U.S. patent application number 09/779525 was filed with the patent office on 2001-09-27 for machining apparatus capable of saving different fluids in machining.
This patent application is currently assigned to DISCO CORPORATION. Invention is credited to Sekiya, Kazuma.
Application Number | 20010023691 09/779525 |
Document ID | / |
Family ID | 18590627 |
Filed Date | 2001-09-27 |
United States Patent
Application |
20010023691 |
Kind Code |
A1 |
Sekiya, Kazuma |
September 27, 2001 |
Machining apparatus capable of saving different fluids in
machining
Abstract
In order to provide a machining apparatus which can save fluids
such as water, compressed air and clean air, it comprises at least
a spindle unit including a rotary spindle having a machining
element attached thereto for effecting a required machining work on
a workpiece and a spindle housing rotatably bearing the rotary
spindle, and means for supplying the spindle unit with fluid for
use in machining the workpiece. The means for supplying the spindle
unit with fluid has a flow control provided in the fluid flowing
passage for controlling the flow rate of the fluid in response to
the rotating and stopping of the rotary spindle, thereby saving
such fluid. Also, a controlled small quantity of such fluid is
allowed to flow in the spindle housing after the machining is
stopped, thereby retaining the thermal condition without being
changed until the machining is resumed. Thus, no thermal
calibration is required when the machining apparatus resumes
work.
Inventors: |
Sekiya, Kazuma; (Tokyo,
JP) |
Correspondence
Address: |
ARENT FOX KINTNER PLOTKIN & KAHN, PLLC
1050 Connecticut Avenue, N.W., Suite 600
Washington
DC
20036-5339
US
|
Assignee: |
DISCO CORPORATION
|
Family ID: |
18590627 |
Appl. No.: |
09/779525 |
Filed: |
February 9, 2001 |
Current U.S.
Class: |
125/13.01 |
Current CPC
Class: |
B28D 5/007 20130101;
B28D 5/0076 20130101; B28D 5/0064 20130101 |
Class at
Publication: |
125/13.01 |
International
Class: |
B28D 001/04 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 15, 2000 |
JP |
2000-72160 |
Claims
What is claimed is:
1. A machining apparatus comprising: at least means for holding a
workpiece to be machined; a spindle unit comprising a rotary
spindle having a machining element attached thereto for effecting a
required machining work on the workpiece and a spindle housing
rotatably bearing said rotary spindle; and means for supplying said
spindle unit with fluid for use in machining said workpiece,
wherein means for supplying said spindle unit with fluid includes a
flow control provided in the fluid flowing passage for controlling
the flow rate of said fluid in response to the rotating and
stopping of said rotary spindle.
2. A machining apparatus according to claim 1, wherein said means
for supplying said spindle unit with fluid comprises at least a
cooling water source, a coolant feeding conduit for feeding said
spindle housing with cooling water, and a coolant draining conduit
for draining all the cooling water from said spindle housing after
use; said coolant feeding conduit having a first control valve as
said flow control, thereby reducing or stopping cooling water to
said spindle housing when said rotary spindle is not rotating.
3. A machining apparatus according to claim 1, wherein said spindle
housing has a pneumatic bearing for bearing said rotary spindle
with high-pressure air, said spindle housing being connected to a
high-pressure air supply via an associated air duct.
4. A machining apparatus according to claim 3, wherein said air
duct is equipped with a second control valve as air flow control,
which is responsive to non-rotating of said rotary spindle for
preventing the high-pressure air from flowing to said spindle
housing.
5. A machining apparatus according to claim 1, wherein it further
comprises demisting means for drawing and removing the mist from
the working area where the machining element confronts the
workpiece, allowing machining liquid to sputter in the form of
mist, said demisting means including a duct opening at the working
area for drawing the mist from the working area, said duct being
equipped with a flow control.
6. A machining apparatus according to claim 5, wherein said flow
control comprises a fan and/or a third control valve, which may be
made to stop its rotation or may be closed in response to absence
of mist.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a machining apparatus for
use in cutting, grinding or effecting any other machining.
