U.S. patent application number 14/417037 was filed with the patent office on 2015-07-02 for vacuum pump part and vacuum pump.
This patent application is currently assigned to Edwards Japan Limited. The applicant listed for this patent is Edwards Japan Limited. Invention is credited to Takashi Kabasawa, Manabu Nonaka.
Application Number | 20150184669 14/417037 |
Document ID | / |
Family ID | 50027839 |
Filed Date | 2015-07-02 |
United States Patent
Application |
20150184669 |
Kind Code |
A1 |
Kabasawa; Takashi ; et
al. |
July 2, 2015 |
VACUUM PUMP PART AND VACUUM PUMP
Abstract
Provided are a vacuum pump part and a vacuum pump suitable for
performing adequately the processing of forming a coating on the
surface of a fiber-reinforced composite material. In a vacuum pump
part, a plating layer, which is a coating serving as a coating
layer, is formed on the surface of a second cylindrical member of a
cylindrical shape which is constituted by a fiber-reinforced
composite material. The plating layer is formed through a removal
processing step for removing a surface portion including a parting
agent layer from the surface of the second cylindrical member of a
cylindrical shape, and a roughening step for roughening a surface
of the second cylindrical member after the surface portion
including the parting agent layer has been removed.
Inventors: |
Kabasawa; Takashi;
(Chiba-shi, JP) ; Nonaka; Manabu; (Chiba-shi,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Edwards Japan Limited |
Yachiyo-shi, Chiba |
|
JP |
|
|
Assignee: |
Edwards Japan Limited
Yachiyo-shi, Chiba
JP
|
Family ID: |
50027839 |
Appl. No.: |
14/417037 |
Filed: |
July 24, 2013 |
PCT Filed: |
July 24, 2013 |
PCT NO: |
PCT/JP2013/070021 |
371 Date: |
January 23, 2015 |
Current U.S.
Class: |
428/141 ; 216/83;
451/38; 451/56; 451/57; 451/59 |
Current CPC
Class: |
F05D 2300/611 20130101;
Y10T 428/24355 20150115; F05D 2300/603 20130101; F04D 29/023
20130101; F04D 29/26 20130101; B24C 1/08 20130101; F05D 2300/516
20130101; F04D 19/042 20130101; F04D 19/044 20130101 |
International
Class: |
F04D 29/02 20060101
F04D029/02; B24C 1/08 20060101 B24C001/08; F04D 29/26 20060101
F04D029/26 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 1, 2012 |
JP |
2012-171432 |
Claims
1. A vacuum pump part which is made from a fiber-reinforced
composite material provided with a coating, wherein the coating is
formed through a removal processing step for removing at least a
surface portion of the fiber-reinforced composite material, and a
roughening step for roughening a surface of the fiber-reinforced
composite material.
2. The vacuum pump part according to claim 1, wherein the removal
processing step includes removing the surface portion by dissolving
the fiber-reinforced composite material with a chemical.
3. The vacuum pump part according to claim 1, wherein the removal
processing step includes removing the surface portion by polishing
the fiber-reinforced composite material with a polishing material
in which abrasive grains are fixedly attached to a flexible base
material.
4. The vacuum pump part according to claim 1, wherein the removal
processing step includes removing the surface portion by applying
abrasive grains to a flexible base material and polishing the
fiber-reinforced composite material.
5. The vacuum pump part according to claim 1, wherein the removal
processing step includes removing the surface portion by blasting
the fiber-reinforced composite material.
6. The vacuum pump part according to claim 1, wherein the
roughening step includes roughening the surface by polishing the
fiber-reinforced composite material, from which the surface portion
has been removed, with a polishing material in which abrasive
grains are fixedly attached to a flexible base material.
7. The vacuum pump part according to claim 1, wherein the
roughening step includes roughening the surface by applying
abrasive grains to a flexible base material and polishing the
fiber-reinforced composite material, from which the surface portion
has been removed.
8. The vacuum pump part according to claim 1 wherein the roughening
step includes roughening the surface by blasting the
fiber-reinforced composite material, from which the surface portion
has been removed.
9. The vacuum pump part according to claim 1, wherein the removal
processing step includes removing the surface portion by polishing
the fiber-reinforced composite material with a polishing material
in which abrasive grains are fixedly attached to a flexible base
material, or removing the surface portion by applying abrasive
grains to a flexible base material and polishing the
fiber-reinforced composite material, the roughening step includes
roughening the surface by polishing the fiber-reinforced composite
material, from which the surface portion has been removed, with a
polishing material in which abrasive grains are fixedly attached to
a flexible base material, or processing of roughening the surface
by applying abrasive grains to a flexible base material and
polishing the fiber-reinforced composite material, from which the
surface portion has been removed, and a grain size of the abrasive
grains used in the roughening step is three or more times a grain
size of the abrasive grains used in the removal processing
step.
10. The vacuum pump part according to claim 1, wherein the removal
processing step includes removing the surface portion by blasting
the fiber-reinforced composite material, the roughening step
includes roughening the surface by blasting the fiber-reinforced
composite material, from which the surface portion has been
removed, and a grain size of a blasting material used for the
blasting in the roughening step is three or more times a grain size
of a blasting material used for the blasting in the removal
processing step.
