U.S. patent number RE31,627 [Application Number 06/328,423] was granted by the patent office on 1984-07-10 for quill drive with variable feed.
This patent grant is currently assigned to The Gleason Works. Invention is credited to Larry Evans.
United States Patent |
RE31,627 |
Evans |
July 10, 1984 |
Quill drive with variable feed
Abstract
A quill drive comprising a housing adapted for mounting on
machine tools. A quill is slidably mounted in a longitudinal bore
in the housing, and is longitudinally positioned by a ball screw.
The ball screw is driven for longitudinal positioning of the quill
by a variable speed, reversible motor. The quill rotatably supports
a spindle for driving various cutting tools. The spindle is
advanced longitudinally by the quill and is rotatably driven by a
second motor. The quill drive can be used singly or in a multiple
arrangement on transfer machines or other automatic equipment. The
unique design has fewer parts resulting in a simple reliable,
relatively inexpensive device which is compact and easy to use. A
relatively simple modification of the gear box converts the quill
drive into a drive for tapping threaded holes.
Inventors: |
Evans; Larry (Sterling Heights,
MI) |
Assignee: |
The Gleason Works (Rochester,
NY)
|
Family
ID: |
26986367 |
Appl.
No.: |
06/328,423 |
Filed: |
December 7, 1981 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
Reissue of: |
923459 |
Jul 10, 1978 |
04201271 |
May 6, 1980 |
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Current U.S.
Class: |
74/89.31;
173/146; 408/137; 74/841 |
Current CPC
Class: |
B23Q
1/70 (20130101); B23Q 5/40 (20130101); F16H
25/2018 (20130101); Y10T 74/173 (20150115); F16H
2025/2081 (20130101); Y10T 408/6793 (20150115); Y10T
74/1864 (20150115); F16H 25/2204 (20130101) |
Current International
Class: |
B23Q
1/70 (20060101); B23Q 5/40 (20060101); B23Q
5/22 (20060101); B23Q 1/00 (20060101); F16H
25/20 (20060101); B23Q 005/033 (); F16H
027/02 () |
Field of
Search: |
;74/89.15,424.8R,841
;173/19,29,145,146,152,165,166 ;408/14,126,137 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Schran; Donald R.
Attorney, Agent or Firm: Basile, Weintraub & Hanlon
Claims
Having thus described my invention, what I claim is: .[.1. A quill
drive with variable feed comprising:
a quill shaft slidably mounted for movement along its longitudinal
axis;
a spindle shaft rotatably mounted for rotation with respect to said
quill shaft and carried longitudinally by said quill shaft during
its longitudinal movements.
a first motor drivably connected to an input shaft, said input
shaft rotatably mounted within said spindle shaft;
said input shaft having disposed along its inner end a male
spline;
said male spline drivingly engaging a female spline disposed at one
end of said spindle shaft, said male spline providing rotational
drive from said input shaft to the female spline of said shaft
during the longitudinal movement of said quill shaft;
said quill shaft being of tubular construction and having attached
thereto a ball nut as its inner end and within its inside
diameter;
a ball screw threadingly engaging said ball nut, said ball screw
being of tubular construction, the inside diameter of said ball
screw tube surrounding but not touching the outer diameter of the
inner end of said quill shaft, said ball screw extending inwardly a
distance equal to the desired longitudinal travel of said quill;
and
said ball screw being rotatably supported at its outer end and
driven at its outer end by a variable speed, variable direction
motor, the speed and direction of said variable speed and variable
direction motor determining the direction and rate of feed of said
quill..]. .[.2. The quill drive with variable feed as defined in
claim 1 wherein said variable speed, variable direction motor is an
electrical stepper motor..]. .[.3. The quill drive with variable
feed as defined in claim 1 wherein said variable speed, variable
direction motor is a hydraulic motor..]. .[.4. The quill drive with
variable feed as defined in claim 1 wherein said first motor and
said variable speed and variable direction motor are drivingly
connected to said input shaft and said ball screw by means of
gearing..]. .[.5. The quill drive with variable feed as defined in
claim 1 wherein said first motor and variable speed and variable
direction motor are drivingly connected to said input shaft and
said ball screw by means of timing belts..]. .[.6. 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 rotation 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;
an adjustable stop for fixedly establishing the maximum
longitudinal motion of said quill, said adjustable stop being a
ring with a threaded inner diameter, said ring being threadingly
attached to the innermost end of said quill, the threaded inner
portion of said quill extending along the length of said quill a
distance not exceeding the length of said quill's longitudinal
motion, said ring abutting the inner wall of said one end of said
housing when the maximum motion of said quill is reached;
means for adjusting the position of said ring along the threaded
length of said quill and for locking said ring in its desired
position; and
means for stopping the extension of said quill shaft when said ring
