EP3081333B1

EP3081333B1 - A sanding tool

Info

Publication number: EP3081333B1
Application number: EP16159485.8A
Authority: EP
Inventors: Hadi Idir
Original assignee: Stanley Middle East FZE
Current assignee: Stanley Black and Decker MEA FZE
Priority date: 2015-04-13
Filing date: 2016-03-09
Publication date: 2020-08-19
Anticipated expiration: 2036-03-09
Also published as: US20160303712A1; CN106041692A; CN106041692B; EP3081333A1; GB2537372A; AU2016201672A1; GB201506237D0

Description

The present invention relates to a sanding tool with a flexible base and a lateral dust extraction arrangement on its flexible base.
Patent publication number US 5,283,988 discloses a sanding tool comprising a hollow handle of moulded plastic which has a tubular tail-piece with an opening for connection to a standard vacuum hose. The two lower ends of the hollow handle are fixed to a solid base which is provided with two holes in fluid communication with the interior of the handle and the tubular tail-piece. The base has screw clamps at either end for releasably securing a sheet of abrasive, air-permeable mesh or paper under a moulded neoprene rubber backing pad fixed to the bottom of base. The pad is also provided with two holes, each of which is aligned with a respective hole in the base.
The pad has a series of support ridges and a support perimeter which protrude from an inner recessed surface of the pad. The pad's support perimeter extends completely around the base. Passageways separate the various support ridges. The support perimeter is provided with regularly spaced ridges and grooves forming a rippled surface. The grooves provide an air passageway from the exterior perimeter of sanding tool to a negative pressure chamber formed between a working surface being sanded and recessed surface of the pad. In turn, the negative pressure chamber communicates with a standard vacuum hose via the holes though the pad and the base, the hollow handle and the tail-piece.
In use, the vacuum hose sucks dust entrained air laterally in from the exterior perimeter of sanding tool. The rubber material chosen for the pad supports the abrasive sheet and conforms to small lumps or protrusions on the working surface.
Patent publication number FR 2964892 , which has been assigned to the applicant of the present application, discloses a sanding tool which is particularly useful for smoothing curved surfaces, like, for example, car body panels after repair.
Referring to Figures 1 and 2, the sanding tool of FR 2964892 comprises a handle 10, a flexible base 20 and connecting means 22 to connect first 24 and second 25 pivot points of the flexible base 20 with respective first 11 and second 12 pivot points at the ends of the handle 10. The first 24 and second 25 pivot points of the flexible base 20 are capable of moving relative to the first 11 and second 12 pivot points at the end of the handle 10 in a vertical plane 30 (passing through and perpendicular to the first 11 and second 12 pivot points).
The sanding tool may be used for sanding many materials, for example wood, plastics material or metallic material. The flexible base 20 is made of a resilient flexible metallic material such as a sheet of stainless steel or spring steel. Alternatively, it could be made another resilient flexible laminar material, such as plastics material.
The sanding tool comprises a guiding means 40 for guiding displacement of an intermediate point 26 of the flexible base 20 (located between its first 24 and second 25 pivot points) in the vertical plane 30. The sanding tool comprises biasing means 50 for biasing the intermediate point 26 of the flexible base 20 away from a third point 14 of the handle 10. The third point 14 is located between the first 11 and second 12 pivot points of the handle 10.
The guiding means 40 for guiding displacement of the intermediate point 26 of the flexible blade 20 in the vertical plane 30 comprises a rod 41, connection means 42 for connecting a first end 43 of the rod 41 to the intermediate point 26 of the flexible base 20, for example by welding or screwing. The guiding means 40 comprises a bearing 44 for supporting the rod 41 in the handle 10. The bearing 44 permits vertical translation of the rod 41 with respect to the handle 10 along an axis 45 through the intermediate point 26 of the flexible base 20 and in the vertical plane 30.
The biasing means 50 preferably comprises a compression spring 51 coiled around the rod 41. The two ends 52, 53 of the spring 51 abut, respectively, the flexible base 20 and the handle 10. The bearing 44 comprises a linear bearing 46 having an inner sleeve 47 (in which the rod 41 is supported), an outer sleeve 48 fixed within the handle 10, and rolling means 49, such as balls or rollers, mounted in cooperation with inner 47 and outer 48 sleeves. The linear bearing 46 is a common type well known to the skilled addressee.
