ENSEMBLE A PLATEAU TOURNANT

INDEX TABLE ASSEMBLY

Abrégé anglais

An index table structure and method of indexing where
the index table structure includes a table having a table top
which is angularly rotatable and has a plurality of cam members
around the periphery thereof including radially outwardly opening
cam recesses therein having a precisely located indexed position
locating surface, a dual motor brake structure for driving the
portion of the table between angularly separated indexed
positions, a shot pin positioned adjacent the periphery of the
table top and having a precisely indexed position locating
surface thereon adapted to mate with a locating surface of a cam
recess with the indexed table top in a precisely indexed
position, a fluid cushion structure for providing a fluid
cushion for the rotatable table top and means for holding the
shot pin in engagement with the locating surface in the
associated cam recess the rotatable table top in rotation being
released and floated on a fluid cushion and rotated in one
direction whereby the shot pin is cam actuated into one of the
cam recesses to approximately locate the table top in an
indexed position and subsequently the table top is rotated in
the opposite direction to engage the locating surfaces on the
shot pin and the cam recess to precisely locate the table top
in one of its indexed positions and to wedge lock the shot pin
to prevent the table top from rotating out of position.

Revendications

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. An index table assembly comprising an index table
having an axis of rotation, drive means connected to said index
table for driving said index table in one direction about said
axis of rotation and stopping said index table at a first
position proximate to but past a preselected indexed position of
said index table and sensing means operably associated with said
index table for sensing the location of said index table at said
first position and providing a signal to said drive means, said
drive means responsive to said signal for subsequently driving
said index table in a direction about said axis of rotation of
said index table opposite said one dire<aion and stopping said
index table precisely at said preselected indexed position.
2. The index table assembly of claim 1 further including
lift means operably associated with said index table for lifting
said index table on a fluid medium cushion during rotation of
said index table for producing substantially friction free
rotation of said index table about said axis of rotation.
3. The index table assembly of claim 1 further including
holding means operably associated with. said index table for
holding said index table at said preselected indexed position.
4. An index table assembly comprising an index table
having an axis of rotation about which said index table may be
rotated to preselected indexed positions, guide means for
guiding said index table in rotation about said axis of
rotation, cam means comprising a plurality of cam members
22

secured to the periphery of said index table at said preselected
indexed positions, each of said cam members having a radially
extending, outwardly opening recess therein Including a first
locating surface, said cam means further comprising a shot pin
positioned adjacent the periphery of said index table having a
second locating surface thereon and engageable with said first
locating surface of each of said cam members on rotation of said
index table for sequentially locating said index table in each
of said preselected indexed positions, drive means for driving
said index table in one direction about said axis of rotation,
and for stopping said index table at a first position proximate
to but past one of said preselected indexed positions with said
shot pin extending into said recess in said one of said cam
members of said cam means and sensing means operably associated
with said index table for sensing the location of said index
table at said first position and providing a signal to said
drive means, said drive means responsive to said sensed signal
for driving said index table in the opposite direction to
position said second locating surface on said shot pin against
said first locating surface of said recess to precisely position
said index table in the associated one of said indexed
positions.
5. The index table assembly of claim 4 wherein said index
table has an open center.
6. The index table assembly of claim 4 further including
bearing means in the center of said index table for supporting
a tool structure on said index table.
23

7. An index table assembly comprising an index table
having an axis of rotation about which said index table may be
rotated to preselected indexed positions, guide means for
guiding said index table in rotation about said axis of
rotation, cam means comprising a plurality of cam members
secured to the periphery of said index table at said preselected
indexed positions, each of said cam members having a radially
extending, outwardly opening recess therein including a first
locating surface, said cam means further comprising a shot pin
positioned adjacent the periphery of said index table having a
second locating surface thereon and engageable with said first
locating surface of each of said cam members on rotation of said
index table for sequentially locating said index table in each
of said preselected indexed positions, drive means for driving
said index table in one direction about said axis of rotation,
and for stopping said index table at a first position proximate
to but past one of said preselected indexed positions with said
shot pin extending into said recess in said one of said cam
members of said cam means and sensing means operably associated
with said index table for sensing the location of said index
table at said first position and providing a signal to said
drive means, said drive means responsive to said sensed signal
for driving said index table in the opposite direction to
position said second locating surface on said shot pin against
said first locating surface of said recess to precisely position
said index table in the associated one of said indexed
positions, said guide means includes separate centering pads
24

positioned angularly about said axis of rotation of said index
table and each of said centering pads being separately moveable
relative to said axis of rotation of said index table.
8. The index table assembly of claim 4 wherein said drive
means comprises a ring gear secured to said index table, pinion
means in engagement with said ring gear and a combination motor,
brake means for driving and stopping said pinion means.
9. The index table assembly of claim 4 wherein said drive
means includes separate motors for driving said index table in
said one and said opposite directions.
10. The index table assembly of claim 4 further including
support means for supporting said index table during rotation
about said axis of rotation for reducing friction tending to
retard the rotation of said index table.
11. The index table assembly of claim 10 with said support
means providing a cushion of fluid medium for said index table.
12. The index table assembly of claim 11 wherein said
fluid medium is selected from a group comprising air and oil and
with said support means providing the cushion in separate
angular segments about said axis of rotation of said index
table.
13. The index table assembly of claim 4 including holding
means for holding said index table in said precise indexed
positions.
14. An index table assembly comprising an index table
having an axis of rotation about which said index table may be
rotated to preselected indexed positions, guide means for
25

