JPH02290613A - Manufacture of hollow extruded aluminum material to be formed for vacuum - Google Patents

Abstract

PURPOSE:To decrease the adsorption and occulusion of vacuum deteriorating materials by forming so as not to bring the inner part of hollow aluminum material to be formed into contact with the atmosphere including moisture while the material is subjected to extruding and forming at the specified temperature. CONSTITUTION:A billet 2 is subjected to extrusion molding at the extruding temperatures of 300-450 deg.C, the mixed gas 26 contg. 7% oxygen and the balance argon is ejected from a jet nozzle 6, the tip opening part of the material to be formed 15 which is slightly pushed out is sealed by pressure welding with a press and a sealed end 27 is formed. A cooling and aging treatment are performed while the mixed gas 26 is sealed. At last, the hollow extruded material 15 is manufactured by cutting both the sealed ends 27, 28 by no use of oil and without air blow. Because a dense and thin oxided film is formed on the inner face, the adsorption and occulusion of the vacuum deteriorating materials is less and degassing treatment is simple.

Description

[Detailed Description of the Invention] Industrial Field of Application This invention is applicable to particle acceleration vibrators used in accelerators such as synchrotrons, high vacuum devices such as thin film manufacturing devices, surface analysis devices, and nuclear fusion devices. The present invention relates to a method for manufacturing a hollow extruded aluminum material for vacuum use.

In this specification, aluminum includes pure aluminum and alloys thereof.

Problems with Prior Art and Inventions For example, until now stainless steel has been mainly used as a material for particle acceleration vibrators, but recently aluminum has been found to be suitable for this purpose and is being used. It's coming. The reasons for this are that compared to stainless steel, aluminum is less likely to generate induced radiation and has a shorter decay time even if it does occur, has good thermal and electrical conductivity, and has a small surface gas release coefficient.
This is because it is excellent in terms of light weight and good workability. The inside of this particle acceleration pipe must be kept at a high vacuum in order to allow particles to pass through it at high speed. Therefore, an important issue is how to create a high vacuum inside the vibrator.

Conventionally, in order to create a high vacuum inside the particle acceleration pipe,
After degreasing the inner surface of the pipe with an organic solvent, etc., approximately 15
Previously, heat degassing treatment was repeatedly performed at 0°C for about 24 hours, and in combination with this treatment, discharge cleaning was performed in hydrogen gas, argon gas, oxygen gas, etc. In addition to requiring a long time and being inefficient, the degree of vacuum was still not fully satisfactory.

In order to maintain a high degree of vacuum inside the particle acceleration pipe, it is important to reduce the amount of gas released from the inner wall of the pipe after it is made into a product.

As a result of repeated experimental research on this point, the present inventors have found that the state of the coating on the inner surface of the aluminum pipe has a large effect on the degree of vacuum.

As is well known, aluminum is a metal that is very easily oxidized, and an oxide film is formed on the surface when it comes into contact with even a trace amount of oxygen. Furthermore, when placed in an environment containing moisture such as water or humidity, a hydrated oxide film is formed on the surface.

The higher the temperature of the Eiwa oxide production reaction is, the more the Eiwa oxide film grows, and in a high temperature environment, an Eiwa oxide film such as boehmite or vialite is formed on the aluminum surface. The quality of such a permanent oxide film is much rougher and more porous than that of an aluminum oxide film formed in an environment without moisture, and the pores are also intricately shaped. In addition, the film thickness is also thick.

Incidentally, a hydrated oxide film is formed on the inner surface of an aluminum pipe formed by ordinary extrusion processing due to contact with the atmosphere containing moisture during forming. Furthermore, since this hydrated oxide film is exposed to high temperatures during extrusion, the formation reaction of the hydrated oxide film is promoted, resulting in a thick film. The film quality of this Eiwa oxide film is as described above, and since it is a thick film, a large amount of water is adsorbed to the film. Moreover, since the film lacks tightness, even after molding, vacuum-degrading substances such as moisture, hydrocarbon, carbon dioxide, and carbon monoxide present in the atmosphere are adsorbed to the film. Such substances that lower the degree of vacuum are still present to some extent even during discharge cleaning in the gas or during evacuation, and therefore are adsorbed to the film as described above. Moreover, since the hydrated oxide film is as described above, it is in the form of being occluded within the film.

