U.S. patent application number 15/360321 was filed with the patent office on 2017-04-13 for laser machining method.
This patent application is currently assigned to SUGINO MACHINE LIMITED. The applicant listed for this patent is SUGINO MACHINE LIMITED. Invention is credited to Masanori KANEMITSU, Ryoji MURATSUBAKI, Yukiaki NAGATA, Masashi TSUNEMOTO.
Application Number | 20170100798 15/360321 |
Document ID | / |
Family ID | 47218526 |
Filed Date | 2017-04-13 |
United States Patent
Application |
20170100798 |
Kind Code |
A1 |
NAGATA; Yukiaki ; et
al. |
April 13, 2017 |
LASER MACHINING METHOD
Abstract
Laser machining method, including: liquid supplying into
rectifying chamber; rectifying chamber attenuating disturbances in
flow of liquid supplied; liquid injecting into liquid oscillating
chamber exclusively from one direction from liquid inlet port
arranged on only one portion of sidewall of liquid oscillating
chamber; liquid jetting as jet liquid column into air from nozzle;
laser beam focusing on axis of nozzle and guiding to machining
point by jet liquid column; surface wave of jet liquid column
generating and gradually increasing in amplitude in direction away
from nozzle; a body of jet liquid column atomizing when jet liquid
column strikes workpiece on machining point. Liquid flows from
oscillating chamber inlet path for guiding liquid from rectifying
chamber to oscillating chamber inlet port, oscillating chamber
inlet path guiding liquid along window from one direction of liquid
oscillating chamber to oscillating chamber inlet port.
Inventors: |
NAGATA; Yukiaki;
(Kurobe-shi, JP) ; MURATSUBAKI; Ryoji; (Uozu-shi,
JP) ; KANEMITSU; Masanori; (Uozu-shi, JP) ;
TSUNEMOTO; Masashi; (Uozu-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SUGINO MACHINE LIMITED |
Uozu-shi |
|
JP |
|
|
Assignee: |
SUGINO MACHINE LIMITED
Uozu-shi
JP
|
Family ID: |
47218526 |
Appl. No.: |
15/360321 |
Filed: |
November 23, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
13476677 |
May 21, 2012 |
|
|
|
15360321 |
|
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B23K 26/16 20130101;
B23K 26/146 20151001 |
International
Class: |
B23K 26/146 20060101
B23K026/146; B23K 26/16 20060101 B23K026/16 |
Foreign Application Data
Date |
Code |
Application Number |
May 25, 2011 |
JP |
2011-116692 |
Nov 25, 2011 |
JP |
2011-257232 |
Claims
1. A laser machining method, comprising: a liquid supplying into a
rectifying chamber; the rectifying chamber attenuating disturbances
in flow of the liquid supplied; a liquid injecting into a liquid
oscillating chamber exclusively from one direction from a liquid
inlet port arranged on only one portion of a sidewall of the liquid
oscillating chamber; the liquid jetting as a jet liquid column into
air from a nozzle; a laser beam focusing on the axis of the nozzle
and guiding to a machining point by the jet liquid column; a
surface wave of the jet liquid column generating and gradually
increasing in amplitude in the direction away from the nozzle and a
body of the jet liquid column atomizing when the jet liquid column
strikes the workpiece on the machining point, wherein the liquid
flows from an oscillating chamber inlet path for guiding the liquid
from the rectifying chamber to the oscillating chamber inlet port,
the oscillating chamber inlet path guiding the liquid along the
window from one direction of the liquid oscillating chamber to the
oscillating chamber inlet port.
2. The laser machining method according to claim 1, wherein the
liquid flows into the oscillating chamber along the window.
3. The laser machining method according to claim 1, wherein a
focusing optical system focuses the laser beam toward the window
with respect to the nozzle inlet opening for causing a portion of
the laser beam to strike a flow contracting portion at which the
jet liquid column is formed and further increasing the surface wave
on the outer surface of the jet liquid column.
4. The laser machining method according to claim 1, further
comprising: a mist jet inject on a workpiece surface to remove
residues generated by machining.
Description
[0001] This is a Divisional application of application Ser. No.
13/476,677 filed May 21, 2012, which claims priority to JP
2011-257232 filed Nov. 25, 2011 and JP 2011-116692 filed May 25,
2011. The disclosures of the prior applications are hereby
incorporated by reference herein in their entirety.
BACKGROUND
[0002] 1. Technical Field
[0003] The present invention relates to a laser machining method
and more particularly, to a laser machining method using a laser
beam that is guided by a jet liquid column.
[0004] 2. Related Art
[0005] Japanese Patent No. 3680864 discloses an apparatus for
machining a material with a laser beam. In this apparatus, a liquid
beam is jetted by a nozzle, and the laser beam is focused at an
intake opening of the nozzle. Thus, the laser beam is guided by the
liquid beam to reach a workpiece, so that the workpiece is
machined.
[0006] Additionally, Japanese Published Unexamined Patent
Application No. 2010-221265 discloses a laser machining apparatus.
In this laser machining apparatus, a liquid is jetted from a
nozzle, and a workpiece is machined by a laser beam that is
introduced into a jet liquid column jetted from the nozzle. Also, a
protective cover is disposed between the nozzle and the workpiece.
The jetted liquid reaches the workpiece through a through-hole
provided in the protective cover.
[0007] However, in the apparatus (the laser machining apparatus)
disclosed in Japanese Patent No. 3680864, there is a problem in
that, when the liquid beam (the jet liquid column) jetted to guide
the laser beam strikes the workpiece, liquid is splashed back from
the workpiece, and a mass of the splashed-back liquid strikes the
jet liquid column, leading to disturbance in the jet liquid column.
If a disturbance occurs in the jet liquid column, the laser beam
that is guided while repeating total reflection within the jet
liquid column becomes likely to leak out of the jet liquid column,
causing a reduction in the laser guiding efficiency as well as the
machining performance. Furthermore, in the case of cutting of a
thick workpiece or deep hole drilling in a workpiece with the laser
machining apparatus, since the machining cannot be completed in one
scanning, the jet liquid column needs to be reciprocated several
times in the same machining path. Especially in such a case, the
influence of the splashed-back liquid increases.
[0008] On the other hand, in the laser machining apparatus
disclosed in Japanese Published Unexamined Patent Application No.
2010-221265, the protective cover is provided for protecting the
jet liquid column from the liquid that strikes the workpiece and is
splashed back, thereby suppressing a reduction in laser guiding
efficiency. However, also in this laser machining apparatus, there
is a problem in that the splashed-back liquid strikes a portion of
the jet liquid column in between the protective cover and the
workpiece, leading to disturbance in the jet liquid column. There
is also a problem in that, even if the jet liquid column is
protected from droplets of the liquid splashed back from the
workpiece, when the jetted liquid is accumulated on a surface of
the workpiece to form a water layer, the accumulated liquid causes
a reduction in light guiding efficiency. In other words, when a
water layer is formed on the surface of the workpiece, the laser
beam introduced by the jet liquid column might be scattered by the
accumulated liquid or the light path of the laser beam might be
changed by the influence of the water layer. Especially in the case
of deep hole drilling with the laser machining apparatus, water is
likely to be accumulated inside the hole during machining, and
therefore the water layer exerts a great adverse influence.