The connecting means 22 (for connecting the first 24 and second 25 pivot points of the flexible base 20 to, respectively, the first 11 and second 12 pivot points of the handle 10) comprises connecting arms 27, 28 whose respective ends are mounted for rotation about axes substantially perpendicular to the vertical plane 30. The connecting arms 27, 28 are mounted for rotation with respect to the handle 10 and the flexible base 20. When the base 20 is substantially planar (see Figure 1) the distance separating the first 11 and second 12 pivot points of the handle 10 is less than the distance separating the first 24 and second 25 pivot points of the flexible base 20. The connecting roods 27, 28 allow the flexible base 20 to bend. The position of the connecting arms 27, 28 in dashed lines (see Figure 2) is an extreme position for when the flexible base 20 undergoes a maximum curvature (in one way or the other). This allows the flexible base 20, when curved, to adapt in shape to concave and convex surfaces.
The sanding tool comprises attachment means for attaching an abrasive sheet 60 to an underside surface 29 of the flexible base 20 on the opposite side to the handle 10. The attachment means may be of any type, for example adhesive bonding, hook and loop fastening, mechanical fastening, or electromagnetic attraction.
WO 2014/124614 A1 , which is the basis for the preamble of appended claim 1, discloses a sander especially for sanding curved surface areas.
US 2012/0222230 A1 discloses a tool, an attachment head and a power tool system, each for working on contoured surfaces.
According to the present invention, there is provided a sanding tool according to claim 1.
The sanding tool of the present invention provides a base which is flexible to enable an abrasive sheet to adapt to a flat, convex, concave or undulating work surface as may be required when working on vehicle bodywork, for example. The flexible base has a flat bottom surface which provides uniform support to the abrasive sheet which may help to accomplish a smoother finish. Advantageously, the bottom surface provides a barrier from the work surface behind which the flexible pad's dust extraction channel may be protected. The sanding tool may generate a lot of dust. The or each dust extraction inlet arranged in or near a perimeter of the base may suck dust entrained air and deliver it to a vacuum source even while the bottom surface is continually flexing with the contours of the work surface. The flexible base is less expensive to manufacture because it does not need to be formed with an array of through-holes or suchlike. Sheet metal or plastics material will suffice. The flexible pad is pre-formed with the or each dust extraction inlet channel and fixed to the top surface of the base by adhesive or another simple fixing means.
Preferably, the sanding tool comprises an intermediate guide arranged to guide displacement of an intermediate point of the base and wherein the intermediate point is displaceable in the plane. The intermediate guide provides additional stability to the base as it flexes.
Preferably, the sanding tool comprises biasing means arranged to bias the intermediate point of the flexible base away from a third point of the handle and wherein the third point is located between the first and the second pivot points of the handle and optionally wherein the third point (140,240) is located in the plane. The biasing means may be a helical spring or a rubber block or any other device or spring capable of biasing the intermediate point of the base away from the third point of the handle. This bias may helps to maintain an even pressure on the underside surface of the base as it flexes to adapt to a work surface's contours.
Preferably, the intermediate guide comprises: a rod; a fastener for connecting a first end of the rod to the intermediate point; and a bearing for supporting the rod in displacement relative to the handle in a second direction passing through the intermediate point and contained in the plane and wherein the second direction makes a non-zero angle with respect to a straight line passing through the first and second pivot points of the handle. The rod, fastener and bearing arrangement provides a simple intermediate guide which provides reliable stability to the base as it flexes.
The at least one dust extraction inlet channel is fluidly connectable to a vacuum source via a coupling arrangement. The coupling arrangement extends the reach of the or each dust extraction inlet channel thereby facilitating connection to an external vacuum source.
The coupling arrangement comprises a tubular coupling. Preferably, the coupling arrangement comprises a tubular nozzle detachably coupled to the tubular coupling. This may allow easier disassembly of the coupling arrangement to facilitate unblocking of dust and debris caught in the coupling arrangement. The coupling arrangement may comprise external serrations for gripping a vacuum hose.
Preferably the at least one dust extraction inlet channel comprises a plurality of side inlet channels. This helps to spread suction more evenly around the perimeter of the flexible base.
Preferably, the plurality of side inlet channels is fluidly connectable to a vacuum source via a central channel formed in the flexible pad. The central channel gathers dust and dirt entrained air from all the side inlet channels and directs it towards the vacuum source.
The central channel may comprise the plane. The central channel aligned to flex within the plane. Thus, the central channel gathers dust and dirt entrained air from along substantially the length of the flexible base.
Preferably, the side inlet channels are each funneled into the central channel by a respective funnel and wherein the funnels taper inwardly in a direction towards a vacuum source. The inward taper from the mouths of the funnels causes a decrease in cross-sectional area so that air flow speed increases in the general direction of the vacuum source. This helps to maintain entrainment of particulate matter in the air flow.
Preferably, each funnel comprises curved lips. This smooth curved lips help to reduce turbulence and energy losses.
Preferably, each side inlet channel spans a dimension of the flexible pad. This helps to provide suction of dust and dirt entrained air from opposite sides of the flexible base.