[0003] 2. Related Arts
[0004] Referring to FIG. 9, a dicing apparatus for cutting
semiconductor wafers into small square pieces has a spindle unit 24
equipped therewith. The spindle unit 24 has a rotary spindle 22
air-borne in its spindle housing 23 by ejecting air streams from
radial bearings 39 and thrust bearings 40 at an increased pressure.
Thus, the rotary spindle 22 having a dicing blade 18 fixed to its
end is floated in non-contact condition within the spindle housing
23. Even when the rotary spindle 22 is not rotating, the
high-pressure air is supplied from a high-pressure air source 43 to
the spindle housing 23 via an associated air channel 41. As shown,
the rotary spindle 22 is integrally connected to the shaft of a
synchronous motor 29a. When the synchronous motor 29a is driven,
the rotary spindle 22 and the dicing blade 18 are rotated.
[0005] While the dicing blade 18 is rotated at an increased speed,
the spindle unit 24 is lowered, and then, water is ejected from a
pair of water nozzles 94 toward a semiconductor wafer W, which is
carried and moved back and forth by the chuck table 15 of the
dicing apparatus, thereby permitting the dicing blade 18 to cut the
semiconductor wafer W.
[0006] Rotation of the rotary spindle 22 at an increased speed will
cause thermal expansion of the rotary spindle 22 and spindle
housing 23, thus allowing the dicing blade 18 to be displaced
relative to the semiconductor wafer W. The deviation thus caused
adversely affects the accuracy of the cutting. Cooling water is
supplied to the spindle housing 23 ceaselessly even when the rotary
spindle 22 is not rotating, thus cooling the spindle 22 with the
result that the dicing blade 18 is prevented from moving apart from
the correct position. With recourse to this remedy, however, a lot
of cooling water is required uneconomically.
[0007] While dicing a semiconductor wafer, cooling water is ejected
to the machining area to produce a debris-abundant mist by cutting
the semiconductor substance, thus causing some parts of the
machining apparatus to be contaminated with the debris when exposed
to such mist. To prevent such contamination it is necessary that
the debris-abundant mist be purged from the machining area to the
outside. The dicing apparatus, however, is installed in the
air-cleaning room. Clean air, therefore, is removed from the
air-cleaning room all the time. This is uneconomical because
air-cleaning costs much.
[0008] The rotary spindle 22 needs to be kept in floating condition
all the time by applying high-pressure air to the rotary spindle 22
via the radial and thrust bearings 39 and 40. This is uneconomical,
too.
[0009] Any machining apparatus having a machining tool attached to
its rotary spindle other than the dicing apparatus has the same
problem as described above.
SUMMARY OF THE INVENTION
[0010] One object of the present invention is to provide a
machining apparatus having a machining tool attached to its
spindle, which can save fluids such as water, compressed air and
clean air.
[0011] To attain this object a machining apparatus comprising: at
least means for holding a workpiece to be machined; a spindle unit
comprising a rotary spindle having a machining element attached
thereto for effecting a required machining work on the workpiece
and a spindle housing rotatably bearing said rotary spindle; and
means for supplying said spindle unit with fluid for use in
machining said workpiece, is improved according to the present
invention in that said means for supplying said spindle unit with
fluid includes a flow control provided in the fluid flowing passage
for controlling the flow rate of said fluid in response to the
rotating and stopping of said rotary spindle.
[0012] Said means for supplying said spindle unit with fluid may
comprise at least a cooling water source, a coolant feeding conduit
for feeding said spindle housing with cooling water, and a coolant
draining conduit for draining all the cooling water from said
spindle housing after use; said coolant feeding conduit having a
first control valve as said flow control, thereby reducing or
stopping cooling water to said spindle housing when said rotary
spindle is not rotating.
[0013] Said spindle housing may have a pneumatic bearing for
bearing said rotary spindle with high-pressure air, said spindle
housing being connected to a high-pressure air supply via an
associated air duct.
