JP3183571U - Turbo molecular pump - Google Patents

Abstract

Provided is a turbomolecular pump that can improve heat discharge from a rotor at low cost.
SOLUTION: Using an upper mold 71 in which convex portions 71a to 71c and a concave portion 71d are formed on a molding surface 81, and a lower mold 72 in which convex portions 72a and concave portions 72b and 72d are formed on a molding surface 82, At the same time when the wing part 3 of the stator blade is pressed, the concave parts 3a to 3c, 3e, 3g and the convex parts 3d, 3f are formed on the surface of the wing part 3 of the stator blade, and the wing part of the stator blade is formed. 3 increase the surface area.
[Selection] Figure 6

Description

  The present invention relates to a turbo molecular pump with good heat dissipation.

  In a process of performing processing in a high-vacuum process chamber such as dry etching or CVD in a semiconductor manufacturing process, a turbo molecular pump is used as a means for exhausting the gas in the process chamber to form a constant high vacuum degree. A vacuum pump is used.

  In the case of a turbo molecular pump, the rotor may exceed an allowable temperature when used in a large flow process in which a large amount of gas flows. When the rotor is operated exceeding the allowable temperature, the creep speed of the rotor increases. As a result, the rotor may come into contact with the screw stator or the rotor may creep.

  As a technique for releasing the heat of the rotor so that the rotor does not exceed the allowable temperature, for example, a technique described in Patent Document 1 is known. In Patent Document 1, the surface of the rotor blade near the exhaust port and the surface of the stator blade are coated with a ceramic coating to increase the radiation rate and improve the heat dissipation performance from the rotor blade to the stator blade.

Japanese Patent No. 2527398

  However, when the method of applying a ceramic coating described in Patent Document 1 is used, it is necessary to add a surface treatment process to the normal manufacturing process, which is problematic in terms of manufacturing cost and man-hours.

A turbo molecular pump according to a preferred embodiment of the present invention includes a plurality of stages of stator blades and a rotor formed with a plurality of stages of rotor blades, and the plurality of stages of stator blades are connected to arcuate inner ribs and outer ribs. The blade angle of the plurality of blade portions includes a press-molded stator blade formed by press working, and at least one surface of the blade portion is formed with unevenness formed by press working.
In a further preferred embodiment, the press-molded stator blade is arranged in a stage downstream of the vacuum exhaust.
In a further preferred embodiment, all stages of stator blades are press-molded stator blades.
Further preferred embodiments are characterized in that irregularities are provided on at least one surface of the inner rib of the press-molded stator blade.
In a further preferred embodiment, the press-molded stator blade is made of aluminum, and the press-molded stator blade is anodized.

  According to the present invention, it is possible to provide a turbo molecular pump that improves heat dissipation without significantly increasing the cost, enables large-flow exhaust, and has a long rotor life.

Sectional drawing of a turbo-molecular pump. FIG. The figure which showed the flow of the heat from a rotor blade | wing. The figure of the stator blade | wing before press work. The figure which showed a mode that a stator blade was pressed. The figure which showed a mode that an unevenness | corrugation was formed simultaneously at the time of press work. The figure which showed a mode that an unevenness | corrugation was formed simultaneously at the time of press work.

-First embodiment-
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view showing a schematic configuration of the turbo molecular pump 100. The rotor 20 is rotatably provided in the casing 52 of the turbo molecular pump 100. The turbo molecular pump 100 shown in FIG. 1 is a magnetic bearing type pump, and the rotor 20 is supported in a non-contact manner by an upper radial electromagnet 101, a lower radial electromagnet 102, and a thrust electromagnet 104. The rotor 20 magnetically levitated by the magnetic bearing is driven to rotate at high speed by a motor 43.

  The rotor 20 is provided with a plurality of stages of rotor blades 21 and a cylindrical portion 45. A plurality of stages of stator blades 1 are provided between the plurality of stages of rotor blades 21 in the axial direction, and a screw stator 44 is provided on the outer peripheral side of the cylindrical portion 45. Each stator blade 1 is disposed on the base 107 via a spacer 50. When the casing 52 is fixed to the base 107, the stacked spacers 50 are sandwiched between the base 107 and the casing 52, and each stator blade 1 is positioned.