SUMMARY
[0009] Accordingly, an object of the present invention is to
provide a laser machining method which can efficiently machine a
workpiece.
[0010] To address the above-mentioned problems, an aspect of the
present invention provides a laser machining method using a laser
beam that is guided to a machining point by a jet liquid column.
The laser machining apparatus includes a nozzle, a rectifying
chamber, a liquid oscillating chamber, a laser oscillator, a
focusing optical system, and a window. The nozzle includes a nozzle
inlet opening. The nozzle jets the jet liquid column. The
rectifying chamber attenuates disturbances in flow of supplied
liquid. The liquid oscillating chamber includes an oscillating
chamber inlet port that allows inflow of the liquid from the
rectifying chamber. The liquid oscillating chamber guides the
inflowing liquid to the nozzle inlet opening. The laser oscillator
generates a laser beam. The focusing optical system focuses the
laser beam generated by the laser oscillator above the nozzle inlet
opening to cause the jet liquid column to guide the laser beam. The
window is opposed to the nozzle inlet opening to cause the laser
beam exiting from the focusing optical system to enter the liquid
oscillating chamber. The liquid oscillating chamber increases a
surface wave on an outer surface of the jet liquid column to cause
the jet liquid column jetted from the nozzle onto a workpiece to be
easily atomized at the machining point.
[0011] According to the aspect of the present invention, supplied
liquid flows into the rectifying chamber to be subjected to
attenuation of flow disturbances. And then the liquid flows into
the liquid oscillating chamber through the oscillating chamber
inlet port. The liquid flowing in the liquid oscillating chamber
passes through the nozzle inlet opening and is jetted, as the jet
liquid column, from the nozzle. On the other hand, the laser beam
generated by the laser oscillator passes through the window opposed
to the nozzle inlet opening to enter the liquid oscillating
chamber, and is focused above the nozzle inlet opening by the
focusing optical system. Thus, the laser beam is guided by the jet
liquid column. Also, the liquid oscillating chamber increases the
surface wave on the outer surface of the jet liquid column, thereby
causing the jet liquid column jetted from the nozzle onto the
workpiece to be easily atomized at the machining point.
[0012] The jet liquid column, after reaching the workpiece, is
immediately atomized, and therefore the disturbances given to the
jet liquid column due to the liquid splashed back from the
workpiece can be suppressed. Also, since the liquid is less likely
to be accumulated in the machining point on the workpiece,
interference with light guiding due to the accumulated liquid can
be suppressed. This allows efficient machining of the
workplace.
[0013] In the aspect of the invention, preferably, the oscillating
chamber inlet port is disposed such that the liquid flows in from
one side of a sidewall of the liquid oscillating chamber
surrounding the nozzle inlet opening. With this structure, an
appropriate liquid flow is caused in the vicinity of the window,
and consequently attachment of foreign material to the window due
to the laser trapping phenomenon can be prevented.
[0014] In the aspect of the invention, preferably, the liquid
oscillating chamber has a height in the range of about 20 to 300
times a diameter of the nozzle inlet opening, and a width in the
range of about 15 to 200 times the diameter of the nozzle inlet
opening. With this structure, the liquid oscillating chamber
effectively oscillates the liquid and can form the sufficient
surface wave on the jet liquid column. Therefore, the jet liquid
column can be immediately atomized.
[0015] In the aspect of the invention, preferably, the rectifying
chamber has an annular shape that surrounds at least a portion of
the liquid oscillating chamber. This structure allows attenuation
of the liquid flow in small space, thereby allowing a reduction in
size of the laser machining apparatus.
[0016] In the aspect of the invention, preferably, the liquid
oscillating chamber has a generally cylindrical shape with a height
greater than its diameter. With this structure, the liquid
oscillating chamber effectively oscillates the liquid and can form
the sufficient surface wave on the jet liquid column. Therefore,
the jet liquid column can be immediately atomized.
[0017] In the aspect of the invention, preferably, the liquid
oscillating chamber is provided in the sidewall thereof with an
air-bleeding hole separately from the oscillating chamber inlet
port. With this structure, since the air-bleeding hole is provided
on the opposite side of the oscillating chamber inlet port,
accumulated air in the liquid oscillating chamber is forced out by
the liquid flowing from the oscillating chamber inlet port, and
thus the air can be quickly discharged.
[0018] In the aspect of the invention, preferably, the laser
machining apparatus further includes a workpiece holder for holding
the workpiece. The workpiece holder allows movement of the
workpiece in a direction of an X-axis, movement of the workpiece in
a direction of a Y-axis perpendicular to the X-axis, and rotation
of the workpiece about respective axes parallel to the directions
of the X- and Y-axes to be simultaneously performed, for flexible
machining in three-dimensional space.
[0019] This structure allows the workpiece to move with a high
degree of flexibility during machining, thereby allowing a very
wide range of machining and an increase in machining accuracy.
Also, accumulation of liquid in the vicinity of the machining point
can be suppressed by moving the workpiece during machining.
[0020] In the aspect of the invention, preferably, the laser
machining apparatus further includes a workpiece holder for holding
the workpiece. The workpiece holder allows movement of the
workpiece in a direction of an X-axis, movement of the workpiece in
a direction of a Y-axis perpendicular to the X-axis, and rotation
of the workpiece to be simultaneously performed, for flexible
machining in three-dimensional space.
[0021] This structure allows the workpiece to move in the
directions of the X- and Y-axes while rotating the workpiece during
machining. Also, accumulation of liquid in the vicinity of the
machining point can be further suppressed by rotating the workpiece
at high speed during machining.
[0022] In the aspect of the invention, preferably, the focusing
optical system focuses the laser beam toward the window with
respect to the nozzle inlet opening for causing a portion of the
laser beam to strike a flow contracting portion at which the jet
liquid column is formed and further increasing the surface wave on
the outer surface of the jet liquid column.
[0023] With this structure, a portion of the laser beam strikes the
jet liquid column at the flow contracting portion in the vicinity
of the nozzle inlet opening, thereby giving a disturbance to the
jetted jet liquid column. This disturbance excites the surface wave
on the jet liquid column and thereby allows a further increase in
size of the surface wave, so that the jet liquid column after
reaching the workpiece can be immediately atomized.
