Spherical seat cutting apparatus

Details Spherical seat cutting apparatus Spherical seat cutting apparatus

1999-03-05

2001-04-24

Tsai, Henry (Department: 3722)

Cutters, for shaping

Rotary cutting tool

Including holder having seat for inserted tool

C407S042000, C407S048000, C407S065000

Reexamination Certificate

active

06220794

ABSTRACT:

BACKGROUND OF THE INVENTION
The invention relates to a cutter for cutting spherical seats in metallic workpieces.
Depicted in
FIG. 1
is a prior art spherical seat cutter
20
a
of the type described in Peuterbaugh U.S. Pat. No. 5,232,317. The seat cutter
20
a
cuts a spherical seat S on the interior of a workpiece such as a differential casing D which is fixedly held. Suitable article handling apparatus, not shown, transfers the casing D to and from the work station shown in
FIG. 1
in a direction
10
perpendicular to the paper. The casing D has diametrically aligned bores B around which the seats S are cut, as well as a large opening O at its top. The cutter
20
a
is supported for rotation about its central axis by a hanger
22
a
which is in turn mounted for vertical and horizontal movement. Cutter
20
a
includes a steel cutter body
26
a
formed with a reduced diameter section
28
a
at its rearward end which is rotatably supported within a bore
30
a
through hanger
22
a
. A removable retainer plate
32
a
detachably coupled to the rearward end of the reduced diameter section
28
a
of the cutter body retains the cutter against axial movement relative to hanger
22
a.
In the tooling arrangement shown in
FIG. 1
, a single-ended cutter cuts the seat at one side of the differential case at the work station. An alternative arrangement could be provided which utilizes a double-ended cutter, i.e., with a like second body portion
26
a
projecting from the opposite end of reduced diameter section
28
a
, initially to cut one seat and then the other seat.
A rotatable drive arbor
34
projects through a central passage
36
a
extending through cutter
20
a
and is rotatably supported at opposite sides of the differential casing D by stationary bearing assemblies
38
a
and
40
a
. The arbor
34
a
is formed with splines engageable with complementary splines formed within the central passage
36
a
. The arbor
34
a
is coupled to a suitable drive mechanism which is operable to drive the arbor in rotation and to also shift the arbor horizontally.
The cutting of the seat in the workpiece D is performed by indexible cutting inserts
42
a
detachably mounted in the cutter. The inserts
42
a
include substantially parallel main surfaces
44
a
intersected by end surfaces
46
a
to form cutting edges
48
a
. The inserts
42
a
are mounted by fastener screws
50
a
in recesses formed in a front end surface F of the steel body
26
a
of the cutter
20
a
such that the main surfaces
44
a
lie in planes intersecting the front end surface F. The fastener screws
50
a
extend tangentially with respect to the axis of rotation.
The cutter
20
a
may be susceptible to fracture at regions A disposed between the central passage
36
a
and respective inserts
42
a
, because the thickness of the steel of the body
26
a
there is minimal and may not be able to withstand the forces generated at high rpm's.
SUMMARY OF THE INVENTION
The present invention relates to a rotary cutting tool for cutting a spherical seat on a surface of a workpiece. The cutting tool comprises a body adapted to carry cutting inserts. The body has a bore extending therein along a longitudinal center axis of the body for receiving a drive shaft. The body includes a forwardly facing front surface of generally convex shape so as to protrude forwardly. A plurality of insert seats is formed in the front surface in circumferentially spaced relationship about the axis. Each of the insert seats faces generally forwardly and comprises recesses of generally pyramidal shape. A screw-threaded hole extends through each of the seats in a rearward direction and is adapted to receive an insert-fastening screw.
The inverted pyramidal geometry of each insert seat is preferably formed by a first plurality of V-shaped parallel grooves and a second plurality of V-shaped parallel grooves extending perpendicularly to the first plurality of grooves and intersecting the first plurality of grooves.
The invention also pertains to an indexible cutting insert adapted to be mounted on a rotary body. The insert comprises forward and back surfaces disposed generally parallel to one another and intersected by a plurality of end surfaces. The end surfaces intersect the forward surface to form a plurality of cutting edges therewith. The back surface has projections of generally pyramidal shape. The projections are formed by a first plurality of generally V-shaped parallel grooves, and a second plurality of generally V-shaped parallel grooves extending perpendicularly to the first plurality and intersecting the first plurality. The forward surface includes a generally spherical bevel extending around an outer periphery thereof and intersecting the cutting edges.


REFERENCES:
patent: 2134140 (1938-10-01), Miller
patent: 2202407 (1940-05-01), Sykes
patent: 4789273 (1988-12-01), Wiacek et al.
patent: 4838739 (1989-06-01), Stashko
patent: 5232317 (1993-08-01), Peuterbaugh
patent: 5741095 (1998-04-01), Charron et al.
patent: 5820310 (1998-10-01), Boianjiu
patent: 213925 (1957-12-01), None

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