JP2948435B2 - Method of forming composite material blade - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a method for forming a composite material blade using a resin injection molding method. The present invention relates to a molding method for accurately transferring a mold cavity surface, preventing the occurrence of fine sink marks on the surface, and obtaining a composite material blade having a highly accurate surface shape.

[0002]

2. Description of the Related Art Blades such as propeller blades for aircraft, turbofan blades, helicopter blades, and general industrial rotor blades are sometimes made of composite materials such as FRP instead of conventional metals. In the method of molding a composite material blade, generally, a blade insert having reinforcing fibers attached to the surface is inserted between a mold for molding the abdominal surface of the blade and a mold for molding the back surface, and the mold is squeezed, and a thermosetting resin is formed. A resin injection molding method is employed in which excess resin is allowed to flow out of an outlet while being injected, and then heated to a required temperature or further maintained for a required time to solidify and mold the resin.

[0003]

In the conventional molding method,
Since the volume of the resin is the same at the end of the resin injection and at the time the resin cures and shrinks, when the cure shrinkage occurs, the surface of the molded product separates from the mold cavity, so the cavity surface can be transferred. However, there was a problem that fine sink marks occurred on the surface and the appearance deteriorated.

[0004] The present invention relates to a method of forming a composite material blade using a resin injection molding method, wherein a mold cavity surface is accurately transferred to prevent the occurrence of fine sink marks on the surface, thereby achieving a highly accurate surface shape. It is an object of the present invention to provide a forming method for obtaining a composite material blade having the following.

[0005]

SUMMARY OF THE INVENTION According to the present invention, a blade insert having reinforcing fibers attached to the surface thereof is inserted between a mold for molding the abdominal surface of the blade and a mold for molding the back surface thereof, and the mold is squeezed and heat-cured. In a method of forming a composite material blade using a resin injection molding method in which a reactive resin is injected and then solidified, a sealant is sandwiched between the mating surfaces of the abdominal surface type and the back type with a sealant interposed therebetween, and excess resin is discharged while injecting the resin. This is a method of forming a composite material blade, characterized in that the resin is discharged from an outlet, the mold is loosened, the resin is further injected, the resin is hardened after the injection is stopped, and the mold is clamped.

Specifically, the following steps are characterized. 1) The mold is clamped with a sealant between the mating surfaces of the abdominal surface type and the back type to cure. 2) Load the blade insert and tighten the mold. 3) The thermosetting resin kept at the same temperature as the mold is injected into the mold and overflows from the outlet. 4) Loosen the mold clamping by about 0.1 mm to 0.5 mm in terms of gap. 5) Inject resin further. 6) Stop the injection and cure the resin. 7) The mold is slowly re-closed at the timing including the time when the pressure of the resin in the mold starts to decrease. 8) Cure.

[0007]

The operation of the method for forming a composite material blade according to the present invention will be described in detail with reference to the drawings. FIGS. 1A and 1B are cross-sectional views of a molding die showing steps of a method for molding a composite material blade according to the present invention. FIG. 2 is a perspective explanatory view of a molding die showing steps of a method for molding a composite material blade according to the present invention. A resin injection port 2 and a discharge port 3 are provided in a molding die 1 of the molding apparatus. The resin injection port 2 is connected to an injection pipe from a resin pressure feeding tank, and the discharge port 3 is connected to a resin reservoir via a conduit. It is configured to be connected to a container.

First, an appropriate amount of a silicone sealant 4 is applied to the mating surfaces of the molds 1a and 1b, covered with a Teflon film, and the molding mold 1 is tightened and cured. The mold 1 is opened, the Teflon film is removed, the blade insert 10 covered with the reinforcing fiber 11 is mounted in the cavity 1c, and the mold 1 is closed with a specified torque. The resin is prepared by mixing a curing agent with the base material, placing the mixture in a pressure feed tank, and maintaining the same temperature as the mold. At the time of molding, the piston of the resin pressure feeding tank is pushed down, and the resin in the tank is injected into the molding die 1 from the injection port 2 via the injection pipe. The resin flows through the gap between the wall of the cavity 1c and the blade insert 10,
Since the gap is filled with the reinforcing fibers 11, the reinforcing fibers 11
Flows slowly to penetrate

