JPH0355221B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for casting metal rods such as welding rods, and a casting apparatus for carrying out the method.

[Technical background of the invention]

Recently, various cobalt-based alloys, nickel-based alloys, and tungsten carbide-based alloys have been developed as surface hardening alloys, and welding rods for hardfacing made of these alloys, such as Stellite, which has cobalt, chromium, and tungsten attached, are available. Welding rods such as welding rods and colmonoids cannot be manufactured or are difficult to manufacture by the wire drawing or cutting processes used for general welding rods. For this reason, welding rods made of these alloys are generally manufactured by casting, in part to reduce the number of processing steps.

[Problems with background technology]

However, generally the dimensions of welding rods are between 2mm and 10mm.
Requires diameter of mm and length of 180mm to 400mm. For this reason, in conventional casting using a sand mold, a predetermined length cannot be secured due to insufficient hot water circulation due to a drop in temperature, or air is drawn in during casting, resulting in the formation of cavities. Furthermore, when conventional casting is used, the surface roughness is as rough as 80 to 100S, and the hardness is high and it requires a large number of man-hours to smooth the surface.

[Purpose of the invention]

The present invention has been made to improve the above-mentioned problems, and its purpose is to prevent insufficient hot water flow when casting bar-shaped metals made of alloys with low rollability and low machinability, such as stellite alloys. To provide a casting method and a casting apparatus which can obtain a product with a smooth surface without causing any air to be drawn in during casting.

[Summary of the invention] In order to achieve the above object, the casting method according to the present invention includes:
The molten metal suction port of a pipe-shaped mold with a molten metal suction port at the lower end is immersed in the molten metal, the pressure inside the mold is reduced, the molten metal is sucked into the mold, and the upper part of the molten metal that has risen is rapidly cooled to stop the molten metal from rising. The gist is that the casting device according to the present invention connects the upper end of the pipe-shaped mold to a vacuum suction device, forms a molten metal suction port at the lower end, and further connects the inner surface of the mold to the inside of the mold. The gist of this is that the chiller was placed with a gap between the two.

[Embodiments of the invention]

An example of the implementation of the present invention will be explained in detail below based on the accompanying drawings.

FIG. 1 is a sectional view of a casting apparatus according to the present invention, and in the figure, 1 is a quartz tube that becomes a mold.
The lower end of the is a molten metal suction port 2, and this suction port 2 is connected to a cap 3 made of a low melting point metal such as aluminum.
A narrowed portion 4 is formed slightly above the suction port 2. The upper end of the quartz tube 1 is fitted into and fixed to a fastening part 6 of a vacuum suction jig 5 via a silicone rubber 7. Further, the vacuum suction jig 5 has a space 8 formed therein,
This space 8 and the inside of the quartz tube 1 are communicated through a pipe 10 having a horizontal hole 9 formed therein, and a chiller 11 is screwed to the lower end of this pipe 10. The diameter of the chiller 11 is made slightly smaller than the inner diameter of the quartz tube 1 so as to form a gap 12 between the quartz tube 1 and the quartz tube 1.

Further, a hole 13 communicating with the outside is formed in the vacuum suction jig 5, a hose attachment portion 14 is fixed to the hole 13, and a pipe 16 of a vacuum suction device 15 is attached to the hose attachment portion 14. .

Here, for example, to show an example of the dimensions of the main components mentioned above when casting a welding rod with a diameter of 8 mm and a length of 400 mm, the quartz tube 1 has an inner diameter of 8 mm and a length of 460 mm.
mm, and the inner diameter of the narrowed part 4 is 6 mm.
~4 mm, and the distance from the bottom end is approximately 15 mm to 25 mm, and the diameter of the chiller 11 is approximately 6 mm, and the length is approximately 10 mm.
20 mm, and the gap between the cold metal 11 and the inner surface of the quartz tube 1 is 1 mm or less. In the figure, the shape of the narrowed portion 4 is a constricted tube, but another tube may be arranged inside.

A casting method using the casting apparatus configured as described above will be described below.

