JP2775036B2 - pump - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a pump.

[Prior Art] With the remarkable development of the semiconductor industry in recent years, a large amount of high-purity water having a low content of impurities such as particles has been used.

Furthermore, as LSIs become more highly integrated and higher in performance, and ultra-LSIs with a minimum pattern size of the order of sub-microns are manufactured, even small amounts of impurities can cause LSI pattern defects. (Specific resistance 18.25MΩ ・ cm
At 25 ° C), high-purity water is required.

In order to achieve high-purity water at a level close to such theoretical pure water, at least particles have a particle size of 0.1.
Particles of 2 μm or more are 10 particles / ml or less, particle size 0.1 to 0.2
The particle size of μm should be 100 particles / ml, and the particle size of 0.1 μm or less should be 100 particles / ml or less.

However, even if high-purity water is used as the source water before being supplied to the water supply system, fine particle particles may be mixed from the water supply system, for example, pumps, pipes and members thereof, or the inner surfaces of these may be mixed. Since metal and the like eluted from the water are mixed, the purity is greatly reduced.

For pipes, various pipes, pipes such as regulators and their members, the liquid contact surface is smoothed, and the structure is also devised such as cleaning out the water retention part of the piping system from the main line. We are moving in the direction of solving the problem.

However, no appropriate cleaning technology has been developed for pumps that are most likely to cause contamination and have the greatest effect on determining whether to supply high-purity water. At present, it is used for semiconductor high-purity water without contrivance.

In other words, conventional pumps generally use SCS13
Is used, and the pump is manufactured by the following steps.

(Casting to predetermined shape) → (Heat treatment) → (Pickling) → (Cutting) → (Burr removal) → (Alcohol cleaning) → (Cleaning)
→ (Assembly) → (Performance test) However, in the pump manufactured by such a process, the inner surface has a casting surface, and the surface is very uneven. Also, even if the casting surface is removed by cutting, cracks, pores, folds, blow holes, and the like are present.
In addition, a porous surface is formed by the heat treatment, and corrosion is progressing on the crystal grain boundaries by pickling.

Therefore, it has a surface that embeds particles and non-metallic inclusions and is liable to cause chemical contamination, which causes a deterioration in quality of high-purity water.

Moreover, in terms of structure, it has a complicated shape without consideration for high-purity water, has a large liquid contact area, and has many dead spaces.

In addition, particles of the pump are also generated due to friction, vibration, and the like of the pump shaft sealing portion, and metal powders and the like are mixed into the pump, which causes generation of particles.

Note that a filter may be provided to remove particles. However, in the case of particles of 0.1 μm or more, if a filter is installed downstream of the pump, such particles can be removed to some extent.
In the case of the following fine particles, it is difficult to remove them with a filter.

In order to solve these problems, mechanical polishing (buff polishing) has been attempted as the inner surface treatment of the pump. However, abrasives and brighteners are mixed into the surface, increasing the TOC (total organic carbon) amount. These would rather reduce the quality of the water, and also have a number of other disadvantages. Therefore, these technologies are not perfect technologies.

In addition, there is also a general immersion electropolishing method, but the surface roughness and the like are not improved, and it cannot be said that the technology can be used for a pump for high-purity water.

[Means for Solving the Problems] The pump of the present invention is characterized in that at least the main surface of the liquid contacting part surface in the pump is made of a rolled material or a forged material having a mirror-finished surface by electrolytic composite polishing. And

[Operation] The inventors of the present invention have made various efforts to obtain a pump capable of suppressing the generation of particles and sending out a liquid such as water maintaining a high specific resistance value. It has been found that the purpose can be achieved by using a rolled or forged material on the surface and mirror-finished by electrolytic combined polishing.

The present invention has been made on the basis of the above-described findings. By the electrolytic combined polishing method, extremely smooth, and free of pores, etc., on the inner surface of the pump, fine particles are hardly generated, and metal It is possible to provide a pump capable of transferring a high-purity liquid close to theoretical pure water with a small amount of elution.

In the present invention, in order to maintain high purity, at least the main area of the contact surface with water (the inner surface in contact with the liquid) is electrolytically combined and polished, so that the inner surface is mirror-finished, the generation of particles is significantly reduced, and Chemical contamination adsorbed and desorbed on the inner surface is reduced, and the high specific resistance value can be maintained.

[Embodiments] Embodiments of the present invention will be described below.

The pump which is the object of the present invention is a pump which is generally sold under the name of ultrapure water pump. The type of the pump is not particularly limited. For example, a vortex pump (FIG. 1 (a)) A centrifugal pump (FIG. 2 (a)) is preferred.

