARING UNIT

Abstract: A shearing unit, for the removal of wool or the like from a skin, wherein a high speed endless cutting blade passes through a shearing head of the unit. The blade is sharpened periodically by an internally reinforced grinding disc or wheel that has a bond and abrasive grit that will wear at a rate to substantially prevent lanolin build-up on the disc or wheel.

Description: SHEARING UNIT This invention relates to an improved shearing unit, more particularly for a unit for the removal of a fleece from a sheep or from the pelt by the use of a continuously moving cutting blade. 5. In my earlier Patent specification No. 545,257 there is described a shearing unit for shearing wool from a pelt or skin of a sheep, the unit comprising a head having an endless cutting blade, characterized in that said endless cutting blade is provided with a serrated cutting edge such that at cutting speeds in the range of 500 to 3,000 metres per minute the ιo. serrated edge cuts the wool. In that specification, throughout the specificaiton and claims the term " serrated edge" is intended to mean an edge having a roughness similar to that produced by grinding with a stone having a grit size between 30 and 120 grit. is. The edge of the blade is treated with a selected stone during the process of removal of the wool from the skin or pelt to maintain its cutting efficiency. This is achieved by applying a stone to the blade by rotating the stone at a peripheral speed and at the reduired angle of presentation of the stone to the blade to produce the desired angle of serrations to engage the 20. fibres. While this has been very satisfactory, it has been found that further improvements can be made in order to facilitate this grinding of the cutting blade. There is provided according to the invention, an improved shearing unit 25. for removing wool from a skin, the unit including a shearing head, an endless cutting blade passing through the head, a grinding disc or wheel, and means for applying the grinding disc or wheel to the blade to provide the blade with a serrated cutting edge, characterized in that the grinding disc or wheel has an internal reinforcement for rotation at a high peripheral speed, 30. and also having a bond and gπt such that the grinding disc or wheel will wear at a rate to substantially prevent the build-up of lanolin in the wheel or disc. The required speed of the cutting blade is in the order of 500 to 3,000 metres per minute, preferably about 1 ,500 metres per minute and in order to 5 . produce a serration approximately perpendicular to the edge of the blade a particular range of peripheral speeds of the grinding disc is required to be produced. It is therefore required that the bonding properties of this disc or stone will allow the wheel to be safely rotated at this speed. The required hardness or strength of the bond is assisted by the incorporation of 10 . special fibres in the body of the wheel thus allowing a high peripheral speed to be used. Having produced the required cutting edge, a problem was encountered in maintaining this edge due to the lanolin in the wool. After a time the lanolin accumulates on the cutting edge oT the blade and is transferred to is. the surface of the grinding disc having the effect of sealing over the grits. The required grinding effect was then lost. In order to achieve a satisfactory operation a method of maintaining the exposure and presentation of the grits to the cutting edge had to be found. 2 0. Because of the relatively high peripheral speed required for the grinding disc, in the order of 3,000 metres per minute, a reinforced disc was selected. At the same time and still because of the relatively high peripheral speed required, a relative strong bond is required. The solution found is associated with the control of the rate of 2 5. wearing away of the grinding wheels. This rate of wear is a function of:- A. Type of grit. B. Strength of bond. C. Pressure of application. D. Time of application. The cutting blade is a special hard saw blade grade steel. The standard specification of grit for grinding this type of steel is normally regular aluminium oxide which is tough and not easily fractured. Silicon carbide grit is harder but more easily fractured. The silicon carbide wheel is used 5 . for grinding materials of low tensile strength, that is, marble, masonry etc. since the silicon carbide thus fractures more readily thus exposing more cutting edges. To facilitate control of the required rate of breaking away of the disc the silicon carbide disc or alternatively a modified aluminium oxide which 1 0. is intermediate between the regular aluminium oxide and the silicon carbide is used, and the required rate of fracturing of the grits associated with the strength of the bond is varied to the requirement by controlling the pressure and length of application of the disc to the blade. An air cylinder is employed to move the grinding disc to make contact is. , between the disc and the blade. The pressure of contact is controlled while the pressure of the air cylinder and the pressure regulator is used to vary this pressure. Thus a selected pressure is required for the grinding operation, the frequency and period of application of the grinding disc being under the 20. control of a control unit to periodically apply the disc to the blade. Reduced cutting efficiency of the blade which is immediately apparent to the operator is normally directly associated with the build-up of lanolin on the grinding disc. The methods available to the operator to re-establish the cutting efficiency by accelerating the breaking away of the grinding disc 25. in order to remove the build-up of lanolin is to :- 1. Increase the pressure of application of the disc by means of adjustment of pressure at the regulator. 2. To manually override the normal period of application applying the disc to the blade until the required grinding efficiency is 30. re-established. 3. Combination of both of the above. It has been found that the rate of build-up of lanolin is not necessarily constant. It is a function of the amount of lanolin in the wool which varies with the type of sheep and the season of the year, and thus it is often . necessary to take the above steps to remove the build-up of the lanolin in the grinding disc. In a preferred form of the invention a grinding disc is used having a reinforced fibre to allow the high speeds required. A silicon carbide or the modified aluminium oxide grit is used of coarse grain size ranging from 30 1 0, to 120, preferably 40. The hardness grade of the bond can vary from medium to hard, that is, from L to R grade, preferably 0, the bond being of a rubber or resinoid type with a porosity structure from 2 to 8, preferably 5. The figures given above are as stated in the Australian Standard Association For Bonded Abrasive Products, Part 1 - Designation and Marking 15. . AS B172 part 1 , 1967. Thus the invention in a preferred form, utilizes a grinding disc for the production of a cutting edge on a high carbon steel blade by the use of a grinding disc having a silicon carbide or a modified aluminium oxide grit which is not usually used or recommended to use on such a steel, this having 20. a coarse grain size to provide a serrated cutting edge, the bond being such that after fracturing of the grit to provide a further cutting edge, the grit is more readily removed from the disc to expose further grit to thus provide a sufficient rate of wear of the grinding disc to eliminate or minimize the build-up of lanolin on the disc. 25. Thus there is provided an improved shearing unit with a continuously moving cutting blade of an endless nature in which the blade is periodically sharpened by a grinding wheel or disc having a reinforced bond to hold the grit so that the wheel or disc will rotate at very high speeds and yet the bond and grit being of such a nature that it will wear away at a rate to prevent any substantial build-up of lanolin or grease on the wheel which build-up would then reduce the effectiveness of the grinding wheel or disc. Although one form of the invention has been described in some detail it is to be realised that the invention is not to be limited thereto but can 5 . include various modifications falling within the spirit and scope of the invention.

