Vacuum pump, vacuum pump component, and method for manufacturing same

Abstract

Provided are a vacuum pump, a vacuum pump component, and a method for manufacturing the same, enabling effectively to heat a portion, formed of a material having low heating efficiency, in electromagnetic induction heating by electromagnetic induction heating. A vacuum pump 300 includes a casing 310, a rotor shaft 113 disposed in the casing 310, a rotor blade 102 rotatable together with the rotor shaft 113, and a heating means 340 for performing heating by electromagnetic induction by causing an alternating current to flow through a coil 342, wherein the vacuum pump 300 exhausts a gas by rotation of the rotor blade 102, and a heated portion 350 heated by the heating means 340 includes a metal plating layer 351 having magnetism.

Description

2023-024-GB 1VACUUM PUMP , VACUUM PUMP COMPONENT , AND METHOD FOR MANUFACTURING SAME[ Technical Field]

[0001] The present invention relates to a vacuum pump, a vacuum pump component , and a method for manufacturing the same .[Background Art ]

[0002] A semiconductor manufacturing apparatus , a liquid crystal manufacturing apparatus , an electron microscope , a surface analyzer, a microfabrication apparatus , or the like is required to bring the environment inside the apparatus into a highly vacuum state . A vacuum pump is used to bring the inside of these apparatuses into a highly vacuum state . Examples of vacuum pumps used include , for example , a combined pump in which a turbo molecular pump and a thread groove pump are combined .

[0003] In the vacuum pump in which the turbo molecular pump and the thread groove pump are combined, the thread groove pump is disposed on the downstream side of a turbo pump having rotor blades and stator blades alternately arranged in an axial direction . An exhaust gas taken in from an inlet port is compressed by the turbo molecular pump and the thread groove pump, and is discharged to outside of the vacuum pump from the outlet port .

[0004] Since the pressure of the exhaust gas is relatively high particularly in a downstream flow path, the exhaust gas exhibits a behavior like a viscous flow . For this reason, a byproduct is likely to precipitate at a portion where the flow of the exhaust gas is stagnant in the flow path of the vacuum pump . When the byproduct precipitates in the flow path, a phenomenon, in which a portion that is not originally in contact with the flow path comes into contact with the flow path, occurs , and the vacuum pump is damaged or a variation in temperature distribution due to a change in heat trans fer performance of an internal structure occurs , which may impair safety and productivity .

[0005] For this reason, in the vacuum pump, a heating means for heating a component forming the gas flow path may be disposed in order to suppress precipitation of the byproduct in the gas flow path . For example , PTL 1 discloses a structure in which a heating unit that heats a stator component on a stator blade side by electromagnetic induction2023-024-GB 2 heating is disposed.

[0006] The heating unit includes a yoke fixed to the stator component, a coil disposed on the yoke, and a heating plate connected to the stator component. The heating plate and the yoke are made of a magnetic material such as an iron-based material or a stainless material. When a high- frequency alternating current flows through the coil, the coil, the heating plate, and the yoke are electromagnetically coupled, and an eddy current is generated inside the heating plate and the yoke. Since the heating plate and the yoke have an inherent electrical resistance, the heating plate and the yoke generate Joule heat. In addition, iron loss heat generation occurs in the heating plate and the yoke, and copper loss heat occurs in the coil, and the stator component is also heated by these types of heat.[Citation List][Patent Literature]

[0007] [PTL 1] WO 2014 / 119191[Summary of Invention][Technical Problem]

[0008] In the vacuum pump described in PTL 1, since the component is heated by electromagnetic induction heating, it is difficult to heat the component when the component to be heated is formed of a material having low magnetism.

[0009] The present invention has been made to solve the abovedescribed problems, and an object of the present invention is to provide a vacuum pump, a vacuum pump component, and a method for manufacturing the same, enabling to effectively heat a portion, formed of a material having low heating efficiency, in electromagnetic induction heating by electromagnetic induction heating. [Solution to Problem]

[0010] The above object is achieved by the invention described in following (1) below.

[0011] (1) A vacuum pump according to the present invention includes: a casing; a rotor shaft disposed in the casing; a rotor blade rotatable together with the rotor shaft; and a heating means for performing heating by electromagnetic induction by causing an alternating current to flow through a coil, wherein the vacuum pump exhausts a gas by rotation of the2023-024-GB 3 rotor blade, and a heated portion heated by the heating means includes a metal plating layer having magnetism.[Advantageous Effects of Invention]

[0012] In the vacuum pump according to (1) , since a portion formed of a material having low heating efficiency in the electromagnetic induction heating is covered with a metal plating layer having magnetism, heating efficiency in the electromagnetic induction heating can be enhanced.

[0013] (2) In the vacuum pump according to (1) , the metal plating layer may include a first metal plating layer having magnetism and formed by electroless plating, and a second metal plating layer having magnetism and formed on the first metal plating layer by electrolytic plating. The first metal plating layer formed by electroless plating that can be uniformly plated even in a complicated shape regardless of the presence or absence of magnetism or conductivity of the plating target can improve corrosion resistance and plating adhesion. Then, with the first metal plating layer as a base, the second metal plating layer is appropriately formed by electrolytic plating in which the purity of the metal material is high but it is difficult to control the thickness. Therefore, the metal plating layer can improve heating efficiency by electromagnetic induction heating.

[0014] (3) In the vacuum pump according to (1) , the metal plating layer may have a columnar crystal structure extending in a direction away from a surface of a portion to be plated, which is covered with the metal plating layer. As a result, in the vacuum pump, an eddy current easily flows along the extending direction of the crystal structure by the electromagnetic induction of the heating means disposed in the direction away from the surface of the portion to be plated, so that the heating efficiency by the electromagnetic induction heating of the metal plating layer can be improved.

[0015] (4) In the vacuum pump according to any one of (1) to (3) , the metal plating layer may be a plating layer containing nickel as a main component. Thus, the metal plating layer can have high heating efficiency and high corrosion resistance in electromagnetic induction heating.

[0016] (5) A vacuum pump component according to the present invention is a vacuum pump component constituting a part of a gas flow path of a vacuum pump, the vacuum pump component including a metal plating layer having magnetism and heatable by electromagnetic induction, wherein the2023-024-GB 4 metal plating layer includes a first metal plating layer having magnetism and formed by electroless plating, and a second metal plating layer having magnetism and formed on the first metal plating layer by electrolytic plating . As a result , in the vacuum pump component , after the first metal plating layer is formed by electroless plating that can be uni formly plated even in a complicated shape regardless of the presence or absence of magnetism or conductivity of the plating target , the second metal plating layer can be appropriately formed by electrolytic plating with a high purity of the metal material but di f ficult to control the thickness , using the first metal plating layer as a base . Therefore , in the method for manufacturing a vacuum pump component , a portion formed of a material having low heating ef ficiency in electromagnetic induction heating can be ef fectively heated by electromagnetic induction heating .

[0017] ( 6 ) A method for manufacturing a vacuum pump component according to the present invention is a method for manufacturing a vacuum pump component constituting a part of a gas flow path of a vacuum pump, the method includes : a step of forming a first metal plating layer on a surface of a portion to be plated of the vacuum pump component by electroless plating; and a step of forming a second metal plating layer having magnetism and heatable by electromagnetic induction on a surface of the first metal plating layer by electrolytic plating . Thus , in the method for manufacturing the vacuum pump component , after the first metal plating layer is formed by electroless plating that can be uni formly plated even in a complicated shape regardless of the presence or absence of magnetism or conductivity of the plating target , the second metal plating layer can be appropriately formed by electrolytic plating with a high purity of the metal material but di f ficult to control the thickness , using the first metal plating layer as a base . Therefore , in the method for manufacturing a vacuum pump component , a portion formed of a material having low heating ef ficiency in electromagnetic induction heating can be ef fectively heated by electromagnetic induction heating .

