WEAR PART ATTACHMENT SYSTEM FIELD OF THE INVENTION

The present invention relates to the attachment of a wear part to a machine tool. In particular the present invention relates to the attachment of a wear part, such as a tooth, tool or wear part, to a pocket or holder of a machine tool. The present invention provides an attachment system for a wear part and a machine tool as well as a method for attaching a wear part to a machine tool. The present invention has particular application to the attachment of teeth or tools or wear parts to augers.

BACKGROUND OF THE INVENTION Augers are employed to bore through many different types of substrate from soft earth to hard rock and many combinations and variations in between. The teeth of the auger are generally prone to wear and often need replacement for the efficient operation of the auger. The teeth or wear parts are preferably mounted on the auger or other machine tool so as to be replaceable in the field with the minimum of downtime. In augers, for example, pockets or holders are welded to the augers to receive and position the teeth. The teeth have a notch extend through the body which is received about a corresponding land in the corresponding pocket. The land assists in restraining the tooth from lateral movement within the pocket. Our current commercially used system employs a rubber lock that extends through a bore in the land and the rubber lock is compressed within the pocket between the land of the pocket and the internal surface of the notch of the tooth.

Our searches of the patent literature have revealed an Australian patent application that describes an alternative locking system in which a rubber shock absorbing member extends about the periphery of the land within the pocket and is received within the notch of the tooth. A locking pin is used to retain the tooth in the pocket. This system is somewhat complex requiring additional inventory of parts for the replacement of teeth as well as a more complex system for the removal of worn teeth and the fixing of new teeth. Furthermore, the knocking out of locking pins generally results in the pins being scattered and in order to maintain efficiency it would be expect that in commercial use the pins would be left in the field. It may also be difficult to remove the pins without the use of a drill or purpose made punch.

A variety of pockets are available for use and recently the pockets have been

supplied in a variety of sizes generally adapted to receive teeth of varying thickness. This presents the user with a limitation on the interoperability of teeth with pockets. A user may have teeth that are too thin to be received within a pocket and be used efficiently due to the differing systems. The present invention aims to overcome or alleviate at least one of the above disadvantages by providing improved methods of and means for attaching a wear part to a machine tool. Other objects and advantages of the invention will become apparent from the following description.

SUMMARY OF THE INVENTION We have now found an attachment system for a wear part, tooth or machine tool which provides a readily interchangeable system that is also compatible with a wide variety of existing mounting systems and which provides effective locking to retain the wear part to the tool in use but yet allows ready replacement with a minimum of downtime, or provides the user with a useful or commercial choice. In a first aspect, the present invention provides a wear part assembly comprising a wear part that is slidably received within a pocket, wherein a compressible member is located between the wear part and the pocket.

In one embodiment, the wear part may have at least one surface and the compressible member may be interposed between the at least one surface of the wear part and the pocket. Suitably, the wear part may have an upper surface and a lower surface and the compressible member may be interposed between one or both of the upper surface and the lower surface and the pocket. hi another embodiment, the wear part may comprise a body portion that, in use, is positioned within the pocket and the body portion has at least one surface, wherein the compressible member is interposed between the at least one surface of the wear part and the pocket. Suitably, the body portion may have an upper face and a lower face and the compressible member may be interposed between one or both of the upper face and the lower face of the body and the pocket

In accordance with a second aspect of the present invention there is provided a wear part assembly comprising a wear part, a pocket and at least one compressible member wherein the wear part comprises a body for slidably engaging a pocket, the body having an upper face and a lower face and wherein the at least one compressible member is interposed between either one or both of the upper face and the lower face of the body of the wear part and the pocket.

In accordance with a third aspect of the present invention there is provided a method for attaching a wear part to a machine tool comprising slidably engaging the wear part into a pocket of the machine tool with at least one compressible member interposed between a surface of the wear part and the pocket. Suitably, the wear part has an upper surface and a lower surface and the compressible member is interposed between either one or both of the upper surface and the lower surface of the wear part and the pocket.

In another embodiment, the wear part includes a body portion that is inserted into the pocket and the compressible member is interposed between a surface of the body and the pocket. Suitably, the body part has an upper surface and a lower surface and the compressible member is interposed between either one or both of the upper surface and the lower surface of the body portion of the wear part and the pocket.

The wear part assembly of the present invention requires a pocket typically attached to a machine tool, such as an auger, although it is within the scope of the present invention that the pockets are formed integrally with the machine tool. We have found that it is preferred that the pockets be attached to the machine tool, for example by welding as the pockets are less frequently replaced due to damage that occurs at the working end of the machine tool.

The wear part assembly of the present invention also requires a wear part that is removably attached to the machine tool. A compressible member is interposed between the wear part an the pocket between at one of the upper and lower surface of the wear part and the pocket.

The wear part may comprise a body for slidably engaging a pocket, the body having an upper face and a lower face. In a preferred embodiment of the present invention, the body incorporates a notch for receiving a corresponding land in the pocket for assisting in restraining lateral movement of the wear part within the pocket. Preferably the notch is of

an elongated slot for receiving a correspondingly shaped finger-like land within the pocket. It will be appreciated that the wear part will also have a wear surface.