The vortex pump shown in FIG. 1A typically has the following configuration. That is, a plurality of blades 18 are formed on the periphery of the disc (FIG. 1 (b)),
An impeller 12 integrally mounted on the bearing 13 is supported by a bearing 17 via a seal box 14 in a casing 13,
The space formed by the casing 13 and the impeller 12 is a fluid passage 20. Fluid passage 20 is in communication with fluid inlet 19. In the pump having such a structure, the rotating shaft 16
Is driven by driving means (not shown) to rotate the impeller 12, the fluid in the blade 18 of the impeller 12 flows out of the outer periphery of the blade 18 by centrifugal force, and the blade passes through the fluid passage 20 through the side of the blade 18. The flow flowing into 18 occurs, the fluid receives energy by the centrifugal force of rotation of the impeller 12, and is converted into velocity energy and pressure energy in the fluid passage 20,
Such an action is repeated in the impeller 12 to increase the pressure of the fluid and discharge the fluid through the discharge port. The pump having this structure is suitable in the present invention as a pump having a small dead space and a small amount of particles because the sliding portion is only the shaft sealing portion.

The centrifugal pump shown in FIG. 2 (a) has a disk (disc).
A plurality of blades 18 are formed extending in a direction slightly deviated from the radial direction from the peripheral edge of the seal box 14 (FIG. 2 (b)). The bearing is supported by a bearing 17 via an impeller 12.
Is covered by a casing 13, and this casing 13
An opening serving as a fluid inlet 19 is opened in the head of the device.
Also in the pump having such a structure, when the rotating shaft 16 is driven by driving means (not shown) to rotate the impeller 12,
The fluid flowing from the fluid inlet receives energy by the blade 18 and is discharged in the circumferential direction of the impeller 12. The pump having this structure is also suitable as a pump having a small dead space and a small amount of particles because of a small number of sliding portions.

The pump may be made of, for example, a material such as steel, an aluminum alloy, or a titanium alloy, and is not limited to these as long as it is a metal pump.

In the present invention, a plastically processed material is used. As the plastic working material, for example, a material obtained by plastic working such as rolling, forging, or extrusion may be used. When a material other than the plastic working material (for example, a cast material) is used, a surface capable of suppressing the generation of particles cannot be obtained even by performing electrolytic composite polishing described later.

The pump of the present invention may be manufactured, for example, by the following steps.

(Forging into a predetermined shape) → (heat treatment) → (pickling) → (shape cutting) → (burr removal) → (washing) → (electrolytic composite polishing) → (washing) → (assembly) In the present invention, the mirror surface Surface roughness is 0.
1 μmRmax or less is preferable.

With the electrolytic combined polishing method applied in the present invention, the polished metal to be polished is electrolytically eluted by electrolysis, and the passivation oxide film generated on the surface of the polished metal is rubbed by abrasive grains. This is a method of processing into a mirror surface. At the same time as giving a certain speed or more to the abrasive grains and rubbing the polished surface, at the same time as the electrolytic current speed of several A / cm ² or less through the passivation type electrolyte,
This is a method in which an anodic reaction of elution and oxidation occurs on a polished surface (JP-B-57-47759, JP-B-58-19409).

 This will be described more specifically with reference to FIG.

FIG. 3 shows an example of a tool used in the mirror finishing method of the present invention, wherein 1 is a tool rotated by a driving device connected to a driving shaft, and 2 is a steel plate formed at a lower portion of the tool 1. A disk-shaped cathode 3 has an exposed surface formed in a cross shape on the lower surface of the cathode 2, and 4 has an electrolyte 5 penetrated in the center of the cathode 2.
6 is an abrasive grain attached to the entire surface except for the exposed surface 3 on the lower surface of the cathode 2 and the outlet 4, and 7 is a thin film of an electrically insulating paint or the like. And tool 1
Useless leakage current is prevented from flowing out of the peripheral surface of the
Is transferred from the electrolytic solution supply device via the drive shaft of the tool 1, supplied from the outlet 4 to the gap between the exposed surface 3 and the metal to be polished (not shown), and discharged out of the tool. . Then, the cathode side and the anode side of direct current or pulsed voltage are connected to the cathode 2 of the tool 1 and the metal to be polished, respectively.

During the polishing process, the voltage is applied between the cathode 2 of the tool 1 and the metal to be polished as described above, and the electrolytic solution 5 is supplied during the application, and the cathode 2 rotates while pressing the cathode 2 against the metal to be polished. The anodic dissolution of the metal to be polished is performed by the action, and among the passivation oxide films formed on the irregularities on the surface of the metal to be polished, the convex portions are rubbed and removed by the abrasive grains 6 to remove the convexities of the metal to be polished. The part is preferentially and selectively electrolytically eluted to a mirror finish.

As an example of polishing, if the initial surface roughness is rubbed with SUS316L inner surface of 20 to 50 μmRmax with # 120 to # 1500 SiC-based abrasive, use 20% NaNO ₃ aqueous solution as the passivating electrolyte. If the polishing is performed while changing the electrolytic current density in the range of 0 to 6 A / cm ² , an inner surface having a surface roughness of 0.1 μmRmax or less can be obtained.

Also, an aluminum alloy or the like can be polished by the same method.

It goes without saying that the pump according to the present invention can be used not only in the field of semiconductors but also in fields of biotechnology, medicine, food, chemical industry and the like.

If a corrosion-resistant material such as stainless steel, aluminum, or titanium is used as the material, a corrosive liquid can be transferred without causing chemical contamination.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

(Example 1) Example 1 is described using the vortex pump shown in Fig. 1 (a) as an example.

