Note: Descriptions are shown in the official language in which they were submitted.
37~7
The present invention relates ~enerally to the field
of quill drives for machine tools and, in particular, to quill
drives having an infinitely variable feed.
This application is a divisional application of copend-
ing application No. 343,271 filed January 8, 1980.
Constituted in the prior art are the following United
States Patent Nos. 3,955,629, 3,160,033, 3,711,212, 2,905,440,
2,768,539, 3,640,147, 3,740,161, 3,561,544, 3,859,001, and 3,885,
635. All of the above patents do not anticipate the present
invention in that they use a multiplicity of motors for varying
feed rate, or use planetary gears and clutches to vary feed rate,
or use an offset feed mechanism, or they drive a ball nut arrange-
ment to accomplish the feed function.
In the opinion of the Applicant Patent Nos. 3,859,001
and 3,885,635 constitute the most relevant prior art to the
present invention in that a ball nut disposed in the longitudinal
center of the unit is driven to achieve the feed operation. The
mechanical complexity of this arrangement renders its design more
expensive. Patent No. 3,885,635 drives a ball nut in the longi-
tudinal center of the unit as well to achieve the feed drive,and in addition, Patent No. 3,885,635 uses two feed drive motors
operating at different speeds with clutches to vary the feed rate.
Clearly, the two patents cited as the closest art are far more
complex than the present invention and more costly in their con-
struction.
..~..
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The present invention relates to a quill drive
having a housing adapted for mounting on machine tools of
various types. The quill housing has a longitudinal bore
which slidingly supports a quill which, in turn, is longi-
tudinally advanced by means of a ball nut and screw. The
quill is of hollow construction and it rotatably supports,
by means of bearings, at its interior a spindle shaft. The
spindle shaft is rotatably driven by a spindle drive means
and it is advanced longitudinally with the quill.
A gear box, fixedly attached at one end to the
quill housing, provides a mounting for a quill drive motor
and a spindle drive motor. A gear box cover is attached to
the other end of the gear box. A train of gears provides a
means whereby the quill drive motor drives the ball screw.
The gear box housing and gear box cover provide support for
the bearings which support the gears therebetween.
The ball screw is rotatably supported by bearings
in the quill housing and the gear box cover. An input shaft
which drives the spindle shaft is rotatably supported by a
bearing in the ball screw and the gear box cover. A shiv
fixedly attached to the spindle drive motor drives a timing
belt which in turn drives a shiv fixedly attached to the
input shaft. A simple modification of the gear box wherein
the ball screw and spindle are geared to a common input con-
verts the quill drive to a tapping drive for producing
threaded holes.
L ~1 ~ 7~7
It is therefore, an object of this invention to provide
a quill with infinitely variable and reversible feed which is
simple in construction, reliable in operation, and inexpensive
to produce in comparison to others.
It is further an object of this invention to provide
a quill drive which is easily convertible to a tapping drive with
a minor rearrangement of the parts.
Another object of the present invention is to provide
an adjustable stop for the maximum outward position of the quill
that is concentric with the quill is easily adjustable and is
accurate and repeatable. A meter relay is provided to stop the
advance of the machine when the stop is engaged.
In copending application No. 343,271 there is claimed
a quill shaft drive comprising a housing having an opening at one
end, an elongate quill shaft of hollow tubular construction mount-
ed in said housing for axial sliding movement relative to said
housing wherein one end of said quill shaft is projected through
said opening in rotatively fixed relationship to said housing,
a ball nut fixedly mounted within said quill shaft adjacent the
end thereof remote from said opening, a ball screw of hollow
tubular construction threadably received within said ball nut in
coaxial relationship to said quill shaft and supported for rota-
tion within the quill shaft, a spindle shaft coaxially mounted
within said ball screw and coupled to said quill shaft for free
rotation relative to said quill shaft and said ball screw in
axially fixed relationship to said quill shaft and axially movable
relationship relative to said ball screw, an input shaft coaxi-
ally received within said spindle shaft and mounted for rotation
in said housing, spline means coupling said input shaft to said
spindle shaft, first reversible drive means for driving said ball
screw in rotation to advance or retract said quill shaft, and
second drive means for driving said input shaft in rotation.
