JPH1036934A - Casting cable parts - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a casting cable parts producible by a casting method and excellent in strength and reliability. SOLUTION: An alloy contg. 0.3 to 1.5% Si and one or >= two kinds among 0.1 to 2.0% Cu, 0.2 to 3.0% Mg and 0.3 to 1.0% Mn, furthermore contg. one or two kinds of 0.005 to 0.2%. Ti and 0.0005 to 0.05% B, and the balance Al with inevitable impurities is cast in a mold so as to regulate the casting rate in the gate part of the mold to <=1.0m/sec, and pressurizing is continued under the pressure of >=20MPa till the completion of its solidification.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cast wire part for gripping, retaining, and fixing overhead transmission lines, distribution lines, and the like.

[0002]

2. Description of the Related Art Various kinds of electric wire parts are used in overhead power transmission equipment and power distribution equipment in various states. For example, they are used to hold conductors of high-voltage power transmission lines and hold them to a steel tower or the like. In order to prevent accidents due to corona discharge, loss of transmission power, and the like, the outer shape of the electric wire part is designed and manufactured in a complicated shape having a rounded shape as a whole. If a component having such a complicated shape is to be obtained by machining, the cost of machining is increased. Therefore, a cast product is generally used. Aluminum casting alloys for electric wire parts include
Al with excellent strength, toughness, corrosion resistance, and moderate castability
-Mg-based alloys, some of which are Al-Si-Mg-based alloys for casting, specifically, seven types of castings A (A
A C7A) alloy or a four-type casting (CH4AC) alloy is used, and is cast by a sand-type gravity casting method.

[0003]

The electric wire parts are parts that are handled even at high places, and thus have been demanded to be lighter in weight. However, in recent years, in order to increase the efficiency of transmission capacity, the transmission voltage has to be increased. As the number of conductors increases and the number of conductors increases, the shape of electric wire components becomes larger and more complicated, and the number of components is becoming unavoidable. Such a change in the situation results in an increase in the weight of the electric wire parts, an increase in the load on the tower, and the reinforcement thereof also contributes to an increase in the cost of the tower construction. For the reasons described above, increasing the strength of electric wire components has become an increasingly important issue. To this end, it is desirable to improve the mechanical strength and toughness of the material to increase the strength without impairing the reliability of the component itself. However, according to the conventional technology, there are the following problems. .

The reason why AC7A alloy has been used for cast electric wire parts is that mechanical properties, especially large elongation, can be obtained as compared with other cast alloys. That is, by having a larger elongation, excellent toughness is exhibited, rapid breakage can be avoided, and the reliability as a cast electric wire component is excellent. However, this alloy is 3.5-5.
It contains 5% of Mg, and the molten metal at the time of casting is severely oxidized. By this oxidation, MgO and Al2O3 are generated and combined to form a compound having a spinel type crystal structure. This compound is mixed into the product as a non-metallic inclusion to reduce the mechanical properties of the product and to form a so-called hard spot, which significantly reduces the machinability. Further, the casting method using a sand mold has been conventionally employed because of the low thermal conductivity of the sand mold, which prevents a decrease in the flowability of the molten metal during casting and improves the flow of the molten metal. . But,
The slow solidification rate causes the internal structure of the material to coarsen, increasing the risk of shrinkage cavities and microporosity in the annealed zone, leading to reduced mechanical properties and reduced production yield. There is a problem of doing. In addition, AC4CH has strength, corrosion resistance,
Although it has the feature of being excellent in castability, its elongation is inferior and its improvement is desired.

[0005] As a casting method for increasing the solidification rate, there are a die casting method and a die casting method. However, when the AC7A is cast by these methods, the flowability of the molten metal is remarkably reduced, resulting in poor running of the molten metal. In addition, there are problems such as internal defects such as shrinkage cavities being concentrated on the thick portion, and turbulence of the molten metal being generated, causing many blow holes due to air entrainment. Further, when a material having a large amount of air entrainment is heat-treated, defects such as blisters are generated, so that there is a problem that the heat treatment becomes impossible. In addition, A, which is widely used as a casting alloy,
Al-Cu alloys other than C7A, AC4CH, Al-
Casting materials such as Si-Cu alloys have problems such as low elongation, low reliability, and poor corrosion resistance even if mechanical strength can be obtained, and they are not suitable as materials for cast electric wire parts. In order to solve the above problems, the appearance of a cast electric wire component made of a material having high strength, large elongation and excellent corrosion resistance has been strongly desired and lived.

