JPS63157739A - Apparatus for producing hollow metal ingot having high melting point - Google Patents

Abstract

PURPOSE:To easily obtain a hollow metal ingot metal ingot having high melting point under high yield and low cost by melting the metal having high melting point by energy beam under high vacuum pouring into annular casting and drawing while vibrating the mold and rotating the ingot. CONSTITUTION:Under high vacuum, the metallic raw material having high melting point, such as Ti, etc., is supplied into the watercooling copper hearth 4 from a hopper 3 through a guide 3 and gladually melted by applying electron beam from an electron beam gun 1. The molten metal obtd. in this way, is overflowed, and poured into the annular casting space formed by a water-cooled copper mold 5 and a water-cooled copper core 6. Further, the molten metal pool in the above space is periodically applied by the electron beam from the electron beam gun 1, to prevent rapid solidification and hold the molten metal pool. While vibrating the above mold 5 and the core 6, the hollow ingot 7 formed by cooling and solidifying, is drawn downward, while rotating as centering an axis by drawing device 8.

Description

[Detailed Description of the Invention] <Object of the Invention> Industrial Field of Application The present invention relates to an apparatus for manufacturing hollow ingots of refractory metals, and more specifically, it is capable of manufacturing pipes of refractory metals and superalloys. This relates to a manufacturing device for hollow ingots of high melting point metal.

Conventional technology The processability of high-melting point metals and superalloys is generally poor and is largely affected by purity. For this reason, in addition to devising the pipe manufacturing process, many attempts have been made to improve purity in order to maintain and improve workability. To give a specific example, 1) Ti: After manufacturing a thin plate by the usual method, forming T
rG welding or hot extrusion of round ingots 2) 2r: Hot extrusion after drilling the center of a round slab 3) MOLW: Hot extrusion after sintering and forging the powder 4) N
b, ■a: Hot extrusion of round slab 5) Superalloy: Same
In other words, when starting materials with a round cross section are used, it is difficult to manufacture raw pipes using a punching machine such as a mandrel mill, which is generally used to manufacture ordinary steel seamless pipes! It's self-evident that it's a mouthful. Furthermore, in order to improve the purity of the material, arc melting or electron beam melting is performed under vacuum, but in particular, with Ti and Zr, it is virtually impossible to expect any improvement in purity. It is even feared that contamination of the material may occur as the processing temperature increases. Therefore, the weight ratio of the pipe product to the material, that is, the product stagnation, is quite low, but this is mainly due to poor workability and contamination such as oxidation due to increased processing temperature.

Due to this current situation, there is a strong desire for a radical method of manufacturing pipes, that is, a manufacturing method that involves high manufacturing volume, low manufacturing costs, and a simple manufacturing process, especially for high-melting point metals and superalloys.

Regarding the manufacturing method of steel pipes, there are methods using a core supplied with a lubricant (Japanese Patent Application Laid-Open No. 56-141944) or a core whose surface is coated with a fireproofing agent (Japanese Patent Application Laid-open No. 134048-1982), but none of them However, the method for heating the molten metal that has flowed into the mold is not clearly disclosed, and it cannot be applied to the high melting point metal that the present invention is intended to disclose.

Problems to be Solved by the Invention The present invention aims to solve these problems.Specifically, the present invention aims to solve these problems. The purpose of the present invention is to provide a hollow ingot manufacturing device.

<Structure of the Invention> Means for Solving the Problems and Their Effects The present invention provides an apparatus for successively melting a high melting point metal using an energy beam under a high vacuum, and a water-cooled mold and a core that overflow from the melting apparatus. an energy beam drive device that periodically irradiates the molten pool of the metal formed in the annular space formed between the two, a device that vibrates the water-cooled mold and the core, and a hollow ingot of the metal centered on the axis. It consists of a device that rotates it and pulls it out downward at the same time.

Hereinafter, the structure and operation of the means of the present invention will be explained with reference to the drawings.

FIG. 1 is an explanatory diagram showing a hollow ingot manufacturing apparatus according to the present invention used in Examples, and FIG. 2 shows an example of electron beam scanning that scans the concentric bottom surface of molten metal in a mold. It is an explanatory diagram.

