JPS5851781B2 - Enshinchi Yuzou Niokeru Youto Noikomihouhou Oyobi Souchi - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for casting molten metal in centrifugal casting.

Conventionally, as shown in FIG. 3, a casting machine 7 is disposed facing the casting opening of a rotary mold 1, and the molten metal 5 in a ladle 8 is injected into the casting machine 7 from a nozzle 71 of the casting machine 7 into the rotary mold 1. What is cast is put into practical use.

Since such a centrifugal casting apparatus injects the molten metal into the mold 1 from the end thereof, it takes time for the molten metal to move the entire length of the mold 1, and the temperature drop due to the flow of the molten metal and the casting machine 7. Therefore, centrifugal casting of long tubes was difficult.

In addition, with this method, the molten metal always falls at the same position in the mold, which not only tends to cause unevenness in the quality of the casting tube itself, but also, in extreme cases, causes a decline in the casting quality of this part. .

Furthermore, in the above-mentioned centrifugal casting, the surface properties of the mold always had to be strictly controlled because the inner surface inside the mold, the so-called roughness of the mold surface, affected the flow of the molten metal.

In addition to the above-mentioned apparatus, a centrifugal casting apparatus has been put into practical use, as shown in FIG. 4, in which a mobile casting machine 9 is installed on the casting side of the rotary mold 1. By doing this, it is possible to change the casting position at the tip of the gutter 9, and it is possible to cast long tubes of this size.
must be made long according to the axial length of the mold 1, and there is also a limit to the axial length of the mold 1, considering the drop in temperature of the hot water in the soil.

Moreover, the casting machine 9 of such an apparatus not only has a complicated structure in order to prevent the temperature of the hot water from dropping, but also needs to be cleaned after every casting to prevent molten metal and slag from adhering to the groove walls of the casting machine 9. This was a cause of lowering the efficiency of the casting operation.

In addition, even if the casting machine is moved to a constant speed, the amount of molten metal poured per hour does not remain constant, and it is difficult to adjust this.
There were many problems.

The present invention solves the conventional problems by changing the pressure in the pot and ejecting the molten metal from a nozzle into the rotary mold to control the falling position of the molten metal. The present invention provides a method and apparatus for pouring molten metal in centrifugal casting, which makes it possible to control the amount of molten metal poured and achieve the casting of high-quality long tubes.

The present invention will be specifically described below based on embodiments shown in the drawings.

In FIG. 1, a rotary mold 1 of a centrifugal casting apparatus has a cylindrical shape with a desired length and diameter depending on the pipe to be cast, and is freely rotatable at both ends by rollers 12 and 13 of a machine base 11, respectively. By supporting each roller with a rotary drive device (not shown), the mold 1 is axially rotated in a horizontal state. An annular band 15.15 protruding from the inner wall 14 at a distance corresponding to the length of the pipe wall and corresponding to the thickness of the tube wall is removably inserted and fixed between both bands 15.15 and the inner wall 14 between the bands. A mold portion 16 is formed, and a molten metal casting device 2 according to the present invention is disposed in front of the casting opening of the rotary mold 1 so as to face each other.

The casting device 2 fills high-pressure air into the casting steel 21 to increase the internal pressure and discharges the molten metal.A casting nozzle 2 is installed at the bottom of the casting steel 21 facing the casting opening of the mold 1.
2 is opened, and the upper opening of the pot 21 has a lid 23 that can be opened and closed.
A high pressure device 3 for increasing the internal pressure of the cast steel 21 is attached to the lid 23.
Connect.

In the high pressure device 3, the lid 23 is connected to a ventilation pipe 31, and the pipe 31 is connected to the high pressure source 3 through a pressure regulating valve 32 and an on-off valve 33.
4.

The casting nozzle 22 is equipped with an adjusting means 4 for adjusting and opening/closing the opening of the nozzle 22.
A guide frame 41 is provided on the side wall 24 of the opening, and an opening/closing plate 42 is slidably attached thereto, and an adjustment hole 43 that matches the opening of the nozzle 22 is opened in this opening/closing plate 42.
is connected to the operating mechanism 44 and slid, and the adjustment hole 43 is brought into matching communication with the nozzle 22 or shifted in position to adjust the size of the communication opening and open.

The cast steel 21 is placed on a support stand 25 that can be raised and lowered, and the height of the casting nozzle 22 can be adjusted from upper to lower while controlling the speed using a lifting device, or the discharge direction of the nozzle 22 can be moved up and down. None.

