JP2008144695A - Vacuum pump and method of manufacturing same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vacuum pump enhanced in safety by reducing the effect of a corrosive gas thereon. <P>SOLUTION: When a rotor 20 is tightened to a shaft 7, a tightening projection 70 formed at the top of the shaft 7 is fitted into the tightening hole 200 of the rotor 20, and a corrosion resistant protective member 713 is placed in the tightening hole 200. A shaft cover 71 is attached to the rotor 20, and the shaft 7, the rotor 20, and the shaft cover 71 are tightened together with bolts 72 to integrate the shaft 7, the rotor 20, and the shaft cover 71 into one. When they are finally corrected for balance after the integration, the corrosion resistant shaft cover 71 is cut for correction. The tightening projection 70 and the tightening hole 200 are protected against the corrosive gas by the protective member 713. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a vacuum pump that performs vacuum evacuation by rotating a pump rotor at a high speed, such as a turbo molecular pump and a molecular drag pump, and a method for manufacturing the vacuum pump.

  A turbo molecular pump is a device that performs high-speed rotation of a rotor having rotor blades with respect to fixed blades to perform vacuum evacuation. For example, it is used for evacuating a process chamber of a dry etching apparatus or a CVD apparatus used in semiconductor manufacturing. It has been. Since the rotor of this kind of turbo molecular pump is generally made of an aluminum alloy, the turbo molecular pump used in equipment using chlorine or fluorine corrosive gas such as dry etching or CVD is used. In some cases, the rotor surface is subjected to corrosion resistance treatment such as nickel phosphorus alloy plating (see, for example, Patent Document 1).

  By the way, in the turbo molecular pump that rotates at high speed, it is necessary to balance the rotating body in the pump assembly manufacturing stage. Generally, the balance correction at the time of balancing is performed by scraping off a part of the outer peripheral surface or inner peripheral surface of the rotating body with a drill or the like. There's a problem. Therefore, in the conventional turbo molecular pump described above, an adhesive such as an epoxy resin is applied as an additional mass for balance correction.

JP 2003-148389 A

  However, since the protrusion formed on the top of the rotation shaft is fitted into the through hole formed at the rotation center of the rotor, the rotor and the rotation shaft are centered. Corrosion-resistant treatment is not performed on the side surface of the through hole, and there is a concern that the rotating shaft and the through hole are corroded by corrosive gas.

According to the first aspect of the present invention, a protrusion provided on the top of the rotating shaft is fitted into a through hole formed at the rotation center of the pump rotor, the pump rotor and the rotating shaft are fastened, and the pump rotor is rotated at a high speed. The present invention is applied to a vacuum pump that performs evacuation, and includes a cover that is fixed to a pump rotor fastened to a rotating shaft so as to cover a through hole and has corrosion resistance against exhaust gas.
According to the second aspect of the present invention, a protrusion provided on the top of the rotating shaft is fitted into a through hole formed at the rotation center of the pump rotor, the pump rotor and the rotating shaft are fastened, and the pump rotor is rotated at a high speed. This is applied to a vacuum pump that performs vacuum evacuation, the protrusion height of the protrusion is set to be smaller than the depth of the through hole, and the protrusion is injected into the inserted through hole to cover the surface of the protrusion and the side surface of the through hole. A corrosion-resistant protective member and a cover fixed to the pump rotor fastened to the rotating shaft so as to cover the through hole and having corrosion resistance against exhaust gas are provided.
According to a third aspect of the present invention, in the vacuum pump according to the first or second aspect of the present invention, a concave portion is provided on a surface covered with the cover of the pump rotor and provided with an additional mass for balance correction.
A fourth aspect of the present invention is the vacuum pump according to any one of the first to third aspects, wherein a gas vent hole is formed at a position facing the through hole and the concave portion of the cover.
The invention of claim 5 is a method of manufacturing the vacuum pump according to claim 1 or 2, wherein a part of the cover is deleted and the balance of the rotating body formed by integrating the pump rotor and the rotating shaft is corrected. It is characterized by performing.
According to a sixth aspect of the present invention, in the manufacturing method according to the fifth aspect, before the pump assembly, a part of the region covered with the cover of the pump rotor is deleted to correct the balance of the pump rotor alone, and then the pump assembly is performed. Is to do.

  According to the present invention, by providing the protective member and the cover, the influence of the corrosive gas on the rotating body can be reduced, and the safety of the vacuum pump can be improved.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing an embodiment of a vacuum pump according to the present invention, and is a cross-sectional view of a turbo molecular pump. The turbo molecular pump includes a pump main body 1 shown in FIG. 1 and a controller (not shown) that supplies power to the pump main body 1 to control rotational driving.

  Inside the casing 3 of the pump body 1, a rotor 20 having a plurality of stages of rotating blades 21 and a rotating cylindrical portion 22 is provided. The rotor 20 is bolted to the shaft 7. The shaft 7 to which the rotor 20 is fixed is supported in a non-contact manner by a pair of upper and lower radial magnetic bearings 31 and 32 and a thrust magnetic bearing 33 and is driven to rotate by the motor 6.