11. A rotor for use in a vacuum pump, the rotor comprising: a
vacuum pump part which is made from a fiber-reinforced composite
material provided with a coating, wherein the coating is formed
through a removal processing step for removing at least a surface
portion of the fiber-reinforced composite material, and a
roughening step for roughening a surface of the fiber-reinforced
composite material.
12. A vacuum pump comprising: a vacuum pump part which is made from
a fiber-reinforced composite material provided with a coating,
wherein the coating is formed through a removal processing step for
removing at least a surface portion of the fiber-reinforced
composite material, and a roughening step for roughening a surface
of the fiber-reinforced composite material.
13. The rotor according to claim 11, wherein the removal processing
step includes removing the surface portion by at least one of
dissolving the fiber-reinforced composite material with a chemical,
polishing the fiber-reinforced composite material with a polishing
material in which abrasive grains are fixedly attached to a
flexible base material, applying abrasive grains to a flexible base
material and polishing the fiber-reinforced composite material, or
blasting the fiber-reinforced composite material.
14. The rotor according to claim 11, wherein the roughening step
includes roughening the surface by at least one of polishing the
fiber-reinforced composite material, from which the surface portion
has been removed, with a polishing material in which abrasive
grains are fixedly attached to a flexible base material; applying
abrasive grains to a flexible base material and polishing the
fiber-reinforced composite material, from which the surface portion
has been removed; or blasting the fiber-reinforced composite
material, from which the surface portion has been removed.
15. The rotor according to claim 11, wherein the removal processing
step includes removing the surface portion by polishing the
fiber-reinforced composite material with a polishing material in
which abrasive grains are fixedly attached to a flexible base
material, or removing the surface portion by applying abrasive
grains to a flexible base material and polishing the
fiber-reinforced composite material, the roughening step includes
roughening the surface by polishing the fiber-reinforced composite
material, from which the surface portion has been removed, with a
polishing material in which abrasive grains are fixedly attached to
a flexible base material, or processing of roughening the surface
by applying abrasive grains to a flexible base material and
polishing the fiber-reinforced composite material, from which the
surface portion has been removed, and a grain size of the abrasive
grains used in the roughening step is three or more times a grain
size of the abrasive grains used in the removal processing
step.
16. The rotor according to claim 11, wherein the removal processing
step includes removing the surface portion by blasting the
fiber-reinforced composite material, the roughening step includes
roughening the surface by blasting the fiber-reinforced composite
material, from which the surface portion has been removed, and a
grain size of a blasting material used for the blasting in the
roughening step is three or more times a grain size of a blasting
material used for the blasting in the removal processing step.
17. The vacuum pump according to claim 12, wherein the removal
processing step includes removing the surface portion by at least
one of dissolving the fiber-reinforced composite material with a
chemical, polishing the fiber-reinforced composite material with a
polishing material in which abrasive grains are fixedly attached to
a flexible base material, applying abrasive grains to a flexible
base material and polishing the fiber-reinforced composite
material, or blasting the fiber-reinforced composite material.
18. The vacuum pump according to claim 12, wherein the roughening
step includes roughening the surface by at least one of polishing
the fiber-reinforced composite material, from which the surface
portion has been removed, with a polishing material in which
abrasive grains are fixedly attached to a flexible base material;
applying abrasive grains to a flexible base material and polishing
the fiber-reinforced composite material, from which the surface
portion has been removed; or blasting the fiber-reinforced
composite material, from which the surface portion has been
removed.
19. The vacuum pump according to claim 12, wherein the removal
processing step includes removing the surface portion by polishing
the fiber-reinforced composite material with a polishing material
in which abrasive grains are fixedly attached to a flexible base
material, or removing the surface portion by applying abrasive
grains to a flexible base material and polishing the
fiber-reinforced composite material, the roughening step includes
roughening the surface by polishing the fiber-reinforced composite
material, from which the surface portion has been removed, with a
polishing material in which abrasive grains are fixedly attached to
a flexible base material, or processing of roughening the surface
by applying abrasive grains to a flexible base material and
polishing the fiber-reinforced composite material, from which the
surface portion has been removed, and a grain size of the abrasive
grains used in the roughening step is three or more times a grain
size of the abrasive grains used in the removal processing
step.
20. The vacuum pump according to claim 12, wherein the removal
processing step includes removing the surface portion by blasting
the fiber-reinforced composite material, the roughening step
includes roughening the surface by blasting the fiber-reinforced
composite material, from which the surface portion has been
removed, and a grain size of a blasting material used for the
blasting in the roughening step is three or more times a grain size
of a blasting material used for the blasting in the removal
processing step.
Description
[0001] This application is a national stage entry under 35 U.S.C.
.sctn.371 of International Application No. PCT/JP2013/070021, filed
Jul. 24, 2013, which claims the benefit of JP Application
2012-171432, filed Aug. 1, 2012. The entire contents of
International Application No. PCT/JP2013/070021 and JP Application
2012-171432 are incorporated herein by reference.
BACKGROUND
[0002] The present invention relates to a vacuum pump part for use
in a vacuum pump to be used as gas evacuation means of a process
chamber or other sealed chambers in semiconductor fabrication
devices, flat panel display production devices, and solar panel
production devices, and also relates to a vacuum pump. More
particularly, the present invention relates to a vacuum pump part
and a vacuum pump suitable for performing adequately processing of
forming a coating on the surface of a fiber-reinforced composite
material.
