Note: Descriptions are shown in the official language in which they were submitted.
- .~.iLZ~5i68
Thls invention relates generally to a mach~ne tool and more parti-
cularly it relates to a machine tool of the type having a drivlng spindle
driven by an electromotor and a turret head portion for supporting a plur-
ality o~ tool holders and for positioning a selected tool holder lnto align-
ment with the driving spindle, whereby the facing ends o the driving spindle
and of the tool holder are provided with coupling members and further includ-
ing feed mechanism for axial displacement of the driving spindle and the tool
holder. From prior art an automatic machine tool of this type is known in
the form of a turret drill in which the tool holders are made as drill spin-
dles which include, respectively, a working spindle and driving gears assignedthereto. The driving spindle is driven by an alternating current motor and
is dlrectly coupled to each driver spindle. The rotary speed of the working
tool is, in each individual case, determined by the transmission ratio of
the gears in the drill spindle. As a consequence, if a large range of rotary
speeds is required there are necessarily many drill spindles with correspond-
lng transmission gears. Ilowever, the gears having a high transmission ratio
are expenslve and also there are problems as far as the size of the trans-
mlssion Ullit and the torque transmisslon are concerned. To define the length
and the speed o~ the feed of the tool each driver spindle is provided with
its own signalling elements in the form of cams, fixed stops and switches,
amount controllers and the like. As a rule, during the exch~nge of the
working tool it is necessary to replace the whole driver spindle by another
one so that the tool can be adjus*ed via the corresponding transmission gears
to correct rotary speed and via each setting member to the correct feed. By
means o~ the coupling between the driving spindle and the drill spindle, the
working tool is driven at the necessary rotational speed and a feed mechanism
imparts the feeding movement to the coupling. As a con3equence, a consider-
able axial pressure is to be taken up by the coupling elements. Respective
6~3
drill spindles are transported into their position by mechanical rneans; they
are seated in a turret in the form of a Maltese cross wheel which is driven
by a separate motor and therefore only a steplike change of working position
of respective drill spindles is possible. The disadvantage of such prior
art arrangement of the machine tool is the fact that the positioning of re-
spective working tool is difficult, the control of the working cycle is
expensive, the power output - and the range of rotational speed is limited,
adjustment time is large, the structure is heavy and, due to the necessary
transmission gears and motors, very costly.
It is therefore a general object of the present invention to over-
come the aforementioned disadvantages.
More particularly, it is an object of the invention to provide an
improved machine tool which is substantially simpler in structure and easier
to operate.
Another object of the invention is to provide such an improved
machine tool which has minimum setting up times.
A further object of the invention is to provide a machine tooL
which is adapted for being controlled automatically according to a program.
In keeping with these objects, and others which will become
apparent hereafter, one feature of the invention resides, in a machine tool
of the aforedescribed type, in the provision of driving means for respective
working tools which includes a direct current driving motor having a rela-
tively stable torque in a wide range of rotational speeds and means for
; electrically controlling the rotational speed and the position of its rotor
according to a predetermined program. Thls program is determined in response
to the desired feeding speed and to the desired length of travel of the tool
holder. In the preferred embodiment, the driving direct current motor is a
servo-motor with a permanent magnetic field. Such servo-motors, as is kno~n,
~. ~
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have light weight, small size, very high torque even at low ratational
speeds and, due to the high ratio:between torsional moment and inertia
moment, a high acceleration and reactivity. The direct current servo-
motor is a multipole motor and as a rule is electrically controlled via a
thyristor amplifier According to another eature of this invention, the
parameters o the driving direct current motor in the machine tool of this
invention, namely the size of the motor, its power, its torsional moment
and lts rotational range, are intentionally below the limits which would
otherwise be required for the operation of the machine in its designed
range of application. Such underdimensioning of the driving motor hitherto
has been applied for feed drivin~ motors and not for the main power drive
for working tools. The application of the driving motor of this invention,
in spite of its underdimensioning, enables a continuous regulation of ro-
tational speed, is inexpensive and has output characteristics well suited
for machining. Expecially it has very high thermal time constant so that
it can be overloaded for an extended period of time and without the danger
o~ being overheated.
