EP0543890A1

EP0543890A1 - Abrading device

Info

Publication number: EP0543890A1
Application number: EP91914893A
Authority: EP
Inventors: David Anthony Edgerley; Ian James Hamilton Coulter
Original assignee: Individual
Current assignee: Individual
Priority date: 1990-08-16
Filing date: 1991-08-13
Publication date: 1993-06-02
Also published as: WO1992003256A1; GB2248568B; GB2248568A; IL99215A0; CA2091582A1; GB9117284D0; GB9017981D0; AU8411191A

Abstract

Dispositif à abraser (10) comprenant une chambre (12) servant de réservoir (14) pour un fluide refroidissant, une roue à abraser (15) montée dans la chambre (12) et pouvant tourner autour d'un axe pratiquement horizontal, de premiers moyens (18) servant à diriger le fluide refroidissant du réservoir (14) vers le haut lors de la rotation de la roue à abraser (15) autour de son axe, et de seconds moyens (20) servant à diriger ledit fluide dirigé vers le haut à travers une face d'aiguisement (25) de la roue à abraser (15) afin de refroidir un outil de coupe en train d'être aiguisé contre ladite face (25). Un porte-outil est monté de manière à se déplacer par rapport à une partie de surface (25) de la roue à abraser qui est placée à un angle étroit, par exemple à moins de 5° (de préférence environ 1°), par rapport à la ligne perpendiculaire à l'axe de la roue et se trouve en contact avec l'outil lors de son utilisation.Abrading device (10) comprising a chamber (12) serving as a reservoir (14) for a cooling fluid, an abrading wheel (15) mounted in the chamber (12) and rotatable about a substantially horizontal axis, first means (18) for directing coolant from the reservoir (14) upwards as the abrading wheel (15) rotates about its axis, and second means (20) for directing said directed fluid upwards up through a sharpening face (25) of the abrading wheel (15) to cool a cutting tool being sharpened against said face (25). A tool holder is mounted for movement relative to a surface portion (25) of the wheel to be abraded which is placed at a narrow angle, for example less than 5° (preferably about 1°), by relative to the line perpendicular to the axis of the wheel and is in contact with the tool during use.

Description

ABRADING PgVJCE

PESCRipryoy

This invention relates to abrading devices and is particularly, but not exclusively, concerned with abrading devices for use in sharpening edge tools - preferably edge tools that are hand held in use (e.g. chisels, screw¬ drivers, scissor-blades, shear-blades, knives and the like).

A common reguirement with abrading devices is to ensure that the abrading surface does not over heat. It has already been suggested to sharpen an edge tool against the rotating cylindrical surface of a grinding wheel that enters a water bath. Although the wheel's perimeter is cooled there is a tendency for the water to be splashed into unwanted areas - particularly with increased rotational wheel speed. Moreover, the cylindrical surface of the wheel will provide a cusp-like form to the edge being sharpened instead of a V-formed edge that is often the ideal requirement.

It is therefore desirable to provide an abrading device which can overcome these and/or other disadvantages of the prior art. According to a first aspect of this invention, there is provided an abrading device comprising: a housing to provide a reservoir for cooling fluid; an abrading wheel mounted in the housing for rotation about a substantially horizontal axis; first means to direct cooling fluid from the reservoir upwards upon rotation of the abrading wheel about its axis; and second means to direct the said upwardly directed fluid across a sharpening face of the abrading wheel to effect cooling of an edge tool being sharpened against said face.

The said first means (to direct cooling fluid upwards) may comprise a paddle-wheel structure to move (e.g deflect or carry) the fluid upwards. Alternatively, as is preferred, the said first means (to direct cooling fluid upwards) may comprise a peripheral surface of the abrading wheel itself to move the fluid upwards by centrifugal action.

Advantageously the said second means (to direct fluid across the wheel's sharpening face) comprises conduit means.

Preferably the abrading device comprises a deflector plate to deflect fluid emanating from the second means in a direction towards the said sharpening face of the abrading wheel.

Advantageously the deflector plate is directed towards a recess in said sharpening face and such as to deflect fluid from the second means into said recess. Preferably said recess is located centrally of said sharpening face on the abrading wheel's axis. In use, coolant fluid deflected into said recess can flow out therefrom over said sharpening face at a rate providing an appropriate cooling effect with little or no splashing.

Said sharpening face may be radial or, as is preferred, may be slightly conical, e.g. with a cone angle of at least 175" (preferably of 178°).

