U.S. patent application number 11/504042 was filed with the patent office on 2007-02-15 for abrasive water jet cutting machine.
Invention is credited to Shigekazu Kanai, Masayuki Matsubara, Satoshi Tateiwa, Masaaki Yamamoto.
Application Number | 20070037495 11/504042 |
Document ID | / |
Family ID | 37743131 |
Filed Date | 2007-02-15 |
United States Patent
Application |
20070037495 |
Kind Code |
A1 |
Matsubara; Masayuki ; et
al. |
February 15, 2007 |
Abrasive water jet cutting machine
Abstract
To provide an abrasive water jet cutting machine in which an
abrasive recovery unit can be continuously used without needing
maintenance, and an abrasive having a uniform grain size can be
easily recovered, the machine has a catch tank for receiving a
high-pressure abrasive mixture liquid jetted from a jet nozzle, and
an abrasive recovery unit that recovers abrasive having a grain
size in a reusable predetermined range from the abrasive mixture
liquid transported from the catch tank, and transports abrasive
mixture liquid including recovered abrasive into an
abrasive-mixture-liquid retention tank; wherein the abrasive
recovery unit has an abrasive sorting tank which flows the abrasive
mixture liquid transported from the catch tank in an approximately
horizontal direction, and sorts abrasive depending on grain size by
using difference in sedimentation rate depending on grain size, and
recovers the abrasive having the grain size in the reusable
predetermined range.
Inventors: |
Matsubara; Masayuki; (Tokyo,
JP) ; Tateiwa; Satoshi; (Tokyo, JP) ; Kanai;
Shigekazu; (Tokyo, JP) ; Yamamoto; Masaaki;
(Tokyo, JP) |
Correspondence
Address: |
WENDEROTH, LIND & PONACK, L.L.P.
2033 K STREET N. W.
SUITE 800
WASHINGTON
DC
20006-1021
US
|
Family ID: |
37743131 |
Appl. No.: |
11/504042 |
Filed: |
August 15, 2006 |
Current U.S.
Class: |
451/75 |
Current CPC
Class: |
B24C 1/045 20130101;
Y02P 70/10 20151101; Y02P 70/179 20151101; B24C 9/006 20130101 |
Class at
Publication: |
451/075 |
International
Class: |
B24C 3/00 20060101
B24C003/00 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 15, 2005 |
JP |
2005-235481 |
Claims
1. An abrasive water jet cutting machine comprising: an
abrasive-mixture-liquid retention tank for retaining an abrasive
mixture liquid in which an abrasive and a liquid are mixed, a
high-pressure liquid supply unit for feeding out the abrasive
mixture liquid retained in the abrasive-mixture-liquid retention
tank at high pressure by supplying a high-pressure liquid to the
abrasive-mixture-liquid retention tank, a jet nozzle for jetting
the high-pressure abrasive mixture liquid, which is fed out from
the abrasive-mixture-liquid retention tank, to workpiece, a catch
tank for receiving the high-pressure abrasive mixture liquid jetted
from the jet nozzle, and an abrasive recovery unit that recovers
abrasive having grain size in a reusable predetermined range from
the abrasive mixture liquid transported from the catch tank, and
transports abrasive mixture liquid including recovered abrasive
into the abrasive-mixture-liquid retention tank, thereby cutting
the workpiece by the high-pressure abrasive mixture liquid jetted
from the jet nozzle; wherein the abrasive recovery unit has an
abrasive sorting tank that flows the abrasive mixture liquid
transported from the catch tank in an approximately horizontal
direction, and sorts abrasive depending on grain size of the
abrasive by using difference in sedimentation rate caused by grain
size of the abrasive, and recover the reusable abrasive having the
grain size in the predetermined range; the abrasive sorting tank
has a flow inlet provided on an upper portion at one end side, a
flow outlet provided on an upper portion at the other end side, a
first sorting member as a partition member that is set at a side of
the flow inlet in a bottom and divides the bottom, a second sorting
member as a partition member that is set at a side of the flow
outlet in the bottom and divides the bottom, and a first discharge
port set between the first and second sorting members; and when the
abrasive mixture liquid transported from the catch tank flows in
the approximately horizontal direction from the flow inlet to the
flow outlet, the abrasive sorting tank sediments abrasive having a
grain size larger than a maximum of the reusable predetermined
range included in the relevant abrasive mixture liquid in a side
near the flow inlet side compared with the first sorting member,
sediments abrasive having a grain size in the reusable
predetermined range between the first and second sorting members,
and sediments abrasive having a grain size smaller than a minimum
of the reusable predetermined range in a side near the flow outlet
side compared with the second sorting member, and discharges the
abrasive having the grain size in the reusable predetermined range
from the first discharge port and recover it.
2. The abrasive water jet cutting machine according to claim 1,
wherein height of the first and second sorting members may be
changed.
