Machine tools abstract
A machining apparatus is disclosed which includes a rotatable tool
turret having a plurality of modular machine tools removably supported
thereon in circumferentially spaced apart relationship, a transmission
assembly for effectuating the indexed rotation of the tool turret,
and a multi-disc variable-speed drive system for independently driving
each of the modular machine tools supported on the tool turret.
Machine tools claims
What is claimed is:
1. A machining apparatus comprising:
a) a supporting structure mounted adjacent a work holding platform;
b) a turret operatively connected to said supporting structure
and mounted to rotate about an axis extending parallel to said work
holding platform;
c) a primary drive member mounted to rotate about a fixed axis
of rotation with respect to said supporting structure;
d) a plurality of tool assemblies supported on said turret in circumferentially
spaced apart relationship, each tool assembly having a respective
driven member operatively connected thereto which is mounted to
rotate about a respective axis of rotation relative to said turret;
e) a secondary drive member operatively connected to said supporting
structure and configured to transmit rotational motion between said
primary drive member and a selected one of said driven members frictionally
engaged with said secondary drive member, said secondary drive member
mounted to translate along an axis extending perpendicular to the
axis of rotation of said primary drive member;
f) a transmission assembly for effectuating the rotation of said
turret relative to said supporting structure to align a selected
one of said tool assemblies with said work holding platform and
consequently frictionally engage a corresponding one of said driven
members with said secondary drive member; and
g) a linear drive assembly for effectuating the axial translation
of said secondary drive member relative to said selected driven
member.
2. An apparatus as recited in claim 1 wherein said secondary drive
member is mounted to translate relative to said selected driven
member and said primary drive member, while remaining in frictional
contact therewith, to vary the relative rotational speeds thereof.
3. An apparatus as recited in claim 2 wherein said secondary drive
member is mounted to translate along an axis which is perpendicular
to the axis of rotation of said primary drive member.
4. An apparatus as recited in claim 3 wherein the rotational speed
of a selected one of said driven members decreases with respect
to the rotational speed of the primary drive member as the secondary
drive member translates radially outwardly from the axis of rotation
of said driven member.
5. An apparatus as recited in claim 3 further comprising a linear
drive assembly for effectuating the axial translation of said secondary
drive member.
6. An apparatus as recited in claim 5 wherein said linear drive
assembly includes an axial drive screw, a bearing collar operatively
associated with said axial drive screw and said secondary drive
member, and a motor for driving said axial drive screw.
7. An apparatus as recited in claim 1 wherein said transmission
assembly includes a series of intermeshed drive gears operatively
connected to said turret and driven by a stepper motor.
8. An apparatus as recited in claim 1 wherein said plurality of
tool assemblies is selected from the group of tool assemblies consisting
of a sanding tool, a routing tool, a sawing tool, and a drilling
tool.
9. An apparatus as recited in claim 1 further comprising a main
drive motor housed within said supporting structure for delivering
power to said primary drive member.
10. A machining apparatus comprising:
a) a supporting structure mounted adjacent a work holding platform
defining a substantially planar work surface;
b) a turret operatively connected to said supporting structure
and mounted to rotate relative to said work holding platform about
an axis extending parallel to said planar work surface;
c) a primary drive member operatively connected to said supporting
structure and mounted to rotate about an axis extending perpendicular
to said planar work surface;
d) a plurality of tool assemblies supported on said turret in circumferentially
spaced apart relationship, each tool assembly having a respective
driven member operatively connected thereto which is mounted to
rotate about an axis extending perpendicular to the axis of rotation
of said turret;
e) a secondary drive member configured to transmit rotational motion
from said primary drive member to a selected one of said driven
members frictionally engaged therewith, said secondary drive member
mounted to translate along an axis extending perpendicular to the
axis of rotation of said primary drive member, relative to said
selected driven member, while remaining in frictional contact therewith,
to vary the rotational speed of said driven member;
f) a transmission assembly for effectuating the rotation of said
turret relative to said planar working surface to align a selected
one of said tool assemblies with said work holding platform and
consequently engage a corresponding one of said driven members with
said secondary drive member; and
g) a linear drive assembly for effectuating the axial translation
of said secondary drive member relative to said selected driven
member.
