GB2302295A

GB2302295A - Reamer

Info

Publication number: GB2302295A
Application number: GB9612120A
Authority: GB
Inventors: Douglas Millington
Original assignee: Cogsdill Nuneaton Ltd
Current assignee: Cogsdill Nuneaton Ltd
Priority date: 1995-06-16
Filing date: 1996-06-10
Publication date: 1997-01-15
Anticipated expiration: 2016-06-10
Also published as: GB9512307D0; GB2302295B; GB9612120D0

Abstract

A replaceable blade 1 for a reamer 2, comprises a solid, elongate body 3 having front and rear faces 4, 5 and parallel major edges 6, 7. The rear face is adapted to seat against a support surface of the reamer 2, whilst the front face 4 is adapted to be engaged by a screw clamping member 9 to urge the blade 1 into tight seating engagement against the support surface. The front face 4 is provided, intermediate its ends 10, 11, with at least one relatively shallow indentation or recess providing an abutment surface 13 that is non-parallel with respect to the major edges 6, 7, which abutment surface 13, or non-parallel portion of that surface, being engageable by the clamping member 9.

Description

REAMER This invention relates to a replaceable and elongate blade of tungsten carbide, for fitting into a reamer, and to a reamer provided with such a blade.

One known reamer is described for example in GB 2110129, and has proved successful in practice. It is possible however that manufacturing costs can be reduced and a reamer of improved strength provided, if certain changes in design are effected. Furthermore, known constructions of replaceable blade have been provided with a groove on one surface, from end to end, the intention being that the clamping means exhibits an improved clamping grip by positively engaging the groove rather than frictionally engaging a planar surface for example. However, grooving results in the creation, at the end of the blade, of a gap between the blade and the reamer, in which gap swarf disadvantageously accumulates.

According to a first aspect of the invention there is provided a replaceable blade for a reamer, comprising a solid, elongate body having front and rear faces and parallel major edges, the rear face being adapted to seat against a support surface of the reamer, and the front face being adapted to be engaged by a screw clamping member to urge the blade into tight seating engagement against the support surface, with the front face provided, intermediate its ends, with at least one relatively shallow indentation or recess providing an abutment surface that is non-parallel with respect to the major edges, the abutment surface or non-parallel portion of that surface being engageable by the clamping member.

According to a second aspect of the invention there is provided a reamer incorporating a blade in accordance with the first aspect1 with at least one screw clamping member engageable with the blade and having a thread so handed that, upon tightening that clamping member the blade is urged axially of the reamer against a datum support.

Thus, with the blade and reamer in accordance with the first and second aspects tightening of a left or right hand threaded clamping member automatically and positively urges the blade against a stop constituting a datum support, thereby minimising the skill required to assemble a reamer in accordance with the second aspect, and hence, accurate axial positioning of the blade within the reamer, and resultant accurate reaming, is guaranteed, as accurate blade positioning relative to the two conventionally provided guide or burnishing pads is essential in view of users requirements to operate at ever increasing rotational speeds.

The blade body may be of carbide, diamond cermet, or high speed steel.

Although the non-parallel abutment surface could be a curve, or a portion thereof, e.g. constituted by a circular, oval etc., hole, slot, indentation or recess, preferably the abutment surface is linear, in which case the abutment surface is wholly or partially inclined with respect to the major edges.

With the abutment surface in the form of a curve, the axis of rotation of the clamping member (a headed screw or stud) needs to be slightly offset in order to obtain the urge or "pull" on the blade in the desired seating direction.

In detail, the indentation or recess may be provided by a shallow groove e.g. 'V' profile - with an obtuse inclined angle, so that, with a blade having two cutting edges, one side of the groove constituting the abutment surface engageable by the screw clamping member for use of one cutting edge, and the other side, after rotation of the blade through 1800, for use of the other cutting edge. Advantageously, the sides of the groove are flat or planar.

A single indentation or recess e.g. a 'V'-groove may be provided, extending the full major axis length of the blade.