3. The abrasive water jet cutting machine according to claim 1,
wherein the abrasive sorting tank further has a second discharge
port set at a side near the flow inlet compared with the first
sorting member in the bottom, and a third discharge port set at a
side near the flow outlet compared with the second sorting member
in the bottom, so that the abrasive having the grain size larger
than the maximum of the reusable predetermined range is discharged
from the second discharge port, and the abrasive having the grain
size smaller than the minimum of the reusable predetermined range
is discharged from the third discharge port.
4. The abrasive water jet cutting machine according to claim 2,
wherein the abrasive sorting tank further has a second discharge
port set at a side near the flow inlet compared with the first
sorting member in the bottom, and a third discharge port set at a
side near the flow outlet compared with the second sorting member
in the bottom, so that the abrasive having the grain size larger
than the maximum of the reusable predetermined range is discharged
from the second discharge port, and the abrasive having the grain
size smaller than the minimum of the reusable predetermined range
is discharged from the third discharge port.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an abrasive water jet
cutting machine for cutting workpiece by jetting a high-pressure
liquid including abrasive.
[0003] 2. Related Art
[0004] A water jet is a jet stream of high-pressure water formed by
providing energy to water by a super high-pressure pump and the
like, and for example, has flow velocity one to three times faster
than the sound velocity. In these years, methods and machines for
cutting various kinds of workpiece by using the water jet have been
developed. In particular, an abrasive jet is now noticed in order
to improve a cutting efficiency, in which solid abrasive is mixed
in high-pressure water. The abrasive includes a material having
high hardness such as gamet, alumina, and silicon carbide, which
has a granular body having a grain size of, for example, about
several ten to several hundred micrometers. The abrasive collides
with the workpiece at high speed with the high-pressure water so
that the workpiece is cut while being partially broken.
[0005] Such cutting by the water jet has an advantage that the
workpiece can be cut without any thermal effect, and occurrence of
burrs in a cutting surface can be reduced by the abrasive.
Furthermore, the cutting has another advantage that even if a
cutting line is a curved line, the workpiece can be cut without any
difficulty, in addition, it is suitable for cutting a composite
material or a material of hard workability. Therefore, in these
years, a cutting process using the water jet has been investigated
for dicing of a semiconductor substrate, in particular, a packaged
substrate, instead of using a dicing blade as usual.
[0006] In the so-called abrasive water jet cutting machine using
the abrasive jet, the abrasive that was used for the cutting
process is generally recovered for reuse (for example,
JP-A-10-66895 and JP-A-2001-79443). This is because all abrasive
jetted with the high-pressure water from a jet nozzle is not
consumed to contribute to the process in one time of cutting of the
workpiece, therefore if the abrasive is disposable, a large amount
of unconsumed abrasive is disposed, consequently production
efficiency is significantly reduced.
[0007] Thus, the inventors of the application have investigated an
abrasive water jet cutting machine so far, in which abrasive is
automatically circulated to be reusable by using abrasive recovery
apparatus 160 having an abrasive recovery filter 167, as shown in
FIG. 4. In the abrasive water jet cutting machine, as shown in FIG.
4, abrasive mixture liquid in an abrasive-mixture-liquid retention
tank 122a or 122b is fed out at high pressure by high-pressure
water supplied from a high-pressure pump 115, and the high-pressure
abrasive mixture liquid (abrasive jet) J is jetted from a jet
nozzle 130 to workpiece 105 for cutting. Furthermore, the abrasive
mixture liquid J jetted from the jet nozzle 130 is received by a
catch tank 150, and then abrasive having a reusable grain size (for
example, 25 to 100 .mu.m) is recovered from the relevant abrasive
mixture liquid by the abrasive recovery apparatus 160, and
replenished into one of the abrasive-mixture-liquid retention tanks
122a and 122b, which is not being used for the cutting process.
[0008] In the abrasive recovery apparatus 160, the abrasive
recovery filter 167 that was able to transmit grains having a
predetermined size or less (for example, 100 .mu.m or less) was
used, and the abrasive mixture liquid was designed to be flown at a
certain flow velocity (for example, 8 liter/min using a
positive-pressure pump) on the abrasive recovery filter 167 with
the abrasive recovery filter 167 being oscillated, and thus an
abrasive having a grain size in a predetermined range (for example,
25 to 100 .mu.m) passed through the abrasive recovery filter 167
was sorted and recovered. This is because abrasive having
excessively small grain size can not contribute to polishing even
if it is reused, and on the other hand, abrasive having excessively
large grain size may cause dogging of the jet nozzle 130.
[0009] However, in the abrasive recovery apparatus 160 as shown in
FIG. 4, since the abrasive recovery filter 167 is used, meshes of
the abrasive recovery filter 167 may be dogged by the abrasive.
Therefore, a measure was taken, in which the abrasive recovery
filter 167 was regularly cleaned so that the abrasive was separated
from the meshes to eliminate the dogging, however, since the meshes
are worn by the abrasive, the abrasive recovery filter 167 needs to
be replaced with a new filter.
[0010] However, in the abrasive recovery apparatus 160, there has
been a difficulty that since the abrasive recovery filter 167 is
disposed in a firmly sealed housing, it is extremely difficult for
an operator to replace the abrasive recovery filter 167.
