U.S. patent application number 10/392295 was filed with the patent office on 2004-03-25 for adapter for agile fixturing automation.
Invention is credited to Bartos, Andrew Leslie, Bojda, Phillip A., Jones, Gary Lee, Kramarczyk, Mark A., Lin, Yhu-Tin.
Application Number | 20040056401 10/392295 |
Document ID | / |
Family ID | 31997390 |
Filed Date | 2004-03-25 |
United States Patent
Application |
20040056401 |
Kind Code |
A1 |
Kramarczyk, Mark A. ; et
al. |
March 25, 2004 |
ADAPTER FOR AGILE FIXTURING AUTOMATION
Abstract
An adapter for picking up and placing a fixture element on a
fixture body using a controlled tool handling device having a tool
translating and rotating spindle. The spindle has a tool receiving
end and an axis of rotation. The adapter receives a cylindrical
post member of a fixture element on a fixture body. The adapter has
a first end having a receptacle for receiving the end of the
spindle. The second end of the adapter is displaced from the first
end and includes a cylindrical socket formed on the end. The socket
is co-axial with the spindle and receives the cylindrical post
member of the fixture element. A fluid passage is formed in the
adapter from the receptacle to the cylindrical socket. The
cylindrical socket has an upstream end and a down stream end. A
piston is disposed in the upstream end of the socket. The piston is
moveable longitudinally within the socket in response to fluid
pressure delivered from the spindle through the fluid passage. The
downstream end of the socket has a circumference with radially
inwardly protruding bayonet pins for engaging a circumferential
groove of the cylindrical post member.
Inventors: |
Kramarczyk, Mark A.;
(Westland, MI) ; Jones, Gary Lee; (Farmington
Hills, MI) ; Bartos, Andrew Leslie; (Clarkston,
MI) ; Lin, Yhu-Tin; (Rochester Hills, MI) ;
Bojda, Phillip A.; (Macomb, MI) |
Correspondence
Address: |
KATHRYN A. MARRA
General Motors Corporation
Legal Staff, Mail Code 482-C23-B21
P.O. Box 300
Detroit
MI
48265-3000
US
|
Family ID: |
31997390 |
Appl. No.: |
10/392295 |
Filed: |
March 18, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60413188 |
Sep 24, 2002 |
|
|
|
Current U.S.
Class: |
269/71 |
Current CPC
Class: |
B23Q 16/001 20130101;
B25B 5/16 20130101 |
Class at
Publication: |
269/071 |
International
Class: |
B23Q 001/25 |
Claims
What is claimed is:
1. A double-ended adapter tool for use with a numerically
controlled machine tool having a rotatable and translatable spindle
to locate a fixture element on a fixture body, said spindle having
a tool receiving end and an axis of rotation, and said fixture
element having a cylindrical post member, said cylindrical post
member having a circumferential groove, said adapter tool
comprising: a first end having a receptacle member with a
receptacle for fixedly receiving said tool receiving end of said
spindle, said receptacle member having a longitudinal axis
coincident with said axis of rotation of an inserted spindle; a
second end, displaced from said first end, said second end
comprising a cylindrical socket, centered on said axis of rotation
of said receptacle, for receiving and holding said cylindrical post
member of said fixture element; a fluid passage from said
receptacle to said cylindrical socket; said cylindrical socket
having an upstream end and a down stream end, said socket having a
piston disposed in the upstream end of said socket, the piston
being moveable longitudinally within the socket in response to
fluid pressure delivered from said spindle through said fluid
passage, and the downstream end of said socket having an internal
circumference with radially inwardly protruding bayonet pins for
engaging said circumferential groove; whereby in the operation of
said adapter tool, said cylindrical post is received into said
downstream end of said socket into engagement with said bayonet
pins and fluid pressure applied to said piston moves it into
contact with said cylindrical post member to secure said fixture
element.
2. The adapter tool of claim 1 comprising a screw for retaining
said piston against movement beyond a boundary of said socket.