As a result, it becomes difficult to remove it, and it is difficult to remove it even by vacuuming. Therefore, this is a cause of hindering the improvement of the degree of vacuum in the particle acceleration pipe.

In addition, in order to increase the mechanical strength of aluminum pipes after extrusion, quenching treatments such as water cooling and air cooling are performed after high-temperature heating. As it grows, the vacuum-lowering substances that have already been sucked become incorporated into the film.

Therefore, as a manufacturing method for vacuum extrusion aluminum hollow extrusion moldings that solves the above problems, the aluminum hollow extrusion molding material is manufactured while maintaining the inside of the hollow part of the hollow molding material being extruded in an atmosphere that does not come into contact with moisture. A method was proposed in which an oxide film was formed on the inner surface of the hollow part by extrusion molding.

In this method, methods for maintaining an atmosphere that does not come into contact with the moisture-containing atmosphere include a method of supplying an oxygen-mixed inert gas into the hollow space (Japanese Patent Publication No. 59-19769);
A method of supplying an inert gas containing oxygen as an impurity into the hollow part (Japanese Patent Publication No. 61-37005), a method of vacuuming the inside of the hollow part (Japanese Patent Publication No. 61-37006), a method of supplying dry air or pure oxygen into the hollow part. Method of supplying
-313612).

However, in any of the above methods, the extrusion temperature during extrusion molding is about 500°C, and a part of the oxide crystallizes, so the oxide film formed on the inner surface of the hollow part of the hollow extruded molded material is Part of the amorphous film may become crystallized, and a honey film may not be formed.

Therefore, substances that reduce the degree of vacuum are easily adsorbed and occluded, and the released gas coefficient on the inner surface of the hollow part of the manufactured hollow molded material is 1.
The order is 0""37orr fist p/sac-. This is still not a satisfactory value for a particle acceleration pipe, for example.

An object of the present invention is to solve the above-mentioned problems and provide a method for manufacturing a hollow extruded aluminum profile for vacuum use, which is suitable for applications such as particle acceleration pipes that require the interior to be kept in a vacuum. .

Means for Solving the Problems The method of manufacturing a hollow extruded aluminum profile for vacuum use according to the present invention is to maintain the inside of the hollow part of the hollow profile being extruded in an atmosphere that prevents it from coming into contact with the moisture-containing atmosphere, When extruding the hollow extruded material and forming an oxide film on the inner surface of the hollow part, the extrusion temperature is set at 300 to 450.
It is characterized by extrusion molding at ℃.

In the above, the extrusion temperature was limited to 300 to 450°C because if it is less than 300°C, aluminum cannot be extruded, and if it exceeds 450°C, crystallized oxides will be produced.

The billets used to manufacture extrusion molding materials include JISAIOOO series and JIS A6000, which are used for ordinary extrusion molding.
From the viewpoint of extrudability and mechanical strength, JIS A6061 and JISA6
It is preferable to use an A/-Mg-Si alloy such as 063. Further, it is more preferable to use a billet made of a pure aluminum core material and the A/-Mg-St alloy skin material.

The Jj method maintains the inside of the hollow part of the hollow material being extruded in an atmosphere that does not come into contact with the moisture-containing atmosphere.
Known methods such as those described below can be applied.

First, when extruding aluminum hollow extrusion moldings, a mixed gas consisting of 0.5 to 30 volumes of oxygen, especially 1 to 10% by volume, and the balance of inert gas is used from the beginning.
This method is carried out while feeding the material into the hollow part of the mold H which is being extruded.

