U.S. patent application number 11/879440 was filed with the patent office on 2007-11-15 for method and apparatus for fluid polishing.
This patent application is currently assigned to DENSO Corporation. Invention is credited to Shigeya Kato, Yasuhito Ooka.
Application Number | 20070264910 11/879440 |
Document ID | / |
Family ID | 37763303 |
Filed Date | 2007-11-15 |
United States Patent
Application |
20070264910 |
Kind Code |
A1 |
Ooka; Yasuhito ; et
al. |
November 15, 2007 |
Method and apparatus for fluid polishing
Abstract
In a fluid polishing method for processing a fine aperture by
slurry 7, the slurry is supplied from a cylinder 2a in a slurry
flow rate target process until the flow rate increases to a target
value of a slurry feed flow rate. When the flow rate reaches the
target flow rate, the cylinder is stopped and switched to another
cylinder 2b and the operation fluid flow rate of the fine aperture
is thereafter measured. In a metering process, to be executed next,
a necessary processing time is calculated on the basis of the
operation fluid flow rate and polishing is carried out for a
necessary processing time by another cylinder 2b. Another cylinder
is then stopped and switched and the operation fluid flow rate is
measured. In this way, the metering process is repeated until the
operation fluid flow rate reaches a predetermined value. In each
process, the supply of the slurry is not interrupted.
Inventors: |
Ooka; Yasuhito; (Anjo-city,
JP) ; Kato; Shigeya; (Kariya-city, JP) |
Correspondence
Address: |
HARNESS, DICKEY & PIERCE, P.L.C.
P.O. BOX 828
BLOOMFIELD HILLS
MI
48303
US
|
Assignee: |
DENSO Corporation
Kariya-city
JP
|
Family ID: |
37763303 |
Appl. No.: |
11/879440 |
Filed: |
July 17, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11509749 |
Aug 24, 2006 |
|
|
|
11879440 |
Jul 17, 2007 |
|
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Current U.S.
Class: |
451/36 |
Current CPC
Class: |
B24B 1/00 20130101; B24B
31/116 20130101 |
Class at
Publication: |
451/036 |
International
Class: |
B24C 1/08 20060101
B24C001/08 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 30, 2005 |
JP |
2005-249256 |
Sep 20, 2005 |
JP |
2005-272176 |
Sep 21, 2005 |
JP |
2005-273647 |
Claims
1. A fluid polishing method for polishing and processing a fine
aperture in a work by supplying a slurry as a polishing fluid to
said work, comprising at least one process, wherein said at least
one process includes the steps of: measuring an operation fluid
flow rate (Q1) before processing; causing said slurry to flow to
said work for a predetermined processing time (T); and measuring an
operation fluid flow rate (Q2) after processing; and wherein: a
processing capacity coefficient (K) is determined on the basis of
past data about a ratio (dQ/T) of an increment amount (dQ=Q2-Q1) of
the operation fluid flow rates before and after processing to said
processing time (T); and when said processing capacity coefficient
(K) becomes less than a predetermined threshold value (a), a
measure for improving the fluid polishing processing performance is
taken.
2. A fluid polishing method according to claim 1, wherein said
operation fluid is any of a slurry, an oil and air.
3. A fluid polishing method according to claim 1, wherein said
measure for improving said fluid polishing processing performance
is a method that elevates a feed pressure of said slurry from said
feeding apparatus.
4. A fluid polishing method according to claim 1, wherein said
measure for improving said fluid polishing processing performance
is the addition of new slurry.
5. A fluid polishing method according to claim 1, wherein said
processing capacity coefficient (K) is determined as a moving
average (.SIGMA.Kj/N) of a plurality of works, and a processing
capacity coefficient (Kj) of each work is an average (.SIGMA.Ki/M)
of a processing capacity coefficient (Ki) of each process of said
work.
6. A fluid polishing method according to claim 1, wherein said
processing capacity coefficient (K) is determined as a moving
average (.SIGMA.Kj/N) of a plurality of works, and a processing
capacity coefficient (Kj) of each work is calculated by a
mathematical extrapolation method using an operation fluid flow
rate of each step of said work and three or more operation fluid
flow rates formed by processing time corresponding to said
operation fluid flow rate.
7. A fluid polishing method according to claim 6, wherein said
mathematical extrapolation method is the method of least
squares.
8. A fluid polishing method according to claim 1, wherein the feed
pressure of said slurry from said feeding apparatus is kept
constant during processing of one work.
9. A fluid polishing method according to claim 1, wherein said work
is a fine aperture of a fuel injector for a diesel engine.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of U.S. patent application
Ser. No. 11/509,749 filed on Aug. 24, 2006. This application claims
the benefit of JP 2005-249256, filed Aug. 30, 2007, JP 2005-272176,
filed Sep. 20, 2005, and JP 2005-273647 filed Sep. 21, 2005. The
disclosures of the above applications are incorporated herein by
reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This invention relates to a fluid polishing method and a
fluid polishing apparatus for executing the fluid polishing method.
More particularly, the present invention relates to a method, and
an apparatus for the method, for highly precisely processing a fine
aperture by using a slurry of a polishing material.
[0004] 2. Description of the Related Art
[0005] A large number of apparatuses exist that have a high
precision fine aperture such as a nozzle tip of a fuel injector, a
jet port of a carburetor, an orifice for regulating a fluid flow
rate, a jet nozzle of a printer, and so forth. Methods for
processing such a fine aperture include methods which employ laser,
electron beam and discharge processing. There is the case where
fluid polishing is employed when sufficient precision cannot be
achieved by such methods. An example of the use of the fluid
polishing method is a processing of a fine aperture of an orifice
of a fuel injector for a diesel engine common rail. A common rail
construction has recently been employed for diesel engines, and the
diesel engines have been mounted to a variety of automobiles
ranging from compact cars having an output of about 80 kW to
large-scale trucks. However, fuel efficiency drops, and this
adversely affects the economy, if any flow rate error occurs in the
fuel injector. At the same time, pollutants of the environment
increase undesirably in the exhaust gas and this is not
desirable.
[0006] The flow rate error of the diesel engine common rail
injector is greatly affected by the accuracy of the static oil flow
rate of the orifice, as one of its constituent components, and a
metering processing has been carried out by fluid polishing. Fluid
polishing is carried out by causing a slurry (mixture of abrasives
and an oil), discharged from a cylinder by the movement of a
piston, to flow through the orifice to enlarge the diameter and to
form an inlet R. However, there are cases where the oil flow rate
greatly exceeds a target flow rate to thereby invite a defect, or
is greatly smaller than the target flow rate and requires the
repetition of fine adjustment.
[0007] The prior art technology has proposed a polishing method of
a fine aperture of a nozzle of a diesel fuel injector (for example,
Japanese Translation of PCT application 11-510437). A fluid
polishing apparatus used for such a fluid polishing method includes
a slurry tank and a cylinder for feeding the slurry.
[0008] The possibility of the occurrence of switching the
cylinders, during the processing, exists in the fluid polishing
method according to the prior art. In the fluid polishing
apparatus, a piston of each cylinder moves back to suck the slurry
from the tank after the slurry is used up. Because the suction time
exists, the equipment has two cylinders so that as soon as the
slurry of one of the cylinders is used up, the other cylinder is
used. Nonetheless, the processing pressure cannot be kept constant
at the instant of switching and a pressure fluctuation develops. If
the pressure rises instantaneously, the flow rate apparently rises
with reference to the relation Q=A P (A: constant, P: pressure) and
reaches a target flow rate. Consequently, suitable processing is
not carried out and the actual oil flow rate becomes smaller (see
FIGS. 3 and 4). When the timing of switching of the cylinders
occurs at the time that the flow rate is in the proximity of the
target slurry flow rate (smaller by about 1 to 2 cc/min), the oil
flow rate becomes large, on the contrary. As the processing
capacity of fluid polishing is proportional to the pressure, the
processing is promoted as the pressure becomes higher at the
instant of switching and the processing that should originally be
finished after a little time is excessively executed. As a result,
the oil flow rate becomes larger (see FIG. 4). To solve this
problem, it may be conceivable to drastically increase the cylinder
capacity and to reduce the frequency of switching. When the
cylinder capacity is increased, however, the slurry may be
separated and the abrasives may precipitate inside the cylinder, so
that variance occurs in the processing capacity and the
precipitated abrasives are solidified and clog the cylinders.
