WO2001034348A1 - Implements and methods of manufacturing same - Google Patents

Abstract

An abrasive implement has a supporting member (1) with a central hub (2) mounting for use in connecting the member to a tool and an annular abrasive (4) support region surrounding the central hub. The supporting member is formed from an elastomeric polymer matrix. One or more abrasive elements (4) are partially embedded in the elastomeric polymer matrix to protrude from the supporting member on the side thereof facing away from the tool. A manufacturing method is disclosed which is suitable for forming a range of rotary abrasive implements including grinding discs, wire brushes, flap discs and stripping wheels.

Description

"IMPLEMENTS AND METHODS OF MANUFACTURING SAME"

BACKGROUND TO THE INVENTION Field of the Invention The present invention relates to implements, and in particular to implements such as grinding discs, wire brushes, flap discs and stripping wheels for connection to rotary power tools, and to methods of manufacturing same.

SUMMARY OF THE PRIOR ART Implements such as grinding discs, wire brushes, flap discs and stripping wheels, despite their similar applications are presently formed in almost entirely unique manners. For example grinding wheels are formed in their final disc form from compressed particles reinforced by one or more fibre glass reinforcing webs and then baked. Wire brushes are formed by arranging an array of wire elements in the open end of a cup, and then crimping the cup to grip the array of elements. Stripping wheels are formed by punching out and gluing a pad of abrasive material to a plastic backing disc which incorporates the hub for connecting to the power tool (an angle grinder, for example).

This range of manufacturing techniques has made it difficult for one manufacturer to produce a complete range by requiring a large array of production machinery and consequent overheads. The array of products and sources has made it difficult for consumers to make simple choices. The products formed using the traditional processes are not similar in appearance or specification.

At an individual product level the products, particularly the grinding disc, wire brush and stripping wheel products, are unstable at high speeds due to the centrifugal forces, and if used at speeds that are too great, or over stressed during use, may break up, releasing parts of themselves at high speed and causing considerable danger. For this reason they have limited operating speeds, but even so there is always a risk that a defect in the product may lead to such catastrophic failures.

SUMMARY OF THE INVENTION It is an object to provide implements and methods of manufacturing same which at least go some way toward overcoming the above disadvantages or which will at least provide the public with a useful choice.

Accordingly in one aspect the invention consists in an abrasive implement comprising: a supporting member having a central hub mounting means for use in connecting said member to a tool and an annular abrasive support region surrounding said central hub, said supporting member formed from an elastomeric polymer matrix, and, one or more abrasive elements partially embedded in said elastomeric polymer matrix to protrude from said supporting member on a side thereof facing away from said tool. In one further aspect the invention consists in an abrasive implement as set forth above wherein said abrasive element comprises an annular pad of open matrix abrasive material located concentrically around said hub, and embedded in said polymer matrix such that said polymer matrix infuses at least a part of said open matrix.

In another further aspect the invention consists in an abrasive implement as set forth above wherein said abrasive element comprises one or more pieces substantially closed matrix abrasive material, each said piece having one or more detents or protrusions into or around which said polymer matrix of said supporting member extends to interlock said polymer matrix and the respective said piece.

In a still further aspect the invention consists in an abrasive implement as set forth above wherein said abrasive element comprises an array of wire elements embedded in said polymer matrix and having free ends thereof clear of said polymer matrix.

In a yet further aspect the invention consists in an abrasive implement as set forth above wherein said abrasive elements comprise an annular array of flat abrasive carrying members, each carrying abrasives on the face thereof facing away from said supporting member, adjacent member in said array overlapping, each member in said array having an edge thereof embedded within said polymer matrix and being held over to lie substantially flat against an adjacent said member.

In a still further aspect the invention consists in a method for making an abrasive tool including the steps of: pooling an elastomeric polymer resin in an open topped mould to define a hub region and an annular abrasive support region surrounding said hub region, and before said resin gels applying a part of each of one or more abrasion means into said resin of said abrasive support region, such that the remainder of each said abrasion means extends clear of said resin.

In a yet further aspect the invention consists in an abrasive tool manufactured according to the above method.

