JP3088272B2 - Ladle for bottom tap type hot water supply of pressure casting machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a ladle of a bottom tap type hot water supply apparatus in pressure casting such as squeeze casting.

[0002]

2. Description of the Related Art Hot water supply using a bottom tap type ladle (L) as a device for supplying a cast metal melt (a molten aluminum alloy or the like) in a pressure casting such as squeeze casting from a molten metal holding furnace to a die (die). Equipment is being developed.
The ladle (L) is, as shown in FIG.
And a cylinder part (2) at the bottom of the cylinder part (2). The lower end opening (23) of the cylinder part (2) is moved up and down by a stopper rod (S) inserted in the ladle (L). Opening / closing is controlled. As shown in FIG. 6A, the ladle (L) is immersed in a molten metal bath (M) of a holding furnace (F) to a predetermined depth (at this time, a valve portion at a lower end is in an open state). After the molten metal (M) is taken in), the valve part is closed with the stopper rod (S), and the molten metal (M) is pulled up above the bath.
Then conveyed to the casting machine of the plunger sleeve, inserting the cylinder portion of the ladle (2) to the plunger sleeve (P _S) inside, pouring molten metal into the sleeve (P _S) by opening the valve. Hot water supply operation of the molten metal holding furnace from (F) to the plunger sleeve (P _S) is repeated carried out about 1-2 minutes as one cycle. As described above, since the hot water supply operation using the ladle (L) is performed by opening and closing the valve at the bottom of the ladle, the molten metal in the holding furnace (F) is pumped without mixing the oxide on the molten metal surface, and the ladle (L) ) from the plunger sleeve (P _S) small drop of the molten metal at the time of hot water in,
It has many advantages for improving and stabilizing the quality of die-cast products, such as minimizing turbulence and air entrainment.

[0003]

Although the bottom tap type ladle is made of cast iron, the ladle has poor erosion resistance to a molten metal such as an aluminum alloy. The molten metal of the ladle (L) contaminates the molten cast metal, and the molten metal leaks easily at the seal portion of the valve at the lower end of the ladle where the opening and closing operations by the stopper rod (S) are repeated. For this reason, the service life is limited to several hundred to 1,000 shots (number of castings). As a countermeasure against erosion, it is effective to replace the ladle with cast iron and use a ceramic sintered product, and the present inventors have realized that by using ceramics, the erosion resistance is several times to ten and several times that of cast iron. We know that we can secure it. However, while ceramics have excellent resistance to erosion and corrosion, they are brittle materials that are susceptible to damage by impact. In actual use, ceramics are located in the boundary area (a) between the bowl (1) and the cylinder (2). Cracks such as cracks and chippings are apt to occur, so that erosion is extremely small, but must be discarded due to the cracks. According to the detailed observations of the present inventors on the actual use of ceramic ladles, the breakage of the ladles was not only caused by mechanical shock (contact / collision with objects, etc.) in the handling process of hot water supply work, but also by short-time cycle. Thermal stress caused by a change in temperature rise and fall accounts for one half of the cause. Therefore, if the occurrence of breakage due to thermal stress can be suppressed and prevented, the useful life of the ceramic ladle can be dramatically increased. The present invention has been made in view of the above, and a bottom tap type ladle that prevents the occurrence of breakage due to thermal stress and enables a dramatic improvement in service life due to outstanding melting resistance of ceramics. To provide.

[0004]

SUMMARY OF THE INVENTION The present invention relates to a bottom tap type hot water supply ladle comprising a bowl portion and a cylinder portion projecting downward from the bottom thereof in a hot water supply device of a pressure casting machine. A bowl member (1
0) and a cylinder member (20) which is a ceramic sintered product connected to the bottom of the bowl member (10).
At the bottom of the bowl member (10), there is provided a hollow cylindrical portion (11) having an inwardly projecting annular projection (11 ₁ ) at the lower end edge, and on the top side of the cylinder member (20), A bulging step (21) is formed by fitting into the hollow cylindrical portion (11) of (10), and the cylinder member (2) is formed.
0) is inserted from the upper side of the bowl member (10) into the hollow cylindrical portion (11) at the bottom, and the bulging step portion (21) of the cylinder member is fitted into the hollow cylindrical portion (11) to form an annular shape. The bowl member (1) is supported by the projection (11 ₁ ).
0).

