U.S. patent application number 09/362106 was filed with the patent office on 2002-01-17 for machine tool with improved tool changer means.
Invention is credited to SUSNJARA, KENNETH J..
Application Number | 20020006853 09/362106 |
Document ID | / |
Family ID | 23424723 |
Filed Date | 2002-01-17 |
United States Patent
Application |
20020006853 |
Kind Code |
A1 |
SUSNJARA, KENNETH J. |
January 17, 2002 |
MACHINE TOOL WITH IMPROVED TOOL CHANGER MEANS
Abstract
A tool changer for a machine tool having a toolhead assembly
including a spindle with means for detachable securing a tool
thereto, generally consisting of at least one means for holding a
tool detachably securable to the spindle, pivotally connected to
the assembly and angularly displaceable in a plane including the
axis of the spindle between a retracted position and an extended
position for transferring a tool between the tool holding means and
the spindle; and means for angularly displacing the tool holding
means between such retracted and extended positions.
Inventors: |
SUSNJARA, KENNETH J.;
(BIRDSEYE, IN) |
Correspondence
Address: |
PETER N LALOS
LALOS & KEEGAN
1146 NINETEENTH STREET NW
FIFTH FLOOR
WASHINGTON
DC
20036
|
Family ID: |
23424723 |
Appl. No.: |
09/362106 |
Filed: |
July 28, 1999 |
Current U.S.
Class: |
483/47 ;
294/110.1; 483/50; 483/51; 483/64; 483/902 |
Current CPC
Class: |
Y10T 483/1752 20150115;
B23Q 3/15539 20161101; Y10T 483/1781 20150115; B23Q 3/1574
20130101; Y10S 483/902 20130101; B23Q 3/1554 20130101; B23Q
2003/155432 20161101; B23Q 3/15536 20161101; B23Q 2003/155421
20161101; B23Q 3/15746 20130101; B23Q 2003/15537 20161101; B23Q
3/15706 20130101; Y10T 483/1855 20150115; Y10T 483/1774 20150115;
B23Q 2003/155446 20161101; Y10T 483/1783 20150115 |
Class at
Publication: |
483/47 ; 483/50;
483/51; 483/64; 483/902; 294/110.1 |
International
Class: |
B23Q 003/157 |
Claims
I claim:
1. A tool changer for a machine tool having a toolhead assembly
including a spindle with means for detachable securing a tool
thereto, comprising: at least one means for holding a tool
detachably securable to said spindle, pivotally connected to said
assembly and angularly displaceable in a plane including the axis
of said spindle between a retracted position and an extended
position for yielding a tool to or accepting a tool from said
spindle; and means for angularly displacing said holding means
between said retracted and extended positions.
2. A tool changer according to claim 1 wherein said holding means
includes a section disposable in axial alignment with said spindle
when said holding means is in said extended position, for yieldably
gripping a tool.
3. A tool changer according to claim 2 wherein said gripping
section includes a set of spring biased portions.
4. A tool changer according to claim 2 wherein said gripping
section includes a set of arcuately spaced, substantially parallel
finger portions, biased radially inwardly relative to the axis of a
circumference including an arc along which said finger portions are
spaced.
5. A tool changer according to claim 1 wherein said holding means
has a J-shaped arm section pivotally connected to said assembly and
a gripping section disposable in axial alignment with said spindle
when said holding means is in said extended position for yieldably
gripping a tool.
6. A tool changer according to claim 5 wherein said gripper section
is disposed on a free end of said arm section.
7. A tool changer according to claim 6 wherein said gripping
section includes a set of arcuately spaced, substantially parallel
finger portions, biased radially inwardly relative to the axis of a
circumference including an arc along which said finger portions are
spaced.
8. A tool changer according to claim 1 wherein said displacing
means is operated by a controller.
9. A tool changer according to claim 1 wherein the operation of
said displacing means is controlled by a program executed by a
controller.
10. A tool changer according to claim 1 wherein said displacing
means comprises a fluid actuated cylinder assembly.
