Tool changer machining center

An improved machining center including an automatic tool changer adapted for boring, drilling, milling, tapping and tool changing operations under numerical control. The machine, which may be built in both horizontal spindle and vertical spindle configurations, includes a tool storage matrix and tool transport shuttle compactly arranged on the upstanding column and a two-handed transfer arm on the headstock. The toolholders are carried in tool cups having mechanical latches. The matrix and the shuttle are also provided with mechanical latches for the tool cups actuated as an incident to transfer of tools between the matrix, shuttle, and arm or vice versa. The machine is adapted to operate with toolholders interchangable with those for a current commercial vertical spindle machining center.

DESCRIPTION OF THE INVENTION 
The present invention relates in general to machine tools and, more 
specifically, to a multifunction machine tool known as a machining center. 
Such machines are capable of performing a variety of machining operations 
such as boring, drilling, milling, and tapping under a numerical control 
system. They are usually provided with automatic tool changer capability 
which is also under the numerical control system. 
Automatic tool changing devices have been the subject of considerable 
activity heretofore. Many of them are unduly complex and require an 
excessive amount of time for a tool change by reason of the design, 
location, or operation of their tool storage matrices, shuttles, transfer 
arms or other components. 
With the foregoing in mind, the general aim of the present invention is to 
provide a heavy duty horizontal spindle and vertical spindle machining 
center adapted to perform automated boring, drilling, milling, and tapping 
operations and incorporating an automatic tool changer of improved 
construction, operation, and efficiency. 
More specifically, it is an object of the present invention to provide a 
machining center of the above type with an automatic tool changer that is 
compact, rugged, and positive in operation through the use of a mechanical 
latching system for supporting and transferring the toolholders. 
Another object of the invention is to provide a machining center and 
automatic tool changer of the character set forth which is adapted to 
operate with toolholders interchangeable with those utilized in the tool 
changer of a current commercial vertical spindle machining center. 
A further object of the invention is to provide a machining center and 
automatic tool changer of the above type wherein each toolholder is 
carried in an open tool cup in the tool storage matrix and in the tool 
shuttle, thereby protecting the precision shank of the toolholder during 
storage and transport to or from the tool change position. 
Another object is to provide a machining center and automatic tool changer 
of the character set forth above which is adapted to operate with 
toolholders having a relatively short shank which contributes to optimum 
rigidity and tool clearance. 
A further object of the invention is to provide a machining center and 
automatic tool changer as noted above wherein the tool exchange arm is 
mounted on the headstock and a compact mechanism is provided within the 
headstock to extend axially and to rotate the tool exchange arm. 
Still another object is to provide a machining center and automatic tool 
changer of the character set forth above having a compact and quick acting 
drawbolt mechanism for releasably securing the toolholder in the machine 
spindle.

While the invention is susceptible of various modifications and alternative 
constructions, certain illustrative embodiments have been shown in the 
drawings and will be described below in considerable detail. It should be 
understood, however, that there is no intention to limit the invention to 
the specific forms described but, on the contrary, the intention is to 
cover all modifications, alternative constructions, and equivalents 
falling within the scope of the appended claims. 
GENERAL ORGANIZATION OF HORIZONTAL SPINDLE MACHINE 
Referring more specifically to FIGS. 1 to 3, the invention is there 
exemplified in an illustrative heavy duty machining center 20 which 
incorporates an automatic tool changer 21. The machining center 20 is a 
horizontal spindle unit and in this instance happens to be a floor type 
machine. It is adapted to perform boring, drilling, milling and tapping 
operations, as well as automatic tool changing, all under numerical 
control. 
The machining center 20 utilizes a horizontal base or runway 22 supported 
on the foundation 24 and provided with leveling mechanisms 25. It includes 
a saddle 26 supported on antifriction rollers and ways (not shown) on the 
runway 22 for translational movement longitudinally of the runway, and a 
cross slide 28 translatably supported by antifriction rollers (not shown) 
and ways 29 on the saddle for movement along an axis perpendicular to the 
longitudinal axis of the runway. A split column 30 is fixed in upstanding 
relation on the cross slide 28 and is formed with vertical ways 31 which 
support a vertically translatable headstock 32. The headstock 32 carries a 
horizontal tool spindle 34 which is a rotatably supported therein on 
antifriction bearings. The spindle 34 is fashioned with an appropriately 
tapered socket for receiving and engaging the tapered shanks of the 
toolholders used for machining operations. 
A typical toolholder 34 used in the machining center 20 is illustrated in 
FIG. 1a. The toolholder 35 comprises a body 36 in which a milling cutter 
38 or other tool is securely clamped, and a precision tapered shank 39 
adapted to fit into a mating socket 40 in the spindle 34, and a tapered 
knob 41 adapted to be engaged by a power drawbolt. The toolholer also 
includes drive teeth 42 for engaging corresponding teeth in the spindle 
socket, a gripping flange 44, and an orientation button 45 fixed to the 
flange 44. It may also have a peripheral rib 46 spaced slightly below the 
drive teeth which serves as a retaining device when the toolholder is used 
in a vertical spindle machine. 
The automatic tool changer 21 of the machining center 20 comprises a tool 
storage matrix 48 mounted on the column, a tool carriage or shuttle 49, 
also mounted on the column, and a two-handed tool exchange arm 50 mounted 
on the headstock. The exchange arm 50 is adapted to move axially in a 
direction parallel to the rotational axis of the spindle 34 and to rotate 
in planes perpendicular to the axis of the spindle. Its function is to 
transfer tools between the shuttle and the spindle. 
