U.S. patent application number 16/325231 was filed with the patent office on 2019-07-04 for drilling method, resist layer, and fiber-reinforced plastic.
This patent application is currently assigned to SINTOKOGIO, LTD.. The applicant listed for this patent is SINTOKOGIO, LTD.. Invention is credited to Kouichi INOUE.
Application Number | 20190202029 16/325231 |
Document ID | / |
Family ID | 61760762 |
Filed Date | 2019-07-04 |
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United States Patent
Application |
20190202029 |
Kind Code |
A1 |
INOUE; Kouichi |
July 4, 2019 |
DRILLING METHOD, RESIST LAYER, AND FIBER-REINFORCED PLASTIC
Abstract
In an embodiment, provided is a drilling method of Bawling a
hole having a desired diameter in a fiber-reinforced plastic
workpiece. The method includes disposing a resist layer, in which
an opening having a diameter smaller than the desired diameter is
formed, on the workpiece and ejecting blasting abrasives to the
workpiece through the resist layer to cut a portion, which is
exposed from the opening, in the workpiece while cutting a
peripheral edge portion of the opening of the resist layer.
Inventors: |
INOUE; Kouichi;
(Kitanagoya-shi, Aichi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SINTOKOGIO, LTD. |
Nagoya-shi, Aichi |
|
JP |
|
|
Assignee: |
SINTOKOGIO, LTD.
Nagoya-shi, Aichi
JP
|
Family ID: |
61760762 |
Appl. No.: |
16/325231 |
Filed: |
September 25, 2017 |
PCT Filed: |
September 25, 2017 |
PCT NO: |
PCT/JP2017/034538 |
371 Date: |
February 13, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B24C 5/02 20130101; B24C
1/045 20130101; B24C 5/04 20130101; B24C 1/04 20130101 |
International
Class: |
B24C 1/04 20060101
B24C001/04; B24C 5/04 20060101 B24C005/04 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 28, 2016 |
JP |
2016-189185 |
Mar 8, 2017 |
JP |
2017-043513 |
Claims
1. A drilling method of forming a hole having a desired diameter in
a fiber-reinforced plastic workpiece, comprising steps of:
disposing a resist layer, in which an opening having a diameter
smaller than the desired diameter is formed, on the workpiece; and
ejecting blasting abrasives to the workpiece through the resist
layer to cut a portion, which is exposed from the opening, in the
workpiece while cutting a peripheral edge portion of the opening of
the resist layer.
2. The drilling method according to claim 1, wherein a ratio of the
diameter of the opening to the desired diameter is 0.84 or more and
0.94 or less.
3. The drilling method according to claim 1, wherein in the step of
ejecting the blasting abrasives to the workpiece, the blasting
abrasives are ejected toward the workpiece from a nozzle, and an
angle formed by a surface of the workpiece and a ejecting direction
of the blasting abrasives from the nozzle is
90.degree..+-.5.degree..
4. The drilling method according to claim 3, wherein the nozzle is
configured to suck the blasting abrasives by introducing compressed
air to the inside of the nozzle to eject the blasting abrasives
with the compressed air as a solid-gas two-phase flow.
5. The drilling method according to claim 1, wherein the workpiece
comprises the fiber-reinforced plastic in which a cut reinforcing
fibers are dispersed in a resin.
6. The drilling method according to claim 1, wherein the workpiece
comprises the fiber-reinforced plastic in which a woven reinforcing
fibers infiltrate into a resin.
7. A resist layer that is used in the drilling method according to
claim 1, wherein the resist layer is a polymer including
unsaturated polyurethane or an abrasion-resistant rubber as a main
component.
8. A fiber-reinforced plastic having a hole formed by the drilling
method according to claim 1, wherein the fiber-reinforced plastic
has a plate shape having a thickness of 1.0 mm or more and 2.0 mm
or less, and an angle formed by a plane perpendicular to a central
axis line of the hole and a wall surface defining the hole is
80.degree. or more and 90.degree. or less.
9. A drilling method of forming a hole in a fiber-reinforced
plastic workpiece having a front surface and a rear surface, the
hole being opened on the front surface and the rear surface and
having a first opening on the front surface side having a first
area, comprising: disposing a resist layer having blast resistance
higher than blast resistance of the workpiece on the workpiece, the
resist layer having a second opening which has a shape
corresponding to a shape of the first opening and has a second area
smaller than the first area; and ejecting blasting abrasives to the
workpiece through the resist layer to cut a portion, which is
exposed from the second opening, in the workpiece while cutting a
peripheral edge portion of the second opening of the resist layer.
Description
TECHNICAL FIELD
[0001] The present disclosure relates to a drilling method, a
resist layer, and a fiber-reinforced plastic.
BACKGROUND ART
[0002] A fiber-reinforced plastic (FRP) is a composite material in
which reinforcing fiber (glass fiber, carbon fiber, aramid fiber,
polyethylene fiber, cylon fiber, boron fiber, and the like) is put
into a resin (a polyester resin, a vinyl ester resin, an epoxy
resin, a phenol resin, and a thermoplastic resin) to improve
strength. The FRP has been used in a wide range of fields such as
daily necessities, sporting goods, automobiles, and aerospace
applications.
[0003] The FRP may be subjected to drilling to improve joining and
sound absorbency in some cases. As a method of forming a hole in an
FRP workpiece, drilling performed by using a drill, and
sandblasting are used. For example, Patent Literature 1 discloses a
configuration in which a resist layer having sandblast resistance
is disposed on a surface of the workpiece, and a region which is
not covered with the resist layer in the workpiece is removed by
sandblasting.
CITATION LIST
Patent Literature
[0004] Patent Literature 1: Japanese Unexamined Patent Publication
No. 2012-196751
SUMMARY OF INVENTION
Technical Problem
[0005] In drilling performed by using a drill, in a case where the
number of holes to be processed is large, a processing time is
lengthened, and thus the drilling is not preferable from the
viewpoint of productivity. In addition, in the drilling performed
by using a drill, fluffing may occur in the vicinity of a hole
formed in a workpiece, or peeling-off may occur on a surface of the
workpiece.
[0006] In addition, as in a method described in Patent Literature
1, even in a case where a hole is formed in a workpiece by
sandblasting, fluffing or peeling-off may occur in the workpiece
although the degree of occurrence is lower in comparison to the
drilling performed by using a drill.