[0011] Moreover, in the abrasive recovery apparatus 160, an
abrasive having an extremely small grain size is washed away by a
water stream without passing through the abrasive recovery filter
167 because of its light weight, and an abrasive having an
extremely large grain size is also washed away by the water stream
and discharged because it can not pass through the abrasive
recovery filter 167. However, as a result of verification of the
inventors of the application, it was found that abrasive (for
example, in a size of 25 to 100 .mu.m) to be essentially recovered
by the abrasive recovery apparatus 160 was mixed in the abrasive to
be discharged. It is considered to be one reason for this that
since a minimum of the grain size is controlled by flow velocity of
the water stream, the minimum is extremely unstable. There has been
a further difficulty that the amount of the abrasive that is
discharged in this way despite being reusable is estimated to reach
about 8% of the total amount of reusable abrasive, thereby
productivity is significantly reduced.
[0012] Furthermore, since the grinding force of the abrasive jet is
determined by the grain size of the abrasive, the abrasive is
desirably made to have uniform grain size to the utmost in order to
realize stable quality. However, if the quality is intended to be
realized in the abrasive recovery apparatus 160, it is necessary
that the flow velocity of the abrasive mixture liquid flowing on
the abrasive recovery filter 167 is increased, and the meshes of
the abrasive recovery filter are reduced, consequently a ratio of
the reusable abrasive that can not be recovered is further
increased, therefore it is extremely difficult to make the grain
size of the abrasive uniform.
SUMMARY OF THE INVENTION
[0013] It is an object to provide a new and improved abrasive water
jet cutting machine, in which an abrasive recovery unit can be
continuously used without needing maintenance, and an abrasive
having uniform grain size can be easily recovered.
[0014] To overcome the difficulties, an abrasive water jet cutting
machine according to the present invention including an
abrasive-mixture-liquid retention tank for retaining an abrasive
mixture liquid in which an abrasive and a liquid are mixed, a
high-pressure liquid supply unit for feeding out the abrasive
mixture liquid retained in the abrasive-mixture-liquid retention
tank at high pressure by supplying a high-pressure liquid to the
abrasive-mixture-liquid retention tank, a jet nozzle for jetting
the high-pressure abrasive mixture liquid, which is fed out from
the abrasive-mixture-liquid retention tank, to workpiece, a catch
tank for receiving the high-pressure abrasive mixture liquid jetted
from the jet nozzle, and an abrasive recovery unit that recovers
abrasive having grain size in a reusable predetermined range from
the abrasive mixture liquid transported from the catch tank, and
transports abrasive mixture liquid including recovered abrasive
into the abrasive-mixture-liquid retention tank, thereby cutting
the workpiece by the high-pressure abrasive mixture liquid jetted
from the jet nozzle; wherein the abrasive recovery unit has an
abrasive sorting tank that flows the abrasive mixture liquid
transported from the catch tank in an approximately horizontal
direction, and sorts abrasive depending on grain size of the
abrasive by using difference in sedimentation rate caused by grain
size of the abrasive, and recover the reusable abrasive having the
grain size in the predetermined range; the abrasive sorting tank
has a flow inlet provided on an upper portion at one end side, a
flow outlet provided on an upper portion at the other end side, a
first sorting member as a partition member that is set at a side of
the flow inlet in a bottom and divides the bottom, a second sorting
member as a partition member that is set at a side of the flow
outlet in the bottom and divides the bottom, and a first discharge
port set between the first and second sorting members; and when the
abrasive mixture liquid transported from the catch tank flows in
the approximately horizontal direction from the flow inlet to the
flow outlet, the abrasive sorting tank sediments abrasive having a
grain size larger than a maximum of the reusable predetermined
range included in the relevant abrasive mixture liquid in a side
near the flow inlet side compared with the first sorting member,
sediments abrasive having a grain size in the reusable
predetermined range between the first and second sorting members,
and sediments abrasive having a grain size smaller than a minimum
of the reusable predetermined range in a side near the flow outlet
side compared with the second sorting member, and discharges the
abrasive having the grain size in the reusable predetermined range
from the first discharge port and recover it.
[0015] According to such an abrasive sorting tank, the abrasive
having the grain size in the reusable predetermined range can be
sorted and recovered without using the abrasive recovery filter.
Therefore, the abrasive recovery unit can be continuously used over
a long period without needing maintenance of the abrasive recovery
unit. Moreover, according to the abrasive sorting tank, since the
abrasive is accurately sorted and thus uniform abrasive is easily
obtained compared with a case of using the abrasive recovery
filter, cutting quality of workpiece can be improved.
[0016] Height of each of the first and second sorting members may
be changed. Thus, height of the first sorting member is changed,
thereby maximal grain size of the abrasive to be recovered for
reuse can be changed, and height of the second sorting member is
changed, thereby minimal grain size of the abrasive to be recovered
for reuse can be changed.