Preferably, the peripheral surface of the abrading wheel comprises a cylindrical perimeter and a bevelled surface between the cylindrical perimeter and said sharpening face, the latter having a radial extent less than that of the cylindrical perimeter. Advantageously a baffle plate in the housing extends to adjacent said bevelled surface, so that (at least prior to any wear) the sharpening face projects in front of the baffle plate. In use, any coolant thrown outwards by the bevelled surface will tend to be thrown rearwardly of the baffle plate thereby reducing the possibility of such coolant emanating out from the front of the housing with consequential splashing of the operator and/or coolant loss.

According to a second aspect of this invention there is provided for abrading an implement, an abrading device comprising an abrading wheel rotatable about an axis, an implement holder, and means for mounting the holder for movement relative to a surface portion of the abrading wheel, that is directed at a small angle to the perpendicular to said axis and is in use in contact with the implement. The said small angle is preferably of the order of 1° .

Advantageously the said surface is of frusto-conical form. The consequential large cone angle (that is complementary to said small angle) ensures that the sharpening face has a substantial radial extent (substantially greater than, say, the width of the abrading wheel's cylindrical perimeter) whereby any hollow ground effect imparted to the implement's edge by the curvature of the sharpening face will be negligble and of virtually no consequence.

Preferably said movement is reciprocal.

Advantageously stop means are provided associating the said holder and a support unit for the abrading wheel, said stop means serving to prevent the implement and wheel coming out of contact during said movement of the holder.

Preferably a reservoir for cooling fluid is provided in a (or the) support unit for the abrading wheel.

Advantageously said support unit comprises a housing and the abrading device further comprises the said first means and second means of said first aspect of this invention.

By way of non-limiting example, embodiments of the invention will now be described with reference to the accompanying drawings of which:-

Figure 1 is a schematic axial cross-section through a first embodiment of an abrading device according to this invention; Figure 2 is a schematic sharpening cross-section on the line A-A of Fig. 1; Figure 3 is a schematic cross-sectional view taken on the line B-B of Fig. 1; Figure 4 is an axial cross-section through a second embodiment of an abrading device according to this invention; Figure 5 is a plan view of the device shown in Fig. 4; Figure 6 is a front elevation of the device shown in Fig. 4; Figure 7 is a plan view of part of the device of Fig. 4 showing parts thereof obscured in Fig. 5; Figure 8 is a front elevation of part of the device of

Fig. 4 showing parts thereof obscured in Fig. 6;

Figure 9 is a schematic side view of the device of Fig. 4 showing a setting mode of the device; Figure 10 is a perspective sketch of a modification of the device shown in Figs. 4 to 9;

Figure 11 shows at 11A a schematic, partly-exploded, perspective view (from the lower front) of parts of a third embodiment of abrading device according to this invention in an open condition, and at 11B (with additional parts) in a closed condition; Figure 12 and Figure 13 are similar schematic, partly- exploded, perspective views (from the upper rear) showing further parts of the abrading device of

Fig 11; Figure 14 is another schematic perspective view (from the upper rear showing parts of the abrading device of Fig 11; and Figure 15 is a schematic, partly-exploded perspective view of the rear of an implement clamp for use with the parts of the abrading device of Figs 11 to 14 or of Figs 7 and 8.

The abrading device 10 of Figs 1 to 3 comprises a housing 12 to provide a reservoir for cooling fluid 14, e.g. water. An abrading wheel 15 provided with a stepped central bore 26 is mounted on a shaft 13 by a T-section retainer 17 so as to be rotatable in the housing about the substantially horizontal axis 16 of shaft 13 and with a lower sector of the abrading wheel immersed in the reservoir's fluid 14.

The abrading wheel 15 has its periphery formed by a cylindrical perimeter surface 18 and an annular bevelled surface 19 extending from surface 18 progressively inwardly towards axis 16 as it extends forwardly of housing 12 and towards the wheel's sharpening face 25. The sharpening face 25 is provided by the inclined face of a cone of very wide angle, e.g. greater than 175^* (in this preferred example, equal to 178 " ) . Thus the cone has a substantial 'base' diameter (which is defined by the inner diameter of the bevelled surface 19) and the sharpening face 25 is almost radial.