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According to the present invention there is provided
a quill drive with longitudinal feed comprising: a quill shaft
slidably mounted within one end of a housing for movement along
its longitudinal axis, a spindle shaft rotatably mounted for ro-
tation with respect to said quill shaft and carried longitudinally
by said quill shaft during its longitudinal movement; means for
longitudinally moving said quill shaft; means for rotationally
driving said spindle shaft; said means for longitudinally moving
said quill shaft comprising a ball nut fixedly attached to the
innermost end of said quill; a ball screw threadingly engaging
said ball nut, and means for rotationally driving said ball screw;
an adjustable stop for fixedly establishing the maximum longitud-
inal motion of said quill, said stop being a ring with a threaded
inner diameter, said ring threadingly engaging the innermost end
of said ball screw, the threaded portion of said ball screw ex-
tending along the length of said ball screw a distance, said ring
abutting said ball nut when the maximum motion of said quill is
reached.
Other objects, advantages and applications of the pre-
sent invention will become apparent to those skilled in the artof quill drives when the accompanying description of one example
of the best mode for practicing the invention is read in con-
junction with the accompanying drawing.
The description herein makes reference to the accompany-
ing drawings wherein like reference numerals refer
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to like parts throughout the several views, and wherein:
FIG. 1 is a cross-sectional view of one example of
a quill drive constructed in accordance with the principles
of the present invention;
FIG. 2 is a fragmentary, enlarged, sectioned view
of a drive train arranged for tapping using timing belts;
FIG. 3 is a fragmentary, enlarged, sectioned view
of a drive train arranged for tapping using a gear train;
FIG. 4 is a side elevational view of the quill
drive illustrated in FIG. 1;
FIG. 5 is a front view of the quill drive of FIG. 4;
FIG. 6 is a top view of FIG. 4 showing a standard
limit switch assembly;
FIG. 7 shows a typical electrical circuit for the
operation of the quill drive;
FIG. 8 illustrates the quill drive of FIG. 1 with
another embodiment of a stop for controlling the fully
extended position of the quill; and
FIG. 9 is a cross-sectional view of FI~. 1 taken
along plane 9-9 of FIG. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENT
___ ___________________________________
Referring now to the drawings and, in particular,
to FIG. 1 wherein there is illustrated one example of the
present invention in the form of quill drive 20. The drive
20 comprises a quill housing 40 having a longitudinal bore
21 which slidingly supports a quill 38. One end of a gear
box housing 25 is fixedly attached to the quill housing 40.
A quill drive motor 50 is attached to the gear box housing
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25. A spindle drive motor 22 is supported by a bracket 23
which, in turn, is carried by the housing 40. A gear box
cover 36 is fixedly attached ts the other end of the gear
box housing 25.
A shiv 24 is fixedly attached to the shaft of the
spindle drive motor 22 such that the shiv 24 transmits power
to a belt 28 which in turn drives a second shiv 26 that is
fixedly attached to and rotatably drives an input shaft 30.
The input shaft 30 is rotatably supported by a bearing 31 in
gear box cover 36 and a bearing 33 in a ball screw 44.
Input shaft 30 has along its inner end a male spline 32
which slidingly and drivingly engages a female spline 35
disposed in the center of a spindle shaft 34.
A torque reaction bar 51 is attached .o the lower
end of quill 38 at its spindle end by means of a threaded
fastener 53. A bore 55 in quill housing 40 slidingly engages
reaction bar 51, preventing rotation of quill 38 thereby.
Spindle shaft 34 is rotatably mounted within and
longitudinally carried by a pair of bearings 39 in quill 38.
A seal retainer 41 supports a shaft seal 45 which rotatingly
seals spindle 34 against the seepage of lubricant thereby.