Preferably, the flexible pad is elongate and wherein side inlet channels are spaced at intervals along an elongate dimension of the flexible pad. This helps to provide suction of dust and dirt entrained air along the greater length of the flexible base. Preferably, the side inlet channels are spaced at equiangular intervals along the elongate dimension of the flexible pad.
Embodiments and advantages of the invention will be understood by reference to the following description which is given by way of example and in association with the accompanying drawings of which:

Figure 3 is a perspective view of a long sanding tool according to the present invention;
Figure 4 is an exploded perspective view of the long sanding tool of Figure 3;
Figure 5 is an exploded perspective view of a flexible base of the long sanding tool of Figure 3;
Figure 6 is a side elevation view of a flexible pad of the flexible base of Figure 5;
Figure 7 is an underside view of the flexible pad of Figure 6;
Figure 8 is a side elevation view of a tubular nozzle;
Figure 9 is a side elevation view of a tubular coupling;
Figure 10 is a perspective view of a short sanding tool according to the present invention;
Figure 11 is an exploded perspective view of the short sanding tool of Figure 10;
Figure 12 is an exploded perspective view of a flexible base of the short sanding tool of Figure 10;
Figure 13 is a side elevation view of a flexible pad of the flexible base of Figure 12; and
Figure 14 is an underside view of the flexible pad of Figure 12.

For consistency, features of the long sanding tool according to the present invention which correspond to those of the sanding tool of FR2964892 have the same feature reference number increased by one hundred.
Referring to Figures 3 to 5, the long sanding tool comprises a handle 110, a generally rectangular flexible base 120 and connecting means 122 to connect first 124 and second 125 pivot points of the flexible base 120 with respective first 111 and second 112 pivot points at the ends of the handle 110. The first 124 and second 125 pivot points of the flexible base 120 are capable of moving relative to the first 111 and second 112 pivot points at the end of the handle 110 in a vertical plane 130 passing through the handle 110 and perpendicular to the first 111 and second 112 pivot points.
The handle 110 is formed of two clam shells 110a, 110b joined together at the vertical plane 130 passing through the handle 110 by fasteners 116, as is best shown in Figure 4.
The long sanding tool may be used for sanding many materials, for example wood, plastics material or metallic material. The flexible base 120 is made of a resilient flexible metallic material such as a sheet of stainless steel or spring steel. Alternatively, it could be made another flexible laminar material, such as plastics material.
The long sanding tool comprises a guiding means 140 for guiding displacement of an intermediate point 126 of the flexible base 120 (located between its first 124 and second 125 pivot points) in the handle's vertical plane 130. The long sanding tool comprises biasing means 150 for biasing the intermediate point 126 of the flexible base 120 away from a third point 114 of the handle 110. The third point 114 is located between the first 111 and second 112 pivot points of the handle 110.
The guiding means 140 for guiding displacement of the intermediate point 126 of the flexible base 120 in the handle's vertical plane 130 comprises a rod 141, a fastener 142 for connecting a first end 143 of the rod 141 to the intermediate point 126 of the flexible base 120, for example by welding, riveting or screwing. The guiding means 140 comprises a bearing 144 for supporting the rod 141 in the handle 110. The bearing 144 permits vertical translation of the rod 141 with respect to the handle 110 along an axis 145 through the intermediate point 126 of the flexible base 120 and in the handle's vertical plane 130.
The biasing means preferably comprises a compression spring 150 coiled around the rod 141. The two ends 152, 153 of the spring 150 abut, respectively, the flexible base 120 and the handle 110. The bearing comprises a linear bearing 144 having an inner sleeve 147 (in which the rod 141 is supported), an outer sleeve 148 fixed within the handle 110, and rolling means, such as balls or rollers, mounted in cooperation with inner 147 and outer 148 sleeves. The outer sleeve 148 is fastened to the handle clam shell 110a by a pair of fasteners 149. The linear bearing 144 is a common type well known to the skilled addressee.
The connecting means 122 each comprises a connecting arm 127, 128 whose respective ends are mounted for rotation about axes substantially perpendicular to the handle's vertical plane 130.
The connecting arms 127, 128 are mounted for rotation with respect to the handle 110 and the flexible base 120. When the base 120 is substantially planar the distance separating the first 111 and second 112 pivot points of the handle 110 is less than the distance separating the first 124 and second 125 pivot points of the flexible base 120. The connecting roods 127, 128 allow the flexible base 120 to bend. The connecting arms 127, 128 adopt an extreme position when the flexible base 120 undergoes a maximum curvature (one way or the other) such that the distance separating the first 124 and second 125 pivot points of the flexible base 120 diminishes until it is similar to, or the same as, the distance separating the first 111 and second 112 pivot points of the handle 110. This allows the flexible base 120, when curved, to adapt in shape to concave and convex surfaces.
