This invention relates to an adapter for a power tool of the general form described and shown in our PCT Application No GB93/00079 (WO93/14903).

In said PCT application there is disclosed an adapter for releasable engagement with a powered grinding tool having a motor adapted to be driven by power supply means, a rotatable shaft drivable, in use, by the motor, and a rotatable grinding wheel to which drive is transmitted in use, from said shaft, the adapter defining a location which, when the adapter is fitted to said tool at a work station thereof and said wheel driven, in use, provides for correct positioning between part of an implement at said location and said grinding wheel for said part to be worked by the wheel.

Such an adapter will hereinbefore be referred to as being of the kind specified.

An object of the invention is to provide an improved adapter of the kind specified.

According to the invention there is provided an adapter of the kind specified comprising a body, and a drill bit receiving dial rotatably mounted on the body, the dial having a multiplicity of openings therein for receiving respective differently sized drill bits to be sharpened at said location, in use, by said grinding wheel, characterised in that the body and dial have respective interengagable parts of quick engagement and

release means for securing the dial on the body and releasing it therefrom.

The invention will now be described, by way of example, with reference to the accompanying drawings, in which:

Figure 1 is a front perspective view of a powered grinding tool with which an adapter of the invention is intended to used, a grinding wheel of the tool not being shown,

Figure 2 is a fragmentary rear perspective view of the grinding tool with alternative shaft adapters,

Figure 3 is an exploded perspective view of part of a different embodiment of the grinding tool, showing a motor and a grinding wheel thereof, •

Figure 4 is an exploded schematic front perspective view of the adapter of the invention,

Figures 5 and 6 are rear and front views respectively of a rear part of the adapter,

Figures 7 and 8 are front and rear views respectively of a front part of the adapter, with a drill bit sharpening dial removed,

Figures 9 and 10 are front and rear views respectively of the drill bit sharpening dial,

Figure 1 1 is a front perspective view of the adapter, and

Figure 12 is a fragmentary view of the adapter showing the sharpening of a drill bit.

As mentioned hereinabove, this invention relates to an adapter for a power tool of the general form described and shown in our PCT Application No GB93/00079 (WO93/14903).

As far as the grinding tool itself is concerned, details of this are shown in Figures 1 to 3. In essence the tool is not significantly different from that described and shown in our above mentioned earlier application, but there are some differences and these will now be described.

Firstly as far as the releasable engagement of an adapter is concerned, each undercut groove at the end of each side of the casing has been replaced by a short generally rectangular slot 10 extending downwardly from the top of each corner projection. Beneath each slot 10, the undercut is effectively filled in to provide a sloping surface 1 1 extending to a lower front surface 12 which may have a pair of spaced upwardly directed pegs 13 adjacent its respective ends.

As will be described, a rear part of each adapter has spaced upper ears 14 to engage in the slots 10 at one face of the casing whilst opposite sides of this rear part of the adapter fit adjacent the facing surfaces 1 1 respectively. The bottom of this rear part of the adapter can fit behind the pegs, or can have a pair of slots into which suitably positioned pegs 13 engage. In this position a resilient catch 15 at a top, central part of

the front face of the casing can snap- fittingly engage with a ledge or the like of an adapter to retain it against vertical upwards sliding movement.

The lower half of the construction of the tool shown in Figure 3 is somewhat different in appearance from that shown in Figures 1 and 2, but it will be appreciated that many variations in shape can be used. Here, the pegs 13a are turned through 90° from pegs 13 and disposed forwardly of the plane containing the surfaces 1 1. Accordingly the rear part of an associated adapter has no lower slots but is retained in the plane of the surfaces 1 1 behind the pegs 13a and by engagement with the catch 15. Figure 3 shows a motor 16 which drives a shaft 17 (Figure 1) on which is carried a grinding wheel 18, which has an annular chamfered portion 19 between a central planar, circular front portion 20 and its cylindrical periphery 21. However, as will be described different grinding wheels can be used as appropriate to any particular adapter. Moreover as described herein a solid grinding wheel can be replaced by one in the form of a sanding wheel made up of a plastics disc on which is abrasive material or the like.

As shown in Figure 2, a further shaft 22, driven, in use, by the motor 16 can project from the face of the casing opposite to that front which the shaft 16 projects. This can be provided with a dog 23 and belt arrangement to provide a flexible drive or can be adapted for any other grinding wheel arrangement. It will be noted that at this surface side catches 24 are used to secure an adapter rather than the pegs 13, but the means of attachment can be varied as required.