[0024] In the aspect of the invention, preferably, the laser
machining apparatus further includes a mist jet injector for
directing a mist jet on a workpiece surface to remove residues
generated by machining. With this structure, machining dust
generated by machining of the workpiece can be removed from the
machining point, thereby allowing elimination of residues on the
surface of the workpiece.
[0025] In the aspect of the invention, preferably, the laser
machining apparatus further includes an oscillating chamber inlet
path for guiding the liquid from the rectifying chamber to the
oscillating chamber inlet port. The oscillating chamber inlet path
guides the liquid along the window from one side of the liquid
oscillating chamber to the oscillating chamber inlet port.
[0026] With this structure, since foreign material in the liquid
can be washed out by the liquid flow along the window, attachment
of foreign material to the window can be prevented.
[0027] In the aspect of the invention, preferably, the laser
machining apparatus further includes an oscillating chamber inlet
path adjusting member defining a form of the oscillating chamber
inlet path. The surface wave on the outer surface of the jet liquid
column is adjusted in size by changing the oscillating chamber
inlet path adjusting member.
[0028] With this structure, the jet liquid column can be
appropriately atomized depending on objects to be machined, thereby
allowing machining of a wide range of objects to be machined with
the laser machining apparatus of the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] Embodiments of the present invention will be described in
detail based on the following drawings, wherein:
[0030] FIG. 1 is a sectional view of a head of a laser machining
apparatus according to a first embodiment of the present
invention;
[0031] FIG. 2 is a perspective view illustrating a section taken
along line II-II of FIG. 1;
[0032] FIGS. 3A to 3C are top plan, sectional side, and bottom
views, respectively, of a liquid oscillating chamber forming
member;
[0033] FIGS. 4A to 4C illustrate states of a jet liquid column
jetted from a nozzle;
[0034] FIGS. 5A and 5B are enlarged views of a laser beam
introduced into the jet liquid column through an inlet opening of
the nozzle;
[0035] FIGS. 6A and 6B are top plan and front views, respectively,
of a liquid oscillating chamber forming member incorporated in a
laser machining apparatus according to a second embodiment of the
present invention;
[0036] FIG. 7 illustrates a laser machining apparatus according to
a third embodiment of the present invention;
[0037] FIG. 8 illustrates a laser machining apparatus according to
a fourth embodiment of the present invention;
[0038] FIG. 9 illustrates a laser machining apparatus according to
a fifth embodiment of the present invention;
[0039] FIG. 10 is a sectional view of a head of a laser machining
apparatus according to a sixth embodiment of the present
invention;
[0040] FIG. 11 is a perspective view illustrating a section taken
along line XI-XI of FIG. 10;
[0041] FIG. 12 is a perspective view illustrating the forms of a
liquid oscillating chamber, an oscillating chamber inlet path, and
a rectifying chamber which are formed within the head of the laser
machining apparatus; and
[0042] FIGS. 13A to 13C are plan views of oscillating chamber inlet
path adjusting members according to the sixth embodiment, a first
modification, and a second modification of the present
invention.
DETAILED DESCRIPTION
[0043] Next, referring to FIGS. 1 to 5B, a laser machining
apparatus according to a first embodiment of the present invention
will be described.
[0044] As shown in FIG. 1, a laser machining apparatus 1 according
to the first embodiment of the present invention has: a laser
machining head 2; a laser oscillator 4 for transmitting a laser
beam to the laser machining head 2; a focusing optical system 6 for
focusing the laser beam transmitted from the laser oscillator 4;
and a liquid supply source 8 for supplying water, serving as the
liquid, to the laser machining head 2. Also, the liquid delivered
from the liquid supply source 8 is supplied to the laser machining
head 2 through a liquid processor 10, a high-pressure pump 12, and
a high-pressure filter 14.
[0045] Furthermore, as shown in FIG. 1, the laser machining head 2
has a head body 16, a nozzle 20, a window 22, and a liquid
oscillating chamber forming member 24. The laser oscillator 4
generates a laser beam having a predetermined strength. In this
embodiment, a green laser is used as the laser beam; however, any
kind of laser beam that is less absorbable by water may be
arbitrarily selected.
[0046] A typical green laser is the second harmonic of a YAG laser
fundamental wave (wavelength 1064 nm) and has a wavelength of 532
nm. Unlike the YAG laser fundamental wave (wavelength 1064 nm) and
the CO.sub.2 laser (wavelength 10.6 .mu.m), the green laser has a
property being less absorbable by water. Therefore, when water
easily available at a cheaper cost is used as the jet liquid, the
propagation efficiency of the laser can be increased.
[0047] The focusing optical system 6 focuses the laser beam
generated by the laser oscillator 4 to a predetermined position.
The laser beam emitted from the laser oscillator 4 is introduced
into the laser machining head 2 through optical fibers or the like
(not shown) and converted to a parallel beam by a collimating lens
(not shown). And then the beam is focused on the axis of the nozzle
20 in the laser machining head 2 by a condensing lens. It should be
noted that, in FIG. 1, only one condensing lens, which is a portion
of the focusing optical system 6, is shown by reference sign "6" as
the focusing optical system 6.
[0048] The liquid supply source 8 supplies water serving as the
liquid to be jetted from the nozzle 20. The liquid processor 10
performs processing such as deionization of the liquid supplied
from the liquid supply source 8. The high-pressure pump 12
pressurizes the liquid having undergone the liquid processor 10 and
delivers the high-pressure liquid to the laser machining head 2.
Also, the high-pressure filter 14 removes foreign material or the
like from the liquid pressurized by the high-pressure pump 12. The
water having undergone the high-pressure filter 14 is introduced
into the laser machining head 2. It should be noted that, in this
embodiment, water is pressurized to a pressure in the range of from
10 to 30 MPa by the high-pressure pump 12 to be introduced into the
laser machining head 2.
[0049] The head body 16 is a shouldered, generally cylindrical
member and allows the laser beam transmitted from the laser
oscillator 4 to pass through the inside thereof. Also, the head
body 16 is attached at its recessed shoulder with the condensing
lens 6 so that the laser beam from the laser oscillator 4 is
focused by the condensing lens 6. In addition, a cylindrical window
receiving recess 16a for receiving the window 22 is formed within
the head body 16, and the window 22 is disposed within the window
receiving recess 16a. The laser exiting from the condensing lens 6
passes through the window 22 to be focused in the vicinity of an
inlet opening of a nozzle hole.
[0050] The window 22 is a columnar member that allows a laser beam
to pass through, and may be made of quartz, sapphire or the like.
Also, a seal is disposed around the window 22 to ensure the
water-tightness between the window receiving recess 16a and the
window 22.
[0051] Also, the liquid oscillating chamber forming member 24 is
disposed below the window 22. The liquid oscillating chamber
forming member 24 is built in the head body 16. The window 22 is
fixed in such a manner as to be held between the liquid oscillating
chamber forming member 24 and the window receiving recess 16a (see
FIG. 1).