[0014] Said air duct may be equipped with a second control valve as
air flow control, which is responsive to non-rotating of said
rotary spindle for preventing the high-pressure air from flowing to
said spindle housing.
[0015] A machining apparatus may further comprise demisting means
for drawing and removing the mist from the working area where the
machining element confronts the workpiece, allowing machining
liquid to sputter in the form of mist, said demisting means
including a duct opening at the working area for drawing the mist
from the working area, said duct being equipped with a flow
control.
[0016] Said flow control may comprise a fan and/or a third control
valve, which may be made to stop its rotation or may be closed in
response to absence of mist.
[0017] Other objects and advantages of the present invention will
be understood from the following description of a machining
apparatus according to one preferred embodiment of the present
invention, which is shown in accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWING
[0018] FIG. 1 is a perspective view of a dicing apparatus to which
the present invention can be applied;
[0019] FIG. 2 is a perspective view of the cutting means of the
dicing apparatus of FIG. 1;
[0020] FIG. 3 is a perspective view of the spindle housing of the
cutting means;
[0021] FIG. 4 is a block diagram of a control system for supplying
the spindle housing with cooling water;
[0022] FIG. 5 is a block diagram of a control system for supplying
the spindle housing with a controlled high-pressure air;
[0023] FIG. 6 is a block diagram of a control system for drawing
the mist from the working area;
[0024] FIG. 7 is a block diagram of another control system for
drawing the debris-abundant mist from the working area;
[0025] FIG. 8 is a perspective view of a grinding apparatus to
which the present invention can be applied; and
[0026] FIG. 9 is a longitudinal section of the spindle unit of a
conventional dicing apparatus.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENT
[0027] FIG. 1 shows a dicing apparatus 10 to which the present
invention can be applied. It can be used in cutting semiconductor
wafers into small square pieces. A frame F has a semiconductor
wafer W attached thereto with an adhesive sheet T. A plurality of
frames each having a semiconductor wafer W attached thereto are
stored in a cassette 11.
[0028] These frames are transferred one by one from the cassette 11
to the tentative storage area 13 with the aid of taking
out-and-putting in means 12, and the frame F is transferred from
the tentative storage area 13 to the chuck table 15 with the aid of
a first transferring means 14.
[0029] Then, the chuck table 15 is moved in the -X-direction to be
put just below the picture-taking means 16. From the picture of the
semiconductor wafer W thus taken by the picture-taking means 16,
the alignment means 17 locates a selected street along which the
semiconductor wafer W is to be cut. The semiconductor wafer W is
moved in the -X-direction, allowing the cutting means 19 to cut the
semiconductor wafer W along the so located street with the dicing
blade 18 while machining water is ejected toward the machining
area. Every time the semiconductor wafer W is cut along a selected
street, the semiconductor wafer W is displaced a street-to-street
distance laterally in the Y-axial direction to resume the cutting
of the semiconductor wafer along another street by moving the chuck
table 15 in the X-axial direction.
[0030] After completing the cutting of all streets in same
directions, the chuck table 15 bearing the semiconductor wafer W is
made to turn 90 degrees, and then the cutting is resumed and
repeated in the orthogonal direction in the same way as described
above. Thus, the semiconductor wafer W is cut into small
squares.
[0031] The mist is produced in the machining area 20 from the
scattering of water and debris. The debris-abundant mist thus
produced is sucked and removed from the dust opening 21 to the
outside of the dicing apparatus 10.
[0032] Referring to FIG. 2, the cutting means 19 is composed of the
dicing blade 18 as the spindle unit 24 having the rotary spindle 22
rotatably supported by the spindle housing 23, and a Y-axial slider
25 for moving the spindle unit 24 in the Y-axial direction and an
X-axial slider 26 for moving the spindle unit 24 in the X-axial
direction.
[0033] As shown in FIG. 3, the spindle housing 23 comprises a
cylindrical body 27, a tip piece 28 and a base 29 containing a
synchronous motor 29a, all parts being connected together.