[0018] ( 7 ) In the method for manufacturing a vacuum pump component according to ( 6 ) , a plating solution used for electrolytic plating of the second metal plating layer may not contain a brightener . As a result , since the second metal plating layer to be formed has the columnar crystal structure extending in a direction away from the surface of the2023-024-GB 5 portion to be plated, eddy current easily flows, and heating efficiency by electromagnetic induction heating can be improved.

[0019] (8) In the method for manufacturing a vacuum pump component according to (6) or (7) , at least the second metal plating layer may be subjected to a baking treatment. As a result, the second metal plating layer to be formed can eliminate the boundary of the layer that hinders the flow of the current, thereby improving the heating efficiency by electromagnetic induction heating.[Brief Description of Drawings]

[0020] [Fig. 1] Fig. 1 is a longitudinal sectional view of a vacuum pump. [Fig. 2] Fig. 2 is a circuit diagram of an amplifier circuit. [Fig. 3] Fig. 3 is a time chart illustrating control in a case where a current command value is larger than a detection value.[Fig. 4]Fig. 4 is a time chart illustrating control in a case where a current command value is smaller than a detection value. [Fig. 5] Fig. 5 is a longitudinal sectional view of a vacuum pump according to a first embodiment. [Fig. 6] Fig. 6 is an enlarged sectional view of the vicinity of a heating means and a heated portion of the vacuum pump according to the first embodiment . [Fig. 7] Fig. 7 is an enlarged sectional view illustrating the heated portion. [Fig. 8] Fig. 8 is a photograph illustrating a cross section of a metal plating layer containing a brightener formed by electrolytic plating using nickel as a main component. [Fig. 9]Fig. 9 is a photograph illustrating a cross section obtained by performing a baking treatment on the metal plating layer containing the brightener formed by electrolytic plating using nickel as a main2023-024-GB 6 component .[Fig. 10]Fig. 10 is a schematic sectional view of a metal plating layer not containing the brightener formed by electrolytic plating using nickel as a main component.[Fig. 11]Fig. 11 is a longitudinal sectional view of a vacuum pump according to a second embodiment.Fig. 11 is a perspective view illustrating a heating means.[Fig. 12]Fig. 12 is a perspective view illustrating a heating means of the vacuum pump according to a second embodiment.[Fig. 13]Fig. 13 is a schematic view illustrating a testing device.[Fig. 14]Fig. 14 is a graph illustrating a temperature of a test body with respect to a heating time in a plating evaluation test.[Fig. 15]Fig. 15 is a graph illustrating a temperature of a coil with respect to a heating time in a plating evaluation test.[Fig. 16]Fig. 16 is a graph illustrating a temperature of a test body not containing a brightener with respect to a heating time in a baking treatment temperature evaluation test.[Fig. 17]Fig. 17 is a graph illustrating a temperature of a test body containing the brightener with respect to the heating time in the baking treatment temperature evaluation test.[ Fig . 18]Fig. 18 is a graph illustrating a temperature of a test body containing a brightener with respect to a heating time in a baking treatment time evaluation test.[Fig. 19]Fig. 19 is a graph illustrating a temperature of a test body not containing the brightener with respect to the heating time in the baking treatment time evaluation test.[Description of Embodiments]2023-024-GB 7

[0021] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that dimensions of the drawings may be exaggerated and different from actual dimensions for convenience of description. Furthermore, in the present specification and the drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant description will be omitted.

[0022] A vacuum pump 100 is a turbo molecular pump 100 in which a rotating blade of a rotating body rotating at a high speed flicks gas molecules to exhaust the gas. The turbo molecular pump 100 is used, for example, to suck and exhaust gas from a chamber of a semiconductor manufacturing apparatus or the like. First, a basic configuration of the turbo molecular pump 100 will be described.

[0023] A longitudinal sectional view of this turbo molecular pump 100 is illustrated in Fig. 1. In Fig. 1, in the turbo molecular pump 100, an inlet port 101 is formed at an upper end of a cylindrical outer cylinder 127. Inside the outer cylinder 127, a rotor 103 in which a plurality of rotor blades 102 (102a, 102b, 102c, ...) , which are turbine blades for sucking and exhausting gas, are radially formed in multiple stages in a peripheral portion is provided. A rotor shaft 113 is attached to the center of the rotor 103, and the rotor shaft 113 is floated in the air, supported, and is positionally controlled by, for example, a five-axis control magnetic bearing. The rotor 103 is generally made of metal such as aluminum or an aluminum alloy.

[0024] In an upper radial electromagnet 104, four electromagnets are arranged in pairs on the X axis and the Y axis. Four upper radial sensors 107 are provided in proximity to the upper radial electromagnet 104 and corresponding to the upper radial electromagnets 104, respectively. As the upper radial sensor 107, for example, an inductance sensor having a conductive winding, an eddy current sensor, or the like is used, and the position of the rotor shaft 113 is detected on the basis of a change in inductance of the conductive winding that changes according to the position of the rotor shaft 113. This upper radial sensor 107 is configured to detect the radial displacement of the rotor shaft 113, i.e. the rotor 103 fixed thereto, and to send it to a control device 200.

[0025] In the control device 200, for example, a compensation circuit having a FID adjustment function generates an excitation control command2023-024-GB 8 signal of the upper radial electromagnet 104 on the basis of a position signal detected by the upper radial sensor 107 , and an ampli fier circuit 150 ( described later ) illustrated in Fig . 2 performs excitation control of the upper radial electromagnet 104 on the basis of the excitation control command signal , whereby the upper radial position of the rotor shaft 113 is adj usted .

[0026] The rotor shaft 113 is formed of a high-permeability material ( Iron, stainless steel , etc . ) or the like , and is attracted by the magnetic force of the upper radial electromagnet 104 . Such adj ustment is performed independently in the X axis direction and the Y axis direction . A lower radial electromagnet 105 and a lower radial sensor 108 are disposed similarly to the upper radial electromagnet 104 and the upper radial sensor 107 , and the lower radial position of the rotor shaft 113 is adj usted similarly to the upper radial position .

[0027] Further, axial electromagnets 106A and 106B are arranged with a disc-shaped metal disc 111 provided in the lower part of the rotor shaft 113 interposed therebetween in a vertical direction . The metal disc 111 is made of a high-permeability material such as iron . An axial sensor 109 is provided to detect the axial displacement of the rotor shaft 113 , and its axial position signal is configured to be sent to the control device 200 .

[0028] Then, in the control device 200 , for example , a compensation circuit having a FID adj ustment function generates an excitation control command signal of each of the axial electromagnet 106A and the axial electromagnet 106B on the basis of the axial position signal detected by the axial sensor 109 , and the ampli fier circuit 150 performs excitation control on each of the axial electromagnet 106A and the axial electromagnet 106B on the basis of these excitation control command signals , so that the axial electromagnet 106A attracts the metal disc 111 upward by magnetic force , the axial electromagnet 106B attracts the metal disc 111 downward, and the axial position of the rotor shaft 113 is adj usted .