Alternatively, a 'V'-groove may stop short of the ends of the blade, so that the ends are uninterrupted. Alternatively two grooves, on a common or non-common inclined axis may be provided. Again, each of the two grooves may run out at an adjacent end surface, or may stop short of an adjacent end surface.

If the blade is intended to be reversible, with the blade of regular or rhomboid profile, then in addition to the indentation(s) or recess(es) providing the abutment surface(s) being formed only in the front face, a similar indentation(s) or recess(es) providing abutment surface(s) may be formed in the rear face as, upon reversal to present a fresh cutting edge, the rear face becomes the front face.

Apart from the indentation(s) or recess(es), the front and rear faces of the blade are preferably planar subject to any cutting rake and also are preferably parallel.

The front and rear faces may be joined by converging faces, which may have a first face portion at one converging angle and a second face portion at a different converging angle.

If the blade body is produced by sintering, the or each indentation or recess is preferably formed during sintering of the carbide of the blade, although machining or grinding is possible.

If, as is conveniently the case, the screw clamping member is constituted by the frusto-conical head of a screw the appropriate selection of left or right hand thread results in a component of force on the blade to ensure engagement of an end of the blade with the conventionally provided stop of the reamer, with such a head advantageously engaging a flat or planar side of a "V"-grooved blade. In practice, depending on the major axis length of the blade, a single clamping member or multiple clamping members would normally be employed.

It follows that, if the clamping means is constituted by one (or two) screw clamping member(s) having an enlarged head(s) adapted to engage the front face of the blade, the reamer needs to be provided with one (or two parallel) and tapped hole(s), with preferably the or both screw clamping member(s) of left or right hand thread so that upon tightening, the blade is inevitably urged against the datum support. The latter may be provided by a pin or other stop surface, whilst the enlarged heads are recessed to accommodate an industry-standard driver.

Compared for instance with GB 2110129, the reamer in accordance with the second aspect of the present invention is of stronger cross-section, in that it avoids the need for a clamping plate and consequently avoids the need for substantial machining of the reamer to provide space to accommodate the clamping plate with attendant weakening of the reamer by such metal removal. As is conventional, the reamer in accordance with the second aspect of the invention is provided with a pair of tapped holes to accommodate a pair of adjusting screws adapted to engage an inner converging face of the blade to set the extent of radial projection of the blade.

Furthermore, with the blade in accordance with the first aspect, and the reamer in accordance with the second aspect, radially outward blade adjustment results in progressively increased clamping forces. Also conventionally, the reamer is provided with two circumferentially spaced apart guide or burnishing pads.

Examples of blades in accordance with the first aspect and parts of reamers in accordance with the second aspect are shown in the accompanying drawings, in which: Figures 1 and 2 show first embodiments with a full length 'V'-groove in the front face only; Figures 3 and 4 correspond to Figures 1 and 2 but show a rhomboid profile blade with a 'V'-groove in both the front and rear faces; Figures 5 and 6 also correspond to Figures 1 and 2 but show a restricted length 'V'-groove; Figures 7, 8 and 9 show respectively a blade with a curved abutment surface, and an offset screw clamping member; and Figure 10 is a view of a reamer in accordance with the second aspect, provided with a blade in accordance with the first aspect.

In all figures, like reference numerals are used for like component parts.

A replaceable blade 1 e.g. of tungsten carbide, for a reamer 2, comprising a solid, elongate body 3 having front and rear faces 4, 5 and parallel major edges 6, 7. The rear face 5 is adapted to seat against a support surface 8 of the reamer 2, whilst the front face 4 is adapted to be engaged by a screw clamping member 9 to urge the blade 1 into tight seating engagement against the support surface 8. The front face 4 is provided, intermediate its ends 10, 11, with at least one relatively shallow indentation or recess 12 providing an abutment surface 13 that is non-parallel with respect to the major edges 6, 7, which abutment surface 13, or non-parallel portion of that surface, being engageable by the clamping member 9.