[0034] The rotary spindle 22 can be inserted in the hollow cylinder
body 27, which has coolant channels 30 formed longitudinally in its
circumferential thickness to communicate with the corresponding
coolant channels of the base 29. One half of the coolant channels
30 are connected to cooling water source 32 via a first control
valve 31 whereas the other half of the coolant channels 30 are
connected to a drain.
[0035] The tip piece 28 has reentrant channels formed therein. Each
reentrant channel is connected on one end to a selected
coolant-feeding channel, which is connected to the cooling water
supply 32, and connected on the other end to a selected
coolant-removing channel, which is connected to the drain. With
this arrangement the cooling water passes from the cooling water
supply 32 to the drain via the coolant-feeding channels, the
reentrant channels and the coolant-removing channels.
[0036] Referring to FIG. 4, the first control valve 31 is connected
to the joint between the cooling water source 32 and the coolant
feeding cannel 30 for controlling the flow rate of the cooling
water.
[0037] The first control means 33 is connected to a
spindle-rotation detector 34, which is connected to the synchronous
motor 29a in the base 29 to make a decision in terms of whether the
rotary spindle 22 is rotated or not. One example of such
spindle-rotation detector 34 is an ampere meter.
[0038] As shown in FIG. 4, the first control means 33 comprises an
instruction dispatching section 33a for dispatching an "on" or
"off" instruction to the first control valve 31 and a timer section
35 for instructing the rotary spindle 22 to run at a selected time.
The timer section 35 comprises an idling-time storing sub-section
36 for storing a length of time for which the rotary spindle is
allowed to run idle, a machining start time storing sub-section 37
for storing time at which a required machining starts, and a time
measuring section 38 informing what time it is now.
[0039] Assuming that a semiconductor wafer W held on the chuck
table 15 is cutting into small squares by rotating the rotary
spindle 22 having a dicing blade 18 attached thereto at an
increased speed (see FIG. 1), the spindle 22 and spindle housing 23
are heated to expand somewhat in the Y-axial direction, thus
allowing the dicing blade 18 to traverse the semiconductor wafer W
accordingly. To prevent the dicing blade 18 from being displaced
laterally, cooling water is supplied to the spindle housing 23 via
the coolant channel 30, as seen from FIG. 3.
[0040] Specifically when the first control valve 31 is made to open
in response to the instruction from the first control means 33,
cooling water flows from the cooling water supply 32, passing
through the coolant channels 30 of the spindle housing 23 to be
drained.
[0041] Assuming that the machining is interrupted (for example, one
hour), the spindle-rotation detector 34 detects the stopping of the
rotary spindle 22, realizing that the dicing apparatus has stopped.
If no cooling water were supplied to the spindle housing 23, the
idling of the dicing apparatus would be necessitated while being
fed with cooling water, thereby putting the dicing apparatus into
the pre-interruption thermal condition before resuming the
machining. With a view to eliminating the necessity of effecting
such an extra idling, the dicing apparatus is supplied with a
controlled small quantity of cooling water to keep the rotary
spindle at the same temperature as the cooling water even after
interruption of machining. Thanks to the saving of the extra
idling, the workability or working efficiency can be improved
accordingly.
[0042] In case that the dicing apparatus 10 stops working for a
relatively long time (for example, 10 hours), the supplying of
cooling water is made to stop completely. In order to assure that
the dicing apparatus can resume the machining with the same
accuracy as the accuracy with which it was machining prior to
interruption, the dicing apparatus is allowed to run idle while the
cooling water and the machining water are being supplied to the
spindle housing 23 and the machining area respectively, and while
the high-pressure air are being supplied to the radial bearings 39
and the thrust bearings 40, allowing the rotary spindle 22 and the
dicing blade 18 to rotate at an increased speed. Thus, while the
dicing apparatus is running idle, the cooling water and
high-pressure air are drained all the time.