guiding said index table in rotation about said axis of
rotation, cam means comprising a plurality of cam members
secured to the periphery of said index table at said preselected
indexed positions, each of said cam members having a radially
extending, outwardly opening recess therein including a first
locating surface, said cam means further comprising a shot pin
positioned adjacent the periphery of said index table having a
second locating surface thereon and engageable with said first
locating surface of each of said cam members on rotation of said
index table for sequentially locating said index table in each
of said preselected indexed positions, drive means for driving
said index table in one direction about said axis of rotation,
and for stopping said index table at a first position proximate
to but past one of said preselected indexed positions with said
shot pin extending into said recess in said one of said cam
members of said cam means and sensing means operably associated
with said index table for sensing the location of said index
table at said first position and providing a signal to said
drive means, said drive means responsive to said sensed signal
for driving said index table in the opposite direction to
position said second locating surface on said shot pin against
said first locating surface of said recess to precisely position
said index table in the associated one of said indexed
positions, holding means for holding said index table in said
precise indexed positions, said holding means includes a wedge
and actuating means for actuating said wedge with said index
table in said precise indexed positions.
26

Description

_ 20313U~U
INDEX TABLE ASSEMBLY
SUMMARY BACKGROUND OF THE INVENTION
The invention relates to index table assemblies for
machine tools and the like and more specifically to an index
table assembly having an actuating mechanism for rotating an
index table to a plurality of positions and quickly and
accurately locating the index table at each position.
In the past, index table assemblies have been such that
the associated index tables have normally been rotated in only
one direction between indexed positions. Such index table
assemblies require that the index table be precisely stopped in
the desired indexed position; yet it is desirable that the table
be rotated at a relatively high rate of speed for as long as
possible to decrease the indexing time between indexed positions.
At the same time the rotational velocity of the index table often
is prematurely reduced in order to prevent overshoot. In
addition, rapid deceleration and abrupt stops can put high
stresses on the actuating mechanism of the index table assembly,
which may result in improper indexing and/or in early failure of
the operative parts.
With prior index table assemblies, the index table has
often been supported on roller bearings or the like to relieve
friction between the index table and the supporting structure to
permit indexing of the table with a conventional drive structure.
Such bearings are in permanent contact with the table and may not
provide a steady base for such index tables at their indexed
positions. Further, such bearings are subject to wear and thus
1

- 2~~~.~~~D
require periodic checking and adjustment or replacement if the
required accuracy of most index tables is to be maintained.
Also, some prior index table assemblies have not been
provided with a structure for holding the table in an indexed
position other than the structure required for initially
positioning the index table in the indexed position. In this
regard it has been known to use a shot pin assembly to hold the
index tables in the desired positions. But such shot pin
assemblies were not securely locked and could loosen resulting
in inaccurate positioning. Maintaining such prior index tables
in their indexed positions has thus been less secure than
desirable. Where a separate assembly for holding prior index
tables in indexed positions has been provided, it often has been
internally buried in the index table structure so as not to be
readily available for maintenance or inspection.
In the present invention the index table is rapidly
rotated in one direction towards an indexed position. The
actuation of table rotation is stopped near that position with
the table slightly overshooting that position. Next the index
table is rotated the short distance in the opposite direction to
a precise indexed position and is locked in that indexed
position. To facilitate rotation and minimize friction the index
table is floated on a fluid medium such as air or oil.
In the present invention the index table assembly
permits ease of adaptability to different sized tables. At the
same time the index table assembly provides means for readily
changing or selecting the number of stations to be served.
2
f

CA 02031300 2001-09-13
In accordance with one aspect of the invention, there
is provided an index table assembly comprising an index table
having an axis of rotation, drive means connected to the index
table for driving the index table in one direction about the
axis of rotation and stopping the index table at a first
position proximate to but past a preselected indexed position of
the index table. Sensing means are operably associated with the
index table for sensing the location of the index table at the
first position and providing a signal to the drive means. The
drive means is responsive to the signal for subsequently driving
the index table in a direction about the axis of rotation of the
index table opposite the one direction and stopping the index
table precisely at the preselected index>ed position.
In accordance with another aspect of the invention,
there i.s provided an index table assembly comprising an index
table having an axis of rotation about which the index table may
be rotated to preselected indexed positions, guide means for
guiding the index table in rotation about the axis of rotation,
cam means comprising a plurality of cam members secured to the
periphery of the index table at the preselected indexed
positions, each of the cam members having a radially extending,
outwardly opening recess therein including a first locating
surface, the cam means further comprising a shot pin positioned
adjacent the periphery of the index table having a second
locating surface thereon and engageable with the first locating
surface of each of the cam members on rotation of the index
table for sequentially locating the indE=_x table in each of the
preselected indexed positions, drive means for driving the index
table in one direction about the axis of rotation, and for
stopping the index table at a first po:>ition proximate to but
past one of the preselected indexed positions with the shot pin
extending into the recess in the one of the cam members of the
cam means and sensing means operably associated with the index
table for sensing the location of the index table at the first
position and providing a signal to the drive means, the drive
means responsive to the sensed signal for driving the index
- 2a -