In this case, there is a method of sealing the opening at the tip of the mold material after it has been slightly extruded, continuing to supply mixed gas, extruding it for a predetermined length, cutting the mold material, and sealing the cut end. There is a method in which the tip opening is not sealed. In the former case, both sealed ends may be cut and opened after being sent to the place where the hollow stamped material is used after extrusion molding, or may be cut and opened at a stage before being sent.

Argon and helium are commonly used as inert gases.

The second method is to use an inert gas containing oxygen as an impurity instead of the mixed gas in the method of the first method. The purity of the inert gas currently available industrially is approximately 99.99%, and it always contains a small amount of oxygen as an impurity. Also in this method, argon and helium are commonly used as the inert gas.

The third method is to use dry air or pure oxygen instead of the mixed gas in the method of the first method. Dry air can be obtained, for example, by compressing atmospheric air with a compressor and passing it through a dehumidifier containing a desiccant. In this method, any known desiccant can be used, but among them, it is preferable to use synthetic zeolite. Also, the dew point of dry air is -30
The temperature is preferably below 0.degree. C., and desirably below -50.degree. Pure oxygen is oxygen with a purity of 1 0 0 96, which does not contain water.

The fourth method is to create a vacuum in the hollow part of the molded material that is being extruded in the method of No. 1 above. in this case,
There is a method in which nothing is co-supplied into the hollow part during extrusion molding, and a method in which the inside of the hollow part is evacuated. In the latter case, the hollow part of the mold is evacuated at least only at the beginning of extrusion, the opening at the tip of the mold immediately after extrusion is sealed, and after extrusion for a predetermined length, the mold is cut and the cut ends are sealed.

Vacuuming may be performed not only at the beginning of extrusion but also continuously during the extrusion process. In this method, an oxide film is formed by oxygen remaining in the hollow portion.

In any of the above methods, a permanent oxide film is not formed inside the hollow part of the mold, and a honey oxide film with a thickness of about 20 to 30 mm is obtained.

Note that the hollow extruded material obtained by the method of the present invention can be used not only for particle acceleration pipes but also for devices that need to maintain a high vacuum.

Function When the extrusion temperature is within the range of 300 to 450°C, no crystallized oxide is produced during extrusion molding, and the formed oxide film consists only of amorphous oxides.

Example Embodiments of the invention will be described below with reference to the drawings.

FIG. 1 shows an extruder, in which (1
) is the container, (2) is the aluminum billet inside the container (1), (3) and (4) are the dummy blocks and stems that press the billet (2), and (5) is the gas injection port (6) in the center. Boat hole die male type with (
7) is the same female type, (8) is the die holder, (9) (10
) is a gas passage formed in the male mold (5) and die holder (8), (l1) is a mixed gas supply port provided in the die holder (8), (12) is a mixed gas container, A conduit (l3) attached to this is connected to a mixed gas supply port (l1). (l4) is a bolster.

The extruder shown in FIG. 1 extrudes a hollow extruded material (15) (1G) used for a particle acceleration pipe having a cross section as shown in FIGS. 2 and 3. Of course, the dies for molding both are used in shapes that match the molding materials (15) (1(i)) to be molded. Both extrusion molding materials (15) (1
B) are connected alternately to assemble an endless particle acceleration vibe (not shown). In both figures, (
17) (18) is a particle distribution hollow part with an elliptical cross section (same as below when incorporated into a particle acceleration pipe), (19) is an adjacent hollow part for evacuation with a rectangular cross section, (20) is a partition wall between the two hollow parts (17) (Ig), in which communication holes are bored at predetermined intervals. (21) and (22) are particle circulation hollows (17) and cooling water circulation hollows with a small circular cross section provided on one side of (1g); (23), (24) and (25) are particle circulation hollows. (17) Grooves for attaching sheathed wires for heating and degassing treatment provided on one side of each of (1g) and the vacuum hollow section (19).

A specific example of manufacturing the hollow extruded material (15) will be described below.