[0003] A vacuum pump in which a screw groove pump section is
configured by fixing a fiber reinforced plastics (FRP) cylinder,
which is a fiber-reinforced composite material, to a lower portion
of an aluminum alloy rotating vane of a turbomolecular pump is well
known as disclosed in Japanese Patent Application Publications Nos.
H7-4383 and 2004-278512.
[0004] In a vacuum pump of this type, since a corrosive gas should
be evacuated, an anticorrosive coating constituted by a nickel
alloy or the like is typically formed on the surface of various
parts to prevent them from corrosion.
[0005] However, although several inventions relating to coatings
for the rotating vanes made from aluminum alloys have been publicly
disclosed, no inventions relating to coatings on FRP cylinders can
be found.
SUMMARY
[0006] A parting agent used when molding a FRP cylinder often
adheres or fuses to the surface thereof. For this reason, the
parting agent should be removed in advance in order to ensure
strong adhesion of the coating which is a plating layer
constituting the coating material to the surface of the FRP
cylinder.
[0007] In particular, in the vacuum pump which is the object of the
present invention, the FRP cylinder should be rotated at a high
speed. Therefore, the processing of removing the parting agent
should be performed in advance in order to prevent the coating,
which is a coating material, from peeling off from the surface of
the FRP cylinder.
[0008] The parting agent that has adhered or fused to the surface
of the FRP cylinder can be removed by grinding the surface with a
grinding stone or sandpaper, or by blasting. However, where the
surface is ground too much, fibers in the FRP can be damaged and
the material strength can be reduced.
[0009] In this case, only the fibers close to the surface are
damaged and the strength of the entire material is not reduced.
Therefore, the damage is at a level producing practically no effect
in typical use. However, in the vacuum pump which is the object of
the present invention, the FRP cylinder should be rotated at a high
speed, as mentioned hereinabove, and therefore where the fibers
close to the surface of the FRP cylinder are cut, the fibers are
scattered from the cut locations, thereby causing significant
failures in the vacuum pump of this type.
[0010] Accordingly, the following conditions should be fulfilled
when removing the parting agent present on the surface of the FRP
cylinder used in the vacuum pump of this type.
[0011] Condition 1: the polishing amount is strictly controlled,
and fibers close to the surface of the FRP cylinder are prevented
from damage.
[0012] Condition 2: the FRP cylinders of this type often have a
wavy surface due to uneven winding of fibers during molding.
Therefore, the polishing should follow the surface waviness.
[0013] Condition 3: depressions and protrusions of an adequate size
should be produced on the surface of the FRP cylinder after the
parting agent has been removed in order to increase the adhesion of
the plating layer formed after the parting agent has been removed
(anchoring effect).
[0014] Where the polishing is performed with fine abrasive grains,
the polishing amount is easy to control. Therefore, Condition 1 is
fulfilled, but since surface depressions and protrusions are small,
Condition 3 is difficult to fulfill.
[0015] Further, when the polishing is performed with coarse
abrasive grains, depressions and protrusions of an adequate size
are formed on the surface. Therefore, Condition 3 is fulfilled.
However, since the polishing amount is difficult to control,
Condition 1 is difficult to fulfill.
[0016] Meanwhile, when the polishing is performed with abrasive
grains of an intermediate size, Condition 1 and Condition 3 are
difficult to fulfill and the two conditions are difficult to fulfil
at the same time.
[0017] The present invention has been created to resolve the
above-described problems, and it is an objective thereof to provide
a vacuum pump part and a vacuum pump suitable for performing
adequately the processing of forming a coating on the surface of a
fiber-reinforced composite material.
[0018] In order to attain the abovementioned objective, the present
invention provides a vacuum pump part which is made from a
fiber-reinforced composite material provided with a coating,
wherein the coating is formed through a removal processing step for
removing at least a surface portion of the fiber-reinforced
composite material, and a roughening step for roughening a surface
of the fiber-reinforced composite material.
[0019] In this case, the removal processing step may include
processing of removing the surface portion by dissolving the
fiber-reinforced composite material with a chemical.
[0020] The removal processing step may include processing of
removing the surface portion by polishing the fiber-reinforced
composite material with a polishing material in which abrasive
grains are fixedly attached to a flexible base material.
[0021] The removal processing step may include processing of
removing the surface portion by applying abrasive grains to a
flexible base material and polishing the fiber-reinforced composite
material.
[0022] Further, the removal processing step may include processing
of removing the surface portion by blasting the fiber-reinforced
composite material.
[0023] The roughening step may include processing of roughening the
surface by polishing the fiber-reinforced composite material, from
which the surface portion has been removed, with a polishing
material in which abrasive grains are fixedly attached to a
flexible base material.
[0024] The roughening step may include processing of roughening the
surface by applying abrasive grains to a flexible base material and
polishing the fiber-reinforced composite material, from which the
surface portion has been removed.
[0025] The roughening step may include processing of roughening the
surface by blasting the fiber-reinforced composite material, from
which the surface portion has been removed.