11. An apparatus as recited in claim 10 wherein the rotational
speed of a selected one of said driven members increases with respect
to the rotational speed of the primary drive member as said secondary
drive member translates radially inwardly from a peripheral edge
of said driven member.
12. An apparatus as recited in claim 10 wherein said linear drive
assembly includes an axial drive screw, a bearing collar operatively
connected to said drive screw and said secondary drive member, and
a motor for driving said drive screw.
13. An apparatus as recited in claim 10 wherein said plurality
of tool assemblies is selected from the group of tool assemblies
consisting of a sanding tool, a routing tool, a sawing tool, and
a drilling tool.
14. An apparatus as recited in claim 10 wherein said transmission
assembly includes a series of intermeshed drive gears operatively
connected to said turret and driven by a stepper motor.
15. An apparatus as recited in claim 10 further comprising a main
drive motor associated with said supporting structure for delivering
power to said primary drive member.
16. A machining apparatus comprising:
a) a supporting structure housing a drive motor and mounted adjacent
a work holding platform defining a substantially planar work surface;
b) an indexing turret disposed adjacent said supporting structure
and mounted to rotate relative to said work holding platform about
an axis extending parallel to said planar work surface;
c) a primary drive member operatively connected to said drive motor
and mounted to rotate about an axis extending perpendicular to said
planar work surface;
d) a plurality of tool assemblies removably supported on said indexing
turret in circumferentially spaced apart relationship, each tool
assembly having a respective driven member operatively connected
thereto which is mounted to rotate about an axis extending perpendicular
to the axis of rotation of said indexing turret;
e) a secondary drive member operatively connected to said supporting
structure and configured to transmit rotational motion from said
primary drive member to a selected one of said driven members, said
secondary drive member mounted to translate along an axis extending
parallel to the axis of rotation of said indexing turret, relative
to said selected driven member and said primary drive member, while
remaining in frictional contact therewith, to vary the rotational
speed of said driven member;
f) a transmission assembly for effectuating the rotation of said
indexing turret relative to said planar work surface to align a
selected one of said tool assemblies with said work holding platform
and consequently engage a corresponding one of said driven members
with said secondary drive member; and
g) a linear drive assembly for effectuating the axial translation
of said secondary drive member relative to said selected driven
member and said primary drive member.
17. An apparatus as recited in claim 16 wherein said plurality
of tool assemblies is selected from a group of tool assemblies consisting
of a sanding tool, a routing tool, a sawing tool, and a drilling
tool.
18. An apparatus as recited in claim 16 wherein said linear drive
assembly includes an axial drive screw, a bearing collar operatively
associated with said drive screw and said secondary drive member,
and a motor for driving said drive screw.
19. An apparatus as recited in claim 16 wherein said transmission
assembly includes a series of intermeshed drive gears operatively
connected to said turret and driven by a stepper motor.
20. A drive assembly for a machine having a power source comprising:
a) a primary drive member operatively connected to the power source
of said machine and mounted to rotate about a first axis of rotation;
b) a driven member mounted to rotate about a second axis of rotation
which is parallel to said first axis of rotation; and
c) a secondary drive member configured to transmit rotational motion
from said primary drive member to said driven member, said secondary
drive member including means providing for rotative movement about
and translation along an axially disposed linear drive screw extending
perpendicular to said first and second axes of rotation, while remaining
in frictional contact with said primary drive member and said driven
member, to vary the rotational speed of said driven member.
21. A drive assembly as recited in claim 20 further comprising
a linear drive assembly for effectuating the axial translation of
said secondary drive member relative to said driven member and said
primary drive member.
22. A drive assembly as recited in claim 20 wherein said primary
drive member comprises a first friction disc having an annular planar
contact surface.
23. A drive assembly as recited in claim 22 wherein said secondary
drive member comprises a second disc having a circumferential peripheral
contact surface.
24. A drive assembly as recited in claim 23 wherein said driven
member comprises a third disc having an annular planar contact surface.
25. A drive assembly as recited in claim 23 wherein the circumferential
peripheral contact surface of the second disc is provided with an
elastomeric contact material.
26. A drive assembly as recited in claim 20 wherein said power
source comprises an electric drive motor.
27. A drive assembly for a machine having a power source comprising:
a) a primary driver operatively connected to the power source of
said machine and mounted to rotate about a first axis of rotation;
b) a driven member supported adjacent said primary driver and mounted
to rotate about a second axis of rotation; and
c) a secondary drive member configured to transit rotational motion
from said primary driver to said driven member, said secondary drive
member including means providing for linear translation with respect
to the axis of rotation of said driven member, along an axially
disposed linear drive screw extending therethrough, said means further
providing for rotative movement of said secondary drive member about
said drive screw, while remaining in frictional contact with said
driven member and said primary driver to vary the rotational speed
of said driven member.
28. A drive assembly as recited in claim 27 wherein said primary
driver comprises a driving friction disc mounted on a rotating drive
shaft.
29. A drive assembly as recited in claim 27 wherein said secondary
drive member comprises a driven friction disc mounted to rotate
about and translate along an axis extending perpendicular to said
first and second axes of rotation.
30. A drive assembly as recited in claim 27 wherein said second
axis of rotation is parallel to said first axis of rotation.
Machine tools description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The subject invention is related to machine tools, and more particularly,
to a machining apparatus having a plurality of modular machine tools
supported on a rotating turret and a system for driving each of
the machine tools.
2. Background of the Related Art
Various approaches and techniques have been utilized to develop
machine tools that would be highly efficient in large-scale manufacturing.
One approach is to construct machines from basic modular units that
accomplish a particular function rather than produce a specific
part. These units are often referred to as self-contained power-head
production machines. Such machines are generally connected to one
another by automatic transfer devices which move work pieces from
one station to the next.
Transferring is usually accomplished by one of four methods. In
one method, work pieces are pulled along supporting rails by means
of an endless chain which moves intermittently as required. In another
method, work pieces are pushed along continuous rails by air or
hydraulic pistons. A third method involves moving workpieces by
an overhead chain conveyor which lifts the work from one station
and deposits it at another. A fourth method, utilized when only
a few operations are to be performed, employs a rotary indexing
table to support the workpiece, and a plurality of machining heads
or tools arranged radially about the table. The table may move continuously
or intermittently to transfer the workpiece from one tool to another.
In each of these transfer devices, means must be provided for accurately
positioning the workpieces at each work station.
To overcome the need for such positioning means, machines have
been constructed with rotating turrets which support a number of
tool heads adjacent a working surface. In use, a work piece is positioned
on the working surface and the turret is selectively rotated to
move a particular tool head into alignment with the work piece.
Early examples of this type of machine are disclosed in U.S. Pat.
No. 463790 to Quint and U.S. Pat. No. 542695 to Stover et al.,
both of which are directed to drilling machines having multiple
drill heads. A later machine disclosed in U.S. Pat. No. 2767598
to Burg includes a rotating turret which supports a plurality of
drill presses and means for controlling the rotational speed of
the rotary tool elements. The speed of the tool elements may be
controlled either by adjusting the speed or the motor or by selecting
between two pulley drives of different ratio.
A modem computer controlled machining apparatus having a rotating
turret which supports a plurality of machine tools is presently
manufactured by CMS North America, of Grand Rapids, Mich. Each machine
tool is driven by a separate motor which is also supported on the
turret. The speed of each tool element is varied by selectively
varying the speed of the motor associated therewith. Consequently,
at low tool speed, motor efficiency is necessarily below optimum.
A need exists for a machining apparatus with a rotary turret that
supports a plurality of machine tools in such a manner so that all
tools are driven by a single drive motor, and wherein the speed
of each tool may be selectively varied without varying the speed
of the drive motor, so that the drive motor may be continuously
operated at peak horsepower.
SUMMARY OF THE INVENTION
The subject invention is directed to a highly efficient machining
apparatus which includes an indexing tool turret mounted to rotate
relative to a work holding platform. A plurality of machine tools
are supported on the turret in circumferentially spaced apart relationship.
Each machine tool is configured as a removable module and includes
a respective driven member which is mounted to rotate relative to
the tool turret.
The apparatus further includes a drive system including a primary
drive member driven by a main drive motor, and a secondary drive
member configured to transmit rotational motion from the primary
drive member to the driven member of a selected one of the machine
tools supported on the tool turret. Preferably, the secondary drive
member is mounted to translate along an axis extending perpendicular
to the axis of rotation of the primary drive member, relative to
the selected driven member, while remaining in frictional contact
therewith, to vary the rotational speed of the driven member.
A linear drive assembly is provided to effectuate the axial translation
of the secondary drive member relative to the selected driven member
and the primary drive member. Preferably, the linear drive assembly
includes an axial drive screw and a drive motor to effectuate the
rotation of the drive screw. In use, the rotational speed of a selected
one of the driven members will decrease with respect to the rotational
speed of the primary drive member as the secondary drive member
translates radially outwardly from the axis of rotation of the driven
member. Conversely, the rotational speed of a selected one of the
driven members will increase with respect to the rotational speed
of the primary drive member as the secondary drive member translates
radially inwardly from a peripheral edge of the driven member. Accordingly,
the speed of a selected driven member can be varied during a machining
operation without effecting the operating efficiency of the main
drive motor.
The machining apparatus of the subject invention further includes
a transmission assembly for effectuating the indexed rotation of
the tool turret relative to the work holding platform, to align
a selected one of the machine tools therewith and consequently engage
a corresponding one of the driven members with the secondary drive
member. The transmission assembly preferably includes a series of
intermeshed gears which are operatively connected to the tool turret
and a stepper motor for driving the gears.
A wide variety of machine tools may be employed with the machining
apparatus of the subject invention. For example, the apparatus may
include sanding tools, routing tools, sawing tools, or drilling
tools. Preferably, each machine tool is configured as an independent
modular unit which is removably mounted on the tool turret utilizing
a standardized mounting assembly. Accordingly, the tool modules
may be interchanged or rearranged on the tool turret depending upon
the machining operation to be performed.
The subject invention is further directed to a drive assembly for
a machine which includes a primary chive member operatively connected
to a drive motor and mounted to rotate about a first axis of rotation,
a driven member mounted to rotate about a second axis of rotation
which is parallel to the first axis of rotation, and a secondary
drive member configured to transmit rotational motion from the primary
drive member to the driven member, wherein the secondary drive member
is mounted to translate along an axis extending perpendicular to
the first and second axes of rotation, while remaining in frictional
contact with the primary drive member and the driven member, to
vary the rotational speed of the driven member. Preferably, the
primary drive member comprises a first disc having an annular planar
contact surface, the secondary drive member comprises a second disc
having a circumferential peripheral contact surface, and the driven
member comprises a third disc having an annular planar contact surface.
Further features of the machining apparatus of the subject invention
will become more readily apparent from the following detailed description
taken in conjunction with the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
So that those having ordinary skill in the art to which the subject
invention appertains will more readily understand how to construct
and use the machining apparatus described herein, preferred embodiments
of the apparatus will be described in detail hereinbelow with reference
to the drawings wherein:
FIG. 1 is a perspective view of a work station employing a machining
apparatus constructed in accordance with a preferred embodiment
of the subject invention;
FIG. 2 is a perspective view of the machining apparatus of the
subject invention;
FIG. 3 is a front elevational view of the machining apparatus of
FIG. 2 illustrating the plurality of machine tool modules associated
therewith;
FIG. 4 is a side elevational view of the machining apparatus of
FIG. 2 illustrating the components of the transmission assembly
and drive system associated therewith;
FIG. 5 is front elevational view of the machining apparatus of
FIG. 2 with the tool turret rotated in a counter-clockwise direction
from the position shown in FIG. 3;
FIG. 6 is a perspective view of the machining apparatus of FIG.