abuts said wall..]. .[.7. A tapping quill drive capable of
accommodating an infinite variety of threaded pitches comprising: a
quill shaft slidably mounted for movement along its horizontal
axis;
a spindle shaft rotatably mounted for rotation with respect to said
quill shaft during its longitudinal movement;
a spindle shaft rotatably mounted for rotation with respect to said
quill shaft and carried longitudinally by said quill shaft during
its longitudinal movement;
an input shaft for rotationally driving said spindle shaft during
its longitudinal motion;
a drive shaft for longitudinally translating said quill shaft;
means for longitudinally translating said quill shaft a fixed
amount per revolution;
means for fixing the rotational ratio between said input shaft and
said drive shaft so that for one revolution of said spindle shaft
said quill shaft advances a fixed amount;
means for varying said rotational ratio an infinite amount so that
any amount of longitudinal motion of said quill per revolution of
said spindle shaft is available;
reversible drive means for driving said spindle shaft and said
drive shaft; and
an adjustable stop means contained within the quill housing for
varying the maximum longitudinal position of said quill..]. .[.8. 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 rotation 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
longitudinal motion of said quill, said stop being a ring with a
threaded inner diameter, said ring threadably engaging the
innermost end of said ball screw, the threaded portion of said ball
screw extending along the length of said ball screw a distance,
said ring abutting said ball nut when the maximum motion of said
quill is reached..]. .Iadd. 9. In a variable speed quill drive
including a housing having a front and a rear end and means
defining an elongate bore extending through said housing from the
front end thereof, a shaft rotatably mounted in said housing
adjacent the rear end thereof and projecting forwardly in coaxial
relationship within said bore, an elongate spindle coaxially
mounted on said shaft and projecting forwardly from said shaft,
spline means coupling said spindle to said shaft to accommodate
axial movement of said spindle relative to said shaft and said
housing while rotatively locking said spindle to said shaft, and
first variable speed drive means for driving said shaft in
rotation; the improvement comprising a hollow ball screw member
having a threaded section substantially axially coextensive with
said spline means rotatably mounted in said housing and coaxially
surrounding said spindle, independent second variable speed drive
means for driving said screw in rotation, a ball nut operatively
received on said threaded section of said screw, an elongate hollow
quill member slidably received in said bore and fixedly mounted at
its rearward end upon said ball nut and projecting forwardly from
said bore beyond the front end of said housing, means on said
housing remote from said bore constraining said quill member
against rotation within said bore, bearing means adjacent the front
end of said quill member rotatably mounting said spindle within
said quill member in fixed axial relationship thereto, said spindle
projecting forwardly from said bearing means beyond the front end
of said quill member, rotary seal means at the front end of said
quill member sealingly engaged with the periphery of said spindle,
nonrotary sliding seal means at the front end of said housing
sealing said quill to said housing around the entire periphery of
said bore, and adjustable annular stop means coaxially mounted
within said bore establishing a forward end limit of movement of
said quill relative to said housing..Iaddend..Iadd. 10. The
invention defined in claim 9 wherein said stop means comprises an
annular stop and an annular stop surface coaxially located within
said bore in axial alignment with each other, said stop being
threadably mounted on one of said members for adjustment axially of
said one of said members, said one of said members being axially
movable relative to said stop surface. .Iaddend..Iadd. 11. The
invention defined in claim 10 wherein said one of said members is
said quill member and said stop surface is defined by a radial
shoulder in said bore. .Iaddend..Iadd. 12. The invention defined in
claim 10 wherein said one of said members is said ball screw and
said stop surface is defined by one end of said nut. .Iaddend.
Description
BACKGROUND OF THE INVENTION
I. Field of the Invention
The present invention relates generally to the field of quill
drives for machine tools and, in particular, to quill drives having
an infinitely variable feed.
II. Description of the Prior Art and Prior Art Statement
Constituted in the prior art are the following U.S. Pat. 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 arrangement to accomplish the
feed function.
In the opinion of the Applicant U.S. Pat. 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.
U.S. Pat. No. 3,885,635 drives a ball nut in the longitudinal
center of the unit as well to achieve the feed drive, and in
addition, U.S. Pat. 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
construction.