[0052] A nozzle receiving recess 16b for receiving the nozzle 20 is
formed at a lower portion of the head body 16, and the nozzle 20 is
disposed within the nozzle receiving recess 16b. Internal threads
are formed in the inner circumference of a lower end of the head
body 16. The internal threads engage external threads that are
formed in the outer circumference of a nozzle holding member 28,
thereby fixing the nozzle 20 within the nozzle receiving recess
16b. Also, a seal is disposed around the nozzle 20 to ensure the
water-tightness between the head body 16 and the nozzle 20.
[0053] Moreover, a liquid feed path 16c is formed in a side surface
of the head body 16. The liquid feed path 16c is a substantially
horizontally extending liquid path through from the outside to the
inside of the head body 16. The liquid feed path 16c allows the
liquid supplied from the liquid supply source 8 to flow into the
laser machining head 2 through the liquid feed path 16c. The liquid
flowing in through the liquid feed path 16c enters a generally
annular space in the head body 16. The annular space attenuates
disturbances in the liquid supplied from the liquid feed path 16c,
and therefore serves as a rectifying chamber 30 (see FIG. 2).
Furthermore, the liquid flows into a liquid oscillating chamber 24c
from the rectifying chamber 30 through an oscillating chamber inlet
port 24b.
[0054] Next, the nozzle 20 is a generally columnar member, and
formed on its central axis with a nozzle hole 20a of circular cross
section. The liquid in the liquid oscillating chamber 24c flows
into the nozzle hole 20a through the nozzle inlet opening located
at a top end of the nozzle hole 20a, and is jetted, as a jet liquid
column J, from the nozzle 20. It should be noted that, in this
embodiment, the diameter of the nozzle hole 20a (the nozzle inlet
opening) is about 60 .mu.m, however, may be arbitrarily changed
depending on objects to be machined, etc.
[0055] Next, referring to FIGS. 3A to 3C, the structure of the
liquid oscillating chamber forming member 24 will be described in
detail. As shown in FIG. 3B, the liquid oscillating chamber forming
member 24 is a generally cylindrical member, and disposed within
the head body 16 so as to form on its outer side the rectifying
chamber 30, and on its inner side the cylindrical liquid
oscillating chamber 24c. In other words, the inner peripheral
surface of the liquid oscillating chamber forming member 24 forms
the sidewall of the liquid oscillating chamber 24c which surrounds
the nozzle inlet opening. Also, the rectifying chamber 30 is formed
as an annular space that surrounds the liquid oscillating chamber
24c around the liquid oscillating chamber forming member 24.
[0056] Also, as shown in FIGS. 3A and 3B, a window abutting surface
24d that abuts on the window 22 is formed at the top end of the
liquid oscillating chamber forming member 24. With the window
abutting surface 24d abutting on the lower end surface of the
window 22, the window 22 is positioned.
[0057] Furthermore, a lower end surface 24e of the liquid
oscillating chamber forming member 24 abuts on the top end surface
of the nozzle 20, and an inclined surface 24f at a lower portion of
the liquid oscillating chamber forming member 24 abuts on an inner
wall surface of the head body 16. In this manner, with the window
abutting surface 24d abutting on the window 22 and the lower end
surface 24e abutting on the nozzle 20, the cylindrical liquid
oscillating chamber 24c is defined by the lower end surface of the
window 22, the top end surface of the nozzle 20, and the inner
peripheral surface of the liquid oscillating chamber forming member
24. In this embodiment, the defined liquid oscillating chamber 24c
is 6 mm in height and 5 mm in diameter, and is formed in a
cylindrical shape having a height greater than the diameter.
Preferably, the liquid oscillating chamber 24c has a height in the
range of from 20 to 300 times the diameter of the nozzle hole (the
nozzle inlet opening) and a diameter in the range of from 15 to 200
times the diameter of the nozzle hole (the nozzle inlet opening),
the height of the liquid oscillating chamber 24c being set to be
greater than the width.
[0058] Furthermore, as shown in FIG. 3C, the sidewall of the liquid
oscillating chamber forming member 24 is provided with a notch with
a central angle of approximately 90.degree.. The notch allows
communication between the outer peripheral side and inside of the
liquid oscillating chamber forming member 24, and therefore serves
as an oscillating chamber inlet path 24h and the oscillating
chamber inlet port 24b which allow communication between the
rectifying chamber 30 and the liquid oscillating chamber 24c. More
specifically, the oscillating chamber inlet path 24h is a path that
is tapered from the rectifying chamber 30 to the liquid oscillating
chamber 24c, and the oscillating chamber inlet port 24b is an
opening for connection between the oscillating chamber inlet path
24h provided in the sidewall of the liquid oscillating chamber 24c
and the liquid oscillating chamber 24c. Thus, the supplied liquid
flows through the oscillating chamber inlet path 24h from the
rectifying chamber 30 and enters the liquid oscillating chamber 24c
through the oscillating chamber inlet port 24b. In this manner,
liquid flows into the liquid oscillating chamber 24c from one side
of the sidewall of the liquid oscillating chamber 24c.
[0059] Also, as shown in FIG. 3B, the liquid oscillating chamber
forming member 24 is formed at a sidewall thereof with an
air-bleeding hole 24g through from the liquid oscillating chamber
24c to an outer peripheral surface of the liquid oscillating
chamber forming member 24, separately from the oscillating chamber
inlet port 24b. The air-bleeding hole 24g is a small hole with
circular cross section having a cross-sectional area smaller than
the oscillating chamber inlet port 24b, and opposed to the
oscillating chamber inlet port 24b. During operation of the laser
machining apparatus 1, all of the liquid in the rectifying chamber
30 flows into the liquid oscillating chamber 24c through the
oscillating chamber inlet port 24b because the air-bleeding hole
24g is increased in flow resistance.
[0060] Next, referring additionally to FIGS. 4A to 5B, the
operation of the laser machining apparatus 1 according to the first
embodiment of the present invention will be described. Upon
start-up of the laser machining apparatus 1, firstly, the
high-pressure pump 12 is activated. Thus, liquid is supplied to the
high-pressure pump 12 from the liquid supply source 8 through the
liquid processor 10. The liquid pressurized by the high-pressure
pump 12 is fed into the liquid feed path 16c through the
high-pressure filter 14. The liquid having flowed into the laser
machining head 2 through the liquid feed path 16c passes through
the rectifying chamber 30 and flows into the liquid oscillating
chamber 24c through the oscillating chamber inlet port 24b. Here,
at the time of startup of the laser machining apparatus 1,
accumulated air in the liquid oscillating chamber 24c is discharged
to the outside of the liquid oscillating chamber 24c through the
air-bleeding hole 24g opposed to the oscillating chamber inlet port
24b. The air discharged out of the liquid oscillating chamber 24c
is discharged to the outside of the laser machining head 2 through
an air-bleeding path 16d (see FIG. 1). The air-bleeding path 16d is
connected to a valve (not shown). When the valve is closed after
discharge of air to the outside, the liquid oscillating chamber
24c, the rectifying chamber 30 and the like are filled with liquid.
