JPS61144468A - High speed cylinder device - Google Patents

Abstract

PURPOSE:To manufacture a piston member having high strength and heat- resistance with a specific gravity of light metal's level by mixing whiskers having a small specific gravity or long fibers in a light metal matrix. CONSTITUTION:Whiskers and fibers are compounded with light metal of a matrix to form a piston. It is necessary to set the volume percentage of whiskers in composite material within the range of 10-50%. The volume percentage of the fibers should be within the range of 20-70%. A Al-base, Mg-base or Ti-base light alloy is used for matrix.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a high-speed cylinder device, and more particularly to a high-speed cylinder device suitable for a quick-acting valve driven at high speed used in a protection device of an ultra-high vacuum system.

[Technical background of the invention and its problems]

For example, in an ultra-high vacuum system used in a nuclear fusion device, etc., a protection device having a quick-release valve that operates at high speed is provided in the vacuum vessel to prevent atmospheric air from entering in the event of an unexpected accident.

Figure 3 shows the system of such ultra-high vacuum system protection equipment (
. In FIG. 3, an ultra-vacuum vessel 1 and a measurement station 2 are connected by a beam channel 3, and a pressure detector 4 is provided in the middle of the beam channel 3 to detect intrusion of the atmosphere. A detection signal from the pressure detector 4 is input to a system controller 5, and an operation command for the electromagnetic valve 6 is output from the system controller 5.

A valve seat 8 of a quick-release valve 7 is attached to the beam channel 3, and the valve body 9 of the quick-release valve 7 is driven to open and close by a high-speed drive device 11 that operates with fluid from a fluid source 10. In this ultra-high vacuum system protection system, if air accidentally enters the vacuum system during measurement at the measurement station 2, the pressure detector 4 will detect the air entry as soon as possible, and a signal will be sent to the controller 5. It looks like this. In response to the signal, the controller 5 outputs an operation command to the electromagnetic valve 6, switches the flow from the fluid source 10, and operates the high-speed drive device 11. The valve body 9 connected to the high-speed drive device 11 is
Close the valve seat 8 rapidly. This series of operations must be completed before the entered air reaches the quick-release valve 9 to reliably prevent air from entering the ultra-high vacuum container 1. The intrusion speed of the atmosphere is approximately the speed of sound (approximately 340 m/5e
c) Therefore, for example, if the distance from the pressure detector 4 to the valve seat 8 is 3 m, the operating time of the entire protection system is required to be 8.8 m5ec or less, and the pressure detector and control 0
- After subtracting the delay time of A, the operating time of the quick-acting valve itself is 5 m.
It is required that it be 5ec or less.

FIG. 4 shows an example of the structure of the quick-release valve 7. A piston-type speed drive device 11 is integrally assembled with the quick-release valve 7. A fluid source 10 is connected to the cylinder 12 of the high-speed drive device 11 via a flow path 14.15 having a solenoid valve 6, a pressure reducing valve 13, etc.
The valve body 9 is connected to a piston rod 17 of a piston 16 that slides within the cylinder 12. In addition, 18 is a valve body communicating with the beam channel 3,
19 is a stopper for stopping the valve body 9 at the maximum opening position.

In such a quick-release valve 7, the pressure in the air chamber [Al2O] in the cylinder 12 and the pressure in the air chamber [8] 2i are usually set by the pressure reducing valve 13 so that the relationship [Al < [8] holds. , the piston 16 is pulled up to the position shown in the figure, and the valve body 9 is kept open.

When air enters, the solenoid valve 6 is energized and the air chamber [8]
By releasing the pressure of 21, the piston 16 is pushed down by the pressure of the air chamber [Al2O, and the valve body 9 pushes the valve seat 8 down.
The opening is closed. In order to drive such a quick-release valve 7 at high speed, it is necessary to rapidly reduce the pressure in the air chamber [8121, but in this case, the piston 16 must be configured to be able to respond to pressure fluctuations in the shortest possible time. .

Conventionally, it has been common to use SUS material for the piston of this type of high-speed cylinder device, but such iron-based material increases the weight of the piston and slows down the response time.

In order to reduce this problem, the use of aluminum alloy materials is being considered, but if only aluminum alloy is used, high-temperature strength will be increased due to baking treatment (approximately 150℃) to achieve ultra-high vacuum. There is a risk of light aging due to second phase precipitation such as overaging. In addition, aluminum alloys have a low Young's modulus, low rigidity, and a high coefficient of thermal expansion, so it is difficult to apply them directly to sliding parts that require precision dimensions, such as pistons.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a high-speed cylinder device that is lightweight, has high strength, is heat resistant, and has excellent wear resistance.