[0029] In this manner, the control device 200 appropriately adj usts the magnetic force exerted by the axial electromagnets 106A and 106B on the metal disc 111 , magnetically floats the rotor shaft 113 in the axial direction, and holds the rotor shaft in the space in a non-contact manner . The ampli fier circuit 150 that performs excitation control on the2023-024-GB 9 upper radial electromagnet 104, the lower radial electromagnet 105, and the axial electromagnets 106A and 106B will be described later.

[0030] On the other hand, a motor 121 includes a plurality of magnetic poles arranged circumferentially so as to surround the rotor shaft 113. Each magnetic pole is controlled by the control device 200 to rotationally drive the rotor shaft 113 via an electromagnetic force acting between the magnetic pole and the rotor shaft 113. A rotational speed sensor (not illustrated) such as a Hall element, a resolver, or an encoder is incorporated in the motor 121, and the rotational speed of the rotor shaft 113 is detected by a detection signal of the rotational speed sensor .

[0031] Further, for example, a phase sensor (not illustrated) is attached in the vicinity of the lower radial sensor 108 to detect the phase of rotation of the rotor shaft 113. The control device 200 detects the position of the magnetic pole by using both the detection signals of the phase sensor and the rotational speed sensor.

[0032] A plurality of stator blades 123 (123a, 123b, 123c, ...) is disposed with a slight gap from the rotor blades 102 (102a, 102b, 102c, ...) . The rotor blades 102 (102a, 102b, 102c, ...) are each formed to be inclined by a predetermined angle from a plane perpendicular to the axis of the rotor shaft 113 in order to transfer molecules of the exhaust gas downward by collision. A stator blade 123 (123a, 123b, 123c, ...) is made of, for example, metal such as aluminum, iron, stainless steel, or copper, or metal such as an alloy containing these metals as a component.

[0033] Similarly, the stator blades 123 are formed to be inclined by a predetermined angle from a plane perpendicular to the axis of the rotor shaft 113, and are alternately arranged with the steps of the rotor blades 102 toward the inside of the outer cylinder 127. The outer peripheral end of the stator blade 123 is supported in a state of being fitted between a plurality of stacked stator blade spacers 125 (125a, 125b, 125c, . . . ) .

[0034] The stator blade spacer 125 is a ring-shaped member, and is made of, for example, a metal such as aluminum, iron, stainless steel, or copper, or a metal such as an alloy containing these metals as a component. The outer cylinder 127 is fixed to the outer periphery of the stator blade spacer 125 with a slight gap. A base portion 129 is disposed at a bottom portion of the outer cylinder 127. An outlet port 133 is2023-024-GB 10 formed in the base portion 129 and communicates with the outside . The exhaust gas having entered the inlet port 101 from the chamber (vacuum chamber ) side and trans ferred to the base portion 129 is sent to the outlet port 133 .

[0035] Furthermore , depending on the application of the turbo molecular pump 100 , a thread groove spacer 131 ( fixing member ) is disposed between a lower portion of a stator blade spacer 125 and a base portion 129 . The thread groove spacer 131 is a cylindrical member made of metal such as aluminum, copper, stainless steel , iron, or an alloy containing these metals as a component , and a plurality of spiral thread grooves 131a are engraved on an inner peripheral surface thereof . The direction of the spiral of the thread groove 131a is a direction in which molecules of the exhaust gas are trans ferred toward an outlet port 133 when the molecules move in the rotation direction of the rotor 103 . A cylindrical portion 102d is suspended from a lowermost portion of the rotor 103 following a rotor blade 102 ( 102a, 102b, 102c, . . . ) . An outer peripheral surface of the cylindrical portion 102d has a cylindrical shape and protrudes toward the inner peripheral surface of the thread groove spacer 131 , and is close to the inner peripheral surface of the thread groove spacer 131 with a predetermined gap amount . The exhaust gas trans ferred to the thread groove 131a by the rotor blade 102 and the stator blade 123 is guided by the thread groove 131a and sent to the base portion 129 .

[0036] The base portion 129 is a disc-shaped member constituting a base portion of the turbo molecular pump 100 , and is generally made of metal such as iron, aluminum, or stainless steel . Since the base portion 129 physically holds the turbo molecular pump 100 and also has a function of a heat conduction path, it is desirable to use a rigid metal having high thermal conductivity such as iron, aluminum, or copper .

[0037] In the configuration, when the rotor blades 102 are rotationally driven together with the rotor shaft 113 by the motor 121 , the exhaust gas is sucked from the chamber through the inlet port 101 by the action of the rotor blades 102 and the stator blades 123 . A rotation speed of the rotor blade 102 is usually 20 , 000 rpm to 90 , 000 rpm, and a peripheral speed at a distal end of the rotor blade 102 reaches 200 m / s to 400 m / s . The exhaust gas sucked from the inlet port 101 passes between the rotor blades 102 and the stator blades 123 and is trans ferred to the2023-024-GB 11 base portion 129 . At this time , the temperature of the rotor blade 102 increases due to frictional heat generated when the exhaust gas comes into contact with the rotor blade 102 , conduction of heat generated by the motor 121 , and the like , but this heat is transmitted to the stator blade 123 side by radiation, conduction by gas molecules of the exhaust gas , or the like .

[0038] The stator blade spacers 125 are j oined to each other at the outer peripheral portion, and transmit heat received by the stator blades 123 from the rotor blades 102 , frictional heat generated when the exhaust gas comes into contact with the stator blades 123 , and the like to the outside .

[0039] In the above description, the thread groove spacer 131 is disposed on the outer periphery of the cylindrical portion 102d of the rotor 103 , and the thread groove 131a is engraved on the inner peripheral surface of the thread groove spacer 131 . However, conversely, a thread groove may be engraved on the outer peripheral surface of the cylindrical portion 102d, and a spacer having a cylindrical inner peripheral surface may be disposed around the thread groove .

[0040] In addition, depending on the application of the turbo molecular pump 100 , the periphery of the electric unit is covered with a stator column 122 so that the gas sucked from the inlet port 101 does not enter the electric unit including the upper radial electromagnet 104 , the upper radial sensor 107 , the motor 121 , the lower radial electromagnet 105 , the lower radial sensor 108 , the axial electromagnets 106A and 106B, the axial sensor 109 , and the like , and the inside of the stator column 122 may be kept at a predetermined pressure by the purge gas .

[0041] In this case , a pipe, which is not illustrated, is disposed in the base portion 129 , and the purge gas is introduced through the pipe . The introduced purge gas is delivered to the outlet port 133 through a gap between a protection bearing 120 and the rotor shaft 113 , between the rotor and the stator of the motor 121 , and between the stator column 122 and the inner circumferential side of the rotor blade 102 and the stator column 122 and the base portion 129 .

[0042] Here , the turbo molecular pump 100 requires identi fication of a model and control on the basis of individual adj usted unique parameter( for example , various characteristics corresponding to the model ) . In order to store this control parameter, the turbo molecular pump 1002023-024-GB 12 includes an electronic circuit unit 141 in its main body . The electronic circuit unit 141 includes a semiconductor memory such as an EEP-ROM, electronic components such as a semiconductor element for accessing the semiconductor memory, a substrate 143 for mounting the semiconductor memory, and the like . The electronic circuit unit 141 is accommodated in a lower portion of a rotational speed sensor (not illustrated) , for example , in the vicinity of the center of the base portion 129 constituting the lower portion of the turbo molecular pump 100 , and is closed by an airtight bottom lid 145 .