[0007] Accordingly, it is desired to form a hole in the
fiber-reinforced plastic while suppressing occurrence of fluffing
and peeling-off.
Solution to Problem
[0008] According to one aspect of the present disclosure, there is
provided a drilling method of forming a hole having a desired
diameter in a fiber-reinforced plastic workpiece. The method
includes disposing a resist layer, in which an opening having a
diameter smaller than the desired diameter is formed, on the
workpiece and ejecting blasting abrasives to the workpiece through
the resist layer to cut a portion, which is exposed from the
opening, in the workpiece while cutting a peripheral edge portion
of the opening of the resist layer.
[0009] When the blasting abrasives are continuously projected to
the workpiece through the resist layer, the blasting abrasives
passing through the opening of the resist layer enters a downward
side of the resist layer, and thus peeling-off may occur on a
surface of the workpiece. When the peeling-off occurs, reinforcing
fibers of the workpiece are exposed on the surface of the workpiece
as fluffing. In the method according to the aspect, the blasting
abrasives are ejected to the workpiece through the resist layer in
which the opening having the diameter smaller than the desired
diameter is formed. In this method, the blasting abrasives collide
with the resist layer and cuts a peripheral edge portion of the
opening formed in the resist layer, the diameter of the opening is
gradually enlarged with the passage of a processing time. In this
manner, when the hole is formed in the workpiece while gradually
enlarging the diameter of the opening in the resist layer, even
when peeling-off occurs in the workpiece, a peeled-off portion is
removed along the progress of processing of the workpiece. As a
result, it is possible to suppress occurrence of peeling-off and
fluffing on the surface of the workpiece after processing.
[0010] In one embodiment, a ratio of the diameter of the opening to
the desired diameter may be 0.84 or more and 0.94 or less. When the
ratio of the diameter of the opening to the desired diameter is set
as described above, it is possible to efficiently perform
processing while maintaining accuracy in a hole diameter after
processing.
[0011] In one embodiment, in the step of ejecting the blasting
abrasives to the workpiece, the blasting abrasives may be ejected
toward the workpiece from a nozzle, and an angle formed by a
surface of the workpiece and a ejecting direction of the blasting
abrasives from the nozzle may be 90.degree..+-.5.degree.. When the
blasting abrasives are ejected to the workpiece at this angle, it
is possible to suppress occurrence of peeling-off on the surface
layer of the resin. As a result, it is possible to suppress
fluffing.
[0012] In one embodiment, the nozzle may be configured to suck the
blasting abrasives by introducing compressed air to the inside of
the nozzle to eject the blasting abrasives with the compressed air
as a solid-gas two-phase flow. The fiber-reinforced plastic is a
difficult-to-cut material with respect to blast processing, and
thus a considerable time is necessary until processing is
completed. In this embodiment, the blasting abrasives can be
continuously ejected from the nozzle, it is possible to improve
processing efficiency.
[0013] In one embodiment, the workpiece may comprise the
fiber-reinforced plastic in which a cut reinforcing fibers are
dispersed in a resin. In this type of fiber-reinforced plastic, the
reinforcing fibers are dispersed without directionality.
Accordingly, in a conventional drilling method, a surface may be
peeled off from the reinforcing fibers as the origin, and the
fiber-reinforce plastic may be broken. In contrast, according to
the drilling method of the one embodiment, even in the workpiece as
described above, it is possible to suppress occurrence of
peeling-off or fluffing on the surface of the workpiece.
[0014] In one embodiment, the workpiece may comprise the
fiber-reinforced plastic in which woven reinforcing fibers
infiltrate into a resin. In this type of fiber-reinforced plastic
is obtained by alternately laminating reinforcing fibers that are
woven in a cloth shape and a resin. Accordingly, in the
conventional drilling method, inter-layer peeling-off may occur,
and the fiber-reinforced plastic may be broken. According to the
drilling method of the one embodiment, even in the workpiece as
described above, it is possible to suppress occurrence of
peeling-off or fluffing on the surface of the workpiece.
[0015] According to another aspect of the present disclosure, there
is provided a resist layer that is used in the drilling method. The
resist layer is a polymer including unsaturated polyurethane or an
abrasion-resistant rubber as a main component. In a case of using
the polymer as a material of the resist layer, when drilling the
workpiece, the resist layer is suppressed from being excessively
deformed, and thus it is possible to enhance dimensional accuracy
of a hole that is formed in the workpiece.
[0016] According to still another aspect of the present disclosure,
there is provided a fiber-reinforced plastic having a hole formed
by the drilling method. The fiber-reinforced plastic has a plate
shape having a thickness of 1.0 mm or more and 2.0 mm or less, and
an angle formed by a plane perpendicular to a central axis line of
the hole and a wall surface defining the hole is 80.degree. or more
and 90.degree. or less. When the angle formed by the plane
perpendicular to the central axis line of the hole and the wall
surface defining the hole is an angle of 80.degree. or more and
90.degree. or less, it is possible to improve uniformity of a hole
diameter in a thickness direction of the fiber-reinforced plastic.
Furthermore, the plate shape stated here includes not only a flat
plate shape but also a curved plate shape.
[0017] According to still another aspect of the present disclosure,
there is provided a drilling method of forming a hole in a
fiber-reinforced plastic workpiece having a front surface and a
rear surface, the hole being opened on the front surface and the
rear surface and having a first opening on the surface side having
a first area. The method includes disposing a resist layer having
blast resistance higher than blast resistance of the workpiece on
the workpiece, the resist layer having a second opening which has a
shape corresponding to a shape of the first opening and has a
second area smaller than the first area; and ejecting blasting
abrasives to the workpiece through the resist layer to cut a
portion, which is exposed from the second opening, in the workpiece
while cutting a peripheral edge portion of the second opening of
the resist layer.
[0018] When the blasting abrasives are continuously projected to
the workpiece through the resist layer, the blasting abrasives
passing through the second opening enters a downward side of the
resist layer, and thus peeling-off may occur on a surface of the
workpiece. When the peeling-off occurs, reinforcing fibers of the
workpiece are exposed on the surface of the workpiece as fluffing.