Service lines for electric power and control, hydraulic power, and air are 
led to the machining center by means of a flexible tray unit 51 connected 
to the cross slide 28. 
A work table 52 is mounted in front of the machining center 20 and is 
formed with a number of T-slots for securing a workpiece thereto. The work 
table in this case happens to be of the rotary type including an indexable 
platen 54 which is adapted to present several sides of the workpiece to 
the cutting tools so as to minimize set up time. 
TOOL STORAGE MATRIX AND TOOL CUP 
The tool storage matrix 48 (FIGS. 1-4) in this case is formed as a large 
drum wheel supported for rotation about a horizontal axis on an extension 
housing 55 bolted or otherwise rigidly fixed to the side of the column 30 
as by mounting pads 56. The matrix 48 (FIG. 4) is fabricated as a weldment 
comprising a hub 58, a reinforced central web 59, and an outer annular rim 
60. The rim 60 has in this instance twenty-four outwardly opening pockets 
61 for storing a corresponding number of toolholders and moving them in a 
curved path with their axes perpendicular to a vertical plane passing 
through the spindle axis. The matrix hub 58 is journaled on a pair of 
antifriction bearings 62 on fixed shaft 64 which projects outwardly from 
the extension housing, being retained axially on the shaft by nut 65. 
The matrix 48 is rotated by means of a drive unit 66 (FIG. 4) mounted on 
the side of the column 30 as by means of bolts or cap screws (not shown). 
The drive unit comprises a hydraulic motor (not shown) connected to worm 
shaft 68 which drives worm wheel 69, pinion shaft 70, and drive pinion 71. 
The latter drivingly engages a ring gear 72 centered on the hub 58 and 
fixed to the inner side of the matrix. In the present case, the worm shaft 
68 is coupled to a transducer (not shown) which signals the angular 
position of the matrix and the pockets 61. 
The toolholders 35 are stored in the matrix 48 and transported to or from 
the latter in tool cups 74 (FIG. 6). The cups 74 may be formed of material 
of lesser hardness than the toolholder shanks 39 such as a tough, durable 
plastic. Angular orientation of the toolholder 35 in the tool cup 74 is 
maintained by means of orientation notch 82 which emgages the orientation 
button 45 of the toolholder. Referring more specifically to FIGS. 5, 6, 
and 6a, it will be noted that each tool cup 74 comprises a receptacle 
having a tapered socket 75 adapted to receive the corresponding tapered 
shank 39 of a toolholder 35 and to retain the latter until released in the 
course of a tool change. A latch 76 is mounted for horizontal pivoting 
movement on the top of the tool cup. One end of the latch is formed with 
an upstanding abutment 78 having an undercut shoulder 79 adapted to 
overlie the toolholder flange 44, and thus positively secure the 
toolholder in the tool cup. The latch 76 is spring biased so as to press 
the abutment 78 against the periphery of the toolholder flange. The amount 
of overhang of the undercut shoulder 79 may be adjusted by means of set 
screw 80. The opposite end of the latch 76 is formed with a beveled cam 
surface 81 for releasing the latch upon engagement of the toolholder by 
the tool exchange arm 50. The set screw 80 may also be used to align the 
cam surface 81 with its coacting abutment on the tool exchange arm. 
The tool cup 74 is formed with three axially spaced, external flanges 84, 
85, and 86 which may extend approximately three fourths of the way around 
the outer periphery of the cup. The flange 84 supports the tool cup 74 
when the cup is inserted in matrix pocket 61. The flange 85 supports the 
tool cup within the shuttle 49 and the flange 86 defines a locating 
abutment for precisely positioning the tool cup in the shuttle. 
Provision is made for releasably latching each tool cup 74 in a pocket 61 
of the matrix as an incident to insertion of the tool cup. This is 
accomplished in the present instance by means of a resilient latch element 
88 fixed as by screw 87 in a radial slot on the inner surface of the 
matrix rim 60 and extending radially toward the pocket 61 (FIGS. 4, 4a, 
7). The latch 88 has a fixed end, a central section serving as a spring 
arm, and an outer end portion formed with a beveled cam 89 and a 
transverse shoulder constituting a hook 90 (FIG. 4a). Cooperating with the 
cam 89 and hook 90 is a catch bar 91 fixed to the middle flange 85 of the 
tool cup 74 as by screws 92. The upper surface of the catch bar 91 is 
beveled for free sliding engagement with the cam 89. The flange 85 has a 
clearance aperture 94 for receiving the cam 89 (FIG. 5) with the hook 90 
engaging the rear face of the catch bar 91. 
For purposes of safety, the matrix 48 is enclosed in a peripheral casing 95 
of relatively heavy sheet metal with an opening only in the vicinity of 
the tool change station. The outboard face of the casing 95 may be 
enclosed by a heavy cover 96 of transparent plastic material (FIGS. 1-3), 
permitting ready observation of the stored tools. 
TRANSPORT SHUTTLE 
The transport shuttle mechanism 49 (FIGS. 1, 2, 7-9) is adapted to ferry 
toolholders ad their supporting tool cups 74 back and forth between the 
tool storage matrix 48 and the tool exchange arm 50. The shuttle mechanism 
49 is nested between the matrix 48 and the column 30 in a tunnel 98 
extending radially of the curved path of the toolholders, the tunnel being 
formed in the extension housing 55 (FIGS. 2 and 4). The mechanism 49 
comprises a track 99 having a straight portion and a curved outboard 
portion which is cantilevered partially around the front face of the 
column 30. The track 99 (FIG. 9) is rigidly secured to the column 30 as by 
means of cap screws 100 having spacers 101 around them for obtaining 
accurate alinement between the track and the matrix. Guide grooves 102 are 
formed in the opposed side walls of the track and they extend along both 
its straight and arcuate portions. The track 99 lies in a plane passing 
through the axis of the tool storage matrix and is parallel to the axis of 
the tool spindle. When the headstock is in tool change position, the track 
lies in a plane defined by the axes of the matrix and the spindle. 