Preferably, the body is of substantially constant thickness or has a body portion of substantially constant thickness for slidable engagement into the pocket with substantially planar upper and lower surfaces. In one embodiment, a detent may be provided either on the wear part or the pocket to assist in locking the wear part within the pocket.

The wear part has a wear surface that may be of any convenient configuration that is suitable for the substrate being machined.

The pocket for which the present invention is useful is varied. This is one of the distinct advantages of the present invention in that by simply selecting the use of a compressible member of the desired thickness or by applying the compressible member to one or both of the upper and lower surfaces of the wear part differing thicknesses of pocket may be accommodated with a single wear part configuration.

The at least one compressible member may be provided in a variety of thicknesses to accommodate pockets and wear parts of varying sizes. The compressible member may be manufactured from a variety of convenient materials including rubber, felt, cloth, polymeric materials, soft metals and composites. Preferably the compressible material also provides a substantial degree of friction between the body of the wear part and the pocket to provide improved retention of the tooth with the pocket. Felt is especially suitable for use in the present invention.

The at least one compressible member is interposed between the either one or both of the upper face and the lower face of the body of the wear part and the pocket. In one embodiment of the present invention a suitably dimensioned compressible member may be interposed between either of the upper and lower surfaces of the wear part and the pocket. If it is desired to provide a greater frictional retention of the wear part within the pocket a high friction compressible member may preferably be provided on both the upper and lower surfaces of the wear part. We have found that in general use it is only necessary to interpose the compressible member between either the upper or lower surface of the wear part and the pocket. Certain applications may warrant the use of opposed compressible members on both the upper and lower faces of the wear part. It will be apparent that the selected compressible members will have a commensurate reduction in thickness in such

applications.

The compressible members may be fixed to the wear tooth prior to insertion into the pocket or may be inserted as separate elements by squashing the compression member to the wear part of to the inside of the pocket. In the third aspect of the present invention the method of attaching a wear part to a machine tool comprising slidably engaging the wear part with the pocket with the compressible member(s) therebetween may be conveniently performed with a mallet, hammer or other suitable means for urging the wear part in to the pocket. The wear parts may be removed also with a mallet, hammer or the like, optionally with a punch or other tool for applying the force with greatest effect.

Advantageously the present invention provides a much greater surface area contact between the compressible member and the respective wear part and pocket whereby enhanced frictional retention of the wear part within the pocket is provided when compared with prior art attachment systems. Advantageously, the attachment system of the present invention also allows the use of alternative configurations for constraining the lateral movement of the teeth within the pockets.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the various aspects of the invention may be more fully understood and put into practical effect, a number of preferred embodiments will be described with reference to the accompanying drawings, in which:

FIG 1 shows a disassembled view of a prior art attachment system for attaching a wear tooth within a pocket welded to the operating end of an auger.

FIG 2 shows a partially assembled view of the attachment system shown in Figure 1.

FIG 3 shows an assembled view of the attachment system shown in Figure 1.

FIG 4 shows a wear tooth for an auger according to one embodiment of the present invention.

Figure 5 shows a wear tooth for an auger according to another embodiment of

the present invention.

Figure 6 shows the wear tooth of figure 5 slidably engaged with a pocket for an auger.

Figure 7 shows the wear tooth of figure 4 slidably engaged with a pocket for an auger.

Figure 8 shows the wear tooth of figure 4 slidably engaged with a pocket of the prior art for an auger.

Figures 1 to 3 show a pocket 1 for receiving a wear tooth 2. The pocket 1 has a land 5. The land 5 includes a bore 6 through which a rubber lock 3 extends. As the tooth 2 is urged into the pocket 1 the rubber lock 3 is deformed against the land by the notch 4. The compression of the rubber lock 3 retains the tooth 2 within the pocket 1 in use.

Figure 4 shows a wear tooth 10 for an augur (not shown). The wear tooth 10 has a body 13 formed from a pair of legs that define a notch that may be received on a land in a pocket. A wear surface 12 extends from the body 13. On the upper surface of the body 13 are a pair of compression members 14' and 14". Compression members are suitably made from felt. The compression members may be joined to or affixed to the wear tooth 10, for example, by use of a suitable adhesive.

Figure 7 shows wear tooth 10 from figure 4 within pocket 11. Pocket 11 has a protrusion at its base that can be received within a recess in an augur and welded thereto. The compression member 14 and the tooth 10 are urged into the pocket 11 and the tooth is retained in the pocket 11 in part by the frictional contact between the compression member and the tooth and pocket respectively.

Figures 5 and 6 show an analogous configuration but with the compression members 15' and 15" on the lower surface of the body 13 of the tooth 10. Figure 8 shows tooth 10 of figure 4 positioned for slidable engagement with a pocket 1 of the prior art shown in Figure 2. The selection of appropriately dimensioned compression members permits the use of a variety of sized wear teeth with a variety of sized and configured pockets.

In another embodiment (not shown), the compressible member(s) are not affixed to the wear part but rather are positioned between a surface of the wear part and the

pocket when the wear part is inserted into the tooth. It has been found that this also adequately secures the wear part in the pocket.

Persons skilled in the art will appreciate that the invention described above may be subject to improvements and modifications that will be apparent without departing from the spirit and scope of the invention described herein.