[0026] The removal processing step may include processing of
removing the surface portion by polishing the fiber-reinforced
composite material with a polishing material in which abrasive
grains are fixedly attached to a flexible base material, or
processing of removing the surface portion by applying abrasive
grains to a flexible base material and polishing the
fiber-reinforced composite material, the roughening step may
include processing of roughening the surface by polishing the
fiber-reinforced composite material, from which the surface portion
has been removed, with a polishing material in which abrasive
grains are fixedly attached to a flexible base material, or
processing of roughening the surface by applying abrasive grains to
a flexible base material and polishing the fiber-reinforced
composite material, from which the surface portion has been
removed, and a grain size of the abrasive grains used in the
roughening step may be three or more times a grain size of the
abrasive grains used in the removal processing step.
[0027] Further, the removal processing step may include processing
of removing the surface portion by blasting the fiber-reinforced
composite material, the roughening step may include processing of
roughening the surface by blasting the fiber-reinforced composite
material, from which the surface portion has been removed, and a
grain size of a blasting material used for the blasting in the
roughening step may be three or more times a grain size of a
blasting material used for the blasting of the removal processing
step.
[0028] According to the present invention, in the fiber-reinforced
composite material provided with a coating, the coating is formed
through a removal processing step for removing the surface portion
of at least the fiber-reinforced composite material, and the
roughening step for roughening the surface of the fiber-reinforced
composite material. Therefore, it is possible to provide a vacuum
pump part and a vacuum pump such that the parting agent can be
removed without damaging the fibers close to the surface of the
fiber-reinforced composite material, and a highly adhesive coating
can be formed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] FIG. 1 is a cross-sectional view of a vacuum pump using the
present invention;
[0030] FIG. 2 is a perspective view showing an extracted second
cylindrical member constituting the screw groove pump unit of the
vacuum pump depicted in FIG. 1;
[0031] FIG. 3 is an enlarged view of a partial cross section
denoted by A in the FRP cylinder depicted in FIG. 2, this view
illustrating the removal processing step and roughening step in
accordance with the present invention; and
[0032] FIG. 4 is a cross-sectional view of another vacuum pump
using the present invention.
DETAILED DESCRIPTION
[0033] An embodiment of the present invention will be explained
below in greater detail with reference to the drawings appended to
the present application.
[0034] FIG. 1 is a cross-sectional view of a vacuum pump according
to the present invention. A vacuum pump P1 depicted in the figure
is used for gas evacuation means of a process chamber or other
sealed chambers in semiconductor fabrication devices, flat panel
display production devices, and solar panel production devices.
[0035] The vacuum pump P1 has a vane degassing unit Pt for
evacuating the gas with a rotating vane 13 and a fixed vane 14, and
a screw groove pump unit Ps for evacuating the gas by using a screw
groove 19 inside an outer case 1.
[0036] The outer case 1 has an open-end cylindrical shape obtained
by integrally joining a tubular pump case 1A and an open-end pump
base 1B with bolts in the axial direction thereof. The upper end
portion of the pump case 1A is open as a gas intake port 2, and a
gas discharge port 3 is provided at the side surface of the lower
end portion of the pump base 1B.
[0037] The gas intake port 2 is connected to a sealed chamber (not
shown in the figure) which is under a high degree of vacuum, for
example, the process chamber of a semiconductor fabrication device,
by bolts (not shown in the figure) provided in a flange 1C at the
upper edge of the pump case 1A. The gas discharge port 3 is
connected so as to communicate with an auxiliary pump (not shown in
the figure). A cylindrical stator column 4 including various
electrical components is provided in the central portion inside the
pump case 1A, and the stator column 4 is provided in a vertical
condition in a state in which the lower end side thereof is fixed
by screwing into the pump base 1B.
[0038] A rotor shaft 5 is provided inside the stator column 4. The
rotor shaft 5 is disposed such that the upper end portion thereof
faces in the direction of the gas intake port 2, and the lower end
portion thereof faces in the direction of the pump base 1B. The
upper end portion of the rotor shaft 5 is provided such as to
protrude upward from the upper end surface of the cylinder of the
stator column 4.
[0039] The rotor shaft 5 is supported by radial magnetic bearings
10 and an axial magnetic bearing 11 so as to be capable of rotating
in the radial direction and axial direction. In this state, the
rotor shaft is rotationally driven by a driving motor 12.
[0040] The driving motor 12 has a structure constituted by a stator
12A and a rotor 12B and is provided substantially close to the
center of the rotor shaft 5. The stator 12A of the driving motor 12
is disposed inside the stator column 4, and the rotor 12B of the
driving motor 12 is integrally mounted on the outer circumferential
surface side of the rotor shaft 5.
[0041] A total of two radial magnetic bearings 10--a pair of radial
magnetic bearings--are provided respectively above and below the
driving motor 12, and the axial magnetic bearing 11 is disposed on
the lower end side of the rotor shaft 5.
[0042] The pair of radial magnetic bearings 10 are each constituted
by a radial electromagnet target 10A attached to the outer
circumferential surface of the rotor shaft 5, a plurality of radial
electromagnets 10B disposed on the inner surface of the stator
column 4 opposite the radial electromagnet target, and a radial
displacement sensor 10C. The radial electromagnet target 10A is
constituted by a laminated steel plate obtained by laminating steel
sheets having a high magnetic permeability. The radial
electromagnets 10B attract the rotor shaft 5 by magnetic forces in
the radial direction through the radial electromagnet target
10A.
