JPS5835787B2 - Casting method for metal tubes with protrusions on the inner surface - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a new method for easily and easily obtaining a metal tube having a protrusion on a required portion of the inner surface of the tube using centrifugal force casting means.

In various metal tubes, a part of the inner peripheral surface of the tube,
For example, it goes without saying that structures having thick protrusions at the center or ends of the tube are known, and when obtaining such a tube, it is not possible to form the tube by cutting or other mechanical processing means. Needless to say, the machining is troublesome and there is a lot of material loss.In particular, the smaller the axial length of the thick protrusion compared to the overall length of the tube, the more disadvantageous it is.

Methods such as shrink fitting are limited in terms of materials, and problems remain in terms of integrity.

The present invention uses a casting method that relatively easily and ensures reliable integrity of the metal tube body that requires a protrusion on a required portion of the inner surface, thereby eliminating material loss and the like. The feature is that the first layer is formed by pouring the metal into the centrifugal casting metal frame, and immediately before the first layer starts to solidify, a small amount of tube charging is performed. A weir material made of the same material as the body material is blown into a predetermined position on the inner surface of the first layer using a feeding means such as a blowing pipe to form a wall-shaped weir, and then by the time the first layer is solidified, the weir is By pouring molten metal onto the partitioned first layer to form the second layer, a metal tube with a protrusion formed on the inner surface of the tube due to the integration of the first and second layers can be obtained. be.

The present invention will be described in detail below with reference to the illustrated embodiments. The one illustrated in FIG. 1 is an example in which a protrusion is formed on the inner surface of one end in the axial direction of the tube body, and 1 is a centrifugal casting means. This is a known metal frame to be used, which is rotatable by an appropriate rotation drive means (not shown), and the inner surface of this metal frame 1 is lined with a refractory coating layer 2 in the usual manner, band 3
, 3, the first layer 5a is centrifugally cast using the rotation of the metal frame 1 to a required thickness by pouring the metal into the metal pouring trough 4. It is assumed to span the entire length.

Next, immediately before the solidification of the first layer 5a begins, using the pouring trough 4, a blowing pipe 6 attached to the pouring trough 4 is used to blow vibro, as shown by the dotted line from the solid line in the figure. The opening 6a is positioned at a desired position on the inner surface of the first layer 5a as the trough 4 moves, and the weir material is blown onto the inner surface to form the weir 7 here.

When forming this weir 7, the timing of the injection is important; if it is too early, the material for the weir will melt into the molten metal of the first layer 5a, making it difficult to form a bulge in the weir 7, and vice versa. If the timing of blowing is delayed, not only will it be difficult to weld the weir material and the first layer 5a together, but also the timing of casting the second layer, which will be later cast on top of the first layer 5a, will be delayed, and the first layer 5a will be
This makes it difficult to fuse the two layers, and the best result is obtained when the injection timing is just before the molten metal of the first layer 5a starts to solidify.

In addition, it is basically desirable that the material for the weir be of the same quality as the pipe metal to be cast, but it is difficult to fuse and form the weir with a single material, and actual test results show that good results are obtained. The material for the weir to be obtained is a granular shape with a diameter of about 1 to 5 mm, and the metal to be cast, a metal material with a slightly lower melting point than this, and a metal material with a slightly higher melting point than this. Good results were obtained in terms of quantity by using a mixture of approximately 1/3 of the above three ingredients.

For example, in the case of DOI, granular pig iron (melting point 1150℃) 1/3,
Copper (melting point 1083°C) 1/3. Fe-8i (50%Si
Good results were obtained by using a mixture of 1/3 (melting point: 1200° C.).

Further, the shape of the weir 7 itself becomes a chevron-shaped wall as shown schematically by sintering the above-mentioned granular material in a state where it is partially melted by the heat of the molten metal of the first layer 5a. The height of the weir 7 should be at least the thickness of the second layer to be poured and cast later, and this height can be obtained by controlling the amount of weir material blown into the weir. The upper limit of the height of layer 7 may be approximately the same as the thickness of the first layer 5a.

After the weir 7 is formed by the blowing vibro in this way, the second layer molten metal is poured by the hot water supply trough 4 onto the upper surface of the first layer 5a partitioned by the weir 7 to form the second layer 5b. However, when pouring the second layer 5b, if the molten metal of the first layer 5a starts solidifying and is poured before the solidification is completed, the two can be fused together without any problem.

At this time, the thinner the thickness of the second layer 5b is compared to the thickness of the first layer 5a, the faster the pouring should start immediately after the first layer 5a starts to solidify; The thickness of the first layer is 5a
If the thickness is thicker than , the molten metal may be poured just before completion of solidification.

In this way, the first layer 5a and the second layer 5b combined on the first layer 5a on one side of the weir 7 formation position form a protrusion 5' on a part of the inner surface as shown in FIG. 2I. The metal tube body 5 having the above-mentioned structure is obtained by completing the inner surface finishing process.

The formation position of the inner surface protrusion 5' according to the present invention is of course not limited to the end portion of the tube body 5 shown in FIGS. 1 and 2 I.
The formation position can be determined freely by moving the hot water supply trough 4 forward and backward; for example, as shown in
It is also possible to arrange the protrusions 5', 5' in a row at regular intervals, or to form a protrusion 5' having a concave part 5' on the outer peripheral surface as shown in (■) in the same figure. As shown in FIG. 3, it is possible to form a protrusion 5' having a step 5'' on the outer circumferential surface, so that a tube body 5 having various protrusions 5' can be obtained.

The present invention is as described above, and as a result, a tube body having a protrusion of any size at a desired position on the inner surface of the tube can be obtained very easily, with no loss of material and more efficiently than conventional means. Not only can it be mass-produced, but it can also be obtained at a significantly lower cost than conventional methods.

Moreover, according to the present invention, it is possible to perform the conventional centrifugal force casting method very simply by simply attaching a blowing vibro to the inner surface of the tube body. This is an excellent product that can meet the demands for various metal tubes that need to increase in size.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional front view of an embodiment of the present invention, and FIG. 2 is an explanatory diagram of various shape embodiments of the tube body. 1... Metal frame, 2... Fire-resistant coating layer,
3...band, 4...hot water trough, 5
...Pipe body, 5'...Protrusion, 5a...
...First layer, 5b...Second layer, 6...
- Wear material injection pipe, 7... Weir.

Claims (1)

[Claims] 1. When casting a tube body by centrifugal casting means, the first layer is formed by pouring the metal into the metal frame, and immediately before the first layer starts to solidify, a weir material made of at least the same material as the tube body material is added. is blown into a predetermined position on the inner surface of the first layer using a feeding means such as a blowing pipe to form a wall-like weir;
Next, by pouring molten metal onto the first layer partitioned by the weir to form a second layer until the first layer has solidified,
A method for casting a metal tube having a protrusion on the inner surface, characterized in that the first layer and the second layer are integrated to obtain a metal tube in which the protrusion is formed on the inner surface of the tube.