SUMMARY OF THE INVENTION
[0009] In view of the problems described above, it is an object of
the present invention to provide a fluid polishing method, and an
apparatus for the method, capable of avoiding switching of
cylinders during the fluid polishing and of improving the
processing accuracy of a fine aperture by preventing the separation
of the slurry and the precipitation of the abrasives.
[0010] The flow rate error of a diesel engine common rail injector
is greatly affected by the static oil flow rate accuracy of the
orifice as a constituent component of the injector and a metering
processing is made by fluid polishing. Fluid polishing is carried
out by causing a slurry (mixture of abrasives and oil) discharged
from a cylinder, by the movement of a piston, to flow through the
orifice to enlarge the diameter and to form an inlet R.
[0011] A processing capacity in this fluid polishing depends on the
condition of the slurry and a processing pressure. The pressure is
controlled to a constant level by the equipment but the slurry is
degraded in the course of use due to wear of the abrasives and
mixture of the metering oil, so that the processing capacity
coefficient drops day by day. With the drop of the processing
capacity coefficient, the processing accuracy is also deteriorated,
and the processing time gets gradually longer, thereby extending
the cycle time (CT) of one processing process (see FIG. 9).
[0012] Other prior art technologies are known that propose a fluid
polishing method (Japanese Unexamined Patent Publication (Kokai)
No. 2004-284014 and Japanese Translation of PCT Application No.
11-510437, for example) but these references do not disclose the
proposal of the present invention.
[0013] The invention is completed under the circumstances described
above and provides a fluid polishing method, and an apparatus for
the method, capable of preventing the gradual increase of the
processing time and the eventual extension of the cycle time owing
to degradation with time of a slurry resulting from wear of the
abrasives and mixture of the metering oil during fluid
polishing.
[0014] A fluid polishing method according to the prior art
generally involves the steps of causing the slurry to flow through
the orifice until the slurry flow rate reaches a predetermined
value set to be lower than a true target value, measuring the flow
rate of oil (oil flow rate) as an operation fluid passing through
the orifice at that time, deciding a further necessary processing
time on the basis of insufficiency of the oil flow rate and
conducting fluid polishing for the necessary processing time to
finish the fine aperture of the orifice.
[0015] As a result, however, processing accuracy is deteriorated
and variance in the oil flow rate becomes large. As a metering
method, a method that determines a relation between an oil flow
rate change amount and a processing time (which is called
"processing capacity coefficient") from past statistic data,
decides the processing time on the basis of this relation and
conducts the processing has been proposed (for example, Japanese
Unexamined Patent Publication (Kokai) No. 2004-284014). Because the
processing capacity coefficient varies from work to work, however,
variance occurs between the statistical value and an actual value
and the estimation accuracy of the processing time is deteriorated
with this variance, inviting a drop in processing accuracy.
[0016] According to the fluid polishing method that determines the
processing time from the processing capacity coefficient, the
processing time (T) is calculated from a difference (dQ) between a
flow rate target value and a previous oil flow rate measurement
value and a processing capacity coefficient (K) (that is, T=dQ/K).
Here, the processing capacity coefficient is statistically decided
from the past data by collecting a mean value of N times or a
maximum value among N times as shown in FIG. 20. Because variance
exists in practice from work to work, however, estimation accuracy
of the processing time (T) is deteriorated owing to the difference
between the statistic value and the actual value. Therefore, even
when the processing is executed on the basis of this T value, the
target oil flow rate cannot be reached. When the statistic value is
smaller in comparison with the actual processing capacity
coefficient, the processing time (T) is estimated to be a larger
value, so that the target flow rate is exceeded and the operation
becomes inferior. When the statistic value is larger than the
actual value, on the contrary, the processing time (T) is estimated
to be a smaller value. Though the target flow rate is not reached
in this case, the target value can be achieved by conducting
additional working. Therefore, at present, the processing capacity
coefficient is estimated to a larger value than the actual value by
adding a correction value a to the statistic value. However, when
this procedure is employed, the processing time is always estimated
as a smaller value and the target value cannot be easily reached.
Consequently, the number of times of repetition increases and the
total processing time inclusive of the measurement time also
increases.
[0017] Another prior art technology proposes a fluid polishing
method (for example, Japanese Translation of PCT Application No.
11-510437) but this reference does not disclose the proposal of the
present invention.
[0018] Under the circumstances described above, the present
invention aims at providing a fluid polishing method, and an
apparatus for the method, capable of improving the processing
accuracy of a fine aperture by improving the deterioration of a
processing time by a method that estimates the processing time on
the basis of a past statistical value of fluid polishing.
[0019] To accomplish the object described above, a first form of
the invention provides a fluid polishing method for processing a
fine aperture in a work (5) by supplying slurry (7) as a polishing
fluid to the work (5), wherein the supply of the slurry (7) from
the feeding apparatus (2a) is not stopped till a stop
procedure.
[0020] According to this construction, processing can be carried
out without stopping the slurry feeding apparatus in the fluid
polishing process for supplying the slurry to the work. Therefore,
temporary fluctuation of the slurry flow rate during processing can
be prevented and processing accuracy of the fine aperture of the
work can be improved.
[0021] In the second form of the invention, the apparatus includes
a plurality of feeding apparatuses (2a; 2b), the feeding
apparatuses (2a; 2b) are switched to other feeding apparatuses by a
switching procedure after a stop procedure is executed, and the
slurry is supplied to the work (5) by other feeding apparatuses.
Because the feeding apparatuses (2a; 2b) are switched after a stop
procedure, the feeding apparatuses (2a; 2b) are not operated in an
intermediate stage and the supply of the slurry (7) is not stopped
till the stop procedure.
[0022] According to this construction, it is possible to avoid the
insertion of a switching operation of the slurry feeding apparatus
into the fluid polishing process for supplying the slurry to the
work. Therefore, it becomes possible to prevent a temporary
fluctuation of the slurry flow rate during the processing and to
improve the processing accuracy of the fine aperture of the
work.
[0023] In the first form described above, the third form of the
invention has a feature that the feeding apparatus (2a) is of a
plunger type and has a cylinder (2a), the slurry (7) remaining
inside the cylinder (2a) is completely returned to a slurry tank
(1) while a work feeding apparatus such as a robot fits and removes
the work to and from a jig, and the slurry (7) is again sucked so
that this cylinder (2a) is filled substantially completely with the
slurry (7).
[0024] According to this form of the invention, the processing time
can be shortened by executing packing of the cylinder in parallel
with the fitting or removal of the work and, because the slurry
inside the cylinder is fully returned to the slurry tank, the
separation of the slurry and the precipitation of the abrasives
inside the cylinder can be prevented. This also contributes to the
improvement of accuracy of processing the fine aperture of the
work.
[0025] In the second form described above, the fourth form of the
invention has a feature that the feeding apparatuses (2a, 2b) are
of a plunger type and have a cylinder (2a, 2b), other feeding
apparatus at rest completely returns the slurry (7) remaining
inside the cylinders (2a, 2b) to the slurry tank (1) while the
feeding apparatus in operation supplies the slurry to the work (5),
and then again sucks the slurry (7) and substantially completely
fills the cylinder (2a, 2b) with the slurry (7).
[0026] According to this form of the invention, as two sets of
cylinders are alternately used, the processing time can be
shortened by conducting filling of the cylinder in parallel with
the processing and the slurry inside the cylinder that is switched
and is at rest in the next processing step is fully returned to the
slurry tank. As the separation of the slurry inside the cylinder
and the precipitation of the abrasives can be prevented, this also
contributes to an improvement in the processing accuracy of the
fine aperture of the work.
[0027] In the third or fourth form described above, the fifth form
of the invention has a feature that the capacity of each cylinder
(2a, 2b) is at least 100 cc.