The housing 12 includes conduit means 20 to direct upwardly moved fluid 24 across the almost radial sharpening face 25 of the abrading wheel 15. The conduit means 20 has an enlarged lower mouth 21 disposed laterally of the wheel's perimeter surface 18, the upwardly moved fluid 24 being conducted from this mouth 21 upwardly to adjacent the top of wheel 15 and then forwardly of the wheel 15 to emanate from an outlet 23 of the conduit means. From outlet 23 the fluid can fall freely in front of an upper region of the wheel's sharpening face 25. This fall of fluid 24 effects cooling of said sharpening face 25 and permits sharpening of an edge tool there-against.

The arrangement is such that upon rotation of the abrading wheel 5 about its axis, cooling fluid from the reservoir is moved centrifugally upwards by the peripheral surface 18 of the abrading wheel itself.

The illustrated exemplary abrading device 10 also comprises a deflector plate 22 to deflect fluid emanating from the outlet 23 of the conduit means 20 in a direction towards the said sharpening face 25 of the abrading wheel. This deflector plate 22 is directed towards the recess 27 formed by retainer 17 in the bore 26, this recess 27 being located centrally of the sharpening face 25 on the abrading wheel's axis 16. The arrangement is such as to deflect fluid 24 emanating from outlet 23 of the conduit means into said recess, and such that the coolant fluid can then flow out therefrom over the sharpening face 25 at a rate providing an appropriate cooling effect with little or no splashing. The deflector plate 22 is preferably directed at an angle of 10^* to the horizontal so that it may be used as a rest for manually sharpening scissors against the wheel's sharpening face 25.

The housing 12 is formed internally with a baffle plate 28 directed downwardly from the underside of the conduit means 20 such that the baffle plate's lower free edge lies adjacent said bevelled surface 19. The bevelled surface 19, with perimeter surface 18, tends to throw coolant 14 backwards and outwards to behind the baffle plate 28 and thus reduces the possibility of coolant being thrown outwardly of the housing in a forwards direction towards the user. As illustrated in Fig. 1, the baffle plate 28 is positioned to be initially rearwardly of the abrading wheel's sharpening face 25 so as to allow for wear of the latter in use.

In the embodiment of Figs 4 to 9, the abrading device 110 comprises a main housing 112 having a foot portion 132 by which it is secured to the top surface of a table or bench 130 adjacent its front edge. The housing 112 has a compartment 111 which contains a removable, drawer-like reservoir 114 for the water or other cooling fluid 14. The removability of the reservoir 114 facilitates filling and post-use emptying of the reservoir.

An abrading wheel 115 having a stepped central bore 126 is mounted on a horizontal shaft 113 by a T-section screw retainer 117 thereby to be rotatable in the housing about the shaft's axis and with a lower sector of the abrading wheel immersed in the reservoir's cooling fluid 14. As in the embodiment of Figs 1-3, the abrading wheel 115 has its periphery formed by a cylindrical perimeter surface 118 and an annular bevelled surface 119 extending from cylindrical surface 118 inwardly towards the shaft 113 as it extends forwardly of housing 112 and towards the wheel's almost radial sharpening face 125. As in the embodiment of Figs. 1-3, the sharpening face 125 is provided by the sloping face of a fruεto-cone of very wide angle, e.g. greater than 175° (and in the preferred embodiment of Figs. 4-9 having an included angle of 178").

A moulded thin-walled component 134 is fitted in slots 133 in the housing 112 to co-operate with internal surfaces of the housing in defining conduit means 120 which, in like manner to the embodiment of Figs 1-3, serve to direct upwardly moved cooling fluid from the reservoir 114 to an outlet 123 of the conduit means 120, this outlet 123 being located centrally above the abrading wheel substantially in or adjacent the 'plane' of its sharpening face 125.

The upper region of main housing 112 is provided with a pair of mutually facing U-section channels 136 inclined upwardly as they extend forwardly of the housing. Adjacent their lower ends, the channels 136 are provided with openings 138 in their upper walls. A rail unit 140 of generally T-shaped outline has its "upright" or "web" portion mounted for sliding motion in the channels 136 such that its wider "head" portion 144 projects towards the front of the main housing 112.

The head portion 144 is formed integrally (e.g. by molding of plastics material) with a rail element 145 that extends transversely across the top of the main housing 112 in a vertical plane angled at a very small angle, e.g. about 1°, to the vertical plane perpendicular to the axis of the abrading wheel 115. This angle is the complementary angle to half the cone angle of the sharpening face 125. A clamp 146 for the rail unit 140 has a central limb 147 and two stubs 148 directed laterally outwards and provided with eccentric projections 149. The rail clamp 146 is mounted on main housing 112 with the stubs 148 entering the openings 138 to be moved within channels 136 to position rail element 145 as desired, the central limb 147 being then depressed to move the stubs 148 arcuately and cause their eccentric projections 149 to clamp the rail unit 140 to the channels 136 and thus fix the position of the rail element 145.