Conventionally, the reamer is provided with a stop 14 constituting a datum support, so that either a left or right hand threaded screw clamping member 9 will ensure that, upon tightening, the screw clamping member 9 itself positively urges the blade 1 against the stop 14 and hence into its correct seating position on the reamer 2, thereby minimising the skill required to assemble a reamer in accordance with the second aspect, and hence, accurate axial positioning of the blade within the reamer, and resultant accurate reaming, is guaranteed, as accurate blade positioning relative to the two conventionally provided guide or burnishing pads 15 is essential in view of users requirements to operate at ever increasing rotational speeds.

In the embodiments of Figures 1 to 6, the abutment surface 13 is linear, in which case the abutment surface is wholly or partially inclined with respect to the major edges 6, 7.

In the embodiments of Figures 7 to 9, the abutment surface 13 is in the form of a curve provided by a generally oval indentation 12, and in this case the axis of rotation 16 of the screw clamping member 9 which has an enlarged frustoconical head 17 needs to be slightly offset from the axis 18 of the indentation 12 in order to obtain the urge or "pull" on the blade 1 in the desired seating direction by the underside 19 of the head 17 engaging the curved abutment surface 13 of the oval indentation 12.

As indicated in Figures 1 to 4, the indentations or recess 12 having linear abutment surfaces are provided by shallow groove 20 so that the indentations have a 'V' profile - with an obtuse inclined angle. Thus, with a blade 1 having two cutting edges 6, 7, one side 21 of the groove 20 constituting the abutment surface 13 engageable by the underside 19 of the head 17 of the screw clamping member 9 for use of one cutting edge 6, and the other side 22, after rotation of the blade through 1800, for use of the other cutting edge 7. The sides 21, 22 of the groove 20 are flat or planar.

In the embodiments of Figures 1 to 4, a single indentation or recess e.g. a 'V'-groove, extends from end 10 to end 11 the full major axis length of the blade.

In the embodiments of Figures 5 and 6, the 'V'-groove 20 stops short of the ends 10, 11 of the blade 1, so that the ends 10, 11 are uninterrupted.

As indicated in Figure 4, if the blade 1 is intended to be reversible, with the blade of regular or rhomboid profile, then in addition to the indentation(s) or recess(es) 12 providing the abutment surface(s) 13 being formed only in the front face 4, a similar indentation(s) or recess(es) 12 providing abutment surface(s) 13 may be formed in the rear face 5 as, upon reversal to present a fresh cutting edge, the rear face 5 becomes the front face 4.

Apart from the indentation(s) or recess(es), the front and rear faces 4, 5 of the blade 1 are planar subject to any cutting rake and also are preferably parallel.

As illustrated in Figures 2 and 6, the front and rear faces may be joined by converging faces 23 of the major edges 6,7, which may have a first face portion 24 at one converging angle and a second face portion 25 at a different converging angle.

In practice, depending on the major axis length of the blade 1, a single clamping member 9 or multiple clamping members 9 would normally be employed.

It follows that, if the clamping means is constituted by one (or two) screw clamping member(s) having an enlarged head(s) adapted to engage the front face of the blade, the reamer needs to be provided with one (or two parallel) and tapped hole(s), with preferably the or both screw clamping member(s) of left or right hand thread so that upon tightening, the blade is inevitably urged against the datum support stop 14. The enlarged heads 17 are recessed to accommodate an industry-standard driver.

Claims

1. A replaceable blade for a reamer, comprising a solid, elongate body having front and rear faces and parallel major edges the rear face being adapted to seat against a support surface of the reamer, and the front face being adapted to be engaged by a screw clamping member to urge the blade into tight seating engagement against the support surface, with the front face provided, intermediate its ends, with at least one relatively shallow indentation or recess providing an abutment surface that is non-parallel with respect to the major edges, the abutment surface or nonparallel portion of that surface being engageable by the clamping member.

