JPH0522108B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a metal-to-metal contact diaphragm valve used in piping lines of IC manufacturing equipment.

[Conventional technology]

An example of a conventional metal-to-metal contact diaphragm valve is explained with reference to Fig. 4. 1 is an inverted T-shaped valve box made of SUS material, with a fluid inlet passage 2 on one side and a fluid inlet on the other side. An outflow passage 3 is provided. The outlet side of the fluid inlet passage 2 is opened perpendicularly to the center of the valve body 1, and a protrusion 4 is formed around the opening, and the tip of the protrusion 4 forms a valve seat 5 having an extremely small arcuate cross section. 6 is a diaphragm formed by forming a thin plate of high tensile strength steel or the like into a circular dish shape; 7 is a diaphragm holder that presses the outer circumference of the diaphragm 6 against a step 8 in the valve box 1; There is. Reference numeral 9 denotes a bonnet that presses the diaphragm presser 7, and a flange 1 on the outer periphery of the lower end of the bonnet 9.
0, the vertical part 1 of the valve body 1 from above the bonnet 9.
The flange 13 on the inner periphery of the upper end of the nut 12 screwed onto the screw 11 on the outer periphery of a is hooked, and the nut 12 is tightened with a predetermined torque so that the outer periphery of the diaphragm 6 touches the flange 10 on the outer periphery of the lower end of the bonnet 9. The diaphragm holder 7 is held between the lower surface of the diaphragm holder 7 and the stepped portion 8 in the valve box 1, and is tightened. Center lower hole 14 of the diaphragm presser 7
A light diaphragm push-in piece 15 made of synthetic resin such as Teflon is fitted in advance,
Further, the tip of a stem 18 that has been previously screwed into the threaded portion 17 of the center hole of the bonnet 9 is fitted into the upper center hole 16 of the diaphragm holder 7, and is in contact with the diaphragm pusher piece 15. A bonnet cover 19 is placed over the bonnet 9, and a handle 21 is attached to a pin 22 at the upper end of the stem 19, which is fixed to the bonnet 9 with machine screws 20 and protrudes from the bonnet cover 19.
A pin 23 driven into the lower surface of the handle 21 is engaged with a groove 24 provided on the upper surface of the bonnet cover 19, thereby limiting the rotation angle of the handle 21.

In the diaphragm valve configured in this way, when the handle 21 is turned in the valve closing direction, the pin 2
The stem 18 fixed to the handle 21 by the handle 21 rotates together with the handle 21, descends the threaded part 17 of the bonnet 9, and presses the diaphragm push-in piece 15.
is pushed downward, thereby pushing the diaphragm 6 down toward the valve seat 5 in the valve body 1. When the handle 21 is further turned in the valve closing direction, the lower surface of the diaphragm 6 is pressed against the valve seat 5, and the valve is closed.

Such a diaphragm valve is characterized in that both the diaphragm 6 and the valve seat 5 in the valve body 1 are made of metal, and the valve seat 5 is not made of a soft material such as synthetic resin as in conventional valves. This is why it is called a metal contact type. Therefore, in order to strictly shut off the gas fluid flowing inside the valve when the valve is closed, both the upper surface of the valve seat 5 and the lower surface of the diaphragm 6 must be thoroughly polished to remove any minute scratches from those surfaces. It is necessary.

The reason why we decided to use a metal valve seat 5 instead of using a soft material such as synthetic resin for the valve seat 5 is that due to the porous nature of synthetic resin, the gas fluid flowing inside the valve body 1 is contained in the synthetic resin. The purpose is to prevent this from coming out from the valve seat again and having a negative impact on IC manufacturing.

When the handle 21 is turned in the valve opening direction, the stem 18 also rotates in the opening direction and the threaded portion 17 of the bonnet 9 is raised. As the stem 18 rises, the pressing force of the diaphragm 6 against the valve seat 5 is released, and further rotation of the handle 21 in the closing direction causes the lower end of the stem 18 to press against the diaphragm pushing piece 1.
Move away from the top of 5. The diaphragm 6 is molded into a dish shape and attached, and its own restoring force acts to restore the original dish shape. that time,
Since the diaphragm pushing piece 15 mounted on the upper surface of the diaphragm 6 is made of a light synthetic resin such as Teflon, the restoring force of the diaphragm 6 sufficiently overcomes the weight of the diaphragm pushing piece 15, and the diaphragm 6 returns to its original dish shape. Restore to shape. In this state, the valve seat 5 and diaphragm 6
The lower surface of the valve separates and the valve returns to its open state.