3. The adapter tool of claim 1 wherein the bayonet pins are
disposed equidistant around a circumference of said socket.
4. The adapter tool of claim 1 wherein the cylindrical post member
further includes slots formed around the circumference
corresponding to positions of the bayonet pins of the adapter
tool.
5. The adapter tool of claim 4 wherein the slots intersect the
groove and allow the bayonet pins to enter the groove, wherein
spindle rotation of the adapter tool moves the bayonet pins until
juxtaposed with detents formed in the groove.
6. The adapter tool of claim 5 wherein the locking piston actuates
in response to the delivered fluid pressure moving the piston into
contact with said cylindrical post member whereby the bayonet pins
move into the detents for securely retaining the fixture
element.
7. A double-ended adapter tool for use with a numerically
controlled machine tool having a rotatable and translatable spindle
to locate a fixture element on a fixture body, said spindle having
a tool receiving end and an axis of rotation, and said fixture
element having a cylindrical post member, said cylindrical post
member having a circumferential groove, said adapter tool
comprising: a first end having a receptacle member with a
receptacle for fixedly receiving said tool receiving end of said
spindle, said receptacle member having a longitudinal axis
coincident with said axis of rotation of an inserted spindle; a
second end, displaced from said first end, said second end
comprising a cylindrical socket, centered on said axis of rotation
of said receptacle, for receiving and holding said cylindrical post
member of said fixture element; a fluid passage from said
receptacle to said cylindrical socket; said cylindrical socket
having an upstream end and a down stream end, said socket having a
piston disposed in the upstream end of said socket, the piston
being moveable longitudinally within the socket in response to
fluid pressure delivered from said spindle through said fluid
passage, and the downstream end of said socket having an internal
circumference with radially inwardly protruding bayonet pins for
engaging said circumferential groove; whereby in the operation of
said adapter tool, said cylindrical post is received into said
downstream end of said socket into engagement with said bayonet
pins and fluid pressure applied to said piston moves it into
contact with said cylindrical post member to secure said fixture
element; said receptacle member further comprising a chamber
opening axially opposite said receptacle, said chamber having a
hollow cylindrical member opening terminating in a shaft for
sliding telescopic engagement with said socket member, said shaft
having a terminal flange, said socket member comprising a
cylindrical element adapted for telescopic engagement with said
shaft.
8. The adapter tool of claim 7 comprising a retaining collar, which
is attached in a removable manner to said socket member and
engaging said terminal flange.
9. The adapter tool of claim 7 comprising a screw for retaining
said piston against movement beyond a boundary of said socket.
10. The adapter tool of claim 7 wherein the bayonet pins are
disposed equidistant around a circumference of said socket.
11. The adapter tool of claim 7 wherein the cylindrical post member
further includes slots formed around the circumference
corresponding to positions of the bayonet pins of the adapter
tool.
12. The adapter tool of claim 11 wherein the slots intersect the
groove and allow the bayonet pins to enter the groove, wherein
spindle rotation of the adapter tool moves the bayonet pins until
juxtaposed with detents formed in the groove.
13. The adapter tool of claim 12 wherein the locking piston
actuates in response to the delivered fluid pressure moving the
piston into contact with said cylindrical post member whereby the
bayonet pins move into the detents for securely retaining the
fixture element.
14. The adapter tool of claim 7 further including an anti-rotation
pin disposed between said socket member and said terminal
flange.
15. The adapter tool of claim 7 wherein said chamber includes a
compliant member disposed therein.
16. The adapter tool of claim 15 wherein the compliant member is
compressed within the chamber for preventing damage to the adapter
tool in response to a crash condition wherein said socket member is
driven into said hollow cylindrical member.
17. The adapter tool of claim 15 wherein the retaining collar has a
variable length to adjustably preload a force and displacement of
the compliant member.
Description
This application claims priority to U.S. Provisional Application
No. 60/413,188 filed Sep. 24, 2002.