Example 1 First, a die was washed with caustic, and then a JISA6063 billet (2) was extruded at an extrusion temperature of 350° C. and an extrusion speed of 10 m/1n. No lubricant was used at this time. Simultaneously with the extrusion, a mixed gas (2B) consisting of 7% by volume oxygen and the balance argon is supplied from the mixed gas container (l2) through the conduit (13) and the passage (10) (9) to the jet port (6) at a pressure of 2 to 3 vol.
kg/c and is being extruded (I
5) was supplied into the hollow part.

After being slightly extruded, the opening at the tip of the molded material (15) was pressed and sealed using a press to form one sealed end (27) as shown in FIG.

Thereafter, the mixed gas (2B) was continued to be supplied and after being extruded for a predetermined length, the mold material (l5) was cut with a shear and at the same time the cut end was sealed to form the other sealed end (28) (the fourth (see figure). Thereafter, the mold material (15) with the mixed gas (26) sealed therein was forcedly air cooled to 250° C., then naturally cooled, and then stretched and straightened.

Next, aging treatment is performed at 180°C for 6 hours in that state, and finally both sealed ends (27) (28
) was cut without using oil or air blowing to produce a hollow die-cut material of a predetermined size.

A thin honey oxide film was formed on the inner surface of the extruded material. Then, this was degassed at 150°C for 24 hours, and the degree of vacuum after 20 hours was set to 1F1, and the released gas coefficient was 7X 1 0-"Tor"・l
/s-cd.

Example 2 In addition, a hollow extrusion type mill was manufactured in the same manner as described above except that in the above Example N1, a billet made of JISAIN99 was used instead of the billet (2) of JISA6063, and the aging treatment was not performed. A thin honey oxide film is formed on the inner surface of this extruded material, and when this is degassed at 150°C for 24 hours and the degree of vacuum after 20 hours is determined as ΔPI, the released gas coefficient is 5 × 1 0
-” Torr* //s −c or less.

For comparison, a hollow extrusion mold material was manufactured in the same manner as in Example 1 above, except that the extrusion temperature was 500°C. and,
When this was degassed at 150°C for 24 hours and the degree of vacuum was measured after 20 hours, the released gas coefficient was 2
It was 10-13Torr・ρ/s−c.

Furthermore, for comparison, a hollow extrusion mold material was manufactured in the same manner as in Example 2 above, except that the extrusion temperature was 500°C.

Then, this was degassed at 150°C for 24 hours, and
When the degree of vacuum was measured after the elapse of time, the released gas coefficient was IX103TOrrI+1/s#c.

Effects of the Invention According to the manufacturing method of vacuum aluminum hollow extrusion mold +4 of the present invention, the oxide film formed on the inner surface of the hollow part of the manufactured aluminum hollow extrusion mold material consists only of amorphous oxides. Compared to conventional oxide films mixed with crystallized oxides, adsorption and occlusion of vacuum-lowering substances are significantly less, and even if rock occlusion is present, it can be easily removed by degassing treatment. . Therefore, the amount of vacuum deterioration substances released into the mold material is extremely small.
A high degree of vacuum can be maintained, and the troublesome work required to increase the degree of vacuum, which is conventional, can be omitted or reduced.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention. Fig. 1 is a longitudinal sectional view showing the extrusion process in progress, Fig. 2 is a sectional view taken along the line ■-■ in Fig. 1, and Fig. 3 is a particle acceleration pipe. The second step in making
2 is a sectional view corresponding to FIG. 2 of another mold material used in combination with the mold material shown in the figure, and FIG. 4 is a longitudinal sectional view of the mold material in a mixed gas sealed state. (15) (1G)...Hollow extrusion type shrine. that's all

Claims (1)

[Claims] An aluminum hollow extruded material is extruded while maintaining the inside of the hollow part of the hollow part being extruded in an atmosphere that does not come into contact with the moisture-containing atmosphere, and in order to form an oxide film on the inner surface of the hollow part, the extrusion temperature is set to 300°C. A method for producing a vacuum extrusion aluminum hollow extrusion molding material, which comprises extrusion molding at a temperature of ~450°C.