[0043] Incidentally, in the process of manufacturing a semiconductor, some process gases introduced into the chamber have a property of becoming solid when the pressure thereof becomes higher than a predetermined value or the temperature thereof becomes lower than a predetermined value . Inside the turbo molecular pump 100 , the pressure of the exhaust gas is the lowest at the inlet port 101 and the highest at the outlet port 133 . When the pressure of the process gas becomes higher than a predetermined value or the temperature of the process gas becomes lower than a predetermined value while the process gas is being trans ferred from the inlet port 101 to the outlet port 133 , the process gas becomes solid and adheres and accumulates inside the turbo molecular pump 100 .

[0044] For example , in a case where S1C14 is used as a process gas in an Al etching apparatus , it can be seen from the vapor pressure curve that a solid product ( e . g . , A1C13 ) is precipitated at low vacuum ( 760 [ torr ] to 10-2 [ torr ] ) and low temperature ( about 20 [ ° C ] ) , adheres inside the turbo molecular pump 100 . As a result , when a precipitate of the process gas is deposited inside the turbo molecular pump 100 , the deposit narrows the pump flow path and causes a decrease in performance of the turbo molecular pump 100 . Then, the product described above is likely to solidi fy and adhere in the vicinity of the outlet port 133 or in the vicinity of the thread groove spacer 131 at a portion where the pressure is high .

[0045] Therefore , in order to solve this problem, conventionally, a heater (not illustrated) or an annular water cooling tube 149 is wound around the outer periphery of the base portion 129 or the like , and a temperature sensor ( for example , a thermistor ) (not illustrated) is embedded in the base portion 129 , and control of heating of the heater or2023-024-GB 13 cooling by the water cooling tube 149 (hereinafter referred to as temperature management system ( TMS ) ) is performed so as to keep the temperature of the base portion 129 at a constant high temperature ( set temperature ) on the basis of a signal of the temperature sensor .

[0046] Next , with regard to the turbo molecular pump 100 configured as described above , the ampli fier circuit 150 for performing excitation control on the upper radial electromagnet 104 , the lower radial electromagnet 105 , and the axial electromagnets 106A and 106B will be described . A circuit diagram of the ampli fier circuit 150 is illustrated in Fig . 2 .

[0047] In Fig . 2 , one end of an electromagnet winding 151 constituting the upper radial electromagnet 104 and the like is connected to a positive electrode 171a of a power supply 171 via a transistor 161 , and the other end thereof is connected to a negative electrode 171b of the power supply 171 via a current detection circuit 181 and a transistor 162 . The transistors 161 and 162 are so-called power MOSFETs , and have a structure in which a diode is connected between the source and the drain .

[0048] At this time , in the transistor 161 , a cathode terminal 161a of the diode is connected to the positive electrode 171a, and an anode terminal 161b is connected to one end of the electromagnet winding 151 . In the transistor 162 , a cathode terminal 162a of the diode is connected to the current detection circuit 181 , and an anode terminal 162b is connected to the negative electrode 171b .

[0049] On the other hand, a current regeneration diode 165 has a cathode terminal 165a connected to one end of the electromagnet winding 151 and an anode terminal 165b connected to the negative electrode 171b . Similarly, a cathode terminal 166a of a current regeneration diode 166 is connected to the positive electrode 171a, and an anode terminal 166b thereof is connected to the other end of the electromagnet winding 151 via the current detection circuit 181 . The current detection circuit 181 includes , for example , a current sensor of a Hall sensor type or an electric resistance element .

[0050] The ampli fier circuit 150 configured as described above corresponds to one electromagnet . Therefore , in a case where the magnetic bearings are controlled by five axes and the total number of the electromagnets 104 , 105 , 106A, and 106B is 10 , a similar ampli fier circuit 150 is configured for each of the electromagnets , and ten2023-024-GB 14 ampli fier circuits 150 are connected in parallel to the power supply 171 .

[0051] Furthermore , an ampli fier control circuit 191 includes , for example , a digital signal processor unit (hereinafter, referred to as a DSP unit ) not illustrated in the drawing of the control device 200 , and the ampli fier control circuit 191 switches on / of f of the transistors 161 and 162 .

[0052] The ampli fier control circuit 191 compares a current value detected by the current detection circuit 181 ( a signal reflecting the current value is referred to as a current detection signal 191c ) with a predetermined current command value . The magnitude (pulse width times Tpl and Tp2 ) of the pulse width generated in a control cycle Ts that is one cycle of the PWM control is determined on the basis of the comparison result . As a result , gate drive signals 191a and 191b having the pulse widths are output from the ampli fier control circuit 191 to the gate terminals of the transistors 161 and 162 .

[0053] Note that it is necessary to control the position of the rotor 103 at a high speed and with a strong force when the rotor 103 passes through the resonance point during acceleration operation of the rotational speed of the rotating body, when a disturbance occurs during constant speed operation, or the like . Therefore , a voltage of , for example , about 50 V is used as the power supply 171 so that the current flowing through the electromagnet winding 151 can be rapidly increased ( or decreased) . In addition, a capacitor is usually connected between the positive electrode 171a and the negative electrode 171b of the power supply 171 in order to stabili ze the power supply 171 (not illustrated) .

[0054] In such a configuration, when both the transistors 161 and 162 are turned on, the current (hereinafter, referred to as electromagnet current iL ) flowing through the electromagnet winding 151 increases , and when both are turned of f , the electromagnet current iL decreases .

[0055] In addition, when one of the transistors 161 and 162 is turned on and the other is turned of f , a so-called flywheel current is held . Then, by causing the flywheel current to flow through the ampli fier circuit 150 in this manner, the hysteresis loss in the ampli fier circuit 150 can be reduced, and the power consumption of the entire circuit can be suppressed low . By controlling the transistors 161 and 162 in this manner, high-frequency noise such as harmonics generated in the turbo molecular pump 100 can be reduced . Furthermore , the electromagnet current2023-024-GB 15 iL flowing through the electromagnet winding 151 can be detected by measuring the flywheel current with the current detection circuit 181 .

[0056] That is , in a case where the detected current value is smaller than the current command value , as illustrated in Fig . 3 , only once in the control cycle Ts ( for example , 100 ps ) , both the transistors 161 and 162 are turned on by the time corresponding to the pulse width time Tpl . Therefore , the electromagnetic current iL during this period increases toward a current value iLmax (not illustrated) that can flow from the positive electrode 171a to the negative electrode 171b via the transistors 161 and 162 .

[0057] On the other hand, in a case where the detected current value is larger than the current command value , as illustrated in Fig . 4 , both the transistors 161 and 162 are turned of f only once in the control cycle Ts for the time corresponding to the pulse width time Tp2 . Therefore , the electromagnet current iL during this period decreases toward a current value iLmin (not illustrated) that can be regenerated from the negative electrode 171b to the positive electrode 171a via the diodes 165 and 166 .

[0058] In either case , either one of the transistors 161 and 162 is turned on after the pulse width times Tpl and Tp2 elapse . Therefore , during this period, the flywheel current is held in the ampli fier circuit 150 .

[0059] <First Embodiment>Next , a vacuum pump 300 according to a first embodiment will be described .

