Note: Descriptions are shown in the official language in which they were submitted.
333
This invention relate~ to machine tool systems.
In the past, machine tools have been either stand-
alone machines or part of an automated machining system.
The automated machining systemsinclude a group of machine~
along with a workpi~ce transport system for transporting
workpieces from one machine to the next in the machining
system and control means for synchronizing the operation
of all of the machine tools and the workpiece transport
system.
Automated machining systems are very e~ficient
but require high capital investment while stand-alone
machines are much lower both in terms of capital'investment
and efficiency. One bottleneck for stand-alone machines
is the problem of transferring workpieces onto the machine
for machining and then transferring the finished workpiece
to the next machine for the next machining operation.
The principal object of this invention is to provide a
simple machining system which solves the foregoing work-
piece transfer problem but which is less expensive than
the automated machining systems heretofore known in the
art. Other objects and advantages of the invention will
be apparent from the description which follow~.
In accordance with this invention, the foregoing
problem is solved by arranging a plurality of machine tools
in a closed loop in which each machine tool is between
the tool which comes before it and the tool which comes
after it in the machining sequence.. Workpiece transfer
units are positioned adjacent to each machine tool for
transferring the workpieces from one machine tool to the
next in the machining sequence. An operator's station is
pxovided for introducing unmachined workpieces into the
loop and removing machined workpieces from the loop. ~he
unmachined workpieces introduced,into the loop at the
operator's station are transferred from one machine tool
to the next around the loop for machining and eventually
return to~the operator's station for unloading~
Accord~,ng to the invention there is provided a
machining system comprising at least three machine tools
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positioned in spaced apar~ relationship, each machine tool
having a worktable rotatably rnounted on a bed for rotation
about a vertical axis, and each worktable having horizontal
guide means for slidably receiving a workpiece support; a.
plurality of workpiece transfer units positioned in
operative relationship with said worktables, each work-
piece transfer unit having horizontal guide means fo:r
slidably receiving a workpiece support, and the horizontal
guide means of each workpiece txansfer unit being positioned
to be aligned or interact with the guide means on the
worktables and the machine tool and workpiece transfer
units being arranged to form a closed loop around which
workpiece supports may be transferred from one machine
;~ tool to another all the way around the loop.
:~ Employing the machining system of the invention
workpiece supports can be transferred from a worktable to
a workpiece transfer unit and vice ver~a.
In a particular embodiment each turntable is
: slidably mounted on a bed for movement along a corres-
ponding horiæontal axis, each worktable being indexabl~
- ~ about a corrasponding vertical axis perpendicular to its
horizontal axis. ::
The invention is illustrated in particular and
preferred embodiments by reference to the accompanying
drawings in which:
: Figure`l is a plan view of one preferred embodi-
ment of the invention;
Fig, 2 i~ a plan view of one machine tool and
the adjacent workpiece transfer units with the pallet on
the machine tool worktable being in position to be trans-
ferred off the machine tool worktable;
Fig. 3 is a plan view similar to Fig. 2 but
~ with the machine tool worktable empty and positioned to
- receive a new pallet;
Fig. 4 is a side elevation view, partially cut
away of one workpiece transfer unit: ! '
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Fig. 5 i~ a fragmentary end elevation view of
the workpiece transfer unit shown in Fig. 4,
Fig. 6 i~ a fragmentary longitudinal sectional
view taken on the line 6-6 of Fig. 5,
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Fig. 7 is a diagrammatic perspective view showing the
cables and hydraulic cylinders ~hich move the workpiece
transfer slide;
Fig. 8 is a plan view of a second preferred embodiment
of the invention;
Fig. 9 is a longitudinal sectional view taken on the
line 9~9 in Fig. 8;
Fig. 10 is a fragmentary perspective view of the
T-shaped transfer lug on a workpiece transfer unit and the
- 10 matching T-shaped slot in a transfer bracket attached to a
pallet;
Fig. 11 is a diagramatic longitudinal sectional view of
the hydraulic piston and cylinder mechanism on a workpiece
transfer unit, the transfer lug thereof being positioned
above a T-shaped slot in a transfer bracket on a pallet;
Fig. 12 is a diagramatic longitudinal sectional view
similar to Fig. 11 with the pallet raised to engage the trans-
fer lug in the transfer bracket; and
Fig. 13 is a cross-sectional view of a worktable taken
on the line 13-13 of Fig. 8.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
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Figure 1 is a plan view of one preferred embodiment of
the invention which includes three machine tools 10, 12 and
14 and three workpiece transfer units 16, 18 and 20 arranged -
' 25 in a closed loop which in this particular case is triangular
-~' in shape but which could be any suitable polygon depending ~'
~' on the number of machine tools employed. Each of the ma-
chine tools 10, 12 and 14 has a corresponding worktable 22,
24 and 26 which is slidably mounted on a corresponding bed
28, 30 and 32. Each of the worktables 22, 24 and 26 are
slidable along a horizontal axis and are indexable about a
:~! vertical axis perpendicular to the horizontal axis. Each
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worktable 22, 24 and 26 has horizon~al guide means to slid-
ably receive a pallet 34 carrying one or more workpieces 36,
38 and to clamp.pallet 34 thereon so that workpieces 36, 38
can be machined by machine tools 10, 12 and 14.