[0043] The radial displacement sensor 10C detects the radial
displacement of the rotor shaft 5. As a result of controlling the
excitation current in the radial electromagnets 10B on the basis of
the detected value (radial displacement of the rotor shaft 5) of
the radial displacement sensor 10C, the rotor shaft 5 is supported
in a floating state by magnetic forces at a predetermined radial
position.
[0044] The axial magnetic bearing 11 is constituted by a
disk-shaped armature disk 11A attached to the outer circumference
of the lower end portion of the rotor shaft 5, axial electromagnets
11B facing each other in the vertical direction, with the armature
disk 11A being interposed therebetween, and an axial displacement
sensor 11C disposed at a position set slightly apart from the lower
end surface of the rotor shaft 5.
[0045] The armature disk 11A is constituted by a material with a
high magnetic permeability, and the upper and lower axial
electromagnets 11B attract the armature disk 11A with magnetic
forces in the vertical direction. The axial displacement sensor 11C
detects the axial displacement of the rotor shaft 5. As a result of
controlling the excitation current of the upper and lower axial
electromagnets 11B on the basis of the detection value (axial
displacement of the rotor shaft 5) of the axial displacement sensor
11C, the rotor shaft 5 is supported in a floating state by magnetic
forces at a predetermined axial position.
[0046] A rotor 6 serving as a rotating body of the vacuum pump P is
provided on the outside of the stator column 4. The rotor 6 has a
cylindrical shape surrounding the outer circumference of the stator
column 4 and a structure obtained by joining, in the axial
direction thereof, two tubular bodies (a first tubular body 61 and
a second tubular body 62) having different diameters by a round
member 60 of an annular plate shape positioned at a substantially
intermediate portion thereof.
[0047] The first cylindrical member 61 is formed from the same
material (for example, aluminum or an alloy thereof) as the round
member 60. Meanwhile, the second cylindrical member 62 is formed
from FRP.
[0048] Further, the first cylindrical member 61 is cut out by
machining or the like from an aluminum ingot or an aluminum alloy
ingot. In the composite pump P1 depicted in FIG. 1, the round
member 60 has a flange provided on the outer circumference of the
end portion of the first cylindrical member 61 and is cut out
together with the first cylindrical member 61 from the aluminum
ingot or aluminum alloy ingot.
[0049] Meanwhile, the second cylindrical member 62 is obtained by
forming separately from the round member 60 and the first
cylindrical member 61 and then joining by press fitting onto the
outer circumference of the round member 60. The second cylindrical
member 62 may be also adhesively bonded to the outer circumference
of the round member 60.
[0050] An end member 63 is provided at the upper end of the first
cylindrical member 61, and the rotor 6 and the rotor shaft 5 are
integrated through this end member 63. As an example of such an
integrated structure, in the composite pump P1 depicted in FIG. 1,
a boss hole 7 is provided in the center of the end member 63 and a
step-like shoulder (referred to hereinbelow as "rotor shaft
shoulder 9") is formed at the outer circumference of the upper end
portion of the rotor shaft 5. The rotor 6 and the rotor shaft 5 are
integrated by fitting the distal end portion of the rotor shaft 5
located above the rotor shaft shoulder 9 into the boss hole 7 of
the end member 63 and fastening and fixing the end member 63 and
the rotor shaft shoulder 9 with a bolt.
[0051] The rotor 6 constituted by the first and second cylindrical
members 61, 62 and the round member 60 is supported through the
rotor shaft 5 by the radial magnetic bearings 10 and the axial
magnetic bearing 11 to be rotatable about the central axis (rotor
shaft 5) thereof. The supported rotor 6 is rotationally driven
about the rotor shaft 5 by the rotation of the rotor shaft 5
induced by the driving motor 12.
[0052] Therefore, in the composite pump P1 depicted in the FIG. 1,
the pump support system and rotational driving system constituted
by the rotor shaft 5, radial magnetic bearings 10, axial magnetic
bearings 11, and driving motor 12 function as driving means that
rotationally drives the round member 60 and the first and second
cylindrical members 61, 62 about the center thereof.
[0053] <<Detailed Configuration of Vane Degassing Unit
Pt>>
[0054] In the composite pump P1 depicted in FIG. 1, the zone
upstream (a range from the substantially intermediate position of
the rotor 6 to the side end portion of the gas intake port 2 of the
rotor 6; same hereinbelow) of the substantially intermediate
position of the rotor 6 (more specifically, the position of the
round member 60; same hereinbelow) functions as a vane degassing
unit Pt. The detailed configuration of the vane degassing unit Pt
is described below.
[0055] The constituent portion of the rotor 6 upstream of the
substantially intermediate position of the rotor 6, that is, the
first cylindrical member 61, is a portion rotating as a rotating
body of the vane degassing unit Pt. A plurality of rotating vanes
13 is integrally provided on the outer circumferential surface of
the first cylindrical member 61. The plurality of rotating vanes 13
is radially arranged and centered on the axial center of the rotor
shaft 5 or outer case 1 (referred to hereinbelow as "axial rotor
center") which is the rotation axis of the rotor 6.