CA 02031300 2001-09-13
table in the opposite direction to position the second locating
surface on the shot pin against the first locating surface of
the recess to precisely position thE; index table in the
associated one of the indexed positions..
According to a further object of the invention, there is
provided an index table assembly comprising an index table
having an axis of rotation about which the index table may be
rotated to preselected indexed positions, guide means for
guiding the index table in rotation about the axis of rotation,
cam means comprising a plurality of cam members secured to the
periphery of the index table at th~~ preselected indexed
positions, each of the cam members having a radially extending,
outwardly opening recess therein including a first locating
surface, the cam means further comprising a shot pin positioned
adjacent the periphery of the index table having a second
locating surface thereon and engageable with the first locating
surface of each of the cam members on rotation of the index
table for sequentially locating the index table in each of the
preselected indexed positions, drive means for driving the index
table in one direction about the axis of rotation, and for
stopping the index table at a first po:>ition proximate to but
past one of the preselected indexed positions with the shot pin
extending into the recess in the one of the cam members of the
cam means and sensing means operably associated with the index
table for sensing the location of the iizdex table at the first
position and providing a signal to the drive means, the drive
means responsive to the sensed signal for driving the index
table in the opposite direction to position the second locating
surface on the shot pin against the first locating surface of
the recess to precisely position the index table in the
associated one of the indexed positions, the guide means
includes separate centering pads positioned angularly about the
axis of rotation of the index table ancL each of the centering
pads being separately moveable relative to the axis of rotation
of the index table.
- 2b -

CA 02031300 2001-09-13
In yet another aspect of the invention, there is
provided an index table assembly comprising an index table
having an axis of rotation about which the index table may be
rotated to preselected indexed positions, guide means for
guiding the index table in rotation about the axis of rotation,
cam means comprising a plurality of cam members secured to the
periphery of the index table at the preselected indexed
positions, each of the cam members having a radially extending,
outwardly opening recess therein including a first locating
surface, the cam means further comprising a shot pin positioned
adjacent the periphery of the index table having a second
locating surface thereon and engageable with the first locating
surface of each of the cam members on rotation of the index
table for sequentially locating the indE:x table in each of the
preselected indexed positions, drive means for driving the index
table in one direction about the axis of rotation, and for
stopping the index table at a first position proximate to but
past one of the preselected indexed positions with the shot pin
extending into the recess in the one of the cam members of the
cam means and sensing means operably associated with the index
table for sensing the location of the index table at the first
position and providing a signal to the drive means, the drive
means responsive to the sensed signal for driving the index
table in the opposite direction to position the second locating
surface on the shot pin against the first locating surface of
the recess to precisely position the index table in the
associated one of the indexed positions, holding means for
holding the index table in the precise indexed positions, the
holding means includes a wedge and actuating means for actuating
the wedge with the index table in the precise indexed positions .
- 2c -

Therefore, it is an object of the present invention to
provide a unique index table assembly whereby the associated
table can be quickly rotated towards and past its desired
position and then reverse rotated a short distance and precisely
located at the desired points.
It is another object of the present invention to
provide a unique index table assembly which facilitates the use
of different sized tables and also facilitates the selection of
various indexing locations.
It is still another object of the present invention to
provide a unique index table assembly in which the rotating table
is suspended on a fluid (liquid or air) cushion to reduce
friction and facilitate rotation.
Other objects, features, and advantages of the present
invention will become apparent from the subsequent description
and the appended claims, taken in conjunction with the
accompanying drawings. .
FIG. 1 is a fragmentary side elevational view with some
parts shown in section and other parts shown broken away of the
index table assembly of the present invention;
FIG. 2 is a fragmentary top elevational view of the
index table assembly of FIG. 1, taken substantially in the
direction of arrow 2 in FIG. 1;
FIG. 3 is a fragmentary, sectional view with some parts
shown broken away of the index table assembly of FIG. 1, taken
substantially in the direction of the arrows 3-3 in FIG. 2:
3

