JPH05138322A - Centrifugal casting apparatus - Google Patents

Abstract

PURPOSE:To obtain close casting structure and to improve the wear resistance of a casting product. CONSTITUTION:In a centrifugal casting apparatus provided with a metal-made mold a flowing passage 17 for passing through the cooling water in the inner part of the mold 11 is arranged. The cooling water is supplied into the flowing passage 17 in the inner part of the mold 11 by pressurizing with a pump 38 and forcedly passing through the flowing passage 17 to cool the mold 11. Molten metal contacting with the inner peripheral surface of the mold 11 is rapidly cooled at high solidifying speed to form the close casting structure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a centrifugal casting device for casting hollow or solid castings.

The present invention is used for casting alloy castings which are required to have wear resistance, heat resistance or toughness.

[0003]

2. Description of the Related Art For casting concentric products such as hollow cylinders,
Centrifugal casting is widely used because it does not require a core and has high productivity and yield. Especially, since the solidification rate is higher than that of the static casting method and a dense casting structure can be obtained, the centrifugal casting method is adopted for casting of high alloy castings such as rolling rolls that require wear resistance and toughness. ing.

Recently, high speed alloys have been used as materials for rolling rolls. Table 1 shows an example of the chemical composition of the rolling roll of such HSS alloy.

[0005]

[Table 1]

Since Cr, Mo, W, V, etc. in the components form high hardness MC, M ₆ C carbides, the wear resistance of the rolling roll is remarkably improved. Due to the advantages of centrifugal casting, centrifugal casting is also used in the production of rolling rolls of HSS alloy. (For example, “Material Process” 4-2 (199
1) See 446-449)

[0007]

As described above, the centrifugal casting method has a higher solidification rate than the static casting method, but a higher solidification rate is required for the cast product of the HSS alloy. That is, in the case of a cast product of a high-speed alloy, when the solidification rate is low, carbides are largely deposited and the cast structure becomes rough. As a result, the hardness decreases and the wear resistance deteriorates.

The present invention provides a centrifugal casting apparatus capable of obtaining a dense casting structure and improving the wear resistance of a cast product.

[0009]

In the centrifugal casting apparatus of the present invention, a flow path through which cooling water flows is provided inside a metal mold.

The material of the mold is appropriately selected according to the material to be cast, but copper is suitable. The channels are formed inside the mold body, and it is desirable to provide a plurality of channels, for example, 4 to 20 channels independent of each other. FIG. 3 shows an example of the relationship between the number of channels and the solidification rate. By increasing the number of independent flow paths, the flow path of the cooling water from the inlet to the outlet of each flow path can be shortened accordingly, and the temperature rise of the cooling water due to heat transfer from the inner surface of the mold can be suppressed. .. Therefore, the cooling effect of the mold with the cooling water can be enhanced. However, if the number of channels exceeds 20, as shown in FIG. 3, the rate of increase in the solidification rate saturates and the structure of the mold becomes complicated, which is not preferable. Note that FIG. 3 also shows the relationship between the material of the mold and the solidification rate.

[0011]

The cooling water is pressurized by the pump and supplied to the flow path inside the mold, and forcedly flows through the flow path to cool the mold.
The molten metal in contact with the inner peripheral surface of the mold is rapidly cooled and cooled at a high solidification rate to form a dense cast structure. As a result, wear resistance is improved. FIG. 4 shows an example of the relationship between the solidification rate and the amount of wear of the rolling rolls.

[0012]

EXAMPLE A centrifugal casting apparatus for casting a rolled roll material will be described as an example. 1 is a vertical sectional view of a centrifugal casting apparatus of the present invention, and FIG. 2 is a sectional view taken along the line AA of FIG.

As shown in these drawings, the mold 11 of the centrifugal casting apparatus has a cylindrical shape as a whole and is supported at an angle of about 30 degrees. The mold 11 is the main body 12 and the upper shaft part mold 1
4 and a lower shaft mold 15 whose bottom is closed. The main body 12 is provided with 16 flow paths 17 at equal intervals in the circumferential direction. Each channel 17 has a U-shape that is open on the lower side and extends toward the upper side. With the bottom plate 18 provided with the cooling water supply port 19 in the center,
The bottom of 2 is closed. Further, a space is provided between the lower shaft portion mold 15 and the bottom plate 18, and the space is formed in the main body 12
The cooling water distribution unit 21 communicates with each of the flow paths 17.