To those skilled in the art to which the invention relates, many changes in construction and widely differing embodiments and applications of the invention will suggest themselves without departing from the scope of the invention as defined in the appended claims. The disclosures and the descriptions herein are purely illustrative and are not intended to be in any sense limiting.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a perspective view from below of a stripping disc according to the present invention,

Figure 2 is a pian view of the stripping disc of Figure 1,

Figure 3 is a cross section on AA of the stripping disc of Figure 2,

Figure 4 is a plan view of a grinding disc according to the present invention,

Figure 5 is a cross section on BB of the grinding disc of Figure 4, Figure 6 is a plan view of a wire brush according to the present invention,

Figure 7 is a cross section on CC of the wire brush of Figure 6,

Figure 8 is a plan view of an alternative grinding disc according to the present invention,

Figure 9 is a perspective view of the grinding disc of Figure 8 as it would appear if the step in the manufacture thereof of bending down the abrasive holding members was not completed,

Figures 10A to 10F depict the basic steps of manufacturing an implement according to the present invention,

Figure 11 is a flow diagram further demonstrating the steps in manufacturing an implement of the present invention, and

Figure 12 is a flow diagram further demonstrating the steps in manufacturing an implement of the present invention, in particular being the flap disc of Figure 8.

Figure 13 is a cross section on CC of a wire brush according to the present invention and including a steel reinforcing ring. DETAILED DESCRIPTION

Referring then to Figures 1 to 3 the basic form of implement according to the present invention has an elastomeric plastic supporting member 1 which includes a hub portion 2 at its centre. The hub portion 2 is shaped to conform with standard grinding disc shapes that are used with existing power tools, such as angle grinders. To these ends the hub portion 2 may be raised from the level of the remainder of the supporting member 1, for example through a conical transition 3.

It should be noted that while a recessed hub is advantageous, as it keeps the nut which secures the implement to the power tool clear of the work piece, it is not a required feature. Implements can be made in which the hub is not raised from the remainder of the supporting member. Furthermore, rather than being designed for securing to the power tool by a securing nut, the implement may be adapted for direct connection to the threaded shaft of the power tool, for example having a threaded bore through the hub region for direct threaded connection to the power tool shaft. Such a threaded bore may be provided through a metal boss embedded in the plastic hub.

The implement has an abrasive element, in this case an annular pad 4 of open matrix abrasive material, embedded in the plastic supporting member 1. In other forms of the invention, such as depicted in Figures 4 to 9, the abrasive element takes other forms to create implements particularly adapted for different purposes. In the embodiment of Figures 1 to 3 the annular pad 4 is formed from a material that, while abrasive, is comparatively soft and is known not to damage steel. This material may for example be a non-woven pad of polymer filament, impregnated and stabilised with a bonding agent to give it structural integrity, and with silicon carbide particles dispersed throughout the non-woven pad and bonded in place by the bonding agent. Retaining some flexibility and having an abrasive density too low to damage underlying steel surfaces, the material is particularly useful for stripping coatings

(including rust or corrosion) from metal surfaces or other underlying surfaces. This material may be manufactured in accordance with the methods set forth in US Patent 4227350.

In the embodiment of the present invention depicted in Figures 1 to 3 the open structure of the pad 4 of abrasive material is infused with and effectively merged with the supporting member 1. That infusion helps to connect the pad 4 to the supporting member 1, irrespective of any bonding properties of the plastic resin.

In the preferred forms of the present invention the plastic supporting member 1 is formed from a urethane elastomer such as NEBRATHANE B876 available from C K Witco or ADIPRENE LF750D available from Uniroyal Chemical Co. These products are both toluene diisocyanated (TDI) based polyurethanes. Other products could be used, such as PNC, polyesters and epoxies, but because none of these are elastomeric, they are less able to withstand impact and stresses during use. This plastic material is used because it is chemical setting and consequently will remain in liquid form at room temperature for some (controllable) time before setting. This allows the abrasive element to be partially submerged within the resin, with the resin flowing around (and into) the voids in the abrasive element without the resin filling a mould cavity under pressure as an injection moulded plastic would. Due to the injection pressure an injection moulded plastic would completely fill the open matrix of an open matrix pad and/or completely surround any inserted abrasive elements. The preferred resin allows an open topped mould to be used, into which the resin may be pooled, and the abrasive elements subsequently inserted through the open top, from above. The pooling of the resin under gravity gives a substantially flat and level upper surface to the resin, in or around the abrasive element(s), although some wicking may occur through capillary action with certain abrasive elements, for example open matrix structures or closely bundled linear elements.