Whilst Figures 1 to 3 show the grinding tool with which an adapter of the invention is intended to be engaged, an embodiment of the adapter

is shown in the remaining Figures. The adapter 25 is for sharpening drill bits and is removably fitted at the working face of the powered grinding tool as will be described.

A body of the adapter is made up of two parts, both of plastics material, namely a rear part 26, which is fitted to the grinding tool, and a front part 27 which is adjustably slidably carried on the rear part.

The rear part of the adapter body has a rear wall 28 with a central slot 29 extending upwardly therein from the bottom edge thereof to receive, in use, the shaft 17, with the grinding wheel on the shaft being received within the rear part 26 forwardly of its wall 28 and enclosed by its respective side walls 30a, 30b and top wall 31. A bottom wall 32 of the part 26 is cut away adjacent the rear wall 28 to accommodate the grinding wheel.

The outside of the rear wall defines respective sloping side surfaces 33, 34 and ears 14 at its opposite sides, so that the part 26 can be slidingly fitted to the grinding tool with the surfaces 33, 34 engaging tool surfaces 1 1 and the respective ears being received in the slots 10. A central ledge 35 on the rear wall is engaged, in use, by the catch 15 to retain the adapter in place. On the inside of the rear wall projections can be provided to engage behind the pegs 13 respectively.

Along the respective outsides of its side walls 30a, 30b near the lower edges thereof, the part 26 has respective guide rails 37, 38. Depending from the bottom wall 32 of the part 26 are first and second parallel, spaced flanges 39, 40 respectively, both being normal to and extending between the side walls 29, 30. The second flange 40 is behind the first

flange and has a central portion extending further downwardly than its opposite end portions and also than the first flange.

At the centre of the first flange 39 is secured a square nut 41. Although the nut can be secured in a number of ways, it is shown held in a metallic casing 42, which itself is fixed in a square opening 43 extending upwardly from the bottom of the first flange. Opposite arms 44 of the casing are turned outwardly tightly over the front side edges of the opening to hold the casing and nut in place. The rear of the casing has a circular hole aligned with the screw-threaded hole 45 through the nut. Extending forwardly from the inside of the rear wall 28, adjacent opposite upper corners thereof are respective cylindrical tubes 46, 47.

The front part 27 of the adapter is larger than the rear part 26 so as to be slidably engagable over part of it, in use. The part 27 has an upwardly, rearwardly sloping front wall 48 with a central circular recess 49 therein, having a frustoconical side surface 50. The centre of the base of the recess is itself formed with a further circular recess 51 having a central circular hole 52. Extending through this hole 52 is a headed fixing screw 53, which serves to secure a plastics material circular member 54 in recess 51. The member 54, which has an upstanding peripheral annular flange 55, fills the recess 51 , and acts as a dust seal. It can also in effect act as a location and bearing member as will be explained.

The rear end of the screw has a washer and nut secured thereon, whilst its front end has a first cylindrical collar 56 against the member 54 and a second collar 57, formed as a circular head, spaced from the collar 56 by an annular groove 58.

Depending from the centre of a bottom wall 59 of the front part 57 is a housing part 60 with a circular hole 61 therethrough. Extending through the hole 61 is an adjustment screw formed by a knurled knob 62 and a shaft 63. One end of the shaft 63 is threaded and of reduced diameter, to receive the knob 62 tightly thereon against relative rotation, whilst its other end is screw-threaded to engage with the screw-thread of nut 41 , the shaft having a middle unthreaded portion. Axial movement of the adjustment screw is effectively prevented by a circlip 64 received in a groove on the unthreaded part of the shaft and disposed against or adjacent a rear surface of the housing part. When the screw-threaded part of the shaft is engaged with the nut 41 , rotation of the knob causes the front part 27 to move towards or away from the rear part 26. A compression spring 65 is received on the shaft to bear between the nut 41 and casing 42, so as to be compressed or further compressed as the front part is adjustably moved towards the rear part 26, and thus bias the two parts apart.