[0006]

[Means for Solving the Problems] In order to solve the above-mentioned problems, as a result of intensive studies on various aluminum alloys and various casting methods and characteristics of the obtained castings as electric wire components, the results were as follows. As a result, the present inventors have found the relationship between alloying components and casting conditions for obtaining sufficient mechanical properties, particularly excellent toughness (that is, high elongation), and have completed the present invention. That is, the invention of Claim 1 of the present application
~ 1.0%, Cu 0.1 ~ 2.0%, Mg 0.2 ~ 3.
0%, one or more of Mn 0.3 to 1.0%, and further Ti 0.005 to 0.2%, B 0.0005 to B
It is a cast electric wire component containing one or two of 0.05%, and the balance being Al and unavoidable impurities. Next, the invention of claim 2 of the present application is directed to a casting method in which the casting speed in the gate portion of the mold is controlled to 1.0 m / sec or less, the casting is performed in the mold, and the pressure is maintained at a pressure of 20 MPa or more until the solidification is completed. A cast electric wire part comprising the composition according to claim 1.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the reasons for limiting the components of the present invention will be described. Si forms Mg and Mg2Si,
In the process of formation, it forms an intermediate phase and shows age hardening,
Improve strength. However, if the content of Si is less than 0.3%, sufficient strength as a wire component cannot be obtained, and if the content exceeds 1.5%, not only the effect of improving strength is saturated, but also the elongation and toughness of the material are reduced, so that the content is reduced. The amount is 0.3-1.5%. Mg improves the strength together with Si as described above, but if less than 0.2%, the effect of improving the strength is insufficient.
If it exceeds 3.0%, the effect of strength improvement is saturated, the molten metal is oxidized at the time of casting, and the generation of spinel crystal type oxides is increased, and these are present as inclusions inside the material, resulting in mechanical properties. Harms cutting workability. Therefore, the content of Mg is limited to 0.2 to 3.0%.

[0008] The addition of Cu improves the tensile strength and proof stress, but if the addition amount is less than 0.1%, the effect is not remarkable.
If it exceeds 2.0%, the corrosion resistance deteriorates, which is not preferable. Therefore, the content of Cu is set to 0.2 to 2.0%. Mn has an effect of improving strength by forming a solid solution in the material.
If it is less than 3%, the effect is small, and if it exceeds 1.0%, the effect is saturated, a coarse intermetallic compound is easily formed together with other elements, and there is a risk that elongation and fatigue strength are reduced. Is 0.3 to 1.0%.

One or two of Ti and B are added to Ti and B for refining the grain structure. The amounts of Ti and B are less than 0.005% Ti and 0.0005% B, respectively.
If less than 0.3%, the effect is small.
%, The effect of addition saturates, and at the same time, Ti, B
Is likely to be generated, and there is a danger that the mechanical properties are reduced. Therefore, the content of Ti and B is 0.005-0.2% of Ti, and 0.0005-0.0% of B.
5%. If impurities other than those described above are Fe 1.0 or less, and other impurities are 0.5% or less, they are allowed without impairing the effects of the present invention.

Next, the reasons for limiting the casting method and the casting conditions will be described. By using a mold for casting of the electric wire part of the present invention, an excellent product can be obtained as compared with a conventional sand casting. Casting speed (mold gate 1
The casting speed is set at 1.0 m / sec or less (see FIG. 3). If the casting speed exceeds 1.0 m / sec, the molten casting flow becomes turbulent and entrains the air in the mold, which tends to cause casting defects such as burrow holes and shrinkage cavities.
It is desirable from the standpoint of quality that the casting speed be as low as possible, as long as no poor running is caused by a decrease in the temperature of the hot water. However, if the speed is excessively low, the productivity is reduced. Therefore, if it is within the range of the present invention, it may be appropriately determined according to the size and shape of the electric wire part, but it is preferably 0.6 to 0.3 m / sec. .