In the method according to the aspect, the blasting abrasives are
ejected to the workpiece through the resist layer in which the
second opening having the second area smaller than that of the
first area is formed. In this method, the blasting abrasives, which
collide with the resist layer, cut a peripheral edge portion of the
second opening, and thus the area of the second opening is
gradually enlarged with the passage of a processing time. In this
manner, when the hole is formed in the workpiece while gradually
enlarging the area of the second opening, even when peeling-off
occurs in the workpiece, a peeled-off portion is removed along the
progress of processing of the workpiece. As a result, it is
possible to suppress occurrence of peeling-off and fluffing on the
surface of the workpiece after processing.
Advantageous Effects of Invention
[0019] According to various aspects and embodiments of the present
disclosure, it is possible to form a hole in a fiber-reinforced
plastic while suppressing occurrence of fluffing and
peeling-off.
BRIEF DESCRIPTION OF DRAWINGS
[0020] FIG. 1 is a front view illustrating a sandblast machine that
is used in one embodiment in a partially cut-out manner.
[0021] FIG. 2 is a flowchart illustrating a drilling method of one
embodiment.
[0022] FIG. 3 is a view schematically illustrating a scanning
trajectory of a workpiece of one embodiment.
[0023] FIG. 4 is a cross-sectional view illustrating a workpiece to
which a drilling method of one embodiment is applied.
[0024] FIG. 5 is a cross-sectional view illustrating a workpiece to
which a conventional drilling method is applied.
DESCRIPTION OF EMBODIMENTS
[0025] Hereinafter, various embodiments will be described in detail
with reference to the accompanying drawings. Furthermore, the same
reference sign will be given to the same or equivalent portion in
the drawings, and redundant description for the same or equivalent
portion will be omitted. In addition, it is not necessary for
dimension ratios of the drawings to match actual dimension ratios.
Furthermore, right and left directions and upper and lower
directions in description represent directions in the drawings
unless otherwise stated.
[0026] FIG. 1 is a front view illustrating a sandblast machine 01
according to one embodiment in a partially cut-out manner. The
sandblast machine 01 is a device that projects blasting abrasives
to a fiber-reinforced plastic workpiece W (workpiece) and forms a
hole in the workpiece W. As illustrated in FIG. 1, the sandblast
machine 01 includes a housing 10, a fixed-quantity supply mechanism
20, a separation mechanism 30, a suction mechanism 40, a nozzle 50,
and a control device 60.
[0027] The housing 10 constitutes a processing chamber R on an
inner side thereof. A door 11 is provided in a front surface of the
housing 10, and an operator can access the processing chamber R by
opening the door 11. A nozzle fixture 12, a processing table 13,
and a movement mechanism 14 are provided in the processing chamber
R.
[0028] The nozzle fixture 12 is a mechanism that holds the nozzle
50, and can move the nozzle 50 along a height direction.
Accordingly, the nozzle fixture 12 is configured to freely adjust a
distance between the nozzle 50 and the workpiece W.
[0029] The movement mechanism 14 is provided on a frame 15 that is
provided on a lower side of the housing 10, and is disposed on a
downward side of the nozzle 50. In one embodiment, the movement
mechanism 14 may be plate-shaped body in which a plurality of
through-holes are formed. When the through-holes are formed in the
movement mechanism 14, it is possible to allow blasting abrasives,
which is ejected from the nozzle 50, to propagate toward the bottom
of the housing 10.
[0030] The processing table 13 is provided on the movement
mechanism 14 and supports the workpiece W that is placed on the
processing table 13. For example, the movement mechanism 14 is
configured to convey the processing table 13 and the workpiece W
supported on the processing table 13 in a horizontal direction by a
driving force of a motor. For example, the movement mechanism 14 is
an X-Y stage that extends in the horizontal direction and moves the
workpiece W in an X direction and a Y direction which are
perpendicular to each other (refer to FIG. 3).
[0031] The fixed-quantity supply mechanism 20 is provided on an
upper side of the processing chamber R. The fixed-quantity supply
mechanism 20 includes a storage hopper 21 and a conveyance path 22,
and supplies blasting abrasives in the storage hopper 21 to the
nozzle 50 in a fixed quantity through the conveyance path 22.
Furthermore, a structure of the fixed-quantity supply mechanism 20
is not limited as long as the fixed-quantity supply mechanism 20
can supply a constant amount of blasting abrasives to the nozzle
50. For example, as the fixed-quantity supply mechanism 20, a screw
feeder, a vibration feeder, and a table feeder can be used. In the
embodiment illustrated in FIG. 1, the screw feeder is used as the
fixed-quantity supply mechanism 20.
[0032] The separation mechanism 30 is provided on an upper side of
the storage hopper 21 of the fixed-quantity supply mechanism 20.
The separation mechanism 30 is connected to the storage hopper 21
of the fixed-quantity supply mechanism 20. The separation mechanism
30 has an approximately inverted pyramid shape, collects used
blasting abrasives, and classifies the blasting abrasives into a
blasting abrasives that can be reused, and dust. One end of a first
transport pipe P1 is connected to the separation mechanism 30. The
other end of the first transport pipe P1 is connected to the bottom
of the housing 10. Accordingly, a space in the processing chamber R
and a space in the fixed-quantity supply mechanism 20 communicate
with each other through the first transport pipe P1. In the
embodiment illustrated in FIG. 1, a cyclone type classifier is used
as the separation mechanism 30. However, as the separation
mechanism 30, arbitrary classifiers such as a wind power type
classifier, a screen type classifier can be used.
[0033] In addition, one end of a second transport pipe P2 is
connected to the separation mechanism 30. The other end of the
second transport pipe P2 is connected to the suction mechanism 40.
The suction mechanism 40 is a mechanism that sets the processing
chamber R to negative pressure in order for the blasting abrasives
not to be leaked to the outside of the processing chamber R, and
suctions particles including the blasting abrasives that are
ejected. The suction mechanism 40 collects light particles (a
blasting abrasives that becomes a size that is not appropriate for
reuse, and chip powders of the workpiece W and a sheet 70) which
are classified in the separation mechanism 30 (cyclone type
classifier) through the second transport pipe P2. In addition, the
suction mechanism 40 has a function of setting an internal space of
the separation mechanism 30 to negative pressure, and transporting
the blasting abrasives, which is used and collected at the bottom
of the housing 10, to the separation mechanism 30.
