JPS5849348B2 - Centrifugal casting method for tubes with protrusions on the inner surface - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a new casting means for obtaining a tube having a protrusion on a part of the inner surface of the tube by centrifugal casting.

Needless to say, metal tubes having a thick protrusion on a part of the inner circumferential surface are known, but when obtaining such a tube, the inner surface of the tube may be cut or otherwise mechanically processed. Forming by
This is disadvantageous in terms of material loss as it increases material loss, and the shorter the axial length of the thick protrusion is compared to the overall length of the tube, the more disadvantageous it is. There are other problems, such as being limited to

Various methods have also been proposed for forming protrusions by centrifugal casting, but in many cases the casting operation is difficult or the structure of the casting machine itself is complex, making them impractical ().

The present invention makes it possible to easily obtain thick protrusions on a part of the inner surface of such a tube by casting means. When casting a tube body having a section, a centrifugal casting metal frame in which a protrusion-shaped core mold made of a sand mold or the like is placed at the protrusion forming position is rotated in an attitude tilted in the axial direction. By placing the pouring trough close to the core mold side and pouring the metal, the inner protrusion is cast in advance, and then the metal frame is restored to a horizontal position and rotated, and the remaining portion is poured through the pouring trough. By casting the tube, a tube having a protrusion on a part of the inside of the tube can be obtained.

The method of the present invention will be described in detail below with reference to the embodiments shown in the drawings. Figures 1 and 2 show the basic embodiment, and Figure 1 shows an example in which a metal frame for centrifugal casting is tilted to form internal protrusions. In the figure, reference numeral 1 is a centrifugal casting metal frame for casting tubular bodies as in the past, but in the present invention, the inner protrusion of such a metal frame 1 is shaped or For example, use the band 3 at one end of the metal frame and extend it integrally from the band 3 at the desired position (for convenience, the illustration shows a tube with an internal protrusion at one end). Alternatively, a cylindrical support 4 fixedly supported by the band 3 is used, and a core mold 5 for the inward protrusion formed by, for example, a sand mold is supported on this support 4.

When molding the core mold 5 using a sand mold, it is preferable to use, for example, foundry sand mixed with zircon or shift in order to speed up cooling, but of course any material that has the property of accelerating the cooling of the molten metal may be used. For example, this does not preclude the use of other materials that are disintegrative after casting.

In the same figure, numeral 2 indicates a refractory coating layer applied to the entire inner surface of the metal frame 1.

In the present invention, the metal frame 1 in which the core mold 5 is placed at the position where the intended inner protrusion is to be formed is first shaped into a shaft so that the core mold 5 side is on the lower inclined side as shown in the figure. The direction is preferably inclined at an angle of 5° or more and 200° or less, and the pouring trough 6 is inserted into the metal frame according to the inclination, and the tip of the trough is brought close to the core mold 5Ill, and the metal frame 1 is placed in an inclined position. While rotating at GNO20 to GNO40, pour the required molten metal from the pouring trough 6, and pour the molten metal A along the slope to form the inner protrusion formed between the core mold 5 and the inner surface of the metal frame 1. By inflowing and filling the cavity,
The inner surface protrusion A and the opening of the tube body following it are pre-cast in one piece.

The reason why the inclination angle of the metal frame 1 is desirably set to 5° or more and 200° or less is that if it is less than 5°, the poured molten metal will spread in the axial direction due to centrifugal force, making it difficult to step.
If the axial thrust load on the metal frame 1 exceeds the This is because the casting machine and related equipment become complex and large-scale.

After the inner protrusion A and one mouth of the tube body are pre-cast in this way, the pre-cast portion near the joint 2 between the pre-cast portion and the remaining tube body 8, which will be described later, completes solidification, while the The metal frame 1 is kept in the tilted position until the opening of the tube starts to solidify, and then the metal frame 1 is restored to the horizontal position as shown in FIG. By pouring hot metal, while keeping the rotation of the metal frame 1 at GNO20 to 40 as described above, pour the remaining tube body 8, which is the remaining tube part following the inner surface protrusion A and the opening of the tube body, as shown in the figure. The molten metal is poured through the sequential movement of the trough 6, and the rotation of the metal frame 1 is increased to a GNO of 40 to 80 from the end of casting until just before drawing, solidifying the molten metal to form a tube having a protrusion on the inner surface.

It is easiest to carry out this casting process by dividing it into two steps: the preceding casting shown in Fig. 1 and the subsequent casting shown in Fig. 2. After the preliminary casting of the metal frame 1 is completed, pouring into the metal frame 1 is temporarily stopped, and immediately after the internal protrusion A starts to solidify, the metal frame 1 is returned to the horizontal position, and the metal frame 1 is rotated again to open the trough. The pouring from step 6 will be resumed and subsequent casting will be performed, but instead of this, the pouring speed and the square title of metal frame 1 will be changed. It goes without saying that the A alignment makes it easy to carry out the process continuously in one stroke, and even if the core mold 5 falls over, by improving the cooling performance of the core mold 5, the entire process can be processed efficiently.

In addition, the inner protrusion A does not stop at only one end of the tube, but can be positioned freely.