As a result of studying the manufacture of pipes whose main components are high-melting-point metals and superalloys, the inventors found that the drilling process is a difficult point, and that in order to avoid the drilling process, it is necessary to We came to the conclusion that it is preferable to manufacture a hollow material with a shape suitable for processing to adjust the wall thickness and diameter of the pipe in the process, and in order to realize this, we melted the metal and alloy, designed the VI manufacturing equipment, The present invention was achieved as a result of manufacturing, melting, and casting tests.

In other words, granular or rod-shaped raw metal is melted with an electron beam in a water-cooled copper hearth, and the overflowing molten metal is guided into the annular space between the water-cooled copper mold and the inner water-cooled copper core to form a hollow casting. This device is characterized by rotating the piece around an axis and simultaneously pulling it downward.

At this time, the electron beam heats the raw metal, while heating the molten metal held in the water-cooled copper hearth as well as the molten pool of the molten metal that forms a hollow cross-sectional shape between the water-cooled copper mold and the core. Designed to be controlled. In addition,
Particular care must be taken to control the diameter and position of the electron beam that heats the molten pool of molten metal that has a hollow cross-sectional shape. In other words, the diameter of the electron beam! If f is too large or the displacement control is unstable, a part of the electron beam will heat the water-cooled copper mold or water-cooled copper core, which will not only reduce heating efficiency but also cause impact heating of the copper. There is a risk of burnout.

Therefore, the thickness of the hollow ingot needs to be sufficiently larger than the diameter of the electron beam. In addition, the amount of heat released from molten metal through the solidified metal shell increases the area compared to a round billet without a hollow part, so it is important to take this into consideration when determining the cross-sectional shape of the hollow ingot. Furthermore, if the deepest part of the molten pool is deeper than the bottom end of the water-cooled copper mold, the static pressure of the molten pool will apply pressure to the solidified shell, leading to deformation and cracking of the solidified shell, and furthermore, the risk of breakage 1~ occurring. There is. Therefore, it is necessary to determine the length of the water-cooled copper mold from this point of view, and to set the maximum depth of the molten pool above the lowest end of the mold.

Example Hereinafter, this will be explained in detail with reference to Examples.

Ti and ZR pipes were manufactured using an electron beam furnace with a maximum output of 240 W as shown in FIG.

The water-cooled copper mold 5 has an outer diameter of 300 mm and an inner diameter of 200 m.
m and the upper and lower tapers are 1% (2.5mm/250m+n
), a vertical water channel (slit) was formed inside the mold at a 20 mm thick copper wall, and water cooling was performed at a flow rate of 10 n/sec.

On the other hand, the water-cooled copper core G has an outer diameter of 120 mm and a length of 2
00mm, and a vertical waterway (slit) was similarly formed at the copper wall thickness of 15ml on the outside of the core, and the flow rate was 8.
Water-cooled at m/' S e C. The direction in which the cooling water is supplied is all upward.

Both Ti and lr raw materials are 20 to 50% sponge.
A hollow ingot having a diameter of mmφ was supplied at a rate of 1.8 kg/min, and a hollow ingot was handled from the bottom at a rate of 2 cm/m1na'. In both cases, the Ti and 2r sponges were placed in a horizontal water-cooled copper hearth 4 (effective dimension 150 mm).
Hopper 2 at the end of Wx50mm [lx350mmL]
The hearth is supplied from
The 30 mm D x 20 mm lj overflows at a superheating degree of 80 to 200° C. and drips into the space between the mold and the core for producing hollow ingots.

In this case, the metal that has flowed in solidifies relatively quickly, so the hollow ingot is rotated at 1.5 ppm to equalize the supply amount in the circumferential direction, and the clamping force between the core and solidified shell is used to stabilize the core. Prevent sticking.

In addition, the concentric molten metal that forms the hollow ingot is heated to a degree of superheating of 80 to 80° by an electron beam (an example is shown in Figure 2) that is deflected and orbited within a range that does not illuminate the mold. It is heated to 300° C. to prevent solidification of incoming metal droplets, and care is taken to ensure that the depth of the concentric molten pool is constant and there is no deviation in the circumferential direction. The degree of superheating of the molten pool is set to an appropriate value based on the surface quality of the hollow ingot and the depth of the molten pool.