Amongst thermoset polymer materials certain subsets have been found to have desirable properties. Testing of prototypes has shown that TDI-based thermoset elastomeric polymer resin systems exhibit substantially better properties than MDI-based resin systems or non-elastomeric resin systems. Tests were conducted on prototype abrasive discs of the type described with reference to Figures 1 to 3 and made according to the method of Figures 10A to 10F and 11 (described below). The discs were made with a nominal maximum diameter of 115 mm. In each test the abrasive disc was fitted to a the mounting post of a test rig designed to simulate the mounting post of a typical angle grinder. The test rig was capable of rotating the discs at speeds up to 30,000 RPM. The rotational speed of the disc was gradually increased until such time as the disc ruptured, and the rupture speed was recorded.

A prototype disc manufactured using a TDI-based polymer resin system - sold as

ADIPRENE L315 by Uniroyal - failed catastrophically at a rotational speed of 29,000 RPM.

It is considered that the success of the TDI-based resin systems in achieving high rotational speeds before bursting lies in the combination of strength and flexibility.

The method of manufacture of the implement of Figures 1 to 3 is described with reference to the flow chart of Figure 11 and the illustrations of Figures 10A to 10F.

Referring to Figure 10A the first step 100 in the process is to assemble the mould. The mould is preferably formed in three parts - a cup formed by a wall part 20 and a floor part 21 , and a hub forming cap 22. The mould could simply be a one piece cup part, but to get the favourable and conventional disc geometry in the hub region (necessary for use with existing equipment) the resin is most easily formed from above by a cap 22. The cup part is preferably made of a wall part 20 and a floor part 21 to simplify extraction of the moulded component as will be described later. The wall part 20 includes a floor 23 of its own on which the floor part 21 sits when assembled, and an upwardly extending cylindrical wall 24. The floor 23 spans the opening of between the cylindrical wall 24 of the wall part 20. The floor 23 has openings 54 there through which provide access for removing the floor part 21 by pushing from below. A cylindrical upstand 25 extends upwardly from the floor 23 of the wall part 20 at the centre thereof. This upstand 25 forms the bore through the hub of the implement and also supports the cap 22 in its correct alignment and at its desired height. The three parts are assembled by bringing, as indicated by arrows 31, the floor part 21 within the open space of the wall part 20, such that the upstand 25 passes through central bore 26 of the floor part 21, and the lower face 27 of the floor part 21 butts against upper surface 28 of the floor 23 of the wall part 20. Complimentary annular steps 29, 30 may be provided at the edge of each of the wall part 20 and floor part 21 respectively, to assist alignment. The cap 22 is brought into the assembly as indicated by arrows 32 such that the cylindrical upstand 25 fits inside central bore 33 of the cap 22 until the upper face 34 of the upstand 25 butts against the end face 35 of the bore 33.

It will be appreciated that a two part mould would be equally possible, with a slight draft provided in the mould walls (including on the cylindrical upstand 25) to allow for removal of the moulded part. In this case, for example, the floor part and the wall part would effectively be combined as a single part. Furthermore, if implements are desired which do not have a recessed hub, then the cap part can be dispensed with, and the thickness of the hub portion controlled simply by the amount of resin introduced. This latter technique is not recommended as it could lead to significant variation in hub thickness.

The assembled mould is illustrated in Figure 10B. The outer edge of the floor part 21 matches closely the inner surface 22 of the wall 24 of wall part 20 so that once the parts are assembled there is no discernable space between these surfaces through which resin might flow. It is too be remembered though that in the present invention the resin is not under pressure and so a pressure fit between the parts is not required. A similar fit is maintained between the inner cylindrical surface of the bore 33 of cap 22 and the outer cylindrical surface of the upstand 25.

The cap 22 has a lower surface profile 36 which will determine the lower or inner surface profile of the hub of the implement being formed. The upper surface profile 37 of the floor 21 will determine the upper or outer surface of the implement being formed. In the present embodiment the preferred profile includes a hub raised from the level of the remainder of the disc, and so the surface profiles 36 and 37 include complimentary frusto-conical protrusion and depression respectively. The cap 22 is supported by the upstand 25 such that there is a space between the lower surface profile 36 thereof and the upper surface profile 37 of the floor part 21. This spacing determines the thickness of the hub portion of the disc.