According to still another feature of this invention the maximum
power output Oe the driving mo~r of this invention is devised to be about
half of the actual power consumed during its operation. The rnaximum pead
of impulses of its torsional moment can reach about ten times the value
of its nominal torsional moment.
I the machine is constructed as a turret drill having a plurality
of driving spindles, there are provided, according to one feature of this
invention, groups of transmission gears assigned for respective driving
spindles. Each group of transmission gears has diferent transmission ratio
whereby it has been proved to be of particular advantage when the drilling
spindles are divided into two groups, one having a transmission ratio i = 1:1
s~
and the other group having transmission ratio i 5 ~ 1. In combining these
transmission gears groups with the drive according to this invention, the
conventional multlstage gear shift mechanism can be dispensed with and the
torsional momen~ ls transmltted dlrectly from the driving motor via a
transmlssion belt through the drlving. spindle and via the coupling means
to the drilling spindle and to the working tool. This arrangement has an
addltlonal advantage that in the event when damage of the transmission gears
occurs it can be quickly corrected by replacing the whole drilling spindle.
~ In exchanging the working tools during the drilling operation, it is no
: 10 longer necessary to exchange the whole drilling spindle but itis suf-ficient
to exchange the working tool only and consequently a reduced number of
drilling spindles in the machine is required. Also the re-adjust~ent of
fixed stops, cams, regulators and the like is no longer necessary for
defining the feed of the tool according to its rotary speed and its speed
of travel and consequently the non-operative time of the machine is sub-
stantially reduced.
It is true that the direct current motor in the application accord-
ing to this invention has a lower torsional moment when its rotational
speed is low. nuo to the provision of the a~orementioned transmissi.on gears
for the range of low rotational speeds required for the tool it is achieved
that the driving motor operates only in a single range of its rotational
speeds in which the generated torsional moment is sufficient for driving
the tool at low rotations. In the aforedescribed range of transmissi.on
ratios of the gears for respective drilling spindles and for the range of
; rotary speed of the driving motor, for example 1 to 8, it is possible to
app~y to thè working tool all rotational speeds at sufficient torsional
moment that are required in practice. In exceptional cases it is always
possible to apply drilling spindles having lower or higher transmission
:
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rat~o of their gears whereby the rotary speed of the motor can be lncreased.
Accordingly, it is possible to use a great variety of working tools operable
at di$ferent rotary speeds when the drilling remain unchanged in the turret
and as a rule in a great majority of cases the spindles remain in the turret
without change.
According to still another feature of this invention it is of
particular advantage when the direct current motor of this invention drives
in addition to the driving spindle also via a separate coupling device the
turret with working tools. In this manner the driving D.C. motor takes
over the alignment~ of the selected working tool with the driving spindle
and the positioning of the turret. By virtue of the elimination of a
separate turret drive there results a substantial constructional simplifi-
cation of the machine, respective working tool holders can be aligned more
quickly and the unproductive non-opera~ional times of the machines are
further reduced. The coupling of the motor to the turret is made automatical-
ly, ~or example when the machine tool i5 constructed as a machining center.
Thls coupling takes place within the last 25 mm of the stroke of the spindle.
In one embodiment according to this invention the d~vice for
exchanging the tools is constructed as a turret wheel provided along its
peripheral portion with passages for accommodating the working tool holders
or the driving spindles during their axial feeding whereby the turret
wheel is coupled via gears to the driving direct current motor. A switching
device permits the movement of the turret wheel only when the driving spindle
is in its starting position.
In the case when the machine tool is constructed as a machining
center, coupling means between the working tool and the driving tool include
a spllne shaft movable in a coupling gear provided with corresponding grooves
whereby the spline shaft is axially displacFable therein. Preferably the
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61~3
coupllng gear ls in mesh with the gear connected to the driving spindle.