  The base 107 is provided with an exhaust port 108, and a back pump is connected to the exhaust port 108. By rotating the rotor 20 at a high speed by the motor 43 while magnetically levitating, the gas molecules on the intake port 30 side are exhausted to the exhaust port 108 side. The base 107 is also provided with a cooling pipe 60, and the turbo molecular pump 100 is cooled by flowing a cooling liquid through the cooling pipe 60.

  2A and 2B are views showing the stator blade 1 of the turbo molecular pump 100. FIG. FIG. 2A is a plan view of the stator blade 1, and the stator blade 1 has an inner rib 2, a blade portion 3, and an outer rib 4. FIG. 2B is a cross-sectional view taken along the line AA in FIG. 2A, and shows a cross section of the blade portion 3 of the stator blade 1.

  As shown in FIG. 2B, the blade portion 3 of the stator blade 1 is inclined with respect to the inner rib 2 and the outer rib 4 by the blade angle θ. That is, the fulcrum 31 on the inner rib 2 side and the fulcrum 32 on the outer rib side are twisted, and the wing part 3 is inclined. In the general turbo molecular pump 100, the blade angle θ of the stator blade 1 on the upstream side of the vacuum exhaust is set large, and the blade angle θ of the stator blade 1 on the downstream side of the vacuum exhaust is set small. ing. This is because a large amount of gas is taken in on the upstream side of the vacuum exhaust, and the taken-in gas is prevented from flowing back on the downstream side of the vacuum exhaust. As a result, a pressure difference is generated in the turbo molecular pump 100, and the pressure increases toward the downstream side of the vacuum exhaust. When exhausting, gas molecules collide with the inside of the turbo molecular pump 100, and heat is generated at that time. The higher the pressure, the more intense the collision between the gas molecules and the turbo molecular pump 100, and the more heat is generated at that time. Therefore, the heat generation becomes more intense on the downstream side of the vacuum exhaust. From the above, the stator blade 1 on the downstream side of the vacuum exhaust, where the heat generation is severe, is desired to have a structure with excellent heat conductivity.

  Examples of the method for manufacturing the stator blade 1 include cutting and pressing. Since the cost of producing the stator blades 1 can be suppressed lower than the cutting work, it is desirable to produce the stator blades 1 of all stages by the press work. However, there are the following circumstances, and in general, the stator blades 1 on the downstream side of the vacuum exhaust are pressed, and the stator blades 1 on the upstream side of the vacuum exhaust are manufactured by cutting or the like.

  The stage where the stator blades 1 on the downstream side of the vacuum exhaust are pressed, and the stator blades 1 on the upstream side of the vacuum exhaust are produced by other methods such as cutting. As described above, the stator blade 1 on the upstream side of the vacuum exhaust increases the blade angle θ. Since press working utilizes plastic deformation, the greater the blade angle θ, the greater the degree of plastic deformation. Due to excessive plastic deformation, the stator blade 1 is likely to break. Therefore, the stator blade 1 on the upstream side of the vacuum exhaust is difficult to produce by press working. On the other hand, as described above, the blade angle θ is smaller in the stator blade 1 on the downstream side of the vacuum exhaust. Therefore, the stator blade 1 on the downstream side of the vacuum exhaust is easier to produce by press working. As described above, generally, the stage stator blade 1 on the downstream side of the vacuum exhaust is manufactured by pressing, and the stator blade 1 on the upstream stage of the vacuum exhaust is manufactured by cutting or the like.

  FIG. 3 is a diagram for explaining the flow of heat generated from the rotor 20, in which the stator blade 1 and the rotor blade 21 are partially enlarged. All the arrows shown in FIG. 3 indicate the heat flow from the rotor 20. Here, reference numerals of the stator blade 1 and the rotor blade 21 will be described. The uppermost stator blade 1 on the upstream side of the vacuum exhaust is referred to as a stator blade 1a, which will be referred to as stator blades 1b to 1h in this order. Similarly, the uppermost rotor blade 1 on the upstream side of the vacuum exhaust is referred to as a rotor blade 21a, and hereinafter referred to as rotor blades 21b to 21i in order. The stator blade 1a faces the rotor blade 21a and the rotor blade 21b. Since the rotor 20 is magnetically levitated in a vacuum state, heat transfer between the rotor blades 21a and 21b and the stator blade 1a is mainly performed by radiation. When the heat reaches the outer rib 4 through the stator blade 1a, the heat reaches the cooling pipe 60 through the spacer 50 on the downstream side of the vacuum exhaust and the outer ribs of the stator blades 1b to 1h. The same applies to the state where heat is transferred from the rotor blades 21b to 21i to the stator blades 1b to 1h and reaches the cooling pipe 60. As described above, since heat is transmitted from the rotor blade 21 to the inner rib 2 and the blade portion 3 of the stator blade 1 by radiation, the inner rib 2 and the blade portion 3 of the stator blade 1 are processed so as to easily receive radiant heat. By applying, heat from the rotor 20 is easily discharged.