Referring now to Figure 10C the next step 101 in the manufacturing process is to pour the liquid resin 38 into the assembled mould. The liquid resin 38 may for example be poured from a nozzle 39 into the open mould cavity 40. The liquid resin pools in the open mould cavity, flowing firstly into the hub forming region between the cap 22 and the floor part 21 , and filling the mould cavity from the bottom first until the pouring is discontinued. Referring to Figure 1 OD the resin is sufficiently liquid to flow easily around the mould cavity, and pools under the influence of gravity to form a flat and even surface level 41 across the mould cavity, interrupted at the centre by the upstand 25 and the cap 22, and filling the hub forming region. The next step 102 is to insert the abrasive element (or elements, as will be described later in respect of further implement embodiments) into the mould cavity. In the form of implement being described now, the abrasive element is an annular pad of open matrix abrasive material. This pad 42 has an outer diameter that is just less than the inner diameter of the cylindrical wall 24 of the wall part 20, and an inner diameter that is just greater than the outer diameter of the cap 22, so that it just fits within the annular open cavity of the mould assembly.

The pad 42 is introduced as indicated by arrows 43. The pad 42 is pushed into the cavity so that it partially submerges within the liquid resin, such as is indicated in Figure 10E. With the open matrix of the pad, the resin flows to fill the cavities in the open matrix and the submerged portion 44 of the pad 42 becomes infused with liquid resin. If it is desired to stop the pad from appearing in the upper surface of the implement, then the floor part 21 may include an annular step 45 on its upper surface upon which the outer edge of the pad 42 rests to space the pad 42 from the upper surface of the floor part 21. The next step 103 is to wait for the resin to set sufficiently that the mould can be disassembled and the formed implement removed without damage. With TDI based resin systems the gel time can be controlled by controlling the temperature of the resin. For efficient manufacturing the set-off time needs to be sufficiently long that the abrasive pad element(s) can be introduced and the resin can flow in/around the element(s) as necessary before the resin begins to set, but the set-off time must also be sufficiently short that manufacturing time is not prohibitively long. A suitable set-off time with the above resin would be about 2 minutes. If it is desired that the abrasive elements not protrude completely through the resin, then in the earlier step 101 of pouring the resin may include in stead a two-part process. In particular a first amount of resin may be poured into the mould and left to partially react and gel. A further amount of resin to complete the necessary amount of resin is then poured into the mould, and the abrasive elements are inserted into this resin to but up against the resin that was poured earlier and has now set. This is considered particularly useful where elements such as wires are being used, which cannot be controlled simply by providing a ledge or shelf around the edge of the mould cavity.

Once the resin has been allowed its initial setting time the mould is disassembled as indicated in Figure 10F by the step 104 of removing the cap 22, as indicated by arrow 46 and then the step 105 of pushing out the floor part 21 from within the wall part 20 as indicated by arrows 47. As has already been described, openings 54 are provided in the floor 23 of the wall part 20 through which force can be applied to the back of the floor part 21.

The implement may now be easily removed (step 106) from the floor part 22, which has no steep drafts or other surfaces that might inhibit removal, without damage, or alternatively it may remain on the floor part 22 until it has gone through the final curing stages. The removed implements (or non-removed as applicable) are accumulated (step 107) until a set number have been collected. At that time they are transferred to a curing oven to be cured (step 108) at an elevated temperature for a set period of time. With the resin described earlier the curing at 115°C for 16 hours would be appropriate. As an alternative process, if sufficiently large quantities are being produced then curing in a continuous oven (having a slow moving transport system) may be more economical.

An open mould casting process such as that described above is thought to be of particular advantage in the forming of abrasive implements. It allows the use of thermoset polymers, and in particular elastomeric polymers. These polymers dictate a long cycle time, but the open top mould form as described is sufficiently cheap that parallel manufacturing of larger numbers of implements can be undertaken for the same capital outlay as a much smaller number in an injection based system. Open mould casting allows gravity pooling of resin to a desired level which reduces resin wastage through over infiltration of the abrasive elements (eg: complete immersion as would occur under pressure). The open topped mould accommodates height variation in the abrasive elements. Consequently each mould may be used in the manufacture of a variety of types of implement and of a variety of implements within a type. The open topped moulding process allows production of implements that could not be manufactured in a closed mould. For example the flap disc requires access to the flaps prior to full gelling of the polymer so that they can be folded down. With an open mould process the abrasive elements are inserted after the resin is poured. Consequently there will be a reduction in abrading of the mould surface by the abrasive elements. If any abrading does occur, the cost of mould replacement will be low compared with an equivalent injection mould tool. Referring now to Figures 4 and 5 one alternative embodiment of the invention is shown.