[0034] The nozzle 50 is a mechanism that ejects the blasting
abrasives to the workpiece W, and includes a nozzle holder 51, an
air nozzle 52, and an ejecting nozzle 53. The nozzle holder 51 is
connected to the fixed-quantity supply mechanism 20 through a
blasting abrasive hose H2. A compressor C is connected to the air
nozzle 52 through an air hose H1. In one embodiment, an
electromagnetic valve VL1 and a valve VL2 may be provided between
the air nozzle 52 and the compressor C. When the compressor C is
operated, compressed air is ejected from the air nozzle 52, and the
inside of the nozzle holder 51 becomes negative pressure. According
to this, the blasting abrasives stored in the storage hopper 21 is
suctioned into the nozzle holder 51 through the conveyance path 22
and the blasting abrasive hose 112, is mixed with the compressed
air in the nozzle holder 51, and is ejected as a solid-gas
two-phase flow from an ejecting port of the ejecting nozzle toward
the workpiece W. The nozzle 50 having the above-described
configuration can continuously eject the blasting abrasives, and
thus it is possible to continuously process the workpiece W over a
long time.
[0035] Furthermore, a so-called direct pressure type nozzle can be
used as a nozzle of another type. The direct pressure type nozzle
has more excellent cutting capacity in comparison to the nozzle 50
of this embodiment, but it is difficult to continuously perform
processing over a long time.
[0036] Examples of a blasting abrasives that is ejected from a
nozzle include a metal or nonmetal shot, grid, or cut-wire,
ceramic-based particles (alumina-based particles, silicon
carbide-based particles, zircon-based particles, and the like),
natural stone particles (emery, silica stone, diamond, and the
like), plant-based particles (a shell of a walnut, a peach stone,
an apricot stone, and the like), resin-based particles (nylon,
melamine, urea, and the like), and the like. The fiber-reinforce
plastic is a difficult-to-cut material. Accordingly, when selecting
a relatively hard material as the blasting abrasives, it is
possible to efficiently cut the workpiece W.
[0037] The control device 60 is a computer including a processor, a
storage unit, an input device, a display device, and the like, and
controls respective units of the sandblast machine 01. In one
embodiment, the control device 60 transmits a control signal to the
movement mechanism 14, the fixed-quantity supply mechanism 20, the
suction mechanism 40, and the electromagnetic valve VL1, and
controls positions of the movement mechanism 14 in the X direction
and the Y direction, an operation of the fixed-quantity supply
mechanism 20, an operation of the suction mechanism 40, and opening
and closing of the electromagnetic valve VL1, and the like. As a
control device, various operation devices such as a personal
computer, a motion controller such as a programmable logic
controller (PLC) and a digital signal processor (DSP), a
high-function portable terminal, a high-function portable
telephone, and the like can be used.
[0038] Hereinafter, description will be given of a drilling method
by the sandblast machine 01 of one embodiment with reference to
FIG. 2. In this method, a hole H having a desired diameter d.sub.1
is formed in the fiber-reinforced plastic workpiece W. The
workpiece W has a flat plate shape, and includes an upper surface
(front surface) 82 and a lower surface (rear surface) 84 opposite
to each other (refer to FIG. 4). The hole H to be formed in the
workpiece W is a through-hole that extends from the upper surface
82 to the lower surface 84, and is opened to the upper surface 82
and the lower surface 84. In the hole H, an opening (first opening)
86 on the upper surface 82 side has the desired diameter d.sub.1.
In other words, the hole H to be formed in the workpiece W is a
through-hole including the opening 86 having an area (first area)
corresponding to the desired diameter d.sub.1 on the upper surface
82 side. Hereinafter, description will be given of an example in
which the workpiece W is constituted by a glass fiber-reinforced
plastic (GFRP) that is one kind of the fiber-reinforced
plastic.
[0039] Furthermore, the desired diameter d.sub.1 of the opening 86
represents a length of the widest portion in the diameter of the
opening 86. For example, in a case where the opening 86 has an
elliptical shape, the major axis of the ellipse becomes the desired
diameter d.sub.1. In a case where the opening 86 has a polygonal
shape, a length of the longest straight line among straight lines
which connect arbitrary two corners of the polygon becomes the
desired diameter d.sub.1. Hereinafter, description will be given of
an embodiment in which the opening 86 has a circular shape. In this
embodiment, the diameter of the opening 86 becomes the desired
diameter d.sub.1.
[0040] <S1: Preparation of Resist Layer>
[0041] In a drilling method according to one embodiment, first, a
step S1 is performed. In the step S1, a sheet 70 that functions as
a resist layer is prepared. The sheet 70 is constituted by a
material that is softer than the blasting abrasives and is capable
of absorbing an impact force of the blasting abrasives.
Accordingly, the sheet 70 has blast resistance that is higher than
that of the workpiece W constituted by the fiber-reinforced
plastic.
[0042] One or a plurality of openings (second openings) 71 are
formed in the sheet 70 (refer to FIG. 4). Each of the openings 71
has a shape corresponding to a shape of the opening 86 of the hole
H. For example, the opening 71 has a planar shape such as a
circular shape, an elliptical shape, and a polygonal shape in
correspondence with the shape of the opening 86. In one embodiment,
the opening 71 of the sheet 70 has the same shape as that of the
opening 86 of the workpiece W. However, a diameter d.sub.2 of the
opening 71 is set to smaller than the desired diameter d.sub.1. In
other words, the opening 71 has an area (second area) that is
smaller than the area of the opening 86. A ratio (d.sub.2/d.sub.1)
of the diameter d.sub.2 of the opening 71 to the desired diameter
d.sub.1 may be set in a range of 0.84 to 0.94, particularly, in a
range of 0.90 to 0.94. As to be described later, when the ratio is
excessively small, a collision chance between the workpiece W and
the blasting abrasives are excessively less, and thus a drilling
time is lengthened. In contrast, the ratio is excessively large,
peeling-off is likely to occur in a surface layer of the workpiece
W. Here, the diameter d.sub.2 of the opening 71 represents the
largest diameter among diameters defined by the opening 71. For
example, in a case where the planar shape of the opening 71 is set
to an elliptical shape, the major axis of the opening 71 of the
elliptical shape becomes the diameter d.sub.2. In a case where the
planar shape of the opening 71 is set to a polygonal shape, a
length of the longest straight line among straight lines which
connect arbitrary two corners of the polygon becomes the diameter
d.sub.2. Hereinafter, description will be given of an embodiment in
which the planar shape of the opening 71 is a circular shape. In
this embodiment, the diameter of the opening 71 becomes the
diameter d.sub.2.
