JPH0826421B2 - Method for producing tubular fiber-reinforced metal composite material - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a tubular fiber-reinforced metal composite material (FRM) containing carbon fibers as reinforcing fibers by a high pressure casting method.
To a method of manufacturing.

(Prior Art) There are various methods for manufacturing a cylindrical FRM, and one of them is a high pressure casting method. In this method, an aggregate of reinforcing fibers is placed around a core, placed in a mold, a molten metal of a matrix is poured into the mold, and a plunger is pressed to impregnate the aggregate and solidify it. After that, the mold is removed.

By the way, when it is desired to develop strength and elastic modulus in the longitudinal direction in the FRM by such a method, the aggregate should be prepared so that all or part of the reinforcing fibers are in the axial direction of the core. Deploy. However, when the aggregate is composed of carbon fibers or partially contains carbon fibers, the coefficient of thermal expansion of carbon fibers is almost zero or negative. The heat shrinkage in the axial direction of the fiber, that is, in the axial direction of the core becomes significantly smaller than that of the core and the mold, and the core or mold receives compressive stress and is broken, or even if not broken. The problem often occurs.

(Problems to be Solved by the Invention) An object of the present invention is to solve the above-mentioned problems of the conventional method and to prevent breakage or cracking during cooling, which is a tubular fiber-reinforced metal. A method of manufacturing a composite material is provided.

(Means for Solving the Problems) In order to achieve the above object, in the present invention, the tensile modulus of elasticity is at least 26 tons / mm around the core.
² , and the tensile elongation at break is 1.0% or more, and further, a reinforcing fiber assembly containing at least carbon fibers oriented so that the fiber axis is in the axial direction of the core is arranged in a mold. A method for producing a tubular fiber-reinforced metal composite material is provided, which comprises pouring a molten metal of a metal serving as a matrix into the mold, pressurizing the molten metal to impregnate the aggregate and solidify the aggregate.

In the present invention, the term “cylindrical” means a hollow shape whose length is considerably longer than its radius. The cross-sectional shape is usually circular, but is not limited to this, and other shapes such as a quadrangle or an ellipse may be used.

In addition, in the present invention, the fact that the carbon fiber has its fiber axis in the axial direction of the core means that the fiber axis is not limited to the case where the fiber axis is correctly aligned with the axis of the core. It also includes the case where the angle is within ± 20 ° with respect to the child axis. That is, if it is within the range of ± 20 °, it can be said that the carbon fiber is substantially in the axial direction of the core.

To explain the present invention in more detail, in the present invention, the aggregate of reinforcing fibers always contains carbon fibers, but as the carbon fibers whose fiber axis is in the axial direction of the core, the tensile elastic modulus is 26 Use tons / mm ² or more. Carbon fibers with a tensile modulus of less than 26 ton / mm ² have low rigidity, so they tend to buckle when impregnated with the molten metal of the matrix, and the orientation of carbon atoms in the mesh plane is sufficiently advanced. Therefore, especially when an aluminum alloy is used as a matrix, a reaction with aluminum is likely to occur.

Further, in the present invention, carbon fibers having a tensile elongation at break of 1.0% or more are selected and used as the carbon fibers whose fiber axes are in the axial direction of the core. When carbon fiber having a tensile elongation at break of less than 1.0% is used, when FRM is manufactured and then cooled, F
The RM is subject to compressive stress due to the thermal contraction of the core and the die, causing it to break or crack. Tensile elongation at break
When the carbon fiber is used in an amount of at least%, such carbon fiber is relatively flexible and absorbs the above-mentioned stress well, so that it becomes possible to prevent breakage and cracking. In the case of a tubular shape, the wall thickness is generally thin, and since the compressive stress is applied from both the mold and the core during the cooling process, the above-mentioned breakage or cracking is likely to occur. In addition to having a considerable thickness, since the core is not used, compressive stress is received only from the mold,
Destruction and cracks are of little concern.

The aggregate containing at least such carbon fibers is such that the fibers are aligned in one direction and bound with a binder such as carbon or silica as necessary to give shape retention.

However, the aggregate may include carbon fibers oriented in a direction other than the axial direction of the core. The carbon fibers oriented in such a direction may be of any type, and need not have a tensile modulus of at least 26 ton / mm ² and a tensile elongation at break of 1.0% or more. Further, the aggregate may include other reinforcing fibers other than carbon fibers, such as boron fibers, silicon carbide fibers, and alumina fibers, which have an arbitrary orientation direction according to the purpose of use. For example,
In addition to the above-mentioned carbon fiber whose fiber axis is in the axial direction of the core, a continuous fiber or a woven fabric of carbon fiber or other reinforcing fiber may be wound around the outside thereof. The aggregate should have a tensile modulus of at least 26 ton / mm
² , the tensile elongation at break is 1.0% or more, and the carbon fiber may include the carbon fiber whose axis is in the axial direction of the core.