[0028] According to this form of the invention, it is possible to
avoid the insertion of the cylinder switching operation into each
process, of fluid polishing, that supplies the slurry to the work
by using the cylinders having a sufficient capacity and to
eventually improve the processing accuracy of the fine aperture of
the work.
[0029] In any of the first to fifth forms described above, the
sixth form of the invention has its feature in that the feeding
pressure of the feeding apparatus (2a; 2b) is kept constant.
[0030] According to this form, polishing of the fine aperture can
be carried out smoothly without any problem.
[0031] In the first to sixth forms described above, the seventh
form of the invention has a feature that the work (5) is a fine
aperture in a fuel injector for a diesel engine.
[0032] To accomplish the object described above, the eighth form of
the invention provides a fluid polishing method for polishing and
processing a fine aperture in a work (5) by supplying slurry (7) as
a polishing fluid to the work (5), and this method includes at
least one process. In this at least one process, the slurry (7) is
caused to flow to the work for a predetermined processing time (T)
and operation fluid flow rates (Q1, Q2) before and after processing
are measured. In this fluid polishing method, a processing capacity
coefficient (K) is determined on the basis of past data about a
ratio (dQ/T) of an increment amount (dQ=Q2-Q1) of the operation
fluid flow rates before and after processing for the processing
time (T), and when the processing capacity coefficient (K) becomes
less than a predetermined threshold value (a), a measure for
improving the fluid polishing processing performance is taken.
[0033] According to this construction, degradation of slurry
quality is detected as a change of the processing capacity
coefficient (K). A threshold value is compared with the processing
capacity coefficient and when the processing capacity coefficient
becomes smaller than this threshold value, the fluid polishing
performance is improved to cope with degradation and to prevent an
increase in the processing cycle time (CT).
[0034] In the eighth form described above, the ninth form of the
invention has a feature that the fluid flow rate is any of a slurry
flow rate, an oil flow rate and an air flow rate.
[0035] This form discloses a form that embodies the operation
fluid.
[0036] In the eighth or ninth form described above, the tenth form
of the invention has a feature that the measure for improving the
fluid polishing processing performance is a method that elevates
the feed pressure of the slurry (7) from the feeding apparatus.
[0037] This form copes with slurry degradation by elevating the
processing pressure and prevents an increase of the processing
cycle time (CT).
[0038] In the eighth or ninth form described above, the eleventh
form of the invention has a feature that the measure for improving
the fluid polishing processing performance is the addition of new
slurry (7).
[0039] According to this form, the addition of the slurry is
carried out when the processing capacity coefficient becomes
smaller than the threshold value and in this way, an increase of
the processing cycle time (CT) can be prevented.
[0040] In any of the eighth to eleventh forms described above, the
twelfth form of the invention has a feature that the processing
capacity coefficient (K) is determined as a moving average
(.SIGMA.Kj/N) of the processing capacity coefficients of a
plurality of works, and a processing capacity coefficient (Kj) of
each work is an average (.SIGMA.Ki/M) of a processing capacity
coefficient (Ki) of each process of the work.
[0041] According to this form, a form for embodying the method for
determining the processing capacity coefficient is disclosed.
[0042] In any of the eighth to eleventh forms described above, the
thirteenth form of the invention has a feature that the processing
capacity coefficient (K) is determined as a moving average
(.SIGMA.Kj/N) of the processing capacity coefficients of a
plurality of works, and a processing capacity coefficient (Kj) of
each work is calculated by a mathematical extrapolation method
using an operation fluid flow rate of each process of the work and
three or more measurement values of the operation fluid flow rate
of each process and the processing time corresponding to each
operation fluid flow rate.
[0043] According to this form, a form for embodying the method for
determining the processing capacity coefficient is disclosed.
[0044] In the thirteenth form described above, the fourteenth form
of the invention has a feature that the mathematical extrapolation
method is the method of least squares.
[0045] According to this form, a form for embodying the method for
determining the processing capacity coefficient is disclosed.
[0046] In any of the eighth to fourteenth forms described above,
the fifteenth form of the invention has a feature that a feed
pressure of the slurry (7) from the feeding apparatus is kept
constant during the processing of one work (5).
[0047] According to this form, polishing of the fine aperture can
be carried out more smoothly and without any problem.
[0048] In any of the eighth to fifteenth forms described above, the
sixteenth form of the invention has its feature in that the work
(5) is a fine aperture of a fuel injector for a diesel engine.
[0049] To accomplish the object described above, the seventeenth
form of the invention provides a fluid polishing method for
polishing and processing a fine aperture in a work (5) by supplying
slurry (7) as a polishing fluid to the work (5) by feeding
apparatuses, including a primary processing process, a secondary
processing process and a finishing process. In the primary process,
a slurry feed flow rate is reliably limited to a low level and the
slurry feeding apparatus is stopped in a processing stage in which
the fine aperture is smaller than a target diameter. A first
operation fluid flow rate (Q1) as the flow rate of the operation
fluid flowing through the fine aperture at this time is measured.
In the second process, a second processing time (T1) not reaching
target processing is calculated on the basis of the first operation
fluid flow rate (Q1), and the feeding apparatus is stopped after
polishing is carried out for the second processing time (T1). A
second operation fluid flow rate (Q2) as the flow rate of the
operation fluid flowing through the fine aperture at this point is
measured. In the finishing process, a target third processing time
(T2) is calculated on the basis of the second operation fluid flow
rate (Q2), and polishing is carried out for the third processing
time (T2). Here, the processing time (T1, T2) in the secondary and
finishing processes is determined by a processing capacity
coefficient (K) and the processing capacity coefficient (K) is a
function (K=f(x), x=dQ/T) of a ratio (dQ/T) of an increment amount
(dQ) of the operation fluid flow rate during processing to the
processing time (T).
[0050] To improve the accuracy of the processing time by the method
of estimating the processing time on the basis of the past
statistical amount in fluid polishing, this construction calculates
the processing capacity coefficient for each work or, in other
words, calculates the processing capacity coefficient from the
increment of the operation fluid flow rate and the processing time,
accomplishes processing having higher accuracy by determined the
processing time from the processing capacity coefficient, and
improves the processing accuracy of the fine aperture of the
work.
[0051] In the seventeenth form described above, the eighteenth form
of the invention has a feature that the processing in the primary
process is carried out by feeding the slurry (7) for a first
processing time (T0) that is decided from data of past fluid
polishing and is reliably smaller than a processing time necessary
for processing the target fine aperture.
[0052] According to this construction, because the processing is
carried out in the first process as the first stage of fluid
polishing to a certain extent that reliably does not exceed the
necessary processing amount. Consequently, excessive processing
does not occur and efficient processing capable of reducing the
processing time can be executed.
[0053] The initial stage of fluid polishing is an unstable region
that is affected by the slurry condition and the work shape. In the
nineteenth form of the present invention, therefore, the first
processing time (T0) in the eighteenth form is a time exceeding the
unstable region described above.
[0054] According to this form, processing is done in such a fashion
as to exceed the initial stage as the unstable condition stage of
fluid polishing in the primary process and consequently, the
subsequent secondary process and finishing process become
easier.
[0055] In any of the seventeenth to nineteenth forms described
above, the twentieth form of the invention has a feature that the
second processing time (T1) in said secondary process is calculated
from a formula (1): T1=(Qf-Q1)/first processing capacity
coefficient.
[0056] Here, the first processing coefficient=mean processing
capacity coefficient (K ave)+correction value (.alpha.), and Qf is
a target operation fluid flow rate. The mean processing capacity
coefficient (K ave) is a mean value of processing capacity
coefficients (K) determined from past data of fluid polishing, and
the correction value (.alpha.) is a value larger than one-way
amplitude (3.sigma.) of variance of the past data of the processing
capacity coefficients (K).
[0057] This form discloses a concrete form of a method for deciding
a suitable secondary processing time in the secondary process.