All of the liquid introduced from the liquid feed path 16c is
jetted, as the jet liquid column J, from the nozzle hole 20a. In
this state, the liquid in the rectifying chamber 30 flows into the
liquid oscillating chamber 24c exclusively from one direction
(i.e., the oscillating chamber inlet port 24b) to be jetted through
the nozzle hole 20a. The liquid, after being rectified in the
rectifying chamber 30, flows into the liquid oscillating chamber
24c from one direction and is oscillated, so that an appropriate
disturbance is given to the liquid flow.
[0061] Next, the laser oscillator 4 is activated to generate a
laser beam. The generated laser beam is condensed by the condensing
lens 6 and passes through the window 22 to be focused on the
central axis above the nozzle hole 20a (the nozzle inlet opening)
within the liquid oscillating chamber 24c. The focused laser beam
enters the inside of the jet liquid column J jetted from the nozzle
hole 20a and is guided while repeating total reflection within the
jet liquid column J to reach a workpiece W. The laser beam having
reached the workpiece W machines the workpiece W.
[0062] FIGS. 4A to 4C illustrate in schematic form the states of
the jet liquid column J jetted from the nozzle 20, wherein FIG. 4A
illustrates a state of the jet liquid column J jetted into the air.
FIGS. 4B and 4C illustrate states in which the jet liquid column J
strikes the workpiece W to machine the workpiece W, wherein FIG. 4B
illustrates a state in the process of cutting the workpiece W, and
FIG. 4C illustrates a state of the jet liquid column J passing
through the workpiece W. As shown in FIG. 4, the liquid jetted from
the nozzle 20 is jetted with a surface wave 32 formed on an outer
surface of the jetted liquid column J. The surface wave 32
gradually increases in amplitude in the direction away from the
nozzle 20, and finally, the liquid on a liquid column surface is
partially separated, as droplets 34, from the liquid column J.
Furthermore, the droplets 34 separated from the liquid column J
increase gradually in number in the direction away from the nozzle
20, and finally, a body of the liquid column J is also separated
into liquid masses 36 larger than the droplets 34, so that the
liquid column J disappears.
[0063] To guide a laser beam with the jet liquid column J, it is
necessary to cause the jet liquid column J to reach the workpiece W
with almost no droplets 34 generated so that the laser beam is
totally reflected within the jet liquid column J. Therefore, as for
the laser-guiding function, preferably, the jet liquid column J
reaches the workpiece W with the surface wave 32 small and no
droplets 34 generated. However, actually, when the jet liquid
column J reaches the workpiece W with the surface wave 32 small,
the liquid splashed back from the workpiece W gives a disturbance
to the jet liquid column J, rather, resulting in interference with
light guiding. In particular, in the case of the workpiece W
requiring multiple scanning of the jet liquid column J in order for
the completion of cutting, the influence of the disturbance due to
the liquid splashed back from the workpiece W is increased. In
other words, in the case of cutting with multiple scanning,
machining is performed in the state in which the machining point on
the workpiece W is not pierced. Therefore, jetted liquid is not
discharged downwardly of the workpiece W, and consequently, all of
the jetted liquid is splashed back to the jet liquid column J,
thereby giving a disturbance to the jet liquid column J.
[0064] Here, the laser machining apparatus 1 of this embodiment is
constructed such that the jet liquid column J strikes the workpiece
W after the surface wave 32 of the jet liquid column J jetted from
the nozzle 20 has become larger to some extent. For this reason, as
shown in FIG. 4B, when the jet liquid column J strikes the
workpiece W, the splashed-back water is atomized, thereby hardly
affecting the jet liquid column J even in the state in which the
machining point is not pierced. Also, as shown in FIG. 4C, in the
state in which the machining point is pierced, most of the jetted
liquid is discharged downwardly of the workpiece W, thereby further
reducing the influence of the splashed-back water.
[0065] In the laser machining apparatus 1 of this embodiment,
liquid is allowed to flow into the nozzle hole 20a through the
liquid oscillating chamber 24c, thereby giving an appropriate
disturbance to the liquid flow. Thus, an appropriate surface wave
is excited on the surface of the jet liquid column J jetted from
the nozzle 20. The surface wave 32 grows to an appropriate size
before reaching the vicinity of the workpiece W. In this manner,
when the jet liquid column J strikes the workpiece W after the
surface wave 32 has grown to an appropriate size, the jet liquid
column J is immediately atomized, and therefore a disturbance is
less likely to be given to the jet liquid column J. Also, when the
jet liquid column J is atomized, the jetted liquid is immediately
dispersed from the vicinity of the machining point on the workpiece
W. Therefore, liquid is less likely to be accumulated in the
vicinity of the machining point, so that interference with light
guiding due to the accumulated liquid is suppressed. On the other
hand, in the related art laser machining apparatus in which the jet
liquid column J strikes the workpiece W with the surface wave 32
small, the liquid having struck the workpiece W is likely to be
accumulated in the vicinity of a machining point on the workpiece
W, the accumulated liquid interfering with laser guiding. Compared
with this, in the laser machining apparatus 1 of this embodiment,
even in the case of deep hole formation, since the liquid atomized
at the machining point rises easily from inside a hole during
machining, the liquid accumulated inside the hole is reduced.
[0066] In the laser machining apparatus 1 according to this
embodiment, after liquid flow disturbances have been attenuated in
the rectifying chamber 30, the liquid is introduced into the liquid
oscillating chamber 24c, and the jet liquid column J is jetted
therefrom through the nozzle 20. Thus, the appropriate surface wave
is given to the jetted jet liquid column J, and thus the liquid is
atomized immediately after the jet liquid column J strikes the
workpiece W. It should be noted that, in the laser machining
apparatus 1 of this embodiment, the distance between the lower end
surface of the nozzle 20 and the workpiece W is set to be in the
range of about 5 to 40 mm, thereby allowing efficient guiding of
the laser beam to the workpiece W and atomizing the jet liquid
column J having struck the workpiece W, so that favorable machining
can be performed.
[0067] Next, referring to FIGS. 5A and 52, introduction of the
laser beam into the jet liquid column J will be described. FIG. 5A
illustrates the state where a laser beam is introduced into the jet
liquid column J in a general apparatus for guiding the laser beam
with the jet liquid column J. FIG. 5B illustrates the state where a
laser beam is introduced into the jet liquid column J in the laser
machining apparatus 1 of this embodiment.
[0068] As shown in FIGS. 5A and 5B, liquid flows into the nozzle
hole 20a through the nozzle inlet opening located at the top end
surface of the nozzle 20 to be jetted as the jet liquid column J.