Machine tools 10, 12 and 14 can be any suitable
prior art machine tool, such as the MILWAUKEE-MATXC* 200
horizontal machining center manufactured by the Kearney &
Trecker Corporation of Milwaukee, Wisconsin~ The MILWAUKEE-
MATIC* 200 i~ disclosed in a manual entitled "MILWAUKEE_MATIC
200 Machine Maintenance Manu~l, Publication 413G, Eighth
Edition", published in January 1977, by the Kearney &
TrecXer Corporation of Milwaukee, Wisconsin.
Other suita~le machine tools are disclosed in
U.S. Patent No. 3,587,390 which issued to Earl R. Lohneis
et al on June 28, 1971, for an "INDÆX AND TABLE DRIVE MEANS
FOR A MACHINE TOOL", U.S. Patent No. 3,513,730 which issued
to Earl Ro Lohneis et al on May 26, 1970, for an "INDEXING
MEANS FOR A MACHINE TOOL" and U.S. Patent No. 3,825,245
; which issued to ~ohn G. Osburn et al on July 23, 1974, for
-:- 20 a "WORKPIECE CHANGER MECHANISM FOR A M~CHINE TOOL .
Workpiece transfer units 16, 18 and 20 each extend
between two adjacent machine tools 10, 12 and 14 and are posi-
tioned on the leys of the triangle defined by machine tools
10, 12 and 14. Workpiece transfer units 16, 18 and 20 are
positioned to interact with worktables 22, 24 and 26 in
transferring pallets 34 fro.~ one wor~table 22, 24, 26 to an
: adjacent worktable 22, 24, 26. To transfer a pallet 34 off
one of the worktables 22, 24, 26j the worktable is moved
along its bed to a location opposite the end of the appro-
- 30 priate workpiece transfer unit 16, 18, 20, as shown in Fig.
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2 and is indexed about its vertical axis until the worktable
pallet ways 40 (Fig. 3~ are aligned with the corresponding
' transfer unit pallet ways 42 (Fig. 2) so that pallet 34 can
be slid off of the worktable a~d onto the transfer unit.
Fig. 2 shows the relative positions required to slide pallet
34 off of worktable 24 and onto transfer unit 18.
After pallet 34 is slid off of worktable 24, worktable
24 is indexed to align its pallet ways 40 with the pallet
ways 44 of transfer unit 16, as shown in Fig. 3, so that it
can receive another pallet 34 from transfer unit 16. In
this particular example, the flow of pallets 34 is counter-
clockwise in Fig. 1, although pallet flow in the opposite
direction is equally feasible since the workpiece transfer
units 16, 18 and 20 are adapted to move pallets 34 in either
~ 15 direction.
- Pallets 34 are introduced into the closed loop system
at an operator's station in the middle of transfer unit 16.
An operator 46 places a pallet 34 carrying workpieces 36 and
38 on transfer unit 16 with conventional lifting devices
(not shown). The pallet 34 is subsequently transferred
counterclockwise around the loop first to machine tool 12,
then to machine tool 14, then to machine tool 10, being ma-
chined at each machine tool. After all the machining has
been completed, pallet 34 is returned to the operator's sta-
tion on transfer unit 16 where it is removed by operator 46and replaced by a pallet carrying unmachined workpieces.
-;~ Alternately, only the workpieces 36 and 38 could be removed
and replaced at the operator's station.
- In this particular example, machine tools 12 and 14 are
horizontal machining centers while machine tool 10 is a mul-
tiple spindle indexable turret. However, it will be under-
stood by those skilled in the art that any combination of
machine tools can be employed which have indexable work-
tables adapted to interact with workpiece transfer units to
- 35 transfer workpieces onto and off of the worktables.
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The construction of workpiece transfer units 16, 18 and
20 is illustrated in Figs. 4 through 7. Referring to Figs.