[0043] As a material of the sheet 70, for example, thermoplastic
resins such as various rubbers, nylon, polyethylene (PE),
polypropylene (PP), polyurethane, and acrylic can be used. For
example, as the material of the sheet 70, an abrasion-resistant
rubber can be used. Abrasion resistance of a rubber can be easily
adjusted by changing a blending ratio of a filling reinforcing
material such as calcium carbonate to a natural rubber or a
synthetic rubber that is a main raw material. Accordingly, when
using the abrasion-resistant rubber as the material of the sheet
70, it is possible to easily obtain a resist material having
abrasion resistance that is appropriate for drilling. In one
embodiment, an abrasion-resistance rubber in which a reinforcing
filling material is blended to a natural rubber or a synthetic
rubber in a ratio of 60 wt % to 70 wt % can be used as the material
of the sheet 70.
[0044] In addition, polyurethane is comprehensively excellent in
elasticity, a thermal deformation temperature, and impact strength.
Accordingly, when using polyurethane as the material of the sheet
70, it is possible to improve accuracy of a diameter of the hole H
that is formed in the workpiece W. In addition, it is possible to
easily form the opening 71 having a small diameter (for example,
.PHI. 2 mm or less) in the polyurethane sheet 70. As to be
described later, in a method of one embodiment, a portion exposed
from the opening 71 in the workpiece W is cut while cutting a
peripheral edge portion 72 of the opening 71 in the sheet 70 by
blasting abrasives. At this time, when the peripheral edge portion
72 of the sheet 70 is cut more than necessary, fluffing or
peeling-off may occur on a surface of the workpiece W or
dimensional accuracy may deteriorate due to the cutting.
Accordingly, the material of the sheet 70 is selected in
consideration of elasticity, a thermal deformation temperature, and
impact force resistance. For example, unsaturated polyurethane is
comprehensively excellent in elasticity, a thermal deformation
temperature, and Charpy impact strength, and thus the sheet 70 may
be constituted by a polymer that includes unsaturated polyurethane
as a main component. In addition, a content rate of the unsaturated
polyurethane may be set to 50 wt % or more, or 50 wt % to 70 wt
%.
[0045] In one embodiment, the sheet 70 may be formed from a
photosensitive resin that is shaped in a film shape. When forming
the sheet 70 from the photosensitive resin, first, a transparent
pattern mask in which an opening pattern is printed is disposed on
the sheet 70, the sheet 70 is irradiated with ultraviolet rays from
an ultraviolet ray emission source provided on an upper side of the
sheet 70 through the pattern mask. In the sheet 70, a region that
does not overlap a printed pattern is cured through irradiation of
ultraviolet rays. However, a portion that overlaps the printed
opening pattern become shadow, and is not cured. Subsequently, the
sheet 70 after being irradiated with ultraviolet rays is washed out
by using a development solution, and thus the uncured region of the
sheet 70 is removed. A plurality of the openings 71 can be formed
in the sheet 70 through a series of processes as described
above.
[0046] In addition, in the step S1, the prepared sheet 70 is
disposed on the workpiece W. In one embodiment, the sheet 70 may
have stickiness. In this case, after the sheet 70 is stuck to an
upper surface of the workpiece W, pressure is reduced in a vacuum
chamber. According to this, it is possible to closely stick the
sheet 70 onto the workpiece W. In addition, when the workpiece W is
subsequently heated at a temperature of 60.degree. C. to 90.degree.
C., the workpiece W and the sheet 70 can be firmly and closely
stuck to each other.
[0047] <S2: Preparation of Sandblast Machine>
[0048] Subsequently, in a drilling method according to one
embodiment, a step S2 is performed. In the step S2, the sandblast
machine 01 is prepared. In the step S2, first, the suction
mechanism 40 is operated for suctioning of the processing chamber
R. Subsequently, locking of the door 11 is released to open the
door 11, and a predetermined amount of blasting abrasives are put
into the processing chamber R by an operator as an example.
Subsequently, the blasting abrasives are transported to the storage
hopper 21 of the fixed-quantity supply mechanism 20 through the
first transport pipe P1 and the separation mechanism 30 due to a
suction force of the suction mechanism 40. Then, the door 11 is
closed and locked. The processing chamber R becomes negative
pressure due to suctioning of the suction mechanism 40, and thus
external air flows into the processing chamber R from a suction
hole (not illustrated) provided to communicate with the
outside.
[0049] In the step S2, for example, the control device 60 of the
sandblast machine 01 is operated to set the electromagnetic valve
VL1, which is provided in a path through which compressed air is
supplied to the nozzle 50, to "open", and to set the fixed-quantity
supply mechanism 20 to "ON". Through the setting, the blasting
abrasives are supplied to the nozzle 50, and are ejected from the
nozzle 50. When the blasting abrasives are ejected from the nozzle
50, the degree of opening of the valve VL2 that adjusts compressed
air supply pressure is adjusted, and thus a ejected velocity of the
blasting abrasives are adjusted.
[0050] Subsequently, the control device 60 of the sandblast machine
01 is operated to set the electromagnetic valve VL1 to "close", and
to set the fixed-quantity supply mechanism 20 to "OFF". Through the
setting, ejecting of the blasting abrasives from the nozzle 50 are
stopped. Then, the door 11 is opened, and the workpiece W is placed
on the processing table 13 and is fixed thereto. Subsequently, the
nozzle fixture 12 is operated to adjust a distance and an angle
between the nozzle 50 and the workpiece W. When the above-described
processes are finished, the door 11 is closed and locked.
Furthermore, the workpiece W that is placed on the processing table
13 may be a plate-shaped body having a thickness of 1.0 or more and
2.0 mm or less.
[0051] Subsequently, in the step S2, processing conditions such as
a movement trajectory (distances in the X direction and the Y
direction in FIG. 3) and a movement velocity of the movement
mechanism 14, and the number of times of scanning are input to the
control device 60.
[0052] <S3: Drilling Process>
[0053] Subsequently, a step S3 is performed. In the step S3, as to
be described later, the blasting abrasives are ejected toward the
workpiece W through the sheet 70 to cut a portion exposed from the
opening 71 in the workpiece W while cutting the peripheral edge
portion 72 of the opening 71 in the sheet 70. Hereinafter, an
example of the step S3 will be described in detail.
