AU643148B2 - Cutting implement - Google Patents

Description

AUSTRALIA

Patent Act 643148 C M P L E T E SPECIFICATI ON

(ORIGINAL)

Class Int. Class Application Number: Lodged: Complete Specification Lodged: Accepted: Published: Priority: Related Art: Names(s) of Applicant(s): SE ENGINEERING Actual Inventor(s): Steven Emmanouilidis Our Address for service is: PHILLIPS ORMONDE FITZPATRICK Patent and Trade Mark Attorneys 367 Collins Street MELBOURNE, Australia 3000 Complete Specification for the invention entitled: CUTTING IMPLEMENT The following statement is a full description of this invention, including the best method of performing it known to applicant(s): 0804N o a a oo* *e o oeoo oooo CUTTING TOOL This invention relates generally to cutting tools and more particularly to cutting tools for cutting plastic material for recycling.

There is a growing awareness in the community of the need to recycle materials which would normally have been considered waste. In response to this growing awareness many industrial plants, offices, factories etc. have developed methods for recycling waste materials they produce.

The collection of recyclable materials from households by local councils, conservation groups and recycling agencies have also increased with this growing awareness. As such there is a great need for the development of efficient methods and machinery for the recycling of waste materials, in particular waste plastic materials.

While several methods of recycling waste plastic materials are known most methods require the plastic material to be initially cut into small pieces. Conventional cutters comprise a rotating cutting member supported inside a housing for receiving the material which is to be cut and in:orporating a collection zone or communicating with a collection zone. Previous devices of this kind suffer from the disadvantage that the tips responsible for the cutting form an integral part of either the rotating cutting member itself or a segment of the cutting member or are welded to the cutting member and therefore cannot be readily removed for sharpening or replacement.

During operation the cutting tips are placed under ia considerable amount of stress and as such they may break, 8rack or become worn or blunt. The amount of stress a cutting tip is subjected to will depend on the load and the type of imaterial to be cut. A special problem encountered in the processing of assorted waste plastics is the presence of various non-plastic impurities such as metal, rock or wood ~which cause excessive stress to be placed on the tips.

Removal and replacement of the cutting tips can be a costly>,and time consuming exercise especially if the tips are an integral part of the cutting tool. Several worn or 39 broken tips can result in the cutting tool becoming

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Z ineffective and thus necessitate its replacement. This problem is complicated by the fact that most cutter tips operate within strict tolerance limits.

Another disadvantage of the prior art cutters is that it is not practical to mount tips of different shapes or materials which may be best suited to cut a specific material into a particular shape and thus the prior art machines are limited in the tasks they can perform.

Cutters have been described in the prior art in which removable members incorporating the cutting tips are inserted into or attached to the cutter body. One such cutter is described in WO 87/01304 however the method of inserting the member incorporating the tip into a rectangular recess in a barrel shaped cutting member is not practical in the case of a cutting tool comprising cutting teeth. For cutting tools with rotating cutting teeth it would be more desirable if the tips themselves were replaceable.

It is an object of the present invention to overcome or at least ')alleviate one or more of the above mentioned disadvantages.

Accordingly the present invention provides a s cutting tool including: a hub member mountable for rotation about a central rotation axis; and Sat least one cutting tooth at a periphery of the hub member, the or each cutting tooth having a removable tip portion providing a cutting edge for the tooth.

The hub member preferably includes an aperture to enable the cutting tool to be mounted on a shaft for rotation. The cutting tool may then be secured to the shaft by means of one or more machine screws. In another preferred S embodiment the aperture includes one or more, preferably two, recesses which are preferably 180 apart. In this embodiment the shaft is provided with ribs on or along its .6 length to engage the recesses in the aperture and allow the shaft to drive the cutting tool.

The size of the cutting tool is chosen to suit the particular application ie. the size of the cutter in which the 39 cutting tool is to be installed and the type of material to be

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3 cut. In general the diameter of the cutting tool will range form 100 to 1000 mm. For cutting plastics material the width of the cutting tool will generally range from 30 to 300 mm, preferably 75 to 150 mm.

The hub member and cutting tooth or teeth may be composed of any strong material capable of supporting the removable tip during a cutting operation. Suitable materials include steel, alloy steel, high tensile steel, etc.

