Cutting tool assembly

A cutting tool assembly having a cutter head including a pair of jaws defining a slot therebetween with a knife plate having a pair of axially symmetrical cutting edges being exchangeably mounted in the cutter head in the slot between the jaws is provided with a setscrew adjustably connecting the knife plate on the cutter head and with a pair of support members arranged at the base of the slot between the knife plate and the cutter head cooperating with the setscrew to enable adjustment of the knife plate. The support members are internally threaded and interconnected by a bolt having oppositely threaded portions with oblique abutment surfaces being formed on the support members for engagement with the knife plate.

The present invention relates generally to a cutting tool which includes a 
knife plate which is exchangeably inserted in the end of a cutter head, 
with the knife plate being provided with a pair of axially symmetrical 
cutting edges. 
In order to achieve high accuracy and good surface quality in the work 
products produced by tools of the type to which the present invention 
relates, the two diametrically opposed cutting edges of the tool must be 
arranged to lie precisely on a flight circle concentric relative to the 
axis of the tool. Otherwise, an exact concentricity and resulting equal 
cutting pressure of the two cutting edges could not be ensured. 
Consequently, especially where high cutting efficiency is to be obtained 
by tools of this type, the knife plate must be supported in a stable 
manner and must be securely adjustably retained in position. 
Accordingly, the present invention is directed toward provision of a 
cutting tool enabling stable adjustable securing of the knife plate by 
means which are relatively simple in design and which also make it 
possible to easily exchange and replace the knife plate. 
SUMMARY OF THE INVENTION 
Briefly, the present invention may be defined as a cutting tool assembly 
comprising a cutter head including a pair of jaws defining a slot 
therebetween, a knife plate defining a pair of axially symmetrical cutting 
edges exchangeably mounted on the cutting head in said slot between said 
jaws, setscrew means for adjustably connecting the knife plate on the 
cutter head, a pair of support members arranged at the base of the slot 
between the knife plate and the cutter head, said support members acting 
as abutment means for the knife plate and bolt means having oppositely 
threaded portions engaging each of said support members, respectively, and 
cooperating with the setscrew means to enable adjustment of the knife 
plate. 
In accordance with the present invention, the knife plate may be held 
between the axially symmetrical longitudinal slot which is defined between 
the pair of jaws so that an exact concentricity and a uniform cutting 
pressure of the diametrically opposed cutting edges may be ensured even at 
high cutting capacity and so that exchange of the cutting plate may be 
accomplished in a relatively simple manner. 
In a preferred embodiment of the invention, the cutter head is provided 
with a bore located at the base of the slot within which the support 
members are received, with the support members being formed as internally 
threaded members engaging the bolt means and being provided with generally 
symmetrically arranged oblique surfaces against which the knife plate may 
abut. 
If a two-way or reversible plate is used as the knife plate having cutting 
edges which are not in engagement bearing against the abutment surfaces, 
the latter will have an additional oblique surface which corresponds to 
the undercutting angle. To avoid contact of the abutment surfaces which 
are concentrated in a point, the abutment surfaces are advantageously 
constructed in such a way that they bear against the cutting edges which 
are not in engagement over a flat area. In the case where the cutting 
edges are curved, the abutment surfaces may have a concave configuration 
which corresponds to the curvature of the cutting edges. 
The various features of novelty which characterize the invention are 
pointed out with particularity in the claims annexed to and forming a part 
of this disclosure. For a better understanding of the invention, its 
operating advantages and specific objects attained by its use, reference 
should be had to the accompanying drawings and descriptive matter in which 
there is illustrated and described a preferred embodiment of the invention 
.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now to the drawing, there is depicted a cutting tool assembly 1 
in accordance with the present invention including a cutter head 2 and a 
knife plate 3. The cutter head 2 is formed with a pair of jaws 21, 22 
defining a slot therebetween within which the knife plate 3 is received. 
The knife plate 3 is formed with a pair of axially symmetrical oblique 
surfaces 31, 32 having outer boundaries which form the cutting edges of 
the tool and which, together with a pair of oblique surfaces formed by 
lateral recesses of the cutter head jaws 21, 22, define a cutting space or 
chamber. 
The knife plate 3 is formed with a bore 33 which receives a setscrew 25 and 
with a pair of rearward end faces 34, 35 by means of which the knife plate 
3 bears against oblique surfaces 41 and 51 of a pair of support members 4 
and 5 which are internally threaded and which are arranged within a bore 
26 of the cutter head 2. 
The bore 26 extends perpendicularly to the axis of the cutter head at the 
base of the slot within which the knife head is arranged between the knife 
plate and the cutter head. The slot 26 extends across the entire width of 
the slot within which the knife plate 3 is received. The support members 4 
and 5 are formed with oppositely threaded internal threads with one of the 
support members 4, 5 having a left-hand thread and with the other having a 
right-hand thread. A bolt 6 is provided at opposite ends thereof with 
corresponding external threads which are also oppositely threaded and upon 
which the left- and right-hand threads of the support members 4 and 5 are 
received, respectively. 
The support members 4 and 5 are adjustably engaged with the bolt 6 to 
enable longitudinal movement relative to each other. By means of such 
longitudinal movement of the support members 4 and 5, the two oblique 
surfaces 41 and 51 will slide along the rearward end faces 34 and 35 of 
the knife plate 3 and operate to fix the faces 34, 35 in axial symmetrical 
position in cooperation with the setscrew 25 which extends through the two 
cutter jaws 21 and 22. 
The head of the setscrew 25 is received by a cylindrical bore 23 of the jaw 
21 and with a threaded provided at its opposite end the screw engages in a 
threaded bore 24 of the jaw 22. 
The cutter head 2 is formed at a rearward shaft portion thereof with a 
longitudinal groove 11 into which an engaging member of a drive sleeve or 
chuck may engage for operation of the tool. 
The advantages of the invention are essentially achieved in that the 
setscrew 25 which presses together the jaws of the cutter head 2 will 
extend through the knife plate 3 and in its rearward region the knife 
plate 3 will engage against the oblique surfaces 41, 51 of the support 
members 4, 5 which may be threadedly moved relative to each other in order 
to enable adjustable positioning of the knife plate, with the oblique 
surfaces 41, 51 forming an included angle between each other. 
If the knife plate is to be of the reversible type, the rearward end faces 
34, 35 may also constitute knife edges. In such a case, the oblique 
surfaces 41, 51 may be formed as concave surfaces which are curved in the 
radial direction of the members 4 and 5. In order to avoid contact between 
the abutment surfaces 41, 51 and the rearward end faces 34, 35 which is 
concentrated at a point, the abutment surfaces are advantageously 
constructed in such a way that they bear against the faces 34 and 35 over 
a flat or more extended area. The concavity of the abutment surfaces 41, 
51 may be formed with a curvature which corresponds to the curvature of 
the end faces 34, 35. 
The end faces 34, 35 are formed so that the included angle therebetween is 
not less than 140 degrees and preferably about 160 degrees. 
While a specific embodiment of the invention has been shown and described 
in detail to illustrate the application of the inventive principles, it 
will be understood that the invention may be embodied otherwise without 
departing from such principles.