A tool carriage 104 (FIGS. 7-9) is mounted for longitudinal sliding 
movement on the track 99, the latter being suitably lubricated for this 
purpose. The carriage 104 comprises a saddle 105 and a pivotal head 106 
adapted to engage a tool cup 74. The saddle is retained on the track in 
this instance by means of opposed gib plates 108 secured by cap screws 109 
to its underside and extending into the guide grooves 102. The head 106 is 
pivotally secured to the forward end of the saddle as by means of 
transverse pin 110. The forward end of the head 106 is constrained to 
follow the guide grooves 102 by rollers 111 which are mounted in the guide 
grooves and secured to the head 106 by bolts 112. The head 106 includes a 
forwardly projecting fork 114 for engaging a tool cup 74 and traversing it 
between the storage matrix and the tool exchange arm. 
The tool carriage 104 is power driven along the track 99 as by means of a 
hydraulic actuator 115 connected at one end to a bracket 116 fixed to the 
column 30 and at the other end to a coupling 118 mounted on the saddle 
105. Extension of the piston rod of actuator 115 serves to move the tool 
carriage 104 along the track toward the front face of the column 30. By 
reason of the curvature of the track 99 at its outboard end, the pivotal 
head 106 is moved through an angle of 90.degree., changing the orientation 
of the tool cup 74 and toolholder therein from parallelism with the axis 
of the matrix 48 to parallelism with the axis of the spindle 34. 
For the purpose of attaching the tool cup 74 to the tool carriage 104, a 
resilient latch member 119 is mounted on top of the pivotal head 106 and 
secured as by screws 120 (FIGS. 7-9). The latch member 119 is provided 
with an oblong central orifice defining a pair of laterally spaced spring 
arms in its intermediate portion. The forward end of the latch member 119 
is formed with a raised cam 121 terminating in a transverse shoulder 
defining a hook 122. The latch member 119 is nested in a longitudinal slot 
124 on top of the head and disposed so that its raised cam 121 will 
intercept the beveled lower edge of the catch bar 91 on the tool cup 74 as 
the fork 114 slides under the middle tool cup flange 85. At the point of 
full abutting engagement between the tool cup and a mating concave stop 
shoulder 125 in the fork 114, the cam 121 springs up into the aperture 
behind the catch bar 91 and the hook 122 engages the latter. Under this 
condition, the tool carriage is fully engaged with the tool cup. 
Provision is made in the transport shuttle mechanism for releasing the 
matrix latch 88 as an incident to extracting a tool cup 74 from the matrix 
by the tool carriage, and for releasing the tool carriage latch 119 as an 
incident to inserting a tool cup 74 in the matrix by the tool carriage. In 
keeping with this objective, the actuator coupling 118 on the saddle 105 
is formed so as to provide a predetermined amount of lost motion between 
the actuator and the saddle in both the forward and rearward directions. 
This is accomplished in the present instance by connecting the forward end 
of the actuator piston rod to a tie bolt 126 having a reduced central 
portion 128 which carries a bushing 129 of resilient material such as 
neoprene rubber and end washers 130. The tie bolt 126 extends through a 
pair of alined apertures in the upstanding lugs 131 of a yoke 132 rigidly 
fixed to the saddle 105, the resilient bushing being nested between the 
lugs 131. The end of the tie bolt 126 remote from the actuator is 
threadedly connected to a latch releasing mechanism 134. 
The mechanism 134 in this case comprises a lever 135 (FIGS. 7-9) in the 
form of a rectangular block pivotally mounted on top of the head 106 
between a pair of trunion blocks 136. One end of the lever 135 abuts 
against a projection 138 on top of the tool carriage latch 119. The 
opposite end of the lever 135 has a depending rod 139 fixed thereto and 
extending downwardly through the head 106 to releasably engage an aperture 
140 in the forward end of a flat bar 141 slidably supported on the saddle 
105. The opposite end of the sliding bar 141 is formed with an upstanding 
lug 142 adjustably connected as by threads to the projecting end of the 
tie bolt 126 remote from the actuator 115. The lever 135 is biased against 
the abutment 138 on the shuttle latch 119 by means of a biasing spring 144 
housed in a recess in the head and bearing against the depending rod 139. 
With the construction just described, movement of the tool carriage 104 
into full engagement with a cup 74 in the matrix will serve to latch the 
cup to the tool carriage. The coupling between the actuator 115 and the 
saddle 105 then deflects, allowing the piston rod of the actuator and the 
tie bolt to overtravel to the right (as viewed in FIGS. 7-9) about 0.1 
inch relative to the saddle. This motion is transmitted via the sliding 
bar 141 and depending rod 139 to swing the pivoted lever 135 upwardly 
against the matrix latch 88, thereby releasing the tool cup from the 
matrix. The tool carriage 104 thereupon extracts the tool cup and its 
toolholder from the matrix and transports them to the tool exchange 
position in front of the column. 
Upon reversal of the foregoing motion, with the tool carriage returning a 
cup and its toolholder to the matrix, the returning cup engages the matrix 
pocket 61 and the matrix latch 88 cams over and engages the catch bar 91 
on the tool cup. Since the tool carriage is still latched to the tool cup, 
the piston rod of the actuator and its tie bolt will continue to move to 
the left (as viewed in FIGS. 7-9) about 0.1 inch relative to the saddle. 
