AU2013100886A4

AU2013100886A4 - Wear resistant stud

Info

Publication number: AU2013100886A4
Application number: AU2013100886A
Authority: AU
Inventors: Graeme Johnson
Original assignee: STUDTECH Pty Ltd
Current assignee: STUDTECH Pty Ltd
Priority date: 2013-06-27
Filing date: 2013-06-27
Publication date: 2013-08-01
Anticipated expiration: 2021-06-27
Also published as: WO2014205514A1

Abstract

A wear resistant stud (10) for attachment to an earth working implement (50), the wear resistant stud (10) having a first portion (12) including a weldable wear resistant material, and a second portion (14) attached to the first portion (12), wherein the second portion (14) has greater wear resistance than the first portion (12). oN -- --- ------ Figure 5 XM' N'x ..... ..... R\ q N>K KKKNNN' ... ... .. ... ... .. FigMe "N ' Figure 7

Description

1 WEAR RESISTANT STUD FIELD OF THE INVENTION [0001] The present invention relates to wear resistant studs for attachment to exposed surfaces of earth working implements that are subject to abrasive and impact wear, such as the teeth of ore/rock crushers/grinders and buckets or blades of earth moving equipment. BACKGROUND TO THE INVENTION [0002] There are numerous earth working implements and tools having a metal surface subject to extreme abrasive and impact wear in use, such as from the mining and transporting of ores, sand, rock and the like. [0003] As used herein, the term "earth working implement" includes an implement or tool for extracting, moving or breaking down minerals, ores, rock, sand and coal, such implements having metal surfaces subject to abrasion and impact wear. Such earth working implements include buckets, blades, and grinders, e.g. as used in the construction and mining industries. [0004] A known way of reducing abrasive and impact wear to the exposed working surfaces of such implements is by welding an array of wear resistant studs onto those exposed metal surfaces. [0005] Such wear resistant studs reduce abrasion and impact wear by acting as a barrier between the wear surface and the material being worked or moved. The wear resistant studs are preferentially (sacrificially) worn down before the otherwise exposed surface of the earth working implement is worn down.

2 [0006] Furthermore, material caught in the spaces between the wear resistant studs acts as an additional barrier protecting the surface of the earth working implement. [0007] Wear resistant studs are therefore beneficial for extending the working life of an earth working implement. [0008] However, even the wear resistant studs wear because of the abrasive and impact forces acting on them. After certain use, the wear is so severe that the earth working implement needs to be replaced. [0009] Replacing an earth working implement is costly. It is therefore desirable to extend the life of the wear resistant studs and thus the life of the earth working implement. [0010] With the aforementioned in mind, it is a desirable of the present invention to improve wear resistance capability of wear resistant studs in order to extend life of an earth working implement fitted with the wear resistant studs. SUMMARY OF THE INVENTION [0011] With the aforementioned problem in mind, an aspect of the present invention provides a wear resistant stud for attachment to an earth working implement, the wear resistant stud having a first portion including a weldable wear resistant material, and a second portion attached to the first portion, wherein the second portion has greater wear resistance than the first portion. The first portion and the second portion may be different materials. [0012] The second portion may be at least partially contained within the first portion.

3 [0013] The first portion may be a body of the wear resistant stud and the second portion may be a core retained or formed at least partially within the wear resistant stud. [0014] The stronger, more wear resistant, core supports the body from within. When a stud according to the present invention is subject to abrasive or impact forces, the stud is able to absorb more energy than a standard wear resistant stud (made of single material). Therefore, the overall wear resistance of the stud is increased which in turn extends the working life of the wear resistant stud and of the earth working implement. [0015] Importantly, the two part construction of the stud enables the use of non-weldable materials to absorb impact and abrasive forces acting on an earth working implement. Some non-weldable materials have much better wear resistance capabilities than weldable materials. [0016] The extended life of an earth working implement has several economic benefits. Firstly, the implement may be used for longer period of time. Therefore, the return on investment of the implement can be increased. Secondly, the downtime for replacing the implement is delayed by delaying the need to replace the implement. Therefore, the costs associated with downtime are deferred to a later date. Also, fewer inventory of implements needs to be maintained. [0017] Preferably a portion of the core remains exposed to receive impact when the stud is welded to the earth working implement. The core may project from the body to increase exposed portion to receive impact. [0018] The core may be partially or fully inserted into the body and retained therein by interference fit. Preferably, the core includes a sintered material. [0019] More preferably, the core has serrations on its outer periphery to increase the strength of the interference fit. A serrated periphery allows 4 increasing interference tolerance in order to increase the tightness of the fit. The serrations may be straight or inclined along the length of the core. [0020] The material of the core may be harder than the material of the body. A harder material may have better wear resistance properties than a softer material as it is less prone to abrasion wear. Thus, an exposed upper surface of the second portion or core that is subject abrasive wear and/or impact increases the life of the stud and supports the outer weldable material of the first portion. [0021] The core may include tungsten or tungsten carbide or polycrystalline diamond composite (PDC) material. These materials are harder than weldable materials such as steel which is used in known solid wear studs. These materials have better resistance to abrasive and impact forces. Particularly, tungsten carbide has high impact resistance which is useful in increasing wear resistance of the stud. [0022] A further aspect of the present invention provides an earth working implement to which a plurality of wear resistant studs according to the above aspect of the present invention are attached. [0023] A preferred embodiment of the present invention is described below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS [0024] Figure 1 illustrates a top view of a wear resistant stud according to one embodiment of the present invention. [0025] Figure 2 illustrates a sectional view of the wear resistant stud of figure 1.

