JPS6092063A - Casting method of free-cutting lead steel - Google Patents

Abstract

PURPOSE:To improve the yield of dissolving lead and to distribute uniformly a free-cutting inclusion by casting a molten steel while applying ultrasonic oscillation to the mixed part and the dissolved part of the molten metal and the lead added thereto. CONSTITUTION:The horn 8 attached to the top end of an ultrasonic oscillator 4 is immersed in the molten steel 5 in a casting mold 3. Lead particles 10 are added to the steel 5 and ultrasonic oscillation is applied to the mixed part of the molten steel 5 and the lead particles 10 as well as the molten steel part where the particles 10 are dissolved. The dissolving of the particles 10 into the steel 5 is accelerated. The yield of dissolving is thus improved and the free- cutting inclusion is distributed uniformly, by which the free-cutting lead steel having high quality is cast.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for casting free-cutting steel for ships by an ingot-forming method.

(Prior art 2, its problems) In general, the method for casting lead free-cutting steel, which is a type of free-cutting steel that improves machinability by allowing free-cutting elements to exist in the form of inclusions in the steel, is Fine particles of lead about 0.5 m in diameter are added to the molten steel at the time of casting, and the lead grains are made into υ of 10μ before Lλ in the steel, or they are attached around non-metallic inclusions with a high solidification point, and as the steel cools and solidifies, it becomes fine. A method is adopted in which machinable inclusions are precipitated.

However, the solubility of lead in steel is as small as V'i 0.3%, and this solubility varies depending on the temperature of molten steel and the content of G, Or, N1, etc., and when lead is added, vaporization, evaporation, and Since there is a problem that gravitational segregation occurs to the bottom of the steel ingot and lead accumulates in the taste part of the steel ingot, the above method results in non-uniform precipitation of free-cutting inclusions and lowers the lead dissolution yield. It had the disadvantage of inviting people.

(Object of the invention) The present invention provides a method for casting lead free-cutting steel that eliminates the above-mentioned drawbacks, makes the distribution of lead particles and free-cutting inclusions in a steel ingot uniform, and improves the dissolution yield of lead. This is what we intend to provide.

(Structure of the Invention) In a method of casting lead free-cutting steel by adding ridge grains of lead to the molten steel being cast in the mold 1c and melting the lead by the top pouring or bottom pouring ingot method, the molten steel, etc. Added gn to molten steel
Ultrasonic imaging was added to the mixed part of the lead particles and the part of the molten steel where the lead particles were dissolved to promote dissolution of the lead particles into the molten steel and to improve the distribution of lead particles and free-cutting inclusions in the molten steel. This is a casting method for lead free-cutting steel that aims to achieve uniformity.

(Example) The method of the present invention will be explained below based on the accompanying drawings.

FIG. 1 is a drawing showing an example of making lead free-cutting steel by the top casting ingot method, in which (1) is a ladle, (2) is a nozzle, and (3) is a mold.

(4) is an ultrasonic vibrator, and this fL is housed in a cooling case (6) to protect it from damage due to heat from the molten steel (5). The rows are made of horns made of refractory materials such as alumina and magnesia (
8) is attached in a hanging manner. Then, the ultrasonic transducer body) is attached to the lifting device (9), and the tip of the horn (8) is constantly added with lead particles 110) in the molten steel (5) in the scattering prevention device (3). Immersed in the mixing point rL
, and is designed to increase as the casting progresses.

Length AA of the metal horn (7) and horn (8)
and tB The wavelength of the ultrasonic wave in the Fi horn is λAλ, respectively.
B, AA = (n/2)AA tB=(m/z)λB However, 111. By determining n to a value that satisfies an integer, it is possible to maximize the vibration displacement at the tip of the horn (8).

In addition, in the drawing shown in FIG. 1, an appropriate number of ultrasonic transducers (4) and horns f71 (8) are installed depending on the size of the mold (3). 3) so that ultrasonic vibrations are applied to the entire melt WI (5).

The method of the present invention uses a horn (8) whose tip is immersed in the molten copper (5) in the casting y1+31 to apply ultrasonic vibration to the molten steel (5) and then remove lead from the core. Particle heads are added, and as the casting progresses, the horn (8) is raised to constantly apply ultrasonic vibration to the mixed part of the lead particles α0, and if necessary, for example, when the casting W (3) is large In addition to the horn (8), an ultrasonic vibrator (4) is placed at an appropriate position in the casting m (3), and a molten steel (5) in which lead particles U (to) are melted by the horns (7) and (8). Since lead free-cutting steel is cast by applying ultrasonic vibration to the part, lead particles α0
) into the molten steel (5) is promoted, the dissolution yield of lead is improved, and the lead particles a@ and free-cutting inclusions are dissolved into the molten steel (5).
5) It will be evenly distributed inside.

Furthermore, Figure 2 shows the case of the bottom pouring ingot method.
This may be carried out in the same manner as in the case of the top injection ingot method shown in FIG.

(Specific Example) Lead free-cutting steel was cast by the over-casting ingot method using the apparatus shown in FIG. The casting conditions for this ringing are shown in Table 1, the conditions for adding ultrasonic waves are shown in Table 2, and the results are shown in Table 3.

Table 1 Casting conditions Table 2 Ultrasonic addition conditions Table 3 Casting results As is clear from Table 3, the method of the present invention has the advantage of adding lead particles in steel compared to the conventional method of adding ultrasonic vibration. It was confirmed that the amount of lead particles dissolved in the steel increased and the yield improved, and the distribution of lead particles in the steel became more uniform, improving the homogeneity of the steel ingot.

(Effects of the invention) As described above, the method of the present invention provides molten steel and t added to the molten steel.
Because casting is performed while applying ultrasonic vibration to the mixed part of the lead particles and the molten steel part in which the lead particles have melted, the dissolution of the lead particles into the molten steel is promoted and the lead particle dissolution yield is improved. Moreover, the distribution of grain creep and free-cutting inclusions in the molten steel becomes as uniform as possible, which has the great effect of making it possible to cast lead free-cutting steel of extremely high quality.

[Brief explanation of the drawing]

The drawings are schematic cross-sectional views showing the state in which the method of the present invention is carried out, and FIG. (1) is a ladle, C3) is a prayer type, (4) is an ultrasonic vibrator,
(5) is molten steel, (γ) (8) is a horn, (9) is a lifting device, and 00) is a lead particle. 11 patentees Sumitomo Kinmasu Industries Co., Ltd. Figure 1 Figure 2

Claims (1)

[Claims] (1), Note above (c) In a method of casting lead free-cutting steel by adding fine particles of lead to molten steel being cast into a mold and melting the lead by the Nishita Chuzo method, lif casting is performed by adding ultrasonic vibration to the mixed part of molten steel and lead particles added to the molten steel, and to the molten steel part in which the lead particles have melted.
A casting method for free-cutting lead.