Quill 38 is slidably supported by a longitudinal bore 21 in
quill housing 40. A seal 49 slidingly seals quill 38, pre-
venting the seepage of lubricant thereby. Quill 38 is tubu-
lar in shape, and at its innermost end it fixedly supports a
ball nut 42. Ball nut 42 threadingly engages ball screw 44
which is rotatably supported by a bearing 43 in housing 36
and bearing 47 in housing 40. A gear 46 is drivingly
attached by a key 49 to ball screw 44. Ball screw 44 is
driven by an idler gear 48 and a pinion 52. Idler gear 48
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is rotatably supported by a pair of bearings 61 in gear case
25 and cover 36. Pinion 52 is fixedly attached to the shaft
of a Servo motor 50. Servo motor 50 is a variable speed,
two-direction motor which provides means to move quill 38
longitudinally in either direction at any desired speed.
Ball screw 44 has its innermost end threaded along
the outside diameter for a predetermined distance. A stop
ring 54 threadingly engages a threaded portion 45 of ball
! screw 44. When quill 38 is fully extended, stop ring 54
contacts the inner end of ball nut 42, preventing further
motion. The position at which quill 38 is stopped is varied
by rotflting stop ring 54, moving it axially along the inner
end of ball screw 44. A set screw 56 locks stop ring 54 in
place. An access hole 60 allows adjustment of stop ring 54
(FIG. 9). ~emoving a plug 61 allows stop ring 54 to be
rotated by means of a screw driver or the like, thereby
moving stop ring 54 axially along ball screw 44 by means of
thread 45. When the desired position of stop ring 54 is
established, set screw 56 is tightened and plug 61 is
reinstalled.
The fully extended position of the quill 38 can be
controlled by means of limit switches which are cam operated
and adjustable in a conventional manner. However, this
method has inaccuracies caused by deflection of the parts~
inertia of the moving parts, dirt or chips on the cam or
rollers, wear, etc. The use of stop ring 54 is positive; it
is concentric to the quill and highly repeatable with great
accuracy. A meter relay 136 (FIG. 7) is provided as part of
the electrical circuit to stop the motion of the quill when
the stop ring 54 comes against ball nut 42.
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67
The adjustable meter relay 137 (FIG. 7) is included
in the electrical circuit to provide a load sensitive
machining operation allowing a maximum rate of feed for a
maximum amount of metal removal consistent with the capacity
of the machine or the desired machine finish.
~ eferring now to FIG. 8 wherein there is
illustrated another means for adjusting the maximum exten-
sion of quill 38. Quill 38 has its innermost end threaded
along its outside diameter for a distance. A stop rin~ 54'
threadingly engages the threaded portion 47' of quill 38'.
When quill 38' is extended to the adjusted amount, stop ring
54' contacts the end wall of housing 40, preventing further
motion. The position at which quill 38' is stopped is
varied by rotating stop ring 54', moving it axially along
the threaded portion of quill 38'. A set screw 56' locks
stop ring 54' in place. Access hole 60 allows adjustment of
the stop ring 54' using a screw driver or the like as in the
embodiment illustrated in FIG. 9. The meter relay 136 (FIG.
7) is provided as part of the electrical circuit to stop the
rotation of the ball screw and the quill motion when stop
ring 541 contacts the housing.
Referring now to FIG. 2 wherein gear box 70' has
been adapted for tapping. Housing 25' is fixedly attached
at one end to quill housing 40 by suitable threaded fasteners
(not shown). A reversible drive motor 50' having a shaft 24
is fastened to housing 25'. A gear train comprising pinion
gear 70, idler gear 72 and driven gear 74 transmits the
rotation of shaft 24 to ball screw 44. Ball screw 44 is
rotationally supported by bearings 43 and 47. A female
7t~7
keyway on gear 70 is driven by a mating male key on shaft
24. Gear 70 is rotationally supported by bearings 140 and
141 in bearing housing 27' and has at its end a threaded
portion ~or threadingly engaging a nut 62'. The outer races
of bearings 140 and 141 abut shoulders in bearing housing
27'. A shiv 62 is rotationally supported by gear shaft 70.