This produces an inward rocking or clockwise movement of the lever 135, 
depressing the tool carriage latch 119 and thereby releasing the tool cup 
from the carriage. The tool carriage then continues moving rearwardly to 
its parked position. 
It should be appreciated that the matrix 48 must rotate to bring a tool cup 
with a new tool, or a tool cup for an old tool, into the tool transfer 
station while the tool carriage 104 is at either extreme of its travel on 
track 99. As shown in FIG. 7, there is ample clearance for matrix rotation 
in either position of the carriage 104. 
TOOL EXCHANGE ARM 
The tool exchange arm 50 (FIGS. 1-3, 10, 12) is supported by a shaft 145 
extending from the front face of the headstock 32 in parallel alinement 
with the spindle 34. The arm 50 is fixed to the outer end portion of the 
shaft 145 in this instance by means of a circular plate 146 secured to 
both the arm and the shaft by cap screws 148. The shaft 145 and arm 50 are 
axially extensible to a tool pick-up position, and further to a tool 
exchange position. The shaft 145 and arm 50 are also angularly indexable 
through 180.degree. for tool pick-up and exchange, and also indexable 
through 90.degree. to a vertical or park position. 
For receiving tools, or more specifically tool holders 35, the outer ends 
of the arm 50 are formed with oppositely projecting pockets 149 (FIG. 12). 
Since both ends of the arm 50 are identical, a description of one will 
suffice for both. The pocket 149 is bounded by an end block 150, a side 
block 151 disposed at approximately 90.degree. to the block 150, and a 
rotatable spool 152 disposed at approximately 90.degree. to the side block 
151. Each of the blocks 150, 151 and the spool 152 is formed with a groove 
lying in a common plane and adapted to receive the flange 44 of a tool 
holder 35. The tool holder 35 is releasably secured in the pocket 149 by 
means of a latch 154 having an arcuate face 155 adapted to engage the tool 
holder flange 44 in an area which maintains it in an engagement with the 
blocks 150, 151 and the spool 152. The latch 154 is pivotally mounted on 
the arm 50 as by means of shoulder bolt 156 and biased into a normally 
engaged position against stop 157 by means of tensile spring 158 connected 
between cap screws 159 on the latch and 160 on the arm. The side of the 
latch bar 154 facing the headstock is formed with a tapered cam surface 
161 which is engaged by the toolholder flange 44 to pivot the bar 154 from 
its normally engaged position to permit entry of the flange 44 into the 
groove of the pocket members 150, 151 and 152. 
Provision is made for automatically releasing the toolholders 35 from the 
pockets 149 of arm 50 at the spindle 34, or at the tool carriage 104, 
after a tool exchange. This is accomplished at the spindle by means of a 
depending lug 162 fixed to a transverse shoulder on the side of the latch 
bar 154 facing the headstock (FIG. 10). Upon insertion of the tool 35 into 
the spindle, the lug 162 is accosted by the front face of the spindle 
cover as the arm 50 moves axially toward it, causing the latch bar 154 to 
be pivoted to its released position and permitting the arm to be swung 
clear of the toolholder. At the tool carriage 104, when the toolholder 35 
at the opposite end of the arm is inserted into the tool cup 74 of the 
carriage 104, the surface 161 of latch 154 is accosted by the top of 
abutment 78 which pivots the latch 154 to its released position and 
permits the arm 50 to be rotated freely away from the toolholder. 
Conversely, when a toolholder 35 is to be picked up by the arm 50 from the 
tool cup 74 of the carriage, provision is made for automatically releasing 
the tool cup latch 76 as an incident to rotation of the arm into 
engagement with the flange 44 of the toolholder 35 in the tool cup. This 
is accomplished by means of a depending tapered pin 164 adjacent each 
pocket 149 of the arm 50. As the arm rotates into engagement with the 
flange 44 of the toolholder 35, the tapered pin 164 strikes the cam 
surface 81 of the tool cup latch 76, releasing the latter as the latch bar 
154 of the arm secures the toolholder flange in the pocket 149. The 
toolholder 35 may then be readily extracted axially from the tool cup 74. 
For the purpose of axially extending and for indexing the exchange arm 50, 
two relatively compact mechanisms are provided within the headstock 
housing. Referring more specifically to FIG. 13, it will be noted that the 
tool exchange shaft 145 is formed with a longitudinally splined section 
165 which extends for the greater part of its length. The section 165 
engages a correspondingly splined hub 166 journaled on antifriction 
bearings within a cartridge 168 mounted in the headstock housing. The 
inner end of the shaft 145 is connected to a pair of hydraulic actuators 
169, 170 by means of a rotary coupling 171. Actuator 169 is interposed 
between a fixed mounting plate 172 and a slidable bracket 173 supported on 
a guide rod 174, being connected to the bracket 173 by piston rod 175 
(FIGS. 13, 14). The bracket 173, in turn, is connected to the rotary 
coupling 171 by means of the actuator 170, the body of which is secured to 
the slidable bracket 173 and the piston rod of which is secured to the 
rotary coupling 171. The rearward end of the actuator 170 is slidably 
supported on guide rod 174 by a slidable bracket 176. A control rod 178 
with a cam surface 179 for operating a limit switch 180 is also connected 
to the end of the shaft 145 by a bracket 181 extending between the rotary 
coupling 171 and a shoulder on the control rod 178. 