4 and 5, each transfer unit 16, 18 and 20 comprises a bed 48
which is supported by legs 50. A pair of spaced horizontal
guide means or pallet ways 52 and aligned rollers 53 are sup-
ported on top of bed 48 for slidably receiving a pallet 34.
A transfer slide 54, best shown in Fig~ 7, is slidably mounted
on rails 56 ~Fig. 7) that extend the full length of bed 48.
Transfer slide 54 carries a pair of extendable and retractable
vertical posts 58 and 60 which are cylindrical in shape and
are slotted on their upper end at 59 and 61 to engage lugs 62
on pallets 34 as best shown in Fig. 7. In Fig. 7, post 58 is
shown in its extended position engaging lug 62 while post 60
is shown in its retracted position below the level of lug 62.
In Fig. 4, post 60 is in the extended position engaging lug
62 while post 58 is in the retracted position. Post 60 is
used to pull pallets 34 onto the transfer unit and post 58 is
- used to push pallets off of the transfer unit as described
hereinafter.
Posts 58 and 60 are moved upwardly and downwardly between
their extended and retracted positions by slidable cam plates
64 (Fig. 5) which extend transverse to posts 58 and 60 and _~
have sloping cam slots 66 therein which engage cam rollers 68
attached to the bo~tom of posts 58 and 60, as best shown in
25 Fig. 6 for post 60. Post 60 is notched at 70 (Fig. 6) to pro-
vide clearance for cam plate 64. Cam roller 68 is attached to
the notched end of post 60 by a machine screw 72 and rides in
cam slot 66 of cam plate 64. A similar mounting is used for
the cam plate 64 and cam roller 68 on the bottom of post 58.
Posts 58 and 60 are raised by moving their cam plates 64
~ to the left in Fig. 5 to the position shown therein and are
`~ lowered by moving their cam plates 64 to the right in Fig. 5.
- The movement of cam plates 64 is caused by pairs of hydraulic
~ cylinders 74 and 76 (Fig. 5) mounted on bed 48 and positioned
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opposite the locations where the pallet lugs 62 are to be en-
gaged. Cylinders 74 and 76 move plungers 78 and B0, respec-
tively, against the side edges of cam plates 64 when actuated
to move cam plates 64 either to the left or to the right in
Fig. 4, thereby either raising or lowering the corresponding
post 58 or 60. Cylinders 74 and 76 are double-acting cylin-
ders which are caused to extend or retract their plungers 78
and 80 by conventional control means which is not shown in the
drawings. Cylinders 74 and 76 are actuated in paired opposi-
tion, i.e., when one plunger 78,80 is extended the other isretracted and vice versa. Conventional limit switches 82 and
84 are mounted opposite cylinders 74 and 76 and interact with
bumpers 86 and 88 on the outer ends of plungers 78 and 80 to
indicate whether plungers 78 and 80 are in their extended or
retracted position. Limit switches 82 and 84 provide infor-
mation for the transfer control means.
~; When cam plates 64 are moved to the left, in Fig. 4, to
-~ raise post 58 or 60 to the extended position, roller 68 en-
ters a horizontal portion 90 (Fig. 5) of cam slot 66 at the
upper end thereof which holds the corresponding post 58 or 60
in its extended position as transfer slide 54 is moved back
and forth along bed 48.
Transfer slide 54 is moved by a hydraulically driven ~
cable arrangement which is illustrated schematically in Fig. ; -
: 25 7. A first cable 92 is attached to one end of transfer slide
54 and passes around a first fixed pulley 94 which is rota-
tably attached to transfer unit bed 48 and then passes around
a movable pulley 96 which is rotatably attached to the plun-
ger 98 of a hydrauic cylinder 100. Cylinder 100 is rigidly
30 attached to transfer unit bed 48. After passing around mov- ;
; able pulley 96, cable 92 is attached to a bracket 102 on
transfer unit bed 48.
On the other side of transfer slide 54, a second cable
104 is attached thereto and passes around a fixed pulley 106
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which is rotatably attached to transfer unit bed 48 and then
passes around a movable pulley 108 which is rotatably at-
tached to the plunger 110 of a second hydraulic cylinder
112. Cylinder 112 is rigidly at:tached to transfer unit bed
~8. After passing around movable pulley 108, cable 104 is
attached to a bracket 114 on transfer unit bed 48.
