A two sided abrasive disc with intermediate member

Abstract: A finishing article comprising a backing member defining a central opening and having two opposed surfaces each carrying an abrasive material thereon; an intermediate member, having a central bore therethrough, being positioned in the opening and attached to the backing member, the central bore is capable of being at least partially threaded for supporting the finishing article to a support member. The partially threaded bore of the finishing article is detachably connectable to a threaded portion of a support member to provide rotational movement from the support member to the finishing article for finishing an object wherein the partially threaded portion of the central bore lies substantially in the plane of the backing member so that both abrasive surfaces of the finishing article can be used for abrasive sanding and, if desired, the abrasive surfaces of the article can carry different grades of abrasives.

Description: The field of art to which the present invention pertains is the field of surface finishing and more particularly with respect to a two-sided finishing article which is capable of being detachably supported by a drive member, such as a shank or the like. A variety of prior art finishing devices have been developed for the finishing of objects, for instance those disclosed in U.S. Patent Numbers 3,667,169, 3,667,170, 4,258,509, 3,491,494, 3,747,186 and 3,866,361. Each of the above mentioned prior art references teach a variation of a finishing device which has only one surface capable of finishing an article while the opposite surface of the device is used primarily for accommodating some form of support member, such as a male coupling, a hub, a backing pad, etc., extending from that surface to provide means for connecting the finishing device to a drive member. One of the drawbacks associated with prior art finishing devices is that a surface which is capable of supporting an abrasive material for finishing is totally ignored in favor of a supporting member for supporting the finishing member to the drive member. The closest prior art is believed to be U.S. Patent No. 3,844,072 which relates to a pad assembly for supporting a replaceable paper disc. Although this citation indicates that the two opposed surfaces of the pad assembly may be used for finishing a surface when a replaceable paper disc is temporarily affixed to one surface thereof, this citations has associated drawbacks in that it is a multi-part system which is cumbersome and is relatively expensive to manufacture and use. The flexible, non-vitrified double-sided sanding disc according to the present invention is relatively inexpensive to manufacture, readily follows the contour of the surface being finished, and is simple and easy to use, thereby overcoming the many of the drawbacks associated with this prior art pad assembly system. A further object is to provide a surface finishing article which is easily connectable and disconnectable to a drive member. The present invention relates to a disposable, flexible, non-vitrified double-sided sanding disc for rotatable engagement with a support member having engaging means on one end thereof, said sanding disc having a circular backing means defining a central opening and having two opposed substantially circular planar surfaces; and at least a portion of said central opening lying substantially between said two planar surfaces having means engagable with engaging means on one end of a support member for supporting said sanding disc and transmitting rotational movement from said support member to said sanding disc; said sanding disc having abrasive material permanently affixed directly to and only on both said circular planar surfaces prior to use whereby said sanding disc can be detachably connected to said support member by said backing means so that both abrasive surfaces can be used for finishing an article. Preferably, said means engagable with the engaging means on one end of a support member comprises an intermediate member, defining a central bore, positioned in said central opening and attached to said backing means, said central bore and said central opening being coaxial with one another, and said central bore supporting said means engagable with the engaging means on one end of the support member. Alternatively, said backing means is an intermediate member in the form of a disc having two opposed substantially planar disc carrying surfaces. The invention may be better understood by reference to the annexed drawings which illustrate preferred embodiments of the invention, given by way of example, it being understood that other embodiments employing the same principles may be made as will become readily apparent to those skilled in the art, wherein: Figure 1 is a front elevational view of a finishing article in accordance with a first embodiment of the present invention; Figure 2 is a cross-sectional view of the finishing article of Figure 1 along line A-A; Figure 3 is a cross-sectional view, similar to the view shown in Figure 2, of a second embodiment of the invention; Figure 4 is a cross-sectional view, similar to the view shown in Figure 2, of a third embodiment of the invention; Figure 5 is a front-elevational view of a support member used to carry the finishing article of the present invention; and Figure 6 is a front-elevational view of a second embodiment of a support member used to carry the finishing article of the present invention. Turning first to Figures 1 and 3, the preferred embodiment of the flexible sanding disc or finishing article 1 of the present invention is shown to comprise a intermediate member 4, such as a disc, a washer or other similar flat planar member, having two opposed substantially parallel disc carrying surfaces 5, 6 with a central bore 8 therethrough. A first disc member 2 having an abrasive material 10 of a desired grit size carried on one side thereof while a second, opposite side of the disc is attached to the disc carrying surface 5 by any conventional adhesive well known in this art. A second disc member 3 having an abrasive material 10 of a desired grit size carried on one side thereof is