In order to consider what kind of processing makes it easy to receive radiant heat, the following formula (1) is given. Expression (1) is a relational expression regarding the amount of heat transfer by radiation.
Q = εσ (T ₁ ⁴ −T ₂ ⁴ ) A (1)
Here, Q is the heat transfer amount, ε is the emissivity, σ is the Boltzmann constant, T ₁ is the temperature of the rotor blade 21, T ₂ is the temperature of the stator blade 1, and A is the surface area of the stator blade 1.
As can be seen from Equation (1), the amount of heat transfer can be improved by increasing the emissivity ε and the surface area A of the stator blade 1.

  FIGS. 4A and 4B are views showing a stator blade before press working, that is, a stator blade material 1M. The stator blade material 1M is generally manufactured by etching or punching. FIG. 4B is a BB cross-sectional view of FIG. 4A and shows a cross section of the blade portion 3 of the stator blade material 1M. As shown in FIG. 4B, the blade portion 3 of the stator blade material 1 </ b> M is parallel to the inner rib 2 and the outer rib 3. By pressing the stator blade material 1M, a blade angle θ as shown in FIG. 2B is formed.

  FIGS. 5A to 5C are cross-sectional views illustrating the press working process of the blade portion 3 of the stator blade material 1M. It is the cross section similar to the cross section of the blade | wing part 3 shown in sectional drawing (FIG.2 (b)) of the stator blade | wing 1 after press work. The inner rib 2 and the outer rib 4 are not bent as in the wing portion 3.

  FIG. 5A shows a state where the blade portion 3 of the stator blade material 1M is installed between the upper mold 71 and the lower mold 72. FIG. Before the press working, the blade portion 3 of the stator blade 1M is not inclined with respect to the inner rib 2 or the outer rib 4. That is, the blade angle θ of the blade portion 3 is zero, and the twist amounts of the fulcrums 31 and 32 are also zero. The upper mold 71 is formed with a molding surface 81 having an inclination of φ with respect to the left and right surfaces in the drawing. On the other hand, the lower die 72 is also formed with a molding surface 82 having an inclination of φ with respect to the left and right surfaces in the drawing. The blade angle θ is determined by the inclination φ of the molding surface 81 of the upper mold 71 and the molding surface 82 of the lower mold 72. Strictly speaking, the blade angle θ of the blade portion 3 is smaller than the inclination φ of the molding surfaces 81 and 82 due to the restoring force of the metal plate.

  The upper mold 71 shown in FIG. 5A is moved in the arrow downward direction, and the lower mold 72 is moved in the arrow upward direction. At this time, the inner rib 2 and the outer rib 4 are clamped by a jig (not shown), the position of the stator blade material 1M is fixed, and the upper and lower molds 71 and 72 are moved to the position shown in FIG.

  FIG. 5B shows a state when the press working on the blade portion 3 of the stator blade material 1M is completed. The blade portion 3 of the stator blade material 1M is bent at a blade angle θ by the molding surface 81 of the upper die 71 and the molding surface 82 of the lower die 72. That is, the inner rib 2 and the outer rib 4 are held in parallel by a jig (not shown) and the wing part 3 is pressed by the upper and lower molds 71 and 72, whereby the fulcrums 31 and 32 are twisted and the wing part 3 is Tilt at an angle θ. In other words, the wing 3 is twisted by an angle θ around the fulcrums 31 and 32.

  FIG. 5C shows a state after the press working of the blade portion 3 of the stator blade 1. When pressing is performed in FIG. 5B and the upper die 71 and the lower die 72 are returned to the positions before the pressing, the blade portion 3 of the stator blade 1 is formed at the blade angle θ.