[0043] The idling-time storing sub-section 36 of the first control
means 33 stores a predetermined length of time for idling, and the
machining start time storing sub-section 37 stores time scheduled
for resuming the machining (see FIG. 4). These sub-sections are set
for idling and resuming by using the console 70.
[0044] When the length of time determined by subtracting the
present time given by the time measuring section 38 from the time
set for resuming the machining at the machining start time storing
sub-section 37 is equal to the length of time set for idling at the
idling-time storing sub-section 36, the first control valve 31 is
made to open automatically, thus supplying the cooling water to the
coolant channel 30, and at the same time, the synchronous motor 29a
is driven.
[0045] At the same time, an air stream of high-pressure is supplied
to the radial pneumatic bearings 39 and the thrust pneumatic
bearing 40 of the spindle housing 23 via the air channel 41 to
suspend the rotary spindle 22 within the spindle housing 23, as
seen from FIG. 5.
[0046] As shown in the drawing, the air channel 41 is connected to
the compressed air source 43 via the second control valve 42. The
second control valve 42 is connected to the second control means
44, thereby allowing the second control valve 42 to be opened under
the control of the second control means 44. Specifically the first
control means 33 dispatches an idling start instruction to the
second control means 44 so that the second control means 44 puts
the second control valve 42 in its opening position, thereby
communicating the air channel 41 with the compressed air source 43.
The first control means 33 allows the synchronous motor 29a to
start running approximately 10 seconds later.
[0047] The second control means 44 is connected to the
spindle-rotation detector 34. The spindle-rotation detector 34
detects that the rotary spindle 22 is put in the "off" condition
after the required machining is completed, and then, the rotary
spindle 22 stops completely subsequent to the continuous running
under its inertia, which lasts for instance, 60 seconds after the
"off" condition. Then, the second control means 44 puts the second
control valve 42 in its closing position. Thus, the compressed air
can be saved.
[0048] Referring to FIG. 6, the dicing apparatus has a drain
opening 21 in its machining area 20, which drain opening 21 is
connected to the drain duct 46 via the third control valve 45.
[0049] The third control valve 45 is connected to the third control
means 47, which in turn, is connected to the spindle-rotation
detector 34. The third control valve 45 is opened when the
spindle-rotation detector 34 detects the rotary spindle 22
rotating, and the third control valve 45 is closed when the
spindle-rotation detector 34 detects the rotary spindle 22
stopping. When machining water is ejected toward the machining area
20, the mist is produced, and the so produced mist is drawn into
the duct 46 by rotating an extractor fan 50, which is driven by an
associated motor 48. When the rotary spindle 22 is stopped to
produce no mist, the motor 48 is stopped under the control of the
third control means 47. As seen from FIG. 7, the dicing apparatus
60 may have the fan 61 positioned outside of the apparatus.
[0050] When the third control means 33 allows the rotary spindle 22
to rotate, the spindle-rotation detector 34 detects the rotary
spindle 22 turning, and then, the third control means 47 realizes
that the cutting of a semiconductor wafer starts, putting the third
control valve 45 in its opening position, thereby drawing the mist
from the machining area 20.
[0051] When the cutting is finished, the spindle-rotation detector
34 detects the rotary spindle 22 stopping, and then, the third
control means 47 realizes that the cutting of the semiconductor
wafer is finished, putting the third control valve 45 in its
closing position, or stopping the running of the fan 50, thereby
stopping the demisting operation. Thus, the demisting operation is
made to cease in response to the stopping of the rotary spindle 22,
thereby limiting exhaustion of expensive clean air to possible
minimum.
[0052] As may be understood from the above, the feeding of cooling
water and high-pressure air, and the drawing of the mist are
effected continuously so long as the rotary spindle 22 is running,
and such feeding and drawing operations are made to stop in
response to the stopping of the rotary spindle 22. Thus, the
quantity of cooling water and high-pressure air to be supplied and
the quantity of clean air to be wasted can be reduced to possible
minimum. This is significantly advantageous from the point of
economical view. An automatic idling is performed to the extent
that same machining accuracy is assured after the machining is
resumed.