[0060] As illustrated in Figs . 5 to 7 , the vacuum pump 300 includes a casing 310 that forms an outer shell of the vacuum pump 300 , a rotor shaft 113 rotatably disposed inside the casing 310 , a stator column 122 surrounding an electric unit , a magnetic bearing 320 supporting the rotor shaft 113 , a motor 121 that rotates the rotor shaft 113 , a plurality of stages of rotor blades 102 that are fixed to the rotor shaft 113 and are rotatable together with the rotor shaft 113 , a plurality of stages of stator blades 123 that are fixed to the casing 310 and are disposed between the rotor blades 102 , a heating means 340 that heats a gas flow path in the vacuum pump 300 , and a heated portion 350 that is fixed to the rotor blades 102 by plating .

[0061] The heating means 340 heats the heated portion 350 in a noncontact manner by electromagnetic induction by causing an alternating2023-024-GB 16 current to flow through a coil . As illustrated in Figs . 5 and 6 , the heating means 340 includes a cylindrical high-permeability magnetic body341 that covers an outer peripheral surface of the stator column 122 ( stator component ) surrounding the electric unit , and a coil 342 disposed so as to wind the outer peripheral surface of the high-permeability magnetic body 341 .

[0062] The high-permeability magnetic body 341 is a cylindrical member, and the coil 342 is wound around a surface on a side where the heated portion 350 is disposed, that is , a front surface 344 which is an outer peripheral surface . An upstream end portion of the high- permeability magnetic body 341 is preferably located upstream of the upstream end portion of the coil 342 from the viewpoint of suppressing magnetic flux leakage of the coil 342 . A downstream end portion of the high-permeability magnetic body 341 is preferably located downstream of a downstream end portion of the coil 342 . The high-permeability magnetic body 341 may have a recessed portion for accommodating the coil 342 . The coil 342 is disposed in the gas flow path . That is , the coil 342 is disposed under high vacuum in the gas flow path .

[0063] The high-permeability magnetic body 341 covers a side opposite to the front surface 344 side on which the heated portion 350 of the coil342 is disposed . A thickness of the high-permeability magnetic body 341 is not particularly limited, and is , for example , about 1 mm to 2 mm, but may be less than 1 mm or 2 mm or more .

[0064] The high-permeability magnetic body 341 is a soft magnetic body having high permeability, and is a magnetic ceramic that is less likely to conduct electricity than a metal magnetic material . The high- permeability magnetic body 341 is , for example , ferrite which is a magnetic oxide containing ferric oxide as a main component and is preferably Mn-Zn ferrite which is soft magnetic ferrite containing manganese and zinc or Ni-Zn ferrite which is soft magnetic ferrite containing nickel and zinc . The high-permeability magnetic body 341 is more preferably Mn-Zn ferrite .

[0065] The coil 342 is formed by winding a wire formed of a good conductor ( for example , copper ) a plurality of times and forming at least one layer ( a plurality of layers in the present embodiment ) . The coil 342 may be configured by arranging a plurality of coils in parallel .

[0066] The heated portion 350 is , for example , a portion in which an2023-024-GB 17 inner peripheral surface (portion to be plated) of a substantially cylindrical portion of the rotor blade 102 is covered by plating . The heated portion 350 is heated by electromagnetic induction by the heating means 340 .

[0067] The heated portion 350 includes a metal plating layer 351 having magnetism and formed on the rotor blade 102 by plating . The metal forming the metal plating layer 351 is a nickel that is a conductor having magnetism and can be plated, but is not particularly limited as long as the metal has magnetism and is a conductor that can be plated . The metal plating layer 351 may be formed by electroless plating using a chemical reaction or may be formed by electrolytic plating using electrolysis .

[0068] The metal plating layer 351 may be formed of one layer, or may have a plurality of layers having di f ferent properties . For example , as illustrated in Fig . 7 , the metal plating layer 351 may include a first metal plating layer 352 that is coated on the surface of the rotor blade 102 by plating, and a second metal plating layer 353 that is coated on the surface of the first metal plating layer 352 by plating and has properties dif ferent from those of the first metal plating layer 352 . A thickness of the metal plating layer 351 ( in particular, the second metal plating layer 353 ) is preferably a certain thickness in order to improve heating ef ficiency by electromagnetic induction heating, and is , for example , 30 pm to 200 pm, more preferably 50 pm to 150 pm .

[0069] The first metal plating layer 352 is formed by electroless plating . In the electroless plating, metal can be uni formly plated even in a complicated shape regardless of the presence or absence of magnetism or conductivity of the portion to be plated . Therefore , for example , even when the rotor blade 102 , which is the portion to be plated, is formed of an aluminum alloy or the like having low magnetism and low conductivity, the surface of the rotor blade 102 can be uni formly coated with the first metal plating layer 352 .

[0070] The second metal plating layer 353 is formed by electrolytic plating on the surface of the first metal plating layer 352 formed by electroless plating . The electrolytic plating has high metal purity, but is di f ficult to control the film thickness . Moreover, the electrolytic plating cannot be performed on a material having low magnetism or conductivity . The second metal plating layer 353 formed by electrolytic2023-024-GB 18 plating of the present embodiment can be formed by using the first metal plating layer 352 formed by electroless plating as a base for a portion to be plated having low conductivity .

[0071] The metal plating layer 351 may or may not contain a brightener that gives gloss to the surface . The brightener is , for example , a butynediol additive or a saccharin additive .

[0072] The metal plating layer 351 may or may not contain a pit inhibitor that prevents formation of pits . The pit inhibitor is , for example , a coumarin-based additive or a butynediol-based additive .

[0073] When a plating solution used for electrolytic plating does not contain a brightener, the metal of the metal plating layer 351 ( in particular, the second metal plating layer 353 ) to be formed forms a columnar crystal structure in a direction perpendicular to the surface of the portion to be plated ( the rotor blade 102 in the present embodiment ) as illustrated in Fig . 10 . Meanwhile , when the plating solution used for electrolytic plating contains a brightener, the metal of the metal plating layer 351 ( in particular, the second metal plating layer 353 ) forms a layered crystal structure in a direction parallel to the surface of the portion to be plated as in a photograph illustrated in Fig . 8 .

[0074] The metal plating layer 351 containing a brightener is likely to be formed in a multilayer shape , and thus , a current is less likely to flow in a direction in which the layers overlap, and there is a possibility that heating ef ficiency by electromagnetic induction heating is reduced .

[0075] The metal plating layer 351 may be subj ected to a baking treatment . The baking treatment of the metal plating layer 351 formed of nickel is performed, for example , by heating at 150 ° C to 300 ° C for 30 minutes to 180 minutes . The metal plating layer 351 containing a brightener and a pit inhibitor is likely to form a layered crystal structure in a direction parallel to the surface of the portion to be plated as described above , but it is considered that the separated layers are likely to be bonded to each other by performing the baking treatment as in a photograph illustrated in Fig . 9 . For this reason, it is considered that the metal plating layer 351 containing the brightener is likely to cause an eddy current to flow by the baking treatment , and the heating ef ficiency by electromagnetic induction heating is improved .

[0076] Next , the operation of the vacuum pump 300 according to the2023-024-GB 19 first embodiment will be described.