attached by its second, opposite side adhesively to the other disc carrying surface 6 of the intermediate member 4, to form a finishing article having two abrasive surfaces available for sanding an object. Both disc members 2, 3 have a central opening 9, preferably of a diameter between 0.794 and 2.223 cm (5/16 and 7/8 inches), in the center thereof. This opening is large enough to allow threaded portion 16 (see Figures 5 and 6), on one end of a spindle 15, to pass therethrough with ample clearance. The disc members 2, 3 preferably have diameters between 1.905 and 22.86 cm (0.75 and 9 inches). The intermediate member 4 is preferably made of a high strength synthetic or plastic such as polyvinyl sheeting, vulcanized fibre, nylon, polyester or polypropylene, a metal such as aluminum, steel, brass, copper, etc., or other similar materials which are capable of securely attaching the article by at least a partial threaded engagement with a threaded drive member. It is important that the material chosen for the intermediate member be of sufficient strength to support adequately the finishing article 1 when subjected to grinding and sanding forces. The over-all dimensions (diameter, thickness, type of material, degree of taper, etc.) of the intermediate member 4 are chosen to provide the desired degree of stiffness or flexibility for a given grinding situation. The partially threaded portion 33 of the central bore engages a mating threaded portion (the engaging means) 16 of the support member 14 to support the finishing article 1 during a sanding operation. The partially threaded portion 33 and the thread portion 16 mate with one another and are preferably threads having a size between 0.635 cm (1/4 inch) diameter 20 threads per 2.54 cm (inch) and 1.588 cm (5/8 inch) diameter 11 threads per 2.54 cm (inch). The intermediate member 4 should provide sufficient disc carrying surface area to allow secure adhesive attachment thereto of the opposite surfaces of the first and second disc members 2,3. The disc carrying surfaces 5,6 of the intermediate member 4 are substantially parallel to one another and preferably taper slightly toward one another near the outer periphery of the intermediate member, as can be seen in Figures 2 and 3. In Figure 3, the opposed sides of the disc 2, 3 are attached to each other near the outer periphery. In Figure 4, the finishing member 1 comprises a backing member or means 40, defining a central opening 9, having two opposed substantially planar surfaces 41, 42 each carrying an abrasive material 10 thereon. Alternatively, two disc members 2, 3 aligned with their rear surfaces adhesively attached to one another by a conventional adhesive, similar to those discussed with respect to Figures 1-3, could be used. An intermediate member 25, such as a rivet, a grommet or the like, is positioned in the central opening 9 of the backing member 40 or the two disc members 2, 3. The member 25 has a central bore 8 capable of being at least partially threaded for supporting the finishing article 1 to the support member 14. The member 25 has two exterior flange portions 26, positioned on opposite ends of the bore 8, which compressibly clamp the outer edges of the central opening 9 of the backing member 40 or the disc members 2, 3 so that the member 25 is capable of transmitting rotational movement from the drive member to the member 40 or 2, 3. Turning now to Figure 5, support member 14 comprises a spindle or mandrel 15 having a threaded portion 16 at one end thereof. The opposite end of the spindle 15 is adapted to be engagable with a suitable drive member (not shown), such as a drill. The support member 14 further includes a reinforcing member 17, commonly used in this art, having a central bore 28 therethrough. The reinforcing member 17 is made from rubber or other similar materials for adequately supporting one surface of the finishing article 1 when used in a grinding operation. A locking member 20, such as two nuts, is provided on the threaded end 16 of spindle 15, behind the reinforcing member 17, and the locking member 20 engages the rear surface of the reinforcing member 17 to lockably adjust the length of threaded portion 16 extending out through the central bore 28 of the reinforcing member 17. This length is adjusted so that when the finishing article 1 is threaded onto the support member 14, the end surface 30 of the threaded portion 16 will be flush with, or slightly recessed inside, the outer abrasive surface of the attached finishing member so as not to interfere with the grinding operation. An alternate arrangement of the support member is shown in Figure 6 in which the reinforcing member 17 is omitted. This embodiment is only feasible if the finishing article is sufficiently stiff to adequately support itself, via the intermediate member, during a finishing operation or if a greater flexibility in the finishing article 1 is desire. If the intermediate member 4 is not rigid enough, or if extra rigidity of the finishing article 1 is required for a particular sanding situation, then the arrangement shown in Figure 5 is utilized. A further advantage of the present invention is that the first and second disc members 2,3 can contain different grades of abrasive materials on their respective sides, such as course/medium, medium/fine, fine/extra fine, etc., so that a single finishing article can vary the degree of finishing achieved in a particular situation by simply flipping the finishing article over and using the opposite side. The term "partially threaded" engagement, as used in this application, is intended to include other known arrangements apparent to those skilled in the art for engaging a drive member to a driven member such as projections, engaging slots, annular vanes, etc. In addition, the engagable portion (for instance the threads) of the central bore can be formed therein either by the initial engagement with the engaging means of the support member or it can be formed prior to the initial engagement, such as during manufacturing of the finishing article. Thus, the finishing article as provided herein is economical to manufacture, durable and provides two separate and opposed surfaces for abrasive sanding.

Claims: A disposable,flexible, non-vitrified double-sided sanding disc (1) for rotatable engagement with a support member (15) having engaging means (16) on one end thereof, said sanding disc having a circular backing means (4, 40) defining a central opening (9) and having two opposed substantially circular planar surfaces; and at least a portion of said central opening lying substantially between said two planar surfaces having means (33) engagable with engaging means (16) on one end of a support member (15) for supporting said sanding disc (1) and transmitting rotational movement from said support member (15) to said sanding disc (1); said sanding disc (1) having abrasive material (10) permanently affixed directly to and only on both said circular planar surfaces prior to use whereby said sanding disc can be detachably connected to said support member by said backing means (4, 40) so that both abrasive surfaces can be used for finishing an article. A sanding disc (1) according to claim 1, characterized by one of the following features (a) or (b): a) said means (33) engageable with the engaging means (16) on one end of a support member (15) comprises an intermediate member (25), defining a central bore (8), positioned in said central opening and attached to said backing means (4, 40), said central bore (8) and said central opening (9) being coaxial with one another, and said central bore (8) being engageable with the engaging means (16) on one end of the support member (15); or b) said backing means (4, 40) is an intermediate member in the form of a disc (4) having two opposed substantially planar disc carrying surfaces (5, 6). A sanding disc according to claim 1 or 2, characterized by any one or more of the following features (a), (b) and (c): a) said sanding disc (1) comprises a first disc member (2) having an abrasive material (10) on one side thereof, and a second disc member (3) having an abrasive material (10) on one side thereof; (b) the opposite side of the second disc member is at least partially adhesively attached to the opposite side of said first disc member; c) said backing means (4, 40) has a circular shape with a diameter from 1.905 to 22.86 cm (0.75 to 9 inches). A sanding disc according to claims 2 or 3, characterized by any one or more of the following features (a) to (f): a) said intermediate member is a rivet means (25) having two flange portions which compressibly clamp both outer edges of the central opening to attach securely the rivot means (25) to said backing means; b) the opposite sides of said first and second disc members (2, 3) are each at least partially attached to one of said disc carrying surfaces; c) said intermediate member (4) is made from one of a plastic, metal and synthetic material and chosen to provide a desired stiffness for said finishing article; d) said intermediate member (4) has a diameter approximately equal to the diameter of said disc members (2, 3); e) said intermediate member (4) has a diameter less than the diameter of said disc members (2, 3); f) the opposite sides of said first and second disc members (2, 3) are each attached to one of the circular planar surfaces of said backing means (4, 40). A sanding disc according to claim 1 or 2, characterized in that said means (33) engageable with the engaging means (16) on one end of a support member (15) is an internal thread sized to threadingly engage one end of a support member (15). A sanding disc according to any one of claims 2, 3 or 4, characterized in that said central opening (9) or said central bore (8) of said intermediate member (4) is at least partially threaded, prior to engaging the support member, with an internal thread size from 0.635 cm (1/4 inch) diameter 20 threads per 2.54 cm (inch) to 1.588 cm (5/8 inch) diameter 11 threads per 2.54 cm (inch). A sanding disc according to any one of the preceding claims in combination with a support member characterized in that said support member comprises a spindle (15) having engaging means (16) at one end thereof and the opposite end thereof is engagable with a drive member for providing rotational movement to said support member (15) and said sanding disc (1) supported thereby; a reinforcing member (17), defining a central bore (28), being supported by the engaging means (16) of said spindle (15) via central bore (28); and locking means (20) engaging said engaging means (16), adjacent said reinforcing member (17) on a side thereof facing the opposite end of the spindle (15), for adjusting the length of said engaging means (16) extending out through said central bore (28) of the reinforcing member (17) available for engagement with said sanding disc (1). A sanding disc according to any one of the preceding claims in combination with a support member characterized in that said support member comprises a spindle (15) having engaging means (16) at one end thereof and the opposite end thereof being engagable with a drive member for providing rotational movement to said support member (15) and said sanding disc (1) supported thereby; and locking means (20) engaging said engaging means (16), for adjusting the length of said engaging means (16) available for engagement with said sanding disc (1).

Inventors: JOHNSON COURTLAND M, JOHNSON, COURTLAND M.
Applicants: JOHNSON COURTLAND M, JOHNSON CYNTHIA L B, JOHNSON, COURTLAND M., JOHNSON, CYNTHIA L. B.
Application year: 1990
Main classification: B24D13
IPC codes: B24D7, B24D13