By reason of this construction, the actuator 169 functions to extend the 
exchange arm shaft and the arm 50 from its parked position to a tool 
pick-up position for engaging tool holders in the spindle and in the tool 
carriage at the outboard end of the shuttle track. The actuator 170 
functions to axially position the exchange arm to extract and replace 
toolholders in the spindle and in the cup 74 of the tool carriage at the 
outboard end of the shuttle track. The exchange arm indexing mechanism 
(FIGS. 13, 15) is adapted to rotate the arm 50 through 90 degrees for 
parking and through 180 degrees for tool exchange. It comprises a pinion 
182, integral with the splined hub 166 on the exchange shaft 145, driven 
by a meshing rack 184 translatably supported on rollers 185, 186. First 
and second hydraulic actuators 188, 189 are operated selectively to 
position the rack 184, and thus index the exchange arm 50. Both of the 
actuators are fixed at one end to the headstock through an adjustable 
support 190. The piston rod 191 of the first actuator is secured to a yoke 
192 having a floating pinion 194 journaled therein which meshes with the 
rack 184 and a second rack 195. The latter is translatably supported on 
rollers 196 and driven by the piston rod 198 of the second actuator 189. 
The floating pinion 194 is interposed between the racks 184, 195 for 
driving engagement therewith. A plurality of limit switches 199, 200, 201 
mounted on the yoke sense the position of the racks as the arm 50 is 
indexed. 
The piston rods 191, 198 of the actuators 188, 189 have equal strokes and 
each is operated so as to assume a fully extended or a fully retracted 
position. The mechanical relationship of the drive between the actuators 
is such that operation of the actuator 188 will produce 180 degrees of 
rotation of the arm shaft 145 for tool exchange. Operation of the actuator 
189 will produce 90 degrees of rotation for moving the arm 50 into or out 
of the vertical parked position. When the actuators 188, 189 are 
positioned as illustrated in FIG. 15, the tool exchange arm is in the 
vertical parked position. 
POWER DRAWBOLT 
The spindle 34 includes a power operated drawbolt mechanism 202 (FIG. 16) 
for releaseably securing the toolholders 35 in the tapered spindle socket 
40. The mechanism 202 comprises a drawbolt 204 supported coaxially within 
the spindle for axial movement in a splined coupling 205. The forward end 
of the drawbolt is formed with a head 206 coupled to fingers 208 
projecting into the spindle socket 40. The fingers are formed to receive 
the knob 41 projecting from the rearward end of the toolholder shank. When 
extended forwardly, the fingers open to receive or release the knob 41. 
Springs in the head bias the outer ends of the fingers into camming 
engagement with the inner wall of the tapered spindle socket 40. 
The inner end of the drawbolt 204 is formed with an Acme screw thread 209 
which engages a nut 210 housed within a bore 211 in the spindle. Thrust 
bearing 212 is interposed between the forward end of the nut and a 
shoulder 213 in the spindle. The nut is rotatably driven by a reversible 
drive shaft 214 having a splined connection 215 with the inner end of the 
nut. The nut includes right and left hand sections permanently coupled for 
limited relative axial movement by interfitting clutch teeth biased 
axially apart by springs 216. The inner end of the drawbolt is formed with 
an enlarged head 218 disposed in a cavity within the nut and serves to 
preclude disengagement of the drawbolt from the nut. The clutch teeth 
permit the drawbolt 204 to be moved rearwardly under the influence of a 
toolholder 35 inserted into the spindle socket, whereby drive teeth 42 of 
the tool engage the teeth 219 of the spingle prior to operation of the 
drawbolt. 
The drawbolt drive shaft 214 is reversibly driven by hydraulic motor 220 
through a dogtooth clutch 221 operated by hydraulic actuator 222 through 
yoke 224. The clutch 221 has a splined connection with a drive sleeve 225 
which, in turn, has a splined connection with the drawbolt drive shaft 
214. To preclude driving torque on the spindle from the motor 220 during 
drawbolt operation, while permitting it for spindle orientation, an outer 
sleeve 226 envelops the drive sleeve 225 and has a splined connection 228 
with spindle drive sleeve 229. The outer sleeve is normally urged by 
biasing spring 230 into frictional engagement with the driven element of 
the clutch 221. During drawbolt operation, hydraulic actuator 231, acting 
through arm 232, urges the outer sleeve 226 forward and separates it from 
the clutch element 221. Power from hydraulic motor 220 is thus transmitted 
directly to the drawbolt to engage or disengage the same, with no torque 
applied to the spindle by motor 220. 
The drawbolt mechanism 202 is adapted to provide positive ejection of the 
toolholder 35 from the spindle socket to facilitate tool changing. With a 
toolholder clamped in the spindle socket, the left hand end surface of the 
nut 210 is forced against the thrust bearing. The right hand end surface 
of the nut is always located against the fixed shoulder 234 of the 
spindle. To release the toolholder, the hydraulic motor 220 is operated to 
rotate the nut so that the threaded section moves rearwardly until the 
lost motion in the coupling between the nut sections is taken up. At that 
point, a positive axial ejection force is applied to the knob 41 of the 
toolholder. 
As indicated above, the motor 220 is also used in orienting the spindle 34 
to the predetermined angular position required for alining the positive 
drive teeth 42 of the toolholder 35 with the drive teeth 219 of the 
spindle socket. The angular oriented position of the spindle is 
established by a shot pin 235. For orientation, the spindle has a notched 
flange 236 formed with a shoulder 238. Upon clockwise rotation of the 
spindle with the actuator 239 energized to overcome the bias of spring 
240, the shot pin 235 will ride the periphery of the flange until it falls 
into the notch and engages the shoulder 238 for positive orientation of 
the spindle. 
