Reamer with angled blade and full length clamp

A reamer comprises a single, adjustable, elongate carbide blade clamped in position in an axial slot in the reamer periphery by means of a clamping plate, with the slot having a positive rake blade supporting fade so that the blade is adjustable along a line parallel to a tangent to the reamer periphery.

BACKGROUND OF THE INVENTION 
This invention relates to a reamer of the kind comprising a single carbide 
blade--in contrast to a multiple number of such blades--which blade is 
adjustable so that the projection of the blade from the reamer periphery 
may be accurately set and also comprising at least one carbide burnishing 
pad at a location on the reamer periphery spaced from the blade. Such 
reamers, in providing adjustable cutting edge, ensure that the tolerance 
of the hole being reamed is maintained even on long production runs. 
In a known embodiment of reamer, the blade is secured by a clamping plate 
which extends, for reasons of reamer geometry, over only part of the 
length of the blade, which does not provide a completely satisfactory 
clamping action for all working conditions. Furthermore, in known reamers, 
the blade is set radially with respect to the axis of rotation i.e. the 
blade has a zero rake, but in very many circumstances it is advantageous 
or even essential to give the leading face of the blade a positive cutting 
angle and this can only be effected by an awkward grinding operation on 
the front face of the blade. 
Illustrative of prior art relative to reamers of the type of the present 
invention are disclosed in U.S. Pat. Nos. 786,990; 955,696; 991,283; 
1,320,482; 1,702,485; 2,150,286; 2,155,595; 2,775,821; 3,125,799; 
3,656,859; 3,880,545; 3,490,315; 4,076,445; and 3,125,342. 
SUMMARY OF THE INVENTION 
According to the present invention, there is provided a reamer comprising a 
single, adjustable, elongate, carbide blade clamped in position in an 
axial slot in the reamer periphery by means of a clamping plate, with the 
slot having a positive rake blade supporting face so that the blade is 
adjustable along a line parallel to a tangent to the reamer periphery and 
along a plane preferably disposed in a non-parallel relationship with a 
radial plane extending through the longitudinal axis of the reamer and 
through the outer edge of the cutting face of the blade. Thus, the blade 
is adjustable along a first plane that is not parallel to a second plane 
extending through the longitudinal axis and disposed at a positive angle 
relative to the above-mentioned radial plane. 
Thus, the reamer in accordance with the invention, by virtue of the angled 
blade supporting face of the slot, automatically sets the blade with a 
positive rake, the blade normally having a trapezoidal cross-section with 
a longer, front cutting face and a shorter rear back face, the latter 
abutting the blade supporting face, and avoids blade grinding operations 
to give the blade a positive cutting face. 
Preferably, the clamping plate takes the form of a single element although 
two or more shorter length elements may be provided. With either 
arrangement the blade is preferably clamped along the majority of its 
length. With the clamping plate(s) supporting most, if not all, of the 
length of the blade, there is provided an improved clamping effect over 
known proposals. 
In detail, the blade supporting face may be positively raked at 10.degree.. 
It will be appreciated that to make the reamer more universally usable, a 
simple grinding step on the leading face of the blade may be effected to 
give the particular angle e.g. 6.degree. or even 0.degree. required by the 
user for a particular reaming operation. The blade may be adjustable as to 
its projection beyond the reamer periphery by a pair of screws spaced 
apart along the reamer, one screw to bear at or adjacent each end of the 
blade. The or each clamping plate may also be secured by at least one 
screw. In one embodiment two spaced apart screws are provided, with the 
clamping plate provided with two suitably tapped holes. Conveniently, the 
clamping plate(s) clamps by a wedging action abutting the front face of 
the blade and an opposite, preferably angled, face of the slot.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
The invention will now be described in greater detail, by way of example, 
with reference to the accompanying drawings. 
In the drawings, a reamer 1 comprises a shank 2 adapted to be clamped in a 
machine tool, and an integral head 3, the reamer 1 being rotatable by the 
machine tool about elongate axis 4. 
The head 3 has a circular periphery 5 interrupted by a machined flat 6, and 
an axial slot 7 extending along the flat 6 defined by a blade supporting 
face 8, an opposite face 9 and a common interconnecting base 10. As best 
seen in FIG. 1, the blade supporting face 8 is positively raked at 
10.degree. with respect to a radius plane 11 extending from the axis of 
rotation 4. The opposite face 9 is also angled such that it, and the blade 
supporting face 8, together define a taper which narrows towards the 
centre of the head 3. 
A single, elongate carbide blade 12, of trapezoidal cross-section having a 
longer front cutting face 13 and a shorter rear back face 14 which abuts 
the blade supporting face 8, is located within the slot 7 and is clamped 
against the blade supporting face 8 by means of a single element clamping 
plate 15 extending over the full axial length of the blade 12 and again of 
trapezoidal cross-section having a longer, front face 16 directed away 
from the slot 7 and a shorter, back face 17 directed into the slot 7, with 
angled end faces 18 and 19 abutting respectively the front cutting face 13 
of the cutter 12 and the opposite face 9 of the slot 7. 
As shown in FIG. 1, the supporting face 8 is preferably disposed in a 
non-parallel relationship with the radius plane 11 extending through the 
longitudinal axis 4 of the reamer body and through the outer edge of the 
cutting face 13 of the blade 12. Thus, the blade 12 is adjustable along a 
plane 25 that is not parallel to a plane that extends through the 
longitudinal axis 4 and that is preferably disposed at a positive angle 
relative to the radius plane 11. 
The clamping plate 15 is provided with two spaced apart, tapped holes 20 
each to receive a securing screw 21, the shank of which screw also passes 
through a hole 22 in the head 3. The latter is also provided with two 
further tapped, and spaced apart, holes 23 adjacent each end of the blade 
12, each hole receiving an adjusting screw 24 to adjust the projection of 
the blade 12 beyond the periphery 5 of the head 3, not only for initial 
setting up of the reamer 1, but also for adjustment purposes after wear on 
the blade 12 has occurred by displacing the blade along the plane 25 
parallel to a tangent to the reamer periphery. The slot 7 is also provided 
with a stop pin 26 against which one end face 27 of the blade 12 is 
located, while the head 3 is also provided with a pair of peripherally 
spaced burnishing pads 28 having faces 29 projecting beyond the periphery 
5, the pads 28 being spaced apart circumferentially and spaced from the 
blade 12.