  On the other hand, a plurality of fixed blades 11 and a fixed cylindrical portion 12 are provided on the base 10 side of the pump body 1. A plurality of stages of rotating blades 21 and a plurality of stages of fixed blades 11 arranged alternately in the axial direction constitute a turbine blade. The fixed blade 11 is provided in a plurality of stages, and is held at a predetermined position so that the outer peripheral portion is sandwiched between the spacers 13.

  In addition, a molecular drag pump unit is configured by the rotating cylindrical unit 22 and the fixed cylindrical unit 12 arranged on the downstream side of the turbine blade unit. The rotating cylindrical portion 22 is provided close to the inner peripheral surface of the fixed cylindrical portion 12, and a spiral groove is formed on the inner peripheral surface of the fixed cylindrical portion 12. In the molecular drag pump section, the helical groove of the fixed cylinder section 12 and the rotating cylinder section 22 that rotates at high speed perform exhaust capability by viscous flow.

  The turbo molecular pump in which the turbine blade part and the molecular drag pump part shown in FIG. 1 are combined is referred to as a hybrid turbo molecular pump. The gas molecules flowing in from the intake port 14 are knocked down by the turbine blades and are compressed and exhausted toward the downstream side. The compressed gas molecules are further compressed by the molecular drag pump unit and discharged from the exhaust port 15.

  FIG. 2 is an enlarged view showing a fastening portion between the rotor 20 and the shaft 7. A fastening hole 200 is formed in the axial center portion of the rotor 20. A fastening protrusion 70 formed on the top of the rotating shaft 7 is inserted into the fastening hole 200 from one side (lower side), and the rotor 20 and the shaft 7 are coupled. On the other hand, the shaft cover 71 is attached to the other side (upper side) of the fastening hole 200 so that the protruding portion 710 is inserted into the fastening hole 200.

  The shaft 7 and the shaft cover 71 are centered with respect to the rotor 20 by inserting the respective fastening protrusions 70 and protrusions 710 into the fastening holes 200. The rotor 20 and the shaft cover 71 are fixed to the shaft 7 by fastening them together with bolts 72. The shaft cover 71 also functions as a cutting member when performing balance correction, and a corrosion-resistant material such as stainless steel is used. In FIG. 2, the portions denoted by reference numerals 712A and 712B are portions that have been removed for balance correction.

  A gas vent hole 711 is formed in the projecting portion 710 of the shaft cover 71 so that the fastening hole 200 does not become a gas reservoir. In addition, the gas vent hole 711 of the shaft cover 71 can be omitted by forming a gas vent groove or the like on the rotor 20 side. Since the fastening hole 200 formed in the rotor 20 is used for centering when fastening with the shaft 7 as described above, high accuracy is required, and surface treatment is performed even when the surface of the rotor 20 is subjected to corrosion resistance treatment. Absent. Therefore, in order to prevent the corrosive gas flowing from the gas vent hole 711 from corroding the surface (side surface) of the fastening hole 200 and the coupling protrusion 70, a corrosion-resistant protective member (adhesive, resin, 713) is injected so that they are covered by the protective member 713.

  The procedure for assembling in the state of FIG. 2 is as follows. First, balance correction is performed on the rotor 20 alone and the shaft 7 alone. Regarding the balance correction of the rotor 20 alone, a corrosion-resistant surface treatment may be applied after the balance correction, or the area covered with the shaft cover 71 may be scraped off after the surface treatment as shown in FIG. Also good. In FIG. 4, the part denoted by reference numeral 201 is a correction cutting part. As described above, when the region covered with the shaft cover 71 is a cutting region for balance correction, the correction portion is covered with the shaft cover 71 after the integration, so that corrosion of the correction portion can be prevented.

  Next, the fastening protrusion 70 of the shaft 7 is fitted into the fastening hole 200 of the rotor 20, and the protective member 713 is injected into the fastening hole 200. Thereafter, the shaft cover 71 is attached to the rotor 20, and the shaft 7, the rotor 20 and the shaft cover 71 are fastened together with the bolts 72. Then, final balance correction is performed on the integrated rotor 20 and shaft 7. This balance correction is performed by scraping the shaft cover 71.

  FIG. 3 is a diagram illustrating an example of a fastening structure in a conventional turbo molecular pump. The rotor 20 has the same structure as that of the present embodiment, and a fastening hole 200 is formed. On the other hand, the fastening protrusion 80 formed on the shaft 8 is longer than the fastening protrusion 70 described above, and protrudes upward from the fastening hole 200. Therefore, there is a problem that the fastening protrusion 80 is exposed to corrosive gas and the shaft 8 is rusted, or the rotor 20 is corroded from the fastening hole 200 portion not subjected to surface treatment.

  However, in the above-described vacuum pump of the present embodiment, the height of the protrusion 70 is set to be smaller than the depth of the fastening hole 200, and the corrosion-resistant protective member 713 is injected into the fastening hole 200. It is possible to prevent the holes 200 and the protrusions 70 from being exposed to corrosive gas. In addition, since the shaft cover 71 is provided so as to cover the fastening hole 200, even if the protective member 713 is peeled off, a large piece of the protective member 71 that causes an accident may be outside the fastening hole 200. Can be prevented from splashing. In addition, the diameter of the gas vent hole 713 is set to a size that does not cause an accident with the protective member fragments that can pass through the gas vent hole 713.