Figure 3 shows one of the specific devices for carrying out the method of the present invention.
This figure shows an example, and the same reference numerals in the figure indicate the first
, 2 shows the same parts as in Figure 2, but as shown in the figure, the entire centrifugal casting equipment is constructed by having one end pivoted on a fixed pitch 7 by a pivot 8, and the other end being connected and supported by a rod 10 of a hydraulic cylinder 9. The metal frame 1 is arranged on a movable bed 11 that is horizontally arranged and supported so as to be tiltable. The pouring trough 6 is supported by a trolley 14 mounted on the rail 13 on the bed 11 so as to be able to run and stop freely, and is movable in and out of the metal frame 1. Pouring pot 15
is rotatably installed by a driving member 16 such as a fluid pressure cylinder, so that molten metal can be poured into the trough 6.

Of course, the device itself can be freely designed.

Next, examples will be given and explained.

The production of a centrifugal cast iron pipe having an actual inner diameter of 5QOmmφ, an actual outer diameter of 520mrfLφ, a total length of 2000rrLm, a socket at one end, and an inner protrusion at the other end will be explained with reference to the manufacturing time chart shown in Fig. 4. do.

1. At one end of the centrifugal casting metal frame, a band with an inner diameter of 470 mm and a length of 500 mm was attached with a ten-shaped pattern for forming an inner protrusion, and at the other end, a sand mold was installed for forming a socket. Attach the attached band.

The core mold is formed of foundry sand mixed with zircon sand on a metal cylindrical support fixedly supported by a band.

2. Next, as shown in the fourth drawing section, the metal frame was tilted at an angle of 1,000 degrees, rotated with GNO30, and the inner protrusion was cast. When the inner protrusion began to solidify (3 minutes after the start of casting), Set the metal frame inclination angle to 0°.

5. Next, as shown in section ■ in the figure, the remaining pipe is cast for 5 seconds.

4. Next, as shown in section ■ in the figure, when the casting of the remaining pipe body is completed, the rotation of the metal is increased by GNO60K, held for 5 minutes, the rotation is stopped after solidifying the molten metal, and the product is cooled down. Pull it out.

FIG. 5 shows a partial longitudinal sectional view of the inward protrusion side of the centrifugal cast iron pipe having the inner protrusion obtained as described above.

In the figure, 5' is the core type, which has an inner diameter of 472 mπφ, a wall thickness of 24 mm, and a length of 500 mm, with a small diameter part A having an inner protrusion A', and a subsequent sloped part and an inner diameter of 492 mmφ. A medium diameter portion B is formed, and a gently sloped portion C having a length of approximately 150 mm is formed together with the medium diameter portion B during casting of the inner surface protrusion I and the tube body part mouth. Inner diameter 500 mmφ, wall thickness 10rn7
The remaining pipe body 8' of rt is shaped, and the gently inclined part C
and the remaining tube body 8' were completely welded together.

By the method of the present invention, the target metal tube having a thick protrusion in a part of the inside of the tube can be produced by employing centrifugal casting means, its unique inclination, horizontal pouring, and core type. It is extremely easy to obtain.

In this way, while tilting the centrifugal casting metal frame 1, the core mold 5 is placed in the desired inward part, and by tilting the pouring metal and rotating the metal frame, the part of the tube having the thick protrusion first comes first. If the metal frame 1 is then returned to the horizontal position and the remaining tube parts are cast, a tube with an internal protrusion can be obtained very easily and reliably, and even two-step casting can be used. The collapse of continuous one-stroke casting is sufficient, and the integrity of the protrusion and the tube body is of course good.Moreover, it does not require any significant changes to the conventional centrifugal casting means, and it is simply possible to change the horizontal and inclined postures with respect to the metal frame 1. Only the movable and maintenance means need be added, and the casting means itself can be exactly the same as conventional centrifugal casting operations, and there are no difficulties in terms of equipment or inspection. Compared to those in which a protrusion is further cast on the inner surface, it is superior in terms of integrity, ease of operation, and no risk of failure. This means that it can be economically mass-produced without fear of loss or processing time.

[Brief explanation of drawings]

Fig. 1 is a longitudinal sectional front view of a half part showing the preliminary casting of the inner protrusion in the method of the present invention, Fig. 2 is a front view of the same half showing the casting of the remaining part, and Fig. 3 is a specific casting equipment for carrying out the method of the present invention. It is a partially vertical front view of one example. FIG. 4 is a manufacturing time chart showing an embodiment of the method of the present invention, and FIG. 5 is a partial longitudinal sectional view of the vicinity of the inner surface protrusion of a centrifugal cast iron pipe having an inner surface protrusion. DESCRIPTION OF SYMBOLS 1... Metal frame for centrifugal casting, 2... Fire-resistant coating layer, 3... Band, 4... Support, 5... ... Core type, 6 ... Pouring trough, A ... Inner surface protrusion, mouth ... Part of pipe body,
Ha...Remaining pipe body.

Claims (1)

[Claims] 1. When casting a tube body having a protrusion on the inner surface of the tube by centrifugal casting means, a centrifugal casting metal frame in which a protrusion forming core mold made of a sand mold or the like is placed at the protrusion forming position is tilted in its axial direction. By rotating the metal frame and pouring the metal by bringing the pouring trough close to the core mold side, a protruding inner surface is pre-casted, and then the metal frame is restored to a horizontal position and rotated, and the metal mold is poured. A centrifugal casting method for a tube having a protrusion on its inner surface, characterized in that a tube having a protrusion on a part of the inner surface of the tube is obtained by casting the remaining tube through a trough.