[0054] In the step S3, first, the control device 60 is operated to
set the electromagnetic valve VL1 to "open" and to set the
fixed-quantity supply mechanism 20 to "ON". According to this, the
blasting abrasives are ejected from the nozzle 50. Subsequently,
the movement mechanism 14 is set to "ON", and the movement
mechanism 14 operates so that the workpiece W is moved in a
horizontal direction. For example, as illustrated in FIG. 3, the
movement mechanism 14 repeats movement of the workpiece W in a +X
direction by a predetermined distance, and movement of the
workpiece W in a -X direction after deviating a position of the
workpiece W in a +Y direction by a predetermined pitch. According
to this, the workpiece W is scanned in a comb-tooth shape with
respect to an ejecting region A of the blasting abrasives. The
movement mechanism 14 moves the workpiece W along a scanning
trajectory T to allow the blasting abrasives to collide with the
entire surface of the workpiece W in an approximately uniform
manner. In one embodiment, the scanning is performed in a plurality
of times to form the hole H in the workpiece W. An ejecting port of
the nozzle 50 may have rectangular planar shape. When the ejecting
port of the nozzle 50 has a rectangular planar shape and is
disposed in such a manner that a long side of the ejecting port
matches the Y direction, it is possible to enlarge a collision area
of the blasting abrasives when the workpiece W is scanned in the X
direction. As a result, it is possible to improve processing
efficiency of the workpiece W.
[0055] As described above, when the workpiece W is conveyed in the
X direction and the Y direction by the movement mechanism 14, in
the workpiece W, the hole H is formed in a region that is not
covered with the opening 71 of the sheet 70. Here, as illustrated
in FIG. 4, the blasting abrasives are projected from the nozzle 50
toward a region that includes the opening 71 and the peripheral
edge portion 72 of the opening 71. Accordingly, in the step S3, as
illustrated in FIG. 4, a region exposed from the opening 71 in the
workpiece W is cut while the peripheral edge portion 72 of the
opening 71 is cut. The sheet 70 has blast resistance higher than
that of the fiber-reinforced plastic that constitutes the workpiece
W, and thus the peripheral edge portion 72 of the sheet 70 is cut
slowly in comparison to the workpiece W. Accordingly, in the step
S3, the region exposed from the opening 71 in the workpiece W is
cut in such a manner that a cut area of the workpiece W does not
become excessive while gradually enlarging a diameter (area) of the
opening 71 of the sheet 70. As a result, the peeling-off of the
workpiece W in a surface layer is suppressed. In the step S3,
projection of the blasting abrasives continues until the diameter
of the hole H formed in the workpiece W becomes the desired
diameter d.sub.1.
[0056] FIG. 5 illustrates a shape of the hole H that is formed in
the workpiece W when the diameter d.sub.2 of the opening 71 and the
desired diameter d.sub.1 are set to be the same as each other. That
is, FIG. 5 illustrates a conventional method in which the hole H
having the desired diameter d.sub.1 is directly formed in the
workpiece W without cutting the peripheral edge portion 72 of the
sheet 70. In a case where the fiber-reinforced plastic that
constitutes the workpiece W has a structure in which a cut
reinforcing fibers are dispersed in a resin, when the blasting
abrasives are projected to the workpiece W, the reinforcing fibers
dispersed without directionality becomes the origin of fracture,
and thus peeling-off occurs on a surface of the workpiece W. In
addition, in a case where the fiber-reinforce plastic that
constitutes the workpiece W has a structure in which a woven
reinforcing fibers infiltrate into a resin, the reinforcing fibers
having a cloth shape becomes the origin of fracture, and thus
peeling-off occurs on a surface of the workpiece W. When cutting
further continues after the peeling-off occurs, the diameter of the
hole H formed in the workpiece W finally becomes larger than the
desired diameter d.sub.1, and a surface layer portion does not
become a circle shape. In addition, fluffing of the reinforcing
fibers occur on a wall surface of the hole H (refer to a portion
surrounded by a circle in the same drawing).
[0057] In the case where an ejection flow of the blasting abrasives
are captured microscopically, when the ejection flow flows along
the surface of the workpiece W, the surface layer of the workpiece
W is likely to be peeled off due to the characteristics of the
fiber-reinforced plastic. When peeling-off occurs in the surface
layer of the workpiece W, the reinforcing fibers are exposed to
surface layer, and thus fluffing occurs. Furthermore, the ejection
flow flows in a direction conforming to a wall surface of the
opening of the sheet 70 (that is, a direction perpendicular to the
X direction and the Y direction), it is possible to suppress
peeling-off on the surface layer of the workpiece W. As a result,
it is possible to suppress fluffing of the reinforcing fibers. In a
case where the fiber-reinforced plastic that constitutes the
workpiece W has a structure in which woven reinforcing fibers
infiltrate into a resin, the blasting abrasives collide with the
workpiece W in a direction in which the reinforcing fibers of the
workpiece W is cut, and thus it is possible to further suppress
fluffing of the reinforcing fibers. In addition, in a case where
the ejection flow is greatly inclined to the surface of the
workpiece W, collision energy of the blasting abrasives are not
sufficient. Accordingly, the hole H may not be formed in the
workpiece W, the reinforcing fibers may not be cut, or the
reinforcing fibers may be exposed on an outer peripheral surface of
the hole H as fluffing. Here, in one embodiment, the nozzle 50 may
be disposed at an angle of 85.degree. to 95.degree. (that is, in a
range of 90.degree..+-.5.degree.) with respect to the surface of
the workpiece W. In other words, the nozzle 50 is disposed so that
an angle made by the surface of the workpiece W and an ejecting
direction of the blasting abrasives becomes 85.degree. or more and
95.degree. or less.
[0058] When processing is performed so that an angle of a wall
surface of the hole H formed in the workpiece W becomes
appropriate, the processing is advantageous in performance. For
example, the hole H formed in the workpiece W is provided for
joining, the higher the perpendicularity of a wall surface defining
the hole H is, the more a clearance between a joining member such
as a bolt and the wall surface of the hole H becomes uniform in a
thickness direction. As a result, it is possible to suppress
backlash after joining. In addition, in a case where the hole H
formed in the workpiece W is provided to improve sound absorbency,
the higher the perpendicularity of the wall surface defining the
hole H is, the further sound reflection due to the wall surface of
the hole H is prevented. As in the examples, it is preferable that
the angle of the wall surface with respect to a plane perpendicular
to a central axis line AX of the hole H is close to 90.degree. from
the viewpoint of performance. However, as it is close to
90.degree., productivity further deteriorates. Accordingly, the
angle of the wall surface that constitutes the hole H with respect
to the plane perpendicular to the central axis line AX of the hole
H may be 80.degree. to 90.degree., or 80.degree. to 85.degree. from
the viewpoints of productivity and performance.