[0058] In the twentieth form described above, the twenty-first form
of the invention has its feature in that the third processing time
(T2) in the finishing process is calculated from equation (2):
T2=(Qf-Q2)/second processing capacity coefficient (Kw) (2).
[0059] The second processing capacity coefficient (Kw) is
calculated from equation (3): Kw=(Q2-Q1)/T1 (3).
[0060] This form discloses a concrete form of a method for deciding
a suitable third processing time in the finishing process.
[0061] In any of the seventeenth to twenty-first forms described
above, the twenty-second form of the invention has its feature in
that the finishing process includes a first stage and a second
stage. In the first stage, a third processing time (T2) not
reaching a target processing is calculated on the basis of the
second operation fluid flow rate (Q2), polishing is carried out for
the third processing time (T2), and then the feeding apparatus is
stopped. A third operation fluid flow rate (Q3) as the flow rate of
the operation fluid flowing through the fine aperture at this point
is measured. In the second stage, a target fourth processing time
(T3) is calculated on the basis of the third operation fluid flow
rate (Q3), polishing is carried out for the fourth processing time
(T3) and then the feeding apparatus is stopped.
[0062] This form discloses a finishing process capable of reliably
improving processing accuracy.
[0063] In the twenty-third and twenty-fourth forms described above,
the twenty-second form described above, the third processing time
(T2) is calculated from equation (4): T2=(Q2-Q1)/second processing
coefficient (Kw2). Here, the second processing capacity
coefficient=mean value of first processing capacity coefficients (K
ave1)+correction value (.beta.). The mean value of the first
processing capacity coefficients (K ave1) is a mean value of the
first processing capacity coefficients determined from past data of
fluid polishing, and the correction value (.beta.) is a value
larger than one-way amplitude of variance of the past data of the
first processing capacity coefficient. In the second stage, the
fourth processing time (T3) is calculated by mathematical
extrapolation, specifically the method of least squares, by using
three measurement values formed from the first, second and third
operation fluid flow rates (Q1, Q2, Q3) measured and from the
first, second and third processing times (T0, T1, T2) corresponding
to the respective flow rates.
[0064] According to the seventh and eighth forms, a method of
deciding a suitable processing time in the finishing process is
further embodied.
[0065] In any of the seventeenth to twenty-fourth forms described
above, the twenty-fifth form of the invention has its feature in
that the feed pressure of the slurry (7) from the feeding apparatus
is kept constant.
[0066] According to this form, polishing of the fine aperture can
be executed more smoothly and without a problem, by fluid
polishing.
[0067] In any of the seventeenth to twenty-fifth forms described
above, the twenty-sixth form of the invention has its feature in
that the work (5) is a fine aperture of a fuel injector for a
diesel engine.
[0068] This form further embodies the application of the present
invention.
[0069] Incidentally, the reference numerals in parentheses, to
denote the above means, are intended to show the relationship of
the specific means which will be described later in an embodiment
of the invention.
[0070] The present invention may be more fully understood from the
description of preferred embodiments of the invention set forth
below, together with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0071] FIG. 1 is an explanatory view schematically showing a fluid
polishing apparatus according to an embodiment of the present
invention;
[0072] FIG. 2 is a flowchart for explaining a fluid polishing
method according to an embodiment of the invention;
[0073] FIG. 3 is a graph showing the time change of a slurry
pressure and a flow rate in a fluid polishing method according to a
prior art example shown in FIG. 5;
[0074] FIG. 4 is a graph showing the relation between a slurry flow
rate immediately before cylinder switching and an oil flow rate at
that time in a fluid polishing method according to a prior art, and
also showing a comparison between a fluid polishing method
according to the invention and a prior art example;
[0075] FIG. 5 is an explanatory view when a slurry is again packed
into a cylinder when a work is fitted and removed in another
embodiment;
[0076] FIG. 6 is an explanatory view showing a schematic equipment
construction of a fluid polishing apparatus according to an
embodiment of the invention;
[0077] FIG. 7 is an explanatory view of a construction of a
processing unit of the fluid polishing apparatus shown in FIG.
6;
[0078] FIG. 8 is an explanatory view of a construction of a
measuring unit of the fluid polishing apparatus shown in FIG.
6;
[0079] FIG. 9 is a graph showing data of the change with the number
of days of a processing capacity coefficient in fluid
polishing;
[0080] FIG. 10 is a flowchart of a slurry degradation prevention
process in a fluid polishing method according to the second
embodiment of the invention;
[0081] FIG. 11 is a graph for explaining a method of detecting a
processing capacity coefficient in the fluid polishing method
according to an embodiment of the invention;
[0082] FIG. 12 is a flowchart of a slurry degradation prevention
process in a fluid polishing method according to the third
embodiment of the invention;
[0083] FIG. 13 is a graph showing data of a processing capacity
coefficient in a work subjected to fluid polishing of the prior
art;
[0084] FIG. 14 is a graph for explaining the relation between an
oil flow rate and a processing time in a fluid polishing method and
also for explaining a processing capacity coefficient of a single
work;
[0085] FIG. 15 is a graph showing the shift of an oil flow rate
with a processing time in the fluid polishing method according to
the fourth embodiment of the invention and also explaining a method
of detecting a processing capacity coefficient;
[0086] FIG. 16 is a flowchart of a fluid polishing method according
to the fourth embodiment of the invention;
[0087] FIG. 17 is a graph showing the shift of an oil flow rate
with a processing time in the fluid polishing method according to
the fifth embodiment of the invention and explaining also a method
of detecting a processing capacity coefficient;
[0088] FIG. 18 is a flowchart of a fluid polishing method according
to the fifth embodiment of the invention and shows process steps up
to a secondary process; and
[0089] FIG. 19 is a flowchart of the fluid polishing method
according to the fifth embodiment of the invention and shows
process steps after a finishing process.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0090] A fluid polishing apparatus according to preferred
embodiments of the invention will be hereinafter explained in
detail with reference to the accompanying drawings.
[0091] FIG. 1 is an explanatory view schematically showing a fluid
polishing apparatus according to one embodiment of the invention
and FIG. 2 is a flowchart for explaining a fluid polishing method
according to an embodiment of the invention that uses the fluid
polishing apparatus shown in FIG. 1.
[0092] To begin with, FIG. 1 shows a schematic construction of a
fluid polishing apparatus 50 according to one embodiment of the
invention. In this embodiment, the fluid polishing apparatus 50 is
used for polishing a fine aperture of an orifice (work) 5 contained
in a fuel injection device (ejector) of a diesel engine. The fluid
polishing apparatus 50 has a slurry tank 1 for accommodating a
polishing fluid (slurry) 7 containing a polishing material. A
stirrer 4 is provided to the slurry tank 1. Separation and
precipitation of the slurry 7 are prevented because the polishing
fluid (slurry) 7 inside the slurry tank 1 is stirred by the stirrer
4. The fluid polishing apparatus 50 further has two sets of
cylinders (feeding apparatuses) 2a and 2beach having a piston 6a
and 6b and two sets of three-way valves 3a and 3b. The cylinders 2a
and 2b are plunger type feeding apparatuses. The cylinders 2a and
2b are for discharging the slurry and two cylinders are provided to
eliminate a suction time loss. For example, while one of the
cylinders 2a discharges the slurry, the other cylinder 2b sucks the
slurry and waits for the switching of the cylinders. Therefore,
when the cylinder 2a is changed over, the slurry can be discharged
without delay by the other cylinder 2b. These cylinders 2a and 2b
preferably have a capacity of at least 100 cc (a capacity capable
of achieving a flow rate 200 cc/min for at least 30 seconds). (This
capacity corresponds to an injector orifice of a diesel engine of
80 kW or more).
[0093] In this way, when the cylinder 2a discharges the slurry to
the orifice 5, the three-way valve 3a communicates piping 11 with
piping 12 and closes an outlet port of piping 13. In this instance,
the three-way valve 3a communicates piping 13 with piping 16 so
that the cylinder 2b can suck the slurry 7 from the slurry tank 1,
and an inlet port of the piping is closed. The three-way valve 3a
communicates the piping 11 with the piping 13 at the time of
switching of the cylinder described above and closes the inlet port
of the piping 12. The three-way valve 3b communicates the piping 14
with the piping 15 and closes the outlet port of the piping 16.
