JPH06294471A - Diaphragm type fluid controller - Google Patents

Abstract

PURPOSE:To provide a diaphragm type fluid controller capable of extending the useful life and improving the controllability and control precision by improving the corrosion resistance and mechanical strength of a diaphragm. CONSTITUTION:A metal diaphragm 17 is formed with a high-elasticity, high- corrosion resistance alloy material made of Mo of 4-12%, Ni of 20-30%, Co of 30-45%, W of 3-5%, TiO of 5-3%, C of 0.03%, and Fe and inevitable impurities of the remainder as the basic constitution. When a spindle 18 is lowered and a diaphragm 17 is pressed to a plug seat 15 side to be seated by its tip, a cutoff opener is set to the closed state, the diaphragm 17 is displaced in the linear range to the upper pole P1 of the load-displacement characteristic, and the so-called displacement jump does not occur at all. The durability of the diaphragm 17 is sharply improved, the control precision and controllability of a controller are improved, and the passage resistance can be reduced when the controller is fully opened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvement of a diaphragm type fluid controller used in a semiconductor manufacturing apparatus or the like,
The present invention relates to a diaphragm type fluid controller capable of extending the service life and greatly improving controllability by improving the elasticity, strength, corrosion resistance and the like of the diaphragm.

[0002]

2. Description of the Related Art A diaphragm type fluid controller having a structure as shown in FIG. 4 is frequently used as a fluid controller in an apparatus for handling a high purity gas such as a semiconductor manufacturing apparatus.
54104). That is, in the above-mentioned diaphragm type fluid controller, the valve seat sheet C is formed on the bottom surface of the valve chamber B of the valve body A, and the valve seat sheet C is formed in the opposite shape to the pre-buckling reverse dish type (or partial spherical shell shape). Providing a metal diaphragm D,
By pressing the diaphragm D against the valve seat seat C by the valve rod E, the fluid passage F is closed, and by raising the valve rod E to restore the diaphragm D to its original shape by its elastic force, It is configured to open the passage.

Thus, the fluid controller shown in FIG.
The space volume can be reduced and the sliding portion in the valve chamber B can be reduced. As a result, the gas replacement property can be improved, the gas purity can be prevented from being deteriorated, and excellent practical effects can be achieved.

However, many problems remain to be solved in the diaphragm type fluid controller. The first problem is damage to the metal diaphragm D and service life. That is, in this type of conventional fluid controller, stainless steel or Inconel 718 is often used as the material of the metal diaphragm D, and in reality, the thickness is 0.1 to 0.1 mm.
Inverted plate type diaphragms made of thin stainless steel plates of about 0.2 mm are used alone or in a stacked state. The number of stacked diaphragms D is determined by the fluid pressure, and when the fluid pressure is high, the number of stacked layers increases.

Thus, the outer peripheral edge of the diaphragm D is clamped and fixed between the valve body A and the bonnet G. Therefore, when pressed toward the valve seat C by the valve rod E, extremely complicated stress acts on the diaphragm D. As a result, in reality, when the controller is repeatedly operated several thousand times, the diaphragm D is cracked, or the diaphragm loses its self-restoring force as described later, and the useful life of the diaphragm is extremely short. There is. Also, if the fluid to be handled is corrosive, cracks of the diaphragm will occur more frequently,
There is a problem that it takes time to repair and so on.

The second problem is the self-restoring force of the diaphragm D. This type of fluid controller may handle not only high-pressure fluid but also fluid of extremely low pressure. Therefore, the diaphragm D in the valve closed state needs to self-return to its original shape by its elastic force when the pressing force by the valve rod E is released. If there is no self-restoring force, the fluid passage is opened. Will not be done. Therefore, in a normal diaphragm type fluid controller, the displacement of the diaphragm D is limited to the displacement within the range in which the central part of the diaphragm D does not turn down downward when the central part of the inverted dish type diaphragm D is pressed. There is.

Thus, the relationship between the load and the displacement of the conventional diaphragm D is usually a curve in the state shown in FIG. 5, and has a curve having an upper pole point P ₁ and a lower pole point P ₂ .
In FIG. 5, curve No. 1 is an outer diameter 26 mmφ made of stainless steel, a diameter of the diaphragm clasp 24 mmφ, a radius of curvature R = 66 mm, a thickness 0.1 mm, and an opening angle β =
It is a measured curve for a diaphragm of 0.18 rad, and curve No. 2 is an outer diameter 26 m made of Inconel 718.
mφ, diameter of diaphragm clasp 24 mmφ, radius of curvature R = 54 mm, thickness 0.18 mm, opening angle β = 0.2
It is an actual measurement curve of a 2 rad diaphragm.