11. A tool changer according to claim 1 wherein said displacing
means comprises an air actuated cylinder assembly.
12. A tool changer according to claim 1 including a plurality of
said displaceable means arcuately spaced relative to the axis of
said spindle, each angularly displaceable between said retracted
and extended positions by a separate displacing means.
13. A tool changer according to claim 12 wherein said displacing
means are selectively operated by a controller.
14. A tool changer according to claim 12 wherein the operation of
said displacing means is controlled by a program executed by a
controller.
15. A toolhead assembly for a machine tool comprising: a support
means mountable on said machine tool; a spindle supported on said
support means and having means for detachably securing a tool
thereto; at least one means for holding a tool detachably securable
to said spindle, pivotally connected to said support means and
angularly displaceable between a retracted position and an extended
position for yielding a tool for attachment to and accepting a tool
detached from said spindle; and means for angularly displacing said
holding means between said retracted and extended positions.
16. A toolhead assembly according to claim 15 wherein said holding
means includes a section disposable in axial alignment with said
spindle when said holding means is in said extended position, for
yieldably gripping a tool.
17. A toolhead assembly according to claim 16 wherein said gripping
section includes a set of spring biased portions.
18. A toolhead assembly according to claim 16 wherein said gripping
section includes a set of arcuately spaced, substantially parallel
finger portions, biased radially inwardly relative to the axis of a
circumference including an arc along which said finger portions are
spaced.
19. A toolhead assembly according to claim 15 wherein said holding
means has a J-shaped arm section pivotally connected to said
support means and a gripping section disposable in axial alignment
with said spindle when said holding means is in said extended
position, for yieldably gripping a tool.
20. A toolhead assembly according to claim 19 wherein said gripping
section is disposed on a free end of said arm section.
21. A toolhead assembly according to claim 20 wherein said gripping
section includes a set of arcuately spaced, substantially parallel
finger portions, biased radially inwardly relative to the axis of a
circumference including an arc along which said fingers are
spaced.
22. A toolhead assembly according to claim 15 wherein said
displacing means is operated by a controller.
23. A toolhead assembly according to claim 15 wherein the operation
of said displacing means is controlled by a program executed by a
controller.
24. A toolhead assembly according to claim 15 wherein said
displacing means comprises a fluid actuated cylinder assembly.
25. A toolhead assembly according to claim 15 wherein said
displacing means comprises an air actuated cylinder assembly.
26. A toolhead assembly according to claim 15 including a plurality
of said displaceable means arcuately spaced relative to the axis of
said spindle, each angularly displaceable between retracted and
extended positions by a separate displacing means.
27. A toolhead assembly according to claim 26 wherein said
displacing means are selectively operated by a controller.
28. A toolhead assembly according to claim 26 wherein the operation
of said displacing means is controlled by a program executed by a
controller.
29. A tool changer system for a machine tool comprising; a toolhead
assembly including a spindle with means for detachably securing a
tool therein; at least one first means for holding a tool
detachably securable to said spindle, pivotally connected to said
assembly and angularly displaceable in a plane including the axis
of said spindle between a retracted position and an extended
position for yielding a tool to or accepting a tool from said
spindle; means for angularly displacing said first holding means
between said retracted and extended position; at least one second
means for holding a tool detachably securable to said spindle
mounted on said machine, accessible to said spindle for yielding a
tool to or accepting a tool from said spindle; and means for
positioning said spindle in relation to said second holding means
for transferring a tool therebetween.
30. A tool changer system according to claim 29 wherein said
spindle includes a collet operable for selectively gripping and
releasing a tool retained by either of said holding means.
31. A tool changer system according to claim 29 wherein said second
holding means is stationary and said spindle is displaceable along
orthogonal x, y and z-axes.
32. A tool changer system according to claim 31 wherein said second
holding means is mounted on a stationary worktable.
33. A tool changer system according to claim 31 wherein the angular
displacement of said first holding means and the displacement of
said spindle along the x, y and z-axes is controlled by a
programmed controller.