[0077] In the vacuum pump 300 according to the first embodiment, when the rotor blade 102 rotates, the heated portion 350 coated on the rotor blade 102 by plating rotates. In this state, when a high-frequency alternating current flows through the stationary coil 342, the coil 342, the high-permeability magnetic body 341, and the heated portion 350 are electromagnetically coupled, and an eddy current is generated inside the heated portion 350. The frequency of the alternating current to be applied is, for example, 20 kHz to 60 kHz, but may be a frequency different from these frequencies. The voltage is, for example, 100 V to 300 V, but is not limited thereto. Since the heated portion 350 has a certain thickness (for example, about 100 pm) , Joule heat is generated by eddy currents and iron loss heat is generated. Therefore, the heated portion 350 has a high temperature, and the rotor blade 102 including the heated portion 350 can be heated. Therefore, the heating means 340 can efficiently heat the rotor blade 102 by the coil 342 disposed on the fixed side. Note that the high-permeability magnetic body 341 hardly allows electricity to pass therethrough, and thus does not generate Joule heat due to eddy current. Furthermore, since the coil 342 is disposed on the outer peripheral surface of the high-permeability magnetic body 341, magnetic flux leakage of the coil 342 is suppressed as illustrated in Fig. 6. Therefore, it is possible to prevent the metal material (the stator column 122 in the present embodiment) located on a radially inner side of the high-permeability magnetic body 341 from generating heat due to Joule heat or loss. Therefore, the heating means 340 can efficiently heat the heated portion 350.

[0078] The heated portion 350 is coated on the rotor blade 102 by plating. As a result, the vacuum pump 300 can effectively heat the rotor blade 102 that is difficult to heat from the outside.

[0079] As described above, the vacuum pump 300 according to the first embodiment includes the casing 310, the rotor shaft 113 disposed in the casing 310, the rotor blade 102 rotatable together with the rotor shaft 113, and the heating means 340 for performing heating by electromagnetic induction by causing an alternating current to flow through the coil 342, and the vacuum pump 300 exhausts a gas by rotation of the rotor blade 102, and the heated portion 350 heated by the heating means 340 includes the metal plating layer 351 having magnetism. As a result, in the vacuum2023-024-GB 20 pump 300 , since a portion formed of a material having low heating ef ficiency in electromagnetic induction heating is covered with the metal plating layer 351 having magnetism, heating ef ficiency in electromagnetic induction heating can be enhanced .

[0080] Moreover, the metal plating layer 351 may include a first metal plating layer 352 having magnetism and formed by electroless plating, and a second metal plating layer 353 having magnetism and formed on the first metal plating layer 352 by electrolytic plating . The first metal plating layer 352 formed by electroless plating that can be uni formly plated even in a complicated shape regardless of the presence or absence of magnetism or conductivity of the plating target can improve corrosion resistance and plating adhesion . Then, with the first metal plating layer 352 as a base , the second metal plating layer 353 is appropriately formed by electrolytic plating in which the purity of the metal material is high but it is di fficult to control the thickness . Thus , the metal plating layer 351 can improve heating ef ficiency by electromagnetic induction heating .

[0081] The metal plating layer 351 may have a columnar crystal structure extending in a direction away from the surface of the portion to be plated coated with the metal plating layer 351 . As a result , in the vacuum pump 300 , an eddy current easily flows along the extending direction of the crystal structure by the electromagnetic induction of the heating means 340 disposed in the direction away from the surface of the portion to be plated, so that the heating ef ficiency by the electromagnetic induction heating of the metal plating layer 351 can be improved .

[0082] The metal plating layer 351 may be a plating layer containing nickel as a main component . Thus , the metal plating layer 351 can have high heating ef ficiency and high corrosion resistance in electromagnetic induction heating .

[0083] The vacuum pump component ( for example , the rotor blade 102 ) in the present embodiment is a vacuum pump component constituting a part of the gas flow path of the vacuum pump 300 , and the vacuum pump component includes the metal plating layer 351 having magnetism and heatable by electromagnetic induction, and the metal plating layer 351 includes the first metal plating layer 352 having magnetism and formed by electroless plating, and the second metal plating layer 353 having magnetism and2023-024-GB 21 formed on the first metal plating layer 352 by electrolytic plating . As a result , in the vacuum pump component , after the first metal plating layer 352 is formed by electroless plating that can be uni formly plated even in a complicated shape regardless of the presence or absence of magnetism or conductivity of the plating target , the second metal plating layer 353 can be appropriately formed by electrolytic plating with a high purity of the metal material but di f ficult to control the thickness , using the first metal plating layer 352 as a base . Therefore , in the method for manufacturing a vacuum pump component , a portion formed of a material having low heating ef ficiency in electromagnetic induction heating can be ef fectively heated by electromagnetic induction heating .

[0084] The method for manufacturing a vacuum pump component according to the present embodiment is a method for manufacturing a vacuum pump component constituting a part of a gas flow path of the vacuum pump 300 , and the method includes forming the first metal plating layer 352 on a surface of a portion to be plated of the vacuum pump component by electroless plating, and forming the second metal plating layer 353 having magnetism and heatable by electromagnetic induction on a surface of the first metal plating layer 352 by electrolytic plating . As a result , in the method for manufacturing the vacuum pump component , after the first metal plating layer 352 is formed by electroless plating that can be uni formly plated even a complicated shape regardless of the presence or absence of magnetism or conductivity of the portion to be plated, the second metal plating layer 353 can be appropriately formed by electrolytic plating with a high purity of the metal material but di f ficult to control the thickness , using the first metal plating layer 352 as a base . Therefore , in the method for manufacturing a vacuum pump component , a portion formed of a material having low heating ef ficiency in electromagnetic induction heating can be ef fectively heated by electromagnetic induction heating .

[0085] In the method for manufacturing a vacuum pump component , the plating solution used for electrolytic plating of the second metal plating layer 353 may not contain a brightener . As a result , since the second metal plating layer 353 to be formed has a columnar crystal structure extending in a direction away from the surface of the portion to be plated, eddy current easily flows , and heating ef ficiency by electromagnetic induction heating can be improved .2023-024-GB 22

[0086] In the method for manufacturing a vacuum pump component, at least the second metal plating layer 353 may be subjected to a baking treatment. As a result, the second metal plating layer 353 to be formed can eliminate the boundary of the layer that hinders the flow of the eddy current, thereby improving the heating efficiency by electromagnetic induction heating.

[0087] <Second Embodiment>Next, a vacuum pump 400 according to a second embodiment will be described. As illustrated in Figs. 11 and 12, the second embodiment is different from the first embodiment in that a heating means 440 for heating a gas flow path in the vacuum pump 400 and a heated portion 450 are disposed in a casing 410 forming an outer shell of the vacuum pump 400.

[0088] The casing 410 is formed of a plurality of stator components. Specifically, the casing 410 includes an upper case 411, a lower case 412, and a base portion 129. The casing 410 further includes a heater spacer 430 and a thread groove spacer 131 inside the lower case 412. The casing 410 has a substantially cylindrical shape with the base portion 129 as a bottom portion, and various interior parts are installed in an internal space of the casing. These components are coaxially disposed and integrally connected by a fastening member such as a bolt. In the present embodiment, the stator component heated by the heating means 440 is the thread groove spacer 131, but is not limited to the thread groove spacer 131, and may be another stator component. In addition, the stator blade 123 can also be a stator component heated by the heating means 440.

[0089] An inlet port 101 is disposed on an upstream side (intake side) of the upper case 411, and an outlet port 133 is disposed in the heater spacer 430 on an upstream side of the base portion 129.

[0090] The lower case 412 is formed in a cylindrical shape, and is provided away from the heater spacer 430 so as to cover the outer peripheral surface of the heater spacer 430.

[0091] The heater spacer 430 is disposed to heat the thread groove spacer 131. The heater spacer 430 is formed in a substantially cylindrical shape and is disposed inside the lower case 412. The heater spacer 430 is disposed between the stator blade spacer 125 and the base portion 129 in an axial direction.