As the core, elemental metals such as iron, copper, nickel, aluminum and titanium, and at least one of these elemental metals
An alloy containing seeds as the main component is used.

The metal serving as a matrix is a simple metal that is usually used as a matrix metal for FRM, such as aluminum, magnesium, tin, lead, or zinc, or an alloy containing at least one of such simple metal as a main component. Is like.

Now, in the present invention, the above-mentioned aggregate is placed around a core and placed in a mold, a molten metal of a metal serving as a matrix is poured into the mold, and the molten metal is pressurized to impregnate the aggregate and solidify. And remove the mold to obtain FRM.

To explain the present invention in more detail with reference to the drawings,
The drawings show how a cylindrical FRM is manufactured by the method of the present invention, in which a reinforcing fiber aggregate 2 is arranged around a round rod-shaped core 1 and is arranged in a mold 3. . The aggregate 2 has a tensile modulus of elasticity of at least 26 tons / mm ² and a tensile elongation at break of 1.0% or more at the portion contacting the core 1, and the fiber axis is in the axial direction of the core 1. The fiber 4 is formed, and the portion on the outer side thereof is formed of the carbon fiber 5 having an orientation direction according to the application.

Now, the FRM is manufactured by pouring a molten metal 6 serving as a matrix into a mold 3, pressurizing it with a plunger 7 to impregnate the aggregate 2 and solidifying it. After the molten metal 6 is solidified and cooled, that is, after the FRM is obtained, the mold 3 and the table 8 are separated, and the FRM is inserted into the mold 3 together with the core 1.
Take out from. Then, the core 1 is removed. Then
A tubular FRM is obtained.

(Example) Carbon fiber "Torayca" M30 manufactured by Toray Industries, Inc. (tensile elastic modulus: 30 ton / m) around an iron core having a diameter of 25 mm and a length of 1000 mm.
m ² , tensile elongation at break: 1.3%) so that the fiber axis is in the axial direction of the core and the thickness is 1 mm, and then the carbon fiber “Torayca The flat woven fabric CB6144 of "" was wound so that the warp was in the circumferential direction of the core and the thickness was 1 mm to form an assembly, which was put in a mold as shown in the drawing.

Next, after preheating the mold to 550 ° C, a molten metal of aluminum-silicon alloy (JIS AC4C) (temperature: 750
(° C.), And the assembly was impregnated by applying a pressure of 500 kg / cm ^{2 with} a plunger.

After the molten metal solidifies and cools, the mold and stand are separated and FR
When M was taken out together with the core and the core was pressed with a hydraulic press, a cylindrical FRM with no compression cracks was obtained.

(Comparative Example) Except that the carbon fiber oriented in the axial direction of the core was replaced with the carbon fiber "Torayca" M40 (tensile modulus: 40 ton / mm ² , tensile elongation at break: 0.6%) manufactured by Toray Industries, Inc. Similar to the example,
A tubular FRM was obtained.

When the FRM was observed with the naked eye, compression cracks extending in the direction of about 45 ° to the fiber axis of the carbon fiber were found everywhere in the part where the fiber axis of the carbon fiber was in the axial direction of the core. I was accepted.

(Effects of the Invention) The present invention provides a carbon fiber having a tensile modulus of at least 26 ton / mm ² and a tensile elongation at break as a carbon fiber whose fiber axis is in the axial direction of a core of an aggregate of reinforcing fibers containing carbon fiber. Is 1.0%
Since the above-mentioned materials are used, as shown in the embodiment, it is possible to prevent compression fracture and compression cracking during cooling, and a cylindrical FR having excellent strength and elastic modulus in the longitudinal direction.
You will be able to get M.

[Brief description of drawings]

FIG. 1 is a schematic partial sectional front view showing how the method of the present invention is carried out. 1: Core 2: Aggregate of reinforcing fibers 3: Mold 4: Carbon fiber whose fiber axis is in the axial direction of the core 5: Carbon fiber with an orientation direction according to the application etc. 6: Molten metal 7: Plan Jar 8: stand

Claims (1)

[Claims] 1. A tensile modulus of elasticity of at least 26 around the core.
Ton / mm ² , and the tensile elongation at break is 1.0% or more,
Moreover, a reinforcing fiber assembly containing at least carbon fibers oriented such that the fiber axis is in the axial direction of the core is placed in a mold, and the melt serving as a matrix is poured into the mold, and the melt is A method for producing a tubular fiber-reinforced metal composite material, which comprises pressurizing to impregnate the aggregate and solidify the aggregate.