TECHNICAL FIELD

The present invention relates to abrasive members suitable, in particular, for providing endless abrasive surfaces (for example endless abrasive belts) such as may be found in abrading machines of various types.

BACKGROUND OF THE INVENTION

Powered sanding and grinding machines which employ abrasive belts are available in many different forms for a wide variety of applications. Generally, the endless abrasive belt is mounted around rollers at least one of which is driven so that the belt can be rotated and apply an abrasive action to a workpiece. Machines which employ some form of rotatable drum, instead of a belt, to provide the endless abrasive surface are also known and are also available in many different forms. DE-C-40 32 889 describes a drum sander in which the abrasive surface is provided by an abrasive belt releasably fastened on the outer surface of a drum body. The abrasive belt is open-ended and is wrapped around the surface ofthe drum. To secure the belt to the drum, the surface ofthe latter is covered with barbs which interlock with a loop fabric on the back ofthe abrasive belt.

SUMMARY OF THE INVENTION

The present invention provides an abrading machine comprising an endless backing belt, and an abrasive member positioned around and releasably attached to the backing belt to provide a continuous abrasive surface on the backing belt. Preferably, the opposite ends ofthe length of sheet material are contoured so that they interlock.

The invention also provides an abrading machine comprising an endless rotatable backing surface, and an abrasive member positioned around and releasably-attached to the backing surface, wherein the opposite ends ofthe abrasive member are contoured so that they interlock to provide a continuous abrasive surface on the backing surface.

The invention further provides an abrasive belt support and drive system for use with an abrading machine, the system comprising. a. a first roller configured to support a backing surface at rest and during rotation; b. an endless rotatable backing surface including a front surface for supporting an abrasive belt and a back surface for engagement with the first roller, wherein the backing surface is disposed around the first roller; c. a length of abrasive material including a first end and a second end, a front surface for abrading a workpiece and a back surface for engagement with the backing surface, the abrasive material being positioned around and releasably attached to the front surface ofthe backing surface, to provide a continuous abrasive surface on the backing surface. Advantageously, the first and second ends ofthe length of abrasive material are interlocked, and are contoured such that the first and second ends may be disengaged by lifting one ofthe ends out ofthe plane of the other end.

In accordance with another aspect ofthe invention, there is provided an abrasive belt comprising an endless backing belt, and an abrasive member positioned around and releasably-attached to the backing belt to provide a continuous abrasive surface on the backing belt. Preferably, the opposite ends ofthe length of sheet material are contoured so that they interlock.

The invention further provides an abrasive belt comprising an endless backing belt having a front surface, and a length of abrasive material having a first end, a second end, a front surface for abrading a workpiece, and a back surface for engaging the backing belt, the abrasive material positioned around and releasably- attached to the front surface ofthe backing belt, to provide a continuous abrasive surface on the backing belt. Advantageously, the first and second ends ofthe length of abrasive material are contoured so that they interlock such that either ofthe first and second ends can be lifted out ofthe plane ofthe other end to disengage the first and second ends. In accordance with yet another aspect ofthe invention, there is provided for use in combination with an endless backing belt, an abrasive member suitable for

attachment to the backing belt, the back ofthe abrasive member being formed for releasable attachment to the backing belt and having a length which is sufficient to enable the sheet material to be positioned around the backing belt to provide a continuous abrasive surface on the backing belt. The invention also provides an abrasive member suitable for attachment to an endless backing surface, the back ofthe abrasive member being formed for releasable attachment to a backing surface and having a length which is sufficient to enable the abrasive member to be positioned around an endless backing surface, wherein the opposite ends ofthe length of sheet material are contoured so that they interlock.

The invention further provides abrasive material suitable for attachment to an endless backing surface, comprising first and second ends, a front surface for abrading a workpiece, and a back surface opposite the front surface, the back ofthe abrasive material being formed for releasable attachment to a backing surface and having a length which is sufficient to enable the abrasive material to be positioned around an endless backing surface. Advantageously, the first and second ends of the length of abrasive material are contoured so that they interlock.