[0092] The heater spacer 430 has a substantially cylindrical shape,2023-024-GB 23 and has a ring-shaped first recessed portion 431 for disposing the heating means 440 on a surface facing the upstream side ( intake side ) in contact with the thread groove spacer 131 .

[0093] The heating means 440 includes a high-permeability magnetic body 441 disposed in the first recessed portion 431 and a coil 442 disposed adj acent to the high-permeability magnetic body 441 .

[0094] The high-permeability magnetic body 441 is a ring-shaped member disposed in the first recessed portion 431 , and has a recessed housing portion 445 extending in the circumferential direction on a front surface 444 which is a surface on a side where the heated portion 450 is disposed . The housing portion 445 can house the coil 442 . The housing portion 445 includes a first wall surface 446 located on an inner peripheral side of the coil 442 to be housed, a second wall surface 447 located on an outer peripheral side of the coil 442 , and a housing surface 448 facing the heated portion 450 between the first wall surface 446 and the second wall surface 447 . In the housing portion 445 , a hole or a groove for introducing a metal wire of the coil 442 from the outside is formed from the outer surface .

[0095] The heated portion 450 is formed by plating so as to cover a part of the thread groove spacer 131 forming the gas flow path . The heated portion 450 is disposed so as to cover the housing portion 445 of the high-permeability magnetic body 441 . The heated portion 450 is formed by plating on a surface of the thread groove spacer 131 on the downstream side ( intake side ) in contact with the heater spacer 430 . The heated portion 450 is formed to have a substantially constant thickness corresponding to the shape of the housing portion 445 of the high- permeability magnetic body 441 . The heated portion 450 is separated from the front surface 444 of the housing portion 445 by a minute distance . The heated portion 450 has a metal plating layer 351 as in the first embodiment .

[0096] Next , the operation of the vacuum pump 400 according to the second embodiment will be described .

[0097] When a high- frequency alternating current flows through the coil 442 , the coil 442 , the high-permeability magnetic body 441 , and the heated portion 450 are electromagnetically coupled, and an eddy current is generated inside the heated portion 450 . The frequency of the alternating current to be applied is , for example , 20 kHz to 60 kHz , but2023-024-GB 24 may be a frequency di f ferent from these frequencies . The voltage is , for example , 100 V to 300 V, but is not limited thereto . Since the heated portion 450 has a unique electrical resistance , Joule heat is generated by an eddy current . The heated portion 450 also generates iron loss heat . Therefore , the heated portion 450 has a high temperature , and the thread groove spacer 131 can be heated .

[0098] In the second embodiment , the installation position of the coil 342 is on the vacuum side , but may be on the atmosphere side . Considering that a countermeasure for discharging the coil 342 when disposed on the vacuum side is necessary, the air side is preferable , but the present invention is not limited thereto .

[0099] <Plating Evaluation Test>A plurality of test bodies were prepared, and a test for evaluating heating ef ficiency by electromagnetic induction heating was performed . A first metal plating layer 352 of nickel having a thickness of about 8 pm as a base was formed by electroless plating on one surface of an aluminum (A5083 ) plate material having a side length of 200 mm and a thickness of 10 mm, and a second metal plating layer 353 of nickel having a thickness of about 100 pm containing a brightener was formed by electrolytic plating on the surface of the first metal plating layer 352 to obtain a test body 1 .

[0100] The same structure as that of the test body 1 was subj ected to a baking treatment at 300 ° C for 2 hours to obtain a test body 2 .

[0101] A first metal plating layer 352 of nickel having a thickness of about 8 pm as a base was formed by electroless plating on one surface of an aluminum alloy (A5083 ) plate material having a side of 200 mm and a thickness of 10 mm, and a second metal plating layer 353 of nickel having a thickness of about 100 pm not containing a brightener was formed by electrolytic plating on the surface of the first metal plating layer 352 to obtain a test body 3 .

[0102] A metal plating layer 351 of nickel having a thickness of about 100 pm was formed by electroless plating on one surface of an aluminum alloy (A5083 ) plate material having a side of 200 mm and a thickness of 10 mm and was subj ected to a baking treatment at 300 ° C for 2 hours to obtain a test body 4 .

[0103] A plate material made of an aluminum alloy (A5083 ) having a side of 200 mm and a thickness of 10 mm was used as a reference test body2023-024-GB 255. The aluminum alloy (A5083) is an example of a metal material having low magnetism.

[0104] A plate material made of stainless steel (SUS430) having a side of 200 mm and a thickness of 10 mm was used as a reference test body 6. The stainless steel (SUS430) is an example of a metal material having high magnetism.

[0105] The test was performed by a testing device 500 illustrated in Fig. 13. The testing device 500 included a 100 V AC power supply 501, a first ammeter 502, a transformer 503, a second ammeter 504, an TH power supply 505, an oscilloscope 506, a heating means 507, a first thermometer 508, and a second thermometer 509.

[0106] The TH power supply 505 included an output board 510 that outputs a high frequency current for performing electromagnetic induction heating, and a control board 511 that controls the TH power supply 505.

[0107] The heating means 507 was a portion for heating the test body, and included a coil 513 connected to the output board 510 of the TH power supply 505, and a ferrite high-permeability magnetic body 514 having a ring shape and having a groove for accommodating the coil 513 formed on an upper surface thereof.

[0108] The transformer 503 was disposed between the AC power supply 501 and the output board 510. The first ammeter 502 was disposed between the AC power supply 501 and the transformer 503. The oscilloscope 506 detected the voltage and current of the high-frequency current output from the output board 510.

[0109] The first thermometer 508 detected the temperature of the test body heated by the heating means 507. The second thermometer 509 detected the temperature of the coil.

[0110] A total input power A input to the evaluation device was calculated from a current value detected by the first ammeter 502 and a voltage value of the AC power supply 501. An output board input power B input to the output board 510 was calculated from a current value detected by the second ammeter 504 and a voltage value detectable from the transformer 503. In addition, coil power E (active power C - coil power consumption D) was calculated by subtracting coil power consumption D calculated from a resistance value of the coil 513 and a current value detected by the oscilloscope 506 from active power C calculated from the current value and the voltage value detected by the oscilloscope 506.2023-024-GB 26Then, a first efficiency F (E / AxlOO [%] ) indicating a ratio of the coil power E to the total input power A and a second efficiency G (E / BxlOO [%] ) indicating a ratio of the coil power E to the output board input power B were calculated. The first efficiency F and the second efficiency G calculated from the test results of the test bodies are illustrated in Table 1. In Table 1, arrows in the columns of the coil power E, the first efficiency F, and the second efficiency G indicate changes in values during the test.

[0111] [Table 1]

[0112] Fig. 14 is a graph illustrating a temperature of the test body with respect to the heating time in the plating evaluation test, and Fig. 15 is a graph illustrating a temperature of the coil with respect to the heating time in the plating evaluation test.

[0113] From Figs. 14 and 15, it was confirmed that the test bodies 1 to 4 could raise the temperature of the portion to be plated to a higher temperature than the reference test body 5 which was a plate made of an aluminum alloy.

[0114] In addition, by comparing the results of the test body 1 and the test body 2, it was confirmed that the temperature of the test body could be raised high in a short time by performing the baking treatment. From Table 1, while the first efficiency F and the second efficiency G greatly decreased with the lapse of time in the test body 1 not subjected to the baking treatment, the first efficiency F and the second efficiency G did not greatly change with the lapse of time in the test body 2 subjected to the baking treatment. As a result, it was confirmed that the portion to be plated could be stably heated by performing the baking treatment on the metal plating layer 351.