[0017] The abrasive sorting tank may further have a second
discharge port set at a side near the flow inlet compared with the
first sorting member in the bottom, and a third discharge port set
at a side near the flow outlet compared with the second sorting
member in the bottom, in order to discharge the abrasive having the
grain size larger than the maximum of the reusable predetermined
range from the second discharge port, and discharge the abrasive
having the grain size smaller than the minimum of the reusable
predetermined range from the third discharge port. Thus, the
abrasive having a large grain size in a level of dogging a drain
ditch can be sorted and recovered to be disposed or used for other
applications.
[0018] As described hereinbefore, according to the present
invention, since the abrasive recovery filter is not used, the
abrasive recovery unit can be continuously used over a long period
without needing maintenance of the abrasive recovery unit.
Moreover, since the uniform abrasive is easily obtained compared
with the case of using the abrasive recovery filter, cutting
quality of workpiece can be improved.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 is a schematic view showing a general configuration
of a water jet cutting machine according to a first embodiment of
the invention;
[0020] FIG. 2A is a perspective view showing an outside
configuration of an abrasive sorting tank according to the
embodiment;
[0021] FIG. 2B is a perspective view showing an internal
configuration of the abrasive sorting tank according to the
embodiment;
[0022] FIG. 3 is a vertical section view showing an internal
configuration of the abrasive sorting tank according to the
embodiment; and
[0023] FIG. 4 is an explanatory view showing a general
configuration of a water jet cutting machine in the related
art.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0024] Hereinafter, a preferred embodiment of the invention will be
described in detail with reference to accompanying drawings. In
this specification and the drawings, components having
substantially the same functions and configurations are marked with
the same signs, so that overlapped description is omitted.
First Embodiment
[0025] Hereinafter, an abrasive water jet cutting machine according
to a first embodiment of the invention is described. While the
abrasive water jet cutting machine according to the embodiment is
configured as, for example, a water jet cutting machine for cutting
workpiece by a jet stream of high-pressure water mixed with the
abrasive (abrasive jet) as described below, the invention is not
limited to such an example.
[0026] First, a general configuration of a water jet cutting
machine 1 according to the embodiment is described according to
FIG. 1. FIG. 1 is an explanatory view showing a general
configuration of the water jet cutting machine 1 according to the
embodiment.
[0027] As shown in FIG. 1, the water jet cutting machine 1
according to the embodiment is a cutting machine that can perform
an accurate cutting process (that is, water jet process) to
workpiece 5 at a comparatively free cutting line by jetting
high-pressure water including abrasive. While the workpiece 5 as a
cutting object of the water jet cutting machine 1 includes various
semiconductor substrates such as a silicon wafer and a packaged
semiconductor substrate (for example, CSP substrate), it is not
limited to such examples.
[0028] For example, such a water jet cutting machine 1 mainly has a
high-pressure supply unit 10 including a high-pressure pump 15, an
abrasive mixing unit 20 including abrasive-mixture-liquid retention
tanks 22a, 22b, a jet nozzle 30 for jetting a water jet J, a
holding table 40 for holding the workpiece 5, a table transfer unit
(not shown) for transferring the holding table, a catch tank 50 for
receiving the water jet J, and an abrasive recovery unit 60 having
a sorting tank 70 and a recovered abrasive retention tank 80.
Hereinafter, respective components configuring such a water jet
cutting machine 1 are described in detail.
[0029] The high-pressure pump 15 configuring the high-pressure
supply unit 10 pressurizes water supplied from the outside, thereby
generates high-pressure water of, for example, 600 to 700 bars (1
bar is about 1.02 kgf/cm.sup.2) to be supplied. The water supplied
from the outside is, for example, tap water, however, it is not
limited to such an example, and may be pure water and the like. The
high-pressure water produced by the high-pressure pump 15 is
supplied to the abrasive-mixture-liquid retention tanks 22a, 22b of
the abrasive mixing unit 20 via a pipeline 12 for supplying the
high-pressure liquid.
[0030] The abrasive mixing unit 20 includes the two
abrasive-mixture-liquid retention tanks 22a, 22b (hereinafter, they
may be collectively called "abrasive-mixture-liquid retention tank
22") for retaining the abrasive mixture liquid in which abrasive
(abrasive grains) and water are mixed, the confluence 23, and a
plurality of pipe lines and valves for connecting them. The
abrasive includes a material having high hardness such as gamet,
alumina, silicon carbide, and diamond, which is in a granular body
having a grain size of, for example, about several ten to several
hundred micrometers, and functions to improve cutting efficiency of
the high-pressure water. In the embodiment, alumina having a grain
size of, for example, 40 to 100 .mu.m is used as the abrasive.
[0031] Such an abrasive mixing unit 20 pushes out abrasive mixture
water retained in one abrasive-mixture-liquid retention tank 22a at
high pressure by pressure of the high-pressure water supplied from
the high-pressure pump 15, and sent out the high-pressure abrasive
mixture water to the jet nozzle 30 via a pipe line 21. At that
time, the other abrasive-mixture-liquid retention tank 22b is
replenished with abrasive recovered by the abrasive recovery unit
60 via a pipeline 61 and retains the relevant abrasive, and sent
out unnecessary water to the abrasive recovery unit 60 via a
pipeline 63.