A tool clamping unit 150 of generally C-section is provided to hold the implement C (e.g. a plane iron, chisel, or the like) that is to be sharpened. This tool clamping unit 150 has a rearwardly extending flange 152 provided at its rearward end with a lip 155 of arcuate cross-section. The tool clamping unit 150 is releasably mounted in position on the main housing 112 by hooking lip 155 over the rail element 145 such that the lower, rearwardly extending portion 156 of unit 150 can abut against a stop member 154 on the main housing 112 (when the edge of implement C has been ground away) . It will be appreciated that the angle of the implement's sharpened edge will in general terms depend on the angle of inclination of the implement C to the abrading wheel's sharpening face 125, this being determined by the position of the rail unit 140 with respect to the main housing 112. In use, the tool clamping unit 150 is slid to and fro laterally of the rail element 145 of unit 140 with the implement's edge engaged against the sharpening face 125 of the rotating abrading wheel 115 and until that edge has been sharpened. The tool clamping unit 150 comprises a screw threaded bolt 158 rotatable by a hand wheel 160 and engaged in an internally threaded fixed jaw 162, a co- operating movable jaw 164 being carriec" __>y the free end of bolt 158. The movable jaw 164 is sl_^dably retained and guided by a pair of slots 166 provided in the front face of the clamp unit 150. The jaws 162, 164 have one or both of their mutually facing surfaces inclined to one another so that an implement clamped between them will be urged into abutment of the flat front wall of the clamp unit 150. The movable jaw 164 is provided with an integral stop member 165 upstanding therefrom and such as to be engageable laterally against a fixed stop member 167 provided on the rail element 145. Thus, whatever the width of the implement C being sharpened, its left-hand side cannot be moved rightwardly beyond an end position in which the stop member 165 (that moves with jaw 164) abuts against fixed stop member 167. This right-hand end position is arranged to correspond to a position for the implement's left-hand side that is just within the circumference of the abrading wheel's sharpening face 125 so that the implement C cannot slide rightwards beyond the abrading wheel and be possibly damaged upon the sliding return motion, e.g. by engagement of the implement's left side against the abrading wheel's bevelled surface 119.

A stop member 168 is also provided integrally at the left- hand end of the rail unit 140 (on or adjacent rail element 145) for engagement by a left-hand end face of the clamp unit 150 upon the letter's leftwards sliding motion. The arrangement is such that the implement's right-hand side cannot slide leftwards beyond the inner periphery (defined by bore 126) of the abrading wheel's front face 125 and be possibly damaged upon the sliding return motion of the implement, e.g. by the engagement of its right side against the wall of bore 126.

In use the implement is clamped between the two jaws 162, 164 of the tool clamping unit 150 and the latter is attached to the main housing 112 by hooking lip 155 over rail element 145. This is performed with tool clamping unit 150 disposed towards the right-hand side of the abrading wheel's axis so that the implement's edge contacts with the right-hand half of the slightly conical sharpening face 125 of the abrading wheel. The rail unit 140 is pre- positioned in the channels 136 into one of four possible discrete positions - provided for example by detent means or co-operating teeth between the rail unit and the main housing 112 - and clamped in position by the rail clamp 146. These four positions (two of which are outlined in full and phantom lines in Fig 4) provide four different sharpening angles for implement to be sharpened, e.g. 25°, 30° , 35° and 40° .

The abrading wheel's axle 113 is coupled to an electric drill to effect wheel rotation and consequential movement of water (or other cooling fluid) from reservoir 114, via conduit means 120 and its outlet 123, to fall across the front face 125 of the abrading wheel 115 for cooling of that face and/or of an implement in contact therewith. During such wheel rotation, the clamp unit 150 is slid to and fro along the rail element 145, with the clamped implement in contact with the right-hand half of the wheel's sharpening face 125 so as to be sharpened. The arrangement of the stop means - provided in this embodiment by the left-hand side edge of clamp unit 150 and the members 165, 167 and 168 - ensures that whatever the width of the implement, be it wide plane iron or a narrow chisel, the implement will always engage the abrading wheel's front face 125 during such sliding movement (i.e. without the implement's edge running over the inner or outer boundary of the wheel's sharpening face 125) and have the full face of its edge sharpened. It will be noted that these stop means provide for different implement wi *hs automatically upon clamping of the implement in unit 150.

