Sanding rope and applications thereof

A disposable sanding device is fabricated as a continuous rope-like article which is adapted for selective segmentation and application as a plurality of serially arranged disposable hand sanding devices or ropes. Each hand sanding device is formed as a generally elongated rod shaped base portion formed of lightweight material such as closed cell foam having a relatively constant cross-section along its line of elongation. An abrasive surface is permanently applied to the external surface of the base portion via an intermediate adhesive layer. As constructed, the sanding device is operable to conform to curvilinear contours of a work piece to be sanded upon application of user induced loading against the work piece. A dispenser holds a rolled length of sanding rope and includes a cutter feature for severing pieces of sanding rope from the coil as required as well as a retainer for the free end of the coil. A tensioning hand tool holds a severed length of sanding rope for precise applications. Interconnection means is provided to concentrically position and affix opposed ends of a base portion segment.

The present invention relates generally to hand tools and particularly to sanding devices, especially for use in wood working. More particularly still, the present invention relates to a low cost, hand-held disposable sanding device which can be easily manipulated by hand for sanding and finishing a wide variety of work piece surface shapes and configurations.

BACKGROUND OF THE INVENTION

Small sanding jobs and sanding jobs calling for considerable detail work or access to small confined areas will usually require the direct hand application of sandpaper of one or more suitable grit sizes. The difficulty in hand-sanding is in applying firm pressure long enough to complete the job and in applying even pressure to obtain a desired smooth and even finish. A further difficulty is to obtain efficient use of the sandpaper by not wasting any substantial portion of its surface area.

Common sanding jobs calling for considerable detail work or access to small confined areas, or for the sanding of contoured surfaces, will often require that the surfaces be hand sanded. Therefore, hand-held sanding devices devised for this purpose consist essentially of a sanding block for holding conventional sandpaper wrapped over the block. By using a sanding block as a sandpaper holder, hand-applied sanding forces on the sandpaper can be increased and more evenly distributed. One such device is disclosed in U.S. Pat. No. 4,501,096 to Lukianoff, wherein a generally triangularly shaped sandpaper holding device provides three different sanding surfaces and corners for accommodating a variety of sanding conditions. The sandpaper wrapped around the faces of this device is held at its ends by means of an angled slot located in one of its faces.

The difficulty with the above-mentioned prior sanding devices is the necessity of installing or wrapping a separate piece of sandpaper around the device. This installation or wrapping process presents some inconvenience to the user, and the paper, if improperly installed, is susceptible to falling off. Also, the device requires the purchase of separate sheets of sandpaper which is a further inconvenience in terms of the amount of supplies needed.

Sanding blocks are presently available in a variety of forms in an attempt to meet the needs of those who must sand various surfaces. Perhaps the most common sandpaper support is a block of wood from which one may move through myriad supports and into complex electric sanders. In virtually all of these items, the general purpose of the sanding block is three fold.

First, it allows the user to apply greater pressure to the area being sanded. Secondly, it moves the user's hand away from the work surface, usually by providing a handle for the user to grasp, in order to reduce the likelihood of injuries. Thirdly, when a sanding block having a flat sanding paper supporting surface is used to sand a flat surface, the block reduces points of excessive pressure by more evenly distributing the user's force over the sandpaper supporting surface. However, when non-flat surfaces need to be sanded, difficulties often arise. The standard sanding block has a relatively large, flat sandpaper supporting surface which does not satisfactorily meet the needs of one who is sanding an irregular surface. The use of such a sanding block on an irregular surface will generally result in the user angling the block or using it in a way in which it was not intended in an attempt to conform the sanding surface to the work surface. Even with such attempts, the resultant effect is uneven sanding as generally no portion of the block will conform exactly to the area being sanded and excessive areas of pressure which will result in over sanding.

Excessive pressure points can also result in the quickened wearing of the sandpaper, such that the sanding block itself may become exposed, which, depending upon the fabrication of the sanding block, may damage the work surface. Similarly, as the user angles the sanding block in order to utilize a corner or edge of the sandpaper, a portion of the block not covered by the sandpaper may scratch the work surface.

In an attempt to provide sanding blocks which are usable on irregular surfaces, a wide variety of devices have been developed. For example, U.S. Pat. No. 3,557,496 to R. W. Martin discloses a metal strap to which a piece of sandpaper may be secured. The strap is then placed over a pipe or other circular type object so that a back and forth motion may be applied to sand the item. A circular piece of sandpaper is also secured over the handles which are particularly adapted for sanding the inner edges of the pipes. Other patents disclose devices such as special sandpaper holders for louver doors, U.S. Pat. No. 3,640,031 to Descant; sanding fittings, U.S. Pat. No. 3,722,150 to Pass; abrading corners and crevices as shown in U.S. Pat. No. 2,465,569 issued to Bates. While such devices may be suitable for their intended uses, they do not sufficiently meet the myriad surface irregularities often encountered when sanding a complex work piece.