Therefore, the cylinder 2b can discharge the slurry 7 to the
orifice 5 and the cylinder 2a can suck the slurry 7 from the slurry
tank 1. The slurry 7 discharged from the cylinder is supplied to
the orifice 5 to be processed from the piping 12 or 15 through the
piping 17 and the piping 18.
[0094] The fluid polishing apparatus 50 includes an oil cylinder
(operation fluid feeding apparatus) 22, an oil tank (fluidizing
fluid tank) 21, a three-way valve 23 and a stop valve 26. The oil,
kerosene in this case, is sucked from the oil tank 21 into the oil
cylinder 22 through feed piping 23 and the stop valve 26 in the
later-appearing flow rate measuring step, and the oil cylinder 22
feeds the oil into the orifice (work) 5 through the three-way valve
23 and the piping 18. In this instance, the three-way valve 23 is
so set as to communicate the piping 25 with the piping 18 and to
close the piping 17. When the slurry 7 is caused to flow to the
orifice 5, the three-way valve 23 is so set as to communicate the
piping 17 with the piping 18 and to close the piping 35. In this
embodiment, the feeding apparatus of the oil is the plunger type
oil cylinder 22 but another fluid feeding apparatus, such as a
quantitative pump, may be used.
[0095] The polishing method according to one embodiment will be
explained in further detail with reference to the flowchart of FIG.
2.
[0096] When a slurry flow rate target processing step (Step 2 (S2)
to step 6 (S6) in FIG. 2) and a metering step (Step 7 (S7) to Step
13 (S13) are executed in this embodiment, the processing is started
in Step 1 (S1) and the slurry flow rate target processing step is
executed.
[0097] In Step 2 (S2), the piston 6a of the cylinder 2a moves up in
the state where the three-way valve 3a communicates the piping 11
with the piping 12, and discharges the slurry 7 towards the orifice
5. To reach a predetermined discharge flow rate, the ascending
speed of the piston 6a of the cylinder 2a is so controlled as to
supply the slurry 7 at a constant discharge pressure. On the other
hand, the piston 6b of the cylinder 2b moves down in the state
where the three-way valve 3b communicates the piping 14 with the
piping 16, and sucks the slurry 7 from the slurry tank 1. Next, the
flow proceeds to Step 3 (S3) and whether or not the slurry flow
rate reaches the target value is judged. When the flow rate does
not reach the target value (NO), the piston 6a keeps moving up. On
the other hand, the descending speed of the piston 6b for sucking
the slurry is preferably constant and is sufficiently higher than
the ascending speed of the piston 6a of the cylinder 2a. Generally,
therefore, the piston 6b quickly reaches its lower end and the
slurry 7 fills the inside of the cylinder 2b.
[0098] The ascending speed of the piston 6a becomes gradually
higher as the processing hole becomes larger in size and,
eventually, the slurry flow rate reaches the target value. In this
instance, as a flag of arrival at the target value (YES) is set in
Step 3, the flow proceeds to Step 4 (S4). In S4, the cylinder 2a is
stopped and the flow proceeds to Step 5 (S5). As the three-way
valves 3a and 3b are switched as described above, the cylinder is
switched from 2a to 2b. The flow proceeds from S5 to Step 6 (S6).
The three-way valve 23 is then switched and the oil (operation
fluid) flow rate measurement is executed. In the measurement of the
oil flow rate, the oil is caused to flow at a predetermined
constant pressure and the oil flow rate in this case is measured.
In Steps S5 and S6 after S4, the piston 6b of the cylinder 2b has
already reached the lowermost end and the cylinder 2b has been
filled with the slurry 7. The slurry 7 inside the cylinder 2a is
returned to the slurry tank 1 as the piston 6a is moved up to the
upper end.
[0099] After S6, the flow proceeds to the metering step. In Step 7
(S7), the necessary processing time subsequently required is
calculated on the basis of the measured oil flow rate value. Next,
the flow proceeds to Step 8 (S8). In S8, the piston 6b of the
cylinder 2b moves up, preferably in such a fashion that the slurry
discharge pressure becomes constant, and the fluid polishing step
is advanced by causing the slurry 7 to flow towards the orifice
(work) 5. In Step 9 (S9), whether or not the predetermined
necessary processing time is reached is judged and the processing
is continued by moving up, as such, the piston 6b when the judgment
result is NO. The flow proceeds to Step 10 (S10) at the point at
which the judgment result is YES. The cylinder 2b is stopped in
S10. From S7 to S10, the piston 6a of the cylinder 2a is moved down
at a higher speed than the ascending speed of the piston 6b on the
basis of the calculated necessary processing time, to suck the
slurry 7 from the slurry tank 1 and to fill the cylinder 2a with
the slurry 7.
[0100] In Step 11 (S11), the three-way valves 3a and 3b are
switched in the same way as cylinder switching of S5 to switch the
cylinder from 2b to 2a. After S11, the residual slurry 7 inside the
cylinder 2b is fully returned to the slurry tank 1 in the same way
as in S5. In Step 12 (S12), the oil flow rate measurement is
conducted by the same procedure and method as in S6 described
above. In Step 13 (S13), whether or not the oil flow rate reaches
the target value is judged. When the judgment result proves NO
(when the flow rate does not reach the target value), the flow
returns to S7 and the necessary processing time is again
calculated. The steps S8 to S13 are repeated by using the cylinder
2a. This repetition is conducted until the oil flow rate finally
reaches the target value. When the oil flow rate reaches the target
value (YES) in S13, the flow proceeds to Step 14 (S14) and the
processing is completed.
[0101] Next, the effects and operations of the embodiment described
above will be explained.
[0102] The following effects can be expected from the fluid
polishing method according to this embodiment and fluid polishing
apparatus capable of executing the fluid polishing method.
[0103] In each step of fluid polishing for supplying the slurry to
the orifice as the work by using the cylinders each having a
sufficient capacity, the insertion of the cylinder switching
operation during the processing can be avoided. Therefore, a
temporary fluctuation of the slurry flow rate during the processing
can be prevented and the processing accuracy of the fine aperture
of the orifice can be improved.
[0104] The slurry inside the cylinder that is switched and enters
the standby state in the next step is completely returned to the
slurry tank. Therefore, the separation of the slurry and the
precipitation of the abrasives inside the cylinder can be prevented
and this effect also contributes to an improvement in the
processing accuracy of the fine aperture of the orifice.
[0105] Next, another embodiment of the invention will be explained.
In the embodiment described above, the remaining slurry inside the
cylinder 2a or 2b is returned to the slurry tank during the period
from the stop of the cylinder (S4 or S10) to completion of the oil
flow rate measurement (S6 or S12). The new slurry 7 is thereafter
sucked from the slurry tank 1 to fully fill the cylinder to prepare
for the next fluid polishing step. In another embodiment, in
contrast, it is also possible to return the remaining slurry 7
inside the cylinder to the slurry tank 1 and to again suck the new
slurry from the slurry tank 1 to fully fill the cylinder during the
work fitting/removing step in which the work 5 is fitted and
removed to and from the polishing portion (see FIG. 5). This work
fitting/removing step is carried out between S14 and S1 in the
flowchart shown in FIG. 2. The work fitting/removing step may also
be carried out by using a robot or pick-and-press by an operator as
shown in FIG. 5.
[0106] In this embodiment, too, effects similar to the effects
described above can be acquired.
[0107] In the embodiments described above and in the embodiments
shown in the accompanying drawings, the feeding apparatus for
feeding the slurry to the work is the cylinder as a plunger type
pump. However, the feeding apparatus may be various known pumps or
fluid feeding apparatuses. Though two sets of slurry feeding
apparatuses are provided above, the number of the feeding apparatus
may be one or three or more sets. The three-way valve may be a
combination of changeover valves.