  A method for increasing the surface area of the blade portion 3 of the stator blade 1 and forming irregularities on the blade portion 3 in order to improve heat transfer based on the above formula (1) will be described below with reference to FIG. FIG. 6 is a cross-sectional view showing a state where irregularities are formed in the vicinity of the surface of the blade portion 3 at the same time when the blade portion 3 of the stator blade 1 is pressed, and a region 10 shown in FIG. Is an enlarged version. On the molding surface 81 of the upper mold 71, convex portions 71a, 71b, 71c, and a concave portion 71d are formed. On the other hand, on the molding surface 82 of the lower mold 72, convex portions 72a and concave portions 72b and 72d are formed. The region 72c of the molding surface 82 is not particularly uneven.

  A description will be given of how the unevenness formed in the mold is processed on the blade portion 3 of the stator blade 1. The convex portion 71a of the upper die 71 is pressed, strictly speaking, after the blade portion 3 of the stator blade material 1M is inclined by the angle θ, the blade portion 3 is further moved by the upper die 71 and the lower die 72. By press working, plastic deformation occurs near the surface of the wing 3, and as a result, a recess 3 a is formed in the wing 3. Similarly, in the case of the other convex portions 71b, 71c, 72a, the concave portions 3b, 3c, 3e are formed. The concave portion 71 of the upper mold 71 is pressed against the blade portion 3 of the stator blade 1 by pressing. When the molding surface of the mold is a recess, plastic deformation occurs such that a region near the surface of the wing portion 3 enters the recess 71. As a result, a convex portion 3d is formed on the wing portion 3. Similarly, convex portions 3f and 3g are formed in the other concave portions 72b and 72d. Since the unevenness is not formed in the region 72c of the molding surface 82 of the lower mold 72, the unevenness is not formed in the region in the vicinity of the wing portion 3. Thus, when the unevenness | corrugation formed in the metal mold | die is comparatively small, plastic deformation occurs only in the surface vicinity of the stator blade | wing 1, and an unevenness | corrugation is formed.

  Since the unevenness forming method shown in FIG. 6 is plastically deformed only in the vicinity of the surface, it is possible to form unevenness only on one side (one surface) of the wing part 3. However, since the surface area can be increased by forming irregularities on both sides of the wing part 3 than when forming irregularities on only one side, heat transfer from the rotor 20 can be achieved by forming irregularities on both sides of the wing part 3. The effect is great. The inner rib 2 can also be uneven, and the heat transfer effect from the rotor 20 can be improved.

The turbo molecular pump according to the first embodiment has the following effects.
(1) The blade angle θ of the blade portion 3 of the stator blade 1 of the turbo molecular pump 100 is formed by pressing, and at that time, at least one surface of the blade portion 3 is formed with unevenness by pressing. did. Thereby, the surface area of the wing | blade part 3 becomes large and the heat transfer from the rotor 20 can be improved. Since only a slight deformation is applied to the normal pressing, the heat discharge from the rotor 20 can be improved at low cost.
(2) The stator blade 1 (press-molded stator blade) molded by press working is arranged in a stage downstream of the vacuum exhaust. Thereby, the stator blade 1 on the downstream side of the vacuum exhaust where much heat is generated receives more heat from the rotor 20, so that heat can be efficiently discharged at low cost. Also, since the blade angle θ of the blade portion 3 of the stator blade 1 on the downstream side of the vacuum exhaust is generally made smaller, the press working is accompanied by plastic deformation, so the stator blade 1 having a smaller blade angle θ is pressed. It is consistent with the fact that it is easy to do.
(3) Concavities and convexities are formed not only on the blade portion 3 of the stator blade 1 but also on the inner rib 2 of the stator blade 1. By doing in this way, the surface area of the stator blade | wing 1 becomes still larger, and the discharge | emission of the heat from the rotor 20 can be improved cheaply.

-Modification of the first embodiment-
FIG. 7 is a cross-sectional view showing a state in which large irregularities are formed in the blade portion 3 as compared with FIG. 6 at the same time that the blade portion 3 of the stator blade 1 is pressed, and FIG. The region 10 shown is enlarged. The concave portion 71e formed on the molding surface 81 of the upper mold 71 and the convex portion 72e formed on the molding surface 82 of the lower mold 72 shown in FIG. When the press working shown in FIG. 5B is performed on the wing portion 3 by the concave portion 71e and the convex portion 72e, the wing portion 3 is plastically deformed not only in the vicinity of the surface of the wing portion 3 but also inside, and continuously from the front to the back as in the region 3h. And deform. The convex portion 71f formed on the molding surface 81 of the upper mold 71 and the concave portion 72f formed on the molding surface 82 of the lower mold 72 are also processed with respect to the wing portion 3 by the concave portion 71e and the convex portion 72e. Similar processing is performed to form the region 3i. Even when the wing portion 3 is uneven as in the present modification, the heat dissipation from the rotor 20 can be improved.