BRIEF DESCRIPTION OF THE DRAWINGS By way of example only, embodiments ofthe invention will be described with reference to the accompanying drawings, in which:

Fig. 1 illustrates, diagrammatically, one form of abrading machine employing an endless abrasive belt;

Fig. 2 shows a plan view of an abrasive member in accordance with the present invention;

Fig. 3 is a diagrammatic side view of a backing belt for use with the abrasive member of Fig. 2;

Fig. 4 illustrates, diagrammatically, the construction of an abrasive belt in accordance with the invention; Fig. 5 illustrates, diagrammatically, the construction ofthe abrasive member of Fig. 2;

Fig. 6 illustrates, diagrammatically, the construction ofthe backing belt of Fig. 3; and

Fig. 7 shows a plan view of part ofthe abrasive belt of Fig. 4.

DETAILED DESCRIPTION OF THE INVENTION

The machine illustrated in Fig. 1 may be one part of a hackstand machine and comprises an endless abrasive belt 1 mounted around rollers 2a and 2b respectively, one of which is driven by a motor (not shown) to rotate the belt and thereby apply an abrasive action to a workpiece 3. For clarity, only the rollers 2a and 2b are illustrated. The configuration and construction of abrading machines of the type employing rollers such as 2a and 2b is well known in the art and need not be further described herein. Together, the rollers 2a and 2b, and the abrasive belt 1 will be referred to herein as an abrasive belt support and drive system 8.

The machine referred to in Fig. 1 is just one of many known types of abrading machine, which employ abrasive belts. Typically, the belt is a coated abrasive having a backing which is appropriate to the intended use ofthe belt. The backing may, for example, be a fabric formed from natural materials, for example cotton, and/or synthetic materials, for example nylon or polyester. Different abrading machines generally require belts of different sizes, and different applications ofthe same machine require abrasive belts of different grades. An abrasive belt must, of course, be replaced when it becomes worn but may also have to be changed, before it becomes worn, if a belt of a different grade is required. Fig. 2 shows an abrasive member 10 for use in combination with a non- abrasive backing belt 11 (Fig. 3) to provide an alternative form of abrasive belt. The backing belt 11 will be described in greater detail below. The abrasive member 10, which is shown separate from the belt 11 in Fig. 2, is intended to be releasably- attached along its non-abrasive back side to the belt and is ofthe same length as the latter. In addition, the ends 12 A, 12B ofthe abrasive member 10 are of a shape configured to interlock and provide a continuous abrasive surface on the backing belt in an interlocked arrangement which cannot be easily disengaged unless one of the ends is moved vertically out ofthe plane ofthe other end. For example, the end

12A ofthe member 10 is formed with a bulbous projection 13A which is shaped to fit into a correspondingly-shaped notch 13B in the other end 12B (i.e. the ends have a jig-saw shape).

The backing belt 11, shown in Fig. 3, is an endless rotatable belt mounted around rollers 14a and 14b in an abrading machine. The abrading machine may, for example, have the roller arrangement ofthe type illustrated in Fig. 1 in which case the rollers 14a and 14b correspond respectively to the rollers 2a and 2b.

The backing belt 11 is formed from any suitable material, preferably a comparatively heavy-duty, durable material. Suitable materials for the backing belt 11 are cloth and other sheet materials, for example paper, plastic film, leather, etc. When cloth is used for the backing belt 11 it may be woven or non-woven and may be formed from natural fibers (for example cotton) and/or synthetic fibers (for example polyester, nylon). The cloth may be impregnated or saturated with curable resins to confer additional strength and water/oil repellence. Generally, any material used as the backing of a conventional abrasive belt could be useful for the backing belt 11 of Fig. 3. However, other materials can also be used, as noted below.