TECHNICAL FIELD
[0001] This invention pertains to adapters. More specifically, this
invention relates to adapters for retaining and moving fixture
elements associated with a work fixture.
BACKGROUND OF THE INVENTION
[0002] There is a need in manufacturing operations for durable and
reconfigurable workholding fixtures especially for flexible
manufacturing operations. The fixtures must be readily and
accurately adaptable to hold different workpiece shapes for
machining applications or the like. Sometimes the workpieces are
similar or related part shapes such as cast aluminum cylinder heads
for different engines. In other manufacturing situations the parts
may be of unrelated design but requiring similar manufacturing
operations. In these varied applications, the fixture
reconfiguration or changeover from one part design to another has
to be fast enough to meet the productivity requirements of current
manufacturing systems.
[0003] One innovative fixture utilizes the portability of a flat,
very powerful electro-permanent magnetic chuck to provide freedom
in position maneuverability and autonomous hydraulic modular
elements to provide the automated part support or clamp functions.
Such a fixture and modular elements are described in patent
application Ser. No. 10/243,860 which is commonly owned by the
assignee of the present invention and is herein incorporated by
reference. Each autonomous integrated modular clamping or
supporting element consists of a hydraulic screw pump, a hydraulic
cylinder, such as a typical swing clamp cylinder or a compliant
member extended work support cylinder, and a steel base plate. The
steel base plate provides a channel for hydraulic fluid flow
between the hydraulic screw pump and hydraulic cylinder. The base
is made of ferromagnetic material so that it is strongly attracted
to a magnetized fixture plate. A NC program can command a simple
nut-runner to torque the screw pump to actuate the hydraulic swing
clamp or support. By packaging the hydraulic power source alongside
with the clamp or support, there is no longer a constraint by any
rigid and fixed hydraulic feed lines. The mounting surface area of
the base plate has been optimized so that there will be enough
magnetic flux to create a sufficiently strong magnetic holding
force to secure the modular base plate to the chuck. Moreover, the
bottom face of the base plate has a specially prepared surface
texture and roughness to further increase the sliding resistance to
any slippage between the base plate and the magnetic chuck during
machining.
[0004] Such a fixture system has the ability to reconfigure a part
holding fixture quickly and automatically at a special fixture
setup station. The fixture setup station is fashioned similar to a
state-of-the-art multi-axis machining center. A "fixture element"
storage magazine and a "fixture element" changer could replace the
traditional cutting tool storage magazine and the automatic cutting
tool changer. The choice of the multi-axis machining center is
because of its higher positioning accuracy capability over a
robotic system. The end of the machine spindle nose requires a
specially designed adapter so that a modular fixture element can be
swiftly attached to or released from it. It is an object of this
invention to provide such an adapter.
SUMMARY OF THE INVENTION
[0005] This invention provides an adapter permitting the use of a
numerically controlled machine in placing fixture elements on the
magnetizible fixture plate described above. The structure of the
adapter is described in a following paragraph.
[0006] Once such an adapter is provided and in a fixture setup
station, the magnetic chuck is brought to the station table, hooked
up to a power source, and energized at a reduced magnetization
level. A modular fixture element, locating, clamping, or supporting
as dictated by the specific part fixture arrangement is gripped by
the fixture element changer from the storage magazine and attached
to the spindle nose adapter provided by this invention. The X- and
Y-drives of the fixture setup station will move simultaneously so
that a precise coordinate position on the flat magnetic chuck is
aligned. The fixture element is then brought very close to the
surface of the magnetic chuck by the motion of the spindle Z-axis.