[0053] All of the first, second and third control valves 31, 42 and
45 are described as being capable of opening and closing, thereby
controlling the feeding of cooling water, the feeding of
high-pressure air, and the drawing of clean air. When occasions do
not require the entire first, second and third control valves 31,
42 and 45, selected one or ones may be used to meet occasional
demand.
[0054] The present invention can be equally applied to machining
apparatus other than the dicing apparatus. One example of such
machining apparatus is a grinding apparatus 80 as shown in FIG. 8.
The grinding apparatus 80 has a vertical wall 82 rising upright
from the rear end of the base 81 thereof, and the vertical wall 82
has a pair of rails 83 fixed on its front. A slide plate 84 is
slidably attached to the opposite rails 83. The slide plate 84 has
a spindle unit 85 fixed thereon. The base 81 has a turntable 86
rotatably fixed to its upper surface, and the turntable 86 has a
chuck table 87 for holding a workpiece such as a semiconductor
wafer. As the slide plate 84 is raised and lowered, the spindle
unit 85 is raised and lowered so that it may be brought close to
and apart from the semiconductor wafer held by the chuck table
87.
[0055] The spindle unit 85 has a rotary spindle 88 rotatably
supported in its housing 89, and the rotary spindle 88 has a mount
90 fixed to its end. A grinding wheel 91 is attached to the mount
90 so that the grinding wheel 91 may be driven by rotation of the
rotary spindle 88.
[0056] In operation the semiconductor wafer held on the chuck table
87 is brought just under the grinding wheel 91, and then, the
spindle unit 85 is lowered while the rotary spindle 88 is rotated.
Water is ejected toward the machining area, and the rotary spindle
88 and the grinding wheel 91 are rotated at an increased speed to
be pushed against the semiconductor wafer, thereby grinding the
semiconductor wafer.
[0057] The rotary spindle 88 is suspended by the high-pressure air
ejected from the radial and thrust bearings of the spindle housing
89 in the same way as the spindle unit 24 of FIG. 5. Preferably the
feeding of high-pressure air to the spindle housing 89 is stopped
when the rotary spindle 88 is not driven.
[0058] The thermal expansion of the rotary spindle 88 will cause an
error in grinding the semiconductor wafer to a desired thickness.
To prevent the thermal expansion of the rotary spindle 88, cooling
water is made to flow in the spindle housing 89, passing from the
inlet 92 to outlet conduit 93 through the coolant channel of the
spindle housing 89. Preferably the feeding of cooling water to the
spindle housing 89 is stopped when the rotary spindle 88 is not
driven.
[0059] As is the case with the dicing apparatus, the grinding
apparatus uses a spindle-rotation detector and a flow control
responsive to a signal from the spindle-rotation detector
representing non-rotation of the rotary spindle 88 for stopping the
feeding of cooling water and high-pressure air, which is
advantageous from the point of economical view.
[0060] As may be understood from the above, when the rotary spindle
of the dicing apparatus, the grinding apparatus or any other
machining apparatus is not running, the feeding of cooling water
and high-pressure air, and removal of clean air for demisting are
stopped automatically, thereby preventing these fluids from being
wasted, which is advantageous from the point of economical
view.
[0061] Also, the feeding of machining water can be made to start or
stop dependent on whether the rotary spindle is driven or not,
thereby making an effective, economical use of machining water
[0062] While the rotary spindle is not running, a controlled small
amount of cooling water is allowed to flow in the spindle housing,
thereby keeping the rotary spindle at the same temperature as the
cooling water all the time. Thus, idling preliminary to resumption
of machining can be omitted, and the workability or working
efficiency can be improved accordingly.
[0063] Even if the feeding of cooling water has been stopped
completely, a required idling prior to resumption of machining can
be automatically effected by feeding cooling water to the spindle
housing for a stretch of time long enough to provide the same
thermal condition as was prevailing before the machining was
stopped, thereby assuring that the machining be effected with same
accuracy.
* * * * *