Thus, an individual faced with the task of sanding a variety of irregular surfaces, must either attempt to use different types of sanding blocks, many of which still will not conform to the actual intended use, or in the alternative, those experienced in this area will use their hand in order to conform and support the sandpaper to the work piece. Attempting to enhance this latter approach are devices which either secure the sandpaper directly to the users hand or to a specialized glove.

It should be easily appreciated that these later approaches, while at times effective, are not reasonable alternatives when extreme precision or small detailed contours, such as in furniture finishing, are involved.

The present invention overcomes the forgoing difficulties of hand-held sanding devices by providing a hand-sized sanding device which eliminates the need for a separate sheet of sandpaper. A sanding device is particularly provided which has its own integral abrasive surfaces and which can be manufactured at a sufficiently low cost to be disposable. The invention further provides a self-contained sanding device that can be conveniently used off-the-shelf to hand sand a variety of standard, contoured or shaped surfaces, such as trim or molding surfaces, and for projecting into restricted exactly defined areas.

BRIEF DESCRIPTION OF THE INVENTION

An object of the present invention is to develop a low cost (and thus disposable) hand held sanding device made of lightweight, resilient material capable of recovering its shape after being subjected to radial or axial pressures attendant its usage as a sanding device. The device has a contoured outer surface which can be deformed to match the small, intricate shapes of furniture balusters, moldings and trim. While shaped molding and trim are specifically identified as possible contoured shapes to which the sanding device of the invention can be applied, it shall be understood that the contoured surface of the device can be applied with almost any sandable surface and material.

According to the present invention, a disposable hand sanding device includes an elongated, generally rod shaped base portion which is constructed of lightweight resilient material such as closed cell foam or rubber and is formed with a substantially constant cross-section along its characteristic line of elongation. An abrasive outer surface layer is permanently formed on the base portion by adhering abrasive material such as silicon carbide or aluminum oxide upon an intermediate adhesive layer. This arrangement results in a hand held device which, in application, conforms to curvilinear contours of a work piece to be sanded upon application of user induced loading against the workpiece. The device is light weight, easy to use and is extremely inexpensive to manufacture.

As an additional feature, an elongated, non-resilient flexible cord is embedded within the base portion and extends substantially concentrically with the base portion to limit axial distension of the sanding device upon application of user induced loading. The cord, when exposed, also facilitates manual manipulation of the sanding device.

In the preferred embodiment of the invention, a continuously formed rope-like article is provided which can be selectively cut to length for a specific sanding application. The rope-like article is maintained in a roll. Segments removed from the roll are used and then discarded. This arrangement has the advantage of continuously forming multiple “sanding ropes” in series or a succession such as by extrusion. An artisan can easily maintain the unused roll portion and sever just the length segment required for a specific sanding application.

A dispenser can also be provided which maintains the continuously formed rope-like article in a rotating spool mounted on a frame member which includes a cutter and a loose end holder. This arrangement provides an extremely convenient package which facilitates removal of a length of sanding rope material from the storage roll without the necessity of using additional tools, such as a cutting device.

An additional feature includes witness marks located on the outer surface of the rope-like material which are axially spaced from one another to serve as an indicator or measurement to the artisan in selecting an appropriate amount of length of material to sever. Furthermore, localized weakened areas such as perforations are provided to assist in the stripping off of a short length of base portion to expose an under laying length of inner cord to aid in the manipulation of the severed piece.

A severed length of sanding rope with its internal cord exposed at each end thereof can be employed with a hand held tool, similar to a key hole saw frame, which provides precisely controlled tensioning of the cord in application to a work piece.

These and other features and advantages of this invention will become apparent upon reading the following specification which, along with the drawings, describes and discloses preferred and alternative embodiments of the invention in detail.

DETAILED DESCRIPTION

FIG. 1illustrates a preferred embodiment of the present invention. A disposable sanding rope or device10is formed as a generally rod shaped base portion12elongated along an axis designated A—A. Base portion12is preferably formed from lightweight resilient material such as closed cell foam or rubber. It is contemplated that many other suitable materials such as urethane or neoprene could be substituted, however, based upon an understanding of the present invention and a given specific application.