FIG. 4 is a fragmentary, sectional view of a manifold
structure for a modified form of the index table assembly of FIG.
1:
FIG. 5 is a fragmentary top elevational view to
enlarged scale of the index table assembly of FIG. 1, taken
substantially in the direction of arrow 5 in FIG. 3 and rotated
therefrom by 90°;
FIG. 6 is a fragmentary, sectional view of the index
table assembly of FIG. 1, taken substantially in the direction
of the lines 6-6 in FIG. 5;
FIG. 7 is a fragmentary sectional view to enlarged
scale of a locating and holding structure of the index table
assembly of FIG. 1, and taken substantially in the direction of
the lines 7-7 in FIG. 9:
FIG. 8 is a fragmentary sectional view of the holding
structure of FIG. 7, taken substantially in the direction of the
lines 8-8 in FIG. 7;
FIG. 9 is a top elevational view of the locating and
holding structure of FIG. 7, taken substantially in the direction
of arrow 9 in FIG. 7;
FIG. 9A is a fragmentary view to enlarged scale
depicting the engagement of the outer end of the shot pin of the
locating structure in relation to an associated cam recess: and
FIG. 10 is a fragmentary elevation view of the locating,
and holding structure of FIG. 7, taken in the direction of arrow
10 in FIG. 7
Looking now to FIG. 1, an index table assembly 10
includes a base 12 for supporting an associated table subassembly
9

X031300
14 and drive structure 16 for rotating a table top 18 of the
table subassembly 14 about a central axis X between
circumferentially disposed indexed positions. The table
subassembly 14 includes a fixed support member assembly 19 which
rotatably supports the rotatable table top 18. As will be seen
the table subassembly 14 has a segmented air cushion structure
24 and 26 operative between the support member 19 and rotatable
table top 18 whereby the table top 18 can be supported on a
cushion of air (or other fluid) during rotation (see FIGS. 3 and
5). The rotatable table top 18 is guided during rotation on a
guide structure 27 located on support member 19 (see Fig. 3).
Looking now to FIGS. 7-10, a locating structure 20, is provided
to precisely locate the rotatable table top 18 in predetermined
indexed positions. A holding structure 22 is provided to hold
the rotatable table top 18 in the exact indexed positions.
In the embodiment of the invention, as shown in the
drawings the table subassembly 14 is generally of an annular
construction having an open center 25 extending through the
table top 18 and fixed support member 19.
When it is desired to index the table top 18, the
holding structure 22 is activated to release the locating
structure 20 and the rotatable table top 18 is raised on an air
cushion. The table top 18 is then indexed in a clockwise angular
direction about axis X relative to the fixed support. member 19~
to a position slightly past the desired, exact indexed position
and is subsequently slowly rotated in reverse direction the short
distance to the exact desired indexed position. The air cushion
is then removed and the table top 18 is lowered by gravity and
5

21031 ~~
is held by holding structure 22 in a precise, desired indexed
position for the procedures that are to be performed thereon.
It should be noted that, while in the preferred embodiment shown
air is utilized as the fluid or fluid medium providing the
desired cushioning, a fluid other than air, i.e. oil, could be
utilized; thus the expression fluid or fluid medium as used
herein shall be taken in its broadest sense and not restricted
to air; it should also be noted that the embodiment shown could
be readily adapted to provide for rotation of table top 18 in the
reverse or counterclockwise direction.
More specifically, the base 12 includes a bottom plate
34, a top plate 36 and cylindrical side walls 38 and 44
extending between the bottom plate 34 and top plate 36. Suitable
additional bracing and strengthening members 40, 42, and 46,
provide strength for the base 12 in conjunction with the bottom
plate 34, top plate 36 and the cylindrical side walls 38 and 44.
Both the bottom plate 34 and the top plate 36 are circular (see
FIG. 2). At the same time the locating structure 20 is supported
upon a cylindrical support 39 which is spaced radially outwardly
from and generally surrounds the table subassembly 14.
The fixed support member 19 of table subassembly 14,
is annular in configuration and has an inner diameter edge 28 and
an outer diameter edge 48 (see FIGS. 3 and 5). The fixed support
member 19 is rigidly secured to the top plate 36 of base 12 by
dowels 52 and bolts 54, spaced apart circumferentially
therearound (see FIGS. 3 and 6); the rotatable table top 18 is
mounted oh the fixed support member 19 concentrically therewith
6

zo~~~~~
for relative angular movement with respect thereto about the axis
X (FIG. 1).
The fixed support member 19 is provided with two
separate annular channels 58 and 60 in the bottom thereof and
is provided with an annular recess 62 having the cross sectional
configuration, as shown in FIG. 3. An opening 64 is provided for
an output drive shaft 66 which extends through the fixed support
member 19 along an axis X1 which is parallel with and in spaced
relation to the axis X. An outlet opening 68 in annular recess
62 (FIG. 6) cooperates with a lubricant sight gauge 72 and
connector pipe 74 respectively and these serve a purpose to be
described.
The rotatable table top 18 has a ring gear 76 secured
to the bottom thereof by conventional means such as dawels 78 and
bolts 80, (see FIGS. 3 and 6) spaced circumferentially
thereabout. Removable plugs 82 are threadably located in the top
of threaded openings 84 receiving the dowels 78 to provide
access to the dowels 78 and to prevent chips and the like from
collecting in openings 84.
Ring gear 76, is adapted to mesh with a pinion gear 86
which is part of the output drive shaft 66 and is rotated about
the axis X1 to rotate the rotatable table top 18 about the axis
X in response to rotation of the pinion gear 86 and the drive
shaft 66 about axis Xl.
The individual guide means 27 (see FIGS. 3 and 5)
include a plurality of angularly spaced wear pads 85 secured in
annular recesses 62 by fasteners such as bolts 88. The wear
pads 85 are adjustable through the use of shims 90 to exactly
7