After the casting, the inside of the mold is continuously pressurized at a pressure of 20 MPa or more until the molten metal in the mold is completely solidified. In the mold, solidification proceeds to form an air gap between the mold and the product part. However, the pressurization delays generation of the air gap and prevents a decrease in solidification speed. As a result of preventing the solidification rate from decreasing, the solidified structure becomes dense and fine, and an effect of improving mechanical properties can be obtained. Further, the solidification shrinkage progresses inside the product part as the solidification progresses. However, since the supply of the molten metal to the shrinkage part is continued by the pressurization, the occurrence of internal defects such as shrinkage cavities can be prevented. Further, the delay in the generation of the air gap due to the pressurization promotes the cooling of the solidified shell in the product part, strengthens the solidified shell, and has the effect of preventing the occurrence of solidification cracks.

[0012] Casting of an alloy having a low Si content, which has conventionally been considered to easily cause casting cracks and poor castability, can be easily performed by applying the pressure of the present invention. S
In an alloy having a low i content, since the amount of eutectic melt of Si having a low melting point is small, the supply of molten metal to the solidification shrinkage portion is insufficient, and solidification cracks are likely to occur. However, according to the method of applying pressure according to the present invention, the occurrence of internal defects and solidification cracks in the casting can be prevented by replenishing the molten metal to the shrinking portion and strengthening the solidified shell.

[0013] Further, the AC7A alloy for casting which has been conventionally used for cast electric wire parts is a non-heat-treated alloy, and the effect of heat treatment was not obtained. However, according to the pressure casting method using a mold according to the present invention, Even if heat treatment is performed after casting, heat treatment is possible without generation of defects such as blisters. Therefore, high strength can be achieved by heat treatment, and a heat-treated cast alloy can be selected. As the heat treatment conditions, ordinary heat treatment conditions may be selected according to the alloy components used. That is, the effect of the pressurization of the present invention enables casting of a low Si-containing alloy, such as that used in wrought materials, which has conventionally been impossible to cast. ,
In addition, it is possible to manufacture a cast electric wire part having a large elongation.

In order to obtain the effect of pressurization of the present invention, 20M
Pressurization of Pa or more is necessary, and if the pressure is less than 20 MPa, the effect of pressurization cannot be sufficiently obtained. As the pressing force increases, the effect of pressurization can be obtained more stably.
Desirably, the pressure is 0 MPa or more. The effect of pressing force is 1
There was a tendency to be almost saturated at 00 MPa,
Pressurization exceeding a increases the burden on the equipment cost of the pressurizing device, so that the effect of pressurization exceeding 100 MPa is not economically effective.

[0015]

The present invention will be described in more detail with reference to examples. In the present embodiment, as an example of a cast wire component, a clamp component for gripping an overhead transmission line shown in FIG. 1 was cast. The shape of the present clamp component has a three-dimensional curved surface in order to prevent corona discharge, and has an uneven thickness with a different thickness depending on a portion. FIG. 2 shows a cross-sectional view of a representative portion of the clamp component of FIG. FIG. 3 is a sectional view schematically showing the structure of the casting machine used. The molten metal is injected into the product part 3 by the plunger 4 so that the molten metal velocity at the gate part 1 becomes 1.0 m / sec or less. Simultaneously with the completion of the injection, the gas vent 6 is closed with the aluminum alloy, and the pressure of the plunger 4 is applied. Pressure is 20MPa until solidification is completed
Pressing is continued as above. The components shown in FIG. 1 were produced using alloys having the compositions shown in Table 1 and by the casting method and casting conditions shown in Table 2. Nos. 1 to 6 in Table 1 all have compositions satisfying the conditions of the present invention, and No. 7 in Comparative Example is Si and Mg.
However, No. 8 is Si and No. 9 is Cu not satisfying the component range of the present invention. The conventional example of No. 11 is an alloy having a composition corresponding to the casting alloy AC7A conventionally used for cast wire parts.