At a position on a centre line through the front part extending through the holes 52 and 61 , and at the upper side of the member 54, the base of the recess 49 has an opening 66 therethrough. The opening has straight sides parallel to said centre line and equi-spaced on respective opposite sides thereof, and a curved lower side. The opening continues at its upper end into the frustoconical side surface 50 of recess 49, where there is formed a housing for a turret adjustment lock button 67.

The housing has a pair of straight, parallel grooves 68 in its opposite internal surfaces respectively, and at their respective front ends the grooves open laterally to provide respective bearing surfaces for cylindrical pivotal pegs 69, 70 respectively at the front end of the button

67. The rear of the housing has a lower cross-member 71 , whilst the upper, inner housing surface has a central recess 72 along its whole length.

The button 67 is assembled in its housing by its pegs 69, 70 being slid along the opposite respective grooves 68 and snapped onto their respective bearing surfaces. In this state, the button has its rear end resting on the cross-member 71. However centrally on its upper surface, the button has a peg 73, and a small compression spring 74 has its one end fitted on the peg 73, its opposite end being received in the recess 72, with the spring under compression and biassing the button down onto cross-member 71. On its lower surface, adjacent the cross-member, the button has a central, generally triangular-section projection 75, the apex of which is cut away to provide an arcuate section recess 76 in the centre line of the front part 27.

Integrally formed on the interior surface of the front wall 48 of front part 27, disposed symmetrically at respective opposite sides of the centre line of part 27 are location members 49, 50. As will be described, these members 49, 50 are aligned, in use, with the tubes 46, 47 respectively when the front and rear parts of the adapter fit together. Respective compression springs 77, 78 have one end fitted on a location member and an opposite end received in a tube, so as to bias the two adapter parts apart when they are held together by the shaft 63 engaged with the nut 41.

Finally, to allow for sliding adjustment of the front and rear adapter parts towards or away from one another the respective interior surfaces of side walls 79, 80 have respective channels 81 , 82 to receive the guide rails

37, 38 of the rear part 26, so that the front part can slide relative thereto. Additionally a central groove 83 on the inner upper surface of the top wall 84 of part 27 is slidably engaged with an upstanding guide rib 85 on an outer surface of a top wheel 86 of the rear part. The bottom wall 59 of front part 27 is cut away inwardly from its rear surface to provide an opening generally aligned, in use, with the part of wall 32 of part 26 cut away, to accommodate the grinding wheel.

Thus on assembly the two parts are slidably engaged together with the guide rails 37, 38 engaging in channels 81 , 82 and with guide rib 85 received in groove 83, the springs 77, 78 being compressed between the location members 49, 50 and the ends of the tubes 46, 47. The threaded free end part of shaft 63 is engaged with the nut 41 and by rotating the knob 62, the front part of the adapter is moved adjustably towards or away from the rear part received on the powered grinding tool, such movement towards the rear part being resisted by the springs 77, 78 and also by the spring 65. Movement towards the rear part could, in use, be limited by the engagement of the second flange 40 with the rearwardly facing surface of the bottom wall at said opening and/or by engagement of the end of the shaft 63 against flange 40. However as will be described a setting stop is normally provided.

The adjustment described in primarily intended to be used to compensate for wear of the grinding wheel, in use, so that for correct drill bit sharpening the front part needs to be moved nearer the grinding wheel, i.e. towards the rear part of the adapter. Means can be provided on the front part to provide a warning when sufficient adjustment has been made. This could be by way of a carbide setting stop peg 86 of the rear of the base of recess 29 of part 27 contacting the grinding

wheel, and the warning could be of any suitable form, i.e. an audible warning. This can denote that the adjustment movement is excessive, i.e. that the knob can be backed-off, or alternatively that adjustment is just sufficient for correct grinding.

As mentioned, the adapter is for sharpening drill bits, and such sharpening is carried out by means of a plastics material turret or drill bit receiving dial 87 rotatably mounted on the member 54 by means of fixing screw 53, in a quickly releasable manner to be described.

The turret is of generally cylindrical external form having an annular, radially directed flange 88 dividing the outer periphery of the turret into a front, knurled surface 89 gripped, in use, to move the turret angularly, and a rear indexed surface 90 for positioning the turret for the correct sharpening of a particular size of drill bit. The diameter of the flange 88 corresponds substantially to a maximum diameter of recess 49, thereby filling the recess when the turret is in place on screw 53. The diameter of the cylindrical body of the turret corresponds to the diameter of the base of recess 49.