The spllne shaft ls axially movable in an axially flxed driving gear which
is coupled by transmlssion means to the direct current motor. In this
manner there ls achieved a completely compact and simple structure of the
machine of this invention. The coupling gear and the meshing gear for the
drivlng spindle are preferably arranged in one housing block which is
axially movable by means of a feeding mechanism. The feeding mechanism
consists of a spindle nut fixed to the housing block and of a feed spindle
driven by a separate auxiliary direct current motor (servo-motor). The
coupling gear and the meshing gear for the driving spindle are axially
fixed in the housing block; the driving spindle passing through the gear
and the housing block is also axlally flxed relative to the la~ter and is
dlsplaceable to a fixed stop. In a further simplication of the structure
of this invention, the spline shaft supports a gear which in response to
the positlon of the spline shaft is engageable into another gear coupled
to the turret wheel. The turret wheel is provided on its face with index-
ing borings and during the feeding movement of the driving spindle one end
of the spline shaft enters the assigned boring. A pOSitiO71 indicator is
located over khe driving wheel to enable the orientation of the spindle
and another position indicator is arranged above the axle of the turret
wheel to indicate its position. If the machine tool is constructed as
a turret drill machine, the coupling means of this invention may include
a coupling member connected to the driving spindle and another coupling
member connected to the drilling spindle ~working tool holder) whereby the
coupling is effected by means of a separate power element in one case or
coupling wheel after axial displacement of the driving spindle in another
case. In the latter case the driving spindle is shaped in the form of a
spline sha~t passlng through center boring provlded with corresponding
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guiding grooves o~' the driving wheel driven by the direct current motor and
o the coupling wheel. Preferabl~ the coupling wheel is in the form of a
gear ~hich is in mesh with the gear connected for driving the turret wheel.
To increase the coupling speed the driving spindle together with the associated
coupling members is axially movable b~ means of the aforementioned power
element which is also rotated in a housing block and axially movable by the
feeding mechanism ~d~rect current servo-motor). The burret wheel in this
case is arrestable by means of an indexing bolt which preferably is also act-
uated b~ a power element; both power elements are made as hydraulic cylinder-
piston units controlled ~y the same control device.
The programma~le control for the machine of this invention is
; effected b~ means of a digital control device. Preferably, there is employ-
ed a three-axes or multi-axes digital control so that the dlgital control
de~ices are used for controlling not only the direct current motor for
driving the driving spindle, the turret for exchanging the working tools
and the feed mechanism, but also for controlling the movement of the working
tool supporting table ~x axis and y axis~. The combination of the driving
direct current motor the rotational speed of which is coupled electricalLy
with the digital control device capable of being pre-programmed in a technical
bureau enable to control all essential movements of the support:Lng table and
of the feed mechanism as well as the adjustment of the rotational speed of
the work tool and the exchange of the work tools in the turret, the control
~eing made by a da~a carrier, especially a punched tape. Long readjustment
works in the machine shops are thus substituted by short programming work in
the technical department.
Thus, in accordance with one broad aspect of the in~ention, there is
pro~ided, in a machine tool having a driving spindle, a turret wheel for
~olding a plurality of tool carriers and for displacing a selected tool carrier
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568
into an operational position in alignment with said driving spindle, and means
for coupling said dri~ing spindle to the selected tool carrier, a combination
comprising a direct current motor for driving said driving spindle, said motor
having a relativel~ stable torque in a wide range of rotational speeds, and
programmable means for electricall~ controlling tlle rotational speed and the
angular rest posit~on of the rotor o said motor and the feeding movement
and speed of said tool carrier according to a predetermined program prepared
for machining a particular workpiece.
In accardance wlth another broad aspect of the invention there is
pro~ided, in a turret drill machine having a driving spindle, a turret wheel
for holding a plurality of tool carriers and for displacing a selected tool
carrier into an operational position in alignment with said driving spindle,
means for coupling said dri~ing spindle to the selected tool carrier and means
for displacing said tool carrier in a feeding direction, a combination
comprising a direct current motor for drlving said driving spindle, said motor
having a relatively stable torque in a wide range of rotational speeds,
programmable means for electrically controlling the rotational speed of sa:id
motor and the feecling movement oE said tool carrier according to a predeter~nined
program propared for machining a particular workpiece, a plurality of drill
spindles each including tool carrier and transmission gears arranged between
said tool carrier and said coupling means, the transmission ratio in at least
one group o~ said drill spindles being the samel and wherein one group of drill
spindles in said machine has transmission gears with a first transmission ratio
and another group of spindles has gears with a different transmission ratio.