203130
locate the inner diameter surface 92 of the ring gear 76 and to
thereby establish the axis of rotation X of the index table 14.
The wear pads 85 are accessible through the rotatable
. table top 18 of the table subassembly 14 through individual
recesses 94 which can be accessed upon removal of cover plates
96 secured to the table top 18 by fasteners such as bolts 100
(see FIGS. 3 and 5).
The index table assembly 10 includes the drive
structure 16, for the table top 18, which comprises a dual motor
brake assembly 102, a speed reduction structure 104 and a belt
and pulley structure 106 extending therebetween.
The dual motor brake assembly 102 is of a known
structure; the specific design details thereof, do not constitute
a part of the present invention and thus these details have been
omitted for purposes of simplicity. In this regard the dual
motor brake assembly 102 can be of a construction made by
Mannesmann Demag of Cleveland, Ohio and sold under the name
Micro-Speed and depicted in the catalog titled Industrial Drives
Product dated October 1, 1985.
Thus the dual motor brake assembly 102 and necessary
structure therebetween are operative for selectively driving an
output shaft 112 in opposite directions as required. The motor
brake assembly 102 includes main and auxiliary motors 108 and
110, respectively. The main motor 108 combines a brake assembly
and motor. The main motor 108, of the known construction noted,
has a tapered or conical air gap between the stator and rotor
(not shown) which permits the stator and rotor to shift axially
slightly with respect to each other to run or brake positions.
8

When the main motor 108 is energized, an axial component of the
magnetic field overcomes the force of a brake spring and pulls
the rotor end of the motor brake assembly into the stator,
releasing the brake whereby the rotor of motor 108 can rotate to
thereby rotate output shaft 112 in one direction. When the motor
108 is de-energized, the brake spring pushes the brake end of the
brake assembly into a braking surface, stopping the motor 108.
In operation of the motor brake assembly 102, the main
motor 108 is utilized to drive the rotatable table top 18 in one
direction such as the clockwise direction indicated by the arrow
114 in FIGS. 5 and 7 between one desired indexed position and
a subsequent approximate indexed position; at the approximate
indexed position, the brake of main motor 108 is actuated to halt
the angular rotation of the rotatable table 18.
Subsequently, the auxiliary motor 110 is~actuated to
rotate the rotatable table 18 in the opposite direction into the
final exact desired indexed position: once that location has
been reached the auxiliary motor 110 is ~deactuated and the
reverse rotation of the rotatable table 18 is stopped.
The speed reducing structure 104, (see FIG. 3) includes
a housing 116 secured to the fixed support member 19 by
fasteners such as bolts 118. Housing 116 supports the output
drive shaft 66 having the pinion 86 on the upper end thereof for
rotation in a bearing 120. An annular sealing member 122 having
O-ring seals around the inner and outer peripheries thereof is
provided between the bearing 120 and the upper end of the housing
116.
9

1
An input drive shaft 128 extends through the housing
116 transversely to and in spaced relation to the vertical
output drive shaft 66 and is mounted for rotation in the housing
116. Gearing such as a worm and worm gear, details not shown,
between the input drive shaft 128 and the output drive shaft 66
of the speed reducing structure 104 can be provided to drive the
output shaft 66 at a desired reduced speed on actuation of the
motor brake assembly 102 through the belt and pulley structure
106.
As shown in FIG. 3, the worm gear 130 is secured to the
output drive shaft 66 by convenient means such as the key 132.
A locking nut 134 is provided on the lower end of the drive shaft
66 and a spacer 136 is provided between the worm gear 130 and the
nut 134 in the speed reducing structure 104. Spacer 136 permits
the use of the same drive shaft 66 with housings, such as 116,
of different sizes thereby accommodating speed reducing
structures, such as 104, of different sizes.
A lubricating fitting 138 is provided to pass lubricant
to the index table assembly 14 through the axial opening 140 in
the drive shaft 66 (FIG. 3). Lubricating fitting 138 is secured
to the bottom of the drive shaft 66 by a mounting plate 142 and
the bolts 144.
The speed reducing structure 104 is of a known
construction and since the details thereof do not constitute a
part of the present invention they have been omitted for purposes
of simplicity. The speed reducing structure 104 can be of a type
manufactured by Ex-Cell-O Corp. Cone Drive Div. and as