[0056] Meanwhile, a plurality of fixed vanes 14 is provided on the
inner circumferential surface side of the pump case 1A, and the
fixed vanes 14 are also arranged radially about the pump axis as a
center. The abovementioned rotating vanes 13 and stationary vanes
14 are disposed alternately in multiple stages along the pump axis,
thereby forming the vane degassing unit Pt.
[0057] Each rotating vane 13 is a blade-shaped machined part which
is formed by machining integrally with the outer-diameter machined
part of the first cylindrical member 61. The rotating vanes are
inclined at an angle optimum for discharging gas molecules. Each
fixed vane 14 is also inclined at an angle optimum for discharging
gas molecules.
[0058] <<Explanation of Operation of Vane Degassing Unit
Pt>>
[0059] In the vane degassing unit Pt of the above-described
configuration, when the driving motor 12 is started, the rotor
shaft 5, the rotor 6, and the rotating vanes 13 rotate integrally
at a high speed, and the rotating vane 13 of the uppermost stage
imparts a momentum in the direction from the gas intake port 2
toward the gas discharge port 3 side to the gas molecules entering
from the gas intake port 2. The gas molecules having the momentum
in the discharge direction are conveyed by the fixed vane 14 to the
rotating vane 13 of the next stage. As a result of the
abovementioned operations of imparting the momentum to the gas
molecules and conveying the gas molecules, the gas molecules on the
gas intake port 2 side successively move downstream of the rotor 6
and reach the upstream side of the screw groove pump unit Ps.
[0060] <<Detailed Configuration of Screw Groove Pump Unit
Ps>>
[0061] In the composite pump P1 depicted in FIG. 1, the zone
downstream (a range from the substantially intermediate position of
the rotor 6 to the end portion of the rotor 6 on the gas discharge
port 3 side; same hereinbelow) of the substantially intermediate
position of the rotor 6 functions as the screw groove pump unit Ps.
The detailed configuration of the screw groove pump unit Ps is
described hereinbelow.
[0062] The constituent portion of the rotor 6 downstream of the
substantially intermediate position of the rotor 6, that is, the
second cylindrical member 62, is a portion rotating as a rotating
member of the screw groove pump unit Ps. A tubular fixed member 18
is provided as a screw groove pump unit stator on the outer
circumference of the second cylindrical member 62. The tubular
fixed member (screw groove pump unit stator) 18 has a structure
surrounding the outer circumference of the second cylindrical
member 62. The lower end portion of the fixed member 18 is
supported by the pump base 1B.
[0063] A spiral screw groove pump channel S is provided between the
fixed member 18 and the second cylindrical member 62. In the
example depicted in FIG. 1, the configuration is used in which the
outer circumferential surface of the second cylindrical member 62
is a curved surface having no depressions or protrusions and a
spiral screw groove 19 is formed on the inner surface side of the
fixed member 18, thereby forming the spiral screw groove pump
channel S between the second cylindrical member 62 and the fixed
member 18. Alternatively, the spiral screw groove pump channel S
may be formed between the second cylindrical member 62 and the
fixed member 18 by forming the screw groove 19 in the outer
circumferential surface of the second cylindrical member 62 and
forming the inner surface side of the fixed member 18 as a curved
surface having no depressions or protrusions.
[0064] The screw groove 19 is formed such that the depth thereof
changes as a taper cone shape which decreases downward in diameter.
The screw groove 19 is also cut spirally from the top end to the
lower end of the fixed member 18.
[0065] In the screw groove pump unit Ps, the gas is transferred
while being compressed by a drag effect in the screw groove 19 and
at the outer circumferential surface of the second cylindrical
member 62. Therefore, the depth of the screw groove 19 is set to be
the largest on the upstream inlet side (opening end of the channel
which is close to the gas intake port 2) of the screw groove pump
channel S and to be the smallest on the downstream outlet side
thereof (opening end of the channel which is close to the gas
discharge port 3).
[0066] <<Explanation of Operation of Screw Groove Pump Unit
Ps>>
[0067] As explained hereinabove in <<Explanation of Operation
of Vane Degassing Unit Pt>>, the gas molecules that have
reached the upstream side of the screw groove pump unit Ps further
move into the screw groove pump channel S. As a result of the
effect generated by the rotation of the second cylindrical member
62, that is, the drag effect at the outer circumferential surface
of the second cylindrical member 62 and in the screw groove 19, the
gas molecules move toward the gas discharge port 3, while being
compressed from a transitional flow into a viscous flow and are
eventually discharged to the outside through an auxiliary pump (not
shown in the figure).
[0068] In the vacuum pump P1 of the abovementioned configuration,
the vacuum pump part of the embodiment of the present invention is
used for the second cylindrical member 62 which is a constituent
portion of the screw groove pump unit Ps.
[0069] FIG. 2 is a perspective view showing the extracted second
cylindrical member 62 constituting the screw groove pump unit Ps of
the vacuum pump depicted in FIG. 1. FIG. 3 is an enlarged view of a
partial cross section denoted by A in the FRP cylinder depicted in
FIG. 2, this view illustrating the removal processing step and
roughening step in accordance with the present invention.