Once the distance between the fixture element base plate and the
magnetic chuck has reached a pre-determined value, the fixture
element is released by the spindle nose adapter and automatically
attaches itself gently to the magnetic chuck surface by the
magnetic attractive force. The pre-selected reduced magnetization
level is to ensure the fixture element will not be slamming
violently onto the chuck. The fixture setup NC program then
initiates the next round of commands to setup the second fixture
element, the third element, and so on. After all the modular
fixture elements are set up accurately in their respective
positions, the magnetic chuck is fully energized so as to hold the
modular elements with the designed maximum holding power. The part
will be laid on the fixture by an overhead gantry loader or other
material handling equipment. The spindle nose adapter will pick up
a nut-runner adapter (with a built-in torque limiter) from the
storage magazine and actuate the screw pumps in the various
supporting and clamping elements in a prescribed sequence. Finally,
the magnetic chuck together with its fixture elements and the
clamped part is transferred to a designated machining station for
processing.
[0007] In accordance with a preferred embodiment of this invention
an adapter is secured to a rotatable and translatable spindle of a
numerically controlled machine tool. The spindle has a tool
receiving end and an axis of rotation. The adapter receives a
cylindrical post member (such as a screw pump post) of a fixture
element for placement on a fixture body. The adapter has a first
end having a receptacle for receiving the end of the spindle. The
second end of the adapter has a cylindrical socket and is displaced
on a longitudinal axis from the first end. The socket is co-axial
with the receptacle as well as the spindle that is inserted in the
receptacle and sized and shaped to receive the cylindrical post
member of a fixture element. A fluid passage is formed in the
adapter from the spindle receptacle to the cylindrical socket. The
cylindrical socket has an upstream end and a down stream end. A
piston is disposed in the upstream end of the socket. The piston is
moveable longitudinally within the socket in response to fluid
pressure delivered from the spindle through the fluid passage and
against the piston. The downstream end of the socket has a
circumference with radially inwardly protruding bayonet pins for
engaging a circumferential groove provided for such engagement on
the cylindrical post member. In a fixture element placing
operation, a cylindrical post is inserted into the downstream end
of the socket and into engagement with the bayonet pins. The
spindle rotates the adapter to lock the pins into detents in the
groove. Fluid pressure is then applied to the piston moving it into
contact with the cylindrical post member to secure the fixture
element for lifting and placing by the NC machine.
[0008] The numerically controlled machine is actuated to move its
spindle, the adapter and fixture element to place the element on a
fixture plate as described above. When the fixture element has been
magnetically secured to the plate, the fluid pressure is released
and piston no longer is pressed on the top of the screw pump post.
The spindle is turned to remove the bayonet pins from the detents
and groove on the screw pump surface. The spindle is then lifted
from the fixture element carrying with it the adapter and
completing one such placing operation.
[0009] In a preferred embodiment of the invention, the adapter
comprises a compliant member, such as a spring, in a chamber
located between the spindle receptacle and the piston portion of
the socket member. A purpose of the compliant member is to provide
a cushion between the NC machine and its spindle and the fixture
member and plate in the event there is an impediment not permitting
normal placement of the fixture piece.
[0010] Other objects and advantages of the invention will be
understood from a description of preferred embodiments. Reference
will be made to drawing figures that are described in the following
section.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a side view of an adapter of the present invention
located over a fixture element. The NC machine and spindle are not
shown;
[0012] FIG. 2 is another side view of the adapter and fixture
element in which the adapter is aligned with an axis of the groove
of the fixture element;
[0013] FIG. 3 is a side sectional view of the adapter and fixture
element in which the bayonet pins engage the slots formed in the
groove of the fixture element;
[0014] FIG. 4 is a cut-away isometric view detailing the bayonet
pins within the groove of the fixture element and rotating to align
with detents formed in the groove of the fixture element;
[0015] FIG. 5 is a side sectional view of the adapter and fixture
element in which the locking piston engages the post of the fixture
element and the adapter has been rotated thereby moving the bayonet
pins into the detents to securely retain the fixture element within
the adapter.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0016] The practice of the invention will be illustrated by
describing an adapter 5 for securing to the spindle of an NC
machine and used to place a fixture element 3 on a fixture plate
(not shown) as part of a fixture assembly for machining a cast
work-piece.