AUXILIARY SERVICES TO SPINDLE 
Provision is made in the machining center 20 for supplying coolant to the 
cutting tool via the spindle. The coolant is introduced into a fixed 
collar 241 secured to the face of the headstock in surrounding relation 
with the end of the spindle. It passes between a pair of annular graphite 
sealing rings 242 and into a passage 244 leading to the spindle socket 40. 
Coolant from the passage 244 enters peripheral groove 245 in the 
toolholder shank and then flows into connecting passage 246 within the 
toolholder, ultimately being discharged at the cutting tool. 
Pressurized air is supplied to the spindle for two purposes. The first is 
to blow foreign material out of the spindle socket and off of the 
toolholder shank. The second is to provide an input to the control system 
to signal the presence or absence of a toolholder shank correctly seated 
in the spindle socket. 
The pressurized air is introduced via a passage 248 which directs it 
between two sealing rings 249, thence through a radial passage in the 
spindle sleeve, and then into the space surrounding the drawbolt shaft 
214. It then enters axial passage 250 in shaft 214, flows into the nut 
210, past the threads 209 and splines of coupling 205, and into the 
spindle socket 40. 
SYNOPSIS OF OPERATION--HORIZONTAL MACHINE 
For purposes of summarizing the operation of the machine 20 with the 
automatic tool changer 21, it will be assumed that the machine has just 
completed a machining cycle with the old tool (actually a toolholder 35) 
in the spindle 34 and the control has called for a tool change. The 
following sequence occurs: 
(1) The headstock 32 shifts from the machining position indicated in FIG. 1 
to the tool change position indicated in FIGS. 2 and 3 so as to bring the 
axis of the spindle into the same horizontal plane as the axis of the 
shuttle track 99. The spindle cases its normal rotation and becomes 
oriented for tool change by engagement of the shot pin 235 and orientation 
shoulder 238. 
(2) Tool carriage 104 is moved outwardly by extending actuator 115, 
extracting a new tool (actually a toolholder and its tool cup) from the 
matrix, turning it 90 degrees, and presenting it at the front of the 
column with its axis parallel to that of the spindle. The tool exchange 
arm 50 is moved axially outward from its park position at the headstock by 
the actuator 169. The matrix 48 is rotated to position an empty pocket at 
the tool transfer station for the old tool and its tool cup. 
(3) The tool exchange arm 50 is rotated clockwise (as viewed in FIG. 1) 90 
degrees by extending actuator 189 to engage the tools in the spindle and 
the tool carriage. The drawbolt mechanism 202 releases the old tool in the 
spindle and the arm 50 releases the tool cup latch of the new tool in the 
carriage. 
(4) The exchange arm 50 is moved axially outward by actuator 170, 
extracting the tools from the spindle and the tool carriage. 
(5) The exchange arm 50 is rotated clockwise 180 degrees by retracting 
actuator 188, exchanging the positions of the old and the new tools. 
(6) The exchange arm 50 is retracted axially by actuator 170, inserting the 
new tool in the spindle and the old tool in the empty tool cup on the tool 
carriage. The power drawbolt mechanism 202 engages the new tool in the 
spindle. The shot pin 235 is retracted from orientation shoulder 238. 
(7) The exchange arm 50 is rotated counterclockwise 90 degrees to a 
vertical position by retracting actuator 189. The tool carriage 104, with 
the old tool latched in its tool cup, is moved inwardly by retracting 
actuator 115. This swings the old tool through 90 degrees and inserts the 
old tool and tool cup in the empty matrix pocket at the tool transfer 
station. 
(8) With the new and the old tools secured in place, the headstock moves 
out of the tool change position and commences the next machining cycle. 
GENERAL ORGANIZATION OF VERTICAL SPINDLE MACHINE 
Referring next to FIGS. 17-23, there is shown an illustrative vertical 
spindle machining center 260 also embodying the present invention. The 
machine 260 is a numerically controlled multi-function machine tool which 
incorporates an automatic tool changer 261 similar to the tool changer 21 
of the machine 20 described above. In this case, the machine 260 happens 
to be a floor type machine which is adapted to perform boring, drilling, 
milling and tapping operations, as well as automatic tool changing. 
Since the machine 260 has a number of parts in common with the machine 20, 
like reference numerals will be used for the parts common to both machines 
and additional reference numerals will be used for the parts which are not 
common. 
The machining center 260 (FIGS. 17 and 18) comprises a base 262 supported 
on an appropriate foundation 264 and having longitudinally extending ways 
(not shown) on its top side covered by telescoping way covers 265. A 
saddle 266 is slidably supported on the longitudinal ways of the base by 
means of antifriction rollers (not shown). The saddle 266 is provided with 
ways 268 on its top side extending transversely of the ways on the base. A 
cross slide or column base 269 is slidably supported by antifriction 
rollers (not shown) for sliding movement on the saddle ways 268. An 
upstanding column 270 is mounted on the cross slide 269 and is formed with 
vertical ways 271 which slidably support a vertically translatable 
headstock 272. The headstock includes a vertical tool spindle 274 which is 
rotatably supported on antifriction bearings and driven by spindle drive 
motor 275 on top of the headstock. A feed drive motor 276 mounted on the 
column is adapted to move the headstock vertically via a lead screw (not 
shown) between the column ways 271. 