[0108] Even when the cylinder as the slurry feeding apparatus is
only one as described above, the replacement and refilling of the
slurry are carried out during the cylinder stopping step (S4 or S10
in the embodiment described above) to the oil flow rate measuring
step (S6 or S12 in the embodiment described above) or during the
work fitting/removing step in another embodiment, and the fluid
processing of one process can be executed without interruption of
the processing. Thus, the effects of the present invention can
similarly be accomplished. Incidentally, the flowchart of the fluid
polishing process in this case is similar to the flowchart of the
embodiment shown in FIG. 2 though the cylinder switching step is
deleted.
[0109] This embodiment represents the case of processing of the
orifice for the diesel engine common rail injector by way of
example but the invention is not particularly limited thereto but
may be applied to processing of other orifices or processing of
fine apertures such as the distal end of the nozzle of the fuel
injector, the jet port of the carburetor, the orifice for
regulating the fluid flow rate, the jet nozzle of printers, and so
forth, as described already.
[0110] Next, the second embodiment of the invention will be
explained.
[0111] FIGS. 6 to 8 schematically show a fluid polishing apparatus
according to this embodiment of the invention. FIG. 6 shows a
schematic of the fluid polishing apparatus 50. FIG. 7 is an
explanatory view for explaining the construction of a (fluid
processing) processing unit 10 of the fluid polishing apparatus 50
shown in FIG. 6. FIG. 8 is an explanatory view for explaining the
construction of an (oil flow rate) measuring unit 20 of the fluid
polishing apparatus 50 shown in FIG. 6. In this embodiment, the
work to be processed is an orifice of an injector (fuel injection
device) for a diesel engine common rail and its fine aperture is
subjected to fluid polishing by the fluid polishing apparatus
50.
[0112] Referring initially to FIG. 6, the fluid polishing apparatus
50 of this embodiment includes a (fluid polishing) processing unit
(portion) 10, a measuring unit (portion) 20 of an oil flow rate and
a washing unit (portion) 40.
[0113] The processing unit 10 causes a slurry 7 (processing medium:
mixture of abrasives and oil) to flow to the orifice 5 as the work
from a slurry feeding apparatus (slurry tank 1+cylinders 2a and 2b
) and to execute the processing. After the processing is complete,
the work is washed by the washing portion 40. Next, the measuring
unit 20 causes the oil as an operation fluid to flow from an oil
feeding apparatus (oil tank 21+cylinder 22) to the orifice 5 and
the flow rate at this time is measured by a flow rate meter 25.
This cycle is repeated until a target oil flow rate is reached.
[0114] Next, FIG. 7 shows a schematic construction of a processing
unit 10 inside the fluid polishing apparatus 50 shown in FIG. 6.
The processing unit 10 includes a slurry tank 1 for accommodating
the polishing fluid (slurry) 7 containing an abrasive material, and
a stirrer 4 is provided to the slurry tank 1. As the slurry 7
inside the slurry tank 1 is stirred by the stirrer 4, separation
and precipitation of the slurry 7 is prevented. The processing unit
10 further includes two cylinders (feeders) 2a and 2b each having a
piston 6a and 6b, two sets of three-way valves 3a and 3b and check
valves 8a and 8b. The cylinders 2a and 2b are plunger type feeders.
The cylinders 2a and 2b are for discharging the slurry and two are
provided in order to eliminate a loss of suction time. For example,
while one of the cylinders 2a discharges the slurry, the other 2b
sucks the slurry and enters the standby state until the cylinders
are switched. When the cylinders are switched, therefore, the
slurry 7 can be discharged by the other cylinder 2b without
delay.
[0115] In this case, when the cylinder 2a discharges the slurry 7
to the orifice 5, the three-way valve 3a is so set as to
communicate piping 11 with piping 12 and to close an outlet of
piping 13. In order for the cylinder 2b to suck the slurry 7 from
the slurry tank 1 in this instance, the three-way valve 3b is so
set as to communicate piping 14 with piping 16 and to close an
inlet of piping 15. At the time of switching of the cylinders
described above, the three-way valve 3a is so set as to communicate
the piping 11 with the piping 13 and to close the inlet of the
piping 12 and the three-way valve 3b is so set as to communicate
the piping 14 with the piping 15 and to close the outlet of the
piping 16. Consequently, the cylinder 2b is able to discharge the
slurry 7 to the orifice 5 and the cylinder 2a is able to suck the
slurry 7 from the slurry tank 1. The slurry 7 discharged from the
cylinder is supplied to the orifice 5 to be passed from the piping
12 or 15 through the piping 17 and 18. The check valves 8a and 8b
prevent the backflow to the cylinders 2a and 2b, respectively.
[0116] An (oil flow rate) measuring unit 20 includes an oil
cylinder (operation fluid feeding apparatus) 22, an oil tank
(operation fluid tank) 21, a three-way valve 23 and a check valve
28. In a later-appearing oil flow rate measuring procedure, the oil
(operation fluid) (kerosene in this case) is sucked from the oil
tank 21 into the oil cylinder 22 through a feed piping 33, the
three-way valve 23 and a piping 31. The oil cylinder 22 supplies
the oil to the orifice (work) 5 through the piping 31, the
three-way valve 23, the check valve 28, piping 32, a pressure
sensor 29, a flow rate meter 25 and piping 34. In this instance,
the three-way valve 23 is so set as to communicate the piping 31
with 32 and to close the piping 33. In this embodiment, the oil
feeder is the plunger type oil cylinder 22 but another fluid feeder
such as a quantitative pump may be used as well. The piping 34 may
be connected to the piping 18 of the processing unit 10.
[0117] Next, for the fluid polishing apparatus 50 having the
construction described above, an explanation will be given about
the case where a fine aperture is processed in the orifice as the
work by the fluid polishing method according to this embodiment of
the invention. First, a pre-boring processing is applied to the
orifice 5 by laser processing, or the like. The fluid polishing
method according to this embodiment is thereafter carried out. The
slurry 7 as the polishing fluid is supplied at a predetermined
pressure from the cylinder 2a, for example, of the processing unit
10. In this case, a controller, not shown in the drawings, controls
the cylinder 2a so that the pressure of the slurry 7 attains the
predetermined pressure.
[0118] In this embodiment, a processing capacity coefficient (K) is
set to decide a processing time (T). Fluid polishing is carried out
for this processing time (T) to highly precisely finish a fine
aperture having a predetermined size. The processing time (Ti) of
one process is set to be shorter than the processing time necessary
for processing the fine aperture having a predetermined size.
Whenever one process is carried out, the actual operation fluid
(oil: here, kerosene) is caused to flow through the fine aperture
and the oil flow rate (Qi) is measured. The processing time (Ti+1)
of the next step is determined on the basis of the oil flow rate
(Qi) measured immediately before. A plurality of steps is carried
out in this way and processing is done in such a fashion as to
gradually finish the work to a fine aperture of the predetermined
size.
[0119] The processing capacity coefficient (Ki) as the basis for
calculating the processing time is decided by the change amount
(dQi) of the oil flow rate (Qi) when fluid polishing is carried out
for a certain processing time (Ti). In other words, the processing
capacity coefficient: Ki=dQi/Ti.
[0120] In this embodiment, the change of quality of the slurry as
the polishing fluid is grasped as the change of the processing
capacity coefficient (K) of the slurry, and counter-measures are
taken in accordance with the change of this processing capacity
coefficient so as to maintain the efficiency of fluid polishing.
The processing capacity coefficient becomes smaller with
degradation of the quality of the slurry. Therefore, the processing
time increases when a processing that generates the same oil flow
rate change is carried out.
[0121] FIG. 9 shows the change of the processing capacity
coefficient (K) due to fluidization (as the slurry is used for
processing). The processing pressure is constant at each point
plotted. As is obvious from this graph, the processing capacity
coefficient (K) drops day by day. Here, the change of the
processing capacity coefficient (K) is associated with processing
energy. This processing energy W is expressed by W=.alpha.PQ (where
.alpha. is a coefficient, P is a processing pressure and Q is a
flow rate). The flow rate Q is expressed by Q=CA (P/.rho.) (where C
is a flow rate coefficient, A is an orifice sectional area and
.rho. is a density). When the slurry becomes deteriorated (change
of a blend ratio owing to wear of abrasives, mixture of oil, etc),
.alpha. and .rho. change. In consequence, processing energy drops
and the processing capacity coefficient decreases in accordance
with the former.