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS When manufacturing a bottom tap type ladle as a ceramic sintered product, a large-diameter bowl (1)
A large distortion is generated in the boundary region (a) between the cylinder portion (2) and the small-diameter cylinder portion (2). This is because the shrinkage rate in the sintering reaction process is different between the large diameter portion and the small diameter portion, and there is a time lag in solidification of the grain boundary liquid phase between the large diameter portion and the small diameter portion in the cooling process after sintering. It depends. The ladle containing the distortion promotes the generation of cracks in the boundary region (a) due to the superimposition of thermal stress caused by the repetition of the hot water supply operation, so that early destruction due to breakage cannot be avoided as described above. In contrast, the ladle is connected to the bowl member (10) and the cylinder member (20).
The ladder of the present invention, which is a sintered product of members and has an assembly structure in which the two are connected, has an effect of avoiding internal strain resulting from a sintering process as in an integrated product as a dividing effect, and reducing thermal stress in a process of using the actual machine. Excellent breakage resistance and stable use over a long period of time. Also, compared to cast iron ladle,
The excellent heat insulation facilitates the temperature control of the molten metal in the process of supplying the molten metal from the furnace.

FIG. 1 shows a bowl member (10) and a cylinder member (20) constituting a ladle according to the present invention. FIG. 2 shows an assembly of a ladle (L) by connecting both members (10) and (20). The state is shown. The bowl member (10) has a hollow cylindrical portion (11) at the bottom, and an annular projection (11 ₁ ) protruding inward is provided at a lower end edge of the cylindrical portion (11). The cylinder member (20) has a bulging step portion (21) fitted into the hollow cylindrical portion (11) of the bowl member (10).
On the top side. The upper end surface (22) of the bulging step (21) is formed on the inclined surface (12) of the bowl member (10).
And a smoothly continuous slope. The thickness of the sintered product of the bowl member (10) and the cylinder member (20) is, for example, 10 to 15 mm.

The cylinder member (20) is inserted into the hollow cylindrical portion (11) from above the bowl member (10), and a bulging step (21) fits in the hollow cylindrical portion (11). They are combined and carried by the annular projection (11 ₁ ), and the ladle (L) shown in FIG. 2 is formed. The assembled ladle (L)
Like the conventional integrated ladle, a stopper rod (S) is inserted into the inside thereof, and the opening and closing control of the valve by the raising and lowering operation of the stopper rod and the raising and lowering / transporting operation of the ladle allow hot water supply from the molten metal holding furnace to the casting machine. Work is performed.

The bowl member (10) and the cylinder member (2)
The quality of the fitting state of the fitting portion that connects the above (0) is important for smooth execution of hot water supply work and ensuring durability. The clearance at the fitting interface (circumferential interface) between the hollow cylindrical portion (11) of the bowl member (10) and the bulging step (21) of the cylinder member (20) is 0.1 mm or less (one side). The fitting depth (the length of the fitting surface in the vertical direction) is desirably 10 mm or more. Thereby, both members (10) (2)
Troubles such as rattling of the fitting portion of 0) and leakage of hot water from the fitting interface are surely prevented, and stable and long-term repetition of the hot water supply operation is ensured.

The ceramic material of the bowl member (10) and the cylinder member (20) is not particularly limited.
For example, silicon nitride ceramics are preferably used because they have excellent thermal shock resistance against a change in temperature rise and fall in a short cycle, in addition to erosion resistance to various non-ferrous metal melts such as molten aluminum. In the manufacturing process by sintering the two members (10) and (20), no special conditions or restrictions are added. However, as a preferable process, the raw material powder is sealed in rubber and cold isostatic pressing (CIP) is performed. Process), a step of forming a green compact, sintering it, and then performing finishing processing such as grinding and polishing is employed. By forming the green compact into a near net shape in the CIP process, the grinding and polishing after sintering process is minimized (only the fitting portion of both members and the valve seat surface of the cylinder portion (20)). ) Can be finished to a predetermined product.

[0010]

【Example】

[1] Manufacture of ladle A silicon nitride ceramic powder is sealed in rubber, a powder compact is formed by cold isostatic pressing (1200 kgf / cm ² ), and a bowl member is formed by a sintering process (1700 ° C.). Each sintered product of (10) and the cylinder member (20) is obtained. Sintered product (bowl member 10 and cylinder member 2
0) is polished to the fitting portion, and both members (thickness 10)
１４14 mm) and assemble the ladle (for 6 kg Max hot water supply) shown in FIG. The dimensions of the ladle are as follows (see FIG. 4). Bowl member (10): the top opening diameter (phi ₁₀₎ 254 mm, depth (D) 250 mm hollow cylindrical inner diameter (phi ₁₁₎ 75 mm cylinder member (20): Length (l _S) 450 mm diameter (phi ₂₀₎ 55 mm Fitting interface: clearance 0.08mm (one side) Fitting depth (d) 12mm

[2] Actual machine hot water supply operation Using the above-mentioned ladle, hot water supply of molten aluminum alloy is repeatedly performed from the holding furnace to the plunger sleeve of the squeeze casting casting machine. Set temperature of molten metal in holding furnace: 700-730 ° C. Cycle of hot water supply operation: about 90 seconds (Molten bath immersion time: about 20 seconds, transport time to plunger sleeve: about 20 seconds, required time to supply hot water to plunger sleeve: 10 seconds, time required to return to molten metal holding furnace and wait time :
30 seconds).