[0032] When the retaining amount of abrasive in the one
abrasive-mixture-liquid retention tank 22a being used for the
cutting process is decreased to a predetermined level or less,
operation of the abrasive-mixture-liquid retention tank 22a is
changed with that of the abrasive-mixture-liquid retention tank
22b, so that in the same way as above, the abrasive mixture water
is supplied to the jet nozzle 30, and concurrently with this, the
abrasive is replenished from the abrasive recovery unit 60. Thus,
the high-pressure abrasive mixture water can be supplied to the jet
nozzle 30 stably and continuously. It is also acceptable that at
least three abrasive-mixture-liquid retention tanks 22 are provided
and used while being switched from one another.
[0033] The jet nozzle 30 jets the high-pressure abrasive mixture
water supplied from the abrasive mixing unit 20 to the workpiece 5
held by the holding table 40 from above as the water jet J. Thus,
the workpiece 5 can be cut by energy of the high-pressure water. At
that time, since the abrasive collides with the workpiece 5 with
the high-pressure water so that the workpiece is cut with being
partially broken, cutting efficiency can be improved. In this way,
the water jet J according to the embodiment is configured as an
abrasive jet.
[0034] The table transfer unit (not shown) transfers the holding
table 40 as a workpiece holding unit in a horizontal direction (X
and Y axis directions) and a vertical direction (Z axis direction).
Thus, the holding table 40 is transferred in the X and Y axis
directions relatively to the relevant jet nozzle 30 while jetting
the water jet J from the jet nozzle 30, thereby the water jet J
including the abrasive is allowed to work along an expected cutting
line of the workpiece 5, consequently the workpiece 5 can be
continuously subjected to the cutting process.
[0035] The catch tank 50 is, for example, a vertical-long water
storage tank having an opened top, and acts as a receiver tank of
the water jet J. That is, the catch tank 50 can receive the water
jet J, which has penetrated through the workpiece 5 after cutting
it in the above way, with power of the water jet J being reduced by
retained water as a buffer. On a bottom of the catch tank 50, the
abrasive included in the water jet J received in the above way is
sedimented and deposited. The abrasive mixture water including the
abrasive deposited on the bottom of the catch tank 50 is
transported to the abrasive recovery unit 60 by a first
positive-pressure pump 59 via a pipeline 51.
[0036] The abrasive recovery unit 60 is abrasive recovery apparatus
in a sedimentation type unlike the abrasive recovery apparatus 160
in an abrasive recovery filter type in the related art. The
abrasive recovery unit 60 has the abrasive sorting tank 70 and the
recovered abrasive retention tank 80.
[0037] The abrasive sorting tank 70 sorts and recovers abrasive
having a grain size in a reusable predetermined range, that is, a
grain size of a predetermined minimum (for example, 25 .mu.m) or
more and a grain size of a predetermined maximum (for example, 100
.mu.m) or less from the abrasive mixture liquid transported from
the catch tank 50, and transports the abrasive mixture water
including the recovered abrasive to the recovered abrasive
retention tank 80 via a pipeline 66. Moreover, the abrasive sorting
tank 70 sorts and recovers abrasive having a grain size larger than
the maximum, and sends out it to an abrasive recovery filter 101
via a pipe line 64. Furthermore, the abrasive sorting tank 70 sorts
and recovers abrasive having a grain size smaller than the minimum,
and sends out it to an abrasive recovery filter 102 via a pipe line
65. Abrasive mixture water including abrasive that has not been
recovered by the abrasive sorting tank 70 is discharged to the
outside by a third positive-pressure pump 79 via a pipeline 62.
Such an abrasive sorting tank 70 is a unique configuration
according to the embodiment, and described later in detail.
[0038] The recovered abrasive retention tank 80 retains the
abrasive mixture water including the reusable abrasive recovered by
the abrasive sorting tank 70. The abrasive mixture water including
abrasive deposited on a bottom of the abrasive retention container
80 is transported to the abrasive mixture liquid retention tank
that is not being used for the cutting process in the two abrasive
mixture liquid retention tanks 22a, 22b by the second
positive-pressure pump 69 via the pipeline 61.
[0039] The water jet cutting machine 1 in a configuration as above
sends out the abrasive mixture water in the abrasive mixture liquid
retention tank 22a or 22b at high pressure by the high-pressure
water supplied from the high-pressure pump 15, and jets the
high-pressure abrasive mixture water (abrasive jet) from the jet
nozzle 30 to the workpiece 5 for the cutting process. Furthermore,
the machine is in a configuration where the catch tank 50 receives
the abrasive mixture water jetted from the jet nozzle 30, and then
the abrasive recovery unit 60 recovers the abrasive, which is not
wasted and has a reusable grain size (for example, 25 to 100
.mu.m), from the relevant abrasive mixture water, and returns the
abrasive to the tank that is not being used for the cutting process
in the two abrasive mixture liquid retention tanks 22a, 22b.
According to such a configuration, the abrasive can be
automatically circulated within the water jet cutting machine 1 and
efficiently reused.