The abrasive member 10 may be any suitable abrasive material covered, on its back surface, with one part of a mating surface attachment surface, e.g. a hook and loop attachment system while the backing belt 11 is covered, on its front surface, with the other part ofthe mating surface attachment system. In the particular embodiment illustrated in Figs. 5 and 6, the abrasive member 10 comprises a conventional coated abrasive sheet material 15 the back surface of which is laminated to a loop fabric component 16 of a hook and loop attachment system, and the backing belt 11 carries on its front surface the hooked component 17 ofthe attachment system. To attach the abrasive member 10 to the backing belt 11, it is necessary only to position the abrasive member 10 so that it extends completely around the belt 11 and then to press the abrasive member in position with the ends 12 A, 12B interlocked as shown in Fig. 7. The engagement ofthe back surface ofthe abrasive 10 with the front surface of backing belt 11 is partially illustrated in Fig. 4.

Preferably, the abrasive member 10 is positioned on the belt 1 1 so that the projection 13A is directed against the direction of movement ofthe belt 11 when in use. In Figs. 2 and 7, that direction of movement is indicated by the arrow 18.

The shaped ends 12 A, 12B ofthe abrasive member 10 may be produced by a die cutting operation and need not have the particular form shown in Fig. 2. Any regular, or irregular, convoluted shape (including straight-sided shapes) could be used to provide the ends ofthe abrasive member 10 with projections and recesses which fit together.

It has been found that the interlocking ends 12 A, 12B on the abrasive member 10 reduce any risk ofthe abrasive member coming away from the backing belt 11 during use. In some cases, however, depending on the nature ofthe abrasive member 10 and the attachment system between the abrasive member and the backing belt 11 it may be possible to omit the interlocking shaping ofthe ends 12A, 12B. It will be appreciated that, when abrasive member 10 as shown in Fig. 1 is used to provide the abrasive surface of a belt in an abrading machine, the associated backing belt 11 can remain in position in the machine as shown in Fig. 3. The abrasive member 10 can easily be removed from the backing belt 11 and replaced when necessary (for example, because the abrasive surface is worn or because a different grade of abrasive is required). Because the backing belt 11 can remain in position, it need not be as easy to handle as a conventional abrasive belt and can, therefore, be formed from a much heavier duty material or even from a material which might be unsuitable as a backing for a coated abrasive. For example, the backing belt 1 1 could be formed from an elasticized material to enable it to be comparatively easy to place in position around the rollers 14 in the abrading machine while ensuring that, once in position, it will fit tightly around the rollers. As illustrated in Fig. 7, the abrasive member 10 can be narrower than the backing belt 11, thereby enabling substantial savings to be achieved in the case in which, when using a conventional abrasive belt, the whole width ofthe belt would not be required.

Alternatively, two or more parallel abrasive members (which need not be of the same grade) can be located on the same backing belt. In that case, adjacent side edges ofthe abrasive members could be shaped so that they interlock, in a similar manner to the ends 12 A, 12B. The abrasive member 10 may be any suitable material presenting an abrasive surface. It may, for example, be a coated abrasive comprising a substrate (for example paper, polymeric film, sponge material, cloth), which may be in sheet form and which has abrasive grit particles bonded to it. Alternatively, it may be a non- woven abrasive comprising a substrate (which may be in sheet form) of a porous, fibrous, non-woven construction, with abrasive grit particles on one side ofthe substrate. The first part ofthe mating surface attachment system, e.g. the loop backing 16, is laminated to the back ofthe coated abrasive. Alternatively, the abrasive may be coated directly onto the first part ofthe attachment system 16 which thus forms the substrate ofthe abrasive sheet material. Generally, the abrasive member 10 may be a less costly type of abrasive than those generally employed for abrasive belts since it .does not have to withstand the same tensile forces.

Likewise, the second part ofthe mating surface attachment system, e.g. the hooked surface 17 on the backing belt 11, may be laminated to the belt, or may form an integral part ofthe belt. In a particular case, the belt 11 may actually be formed from the hooked material that provides the hooked part ofthe attachment system.