[0017] In order to facilitate such machining, a part must be
securely held in a fixture so that numerically controlled machine
tools can accurately remove metal from the casting to arrive at its
specified finish dimensions. A reconfigurable, magnetic fixture, as
described above is preferably utilized to support and hold the
part.
[0018] An illustrative modular fixture element 3 for use in
conjunction with the adapter of the present invention is shown in
FIGS. 1-5. Fixture element 3 comprises a hydraulically actuated and
lockable clamping cylinder and arm 10 of a known type. The fixture
element 3 also contains a hydraulic screw pump 12 of a known type.
Hydraulic clamping arm devices suitable for use in the practice of
this invention are commercially available. Various commercial
clamps are available depending upon the height required for clamp
10 and different clamp arm shapes are available. In the described
fixture element 3, hydraulic clamp 10 is used in combination with a
hydraulic screw pump 12. Such pumps are also commercially
available.
[0019] As can be seen in FIG. 1, the hydraulic screw pump 12 is
inserted upright into an elevated portion 18 of a base 20. Screw
pump 12 contains a cylindrical post member 22 with helical threads
(not shown in FIG. 1 but shown in FIGS. 2, 3 and 5) along the
central portion of its length. One end of the cylindrical post
member 22 is inserted in threaded engagement into a hydraulic
cylinder formed in the elevated portion 18 of the base 20. The
upper end 30 of the cylindrical post member 22 is a hexagonal nut
for manual or robotic actuation of the pump 12. Below the hexagonal
nut is a connecting portion 50 of the base 20. Connecting portion
50 is designed to be securely received by the adapter 5. The
connecting portion 50 includes a circumferential groove 52. The
groove 52 is formed between first and second flanges 54, and 56
respectively. The first flange 54 includes vertical slots 58 formed
through the flange 54 and intersecting the groove 52. The slots 58
are positioned around the circumference of the connecting portion
50 at positions corresponding to bayonet pins 34 of the adapter 5,
which will be discussed in more detail below. The groove 52 also
includes detents 51 that engage the bayonet pins 34, as shown in
FIGS. 1, 2 and 4 when the adapter 5 retains the fixture element
3.
[0020] The adapter 5 of the present invention is a double ended
shaft-like tool for connecting a spindle to a fixture element 3.
The adapter 5 comprises a first end 7 having a round, hollow
receptacle 8 for receiving the end of a spindle (not shown) of a
numerically controlled machine (not shown). The second end 9 is
displaced length-wise from the first end 7. The second end 9
comprises a cylindrical socket 11, co-axial with the receptacle 8
and inserted spindle, for receiving and holding the cylindrical
post member 22 of the fixture element 3. A fluid passage 42 is
formed centrally along a length of the adapter 5 extending from the
receptacle 8 of the first end 7 to the hollow, round socket 11 of
the second end 9.
[0021] The cylindrical socket 11 includes an upstream end 13 and a
downstream end 15. A hollow piston 44 is disposed within the
upstream end 13 of the socket 11 and is moveable longitudinally
within the socket 11 in response to fluid pressure delivered from
the spindle of the numerically controlled machine through the fluid
passage 42. The downstream end 15 of the socket 11 is enlarged to
receive flanges 54, 56 of connecting portion 50 of the screw pump
12 and includes radially inwardly protruding bayonet pins 34
disposed about the circumference of the socket 11 for engaging the
circumferential groove 52 of the connecting portion 50.
[0022] In a preferred aspect, the receptacle 8 is a double ended
piece comprising a second hollow receptacle member 36 which is
connected to a first portion 38 of hollow cylindrical member 40
that is fixed relative to the spindle of the machine. The hollow
cylindrical member 40 has a shaft adapted to engage the receptacle
member 36. The hollow cylindrical member 40 preferably includes a
fluid passage 42 formed through the fixed cylinder's center
extending along its axis to allow for fluid pressure to be
delivered to the piston 44, which will be discussed in more detail
below.