According to another broad aspect of ~he invention there is provided,
in a machine tool having a driving spindle, a turret wheel for holding a
plurality of tool carriers and for displacing a selec~ed tool carrier into an
operational position in alignmenk wi~h said driving spindle, means for coupling
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sa~d drivlng sp~ndle to the selected tool carrler and means or displacingsaid tool carrier in a ~eed~ng direction, a comblnation comprlsing a direct
current motor for driving said driving spindle, said motor having a relatively
.~ stable torque ln a wide range of rotational speeds, programmable means for
electrically controlllng the rotational speed of said motor and the feedlng
movement of said tool carr~er according to a predetermined program prepared
for mach.ining a particular workpiece, additional clutch means for coupling
said turret wheel to said driving motor, and wherein sald turret wheel has an
axle provided with a gear, said gear being engageable with transmission gears to
lQ said dri.ving motor.
n accordance w~th a further ~road aspect of the invention there
~s provided, in a mach~ne tool having a driving spindle, a turret wheel for
hold~ng a plurality of tool carriers and for displacing a selected tool
carrier into an operational position in alignment with said driving spindle,
means f~r coupling sald driving spindle to the selected tool carrier and means
for displacing said tool carrler in a feeding direc~ion, a combination
compri~ing a direct current motor or driving said driving spindle, said motor
: ~aving a relatively stable torque in a wide range of rotational speeds, pro-
grammable means for electrically controlling the rotational speed of said
2a motor and the feeding movement of sald tool carrier according to a predetermined
program prepared :Eor machining a particular workpiece, additional clutch means
for coupl~ng said turret wheel to said drivlng motor, said additional clutch
means lncluding a spline shaft and a coupling gear having a grooved central
passage for engaging the splines of said spindle shaft, and wherein said
driving spindle is positively connected to the driving gear, said driving gear
being in mesh with said coupling gear.
According to another broad aspect of the invention there is provided,
~n a machine tool having a driving spindle, a turret wheel for holding a
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Z(~68
plur~l~t~ of tool carr~ers and ~or displacing a selected tool carrier into an
operational position in alignment w~th said driving spindle~ means for coupling
said driv~ng spindle to the selected tool carrier and means for displacing said
tool carrier in a ~eeding direction, a com~ination comprising a direct current
motor for driv~ng said driving spindle, sald motor having a relatlvely stable
~: torque in a wide range o~ rotational speeds, programmable means for electrically
controlling the rotational speed of said motor and the feeding movement of said
tool carrier according to a predetermined program prepared for machining a
particular workpiece, additional clutch means for coupling said turret wheel to
la s~a~d drl~ing motor, and wherein sald coupling mechanism for said tool spindle
~ncludes an intermediate coupling disc co--axially attached to said driving
spindle and defining two opposite coupling surfaces, said driving spindle
being axiall~ movable b:e~ween a first switching position in which one coupling
surface of sa~d intermediate member is in engagement with said coupling gear
and a second position in whlch said one coupling surface is disengaged from
: said coupling gear and the other coupling sur~ace is in eng~gement with said
drill spindle.
The invention wlll be best understood erom the :Eollowing descrlption
o~ speclelc embodimonts when read ln connectlon with tlle accompanying
drawings, in which:
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)568
FIGURE 1 is a front view of a machlne tool constructed as a turret
drilling machine,
FIGURE 2 is a side view of the machine of FIGURE l;
FIGURE 3 is a sectional side view of one embodiment of the turret
head in the mach:ine of FIGURE 2 showing one of the drill spindles in its
- wor]clng position.
FIGURE 4 is a sectional side view of the turret head of FIGURE 3
showing the feeding device;
~IGURE 5 is a sectional side view of a cut-away portion of the
head of ~IGURE 3 showing the turret wheel;
FIGURE 6 is a sectional side vlew of the turret head of the machine
tool of this invention constructed as a machining center and shown in a
posltion during the tool exchange;
FIGURE 7 is a view similar to that of FIGURE 6 and showing the
; position of respective componenet parts during the working process; and
FIGU~ 8 shows a sectional side view of still anokller embodiment
of the turret drilling machine shown in its working position.
