U.S. patent application number 12/414631 was filed with the patent office on 2009-08-06 for indexable table.
Invention is credited to Walter W. Wawrzyniak.
Application Number | 20090193638 12/414631 |
Document ID | / |
Family ID | 39168102 |
Filed Date | 2009-08-06 |
United States Patent
Application |
20090193638 |
Kind Code |
A1 |
Wawrzyniak; Walter W. |
August 6, 2009 |
Indexable Table
Abstract
A continuous tool rotation tool turret is comprised of a turret
head, a plurality of spindles and a motor. The spindles are
attached to the turret head. Each spindle is adapted to secure and
rotate a cutting tool. The motor simultaneously rotates each
spindle. The spindles rotate at an operational speed while the
turret head is being indexed. A bevel gear operationally connected
to the motor simultaneously rotates a bevel gear attached to each
spindle. Air pressure separates the turret head from its rest
surface during indexing. The turret head rotates around a manifold
which supplies coolant and pressurized air to the turret head.
Optionally, a mating wedge and wedge receptacle attached to the
turret head and its housing provide for more precise indexing of
the turret head. The continuous tool rotation minimizes the time
needed to index the turret from one position to another.
Inventors: |
Wawrzyniak; Walter W.;
(Saint Clair Shores, MI) |
Correspondence
Address: |
GREGORY T. ZALECKI
12900 HALL ROAD, SUITE 400
STERLING HEIGHTS
MI
48313
US
|
Family ID: |
39168102 |
Appl. No.: |
12/414631 |
Filed: |
March 30, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11935388 |
Nov 5, 2007 |
7509720 |
|
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12414631 |
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Current U.S.
Class: |
29/40 |
Current CPC
Class: |
B23Q 11/123 20130101;
B23B 29/32 20130101; Y10T 74/14 20150115; B23Q 1/70 20130101; Y10T
408/37 20150115; Y10T 29/5158 20150115; B23Q 39/024 20130101; B23Q
2220/002 20130101; Y10T 83/8732 20150401; Y10T 29/5155
20150115 |
Class at
Publication: |
29/40 |
International
Class: |
B23B 7/04 20060101
B23B007/04 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 4, 2008 |
IB |
PCT/IB2008/054601 |
Claims
1. An indexable table comprising: (a) a housing providing a support
surface and having an axis of rotation for a table; (b) a post
fixed to the housing, said post extending perpendicularly from the
support surface along said axis of rotation; (c) a table positioned
upon the support surface such that said table rotates about the
post; (d) said table being mechanically clamped to the support
surface; (e) said support surface being adapted to receive
pressurized air; and (f) said support surface being adapted to
direct the pressurized air to the interface between the table and
the support surface such that the pressurized air unclamps the
table from the support surface to permit low friction rotation of
the table about the axis of rotation of the support surface.
2. The indexable table of claim 1 wherein the pressurized air is
directed to the interface between the table and the support surface
by one or more air grooves within the support surface, said air
grooves being open at the table interface surface of the support
surface.
3. The indexable table of claim 1 wherein the air grooves are
segmented.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a division of U.S. patent application
Ser. No. 11/935,388 filed on Nov. 5, 2007, now pending, and PCT
application number PCT/IB2008/054601 filed on Nov. 4, 2008 with the
International Bureau of the World Intellectual Property
Organization, now pending, and priority is claimed as to the filing
dates of both applications. Both applications are incorporated
herein by reference.
BACKGROUND
[0002] This application is a division of U.S. patent application
Ser. No. 11/935,388 filed on Nov. 5, 2007, now pending.
[0003] Many automated machine tools use indexing tool turrets for
machining work pieces. The tool turrets contain a plurality of
cutting tools. The cutting tools are positioned upon the tool
turret such that only one tool is in an operational position at a
time. The remaining tools do not interfere with the machining
operation. After a machining operation (or operations) is performed
by the first tool, the tool turret is rotated or indexed to bring a
second cutting tool into an operational position. The objective is
to perform a series of machining operations upon a workpiece with a
plurality of cutting tools in a minimal time period. In prior art
tool turrets only the operational cutting tool rotates. The cutting
tools on the tool turret which are not involved in that machining
operation do not rotate. Thus, one of the steps involved in
indexing the tool turret from one position to another involves
stopping rotation of the operational cutting tool, indexing the
second cutting tool into an operational position and bringing the
second cutting tool up to an operating rotational speed. One of the
objectives of an automated machine tool using a tool turret is to
produce machined finished work pieces as quickly as possible with
minimal wear and tear upon the machine parts. A significant time
delay accompanies prior art tool turrets because of the time needed
to start and stop the cutting tools between tool turret indexings.
Additionally, the starting and stopping of the cutting tools causes
unnecessary wear and tear upon the machine parts. What is needed is
a tool turret having a plurality of spindles attached to cutting
tools wherein the tools continuously rotate and thereby avoid the
rotation start and rotation stop time delays. Also needed is a tool
turret with minimal friction between the tool turret and the
surface upon which it rests. This will provide for more precise
positioning of the tool turret, the need for less energy to rotate
the tool turret and less wear upon the tool turret and the surface
upon which it rests. Additional desirable features of an improved
tool turret include the supplying of coolant and pressurized air to
the tool turret and more precise positioning of the tool turret.
The coolant will allow turret spindles to rotate at a higher speed
and lower temperature with less wear. The pressurized air can be
used to prevent contaminants from entering areas between moving
parts of the tool turret and to remove contaminants which have
entered such areas. The continuous tool rotation tool turret
described herein meets these needs.
SUMMARY
[0004] The simplest embodiment of a continuous tool rotation tool
turret is comprised of a turret head, a plurality of spindles and a
motor. The turret head has an axis of rotation about which the
turret head rotates. Each spindle is attached to the turret head.