The mold 11 is supported by a cup-shaped support frame 25 and a drive roller 28. That is, the support frame 25 is fixed to the pedestal 23, and supports the bottom plate 18 of the mold 11 via the support rollers 26 provided at the bottom. The drive roller 28 supports the main body 12 via a support ring 13 fixed to the outer periphery of the main body 12 of the mold 11. Both ends of the rotary shaft 29 of the drive roller 28 are supported by bearings 30, and a bevel gear 32 is attached to the central portion. On the other hand, a motor 34 with a reducer is fixed to the pedestal 23, and the motor 3
A large bevel gear 35 that meshes with the small bevel gear 32 is attached to the output shaft of No. 4. When the motor 34 is driven, the drive roller 28 rotates, and the mold 11 rotates due to frictional transmission between the drive roller 28 and the support ring 13.

A rotary joint 36 is attached to the center of the bottom of the support frame 25. The inlet side of the rotary joint 36 is connected to the cooling water supply pump 38 via the pipe 37, and the outlet side of the rotary joint 36 is connected to the mold 1.
The bottom plate 18 is connected to the cooling water supply port 19. A drain port 27 that opens toward the drain tank 40 is provided below the support frame 25.
When the cooling water supply pump 38 is driven, the cooling water passes through the rotary joint 36 and the cooling water distributor 21 and flows through the flow path 17 of the main body 12.
Flow into. Then, the cooling water flows through the flow path 17 while cooling the mold 11, reaches the support frame 18, and flows out to the drain tank 40.

With the centrifugal casting device constructed as described above, the body diameter is 890 mm, the shaft diameter is 690 mm, and the length is 1900 mm.
The rolled roll material was cast. Table 2 shows the chemical composition of the roll material
Shown in. Ductile cast iron was used as the core material.

[0017]

[Table 2]

The mold is made of copper, and the outer diameter of the main body is 1350.
mm, the inner diameter is 890 mm. The number of channels is 16 and the diameter is 40 mm. The flow rate of cooling water in each channel is 50
It was l / min. After casting, the roll material is destabilized by heat treatment (about 1000 ° C x 1h) and tempered (about 500 ° C x 1h).
h) was done.

As a result of casting, the solidification rate was 6 mm / min, and the precipitated carbide was refined as shown in FIG. 5 (a). As a conventional example, a similar rolling roll material was cast without water cooling. As a result, the solidification rate was 4 mm / min.
As shown in (b), the precipitated carbide was coarse. Also,
The wear resistance life of the rolling roll cast by the apparatus of the present invention is about 1.3 times longer than that of the conventional one.

[0020]

In the centrifugal casting apparatus of the present invention, the cooling water is forced to flow through the channel to cool the mold, so that the molten metal is rapidly cooled and cooled at a high solidification rate. As a result, a dense cast structure is formed and wear resistance is improved.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a centrifugal casting apparatus according to the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG.

FIG. 3 is a graph showing an example of the relationship between the number of channels and the solidification rate.

FIG. 4 is a graph showing an example of a relationship between a solidification rate and a wear amount of a rolling roll.

FIG. 5 (a) shows the device according to the invention and FIG.
(B) is a micrograph showing the structure of a rolling roll cast by a conventional apparatus.

[Explanation of symbols]

11 Mold 28 Drive Roller 12 Mold Body 30 Bearing 13 Support Ring 32 Bevel Gear 17 Flow Path 34 Motor 18 Bottom Plate 35 Bevel Gear 21 Cooling Water Distributor 36 Rotating Joint 23 Frame 38 Cooling Water Supply Pump 25 Support Frame 40 Drain Tank 26 Support Roller

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shoichi Araya 20-1 Shintomi, Futtsu City, Chiba Shin Nippon Steel Co., Ltd.

Claims (1)

[Claims] 1. A centrifugal casting apparatus provided with a metallic mold, characterized in that a channel through which cooling water flows is provided inside the mold.