[Problem to be solved by the invention]

By the way, as mentioned above, in the conventional metal-to-metal contact type diaphragm valve, the diaphragm 6 is simply molded in the shape of a face down, so when the valve is closed, the diaphragm 6 does not touch the valve seat 5. A problem occurred in which undulation occurred on the circumference of the contact surface. For this reason, it is not possible to use a diaphragm 6 with a deep plate, and therefore it is not possible to provide a large gap between the valve seat 5 and the lower surface of the diaphragm 6 when the valve is opened, so that the so-called Cv There was a problem that the value became a small valve.

Furthermore, the lower surface of the diaphragm 6, which contacts the valve seat 5 when the valve is closed, must be polished so as not to leave even minute scratches, in order to completely prevent internal leakage of the valve as described above. However, since the diaphragm 6 has a flat surface, it is difficult and time consuming to completely remove minute scratches existing on the lower surface of the diaphragm 6 on the surface that contacts the valve seat 5 by polishing.

Furthermore, when the valve is closed, the lower surface of the diaphragm pushing piece 15 must remain completely parallel to the upper surface of the valve seat 5, and the lower surface of the diaphragm 6 must be pressed onto the circumference of the upper surface of the valve seat 5 with a uniform force. However, since complete closure is not possible, there are various problems such as the need to ensure accuracy in the thickness of the diaphragm pusher piece 15 and accurate perpendicularity of the guide surface of the diaphragm presser 7 with respect to the diaphragm pusher piece 15.

Therefore, the present invention can increase the gap between the valve seat and the lower surface of the diaphragm when the valve is open, and
The Cv value can be increased, and fine scratches on the bottom surface of the diaphragm and the top surface of the valve seat can be easily and quickly removed by polishing, and the thickness accuracy of the diaphragm push piece can be improved. An object of the present invention is to provide a metal-to-metal contact diaphragm valve that can press the lower surface of the diaphragm onto the circumference of the upper surface of the valve seat with uniform force without increasing the precision of the perpendicularity of the guide surface. .

[Means to solve the problem]

The metal-to-metal contact type diaphragm valve of the present invention to solve the above problems has a diaphragm made of a special steel thin plate pressed against the valve seat surface of a valve box made of SUS material etc. In a metal-to-metal contact diaphragm valve for shutting off fluid, the diaphragm is a diaphragm having an annular protrusion with an arcuate cross section that protrudes downward on the circumference near the center, and the annular protrusion of the diaphragm The valve seat against which the tip is pressed is an annular valve seat with a flat upper surface.

[Effect]

The metal-to-metal contact type diaphragm valve of the present invention configured as described above has an annular protrusion with an arcuate cross section that protrudes downward on the circumference near the center of the diaphragm. When pressed against the top of the seat, the diaphragm does not wave (wrinkle).
The tip of the annular protrusion can be brought into complete contact with the upper surface of the annular valve seat. Furthermore, when the valve is opened, a large gap can be created between the lower surface of the diaphragm and the upper surface of the annular valve seat, and the stroke of the diaphragm can be increased, making it possible to realize a valve with a large Cv value.

Furthermore, since the width of the arcuate cross-sectional view of the annular protrusion of the diaphragm is reduced when the valve is closed, the elastic restoring force when the valve is opened is stored here.

〔Example〕

An embodiment of the metal-to-metal contact diaphragm valve of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal cross-sectional view of the diaphragm valve, and since the structure of the valve and the principle of opening and closing of the valve are the same as those of the conventional diaphragm valve shown in FIG. 4, a description thereof will be omitted. The diaphragm valve of the present invention differs from conventional diaphragm valves in the structure of the diaphragm and the shape of the valve seat. That is, the diaphragm valve of the present invention replaces the conventional diaphragm 6 with a diaphragm 6' having an annular protrusion 30 with an arcuate cross section that protrudes downward on the circumference near the center, as shown in FIG. The valve seat against which the tip of the annular protrusion 30 of ' is pressed is replaced with an annular valve seat 5' having a flat upper surface.