2 with the machine tool modules removed from the turret to better
illustrate the components of the transmission assembly;
FIG. 7 is a perspective view of the tool turret separated from
the machining apparatus of FIG. 2 to better illustrate the driven
disc of each machine tool module supported thereon;
FIG. 8 is a side elevational view of the multi-disc drive system
of the machining apparatus of FIG. 2 with the intermediate drive
disc and associated drive screw shown in partial cross-section for
ease of illustration;
FIG. 9 is an enlarged localized view of the bearing assembly associated
with the intermediate drive disc and drive screw illustrated in
FIG. 8;
FIG. 10 is a side elevational view of the drive assembly of the
machining apparatus of FIG. 2 with the intermediate drive disc advanced
from the position shown in FIG. 8 to vary the rotational speed of
the driven disc;
FIG. 11 is a cross-sectional view taken along line 11--11 of FIG.
10 illustrating the geometric configuration of the protective shroud
of the main drive shaft; and
FIGS. 12-14 are schematic representations of the multi-disc drive
system of the machining apparatus of the subject invention, depicting
in sequential order, the axial translation of the intermediate drive
disc with respect to the driven disc to vary the relative rotational
speeds thereof wherein:
FIG. 12 illustrates the intermediate drive disc positioned adjacent
the outer periphery of the driven disc;
FIG. 13 illustrates the intermediate drive disc positioned between
the outer periphery and the rotational axis of the driven disc;
and
FIG. 14 illustrates the intermediate drive disc positioned adjacent
the rotational axis of the driven disc.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to the drawings wherein like reference numerals identify
similar structural elements of the subject invention, a machining
apparatus constructed in accordance with a preferred embodiment
of the subject invention is illustrated in FIG. 1 and is designated
generally by reference numeral 10. In brief, machining apparatus
10 includes a rotatable tool turret 12 having a plurality of modular
machine tools 14a-14h removably supported thereon (see FIG. 3).
A transmission assembly 18 is provided for effectuating the rotation
of tool turret 12 and a multi-disc variable-speed drive system 20
is provided for independently driving each of the modular machine
tools supported on the tool turret.
Referring now in detail to FIG. 1 machining apparatus 10 is preferably
employed in conjunction with a computer controlled automated work
station 22 having a superstructure 24 and a work holding platform
26 associated therewith. The work holding platform defines a planar
work surface configured to support a workpiece, such as, for example,
a piece of woodwork. The work surface may include conventional work
holding fixtures, such as, for example, clamping devices, or it
may be configured as a vacuum table (as shown) which utilizes suction
to maintain a particular workpiece in a desired location with respect
to the machining apparatus.
With continuing reference to FIG. 1 machining apparatus 10 includes
a main support housing 30 mounted on a carriage 32 which is adapted
to translate along a horizontal axis relative to work holding platform
26. Preferably, support housing 30 is mounted to translate relative
to carriage 32 along a vertical axis with respect to work holding
platform 26 to increase the operating range of the apparatus. Tool
turret 12 the components of transmission assembly 18 and the components
of the multi-disc drive system 20 are supported on housing 30 and
are discussed in greater detail hereinbelow.
Referring to FIGS. 2-6 the transmission assembly 18 of machining
apparatus 10 includes a conventional stepper motor 40 secured to
main support housing 30 by a mounting bracket 38. Stepper motor
40 drives a worm gear 42 supported in a journal bearing 43. Worm
gear 42 is meshed with a main drive gear 44 which drives a subordinate
coaxial pinion gear 46. Pinion gear 46 is meshed with a spur gear
48 which, in turn, is meshed with the circumferential teeth of tool
turret 12. Drive gear 44 and pinion gear 46 are mounted on a common
shaft 50 which depends from support housing 30 while spur gear
48 and tool turret 12 are mounted on parallel shafts 52 and 54
respectively. In operation, transmission assembly 18 effects the
indexed rotation of tool turret 12 in clockwise and counter-clockwise
directions, to align a selected one of the machine tools 14a-14h
with work holding platform 26.