This embodiment of the invention is a grinding disc, again for use with existing power tools, for example angle grinders. The grinding disc is intended for use, for example, with metals, and consequently the open matrix structure of the abrasive element of the earlier embodiment, with its low density of abrasive particles, is not generally sufficient. In the embodiment of Figures 4 and 5 the abrasive element comprises a preformed ring of grinding material (of conventional composition) embedded within the polymer matrix of the supporting member 11. To accommodate the elastomeric nature of the plastic material, and to allow the advantageous properties of it to be properly utilised, the ring of grinding material may comprise a number (for example 6) of blocks 10 of grinding material. The blocks 10 may be completely independent or they may be joined by thin bridges of grinding material, for example adjacent the back faces thereof, so that in manufacture they can be handled and placed as a single unit. These blocks 10 replace the pad 42 in the forming process as described above. To improve the securing of the blocks 10 to the supporting member the blocks may include protrusions, cavities or other "keying" surface features on their back face, into or around which the resin of the supporting member intrudes to lock the blocks to the supporting member. The blocks may for example consist of phenolic resin coated abrasive grains in the size range of 16# to 120#, pressed and cured to give a volume ratio of 50% abrasive, 35% bonding resin and 15% voids. Referring now to Figures 6 and 7 a still further embodiment is shown, the implement being a wire brush attachment. The same basic supporting member and manufacturing method is used, however rather than the open matrix pad of abrasive material a plurality of upwardly aligned wire bristles 70 is inserted into the liquid resin, to protrude (once cured) from the supporting member 71. In the preferred form the portion of each bristle which is to be embedded within the polyurethane resin is first coated with a suitable primer to improve adhesive bonding of the resin to the material of the bristle. For example with steel bristles and a castable urethane elastomeric resin one suitable primer might be CHEMLOC 213 sold by Lord Corporation.

Where heavy gauge steel bristles are used at a moderate to high density and with a substantial protruding length then centrifugal forces on the bristles may lead to flexing or dishing of the supporting member 71 when the implement is rotated at speed. One solution to this problem is illustrated in Figure 13. This involves the inclusion of a reinforcing ring 72 within the polymer matrix of the supporting member 71. The reinforcing ring 72 may for example be an annular steel ring, preferably located adjacent the periphery of the supporting member 71. The steel ring 72 may be stamped from a mild steel sheet, and for efficient material usage concentric rings may be stamped from the single sheet for use in different diameter wire brush implements. The mild steel ring may be submerged in the liquid resin prior to insertion of the steel bristles. Once the resin solidifies the steel ring is encased by the hardened polymer. As with the wire bristles it is preferred that the steel ring be primed prior to insertion, for example with CHEMLOC 213. This improves adhesion of the resin to the steel ring. In use the steel ring significantly limits the deformation or dishing of the abrasive disc due to centrifugal forces on the brush bristles.

It will be appreciated that a wide range of bristle material may be applicable. The wire brush implement has been described with reference to steel wire bristles, which may be of varying gauge. In addition monofilament bristles, including those loaded with abrasive material might be used, for example nylon monofilament bristles loaded with aluminium oxide or silicon carbide particles might be used for some applications.

A still further embodiment of the invention is shown in Figures 8 and 9, which show an alternative form of grinding disc commonly referred to as a flap disc. In this form of grinding disc the abrasive material is held on an annular series of overlapping planar sheets 80. As the sheets wear down more abrasive is exposed. In the process of manufacture the step of inserting the abrasive elements is replaced by a two step procedure (see Figure 12), in that it involves sequentially inserting each of the elements (on edge) into the pooled resin (step 85) so that the inserted edges of the sheets 80 are slightly embedded within the resin, and then (either immediately or after a set delay period to allow some setting-off of the resin too occur) sequentially folding down all of the elements in a circumferential manner so that the sheets each overlap at least one of their neighbours and are overlapped by at least one of their neighbours. The illustration in Figure 8 is as if this latter step 86 was not completed and shows the sheets standing on edge as they have been inserted. The resin cures after the sheets have been folded down and holds them in the folded down configuration.

Prototype wire brushes and flap-discs manufactured using ADIPRENE LF750D resin were subjected to a further test. The rotational speed was gradually increased to 13,500 RPM (the maximum intended rated speed of the disc. With the speed maintained the disc was subjected to extremely aggressive pressure against a work piece. This test was designed to show up any propensity for non-catastrophic damage through over-aggressive use.

