JPH02247353A - Mold for end plate and fly wheel made of high strength cast iron - Google Patents

Abstract

PURPOSE:To combinedly provide the mold and fly wheel with high strength and internal soundness by subjecting them to casting with cast iron having specified contents of C, Ti, Si, Mg and Mn and specified spheroidal graphite rate. CONSTITUTION:A mold for an end plate and a fly wheel are cast by using high strength cast iron having the compsn. constituted of, by weight, 4.0 to 4.3% C, <=0.07% Ti, 0.8 to 1.5% Si, 0.015 to 0.035% Mg, 0.35 to 0.80% Mn and the balance substantial Fe and having 20 to 70% spheroidal graphite rate. In this way, the mold for an end plate is combinedly provided with wear resistance, seizure resistance and economical efficiency. On the other hand, in the fly wheel, high strength and internal soundness can be secured and excellent rotating balance can easily be obtd. as well.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a mold for a cast iron mirror plate and a flywheel.

(Prior art and problems to be solved) The material properties required for a mold for a head plate mainly include wear resistance, seizure resistance, and economic efficiency.
It is formed by C.

However, FC materials are low cost, have good seizure resistance due to crystallized graphite, and do not have high strength.
Since the amount of graphite that contributes to sliding performance is not large, there is a problem of insufficient wear resistance.

On the other hand, 345C has high strength and good wear resistance, but it has the disadvantage of high cost because it requires Cr plating on the surface to ensure seizure resistance.

In addition, flywheels are conventionally formed by casting with FC20 to 25, but when the wall thickness exceeds 300 mm, the difference in solidification time between the outer periphery and the center becomes large, and casting defects such as cavities occur inside the flywheel. It becomes more likely to occur. For this reason, it tends to be difficult to adjust the balance of the rotating body. In order to prevent casting defects, high C, E, and OFC materials may be used, but this results in insufficient strength as a high-speed rotating body.

The present invention was created in view of these problems, and provides a cast iron head plate mold that is excellent in seizure resistance, economical efficiency, and wear resistance, and has higher strength and internal soundness than conventional FC materials. The purpose is to provide a cast iron flywheel with a high quality.

(Means for Solving the Problems) The head plate mold and flywheel of the present invention, which have been made to achieve the above objects, have a chemical composition in weight percent of C: 4.0 to 4.3%, Ti: 0. .07% or lessS
i: 0.8-1.5%, g: 0.015-0.
035%Mn: 0.35 to 0.80%, the remainder substantially consists of Fe, and the graphite nodularity is 20 to 70%.
% of high-strength cast iron.

(Function) The reasons for limiting the components (unit weight %) of the cast iron material for casting the mirror plate mold and flywheel of the present invention and the graphite nodularity rate are shown below.

C: 4.0 to 4.3% C is necessary for graphite crystallization and pearlite formation of the base, and if it is less than 4.0%, the amount of expansion due to graphitization is insufficient,
It becomes difficult to ensure the internal integrity of the cast product. On the other hand, 4.
If it exceeds 3%, graphite becomes excessive and becomes 30kgf/mm.”
Not only is it difficult to secure the above strength, but also the amount of dross increases.

Si: 0.8 to 1.5% Si is an element that promotes graphitization and also has the effect of making the matrix uniform. If it is less than 0.8%, no effective effect can be expected, while if it exceeds 1.5%, strength will be insufficient compared to 0%, and the amount of dross will also increase.

Mn: 0.35-0.8% Mn is a base pearlite stabilizing element, and 0.35%
If it is less than that, no effective effect can be expected. On the other hand, if it is 0.8% or more, the effect is sufficient and it becomes economically disadvantageous.

Ti: 0.07% or less Ti is an element that inhibits the spheroidization of graphite.
Compounds such as TiN are generated in the base, leading to deterioration of strength.

Mg: 0.015-0.035% Mg is a graphite nodularizing element, and if it is less than 0.015%,
If a predetermined spheroidization rate cannot be obtained, and on the other hand, it exceeds 0.035%, graphite will become spheroidized and thermal deformability will increase.

Moreover, dross such as MgC and MgO increases.

In addition to the above-mentioned components, the high-strength cast iron according to the present invention contains Cr,
It is formed of impurities such as V, AI, Sn, Pb, and Ni, and the balance is Fe. In addition, since P and S make the material brittle, it is preferable to have as little as possible; P: 0.15% or less, S: 0.
It is best to keep it below 0.01%.