Tightening bearing nut 62' axially aligns gear 70 and shiv
62 by means of bearings 140 and 141, abutting their
shoulders in bearing housing 27' at their outer races. A
key 63 rotationally affixes gears 70 to shiv 62. Shiv 62
drives timing belt 64, and timing belt 64 drives a shiv 58
which is rotationally attached to input shaft 30 and drives
input shaft 30 by means of a key 63'. Input shaft 30 is
rotationally supported by bearing 31' in bearing housing
27'. Bearing nut 30' threadingly engages a thread on the
end of shaft 30 to hold shiv S8 in its axial position.
The gear ratio between gear 70 and gear 74 is con-
veniently selected so that only a variation in the diameter
of shiv 58 and shiv 62 is required to change $he amount of
advance quill 38 makes per revolution of spindle shaft 34.
To make, for example, on a piece to be machined, a thread
having twelve threads per inch, the shivs 58 and 62 are
selected to give an advance of quill 38 (FIG. 1) in the
amount of 1/12 inch per revolution of input shaft 30. A
cover 142 is attached to the end of the bearing housing 27'
using threaded fasteners (not shown). Cover 142 conceals
the belt 64 and shivs 58 and 62.
Referring now to FIG. 3 wherein gear box 70' has
been adapted for heavy-duty tapping. Shivs 58 and 62 and
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timing belt 64 have been replaced by a meshing set of gears
76, 77, 78 and 80 which perform the same function as the
parts replaced. ~ears 76 and 80 directly replace shivs 58
and 62 on their respective shafts 30 and 70. Gears 77 and
78 are each rotatably supported by a pair of bearings 143
mounted in bearing housing 27r and cover 142' respectively.
Gear 77 is only partly shown in FIG. 3, and its supporting
bearings are not shown because the center of gear 77 is not
in the plane of the section.
]o ~eferring now to FIG. 6 wherein a standard limit
switch assembly is illustrated. A cam bar 82 is attached to
quill 38 by screws 84. Cam bar 82 moves longitudinally with
quill 38. In the position shown, quill 38 is retracted and
a limit switch 86 is actuated by a cam 88, holding the quill
in the retracted position. To cycle the machine, a cycle
start button (not shown) is pressed and the quill moves for-
ward in the rapid advance mode until a limit switch 90 is
actuated by a cam 92 which places the quill into the feed
mode. The quill advances in its feed mode until a cam 96
actuates limit switch 94 which activates a dwell followed by
an automatic return motion, returning the quill to its
original position where limit switch 86 is actuated by cam
88 and the machine is ready for another cycle.
Referring now to PIGo 7 wherein a typical wiring
diagram for the quill drive is shown. To place the machine
in operation, the main switch 98 is first closed. Current
then flows to the power transformer 100 and the control
transformer 102. ~hen the master start button 104 is
pressed,
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the relay 106 is energized and holds itself closed. If the sel-
ector switch 108 is in the "m2nual" position to the left, nothing
happens. If selector switch is in the "auto" position the
spindle motor 110 starts by closing the relays 112. Use of the
"manual" position allows the unit to be cycled without the
spindle running preventing tool damage. When the unit is in
the "manual" position, the quill position can be jogged by
pressing the cycle start button 114 which energized the rapid
forward relay 116. The unit will move "rapid forward" as long
as button 114 is pressed until the feed switch 118 is closed
by its cam. When feed switch 118 is closed a relay 120 is ener-
gized and relay 116 is deenergized. Relay 120 energizes a relay
122 and holds it in until the limit switch 124 is closed ener-
gizing the dwell timer 126 which holds closed for a preset time
then it opens. When 126 opens, relay 122 is opened stopping
the feed and pressing button 114 after this has no erfect.
Pressing the button 128 returns the unit by energizing a relay
130. Returning the quill to actuate limit switch 132 which
allows the quill to again be jogged forward by pressing button
114.