Each spindle is adapted to secure and rotate a cutting tool. The
motor is adapted to simultaneously rotate each spindle. The
spindles are adapted to rotate at an operational speed while the
turret head is being indexed. The spindles are sized, positioned
and angled with respect to the axis of rotation of the turret head
and the turret head such that only one spindle may be in a work
position at a time. The preferred angle between the axis of
rotation of each spindle and the axis of rotation of the turret
head is about 45.degree..
[0005] In a second improved embodiment, the turret head rests upon
a slant surface provided by a housing. The turret head is rotatable
upon the slant surface. The housing also provides a receptacle
within which a portion of the turret head is rotatably seated. A
post is attached to the housing. The post is perpendicularly
oriented with respect to the slant surface. The turret head
rotatably rests upon the slant surface and partially within the
receptacle of the housing such that the turret head has an axis of
rotation about which it rotates for indexing on the slant surface.
A fastener attached to the post clamps the turret head to the slant
surface. Preferably, the slant surface has one or more air grooves.
Each of the air grooves are connectable to a pressurized air
source. The grooves are open at the surface of the slant surface.
This permits the pressurized air to provide a force which tends to
unclamp the turret head from the slant surface of the housing.
[0006] The best mode of implementing continuous tool rotation
involves the use of bevel gears. A drive bevel gear is adapted to
rotate about the axis of the post. Each spindle has an input gear.
This input gear is a driven bevel gear. The motor is operationally
connected to the drive bevel gear such that it causes rotation of
the drive bevel gear about the axis of the post. The drive bevel
gear is engaged with each of the input driven bevel gears of the
spindles. This provides for simultaneous rotation of all spindles.
The spindles and gears are adapted such that the spindles rotate at
an operational speed while the turret head is being indexed. The
operational speed of the spindles can be controlled by the
selection of appropriate bevel gear teeth ratios and motor
rotational speed.
[0007] A manifold may be used to supply coolant and pressurized air
to the turret head. In this case the post has a supply coolant
passage, a return coolant passage and an air passage. The supply
coolant passage is connected at one end to the manifold and at the
other end to a coolant inlet for supplying coolant to the manifold.
The return coolant passage is connected at one end to the manifold
and at the other end to a coolant outlet for receiving coolant from
the manifold. The air passage is connected at one end to the
manifold and at the other end to an air inlet for supplying
pressurized air to the manifold. The manifold is attached to the
post. The manifold has a plurality of annular grooves along its
periphery. A first groove is connected to the supply coolant
passage of the post and is adapted to supply coolant to the turret
head. A second groove is connected to the return coolant passage of
the post and is adapted to return coolant from the turret head. A
third groove is connected to the air passage of the post and is
adapted to supply pressurized air to the turret head. The manifold
is shaped to permit rotation of the turret head about its
periphery. The turret head is adapted to receive supply coolant
from the manifold, to receive pressurized air from the manifold and
to return coolant to the manifold. Return coolant is coolant that
has previously been delivered to the turret head through the supply
coolant passage and, after absorbing heat, is carried away from the
turret head.
[0008] A servo motor is used to index the turret head into a
desired operational position. The servo motor has an output shaft
with a pinion gear. This pinion gear is engaged with a ring gear
attached to the turret head. Rotation of the pinion gear
repositions the turret head by causing rotation of the ring gear.
Optionally, a wedge locator system may be used for more precise
indexing of the turret head. The wedge locator system is comprised
of a plurality of first wedge locator members, an actuator and a
second wedge locator member. The first wedge locator members are
attached to the turret head. The actuator is adapted for extension
and retraction of a wedge locator member. An air cylinder may be
used as an actuator. The second wedge locator member is attached to
the actuator. The first wedge locator members and the second wedge
locator member are shaped to fit together as a wedge and a wedge
receptacle. Although the first wedge locator members are preferably
shaped as wedges and the second wedge locator member is preferably
shaped as a wedge receptacle, these shape assignments can be
transposed. The actuator is fixedly positioned with respect to the
turret head. The position of the actuator with respect to the
turret head, the position of each first wedge locator member upon
the turret head and the position of the second wedge locator member
with respect to the actuator are set such that a preselected
indexed position of the turret head results from the engagement of
the second wedge locator member with a first wedge locator
member.
[0009] The preferred embodiment of a continuous tool rotation tool
turret which indexes on a slant surface is comprised of a turret
head, a housing, a manifold, a manifold and clamp post, a plurality
of spindle assemblies, a drive bevel gear and a motor. The housing
provides a slant surface upon which the turret head rotatably rests
and a receptacle within which a portion of the turret head is
rotatably seated. The manifold and clamp post is attached to the
housing such that the post is perpendicularly oriented with respect
to the slant surface. The post has a supply coolant passage
connected at one end to the manifold and at the other end to a
coolant inlet for supplying coolant to the manifold. The post has a
return coolant passage connected at one end to the manifold and at
the other end to a coolant outlet for receiving coolant from the
manifold. The post also has an air passage connected at one end to
the manifold and at the other end to an air inlet for supplying
pressurized air to the manifold. The manifold end of the post is
adapted to receive a fastener for clamping the turret head to the
slant surface. The end of the post may be threaded and the fastener
may be a nut which fits the threads. The manifold is attached to
the post. The manifold has a plurality of annular grooves along its
periphery. A first groove is connected to the supply coolant
passage of the post and is adapted to supply coolant to the turret
head. A second groove is connected to the return coolant passage of
the post and is adapted to return coolant from the turret head. A
third groove is connected to the air passage of the post and is
adapted to supply pressurized air to the turret head. The manifold
should be provided with O-rings above and below the grooves for
preventing leakage of coolant or air. The manifold is shaped to
permit rotation of the turret head about the periphery of the
manifold. A cylindrically shaped manifold may be used.