-Second embodiment-
The second embodiment is characterized in that all stages of stator blades 1 are formed by press working according to the first embodiment. That is, in the turbo molecular pump of the second embodiment, the blade portions 3 of the stator blades 1 of all stages are bent by press working, and the surface of the blade portions 3 of the stator blade 1 is uneven by press work. It is formed.

  As described above, generally, the stator blades 1 on the downstream side of the vacuum exhaust are pressed, and the stator blades 1 on the upstream side of the vacuum exhaust are manufactured by cutting. However, in the small turbo molecular pump 100, even the stator blade 1 on the upstream side of the vacuum exhaust has a small blade angle θ. In such a turbo molecular vacuum pump 100, the stator blades 1 of all stages can be pressed.

  Therefore, at the same time as performing the pressing process, a process for forming irregularities only in the vicinity of the surface as shown in the first embodiment, or a continuous plasticity from front to back as shown in the modification of the first embodiment. For example, the stator blades 1 of all stages can be subjected to a process of causing deformation to form irregularities.

  In the present embodiment, the stator blades 1 molded by press working are arranged at all stages. Thereby, since the stator blades 1 of the present invention are arranged in all the stages, heat from the rotor 20 can be discharged more than in the case where the stator blades 1 of the present invention are arranged in only some stages. Can do.

-Third embodiment-
When the material of the stator blade 1 is aluminum, in addition to the irregularities on the surface of the blade portion 3 of the first embodiment, alumite treatment (treatment for modifying the surface to aluminum oxide) can also be performed. When the alumite treatment is performed, the surface of the stator blade 1 can be roughened, so that the surface area can be improved. Moreover, since the emissivity of aluminum oxide is higher than that of aluminum, the emissivity of the stator blades 1 can be improved. Since the outer rib 4 of the stator blade 1 is in contact with the spacer 50 and becomes a heat flow path, it is preferable that there is no unevenness. Therefore, it is desirable to mask the outer rib 4 during the alumite treatment.

  According to the third embodiment, the surface area of the stator blade 1 is further increased in addition to the unevenness treatment, and the emissivity is also improved. Therefore, it can be seen that the heat transfer property is improved from the relational expression shown by the equation (1). Therefore, it is possible to provide the turbo molecular pump 100 with higher heat dissipation from the rotor than in the first embodiment.

  In addition to the modification of the first embodiment and the unevenness of the surface of the wing part 3 of the second embodiment, the third embodiment can also be applied.

  The above description is merely an example, and the device is not limited to the above embodiment.

1, 1a to 1h: stator blade, 1M: stator blade material, 2: inner rib, 3: blade portion,
4: outer rib, 20: rotor, 21, 21a to 21i: rotor blade, 30: air inlet,
31, 32: fulcrum, 43: motor, 44: screw stator, 45: cylindrical part,
50: Spacer, 52: Casing, 60: Cooling pipe, 71: Upper mold,
71a to 71f: irregularities on the upper mold, 72: lower mold, 72a to 72f: irregularities on the lower mold,
100: turbo molecular pump, θ: blade angle

Claims (5)

A multi-stage stator blade;
A rotor having a plurality of stages of rotor blades,
The plurality of stages of stator blades includes a press-formed stator blade in which blade angles of a plurality of blade portions connected to arc-shaped inner ribs and outer ribs are formed by pressing,
A turbo molecular pump, wherein at least one surface of the wing portion is provided with irregularities formed by the press working. In the turbo-molecular pump according to claim 1,
The press-molded stator blade is a turbo molecular pump disposed in a stage downstream of the vacuum exhaust. In the turbo-molecular pump according to claim 1,
A turbo molecular pump in which all stages of stator blades are the press-molded stator blades. In the turbomolecular pump according to any one of claims 1 to 3,
A turbo molecular pump, wherein unevenness is provided on at least one surface of the inner rib of the press-molded stator blade. In the turbo molecular pump according to any one of claims 1 to 4,
The turbo-molecular pump, wherein the press-molded stator blade is made of aluminum, and the press-molded stator blade is anodized.

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