The automatic tool changer 261 in this instance comprises a tool storage 
matrix or magazine 278 mounted on the column 270 as by means of an 
overhanging support bracket 279 in the form of a generally rectangular 
plate (FIGS. 17, 18). It further comprises a tool carriage or shuttle 49, 
also mounted on the column, and a two-handed tool exchange arm 50 mounted 
on the headstock 272. The shuttle 49 and exchange arm 50 are substantially 
identical with those of the automatic tool changer 21 described earlier 
herein except for a differing orientation to accommodate the vertical 
spindle 274. The exchange arm 50 in the tool changer 261 is adapted to 
move axially in a direction parallel to the rotational axis of the spindle 
274 and to rotate in planes normal to the rotational axis of the spindle. 
Its function is the same here as in the tool changer 21, namely, to 
transfer tools between the shuttle and the spindle. The machining center 
260 and its automatic tool changer 261 are adapted to use toolholders 35 
and tool cups 74 identical to those of the machine 20 described above. 
The service lines for electric power and control, hydraulic power, and air 
are connected to the cross slide 269 of the machining center 260 via a 
flexible tray unit 51 similar to the one described above. 
Work to be operated upon by the machining center 260 is set up on work 
table 52 located in front of the machine (FIG. 18). The table 52 is 
similar to that associated with the machine 20 and may include an 
indexable platen (not shown) to speed the set up procedure. 
TOOL CAROUSEL STORAGE MATRIX 
The tool storage matrix 278 (FIGS. 17-21 and 23) is of the carousel type 
and in the present instance is adapted to hold forty-eight of the 
toolholders 35 in their associated tool cups 74. The matrix 278 comprises 
a pair of drums 280, 281 journaled on inner support plate 282 for rotation 
about horizontal axes in a common vertical plane spaced outwardly from the 
side of the column. An endless flexible carrier band 284, in this case 
made of alloy steel, is trained around the drums 280, 281 for movement in 
unison therewith. The carrier band 284 has a plurality of tool receptacles 
285 fixed in longitudinally spaced relation thereon for releasably 
supporting a series of toolholders 35 and their tool cups 74 and moving 
them in a curved path with their axes perpendicular to a vertical plane 
passing through the spindle axis. 
Each of the tool receptacles 285 comprises a platen 286 rigidly fixed to 
the carrier band 284 as by bolts 288 (FIGS. 20, 21). The periphery of each 
drum is formed with appropriate recesses to register with the bolts 288 so 
that the band 284 remains in contact with the drum surface throughout the 
180 degree arc of contact. Each platen has a socket member 289 fixed to 
the side thereof adjacent to the matrix support bracket 279 and extending 
parallel to the plane of the carrier band 284. The socket member 289 is 
shaped internally like the matrix pocket 61 of the tool changer 21 
described earlier herein and is adapted to releasably engage the tool cup 
74 between the flanges 84 and 85. The member 289 includes a resilient 
latch element 88 such as the one shown in FIGS. 4 and 4a which is adapted 
to cam into engagement with the catch bar 91 of the tool cup 74 as 
described above. 
The drum 280, which serves as the matrix driver, is journaled on shaft 290 
fixed to the inner support plate 282. Power is supplied to the drum 280 by 
means such as a hydraulic motor supported on the column and associated 
gearing similar to the arrangement shown in FIG. 4. In order to provide a 
positive drive between the drum 280 and the carrier band 284, the latter 
is formed with a series of longitudinally spaced apertures 291, each 
located at a platen 286 and adapted to register with corresponding radial 
lugs 292 spaced around the periphery of the drum 280. To accommodate the 
projecting lugs 292, each platen is formed with an appropriate clearance 
hole 294 (FIG. 21). The drum 281 is also formed with the spaced radial 
lugs 292 to assure engagement with the carrier band 284 (FIG. 21). 
Tension in the carrier band 284 is controlled by adjustment of the spacing 
between the axes of the drums 280, 281. This is accomplished in the 
present instance by journaling the drum 281 on a mounting plate 295 
adjustably secured to the inner support plate 282 as by clamping bolts 296 
(FIG. 19). The mounting plate 295 may be shifted to the right or left as 
viewed in FIG. 19 to regulate band tension. Oblong clearance slots 298 in 
the support plate 282 associated with the bolts 296 accommodate such 
movement. Adjustment is accomplished by means of a pair of wedge blocks 
299, 300, one fixed to the mounting plate 295 and the other fixed to the 
inner support plate 282. Relative movement between the wedge blocks is 
effected by adjusting screw 301 which is journaled in a bracket fixed to 
the block 299 and engages a tapped hole in the block 300. 
Provision is made in the storage matrix 278 for supporting the straight 
reaches of the carrier band 284, and its toolholders and tool cups, 
between the drums 280, 281. In furtherance of this objective, a pair of 
laterally spaced guide bars 302 is mounted in straddling relation with 
each straight reach of the carrier band. The ends of each platen 286 are 
downwardly turned and formed with appropriate grooves 304 for slidably 
engaging the guide bars 302 (FIGS. 20, 21). The bars 302 are supported by 
spreader brackets 305 mounted on pedestals 306 fixed to the inner support 
plate 282. 
In order to provide additional rigidity during tool change, the ends of the 
guide bars 302 at the tool change station are provided with arcuate 
extensions 303 which bridge the gap in support for the tool receptacle 
between the ends 302 and the drum 280. The extensions 303 are mounted on 
fixed brackets, the outer one 303a of which is attached to the fixed shaft 
290. 
The storage matrix 278, like the matrix 48, is enclosed within a peripheral 
casing 308 of relatively heavy sheet metal with an opening in the area of 
the tool change station (FIGS. 17-19, 21). The outboard face of the casing 
may be enclosed by a heavy cover 309 of transparent plastic material for 
observation of the stored tools. 
