JPS6374628A - Manufacture of fiber reiforced plastic rocket motor case - Google Patents

Abstract

PURPOSE:To make it possible to set an ignition device and a nozzle at their required positions by a method wherein irregularities are provided at parts, at which mouth pieces are in contact with both ends of fiber reinforced plastic (FRP) so as to mold integrally with FRP. CONSTITUTION:The slippage between mouth pieces and FRP is prevented from occurring by providing irregularities at positions, at which the outer peripheries of the mouth pieces 1 contact FRP. The formation of the irregularities is done by providing grooves 3 peripherally and continuously at parts, at which the outer peripheries of the mouth pieces contact FRP. The preferable form of the groove is a circular arc or a triangle. In the above-mentioned grooves, a fiber wound by the filament winding method tends to easily enter the whole groove, resulting in allowing to stop the rotation even by the small groove. Because the carbon fiber reinforced plastic (CFRP) rocket motor case main body and the mouth piece parts are mechanically bonded and no slippage occurs between the case main body and the mouth piece parts, correct positions of various jigs can be kept, even when the jigs are attached on the mouth pieces in the above-mentioned CFRP rocket motor case.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method of manufacturing a rocket motor case made of HFRP.

(Prior Art) A rocket motor case is a pressure vessel for loading rocket motor propellant, and in the past, it was mostly made of metal. However, in recent years, with the development of high-strength reinforcing fibers, FRP ( N1 fiber-reinforced composite material) is now attracting attention.

Rocket motors, for example, have a cylindrical rocket motor case with a lining made of heat-resistant rubber or the like on the inner surface.
A propellant in the form of L and VC slurry is injected and hardened at a predetermined temperature at a predetermined time, and an ignition device and nozzle are also provided.

Therefore, when attaching an ignition device or nozzle to an FRP rocket motor case, it was necessary to attach metal caps to both ends of the motor case. There was a method of attaching this metal base to the FRP motor case using screws, but in order to obtain sufficient connection strength, VC
, which was undesirable because it became heavy. For this reason, FR
As a method of attaching the caps to both ends of the Pg rocket motor case, there has been a method of molding the caps and the FRP main body.

(Problem to be solved by the invention) However, the FRP used on the metal cap and heat-curing resin
When molded in one piece, due to the difference in expansion coefficient between metal and FRP, a gap will be created between the contact surface of the cap and FRP after molding, and the cap will move when setting the ignition device, nozzle, etc. There were problems such as not being able to set it in the correct position, and cracks forming in the lining material inside the rocket motor case.

(Means for solving all the problems) and (Operation) This invention was made by paying attention to such conventional problems, and in an FRP rocket motor case with metal caps attached at both ends, The objective is to solve the conventional problems by providing unevenness on the parts of the base that contact both ends of the FRP and molding it integrally with the FRP.

The present invention will be explained below.

In the method for manufacturing a rocket motor case of the present invention, FR
P (M fiber reinforced composite material) is a material made by hardening reinforced fibers with resin. Examples of reinforcing fibers include carbon fibers, Kepler fibers, and glass fibers, and carbon fibers are most suitable because of their high strength and elastic modulus. Further, the temperature of the motor case rises to 100° C. or more when the propellant is combusted. Therefore, the resin used is required to have heat resistance. Therefore, thermosetting resins such as Evoki resin, polyester resin, polyimide resin, phenol/L-resin, and high-performance engineered plastics such as PEEK (polyether ether ketone) and pps (polyphenylene samphide) are used. High quality thermoplastic resins are suitable.

Rocket motor case generally weighs 200 kg/aI11
A certain degree of pressure resistance is required, and large stress is also generated at the connection between the FRP motor case and the cap, which is rounded at both ends. When fixing the cap with a screw, in order to withstand the stress that occurs, it is necessary to increase the diameter of the screw (or make the screw longer), which makes it heavy and unsuitable.
Mandrel (core metal) for forming into a shape that does not come off from P
Nowadays, a method has been adopted in which they are set on both sides of the FRP and molded integrally with the FRP.

The metal for the cap may be iron, titanium, aluminum, copper, etc., but since large stress is generated, it is preferable to use ultra-high-strength steel such as maraging steel, Nitsu'Ik chromium molybdenum steel, chromium molybdenum steel, etc. Titanium etc. are preferable. The shape of the rocket motor case is preferably cylindrical or spherical in terms of strength and moldability. The integrated method for making an FRP rocket motor case involves setting metal caps on both ends of a cylindrical mandrel, and using the filament winding method to create a reinforcing fiber impregnated with NVC packing fat at a predetermined orientation angle to the required thickness. There is a method of winding the material and curing it, a method of laminating a predetermined thickness of bripreg sheets made of reinforcing mal impregnated with resin, and curing the material, or a combination of all of these methods. In the filament winding method, reinforcing fibers are wound around a mandrel under tension, resulting in higher strength and elastic modulus than the method of laminating prepreg sheets.
Suitable for molding T-ket motor cases. Therefore, although it is possible to combine some prepreg sheet lamination methods, it is preferable to mainly use the filament winding method.