34. A tool changer system according to claim 29 wherein said second
holding means is displaceable along an x-axis and said spindle is
displaceable along y and z-axes.
35. A tool changer system according to claim 34 wherein said second
holding means is mounted on a table displaceable along the
x-axis.
36. A tool changer system according to claim 34 wherein the angular
displacement of said first holding means, the displacement of said
second holding means along the y-axis and the displacement of said
spindle along the y and z-axes are controlled by a programmed
controller.
37. A tool changer system for a machine tool comprising: a toolhead
assembly including a spindle with means for detachably securing a
tool thereto; at least one first means for holding a tool
detachably securable to said spindle, pivotally connected to said
assembly and angularly displaceable in a plane including the axis
of said spindle between a retracted position and an extended
position for yielding a tool to or accepting a tool from said
spindle; means for angularly displacing said first holding means
between said retracted and extended positions; at least one second
means for holding a tool detachably securable to said spindle
mounted on a unit separate from said machine, accessible to said
spindle for yielding a tool to and accepting a tool from said
spindle; and means for positioning said spindle in relation to said
second holding means for transferring a tool between said spindle
and said second holding means.
38. A tool changer system according to claim 37 wherein said unit
includes a plurality of said second holding means and means for
indexing selected ones of said second holding means in relation to
said spindle for transferring a tool between said selected second
holding means and said spindle.
39. A tool changer system according to claim 37 wherein said
spindle is displaceable along orthogonal x, y and z-axis.
40. A tool changer system according to claim 37 wherein said
machine includes a workpiece support table displaceable along an
x-axis in said spindle is displaceable along y and z-axes.
41. A tool changer system according to claim 37 wherein first
holding means and said spindle are displaceable responsive to a
program executed by a controller
42. A tool changer system according to claim 37 including at least
one third means for holding a tool detachably securable to said
spindle, mounted on said machine and accessible to said spindle for
yielding a tool to or accepting a tool from said spindle, and
wherein said positioning means also is applicable for positioning
said spindle in relation to said third holding means for
transferring a tool between said third holding means and said
spindle.
43. A tool changer system according to claim 42 wherein said
spindle is displaceable along orthogonal x, y and z-axes.
44. A tool changer system according to claim 42 wherein said
machine includes a workpiece support table displaceable along an
x-axis and said spindle is displaceable along y and z-axes.
45. A tool changer system according to claim 42 wherein said first
holding means and said spindle are displaceable responsive to a
selected program executed by a controller.
46. A tool changer system according to claim 45 wherein said first
displaceable means, said workpiece support table and said spindle
are displaceable responsive to a program executed by a controller.
Description
[0001] This invention relates to CNC machine tools and more
particularly to a tool changer for such machines. The invention
further contemplates a novel automatic tool changer operable to
reduce the cycle times of machining parts requiring the use of
different tools to perform various machining operations.
BACKGROUND OF THE INVENTION
[0002] In many machining operations performed by conventional CNC
machine tools used in the woodworking, plastic and airframe
industries, multiple tasks are required to be performed, requiring
the use of different tools. Initially, tool changes were performed
manually, simply by having the operator interrupt the operation of
the machine, change out the tool and then resume operation. Because
of the time consuming aspect of manual tool changes, automatic tool
changes were developed which generally have involved moving the
toolhead to a tool changer positioned on or adjacent the machine or
moving the tool changer to the toolhead assembly to effect the tool
change. In either of such arrangements, considerable machine motion
and time has been required, resulting still in undue cycle times
and less than optimal productivity. It thus has been found to be
desirable and therefore the principal object of this invention to
provide a tool changer for a CNC machine tool in which tool changes
may be performed with minimal movement and rapidly, thereby
reducing cycle times and correspondingly increasing
productivity.
SUMMARY OF THE INVENTION
[0003] The present invention overcomes the disadvantages of prior
art automatic tool changers by providing a tool changer mountable
on the toolhead assembly of a CNC machine tool generally consisting
of an array of tool holders pivotally connected to the toolhead
assembly and spaced apart relative to the axis of the toolhead
spindle, with each of the tool holders being selectively angularly
displaceable in a plane including the axis of the spindle between a
retracted position and an extended position aligning the tool
holder for loading or unloading a tool with respect to the spindle.