[0010] The turret head rotatably rests upon the slant surface of
the housing such that the turret head has an axis of rotation about
which it rotates for indexing on the slant surface. A portion of
the turret head should be rotatably seated within the receptacle of
the housing. The turret head is clamped to the slant surface by a
fastener engaged with the manifold end of the post. In the
preferred embodiment the fastener is a nut engaged with threads on
the post. The nut is torqued such that it causes a desired clamping
force between the turret head and the slant surface. The turret
head is adapted to receive coolant from the manifold, to receive
pressurized air from the manifold and to return coolant to the
manifold. The turret head may be provided with holes to receive and
transmit these fluids.
[0011] The slant surface of the housing has one or more air
grooves. Each of the air grooves are connectable to a pressurized
air source and are open at the surface of the slant surface for
providing a force which tends to unclamp the turret head from the
slant surface of the housing. Preferably, the air grooves are
segmented such that they are isolated from each other. This
provides an unclamping force which is more evenly balanced about
the portion of the turret head which rests upon the slant surface.
The use of segmented air grooves also permits the use of a slant
surface and a mating surface on the turret head which have flatness
imperfections.
[0012] The spindle assemblies are attached to the turret head. Each
spindle assembly is comprised of a spindle housing, a spindle, a
toolholder and an input driven bevel gear. Each toolholder is
adapted to secure a tool and is attached to a spindle. An input
driven bevel gear is attached to each spindle for rotatably driving
that spindle. Each spindle assembly is adapted to secure and rotate
a cutting tool. Each spindle housing has a cooling jacket which is
adapted to receive supply coolant from the manifold and to return
coolant to the manifold for cooling the spindle assembly.
[0013] The drive bevel gear is adapted to rotate about the axis of
the post. The spindle motor is operationally connected to the drive
bevel gear for rotating the drive bevel gear about the axis of the
post. The drive bevel gear is engaged with each input driven bevel
gear. This provides for simultaneous rotation of all spindles. The
spindles and gears are adapted such that the spindles rotate at an
operational speed while the turret head is being indexed. Each
spindle has an axis of rotation about which a tool secured to the
spindle rotates. The angle between the axis of rotation of each
spindle and the axis of rotation of the turret head is less than
90.degree.. Preferably, it is about 45.degree.. The spindles are
sized, positioned and angled with respect to the axis of rotation
of the turret head and the turret head such that only one spindle
may be in a work position at a time. A spindle is in a work
position when it is indexed relative to the housing (e.g. the
bottom spindle of FIG. 1) into a position for the performance of a
machining operation upon the workpiece.
[0014] The preferred embodiment of the continuous tool rotation
tool turret which indexes on a slant surface is equipped with a
wedge locator system, as previously described.
[0015] This invention also includes a method for machining a
workpiece with a tool turret having a plurality of cutting tools.
In its simplest form, a machining operation is performed upon the
workpiece with a first cutting tool. The first cutting tool is then
backed away from the workpiece. A second cutting tool on the tool
turret is rotated into an operational position while the first
cutting tool continues to rotate at an operational speed.
Preferably, all of the cutting tools on the tool turret continue to
rotate at an operational speed. A machining operation is performed
upon the workpiece with the second cutting tool. The time required
to index the tool turret from one position to another is reduced
because delays caused by starting and stopping the cutting tools
are not encountered.
[0016] Additionally, this invention encompasses an indexable table
comprised of a housing, a post and a table. The housing provides a
support surface for the table. The housing has an axis of rotation
for the table. The post is fixed to the housing. It extends
perpendicularly from the support surface along the axis of
rotation. The table is positioned upon the support surface such
that it rotates about the post. The table is mechanically clamped
to the support surface. The table may be mechanically clamped to
the support surface by tightening a nut which is in contact with
the table and which is also threaded onto the post. The support
surface is adapted to receive pressurized air. The support surface
is also adapted to direct the pressurized air to the interface
between the table and the support surface such that the pressurized
air unclamps the table from the support surface. This will permit
the low friction rotation of the table about the axis of rotation
of the support surface. Low friction rotation of the table permits
the use of a lower degree of torque to rotate the table. The
pressurized air is directed to the interface between the table and
the support surface by one or more inner grooves within the support
surface. The air grooves are open at the table interface surface of
the support surface. Preferably, the air grooves are segmented for
the reasons described herein.
DRAWINGS
[0017] These and other features, aspects, and advantages of the
present invention will become better understood with regard to the
following description, appended claims, and accompanying drawings
where:
[0018] FIG. 1 is a side view of an automated machine tool using a
continuous tool rotation tool turret.
[0019] FIG. 2 is a top view of an automated machine tool using a
continuation tool rotation tool turret.
[0020] FIG. 3 is a top view of an automated machine tool having
five workstations which use continuous tool rotation tool
turrets.
[0021] FIG. 4 is a front elevation view of a three axis CNC slide
having a continuous tool rotation tool turret attached to it and
which is typical of a single workstation of the automated machine
tool of FIG. 3.
[0022] FIG. 5 is a side elevation sectional view of a continuous
tool rotation tool turret.
[0023] FIG. 6 is a broken away sectional view of the continuous
tool rotation tool turret of FIG. 5, showing the tool turret
unclamped from the slant surface of the housing.
[0024] FIG. 7 is a broken away sectional view of the continuous
tool rotation tool turret of FIG. 5, showing the bevel gear
engagement of a spindle, as well as coolant and air passages within
the post.
[0025] FIG. 8 is a sectional view of a continuous tool rotation
tool turret.