[0023] A second portion 45 is connected to the first portion 38 and
comprises a cylindrical element 46 adapted to engage an inner
diameter of the hollow cylindrical member 40. The hollow
cylindrical member 40 and cylindrical element 46 cooperate to
define a chamber 47. A compliant member 48 is disposed in the
chamber 47 to allow for longitudinal movement of the first portion
38 relative to the second portion 45 in the event of a crash
condition, which will be discussed in more detail below.
[0024] A retaining collar 49 engages an outer diameter of the
cylindrical element 46 at a first end 200 and a flange 68 formed on
the hollow cylindrical member 40 at a second end 64 to connect the
cylindrical element 46 and hollow cylindrical member 40. The length
of the retaining collar 49 can be varied to adjustably preload a
force and displacement of the compliant member 48, such that the
movement of the first portion 38 of the adapter relative to the
second portion 45 during a crash condition can be varied. A crash
condition is defined as a condition where the adapter 5 fails to
engage and retain a fixture element 3. A pin 75 is disposed in a
hole 88 formed in the cylindrical element 46 and engages a notch 89
formed in the flange 68 of hollow cylindrical member 40. The pin 75
prevents rotation of the cylindrical element 46 with respect to the
hollow cylindrical member 40.
[0025] The piston 44, as referenced above, is disposed within the
socket 11 and further extends into a bore 92 formed in the
cylindrical element 46, as best seen in FIGS. 3 and 5. The piston
44 is moveable longitudinally within the bore 92 in response to a
delivered fluid pressure. The piston 44 includes an oval slot 94
formed therein. A screw 99 disposed in a circumferential bore 98
formed in the cylindrical element 46 engages the slot 94 to prevent
the piston 44 from moving beyond a boundary of the bore 92.
[0026] Bayonet pins 34 are disposed in a plurality of
circumferential bores 35 formed in the cylindrical element 46. The
bayonet pins 34 engage corresponding slots 58 formed on the fixture
element 3, as discussed above.
[0027] In use, the adapter 5 is stored in a NC machine's tool
magazine, or similar location, during normal machining operations.
When needed for a changeover, the adapter 5 is selected and
installed in the robot or NC spindle, as a conventional tool would
be. The adapter 5 is then lined up with the axis 104 of the mating
groove 52 (see FIG. 2) and advanced along this axis 104 so that the
bayonet pins 34 engage the slots 58 (see FIG. 3). The adapter 5
continues to advance until it is able to rotate the bayonet pins 34
into the groove 52 of the fixture element 3 (see FIG. 4). The
adapter 5 rotates until the bayonet pins 34 align with the detents
51. At this point pressurized fluid from the NC machine (not shown)
travels through the fluid passage 42 into the chamber 47 to force
the piston 44 down against the upper face 106 of the fixture
element 3. At this moment, the adapter 5 retracts, moving the
bayonet pins 34 into the detents 51 and lifting the fixture element
3 free of a fixture (not shown). The fixture element 3 is now
firmly grasped and can be relocated as desired (see FIG. 5). In a
preferred aspect of the invention, the slots 58 are placed equally
around the circumference of the adapter 5. This arrangement allows
the spindle of the NC machine to rotate in the same direction to
engage and disengage the adapter 5 thereby simplifying operation of
the NC machine.
[0028] In the event that the adapter is prevented from reaching its
full advancement, either due to misalignment or contamination of
the mating surfaces, then a crash condition exists. In such a
situation the first portion 38 of the adapter 5 compresses (see
FIG. 5) the compliant member 48 trapped in the chamber 47 as the
cylindrical element 46 slides into the hollow cylindrical member
40.
[0029] While the invention has been described in terms of certain
preferred embodiments it is apparent that other embodiments could
readily be devised by one skilled in the art. The scope of the
invention is to be considered limited only by the following
claims.
* * * * *