[0040] Next, the abrasive sorting tank 70 as a feature according to
the embodiment is described in detail according to FIGS. 2A to 2B
and FIG. 3. FIG. 2A is a perspective view showing an outside
configuration of the abrasive sorting tank 70 according to the
embodiment, FIG. 2B is a perspective view showing an internal
configuration of the abrasive sorting tank 70 according to the
embodiment, and FIG. 3 is a vertical section view showing an
internal configuration of the abrasive sorting tank 70 according to
the embodiment.
[0041] As shown in FIGS. 2A to 2B and FIG. 3, the abrasive sorting
tank 70 functions to flow the abrasive mixture water transported
from the catch tank 50 in an approximately horizontal direction
near a liquid level W, and sort the abrasive in the relevant
abrasive mixture water by using difference in sedimentation rate of
the abrasive depending on grain size, and recover the abrasive
having the grain size in the reusable predetermined range.
[0042] The abrasive sorting tank 70 has a housing 71 in an
approximately rectangular prism shape for retaining the abrasive
mixture water, a buffer tank 72 being set in an upper portion in
one side of the housing 71 and connected with the pipe line 51 from
the catch tank 50, a flow inlet 91 provided in a lower outlet of
the buffer tank 72, a flow outlet 92 set in an upper portion in the
other side of the housing 71, a first sorting member 73 set at a
flow inlet 91 side in a bottom of the housing 71, a second sorting
member 74 set at a flow outlet 92 side in the bottom of the housing
71, a liquid-level measuring sensor 75 for measuring height of the
liquid level W of the abrasive mixture water retained in the
housing 71, a connection member 76 for connecting between the
bottom of the housing 71 and the pipeline 66, a first discharge
port 94 set between the first sorting member 73 and the second
sorting member 74 in the bottom of the housing 71, a second
discharge port 93 set at a side near the flow inlet port 91
compared with the first sorting member 73 in the bottom of the
housing 71, and a third discharge port 95 set at a side near the
flow outlet port 92 compared with the second sorting member in the
bottom of the housing 71.
[0043] As shown in the figures, the abrasive sorting tank 70 is a
water tank that can retain the abrasive mixture water within the
housing 71 in the approximately rectangular prism shape. In the
upper portion of the housing 71, the flow inlet port 91 and the
flow outlet port 92 for the relevant abrasive mixture water are set
in places where the abrasive mixture water transported from the
catch tank 50 is flown in a horizontal direction within the housing
71. The flow inlet port 91 and the flow outlet port 92 are set at
approximately the same height in the housing 71, and positioned in
a side lower than the retained liquid level W at the maximum.
[0044] On the upper portion of the housing 71 at a side where the
flow inlet 91 is positioned, the buffer tank 72 is provided, which
temporarily retains the abrasive mixture water transported from the
catch tank 50. Since a fixed amount of abrasive mixture water is
not always transported from the catch tank 50 to the abrasive
sorting tank 70, the buffer tank 72 temporarily retains the
abrasive mixture water such that a fixed amount of abrasive mixture
water is always flown from the flow inlet 91 positioned in the
lower portion of the buffer tank 72 into the housing 71.
[0045] Furthermore, in the lower outlet of the buffer tank 72, a
regulation member 721 is set, the member being formed by a sheet
member having an L-shaped section. At one side of the regulation
member 721, the flow inlet 91 is formed in a manner of opening in a
lateral direction. Such a regulation member 721 regulates the
abrasive mixture water discharged from the bottom of the buffer
tank 72 such that it does not flow out in a vertically downward
direction, and guides the water to flow out in a horizontal
direction from the flow inlet 91. Thus, a horizontal stream of the
abrasive mixture water can be preferably generated in the upper
portion within the housing 71.
[0046] Moreover, the liquid-level measuring sensor 75 is provided
in the upper portion of the housing 71, which is for measuring the
height of the liquid level W of the abrasive mixture water retained
in the abrasive sorting tank 70. The liquid-level measuring sensor
75 is configured by, for example, a small capacitance-type liquid
level sensor, and measures the height of the liquid level W
according to difference in capacitor (capacitance) between an
electrode and an inner wall of a container. According to a
measurement result by such a liquid-level measuring sensor 75, a
flow rate of the abrasive mixture water outputting/inputting
from/into the abrasive sorting tank 70 is controlled, thereby the
height of the liquid level W is adjusted. Specifically, the height
of the liquid level W is adjusted such that the liquid level W is
higher than each position of the flow inlet 91 and the flow outlet
92, and it does not reach the ceiling of the housing 71.
[0047] According to the above configuration, the abrasive mixture
water transported from the catch tank 50 to the abrasive sorting
tank 70 via the pipe line 51 can be temporarily retained in the
buffer tank 72, then flown from the flow inlet 91 into the housing
71, and flown in the horizontal direction in the upper portion
within the housing 71, and in turn discharged to the outside from
the flow outlet 92 via the pipe line 62.
[0048] Next, in the abrasive sorting tank 70, a configuration for
sorting abrasive depending on grain size is described, the abrasive
being included in the abrasive mixture water flowing in the
horizontal direction.