Referring in particular to Figure 5, the long sanding tool comprises an attachment means 129 for attaching an abrasive sheet to an underside surface of the flexible base 120 on the opposite side to the handle 110. The attachment means 129 shown is a hook and loop fastening system, but it may be of any type, for example adhesive bonding, mechanical fastening, or electromagnetic attraction.
Referring to Figure 3 to 9, the long sanding tool has a dust extraction arrangement for sucking dust formed around the flexible base 120 while the long sanding tool is in use. The long sanding tool comprises a rectangular pad 160 fixed to the top surface of the flexible base 120 on the same side as the handle 110. In the present example, the pad 160 is made of flexible foam rubber material, although it may be made of any flexible resilient material capable of forming the network of duct extraction channels described below.
The long sanding tool comprises a tubular nozzle 170 and a tubular coupling 180. A top end 171 of the tubular nozzle 170 is surrounded by an array of circumferential serrations to facilitate a grip fit connection to a standard vacuum hose of a vacuum source. A bottom end 172 of the tubular nozzle 170 has an array of tongues for snap fit connection to a top end 181 of the tubular coupling 180. The tubular coupling 180 is secured to the flexible base 120 at the first pivot point 124 which passes through an aperture 182 though the middle of the tubular coupling 180. A bottom end 183 of the tubular coupling 180 engages an outlet hole 161 formed at the first end of the pad 160 which, in turn, leads to a network of duct extraction channels formed in the underside of the pad 160. Thus, the network of dust extraction channels may be fluidly coupled to a standard vacuum hose via the tubular nozzle 170 and the tubular coupling 180.
Referring in particular to Figures 6 and 7, the network of dust extraction channels formed in the underside of the pad 160 comprises a central channel 162 extending generally along a central longitudinal axis A-A of the pad 160 from a wall 163 near the second end of the pad 160 to the outlet hole 161 at the first end of the pad 160. The handle's vertical plane 130 comprises the axis A-A.
The central channel 162 is traversed by five side inlet channels 164a, 164b, 164c, 164d, 164e each of which spans the long sides of the pad 160 in a direction perpendicular to the axis A-A of the pad 160. The first inlet channel 164a is located about 15 percent of the length of the pad 160 from the first end of the pad 160. The fifth inlet channel 164e is located about 15% of the length of the pad 160 from the second end of the pad 160. The second 164b, third 164c and fourth 164d inlet channels are equally-spaced along the pad 160 between the first 164a and fifth 164e inlet channels.
The central channel 162 is interrupted by a hole 165 through the pad 160 where the first end 143 of the rod 141 is connected by the fastener 142 to the intermediate point 126 of the flexible base 120. The hole 165 is surrounded by a collar 166. The collar 166 and the underside of the pad 160 not having the dust extraction channels 162, 164a, 164b, 164c, 164d, 164e are generally coplanar, as is best shown in Figure 6, and are fixed to the top surface of the flexible base 120 between the first 124 and the second 125 pivot points. The dust extraction channels 162, 164a, 164b, 164c, 164d, 164e are located between the pad 160, on top, and the flexible base 120, below. This provides an air passageway from the exterior perimeter of the flexible base 120 to a negative pressure chamber formed by the dust extraction channels 162, 164a, 164b, 164c, 164d, 164e in fluid communication a vacuum source. Dust-entrained air flowing from the perimeter of the flexible base 120 into the dust extraction channels 162, 164a, 164b, 164c, 164d, 164e is indicated by the bold arrows shown in Figure 7.
Those parts of the central channel 162 extending between the outlet hole 161 and the first inlet channel 164a, between the first 164a and second 164b inlet channels and between the fourth 164d and fifth 164e inlet channels each have the shape of a small funnel 167a, 167b, 167e in cross-section. The mouth of each of the first 167a, second 167b and fifth 167e small funnels has curved lips leading to a throat with straight sides. The straight sides of the throat of the first small funnel 167a are substantially parallel. The straight sides of the throat of each of the second 167b and fifth 167e small funnels gently converge by an angle of approximately 3 degrees as they extend away from the mouth of the respective small funnel (in the direction of the outlet hole 161).
The inward taper from the mouths of the second 167b and fifth 167e small funnels causes a decrease in cross-sectional area so that air flow speed increases in the general direction of the outlet hole 161. This helps to maintain entrainment of particulate matter in the air flow.
