JPH0347653A - Method for adjusting molten metal surface height in drawing up casting - Google Patents

Abstract

PURPOSE:To form a casting pipe body having almost uniform thickness by descending a cooling mold corresponding to decrease of molten metal accompanying progress of casting of the pipe body to keep the height of molten metal surface constant in drawing-up casting method for forming the pipe body by drawing up solidified layer while cooling and solidifying the molten metal. CONSTITUTION:As the position adjusting method for height of the molten metal surface, lower part of the cooling mold 2 having mold hole 21 vertically penetrated, is dipped into the molten metal 9 and the solidified layer 91 is drawn up while cooling and solidifying the molten metal 9 from lower opening hole of this mold hole 21 to form the pipe body, and by descending the cooling mold 2 corresponding to decrease of the molten metal 9, the molten metal surface in the mold hole 21 can be kept constant. By intermittently descending the mold in synchronous with drawing-up movement and stop of the solidified layer 91, relative standstill time of the solidified layer 91 and cooling mold 2 can be secured. By this method, the casting pipe body having almost uniform thickness can be formed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for adjusting the height of a molten metal in a cooling mold in pull casting.

(Prior art) Conventional pull casting of this type uses a cooling mold (2
) is exposed above the molten metal surface, and the lower part of the mold is exposed to the molten metal (9
), and the molten metal (9) is introduced into the mold hole (21) from the lower opening of the mold hole (21).

A starting rod (8) is inserted into the mold hole (21) from above the cooling mold (2), and the molten metal (9) is attached to the shaft (81) protruding from the lower end of the rod. ) Wait for the outer periphery of the inside to solidify, then pull up the starting rod (8).

When the solidified layer (91) is pulled up to a certain height, the pulling is interrupted and the next solidified layer is formed in the mold cavity.

By repeating the pulling of the coagulated layer intermittently in this way, it is possible to continuously form a tube body in which the cylindrical coagulated layer is connected.

In the above-mentioned pull casting, in order to stably form a solidified layer (91), the mold hole (21) and the molten metal (9) in contact with the mold hole are
It is necessary to ensure a period of time during which the cast tubes are relatively stationary, and for this purpose, the cast tube bodies are pulled up intermittently.

Furthermore, when producing a tube with uniform wall thickness by pull casting, it is important to maintain a constant height of the molten metal relative to the mold hole (21).

The thickness of the solidified layer (91) increases as the time that the molten metal is in contact with the mold cavity (21) increases, that is, the higher the melt level in the mold cavity (21). Further, the shorter the time of contact with the mold hole (21), that is, the lower the melt level in the mold hole (21), the smaller the mold becomes.

As casting progresses, the amount of hot water gradually decreases, so the mold hole (
21) To keep the height of the hot water level constant.

There are the following four methods and their application variations, all of which are carried out in response to the progress of casting.

As shown in Figure 4, the molten metal supply furnace (11) is placed in the molten metal storage furnace (1).
The molten metal (9) is supplied from the molten metal supply furnace (11) to the molten metal storage furnace (1) according to the decrease of the molten metal (9), and the height of the molten metal level in the supply furnace (1) is adjusted. Keep it constant.

East 1 (2) Volume of earth As shown in Figure 5, by fixing the height position of the cooling mold (2) and lowering the molten metal storage furnace (1) according to the decrease in molten metal (9), the storage furnace ( 1) Keep the hot water level constant.

As shown in Figure 6, an auxiliary furnace is installed in communication with the molten metal storage furnace (1), and a refractory lump (13) is suspended from the auxiliary storage furnace (12) so that it can be raised and lowered. By adjusting the amount of immersion into the auxiliary containment furnace (12), the height of the hot water level in the containment furnace (1) is kept constant.

i Habitat volume As shown in Figure 7, a pressurizing chamber (14) is provided in communication with the molten metal storage furnace (1), and the pressure inside the pressurizing chamber is adjusted by the pressurizing pump (15). ) to keep the hot water level constant.

(Problems to be Solved by the Invention) The above four means all have the problem of requiring large-scale equipment.

The present invention provides a cooling mold (2) mold hole (
The purpose of this study is to clarify a method for adjusting the height of the molten metal (9) in pull casting, which can maintain a constant height of the molten metal (9) relative to 21).

(Means for solving the problem) The height position adjustment method of the molten metal surface in pull casting of the present invention is as follows:
The lower part of a cooling mold (2) having a vertically penetrating mold hole (21) is immersed in the molten metal (9), and the molten metal (9) is allowed to enter from the lower opening of the mold hole (21). In the pull-casting method of forming a tube by pulling up the solidified layer (91) while cooling and solidifying the metal, the cooling mold (2) is lowered in response to the decrease in the molten metal (9) as the manufacture of the tube progresses. Cooling mold (2
) to maintain the hot water level at a constant height.

(Functions and Effects) By lowering the cooling mold (2) as the molten metal (9) decreases, the level of the molten metal relative to the mold hole (21) can be maintained constant.

In synchronization with the pulling operation and stop of the molten metal solidification layer (91),
By lowering the mold intermittently, the relative rest time between the solidified layer (91) and the cooling mold (2) can be ensured, and a cast pipe body having a substantially uniform thickness can be formed.

(Example) As shown in FIG. 1, a molten metal storage furnace (1) is provided on a base (3), and a cooling mold (2) is suspended and supported within the furnace.

The frame (4) for hanging the cooling mold (2) is attached to the base (3).
) on top of the cooling mold (2) at four symmetrical positions around the cooling mold (2).
1), and the upper ends of each column are connected by a rectangular frame (42).