Hydraulic cylinders 100 and 112 are both double-acting
and are actuated in paired opposition to cause transfer
slide 54 to move along transfer unit bed 48, i.e., when one
of the hydraulic cylinders 100,112 is retracted, the other
is extended by the same amount and vice versa. Hydraulic
cylinders 100 and 112 are operated by conventional control
means which is not shown in the drawings.
To draw a pallet 34 onto the transfer unit, transfer
slide 54 is moved to the end of transfer unit bed 48 adja-
cent to pallet 34, as shown in Fig~ 4. Hydraulic cylinders
74 and 76 are then actuated to raise post 60 and engage it
with lug 62. Hydraulic cylinders 100 and 112 are then actu-
ated to draw pallet 34 onto and across the transfer unit.
When transfer slide 54 reaches the other end of the trans-
fer unit, post 60 is lowered and transfer slide 54 is re-
positioned to place post 58 under the lug 62 at the other
end of pallet 34O Post 58 is then raised to engage lug 62
and transfer slide 54 is moved to push pallet 34 off the
- 25 transfer unit. The pallet 34 is drawn onto the transfer
unit by post 60 and is pushed off by post 58. However, if
desired, the direction of transfer can be reversed, and if
so, the pallet 34 will be drawn onto the transfer unit by
post 58 and will be pushed off by post 60.
The hydraulic control means which cause the above-de-
scribed movements of transfer slide 54 and posts 58 and 60
~` is conventional, and hence, i8 not shown in the drawings.
Figs. 8 to 13 show a second preferred embodiment of the
invention in which three machine tools 116, 118 and 120,
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each of which has a corresponding worktable 122, 124 and
126, are positioned around a pallet carousel 128, as shown
in Fig. 8. Pallet carousel 128 is rotatably mounted on a
base 130 (Fig. 9) by conventional means (not shown) and has
four workpiece transfer units 132, 134, 136 and 138 which
are spaced at 90 positions around the center of carousel
128 in position to interact with worktables 122, 124 and
126. Each of the worktables 122, 124 and 126 is rotatably
mounted on a corresponding base 140, 142 and 144 by conven-
tional means (see Fig. 13) and each has conventional hori-
zontal guide means 146 to slidably receive a pallet 148 and
has conventional clamp means (not shown) to clamp pallet
148 thereto. Workpieces 150 can be clamped to pallets 148
- by conventional means (not shown). Each worktable 122, 124
and 126 can be rotated through 360.
Workpiece transfer units 132, 134, 136 and 138 are
positioned in operative relation with the horizontal guide
means 146 on worktables 122, 124 and 126 so that pallets
148 can be slid from any one of the workpiece transfer units
132, 134, 136 and 138 to any one of the worktables 122, 124
and 126 and vice versa. The pallets 148 are slid from a
worktable 122, 124 or 126 to workpiece transfer units 132,
134, 136 or 138 by a hydraulic piston and cylinder mechan-
ism 156 described below.
The details of workpiece transfer unit 136 are shown
in Figs. 8 to 12.
Referring to Figs. 8 and 9, a pair of horizontal ways
152 are mounted on a base 154 to slidably receive pallets
-, 148. Base 154 is rigidly mounted on carousel 128 by con-
ventional means and rotates therewith. A hydraulic piston
and cylinder mechanism 156 i5 mounted on base 154 by con-
ventional means. Hydraulic piston and cylinder mechanism
156 has a piston rod 158 to which a bracket 160 is attached~
Bracket 160 has a forwardly extending portion 162 which is
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T-shaped (see Fig. 10) and which engages a T-shaped slot
164 in a bracket 166 attached to the bottom of pallet 148
(see Figs. 11 and 12).
To engage the T-shaped end 162 of bracket 160 with
the T-shaped slot 164 in bracket 166, hydraulic piston rod
158 is extended, as shown in Figs. 10 and 11, to place
T-shaped end 162 over T-shaped slot 164. This is done by
pumping hydraulic fluid into hydraulic piston and cylinder
mechanism 156 by conventional hydraulic pump means 168
(Fig. 9) through conduit 170 to fully extend piston rod
158. At the full extension of piston rod 158, limit switch
172 (Fig. 11) is actuated by a lug 176 on a rearwardly ex-
tending portion 178 of bracket 160 and terminates the flow
of hydraulic fluid by conventional means not shown. After
piston rod 158 has been fully e~tended, with T-shaped end
portion 162 being aligned with T shaped slot 164, as shown
in Figs. 10 and 11, the worktable holding pallet 148 is
raised by means described hereinafter to engage bracket 162
with bracket 166, as shown in Fig. 12.