[0070] In the vacuum pump depicted in FIG. 1, the second
cylindrical member 62 constituting the screw groove pump unit Ps is
formed from a fiber-reinforced composite material that uses mainly
an epoxy resin as a matrix and, for example, carbon fibers as a
reinforcing material.
[0071] In this case, reinforcing fibers 621, which are the
reinforcing material, are wound in multiple layers along the
circumferential direction of the second cylindrical member 62, as
depicted in FIG. 3A. Because of uneven winding of the reinforcing
fibers 621, the surface of the second cylindrical member 62 has a
certain waviness and is not flat.
[0072] Further, since the second cylindrical member 62 of the
present embodiment is formed by heating and pressure molding, when
the molding is removed from the mold, for example, a parting agent
layer 622 including an adhered or melted silicone parting agent is
formed on the surface of the molding, as depicted in FIG. 3A.
[0073] The parting agent layer 622 present on the surface reduces
the adhesion of the plating layer constituted, for example, by a
nickel alloy which is formed by electroless plating in the
subsequently performed coating processing.
[0074] Therefore, in the second cylindrical member 62 of the
present embodiment, a removal processing step is initially
performed to remove the surface portion including the parting agent
layer 622 depicted in FIG. 3A. FIG. 3B shows the state after the
surface portion including the parting agent layer 622 has been
removed. A surface 623 shown by a solid line is the outer surface
(front surface) of the second cylindrical member 62 after the
surface portion including the parting agent layer 622 has been
removed, and a surface 624 shown by a dot-dash line is the outer
surface of the second cylindrical member 62 before the surface
portion including the parting agent layer 622 is removed.
[0075] In the removal processing step, the removal amount of the
surface portion including the parting agent layer 622 should be
strictly controlled to prevent the removal processing from reaching
the reinforcing fibers 621 and cutting a large number of the
reinforcing fibers 621. For example, where the removal amount of
the surface portion including the parting agent layer 622 in the
removal processing step is such that the reinforcing fibers 621 are
reached and the reinforcing fibers 621 are damaged, peeling and
scattering of the reinforcing fibers 621 starts from the damaged
portions, thereby causing significant problems in the vacuum pump
of this type.
[0076] Accordingly, the removal processing step is performed by any
of the below-described methods.
[0077] (A-1) The surface portion including the parting agent layer
622 is dissolved and removed with a chemical.
[0078] An organic solvent such as "Silicon-off" produced by Sansai
Kako KK, "Silicon Cut" produced by Nichido Kagaku Kogyo Co., Ltd.,
and "e-Solve 21 Series" produced by Kaneko Chemical Co., Ltd.,
chromic acid, and permanganic acid can be used as the chemical to
be used in this method.
[0079] (A-2) The surface portion including the parting agent layer
622 is removed by polishing the surface with a polishing material
in which abrasive grains are fixedly attached to a flexible base
material.
[0080] In this case, examples of materials that can be used as the
polishing material, in which abrasive grains are fixedly attached
to a flexible base material, are as follows: (1) a polishing
material in which abrasive grains are bonded to a sponge surface;
(2) a polishing material in which abrasive grains are bonded to
Nylon nonwoven fabric; (3) a brush obtained by bundling Nylon
threads to which abrasive grains have been bonded; and (4) a flap
wheel constituted by polishing fabric bonded to abrasive grains and
provided with slits. It is preferred that grains with a size equal
to or greater than #240, for example, abrasive grains #600, be
selected for use as the aforementioned abrasive grains.
[0081] (A-3) The surface portion including the parting agent layer
622 is removed by polishing the surface by applying abrasive grains
to a flexible base material and polishing the surface.
[0082] This method is the so-called buffing. In this case, it is
preferred that grains with a size equal to or greater than #240,
for example, abrasive grains #600, be selected for use.
[0083] (A-4) The surface portion including the parting agent layer
622 is removed by blasting the surface.
[0084] The blasting, as referred to herein is a method called air
blasting in which a blasting material (grains of polishing
materials, or the like) are blown onto the surface of a product
with compressed air or projected onto the surface continuously by a
rotating vane. Steel grits, steel shots, cut wires, alumina, glass
beads, and quartz sand can be used as the blasting material. Liquid
honing in which a processing liquid with fine abrasive grains
uniformly dispersed therein is blown at a high speed onto the
product surface with compressed air can be used instead of the air
blasting.
[0085] By using any of the above-described methods (A-1) to (A-4),
it is possible to remove the parting agent layer 622, without
damaging the reinforcing fibers 921, by tracking the surface
waviness where such is present on the surface for the second
cylindrical member 62.
[0086] Where the surface portion including the parting agent layer
622 is removed from the surface of the second cylindrical member
62, as depicted in FIG. 3B, a roughening step is then executed in
which a surface 623 shown by a solid line in FIG. 3B is roughened
to obtain a surface 625 shown by a solid line in FIG. 3C.
[0087] The roughening step is implemented by any of the
below-described methods.
[0088] (B-1) The surface is roughened by polishing the surface 623
with a polishing material in which abrasive grains are fixedly
attached to a flexible base material, after the surface portion
including the parting agent layer 622 has been removed.
