AU2012101572A4 - Wear resistant liner - Google Patents

Abstract

A method of making a wear-resistant liner which includes the steps of providing a backing plate, locating a first layer of a first material on the plate, locating a second layer of a second material on the first layer and bonding the first layer to the plate and to the second layer, wherein the first material is a suitable polymer or rubber and the second material is a suitable polymer or rubber. 37854051 (GHMatters) P91644.AU 19/10/12 34s d 14

Description

AUSTRALIA Patents Act 1990 COMPLETE SPECIFICATION Innovation Patent Applicant (s): George Wilson FRASER Invention Title: Wear resistant liner The following statement is a full description of this invention, including the best method for performing it known to me/us: -2 BACKGROUND OF THE INVENTION [0001] This invention relates generally to a wear resistant liner. More particularly the invention is concerned with the manufacture of a wear resistant liner which is suitable for use in a device which handles an abrasive material. [0002] In the mining industry, by way of example, highly abrasive products such as ore, rock, slurries and the like are handled by devices such as chutes, hoppers, skips, and so on. This type of device is typically made from steel components such as steel plates which are shaped and configured to contain, or direct the flow of, an abrasive medium in a desired manner. It is well known that steel, although possessing substantial physical strength, is not normally capable of resisting abrasion over an extended time period. For this reason parts of a material handling device which are exposed to an abrasive medium are usually lined with a wear resistant material such as rubber. [0003] Typically the lining is effected by bonding a number of sheets of uncured rubber to a steel backing plate using a bonding medium or adhesive, and by curing the rubber in a vulcanisation process e.g. by subjecting the rubber sheets to pressure at an elevated temperature. [0004] A product produced in the aforementioned manner generally operates satisfactorily and exhibits wear resistant characteristics for an extended period. However the cost of uncured natural rubber sheeting is relatively high. Consequently the cost of enhancing the wear resistant properties of a material handling device is also 37854051 (GHMatters) P91644.AU 19/10/12 -3 high. It is pointed out in this respect that, although the rubber-lined parts offer extended operating lifetimes, the rubber is abraded by usage and, in time, the parts in question must be replaced. [0005] An object of the present invention is to provide a method of making a wear resistant liner which, at least in a preferred embodiment, can be implemented in a cost effective manner. SUMMARY OF INVENTION [0006] The invention provides a method of making a wear resistant liner which includes the steps of providing a backing plate, locating a first layer of a first material on the plate*, locating a second layer of a second material on the first layer and bonding the first layer to the plate and to the second layer, wherein the first material is a suitable polymer or rubber and the second material is a suitable polymer or rubber. [0007] As used herein "suitable polymer" includes polyurethane or any similar wear-resistant and abrasion resistant material. [0008] The first layer may be formed from a plurality of sheets of the first material e.g. uncured rubber. [0009] The f irst layer may be bonded to the plate at least through the medium of a suitable adhesive or bonding agent. [0010] If the first layer consists of a plurality of rubber sheets then the sheets can be bonded to one another by 37854051 (GHMatters) P91644.AU 19/10/12 -4 means of an appropriate vulcanising process i.e. by subjecting the sheets to an elevated pressure at an elevated temperature. [0011] The second material may comprise cured rubber which may be derived from any appropriate source. In one form of the invention the cured rubber is taken from a tread portion of a rubber tyre. The tread portion may be obtained by severing the tread portion from adjacent walls of a rubber tyre and then, as may be required, cutting the tread portion to a desired shape and size thereby to produce a product which is suitable for use as the second layer. [0012] The second layer may be bonded to the first layer by means of an adhesive or bonding medium which is positioned between opposing surfaces of the first layer and the second layer and which is activated in any appropriate way e.g. by means of pressure at an elevated temperature. [0013] The method may include the additional steps of providing a third layer of material e.g. uncured rubber on the second layer and overlying the third layer with a fourth layer of material e.g. cured rubber. These steps are