2031300
illustrated in the catalog titled Standard Single Reductions
dated April, 1980.
As pointed out above and as shown in FIGS. 1 and 2, the
speed reducing structure 104 is driven by the dual motor brake
assembly 102 through the pulley and belt structure 106; the
structure 106 includes a drive pulley 150 and driven pulley 152
secured to the motor drive shaft 112 and input shaft 128,
respectively, by conventional means, not shown; the endless belt
154 extends between and drivingly connects the pulleys 150 and
152.
Looking now to FIG. 6, the recess 62 in the fixed
support member 19 is filled with oil to lubricate the table
subassembly 14 during rotation of the rotatable table top 18
via the pinion 86 in mesh with the ring gear 76. An overflow
tube 156, is provided to drain any excess lubricant from the
recess 62 to the drain pipe 158.
The lubricant sight glass 72, (see FIG. 6), is
connected through piping 160 to fluid communicate with the recess
62 through the opening 68 in the support member 19 of the index
table subassembly 14. As shown, piping 160, which is connected
to piping 74, extends through an opening 162 in the
cylindrical support 39. Accordingly, the operator is provided
raith a visual indication of the level 164 of the oil in the
recess 62 by the sight glass 72 which is located conveniently at
a position radially outwardly of the base 12 and table
subassembly 14.
The cushion or bearing on which the rotatable table
top 18 of the table subassembly 14 floats during rotary movement
11

thereof relative to the fixed support member 19 is provided
through two small annular grooves 166 and 168 in the top of the
support member 19. The annular grooves 166 and 168 are
concentric and are spaced apart radially. The grooves 166 and
168 are divided into angular segments by plugs such as plugs 170
and 172, spaced angularly therearound (see FIG. 5).
The angular segments of the grooves 166 and 168 are
provided with pressurized air resulting in the creation of a
fluid cushion or bearing medium; the fluid can be air or oil fed
through passages such as passages 174 extending through the
support member 19 (see FIGS. 3 and 6). The passages 174 are
individually connected to a source of air or other fluid medium
under pressure, not shown, through conduits 178, which are
positioned in the recesses 58 and 60 in the bottom of the support
member 19.
Thus, in operation, when air is passed through conduits
178, it passes upwardly through the passages 174 and into the
segments 24, 26 of the grooves 166 and 168, respectively, to lift
the rotatable table 18 from the support member 19 and float it
on an air cushion. Rotation of the table top 18 with respect to
the support member 19 is thus accomplished substantially friction
free. Further, due to the circumferentially, generally equally
spaced segments 24, 26 of the annular grooves 166 and 168 and
individual feeding of the passages 174 from the conduits 178, the
air cushion is substantially uniformly distributed around the
circumference of the lower surface of the table top 18.
Control of the indexing of the table subassembly 14 is
effected through the locating structure 20 and the locking or
12

zo~~~oo
holding structure 22; an associated electrical control circuit
179 is operatively associated with the dual motor brake assembly
102, the locating structure 20 and holding structure 22 and is
of a construction within the purview of one skilled in the art
and since the details thereof do not constitute a part of the
present invention these have been omitted for purposes of
simplicity.
Looking now to FIGS. 7-9, the locating structure 20
includes a plurality of cam mechanisms 190 secured to the outer
periphery of the upper portion of the rotatable table top 18 in
angularly spaced recesses 192 by fastening means such as bolts
194. The exact positioning of the cam mechanisms 190 within the
associated recesses 192 is provided by shims 196 located in the
recesses 192. In this regard the through holes in the cam
mechanisms 190 are oversized for clearance to permit final
positioning via the shim adjustment.
Each of the cam mechanisms 190 includes a cam plate 198
having a recess 200 therein, into which the end 202 of a spring
biased shot pin 204 extends in operation. The recess 200 has a
locating surface 206 thereon for precisely locating an indexed
position of the rotatable table top 18 in conjunction with a
complementary locating surface 208 on the end 202 of the shot pin
204.
The end 202 of the shot pin 204 has a camming surface
210 thereon operable in conjunction with a corresponding camming
surface 212 in the recess 200 and a camming surface 214 on the
leading edge of the cam plate 198 to move the shot pin 204
13

20~130~
axially thereof as desired on rotation of the rotatable table
top 18.
In operation, with the cam plate 198 moving with the
rotatable table top 18 (in the direction of the arrow 114 as
shown in FIG. 9) and with the shot pin 204 located via its
supporting structure 246 in a fixed position adjacent the
periphery of the table subassembly 14 , the surface 210 of the
outer end 202 of the shot pin 204 is first cammed over the
surface 214 of cam plate 198 until the end 202 of shot pin 204
passes in front of recess 200 in the cam plate 198; at this time
the spring biased shot pin 204 extends into the recess 200.
Rotation of the rotatable table top 18 in the direction
shown by arrow 114 is then stopped and the rotatable table top
18 is rotated in the opposite direction to engage the locating
surface 206 in the recess 200 with the locating surface 208 of
the shot pin 204 positioning the rotatable table top 18 in a
precisely indexed position, as determined by the positioning of
the cam plate 198.
When it is again desired to index the ratatable table
top 18 relative to the support member 19, the table top 18 is
again moved in the direction of arrow 114 and the end 202 of the
shot pin 204 is cammed out of recess 200 with the camming
surfaces 210 and 212 in engagement. The table top 18 is then
rotated to the next desired indexed position.
A position sensor 218, see FIGS. 1 and 3, is
operatively connected to drive shaft 66 via a locating ring 220
and actuating rod member 222. The locating ring 220 can be
selectively positioned on the drive shaft 66 and has a cam
14