[0049] On the bottom of the housing 71, the first sorting member 73
is disposed at a side near the flow inlet port 91, and the second
sorting member 74 is disposed at a side near the flow outlet port
92. Each of the first and second sorting members 73 and 74 is
configured by, for example, a triangular prism unit, and disposed
in a manner of dividing the bottom of the housing 71 in a
perpendicular direction to the direction of the horizontal
flow.
[0050] The first sorting member 73 is configured by, for example, a
comparatively large triangular-prism-unit, and disposed with an
inclined surface 73a being at a side of the flow outlet 92 and a
vertical surface 73b being at a side of the flow inlet 91. The
first sorting member 73 acts as a partition member for sorting size
of the maximal grain size (for example, 100 .mu.m) of reusable
abrasive. Height h1 of such a first sorting member 73 is changed,
thereby the size of the maximal grain size of the abrasive to be
recovered for reuse can be changed. In this case, several kinds of
triangular-prism-units having different height h1 may be prepared
as the first sorting member 73 such that the relevant
triangular-prism-unit is selectively disposed depending on set
maximal grain size, or the first sorting member 73 may be
configured such that the height h1 of the member itself can be
changed depending on the set maximal grain size.
[0051] The second sorting member 74 is configured by a small
triangular-prism-unit compared with the first sorting member 73,
and disposed with an inclined surface 74a being at a side of the
flow inlet 91 and a vertical surface 74b being at a side of the
flow outlet 92. The second sorting member 74 acts as a partition
member for sorting size of the minimal grain size (for example, 25
.mu.m) of the reusable abrasive. Height h2 of such a second sorting
member 74 is changed, thereby the size of the minimal grain size of
the abrasive to be recovered for reuse can be changed, as the first
sorting member 73.
[0052] The first and second sorting members 73 and 74 as above are
disposed, thereby the bottom of the housing 71 is divided into
three bottom areas along the direction of the horizontal flow. In
the three bottom areas, a bottom area (left area in FIG. 3) at a
side near the flow inlet 91 compared with the first sorting member
73 is an area where abrasive having a grain size larger than the
maximal grain size of the reusable abrasive (for example, larger
than 100 .mu.m) is sedimented and deposited. A bottom area between
the first and the second sorting members 73 and 74 (central area in
FIG. 3) is an area where abrasive having a grain size in the
reusable predetermined range (for example, 25 .mu.m to 100 .mu.m)
is sedimented and deposited. A bottom area (right area in FIG. 3)
at a side near the flow outlet 92 compared with the second sorting
member 74 is an area where abrasive having a grain size smaller
than the minimal grain size of the reusable abrasive (for example,
smaller than 25 .mu.m) is sedimented and deposited.
[0053] According to a configuration as above, by using difference
in sedimentation rate of abrasive depending on grain size, abrasive
included in the abrasive mixture water horizontally flowing in the
housing 71 is sorted, so that the abrasive having the grain size in
the reusable predetermined range can be recovered.
[0054] Specifically, the inputted abrasive mixture water from the
flow inlet 91 is horizontally flown in the upper portion within the
housing 71, and then discharged to the outside from the flow outlet
92. At that time, abrasive having a fine grain size (for example,
10 .mu.m or less) is discharged to the outside from the flow outlet
92 with the horizontal flow without sedimenting in the abrasive
sorting tank 70 (refer to an arrow A in FIG. 3). Such abrasive
having the fine grain size does not dog the discharge ditch even if
it is discharged as it is.
[0055] Since the abrasive having the grain size larger than the
maximal grain size of the reusable abrasive, which is included in
the horizontally flowing abrasive mixture liquid, has large
sedimentation rate, it sediments in the bottom area at the side
near the flow inlet 91 compared with the first sorting member 73
(refer to an arrow B in FIG. 3). Since the abrasive having the
grain size in the reusable predetermined range has medium
segmentation rate, it sediments in the bottom area between the
first and second sorting members 73 and 74 (refer to an arrow C in
FIG. 3). Furthermore, the abrasive having the grain size smaller
than the minimal grain size of the reusable abrasive has small
segmentation rate, it sediments in the bottom area at the side near
the flow outlet 92 compared with the second sorting member 74
(refer to an arrow D in FIG. 3).
[0056] In this way, the abrasive sorting tank 70 sorts the abrasive
by using difference in sedimentation rate of abrasive depending on
grain size, so that the abrasive can be deposited in each of the
three bottom areas divided by the first and second sorting members
73 and 74. Thus, for example, when the minimal grain size of the
reusable abrasive is set to be 25 .mu.m, and the maximal grain size
is set to be 100 .mu.m, abrasive having a grain size larger than
100 .mu.m can be excluded from a recovery object by the first
sorting member 73, and abrasive having a grain size smaller than 25
.mu.m can be excluded from the recovery object by the second
sorting member 74.