Moreover it will be noted that, due to the small angle (e.g. about 1°) between on the one hand the wheel's sharpening face 125 and the rail element 145 and, on the other hand the vertical plane perpendicular to the wheel axis, the implement's edge can contact only the right-hand portion of the wheel's face 125. Thus, as the clamp unit is slid leftwards more of the implement's edge overlies- but does not contact - the left-hand, relatively rearwardly inclined portion of the wheel's front face 125. Accordingly this left-hand half of the sharpening face 125 effects no unintended (and possibly incorrect) re-sharpening of the implement's edge that has been correctly sharpened by the right-hand half of the slightly conical sharpening face 125.

As explained above, the stop means ensures that however far leftwards the clamp unit 150 is slid, at least some right- hand part of the implement's edge remains in contact with the right-hand relatively forwardly inclined portion of the wheel's sharpening face 125. Accordingly, the implement C always remains in contact with part of the sharpening face and, in particular, the corners of the implement's edge are not rounded off.

It will be appreciated that the laterally reciprocating sliding motion of the clamp unit 150 may be interrupted occasionally and the clamp unit lifted off the rail unit 140 so that the implement's edge can be inspected. It will also be apparent that, as material is ground away from the implement's edge, the lower limb portion 156 of the clamp unit comes into contact with the stop member 154 on main housing 112. This stop member can be positionally adjusted to pre-set the depth of material to be removed from the implement's edge face. For example, this pre-setting stop member 154 can be initially located in a forwardly extended position and with the clamp unit 150 in position with its limb 156 engaged with the extended pre-setting stop member, the implement's edge is brought into contact with the wheel's sharpening face 125 and the bolt 158 is then rotated (by hand wheel 160) to close up the jaws 162, 164 of the clamp unit in tight clamping engagement of the implement's sides thereby to hold the implement fast with the clamp unit 150. The pre-setting stop member is then moved rearwardly to a retracted position to permit grinding of the implement's edge to a depth corresponding to the distance between the extended and retracted positions of the pre-setting stop member 154. In this regard it will be noted that when the stop member is in its retracted position and is re-engaged by the clamp unit's lower limb portion 156, no further material can be ground away from the face of the implement's sharpened edge.

In a modification, the function of the pre-setting stop member 154 can be performed by a screw member threaded in the clamp unit's front wall with its rearward free end engageable with the main housing 112. Inwards rotations of the screw member spaces lower limb portion 156 away from main housing 112 - equivalent to the forwardly extended position of the pre-setting stop member 154 - and outwards rotation of the screw member allows lower limb portion 156 to approach main housing 112 as the implement's edge is progressively sharpened - equivalent to the rearward retracted position of the stop member 154.

The illustrated exemplary abrading device 110 also comprises a deflector plate 122 to deflect fluid emanating from the outlet 123 of the conduit means 120 in a direction towards the said sharpening face 125 of the abrading wheel. This deflector plate 122 is directed towards the recess 127 formed by retainer 117 in the bore 126, the recess 127 being located centrally of the sharpening face 125 on the abrading wheel's axis 116. The arrangement is such as to deflect fluid 124 emanating from outlet 123 of the conduit means into said recess, and such that the coolant fluid can then flow out therefrom over the sharpening face 125 at a rate providing an appropriate cooling effect with little or no splashing. The deflector plate 122 is preferably directed at an angle of 10° to the horizontal so that it may be used as a rest for manually sharpening scissors against the wheel's sharpening face 125. It will be noted that forward portions of the side walls of housing 112 are angled inwards towards the housing's front (see Fig. 7) thereby to permit sharpening of scissor blades almost right up to the pivot pin of the scissors.

The housing 112 is formed internally with a baffle plate 128 directed downwardly from the underside of the conduit means 120 such that the baffle plate's lower free edge lies adjacent said bevelled surface 119. The bevelled surface 119, with perimeter surface 118, tends to throw coolant 114 backwards and outwards to behind the baffle plate 128 and thus reduces the possibility of coolant being thrown outwardly of the housing in a forward direction towards the user. As illustrated in Fig. 4, the baffle plate 128 is positioned to be initially rearwardly of the abrading wheel's sharpening face 125 so as to allow for wear of the latter as the device is repeatedly used.