~o~~~o~
portion 176 which can be selectively located relative to the
actuating rod member 222. Actuation of the rod member 222
actuates a limit switch 234, which is operative with electrical
control circuit 179 to effect actuation of the dual motor brake
assembly 102 as required in the operation of the index table
assembly 10, as discussed below. Thus the locating ring 220 can
be selectively positioned relative to the positions of the cam
mechanisms 190 to sense the approach of each of the cam
mechanisms 190 to the locating structure 20 sufficiently in
advance to provide a signal to the electrical control circuit
179 whereby the dual motor brake assembly 102 will be actuated
. to initiate braking and deceleration of the table top 18 before
the shot pin 204 is located in the cam recess 200. Note that
since the cam mechanisms 190 are located equally
circumferentially about the table top 18 only a single such
position sensor 218 is required and hence only one adjustment is
needed to accommodate the plurality of cam mechanisms 190 as each
approaches the single locating structure 20. The control circuit
179 where necessary can be set to actuate the motor brake
assembly 102 after receiving one or more signals from the limit
switch 234. Also-the electrical control circuit 179 will respond
to the positioning of the shot pin 204 in the cam recess 200 to
initiate reverse rotation of the motor brake assembly 102 to
locate the table top 18 in its final desired position with pirl-
surface 208 and recess surface 206 engaged. At the same time,
as will be seen, the shot pin 204 will be locked in the index
position until initiation of the next operating cycle.

Other types of apparatus could be used such as a timing
belt and appropriate gearing or a position sensor such as a
proximity switch like device for detecting a preselected number
of pulses relative to a multiple grooved ring on drive shaft 66.
The shot pin 204 extends through an opening 240 in a
housing 242 for reciprocal movement on its longitudinal axis.
Housing 242 is positioned on mounting plate 245 supported from
the cylindrical support 39 on brackets 246. Shot pin 204 is
urged outwardly from opening 240 and housing 242 by spring means
248, as shown in FIG. 7. 'Rotation of the shot pin 204 about its
axis 244 is prevented by a pin 252 in a slot 250.
Undesired transverse movement of the shot pin 204
within the opening 240 during reciprocal movement of the shot pin
204 along axis 244 is prevented by means of the members 254 and
256 located radially with respect to the shot pin 204 and held
in position by plugs 258 (see FIG. 8). The shot pin 204 can be
lubricated through passages 260 and 262 in the housing 242.
Shot pin 204 is secured in the opening 24.0 in the
housing 242 at opposite axial ends by means of end plate 264 and
bushing 266. The bushing 266 is provided in the outer end of
the opening 240 in the housing 242 to guide the shot pin 204 in
its reciprocal movement.
An air fitting 270 connected to a pressure switch 314
extends through the end of shot pin 204 to provide pressurized
air from pneumatic source 277. In this regard, the shot pin 204
is provided with an axially extending air passage 272 (see FIGS.
8, 9 and 9A), which is in communication with pneumatic source 277
16

2031300
and further communicates with transversely extending orifices 274
and 275.
In operation, the inclined shot pin surface 210 first
engages the inclined surface 212 of the cam recess 200 and then
urges the shot pin locating surface 208 into engagement with the
locating surface 206 of cam plate 198. This wedges the shot pin
204 into recess 200 to positively locate and hold the table top
18 in the desired indexed position. When the surfaces 208 and
210 of the shot pin end 202 engages the mating surfaces 206 and
212 of the cam plate 198, the orifices 274 and 275 are closed to
actuate the pressure switch 314, providing an indication to the
control circuit 179 that the rotatable table top 18 is in the
desired indexed position; in response, the control circuit 179
actuates the holding structure 22 causing the shot pin 204 to
be locked in the index locating position. Note that the forward
end 273 of shot pin 204 will not be seated against the bottom
surface 277 of the cam recess 200 (see FIG. 9A) thus assuring
proper location of the table top 18 at the indexed position.
Note that only the single orifice 274 need be used in some
application.
The locking or holding structure 22 includes a wedge
310 positioned in housing 242 on a piston rod 340 for reciprocal
movement along the axis 312, shown in FIG. 7, in response to
actuation of a pressure switch 314. The locking wedge 310 is
moveable into or out of opening 316 in the shot pin 204 to hold
the shot pin 204 relative to the upper portion of the table
subassembly 14 in a precise indexed position upon actuation of
a piston and cylinder structure 318 in response to actuation of
17
r