Two electron guns were used to melt the raw materials and maintain the molten pool as described above, and the accelerating voltage was 30V and the current was 3.1V.
~4.28, the diameter of the electron beam is 20 mm, and the energy density is 10' W/C12. This electron beam is applied to the melting part of the Ti sponge by 70% of the output of one electron gun.
Scanning is performed to provide a time rate distribution of 30 to 6 for heating the molten pool in the water-cooled copper hearth. In addition, the output of the other electron gun was scanned so that 30% of the time was distributed to the melt outlet from the water-cooled copper hearth, and 70% was distributed to the heat retention of the concentric molten pool. In this case, the temperature of the Ti melt flowing into the water-cooled copper hearth was 1820°C, and the maximum value of the surface temperature of the concentric molten pool was 1835°C. In addition, the vacuum eater is 2
X10-4Torr, 8x10-3T in stationary phase after start
It was orr. In the case of 2r, the sponge feeding speed is 2.
A hollow ingot was produced at a drawing speed of 2 kBmin and a drawing speed flu of 1.7 cm/min. In this case, the temperature of the Zr melt flowing from the water-cooled copper hearth was 1950°C, and the temperature at the surface of the molten pool in the hollow ingot was 1970°C.

The length of the hollow ingot was set to 1.0 m, but in reality, the length of the hollow ingot was 32 m at the fitting part with the center fitting at the bottom of the ingot.
For the top part, the output of the electron beam was gradually reduced to prevent the formation of shrinkage holes, but since this shrinkage was 25 mm, in the case of Ti, the thickness was 925 mm, the outer diameter was 195 mm, and the inner diameter was 1 mm.
For 18mm Zr: Goodness 9351T1m, outer diameter 19G
IIIIIIl, inner radius was 118mm.

In addition, although the unevenness on the surface of the hollow ingot cannot be ignored, the unevenness on the outer diameter side is at most 1. In the case of Lnm and Zr, the maximum is 0.9 mm, and on the inner diameter side, the maximum is 0.9 mm in the case of Ti.
7 mm, in the case of -Zr, it was within the maximum range of 0.7 mm, and there was no problem in cold rolling of the hollow ingot in the next step.

In addition, the frequency for the water-cooled copper mold and core is 4500Hz.
When subjected to vibration with a maximum width of 0.03 mm, the above-mentioned unevenness was 0.7 mm on the outer diameter side and 0.4 m on the inner diameter side in the case of Ti.
It was found that in the case of m and lr, there is a significant decrease at 0.5 mm on the outer diameter side and 4 mm on the inner diameter side.

<Effects of the Invention> As explained above, the present invention provides a device for sequentially melting a high-melting point metal using an energy beam under a high vacuum, and a device that overflows from the melting device and is formed between a water-cooled mold and a core. The molten pool of the metal formed in the annular space is l! 1
11 A driving position for the energy beam that irradiates the object, a device that vibrates the water-cooled mold and the core, and the hollow space of the metal! 77 A device for producing a hollow ingot of a refractory metal, which is characterized by comprising a device that rotates an ingot around an axis and simultaneously pulls the ingot downward. Discloses a pipe manufacturing device,
The effect is significant in simplifying the current process and reducing the required capital investment.

In other words, the elimination of the need for drilling equipment and hot extrusion equipment, especially the latter, which requires enormous equipment costs, is considered to be particularly noteworthy in that it significantly contributes to reducing pipe manufacturing costs.

It goes without saying that the present invention can be easily developed to extend the length of hollow ingots and to continuously produce hollow ingots.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing a hollow ingot manufacturing apparatus according to the present invention used in Examples, and FIG. 2 is an explanatory diagram showing an example of electron beam scanning that scans the concentric molten metal surface in a mold. be. Code 1...Electron beam gun 1'...Electron beam gun 2...Hopper 3...Guide 4...Water-cooled copper hearth 5. ... Water-cooled copper mold 6 ... Water-cooled copper core 7 ... Hollow ingot 8 ... Handling device Fig. 1 Fig. 2

Claims (1)

[Claims] A device for sequentially melting a high-melting point metal using an energy beam under a high vacuum, and a molten pool of the metal overflowing from the melting device and formed in an annular space formed between a water-cooled mold and a core periodically. A device for driving an energy beam to irradiate the metal, a device for vibrating the water-cooled mold and the core, and a device for rotating the metal hollow ingot around an axis and pulling it downward at the same time. Equipment for manufacturing hollow ingots of melting point metal.