TRANSPORT SHUTTLE AND EXCHANGE ARM--VERTICAL MACHINE 
Referring further to FIGS. 18, 19 and 22, it will be noted that the tool 
transport shuttle mechanism 49 is incorporated in the machining center 260 
and is adapted to ferry toolholders 35 and their tool cups 74 between the 
tool change station of the storage matrix 278 and the tool exchange arm 50 
at the bottom of the headstock. This of course presupposes that the 
headstock 272 has been raised to tool change position. The shuttle 
mechanism 49 is mounted on the vertical center line of the drum 280 and 
nested in the tunnel 307 between the matrix support bracket 279 and the 
drum 280. The tunnel 307 and mechanism 49 extend radially of the curved 
path of the toolholders. The track 99 of the mechanism 49 is secured to 
the bracket 279 in any suitable manner with its upper end portion adjacent 
the tool change station and its lower end portion, including the curved 
section, extending in depending relation below the bracket 279. The track 
99 lies in a plane passing through the axis of the matrix drum and 
parallel to the axis of the tool spindle. Thus the tool carriage 104 is 
adapted to extract from the matrix a tool cup and toolholder at the tool 
change station, and to transport them downwardly while swinging them 
through an angle of 90.degree. for presentation to the tool exchange arm 
50. As an incident to such movement, the axis of the toolholder is shifted 
from horizontal to vertical orientation. 
The two handed tool exchange arm 50 is mounted in depending relation from 
the underside of the headstock 272 and is supported by its shaft 145 which 
has an axis parallel to that of the spindle 274. The shaft 145 and arm 50 
are axially extensible from a park position adjacent the bottom of the 
headstock of a tool pick-up position spaced below the park position, and 
to a tool exchange position spaced below the pick-up position (FIGS. 17, 
18, 22, 23). The shaft 145 and arm 50 may also be anguarly indexed through 
an angle of 180.degree. for tool pick-up and exchange, and are also 
indexable through a lesser angle to and from the park position. The outer 
ends of the arm 50 are formed with oppositely projecting pockets 149 and 
associated latching and releasing mechanisms described earlier herein. The 
arm is thus adapted to engage a toolholder in the tool cup and another 
toolholder in the spindle, to extract the toolholders from the tool cup 
and spindle, and to exchange their positions all in the manner described 
in connection with the horizontal spindle machine 20. 
POWER DRAW BOLT--VERTICAL MACHINE 
The spindle 274 of the vertical machine 260 includes a power operated draw 
bolt mechanism 202 which may, for example, be similar to that described 
above in connection with the horizontal machine 20. In the present 
instance, the draw bolt mechanism 202 is incorporated within the vertical 
spindle 274 and is driven by a power draw bolt motor 310 on top of the 
headstock. The power draw bolt is adapted to be used in the course of a 
tool change cycle for both clamping and releasing a toolholder in the 
spindle socket. 
the mechanism 202 provides positive ejection of the toolholder 35 from the 
spindle socket during tool changing. Its motor is also used in orienting 
the spindle 274 to the predetermined angular position required for meshing 
the positive drive teeth 42 of the toolholder 35 with the drive teeth of 
the spindle socket. 
SYNOPSIS OF OPERATION--VERTICAL MACHINE 
In the following summary of the operation of the machine 260 with the 
automatic tool changer 261, it will be assumed that the machine has just 
completed a machining cycle with the old tool (actually a toolholder) in 
the spindle 274 and that the control has called for a tool change. The 
sequence is then as set forth below: 
(1) The headstock 272 shifts from the machining position indicated in FIGS. 
17 and 18 upwardly to the tool change position indicated in FIGS. 22 and 
23 so as to bring the exchange arm 50 into closer proximity with the end 
of the shuttle track 99. The spindle ceases rotation and becomes oriented 
for tool change by engagement of the shot pin 235 and orientation shoulder 
238 described above. 
(2) Tool carriage 104 is moved downwardly by extending its actuator 115, 
extracting a new tool (actually a toolholder) and its tool cup from the 
matrix 278, turning it 90.degree. by means of the carriage head 106, and 
presenting it in the position shown in FIGS. 22 and 23 with its axis 
parallel to that of the spindle. The tool exchange arm 50 is moved axially 
downward from its park position at the bottom of the headstock. 
(3) The tool exchange arm 50 is then rotated counterclockwise (as viewed 
from the top) to tool pick-up position in which it engages the tool in the 
spindle and the tool in the tool cup held by the tool carriage. The draw 
bolt mechanism 202 releases the old tool in the spindle and the exchange 
arm 50 releases the tool cup latch 76 of the new tool in the carriage 104. 
(4) The exchange arm 50 is moved axially downward, extracting the tool from 
the spindle and the tool from the tool cup held by the carriage 104. 
(5) The exchange arm 50 is rotated 180.degree., exchanging the positions of 
the old and the new tools. 
(6) The exchange arm then retracts axially, inserting the new tool in the 
spindle and the old tool in the empty tool cup on the tool carriage. The 
power draw bolt mechanism 202 engages the new tool in the spindle. The 
shot pin 235 is retracted from the orientation shoulder 238. 
(7) The exchange arm 50 is rotated clockwise (as viewed from the top) 
through an acute angle and then raised to its park position. The tool 
carriage 104, with the old tool latched in its tool cup, is moved upwardly 
by retracting actuator 115. This swings the old tool and its tool cup 
through 90.degree. and inserts the old tool and tool cup in the empty 
matrix pocket at the tool change station. 
(8) With the new and the old tools secured in place, the headstock 272 
moves downwardly from the tool change position and commences the next 
machining cycle.