Claims: THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:- 1. An improved shearing unit for removing wool from a skin, the unit including a shearing head, an endless cutting blade passing through the head, a grinding disc or wheel, and means for applying the grinding disc or wheel to the blade to provide the blade with a serrated cutting edge, 5. characterized in that the grinding disc or wheel has an internal reinforcement for rotation at a high peripheral speed, and also having a bond and a grit such that the grinding wheel or disc will wear at a rate to substantially prevent the build-up of lanolin on the wheel or disc. 2. A unit as defined in claim 1 , further characterized in that the grit is silicon carbide or modified aluminium oxide having a grain size selected from the range of 30 to 120, preferably 40. 3. A unit as defined in claim 1 , further characterized in that the bond is selected from rubber or a resinoid type. 4. A unit as defined in claim 1 , further characterized in that the bond has a hardness selected from the range of N to U, preferably R. 5. A unit as defined in claim 1 , further characterized in that the porosity structure is selected from 2 to 8, preferably 5. 6. A unit as defined in claim 1 , characterized in that the endless cutting blade has a peripheral speed selected in the range of 500 to 3,000 metres per minute, preferably 1 ,500 metres per minute. 7. A unit as defined in claim 1 , characterized in that the peripheral speed of the grinding wheel or disc has a peripheral speed of 3,000 metres per minute. 8. A method of sharpening an endless cutting blade cutting wool from a skin, said method including the step of periodically applying to the moving cutting blade a reinforced grinding disc, said grinding disc having a silicon carbide grit of a grain size selected from the range of 30 to 120, a resinoid bond having a hardness selected from the range of M to U, and a porosity 5 . selected from the range of 2 to 8. 9. An improved shearing unit for removing wool from a skin, substantially as hereinbefore described.

Inventors: ANDERSON COLIN CHARLES, ANDERSON, COLIN, CHARLES
Applicants: ANDERSON COLIN CHARLES, ANDERSON, COLIN, CHARLES
Application year: 1987
Main classification: B26B19
IPC codes: A01K13, C14B1, C14B17