The outer circumferential surface of base portion12is substantially covered with an abrasive coating layer11suitably affixed to the underlying base portion12by an intermediate adhesive layer16. Adhesive layer16is spray applied to base portion12prior to application of a suitable aggregate abrasive14such as coarse aluminum oxide or silicon carbide. Such materials are commercially available from the Household and Hardware Products Division of the 3M Company under a number of product names. One type of spray adhesive that can be used is “Spray Mount” No. 6065 produced by 3M Adhesives Division of the 3M Company. This construction allows momentary resilient deformation of the sanding rope10as it engages a work piece. Upon completion of the sanding process, the sanding rope returns to its illustrated shape. Alternatively, abrasive layer14could be formed of traditional sand paper which is, in turn, adhered to base portion12by adhesive layer16.

A reinforcing cord18, formed of woven fibrous material such as cotton or nylon, extends along axis A—A within base portion12of sanding rope10. Cord18is flexible in the radial direction and inflexible in the axial direction and thus serves to limit axial distension of sanding rope10when applied against a work piece. Furthermore, cord18also extends axially beyond the longitudinal ends20and22of base portion12to define grip handles24and26.

Sanding rope10is intended for hand sanding complex curvilinear surfaces of work pieces such as wooden furniture or moldings. Rope10is employed by either grasping the abrasive layer by the user's finger tips or palm of the hand and applying force against a work piece. In this manner the tactile sense of the operator's hand allows continuous variation in force applied against the work piece and thus the rate and configuration of sanding. This is useful for non-symmetrical or custom surface features.

Alternately, for work piece surfaces which are regular or symmetrical in at least one plane, grip handles24and26can be held by the fingertips of the user's respective right and left hands. Insodoing, the user tensions cord18along axis A—A. The user then positions the abrasive surface14of rope10against a specific feature of the work piece to be sanded and alternatively pulls grip handles24and26along axis A—A. This action will largely conform the local circumferential shape of the sanding rope10to the adjacent contour features of the work piece. As grip handles24and26are alternatively pulled in one direction and then another along axis A—A, the portion of abrasive layer14of sanding rope10contacting the work piece reshapes its surface. The amount of tension applied along the cord18will control the degree in which the abrasive layer will conform to the work piece. For example, if very little tension is applied to cord18, the sanding rope10will tend to increase its “wrap” or engagement with convex surface features of the work piece. Conversely, if the cord18is placed under high tension, sanding rope10will tend to decrease its “wrap” around convex surfaces. Accordingly, an amount of user experience and test sanding of material similar to that contained in an intended work piece will facilitate skilled use of the present invention.

Referring toFIG. 2, sanding rope10is illustrated in application with a work piece28. The work piece28is of relatively simple geometric form for purposes of illustration only, it being contemplated that the present invention is best applied with extremely irregular contoured surfaces. The work piece28is configured as a generally rectangular block of wood having an upper surface30with a generally rounded configuration. Sanding rope10is applied by draping it over upper surface30with cord18extending generally from left to right. Grip handles24and26are alternatively pulled leftwardly, as illustrated by arrow32, and then rightwardly, as illustrated by arrow34. As described hereinabove, the user will maintain continuous tension in cord16throughout this process.

Referring toFIGS. 2 and 3A, sanding rope10is being employed to form a generally saddle or crescent shaped groove36in upper surface30of work piece28. When subjected to very low tension forces in the direction of arrows32and34, the base portion12of sanding rope10substantially maintains its nominal circular configuration. As such, only a small portion of the abrasive layer14adjacent the intersection of the uppermost portion of groove36and upper surface30conforms to the adjacent portion of the groove36at regions designated38and40. Therefore, axial manipulation of sanding rope10will result in removal of material at regions38and40.

Referring toFIGS. 2 and 3B, sanding rope10is illustrated as being subjected to intermediate tension forces in the direction of arrows32and34. As a result, sanding rope is displaced further within groove36and conforms thereto at adjacent regions designated42and44. Again, axial manipulation of sanding rope10will result in removal of material at regions42and44.

Referring toFIGS. 2 and 3C, sanding rope10is illustrated as being subjected to relatively high tension forces in the direction of arrows32and33. As a result, sanding rope10is displaced into the bottom of groove36and conforms thereto at a single adjacent region45. Axial manipulation of sanding rope10will result in removal of material at region45.

The various positionings of sanding rope10inFIGS. 3A,3B and3C serve to illustrate how an artisan using sanding rope10can skillfully and precisely remove material from a complex recess in a work piece by varying the tension applied to the cord18of sanding rope10. Varying the positioning of the sanding rope10vis-á-vis the groove36causes momentary localized deformation of the base portion12and the abrasive coating layer14as well as the intermediate adhesive layer16. Upon removal of the sanding rope10from engagement with the work piece28, the overall shape of the sanding rope10will return to the generally cylindrical configuration illustrated inFIG. 1.