The falling position of the molten metal discharged from the nozzle can be varied over the entire length of the mold 1, or the cast steel 21 can be supported on a weighing device to detect the weight of the molten metal, and the amount of molten metal in the pot can be increased or decreased. In addition to adjusting the pressure within the cast steel 21, the above method can also be added, such as adjusting the falling position of the molten metal discharged from the nozzle.

After pouring a predetermined amount of molten metal 5 into the cast steel 21 according to the pipe to be cast, and keeping the upper opening of the pot 21 hermetically sealed with the lid 23, the high pressure device 3 is activated to reduce the internal pressure in the cast steel 21. Increase to desired pressure.

Next, when the mold 1 is rotated at high speed by the rotary drive device and the opening/closing plate 42 of the casting nozzle 22 is opened and released according to the casting speed, the molten metal 5 is ejected from the nozzle 22 under the pressure in the pot 21. and falls into the mold part 16 of the opposing rotary mold 1,
It is laminated on the inner circumferential surface of the mold part 16 surrounding the falling position by receiving the rotational centrifugal force of the mold 1 at the same time as it falls, and the pressure of the casting steel 21 is adjusted from the start of casting to a small value according to the elapse of casting time. As a result, the falling position of the molten metal can be shifted over the entire length of the mold 1, and the molten metal can be poured.

For example, when casting a long tube with a uniform thickness over the entire length of the tube wall, the pressure in the casting steel 21 is set high at the beginning of casting, and gradually lowered as the casting time progresses. Since the position of the molten metal falling into the pipe changes at a constant speed over time, a long pipe with uniform wall thickness can be formed. When casting a long tube with a thick wall 6, correspond to the location where the thick wall is to be formed.

By stopping the pressure drop in the cast steel 21 for a short time, the required amount of molten metal is poured into the thick interior, and the amount of molten metal is increased or decreased depending on the wall thickness.

The casting speed is adjusted by operating the opening/closing plate 42 to set the opening of the casting nozzle 22 to be large or small, and the opening/closing plate 42 is adjusted manually or automatically by the operating mechanism 44.

As described above, the present invention disposes the casting nozzle 22 facing the casting opening of the rotary mold 1, releases the molten metal 5 in the cast steel 21 from the nozzle 22 into the rotary mold 1, and reduces the pressure inside the cast steel 21. Since the molten metal is poured while controlling the falling position of the molten metal, the molten metal discharged from the nozzle 22 comes into contact with air between the nozzle 22 and the falling position of the mold part 16, but this only occurs for a very short time. Therefore, there is no large temperature change unlike when using the conventional casting troughs 7 and 9, and therefore the molten metal maintains approximately the set casting temperature regardless of the distance from the nozzle 22 where it falls, improving casting quality and preventing it from being ejected from the nozzle. This enables centrifugal casting of long tubes that correspond to the maximum flying distance of molten metal.

Further, the casting nozzle 22 is provided with an adjusting means 4 to adjust the nozzle 22.
Since the opening and closing of the nozzle and the nozzle opening can be adjusted to large or small,
The amount of molten metal poured and the pouring speed can be accurately set and adjusted.

Furthermore, unlike conventional devices, casting troughs are not used.
This not only saves the trouble of cleaning the casting gutter, but also because there is no heat absorption by the gutter, the molten metal can be poured at the set pouring temperature, which is effective in improving the quality of centrifugally cast castings.

Furthermore, since the present invention releases the molten metal from the nozzle and controls its falling position, the molten metal falling position changes over the entire surface of the mold part of the rotary mold, so the mold is not damaged and the quality of the casting is further improved. It has excellent effects.

[Brief explanation of the drawing]

FIG. 1 is an overall sectional view showing the implementation situation, FIG. 2 is a partial sectional view of a mold part in the embodiment, and FIGS. 3 and 4 are sectional views of a conventional device. 1... Rotary mold % 11... Machine stand, 2... Casting device, 22... Casting nozzle, 23... Lid, 4...
・Adjustment means.

Claims (1)

[Claims] 1. While applying pressure to the molten metal in the casting pot, the casting nozzle is opened to release the molten metal into the rotary mold, and the pressure in the pot is adjusted to control the falling position of the molten metal. A method for pouring molten metal in centrifugal casting, which is characterized by pouring the molten metal. 2. A rotary mold 1 rotatably supported on a machine base 11 and connected to a rotary drive device, and a lid 23 disposed opposite to the front of a casting opening of the mold 1, having a casting nozzle 22, and an openable/closable lid 23 at the top. and a pressure regulating valve 3 in the casting amount 2.
2 and the casting nozzle 2.
2 and an adjusting means 4 for adjusting opening and closing.