At opposite sides the deflector plate/scissors guide 122 is provided with deep slots or recesses 162 to receive a removable guide plate. This guide plate is provided with tabs to fit into the slots 162 and locate the guide plate in an upwardly inclined position at 77.5° to the horizontal. When thus positioned and with the tool clamping unit 150 removed, this guide plate can serve as a rest or guide for knives and similar blade-like implements to be sharpened against the abrading wheel's front face 125. When not required, the guide plate 160 can be stored in similar slots or recesses provided at the rear of the main housing 112.

The embodiment of Figs 11 to 15 is substantially similar to that of Figs 4 to 9 and in general like parts have been referenced with the same reference numerals plus '100'. Thus, for example, the abrading device 210 of this embodiment comprises conduit means 220 that, in use of the device, serves to direct upwardly moved cooling fluid from the reservoir 214 (shown in Fig 11A in its open, out-of-use condition) to an outlet 213 of the conduit means, this outlet 213 being located centrally above the abrading wheel 215 and substantially in or adjacent to the "plane" of the wheel's sharpening face 225 of large cone-angle. As shown in Fig 11A, the conduit means 220 is defined by the housing's internal surfaces and a molded, thin-walled component 234 that is fitted in slots 233 in the main housing 212.

The abrading device 210 of Figs 11 to 15 differs from abrading device 110 mainly in the following features.

The underside of the main housing 212 has a pair of laterally spaced bars 211 towards the rear of the housing. The rear of the removable reservoir 214 (for the water or other cooling fluid 14) is provided integrally with a pair of similarly-spaced hooks 201 that can hook over the bars 211 and permit the reservoir 214 to pivot downwards - the position illustrated in Fig 11A - for filling and post-use emptying of the reservoir. The external side faces of the reservoir 214 are molded integrally with a pair of flexible lugs 208 that snap into T-εlot apertures 207 in the sides of the main housing 212 to hold the reservoir 214 in its raised in use condition (see Fig 11B). The front wall of the reservoir 214 has a ramp-shaped portion 204 that protrudes forwardly of the housing 212 and provides a filling 'spout' (Fig 11B) and/or, when lowered (Fig 11A) , a drainage conduit.

The rear end of horizontal shaft 213 (Fig 12) has its bearing 203 located in an eccentrically apertured bearing sheath 202. During initial assembly and/or setting up of the apparatus relative angular movement between the sheath 202 and the bearing 203 sets the angular difference (of e.g. 1^*) between the sharpening face 225 of the abrading wheel 215 and the vertical plane (perpendicular to the shaft axis) containing the rail element 245. The upper, sloping face of housing 212 is provided with a pair of laterally spaced under-cut slots 236 which have wider openings 238 at their forward upper ends. The rail unit 240 is provided at its rear end with a pair of outwardly directed hook-like protuberances 237 that for assembly enter the under-cut slots 236 via openings 238. The rail unit 240 is then pivoted downwardly and forwardly so that the protuberances 237 thereafter lie within the under-cut slots 236 and are retained therein.

The rail unit 240 can be located in any one of a plurality of predetermined positions (e.g. four positions) with respect to the main housing 212, by one or more teeth (not shown) provided on the underside of the rail unit 240 and intergaging with mating teeth 239 on the upper surface of the main housing (see Fig 12). The selectively available positions for the rail unit 240 predetermine the forward projection of the rail element 245 beyond the vertical plane of the main housing's stop member 254 (Fig 11), and thus define the ultimate sharpening angle of an implement which, whilst held in the tool clamping unit 250 (Fig 15) is being sharpened against the wheel's face 225.

The upper surface of the main housing 212 can be marked with indicia 206 - indicative of sharpening angles - located such as to be visible, one at a time, through a window 205 in the rail unit 240 as the latter is moved through its selectible positions.

The rail unit 240 can be held firmly in its selected position by a clamp 246 comprising a cross-bar inter¬ connecting a pair of limbs that are provided adjacent their free ends with inwardly directed stubs 248 having eccentric- camming surfaces. The rail clamp 246 straddles the rail unit 240 and such that the clamp's stubs 248 extend through shaped holes 249 in the sides of the rail unit 240 and into an undercut 247 in the sides of the main housing 212. As the cross-bar of clamp 246 is pivoted rearwardly and downwardly, the eccentric camming surface of each stub 248 acts between the lower surface of the hole 249 and the laterally protruding upper lip of the undercut 247 so as to compress or force together the toothed interengagement of the rail unit 240 and the main housing 212 effected via the teeth 239.