Through the use of the collet on the end of the toolhead spindle,
various tools may not only be loaded and unloaded unto and off of
the spindle but may be transferred between the tool holder assembly
mounted on the toolhead assembly and tool holders either mounted on
other components of the machine or on separate equipment.
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] FIG. 1 is a perspective view of a CNC machine tool embodying
the present invention, illustrating a portion of a conventional
bulk tool changer which comprises a component of another embodiment
of the invention;
[0005] FIG. 2 is a top plan view of the machine tool and bulk tool
changer shown in FIG. 1, having portions thereof broken away;
[0006] FIG. 3 is a side elevational view of the machine tool shown
in FIGS. 1 and 2;
[0007] FIG. 4 is an enlarged top plan view of a gripper section of
a tool holder comprising a component of the embodiment shown in
FIGS. 1 through 3;
[0008] FIG. 5 is a cross sectional view taken along line 5-5 of
FIG. 4;
[0009] FIG. 6 is an enlarged, top plan view of the tool changer
shown in FIGS. 1 through 3, embodying the present invention, having
portions thereof broken away;
[0010] FIG. 7 is an enlarged cross sectional view taken along line
7-7 in FIG. 6;
[0011] FIG. 8 is an enlarged, vertical cross sectional view of the
spindle assembly forming a component of the toolhead assembly shown
in FIGS. 1 through 3; and
[0012] FIG. 9 is and enlarged view of the view shown in FIG. 8,
designated by the reference numeral 9.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0013] Referring to FIGS. 1 through 3, there is illustrated a CNC
machine tool 10 adapted to perform various machining functions on
workpieces positioned thereon including routing, drilling, sawing,
sanding and the like, and a bulk tool changer 11. The machine
generally consists of a base member 12, a movable workpiece support
table 13, a gantry 14, a toolhead support assembly 15 and a
toolhead assembly 16. The base member includes a lower section 17,
a pair of longitudinally disposed, transversely spaced boxed beam
sections 18 and 19 and a set of longitudinally disposed,
transversely spaced guideways 20 and 21. Table 13 is supported and
displaceable longitudinally or along an x-axis or line of travel on
guideways 20 and 21, and includes a rectangularly configured
workpiece support surface 22.
[0014] Gantry 14 includes a pair of leg sections 23 and 24 disposed
astride table 13, rigidly connected at their lower ends to base
section 17, and a bridge section 25 secured to the upper ends of
leg sections 23 and 24, spaced above table 13 and disposed
transversely. The front face of bridge section 25 is provided with
a pair of transversely disposed, vertically spaced guideways 26 and
27 on which there is mounted and guided, toolhead support assembly
15 for displacement transversely along a y-axis or line of travel.
Toolhead assembly 16 similarly is mounted and guided vertically
along a z-axis or line of travel on a pair of vertically disposed,
transversely spaced guideways mounted on a front face of the
toolhead support assembly.
[0015] The toolhead assembly includes a support frame 28 and a
spindle assembly 29, a DC servomotor 30 and a tool changer assembly
31 mounted on the support frame. The spindle assembly is best
illustrated in FIGS. 8 and 9 and is driven through a belt drive by
servomotor 30. Tool changer assembly 31 is best shown in FIGS. 4
through 7. In addition to servomotor 30, the machine is provided
with a number of additional DC servomotors for displacing the table
along the x-axis, displacing the toolhead support assembly along
the y-axis and displacing the toolhead assembly along the z-axis.
Such motors are operated by a controller (not shown) pursuant to
the execution of a program loaded into the controller in the
conventional manner.