The use of a hook and loop type of attachment system to secure the abrasive member 10 to the backing belt 11 is not essential. Any other suitable means can be used to secure the abrasive member 10, provided that it permits the abrasive member to be removed and replaced without damage either to the abrasive member or to the backing belt 11 while ensuring that the abrasive member remains firmly attached while the belt is in use. For example, a suitable repositionable adhesive could be used to secure the abrasive member 10 to the backing belt 1 1, the adhesive preferably being carried by the abrasive member. In that case, the abrasive member

10 may be provided with a backing sheet which protects the adhesive and is removed before the abrasive member is secured to the backing belt 11.

When a hook and loop type of attachment system is used, suitable loop fabrics 16 include looped stitched materials generally; brushed nylon, materials available under the trade name "Kanebo"; and materials available under the trade name "Velcro."

Another suitable loop material is one which can be made by stitching loops into a substrate with commercially available chenille stitch machines. The substrate can be any suitable substrate to which a strand may be stitched to form a plurality of loops. The substrate should be chosen to allow the needle to penetrate the substrate when forming loops, to provide adequate support for the loops, to provide an adequate bond with an adhesive layer described in more detail below, and to avoid picking and snagging by the needle when the forming loops. Preferred materials for the substrate include woven fabrics such as polyester, fortrel polyester gabardine, 65/35 polyester/cotton blend poplin, rip stop nylon, cotton canvas, polyester double knit, 50/50 cotton/polyester blend, cotton twill, and woven cellulosic fabric, such as cotton or rayon, in a 2 over 1 twill weave having a weight of 165 grams/meter ² .

In general, the loops are formed by repeatedly piercing the substrate and causing portions ofthe strand to extend through the substrate with a suitable needle, thereby forming a plurality of loops formed from a continuous strand. This type of stitch is generally referred to as a drop stitch or a moss stitch. The result is a series of free standing loops made from a single continuous strand. The loops are generally oriented in the direction defined from hole to hole of adjacent loops. Often, sewing and embroidery operations employ a second strand in a bobbin below the substrate which locks each individual stitch. However, the chenille stitch method described above does not lock each loop. Accordingly, the loops are connected to one another, but are not tied or locked in place. If one loop is pulled up through the substrate, it will pull the strand from adjacent loops. It is therefore necessary to lock all ofthe loops in place. This is preferably done by adding adhesive layer to the back surface ofthe substrate after forming the loops. The adhesive should provide a strong

enough bond to lock the stitches and prevent pull out of loops during operation ofthe abrading machine and during removal and replacement ofthe abrasive member. Suitable types of adhesives include, but are not limited to, polyolefins, polyesters, polyurethanes, polyamides, phenolic adhesives, urea-formaldehyde adhesives, epoxy adhesives, acrylate adhesives, and the like.

With commercially available chenille machines, the substrate can be moved in any direction after each stitch. Thus, the loops can be made to have an orientation in any direction. This provides the ability to closely control the orientation ofthe loops and to stitch a loop material in which the loops are oriented in the same direction or in different directions relative to one another by a desired amount.

Suitable hooked materials 17 are also available under the trade names "Kanebo" and "Velcro." Other suitable hook materials include those described in U.S. Patent No. 5,505,747 (Chesley et al ); U.S. Patent No. 5,077,870 (Melbye et al.); and in WIPO International Publication No. WO 95/19242. It will be appreciated that it is not essential for the loop fabric 16 to be carried by (or form part of) the abrasive member 10: the loop fabric 16 could instead be carried by (or form part ofthe belt 11 with the hooked material 17 being carried by (or forming part of) the abrasive member 10.

Preferably the abrasive member 10 is attached to the backing belt 11 over the whole of its rear surface.

As already mentioned, the abrading machine referred to with respect to Fig. 1; is an example of one of many different types of machines which use abrasive belts. Use of an abrasive member as shown in Fig. 2 in combination with a backing belt is, accordingly, not restricted to a machine ofthe type referred to with respect to Fig. 1 : a similar combination could be used in any machine employing an abrasive belt. Alternatively, an abrasive member having the form shown in Fig. 2 could be releasably attached to a rotatable drum (for example, in a drum sander) instead of an endless rotatable belt. Similar attachment systems can be used to those described above and, in the case of a two-part attachment system, one part would be provided on the surface ofthe drum.