implemented before the aforementioned bonding process takes place. Thus, when the bonding process is implemented, the first, second, third and fourth layers are bonded, sequentially, to one another and to the plate. [0014] At least one passage may be formed through the plate and through the layers of material which are bonded thereto. The size of a portion of the passage which extends through the plate is, preferably, smaller than the size of a portion of the passage which extends through the 37854051 (GHMatters) P91644.AU 19/10/12 -5 material layers. This permits a fastener such as a bolt to be inserted into the passage with a shank of the bolt passing through the passage (hole) in the plate and with a head of the bolt, which is located in a portion of the passage which extends through the material layers, abutting a portion of the metal plate which surrounds the passage which extends through the plate. BRIEF DESCRIPTION OF THE DRAWINGS [0015] The invention is further described by way of example with reference to the accompanying drawings in which: Figure 1 is a side view in section of various components which are included in a wear resistant liner during the course of manufacture thereof; Figure 2 illustrates the components of Figure 1 in an assembled configuration; Figure 3 is a perspective view of the components when bonded together; and Figure 4 is a side view in section illustrating how a fastening arrangement can be provided in the wear resistant liner. DESCRIPTION OF PREFERRED EMBODIMENT [0016] Figure 1 of the accompanying drawings is a side view in section and in an exploded configuration of components of a wear resistant liner 10 during the course of manufacture thereof. [0017] The wear resistant liner includes a backing sheet 12 which is made from a suitable grade of steel of an 37854051 (GHMatters) P91644.AU 19/10/12 -6 appropriate thickness and with desired properties, a first layer 14 of uncured rubber, a second layer 16 of cured rubber, a third layer 18 of uncured rubber and a fourth layer 20 of cured rubber. [0018] The first layer 14 of uncured rubber consists of a number of relatively thin sheets 22 of uncured natural rubber. The sheets are cut to size as appropriate and are placed one over the other in a stacked configuration to form the first layer. As appropriate a bonding agent, not shown, can be positioned between opposing surfaces of the respective sheets. [0019] The second layer 16 of cured rubber is preferably derived from recycled material. In one form of the invention discarded tyre material or discarded tyres are processed to recover tread sections thereof. For example if a discarded tyre is available then walls of the tyre are cut from the tread section which, thereafter, is cut to an appropriate size so that a component suitable for forming the second layer 16 is formed. It may be that according to requirement the size of the wear resistant liner is substantially larger than the dimensions of a tread section which may be recovered from a tyre. In this event two or more sections, cut as required, are assembled side-by-side to make up the layer 16. [0020] The third layer of uncured rubber is substantially the same as the first layer 14. It, too, is made from a number of relatively thin, uncured natural rubber sheets 22A. [0021] The fourth layer 20 of cured rubber is, for all practical purposes, the same as the second layer 16 of 37854051 (GHMatters) P91644.AU 19/10/12 - 7 cured rubber, and is formed from recycled cured rubber products e.g. tyres, typically truck tyres, or the like. As before, the recovered tread sections are cut to desired shapes and then assembled to make up the fourth layer with suitable dimensions. [0022] Of importance in the implementation of the method of the invention is the cleanliness of the cured rubber layers 16 and 20. If recycled material is used in this respect then the material is subjected to a strong cleaning and abrading action e.g. using wire brushes, wire wheels or the like. This action removes dirt from a surface of the rubber and, through abrasion, roughens the surface. This makes the surface more amenable to a bonding process. [0023] The various sheets 22 and 22A are normally of regular thickness. This however is not necessarily the case with the cured rubber layers, particularly if these layers are formed from recycled tyre tread sections. For example tread patterns may be embodied in the tread sections at the time of usage. This characteristic does not however impede the successful implementation of the method. [0024] A suitable bonding agent, not shown, is applied between opposing surfaces of the sheets 20, and 22A, and between opposing surfaces of the layers 14 and 16, 16 and 18, and 18 and 20, as appropriate. The layers are then positioned one over the other, as shown schematically in