SUMMARY OF THE INVENTION
The present invention relates to a quill drive having a housing
adapted for mounting on machine tools of various type. The quill
housing has a longitudinal bore which slidingly supports a quill
which, in turn, is longitudinally 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 bearings 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 converts the quill drive to a tapping drive for
producing threaded holes.
It is therefore, an object of this invention to provide a quill
with infinitely variable and reversable feed which is simple in
construction, reliable in operation, and inexpensive to produce in
comparison to others.
It is further object of this invention to provide a quill drive
which is easily convertable 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.
Other objects, advantages and applications of the present invention
will become apparent to those skilled in the art of quill drives
when the accompanying description of one example of the best mode
for practicing the invention is read in conjunction with the
accompanying drawing.
BRIEF DESCRIPTION OF THE DRAWINGS
The description herein makes reference to the accompanying drawings
wherein like reference numerals refer 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 FIG. 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 .[.fexedly.]. .Iadd.fixedly
.Iaddend.attached to the quill housing 40. A quill drive motor 50
is attached to the gear box housing 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 to 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 to 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 preventing the seepage of lubricant thereby. Quill
38 is tubular 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 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 rotating 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). Removing 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, in its 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.
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.
Referring now to FIG. 8 wherein there is illustrated another means
for adjusting the maximum extension of quill 38. Quill 38 has its
innermost end threaded along its outside diameter for a distance. A
stop ring 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
54' 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 reversable
drive motor 50' having a shaft .[.24.]. .Iadd.24' .Iaddend.is
fastened to housing 25'. Bearing housing 27' abuts the other end of
housing 25'. A gear train comprising pinion gear 70, idler gear 72
and driven gear 74 transmits the rotation of shaft .[.24.].
.Iadd.24' .Iaddend.to ball screw 44. Ball screw 44 is rotationally
supported by bearings 43 and 47. A female keyway on gear 70 is
driven by a mating male key on shaft .[.24.]. .Iadd.24'.
.Iaddend.Gear 70 is rotationally supported by bearings 140 and 141
in bearing housing 27' and has at its end a threaded portion for
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 58 in its
axial position.
The gear ratio between gear 70 and gear 74 is conveniently selected
so that only a variation in the diameter of shiv 58 and shiv 62 is
required to change the 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 thread
fasteners (not shown). Cover 142 conceals the belt 64 and shivs 58
and 62.
Referring now to .Iadd.FIG. 2 and .Iaddend.FIG. 3 wherein gear box
70' has been adapted for heavy duty tapping. Shivs 58 and 62 and
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.
Gears 76 and 80 directly replace shivs 58 and 62 on their
respective shafts 30 and .[.70.]. .Iadd.71'.Iaddend.. Gears 77 and
78 are each rotatably supported by a pair of bearings 143 mounted
in bearing housing 27' 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.
.Iadd.FIGS. 4 and 5 are respective overall side and front end views
of the drive. The two drive motors 50 and 22 are mounted at the
rear end of the quill housing in stacked relationship to each
other. This arrangement provides convenient access to both motors
and to a drive control arrangement which may take the form of limit
switches such as 86, 90 and 94 mounted upon the top of the quill
housing as shown in FIGS. 4-6. .Iaddend.
Referring 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 forward 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 a
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 FIG. 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. When the master
start button 104 is pressed, the relay 106 is energized and holds
itself closed. If the selector switch 108 is in the "manual"
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 energizes the rapid
forward relay 116. The unit will move "rapid forward" as long as
button 114 is pressed until the feed the switch 118 is closed by
its cam. When feed switch 118 is closed a relay 120 is energized
and relay 116 is deenergized. Relay 120 energizes a relay 122 and
holds it in until the limit switch 124 is closed energizing 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 effect. 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 selector switch 108 in its "auto" position, pressing 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 130 for rapid return. The quills
longitudinal motion comes to a stop when limit switch 132 is
reached 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 infintely
variable feed quill 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 type of machine tools or transfer
machines.
The present invention has a unique arrangement of very few parts in
a simple assembly providing many advantages 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
performance 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. The simplicity of design
becomes apparent when it is compared 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. All functions of the machining cycle are
performed by means of a D.C. 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 return 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 reversible DC motor is used for the feed drive
and spindle drive which are geared or belted by means of a timing
belt to produce 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 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 stop are standard equipment. Mounting
position is not critical, in fact vertical nose up or down, wall
mounted or ceiling mounted or any angle in between will not effect
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
being concentric with the quill provides a precise repeatable stop
with great accuracy compared to the conventional external stop
which is mounted on the machine frame and is offset from the quill
center.
* * * * *