With continuing reference to FIGS. 2-6 the multi-disc drive system
20 of machining apparatus 10 is preferably powered by a main a drive
motor 60 which is supported on a mounting bracket 62 secured to
support housing 30. Alternative power sources may be employed, such
as, for example, a combustion engine. A main drive shaft 64 extends
from drive motor 60 along an axis which is perpendicular to the
planar surface of work holding platform 26. Drive shaft 64 is enclosed
within a generally U-shaped protective shroud 65 which depends from
drive motor 60 (see FIG. 11).
As best seen in FIG. 4 drive system 20 includes a primary drive
disc 66 having an annular planar contact surface 66a and mounted
on the distal end of drive shaft 64. Drive disc 66 is positioned
to deliver power to an intermediate drive disc 68 which is mounted
for rotation about an axis extending perpendicular to the axis of
drive shaft 64. Intermediate drive disc 68 has a circumferential
peripheral contact surface 68a which preferably includes an elastomeric
contact material configured to frictionally engage the annular contact
surface 66a of primary drive disc 66. As discussed in greater detail
hereinbelow, intermediate drive disc 68 is configured to transfer
power from primary drive disc 66 to a selected one of the modular
machine tools 14a-14h supported on the tool turret 12 of machining
apparatus 10.
As illustrated in FIGS. 2-5 a plurality of machine tools 14a-14h
are removably supported on tool turret 12 and are arranged in circumferentially
spaced apart relationship. Preferably, tool turret 12 is configured
to accommodate eight machine tools. However, the number of machine
tools is limited only by the radial dimension of tool turret 12.
For purposes of illustration, machining apparatus 10 is depicted
with a rotary cutting saw 14a, two routing tools 14b and 14f, two
axial drilling tools 14c and 14g, a rotary sanding tool 14d, a right
angle drilling tool 14e, and an acute angle drilling tool 14h. It
will be readily appreciated by those having ordinary skill in the
art that the selection of machine tools supported on tool turret
12 will vary in dependence upon the machining operation or woodworking
task to be performed. Furthermore, the machine tool modules can
be selectively positioned with respect to one another to minimize
machining time by reducing the travel distance of tool turret 12
between tool changes.
As best seen in FIG. 7 a standardized mounting assembly is employed
to removably mount each tool module on tool turret 12. The mounting
assembly includes a support base 55 having a concave reception seat
56 for receiving a tool module, and a U-shaped securement bracket
57 for securing the tool module in reception seat 56. Conventional
threaded fasteners 58 are utilized to secure bracket 57 to support
base 55 as well as to secure each support base in any one of the
eight circumferentially arranged mounting positions on tool turret
12 as shown in FIG. 6.
Referring to FIGS. 5 and 7 each modular machine tool, regardless
or type or configuration, includes an identical driven disc 70 mounted
to rotate about an axis which is perpendicular to the axis of tool
turret 12. Each driven disc 70 has an annular planar contact surface
70a configured to interact with the circumferential peripheral contact
surface 68a of the intermediate drive disc 68 of drive system 20.
Thus, in operation, when tool turret 12 is rotated by transmission
assembly 18 to align a selected one of the machine tools 14a-14h
with a workpiece positioned on work platform 26 the annular surface
70a of the selected driven disc 70 is moved into frictional engagement
with the circumferential surface 68a of intermediate drive disc
68. Accordingly, the rotational motion of the primary drive disc
66 is transferred directly to the driven disc 70 via intermediate
disc 68.
In addition to transferring rotational motion from the primary
drive disc 66 to the driven disc 70 of a selected machine tool 14a-14h,
the intermediate drive disc 68 is configured to vary the rotational
speed of the driven disc 70 of a selected machine tool, and consequently,
the operating speed of the rotating tool element associated therewith.