2. A blade as claimed in Claim 1, wherein the blade body is of carbide, diamond cermet, or high speed steel.

3. A blade as claimed in Claim 1 or Claim 2, wherein the non-parallel abutment surface is a curve, or a portion thereof.

4. A blade as claimed in Claim 3, wherein the axis of rotation of the clamping member is slightly offset

5. A blade as claimed in Claim 1 or Claim 2, wherein the non-parallel abutment surface is linear and is wholly or partially inclined with respect to the major edges.

6. A blade is claimed in Claim 5, wherein the indentation or recess is provided by a shallow groove.

7. A blade as claimed in Claim 6, wherein the groove is of 'V' profile - with an obtuse inclined angle.

8. A blade as claimed in Claim 6 or Claim 7, wherein the sides of the groove are flat or planar.

9. A blade as claimed in any one of Claims 5 to 8, wherein a single indentation or recess is provided, extending the full major axis length of the blade.

10. A blade as claimed in any one of Claims 5 to 8, wherein the indentation or recess stops short of the ends of the blade.

11. A blade as claimed in any one of Claims 5 to 8, wherein two grooves, on a common or non-common inclined axis are provided.

12. A blade as claimed in Claim 11, wherein each of the two grooves runs out at an adjacent end surface.

13. A blade as claimed in Claim 11, wherein each of the two grooves stops short of an adjacent end surface.

14. A blade as claimed in any preceding claim, in a reversible blade format, wherein, in addition to the indentation(s) or recess(es) providing the abutment surface(s) being formed only in the front face, a similar indentation(s) or recess(es) providing abutment surface(s) is formed in the rear face as, upon reversal to present a fresh cutting edge, the rear face becomes the front face.

15. A blade as claimed in any preceding claim, wherein, apart from the indentation(s) or recess(es), the front and rear faces of the blade are planar subject to any cutting rake and also are preferably parallel.

16. A blade as claimed in any preceding claim wherein the front and rear faces are joined by converging faces.

17. A blade as claimed in Claim 16, wherein the converging faces have a first face portion at one converging angle and a second face portion at a different converging angle.

18. A blade as claimed in any preceding claim, formed by sintering, wherein the indentation(s) or recess(es) are formed during sintering.

19. A blade as claimed in any one of Claims 1 to 17, wherein the indentation(s) or recess(es) are formed by machining or grinding.

20. A blade substantially as hereinbefore described with reference to Figures 1 and 2 of the accompanying drawings.

21. A blade substantially as hereinbefore described with reference to Figures 3 and 4 of the accompanying drawings.

22. A blade substantially as hereinbefore described with reference to Figure 5 of the accompanying drawings.

23. A blade substantially as hereinbefore described with reference to Figure 6 of the accompanying drawings.

24. A blade substantially as hereinbefore described with reference to Figures 7 to 9 of the accompanying drawings.

25. A reamer incorporating a blade in accordance with any preceding claim, with at least one screw clamping member engageable with the blade and having a thread so handed that, upon tightening that clamping member the blade is urged axially of the reamer against a datum support.

26. A reamer as claimed in Claim 25, wherein depending on the major axis length of the blade, a single clamping member or multiple clamping members are employed.

27. A reamer as claimed in Claim 25 or Claim 26, wherein ,the or each clamping member is a screw with an enlarged head.

28. A reamer as claimed in Claim 27, wherein the or each head is frusto-conical.

29. A reamer as claimed in any one of Claims 25 to 28, provided with at least one tapped hole to receive a screw clamping member, of left or right hand thread so that upon tightening, the blade is inevitably urged against a datum support.

30. A reamer as claimed in Claim 29, wherein the datum support is provided by a pin or other stop surface.

31. A reamer as claimed in Claim 27 and any claim appendant thereto, wherein the enlarged head of the or each screw clamping member is recessed to accommodate an industrystandard driver.

32. A reamer substantially as hereinbefore described with reference to Figure 10 of the accompanying drawings.