JPS60179575A - Gate valve for vacuum - Google Patents

Abstract

PURPOSE:To eliminate permanent set in a knife edge of a gate seal in time of baking, by forming a metal seal ring and a gate seal operating device with an alloy having a shape memory effect. CONSTITUTION:A seal ring 12 and each of links 19 and 20 are formed with an alloy having a shape memory effect. In time of baking, a valve body 11 grows large in its interval between top and bottom inside a hollow chamber as much as a portion for delta1 due to heat expansion. On the other hand, the seal ring 12 increases in size as much as a portion for delta2 owing to the shape memory effect. Here delta1 and delta2 are selected in advance so as to be equalized. When baking advances, an operating device grows large as much as a portion for delta3 but since these links 19 and 20 function so as to be decreased as much as a portion for delta4 owing to the shape memory effect, vertical size for the operating device or the like keeps up measurements in room temperature in consequence.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to the improvement of vacuum gate pulp, and particularly to the improvement of an all-metal vacuum gate valve suitable for ultra-high vacuum applications.

[Background of the invention]

Vacuum gate pulp made of all-metal has come to be widely used as ultra-high vacuum equipment becomes larger, but the important points that affect the sealing performance of all-metal vacuum gate valves are: , maintaining elastic deformation on the sealing surface due to knife-like suppressive contact between the movable metal gate seal and the stationary metal seal ring;
In addition, it is necessary to prevent the sealing surface from being damaged by fine dust or the like.

Among these, the former, maintaining elastic deformation, becomes a particular problem when a vacuum device is baked at high temperatures, for reasons that will be explained later.

゛ Fig. 1 is a system diagram showing the driving method of a vacuum gate valve made of all foreign metal. It is located between 4 and 4.

A heater (not shown) and a paking device 5 made of a heat insulating material are provided outside the all-metal vacuum gate valve. In addition, 6 is a piston for driving the gate valve, 7 is a d magnetic switching valve, 8 is an air distribution L, 9 is an air tank,
lO is a compressor.

The driving system of the vacuum gate valve is constructed as described above, and the gate valve is opened and closed by compressed air from the compressor 10 via the gate valve driving piston 6.

The structure of the vacuum gate valve 1 itself is shown in FIG. The vacuum gate valve 1 includes a valve body 11 having a supply/discharge port 2 and a hollow chamber, a metal seal ring 12 attached to the valve body, and a metal seal ring 12 that moves within the hollow chamber R of the valve body 11 to connect to the seal ring 12. and a metal gate seal 13 that opens and closes the valve by interaction with the metal gate seal 13.

The closing operation, that is, the sealing of the supply/discharge port 2 is performed by a gate seal operating device 23 using a link mechanism.
and is rotatably supported on this bracket by a pin 16,
Rollers 17 and 18 roll along the earthen walls of the hollow chamber of the valve body 11, and one end of the rollers 17 and 18 are attached to the bracket 15 in the same manner as the pin 1.
6 is rotatably supported, and the other end is a metal gate seal 1.
Link 19.20 rotatably supported by pin 16 on 3
and a roller 22 rotatably supported by a pin 16 on a support arm 21 protruding from the side opposite to the rod of the seal ring 12.
It is composed of.

That is, when compressed air is supplied from the air tank 9 to the driving piston 6 via the air pipe 8 and the electromagnetic switching valve 7, the rod 14 extends to the left in the figure, and accordingly, the gate seal operating device 23 also moves its roller. 17 and 18 move to the left while rolling along the earthen wall of the hollow chamber H. Then, the roller 22 comes into contact with the side wall of the hollow chamber box on the side opposite to the rod 14.
When the metal gate seal 13 reaches the position indicated by the dotted chain line, further movement of the metal gate seal 13 is prevented, but the bracket 15
continues to move to the left.t1 The metal gate seal 13 is guided by the roller 22 and moves towards the link 1.
9.20, and brought into intimate contact with the sealing ring 12 with an appropriate pressing force.