More particularly, as illustrated in FIG. 8 intermediate drive
disc 68 is mounted to translate relative to the primary drive disc
66 and the driven disc 70 while remaining in frictional contact
with both, to vary the rotational speed of the driven disc 70.
Referring to FIG. 8 in conjunction with FIGS. 4 and 6 the axial
translation of intermediate drive disc 68 is effectuated by a linear
drive assembly 80 which includes a motor 82 an axial drive screw
84 and a threaded bearing collar 86. Motor 82 is supported on a
mounting bracket 88 which depends from shaft shroud 65. Drive screw
84 extends from motor 82 and is rotatably supported in a journal
bearing 90 mounted adjacent tool turret 12. Bearing collar 86 is
threadably engaged on drive screw 84 and is seated within an axial
aperture 92 defined in intermediate drive disc 68. As best seen
in FIG. 9 a plurality of ball bearings 94 are disposed between
the outer peripheral wall 96 of bearing collar 86 and the inner
peripheral wall 98 of aperture 92 to facilitate the axial rotation
of intermediate drive disc 68 as well as the linear translation
thereof. Those skilled in the art will readily appreciate that alternative
mounting arrangements may be utilized to facilitate the linear and
rotational movements of intermediate drive disc 68 relative to drive
screw 84.
As shown in FIGS. 8 and 10 when the driven disc 70 of one of the
selected machine tools 14a-14h is rotated into frictional engagement
with intermediate drive disc 68 the axis of rotation of the driven
disc 70 is offset from the axis of rotation of the primary drive
disc 66 by a predetermined distance. Preferably, the two discs are
axially offset such that the peripheral edge of the primary drive
disc 66 is aligned with the axis of the selected driven disc 70.
The determination of this distance effects the speed ratios between
drive disc 66 and the selected driven disc 70. It will be readily
appreciated by those having ordinary skill in the art that the specific
speed ratios between the drive disc and the driven disc will necessarily
depend upon the relative size of each component in the multi-disc
drive system.
Referring to FIGS. 12-14 in use, the rotational speed of a selected
driven disc 70 increases with respect to the rotational speed of
the primary drive disc 66 as the secondary drive member 68 translates
radially inwardly from the periphery of the driven disc toward the
axis of rotation thereof. For example, in a preferred embodiment
of the subject invention, when the peripheral contact surface 68a
of intermediate drive disc 68 is in frictional contact with the
outermost section of the annular contact surface 70a of driven disc
70 as illustrated in FIG. 12 the speed ratio between the drive
disc 66 and the driven disc 70 is approximately 4:3. Conversely,
when peripheral contact surface 68a is in frictional contact with
the innermost section of annular contact surface 70a, as illustrated
in FIG. 14 the speed ratio between the drive disc 66 and the driven
disc 70 is approximately 1:6. As illustrated in FIG. 13 other speed
ratios are achieved when intermediate drive disc 68 is in a location
between the axis of rotation of driven disc 70 and the outer periphery
thereof. Accordingly, the rotational speed of any driven disc, and
consequently any rotating tool element associated therewith, can
be selectively varied during a machining operation without effecting
the operating efficiency of the main drive motor 60. Moreover, the
main drive shaft 64 will remain in motion at all times during a
machining operation, delivering peak horsepower to the primary drive
disc 66 without interruption.
Although the machining apparatus of the subject invention has been
described with respect to a preferred embodiment, it is apparent
that modifications and changes can be made thereto without departing
from the spirit and scope of the invention as defined by the appended
claims. For example, it is envisioned that the frictional coupling
arrangement between the primary drive disc and the driven disc could
be replaced by an equivalent coupling arrangement, such as, a jaw-type
coupling arrangement or a cup-type coupling arrangement. Furthermore,
it is envisioned that the respective frictional contact surfaces
of the primary drive disc, the intermediate drive disc, and the
driven disc of each tool module, could have tapered geometries.
In such an instance, the intermediate drive disc would be configured
to translate on two distinct axes, one perpendicular to the axis
of rotation of the primary drive disc and the other parallel to
the axis of rotation of the primary drive disc. |