Table 1 shows the service life of the ladle in the above hot water supply operation. In the same table, the use results (number of shots) of the ceramic-made ladles (test ladles B) and the cast iron ladles (test ladles C) together with the ladles (test ladles A) of the invention examples are shown. Is shown. FIG. 3 shows a temporal change of the temperature of the molten metal pumped into the ladle from the molten metal holding furnace. The horizontal axis in the figure is the elapsed time after the ladle was lifted on the molten metal bath, (A) is the measurement result of the ceramic ladle of the invention, and (C) is the measurement result of the cast iron ladle.

[0013]

[Table 1]

As shown in Table 1, the ladle (A) of the invention has excellent durability that cannot be obtained with the integrated ceramic ladle (B) and the cast iron ladle (C). That is, the cast iron ladle (C) has a rapid progress of erosion, and in particular, the molten metal leaks due to the erosion of the seal portion of the valve, which necessitates early disposal, and the integrated ceramic ladle (B) Although it has a service life much greater than that of cast iron ladles (C) due to its high erosion resistance, it has been found that the erosion of the boundary area (area a in FIG. 5) between the bowl section and the cylinder section has occurred. Discarded with minor losses. On the other hand, the ladle (A) of the invention example has a split structure effect, in which the occurrence of breakage is suppressed and prevented, and the erosion resistance of ceramics is sufficiently utilized, so that the cast iron ladle (C) is, of course, an integrated type. It enables a large number of repetitive uses far exceeding the ceramic ladle (B). Also,
As shown in FIG. 3, the ladle (A) of the present invention effectively suppresses the temperature drop of the molten metal in the process of being transferred from the holding furnace to the casting machine, as a heat insulating effect of the ceramics. Transition process from holding furnace to plunger sleeve (time required about 15-2
The molten metal temperature drop (ΔT) of 0 second) is reduced by about 25 ° C. as compared with the cast iron ladle. This effect of keeping the molten metal heat contributes greatly to the improvement and stabilization of casting quality.

[0015]

The bottom tap type ladle according to the present invention has excellent resistance to erosion against molten metal such as aluminum as a characteristic of ceramics, and has a thermal effect as a structural effect of the two members of a bowl member and a cylinder member. -Having stability against mechanical shock enables stable use over a long period of time, and provides a service life far exceeding that of conventional ladles. As a result, it is possible to reduce the maintenance of the hot water supply apparatus and to improve the efficiency of the casting operation, and also to prevent the contamination of the casting metal and to easily control the temperature of the molten metal.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a constituent member of a ladle according to the present invention.

FIG. 2 is a sectional view showing a ladle according to the present invention.

FIG. 3 is a graph showing a change over time of a molten metal temperature in a ladle in a hot water supply operation.

FIG. 4 is an explanatory diagram of dimensions of a ladle.

FIG. 5 is a sectional view showing a conventional ladle.

FIG. 6 is a diagram showing a hot water supply operation from a molten metal holding furnace to a casting machine by a ladle.

[Explanation of symbols]

L: ladle, S: stopper rod, F: the molten metal holding furnace, M: melt, P _S: plunger sleeve, 1: bowl portion 2: cylinder, 10: bowl member, 11: hollow cylindrical portion, 11 _1: An annular projection, 20: a cylinder member, 21: an enlarged-diameter stepped portion, 23: an opening.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Hide Suzuki 2-3-1-11 Higashishinagawa, Shinagawa-ku, Tokyo UBE Building Ube Industries, Ltd. Tokyo Head Office (56) References JP-A-6-344109 (JP, A) JP-A-6-246419 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B22D 17/30

Claims (2)

(57) [Claims] 1. A bottom tap type hot water supply ladle comprising a bowl portion and a cylinder portion projecting downward from a bottom portion thereof in a hot water supply device of a pressure casting machine, comprising: a bowl member (10) which is a ceramic sintered product; A cylinder member (20), which is a ceramic sintered product, is connected to the bottom of the bowl member (10). An inwardly projecting annular projection (11 ₁ ) is provided at the bottom of the bottom of the bowl member (10). A hollow tubular portion (11) having an edge is provided, and a bulging step () fitted into the hollow tubular portion (11) of the bowl member (10) is provided on the top side of the cylinder member (20). 21) is formed, and the cylinder member (20) is inserted from the upper side of the bowl member (10) into the hollow tubular portion (11) at the bottom, and the bulging step portion (11) is inserted into the hollow tubular portion (11). 21) is fitted into the annular projection (1). 1 ₁ ), the bowl member (1)
A pressure tapping bottom tap type hot water supply ladle characterized by being connected and fixed to 0). 2. A hollow cylindrical portion (1) of a bowl member (10).
The clearance of the fitting interface between 1) and the bulging step (21) of the cylinder member (20) fitted thereto is 0.1 mm.
The bottom tap type hot water supply ladle according to claim 1, wherein the fitting depth is not less than 10 mm (one side).