By the way, in order to create an ultra-high vacuum, the vacuum device n is heated at a high temperature T2 (approximately 200C) (with the gate valve closed). Room temperature 'l'+ before time t1
(approximately 20C) valve leak i + tQ (approximately I
X 10-'Torr 1/s)
l Valve leakage ijl' Q 2 at room temperature T1 after the completion time t2 of shite painting is approximately 2 X l 0
-6 Torr 1/s, which generally increases by about 100 to 200 times, which tends to impair sealing performance.

When the cause of this was investigated through various experiments, the following was found. In other words, when paking, vacuum gate valve 1
, the valve body 11 and seal ring 12 are first heated to a high temperature, but the metal gate seal 13 placed in the hollow chamber of the vacuum gate valve 1 and its gate seal operating device 23 are
Because there are only a few parts in contact with other objects, and most of them are in a vacuum, it takes time for them to heat up to a high temperature. On the other hand, as described above, the metal gate seal 13 is pressed into contact with the seal ring 12 by the appropriate pressing blade of the gate seal operating device 23 using compressed air (constant pressure Pi) from the air tank 9, but at the initial stage of paking. As mentioned above, there is a temperature difference between the valve body 11 etc. and the gate seal operating device 23, and the former expands due to heat, and the vertical distance in the hollow chamber becomes narrow. The latter undergoes almost no thermal elongation and maintains the dimensions of 7 mm, so when a constant operating air pressure P1 is applied, the chamber + m T
From 1 o'clock, the rod 14 and the bracket 15 move to the left, and the links 19 and 20 become nearly upright, allowing the gate seal 13 to be pressed into contact with the seal ring 12 using the appropriate pressing blade, the same as at room temperature. Become.

However, as the baking progresses, the temperature of the gate seal operating device 230 gradually increases, and the gate seal operating device 23
When the valve pod 11 is thermally elongated and its vertical dimension increases, the valve pod 11 is already fully extended and the vertical distance within the hollow chamber is kept almost constant. The push-down blade by the gate seal operating device 23, one! Shimetal Gate - Seal 13 and Seal Link 1
The suppressing contact force of No. 2 becomes excessive than the appropriate value. Moreover, during paking, the metal gate seal 13 is heated to a high temperature and the knife seal 13a is easily deformed.
When such an excessive pressing contact force is applied, "sagging" occurs as shown by the broken line 138' in FIG. 4, and the contact area with the metal seal ring 12 increases, resulting in a knife-like pressing contact It was found that elastic deformation in the seal could not be maintained and sealing performance was impaired.

[Purpose of the invention]

The present invention has been made in view of this, and its purpose is to provide a vacuum gate valve that eliminates the "sagging" of the gate seal during paking and has good sealing performance. .

[Summary of the invention]

That is, in the present invention, the metal seal ring and the gate seal operating device are formed of an alloy having a shape memory effect, and the shape memory of both is made to have opposite thermal elongation to the thermal elongation during baking. It was designed to achieve the intended purpose.

[Embodiments of the invention]

The present invention will be explained below in detail based on the illustrated embodiments. FIG. 5 shows a cross section of the main parts of the vacuum gate valve that includes the metal gate seal 13, seal ring 12, and gate seal operating device 23. 2nd in the diagram
Parts that are the same as those in the figures are given the same reference numerals.

This embodiment differs from the conventional example shown in FIG. It is made of an alloy that returns to its original shape when removed.

That is, as shown in FIG. 6, this seal ring 12 is made so that its initial shape is dimension A1 and the shape memorized by shape memory processing is dimension B shown by the two-dot chain line. Therefore, when heated, this seal ring has a B-
The size increases by A=δ.

Furthermore, the links 19 and 20, as shown in FIG. 7, are made so that the dimensions of the initial shape are the dimensions memorized by the C1 shape memory process, as indicated by the two-dot chain line. Therefore, during heating, compared to normal times, C-
The size is reduced by D=δ4.