[0016] As best shown in FIGS. 4 through 7, tool changer assembly 31
includes a support bracket 32 secured to support frame 28, and a
plurality of arcuately spaced tool holders 33 pivotally connected
to the support bracket. The support bracket includes a base section
32a mounted on the side of the support frame by means of a set of
bolts or other suitable means, and disposed longitudinally,
extending beyond the front end of the toolhead assembly, and a
transversely disposed section 32b, spaced from and extending across
the front of the assembly, substantially at a right angle relative
to the base section. Each of the tool holders consists of an arm
section 34 and a gripper section 35. Each arm section 34 has a
j-shaped portion 34a pivotally connected to bracket section 32b, as
at 34b and an arcuate portion 34c formed integrally on the end of
the J-shaped portion. As best seen in FIGS. 4 and 5, gripper
section 35 includes an arcuate portion 35a mounted on and secured
to arcuate arm portion 34c by means of a set of bolts 35b, and
arcuately spaced sets 35c of finger portions extending into the
space in arcuate arm portion 34c and yieldably biased to engage a
tool 36 therebetween as shown in FIG. 3. Each of the tool holders
is provided with an air actuated cylinder assembly 37 for pivoting
the tool holder between a retracted position as shown in solid
lines in FIG. 7 and an extended position as shown in phantom lines
in FIG. 7 in which tool gripper section 35 is disposed coaxially
with and below a spindle of the toolhead assembly for yielding or
accepting a tool relative to the spindle. Each cylinder assembly
consists of a cylinder member 37a pivotally connected adjacent its
rod end to transverse section 32b of the support bracket as at 37b,
and an extendable rod member 37c pivotally connected to the arm
section of a tool holder as at 37d. The various cylinder assemblies
are operated by the controller pursuant to the execution of a
software program loaded into the controller to selectively extend
and retract selected tool holders for loading and unloading tools
with respect to the spindle. The configuration of the arm sections
and gripper sections of each of the tool holders permits each of
the holders to hold and maintain a tool in a retracted position
clear of the lower end of the spindle so as not to interfere with
any machining operation of the spindle, and an extended position in
which the collet of the spindle may grip or release a tool held by
the holder. The inwardly biased fingers 35c of the gripping portion
of each tool holder will yieldingly grip and hold a tool in the
tool holder permitting the tool to be retained in the extended
position for storage purposes, and displaced from the retracted to
the extended position and easily be released or gripped in
attaching and detaching the tool with respect to spindle.
[0017] Referring to FIGS. 8 and 9, the toolhead assembly includes a
spindle assembly 40 generally consisting of a housing 41, a spindle
42 mounted in the housing and a cylinder assembly 43. The housing
is provided with a lower section 41a and an upper section 41b.
Housing section 41a is provided with a cylindrical bore 41f
therethrough having a first enlarged section 41c at a lower end
thereof, a second enlarged section 45 and a third enlarged section
46 at the upper end thereof. Enlarged bore section 41 cprovides a
bearing seat including an annular wall 41d and an annular seat 41e.
Enlarged section 45 similarly provides a bearing seat including an
annular side wall 45a and an annular seating surface 45b. Provided
in enlarged section 41c is a cylindrical sleeve 47 having the outer
cylindrical surface thereof adhesively bonded to annular wall 41d
of the housing. A pair of roller bearings 48 and 49 are seated in
enlarged bore section 41c with the outer surfaces of the outer
races thereof engaging the inner annular surface of cylindrical
sleeve 47 and an annular end surface of outer race 48 engaging
annular surface 41e of enlarged bore section 41c. Similarly, a
cylindrical sleeve 50 is disposed in enlarged bore section 45 with
the outer cylindrical surface thereof adhesively bonded to the
annular side wall surface 45a of enlarged bore section 45. Disposed
within cylindrical sleeve 50 and axially displaceable relative
thereto is roller bearing 51. The inner races of bearings 48 and 51
are maintained in axially spaced relation by means of a spacer tube
52. A spring washer 53 is provided between the outer race of
bearing 51 and annular surface 45b of enlarged bore section 45.