[Summary of the invention]

In order to achieve the above object, the present invention provides a piston with A
It is characterized by being made of a reinforcing material that is a composite of whiskers or fibers made of a heat-resistant inorganic material at a predetermined volume percentage in a light metal matrix such as L.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

In this example, the piston is constructed by combining the whiskers and mM with the light metal of the matrix. In this case, first, a preform (preformed body) is created by molding Raiskaya fiber into a predetermined shape, and pressure molding is performed at a high temperature by a method such as an infiltration method, a powder method, or a diffusion method.

In whisker preform molding, since untreated whiskers are powdery and cannot be molded into a predetermined shape, preform molding is performed using water or an organic solvent as a medium. For example, a suspension of SiC whiskers in an aqueous solution or an organic solvent is prepared, only the solvent solution is removed through a filter paper, the SiC whiskers are pressurized in a wet state, and the preformed SiC whiskers are dried. The volume fraction of the preformed body obtained in this way (SiC in the volume of the whole molded body)
The whisker volume percentage) is 19%.

Therefore, the lower limit of the volume fraction of SiC whiskers required for the preform is approximately 10%. It is possible to manufacture SiC whiskers with a large volume fraction required for preforms, but when placing the preform in a mold and injecting light metal such as Al and pressurizing it, if the volume fraction is too large, A7 Since the molten metal does not sufficiently infiltrate into the SiC whisker preform, the effect of composite reinforcement becomes small.

Figure 2 shows the characteristics of an A6061 composite material reinforced with SiC whiskers when the SiC whisker volume fraction was varied. As the volume fraction of SiC whiskers increases, the properties of the composite material gradually improve, but even if it exceeds 50%, there is almost no improvement in properties, and on the contrary, it becomes difficult for the light metal melt in the matrix to infiltrate inside the preform, and Pressure molding cannot be performed and defects become large. Therefore, it can be seen that it is necessary to set the volume fraction of whiskers in the composite material in the range of 10 to 50%.

As a method for manufacturing the composite material, a powder method or a solid phase bonding method can be used instead of the above-mentioned dipping method.

On the other hand, in the case of fiber preform molding, the connection is made using an organic binder, but whether the manufacturing method is the infiltration method, the powder method, or the solid phase bonding method, the molding is performed at a high temperature of about 500 to 800°C. The binder scatters at 200-300°C. For this reason, in 11M with a volume fraction of 20% or less, local deviation occurs, and variations in the tal II volume fraction become a big problem. In addition, the mechanical strength of fibers increases proportionally as the volume fraction increases, but when the volume fraction exceeds 70%, the matrix metal cannot completely wrap around the fibers, resulting in a material with many defects. Therefore, it is necessary for the volume fraction of fibers to be in the range of 20 to 70%.

A specific example will be explained below.

In the quick-acting valve shown in Fig. 4, the piston 16 is made of austenitic stainless steel (SUS304), aluminum alloy (A2024), or aluminum composite material (Vf30%-
8i C Whisker/A1) I) Three types were created. By comparing the properties of these three types of materials, the mechanical properties shown in Table 1 and the physical and other various properties shown in Table 2 were clarified. Note that the aluminum composite material was manufactured by an infiltration method. Also, whisker is simply abbreviated as W.

Table 1 Table 2 For example, the conditions that should be met in a quick-acting valve for a high-speed cylinder device related to an ultra-vacuum system are: (i) It must be lightweight for quick response; and (i) It must be lightweight to withstand pressure fluctuations in the fluid source. It must have high strength and high elasticity, c) It must have structural stability even against m 14f during baking, 2) It must have a small coefficient of linear expansion in order to be driven at high speed in the cylinder, and e) It must be resistant to It is required to be abrasive.

Based on the properties in Tables 1 and 2, SiC(w)/A has the best properties under the conditions a) to e) above.
It turns out that it is J. In particular, item (a) is important in order to obtain high reliability as a quick-acting valve. The reduction in operating time due to the reduction in the weight of the piston is determined by the following kinematics equation. From the equation of motion F=ma, a=□・・・・・・(1) (However, F: Force acting on the object, m: 1iffi of the object
, a: Acceleration due to F) When the quick-opening valve moves a certain distance, from the equation of uniformly accelerated motion, S = -at (2) (However, S
: Distance traveled, V. = initial velocity, t: time, a: acceleration due to F) Substituting equation (1) into equation (3) yields 5US304 and Si shown in Tables 1 and 2.
The operating times for two types of materials, C(w)/A, are compared using equation (4). However, S and F are constant, and m-
In the case of ρ
The operation is completed in about 60% of the operating time.

For actual piston operation, cylinder pressure accuracy,
#! Since factors such as friction coefficient and contact surface pressure have a large effect on the operating time, the SiC(w)/A piston is 5U.
Naturally, the operating time of the piston in S304 is not completely reduced by 60%.