The machine tool o:E this invention is, in ~IGUR~S L and 2, illu-
strated in the form of a kurrek drilllng machlne including convent:ional
parts such as base 1, upon which a working table 2 is displaceable in X-
and Y- direction, and supporting means for clamping a workpiece ~not shown
in the drawing). Stand 3 projects upwardly from base 1 and supports turret
head ~ which is vertically adjustable and arrestable in a fixed working
position. Turret head ~ supports a turret wheel 5 (switching drum) in
which tool holders such as, for example, 12 drill spindles 6 are suppor~ed.
The displacement of the turret wheel as well as the determination of the
position of the table 2 in the X- and Y-axes is effected by means of a
digital control device which also controls the feeding speed along both
' , ~ ,
1~ 68
axes. For this purpose a direct current motor 7 takes care of the feeding
in Y-direction and a direct current motor 8 moves table 2 in X-direction.
Both motors 7 and 8 are pneumatically controlled with the aid of a tacho-
generator and a rotational speed indicator.
In t~e embodiment shown in FIGURES 3 to 5, there is shown head~'~
whlch includes feed spindle 9 in the form of a ball roller spindle, a guid-
ing rod 10, a driving spindle 11, bore spindles 6 seated on a turret wheel
5 and a bearing piece 13. The components 6, 9, 10, 11 and 13 are vertically
arranged in the housing of head ~. Bearing piece 13 is a tubular piece
supported for rotation in the housing portion 14 and having its lower end
fastened by screws to the turret wheel 5. Feed spindle 9 is connected by
means of an axially extended shaft 15 to an auxiliary direct current motor
16. Peed spindle 9 is threaded and supports for axial displacement nut 18
which carries housing block 12 acting as feed element 17. A projection 19
of feeding element 17 engages a corresponding circumferential groove in
drill spindle 6. Spindle 6 is insertable laterally into its seat on turret
wheel 5 and to define the position of the spindle 6 in the dircction of
the axis there is also used the same digital control device wh:ich controls
the speed of feeding.
Driving spindle 11 is supported for axial displacement and is
connected for rotation with driving wheel 20 which in turn is coupled
via transmission means, such as toothed belt 21, to the driving disc. The
driving disc is rotated by the main driving unit 22 which is composed of
an electrically controllable direct current motor of a programmable digital
control unit. Each drill spindle 6 has its own transmission gear 2~, which
gears have transmission ratios divided in several groups so that the ratio
of several transmission gears in one group is uniform. For example, if
turret ~heel 5 supports twelve drive spindles 6, a first group of, say,
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five spindles has gears with a transmission ratio i ~:1 and another group
of seven spindles 6 has gears with a transmission ratio i 1:1. The first-
mentioned group is employed for working tools whichJ during the machining
of a workpiece, are supposed to operate at low rotational rate and at the
same time require a high torsional moment; the second group having a direct
trans~ntssion is employed for working tools requiring higher rotational
speed. In this manner the required torsional moment can always be applied
to the work tool even if motor 22 is a direct current motor which at lower
rotat~onal speed has a diminished rotational moment. The provision of a
drill spindle in the reduction gear ensures that the direct current driving
motor, even at low rotational speeds of the working tool, operates at a
high rotational speed where its torque is optimum.
The facing ends of driving spindle 11 and of drill spindle 6 are
provided, respectively, with coupling elements 25 and 28 which, in the
illustrated embodiment~ form together a cone clutch with a bell-shaped
coupling member 24 and a matching cone-shaped coupling member 27. As
illustrated in FIGURF 4, the separate power drive unlt 29 such as,for
example, a cylinder-piston hydraulic drive is incorporated in the ~eed
mechanism 17 and controls the :Erictional connection or discolmection of
driving spindle 11 to drill spindle 6. In the actuated condition of
clutch 24 and 27 driving spindle 11 is subject to axial displacement impart-
ed to a drill spindle 6 by feed mechanism 17. For stepwise rotation of
turret wheel 5, in the illustrated embodiment, the turret wheel is in the
form of a Maltese cross wheel which, as illustrated in FIGURE 5, is driven
by driving member 30 actuated via chain 32 or via any suitable driving
mechanism by driving motor 31. The outer Jacke~. of each spindle 6iis
seated-on turret wheel 5 in such a manner that it is secured against
rotation but is axially displacea~le. As soon as turret wheel 5 places
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a selected spindle into allgmnent with drivlng spindle 11, this posltion
is secured by means of a suitable arrestlng or indexing device, as illu-
, strated in the drawing.