The cutting tooth or teeth may be formed integrally with the hub member or may be welded or otherwise connected to the hub member. The cutting tooth may be composed of any strong material capable of cutting through the desired material. Preferably the cutting tooth is composed of a material which is harder than the material of the hub or cutting tooth. Preferred materials include steel, alloy steel, hardened steel, high tensile steel, high alloy tool St~eI: eC. H~ghTM steel etc. High alloy tool steel such as VHB Viking TM steel is especially preferred.

In a preferred embodiment the tips are removeably attached to the periphery of the cutting tooth by one or more, preferably two, bolts .or machine screws. The bolts or machine S screws are preferably countersunk into the body of the tip so as not to interfere with the action of the tip on the cutting surface. A particularly suitable machine screw which is lTM available is the unbrako TM bolt.

In another preferred embodiment each cutting tooth possesses a recess into which the tip is inserted. The recess may contain 'guiding or retaining means, such as ribs or indentation, for positioning and aligning the tip in the recess. In this case the tip may be provided with ribs or indentations which co-operate with the guiding means in the recess.

In a particularly preferred embodiment the recess does not extend completely through the cutting tooth. In this arrangement the stress on the machine screws is minimized, e much of the stress being absorbed by the body of the cutting tooth.

In another preferred embodiment of the invention a 39 cutting implement is provided with a plurality of abutting

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4 cutting tools each cutting tool having a hub member mountable for rotation about a central rotation axis; at least one cutting tooth at a periphery of the hub member, the or each cutting tooth having a removable tip portion providing a cutting edge for the tooth. Preferably the cutting implement has between 6 and 15 cutting tools.

In a preferred arrangement the cutting tools are mounted on a shaft for rotation and each cutting tool preferably comprises 2 to 8, more preferably 3 to 6 and most preferably 3 or 4 cutting teeth.

The cutting tool of the present invention may be used to cut all types of known plastic materials. Some examples of suitable plastic materials include polyurethane, polyester, polyvinylchloride, polystyrene, nylon, polypropylene etc.

While the present invention has been described in relation to the cutting of plastic materials it is to be understood that the invention is not limited to this application. The cutting tool of the present invention may also be used to cut other materials such as cardboard, garden clippings, light branches of trees or shrubs and other organic materials such as dead beasts, offal, bones etc.

To facilitate understanding of the invention reference is made to the accompanying drawings which 26 illustrates some of the preferred features. However, it is to be understood that the description following is illustrative only and should not be taken in any way is a restriction on the generality of the invention described above. Referring to the drawings Figure 1 is a side elevation of a four-tooth cutting tool, 0 Figure 2 is a front perspective view of a cutter in operation.

Referring to Figure 1 there is shown a cutting tool having a diameter of 300 mm and comprising a hub (2) and four cutting teeth The hub contains an aperture (4) to enable the cutting tool to be mounted on a shaft for rotation. The cutting tool is secured on the shaft by 39 means of a machine screw A second machine screw (not

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5 shown) is located diametrically opposite this machine screw.

The cutting teeth are integral with the hub and are composed of high tensile steel.

Each cutting tooth has a cutting tip at its periphery. In the embodiment shown in figure 1 the dimensions of the tip are 75 x 22 x 75 mm. The cutting tooth has a recess into which the cutting tip is inserted. In this particularly preferred arrangement the recess does not extend completely through the cutting tooth, leaving a portion of the cutting tooth (15) to absorb much of the stress which would otherwise be placed on the machine screws.

The cutting tips are composed of UHB VikingTM steel which is a high alloy tool steel with a hardness between 56 and 58 Rockwell.

The cutting tip is removeably attached to the periphery of the cutting tooth by means of two unbrakoTM bolts Referring to Figure 2 there is shown a cutter comprising a series of abutting cutting tools mounted on a shaft inside a housing The housing is contains a cutting chamber, the top portion of which is defined by lid ee. (11) which contains an opening (12) for receiving the material to be cut. The housing has a steel frame on which S* TM Demtion A4 self-annealing tar sheets are mounted. In order to reduce the noise emitted by the cutter AF25 Acoustic Foam TM is f/1tted to the tar sheets.