[0059] Particles including the blasting abrasives projected to the
workpiece W in the step S3 are collected at the bottom of the
housing 10, and is transported to the separation mechanism 30
through the first transport pipe P1 due to a suction force of the
suction mechanism 40. The particles transported to the separation
mechanism 30 are separated into a blasting abrasives that can be
reused and dust in the separation mechanism 30. The blasting
abrasives that can be reused are accumulated in the storage hopper
21, and light dust is suctioned to the suction mechanism 40 and is
collected by a collection filter provided inside the suction
mechanism 40. The blasting abrasives that are accumulated in the
storage hopper 21 and can be reused are transported to the nozzle
50 in a constant amount, and are ejected again toward the workpiece
W.
[0060] <S4: Recovery Process>
[0061] After forming the hole H in the workpiece W in the step S3,
a step S4 is performed. In the step S4, the control device 60 is
operated to set the movement mechanism 14 to "OFF", to set the
electromagnetic valve VL1 to "close", and to set the fixed-quantity
supply mechanism 20 to "OFF", respectively. Then, locking of the
door 11 is released to open the door 11, and the workpiece W is
recovered from the processing chamber R. Subsequently, after the
sheet 70 stuck to the workpiece W is peeled off, the blasting
abrasives and dust which adhere to the workpiece W are removed by
using air blow, ultrasonic cleaning, and the like. Through the
processes, a series of drilling is terminated.
[0062] Next, description will be given of an experiment example in
which drilling of the FRP was performed by using the drilling
method of one embodiment. In the experiment example, processing of
forming 100 pieces of holes (10 pieces.times.10 pieces) which have
a diameter .PHI. of 2.0 mm (on a surface to be processed side) and
have an approximately circular shape in glass fiber-reinforced
glass (GFRP) workpiece W having a plate shape (200 mm.times.200
mm.times.t1.0 mm (thickness)) was performed.
[0063] As the resist layer, a sheet (thickness: 0.5 mm), which
contains an unsaturated polyurethane or an acrylic resin as a main
component and in which an opening having a shape corresponding to a
hole to be processed, was used.
[0064] Resist A: Unsaturated polyurethane is a main component
(contained in 53 wt %)
[0065] Resist B: Unsaturated polyurethane is a main component
(contained in 73 wt %)
[0066] Resist C: Acrylic resin is a main component (contained in 60
wt %)
[0067] Other main processing conditions were set as illustrated in
Table 1.
TABLE-US-00001 TABLE 1 Blasting abrasives Silicon carbide particles
(average particle size: 150 .mu.m) Ejecting pressure 0.4 MPa
Distance between workpiece and 100 mm nozzle Angle of nozzle
90.degree. Scanning velocity of workpiece 100 mm/sec Number of
times of scanning of 40 Pass workpiece
[0068] After performing drilling with respect to the workpiece W,
among 100 pieces of holes which were formed, arbitrary 10 pieces of
holes were selected, and were observed by using an electron
microscope. Then, evaluation was performed. Evaluation standards
were as follows.
[0069] <Processing Progress>
[0070] .largecircle. . . . All holes are penetrated, and an angle
of a wall surface of the all holes is 80.degree. to 90.degree..
[0071] .DELTA. . . . All holes are penetrated, and the angle of the
wall surface of the all holes is 60.degree. to 80.degree..
[0072] X . . . Hole which is not penetrated exists, or hole in
which the angle of the wall surface of the hole is 59.degree. or
less exists.
[0073] <Diameter of Hole>
[0074] .largecircle. . . . Diameter on a surface to be processed
side is less than .+-.7% of a target dimension .PHI. 2.0 mm) in all
holes.
[0075] .DELTA. . . . Diameter on the surface to be processed side
is .+-.8% to .+-.15% of the target dimension (.PHI. 2.0 mm) in the
all holes.
[0076] X . . . Hole in which the diameter on the surface to be
processed side is .+-.16% of the target dimension (.PHI. 2.0 mm)
exists.
[0077] <Presence of Absence of Peeling-Offs
[0078] .largecircle. . . . All holes have a circular shape.
[0079] .DELTA. . . . Hole in which a surface-layer peeling-off
trace is observed in the vicinity of an outer periphery exists, but
the trace is less than 1 mm from an outer periphery of a
circle.
[0080] X . . . Hole in which the surface-layer peeling-off trace is
observed in the vicinity of the outer periphery exists, and the
magnitude of the trace is 1 mm or greater from the outer periphery
of a circle.
[0081] <Presence or Absence of Fluffing>
[0082] .largecircle. . . . Fluffing is not confirmed in all
holes.
[0083] .DELTA. . . . Hole in which slight fluffing is confirmed
exists, but an exposed glass fiber is less than 0.1 mm.
[0084] X . . . Hole in which fluffing is confirmed exists, and the
exposed glass fiber is 0.1 mm or greater.
[0085] Hereinafter, processing conditions and evaluation results of
various examples and comparative examples are illustrated in Table
2. "Processing" in Table 2 represents an evaluation results
relating to "Processing Progress", "Peeling-Off" represents an
evaluation result relating to "Presence or Absence of Peeling-Off",
and "Fluffing" represents an evaluation result relating to
"Presence or Absence of Fluffing". In addition, "Nozzle angle" in
Table 2 represents the angle of the ejection flow of the blasting
abrasives with respect to the surface of the workpiece W, and
0.degree. is an angle at which the ejection flow is horizontally
ejected toward a scanning direction side in the longitudinal
direction of the workpiece W at initiation of scanning. That is, a
state in which the ejection flow flows in the +X direction
illustrated in FIG. 3 is set as 0.degree..
TABLE-US-00002 TABLE 2 Resist Evaluation Layer d2/d1 Nozzle angle
(deg.) Processing Diameter of hole Peeling-Off Fluffing Example 1 A
0.85 92 .largecircle. .largecircle. .largecircle. .largecircle.