Further, the high-strength cast iron has a graphite nodularity rate of 20 to 70%. If it is less than 20%, spheroidization will be insufficient and a large amount of flaky graphite will be present, making it difficult to secure a tensile strength of 30 kgf/mm or more. On the other hand, if it exceeds 70%, the graphite will become almost spherical and will have a caterpillar-like graphite shape. Growth is 7 due to lack of
% or more, which is excessive and thermal deformation becomes large, which is not preferable.

In addition, when used as a mold material for a mirror plate, it is better to promote the production of pearlite and increase the amount of pearlite and therefore Fe5Cl to further improve wear resistance.
i: 0.8-1.2%, Mn: 0.5-0.8
%, and the spheroidization rate is preferably about 50% or more.

(Example) High-strength cast iron for casting head plate molds and flywheels of the present invention is produced by adding an Mg-based nodularizing agent, such as FeFe-5t-, Fe-5tFe-5t- (rare earth element), to blast furnace hot metal. It can be easily obtained by adding Regarding the addition of the spheroidizing agent, the injection method, plunger method, and pressure addition method are mainly applied. In addition, in order to adjust the graphite shape, spheroidization rate, and base structure, Fe
-5i series and Fe-Ca5i-Ba series inoculants. The most common method of inoculation is tondock weir inoculation, but ladle inoculation is also used in some cases.

Next, specific examples are listed.

A Flywheel manufacturing example (1) JIS molten cast iron with the chemical composition shown in Table 1
G5502, No. B and No. 0 test materials were sand cast.

The casting temperature was 1270°C.

Table 1 (2) JIS Z2201.4 from the bottom of No. C sample material
A No. 1 test piece was taken and subjected to a tensile test, etc. The results are shown below.

Tensile strength -39.5kgf/n+o+" elongation...
-4.05% Hardness...HB168 In addition, the metal structure at the bottom of the No. B sample material (100x magnification) was observed using an optical microscope. The results are shown in FIG. From the same figure, a structure in which spherical or caterpillar-shaped graphite crystallizes in the pearlite base and ferrite is formed around it can be observed. In addition, spheroidization has not progressed much, and the spheroidization rate is 50.
%.

(3) Using the molten cast iron shown in Table 1, a short cylindrical flywheel having an outer diameter of 2182 mm, an inner diameter of 410 m, and a wall thickness of 435 mm was sand-cast at 1270°C. After demolding, a product was obtained by machining. There were almost no casting defects such as cavities in the thick center of the product, and a good rotational balance was obtained. In addition, the strength was 30 kgf/mm'' or more, which was sufficient.

B Manufacturing example of a mold for head plate (1) JIS molten cast iron having the chemical composition shown in Table 2
G5502, No. B and No. 0 test materials were sand cast. The casting temperature was 1270°C.

Table 2 (Note) Unit -1%, remainder substantially Fe (2) A JIS Z2201.4 test piece was taken from the bottom of the No. C sample material and subjected to a tensile test, etc. The results are shown below.

Tensile strength: -50.6 kgf/mm2 Elongation: 4.40% Hardness: HB193 In addition, the metallographic structure (100 times magnification) of the lower part of the No. B specimen is shown in Figure 2. From the figure, it can be seen that, compared to FIG. 1, graphite spheroidization and base pearlite formation are promoted, and the formation of ferrite around graphite is suppressed. The spheroidization rate was determined to be 70%.

(3) Using the molten cast iron shown in Table 2, a roughly short cylindrical end plate mold having a maximum outer diameter of 2840 I [1 ffl, an inner diameter of 1835 mm, and a maximum wall thickness of 240 mm] was sand cast at 1270°C. After demolding, a product was obtained by machining. When the end plate was press-formed by setting it in a press machine, good results were obtained, with no seizure occurring and good wear resistance.

(Effects of the Invention) As explained above, the head plate mold and flywheel of the present invention have a graphite nodularity of 20 to 70% and are made of high C cast iron material. The flywheel has wear resistance, seizure resistance, and economy, while ensuring high strength and internal soundness, and as a result, an excellent rotational balance can be easily obtained.

[Brief explanation of drawings]

FIG. 1 shows a metallographic structure of high-strength cast iron as a material for a flywheel according to an embodiment, and FIG. 2 shows a metallographic structure of high-strength cast iron as a material for a head plate mold in an embodiment. Patent applicant: Kubota Iron Works Co., Ltd. Figure 2

Claims (2)

[Claims] (1) Chemical composition in weight percent: C: 4.0 to 4.3%, Ti: 0.07% or less, Si: 0
．． 8-1.5%, Mg: 0.015-0.035%Mn
:0.35~0.80% The remainder is substantially composed of Fe, and the graphite nodularity is 20~70%.
% cast iron mirror plate mold. (2) A high-strength cast iron flywheel characterized by being cast from the high-strength cast iron of claim (1).