The cutting tools are rotated with respect to S one another on the shaft so that one cutting tooth passes the cutting surface (13) at any one time. In this embodiment the cutter performs a slicing action rather than a chopping action and this minimises the impact stress on the motor providing the torque. The cutting tips are attached to the periphery of the cutting tools using two machine screws (9) which are countersunk into the body of the tip.

The leading surfaces (14) of the cutting teeth shown in both figures are concave which to assist in forcing the material to be cut into contact with the cutting surface (13).

39 Finally it is to be understood that various

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6 alterations, modifications or additions may be introduced into the cutting tool described without departing from the spirit or amubit of the invention.

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Claims (19)

1. A cutting tool including: a hub member mountable for rotation about a central rotation axis; and at least one cutting tooth at a periphery of the hub member, the or each cutting tooth having a removable tip portion providing a cutting edge for the tooth; wherein the or each cutting tooth includes a recess in which the removable tip portion is inserted.

2. A cutting tool according to claim 1 wherein said recess is located on the outer periphery of the at least one cutting tooth. i'2*

3. A cutting tool according to claim 1 or claim 2 wherein said recess extends part way through the cutting tooth such that at least part of the stress applied to the tip portion during a cutting operation is transferred to 0 0 the cutting tooth through an edge of the tip portion.

4. A cutting tool according to any one of claims .0 1 to 3 wherein said recess includes guiding means to align the tip portion in the recess.

5. A cutting tool according to claim 4 wherein the guiding means includes a rib or groove, adapted to interact with a groove or rib located on said tip portion.

6. A cutting tool according to any one of the preceeding claims wherein the tip portion is attached to the cutting tooth using one or more machine screws.

A cutting tool according to claim 6 wherein the machine screws are countersunk into the body of tip WDN 8 -8 portion.

8. A cutting tool according to any one of the preceding claims wherein the tip portion is composed of a material of greater hardness than the cutting tooth.

9. A cutting tool according to any one of the preceding claims having between 2 and 8 cutting teeth.

A cutting tool according to any one of the preceding claims having 3 or 4 cutting teeth.

11. A cutting implement including a cutting tool as claimed in any one of the preceding claims.

12. A cutting implement comprising a plurality of abutting cutting tools, each cutting tool including: a hub member mountable for rotation about a central rotation axis; :*2 at least one cutting tooth on a periphery of the hub member, the or each cutting tooth having a removable tip portion providing a cutting edge for the tooth; 2 wherein the or each cutting tooth includes a recess in which the removable tip portion is inserted.

13. A cutting implement according to claim 12 wherein said plurality of cutting tools are mounted on a shaft for rotation.

14. A cutting implement according to claim 12 or claim 13 comprising 6 to 15 cutting tools.

15. A cutting implement according to any one of claims 12 to 14 further comprising a cutting surface against which said tip portions performs a cutting action. r 39

16. A cutting implement according to claim 16 wherein 9 the tip portion or portions of each said cutting tool are angularly displaced relative to the tip portion or portions of each adjacent cutting tool such that when the cutting implement is in operation the tip portions of adjacent cutting tools strike the cutting surface in succession.

17. A, cutting implement according to claim 16 wherein the tip portions of adjacent cutting tools are arranged in a helfcal configuration such that the cutting implement performs a slicing action.

18. A cutting tool according to claim 1 substantially as hereinbefore described with reference to the embodiment thereof as illustrated in the accompanying drawings.

19. A cutting cutting implement according to claim 12 substantially as hereinbefore described with reference to the embodiment thereof as illustrated in the accompanying 20 drawings. ea 0 00 0 00 0 0 00 S0 0 300 0 .00 0 *0 0 0000 0 DATED: 26 August 1993 PHILLIPS ORMONDE FITZPATRICK Attorneys for: SE ENGINEERING s rL 9797N :3 9 xWDN tv r" 10 I .1 ABSTRACT A cutting tool including: a hub member mountable for rotation about a central rotation Axis; and at least one c utti ng tooth at a periphery of the hub member, the or each cutting tooth having a removable tip portion providing a cutting edge for the tooth. 2 3 0 355 39S WDN 11