First, a molten stellite alloy 18 maintained at 1530 to 1550°C is prepared in a melting furnace 17. Then, the vacuum suction device 15 is activated to reduce the pressure inside the quartz tube 1 to 10 ^-1 to 10 ^-3 torr in 5 to 10 seconds. Next, in this state, the quartz tube 1 is immersed into the molten metal 18 from the surface of the molten metal 18 which has been cleaned up to the bottom of the narrowed portion 4. Then, the cap 3 that was blocking the molten metal suction port 2 is instantly burned away by the heat of the molten metal 18, and the molten metal 18 rises to the top of the quartz tube 1 in 0.1 to 0.2 seconds. The molten metal 18 that has reached the chilled metal 11 is the second
As shown in the figure, the molten metal 18 is rapidly cooled and solidified by the chiller 11, and the rising of the molten metal 18 is stopped. After a predetermined period of time has elapsed, the quartz tube 1 is pulled out of the molten metal 18. In this case, since the molten metal 18 is solidified in the narrowed portion 4, the molten metal 18 in the quartz tube 1 will not flow out.
After this, the solidified welding rod is taken out from the quartz tube.

FIG. 3 is a cross-sectional view of another embodiment, and FIG. 4 is a cross-sectional view of a joint. In this embodiment, ten quartz tubes 1 are bundled to form an equilateral triangular shape that can be in a close-packed state. , the upper ends of these quartz tubes 1...1 are fixed to one vacuum suction jig 5 via silicone rubber 7,
Its outer periphery is held by a fastener 20 lined with asbestos cloth 19.

Therefore, in the case of this other embodiment as well, by operating the vacuum pump etc., the inside of the quartz tube 1...1 is
The pressure is reduced through 0...10. Then, by immersing the molten metal suction ports of the quartz tubes 1...1 into the molten metal while maintaining the reduced pressure, the molten metal rises into the quartz tube 1, and the rising end is rapidly cooled by the chiller 11 to stop the rise of the molten metal 18. Then, pull out the quartz tube 1...1 from the molten metal,
After solidifying, take out the product.

〔Effect of the invention〕

As described above, according to the present invention, the molten metal is drawn directly and rapidly into the mold from the furnace, so there is almost no temperature drop during the process, and welding rods of sufficient length can be cast. be able to. Further, since vacuum suction is performed, air is not drawn in, and a welding rod without oxidation or formation of blowholes can be obtained.

In addition, by using a quartz tube as a mold, it is possible to obtain a product with a smooth surface, eliminating the need for post-processing.Furthermore, by attaching an aluminum cap, etc. to the molten metal suction port, the molten metal can be melted after sufficiently reducing the pressure. This means that water can be suctioned, and therefore the water flow can be improved.

Furthermore, since the chiller that rapidly cools the rising molten metal is screwed onto the pipe, etc., even if the chiller comes into contact with the molten metal and deteriorates, it can be easily replaced, and many other effects are achieved.

[Brief explanation of drawings]

Fig. 1 is a longitudinal cross-sectional view of a casting apparatus according to the present invention, Fig. 2 is a cross-sectional view of a quartz tube showing a state in which molten metal has risen, Fig. 3 is a cross-sectional view of another embodiment, and Fig. 4 is the same. FIG. 3 is a longitudinal cross-sectional view of the embodiment. DESCRIPTION OF SYMBOLS 1... Mold, 2... Molten metal suction port, 3... Cap, 4... Constricted part, 11... Chilled metal, 15... Vacuum suction device, 18... Molten metal.

Claims (1)

[Claims] 1. The inside of the pipe-shaped mold is depressurized by suction, and the molten metal suction port at the lower end of the mold is immersed in the molten metal, the molten metal is sucked up into the mold, and the upper part of the rising molten metal is cooled to cause the molten metal to rise. A method for casting bar-shaped metal, characterized by stopping the process. 2. A pipe-shaped mold whose upper end is connected to a direct air suction device and whose lower end is a molten metal suction port, and a cooling metal disposed within this pipe-shaped mold so as to form a gap with the inner surface of the mold. A casting device for rod-shaped metal consisting of. 3. The rod-shaped metal casting apparatus according to claim 2, wherein a narrowed portion is formed at a lower portion of the pipe-shaped mold. 4. The rod-shaped metal casting apparatus according to claim 2, wherein a cap made of a low-melting point material is attached to a molten metal suction port formed at the lower end of the pipe-shaped mold.