Referring toFIG. 4, an alternative application of the sanding rope10described in connection withFIG. 1is illustrated. Sanding rope10is illustrated inFIG. 4in application with a work piece46. As in the case of work piece28described in connection withFIG. 2, work piece46is of relatively simple geometric form for purposes of illustration only, it being contemplated that the present invention is best applied with extremely irregular contoured surfaces. The work piece46is configured as a generally rectangular block of wood having an upper surface48with a generally concave feature50formed therein. Sanding rope10is applied to work piece46by conforming it generally to the contours of concave feature50on upper surface48of work piece46. Sanding rope is maintained in its illustrated position by the artisan applying pressure, as indicated by arrow52, from one or more finger tips54. While holding sanding rope10in position, the artisan would apply his other hand to grasp either of the grip handles24or26and apply tension to cord18, as illustrated by arrows56′ and58, respectively. Increasing or decreasing pressure (arrow52) will deform the base portion12of sanding rope10and thus increase or decrease the amount of abrasive layer that is bearing against the adjacent area60of concave feature50. This will result in precisely controlled removal of material at region60in response to axial manipulation of sanding rope10.

Referring toFIGS. 5 and 5A, to facilitate economical large scale production of sanding rope10such as illustrated inFIG. 1, it would be formed in an endless or continuous stream62emerging from appropriate manufacturing equipment64, such as an extruder, along an axis B—B. The continuous stream62of sanding rope preferably has a typical cross section configuration substantially identical to that described with respect to the sanding rope10segment ofFIG. 1. The continuous stream62comprises successive segments of sanding rope66joined end-to-end along axis B—B.

The continuous stream62structure consists of concentrically arranged cord68, base portion70, adhesive layer72and abrasive coating layer74. Witness marks76are imprinted on the outer surface of abrasive coating layer74at axially spaced locations there along. Weakened areas78such as perforations are formed at axially spaced locations as well. The witness marks are indicators of suggested locations for severing one specific sanding rope segment66from an immediately adjacent segment66. The applicant has discovered that spacing (designated “L”) between successive witness marks of eight (8″) to twelve (12″) inches results in sanding rope segments66of convenient length for many craft and hobby applications.

Perforations78are provided at a location spaced from each end of each sanding rope segment66. The perforations extend inwardly through abrasive coating layer74, adhesive layer72and substantially all of base portion70. The cord68is not weakened, however. The portions of the abrasive layer74, adhesive layer72and base portion70intermediate the (severed) witness marks76and a related perforation78are optionally removable to expose a segment of the underlying cord68. The applicant has discovered that the exposed cord68portion, i.e. the spacing (designated “D”) between each witness mark76and its associated perforations78of one (1″) to two (2″) inches results in a convenient length of exposed cord68for finger grasping by the artisan in application of a given sanding rope segment66without undue waste of material.

When constructed in a continuous stream62, the sanding rope segments66of the present invention can be easily packaged and marketed in bulk or rolls. Referring toFIG. 6, an example roll dispenser80for retail sales of a substantial length (such as 10′ to 25′) is illustrated. A spool82dimensioned to receive and hold an extended length of sanding rope84(shown in phantom) is mounted for rotation on an axle86extending concentrically through the hub88of spool82. The lower end of axle86is affixed to a stop member90which functions to prevent relative upward displacement of the axle86with respect to hub88but allow free relative rotation between the two. Axle86extends upwardly above spool88and through a frame member92, terminating in a second stop member94. Stop member94is affixed to both the uppermost end of axle86and frame member92, and prevents relative downward displacement of the axle86with respect to hub88. Thus, frame92, axle86, and stop members90and94comprise one rigid, fixed assembly. Spool82(and any sanding rope84carried thereon) is free to rotate about axle86but is restrained from relative axial displacement with respect to the remainder of roll dispenser80.

Frame member92of roll dispenser80extends radially outwardly beyond spool82and terminates in a cutter/retainer portion96. Cutter/retainer portion96serves as an integrated tool for conveniently severing one or more sanding rope segments66(seeFIG. 5) as required. Subsequently, the free end111of the extended length of sanding rope84remaining on spool82is retained in its illustrated position to prevent inadvertent uncoiling of the extended length of sanding rope84remaining on the spool82. Cutter/retainer portion defines a generally “V” shaped cutter98defining converging sharpened edges100and102. A pocket104formed in the cutter98adjacent the point of closest approach of edges100and102is dimensioned to receive the cord68of a sanding rope segment66being severed from the remaining length of sanding rope84remaining on the spool82. Thickened guide walls106,108and110coact with cutting edges100,102and pocket101, respectively, to precisely guide the segment of sanding rope66being severed to ensure a clean perpendicular cut occurs. Cutter/retainer portion96also defines a necked opening112dimensioned to enable the user to press fit the free end111of the extended length of sanding rope84remaining on the spool82during storage.