  Furthermore, as shown in FIG. 2, the shaft cover 71 can be used as a part to be cut when the balance is corrected. Therefore, the rotor 20 is shaved for correcting the balance, or an additional mass is added to the rotor 20. There is no need.

[Modification 1]
FIG. 5 is a diagram showing a first modification of the above-described embodiment. In the first modification, when the balance correction of the rotor 20 alone is performed, the correction is performed by adding mass. A plurality of correction holes 202 for adding the additional mass 203 are formed in the rotor 20 in advance. When the balance of the rotor 20 is corrected, the mass is added by injecting an adhesive into the correction hole 202 or inserting a pin. The shaft cover 71 is formed with a gas vent hole 712 at a position facing the correction hole 202 so that each correction hole 202 does not become a gas reservoir.

  As described above, since the correction hole 202 for the additional mass is provided in the region covered with the shaft cover 71, it is possible to reliably prevent the additional mass from dropping from the rotor 20. The final balance correction after being integrated is performed by scraping the shaft cover 71.

[Modification 2]
FIG. 6 is a diagram showing a second modification. In the second modification, the height of the fastening protrusion 70 of the shaft 7 is set to be substantially the same as the depth of the through hole 200, and the portion of the through hole 200 and the fastening protrusion 70 is covered with the shaft cover 71. . Here, since no depression is generated in the through-hole 200 portion, the protective member 713 and the gas vent hole 711 described above are omitted to reduce the cost. Of course, the shaft cover 71 and the rotor 20 may be fastened together after an adhesive is applied to the upper surface of the fastening protrusion 70 in order to reliably prevent gas accumulation. In the case of the second modification, the correction hole 202 may be provided in the portion covered with the shaft cover 71 as in the first modification.

  In the above-described embodiment, the hybrid turbo molecular pump has been described as an example. However, the present invention can be similarly applied to a vacuum pump such as an all blade type turbo molecular pump or a molecular drag pump without blades.

  In the correspondence between the embodiment described above and the elements of the claims, the rotor 20 is a pump rotor, the shaft 7 is a rotating shaft, the fastening projection 70 is a projection, and the fastening hole 200 is a through hole. Each of the holes 202 constitutes a recess. The above description is merely an example, and when interpreting the invention, there is no limitation or restriction on the correspondence between the items described in the above embodiment and the items described in the claims.

It is a figure which shows one Embodiment of the vacuum pump which concerns on this invention, and is sectional drawing of a turbo-molecular pump. It is the figure which expanded and showed the fastening part of the rotor 20 and the shaft 7. FIG. It is a figure which shows an example of the fastening structure in the conventional turbo molecular pump. FIG. 3 is a diagram showing a balance correction unit 201 of the rotor 20. It is a figure which shows the modification 1. FIG. It is a figure which shows the modification 2. FIG.

Explanation of symbols

  1: pump body, 7, 8: shaft, 20: rotor, 70, 80: fastening protrusion, 71: shaft cover, 200: fastening hole, 202: correction hole, 203: additional mass, 711, 712: degassing Hole, 713: protective member

Claims (6)

A projection provided at the top of the rotation shaft is fitted into a through hole formed at the rotation center of the pump rotor, the pump rotor and the rotation shaft are fastened, and the pump rotor is rotated at high speed to perform vacuum exhaust. In vacuum pump,
A vacuum pump comprising: a cover fixed to the pump rotor fastened to the rotating shaft so as to cover the through-hole and having corrosion resistance against exhaust gas. A projection provided at the top of the rotation shaft is fitted into a through hole formed at the rotation center of the pump rotor, the pump rotor and the rotation shaft are fastened, and the pump rotor is rotated at high speed to perform vacuum exhaust. In vacuum pump,
The protrusion height of the protrusion is set smaller than the depth of the through hole,
Corrosion-resistant protective member that is injected into the through-hole into which the protrusion is inserted and covers the surface of the protrusion and the side surface of the through-hole,
A vacuum pump comprising: a cover fixed to the pump rotor fastened to the rotating shaft so as to cover the through-hole and having corrosion resistance against exhaust gas. The vacuum pump according to claim 1 or 2,
A vacuum pump comprising a recess formed in a surface covered by the cover of the pump rotor and provided with an additional mass for balance correction. In the vacuum pump as described in any one of Claims 1-3,
A vacuum pump, wherein a gas vent hole is formed at a position facing the through hole and the concave portion of the cover. A method for producing a vacuum pump according to claim 1 or 2,
A manufacturing method, wherein a part of the cover is deleted and balance of a rotating body formed by integrating the pump rotor and the rotating shaft is corrected. In the manufacturing method of Claim 5,
Prior to pump assembly, a part of the area covered by the cover of the pump rotor is deleted, the balance of the pump rotor alone is corrected, and then the pump assembly is performed.

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