5 [0026] Figure 3 illustrates a front view of the wear resistant stud of figure 1. [0027] Figure 4 illustrates a bottom view of the wear resistant stud of figure 1. [0028] Figure 5 illustrates an axonometric view of the wear resistant stud of figure 1. [0029] Figure 6 shows a plurality of wear resistant studs attached to an earth working implement. [0030] Figure 7 shows the process of attaching a wear resistant stud to an earth working implement. DESCRIPTION OF PREFERRED EMBODIMENT [0031] Referring to figures 1 to 5, a wear resistant stud 10 includes a first portion 12 and a second portion 14 retained in the body 12. [0032] The first portion 12 is the body of the wear resistant stud 10 and the second portion 14 is a core retained or formed at least partially within the wear resistant stud 10. The first portion 12 is the outer portion of the stud 10 such that it acts as a jacket for the second portion 14. [0033] The body 12 of the wear resistant stud 10 is substantially cylindrical. The welding end 16 of the stud 10 is tapered in order to provide material for fusing with a surface of the earth working implement 50 during welding. The other end of the stud 10 is the wear end 18. When the stud 10 is welded on to an earth working implement 50, the wear end 18 remains exposed to receive impact and abrasion forces acting towards the earth working implement 50.

6 [0034] A hole 20 is drilled in the body 12 on the wear end 18. The hole 20 is centrally located and is co-axial with the body 10. A wear resistant core 14 is inserted in the hole 20. The wear resistant core 14 is substantially cylindrical. The wear resistant core 14 is of such a length that when it is completely inserted in the body 12, the wear end 18 face of the core 14 and that of the body 12 are flush. Preferably, the core 12 is protrudes slightly (e.g. less than 1 mm) from the hole 20. An end of the core 12 inserted in the hole 20 is substantially flat or slightly rounded such that the core 12 is able to rest on the hole 20. [0035] The wear resistant core 14 is anchored to the body 12 by interference fit between the body 12 and the core 14. The core 14 has serrations on its cylindrical face. The serrations are parallel or inclined along the length of the core 12. The core 12 is weaker at the serrations. When the core 14 is pressed into the hole 20, the serrations are able to deform, whereby the interference tolerance can be increased to increase tightness of the fit. Additionally, the core can be made of sintered material to assist the interference fitment. [0036] The body 12 is made of weldable and machinable steel. Machinability of steel reduces cost of drilling the hole 20. [0037] The core 14 is made of tungsten or tungsten carbide bar. Tungsten carbide is approximately 100 times more wear resistant than some steels due to its greater hardness. [0038] The core 14 can be made of polycrystalline diamond composite (PDC) material. PDC is made by combining layers of polycrystalline diamonds (PCD) with a layer of cemented carbide liner at high temperature and high pressure. PCD is made by sintering micro-sized single diamond crystals at high temperature and high pressure. PCD has good fracture toughness and good thermal stability. Therefore, PDC acquires the hardness from diamond and toughness from carbide. PDC is approximately 5 times harder than tungsten carbide. PDC is more wear resistant than tungsten carbide.