With selec~r switch 108 in its "auto" postion, press-
ing button 114 energizes relay 116 which holds itself closed
and which moves the quill forward in rapid feed until switch 118
is closed energizing relay 120. This holds the unit in "feed"
until limit switch 124 is closed energizing time delay 126.
This stops the feed and holds the quill in position for a preset
time after which 126 opens which energizes relay(s) 130 (and
134) for rapid return. The quills longitudinal motion comes to
a stop when limit switch 132 is reached
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and closed by its cam. Meter relay 136 protects the Servo
motor from overload in the event that a tool becomes jammed
or too rapid a feed is used or any other misuse might occur.
The controller 138 can be programmed to give the
desired longitudinal motion to the quill in any of its
modes; even a pecking motion for deep hole drilling can be
used.
While in the above description of the preferred
embodiment an electric Servo motor is used to longitudinally
move the quill, it is obvious to those skilled in the art
that a hydraulic motor, pneumatic motor or the like could be
used to achieve the desired result.
The present invention provides a ball screw
actuated, infinitely variable, feed guill drive having all
mechanical and electrical components. This quill drive is
suitable for reaming, boring, spot facing, chamfering,
hollow milling, recessing, drilling, deep hole drilling and
tapping. The drive can be used either singly or in
multiples on advanced types of machine tools or transfer
machines.
The present invention has a unique arrangement of
very few parts in a simple assembly providing many advan-
tages of both versatility of application and maintenance-
free operation. The above attributes are accomplished
without sacrificing any of the advantages of hydraulics,
such as compactness or ease of adjustments, to vary perfor-
mance and flexibility. There are no clutches or other
engagement and disengagement devices. The gears can be
replaced by timing belts and shivs or "V" belts for lighter
work. No planetary gears or harmonic drive is required.
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The simplicity of design becomes spparent when it is com-
pared to other mechanical feed units which use two or three
motors and/or clutches and brake arrangements to provide
rapid feed, machining feed, dwell, and rapid return. In the
present invention, the spindle drive has only two moving
parts. The rapid advance and feed drive consists of a quill
assembly having a ball nut, a ball screw, three gears or a
belt and shiv assembly. A11 functions of the machining
cycle are performed by means of a DC Servo motor and
controller which provides complete control of rate of rapid
approach, rate of feed, and rate of rapid return. The
amount of thrust in feed, amount of thrust in dwell and
automatic returr. when overloaded is also controllable. With
the addition of a resolver to the motor, limit switches can -
be eliminated and the cycle controlled by programmable
controller or computer. The spindle motor can be either AC
or DC and can be turned off for tool set up. Another
embodiment of the present invention converts the quill drive
for tapping. When arranged for tapping, only the rear
housing and gears or belts are changed and only the revers-
ible DC motor is used for the feed drive and spindle drive
which are geared or belted by means of a timing belt to pro-
duce the required threads per inch. The thrust capability
of the unit (3200 pounds) exceeds self-contained hydraulic
units presently available that mount on the same hole
pattern. Due to the center thrust design and the bearing
construction, the spindle and quill are inherently stable
even under high-load conditions. The extreme flexibility of
the unit is evident by the special cycles which are easily
obtained, such as jump gap, dual feed, back feed, dual back
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feed, forward and back feed, peck feed and any combination
of these, with single or multiple spindle head applications.
A tool change mechanism and single in-line positive stops
are standard equipment. Mounting position is not critical;
in fsct vertical nose up or down, wall mounted or ceiling
mounted or any angle in between will not affect its
operation. All bearings are grease packed for life and the
quill can be lubricated by gravity or automatic system.
An internal, maximum out-position stop is provided.
The stop is easily adjusted through an access hole in the
housing. The stop's being concentric with the quill pro-
vides a precise, repeatable stop with great accuracy com-
pared to the conventional external stop which is mounted on
the machine frame and is offset from the quill center.
Having thus described my invention, what I claim is:
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