[0018] Spindle 42 has a generally tubular configuration and is
journaled in lower bearings 48 and 49 and upper bearing 51. Outer
cylindrical surface 60 is provided with a recessed cylindrical
section 61 providing an annular shoulder on which the inner race of
bearing 49 is seated, and an upper threaded portion 62. It further
is provided with an axially disposed bore 63 having a lower, first
enlarged section 64 and a second enlarged section 65 opening into
an end portion 66 provided with a diverging, conically configured
wall 67 adapted to receive an upper portion 68 of a tool 36,
provided with a complimentary conical surface relative to surface
67. The upper end of the tool is provided with a neck portion 70
and a head portion 71 received within enlarged bore section 64 of
the spindle. The upper end of axial bore 63 is provided with an
enlarged section 72.
[0019] The bearings and the spindle journaled in the bearings are
retained within the housing with the bearings seated within
enlarged bore sections 41c and 45 by means of a lower cover plate
80, a bearing washer 81 and a jam nut 82. Cover plate 80 has an
annular configuration and is secured to the bottom end of housing
11 by a set screws. An inner end of plate 80 engages the outer race
of bearing 49 and is provided with a seal 83 engaging the spindle
about the periphery thereof Bearing washer 81 also has an annular
configuration and has a depending, annular portion which engages
the inner race of bearing 51. Jam nut 52 is provided with an axial
bore 84 having an enlarged, threaded section 84a threaded onto the
upper threaded end of the spindle so that it engages bearing washer
81 which bears on the inner race of bearing 51. Outer annular
surface 84b of the jam nut is provided with an annular recess 84c
which is adapted to receive a pair semi-circular retaining flanges
85.
[0020] Upper housing section 41b has a cylindrical configuration
and is adapted to seat on and be secured to the upper end of lower
housing section 41a by means of a set of bolts 86. Such section is
axially aligned with axial bore 41f of lower housing section 41a.
Mounted within upper housing section 41b is a floating cylinder
mount 90 provided with an axially disposed bore 90a aligned axially
with lower housing bore 41f and spindle 42, having a lower enlarged
section 90a which receives the upper end of jam nut 82. Axial
displacement of the cylinder mount is restricted relative to the
spindle by means of retainer plates 85 which are secured to the
underside of the cylinder mount by means of a set of screws, and
project into annual grove 84c of jam nut 82.
[0021] Axially displaceable in spindle bore 63 is a draw bar 100
having a lower enlarged section 101 disposed in enlarged spindle
bore section 64 and an upper enlarged section 102 received in an
upper enlarged section 64a of spindle bore 63. A collet 103 is
provided on the lower end of enlarged draw bar section 101 having a
set of fingers which are adapted to cam inwardly when the draw bar
is urged in an upward direction to grip head portion 71 of the
tool, and to spring apart when the draw bar is moved in a downward
direction to release the head portion of the tool. The draw bar is
urged into the upper position by means of a set of spring washers
105 disposed between an annular shoulder provided by enlarged
spindle bore section 64a and a lower cylindrical surface of
enlarged draw bar section 102.
[0022] Cylinder assembly 43 includes a cylinder 110 retained in a
frame 111 secured to the upper end of cylinder mount 90 and a rod
member 112 which extends through bore 90b of the cylinder mount in
axial alignment with draw bar 100. When rod member 112 is in the
retracted position, it will be out of engagement with enlarged draw
bar section 102 so that spring washers 105 will urge the draw bar
into an upper position causing the fingers of the collet to be
cammed inwardly and grip head portion 71 of the tool and
correspondingly secure the tool to the spindle for performing a
machining function. When the rod member is extended as shown in
FIGS. 8 and 9, the rod member will engage and downwardly displace
the draw bar against the biasing action of spring washers 105,
allowing the fingers of collet 103 to spring apart and thus release
the head portion of the tool, allowing it to be removed from the
lower end of the spindle. The detachment of rod member 112 from
draw bar 100 permits the draw bar to rotate as part of the spindle
assembly during machining operations.