A screw shaft (43) is arranged vertically inside each column, and a lifting platform (5) is arranged spanning between each screw shaft (43).

The lifting platform (5) has screw holes (51) at four corners, and the screw shaft (43) is screwed into the screw holes (51).

The four screw shafts (43) are located at the top of the frame (4).
It is connected to one motor (44) via a rotation transmission means (45), and when the motor rotates in the forward direction, the lifting platform (5) rotates all at once in the direction of raising it, and when the motor rotates in the opposite direction, the lifting platform (5) moves up. (5) Rotate all at once in the direction of lowering.

A cooling mold (2) is disposed on the lifting platform (5) via a cylindrical bracket (52), and the lower part of the cooling mold (2) is immersed in the molten metal (9) in the molten metal storage furnace (1). There is.

A control device (not shown) is connected to the motor (44),
In the control device, a motor (44) is operated by a signal generated by a molten metal level detector (6) installed in the molten metal storage furnace (1).

A pulling device (7) for pulling up the cast tube body is provided in the center of the frame (4), and the pulling device is connected to a pair of pinch rollers (71) across the lifting transition path of the cast tube body.
(71) are arranged facing each other, and a drive motor (
An intermittent drive setting device (not shown) is connected to the drive motor (72), and the stop time and operation time can be arbitrarily set to repeat the movement and stop.

The starting rod (8) is inserted into the mold hole (21) from above the cooling mold (2), the molten metal (9) is attached to the lower end of the rod, and the outer periphery inside the mold hole (21) is solidified. Wait for , pull up the starting rod for a certain period of time, and then stop it.

While the lifting of the starting rod (8) is stopped,
There is no change in the level of the molten metal, the mold hole (21) and the molten metal (9) are relatively stationary, and the molten metal (9) moves into the mold hole (21) due to heat removal by the cooling mold (2). Cool and solidify along the line.

After a certain period of time has elapsed, when the starting rod (8) is pulled up for a certain period of time, the solidified layer (91) is pulled up together.

When the solidified layer (91) is pulled up, the level of the molten metal falls depending on its wall thickness and the length of the bow, but the molten metal level detector (6) detects the drop in the molten metal level, and the cooling mold (2) Since the cooling mold (2) is lowered by driving the lowering motor (44), the molten metal level relative to the mold hole (2I) is kept constant.

By repeating the pulling of the coagulated layer (91) intermittently in this way, it is possible to continuously form a tube body in which the cylindrical coagulated layer is connected.

λ Closed Molten Metal Retaining Furnace Inner Diameter 400mm Inner Height 500mm Cooling Mold Outer Dimension 300mm Mold Hole Diameter 60mm Molten Metal Composition (Weight %) Ni Cr CSi Mn Fe35
% 25% 04% 1% 1% Temperature of remaining molten metal (near the molten metal surface) 1450℃ The solidified layer (91) is pulled up and the cooling mold (2 ) was controlled in synchronization with the descending movement of the metal.

FIG. 3 is a concrete chart showing the relationship between the lifting of the solidified layer (91) and the lowering of the cooling mold (2) in the above-mentioned example.

The pulling up of the coagulated layer (91) is 0.0 for the first 0.3 seconds.
The lifting is carried out at an accelerated speed of 6 m/s 2 , and the lifting is continued at the maximum speed for the next 0.4 seconds, and then the lifting is abruptly stopped, and the lifting is stopped for 0.3 seconds.

The rate of pull-up of the solidified layer (91) is much greater than the rate of descent of the mold.

By repeating the above operation for 0.15 hours, a tubular body having an outer diameter of 60 mm, a wall thickness of 8 mm, and a length of 5300 mm and having a substantially uniform thickness was cast.

In carrying out the present invention, the descending operation of the molten metal storage furnace (1) is determined based on experiments and calculations in advance to determine the time required for the molten metal (9) to solidify to the required thickness within the mold cavity (21); The relationship between the amount of descent of the cooling mold (2) and the amount of rise of the molten metal level can be grasped, and from these values, the lowering of the cooling mold (2) and the lifting drive of the casting tube can be automatically controlled.

Furthermore, we visually detect the decrease in the molten metal level due to the progress of casting,
The motor (44) driving the cooling mold (2) can be activated as needed to lower the cooling mold (2).

The present invention is not limited to the configuration of the above embodiments, and various modifications can be made within the scope of the claims.

[Brief explanation of drawings]

Figure 1 is a perspective view of the pulling casting device used in the present invention, Figure 2 is a sectional view of the same device, Figure 3 is a chart of the speed and timing of pulling up the solidified layer and lowering the cooling mold, and Figure 4.
FIG. 5, FIG. 6, FIG. 7, and FIG. 8 are explanatory diagrams of conventional examples. (1)... Molten metal storage furnace (2)... Cooling mold (3
)...Base (4)...Frame (5)
... Lifting platform (9) ... Molten metal 319-

Claims (1)

[Claims] [1] A cooling mold (
2) Immerse the lower part of the mold in the molten metal (9) in the molten metal storage furnace (1), let the molten metal (9) enter through the lower opening of the mold hole (21), and solidify while cooling and solidifying the molten metal (9). In the pull-casting method of forming a tube by pulling up the layer (91), the cooling mold (
2) A method of adjusting the height of the molten metal in pull casting, in which the molten metal level in the mold hole of the cooling mold (2) is maintained at a constant height by lowering the mold.