Those parts of the central channel 162 extending between the second 164b and third 164c inlet channels and between the third 164c and fourth 164d inlet channels each have the shape of a large funnel 167c, 167d in cross-section. The mouth of each of the third 167c and fourth 167d large funnels has curved lips leading to a throat with gently converging straight sides. The straight sides of the throat of the fourth large funnel 167d converge by an angle of approximately 3 degrees as they extend away from the mouth of the fourth large funnel 167d (in the direction of the outlet hole 161). The straight sides of the throat of the second large funnel 167c continue the converging path defined by the straight sides of the throat of the fourth large funnel 167d. The third 167c and fourth 167d large funnels combine to form an enlarged area 168 of the central channel 162. The collar 166 protrudes into the middle of the enlarged area 168 in line with where the third inlet channel 164c joins the central channel 162. The width of the enlarged area 168, in a direction perpendicular to the axis A-A, is approximately twice the diameter of the collar 166.
The inward taper of the enlarged area 168 causes a decrease in cross-sectional area so that air flow speed increases in the general direction of the outlet hole 161. This helps to maintain particulate matter in the air flow.
The collar 166 does not cause a significant restriction to air flow or turbulence. This is partly due to the fact that the collar 161 is a smooth circular obstruction and the fact that the enlarged area 161 is provides a sufficiently large chamber to provide ample clearance around the collar 161.
The curved lips at the mouths of the funnels 167a, 167b, 167c, 167d, 167e help to maintain laminar air flow as it turns to flow from the inlet channels 164a, 164b, 164c, 164d, 164e into the central channel 162. This helps to reduce turbulence and energy losses.
In the present example, the entry to the first 164a, second 164b and third 164c inlet channels have a width, measured in a direction parallel to the major axis A-A, of approximately 5mm. The entry to the fourth inlet channel 164d has a width of 6mm. The entry to the fifth inlet channel 164e has a width of 7mm. This progressive increase in width of the entries to the inlet channels 164a, 164b, 164c, 164d, 164e (the further the entries are away from the outlet hole 161) helps to encourage even air volume flow rate into the inlet channels.
When a vacuum source (not shown) is connected, via a vacuum hose, to the tubular nozzle 170, the network of dust extraction channels 162, 164a, 164b, 164c, 164d, 164e is fluidly coupled the vacuum source.
The main difference between the long sanding tool and the short sanding tool is that the former has a longer flexible base 120 and a different shaped handle 110. Thus, features of the short sanding tool according to the present invention which correspond to those of the long sanding tool have the same feature reference number increased by two hundred.
Referring to Figures 9 to 12, the short sanding tool comprises a handle 210, a generally rectangular flexible base 220 and connecting means 222 to connect first 224 and second 225 pivot points of the flexible base 220 with respective first 211 and second 212 pivot points at the ends of the handle 210. The first 224 and second 225 pivot points of the flexible base 220 are capable of moving relative to the first 211 and second 212 pivot points at the end of the handle 210 in a vertical plane 230 passing through the handle 210 and perpendicular to the first 211 and second 212 pivot points.
The handle 210 is formed of two clam shells 210a, 210b joined together at the vertical plane 230 passing through the handle 210 by fasteners 216, as is best shown in Figure 7.
The short sanding tool may be used for sanding many materials, for example wood, plastics material or metallic material. The flexible base 220 is made of a resilient flexible metallic material such as a sheet of stainless steel or spring steel. Alternatively, it could be made another flexible resilient material, such as plastics material.
The short sanding tool comprises a guiding means 240 for guiding displacement of an intermediate point 226 of the flexible base 220 (located between its first 224 and second 225 pivot points) in the handle's vertical plane 230. The short sanding tool comprises biasing means 250 for biasing the intermediate point 226 of the flexible base 220 away from a third point 214 of the handle 210. The third point 214 is located between the first 211 and second 212 pivot points of the handle 210.
The guiding means 240 for guiding displacement of the intermediate point 226 of the flexible base 220 in the handle's vertical plane 230 comprises a rod 241, a fastener 242 for connecting a first end 243 of the rod 241 to the intermediate point 226 of the flexible base 220, for example by welding, riveting or screwing. The guiding means 240 comprises a bearing 244 for supporting the rod 241 in the handle 210. The bearing 244 permits vertical translation of the rod 241 with respect to the handle 210 along an axis 245 through the intermediate point 226 of the flexible base 220 and in the handle's vertical plane 230.
The biasing means preferably comprises a compression spring 250 coiled around the rod 241. The two ends 252, 253 of the spring 250 abut, respectively, the flexible base 220 and the handle 210. The bearing comprises a linear bearing 244 having an inner sleeve 247 (in which the rod 241 is supported), an outer sleeve 248 fixed within the handle 210, and rolling means, such as balls or rollers, mounted in cooperation with inner 247 and outer 248 sleeves. The outer sleeve 248 is fastened to the handle clam shell 210a by a pair of fasteners 249. The linear bearing 244 is a common type well known to the skilled addressee.