7 [0039] Wear resistance is the ability of a material to resist gradual wearing away caused by abrasion and friction. Generally, harder materials have greater wear resistance. However, hardness also depends on the composition of the material, grain size and grain structure of a material. It has been found that the abovementioned materials for the second portion viz, tungsten, tungsten carbide and PCD have higher wear resistance than steel or hardened steel. [0040] For comparative analysis, on Mohs hardness scale the hardness values of the materials are estimated to be: o Steel - 4 to 4.5 o Hardened steel - 7.5 o Tungsten - 7.5 o Tungsten carbide - 9 o Diamond - 10 [0041] The stud 10 including the body 12 and the core 14 may be heat treated to increase the hardness of the two components. Whereby, softer steel, more machinable than hardened steel, may be used as material for the body 12. Alternatively, the core 14 may be heat treated separately before affixing it to the body 12. [0042] Referring to figure 6, a plurality of wear resistant studs 10 are attached to an earth working implement 50. The wear resistant studs 10 are arranged in an array on the surfaces of the earth working implement 50. The wear end 18 of each stud, and therefore the core 14, is exposed to receive impact and abrasion forces acting towards the earth working implement 50. [0043] Referring to figure 7, the wear resistant stud 10 is welded on to a surface of an earth working implement 50 by the following process: 1) The stud 10 is located on the surface 50 to which it is to be welded.

8 2) The stud 10 is pulled away from the surface 50 and a pilot arc is drawn. When the welding arc strikes, the material on the lower part of the stud 10 is melted and the surface 50 underneath the stud 10 puddles. 3) The stud 10 is plunged into the molten metals. The molten metals solidify very quickly. The stud 10 and the surface 50 are fused to form a permanent bond. The stud 10 is thereby attached to the surface of the earth working equipment 50. [0044] Alternative embodiments: [0045] In an alternative embodiment, the second portion having high wear resistance is annular and it is mounted on a protrusion of the first, weldable, portion. In this embodiment, greater area of the second portion could be exposed to receive impact/abrasive forces, when the stud is attached to an earth working implement. Additionally, the wear end of the second portion could be closed such that the second portion covers the wear end of the first portion. [0046] In a further alternative embodiment, the second portion may be inserted in the first portion from a hole in the first portion at the welding end of the stud. In this embodiment, the first portion could fully cover the second portion once the stud is welded to an earth working implement. [0047] The wear resistant stud 10 may be made of a single material wherein a portion of the material is hardened, for example by case hardening process. Therefore, the wear resistant stud could be made of a single material hardened partly. [0048] The size and shape of the wear resistant stud 10, the body 12 and/or the core 14 may be modified to suit a particular application. Typically, smaller wear resistant studs 10 will be applied to curved surfaces, whereas larger wear resistant studs 10 will be applied to flat surfaces.

9 [0049] The core 14 may be affixed to the body 12 by other methods such as threading, fastening, gluing, etc. [0050] The materials used for the body 12 or the core 14 may be varied to suit a particular application. Reference number table: No. Integer 10 Wear resistant stud 12 first portion / Weldable body 14 Second portion / Wear resistant core 50 Earth working implement / surface thereof

Claims

1. A wear resistant stud for attachment to an earth working implement, the wear resistant stud having a first portion including a weldable wear resistant material, and a second portion attached to the first portion, wherein the second portion includes a material having greater wear resistance than the first portion.

2. A wear resistant stud according to claim 1, wherein the first portion and the second portion are different materials.

3. A wear resistant stud according to claim 1 or 2, wherein the second portion is at least partially contained within the first portion.

4. A wear resistant stud according to any one of the preceding claims, wherein a part of the second portion remains exposed to receive impact when the stud is attached to an earth working implement.

5. A wear resistant stud according to any one of the preceding claims, wherein the second portion is inserted in the first portion and retained therein by an interference fit between the first portion and the second portion.

6. A wear resistant stud according to claim 5, wherein the second portion has serrations on its periphery to allow increasing the tolerance of the interference fit.

7. A wear resistant stud according to any one of the preceding claims, wherein the material of the second portion is harder than the material of the first portion. 11

8. A wear resistant stud according to any one of the preceding claims, wherein the second portion is made of tungsten or tungsten carbide or polycrystalline diamond composite (PDC) material.

9. An earth working implement having plurality of wear resistant studs according to any one of the preceding claims attached thereon. STUDTECH PTY LTD WATERMARK PATENT AND TRADE MARKS ATTORNEYS UIP1416AUOO