Here, contraction flow occurs when the liquid flows into the nozzle
inlet opening. Thus, the diameter of the jetted jet liquid column J
becomes slightly smaller than that of the nozzle inlet opening.
[0069] As shown in FIG. 5A, in general apparatuses, the laser beam
is focused at the center point of the circle of the nozzle inlet
opening. The laser beam, expanding downward from the focusing
point, strikes the boundary surface between the jet liquid column J
and outside air, and then is guided while repeating total
reflection within the jet liquid column J. On the other hand, in
the laser machining apparatus 1 of this embodiment, the laser beam
is focused above the nozzle inlet opening, that is, toward the
window 22 with respect to the nozzle inlet opening. The laser beam
focused above the nozzle inlet opening expands downward and strikes
the jet liquid column J at a flow contracting portion C in the
vicinity of the nozzle inlet opening, and then is guided while
repeating total reflection within the jet liquid column J. In this
manner, the laser beam gives a disturbance to the jetted jet liquid
column J by causing the laser beam to strike the vicinity of the
flow contracting portion C at which the jet liquid column J is
formed. This disturbance excites the surface wave 32 on the jet
liquid column J, and thereby allows a further increase in size of
the surface wave 32, so that the liquid can be immediately atomized
after the jet liquid column J has reached the workpiece W.
[0070] Also, in the related art laser machining apparatus, purified
water is used as the liquid, and the liquid is pressurized by a
high-pressure pump and then supplied through a high-pressure
filter. However, there has been a problem in that slight dirt and
oil eluted from the pump, pipes and the like by purified water
collect on a window and are attached to a surface of the window.
This is due to the optical tweezers principle (also called the
laser trapping phenomenon) in which, when a strong laser beam
passes through the window, dirt, oil, etc. in the water adjacent to
the window are attracted to the window surface by the strong laser
beam. In particular, the related art laser machining apparatus is
constructed such that liquid flows axisymmetrically toward the
center from the periphery of a liquid accumulation chamber that is
provided for supplying liquid to the nozzle. Therefore, a
stagnation point occurs in the center of the liquid accumulation
chamber, the liquid flow speed in the vicinity thereof is greatly
reduced. For this reason, dirt, oil, etc. in the water in the
vicinity of the window surface are attracted and attached to the
window.
[0071] On the other hand, with the laser machining apparatus 1 of
this embodiment, since liquid flows into the liquid oscillating
chamber 24c from one direction, liquid flows at a certain constant
speed over the whole surface of the window 22. Thus, dirt, oil,
etc. in the water are less likely to be attached to the window 22.
Even if dirt, oil, etc. are attached to the window 22, they are
immediately washed out by newly supplied liquid, and therefore
attachment of impurities in the liquid to the window 22 can be
suppressed.
[0072] Next, referring to FIGS. 6A and 6B, a laser machining
apparatus according to a second embodiment of the present invention
will be described. The laser machining apparatus of this embodiment
differs from that of the above-described first embodiment in the
shape of a liquid oscillating chamber forming member. Therefore,
only the differences between these embodiments will be described
hereinafter, and the description of the same construction,
operation, and advantages will not be repeated.
[0073] As shown in FIGS. 6A and 6B, a liquid oscillating chamber
forming member 40 in this embodiment is formed in a generally
cylindrical shape with an outside diameter of 8 mm, an inside
diameter of 3.5 mm, and a height of 4 mm. Also, the liquid
oscillating chamber forming member 40 is disposed with a top end
surface 40d thereof abutting on the lower end surface of the window
22 and a lower end surface 40e abutting on the top end surface of
the nozzle 20. Consequently, a liquid oscillating chamber 40c
defined by the liquid oscillating chamber forming member 40 is of a
columnar shape with a diameter of 3.5 mm and a height of 4 mm.
Also, the generally cylindrical liquid oscillating chamber forming
member 40 is partially provided with a notch. The notch forms an
oscillating chamber inlet path 40f and an oscillating chamber inlet
port 40b. The oscillating chamber inlet path 40f and the
oscillating chamber inlet port 40b are each 3 mm in height, the top
end surfaces thereof being defined by the lower end surface of the
window 22. Also, the oscillating chamber inlet path 40f is tapered
in width with a taper angle of 30.degree. from the outer periphery
to the inner periphery, and connected to the liquid oscillating
chamber 40c through the innermost oscillating chamber inlet port
40b. Also, the width of the oscillating chamber inlet port 40b is
the same as the diameter of the liquid oscillating chamber 40c,
that is, 3.5 mm.
[0074] In the second embodiment constructed in this manner, the
liquid oscillating chamber 40c is small, and liquid in the
rectifying chamber 30 flows into the liquid oscillating chamber 40c
from one direction above the liquid oscillating chamber 40c.
Therefore, the flow speed on the upper side in the liquid
oscillating chamber 40c increases, thereby strongly oscillating the
liquid and allowing generation of a strong surface wave on the jet
liquid column J. Thus, as shown in FIG. 5B, the sufficiently strong
surface wave can be provided without causing a laser beam to strike
the flow contracting portion C, and the jet liquid column J having
struck the workpiece W can be sufficiently atomized by just
oscillation with the liquid oscillating chamber 40c.
[0075] Next, referring to FIG. 7, a laser machining apparatus
according to a third embodiment of the present invention will be
described. The laser machining apparatus of this embodiment differs
from that of the above-described first embodiment in a workpiece
holder for holding the workpiece W. Therefore, only the differences
between these embodiments will be described hereinafter, and the
description of the same construction, operation, and advantages
will not be repeated.
[0076] As shown in FIG. 7, the laser machining apparatus of this
embodiment includes a workpiece holder 50 that is disposed below
the laser machining head 2. The workpiece holder 50 has an XY table
52, a bearing 54 provided on the XY table 52, a joint cross 56
supported by the bearing 54, a tilting rotary table 58 supported by
the joint cross 56, and a clamp 59 for fixing the workpiece W to
the tilting rotary table 58.
[0077] The XY table 52 can be translated in the directions of X-
and Y-axes perpendicular to each other in the horizontal plane. The
bearing 54 is fixed on the XY table 52 and supports the joint cross
56 rotatably about an axis (B-axis) parallel to the YX table 52.
The joint cross 56 is a cross-like shaft that is composed of an
integrated combination of a first shaft rotatably supported by the
bearing 54 and a second shaft perpendicular to the first shaft.
Also, the first shaft of the joint cross 56 is parallel to the
direction of the Y-axis.
[0078] The tilting rotary table 58 is rotatably attached to the
second shaft of the joint cross 56. The tilting rotary table 58 is
rotatable about the second shaft (A-axis) of the joint cross 56.