It will be appreciated that the invention is not limited to the particular embodiments described above and that other embodiments and modifications will be readily apparent to those skilled in this art - by a combination of features from the different embodiments described above with reference to the drawings, or otherwise.

In one exemplary modification, the position of the rail unit 140 is infinitely variable rather than in the (four) discrete steps described.

In another exemplary modification, the function of the pre¬ setting stop member 154 can be performed by providing a block on the clamping unit's lower limb, this block being eccentrically mounted on a vertical axis and spring loaded to engage the bottom "rail" of the main housing unit 112. An indicator limb projects from the block through a slot in the front wall of the clamping unit to be aligned with a 'scale' or markings indicating (say) 'COARSE', 'FINE' and 'STOP'. Prior to final full clamping of the implement C in the jaws 162, 164 the clamping unit is pushed towards housing unit's bottom "rail" until the indicator limb points to the desired marking ('COARSE' or 'FINE') and with the implement's edge in contact with the wheel's sharpening face 125, the jaws 162, 164 are then tightened. As the tool clamping unit 150 is pressed against the wheel and slid to and fro across its front face, material is ground away from the implement's edge and, as a result, the tool clamping unit pivots towards the housing unit 112 and the indicator limb moves progressively towards the 'STOP' marking.

In still another exemplary modification (see Fig 15), the bottom 'rail' 254 of the main housing unit 212 is engaged by the tip of a resilient finger 264 that is molded integrally with the tool clamping unit 250 (or 150). The tip of this resilient finger 264 projects rearwardly of a pair of relatively rigid blocks 265 disposed one each side of the finger, the degree of projection being a predetermined small distance, e.g. 1 or 2mm. In use, an implement is clamped in unit 250 (or 150) and the latter is hooked over the upper rail element 245 (or 145) of rail unit 240 (or 140) so as to hang downwardly therefrom with the implement's edge to be sharpened abutting against the abrading wheel's front face 225 (or 125). In this position, the tip of the resilient finger 264 abuts against the bottom 'rail' 254 of main housing unit 212 and, in the absence of any manually applied pressure, spaces said pair of relatively rigid blocks 265 away from this bottom 'rail' 254 by the said predetermined distance. As the implement's edge is sharpened by manually reciprocating and applying rearward pressure upon the clamping unit 250 (or 150), the lateral blocks 265 progressively approach the bottom 'rail' 254 and, when ultimately engaged therewith, substantially prevent abrasive removal of further material from the now- sharpened implement's edge.

In yet another exemplary modification, the clamping unit 150 (or 250) is replaced by a simple guide member that is mounted on the rail element 145 (or 245) for lateral reciprocal movement relative to the abrading wheel. The implement to be sharpened is then held manually against the guide member with its edge against the wheel's front face 125 (or 225). Optionally, the guide member and implement can be then together moved reciprocally with respect to the front face 125 (or 225) as the abrading wheel 115 (or 225) is rotated (e.g. by the motor of an electric drill).

An example of this is illustrated in Fig. 10 where the guide member 350 has a rearwardly extending flange 352 that is provided at its rearward end with a lip 355 of arcuate cross-section whereby the guide member 350 can be releasably hooked over the rail element 145 (or 245) of the rail unit 140 (or 140). The guide member is provided with a part-cylindrical surface 363 that is inclined downwardly and rearwardly towards abrading wheel 115 (or 215) so as to provide a guide surface for a gouge implement that is to have the bevel edge on its convex outer face re-sharpened. It will be appreciated that this arrangement permits the operator to effect arcuate movement of the gouge about its longitudinal axis whilst using the part-cylindrical guide surface 363 as a rest or guiding surface for such movement. Moreover this can be effected manually with the guide member 350 stationary or whilst the guide member 350 is slid to and fro on the rail element 145 (or 245).

It will be appreciated that gouges of smaller radius of curvature can be sharpened whilst being guided against a surface 363 having the same or a larger radius of curvature.

In still yet another exemplary modification, the clamping unit 150 (or 250) is replaced by a simple guide member having an upper hook member by which it is mounted on the rail element 145 (or 245) and is in use held thereon against reciprocal movement. The guide member comprises two laterally spaced, flat resilient limbs depending from the hook member and interconnected at their bottom ends by a shelf-like plate. The edge of a knife to be sharpened is rested lightly upon the plate and pressed against the flat limbs which deflect to permit the side of the knife edge to engage the abrading wheel's front face 125 (or 225) and be sharpened thereby as the knife is reciprocated. The molded plastics material of the guide member (or at least said shelf-like plate) is resistant to the cutting action of the knife blade that rests lightly thereon and does not suffer substantial damage thereby.