[0016]

[Table 1]

The produced parts were examined for the occurrence of casting defects by a tensile test and an X-ray transmission test. The tensile test was conducted according to JIS 14 from the position shown by the dotted line in FIG.
(A) No. test piece (shape; round bar, total length of test piece; 100 m
m, parallel part diameter 6 mm, parallel part length 40 mm)
The test was performed according to JIS Z2214 (metallic material tensile test method). The X-ray transmission test was performed in accordance with JIS H0522 (radiation transmission test method for aluminum casting and classification method for transmission photograph). As for the mechanical properties, non-defective products were selected from 50 samples obtained under each manufacturing condition, and five test pieces were sampled and subjected to a tensile test, and the results were shown as average values. The X-ray transmission test was performed on all the samples to check the state of occurrence of defects. Yield was determined to be non-defective with no casting defects. Table 2 summarizes the test results described above.

Numbers 11 to 19 shown in Table 2 are obtained by casting using an alloy having the composition of the present invention within a range suitable for the casting method and conditions of the present invention. As is clear from the comparison with the conventional example No. 31 in which the conventional alloy was cast by the conventional method, no defect was observed even after the heat treatment was performed.
As a result, the mechanical properties have been dramatically improved.
On the other hand, Comparative Examples Nos. 21 to 23 are alloys that do not satisfy the composition range of the present invention cast under the casting conditions of the present invention. In No. 21, no casting defect was found due to the casting conditions of the present invention, but the content of Si was small, a sufficient age hardening effect was not obtained, and the yield strength and elongation were poor. Number 2
Samples Nos. 2 and 23 each contain Si and Cu in excess, and have good results in mechanical properties of test pieces that can be subjected to a tensile test, but have low elongation and a remarkable improvement effect as compared with the conventional method. Not obtained. In Comparative Examples Nos. 24 and 25, the alloy composition satisfies the conditions of the present invention, but the casting conditions do not satisfy the conditions of the present invention.
No good product was obtained. Note that the mechanical properties of Nos. 24 and 25 are the results of the fact that casting defects could be avoided only in the test pieces.

[0019]

[Table 2]

[0020]

As described above, according to the present invention,
A cast electric wire component having excellent strength and mechanical properties with large elongation can be obtained, which can contribute to improvement in the strength and reliability of the electric wire component, and thus has a remarkable industrial effect.

[Brief description of the drawings]

FIG. 1 is a view showing an outline of a shape of a clamp component and a test piece sampling position as an example of a cast electric wire component in an embodiment of the present invention, (1) is a side view, and (2) is a bottom view. .

2 is a sectional view of a main part of the clamp component shown in FIG. 1, (1) is a sectional view taken along line AA, (2) is a sectional view taken along line BB,
(3) is a CC sectional view, (4) is a DD sectional view, (5)
Is an EE cross-sectional view.

FIG. 3 is a cross-sectional view schematically showing a mechanism of a pressure casting apparatus used for carrying out the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Gate part 2 Mold 3 Product part 4 Plunger 5 Mold water cooling pipe 6 Gas release part

Claims (2)

[Claims] 1. A method according to claim 1, wherein said alloy contains 0.3 to 1.5% of Si and 0.1 to 0.1% of Cu.
2.0%, Mg 0.2-3.0%, Mn 0.3-1.0
%, One or more of them, and further 0.005 to 0.005%.
A cast electric wire part containing one or two of 0.2% and B 0.0005 to 0.05%, and the balance being Al and unavoidable impurities. 2. A casting method in which a casting speed in a gate portion of a mold is controlled to 1.0 m / sec or less, and casting is performed in the mold, and pressurization is continued at a pressure of 20 MPa or more until solidification is completed. A cast wire component comprising the composition according to claim 1.