JPH04279254A - Twin roll type casting method for phosphor bronze strip having excellent internal characteristic - Google Patents

Abstract

PURPOSE:To cast a phosphor bronze strip having excellent surface characteristic by pouring the molten phosphor bronze into a twin roll continuous caster using the specific atmosphere. CONSTITUTION:At the time of directly casting the strip by pouring the molten phosphor bronze into the twin roll continuous caster, by using inert and insoluble gas atmosphere containing steam of <=10g/cm<3> absolute humidity, the casting is executed. By this method, blow hole and surface fold developed at rapid cooling part due to the rolls at the time of directly casting the phosphor bronze cast strip in the twin roll caster can be prevented and the phosphor bronze strip having excellent surface characteristic can be cast.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a twin-roll casting method for phosphor bronze thin sheets with excellent surface properties.

0002

[Prior Art] Phosphor bronze is mainly used as a spring material, and has a Cu-4-8% Sn alloy with a 0.03-0.35%
%P has been added, and has improved toughness and elasticity compared to bronze. Due to its wear resistance, it is also used in gears, bearings, etc. It is also known that adding lead (free-cutting phosphor bronze) improves machinability. For example, it has been proposed in Japanese Patent Application Laid-Open No. 1-107943 to directly cast a phosphor bronze thin plate using a twin-roll continuous casting machine;
．． When casting 5-5 mm thin plate slabs in a twin-roll casting machine, it is extremely important to obtain good surface and internal properties. Furthermore, Japanese Patent Application Laid-open No. 77151/1983 proposes a method in which casting is carried out using twin rolls in an inert gas atmosphere to prevent oxidation of the cast strip. Surface defects in slabs are represented by pores and surface wrinkles generated during solidification of slabs, but a twin-roll casting method for phosphor bronze sheets with excellent surface properties has not yet been established industrially.

0003

[Problems to be Solved by the Invention] When a thin plate slab of phosphor bronze is directly cast using a twin-roll type casting machine, pores and surface wrinkles are generated in the portion rapidly cooled by the rolls. The present invention proposes a twin-roll casting method for phosphor bronze thin sheets with excellent surface properties.

0004

[Means for Solving the Problems] The present invention provides a method for directly casting thin plates by pouring molten phosphor bronze into a twin-roll continuous casting machine. This is a twin-roll casting method for phosphor bronze thin sheets with excellent surface properties, characterized by the use of an insoluble gas atmosphere.

The present invention will be explained below with reference to the drawings. The phosphor bronze in the present invention is intended for component systems defined by JIS and systems corresponding thereto. After the main body container 1 is evacuated to a predetermined degree of vacuum, argon or helium gas is supplied from the gas supply port 7 to replace the inside of the container 1 with gas in advance. 8
is an exhaust port, and 9 is an opening/closing door. Next, the molten metal is poured from the ladle 2 through the tundish 3 between the cooling rolls 4, 4 to form a molten metal pool 15. The molten metal is passed through cooling rolls 4, 4
The thin plate slab 16 is obtained by rapid cooling and solidification. 14 is a pinch roll.

In the present invention, the insoluble and inert gas is dehumidified in advance to an absolute humidity of 10 g/m 3 or less. According to experiments, when creating an atmosphere of insoluble and inert gas dehumidified to an amount of water vapor with an absolute humidity of 10 g/m3 or less,
The surface properties of the resulting thin plate slabs are excellent, with no pores or surface wrinkles. In other words, dissolved gas is generated when phosphor bronze solidifies, and this forms pores and surface wrinkles on the surface of the slab, but by removing trace amounts of moisture contained in the insoluble and inert gas, the surface quality during solidification is improved. It is possible.

[0007]

EXAMPLE A thin slab of phosphor bronze (Cu-5.5%Sn-0.1%P) with a thickness of 2 mm was cast using a twin-roll casting machine shown in FIG. Argon was used as the atmosphere. The temperature of the gas is room temperature. Table 1 shows the absolute humidity, surface pores, and surface wrinkles.

[0008]

[Table 1]

(Note) Those with a pore size of 0.1 mmφ or more were calculated and ranked.

0010 A: 0.1 pieces/cm2 or less B: 0.1 to 1 piece/cm2 C: 1 piece/cm2 or more The method for evaluating surface wrinkles is as follows.

[0011] A: 0.1m/m2 or less B: 0.1-1m/m2 C: 1m/m2 or more

0012

Effects of the Invention In the present invention, since the twin roll casting atmosphere is made of an inert gas that does not dissolve trace amounts of water, it is possible to obtain a thin plate slab of phosphor bronze with excellent surface properties.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the present invention.

[Explanation of symbols]

1 Main container 4 Cooling roll 7 Gas supply port 8 Exhaust port 16 Thin slab slab

Claims (1)

[Claims] Claim 1: When pouring molten phosphor bronze into a twin-roll continuous casting machine to directly cast a thin plate, the absolute humidity is 10.
A twin-roll casting method for a phosphor bronze thin plate with excellent surface quality, characterized by using an inert and insoluble gas atmosphere containing water vapor of less than g/m3.