A further exemplary modification provides for the deflector plate 22 (or 122 or 222) to have its leading edge terminate fractionally in front of the abrading wheel's front face 125 (or 225) rather than enter the wheel's central recess. Water descending upon the plate 22 (or 122 or 222) from the conduit means' outlet 23 (or 123 or 223) forms a meniscus¬ like water layer between the deflector plate's leading edge and the wheel's front face. This layer serves to wet the wheel's abrading surface 15 (or 115 or 215) without causing splashing and dissipates the abrasion-generated heating effect.

All these and other embodiments and modifications are to be deemed within the scope of the present invention.

Claims

1. An abrading device comprising: a housing to provide a reservoir for cooling fluid; an abrading wheel mounted in the housing for rotation about a substantially horizontal axis; first means to direct cooling fluid from the reservoir upwards upon rotation of the abrading wheel about its axis; and second means to direct the said upwardly directed fluid across a sharpening face of the abrading wheel to effect cooling of an edge tool being sharpened against said face.

2. An abrading device according to Claim 1, wherein the said first means (to direct cooling fluid upwards) may comprise a paddle-wheel structure to move the fluid upwards.

3. An abrading device according to Claim 1, wherein the said first means (to direct cooling fluid upwards) comprises a peripheral surface of the abrading wheel itself to move the fluid upwards by centrifugal action.

4. An abrading device according to any preceding Claim, wherein the said second means (to direct fluid across the wheel's sharpening face) comprises conduit means.

5. An abrading device according to any preceding Claim, comprising a deflector plate to deflect fluid emanating from the second means in a direction towards the said sharpening face of the abrading wheel.

6. An abrading device according to Claim 5, wherein the deflector plate is directed towards a recess in said sharpening face and such as to deflect fluid from the second means into said recess.

7. An abrading device according to Claim 6, wherein the said recess is located centrally of said sharpening face on the abrading wheel's axis.

8. An abrading device according to any preceding Claim, wherein the peripheral surface of the abrading wheel comprises a cylindrical perimeter and a bevelled surface between the cylindrical perimeter and said sharpening face, the latter having a radial extent less than that of the cylindrical perimeter.

9. An abrading device according to Claim 8, wherein a baffle plate in the housing extends to adjacent said bevelled surface so that (at least prior to any wear) the sharpening face projects^'in front of the baffle plate.

10. An abrading device according to any preceding Claim, wherein the said sharpening face is radial.

11. An abrading device according to any one of Claims 1 to 9, wherein the said sharpening face is inclined at a small angle to the perpendicular to the axis of wheel rotation.

12. An abrading device according to CLaim 11, wherein the said small angle is of the order of l".

13. An abrading device according to Claim 11 or Claim 12, wherein the wheel's said sharpening face is provided by the inclined face of a very wide angle conical or frusto- conical abrasive surface.

14. For abrading an implement, an abrading device comprising: an abrading wheel rotatable about a axis, an implement holder, and means for mounting the holder for movement relative to a surface portion of the abrading wheel that is directed at a small angle to the perpendicular to said axis and is in use in contact with the implement.

15. An abrading device according to Claim 14, wherein the said small angle is preferably of the order of 1°.

16. An abrading device according to Claim 14 or Claim 15, wherein the said surface is of frusto-conical form.

17. An abrading device according to any one of Claims 14 to 16, wherein said movement is reciprocal.

18. An abrading device according to any one of Claims 14 to 17, comprising stop means associating the said holder and a support unit for the abrading wheel, said stop means serving to prevent the implement and the abrading wheel coming out of contact during said movement of the holder.

19. An abrading device according to any one of Claims 14 to 18, wherein a reservoir for cooling fluid is provided in a (or the) support unit for the abrading wheel.

20. An abrading device according to Claim 19 and to any one of Claims 1 to 13, wherein said support unit comprises a housing and the abrading device further comprises the said first means and the said second means.

21. An abrading device substantially as herein described with reference to and/or as illustrated in Figures 1 to 3 or Figures 4 to 9 (with or without the modification of Figure 10) or Figures 11 to 15 of the accompanying drawings.