When the resin is heated and hardened during molding, the metal cap expands and the resin hardens, so the cap and FRPO are heated and hardened when cooled.
There are times when gaps occur due to differences in the coefficient of expansion. In particular, in the case of the filament winding method, since the filament is turned at the base, the orientation angle approaches the circumferential direction and the m-swelling ratio 5Ix of the FRP becomes small. When the reinforcing fiber is carbon fiber, the coefficient of linear expansion becomes
It is much smaller than 6 and there is always a gap. Therefore, FR
When attaching the ignition device and nozzle to the base, which has a circular cross section similar to the P rocket chamber, the base may move, causing cracks in the lining material, making it impossible to set it in the required position, and even causing problems during flight. A problem arises that adversely affects the accuracy of

Therefore, by providing unevenness on the outer periphery of the cap in contact with the FRP, the misalignment between the cap and the FRP was prevented, and the problem caused by the misalignment of the cap was solved. The unevenness is created by providing continuous cylindrical grooves on the outer periphery of the cap in contact with the FRP. The shape of the groove is preferably circular or triangular. The arc-shaped or triangular grooves allow the fibers wound by the filament winding method to easily enter the entire groove, and even small grooves can stop rotation.

In addition, compared to other square shapes, the stress concentration due to the shape of the groove is small, and the strength of the base portion is less reduced, making it suitable for quantizing the base.

(Example> Next, an example will be shown (see FIGS. 1 and 2).

A CFRP rocket motor case with iron caps on both ends was fabricated using integral molding method 9, and a pressure test was conducted.

An 8-piece mandrel (2) with an outer diameter of 120 blades and a length of 500 IIIffl, with a ring-shaped cap (11) attached to both ends so that it can be snapped, and after FRP molding, the mandrel can be divided and extracted from the inside of the cap (2). do.

The ring-shaped cap has a tapered shape on the side that goes into the FRP on one side, so that the FRP will not come out even if internal pressure is applied. The center part of the cap has an outer diameter of 85 mm, the outer diameter on the opposite side of the taper is 95 mm, and the inner diameter on the motor case side is 75 mm.
rnrn and the other side has an M2O screw. Width 5mm+, depth 2rnrn on the side part of the outer diameter 95cm
There are 24 arc-shaped grooves (3) arranged at equal intervals. The material of the cap is 5 soc iron. Apply liquid epoxy resin (e.g. Ebico) 82 to the mandrel with this nozzle set.
8 (Showa Shell ■) 100 parts, hardening agent IHN2200 (
High-strength carbon fiber impregnated with a wetting solution of 90 parts of Hitachi Chemical ■) and 1 part of accelerator 2E4MZ (Shikoku Fine Chemical ■) For example, trading card T300-12000fil (Torayka
) Wind one filament. The layer composition was first set at ±40 degrees with respect to the axial direction of the mandrel and turned at the arc-shaped groove of the base, and the thickness was 1.5 mm.
Winding up to m layers (Next, the mandrel outer diameter is 1201 mm at ±89 degrees.
! At point 111, form an filament winding layer to a thickness of α4. After winding the fibers, a release film was wound, and the resin was heated at 120° C. for 2 hours and then at 150° C. for 2 hours to harden the resin. After curing, the mold is cooled, the release film is removed, and the divided mandrel is taken out from inside the die. In this way, CFRP with iron caps on both ends
A ket motor case (4) was molded. After molding, the inner surface of the motor case is lined with 1m+n of silicone rubber! Then, a pressure test jig with an M2O thread cut on the outer periphery was attached to the cap. When installing the jig, there was no play between the motor case and the cap, and the jig could be installed without any problems.

In addition, in a pressure test, the product was held at a water pressure of 250 kg/Cxf for 60 seconds, but no cracks or water leaks occurred in the main body.

Next, a comparative example will be shown.

The same mandrel as in the example was used, and iron caps having the same dimensions as in the example but without arc-shaped grooves were attached to both ends. A carbon fiber impregnated with resin was filament-winded onto a mandrel equipped with this nozzle under the same molding conditions as in the example to mold a CFRP III motor case. After molding, a silicone rubber lining with a thickness of 1 inch was applied to the inner surface of the motor case, and a pressure test jig with M2O threads was attached to the caps at both ends. However, when attaching the jig, it slipped between the motor case and the cap, causing the cap to rotate and tearing the silicone rubber inside.

So I removed the silicone rubber, applied a new silicone rubber lining, and installed the jig, being careful not to slip between the motor case and the cap. After installing the jig, there was a slight play in the motor case and mouthpiece. In the pressure test, there were no particular problems even when the product was held at a water pressure of 250 kg/- for 60 seconds.

(Effects of the Invention) The CFRPO rocket motor case of the present invention, which has an arc-shaped groove on the outer periphery of the base, has a mechanical structure in which the CFRP rocket motor case body and the base are mechanically stable, compared to the conventional method using a base without grooves. Because it is connected to the base, there is no slippage, so even when various types of jigs are attached to the cap trap, it remains in the correct position and is excellent.

[Brief explanation of the drawing]

FIG. 1 shows a CFRP rocket motor case showing an embodiment of the present invention. FIG. 2 shows a cap used in an embodiment of the present invention. Explanation of symbols 1 Base 2 Mandrel 6 Arc-shaped groove 4 CFRP rocket motor case Fig. 1 Fig. 2

Claims (1)

[Claims] 1. An FRP rocket motor case with metal caps attached to both ends, characterized in that the portions of the cap that contact both ends of the FRP are provided with unevenness and are molded integrally with the FRP. Manufacturing method for manufactured rocket motor cases. 2. The method for manufacturing an FRP rocket motor case according to claim 1, wherein the unevenness of the base has a shape in which arc or triangular grooves are arranged circumferentially. 3. The method for manufacturing an FRP rocket motor case according to claim 1, wherein the FRP molding method is mainly a filament winding method.