The closing operation of the vacuum gate valve having the seal ring and link formed in this way will be explained based on FIG. It is heated and reaches a high temperature.At this time, the valve body 11
Due to thermal expansion, the vertical distance inside the hollow chamber is δ! only becomes larger. On the other hand, the seal ring 12 has δ2 due to the shape memory effect.
The dimensions increase by only Here, the increase dimension δ2 of the seal ring 12 due to shape memory treatment is defined as the thermal elongation δl of the pulp body 11.
If the distance from the upper surface of the hollow chamber to the upper surface of the seal ring 12 is selected in advance to be equal to δ1 and C2,
Since the dimensional changes of change in the direction of canceling each other, the room temperature T1
Keep the time distance and therefore bracket as before) 1
5 will not move more than necessary to the left in the figure. As the paking progresses further, the temperature of the gate seal operating device 23 etc. gradually rises, causing thermal elongation of the operating group +i:f'z3 etc., and furthermore, the dimension in the F direction increases by δ3, but the link 19. 20 acts so as to decrease by δ4 due to the shape memory effect, so the dimensional change of the gate seal operating device 23, etc. acts in a direction where δ and 64 cancel each other out, and the vertical dimension of the operating device 23, etc. This means that the dimensions will be maintained at 1.1 o'clock at room temperature.

Therefore, metal gate seal 13 and seal ring 12
This alleviates the fear that the suppressive contact force will be excessive.

Also, in the final stage of paking, when the heating by the paking device 5 is finished, the valve body 11. The temperature of the seal ring 12 first decreases, and after a while, the temperature of the gate seal operating device 23 and the like decreases. That is, there is a delay in the time of thermal contraction of both. Even at this time, the shape of the seal ring 12 returns to its normal state in response to the contraction of the valve body 11 (7), so that the distance from the upper surface of the hollow chamber to the upper surface of the seal ring 12 is kept constant.

Furthermore, although the gate seal operating device 23 and the like also contract as the temperature decreases, the shape of the links 19 and 20 returns to normal, so that the dimensions of the gate seal operating device 23 and the like in the upper F direction are kept constant.

Therefore, since the vertical dimensions are always kept constant during normal times, during the initial stage of baking, during the continuation of baking, and at the end of baking, the gate seal 13 and seal ring 1
A strong pressing contact force is continuously applied between the two. Therefore, even during paking, the knife edge 13a of the gate seal 13 will not generate [7v, 9J] due to the suppressing contact force becoming excessive, and the sealing performance will not deteriorate.

〔Effect of the invention〕

As explained above, in this Sekimon, the metal seal link and the gate seal operating device are made of an alloy that has a shape memory effect, and the shape memory of both is mutually exclusive against thermal elongation during baking. Since the memory is formed so that the thermal elongation will be such that the metal gate seal will not come into contact with the metal seal ring with excessive pressure, the metal gate seal will not "sag".
Thus, a vacuum gate valve with good sealing performance is obtained without any loss in sealing performance.

[Brief explanation of drawings]

Figure 1 is a schematic diagram showing the drive system of a vacuum gate valve, Figure 2 is a sectional view of the main parts of a conventional vacuum gate valve, and Figure 3 is a schematic diagram showing the drive system of a vacuum gate valve.
Figures (a) and (b) are characteristic diagrams showing the relationship between operating air pressure, valve temperature, and leakage amount in a conventional vacuum gate valve.
5 is a sectional view of a gate valve according to an embodiment of the present invention, and FIG. 6 is an enlarged sectional view showing the sole ring 11 of the present invention. The i7 view shows the initial shape and the shape at the time of shape memory, and Figure 7 shows the initial shape and shape 0 of the link of the present invention.
FIG. 1... Vacuum gate valve, 11... Valve body,
12...Metal seal ring, 13...Metal gate seal, 19.20...Link, 23...Goo 1
Seal operation device +I=. Agent Patent Attorney Akio Takahashi 1st day ¥J2121

Claims (1)

[Claims] 1. A valve body having a supply/discharge port, a metal seal ring, and a hollow chamber, a metal gate seal disposed within the body to open and close the supply/discharge port, and a press contact between the metal gate seal and the metal seal ring. In the vacuum gate valve, the valve body is baked, and the metal seal ring and the gate seal operating device are provided with a gate seal operating device that releases the metal seal ring and the gate seal operating device.
A vacuum gate valve characterized in that it is formed of an alloy having a shape memory effect, and the shape memories of the two are formed so that the thermal elongation is opposite to the thermal elongation during baking.