[0026] FIG. 9 is a top view of a continuous tool rotation tool
turret employing an alternate embodiment of a wedge locator
system.
[0027] FIG. 10 is a top view of the slant surface of a continuous
tool rotation tool turret housing showing segmented air grooves and
the alternate embodiment of the wedge locator system of FIG. 9.
[0028] FIG. 11 is a side elevation view of the servo motor, pinion
gear and ring gear of a continuous tool rotation tool turret.
[0029] FIG. 12 is a perspective view of a drive bevel gear shown in
engagement with four driven bevel gears from a plurality of spindle
assemblies.
[0030] FIG. 13 is a side elevation sectional view of a post gear
attached to a drive bevel gear wherein the post gear is rotatable
about a post and the drive bevel gear is shown in engagement with
two driven bevel gears of two spindles.
[0031] FIG. 14 is a top view of a turret head and a wedge locator
system, showing a spindle motor operationally connected to a post
gear through a belt driven pulling.
[0032] FIG. 15 is a side elevation sectional view of the wedge
locator system of FIG. 14 and of the turret head and housing of
FIG. 14.
[0033] FIG. 16 is a side view of a prior art tool turret and slant
surface overlaid upon a side view of a continuous tool rotation
tool turret and its slant surface.
[0034] FIG. 17 is a side view of a continuous tool rotation tool
turret wherein the tool turret is raised slightly above its
respective slant surface.
[0035] FIG. 18 is a side elevation view of a prior art tool turret
including a housing.
[0036] FIG. 19 is a side elevation view of a prior art tool turret
including a housing.
[0037] FIG. 20 is a side elevation sectional view of a continuous
tool rotation tool turret wherein the turret head is hatched to
distinguish the turret head from the manifold and the post.
[0038] FIG. 21 is a side elevation view of the manifold of a
continuous tool rotation tool turret.
[0039] FIG. 22 is a bottom view of the manifold of FIG. 21.
[0040] FIG. 23 is a side elevation sectional view of the manifold
of FIG. 21.
[0041] FIG. 24 is an enlarged view of the first O-ring groove of
the manifold of FIG. 21.
[0042] FIG. 25 is an enlarged view of the second O-ring groove of
the manifold of FIG. 21.
[0043] FIG. 26 is a top view of the slant surface of a housing of a
continuous tool rotation tool turret showing segmented air grooves,
a wedge locator system and an alternate drive mechanism for
rotating the post gear.
[0044] FIG. 27 is a side elevation view of the wedge locator system
of FIG. 14.
[0045] FIG. 28 is a top plan view of the wedge locator system of
FIG. 14.
[0046] FIG. 29 is a top plan view of the wedge locator system of
FIG. 14.
DESCRIPTION
[0047] The preferred use of the continuous tool rotation (during
index) tool turret 50 is in conjunction with an automated machine
tool 30 incorporating an index table assembly as described in my
U.S. Pat. No. 5,170,678. This patent is incorporated herein by
reference. The phrase continuous tool rotation, as used herein,
means that the tool 98 rotates at a substantially constant
operational speed irrespective of whether or not the turret 50 upon
which the tool 98 is mounted is rotating upon the housing 52 upon
which it rests, is stationary with respect to the housing 52, or
whether the tool 98 is about to perform a machining operation upon
a workpiece. Rotation of the tool turret 50 into an operational
position is also known as indexing. Thus, the term indexing of the
tool turret 50 and the phrase rotation of the tool turret 50 into
an operational position are synonymous, as used herein. A typical
application is illustrated within FIG. 3. There, an operator is
shown attending to the operation of an automated machine tool 30.
The automated machine tool 30 has five workstations 38. A machining
operation such as drilling, milling, reaming, tapping or boring may
be performed at each station 38. A workpiece to be machined is
secured to the index table 32. The workpiece is sequentially moved
from one station 38 to another by rotation of the index table 32.
At each station 38 one or more machining operations are performed.
The machining operations are performed by rotating tools 98
attached to spindles 92 contained within a continuous tool rotation
turret 50. At each station 38 a desired tool 98 is brought into a
work position by rotation of the continuous tool rotation tool
turret 50. The continuous tool rotation tool turret 50 is attached
to a three axis CNC slide 34. The three axis CNC slide 34 controls
and facilitates movement of the continuous tool rotation tool
turret 50 along three axes. Thus, a rotating cutting tool 98 may be
precisely positioned with respect to the workpiece and the depth
and contour of the cut performed by the tool 98 may be precisely
controlled. The depth and contour of the cut are controlled by the
movement of the three axis CNC slide 34. The timing and movement of
the three axis CNC slide 34 is programmably controlled. A
programmer programs a program module 36 to define the timing and
geometry of desired machining operations. After one set of
machining operations are performed at a station 38 by one cutting
tool 98, the continuous tool rotation tool turret 50 is backed away
from the workpiece and rotated/indexed so that another cutting tool
98 is in a work position. This cutting tool 98 is then used to
perform one or more machining operations. This process continues
until all machining operations to be performed by the tools 98
attached to the continuous tool rotation tool turret 50 at that
station are completed Once all machining operations are performed
at a given station 38 the index table 32 is rotated to move the
workpiece to another station 38. At that station 38 another series
of machining operations are performed. The process of machining at
each station 38 and rotating the workpiece on the index table 32 to
the next station 38 is repeated until all desired machining
operations are completed.