Also, the second shaft of the joint cross 56 is parallel to the
direction of the X-axis. The clamp 59 is provided on the tilting
rotary table 58 for removably fixing the workpiece W to the tilting
rotary table 58. Also, the laser machining head 2 can be vertically
translated.
[0079] The laser machining apparatus of this embodiment allows the
workpiece W to be translated in the directions of the X- and Y-axes
during machining and rotate about the A- and B-axes, and can
perform the translation and rotation simultaneously. Thus, the
workpiece W can be moved with a high degree of flexibility in
three-dimensional space, thereby allowing a very wide range of
machining and an increase in machining accuracy. Also, with the
laser machining apparatus of this embodiment, accumulation of
liquid in the vicinity of the machining point can be suppressed by
moving the workpiece W during machining.
[0080] Next, referring to FIG. 8, a laser machining apparatus
according to a fourth embodiment of the present invention will be
described. The laser machining apparatus of this embodiment differs
from that of the above-described first embodiment in a workpiece
holder for holding the workpiece W. Therefore, only the differences
between these embodiments will be described hereinafter, and the
description of the same construction, operation, and advantages
will not be repeated.
[0081] As shown in FIG. 8, the laser machining apparatus of this
embodiment includes a workpiece holder 60 that is disposed below
the laser machining head 2. The workpiece holder 60 has an XY table
62, a rotary drive unit 64 provided on the XY table 62, a rotary
table 66 supported by the rotary drive unit 64, and a clamp 68 for
fixing the workpiece W to the rotary table 66.
[0082] The rotary drive unit 64 is a motor provided on the XY table
62 to rotatably drive the rotary table 66. The rotary table 66 is
rotated about a vertical axis (C-axis) by the rotary drive unit 64.
The clamp 68 is provided on the rotary table 66 for removably
fixing the workpiece W to the rotary table 66. The laser machining
head 2 can be translated in the direction of a Z-axis. Also, the
laser machining head 2 may be constructed to be tiltable with
respect to the direction of the Z-axis.
[0083] The laser machining apparatus of this embodiment allows the
workplace W to be translated in the directions of the X- and Y-axes
during machining and rotate, and can perform the translation and
rotation simultaneously. The laser machining apparatus of this
embodiment allows flexible machining in three-dimensional space,
and further facilitates control of the workpiece holder relative to
the laser machining apparatus according to the above-mentioned
third embodiment, thereby allowing the workplace W to move faster.
Also, taper machining can be applied to the workpiece W by tilting
the laser machining head 2 with respect to the workpiece W.
Furthermore, with the laser machining apparatus of this embodiment,
accumulation of liquid in the vicinity of the machining point can
be further suppressed by rotating the workpiece W at high speed
during machining.
[0084] Next, referring to FIG. 9, a laser machining apparatus
according to a fifth embodiment of the present invention will be
described. The laser machining apparatus of this embodiment differs
from that of the above-described first embodiment in that a mist
jet injector for directing a mist jet at a machining point on the
workpiece W is provided. Therefore, only the differences between
these embodiments will be described hereinafter, and the
description of the same construction, operation, and advantages
will not be repeated. As shown in FIG. 9, the laser machining
apparatus of this embodiment has an XY table 70 that is disposed
below the laser machining head 2, and a mist jet injector 72 that
directs a mist jet at a machining point on the workpiece W on the
XY table 70.
[0085] The XY table 70 can be translated in the directions of X-
and Y-axes perpendicular to each other in the horizontal plane. The
mist jet injector 72 atomizes water with high-speed airflow to
direct a mist jet at the machining point on the workpiece W. The
mist jet removes machining dust generated by machining of the
workpiece W from the machining point. Thus, residues on the surface
of the workpiece W can be eliminated.
[0086] Next, referring to FIGS. 10 to 13C, a laser machining
apparatus according to a sixth embodiment of the present invention
will be described. The laser machining apparatus of this embodiment
differs from that of the above-described first embodiment in the
forms of a liquid oscillating chamber, an oscillating chamber inlet
path, and an oscillating chamber inlet port. Therefore, only the
differences between these embodiments will be described
hereinafter, and the description of the same construction,
operation, and advantages will not be repeated.
[0087] As shown in FIG. 10, a laser machining apparatus 100
according to the sixth embodiment of the present invention has a
laser machining head 102, a laser oscillator 104 for transmitting a
laser beam to the laser machining head 102, and a focusing optical
system 106 for focusing the laser beam transmitted from the laser
oscillator 104. Also, water is supplied to the laser machining head
102 from a liquid supply source (not shown) through a liquid
processor, a high-pressure pump, and a high-pressure filter (which
are not shown). Furthermore, as shown in FIG. 10, the laser
machining head 102 has a head body 116, a nozzle 120, a window 122,
and an oscillating chamber inlet path adjusting member 124.
[0088] The oscillating chamber inlet path adjusting member 124 is
disposed below the window 122. The oscillating chamber inlet path
adjusting member 124 is built in the head body 116. The window 122
is fixed in such a manner as to be held between the oscillating
chamber inlet path adjusting member 124 and a window receiving
recess 116a (see FIG. 10).
[0089] A circular tray-shaped space extending downward from an
annular rectifying chamber 130 is formed within the head body 116.
The oscillating chamber inlet path adjusting member 124 is disposed
within the space, thereby defining the form of an oscillating
chamber inlet path 116d. Also, the head body 116 is formed with a
cylindrical bore extending downward from the center of the circular
tray-shaped space, the inside of the bore serving as a liquid
oscillating chamber 126.
[0090] Also, as shown in FIG. 10, an air-bleeding path 116e is
formed on the opposite side of a liquid feed path 116c. The
air-bleeding path 116e extends substantially horizontally on the
opposite side of the liquid feed path 116c. The air-bleeding path
116e is a path for discharging accumulated air in the rectifying
chamber 130 or the like at the time of initial use of the laser
machining apparatus 100 and is closed by a valve not shown) at the
time of actual use of the laser machining apparatus 100.
[0091] Next, referring to FIGS. 11 and 12, the structures of the
liquid oscillating chamber 126 and the oscillating chamber inlet
path 116d will be described in detail. FIG. 12 is a perspective
view three-dimensionally illustrating the forms of the liquid
oscillating chamber 126, the oscillating chamber inlet path 116d,
and the rectifying chamber 130 which are formed as cavities within
the head body 116.
[0092] As shown in FIG. 11, the oscillating chamber inlet path
adjusting member 124 is shaped to conform to the circular
tray-shaped space formed within the head body 116. The oscillating
chamber inlet path adjusting member 124 has a shape in which a
fan-shaped portion with a central angle of approximately 90.degree.
is cut away from the circular tray shape. The oscillating chamber
inlet path adjusting member 124 is disposed within the circular
tray-shaped space formed within the head body 116, and thus the
remaining space serves as the oscillating chamber inlet path 116d.