Figure 2. Thereafter pressure, designated by arrows marked "P"s in Figure 2, is applied to the assembly of layers to compress them together. This is done at an elevated temperature for an extended period. The uncured 37854051 (GHMatters) P91644.AU 19/10/12 -8 rubber is softened and is forced into close contact with an opposing surface of the cured rubber. As a result the layers are firmly bonded to one another and to the metal plate. A typical final product, which may have any appropriate length or width, is shown in perspective in Figure 3. [0025] In order to fix the wear resistant liner to a material handling device such as a chute, hopper, skip or the like, a number of passages are formed through the liner. Figure 4 depicts one passage 30 which passes through the layers 14 to 20 and through the steel plate 12. A portion of the passage which is in the plate has a diameter "d" while a portion of the passage within the layers 14 to 20 has a diameter "D" which is greater than "d" . The dimension "d" is slightly greater than a diameter of a shank 32 of a bolt 34. Similarly the dimension "D" is slightly greater than a transverse dimension of a head 36 of the bolt. Thus when the bolt is passed through the passage the shank can pass through the steel plate and the head can pass through the layers 14 to 20. The head however abuts material of the plate around the passage. The bolt is one of a plurality of similar bolts used to attach the wear resistant liner to a material handling device (not shown). It is evident that this is done in a way in which the head of the bolt is protected. [0026] It is generally recognised that cured rubber derived from a product such as a vehicle tyre is of a better quality than rubber which is provided in uncured form and which normally is used in the making of a wear resistant liner. The use of recycled cured rubber (from a water product), of this type, is therefore beneficial in that it 37854051 (GHMatters) P91644.AU 19/10/12 -9 offers an extended lifetime, compared to the rubber used in the layers 14 and 18. Also, cured rubber is usually available at a lower cost than an equivalent quantity of uncured rubber. It is self-evident that an additional benefit is that the recycling of waste tyres and waste tyre products is facilitated. [0027] In a variation of the invention the first layer 14 may be uncured rubber or a suitable polymer, the second layer 16 may be cured rubber or a suitable polymer, the third layer 18 may be uncured rubber or a suitable polymer and the fourth layer 20 may be cured rubber or a suitable polymer. [0028] A preferred suitable polymer is polyurethane. The polyurethane may be virgin or recycled material. [0029] According to requirement the polymer (preferably polyurethane) and the rubber, whether cured or uncured, can be used interchangeably. It is recognised however that bonding one layer to another layer may present a practical problem particularly if the layers are of different materials. To a considerable extent though this aspect can be addressed by forming dissimilar materials (e.g. rubber and polyurethane) with keying formations which enable the materials to bond to each other thereby providing not only an adhesive bond but also a mechanical interconnection between the materials. [0030] In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, 37854051 (GHMatters) P91644 AU 19/10/12 - 10 i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention. [0031] It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or any other country. 37854051 (GHMatters) P91644.AU 19/10/12

Claims (5)

1. A method of making a wear-resistant liner which includes the steps of providing a backing plate, locating a first layer of a first material on the plate, locating a second layer of a second material on the first layer and bonding the first layer to the plate and to the second layer, wherein the first material is a suitable polymer or rubber and the second material is a suitable polymer or rubber.

2. A method according to claim 1 which includes the steps of providing a third layer of material on the second layer and overlying the third layer with a fourth layer of material.

3. A method according to claim 1 or 2 which includes the step of forming at least one passage through the plate and through the layers of material which are bonded thereto.

4. A wear resistant liner which includes a backing plate, a first layer of a first material bonded to the plate and a second layer of a second material bonded to the first layer, and wherein the first and second material are selected from a suitable polymer and rubber.

5. A wear -resistant liner according to claim 4 wherein the rubber is selected from uncured rubber, cured rubber, and cured rubber taken from a tread portion of a rubber tyre. 37854051 (GHMatters) P91644.AU 19/10112