[0089] In this case, the following polishing materials can be used,
in the same manner as in (A-2) as the polishing material in which
abrasive grains are fixedly attached to a flexible base material:
(1) a polishing material in which abrasive grains are bonded to a
sponge surface; (2) a polishing material in which abrasive grains
are bonded to Nylon nonwoven fabric; (3) a brush obtained by
bundling Nylon threads to which abrasive grains have been bonded;
and (4) a flap wheel constituted by polishing fabric bonded to
abrasive grains and provided with slits. It is preferred that
grains with a size equal to or less than #180, for example,
abrasive grains #100, be selected for use as the aforementioned
abrasive grains.
[0090] (B-2) The surface is roughened by applying abrasive grains
to a flexible base material and polishing the surface 623 after the
surface portion including the parting agent layer 622 has been
removed.
[0091] This method is the so-called buffing and performed in the
same manner as in (A-3). It is preferred that grains with a size
equal to or less than #180, for example, abrasive grains #100, be
selected for use as the aforementioned abrasive grains.
[0092] It is preferred that the grain size of the abrasive grains
used in (B-1) or (B-2) be three or more times the grain size of the
abrasive grains used in (A-2) or (A-3).
[0093] (B-3) The surface is roughened by blasting the surface 623
after the surface portion including the parting agent layer 622 has
been removed.
[0094] This method is similar to that of (A-4), but it is preferred
that the blasting material be used which has a grain size that is
three or more times that of the blasting material used for blasting
in (A-4).
[0095] With any of the methods (B-1) to (B-3), protrusions and
depressions such as shown on the surface 625 in FIG. 3C are
effectively formed on the surface of the second cylindrical member
62, thereby roughening the surface.
[0096] A plating layer 626 which is a coating layer is formed by
electroless plating, as depicted in FIG. 3D, on the roughened
surface 625 of the second cylindrical member 62 shown by a solid
line in FIG. 3C.
[0097] The plating layer 626 strongly adheres to the surface of the
second cylindrical member 62 due to the anchor effect of the
protrusions and depressions formed on the surface 625.
[0098] In the explanation above, four methods (A-1) to (A-4) are
described as the removal processing step, and three methods (B-1)
to (B-3) are described as the roughening step, and any combination
of any of the four removal processing steps (A-1) to (A-4) with any
of the three roughening steps (B-1) to (B-3) can be used.
[0099] Further, in the embodiment, the case is explained in which
the plating layer 626 obtained by electroless plating is formed as
the coating serving as a coating layer, but the film serving as a
coating layer may be also formed by painting or the like.
[0100] In the embodiment, the case is explained in which the
present invention is applied to the composite vacuum pump having
the vane degassing unit Pt and the screw groove pump unit Ps, but
the present invention can be also similarly applied to a vacuum
pump constituted only by a screw groove pump.
[0101] FIG. 4 is a cross-sectional view of another vacuum pump P2
using the present invention.
[0102] The vacuum pump P2 shown in the figure is of a system in
which the vane degassing unit Pt of the vacuum pump P1 depicted in
FIG. 1 is omitted. The basic configuration of this vacuum pump
includes the round member 60, driving means (more specifically, a
pump support system--rotational driving system including the rotor
shaft 5, the radial magnetic bearings 10, 10, the axial magnetic
bearing 11, and the driving motor 12) for rotationally driving the
round member 60 about the center thereof, the cylindrical member 62
joined to the outer circumference of the round member 60, the fixed
member 18 serving as a screw groove pump unit stator surrounding
the outer circumference of the cylindrical member 62, and the screw
groove pump channel S formed between the cylindrical member 62 and
the fixed member 18. This configuration and the operation of
discharging the gas through the screw groove pump channel S by
rotating the round member 60 and the cylindrical member 62 are the
same as in the composite pump P1 depicted in FIG. 1. For this
reason, like members are assigned with like symbols and the
detailed explanation thereof is herein omitted.
[0103] The rotor 6 constituted by the round member 60 and the
cylindrical member 62 has the same structure as the rotor 6
depicted in FIG. 1 and is integrated with the rotor shaft 5.
[0104] The present invention can be likewise applied to the
cylindrical member 62 of the vacuum pump P2, which is depicted in
FIG. 4, in the same manner as to the second cylindrical member 62
depicted in FIG. 1.
[0105] The present invention is not limited to the above-described
embodiment, and various changes can be made by a person skilled in
the air by exercising ordinary creativity, without departing from
the technical scope of the invention.
EXPLANATION OF REFERENCE NUMERALS
[0106] 1: outer case; 1A: pump case; 1B: pump base; 1C: flange; 2:
gas intake port; 3: gas discharge port; 4: stator column; 5: rotor
shaft; 6: rotor; 60: round member; 61: first cylindrical member;
62: second cylindrical member; 63: end member; 7: boss hole; 9:
rotor shaft elbow; 10: radial magnetic bearing; 10A: radial
electromagnetic target; 10B: radial electromagnet; 10C: radial
displacement sensor; 11: axial magnetic bearing; 11A: armature
disk; 11B: axial electromagnet; 11C: axial displacement sensor; 12:
driving motor; 12A: stator; 12B: rotor; 13: rotating vane; 14:
fixed vane: 18: fixed member: 19: screw groove; P1: composite pump
(vacuum pump); P2: screw groove pump (vacuum pump); Pt: vane
degassing unit; Ps: screw groove pump unit; S: screw groove pump
channel
* * * * *