In other words, as shown in FIG. 12, a portion of the circular
tray-shaped space formed so as to communicate with the annular
rectifying chamber 130 is closed by the oscillating chamber inlet
path adjusting member 124, thereby forming the oscillating chamber
inlet path 116d extending horizontally and having the fan shape
with an angle of approximately 90.degree..
[0093] Furthermore, the cylindrical liquid oscillating chamber 126
is formed in a manner communicating with the oscillating chamber
inlet path 116d. The liquid oscillating chamber 126 is formed in a
downwardly extending manner on the central axis of the annular
rectifying chamber 130. Also, as shown in FIG. 10, the sidewall of
the liquid oscillating chamber 126 is constructed of the inner
peripheral surface of the cylindrical bore formed within the head
body 116. The bottom of the liquid oscillating chamber 126 is
constructed of the top end surface of the nozzle 20. Also, the top
end of the liquid oscillating chamber 126 communicates with the
oscillating chamber inlet path 116d through a circular oscillating
chamber inlet port 126a. Thus, supplied liquid flows along the
window 122 through the oscillating chamber inlet path 116d from one
side of the liquid oscillating chamber 126 and passes through the
oscillating chamber inlet port 126a into the liquid oscillating
chamber 126.
[0094] It should noted that, in this embodiment, the liquid
oscillating chamber 126 is about 4.2 mm in diameter and about 4.5
mm in height, and has a cylindrical shape with a height greater
than the diameter. Also, the approximately-fan-shaped oscillating
chamber inlet path 116d is about 1.5 mm in height. The distance
from the top end surface of the nozzle 120 to the lower end surface
of the window 122 is about 6 mm. Preferably, the liquid oscillating
chamber 126 has a height in the range of from 20 to 300 times the
diameter of the nozzle hole (the nozzle inlet opening) and a
diameter in the range of from 15 to 200 times the diameter of the
nozzle hole (the nozzle inlet opening), the height of the liquid
oscillating chamber 126 being set to be greater than the width.
[0095] Also in this embodiment, in the same manner as the first
embodiment, the surface wave 32 can be increased by giving a
disturbance to the jet liquid column J with a laser beam (see FIG.
5). Thus, the jet liquid column J is more immediately atomized
after reaching the workpiece W.
[0096] Furthermore, also in the laser machining apparatus 100 of
this embodiment, it is possible to suppress the attachment of dirt,
oil, etc. in the liquid to the window surface which causes a
disturbance in light guiding. It should be noted that, in the laser
machining apparatus 100 of this embodiment, a portion of the top
end surface of the oscillating chamber inlet path 116d is
constructed of the lower end surface of the window 122, and the
liquid flows along the surface of the window 122. Thus, the surface
of the window 122 can be more effectively washed out, and
attachment of impurities can be more reliably prevented.
[0097] Next, referring to FIGS. 13A to 13C, modifications of the
oscillating chamber inlet path adjusting member 124 will be
described. FIG. 13A is a plan view of the oscillating chamber inlet
path adjusting member 124 according to the sixth embodiment of the
present invention. FIGS. 13B and 13C are plan views of oscillating
chamber inlet path adjusting members according to the
modifications.
[0098] As shown in FIG. 13A, the oscillating chamber inlet path
adjusting member 124 is a member for closing a portion of the
circular tray-shaped space formed within the head body 116, and has
a bottom 124a and an edge 124b that upstands from the edge of the
bottom 124a. The bottom 124a and the edge 124b are provided with a
generally fan-shaped notch with a central angle of approximately
90.degree., the notch serving as the oscillating chamber inlet path
116d. Also, a central angle portion of the fan-shaped notch is
rounded along an arc with a radius of about 10 mm. It should be
noted that FIG. 13A shows, by a phantom line, the position of the
oscillating chamber inlet port 126a with respect to the oscillating
chamber inlet path adjusting member 124.
[0099] FIG. 13B illustrates a first modification of the oscillating
chamber inlet path adjusting member 124. An oscillating chamber
inlet path adjusting member 132 according to the first modification
has a bottom 132a and an edge 132b. The bottom 132a and the edge
132b are each provided with a notch. The notch provided in the
bottom 132a is about 10 mm in width and extends radially to form
the oscillating chamber inlet path 116d to the oscillating chamber
inlet port 126a.
[0100] FIG. 13C illustrates a second modification of the
oscillating chamber inlet path adjusting member 124. An oscillating
chamber inlet path adjusting member 134 according to the second
modification has a bottom 134a and an edge 134b. The bottom 134a
and the edge 134b are each provided with a radially-extending notch
with a width of about 4 mm.
[0101] In the case where the oscillating chamber inlet path
adjusting members 132 and 134 according to the first and second
modifications are used, the oscillating chamber inlet path 116d
becomes narrower relative to the case where the oscillating chamber
inlet path adjusting member 124 of the sixth embodiment is used, so
that the jet liquid column J is more strongly oscillated and the
surface wave 32 increases. Therefore, in the laser machining
apparatus 100 according to the sixth embodiment in which the
oscillating chamber inlet path adjusting member 124 shown in FIG.
13A is used, the jet liquid column J is held over a length of about
48 mm. On the other hand, in the first modification, the liquid
column J breaks down into liquid masses 36 at a length of about 42
mm, while in the second modification the liquid column J breaks
down into liquid masses 36 at a length of about 28 mm.
[0102] Preferably, the oscillating chamber inlet path adjusting
members are changed depending on the uses of the laser machining
apparatus or objects to be machined. More specifically, if the
object to be machined is a thin plate or the like which can be cut
by one scanning of the jet liquid column J, the oscillating chamber
inlet path adjusting member 124 (FIG. 13A) is used. Thus, the jet
liquid column J is held over a long distance, and therefore the
distance between the object to be machined and the laser machining
head can be set larger.
[0103] Alternatively, if the object to be machined is a thick plate
or the like which requires multiple scanning of the jet liquid
column J in order for the completion of cutting, the oscillating
chamber inlet path adjusting member 132 (FIG. 13B) or 134 (FIG.
13C) is used. Thus, the jet liquid column J becomes likely to be
immediately atomized after striking the object to be machined.
Consequently, even in the state where the machining point is not
pierced, liquid becomes less likely to be accumulated in a groove
formed by machining, and a disturbance in light guiding due to the
accumulated liquid can be suppressed.
[0104] Although preferred embodiments of the present invention have
been described above, it should be understood that various changes
may be made to the above-described embodiments. In particular, the
present invention may be constructed by arbitrary combination of
the structures included in the above-described embodiments. Also,
in the above-described embodiments, the head body is an integral
member, however, may be arbitrarily separated into plural members.
Furthermore, by the combination of the above-described third and
fourth embodiments, the present invention may be constructed such
that a rotary table is provided on the tilting rotary table.
* * * * *