Referring toFIG. 7, an alternative configuration of the sanding rope10described with reference toFIG. 1, is illustrated. A sanding rope114, illustrated in typical cross-section, comprises a base portion116formed in a generally square or rectangular configuration. The outer circumferential surface of base portion116is substantially covered by an abrasive coating layer118which is affixed to the base portion116by an intermediate adhesive layer120. A reinforcing cord122, formed of woven fibrous material extends axially through the base portion116. The sanding rope114provides multiple flat normally disposed surfaces and intermediate sharp corners suitable for certain sanding requirements.

Referring toFIG. 8, another alternative configuration of the sanding rope described with reference toFIG. 1, is illustrated. A sanding rope124, illustrated in typical cross-section, comprises a base portion126formed in a generally triangular configuration. The outer circumferential surface of base portion126is substantially covered by an abrasive coating layer128which is fixed to the base portion126by an intermediate adhesive layer130. A reinforcing cord132formed of woven fibrous material extends axially through the base portion126. The sanding rope126provides three acutely angled flat surfaces134,136and138intersected by intermediate corner edges140,142and144. Each surface134,136and138has a significantly different grit size or coarseness characteristic. Furthermore, each surface134,136and138carries unique visible or tactile indicia indicative of its relative degree of coarseness.

In the case of this embodiment of the invention, the indicia comprise single, dual and treble sets of axially extending brightly colored stripes146,148and150. Alternatively, numerical grit or coarseness ratings could be provided on each side surface134,136and138as an aid to the artisan.

Referring toFIG. 9, still another alternative embodiment configuration of the sanding rope described with reference toFIG. 1. is illustrated. A sanding rope152, illustrated in typical cross-section, comprises a base portion154formed in a generally hour glass configuration. The outer circumferential surface of base portion154is substantially covered by an abrasive coating layer156which is fixed to the base portion154by an intermediate adhesive layer158. A reinforcing cord160formed of woven fibrous material extends axially through the base portion154. The top surface162of sanding rope152has an axially extending concave recess164formed therein. Recess164has a characteristic relatively constant radius designated by arrow “R1”. Likewise, the bottom surface166of sanding rope152has an axially extending concave recess168formed therein. Recess168has a characteristic relatively constant radius designated by arrow “R2”. It is contemplated that R1and R2may be dimensionally the same or, alternatively, substantially varied. Side walls170and172of sanding rope152are illustrated as being substantially flat. However, they could be formed as concave, convex or otherwise curvilinear surfaces to suit any number of varied sanding jobs.

Referring toFIG. 10, a further alternative embodiment configuration of the sanding rope described with reference toFIG. 1, is illustrated. A sanding rope174. illustrated in typical cross-section. comprises a base portion176having an exterior surface which is continuously curvilinear in shape. The outer circumferential surface of base portion176is substantially covered by an abrasive coating layer178which is fixed to the base portion176by an intermediate adhesive layer180. Two reinforcing cords182and184formed of woven fibrous material extend axially through the base portion176. Cords182and184are parallel and fall upon an imaginary plane designated “P—P”. Sanding rope174is asymmetrical in overall shape to define convexly curved surfaces of varying radius. Specifically, the upper left hand portion of base portion176defines a region186of relatively small varying radius designated by arrow188. The upper right hand portion of base portion176defines a region190of intermediate varying radius designated by arrow192. The bottom portion of base portion176defines a region194of relatively large varying radius designated by arrow196. Cord182extends through the portion of base portion176adjacent region186and cord184extends through the portion of base portion176adjacent region190. Cords182and184provide enhanced control of sanding rope174when regions186and190, respectively, are being employed in a sanding operation.

When both cords182and184are subjected to tensioning by an artisan in application, sanding rope becomes relatively inflexible within plane P—P, thus proving another measure of control.

Referring toFIGS. 11 and 11A, a tensioning tool198suitable for use with the sanding rope10described in connection withFIG. 1, is illustrated. Tool198can be applied in circumstances where extremely precise control of sanding rope10is required to effect sanding of a workpiece with curvilinear features having section which is straight in at least one direction.

Tensioning tool198is similar in some cosmetic respects to a conventional key-hole saw. Tool198is formed from relatively stiff drawn steel wire that is square or round in cross-section. The wire is bent to form a handle portion200integrally formed with a generally “U” shaped bow frame202. Bow frame202consists of a base portion204and two legs206and208extending there from in cantilever fashion. Legs206and208extend downwardly, terminating in sanding rope clamping assemblies210and212, respectively.