In the metal-to-metal contact diaphragm valve of the present invention employing the diaphragm 6' having the above structure, when the valve is closed, the tip of the annular protrusion 30 of the diaphragm 6' is on the flat upper surface of the annular valve seat 5' as shown in FIG. Although the cross-sectional shape of the diaphragm 6' is deformed by being pressed against the valve seat 5', the diaphragm 6' is not undulated (wrinkled) and the tip of the annular protrusion 30 is perfectly aligned with the upper surface of the annular valve seat 5'. The gas fluid flowing inside the valve body 1 is blocked. In this way, the tip of the annular protrusion 30 of the diaphragm 6' can be brought into complete contact with the flat upper surface of the annular valve seat 5', so that when the valve is open, the lower surface of the diaphragm 6' and the upper surface of the annular valve seat 5' Therefore, the stroke of the diaphragm 6' can be increased, and a diaphragm valve with a large Cv value can be obtained.

Also, when the valve is closed, the annular protrusion 3 of the diaphragm 6'
Since the width of the arcuate cross section of 0 is reduced as shown by the arrow, elastic restoring force is stored here when the valve is opened.

However, in the diaphragm 6' having the above structure, since the part that comes into close contact with the flat upper surface of the annular valve seat 5' is the tip of the annular protrusion 30, it is only necessary to remove minute scratches existing in this part by polishing. Compared to the conventional diaphragm 6 in which minute scratches existing on a wide flat surface are removed by polishing, the polishing and removing work can be done easily and in a short time.

Furthermore, since the area around the annular protrusion 30 of the diaphragm 6' has increased rigidity, it is not necessary to accurately ensure the thickness accuracy of the diaphragm pushing piece 15, the perpendicularity accuracy of the guide surface of the diaphragm presser 7 with respect to the diaphragm pushing piece 15, etc. Even if the lower surface of the diaphragm retainer 7 is slightly inclined and hits the upper surface of the diaphragm 6', the tip surface of the annular protrusion 30 of the diaphragm 6' will not be deformed due to the increased rigidity, and the annular valve seat 5' will remain flat. It can be pressed evenly against the top surface to make it adhere tightly.

Furthermore, by providing the annular valve seat 5' with a narrow flat upper surface, the area that requires polishing to remove minute scratches can be minimized, similar to the diaphragm 6', and workability is improved. Become.

〔Effect of the invention〕

As detailed above, the metal-to-metal contact type diaphragm valve of the present invention is capable of increasing the gap between the valve seat and the lower surface of the diaphragm when the valve is open, thereby increasing the stroke of the diaphragm.
This is a diaphragm valve with a large Cv value. Further, since the area of the tip of the annular protrusion of the diaphragm and the upper surface of the annular valve seat is small, polishing and removing minute scratches existing in these parts can be done easily and in a short time. Furthermore, the lower surface of the diaphragm can be pressed against the upper surface of the valve seat with uniform force without increasing the accuracy of the thickness of the diaphragm pusher piece or the perpendicularity of the guide surface of the diaphragm holder to the diaphragm pusher piece, allowing the flow to flow inside the valve body. Gas fluid can be completely shut off.

[Brief explanation of the drawing]

FIG. 1 is a vertical sectional view showing an embodiment of the metal-to-metal contact diaphragm valve of the present invention, FIG. 2 is an enlarged sectional view of the essential parts of the diaphragm valve of FIG. 1 showing the state when the valve is open, and FIG. This figure is a cross-sectional view of a main part of the diaphragm valve shown in FIG. 1 when the valve is closed, and FIG. 4 is a longitudinal cross-sectional view showing a conventional metal-to-metal contact type diaphragm valve. DESCRIPTION OF SYMBOLS 1... Valve box, 5'... Annular valve seat, 6'... Diaphragm, 30... Annular protrusion of the diaphragm.

Claims (1)

[Claims] 1. In a metal-to-metal contact diaphragm valve in which a diaphragm made of a special steel thin plate is pressed against the valve seat surface of a valve box made of SUS material etc. to shut off gas fluid flowing inside the valve box, the diaphragm is ,
A diaphragm is formed with an annular protrusion having an arcuate cross section that protrudes downward on the circumference near the center, and the valve seat against which the tip of the annular protrusion of the diaphragm is pressed is an annular valve seat with a flat upper surface. A metal-to-metal contact type diaphragm valve featuring: