Note: Descriptions are shown in the official language in which they were submitted.
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Thi~ application is a division of application
serial number 492,695 filed October 10, 1985.
Backqround of Invention
The invention relates to cutter h~ad assemblies
intended for use in gear cutting operations. The
cutter assemblies are designed to receive bar stock
type tools having an indexable shank portion and
profiled cutting surfaces located at one end. The
tools are arranged in slots formed in the periphery of
a cutter head in positions projecting from a front face
thereof. One or more tools may be located in each slot
and in ~he latter instance, a forward and rearward tool
may be defined with respect to a cutting direction.
In gear cutting operations, it is often desirable
to utilize a maximu~ number of cutting tools in a given
size cutter head. Accordingly, known cutter assembly
- arrangements provide for locating more than one cutting
tool in a common slot formed in a cutter head. In one
known design, a pair of cutting tools are located
contiguously within the same slot. This arrangement,
however, tends to result in chip packing between
succeeding cutting tools thereby inhibiting cutting
performance. In a second known cutter assembly design,
a spacing shim is spot welded to the cutter head
between succeedinq cutting tools located in a common
slot. Although sufficient clearance is provided
between succeedinq cutting tools to alleviate the chip
packing problem, cutter head manufacture is
significantly complicated. Difficulties arising from
accurately sizinq and locating the spacinq shim add
cost to the manufacture of the cutter head and may
adversely affect accurate positio~ing of the cutting
tool.
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Summary o~ Invention
The novel cut;ter head assembly of the present
invention obviates the special shim arrangement of the
above mentioned prior art design while preserving
clearance between succeeding cutting tools located in a
common slot. The present invention provides for
cutting clearance through a simple and inexpensive
cutting tool modification which is essentially
independent of the accuracy requirements of individual
tools and the associated cutter assembly. Moreover,
these cutting tools may be indexed and reprofiled
without disturbing a predetermined clearance between
succeeding tools.
The cutter assembly of the present invention
includes a pair of cutting tools adapted to fit
contiguously in a common slot. The shank portion of
the forward most tool of the pair includes a recess
~0 formed in a back wall of the tool which extends along
the length of the tool. On each side of the tool
recess, a narrow portion of the tool back wall remains
as an abutting surface for contacting a front wall of a
succeeding tool. These remaining back wall portions
are sufficiently narrow so as to be easily removed at
the cutting end of the tool by ordinary profiling or
reprofiling operations on the tool. By removing the
remaining narrow portions of the tool back wall at the
profiled end of the tool, chip clearance is provided
between succeeding cutting tools. The depth of recess
provided in the tool back wall may be adjusted to
optimize cutting clearance without affecting tool
location with res~ect to the cutter head.
In addition, the forward tool of the tool pair may
be increased in thickness with respect to the cutting
direction by an amount corresponding approximately to
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the depth of recess formed in the tool back wall. In
this way, profiled cutting ends of each tool of the
pair are maintained approximately equal in thickness.
More importantly, however, the total thickness of the
tool pair is adjusted 50 that the tool pair exactly
fits within the tool slot.
A novel clamping arrangement is also provided for
securing cutting tools within the cutter head assembly
of the present invention. The cutting tools are
received in slots formed in cutter head and are secured
by clamping blocks which are operably ~onnected to a
circumferential ring member which encloses the entire
assembly. The clamping blocks are releasably secured
to ri~g mounted screw elements by snap type
connections. This novel clamping arrangement is also
intended for securing a range of tool types in geax
cutter heads.
These and other features and advantages of the
present invention will become apparent in the more
detailed discussion which follows, and in that
discussion reference will be made to the accompanying
drawings as briefly described below.
Brief DescriPtion of Drawinqs
Figure 1 is a greatly enlarged scale front
isometric view of a cutting tool modified in accordance
with the present invention.
Figure 2 is a back isometric view in the same
scale and of the same tool as shown i~ Figure 1.
Figure 3 is a top view of a cutter assembly
arranged in accordance with the present invention.
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Figure 4 is a cut away side view of the same
cutter assembly shown in Figure 3.
Figure 5 is an isometric view partly in phantom
showing a full view of cutting tools arranged in a
cutter head in accordance with the present invention.
Figure 6 is a bisectional view of the clamping
block shown in Figures 3 and 4.
Figure 7 is a top view of a pair of cutting tools
in accordance with the present invention.
Figure 8 is a cross sectional view through a base
portion of the same pair of tools shown in Figure 7.
Detailed Description of Invention
In face milling type gear cutting assemblies,
cutting tools are often arranged in groups about a
cutter head. Each group may include separately
designed cutting tools for s~parately cutting the two
side walls and the bottom portion of each tooth slot to
be formed in a work piece. For instance, an inside
cutting tool may be provided to cut one side wall of a
tooth slot, an outside cutting tooI may be provided to
cut the opposite side wall of the same tooth slot, and
a bottom cut~ing tool may be provided for forming the
bottom of the tooth slot to be formed in the work
piace.
In certain gear cutting operations, such as
continuous cutting operations in which a work piece and
cutter assembly are rotated together in a timed
relationship, it is especially important to accurately
position bottom cutting tools for protecting clearance
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side surfaces of inside and outside cutting tools
against excessive wear. Accordingly, the preferred
embodiment of the;present invention provides for the
accurate positioning of a bottom cutting tool
contiguously with one of the aforementioned side
cutting tools within a common slot.
Although the preferred embodiment includes a
particular combination of bottom and side cutting tools
positioned contiguously within the same slot, the
principles of the present invention relate to any
combination of tool designs. In addition, the
preferred embodiment includes a particular ~ar stock
type cutting tool in which a front cutting face is
preserved during reprofiling operations. The present
invention, however, is applicable to any type of bar
stock type cutting tools whether a front cutting face
is sharpened or not.
Referring to Figures 1 and 2, a bottom cutting
tool is shown modified in accordance with the preferred
embodiment of the present invention. The tool is
generally of rectangular cross section and may be
formed from a length of bar stock. The tool includes a
base portion 10 and a profiled cutting end 12. The
generally rectangular form of the tool is defined by
front wall 14, back wall 18 and side surfaces 30 and
32. A cutting fac~ 16 is formed in front wall 14 and
defines with flank surfaces 20 and 22 and top surface
24 the profiled cutting end 12 of the tool. Of
particular importance to the present invention, recess
surface 28 is formed in back wall 18. Recess surface
28 extends the length of the tool while preserving
narrow portions of back wall 18 on either side. The
narrow portions of back wall 18, however, terminate
below cutting end 12 due to the formation of flank
surfaces 20 and 22 in side surfaces 30 and 32 of the
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tool respectively. Although not shown, the tool is
also intended to include well known radiused portions
between top surface 24 and ~lank surfaces 20 and 22.
The cutter assembly of the present invention in
its preferred embodiment is shown in Figures 3 and 4.
The cutter assembly illustrated is applicable to
continuous gear cutting operations. The bottom cutting
tool shown in Figures 1 and 2 is now designated as 40
in the remaining figures~ Inside cutting tool 38 and
outside cutting tool 42 are also included within the
cutter assembly. Corresponding surfaces on these tools
are designated with the same reference numerals as
bottom cutting tool 40.
The illustsated cutter assembly includes a main
body member 34 and a ring member 36 which is shxunk
onto or otherwise secured to the main body member 34
after tool receiving slots 44 and 46 ~shown in Figure
5) are formed into main body member 34. Inside cutting
tool 38 is positioned within tool receiving slot 44.
Of particular importance to ~he present invention,
bottom cutting tool 40 and outside cutting tool 42 are
positioned contiguously within tool receiving slot 46.
Narrow back wall surfaces 18 of bottom cutting tool 40
abut front wall 14 of outside cutting tool 42. Back
wall surfaces 18, however, terminate below the cutting
end of bottom cutting tool 40. Accordingly, recess
surface 28 of bottom cutting tool 40 together with
cutting face 16 of outside tool 42 define a clearance
space between the succeeding tools. Figures 7 and 8
further illustrate the contiguous relationship of
bottom cutting tool 40 and outside cutting tool 42.
The preferred embodiment of the present invention
also includes a novel clamp$ng axrangement for
releasably securing cutting tools in tool receiving
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slots. Referring to Figures 3, 4 and 6, a novel
clamping block 48 is illustrated. Clamping block 48 is
adapted to secure cutting tools 40 and 42 within slot
46. A similar clamping block 50 is also provided for
securing tool 38 within slot 44. Both blocks are
associat~d with screw elements having shaped head
portions 56, narrowed neck portions 55 and threaded
portions 52 which are fitted in threaded bores 60 of
ring member 36. The threaded portion 52 of each screw
element is provided with a recessed outer end of
irregular shape for receiving a tool which functions to
turn the screw element toward or away from associated
cuttins tools. Shaped head portions 56 may be
appropriately sized to permit passage through threaded
bores 60 during assembly. Each block is provided with
a through slot 54 and a partially enclosed opening 58
for receiving shaped head portion 56. Furthermore,
partially enclosed opening 58 is adapted to embrace
slightly more than one half the circumference of
narrowed neck portion 55.
This arrangement permits a snap type securement of
each clamping block 48, 50 to its associated screw
element so that clamping block 48, 50 will not fall out
of its respective slot when it is withdrawn from
clamping contact or thereafter inverted. Partially
enclosed opening 58, however, permits quick release of
clamping block 48, 50 when the clamping block i5 pushed
upward through the front face of the assembly with a
predetermined amount of force. In this way, clamping
blocks can be readily cleaned or replaced without
removing screw elements from their threaded bores.
Although not shown, the preferred embodiment may
also include well known shim elements for radially
adjusting the position of cutting tools within their
associated slots. Clamping blocks 48, 50 may be
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readily replaced, as described above, with
appropriately sized clamping blocks for accommodating
different size shim elements.
Having described the present invention and a
preferred embodiment thereof, it can be appreciated
that the concepts disclosed are adaptable to a wide
range of gear cutter assemblies without departing from
the intended scope of invention.
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