[0122] Because processing energy has a relation with the pressure,
however, the processing capacity can be kept constant if the
pressure is carefully controlled to match the decrease of the
processing capacity coefficient. Alternatively, the processing
capacity can be kept constant by conducting addition of slurry on
the basis of the processing capacity coefficient and keeping
.alpha. and .rho. constant. For example, when the processing
capacity coefficient (K) is below a certain threshold value a as
shown in the flowchart of FIG. 10, the addition of the slurry and
the change of setting of the pressure are made. To achieve this
procedure, however, it is necessary to detect the present
processing capacity coefficient.
[0123] Each work is subjected to retry processing until it falls
within the oil flow rate standard. Therefore, the processing
capacity coefficient (Ki=dQ/T) of the work is calculated from the
oil flow rate change (dQ=Q2-Q1) before and after processing and the
processing time (T) as shown in FIG. 11. Because the processing
capacity coefficient can be calculated for each retry, it is
averaged by the number of times of retries (M times) and the
processing capacity coefficient of each work is determined
(.SIGMA.Kj-Ki/M). Furthermore, because the processing capacity has
a variance for each work, the processing capacities of N works is
moved and averaged (.SIGMA.Kj/N) to more accurately detect the
processing capacity.
[0124] The outline of the fluid polishing method according to this
embodiment will be explained with reference to FIG. 11. For
example, the oil as the operation fluid is allowed to flow to the
fine aperture of the orifice 5 after a pre-boring step and a first
oil (operation fluid) flow rate Q1 is measured. Fluid polishing of
the first stage is then started. In this processing of the first
stage, the first processing time T0 to the second oil flow rate Q2
smaller than the target oil flow rate Qf in the target fine
aperture is determined (T0=(Q2-Q1)/K) by using the processing
capacity coefficient K obtained on the basis of the past fluid
polishing data. Fluid polishing is carried out for the first
processing time T0 in the first step processing. In this stage, the
actual oil flow rate Q' is measured.
[0125] The subsequent processing steps are carried out in the same
way as the first step described above. In the example shown in FIG.
11, the steps are executed three times and the processing is
completed because the oil flow rate falls within the standard. In
the example shown in FIG. 11, the oil flow rate Qi is measured at
the end of each step. Because the processing time Ti in each step
is known, the actual processing capacity coefficient Ki in each
step can be calculated. Therefore, the average of the processing
capacity coefficients of one work (Kj=.SIGMA.Ki/M) can be
determined.
[0126] FIG. 10 shows a flowchart of the process of the
counter-measure stage against degradation of the slurry in the
fluid polishing method according to the second embodiment of the
invention. When this process is started in Step 101 (S101), the
processing capacity coefficient (Ki) in each step is calculated by
fluid polishing a specific one of the works in Step 102 (S102) and
the mean value (Kj) of the processing capacity coefficients is
determined as described above (This is the processing capacity
coefficient of this work). These values (Ki, Kj) are stored in the
storage device. Next, in Step 103 (S103), the moving average
(.SIGMA.Kj/N) of the processing capacity coefficient based on the
data of N works by adding the data of the processing capacity
coefficient of one work described above to the data of the
processing capacity coefficients of N-1 works that are previously
fluid-polished.
[0127] Next, in Step 104, whether or not the moving average
described above becomes smaller than a predetermined threshold
value (a) is examined. When it is smaller than the predetermined
threshold value (a), the pressure setting is changed and increased.
When it is larger than the predetermined threshold value (a),
nothing is changed and the flow is as such finished (Step 106
(S106)) and processing of the next work is carried out with the
same properties of the slurry and at the same discharge
pressure.
[0128] FIG. 12 shows the flowchart of the third embodiment of the
present invention. In the third embodiment, the addition of the
slurry is executed in place of the change of setting of the
processing pressure in Step 105 of the flowchart of the second
embodiment as the counter-measure by the improvement of quality of
the slurry. As the rest of the procedures are the same as those of
the second embodiment, a repetition of the explanation will be
omitted.
[0129] The change of setting of the processing pressure and the
addition/renewal of the slurry may be selectively used depending on
the degree of quality degradation of the slurry. For example, it is
permissible to execute the addition/renewal of the slurry depending
on the level of the processing pressure and to renew the slurry
depending on the number of times of addition of the slurry. The
change of setting of the processing pressure and the
addition/renewal of the slurry may thus be used selectively and
appropriately depending on the conditions.
[0130] Next, the effects and operations of this embodiment will be
explained.
[0131] The fluid polishing method and the apparatus for the method
according to the second embodiment of the invention provide the
following effects.
[0132] Degradation of slurry quality is detected as the change of
the processing capacity coefficient, and the threshold value of
this processing capacity coefficient is set. When the processing
capacity coefficient becomes smaller than a threshold value, the
processing pressure is elevated, as a counter-measure, to prevent
an increase in the processing cycle time (CT).
[0133] The fluid polishing method and the apparatus for the method
according to the third embodiment of the invention provide the
following effects.
[0134] The addition of the slurry is executed when the processing
capacity coefficient becomes smaller than the threshold value in
the same way as in the second embodiment to prevent an increase in
the processing cycle time (CT).
[0135] In the embodiments described above or shown in the
accompanying drawings, the feeding apparatus for feeding the slurry
to the orifice as the work is a cylinder of the plunger type pump
but may be various known pumps or fluid feeding apparatuses besides
a plunger type pump. Two or more feeding apparatuses may be
provided though one feeding apparatus is shown in the embodiments
described above.
[0136] Though the foregoing embodiments represent the application
of the present invention to the processing of the orifice for the
diesel engine common rail injector, the invention is not
particularly limited thereto but may be applied to the processing
of other orifices or the processing of fine apertures such as tips
of the nozzle of fuel injection devices, jet ports of carburetors,
orifices for regulating the flow rate of a fluid, jet nozzles of
printers, and so forth.
[0137] Next, the fourth embodiment of the present invention will be
explained.
[0138] To execute this embodiment, the processing time (T) is
decided and the fluid polishing processing is carried out for this
processing time (T). The processing time (T) has been determined in
the past by the processing capacity coefficient (K) that is a
statistical value as shown in FIG. 13.
[0139] The method of deciding the processing time in the fourth
embodiment of the invention will be explained with reference to
FIG. 15.
[0140] In fluid polishing processing, there is an unstable region
in which the processing capacity coefficient (K) changes due to
influences of the slurry condition and the work shape, in an
initial stage of processing. However, it has been found, through
experiment, that the processing capacity coefficient (K) becomes
constant after processing is carried out for a certain
predetermined time (first processing time (T0) inside the work and
the processing capacity coefficient (K) is out of the unstable
region (FIG. 14). This first processing time (T0) is the time when
the time is out of (pass through) the unstable region but is a time
in which the formation of the fine aperture, as the object, is not
reliably reached. In the processing for the first processing time
(T0), the slurry supply flow rate increases to a value that is
determined in advance and is smaller than the predetermined slurry
flow rate necessary for processing the fine aperture as the object.