Clamping assemblies210and212are substantially identical. Accordingly, the detailed structure of only one will be described herein for the sake of brevity. Clamp assembly212includes an annular ring214defining a through bore216. Through bore216of ring214registers with a similarly dimensioned and aligned through bore218formed in leg208near the free end thereof. Legs206and208are generally parallel and are spaced to receive the sanding rope10described in connection withFIG. 1. In application, grip handle or cord segment26of sanding rope10is threaded rightwardly through bores218and216, extending slightly there beyond. A set screw220which is threadably engaged within a bore222in ring214normal to and communicating with bore216, is then tightened to secure grip handle26in its illustrated position. The process is then repeated wherein grip handle24is secured to leg206via clamp assembly210. As a final step, the free ends of legs206and208are momentarily forcibly sprung towards one another. Set screw220is loosened and grip handles24and26are pulled in opposed directions (tensioned). Finally, set screw220is retightened. This arrangement results in bow portion202of tool198acting to maintain a predetermined level of tension in sanding rope10. Thereafter, sanding rope is employed in its intended manner by the artisan grasping and manipulating the tool198by its handle200.

Referring toFIG. 12, an extended length of a sanding device or sanding rope250has first and second opposed ends252and254, respectively, interconnected by a fastener256to form a continuous loop, shown generally at258. Except as denoted herein below, the sanding rope250is constructed substantially as described herein above with respect to the embodiments of the invention illustrated inFIGS. 1–5. In one embodiment, the fastener256releasably engages the ends252and254of sanding rope250, whereby loop258can be easily adjusted, reconfigured, repaired or replaced as required. As will become apparent herein below, fastener256also serves to precisely axially align ends252and254.

Loop258is dressed over two spaced pulleys260and262carried for rotation upon axles264and266, respectively, which, in turn, are carried by appropriate bearing assemblies and support structure (not illustrated). A tensioner (not illustrated) can be provided to prevent slack within loop258. Axle264is fixed for rotation with pulley260by an interlocking key268.

Loop258can be rotated (with pulleys260and262) either manually by a hand crank (not illustrated) or by a motorized mechanism such as an electric motor (not illustrated). The embodiment illustrated inFIG. 12is intended for low speed, low force applications and provides a fixed radius zone for sanding tangent to the o.d. of each of the pulleys260and262. The pulleys260and262can be of the same or differing diameters as required by a particular application.

Referring toFIG. 13, a broken, sectioned portion of pulley260with an overlaying segment of sanding rope250is illustrated. As described herein above, sanding rope250is constructed with a soft, foam-like generally rod shaped base portion270, which is substantially of constant cross-section along its axial line of elongation. An abrasive outer coating or layer272is applied to the outer peripheral surface of base portion270by an intermediate adhesive layer274. The abrasive layer272covers substantially the entire circumferential surface of the sanding rope250.

Sanding rope258is divided into a plurality of discrete abrasive surface regions276separated by outwardly opening annular recesses or neck regions278. The abrasive surface regions276and intermediate neck regions278form a repeating pattern to facilitate usage of the sanding rope250, as well as inexpensive manufacturing by simple extrusion process. Such construction materially adds to the overall flexibility of the sanding rope250, allowing it to be draped over work pieces or pulleys of relatively small diameter without concern for deformation of the abrasive layer272. This aspect of the invention permits sanding of extremely intricate workpiece features. Preferably, the axial length of the individual abrasive regions276and recesses/necks remain constant. The specific dimensions of the abrasive surface regions276are selected as a function of the diameter of the sanding rope250as well as the intended application, material to be sanded, rate of sanding, and the like. The axial dimension of the neck regions are preferably kept to a minimum, but must be able to adapt to the minimum sanding radius contemplated for the specific application.

To maximize overall flexibility of sanding rope250, neck regions278extend radially through abrasive layer272and adhesive layer274, exposing the relatively softer base portion270. In the relaxed condition wherein successive abrasive surface regions276are in axial alignment, the average circumferential width (W-ave.) remains substantially constant. When sanding rope250is dressed over a pulley or workpiece, the outer portion of each neck region278is locally distended under tension to momentarily assume a maximum axial dimension (W-max.). Simultaneously, the inner portion of each neck region278is locally compressed to momentarily assume a minimum axial dimension (W-min.).

