(19)
(11)EP 2 881 590 A1

(12)EUROPEAN PATENT APPLICATION
published in accordance with Art. 153(4) EPC

(43)Date of publication:
10.06.2015 Bulletin 2015/24

(21)Application number: 13824768.9

(22)Date of filing:  24.07.2013
(51)International Patent Classification (IPC): 
F04D 19/04(2006.01)
(86)International application number:
PCT/JP2013/070021
(87)International publication number:
WO 2014/021160 (06.02.2014 Gazette  2014/06)
(84)Designated Contracting States:
AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR
Designated Extension States:
BA ME

(30)Priority: 01.08.2012 JP 2012171432

(71)Applicant: Edwards Japan Limited
Yachiyo-shi, Chiba 276-8523 (JP)

(72)Inventors:
  • KABASAWA, Takashi
    Yachiyo-shi Chiba 276-8523 (JP)
  • NONAKA, Manabu
    Yachiyo-shi Chiba 276-8523 (JP)

(74)Representative: Clark, Charles Robert et al
Edwards Limited Intellectual Property Manor Royal
Crawley West Sussex RH10 9LW
Crawley West Sussex RH10 9LW (GB)

  


(54)PART FOR VACUUM PUMPS AND VACUUM PUMP


(57) 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.




Description


[0001] 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.

[0002] 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.

[0003] 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.

[0004] 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.

[0005] 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.

[0006] 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.

[0007] 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.

[0008] 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.

[0009] 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.

[0010] Condition 1: the polishing amount is strictly controlled, and fibers close to the surface of the FRP cylinder are prevented from damage.

[0011] 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.

[0012] 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).

[0013] 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.

[0014] 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.

[0015] 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.

[0016] 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.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] Further, the removal processing step may include processing of removing the surface portion by blasting the fiber-reinforced composite material.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] FIG. 1 is a cross-sectional view of a vacuum pump using the present invention;

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;

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

FIG. 4 is a cross-sectional view of another vacuum pump using the present invention.



[0029] An embodiment of the present invention will be explained below in greater detail with reference to the drawings appended to the present application.

[0030] FIG. 1 is a cross-sectional view of a vacuum pump according to the present invention. A vacuum pump PI 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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.

«Detailed Configuration of Vane Degassing Unit Pt»



[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

«Explanation of Operation of vane Degassing Unit Pt»



[0053] 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.

«Detailed Configuration of Screw Groove Pump Unit Ps»



[0054] 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.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 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).

«Explanation of Operation of Screw Groove Pump Unit Ps»



[0059] 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).

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] 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.

[0068] Accordingly, the removal processing step is performed by any of the below-described methods.

[0069] (A-1) The surface portion including the parting agent layer 622 is dissolved and removed with a chemical.

[0070] 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.

[0071] (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.

[0072] 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.

[0073] (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.

[0074] 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.

[0075] (A-4) The surface portion including the parting agent layer 622 is removed by blasting the surface.

[0076] 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.

[0077] 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.

[0078] 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.

[0079] The roughening step is implemented by any of the below-described methods.

[0080] (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.

[0081] 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.

[0082] (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.

[0083] 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.

[0084] 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).

[0085] (B-3) The surface is roughened by blasting the surface 623 after the surface portion including the parting agent layer 622 has been removed.

[0086] 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).

[0087] 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.

[0088] 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.

[0089] 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.

[0090] 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.

[0091] 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.

[0092] 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.

[0093] FIG. 4 is a cross-sectional view of another vacuum pump P2 using the present invention.

[0094] 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.

[0095] 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.

[0096] 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.

[0097] 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.

[0098] 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.


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 processing of 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 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.
 
4. The vacuum pump part according to claim 1, wherein the removal processing step includes processing of 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 processing of removing the surface portion by blasting the fiber-reinforced composite material.
 
6. The vacuum pump part according to any one of claims 1 to 5, wherein the roughening step includes 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.
 
7. The vacuum pump part according to any one of claims 1 to 5, wherein the roughening step includes 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.
 
8. The vacuum pump part according to any one of claims 1 to 5, wherein the roughening step includes processing of 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 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 includes 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 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 processing of removing the surface portion by blasting the fiber-reinforced composite material,
the roughening step includes 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 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 the vacuum pump part according to any one of claims 1 to 10.
 
12. A vacuum pump comprising the vacuum pump part according to any one of claims 1 to 10.
 




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Cited references

REFERENCES CITED IN THE DESCRIPTION



This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.

Patent documents cited in the description