The machining of a workpiece is digitally controlled according
to a program. The necessary commands are emitted from a data carrier such
as, for example, a punched band. This digital information controls, via
motors 7 and 8, table 2 and move it at a predetermined speed and direc~ion
of travel to its correct position; similarly, the digital information
controls vertical adjustmen~ of the head 4 and further con~rols via motor
31 and turret wheel 5 the working position of the particular drill spindle
6 in which its axis 33 is aligned with driving spindle ll. In doing~so,
the main driving motor 22 rotates at a speed determined by the program so
that a desired torque and rotary speed is imparted to the working tool
~not shown) disposed in drill spindle 6. On coupling by means of clutch 27
and 24 the driving spindle 11 to stop shaft 26 the auxiliary servo-motor
16 rotates feed spindle 9 in a direction and speed determined by the program
and displaces nut 18 on fixed spindle 9 and via projecting arm 19 the drill
spindle 6 so that the working tool machines the workpiece with the desired
speed,
If it is desired to exchange tools in respective drill spindles
6, the latter as a rule remain in turret wheel 5 and only a corresponding
exchange of the program data carrier has to be made, the new program being
prepared in a separate technical office which determines the path of feedi
ing, the feed speed and the rotational speed of the newly applied working
tools.
FIGURES 6 and 7 illustrate a modification of the machine tool
of this invention constructed as amachining center where base 1 supports
the head 4 which is axially adjustable in both directions as indicated by
~ .
s~
arro~ 35. Turret head 4 slmilarly as in the preceding exampleJ contains
main driving motor 22, driving spindle 11, spline shaft 35, feed drive
mechanism 36 and a tool exchanging turret 37 including a turret wheel 5.
The maln driving motor 22 is again a direct current servo-motor
38 having a maximum power of 7.5 to 11 kilowatts, for example. The direct
current motor 38 is a muLtipole motor with a permanent magnet field and
has an extraordinarily large range of rotational speeds at an almost constant
torsional moment. Its thermal time constant is more than 100 minutes. Heat
which may rise in the motor when the latter is subject to peaks of torsional
moments, substantially exceeding for a prolongated period of time the nominal
torsional moment, can be disspated in the armature having a high amount of
iron. For this reason, the direct current motor, in its application in
the machine tool of this invention can be exposed to a nominal power which
is approximately one-half of its maximum power. The motor of this type
hitherto is employed only as an auxiliary motor for driving the feeding
mechanism. The maximum rotational speed of this motor i5 about 3000 re-
volutions per minute. Due to this relatively large range of rotational
speeds, transmission gears for driving spindles 11 can be constructed as
two-stage transmission gears only. The direct current servo-rnotor 38
drLves, via a tooth belt or the like transmission means 21, a driving
wheel 20 which is fixedly supported for rotation without axial movement
in head 4. A spline shaft 35 is arranged for axial movernent in the grooved
central opening of the drive wheel 20 and extends downwardly through a
grooved central opening o-f coupling wheel 39 arranged for rotation in
houslng block 12. The end portion of spline shaft 35 carries a gear 41
which functions as driving pinion for turret wheel 5 and the free end
portion of shaft 35 is guided in a sleeve 40 ixed on the housing cf
head 4. In this embodiment, spline shaft 35 has a section between drive
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S~
wheel 20 and coupling wheel 39 (which in this example is in the form o~
a gear 42), which is reduced in diameter and without splines so that the
drive wheel 20 can be connected or disconnected from the gear 42 and this
arrangement thus forms a clutch 43.
In housing block 12 there is further supported for rotation gear
44 keyed to driving spindle 11 and being in mesh with coupling gear 42.