By the way, in the conventional diaphragm type fluid controller, in order to reduce the flow resistance in the controller by setting the displacement amount of the diaphragm large, the opening adjustment range by the diaphragm exceeds the lower pole point P ₂ . It has been expanded to the range (for example, Japanese Examined Patent Publication No. 4-54104). However, when the opening adjustment range of the diaphragm is expanded to a region exceeding the lower pole P ₂ as described above, the displacement jumps from P ₁ to P _{2 at the} load S point, and the displacement P ₁
There is a problem that the flow rate and pressure cannot be controlled with high precision because the opening degree between -P ₂ cannot be controlled.

Further, in order to avoid the displacement jump,
Set the displacement range of the ear diaphragm to the upper pole point P ₁Limited to
Even if it does, it can be seen from Fig. 5 in the conventional diaphragm.
As you can see, the change in the rising part Q is not linear,
It is extremely difficult to improve the control accuracy of the fluid controller.
It

[0010]

SUMMARY OF THE INVENTION The present invention has the above-mentioned problems in the conventional diaphragm type fluid controller, that is, the diaphragm is apt to be damaged by cracks, has a short service life, and has a load-displacement characteristic. There is a so-called jump region, lack of fluid controllability, and the range up to the upper pole P ₁ of the load-displacement curve is not linear,
The present invention is intended to solve problems such as difficulty in improving control accuracy, and provides a diaphragm type fluid controller capable of extending useful life and improving controllability and control accuracy.

The present inventor has made the material of the diaphragm used in the diaphragm type fluid controller more highly corrosion resistant and highly elastic so that the outer diameter is 8 to 30 mm and the thickness is 0.1 to 0. In the case of a diaphragm having a radius of curvature of 2 mm and a radius of curvature of about 15 to 70 mm, it is conceived that the rising portion Q of the load-displacement curve can be made to have more linearity. A displacement test was performed, and an operation test (service life test) was performed on the controller mounted with the displacement test.

The invention of the present application was created based on the results of the above-mentioned tests, and is a casing in which a plug seat 15 is provided on the bottom surface of a shallow recessed plug chamber 16 communicating with the fluid inlet 11 and the fluid outlet 12. A body 10; a metal diaphragm 17 disposed above the stopper seat 15 to keep the stopper chamber 16 airtight, and to elastically deform to stop the fluid against the stopper seat 15; above the diaphragm 17 A diaphragm 18 which is arranged so as to be able to move up and down, and which is seated on the stopper seat 15. The diaphragm 17 separates from the stopper seat 15 when opened by the restoring force due to the elasticity of the metal diaphragm 17. In the type fluid controller, the metal diaphragm 17 is made to have a Mo content of 4 to 12% and a Ni content of 20 to 30.
%, Co30-45%, W3-5%, Ti0.5-3
%, C 0.03% or less, and the balance being Fe and unavoidable impurities made of a highly elastic and highly corrosion resistant alloy material, which is the basic constitution of the invention.

[0013]

[Operation] By lowering the spindle and pressing the diaphragm toward the stopper seat side with its tip to make it rest,
The circuit breaker is closed. The displacement of the diaphragm is
Since the load-displacement characteristic is performed in a linear range up to the upper pole P ₁ , so-called displacement jump does not occur at all. As a result, the tip of the spindle and the diaphragm are not separated from each other, and the diaphragm is pressed downward with the two constantly contacting each other.

When the spindle is raised, the elastic force of the diaphragm itself, that is, the restoring force in the separating direction causes the diaphragm to be automatically separated, and the fluid controller is opened.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details will be described below based on an embodiment of the present invention shown in the drawings. FIG. 1 is a vertical cross-sectional view of an embodiment of the present invention, in which 10 is a stainless steel casing, 1
1 is a fluid inlet, 12 is a fluid outlet, 13 and 14 are fluid passages, 15 is a stopper seat, and 16 is a shallow recess forming a stopper chamber. Further, 17 is a metal diaphragm disposed above the stopper seat 15, 18 is a spindle, and 19 is a spindle drive device. The plug seat 15 is made of synthetic resin such as ethylene tetrafluoride resin and is fitted into the mounting hole 20. In this embodiment, the plug seat 15 is formed of synthetic resin separately from the housing 10.
It may be a metal cap seat formed integrally with the.

Diaphragm 17 disposed in the plug chamber 16
When the cap nut 21 is tightened, the outer peripheral edge of the cap nut 21 is pressed toward the housing 10 side through the gasket 22 and the presser foot 23, whereby the airtightness inside the stopper chamber 16 is maintained. The spindle 18 is arranged above the diaphragm 17 so as to be movable up and down in the vertical direction, and a pressing body 24 made of synthetic resin, rubber or the like is fitted to the lower end of the spindle 18. Further, a piston 25 is fixedly installed above the spindle 17, and operating air is supplied from an air inlet 26 to resist the elastic force of the spring 27 and prevent the spindle 18 from moving.
Is pressed downward.