[0023] In the normal operation of the spindle assembly to perform a
machine function, the tool will be received in the lower end of the
spindle and firmly gripped by the collet formed on the lower end of
draw bar, and the spindle with the tool will be free to rotate
relative to the housing, the cylinder mount and the cylinder
assembly. When it is desired to change the tool, the spindle drive
is discontinued, suitable controls are operated to supply air under
pressure to the base of the cylinder 110, to extend rod member 112
into engagement with the draw bar against the biasing actin of
spring washers 105, thus causing the collet to displace downwardly
and permit the gripping fingers thereof to spring outwardly,
releasing the tool. A new tool then may be inserted into the lower
end of the spindle and the cylinder assembly operated to allow the
draw bar to displace upwardly under the biasing action of the
spring washers thus causing the gripping fingers of the collet to
be cammed inwardly and grip the upper end of the tool.
[0024] Most machining operations on a particular workpiece have
been found not to require more than five tools to perform the
desired machining operation. Accordingly, up to five tools required
by a particular software program to be run may be inserted in one
or more of the tool holders carried by the toolhead assembly to
perform the desired machining operation. Once the appropriate
number of tools have been loaded on the tool changer as described,
and the appropriate program has been loaded into the controller of
the machine, the controller will execute the program to load and
unload the proper tools with respect to the spindle and in the
appropriate sequence, the spindle will be stopped and started as
required and the toolhead assembly will be displaced along the x, y
and z axes to perform the programmed machining operation. Whenever
a tool on the spindle is to be changed, the spindle will be
stopped, a selected air cylinder will be operated to angularly
displace a selected tool holder from the retracted to the extended
position below and in axial alignment with the tool attached to the
lower end of the spindle to grip the tool, the tool head assembly
will be displaced downwardly along the z-axis to position the
attached tool in the aligned tool holder permitting the spring
biased fingers of the tool holder to grip the tool, cylinder
assembly 43 will be operated to extend the draw bar of the spindle
assembly to cause the fingers of collet 103 to spring outwardly and
release the tool, and the air cylinder for such a tool holder is
operated to displace the tool holder from the extended position
shown in phantom lines in FIG. 7 to the retracted position as shown
in solid lines therein. The machine is then ready to receive
another tool carried by the tool changer. Such loading occurs
simply by the operation of the cylinder assembly for the other
selected tool whereby the tool holder of the selected tool will be
caused to be angularly displaced from its retracted position to its
extended position, positioning the selected tool below the spindle
in axial alignment therewith. The selected tool is then attached to
the lower end of the spindle by operating cylinder assembly 43 to
allow the collet at the lower end of the spindle to move upwardly,
camming the fingers thereof inwardly to grip and thus retain the
head portion of the selected tool. The tool head assembly may then
be displaced along the z-axis as well as the x and y-axes to
continue the machining operation.
[0025] Each of tool holders 33 mounted on support bracket 32 is
operable to be angularly displaced in a plane including the axis of
spindle 42 so that when displaced from its retracted to its
extended position, its gripper section 35 will be positioned below
and in axial alignment with spindle 42 to permit the relinquishment
or receipt of a tool. Such tool changing operation can be performed
as the toolhead assembly is displaced along the x, y and/or z-axis
of the machine, moving from one coordinate to another. By being
capable of effecting a tool change while the toolhead assembly is
repositioned, the cycle time of the machining operation being
performed is substantially reduced. Furthermore, because of the
simple and lightweight construction of the tool holders, the
dynamics in the displacement of the toolhead assembly are
negligently effected.
[0026] In a sense, tool holders 33 resemble and function like the
arms of an early typewriter in which an arm corresponding to a
certain key would angularly displace and strike a platen upon the
key being pressed.
[0027] To expand the number of tools that may be used to perform a
particular machining operation, the tool changer as described may
be used in conjunction with a conventional tool bar 120 mounted on
the machine or a conventional bulk tool changer 121 as best shown
in FIG. 2. The bar tool changer typically consists of a base plate
122 mounted on the rear edge 123 of the machine table, and a number
of transversely spaced tool grippers 35a which are comparable in
construction and function to tool grippers 35. By displacement of
the machine table along the x-axis and the displacement of the
toolhead assembly along the y and z-axes, spindle 42 may be
positioned in axial alignment with a selected one of tool grippers
35a to relinquish and receive a tool in the manner as described in
connected with tool changer assembly 31. Furthermore, through the
use of the collet arrangement on spindle 42, tools may be
transferred between any of tool grippers 35 and tool grippers
35a.