The connecting means 222 each comprises a connecting arm 227, 228 whose respective ends are mounted for rotation about axes substantially perpendicular to the handle's vertical plane 230.
The connecting arms 227, 228 are mounted for rotation with respect to the handle 210 and the flexible base 220. When the base 220 is substantially planar the distance separating the first 211 and second 212 pivot points of the handle 210 is less than the distance separating the first 224 and second 225 pivot points of the flexible base 220. The connecting roods 227, 228 allow the flexible base 220 to bend. The connecting arms 227, 228 adopt an extreme position when the flexible base 220 undergoes a maximum curvature (one way or the other) such that the distance separating the first 224 and second 225 pivot points of the flexible base 220 diminishes until it is similar to, or the same as, the distance separating the first 211 and second 212 pivot points of the handle 210. This allows the flexible base 220, when curved, to adapt in shape to concave and convex surfaces.
Referring in particular to Figure 12, the short sanding tool comprises an attachment means 229 for attaching an abrasive sheet to an underside surface of the flexible base 220 on the opposite side to the handle 210. The attachment means 229 shown is a hook and loop fastening system, but it may be of any type, for example adhesive bonding, mechanical fastening, or electromagnetic attraction.
Referring to Figure 8 to 14, the short sanding tool has a dust extraction arrangement for sucking dust formed around the flexible base 220 while the short sanding tool is in use. The short sanding tool comprises a rectangular pad 260 fixed to the top surface of the flexible base 220 on the same side as the handle 210. In the present example, the pad 260 is made of flexible foam rubber material, although it may be made of any flexible resilient material capable of forming the network of duct extraction channels described below.
The short sanding tool comprises the tubular nozzle 170 and a tubular coupling 280. The tubular coupling 180 is secured to the flexible base 220 at the first pivot point 224 which passes through the aperture 182 though the middle of the tubular coupling 180. The bottom end 183 of the tubular coupling 180 engages an outlet hole 261 formed at the first end of the pad 260 which, in turn, leads to a network of duct extraction channels formed in the underside of the pad 260. Thus, the network of dust extraction channels may be fluidly coupled to a standard vacuum hose via the tubular nozzle 170 and the tubular coupling 180.
Referring in particular to Figures 13 and 14, the network of dust extraction channels formed in the underside of the pad 260 comprises a central channel 262 extending generally along a central longitudinal axis A-A of the pad 260 from a wall 263 near the second end of the pad 260 to the outlet hole 261 at the first end of the pad 260. The handle's vertical plane 230 comprises the axis A-A.
The central channel 262 is traversed by four side inlet channels 264a, 264b, 264c and 264d each of which spans the long sides of the pad 260 in a direction perpendicular to the axis A-A of the pad 260. The first inlet channel 264a is located about 12 percent of the length of the pad 260 from the first end of the pad 260. The fourth inlet channel 264d is located about 12% of the length of the pad 260 from the second end of the pad 260. The second 264b and third 264c inlet channels are equally-spaced along the pad 260 between the first 264a and fifth 264e inlet channels.
The central channel 262 is interrupted by a hole 265 through the pad 260 where the first end 243 of the rod 241 is connected by the fastener 242 to the intermediate point 226 of the flexible base 220. The hole 265 is surrounded by a collar 266. The collar 266 and the underside of the pad 260 not having the dust extraction channels 262, 264a, 264b, 264c, 264d are generally coplanar, as is best shown in Figure 13, and are fixed to the top surface of the flexible base 220 between the first 224 and the second 225 pivot points. The dust extraction channels 262, 264a, 264b, 264c, 264d are located between the pad 260, on top, and the flexible base 220, below. This provides an air passageway from the exterior perimeter of the flexible base 220 to a negative pressure chamber formed by the dust extraction channels 262, 264a, 264b, 264c, 264d in fluid communication a vacuum source. Dust-entrained air flowing from the perimeter of the flexible base 220 into the dust extraction channels 262, 264a, 264b, 264c, 264d is indicated by the bold arrows shown in Figure 14.
Those parts of the central channel 262 extending between the outlet hole 261 and the first inlet channel 264a, between the first 264a and second 264b inlet channels and between the third 264c and fourth 264d inlet channels each have the shape of a small funnel 267a, 267b, 267d in cross-section. The mouth of each of the first 267a, second 267b and fourth 167d small funnels has curved lips leading to a throat with straight sides. The straight sides of the throat of the first small funnel 267a are substantially parallel. The straight sides of the throat of each of the second 267b and fourth 267d small funnels gently converge by an angle of approximately 3 degrees as they extend away from the mouth of the respective small funnel (in the direction of the outlet hole 261).