FIG. 2 is a vertical sectional view of the diaphragm 17 used in the first embodiment of the present invention. The metal diaphragm 17 has Mo4 to 12%, Ni20 to 30%, and C.
30 to 45%, W3 to 5%, Ti 0.5 to 3%, C
0.03% or less and the balance being made of an alloy material composed of Fe and inevitable impurities, and as shown in FIG.
It is formed in a reverse dish type (partial spherical shell) in which the central portion of 6 mmφ, the diameter of the attached portion of 24 mmφ, the thickness of 0.1 mm, the opening angle β of 0.18 rad, and the radius of curvature R66.3 mm bulges upward.

Further, the mechanical and physical properties of the alloy material for the diaphragm have a maximum tensile strength of 267 kg / mm ² ,
Maximum hardness 680 HV, density 8.6 g / mm ³ , linear expansion coefficient 13 × 10 ⁻⁶ (20 to 50 ° C.) longitudinal elastic modulus 22 × 10
^-3 kg / mm ² , and the lateral elastic modulus is 8300 kg / mm ² .

FIG. 3 shows the load-displacement characteristic of each diaphragm used in the present invention, and the curve A shows the characteristic of the diaphragm according to the first embodiment. Curves B and C in FIG. 3 show load-displacement characteristics of the diaphragms according to the second and third embodiments of the present invention described later.

As is clear from the curve A in FIG. 3, in the diaphragm of the present invention, the upper pole point P ₁ of the load-displacement characteristic is
The portion X up to is a straight straight line, and the control accuracy is significantly improved as compared with the conventional diaphragms (No1 and No2 in FIG. 5).

The curve B in FIG. 3 is a load-displacement curve of the diaphragm of the fluid controller according to the second embodiment of the present invention. The diaphragm 17 has a weight ratio of Cr 18 to 2
3%, Mo7-10%, Fe1-10%, Cu2-6
%, Nb 2% or less, C 0.06% or less, and the balance being made of a corrosion-resistant and high-elasticity alloy consisting of Ni and unavoidable impurities. Specifically, the outer diameter is 20 mmφ, the diameter of the diaphragm clasp is 18 mmφ, and the thickness The central portion having a thickness of 0.1 mm, an opening angle of 0.14 rad, and a radius of curvature R = 62.6 mm is formed in an inverted dish type diaphragm that bulges upward.

Further, the metal diamond according to the second embodiment.
The mechanical and physical properties of alloy materials for flams have maximum tensile strength.
220 kg / mm², Maximum hardness 650 HV, density 8.
5 kg / mm³, Linear expansion coefficient 12 × 10^-6(20-50
℃), longitudinal elastic modulus 18 × 10 ³kg / mm²Is.

Further, the curve C in FIG. 3 is the third curve of the present invention.
It is a figure showing the load-displacement curve of the diaphragm of the fluid controller concerning an example. The diaphragm 17 is Cr1.
2-25%, Mo8-15%, Co25-45%, Nb
0.1 to 3%, C 0.03% or less, and the balance is made of a corrosion-resistant and high-elasticity alloy composed of Ni and unavoidable impurities.
2.5 mmφ, radius of curvature R = 66.4 mm, thickness 0.1
mm, and the opening angle β is 0.094 rad.

The mechanical and physical characteristics of the alloy material for a metal diaphragm according to the third embodiment are as follows: maximum tensile strength 320 kg / mm ² , maximum hardness 810 HV, density 8.
6 g / mm ³ , linear expansion coefficient (20 to 50 ° C) 13 x 10
^-6 , longitudinal elastic modulus 23 × 10 ^-3 , lateral elastic modulus 8500 kg
/ Mm ² .

In each of the above alloy materials for diaphragms of the present invention, Cr is mainly added to improve the corrosion resistance and strength, and when it exceeds 8% in the Ni base, the corrosion resistance effect is observed, and conversely 25 %, The malleability deteriorates and the workability deteriorates. Further, Mo mainly enhances the corrosion resistance in a corrosive environment containing halogen ions, and the addition of about 2% exhibits a corrosion resistance effect, and if it exceeds 15%, hot workability and machinability deteriorate.

Co is mainly added to enhance mechanical strength, fatigue resistance, hardness and elasticity, but if its content is 45% or more, cold workability is remarkably deteriorated. Nb stabilizes C, and Cr
It is added to prevent deterioration of corrosion resistance due to precipitation of grain boundaries of carbide and to increase hardness of the alloy. However, if it exceeds 3%, the workability is significantly reduced.