Example 2 A 0.90 92 .largecircle. .largecircle. .largecircle.
.largecircle. Example 3 A 0.94 92 .largecircle. .largecircle.
.largecircle. .largecircle. Example 4 A 0.92 85 .largecircle.
.largecircle. .largecircle. .largecircle. Example 5 A 0.92 94
.largecircle. .largecircle. .largecircle. .largecircle. Example 6 B
0.85 92 .largecircle. .largecircle. .largecircle. .largecircle.
Comparative A 0.78 92 X .largecircle. .largecircle. .largecircle.
Example 1 Comparative A 0.98 92 .largecircle. .DELTA. .DELTA.
.DELTA. Example 2 Comparative A 1.05 92 .largecircle. X X X Example
3 Comparative A 0.92 79 .DELTA. .largecircle. .largecircle. .DELTA.
Example 4 Comparative A 0.92 120 X .largecircle. .largecircle.
.DELTA. Example 5 Comparative C 0.85 92 .DELTA. .DELTA. .DELTA.
.DELTA. Example 6
[0086] (1) Influence of d.sub.2/d.sub.1
[0087] In Examples 1 to 6, all evaluation items were
".largecircle." evaluation, and it was confirmed that drilling was
performed in a satisfactory manner. Furthermore, in a qualitative
evaluation, although the evaluation was the same ".largecircle."
evaluation, but Example 2 and Example 3 shown a tendency in which a
diameter of a hole after processing was closer to a desired
dimension in comparison to Example 1.
[0088] In Comparative Example 1 in which d.sub.2/d.sub.1 was
smaller than 0.84, "Processing Progress" was "X" evaluation. This
is assumed to be because a chance for the blasting abrasives to
come into contact with the workpiece W was excessively small. In
Comparative Example 2 in which d.sub.2/d.sub.1 was greater than
0.94, all evaluations of "Diameter of hole", "Presence or Absence
of Peeling-OFF of Surface Layer", and "Presence or Absence of
Fluffing" were ".DELTA." evaluation. With regard to the ".DELTA."
evaluation, it can be said that quality deterioration has no
problem in practical use, but the quality further deteriorates in
comparison to Examples 1 to 5. In addition, in Comparative Example
3 in which d.sub.2/d.sub.1 was greater than 1 (that is,
d.sub.2>d.sub.1), evaluations of "Diameter of hole", "Presence
or Absence of Peeling-OFF of Surface Layer", and "Presence or
Absence of Fluffing" were "X" evaluation. It is assumed that when
d.sub.2/d.sub.1 increases, an effect of suppressing of a processing
area due to the opening of the resist layer is reduced, and thus a
surface layer of the workpiece W was peeled off.
[0089] (2) Influence of Nozzle Angle
[0090] In Examples 1 to 6, all were ".largecircle." evaluation, and
it was confirmed that drilling was performed in a satisfactory
manner. In Comparative Example 4 and Comparative Example 5 in which
the angle exceeded 90.degree..+-.5.degree., it could be seen that
quality deteriorates in evaluations of "Processing Progress" and
"Presence or Absence of Fluffing". With regard to "Processing
Progress", it is assumed that an inclination angle of the ejection
flow with respect to the workpiece W was great and processing
capability deteriorated, and thus quality deteriorated. With regard
to the ".DELTA." evaluation, it can be said that quality
deterioration has no problem in practical use. However, in
Comparative Example 5 in which the nozzle angle was relatively
large, evaluation was "X". In addition, with regard to "Presence or
Absence of Fluffing", it is assumed that the ejection flow flowed
along the surface of the workpiece W, and thus fluffing
occurred.
[0091] (3) Influence of Material of Resist Layer
[0092] In Example 1, Example 6, and Comparative Example 6, the same
processing conditions were set except for a material of the resist
layer. In Example 1 and Example 6 in which a main component of the
resist layer was unsaturated polyurethane, all evaluation items
were ".largecircle." evaluation, and it was confirmed that drilling
was performed in a satisfactory manner. Furthermore, in a
qualitative evaluation, although the evaluation was the same
".largecircle." evaluation. However, there was a tendency in which
the diameter of the hole after processing was closer to a desired
dimension in Example 1 in which a content rate of unsaturated
polyethylene was in a range of 50% to 70% in comparison to Example
6.
[0093] On the other hand, in Comparative Example 6 in which the
main component of the resist layer was an acrylic resin, evaluation
items of "diameter of hole", "Peeling-off", and "Fluffing" were
".DELTA." evaluation. With regard to the ".DELTA." evaluation, it
can be said that quality deterioration has no problem in practical
use. However, it was confirmed that processing accuracy was further
lowered in comparison to a case of using a resist layer in which
unsaturated polyurethane is a main component.
[0094] Hereinbefore, description has been given of the embodiments,
but various modifications can be employed without limitation to the
embodiments. For example, in the drilling method according to the
embodiment, in the step S1, the sheet 70 in which an opening is
formed in advance is disposed on the workpiece W. However, in one
embodiment, the opening 71 may be formed in the sheet 70 after
disposing the sheet 70, in which the opening 71 is not formed, on
the workpiece W.
INDUSTRIAL APPLICABILITY
[0095] In the embodiments, description has been given of drilling
with respect to the workpiece W that is constituted by glass
fiber-reinforced plastic (GFRP), but the drilling method according
to the embodiments is applicable to drilling of a workpiece W that
is constituted by all kinds of fiber-reinforced plastics such as
carbon fiber-reinforced plastic (CFRP), aramid fiber-reinforced
plastic (AFRP), dyneema fiber-reinforced plastic (DFRP), xyron
fiber-reinforced plastic, and boron fiber-reinforced plastic
(BFRP).
REFERENCE SIGNS LIST
[0096] 01: sandblast machine, 10: housing, 11: door, 12: nozzle
fixture, 13: processing table, 14: movement mechanism, 15: frame,
20: fixed-quantity supply mechanism, 30: separation mechanism, 40:
suction mechanism, 50: nozzle, 51: nozzle holder, 52: air nozzle,
53: ejecting nozzle, 60: control device, 70: sheet, 71: opening,
72: peripheral edge portion, A: ejecting region, H1: air hose, H2:
blasting abrasives hose, R: processing chamber, T: scanning
trajectory, W: workpiece.
* * * * *