The rear of the turret has its interior formed with an upstanding annular projection 91 centred on an axis 'O' which is common to the cylindrical body of the turret and also flange 88. A further annular projection of a somewhat smaller diameter than projection 91 is also centred on axis 'O', but this is interrupted to provide annular sections 92. The diameters of these projections respectively and the difference between such diameters is such that the flange 55 is fairly closely received between the projection 91 and sections 92 when the turret is mounted on the screw

53, the dust seal moulding 54 thus also possibly acting as a location and bearing member for a turret.

The front face of the turret has a multiplicity of reducing diameter, circular section holes 93 therein, each hole extending through the whole thickness of the turret body. The differently sized holes are to receive, as snug but not tight fits, respective corresponding differently sized drill bits respectively to be sharpened using the adapter fitted to the powered grinding tool. Each hole is formed at its end remote from the turret front face with a pair of shaped opposing projections 94 positioned and shaped to engage, in use, with a drill bit flute when a drill bit is located in said hole. This prevents drill bit rotation. Alternatively location means to prevent drill rotation could be formed on the adapter part 27.

The surface 90 has a multiplicity of shallow ribs 95 therearound, each rib being generally of arcuate cross-sectional shape and normal to flange 88. Each rib is positioned to correspond to the location of the centre of one hole of the hole 93, and when a hole in the turret front face is positioned over the opening 66, so that the end of a drill bit located in the hole is engaged by the grinding wheel, the rib 95 associated with said hole is received in the recess 76 of the projection 75 of the turret adjustment lock button. Thus the turret is locked in its selected position due to the spring 74 forcing the button down so that the turret rib is held in recess 76. The strength of the spring 74 is such that when it is wished to align a different hole 93 with opening 66, to sharpen a different size of drill bit, it is merely necessary to grip the knurled surface 89 of the turret and to turn the turret angularly with some degree of force. This causes the engaged rib 95 to move and lift the button 67 against its sprirg 74. As the next rib 95 in the direction of turret rotation reaches the - ;oping side

surface of projection 75 it forces it upwards against spring 74 before being received in the recess 76 as the button snaps back downwardly. Accordingly the turret is moved angularly until the desired hole 93 is aligned with opening 66, with the rib 95 of each intervening hole lifting the button as it enters and then leaves the recess 76.

To cater for Imperial and Metric sizes of drill bit, and also to cater for standard high speed twist drill bits and split-point drill bits, more than one turret can be provided, each with different sizes of holes for the different drill bit sizes and types mentioned above. Each turret indicates the drill sizes for the holes 93 and also the type of drill bit for which the turret is suitable. Accordingly the headed end of the screw 53 and each of such turrets have respective interengagable parts of quick engagement and release means, so that a turret can easily and quickly be released from the front part of the adapter and an alternative replacement turret easily and quickly be fitted thereto.

The centre of the front face of the turret has a rectangular recess 96 extending rearwards to a base 97 axially inwards of the extremities of projection 91. The base has a circular hole 98 therethrough, the centre of the hole being the axis of the turret, about which it moves angularly, in use. The hole is sized to receive therethrough the collar 57, forming the head, and to accommodate the collar 56. Slidable along the base 97 is a plastics material rack 99, held against upwards movement beneath two projections 100, 101 respectively at opposite sides of the recess 96. The rack has a central keyhole slot 102 therethrough arranged longitudinally of the rack. In a first extreme position of the rack, the end of the rack nearest the narrower part of the keyhole slot abuts a closed

end of the recess 96, and the large circular part of the keyhole slot is aligned with and exactly matches the hole 98 in the base.

The rack has respective gear teeth 103a, 103b on its upper surface at respective opposite sides of the large circular part of the keyhole slot, the gear teeth extending to the end of the rack nearer said large circular part. At their other ends, the gear teeth terminate in projections 104, 105 respectively which abut the projections 100, 101 respectively when the rack is in its first extreme position.

At the end of the recess remote from the projections 100, 101 , the recess has its respective opposite sides recessed to form upwardly open bearing surfaces for respective cylindrical pivot pegs 106, 107 of a manually operable lever 108, preferably of plastics material. The pegs are integrally formed on respective opposite side arms at the rear of the lever. The majority of each side arm is formed as a pinion having gear teeth 109 in mesh with the gear teeth 102, 103 respectively on the rack. The end of the recess 96 adjacent the lever mounting is cut away to allow the rack to slide therethrough as the lever is moved from its upright position, when the rack is in its first extreme position, to lie flat, and flush within the recess, when the rack is in its second extreme position. In its second extreme position, the majority of the large circular part of the keyhole slot has moved out of alignment with the hole 98, so that the narrower part of slot 102 is now aligned with it.