Upper free end 45 of driving spindle 11 projects from housing block 12 and
ln the uppermost position of the latter abuts against a fixed stop member
46 which is arranged on a partition in turret head 4. Feed mechanism 36
pro~ides for vertical displacement of the housing block 12 together with
gears 42 and 44 and driving spindle 11. The feed mechanism 36 includes,
similarly as in the preceding examples, a direct current servo-motor 16
supported on the partition of turret head 4 and rotating a threaded feed
sp~i~ndle 9 which engages feed nut 18 connected to housing block 12. The
lower end of driving spindle 11 projects through the housing of turret
head 4 and is guided for axial and rotary movements in bearing sleeve 47
supported ln the lower wall of the turret head housing. In this manner,
driving spindle 11 is movable together with housing block 12 in the Eeed-
ing direction. Driving spindle 11 is terminated at its lower end with a
coupling member 24 consisting of a CenteriJIg conical member ~8 and a
holding member 49. The holding member 49 extends through a center passage
in spindle 11 and its lower free end has a T-shaped cross-section. Biasing
element 50 in the form of a set of springs 59 urges the holding member
inwardly. Coupling portion 24 operates worktool carrier 52 which, at its
face opposite the end of driving spindle 11, is provided with coupling
part 27 in the ~orm of a short cone 53 having a transverse groove matching
the T-shaped end of holding member 49. Cone 53 snugly fits the centering
conical member ~8 and the T-shaped end of holding member 49 engages the
568
corresponding groove 54 and in this manner the rotational moment of spindle
11 is transferred to the worktool. Holding member 49 is keyed to the inner
wall of spindle 11 by a key 55 so that the former is axially guided and the
connection and disconnection of the worklng tool carrier 52 is facilitated.
Worktool carriers 52 are seated in turret wheel 5 which orms the
essential structural part of the tool exchanging device 37. Turret wheel
5 is provlded for this purpose wlth through-holes 57 arranged near its
periphery 56 and each tool carrier 52 as well as driving spindle 11 can
pass through through-holes 57. Axle 58 of turret wheel 5 is supported
for rotation on the lower wall of the turret head housing. Axle 58 is
connected to gear 59 which is engageable with gear 41 of spline shaft 35.
Above axle 58, position indicator 60 is arranged for reading the angular
position of turret wheel 5. The upper surface of turret wheel 5 is provided
with indexing recesses 61 adapted for receiving a stepped down end portion
62 of spline shaft 35 when the latter is in alignment with a corresponding
indexing recess. The smooth section of spline sha:Et 35 'below drive wheel
20 is provided with a collar 63 which rests on a bufEer plate 64 on the
upper surface of housing block 12. 'I'he upper free end of spl:lne shaft 34
is spring-biased clownwardly by means oF a tens:ion spring 65 and above drive
wheel 20 is positioned, on the turret wheel housing, a position indicator
66 for detecting the orientation of driving spindle 11.
FIGU~E 6 illustrates the machlning or tooling center in a position
in ~hlch tool exchange can be effected. Driving spindle 11 is in its start-
ing position, which means the end 45 of holding member 49 abuts against fixed
stop 46, the whole spindle body is retracted in the housing of head 4 and
the turret wheel is free to rotate. Only the T-shaped portion of the lower
end of holding member 49 projects through the lower wall of head 4 to such
an extent that tool carriers 52 together with short cone portion 53 can be
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axially moved out of engagement wlth the centering conical member 48. During
this axial movement, driving spindle 11 is in its "ready to release" position~
namely at an angular position in which the groove 54 and holding member 49
are aligned relative to each other so that during the rotary movement of
turret head 5 working tool holder 52 can be disengaged from holding member
49. To introduce the starting positlon of driving spindle 11, housing block
12 is llfted by means of feed drive 36 to its upper limit whereby also
spline shat 35 ls lifted along by means of its collar 63 and splineless
section 65 of shaft 35 is in the range of coupling gear 42 so that the latter
is disengaged from driving wheel 20 and driving splindle 11 when brought
into its starting position is thus disconnected-~`from its drive. Gear 41 at
the lower end of spline shaft 35~ in contrast, remains in engagement with
gear 59 for driving turret wheel 5~ while the step down end 64 of shaft 35
is lifted above indexing recess 61 in the upper surface of turret wheel 5.