The inward taper from the mouths of the second 267b and fourth 267d small funnels causes a decrease in cross-sectional area so that air flow speed increases in the general direction of the outlet hole 261. This helps to maintain entrainment of particulate matter in the air flow.
The central channel 262 extending between the second 264b and third 264c inlet channels has the shape of a large funnel 267c in cross-section. The mouth of third 267c large funnel has curved lips leading to a throat with gently converging straight sides. The straight sides of the throat of the third large funnel 267c converge by an angle of approximately 3 degrees as they extend away from the mouth of the third large funnel 167c (in the direction of the outlet hole 261). The third 267c large funnel forms an enlarged area 268 of the central channel 262. The collar 266 protrudes into the middle of the enlarged area 268. The width of the enlarged area 268, in a direction perpendicular to the axis A-A, is approximately twice the diameter of the collar 266.
The inward taper of the enlarged area 268 causes a decrease in cross-sectional area so that air flow speed increases in the general direction of the outlet hole 261. This helps to maintain particulate matter in the air flow.
The collar 266 does not cause a significant restriction to air flow or turbulence. This is partly due to the fact that the collar 261 is a smooth circular obstruction and the fact that the enlarged area 261 is provides a sufficiently large chamber to provide ample clearance around the collar 261.
The curved lips at the mouths of the funnels 267a, 267b, 267c, 267d help to maintain laminar air flow as it turns to flow from the inlet channels 264a, 264b, 264c, 264d into the central channel 262. This helps to reduce turbulence and energy losses.
In the present example, the entry to the first 264a, second 264b, third 264c and fourth 264d inlet channels have a width, measured in a direction parallel to the major axis A-A, of approximately 5mm.
When a vacuum source (not shown) is connected, via a vacuum hose, to the tubular nozzle 170, the network of dust extraction channels 262, 264a, 264b, 264c, 264d, 264e is fluidly coupled the vacuum source.
The long sanding tool and the short sanding tool, as described above and illustrated in Figures 3 to 14, are used and works the following way. A user that wishes to polish a work surface whatever its curvature, be it flat, convex, concave, or a combination of these types of curvature, first attaches an abrasive sheet on the underside surface 129,229 of the flexible base 120,220. The user connects a vacuum source, via a vacuum hose, to the tubular nozzle 170. The user then grasps the sanding tool by the handle 110,210, and applies the abrasive sheet to the work surface. The user then exerts a force on the sanding tool, the force having at least two components i.e. a first component which has the effect of applying the flexible base 120,220 on the work surface, and a second component, perpendicular to the first component, which has the effect of displacing the sanding tool back and forth, in linear or circular movements or combinations of these types, on the part of the work surface in need of polishing. The first component of the force exerted by the user is transmitted to the flexible base 120,220 at its two ends 124, 125, 224, 225 via the two connecting arms 127, 128, 227, 228. As for the force applied along the whole surface of flexible base 120, 220 between its first 124, 224 and second 125, 225 pivot points and on the work surface, such force is exerted by the elasticity of the flexible base 120, 220 itself and even more so by the biasing force applied by the compression spring 150, 250 particularly in the case of a long flexible base 120. Therefore, as the sanding tool moves back and forth during the sanding, the force exerted on the work surface is approximately constant and is almost entirely exerted by the compression spring 150, 250. The compression spring 150, 250 may be selected to generate a relatively constant biasing force regardless of the position of the first end 143, 243 of the rod 141, 241.
Meanwhile, the vacuum source is started. Dust created by a sanding action with the sanding tool may be sucked laterally in from around the perimeter of the flexible base 120, 220 into the inlet channels 164a, 164b, 164c, 164d, 164e, 264a, 264b, 264c, 264d and into the central channel 162, 262 from where dust entrained air travels through the outlet hole 161, 262, into the tubular coupling 180, through the tubular nozzle 170, up the vacuum hose and to the vacuum source. This is because the tubular coupling 180 and the tubular nozzle 170 may pivot a small amount about the first pivot point 124, 224 in relation to the handle 120, 220 to follow movement of the pad 160, 260 (and its network of dust extraction channels 162, 164a, 164b, 164c, 164d, 164e, 262, 264a, 264b, 264c, 264d) which is free to bend with the flexible base 120, 220. Dust extraction continues even when the flexible base 120, 220 encounters a bump or a hard edge because these types of impact will not be transmitted to the pad 160, 260. As such, the network of dust extraction channels 162, 164a, 164b, 164c, 164d, 164e, 262, 264a, 264b, 264c, 264d is largely protected by the flexible base 120. Dust extraction efficiency is unaffected whether the work surface be flat, convex, concave, or a combination of these types of curvature. The flexible base 120, 220 presents a work surface with a smooth bottom surface uninterrupted by the dust extraction channels 162, 164a, 164b, 164c, 164d, 164e, 262, 264a, 264b, 264c, 264d. Also, the abrasive sheet need not be air-permeable because dust created by a sanding action is sucked laterally in from around the perimeter of the flexible base 120, 220 and not through it. Thus, an abrasive sheet need not be formed with any particular pattern of through-holes to suit an arrangement of dust extraction holes of the sanding tool's flexible base 120, 220.