~(131~t1J
the pressure switch 314. Rotation of the locking wedge 310
about its axis is prevented by a pin 320 in a slot 321 and the
pin 320 is held in place by a plug 322. The piston and cylinder
structure 318 is secured to the housing 242 via bolts 324.
Looking now to FIG. 7, cam actuated limit switches 325
and 327 are supported by a bracket 330 secured to the bottom of
the piston and cylinder structure 318 by fastener means such as
bolts 332. Operatively associated therewith are cam mechanisms
326 and 328 carried by an extension 336 of the piston rod 340 of
the piston and cylinder structure 318. The limit switches 325
and 327 are actuated by the cam mechanisms 326 and 328 when the
wedge 310 is in a fully up position and when the wedge 310 is in
a fully down position respectively.
The switches 325 and 327 are connected to control
circuit 179. With the switch 325 actuated, and hence the holding
structure 22 actuated, and with the wedge 310 in an up position,
this condition is sensed by the control circuit 179 and the
indexing of the rotatable table top 18 is prevented. With the
wedge 310 in a fury down position so that the switch 325 is no
longer actuated and with the switch 327 actuated, this condition
is sensed by the control circuit 179 and indexing of the
rotatable table top 18 is now permitted; the latter is considered
below in the description of the method of indexing the rotatable
table top 18.
In the operation of the index table assembly 10, when
it is desired to index the rotatable table top 18 between precise
angularly spaced positions, the cylinder and piston 318 of the
holding structure 22 is deactivated, whereby.the wedge 310 is
18
Y,t
f.

203~.~UU
disengaged from the shot pin 204 and returned to a lowered
position, deactuating the limit switch 325 and actuating the
limit switch 327.
Actuation of the limit switch 327 is sensed by
control circuit 179 and this will permit energizing of the dual
motor brake assembly 102. Actuation of the limit switch 327 will
also activate the air cushion apparatus, whereby the rotatable
table top 18 is lifted above the fixed support member 19, so
that it may be rotated substantially friction free on an air
cushion. At the same time, the main motor 108 is energized to
drive the table top 18 in t-he direction of arrow 114, as shown
in FIGS. 5 and 9, to cam the shot pin 204 out of the recess 200
in the cam plate 198 at the prior, desired indexed position.
The rotatable table tap 18 is then rotated to an
approximate new desired indexed position and the shot pin 204 is
cammed over the cam plate 198 at the next desired indexed
position through engagement of the surfaces 212 and 214 on the
cam plate 198 and shot pin 204, respectively. When the shot pin
204 is opposite the recess 200, the shot pin 204 will move into
the recess 200 under the urging of the spring bias means 248.
At this time, the rotatable table top 18 avershoots the desired
new indexed position by a small amount.
At or prior to that time, the cam portion 176 of
locating ring 220 moves the actuating rod 222 to activate the-...
limit switch 234. Actuation of the limit switch 234 is sensed
by the control circuit 179 which causes the de-energization of
the main drive motor 108 and consequent braking action to bring
the rotatable table top 18 to a halt. The auxiliary motor 110
19

is then energized to drive the table top 18 in the apposite
direction to position the table top 18 in the precise required
new indexed position as determined by engagement of the position
locating surface 206 in the recess 200 with the surface 208 of
the shot pin 204.
Engagement of these surfaces closes the orifice 274 in
the shot pin 204 to actuate the pressure switch 314 and, in
response thereto, the control circuit 179 causes the auxiliary
drive motor 110 to be shut off. At the same time, the cylinder
318 is reactivated to drive the wedge 310 into the opening 316
in the shot pin 204 to hold the shot pin 204 in position with the
rotatable table top 18 in the precise, new indexed position.
While one embodiment of the index structure of the
invention has been considered in detail, it will be understood
that modifications thereof and other embodiments are
contemplated.
Thus, the index table assembly l0, as shown for example
in FIG. 3, is annular and has an inner diameter 28. The center
of the index table subassembly 14 is open. In the modified index
table assembly 400, shown in FIG. 4, the top portion 405 of the
index table assembly 400 is extended radially inwardly to have
an inner perimeter 404. A stationary column 402 is provided
on base 408 and is located concentrically of axis 410 by pilot
portion 412. A cylindrical member 414 is sleeved over the column
402 and is connected to the table top portion 405 by fastener
means such as bolts 416. The column 402 is stationary with
respect to the bottom portion, not shown, of the table assembly

400 while cylindrical member 414 rotates with the angularly
indexable top portion 405 of the table assembly 400.
In the embodiment shown in FIG. 4, the centrally
located column 402 is constructed to pass an actuating medium
and lubricant to tool structures, not shown, secured to and
indexable with the rotatable top portion 405 of table assembly
400.
In the embodiment of the invention shown in FIG. 4,
actuating fluid for tools and the like supported on the table
portion 405 is supplied through the passages 418 and 420, while
lubricant can be passed to such tools through the opening 422 in
the column 402. The corresponding passages 424, 426 and 428
in the cylindrical member 414 communicate with passages 418, 420
and 422 in the column 402 through annular grooves 430, 432 and
434 in the column 402 which are in communication with the
respective passages in any angular position of the cylindrical
member 414 relative to the column 402.
While it will be apparent that the preferred embodiment
of the invention disclosed is well calculated to fulfill the
objects above stated, it will be appreciated that the invention
is susceptible to modification, variation and change without
departing from the proper scope or fair meaning of the invention.
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