C forms Cr carbides and reduces the corrosion resistance, so it is preferable that the amount is as small as possible. But,
If it is 0.06% or less, there is no particular problem in terms of corrosion resistance. Further, although Fe causes a decrease in corrosion resistance, it is necessary for improving machinability, and if it is about 10% or less, no particular problem occurs in corrosion resistance. Further, Cu lowers the chemical resistance but increases the machinability. Therefore, the chemical resistance is 6% or less, and the machinability is 2% or more.

[0028]

[Table 1]

Table 1 shows the results of the corrosion resistance test of the diaphragm according to the present invention, and it can be seen that the diaphragm is particularly excellent in corrosion resistance as compared with SUS304 and Inconel 600.

[0030]

According to the present invention, in a diaphragm type fluid controller having a structure in which a so-called diaphragm is directly seated on a stopper and is separated by elastic force, the diaphragm is mixed with a special component. It is made of a corrosion-resistant and highly elastic alloy material having As a result, the diaphragm has excellent linearity in the region X below the upper pole point P ₁ of the load-displacement characteristic curve, and the displacement range with linearity becomes large, so that the controller controls The accuracy and controllability are improved, and the flow passage resistance of the fluid passage at the time of full opening can be reduced.

Further, the diaphragm used in the present invention has high corrosion resistance and mechanical strength, and the displacement range of the diaphragm is restricted to a region below the upper pole point P ₁ of the load-displacement characteristic curve. As a result, the durability of the diaphragm is significantly improved, and it has been confirmed that the damage due to the corrosion of cracks does not occur even after the operation of 100,000 times. As described above, the present invention has excellent practical utility.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an example of a diaphragm type fluid controller according to the present invention.

FIG. 2 is a vertical sectional view of a diaphragm used in the fluid controller according to the first embodiment of the present invention.

FIG. 3 is a load-displacement characteristic curve of a diaphragm used in the fluid controller of the present invention.

FIG. 4 is a vertical cross-sectional view of a conventional diaphragm type fluid controller.

FIG. 5 shows an example of a load-displacement characteristic curve of a diaphragm used in a conventional fluid controller.

[Explanation of symbols]

10 is a housing, 11 is a fluid inlet, 12 is a fluid outlet, 13 ...
Reference numeral 14 is a fluid passage, 15 is a stopper seat, 16 is a stopper chamber, 17 is a diaphragm, 18 is a spindle, 19 is a drive device, 20 is a mounting hole, 21 is a cap nut, 22 is a gasket, 23 is a presser foot, and 24 is a presser. A body, 25 is a piston, 26 is an air inlet, 27 is a spring, P ₁ is an upper pole, P ₂ is a lower pole, S is a load at an upper pole P ₁ , and X is a linear displacement region.

Claims (3)

[Claims] 1. A housing (10) having a stopper seat (15) on a bottom surface of a shallow recessed stopper chamber (16) communicating with a fluid inlet (11) and a fluid outlet (12), and a stopper seat (15). A metal diaphragm (17) which is disposed above the plug chamber (16) to keep the plug chamber (16) airtight, and which is seated on the plug seat (15) by elastic deformation and shuts off the fluid; the diaphragm (17). It is composed of a spindle (18) which is arranged so as to be able to move up and down freely and which is seated on the stopper seat (15), and the diaphragm (17) is capped when opened by the restoring force due to the elasticity of the metal diaphragm (17). In a diaphragm type fluid controller adapted to be separated from a seat (15), the metal diaphragm (17) is replaced with Mo4-12%, Ni20
~ 30%, Co30-45%, W3-5%, Ti0.5
A diaphragm type fluid controller characterized by being formed of a highly elastic and highly corrosion resistant alloy material composed of ˜3%, C0.03% or less and the balance Fe and unavoidable impurities. 2. The diaphragm type fluid controller according to claim 1, wherein the metal diaphragm (17) is C
r18-23%, Mo7-10%, Fe1-10%, C
A diaphragm type fluid controller characterized by being formed of a highly elastic and highly corrosion resistant alloy material comprising u2-6%, Nb2% or less, C0.06% or less and the balance Ni and inevitable impurities. 3. The diaphragm type fluid controller according to claim 1, wherein the metal diaphragm (17) is C
r12-25%, Mo8-15%, Co25-45%,
A diaphragm type fluid controller characterized by being formed of a highly elastic and highly corrosion resistant alloy material containing Nb 0.1 to 3%, C 0.03% or less and the balance Ni and inevitable impurities.