Claims

A sanding tool comprising:
a handle (110,210) with a first pivot point (111,211) and a second pivot point (112,212) distal from the first pivot point;

a flexible base (120,220) having a bottom surface for attachment to an abrasive sheet on an opposite side to the handle (110,210);

arms (127,227/128,228) arranged to couple the base (120,220) with respective first (111,211) and second (112,212) pivot points on the handle (110,210), wherein the base is capable of moving relative to the first and second pivot points of the handle in a plane (130,230) passing through the first and second pivot points of the handle,

characterized in that the sanding tool comprises:
a flexible pad (160,260) arranged on the top surface of the flexible base (120,220), wherein the flexible pad is formed with at least one dust extraction inlet channel (164a, 164b, 164c, 164d, 164e, 264a, 264b, 264c, 264d) arranged to suck air from a perimeter of the flexible base (120,220) and wherein the at least one dust extraction inlet channel is fluidly connectable to a vacuum source via a coupling arrangement (161, 170, 180/261, 170, 180), comprising a tubular coupling (180,) and wherein the tubular coupling (180) is secured to the flexible base at the first pivot point.
A sanding tool as claimed in claim 1, wherein the sanding tool comprises an intermediate guide (140,240) arranged to guide displacement of an intermediate point (126,226) of the base (120,220) and wherein the intermediate point is displaceable in the plane (130,230).
A sanding tool as claimed in claim 2, wherein the sanding tool comprises biasing means (150,250) arranged to bias the intermediate point (126,226) of the flexible base (120,220) away from a third point (114,214) of the handle (110,210) and wherein the third point (114,214) is located between the first (111,211) and the second (112,212) pivot points of the handle (110,210) and optionally wherein the third point (114,214) is located in the plane (130,230).
A sanding tool as claimed in either one of claims 2 or 3, wherein the intermediate guide (140,240) comprises:
a rod (141,241);

a fastener (142,242) for connecting a first end (143,243) of the rod (141,241) to the intermediate point (126,226); and

a bearing (144,244) for supporting the rod (141,241) in the handle (110,210) and permitting vertical translation of the rod (141,241) with respect to handle along an axis (145,245) through the intermediate point of the flexible base and in the handle's vertical plane (130,230).
A sanding tool as claimed in claim 1, wherein the coupling arrangement comprises a tubular nozzle (170,) detachably coupled to the tubular coupling.
A sanding tool as claimed in claim 5, wherein the coupling arrangement comprises external serrations.
A sanding tool as claimed in any one of the previous claims, wherein the at least one dust extraction inlet channel comprises a plurality of side inlet channels (164a, 164b, 164c, 164d, 164e, 264a, 264b, 264c, 264d).
A sanding tool as claimed in claim 7, wherein the plurality of side inlet channels (164a, 164b, 164c, 164d, 164e, 264a, 264b, 264c, 264d) is fluidly connectable to a vacuum source via a central channel (162, 262) formed in the flexible pad (160, 260).
A sanding tool as claimed in claim 8, wherein the central channel (162, 262) comprises the plane (130,230).
A sanding tool as claimed in either one of claims 8 or 9, wherein the side inlet channels (164a, 164b, 164c, 164d, 164e, 264a, 264b, 264c, 264d) are each funneled into the central channel (162, 262) by a respective funnel (167a,167b,167c,167d,167e,267a,267b,267c,267d) and wherein the funnels taper inwardly in a direction towards a vacuum source.
A sanding tool as claimed in claim 10, wherein each funnel (167a,167b,167c,167d,167e,267a,267b,267c,267d) comprises curved lips.
A sanding tool as claimed in any one of claims 7 to 11, wherein each side inlet channel (164a, 164b, 164c, 164d, 164e, 264a, 264b, 264c, 264d) spans a dimension of the flexible pad (160, 260).
A sanding tool as claimed in any one of claims 7 to 12, wherein the flexible pad (160,260) is elongate and wherein side inlet channels (164a, 164b, 164c, 164d, 164e, 264a, 264b, 264c, 264d) are spaced at intervals along an elongate dimension of the flexible pad (160, 260).