For this reason, we tried reducing the operating time of the quick-release valve. Third
The table shows the results for three types of piston materials.

Table 3 5tJS30.4 piston is 4.8m5ec.

3.9m5ec for SiC(w)/Ao piston.

A2042 ended up not working due to a problem. As mentioned above, the operating time of the quick-release valve itself is 5Ti.
Lsec or less is required, 5tJs304
The response of the piston is close to the limit value, and it lacks reliability as a high-speed cylinder intended as a protection device. Additionally, aluminum alloy pistons have many troubles and are currently unsuitable for use.

In addition, it is also possible to combine whiskers and seas. For example, in the disk-shaped piston 16 shown in FIG. 1, long fibers 24 are arranged at the center of the inner periphery, and whiskers or short lIMs 25 are arranged on the outer periphery surface. In this case, the inner peripheral surface portion of Wika or Chikushi N25 has a smaller effect on strength coefficient and linear expansion coefficient than Junken N24, but has a greater effect on wear resistance. Conventional 5US304, aluminum alloys, and the like exhibit a significant decrease in mechanical strength at temperatures above 100° C., but it is also known that fatigue strength and creep strength also decrease significantly. However, for aluminum composite materials mixed with fibers and whiskers, the mechanical, physical, and metallurgical properties do not change from those at room temperature up to about 300°C.

Note that the piston matrix of the high-speed cylinder device according to the present invention is Aj! Not limited to Mg-based,
It can also be applied to light alloys such as Ti-based alloys. In addition, as whiskers or fibers, SiC type, Al2O
A heat-resistant inorganic material of type 3, c type, B type, or s + -T i-c type can be used. Furthermore, if a composite material is obtained by arranging metal or metal in a certain direction in a light metal matrix, the characteristics of the piston will be improved.

〔Effect of the invention〕

As described above, according to the present invention, Aj! It is possible to create a piston member that has high strength, heat resistance, and abrasion resistance while maintaining a specific gravity at the same level as a light metal such as. In particular, as the piston weight is reduced to pumice, the closing time of the quick-release valve during operation can be shortened, which has the effect of significantly improving reliability and light operation. In general, such a piston member not only has a light weight, high specific strength and high specific elasticity, but also exhibits minimal deterioration of various properties even in high-temperature regions of 100°C or higher, which cannot be used with conventional He1 alloy materials. It also has good heat resistance.

Moreover, SiC type, Al2O3 type, c type, B type, Si
Whiskers as a composite material based on the -T i -c system! ! Navy blue has a short half-life similar to light metals such as matrix A7, and even in fields where induced radioactivity is a problem, it is a more preferable material than high-strength aluminum alloys containing additives such as Cu, Mn, and Zn. The effect of

Thus, it is lightweight, high strength, heat resistant, abrasion resistant and rough resistant.
By having good characteristics such as IlfJ4, it is possible to improve reliability and soundness as a quick-release valve of a high-speed cylinder device used in fields such as nuclear fusion and high-energy physics accelerators.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing a piston according to an embodiment of the present invention, Fig. 2 is a graph showing the characteristics of Δ6061 alloy reinforced with whiskers, and Fig. 3 is a system diagram showing a protection device for an ultra-high vacuum system. , FIG. 4 is a sectional view showing the structure of the quick-release valve. 7... Quick-release valve, 9... Valve body, 12... Cylinder,
16... Piston, 24... Long fiber, 25... Whisker or short fiber. Applicant's agent Hisashi Hatano Figure 1 Figure 2

Claims (1)

[Claims] 1. In a high-speed cylinder device equipped with a piston that operates at high speed using fluid pressure, the piston has a volume ratio of 10 to 50%.
Whiskers made of heat-resistant inorganic material, or a volume fraction of 20
A high-speed cylinder device characterized in that it has a composite reinforced structure in which one or both of fibers made of ~70% heat-resistant inorganic material is mixed into a light metal matrix. 2. The high-speed cylinder device according to claim 1, wherein the whiskers or fibers are SiC-based, Al_2O_3-based, C-based, or B-based inorganic materials. 3. The high-speed cylinder device according to claim 1, wherein the light metal matrix is an Al-based, Mg-based, or Ti-based light metal. 4. The high speed cylinder device according to claim 1, wherein the whiskers or fibers are unidirectionally arranged in the light metal matrix. 5. The high-speed cylinder device according to claim 1, wherein the piston has long fibers disposed at the center in the circumferential direction, and whiskers or short fibers are disposed on the outer peripheral surface side of the piston in the circumferential direction. 6. The long fibers are made of any one of Al_2O_3-based, SiC-based, C-based, B-based, or Si-Ti-C-based inorganic materials, and the whiskers or short fibers are made of SiC-based or Al_2O_3-based inorganic materials. High-speed cylinder device as described in section.