Referring toFIGS. 14 and 15, the structural detail and operation of fastener256is illustrated. Fastener256is a clam shell type design made of injection molded plastic or other suitable material. Fastener256is generally cylindrical in shape and comprises upper and lower half portions,280and282, respectively, joined by a living hinge284. Symmetrically facing, semi-cylindrical upper and lower axial passageways286and288are centrally formed within fastener256. Sharpened barbs290are integrally formed with upper half portion280and extend into upper passageway286. An axial stop member292is integrally formed with lower half portion282and extends into lower passageway288.

In application, ends252and254of sanding rope250define the axially outwardly extending stub ends of an elongated, non-resilient, flexible cord294which extends through the center of base portion270of sanding rope250throughout its entire length. The stub ends of cord294are dressed within passageways296and298from opposite ends of fastener256until the stub ends of cord294abut each side of stop member292. Thus positioned, upper and lower half portions280and282are rotated into the orientation illustrated inFIG. 15, whereby a self-engaging latch arm296integrally formed within upper half portion280snap-engages a mating engagement surface298formed within lower half portion282. Thus positioned, barbs290pierce into cord294to affect the closure of the loop258(referFIG. 12) and allow the application of axial tension forces there through.

The outer circumferential surface of fastener256is preferably covered by an abrasive layer300and an intermediate adhesive layer302to enhance the overall sanding effect of the sanding rope250when configured in a loop258.

Referring toFIG. 16, an alternative design fastener304is applied to join two opposed ends306and308of a length of sanding rope310. As described herein above, sanding rope310has an elongated non-resilient, flexible cord312axially disposed within a base portion314formed of relatively soft, compressible material such as foam or rubber. The outer peripheral surface of base portion314is substantially covered by an abrasive layer316bonded to base portion314by an intermediate adhesive layer318. Axially spaced circumferential recesses or neck regions320define outer abrasive surface regions322there between. Ends306and308of sanding rope310have rope stubs324and326, respectively, extending axially there from.

Referring toFIGS. 16 and 17, fastener304is formed of two opposed frustu-conical body portions328and330formed of stamped metal, molded plastic or other suitable material. Body portion328is associated with rope end306, opening rightwardly as viewed inFIG. 16. The small diameter, lefthandmost end of body portion328forms an opening332to receive rope stub324. Axially reversed barbs334integrally formed with body portion328permit rope stub324to be manually displaced rightwardly with respect to body portion328, but check any relative leftward displacement. A knot336formed in rope stub324provides additional design robustness and ensures against inadvertent release of rope stub324from body portion328of fastener304. An axially offset keyhole opening338formed in body portion328permits knot336to be pre-formed and assembled by passing it through keyhole opening338. A radially outwardly directed circumferential flange340is integrally formed at the righthandmost end of body portion328.

Body portion328is assembled with end306of sanding rope310by the following steps. First, rope stub324is dressed axially away from end306and through keyhole opening338. While manually gripping rope stub324, body portion328is oriented concentrically with rope end306and pushed leftwardly therein, resiliently deforming the soft base portion314until the flange340is substantially aligned with rope end306. Thereafter, rope stub324is radially displaced from keyhole338into opening332and released. The natural resilience of the base portion314material will urge body portion328rightwardly, thereby causing the barbs334to bite into the cord312. Finally, knot336is formed in rope stub324with care being taken that the knot336is fully disposed within body portion328.

Body portion330is associated with rope end308, opening leftwardly as viewed inFIG. 16. Body portion330is largely a mirror image of body portion328, including an axial opening342in the small diameter righthandmost end thereof. Axially reversed barbs344are integrally formed with body portion330and permit rope stub326to be manually displaced leftwardly with respect to body portion330but check any rightward withdrawal of rope stub326from opening342. A knot346formed in rope stub326provides additional robustness of the design as described herein above. An axially offset keyhole opening (not illustrated) formed in body portion330facilitates assembly as described herein above. A radially outwardly directed circumferential flange348is integrally formed at the lefthandmost end of body portion330. Four circumferentially equally spaced snap engagement members350extend axially leftwardly from flange348and are integrally formed with body portion330.

Body portion330of fastener304is assembled with end308of sanding rope310substantially as described herein above with respect to body portion328and end306, with care being taken to align the flange348of body portion330with the end308of sanding rope310and the knot346being fully disposed within body portion330.

A final assembly step involves manual axial alignment of the ends306and308and axially pressing them together. Insodoing, snap engagement members350serve to guide the flange340of connector body portion328until engagement occurs as illustrated inFIG. 16. The concentric positioning of flanges340and348ensures precise alignment of the rope ends306and308. Finally, having the flanges340and348aligned with their respective rope ends306and308, respectively, causes to minimize the resultant axial gap between ends306and308. This configuration results in extremely precise sanding by the sanding rope310as well as an aesthetically pleasing appearance, wherein the point of interconnection of sanding rope ends is not apparent.