Because the predetermined time T0 is different depending on the
diameter of the pre-work aperture before polishing, etc, it is
decided by prior processing tests. Alternatively, as the processing
may well be carried out for a time exceeding the time T0, the
slurry flow rate may be stopped at the slurry flow rate that brings
the processing to the time longer than the time T0. After the
processing is conducted for the predetermined time (T0), a
correction value (.alpha.=3.sigma.) of variance approximate to
one-way amplitude 3.sigma. (see FIG. 13) is added to the mean value
(K ave) of the N times of the processing capacity coefficients of
the past works to obtain a provisional (first) processing capacity
coefficient (K ave+.alpha.). The second processing time (T1) is
estimated on the basis of the first processing time (T1=(Qf-Q1)/(K
ave +.alpha.)). Here, Qf is the target oil (operation fluid) flow
rate, that is, the oil flow rate when the processing is carried out
normally. Because the provisional (first) processing capacity
coefficient (K ave+.alpha.) is sufficiently larger than the actual
value, the target flow rate is not reached even when the processing
is carried out. The second processing capacity coefficient of the
work is detected (Kw=dQ/T1) from the change amount of the oil flow
rate before and after processing (dQ=Q2-Q1) and the second
processing time (T1). An optimal third processing time T2 is
estimated (T2=(Qf-Q2/Kw) from the difference (Qf-Q2) between the
second processing capacity coefficient (Kw) inherent to the work
and the target value. Processing can be done very precisely by
using this third processing time T2 and the target oil flow rate
can be reached. As described above, the processing capacity
coefficient (K) is calculated for each work and the processing time
(T) is decided on the basis of the processing capacity coefficient
(K).
[0141] FIG. 16 shows a flowchart of the fluid polishing method
according to the fourth embodiment of the invention. When the fluid
polishing method of this embodiment is started in Step 201 (S201),
a feeding apparatus such as the piston 6a of the cylinder 2a moves
up in Step 202 (S202) and supplies the slurry 7 as the polishing
fluid to the orifice 5, as the work, at a predetermined pressure.
The fluid polishing processing is executed till the predetermined
first processing time (T0) and when the first processing time (T0)
is reached in Step 203 (S203), the piston 6a stops in Step 204
(S204). The cylinder is preferably switched from 2a to 2b in Step
205 (S205). It is preferred that, at the time of switching, the
cylinder 2b completely returns the residual slurry remaining
therein to the slurry tank 1 and again fully fills the tank with
the slurry 7. Next, the first oil (operation fluid) flow rate is
measured in Step 206 (S206) (this flow rate is called "Q1" in FIG.
15). The flow then proceeds to Step 207 (S207), in which the second
processing time (T1) is calculated. This processing time is decided
as described above by adding the correction value .alpha. to K ave
on the basis of the mean value (K ave) of the processing capacity
coefficients of the past data lest T1 becomes excessively large.
Steps S201 to S206 correspond to the first processing steps.
[0142] In Step 208 (S208), the piston 6b of the cylinder 2b moves
up as the cylinder is switched in S205 and the slurry 7 is supplied
to the orifice 5. When the processing time reaches the second
processing time T1 in Step 209 (S209), the flow proceeds to Step
210 (S210) and the cylinder 2b stops. In Step 211 (S211), the
cylinder is preferably switched from 2b to 2a in the same way as in
S205. The flow then proceeds to Step 212 (S212) and the second oil
flow rate (Q2) is measured in S212. The steps from S07 to S212
correspond to the second processing step.
[0143] In Step 213 (S213), the second processing capacity
coefficient (Kw) is calculated on the basis of Q1, Q2 and T1 as
described above. In Step 214 (S214), the third processing time (T2)
is calculated on the basis of Kw as described above. Subsequently,
in Step 215 (S215), the piston 6a of the cylinder 2a moves up and
supplies the slurry 7 to the orifice 5 to execute the polishing
processing. In Step 216 (S216), whether or not the third processing
time T2 is reached is checked. When T2 is reached, the piston 6a is
stopped (Step 217 (S217)) and the processing is finished (Step 218
(S218)). The steps from S213 to S217 correspond to the finishing
step.
[0144] FIGS. 17, 18 and 19 respectively show a method of detecting
the processing capacity coefficient of the fluid polishing method
according to the fifth embodiment of the invention and its
flowcharts. Here, the difference from the first embodiment will be
described. The flowchart of this embodiment is divided into two
drawings. The flowchart of FIG. 9 shows the process from the start
to the secondary process and the flowchart of FIG. 19 shows the
finishing process. In the fifth embodiment, the procedures from
S201 to S212 of the fourth embodiment are the same but the
calculation method of the second processing capacity coefficient
(Kw2) in S213 is different between the fourth embodiment and the
fifth embodiment. The primary and secondary processes are the same
but the finishing process is different. In this embodiment, .beta.,
a value equivalent to the correction value .alpha., is introduced
and the second processing capacity coefficient (Kw2). is given by
Kw2=Kw+.beta.. Here, Kw=(Q2-Q1)/T1. The value .beta. is set to a
value approximate to a one-way amplitude of variance of the mean
value of the past first processing capacity coefficients (Kw), for
example, in the same way as .alpha.. The third processing time (T2)
is calculated on the second processing capacity coefficient Kw2 in
S214 (T2=(Q5-Q2)/Kw2) (see FIG. 17). When .beta. is set in this
way, the target processing value is not reached by the processing
for the third processing time T2.
[0145] The flow further proceeds to Step 215 (S215), in which the
piston 6a is moved up and the slurry 7 is supplied to the orifice
5. When the arrival at the third processing time T2 is detected in
Step 216 (S216), the piston 6a is stopped in Step 217 (S217) and
the cylinder is switched in Step 221 (S221) in the same way as in
S205 and S211. In Step 222 (S222), the third oil flow rate (Q3) is
measured (see FIG. 17) and the third processing capacity
coefficient (Ks) is calculated in Step 223 (S223). The calculation
method of Ks is as follows. The gradient of an approximation line
(thick solid line in FIG. 17) is determined by the method of least
squares from the three points of Q1 and T0, Q2 and T1(T0+T1) and Q3
and T2(T0+T1+T2) and this is set as Ks. In Step 224 (S224), the
line is extended at the gradient Ks from Q3 as shown in FIG. 17 to
determine the fourth processing time (T3) (T3=(Qf-Q3)/Ks). In this
explanation, Ks is determined by the method of least squares but Ks
may be determined by known mathematical methods that performs
extrapolation from the three points described above.
[0146] In Step 225 (S225), the piston 6b moves up and the slurry 7
is caused to flow to the orifice 5. In Step 226 (S226), whether or
not the fourth processing time (T3) is reached is checked and the
processing is finished (Step 218 (S218)). In the finish processing
step (from S213 to S227) in the fifth embodiment, Steps from S213
to S222 are the first stage and Steps from S223 to S227 are the
second stage.
[0147] Next, the functions and operations of the embodiment
described above will be explained.
[0148] The fluid polishing method and the apparatus for the method
according to the fourth embodiment of the invention provide the
following effects.
[0149] To improve the accuracy of the processing time by the method
of estimating the processing time on the basis of the past
statistical amounts in the fluid polishing processing, the
processing capacity coefficient is calculated from the processing
condition of the fine aperture of the orifice during the
processing, and the processing time is decided from this
coefficient. Consequently, the processing accuracy of the fine
aperture of the orifice is improved.
[0150] The fluid polishing method and the apparatus for the method
according to the fifth embodiment of the invention provide the
following effects.
[0151] There is the possibility that processing accuracy can be
improved much more than in the fourth embodiment.
[0152] In the embodiments described above or shown in the
accompanying drawings, the feeding apparatus for supplying the
slurry to the orifice as the work is the cylinder that is the
plunger type pump. However, the feeding apparatus may be a known
pump or fluid feeding apparatus other than the plunger type pump.
Though two slurry feeding apparatuses are provided, one or at least
three feeding apparatuses may be provided.
[0153] The foregoing embodiments represent the example where the
invention is applied to the processing of the orifice for the
diesel engine common rail injector. However, the invention is not
particularly limited thereto and may be applied to the processing
of other orifices or the processing of fine apertures such as the
tip of a fuel injector, the jet aperture of a carburetor, orifices
for regulating a fluid flow rate, the jet nozzles of printers, and
so forth, as described already.
[0154] The embodiments given above merely represent preferred
examples of the invention but in no way limit the invention. In
other words, the invention is defined by only the subject matters
described in the Scope of Claim for Patent, and can be executed in
other forms or embodiments.
[0155] While the invention has been described by reference to
specific embodiments chosen for purposes of illustration, it should
be apparent that numerous modifications could be made thereto, by
those skilled in the art, without departing from the basic concept
and scope of the invention.
* * * * *