Main drive motor 22 keeps running and rotates, via transmission means 21,
driving wheel 20, spline shàft 35 and meshing gears 68, the turret wheel 5
untll a new worktool carrier 52 is brought into alignment w:ith clriving
spindle 11. In the program controlled machine of this inveTItion it is not
necessary to drive turret wheel 5 stepw.ise but instead the suitable program
can bring any selected tool into alignment with driving spindle 11. As
soon as the selected worktool is flush with spindle 11, the program provides
for driving housing block 12 downwardly, holding member 49 disengages top
member 46 and biasing means 50 urge working tool carrier 52 against the bot-
tom of driving spindle 11 so that coupling of the tool to the spindle is
completed. Biasing spring 65 in the casing of driving wheel 20 causes spline
shaft 35 at the beginning of the downward movement of housing block 12 to
follow the latter so that gear 41 disengages gear 59 on the axle of turret
wheel 5 and the latter is fixed in its position relative to the bottom of
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56~
the head housing by the step down end 62 which enters the underlying indexing
recess 61. During the further feeding movement the uppermost splined section
of shaft 35 engages the correspondlng grooves in the central boring of
coupling ge!ar 42 30 that torsional moment is imparted to the latter and con-
sequently driving spindle 11 together with worktool carrier~52 start rotating.
This position durlng the feeding movement in downward direction is indicated
in FIGURE 7 whlch shows the coupling of spindle 11 to tool carrier 52 and
turret wheel 5 is fixed in its position by the lower end of spline shaft 35.
In the embodiment illustrated in FIGURE 8 the machine tool of
this invention is again construc~ed as a drill machine having a~combined
drive for dri~ing the spindle and turret wheel. Construction parts corres-
ponding to those in the embodimants according to FIGURES 1 to 7 are desig-
nated by like reference numerals.
Driving shpindle 11 in this embodiment is again in the form of a
spline shaft axially movable in the grooved central boring of the driving
wheel 20 and passing ~hrough coupling gear 39 adapted for engagin gear 59
connected to the axle of turret wheel 5. The lower end of driving spindle
11 is terminated with a frustoconical clutch member 70 which is engageable
with matching recess in coupling gear 39 to es~ablish frictional comlection
therebetween. Thc worktool carrier 52 CollSists again of drive spindle 6
with a gear box 23 including suitable transmission gears. Gear box 23 is
connected to feed mechanism which moves spindle 6 in axial direction in
sleeve 71 provided in wheel 5. Coupling part 70 connected to the lower end
of driving spindle 11 is extended downwardly to form a coupling body 69
provided witha peripheral groove engaging a coupling fork connected at
its free ends to a piston of a cylinder-piston unit 29 arranged in housing
block 12. Similarly as in the preceding examples, duct 12 accommodates
nut 18 of ~eed mechanism. The jacket wall of turret wheel 5 is provided
S~
wlth indexing recesses 61 to which engage the piston rod 72 of separate
c~linder-piston unit 73. Cylinder-plston units are con-trolled hydraulically
~ia switching valve 74.
FIGUR~ 8 illustrates the drill machine of this invention in its
operational position in which feed mechanism 36 moves housing block 12
downwardly and this downward movement is imparted both to driving spindle 11
and to drill spindle 6. The feeding is again program con~rolled. As soon as
a working cycle is completed, the feed mechanism 36 retracts both the driven
spindle 6 and~driving spindle 11. At a cer~ain upper limit position of the
driving spindle 6 the driving spindle 11 together with its coupling body
69 is still further lifted by means of hydraulic drive unit 29 so that
frictlonal coupling between the driving spindle 11 and driven spindle 6 is
disconnected and instead frustoconical coupling element 70 engages corres-
pondlng recess in coupling wheel 39 and turret wheel 5 is brought via gear
69 into rotational movement. With the actuation o-~ power unit 29 there is
also activated power unit 73 :in the direction in which piston rod 72 is
disengaged from indexing recess 61 and the rotation of turret wheel 5 is
released. Subsecluently a new drill spindle is brought :into its operative
position where it is in alignment with drivin~ spindle 11 and in this posi-
tion hydraulic power unit 29 drives coupling body 69 together with coupling
element 70 downwardly. As a consequence, frictional coupling between
driving spindle 11 and driven spindle 6 is re-established and the entire
deuice 37 for worktool exchange is disconnected. Thereupon hydraulic power
unit 73 is operated to engage its bolt or piston rod 72 into the new index-
ing recess 61 in the jacket of turret wheel 5.