Referring toFIG. 18, an alternative method of forming sanding rope352is illustrated. Rather than co-forming the completed article, as in the case of the embodiment described in connection withFIG. 5herein above, a resilient foam or rubber base portion354is pre-formed with flexible cord356disposed therein. A layered composite consisting of an abrasive layer358, a first adhesive layer360, a carrier layer362and a second adhesive layer364is prepared in strip form and adhesively applied to base portion354in a spiral orientation extending along axis C—C. Suitable gaps366are formed between adjacent edges of the composite overlayment368. The gaps enhance overall flexibility of sanding rope352as do the neck regions278of the sanding rope250described in connection withFIGS. 12–15herein above. Although a single strip368is illustrated, it is contemplated that two or more parallel stripe could be substituted.

Referring toFIG. 19, sanding rope370could be formed in a continuous loop without the use of mechanical fasteners256and304described herein above by substituting a suitable weldment or bond372joining opposed ends374and276of sanding rope370. It is contemplated that the weldment/bond would affix the base portions378, rather than the inner cord380or the outer abrasive layer382and adhesive layer384.

Referring toFIG. 20, the application of a continuous loop of sanding rope386constructed in accordance with the teachings herein on a band saw like apparatus388is illustrated. Sanding rope386is dressed over two vertically spaced pulleys390and392. The upper pulley390is mounted to freely rotate about an axis, while the lower pulley392is rotated by an electric motor394through a suitable drive apparatus396. A work table398is suspended between the pulleys390and392. A clearance hole400in work table398serves to guide the sanding rope386passing downwardly there through. A workpiece402can be conveniently manipulated upon the top surface of the work table398to perform precise continuous sanding operations. It is contemplated that some form of tensioner or device for adjusting the vertical spacing between pulleys390and392will be required to avoid undue slack in sanding rope386.

Referring toFIG. 21, the application of a continuous loop of sanding rope404constructed in accordance with the teachings herein on a drum table sander like apparatus406is illustrated. Sanding rope404is mounted on a pulley shaped spindle408, which, in turn, is carried on an output shaft410of an electric motor-transmission drive mechanism412for rotation about axis D—D. Motor-transmission drive mechanism412is disposed within a housing414defining a horizontal work surface416on the top surface thereof. The output drive shaft410extends upwardly through an opening418in the work surface416dimensioned to position the spindle and sanding rope404vertically adjacent work surface416. A workpiece420can be conveniently manipulated upon work surface416of sander apparatus406to perform precise continuous sanding operations. Sander apparatus406can be of the type which maintains the spindle408and sanding rope404at a fixed vertical orientation with respect to the work surface416as it rotates about axis D—D or, alternatively, of the type that selectively axially reciprocates the spindle408and sanding rope404through a range of motion reflected by arrow422.

Referring toFIG. 22, a sanding rope424is illustrated in application with a workpiece such as a furniture baluster426. It is contemplated that the invention is best applied with extremely irregular contoured surfaces. Sanding rope424is applied by draping it over a surface contour of the baluster426requiring sanding with cords428oriented in a generally parallel orientation normal to the axis E—E of the baluster426. Cords428serve as grip handles, which are alternately pulled rightwardly, as illustrated by arrows430. As described hereinabove, the user will maintain continuous tension in cord428throughout the sanding process. For this type of application, it is contemplated that the sanding rope424will be of relatively small overall diameter and define a large number of discrete abrasive surface regions432interspaced by neck regions434to ensure maximum flexibility.

It is to be understood that the invention has been described with reference to specific embodiments and variations to provide the features and advantages previously described and that the embodiments are susceptible of modification as will be apparent to those skilled in the art. For example, any number of characteristic cross-sectional configurations of the inventive sanding rope can be employed for various applications.

Furthermore, it is contemplated that many alternative common inexpensive materials can be employed to construct the rope core, abrasive coating and string reinforcement. For example, abrasive coating can be applied in a powdered, granular or preformed sheet form. Accordingly, the forgoing is not to be construed in a limiting sense.

The invention has been described in an illustrative manner, and it is to be understood that the terminology which has been used is intended to be in the nature of words of description rather than of limitation. Where in the forgoing description reference has been made to ratios, integers or components having known equivalents, then such equivalents are herein incorporated as if individually set forth.

Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claim wherein reference numerals are merely for illustrative purposes and convenience and are not to be in any way limiting, the invention, which is defined by the following claims as interpreted according to the principles of patent law, including the Doctrine of Equivalents, may be practiced otherwise than as specifically described.