A prototype 115 mm diameter wire brush was manufactured without a steel reinforcement, and without the inserted bristle ends being prep-prepared by priming or deformation. At 10,500 speed the disc was found to flex into a dish shape due to the inertia of the wire bristles. The total displacement out of plane of the circumference relative to the hub due to the rotational speed was approximately 5 mm. The brush had steel bristles extending approximately 25mm from the surface of the support disc. On aggressive working several of the 1600 bristles became removed from the support disc.

A prototype 115 mm wire brush was manufactured with a steel reinforcing ring 110 mm outside diameter, 5 mm wide and cut from a 2mm thick mild steel sheet. The inserted bristle ends were prepared by priming with CHEMLOC 213 before insertion. The bristles extended 15 mm from the surface of the upper disc. At 10,500 rpm the total displacement out of plane of the circumference relative to the hub due to the rotational speed was less than 1 mm. No bristles were lost during aggressive working.

A prototype 115 mm flap disc was manufactured. No flaps were lost from the disc on aggressive working.

It can be seen that the present invention allows manufacture of a range of implements using substantially the same basic technique. Furthermore it has been found that products manufactured according to this method are extremely resistant to breakage, even at what would normally be considered very high rotation speeds. It is thought that some of this strength is due to the chosen material which not only suites the manufacturing method by allowing partial infusion and submersion of the abrasive elements, but due to its elastomeric nature also tends to elastically deform (possibly with some creep) significantly before final failure. For a product of the present type this has significant safety benefits as the deformation before failure will be sufficiently great to alert a user to the problem, and the product itself is a short life commodity item, and so the effect of any creep over the life of the item should be negligible.

These characteristics prove particularly well adapted to a recently developed form of abrasive implements which are "see through" in use. These implements have cut outs or holes which allow a user to view the workpiece behind the implement when the "disc" is rotating at speed. To date this technique has only been applied to sanding pads (such as marketed by Norton under the AVOS brand), and the traditional methods of forming other abrasive implements have so far restricted wider use. For example, grinding discs formed in the traditional way would be subject to early failure if they included the necessary cutouts, with considerable danger, and wire brushes could not be manufactured in the existing manner at all.

However the manufacturing method of the present invention enable manufacture of safe implements including the cut-outs and openings across the entire range. In each case the overall toughness of the urethane elastomeric backing material, and its useful manner of slow creep rather than catastrophic failure, will provide significantly improved safety. The method of manufacture will allow the form of the implement and the layout of abrasive elements to be easily varied however may be required.

Claims

CLAIMS:

1. An abrasive implement comprising: a supporting member having a central hub mounting means for use in connecting said member to a tool and an annular abrasive support region surrounding said central hub, said supporting member formed from an elastomeric polymer matrix, and, one or more abrasive elements partially embedded in said elastomeric polymer matrix to protrude from said supporting member on a side thereof facing away from said tool.

2. An abrasive implement as claimed in claim 1 wherein said elastomeric polymer is a

TDI-based urethane elastomer.

3. An abrasive implement as claimed in claim 1 wherein said abrasive element comprises an annular pad of open matrix abrasive material located concentrically around said hub, and embedded in said polymer matrix such that said polymer matrix infuses at least a part of said open matrix.

4. An abrasive implement as claimed in claim 3 wherein said open matrix abrasive material comprises a non- woven pad of polymer filament, impregnated and stabilised with a bonding agent to give it structural integrity, and abrasive particles dispersed throughout the non-woven pad and bonded in place by the bonding agent.

5. An abrasive implement as claimed in claim 1 wherein said abrasive element comprises one or more pieces substantially closed matrix abrasive material, each said piece having one or more detents or protrusions into or around which said polymer matrix of said supporting member extends to interlock said polymer matrix and the respective said piece.

6. An abrasive implement as claimed in claim 5 wherein said substantially closed matrix abrasive material comprises a matrix of phenolic resin coated abrasive grains pressed and cured to give a rigid abrasive block with a porous but substantially closed structure.

7. An abrasive implement as claimed in claim 1 wherein said abrasive element comprises an array of wire elements embedded in said polymer matrix and having free ends thereof clear of said polymer matrix.

8. An abrasive implement as claimed in claim 7 wherein an annular reinforcing element is embedded is said polymer matrix.