The distance between the collars 56 and 57 corresponds to the thickness of the rack, so that in use the turret can be positioned in recess 49 as described, to be engaged on member 54. This positioning is with the lever 108 upright, and thus with the large circular part of the keyhole

slot 102 aligned over the hole 98. Accordingly the collar 57 passes through the aligned holes to lie just outward of the rack surface which carries the gear teeth, whilst the groove 58 is placed in the plane of the rack and the collar 56 is received in the hole 98. One of the ribs 95 is arranged to be received in recess 76 by angular manipulation of the turret as it is engaged on fixing screw 53.

Once engaged as described, the lever 108, which has a ribbed inner surface can be gripped and pivoted downwardly into the recess 96. This causes the gear teeth 109 on the lever, and in mesh with the gear teeth 102, 103 on the rack, to slide the rack from its first to its second extreme position. Accordingly the necked part of the screw 53 formed by the groove 58 between collars 56 and 57 is received in the narrower part of the keyhole slot, so that the turret is thereby locked onto the screw 53, preventing axial lifting of the turret, but allowing angular indexing movement for particular drill sizes, as described. This locking is because the collar 57 cannot now pass through the narrower part of the keyhole slot.

When a different turret, as referred to, is to be fitted to the screw 53, the lever 108 is lifted manually from its flat position at the top of the recess, this moving the rack so that the large circular part of the keyhole slot is against around the 'necked ^* screw part. Thus the turret can now easily be lifted off the screw and replaced by said different turret which is releasably locked in place in the same manner as described by the use of the manually operable lever, associated rack and fixing screw configuration.

According in the embodiment described one form of a quick engagement and release arrangement for selectively engaging and replacing a turret on an adapter of the invention is disclosed, respective parts thereof being on the body (the fixing screw) and each turret. The quick engagement and release means could of course be of an alternative form, for example by the use of a sliding or rotatable manually operating member to effect locking to the shaft for the turret. Although the provision of the hole 98 in base 97 of recess 96 is convenient to locate the collar 56, the recess could instead be a slot, with the base 97 being omitted. The initial location of the dial on the body might be somewhat less precise, with the collar 56 being disposed merely below the rack instead of in a correspondingly sized opening. However the reception of collar 58 in the large circular part of the keyhole slot and the engagement of the dial on the member 54, serves to locate the dial on the body. It will be appreciated that the collar 56 could be omitted, the screw 53 merely having a peck and an enlarged head, the head being unable to pass through the narrower part of the keyhole slot. The opening in the slidable member, such as a rack, need not be of keyhole shape, provided it allows passage of a member, i.e. a head, in one relative position and prevents it in a second relative position. The head and neck can of course be other than circular. The means for fitting and releasing a turret could merely be by way of part of the manually operable member (of whatever form) tightly gripping the shaft for mounting the turret,with the shaft being unheaded.

In whatever form however, the means enable the turrets to be released and engaged without the need for tools, such as a spanner, thereby providing an easy and quick turret change operation when required.

In use, engagement of the adapter onto the grinding tool locates the grinding wheel directly behind the front wall 48 of the adapter part 27, and a drill bit 110 placed in the hole 93 immediately below the button 67 has its end extending through opening 66, with the projections 94 engaging the drill bit flutes, to engage the grinding wheel as it rotates, in use. The drill bit is loosely held in its hole 93 to allow it to be twisted, and can be sharpened in both of its two possible orientations in the hole by turning it through 180° so that each flute engages a different projection respectively. The wear adjustment knob 62 should be wound back before the adapter is fitted to the grinding tool to ensure clearance from the grinding wheel. Thereafter the knob can be turned until the carbide stop can be heard just touching the grinding wheel, the knob then being slightly backed off.

In an alternative arrangement allowing for quick engagement and release of the turret, there could be respective interengagable means on the body (i.e. screw 53) and the turret, allowing a snap-fit connection by pushing the turret onto the body. The connection could be released by operation of a lever or button on one of the members.