JPS5852459B2 - Manufacturing method for both tsuba pipes - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a double-flange pipe using a centrifugal force casting method, and more specifically, a manufacturing method that can prevent neck breakage accidents at the flange portion of a double-flange pipe. Regarding.

When obtaining a double-flange pipe using a centrifugal casting mold, one of the problems that must be solved is neck breakage at the flange portion.

Conventionally, in order to prevent such neck breakage, a core mold with an inner diameter approximately the same as the outer diameter of the pipe to be cast was set in the centrifugal casting mold, and mixed molding sand was poured into both molds. The sand is introduced into the cavity of the mold, compacted with sand using an air rammer, etc., and molded, and the cushioning effect of the sand is used to prevent neck breakage, and the double-flanked pipe is cast.

However, with this conventional method, the number of man-hours for kneading molding sand and molding increases, and the cooling rate during casting is lower (slower) than in mold casting, making it difficult to obtain a high-density cast product.

The present invention was made in view of the above-mentioned problems, and its purpose is to effectively prevent neck breakage without using a sand mold, and to improve the cooling rate using the mold.
The purpose is to provide a method for casting double-flanked pipes that yields high-density cast products. A core mold with a built-in slit mold is installed inside, and the slit mold is also divided in the circumferential direction and is provided with a mold that can freely move forward and backward toward the center using a heat sensor on the core mold side. A target molten metal is poured into the mold, and when the molten metal solidifies and shrinks, it is pulled up from the center of the slit mold to prevent the flange from breaking.

The present invention will be described in detail below with reference to the illustrated embodiments. FIG. 1 shows a mold embodiment used in the present invention, and FIG.
-A sectional view, 1 is a centrifugal casting mold,
Needless to say, it is rotatably supported on the casting machine, and 2 is a split core mold according to the present invention, and this split core mold 2 is, as is clear from FIG. It has a divided structure divided into three parts in the circumferential direction (radial direction), and a slit mold 3 made of an annular cylindrical mold is inserted approximately at the center of the mold body, and these divided core molds 2 and the slit mold 3 form a core mold.

Like the split core mold 2, this slit mold 3 is arranged in the circumferential direction (
The slit mold 3 is divided into three parts in the radial direction), and a slit relief part 5 formed by a tapered circumferential groove is formed on the split core mold 2 side as shown in the figure, so that the slit mold 3 can move forward and backward toward the center. By moving the slit mold 3 in the center direction, the core mold can be contracted in the axial direction via the slit relief portion 5.

In order to move the slit part 3 toward the center, a cylinder member 4 using hydraulic pressure, pneumatic pressure, etc. is connected to each divided portion as shown in the figure, and the cylinder member 4 is moved back and forth. Therefore, the cylinder member 4 is attached to the circumferential side of the centrifugal casting mold 1, and its reciprocating rod is slidably penetrated through the centrifugal casting mold 1 and connected to each divided portion.

Furthermore, when driving this cylinder member 4, when the poured molten metal starts to solidify and shrink within the core mold consisting of the split core mold 2 and the slit part 3, it moves toward the center of the slit part 3. In order to control the drive so that the core is pulled back, that is, pulled up, a thermocouple 6 as a heat sensor is disposed on a part of the circumference of the split core mold 2 via the centrifugal casting mold 1. The temperature sensing portion of the thermocouple 6 is set to be located at the innermost layer portion of the split core mold 2.

In FIG. 1, 1a represents one flange molding surface on the centrifugal casting mold 1 side, 2a represents the other flange molding surface on the split core mold 2, and 4a in FIG.
indicates a rod of the cylinder member 4.

In the present invention, a desired double-flange pipe is manufactured by centrifugal force casting using a mold as illustrated in FIGS. 1 and 2 above. A core mold consisting of a core mold 3 and a split core mold 2 is installed,
A mold for casting a double-flange pipe is constructed, and the inner surface of the slit part 3 is set at the same level as the inner surface of the split core mold 2, and the centrifugal force casting mold 1 is placed in this mold through rotation. The desired molten metal is poured and the two-flange pipes are centrifugally cast.

After the casting is finished, a thermal sensor such as a thermocouple 6 detects the point at which the molten metal begins to solidify and shrink in the core mold, and the cylinder member 4 is driven to open the slit part 3 by 10 to 20 mm from the center. By gradually raising the core mold at a rate of 1/min, the core mold contracts in the axial direction and prevents the flange from breaking.

At this time, the amount of shrinkage can be freely adjusted by changing the mold thickness in the slit part 3 and the magnitude of the taper gradient in the slit escape part S for retracting the slit part 3.

It is preferable that the slit escape portion 5 of the split core mold 2 is designed to be replaceable, so that the split core mold 2 can be used in common for different taper slopes.

Next, manufacturing examples will be listed and explained.

