JP2559905B2 - Centrifugal casting method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a centrifugal casting method for producing a hollow casting by casting molten metal in a mold that is driven and rotated.

[Prior Art] In the conventional centrifugal casting method, a method of applying a coating material to the inner peripheral surface of a mold and then pouring the molten metal into the mold while drivingly rotating the mold is adopted.

[Problems to be Solved by the Invention]

However, in the conventional centrifugal casting method described above, when a small-diameter pipe is manufactured, the surface of the product often has rough skin called pig skin that may cause cracking of the pipe, resulting in poor product yield. Met. Upon investigating the cause, the mold coating material was not uniformly applied to the required thickness, and the molten metal entered into the insufficiently applied area during casting and was seized on the inner peripheral surface of the mold. There was an insertion. And when this insertion occurs remarkably, a draft for a centrifugal casting mold cannot be basically provided, and therefore the cast pipe may not come off from the mold, which is a manufacturing aspect. Was disadvantageous.

In particular, for small diameter and long molds for producing small diameter pipes, it is difficult for the coating material coating nozzles and the like to enter the interior of the mold, which tends to result in incomplete coating of the coating material.
Since the above-mentioned inconvenient phenomenon is likely to occur, it has been difficult to manufacture a pipe having a small diameter in the conventional centrifugal casting method.

In view of the above circumstances, an object of the present invention is to provide a centrifugal casting method capable of preventing seizure of molten metal on the inner peripheral wall of a mold to obtain a product with less rough skin, and capable of smoothly releasing the mold. .

[Means for solving the problem]

The first feature of the centrifugal casting method according to the present invention is to apply a seizure prevention sheet capable of preventing seizure of the molten metal to the inner peripheral wall of a centrifugal casting mold, and apply the seizure prevention sheet to the inner peripheral surface. After applying the material, the molten metal is cast into the mold while drivingly rotating the mold.

And the 2nd characteristic of the centrifugal casting method by this invention is
A ceramic paper is used as the seizure prevention sheet in the first feature.

[Work]

That is, the anti-seizure sheet made of ceramic paper or the like has a sheet-like shape, and therefore has a substantially uniform thickness, has a substantially uniform overall surface, and has continuous surfaces on both front and back surfaces thereof. It is possible to wind and unroll. Therefore, it is suitable for covering the surface of an object, and since it can be wound up, the seizure prevention sheet cut into a predetermined size is rolled into a cylindrical mold with a smaller size than the inner diameter of the mold. It is possible to insert it inside and unfold it to adhere to the inner surface of the mold. For example, the seizure prevention sheet in a state of being wound in a diameter slightly smaller than the inner diameter of the mold is inserted into the mold, and if the mold is rotated, the seizure prevention sheet is short-timed by centrifugal force. The seizure prevention sheet is developed along the inner surface of the mold, and is easily attached to the inner surface of the mold. Therefore, even if the mold has a small diameter and a long size, it can be easily attached to the inner peripheral wall, and the inner peripheral wall can be surely covered. Therefore, seizure of the molten metal on the inner peripheral wall of the mold can be sufficiently prevented. Furthermore, since the coating material is applied to the inner peripheral surface of the seizure prevention sheet, the effect of the coating material is also added, and the seizure can be sufficiently prevented. In order to prevent pouring of the molten metal, it is not always necessary to apply the mold coating material sufficiently or surely to prevent seizure by itself, and the seam of the seizure prevention sheet should be kept in the adhered state. And, it is enough to prevent the leaching of the molten metal from the joint. This is because the seizure prevention sheet plays a sufficient role in preventing seizure, and only the seam of the seizure prevention sheet is a part where molten metal may be poured, and the mold coating material is to supplement this. Because it is. For example, if the seizure prevention sheet is attached to the inner peripheral wall of the mold by centrifugal force and the coating material is sufficiently applied to the entire inner periphery of the seizure prevention sheet, the seizure prevention sheet is pressed against the inner peripheral wall of the mold by centrifugal force. The anti-seizure sheet is held in close contact with the mold to reliably exhibit the effect of preventing seizure. In addition,
If this mold coating material is applied while rotating the mold, the above state can be maintained more reliably, and the inner peripheral surface of the mold can be formed well.

Furthermore, the seizure prevention sheet is only attached without being integrated with the mold, so when pulling out the product from the mold,
Even with a small-diameter and long-sized mold for making small-diameter pipes where the seizure prevention sheet can be slipped out and uniform application of the mold coating material is difficult, a draft for the centrifugal casting mold is provided while preventing seizure. Even if it is not provided, the mold can be easily released and casting can be performed.

In particular, when ceramic paper is used as the seizure prevention sheet as described in claim 2, it has excellent heat resistance and can sufficiently fulfill the seizure prevention function.

