JPS6016332B2 - Thick-walled cylindrical molding method for composite materials - Google Patents

Description

Detailed Description of the Invention The present invention involves impregnating fibers serving as reinforcing materials with a base material to form a composite material using a filament winding method, and using this composite material to mold a thick-walled cylinder such as a rotating body. This relates to a method for forming thick-walled cylinders of composite materials.

To form a cylindrical body using a composite material using the filament winding method, first, the reinforcing material such as glass fiber or carbon fiber is impregnated with the base material such as resin or metal in a molten state, and then the cylindrical body is wound around a mandrel. The molten base material is heated at a constant temperature in a heating tank to harden it. The reason why the base material is in a molten state is to make it easier to impregnate the reinforcing fibers, to enable uniform winding, and to achieve a uniform workable structure. However, when forming composite cylinders by the filament winding method, the cylinder has a very small inner-to-exterior ratio, for example, most of the cylinders have a thin wall of about 1.1 in outer diameter/inner ridge.

This is due to the lack of thick-walled cylindrical molding technology, and demand is mainly for thin-walled products such as pipes. However, in recent years, in order to effectively apply the high specific strength of composite materials to rotating bodies, it has been desired to establish a method of forming thick cylinders. However, when thick-walled cylinders are formed using the same method used to form conventional pipes, cracks occur during forming and the cylinder becomes unusable.Even if there are no apparent cracks, the residual stress is extremely large. , lowering the tolerance value. Generally, polymeric materials are cured by adding a curing agent from their molten state to become solid.

There are two types of curing: those that harden at high temperatures and those that harden at room temperature, but 11 shrinkage occurs as a result of the curing reaction. Furthermore, the high-temperature type has a large coefficient of thermal expansion, so this contraction is added to it. FIG. 1 schematically shows the volume change of the polymer during the curing reaction. therefore,
Residual stress due to shrinkage during this curing reaction causes cracking during molding, which has become a problem. For example, molding cracks in metal inserts of plastic parts are a typical example, and there are many other accidents as well. On the other hand, when a polymeric material is used as a resin matrix in a composite material, the same kind of phenomenon also occurs. In the thick cylinder A produced by the filament winding method in which fibers are oriented only in the circumferential direction, a residual stress distribution after molding as shown in FIG. 2 occurs. In other words, the stress in the circumferential direction oe is tensile at the inner circumference, compressive at the outer circumference, and the stress is in the radial direction. Regarding r, the maximum tension is approximately at the center of the cylinder A. On the other hand, if the inside-outside ratio is increased, the maximum stress in both directions will naturally increase.
In such a thick-walled cylinder, the circumferential direction is reinforced with fibers, so no fracture will occur, but the fibers have no effect in the radial direction, so the critical stress is easily reached, and the concentric rings This will cause cracks. If such defects exist, the reliability of strength and rotational stability will be extremely poor, so there is a desire to develop a thick-walled cylinder forming technique that eliminates these problems. For this reason, in the past, in order to create a thick-walled cylinder without cracks, thin-walled cylinders B with a small inside-outside diameter ratio were stacked on top of each other, as shown in Figure 3, but this had the disadvantage of requiring a great deal of labor and time. Ta. SUMMARY OF THE INVENTION An object of the present invention is to provide a method for forming a thick-walled composite cylinder with excellent strength reliability and rotational stability.
The feature of the present invention is that a reinforcing fiber such as glass fiber or carbon fiber is impregnated with base material such as resin or metal in a molten state using a filament winding molding machine, and this is wound around a mandrel to create a cylindrical body of composite material. In the process of curing this with a curing means, a load is applied from the thickness direction of the cylindrical body to cause the cylindrical body to shrink in the thickness direction, and after curing, this load is removed to form a thick-walled cylinder. be.

When curing a cylindrical body using the filament winding method, the difference between the amount of contraction in the radial direction and the amount of contraction in the circumferential direction causes strain, which causes clutches during the curing process. In particular, radial shrinkage has a large effect on cracks. By molding as in the present invention, shrinkage after curing is mechanically removed, resulting in a thick-walled composite cylinder that does not generate residual stress or crack, has excellent strength reliability, and rotational stability. can be molded.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 4 shows a jig for filament winding used in the thick-walled cylinder forming method of the present invention.

1 is a mandrel, and reinforcing fibers 2 are wound around this and molded.