Product pipe outer diameter 2001mφ x wall thickness 20iπ x total length 150
Production of double-flanked pipes made of 0mm aluminum material.

■, A core mold consisting of a split core mold and a slit part described below is installed in a centrifugal casting mold, and the first core mold described above is
A mold having the configuration shown in the figure was obtained.

The main part of the split core mold 2 has a tube outer diameter of 264φ.
x Wall thickness: 30m7IL x Total length: 1490mm, as shown in Figure 3, there is a gap l of 9mm at the axial center of the mold.
0771 Butt, regarding the inclination toward the center, 8 from the inner surface
mm, the inclination angle θ1 is 5°, and then the inclination angle θ2 is 41.4° with respect to the inclination direction, and if the molten metal material is iron, it has a slope of θ2 = 29.6°). It has a slit escape part 5, and the slit part 3 engages with the inclined surface on the inner surface side of the split core mold 2, and has a mold thickness t of 8 peaks in the circumferential direction (radial direction). ), and the inner surface is flush with the divided core mold 2.

At this time, the distance between the outer ends of the flanges of the mold is 1522 mm.
Met.

2. Next, attach the lifting cylinder member 4 to the slit part 3.
A rod 4a of a hydraulic cylinder was connected, the centrifugal casting mold 1 was rotated, and the inner surface of the casting was preheated with a burner.

3. Predetermined rotation, predetermined mold preheating temperature (150-200
℃), the molten aluminum material was poured at a casting temperature of about 680℃.

4. A thermocouple 6 is embedded in the split core mold 2 at a position 5m11L from the inner surface, and the time when the thermocouple 6 shows a peak after completion of casting (approximately 2 minutes after completion of casting) From the slit part 3 was pulled up 20 times using a hydraulic cylinder at a rate of 10 to 20 times per minute.

At this time, the core mold was able to shrink for about 23 minutes in the axial direction.

5. After solidifying and cooling the molten metal, stop the rotation, remove the rod 4a of the hydraulic cylinder from the slit part 3, and pull out the core mold together with the solidified brim pipes from the centrifugal casting mold 1.
The mold was demolded to obtain the desired double-flange pipe.

No neck breakage occurred in the flange portions of the both brim pipes.

By the way, during this manufacturing, a thermocouple is also set in the part that comes into contact with the molten metal, and similarly to the temperature of the split core mold 2,
The temperature of the molten metal was also measured.

The results are shown in FIG.

In the figure, the horizontal axis shows the elapsed time (minutes) after completion of casting, the vertical axis shows the temperature (° C.), a shows the molten metal temperature, and b shows the split core mold temperature.

From the figure, at the peak of the split core mold temperature, the molten metal is approximately 60%
It can be seen that the molten metal starts solidifying at 0°C.

As described above, according to the method of the present invention, a core mold that is divided in the circumferential direction and has a built-in slit part is housed in a centrifugal force casting mold to constitute a mold for casting double-flange pipes. After pouring the desired molten metal into the mold, a thermal sensor on the core mold side gradually pulls up and moves the slit parts divided in the circumferential direction toward the center when the molten metal solidifies and contracts. Since the mold can be contracted in the axial direction, it is possible to effectively prevent neck breakage at the flange part.Furthermore, since the casting of both brim pipes is all done in the centrifugal casting mold and the core mold, the outer surface The cooling rate of the mold is faster than that of the conventional sand mold, so it is possible to easily obtain a high-density cast product, and according to the present invention, the split core mold 2 and the slit part mold 3 can be made repeatedly. Because it can be used, if both molds are manufactured first, it is more economical than traditional sand molding, and manufacturing costs can be reduced. It is an excellent casting method.

[Brief explanation of drawings]

Fig. 1 is a longitudinal sectional front view of a mold made by the method of the present invention, Fig. 2 is a sectional view taken along the line A-A in Fig. 1, and Fig. 3 is a slit section of a split core mold used in a manufacturing example of the present invention. FIG. 4 is a diagram showing temperature changes in the molten metal and the split core mold after completion of casting in a manufacturing example of the present invention. 1...Centrifugal force casting mold, 2...Split core mold, 3...Made of slit part, 4...
Cylinder member, 5...Slit relief part, 6...
····thermocouple.

Claims (1)

[Claims] 1. When obtaining a double-flange pipe by centrifugal force casting, a core mold that is divided in the circumferential direction and has a built-in slit mold is installed inside the casting mold, and the slit mold is also divided in the circumferential direction, and Using a mold that can move forward and backward toward the center using a thermal sensor on the core mold side, the desired molten metal is poured into the mold, and when the molten metal solidifies and shrinks, it is pulled up from the center of the slit mold. A method for manufacturing a double-flange pipe characterized by preventing neck breakage at the flange portion.