At the time of the resin pressure feeding, the mold clamping is loosened by about 0.1 mm in terms of a gap, the injection is continued, and the volume increment caused by the loosening of the mold clamping is filled with the resin (see FIG. 1A). Next, the injection is stopped, the injection port 2 is closed, and the discharge port 3 is kept open, and the temperature is raised to the curing temperature and held. The mold clamping is slowly advanced in time with the timing at which the resin in the discharge pipe is sucked into the mold, and finally the mold is clamped to a proper position as shown in FIG. 1B, and then the resin is cured. .

In the present invention, the silicone sealant 4 interposed between the mating surfaces of the molds fills gaps formed in the mating surfaces when the mold is loosened, thereby preventing the resin from flowing preferentially there. In addition, impregnation of the resin into the blade insert has a difficult problem such as residual air bubbles. Therefore, impregnation is first completed in a state where the blade insert is closed at a regular position, thereby preventing generation of defects. In addition, the resin is pre-mixed with a curing agent and heated and held in the pressure feed tank until the temperature becomes the same as that of the mold. It covers the whole area.
By slowly tightening the mold, the resin whose viscosity has increased is caused to flow without generating a large reaction force, thereby discharging excess resin. Therefore, by loosening the mold during the resin injection process and introducing the resin injection process further, the volume increase caused by the loose mold can be filled with the resin, and the mold cavity surface can be accurately measured. The composite material blade having a highly accurate surface shape can be obtained by preventing the occurrence of fine sink marks on the surface.

[0011]

EXAMPLE Using a molding apparatus according to the present invention described above and shown in FIG. 2, a composite material blade was molded using carbon fiber as the reinforcing fiber and epoxy resin as the resin. At this time, the cavity surface of the mold is mirror-finished in advance,
After loosening the mold in the process of injecting the resin, inject more resin, fill the volume increase caused by loosening of the mold with the resin, tighten the mold slowly, then cure the resin Was. It was confirmed that the composite material blade which had been formed had no fine sink marks on its surface layer, and that the surface shape was formed with the same precision as mirror finish.

[0012]

According to the present invention, a blade insert having reinforcing fibers attached to the surface is inserted between a mold for molding the abdominal surface of the blade and a mold for molding the back surface, the mold is squeezed, and a thermosetting resin is injected. Then, in the method of molding a composite material blade using the resin injection molding method of solidifying, the mold is clamped with a sealant between the mating surface of the abdominal mold and the back mold, and the mold is loosened during the resin injection process. In addition, resin can be injected and resin can be replenished to the fine sink marks on the blade molded product surface, so good mold transferability can be obtained.If the inner surface of the mold is finished to a beautiful mirror surface, the surface of the molded product will follow this There is an advantage that it is possible to obtain a composite material blade having a highly accurate surface shape.

[Brief description of the drawings]

FIGS. 1A and 1B are cross-sectional explanatory views of a molding die showing steps of a method for molding a composite material blade according to the present invention.

FIG. 2 is a perspective explanatory view of a molding die showing steps of a method of molding a composite material blade according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Mold 1a, 1b Mold 1c Cavity 2 Inlet 3 Outlet 4 Silicon sealant 10 Blade insert 11 Reinforcing fiber

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B64C 11/20 B64C 3/24

Claims (1)

(57) [Claims] 1. A blade insert having reinforcing fibers attached to the surface thereof is inserted between a mold for molding the abdominal surface of the blade and a mold for molding the back surface, the mold is squeezed, and the thermosetting resin is injected and solidified. In the molding method of the composite material blade using the resin injection molding method, the mold is clamped with a sealant interposed between the mating surfaces of the abdominal mold and the back mold, and excess resin is allowed to flow out from the discharge port while injecting the resin, and then the mold is formed. A method of molding a composite material blade, in which the resin is further poured after loosening the resin, and after the injection is stopped, the resin is cured and the mold is clamped.