[0048] One of the objectives of this invention is to incorporate a
means of rotating all spindles 92 simultaneously using a single
spindle motor 110. A separate servo motor 80 is adapted to index
the tool turret 50 into a plurality of controlled positions while
the tools 98 are rotating. This continuous tool rotation minimizes
the time needed to complete an entire series of machining
operations upon a workpiece. Prior art automated machine tools do
employ the concept of sequentially rotating a plurality of tools
attached to a tool turret into a work position for the performance
of one or more machining operations. However, the tool rotation is
stopped and a clutch is disengaged before the tool turret is
rotated/indexed. Thus, a tool is brought into a work position, the
clutch is engaged and then the tool is brought from a stationary
state up to an operational rotation speed. Before the next tool is
brought into a work position, the rotation of the first tool is
stopped and the clutch is disengaged. This process of starting and
stopping the tool rotation and engaging and disengaging a clutch
before each rotation (indexing) of the tool turret has several
drawbacks. The starting and stopping of the tool rotation and
engaging and disengaging the clutch involves considerable time
delay. During this time delay no machining operations are being
performed and the tool turret is not being rotated (indexed). As a
result the automated machine tool is not being used at maximum
production efficiency. Additionally, the starting and stopping of
the tool rotation places considerable mechanical stress upon the
components of the tool turret and its rotatable tools. This
mechanical stress causes early machine failure and causes a need
for frequent machine maintenance. Prior art automated machine tools
with automatic tool changers also have to stop the spindle, move
into a tool change position, change the tools, and return to a work
position using more time and reducing the efficiency of the
machine. This invention minimizes the time needed to complete an
entire series of machining operations upon a workpiece by employing
the use of continuously rotating tools 98. The tools 98 continue to
rotate while the continuous tool rotation tool turret 50 rotates or
indexes from one position to another and while the index table 32
rotates the workpiece from one station 38 to another.
[0049] The preferred embodiment of a continuous tool rotation tool
turret 50 is comprised of a housing 52, a turret head 70, a
plurality of spindle assemblies 90 and a motor 110 for rotating the
spindles 92 within the spindle assemblies 90. A separate servo
motor 80 is adapted to rotate/index the turret head 70, as shown in
FIG. 11. The output shaft of the servo motor 80 is attached to a
pinion gear 84. A ring gear 82 is attached to the turret head 70.
The ring gear 82 and the pinion gear 84 are positioned such that
they mesh and such that rotation of the pinion gear 84 rotates the
ring gear 82 and indexes the turret head 70 into a preselected
position. The use of a single motor to rotate the spindles 92 and
to index the turret head 70 is also within the scope of this
invention. The continuous tool rotation tool turret 50 may be
provided with or without a housing 52. However, it will generally
be used in conjunction with a housing 52. The housing 52 is adapted
to be attached to a three axis CNC slide 34. For example, the
housing 52 may be adapted to be bolted to a three axis CNC slide
34. The housing 52 has a slant surface 54 upon which the turret
head 70 rests. The slant (rest) surface 54 is generally flat. The
turret head 70 rests upon the slant (rest) surface 54. The slant of
the slant (rest) surface 54 is shown in FIG. 5. That figure
illustrates a tool 98 and spindle 92 in a work position. The
rotational axis of the tool 98 and spindle 92 is depicted
horizontally. The slant surface 54 of the housing 52 is slanted
with respect to the rotational axis of the tool 98 and spindle 92
which are in a work position, as shown in FIG. 5. The slant of the
slant (rest) surface 54 permits one tool 98 and spindle 92 to be in
a work position while the remaining rotating tools 98 and rotating
spindles 92 attached to the turret head do not interfere with the
workpiece.
[0050] The turret head 70 is fabricated as a solid casting.
Preferably, it is cast from aluminum. The preferred diameter of the
turret head 70 is 20.5 inches, as measured at the part of the
turret head 70 which sits upon the slant surface 54 of the housing
52. As shown in FIG. 5, the turret head 70 has a plurality of
spindle housings 72. Each spindle housing 72 is in the shape of a
hollow cylinder extending from the turret head 70. The turret head
70 also has a manifold and clamp post opening 76. The turret head
70 rotates or indexes around a manifold and clamp post 120. The
manifold and clamp post 120 extends through the turret head 70. The
manifold and clamp post 120 is fixed to the housing 52. The
longitudinal axis of the manifold and clamp post 120 defines an
axis about which the turret head 70 rotates or indexes. Rotation of
the turret head 70 around the manifold and clamp post 120 is
facilitated by bearings 78 positioned at the interface between the
turret head 70 and the manifold and clamp post 120, as shown in
FIG. 5. As previously described, the turret head 70 is provided
with a ring gear 82. A servo motor 80 drives the ring gear 82 and
hence rotates the turret head 70 by way of a pinion gear 84, as
shown in FIG. 11. The servo motor 80 provides position and index
speed data feedback to the program module 36.
[0051] The manifold and clamp post 120 is provided with a manifold
121 at one end (the end distal to the slant surface 54 of the
housing 52 and proximal to the spindle housings 72, as shown in
FIG. 5). The manifold 121 is fixed with respect to the manifold and
clamp post 120. The turret head 70 is adapted to rotate around the
manifold clamp post 120 and the manifold 121. The manifold and
clamp post 120 and the manifold 121 supply coolant and pressurized
air to the turret head 70 and the spindle assemblies 90. They also
provide a means of clamping the turret head 72 to the slant (rest)
surface 54 through an adjustable nut 122. In the preferred
embodiment the adjustable nut 122 is tightened such that
approximately 2000 pounds of clamping force exists between the
turret head 70 and the slant surface 54. In an alternate embodiment
the adjustable nut 122 sits on top of a bevel washer. The bevel
washer acts as a spring. As it is compressed, its length along the
longitudinal axis of the post 120 shortens and a higher clamping
force is exerted upon the turret head 70. The bevel washer can be
distinguished from a flat washer by its semi conical shape. While a
flat washer remains in a single plane, the semi conical surface of
a bevel washer rises above the plane, thus making it ideal for use
as a pseudo spring. Under air pressure to the slant rest surface 54
the turret head 70 becomes a piston and offsets the clamp preload
force, unclamps, and the air is an air lubricant allowing the low
friction indexing of the turret head 70.
[0052] The manifold 121 is cylindrical in shape. The cylindrical
shape of the manifold 121 matches a cylindrical opening within the
turret head 70 such that the turret head 70 may rotate around the
manifold 12, but side to side movement of the turret head 70
relative to the longitudinal axis of the manifold 121 is prevented.
The manifold 121 is provided with a plurality of annular grooves
for supplying coolant and air to the turret head 70 and for
receiving O-rings, as shown in FIG. 21 and FIG. 23. The O-rings are
adapted to prevent air and coolant leakage outside of the turret
head 70--manifold 121 interface. The position of the grooves from
bottom to top (top being the end distal to the slant surface 54 of
the housing 52) is as follows. A first O-ring groove 123 is adapted
to receive an O-ring for coolant sealing. A first coolant groove
124 and a second coolant groove 125 are adapted to provide coolant
supply and coolant return paths. A second O-ring groove 126 is
adapted to receive an O-ring for coolant and air sealing. An air
groove 128 is adapted to provide a pressurized air supply to the
turret head 70. A third O-ring groove 127 is adapted to receive an
O-ring for air sealing. The manifold clamp and post 120 is provided
with an air passage 131 and two coolant passages 132, as shown in
FIG. 5. The air passage 131 is supplied with pressurized air. The
coolant passages 132 provide coolant supply and coolant return
paths. The air passage 131 feeds pressurized air to the air groove
128 of the manifold 121 through an air opening 134 within the air
groove 128 of the manifold 121. The coolant passages 132 supply and
receive return coolant via the coolant grooves 125, 126 of the
manifold 121 through coolant openings 135 within the coolant
grooves 125, 126 of the manifold 121. Coolant and air are
transmitted from the manifold 121 to the turret head 70 through
openings within the turret head 70.
[0053] When it is desired to index the turret head 70, the turret
head 70 is lifted from the slant surface 54 of the housing 52 by a
cushion of pressurized air. In the preferred embodiment the slant
surface 54 is ring shaped, as shown in FIG. 5 and FIG. 10. A
central cavity within the housing 52 provides a cup shaped
receptacle for rotatably supporting and positioning the turret head
70. A wall 56 located at the radial edge of the central cavity
steps upward, as shown in FIG. 5 and FIG. 6, to form the side of
the turret head 70 receptacle. The slant surface 54 is ring shaped
and is located at the circumferential periphery of the housing 52.
The bottom of the turret head 70 receptacle has a circular shape. A
bottom central portion of the turret head 70 is shaped to rotatably
fit within the cup shaped receptacle, while the bottom peripheral
portion of the turret head 70 is shaped to mate with the ring
shaped slant surface 54, as shown in FIG. 5 and FIG. 6.
[0054] Preferably, the surface of the ring shaped portion of the
slant surface 54 is provided with a plurality of arc shaped first
segmented air grooves 152. FIG. 10 shows the slant surface 54 with
six segmented air grooves 152. Each segmented air groove 152 may
receive pressurized air through an air feed 150. Each air feed 150
is adapted to provide pressurized air to a first segmented air
groove 152 and a second segmented air groove 154 through an air
channel 156. The second segmented air grooves 154 are
circumferentially positioned along the wall 56 connecting the slant
surface 54 to the bottom of the turret head 70 receptacle within
the housing 52, as shown in FIG. 6. When pressurized air enters the
air grooves 152, 154 it exerts a force normal to each pressurized
groove 152, 154 opening. The force from the first segmented air
grooves 152 tends to lift the turret head 70 from the slant surface
54. The force from the second segmented air grooves 154 tends to
separate the turret head 70 from the wall 56 connecting the bottom
of the turret head receptacle 58 within the housing 52 to the slant
surface 54. The pressurized air emanating from the second segmented
air grooves 154 also purges any contaminants entering the area
between the wall 56 and the turret head 70. The air grooves 152,
154 are not required to be segmented. However, segmentation
provides a better balancing of the lifting and separating forces
provided by the pressurized air to the turret head 70. The use of
segmented air grooves 152 also permits the use of a slant surface
54 and a mating surface on the turret head 70 which have flatness
imperfections.
[0055] When it is desired to rotate or index the turret head 70,
pressurized air is supplied to the air feeds 150. The pressurized
air supplied to the first segmented air grooves 152 tends to lift
the turret head 70 from the slant surface 54. The pressurized air
supplied to the second segmented air grooves 154 tends to separate
the turret head 70 from the turret head receptacle walls 56 and to
purge the area of contaminants, as previously described. The
optimal degree of lift between the turret head 70 and the slant
surface 54 is about 0.0005 inches. For my initial prototype this
degree of lift can be obtained within air pressure of about 70
psig. Once the turret head 70 is rotated into the desired position,
the air pressure is removed and the turret head 70 becomes seated
onto the slant surface 54. Appropriate air bleeds may be employed
to ensure complete seating of the turret head 70 to the slant
surface 54.
[0056] The combination of the turret head 70 airlift system and the
turret head indexing system (comprised of the servo motor 80, the
ring gear 82 and the pinion gear 84) positions the turret head 70
and operational spindle assembly 90 with sufficient accuracy for
many machining operations. Additional accuracy of the positioning
of the turret head 70 for an impending machining operation may be
obtained with the use of a wedge locator system 160 attached to the
housing 52 and the turret head 70. The wedge locator system 160 is
shown in FIGS. 14-15 and 26-29. The wedge locator system 160 is
comprised of an air cylinder 162, an air cylinder bracket 164, a
wedge locator 166 and a plurality of wedge assemblies 168. Each
wedge assembly 168 is comprised of a wedge 170 and an alignment
dowel 172. An air cylinder 162 is attached to the housing 52 by way
of an air cylinder bracket 164. The air cylinder 162 and air
cylinder bracket 164 are positioned proximal to a spindle assembly
90 which is not about to perform a machining operation, as shown in
FIG. 14. The air cylinder 162 contains a wedge locator 166. The
wedge locator 166 moves along the longitudinal axis of the air
cylinder 162 in response to pressurized air being supplied to the
air cylinder 162. When the air cylinder 162 is not supplied with
pressurized air, the wedge locator 166 is in a retracted position
and does not interfere with rotation of the turret head 70. When
the air cylinder 162 is supplied with pressurized air, the wedge
locator 166 extends into an extended position and mates with a
wedge 170 which is fixed to the turret head 70. The turret head 70
contains a plurality of wedges 170. When the wedge locator 166
mates with a wedge 170 the wedge locator system 160 does not
interfere with a machining operation to be performed by a cutting
tool 98 within a spindle assembly 90 which is in an operational
position. Each wedge assembly 168 is comprised of a wedge 170 and
an alignment dowel 172. The turret head 70 contains dowel alignment
holes within which the dowel 172 of a wedge assembly 168 is seated.
Each wedge 170 is attached to a the turret head 70. Each wedge 170
contains an alignment dowel 172 and bolt openings. The turret head
70 dowel alignment holes are positioned such that they will
facilitate accurate positioning of the turret head 70 prior to the
beginning of a machining operation. The wedge assemblies 168 are
attached to the turret head 70 with bolts 176 while their
respective alignment dowels 172 are positioned within the dowel
openings of the turret head 70. Each wedge 170 is in the shape of a
wedge. Each wedge locator 166 is in the shape of an opening adapted
to receive a wedge 170. Thus, when a wedge locator 166 extends onto
a mating wedge 170 the longitudinal axis of the wedge locator 166
and the longitudinal axis of the wedge 170 align. This provides an
additional degree of accuracy when positioning the turret head 70
with respect to a workpiece prior to the beginning of a machining
operation upon the workpiece. The wedge locator system 160 is used
while the turret head 70 is separated from the slant surface 54 of
the housing 52 by pressurized air. The preferred angle between the
faces of each wedge 170, as well as the faces of the wedge locator
166, is approximately 30.degree..
[0057] The use of pressurized air to lift the turret head 70 has
several advantages compared to prior art rotatable turret heads
which do not use an airlift. The friction between the turret head
70 and the slant surface 54 is significantly reduced. Therefore,
the turret head 70 and the slant surface 54 are subjected to less
wear for a given number of rotations. This reduces the need for
repair, replacement and maintenance to the turret head 70 and the
housing 52. Since the turret head 70 rests upon the slant surface
54, rather than upon bearings, a more precise and repeatable
positioning of the turret head 70 is obtained. Bearing wear is not
a factor in the precision and accuracy of the turret head 70
positioning. The minimized friction between the turret head 70 and
the slant surface 54 also facilitates a quicker movement of the
turret head 70 from one indexed positioned to another.
[0058] The spindle housings 72 each contain a spindle assembly 90.
Each spindle assembly 90 is comprised of a spindle 92, a tool
holder 94 and an input gear 96. The tool holder 94 is attached to
one end of the spindle 92. It is adapted to securely hold a tool
98. The input gear 96 is attached to the other end of the spindle
92. A motor 110 rotatably drives the spindle 92. The motor 110
simultaneously drives all of the spindles 92 through a post gear
146. This is to be distinguished from the prior art wherein
typically the motor drives only one spindle at a time through a
clutch and wherein rotation of the spindles ceases and the clutch
is disengaged before indexing or rotation of the turret. The
spindle motor 110 may directly drive the post gear 146.
Alternatively, the spindle motor may indirectly drive the post gear
146 through a belt driven pulley, as shown in FIG. 14.
[0059] Figures and 12-13 depict the method for obtaining continuous
tool rotation. Continuous tool rotation is obtained by driving the
spindles 92 with bevel gears 140. The reference number 140 is used
herein to generally designate all bevel gears. Additional reference
numbers such as 142, 144, 145 and 147 are used to designate
particular types of bevel gears. A post gear 146 is adapted to
rotate around the lower end of the manifold post 120. The post gear
146 is shown in FIG. 13. Bearings facilitate rotation of the post
gear 146 around the manifold post 120. The post gear 146 has an
upper end and a lower end. A lower end driven post gear 147 extends
from the lower end of the post gear 146. The lower end driven post
gear 147 is a bevel gear which extends from the lower end of the
post gear 146. The lower end driven post gear 147 meshes with a
motor driver gear 145. The motor driver gear 145 is a bevel gear.
It is attached to the output shaft of the spindle motor 110.
Alternatively, the motor driver gear 145 is attached to the output
shaft of a pulley driven by the spindle motor 110. When the output
shaft of the spindle motor 110 rotates the motor driver gear 145
rotates the post gear 146 by transmitting a rotational force to the
lower end driven post gear 147. The upper end of the post gear 146
is provided with a drive bevel gear 142. In Figure the 13 the upper
end of the post gear 146 is actually a separate bevel gear which is
made integral with the remainder of the post gear 146 by being
physically attached to it with bolts, as shown in the figure. The
drive bevel gear 142 meshes with each of the spindle driven bevel
gears 96, 144. Thus, rotation of the motor driver gear 145 causes
simultaneous rotation of each spindle driven bevel gear 96, 144. As
can be seen from FIG. 12, the spindle driven bevel gears 96, 144
may simultaneously rotate irrespective of whether the turret head
70 is stationary or rotating.