Reference numeral 3 designates a guide plate for the purpose of adjusting the shape and preventing the matrix from flowing out, and a template agent is applied to the surface of the guide plate for removal after molding and hardening.

This jig is attached to a rotating machine, the reinforcing fibers 2 are impregnated with the matrix under appropriate tension, and the thick-walled cylinder 4 is wound continuously from the inner circumference to the outer circumference of the guide plate 3 in one pass. Shape. When this is heated and hardened, residual stress as shown in FIG. 2 is generated, and cracks occur particularly due to the radial component. All of these are caused by shrinkage, and if this shrinkage is removed in some way during the curing process, not only will cracking during molding not occur, but it will also be directed in a direction that produces beneficial compressive residual stress. You can take it with you. This removal method will be explained only when the cylinder is thick-walled and has a small thickness in the axial direction, particularly when used in a rotor or the like. It is impossible to remove this within a circular plane. Therefore, if the thick-walled cylinder 4 is compressed from the thickness direction with a uniform force P as shown in FIG. 5a, the radius of the thick-walled cylinder 4 will be as shown in FIG. 5b. In this direction, if the elastic modulus in the thickness direction is Ez, and Poisson's ratio is Z, then a reed-like strain is produced. That is, it tends to expand in the radial direction. By curing in this state, even if the external force P is removed after curing, the residual stress in the radial direction can be reduced by adjusting the initial force P setting. Further, if the amount of curing shrinkage and the amount of thermal shrinkage are determined and the resulting strain value and distribution are known, the magnitude and distribution of the external force P can also be determined. FIG. 6 shows an example of a method for curing a thick-walled cylinder without causing mold cracks using the filament winding method.

In this example, a rotor formed by the filament winding method will be explained. In this diagram,
Components with the same symbols as in FIG. 4 are the same parts. 5 is a constant temperature bath that provides constant temperature conditions for heating and curing.

A load 6 is applied to the thick cylinder 4 via the guide plate 3,
Apply pressure. Hydraulic pressure may be used as this pressurizing means,
Other methods can also be used. The pressurized guide plate 3 is supported on a table 8 via a bearing 7 and is hardened while being rotated by a motor 101 via a gear 9.
Although FIG. 6 shows a horizontal type, a vertical type is better when uniformity of the structure in the thickness direction is required. in this way,
A thick cylinder 4 made of reinforcing fiber impregnated with a base material such as a molten resin is contracted in the thickness direction during the curing process, and when cured in this state, the thickness direction of the thick cylinder 4 after hardening is shrinkage can be eliminated. This makes it possible to create a thick-walled cylinder without cracking during molding. Furthermore, a thick cylinder without cracks can be formed in an extremely short time. For example, when comparing the inner diameter of 30th and the outer diameter of 3000, the time can be reduced to about 1/49th of a base degree.

Furthermore, since a new surface can be produced only by finishing work, it is advantageous in terms of material when compared to a thick cylinder made by laminating thin films, which is finished each time by cutting. As explained above, according to the present invention, it is possible to mold a thick-walled composite cylinder having extremely high reliability in strength and stability in rotation.

[Brief explanation of drawings]

Figure 1 is a schematic diagram of shrinkage due to hardening of a polymer material, Figure 2 is a diagram illustrating the residual stress distribution after forming a thick-walled cylinder,
FIG. 3 is a front view showing a multilayer thick-walled cylinder formed by laminating thin-walled subordinate cylinders, FIG. 4 is a vertical side view showing a filament winding jig used in the method of the present invention, and FIGS. b is a diagram for explaining the deformation of a thick-walled cylinder due to a load in an enemy direction according to the method of the present invention, and FIG. 6 is a diagram showing a specific example of the method of the present invention. 1... Mandrel, 2... Reinforced fiber, 3...
...Guide plate, 4... Thick-walled cylinder, 5... Constant temperature chamber, 6... Load, 9... Gear, 10... Motor. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] 1 A composite is formed by impregnating the reinforcing fibers with a molten base material using the filament winding method, the composite is wound to form a cylinder, and in the process of hardening the cylinder, By applying a uniform load from the thickness direction, the cylindrical body is contracted in the thickness direction, and after hardening,
A method for forming a thick-walled cylinder of a composite material, characterized in that the thick-walled cylinder is formed by removing this load.