In this example, the cover 11, the casing 13, the impeller 13, etc.
The SUS316L material was die-forged into a predetermined shape, and after forging, heat treatment and pickling for scale removal were sequentially performed, followed by drilling and surface grinding, and then electrolytic composite polishing. The composite electropolishing was performed using the polishing apparatus shown in FIG.

In FIG. 1 (a), the inner surface indicated by A is set to 0.
Mirror finish to a surface roughness of 1 μm Rmax or less.

The quality of the feed water was measured for the pump using the system shown in FIG.

 Details of the measuring method will be described with reference to FIG.

Pump-ion exchanger-RO membrane (reverse osmosis membrane) -heat exchanger-heater cooler were connected in series via a stainless steel pipe, and high-purity water (source water, particles of 0.07 to 0.1 μm shown in Table 1) (80 / ml) was supplied from the pump port in the clean room, and the pump was operated to transfer the source water. As the stainless steel pipe, a pipe having an inner surface on which a passive oxide film was formed after electrolytic polishing was used.

At the sampling port at the pump outlet, sampling was collected and the particles in the sample were measured.

On the other hand, for comparison, the same measurement was performed for a canned pump having a structure in which the dead space was reduced as much as possible for ultrapure water, and a large amount of both particles of 0.1 μm or less and particles of 0.1 μm or more were generated.

Next, a start-up test of a specific resistance value was performed using the measurement system shown in FIG. In the start-up test, the specific resistance at the outlet of the cooler was measured over time, and the point in time when the specific resistance became 18.2 MΩ.cm was defined as the start point of the start. The measurement results are shown in Table 2 and FIG. As shown in Table 2 and FIG. 5, the pump according to the present example started up quickly, maintained a high specific resistance value of 18.2 MΩ after 30 minutes, and did not decrease.

On the other hand, in the case of the canned pump of the comparative example, 18.1
It took June to achieve 5MΩ · cm.

 The measurement of the specific resistance value was performed using a specific resistance meter.

In addition, when the TOC and the viable bacteria were examined for the sample, the TOC was 50 μgc or less, and the viable bacteria was 1/100 ml.
In addition, the measurement of viable bacteria was based on the membrane culture method.

Example 2 The same measurement as in Example 1 was performed on the centrifugal pump shown in FIG. 2A, and the same effect as in Example 1 was obtained for the particle generation suppressing effect. In addition, the same results as in Example 1 were obtained for the start-up test.

[Effects of the Invention] According to the present invention, the generation of particles is extremely small, and the liquid can be transferred without lowering the purity.
Therefore, transfer of high-purity water is also possible.

[Brief description of the drawings]

FIG. 1A is a sectional view of a pump according to Embodiment 1 of the present invention, and FIG. 1B is a perspective view of an impeller of the pump. FIG. 2A is a sectional view of a pump according to a second embodiment of the present invention, and FIG. 2B is a plan view of an impeller of the pump. FIG. 3 is a plan view and a sectional view of an apparatus used for electrolytic combined polishing. FIG. 4 is a system layout diagram for measuring the quality of supply water. FIG. 5 is a graph showing the rise time of supply water. (Explanation of reference numerals) 1... A tool connected to a drive shaft and rotated by a driving device 2... A disk-shaped cathode made of a copper plate formed under tool 1, 3. The exposed surface 4 formed in the shape of the electrolyte, the outlet of the electrolytic solution penetrated in the center of the cathode 2, the electrolyte outlet 5, the exposed surface 3 and the outlet 4 on the lower surface of the cathode 2 Except for the abrasive grains, 7 ...
… A thin film of electrically insulating paint, etc., 12… impeller, 13… casing, 14 …… sealing box, 16 …… rotary shaft, 17 …… bearing, 18 …… blade, 19 …… fluid Entrance, 20 ……
Fluid passage.

────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Tadahiro Omi 2-1-1-17-301, Yonegabukuro, Aoba-ku, Sendai, Miyagi Prefecture (72) Inventor Minoyuki Osaki 843--5 Kuji, Takatsu-ku, Kawasaki-shi, Kanagawa Prefecture Inside Machinery Co., Ltd. (72) Inventor Rokuhei Sato 843-5 Kuji, Takatsu-ku, Kawasaki City, Kanagawa Prefecture Inside Nikoku Machinery Co., Ltd. (72) Inventor Kenji Sato 4-1 Mizue-cho, Kawasaki-ku, Kawasaki City, Kanagawa Prefecture (56) References JP-A-60-222571 (JP, A) JP-B-57-47759 (JP, B2) (58) Fields investigated (Int. Cl. ⁶ , DB name) F04D 29/40 H01L 21/304 F04D 5/00 F04D 9/00 F04B 15/00

Claims (4)

(57) [Claims] 1. A pump characterized in that at least a main surface of a liquid contacting part surface in the pump is made of a rolled material or a forged material having a mirror-finished surface by electrolytic composite polishing. 2. The pump according to claim 1, wherein the surface roughness of the mirror surface is 0.1 μmRmax or less. 3. The pump according to claim 1, wherein the pump is a vortex pump. 4. The pump according to claim 1, wherein the pump is a centrifugal pump.