9. An abrasive implement as claimed in claim 8 wherein said reinforcing element comprises a steel ring.

10. An abrasive implement as claimed in claim 1 wherein said abrasive elements comprise an annular array of flat abrasive carrying members, each carrying abrasives on the face thereof facing away from said supporting member, adjacent members in said array overlapping, each member in said array having an edge thereof embedded within said polymer matrix and being held over to lie substantially flat against an adjacent said member.

11. A method for making an abrasive tool including the steps of: pooling an elastomeric polymer resin in an open topped mould to define a hub region and an annular abrasive support region surrounding said hub region, and before said resin gels applying a part of each of one or more abrasion means into said resin of said abrasive support region, such that the remainder of each said abrasion means extends clear of said resin.

12. A method as claimed in claim 11 wherein said method includes the steps of: waiting for said resin to gel, removing the abrasive tool from the mould, and curing said resin at an elevated temperature.

13. A method as claimed in either claim 11 or claim 12 wherein said method includes, before applying said abrasion means into said resin, the step of: fitting a first mould forming component to a second mould forming component, said second mould forming component including a cup for containing said pooled resin, the profile of said cup determining the profile of the non-abrasive side of said implement and said first mould forming component at least partly intruding into the space occupied by or to be occupied by the pool of resin, the hub region of said implement being formed between said first and second mould forming components.

14. A method as claimed in any one of claims 11 to 13 wherein said method includes, for forming a stripping implement, partially submerging an annular, open matrix, abrasive pad within the pooled resin such that said resin infuses said open matrix.

15. A method as claimed in any one of claims 11 to 13 wherein said method includes, for forming a grinding implement, partially submerging one or more pieces of substantially closed matrix abrasive material, each said piece having one or more detents or protrusions into said pooled resin, such that said resin flows into or around said detents or protrusions.

16. A method as claimed in any one of claims 11 to 13 wherein said method includes, for forming a wire brush inserting an array of wire elements partially into said resin such that the free ends thereof are clear of said pooled resin.

17. A method as claimed in claim 16 wherein said method includes preparing the inserted ends of the wire elements to enhance their physical or chemical bonding with the elastomeric resin, prior to inserting the elements into the pooled resin.

18. A method as claimed in claim 17 wherein said step of preparing said wire elements comprises coating said wire elements with a primer conducive to bonding with said elastomeric polymer resin.

19. A method as claimed in any one of claims 16 to 18 wherein said wire elements are inserted into said pooled resin to a depth less than half the length of said wire elements and prior to the said step of inserting said wire elements said method includes the further step of inserting an annular steel ring within said open topped mould to be embedded within said abrasive support region.

20. A method as claimed in any one of claims 11 to 13 wherein said method includes, for forming a grinding implement, partially submerging one edge of each member of an annular array of flat abrasive carrying members, each carrying abrasives on a least one face thereof, such that said members stand vertically and are substantially radially aligned, and having inserted all of said members of said array, then flattening said members of said array against one another, so that each member lies substantially on top of one of its neighbours in series around said annular array with each having one edge thereof still residing in or on said pool of resin.

21. A method as claimed in any one of claims 11 to 20 wherein said step of pooling resin includes pooling said resin in said mould in two distinct stages, the timing of said pooling stages and the timing of said application of said abrasive elements into said resin, and the gel time of said resin being such that the resin poured in said first stage has gelled at least before said abrasion means are introduced into the resin poured in said second stage.

22. An abrasive tool manufactured according to a method as claimed in any one of claims 11 to 21.

23. An abrasive implement substantially as herein described with reference to and as illustrated by Figures 1 to 3 of the accompanying drawings.

24. An abrasive implement substantially as herein described with reference to and as illustrated by Figures 4 and 5 of the accompanying drawings.

25. An abrasive implement substantially as herein described with reference to and as illustrated by Figures 6 and 7 of the accompanying drawings.

26. An abrasive implement substantially as herein described with reference to and as illustrated by Figure 6 and 13 of the accompanying drawings.

27. An abrasive implement substantially as herein described with reference to and as illustrated by Figure 8 of the accompanying drawings.

28. A method substantially as herein described with reference to and as illustrated by Figures 10A to 10F and 11 of the accompanying drawings.

29. A method substantially as herein described with reference to and as illustrated by Figures 10A to 10F, 11 and 12 of the accompanying drawings.