[0115] In addition, it was confirmed that the test body 2 in which the2023-024-GB 27 second metal plating layer 353 containing the brightener formed by electrolytic plating was subj ected to the baking treatment could raise the temperature of the portion to be plated to a higher temperature than the reference test body 6 which was a stainless steel plate .

[0116] In addition, it was confirmed that the test body 3 in which the second metal plating layer 353 not containing a brightener formed by electrolytic plating was not subj ected to the baking treatment could raise the temperature of the portion to be plated to a high temperature even though the baking treatment was not performed .

[0117] In addition, by comparing the results of the test body 2 and the test body 4 , it was confirmed that the test body 2 in which the second metal plating layer 353 formed by electrolytic plating was subj ected to the baking treatment could raise the temperature of the portion to be plated to a higher temperature in a shorter time than the test body 4 in which the metal plating layer 351 formed by electroless plating was subj ected to the baking treatment .

[0118] In addition, from Table 1 , it was confirmed that the test body 3 in which the second metal plating layer 353 not containing a brightener formed by electrolytic plating was not subj ected to the baking treatment had higher first ef ficiency F and second ef ficiency G than the test body 1 in which the second metal plating layer 353 containing a brightener formed by electrolytic plating was not subj ected to the baking treatment and the test body 4 in which the metal plating layer 351 formed by electroless plating was subj ected to the baking treatment .

[0119] <Baking Treatment Temperature Evaluation Test>A test body 7 and a test body 8 described later were prepared, and tests were performed by changing the temperature of the baking treatment .

[0120] A first metal plating layer 352 of nickel having a thickness of about 8 pm was formed as a base by electroless plating on one surface of a rectangular plate material made of aluminum (A5083 ) having side lengths of 67 mm and 50 mm and a thickness of 0 . 5 mm, and a second metal plating layer 353 of nickel having a thickness of about 100 pm not containing a brightener was formed on the surface of the first metal plating layer 352 by electrolytic plating to obtain a test body 7 .

[0121] A first metal plating layer 352 of nickel having a thickness of about 8 pm was formed as a base on one surface of a rectangular plate material made of aluminum (A5083 ) having side lengths of 67 mm and 50 mm2023-024-GB 28 and a thickness of 0.5 mm by electroless plating, and a second metal plating layer 353 of nickel having a thickness of about 100 pm containing a brightener was formed on the surface of the first metal plating layer 352 by electrolytic plating to obtain the test body 8.

[0122] The test body 7 was subjected to the baking treatment at 135°C for 2 hours, then at 150°C for 2 hours, then at 175°C for 2 hours, then at 200°C for 2 hours, then at 225°C for 2 hours, then at 250°C for 2 hours, then at 300°C for 2 hours. After the baking treatment at each temperature condition, a test by the above-described testing device 500 was performed. The results are illustrated in Fig. 16.

[0123] The test body 8 was subjected to the baking treatment at 135°C for 2 hours, then at 150°C for 2 hours, then at 175°C for 2 hours, then at 200°C for 2 hours, then at 225°C for 2 hours, then at 250°C for 2 hours. After the baking treatment at each temperature condition, a test by the above-described testing device 500 was performed. The results are illustrated in Fig. 17.

[0124] As a result, it was confirmed that in both the test body 7 and the test body 8, the higher the temperature of the baking treatment was, the shorter the temperature of the portion to be plated could be raised.

[0125] In addition, it was confirmed that the test body 7 not containing a brightener was changed so that the temperature of the test body could be raised in a short time at a lower baking treatment temperature than the test body 8 containing a brightener.

[0126] <Baking Treatment Time Evaluation Test>The above-described test body 8 (a test body having the second metal plating layer 353 of nickel containing a brightener by electrolytic plating) , a test body 9 having the same structure as that of the test body 8 and subjected to the baking treatment at 135°C for 2 hours and at 150°C for 2 hours, that is, for a total of 4 hours, and a test body 10 having the same structure as that of the test body 8 and subjected to a baking treatment at 150°C for 10 hours were prepared, and the test by the above-described testing device 500 was performed. The results are illustrated in Fig. 18.

[0127] As a result, it was confirmed that the test body 9 and the test body 10 after the baking treatment could raise the temperature of the portion to be plated in a short time as compared with the test body 8 not subjected to the baking treatment. It is to be noted that no significant2023-024-GB 29 difference was observed between the test bodies 9 and 10 having different baking times.

[0128] Next, the above-described test body 7 (the test body having a second metal plating layer 353 of nickel not containing a brightener by electrolytic plating) and a test body 11 having the same structure as that of the test body 7 and subjected to a baking treatment at 150°C for 10 hours were prepared, and a test by the above-described testing device 500 was performed. The results are illustrated in Fig. 19.

[0129] As a result, it was confirmed that the test body 11 after the baking treatment could raise the temperature of the portion to be plated to a high temperature in a short time as compared with the test body 7 not subjected to the baking treatment.

[0130] Note that the present invention is not limited to the abovedescribed embodiments, and various modifications and combinations can be made by those skilled in the art within the technical idea of the present invention. For example, the first embodiment and the second embodiment described above may be combined.[Reference Signs List]

[0131] 102 Rotor blade113 Rotor shaft123 Stator blade131 Thread groove spacer300, 400 Vacuum pump310 Casing320 Magnetic bearing340, 440 Heating means342, 442 Coil350, 450 Heated portion351 Metal plating layer352 First metal plating layer353 Second metal plating layer

Claims

2023-024-GB 30Claims

1. A vacuum pump comprising : a casing; a rotor shaft disposed in the casing; a rotor blade rotatable together with the rotor shaft ; and a heating means for performing heating by electromagnetic induction y causing an alternating current to flow through a coil , wherein the vacuum pump exhausts a gas by rotation of the rotor blade , and a heated portion heated by the heating means includes a metal lating layer having magnetism .

2. The vacuum pump according to claim 1 , wherein the metal plating ayer includes a first metal plating layer having magnetism and formed by lectroless plating, and a second metal plating layer having magnetism nd formed on the first metal plating layer by electrolytic plating .

3. The vacuum pump according to claim 1 or 2 , wherein the metal plating ayer has a columnar crystal structure extending in a direction away from surface of a portion to be plated, which is covered with the metal lating layer .

4. The vacuum pump according to claim 3 , wherein the metal plating ayer is a plating layer containing nickel as a main component .

5. A vacuum pump component constituting a part of a gas flow path of a acuum pump, the vacuum pump component comprising : a metal plating layer having magnetism and heatable by lectromagnetic induction, wherein the metal plating layer includes a first metal plating layer having agnetism and formed by electroless plating, and a second metal plating ayer having magnetism and formed on the first metal plating layer by lectrolytic plating .

6. A method for manufacturing a vacuum pump component constituting a art of a gas flow path of a vacuum pump, the method comprising : a step of forming a first metal plating layer on a surface of a2023-024-GB 31 portion to be plated of the vacuum pump component by electroless plating; and a step of forming a second metal plating layer having magnetism and heatable by electromagnetic induction on a surface of the first metal plating layer by electrolytic plating .

7. The method for manufacturing a vacuum pump component according to laim 6 , wherein a plating solution used for electrolytic plating of the econd metal plating layer does not contain a brightener .

8. The method for manufacturing a vacuum pump component according to laim 6 or 7 , wherein at least the second metal plating layer is ubj ected to a baking treatment .

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