[0057] That is, in the bottom area between the first and second
sorting members 73 and 74, the abrasive having the reusable
predetermined grain size (for example, 25 .mu.m to 100 .mu.m) is
sedimented and deposited. Such abrasive having the reusable grain
size is sent out from the first discharge port 94 provided in the
relevant bottom area to the recovered abrasive retention tank 80
via the pipeline 66 and retained therein (refer to FIG. 1). The
abrasive retained in the recovered abrasive retention tank 80 is
timely transported to the abrasive-mixture-liquid supply tank 22
for reuse.
[0058] In the bottom area at the side near the flow inlet 93
compared with the first sorting member 73, not only the abrasive
having the grain size larger than the maximal grain size (for
example, 100 .mu.m) of the reusable abrasive, but also many cutting
wastes produced in cutting of the workpiece 5 are sedimented and
deposited. Since the cutting wastes often have a grain size larger
than the grain size of the reusable abrasive, they are sorted by
the first sorting member 73, and deposited on the relevant bottom
area. Such abrasive or cutting wastes having the grain size larger
than the maximal grain size are discharged from the second
discharge port 93 provided in a side face of the housing 71
positioned in the relevant bottom area, and transported to the
abrasive recovery filter 101 (refer to FIG. 1) via the pipe line
64. Since such abrasive or cutting wastes having the grain size
larger than the maximal grain size may cause clogging of the
discharge ditch or the like, they can not be drained as it is,
therefore they are recovered by the abrasive recovery filter 101
and then disposed.
[0059] On the bottom area at the side near the flow outlet 92
compared with the second sorting member 74, abrasive having a grain
size smaller than the minimal grain size of the reusable abrasive
(for example, smaller than 25 .mu.m) is sedimented and deposited,
which further has a grain size causing dogging of the discharge
ditch (for example, 10 .mu.m to 25 .mu.m) if the abrasive is
discharged as it is. The abrasive is discharged from the third
discharge port 95 provided in a side face of the housing 71
positioned in the relevant bottom area, and transported to the
abrasive recovery filter 102 (refer to FIG. 1) via the pipe line
65. Since such abrasive having the grain size of 10 .mu.m to 25
.mu.m may cause dogging of the discharge ditch or the like, it
cannot be drained as it is, therefore it is recovered by the
abrasive recovery filter 102 and then disposed. While the abrasive
discharged from the second discharge port 93 has not any
possibility of being reused, since the abrasive discharged from the
third discharge port 95 has a possibility of being reused in some
other application, desirably, it is recovered separately from the
abrasive discharged from the second discharge port 93.
[0060] Hereinbefore, detailed description has been made on the
water jet cutting machine 1 according to the embodiment,
particularly on the abrasive sorting tank 70 of the abrasive
recovery unit 60. In the abrasive recovery unit 60 according to the
embodiment, the abrasive mixture water is horizontally flown, and
the reusable abrasive is sorted and recovered by using difference
in sedimentation rate of abrasive depending on grain size without
using the abrasive recovery filter 167 (refer to FIG. 4) like the
abrasive recovery unit 160. Therefore, essentially, the abrasive
recovery unit 60 can be continuously used for a long time without
needing maintenance of the unit, consequently convenience of an
operator can be improved.
[0061] Moreover, in such a sorting/recovery method by using
difference in sedimentation rate of abrasive, compared with the
case of using the abrasive recovery filter 167, abrasive is
accurately sorted for each grain size, consequently uniform
abrasive is easily obtained. Therefore, the relevant uniform
abrasive is circularly used within the water jet cutting machine 1,
thereby cutting quality of the workpiece 5 can be improved.
[0062] Hereinbefore, while the preferred embodiment and examples of
the invention have been described with reference to accompanied
drawings, the invention is not limited to such embodiment and
examples. It will be appreciated that various alterations or
modifications can be conceived by those skilled in the art within a
category of technical ideas according to claims, and it is
obviously understood that they also belong to a technical scope of
the invention.
[0063] The workpiece 5 may include various semiconductor wafers, or
semiconductor substrates such as a packaged substrate such as a CSP
substrate, GPS substrate, or BGA substrate. Alternatively, the
workpiece may include a sapphire substrate, a glass material, a
ceramic material, a metal material, a synthetic resin material such
as plastic, or an electronic material substrate for forming a
magnetic head, laser diode head or the like. A shape of the
workpiece 5 may be any optional shape such as an approximately
rectangular shape or an approximately disk shape.
[0064] While an example of using the water jet cutting machine 1 as
the abrasive water jet cutting machine was described in the
embodiment, the invention is not limited to such an example. The
abrasive water jet cutting machine can be variously altered in
design if the machine has a high-pressure liquid jetting unit for
jetting a high-pressure liquid, and can perform the cutting process
of workpiece by jetting the high-pressure liquid. For example, the
liquid to be jetted and retained is not limited to the example of
water, and may be any other liquid such as alcohol or oil, or may
be any of liquids in which various chemical substances are
dissolved in various solvents.
INDUSTRIAL APPLICABILITY
[0065] The embodiment of the invention can be used for an abrasive
water jet cutting machine for cutting workpiece by jetting a
high-pressure liquid mixed with abrasive.
* * * * *