〔The invention's effect〕

Therefore, unlike the case where the seizure was prevented only by the coating material layer, which could not always be expected to be uniformly applied in the past, the seizure can be prevented mainly by reliably covering the inner peripheral wall of the mold. By supporting the seizure prevention sheet and using a coating material to prevent the intrusion of molten metal into the joints, you can easily form a coating of the seizure prevention sheet on the inner surface of the mold and pull out the product from the mold. Moreover, since the anti-seizure sheet can be pulled out together, the mold release becomes easy. Therefore, without being greatly affected by the good or bad of the coating state of the mold coating material, while protecting the inner surface of the mold from pouring of the molten metal, the mold release is facilitated even in a centrifugal casting mold without draft. In addition, it is also possible to prevent the occurrence of flaws on the surface of the casting during mold release.

As a result, seizure prevention can be achieved not only in the mold for making large diameter pipes but also in the small and long molds for making small diameter pipes, which has been difficult in the past. From small diameter pipes to small diameter pipes, it is possible to obtain high quality cast products with less skin roughness and less risk of cracking, and it is also possible to smoothly remove the resulting cast product from the mold, and there are few problems in terms of production. It is now possible to provide a centrifugal casting method.

〔Example〕

 Embodiments of the present invention will be described below with reference to the drawings.

The centrifugal casting apparatus used in the centrifugal casting method of the present invention is the first
As shown in the figure, a pair of drive rollers (2A) and a pair of idler rollers (2A) are provided below the cylindrical mold (1) having a thickness of about 200 mm with the axis (P) oriented horizontally. 2B) and the mold (1)
The motors (3) are arranged in a distributed manner in the circumferential direction and are linked to the drive roller (2A).

When performing centrifugal casting using this centrifugal casting apparatus, first, as shown in FIG. 2, a seizure prevention sheet (4) made of ceramic paper is attached to the inner peripheral wall of the mold (1). For this deposition, for example, the seizure prevention sheet (4) is positioned in the mold (1), the mold (1) is driven and rotated, and the centrifugal force associated with the rotation causes the inner peripheral wall of the mold (1) to rotate. It is done by pressing against.

Next, the coating material (5) is applied to the inner peripheral surface of the seizure prevention sheet (4). The mold coating material (5) also functions to prevent the molten metal from sticking to the inner peripheral wall of the mold (1) in cooperation with the seizure prevention sheet (4), but mainly the combination of the seizure prevention sheet (4). This is a sealing material for preventing the molten metal from seeping out from the eyes. Therefore, the application of this coating material (5) is much less than the conventional method in which the coating material is used alone to prevent seizure. It does not have to be done carefully.

Then, with one end of the mold (1) closed, the mold (1) is driven and rotated, and the molten metal is cast into the mold (1) from the other end side to form a cast steel pipe. Is manufactured.

As described above, by the cooperation of the seizure prevention sheet (4) made of ceramic paper and the coating material for sealing it, the seizure on the inner peripheral wall of the mold (1) can be effectively prevented,
As a result, it is possible to obtain a cast steel product with less surface roughness and less risk of cracking, and the product after casting is also the mold (1).
I was able to extract it smoothly.

[Another embodiment]

 Next, another embodiment of the present invention will be listed.

<1> In the above embodiment, the coating material is the seizure prevention sheet (4).
Although it is applied to almost the entire inner peripheral surface of the sheet, if it is possible to sufficiently secure the seizure prevention function of the seizure prevention sheet (4) itself, it may be concentrated on only the joint portion.

<2> As the seizure prevention sheet (4), besides a sheet made of ceramic paper, a resin sheet or the like having high heat resistance may be used.

In the claims, reference numerals are provided for convenience of comparison with the drawings, but the present invention is not limited to the configuration shown in the attached drawings.

[Brief description of drawings]

The drawings show an embodiment of the centrifugal casting method according to the present invention.
FIG. 1 is a plan sectional view of a centrifugal casting apparatus, and FIG. 2 is a cutaway perspective view of a centrifugal casting mold. (1) …… Mold, (4) …… Seizure prevention sheet (5) …… Coating material

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-52-30721 (JP, A) JP-A-62-9746 (JP, A) Actual development Sho-58-137556 (JP, U) JP-B-51- 17936 (JP, B2) Actual public Sho 55-53237 (JP, Y2)

Claims (2)

(57) [Claims] 1. An anti-seizure sheet (4) is attached to the inner peripheral wall of a centrifugal casting mold (1) to prevent the molten metal from sticking to the inner peripheral wall of the mold (1). Anti-seize sheet (4)
After applying a mold coating material (5) to the inner peripheral surface of the mold, the mold (1)
Centrifugal casting method in which molten metal is cast into the mold while driving and rotating. 2. The centrifugal casting method according to claim 1, wherein ceramic paper is used as the seizure prevention sheet (4).