To slide pallet 148 from the worktable to workpiece
transfer 136, hydraulic fluid is then pumped into hydrau-
lic piston and cylinder mechanism 156 by hydraulic pump
means 168 through conduit 174 to retract piston rod 158
and draw pallet 148 onto ways 152. When piston rod 158 is
fully retracted, a shoulder portion 163 (Fig. 11) of bracket
160 strikes limit switch 172 and terminates the flow of
hydraulic fluid by conventional means not shown. This
places pallet 148 on workpiece transfer unit 136.
The above-described movements are reversed to push
pallet 148 back onto one of the worktables 122, 124 or 126.
In the operation of the embodiment shown in Fig. 8,
pallets 148 carrying workpieces 150 are loaded one at a
time on workpiece transfer units 132, 134, 136 and 138 at
- an operator's station 180. The pallets are then positioned
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opposite the desired worktable 122, 124 or 126 by rotating
carousel 128 through 90 increments by conventional rotary
drive means (not shown) which can be similar to the rotary
drive shown in Fig. 13. The pallets 148 are then loaded on
the desired worktables, as described above, for ~achining of
the workpieces 150. When all of the machining operations
have been completed, the pallets 148 are loaded back onto
the workpiece transfer units 132, 134, 136 and 138, as de~
scribed above, and pallet carousel 128 is rotated through
90 to move each pallet 148 to the next position around
the loop of machine tools. The pallet that is moved into
operator's station 180 carries a finished workpiece 150
which is removed from its pallet 148 and is replaced by an
unmachined workpiece.
Fig. 13 shows the details of worktable 122 and its base
` 140. The base 140 is a recessed steel casting within which
an index cylinder 182 is seated~ Index cylinder 182 has an
outwardly extending flange 184 which is bolted to a portion
of base 140 by bolts 186. Flange 184 supports a rotary in-
dexable coupling 188 which has an upper ring A and a lower
ring B which are both serrated and are designed to come to-
gether at any one of a plurality of precisely located angu-
lar increments. Ring A is rigidly attached to worktable top
190 and rotates therewith, while ring B is rigidly attached
to stantionary indèx flange 184. To rotate top 190, it is
necessary to first lift it to disengage ring A from ring B.
After top 190 is rotated to the desired angular position, it
is lowered, and as ring A engages ring B, top 190 is rotated ~`
slightly to bring it into alignment with one of the precise -~
~ 30 angular increments of indexable coupling 188.
j Top 190 is rotatably mounted on top of index cylinder
182 by means of bearing 192 which rests on top of a hollow
cylindrical hydraulic piston 194. Piston 194 has a flange
196 whose upper and lower surfaces are boundaries of adja-
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cent hydraulic chambers 198 and 200 into ~hich hydraulic
fluid can be pumped to move piston 194. The lower boundary
of chamber 200 is the inner shoulder of index cylinder 182,
which supports piston 194. To raise piston 194 and top 190,
hydraulic fluid is pumped into chamber 200 and i5 e~hausted
from chamber 198. Hydraulic fluid is pumped into and ex-
hausted from chambers 198 and 200 by conventional means not
shown.
When worktable top 190 is raised, a ring gear 202,
which is attached to top 190 by bolts 204, engages a spur -
. gear 20~. Spur gear 206 is attached by bolts 208 to a shaft
- 210 which is journalled to worktable base 140 by bearings
212 and 214. At its lower end, shaft 210 is connected to a
spiroid gear set comprising a spiroid ring gear 216 and a
spiroid pinion gear 218. Spiroid pinion gear 218 is attached
to a shaft 220 which is journalled to worktable base 140 by
bearings 222, 224 and 226. Shaft 220 is coupled to shaft 228
which, in turn, is coupled to shaft 230. Shaft 230 is coup-
led to a servo motor (not shown) by conventional means not
shown. When shaft 230 is rotated by the servo motor, it
causes rotation of worktable top 190 via gears 218, 216, 206
and 202. Rotation of worktable top 190 also rotates hori-
zontal ~uide means 146 which is connected to worktable top :~
190 by dowel 232. Pallet 148 rotates with horizontal guide
: 25 means 146.
; Although the illustrative embodiments of the invention
have been described in considerable detail for the purpose
of fuIly disclosing practical operative structure incorpor-
ating the invention, it is to be understood that the particu-
; 30 lar apparatus shown and described is intended to be illustra-
- tive only and that the various novel features of the inven- -.
tion may be incorporated in other structural forms without : :
departing from the spirit and scope of the invention as de- ~ :
fined in the subjoined claims.
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