[0028] Bulk tool changer 11 consists of a separate apparatus which
may be positioned adjacent to the machine and operated in
cooperation with the toolhead assembly by the controller to accept
tools from and provide tools to the spindle of the toolhead
assembly. It consists of a base member 30 which is adapted to be
positioned adjacent a side of a machine table, close to the gantry,
and a carriage 131 mounted on the base member and displaceable
longitudinally. Journaled at each end of the carriage is a
vertically disposed shaft 132 having a gear 133. An endless chain
134 is trained about each of gears 133 and is provided with a
plurality of tool grippers 35b spaced along the length thereof.
Each of tool grippers 35b is similar to each of tool grippers 35 of
tool changer assembly 31 and tool grippers 35a of bar tool changer
assembly 120, and may be positioned below and in axial alignment
with spindle 42 of the toolhead assembly. The bulk tool changer is
provided with various drives for longitudinally displacing the
carriage thereof and rotating a gear shaft 132 to index the tool
grippers, thus permitting a selected one of tool grippers 35b to be
positioned at a location where spindle 42 of the toolhead assembly
may be positioned in axial alignment therewith.
[0029] The toolhead assembly may be used in conjunction with the
bulk tool changer assembly to either change a tool as between
spindle 24 and the bulk tool changer or transfer one or more tools
between the bulk tool changer and toolhead mounted tool changer 31.
This is accomplished merely by operating the controls of the bulk
tool changer to displace the carriage thereof and index the chained
conveyor to position a selected tool thereon to a selected
position, and then operating other machine controls to displace the
toolhead assembly so that spindle 42 may be displaced to a position
above and in axial alignment with a tool retained by a tool gripper
of the bulk tool transfer assembly at the selected position. The
cylinder assembly of the spindle may then be operated to cause the
collet component of the spindle to grip the selected tool in the
manner previously described. If the tool thus retrieved from the
bulk tool changer assembly is to be transferred to a tool holder of
tool changer assembly 31, the selected one of the tool holders of
such assembly is then operated to transfer the tool from the
spindle to the selected tool holder.
[0030] Tool changer assembly 31 may be used independently or in
conjunction with one or both of bar tool changer assembly 120 and
bulk tool changer assembly 121 to provide a greater availability of
tools and a minimum amount cycle time in the performance of a
machining operation. The arrangement further permits a program used
to operate the machine to be devised in a manner whereby prior to
the execution of the machining function with respect to a
particular workpiece, the machine will be caused to select the
appropriate tools from either or both of the bar or bulk tool
changer assemblies and mount them on the toolhead mounted tool
changer assembly. Such preliminary routine would be repeated upon
each new machining procedure.
[0031] To minimize the effects of the additional mass possibly
adversely affecting the dynamics of the movement of the toolhead
assembly, the components of a tool changer assembly 31 are formed
of a lightweight materials such as aluminum, plastic and perhaps
lightweight composite materials. Any form of gripping device may be
utilized allowing for the proper gripping, retaining and releasing
of the various tools used with the assembly.
[0032] Although the invention has been described in the context of
a CNC machine tool utilizing a moveable table and a stationary
gantry, it is contemplated within the scope of the invention may be
used with a CNC machine provided with a stationary table and a
moveable gantry. In either of such arrangements, it further is
contemplated that the toolhead mounted tool changer assembly as
described may be used independently or in conjunction with either
or both a bar tool changer assembly and a bulk tool transfer
assembly as described.
[0033] From the foregoing detailed description, it will be evident
that there are a number of changes, adaptations and modifications
of the present invention which come within the province of those
persons having ordinary skill in the art to which the
aforementioned invention pertains. However, it is intended that all
such variations not departing from the spirit of the invention be
considered as within the scope thereof as limited solely by the
appended claims.
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