[0060] Because the drive bevel gear 142 meshes with each driven
bevel gear 96, 144 contained within the spindle assemblies 90 of
the turret head 70 continuous tool rotation is obtained. The tools
98 continue to rotate when the turret head 70 is indexed or
rotated. Therefore, time is not lost due to the starting and
stopping of tool rotation and due to engaging and disengaging a
clutch between the turret head 70 indexings. The production rate
for finished workpieces is increased because the machining
operations performed upon the workpieces occur at a faster
rate.
[0061] The preferred angle between the axis of rotation of each
spindle 92 and the longitudinal axis of the manifold and clamp post
120 is 45.degree.. This permits one spindle assembly 90 to be in a
work position while the remaining spindle assemblies 90 avoid
interference with the workpiece. Each spindle assembly 90 is
mounted within a spindle housing 72 of the turret head 70. Bearings
100 permit the spindle 92 to rotate within the spindle housing
72.
[0062] Prior art turrets typically use separate bolt on spindle
assemblies. In the preferred embodiment of this invention the
spindle assemblies 90 are fit within a spindle housing 72 which is
integral with the turret head 70. This invention also encompasses
embodiments which use separate bolt on spindle assemblies. The
distances between the end of the work tool and the housing rest
surface of prior art turrets is larger than the distance between
the end of the work tool 98 and the slant rest surface 54 of the
device described herein. This can be seen from FIGS. 16, 18 and 19.
FIG. 16 shows a prior art turret overlaid upon a drawing showing
the turret discussed herein. This invention permits the use of
higher tool thrust forces with larger bearings than the prior art
devices.
[0063] A coolant jacket 74 is embedded within the turret head 70
and surrounds each spindle assembly 90, as shown in FIG. 5. A
cooling system is provided which circulates a liquid coolant
through the cooling jackets 74. While the spindles 92 are rotating
and especially while the tools 98 are performing a machining
operation a high degree of heat is produced at the spindle
assemblies 90. The coolant carries this heat away from the spindle
assemblies 90 and the turret head 70. Therefore, the spindle
assemblies 90 operate at a lower temperature compared to what the
temperature would be if there were no circulating coolant. The
spindles can be rotated at a higher speed because of the reduced
temperatures caused by the coolant. Additionally, the reduced
spindle assembly 90 temperatures increase the life expectancy of
the spindle assemblies 90 and increase the time between required
spindle assembly 90 maintenance operations.
[0064] The preferred use of a continuous tool rotation tool turret
50 is in conjunction with an index table 32 and one or more three
axis CNC slides 34. However, the continuous tool rotation tool
turret 50 can be used without an index table 32 or a three axis CNC
slide 34. Two typical work set ups are shown in FIGS. 1-3. FIG. 1
and FIG. 2 show an index table 32 with a single workstation 38 and
two workpiece fixtures. The continuous tool rotation tool turret 50
is shown mounted to a three axis CNC slide 34. The three axis CNC
slide 34 is aligned with the index table 32 such that machining
operations may be performed upon a workpiece attached to a
workpiece fixture of the index table 32. FIG. 3 shows a similar set
up with five workstations 38. A program module 36 controls the
position of the index table 32, the three axis CNC slide 34 and the
spindle assemblies 90 (i.e. rotational/index position of the turret
head 70). In each set up the program module 36 is appropriately
programmed. The program determines the timing and position of the
workpiece. It also controls the speed of the cutting tools 98, the
position of the spindle assemblies 90 with respect to the housing
52 and the position of the spindle assemblies 90 with respect to
the workpiece. The index table 32 is programmed (by way of the
program module 36) to position a workpiece in a work position.
[0065] In order to perform a machining operation a workpiece is
brought into position for machining. Prior to machining all of the
cutting tools 98 on the turret head are brought to an operational
speed. The turret head 70 indexes (or rotates) one of the spindle
assemblies 90 into an operational position. In response to
programming, the operational spindle 92 and cutting tool 98 perform
a machining operation, such as drilling, milling, reaming, tapping
or boring, upon the workpiece. After the machining operation is
completed, the turret head 70 is backed away from the workpiece.
The spindles 92 continue to rotate at an operational speed.
Pressurized air is supplied to the air feeds 150. This unclamps the
turret head 70 from the slant surface 54 of the housing 52.
Ideally, the turret head 70 is separated from the slant surface 54
by a cushion of air. The turret head 70 is then rotated or indexed
such that the next desired spindle assembly 90 and cutting tool 98
are brought into a work position. If the continuous tool rotation
tool turret 50 is equipped with a wedge locator system 160, the air
cylinder 162 is activated. This causes the wedge locator 166 to
mate with a wedge 170 attached to the turret head 70. The mating of
the wedge locator 166 with the wedge 170 facilitates more precise
positioning of the operational cutting tool 98 with respect to the
housing 52 and, more importantly, the workpiece. After the spindle
assembly 90 is accurately positioned with respect to the housing 52
and the workpiece, air pressure is removed from the air feeds 150.
As a result, the turret head 70 becomes clamped into the proper
desired position. At all times during the machining process the
spindles 92 continuously rotate. This continuous rotation of the
spindles 90 permits the turret head 70 to be indexed from position
to position much quicker, and with much less wear on the moving
parts, as compared to prior art tool turrets.
[0066] Although the invention has been shown and described with
reference to certain preferred embodiments, those skilled in the
art undoubtedly will find alternative embodiments obvious after
reading this disclosure. With this in mind, the following claims
are intended to define the scope of protection to be afforded the
inventor, and those claims shall be deemed to include equivalent
constructions insofar as they do not depart from the spirit and
scope of the present invention.
* * * * *