CN103909658A - Composite material connecting skirt forming method and mold and inner rubber core mold forming mold - Google Patents

Abstract

The invention discloses a composite material connection skirt forming method, a mold and a rubber inner core mold forming mold thereof. The method comprises the following steps: 1) Making a forming mold: making an outer mold, an inner mold, and a rubber inner core mold, and The rubber inner core mold is set on the outer wall of the inner mold; 2) Layer laying; 3) Preheating and vacuuming of the forming mold; 4) Resin pretreatment; As the temperature rises and expands, the preform is uniformly pressurized so that the resin fully infiltrates the preform; 6) demoulding and trimming; the rubber inner core mold is used in the forming mold structure. The invention adopts silicone rubber-assisted RTM process to form the connecting skirt of composite materials, and adopts double-sided molds, so that the product has the advantages of stable size, good quality consistency, and controllable fiber and resin content; at the same time, it adopts co-curing and expandable cores Modes and other means reduce the porosity and improve the fiber volume content and mechanical properties of the product.

Description

Composite connecting skirt forming method, mold and rubber inner core mold forming mold thereof

technical field

The invention relates to the molding technology of solid rocket motor shells, in particular to a molding method of a composite material connecting skirt, a mold and a rubber inner core mold molding mold thereof.

Background technique

The connecting skirt of the solid rocket motor casing is an integral extension of the casing, which is used to realize the connection between the missile stages or with other components. The connecting skirt needs to withstand various loads such as axial pressure, bending moment, shear, and internal pressure. The force situation is more complicated. How to simplify the molding process and improve its performance without increasing the weight of the connecting skirt is crucial to the improvement of the performance of the entire engine casing.

At present, the connecting skirt of composite materials is usually formed by the "prepreg lay-up + winding" molding method. This molding method exposes the following problems in the production process: 1) There is only one rigid male mold in the molding process, and the outer surface of the product is made of The fiber yarn is wound and pressed, and sometimes there are strangle marks, protrusions, and depressions, etc., which cannot guarantee the smoothness of the outer surface of the product, and it is difficult to guarantee the overall size of the product; 2) The resin content is controlled by manual scraping, which is more harmful to the fiber damage. Large, and the degree of scraping is not easy to control, which has a great impact on the total weight and specific impulse of the engine casing; 3) It is impossible to form a composite connecting skirt with a rib structure, and the product structure efficiency is low; 4) The fiber at the corner of the connecting skirt It is easy to be overhead, delaminated and wrinkled. At present, a conservative design method with an increased safety factor is used to ensure that the place will not be damaged under the working load, but this method further reduces the structural efficiency of the composite skirt.

Contents of the invention

The purpose of the present invention is to provide a molding method of a composite material connecting skirt, a mold and a rubber inner core mold forming mold thereof, the composite material connecting skirt made by the molding method and the mold thereof has excellent mechanical properties, high fiber volume content, Simultaneously, the molding process is simple and the operation is convenient.

In order to achieve the above object, the technical solution adopted in the present invention is: a method for forming a composite material connecting skirt, comprising the following steps:

1) Making a forming mold: making an outer mold, an inner mold, and a rubber inner core mold. Shape fit, the shape of the inner mold matches the inner shape of the rubber inner mandrel; then apply a release agent evenly on the outer wall of the inner mold, and set the rubber inner mandrel on the outer wall of the inner mold;

2) Lay-up: After cutting the fiber reinforced material into different sizes and angles and applying a sizing agent, lay it on the rubber inner mandrel layer by layer, lay it to a certain thickness and then compact it until there is no wrinkle. Obtain the preform;

3) Preheating and vacuuming of the forming mold: the outer mold and the inner mold are clamped and assembled, and then the forming mold is heated and vacuumized;

4) Resin pretreatment: Stir the resin evenly and then vacuumize;

5) Glue injection and curing: inject the pretreated resin into the mold cavity for molding; after the glue injection is completed, the resin is heated and cured, and the rubber inner mandrel expands as the temperature rises, and the preform is uniformly pressurized , so that the resin fully infiltrates the preform;

6) Demoulding and trimming: After demoulding, the molded body is trimmed to obtain a composite skirt.

Further, in the step 1), the molding method of the rubber inner core mold includes the following steps:

a. Preparation of rubber glue: prepare rubber glue according to the mass ratio of rubber emulsion: vulcanizing agent = 90-99%: 1-10%, stir the rubber glue evenly and then evacuate to -10--20Kpa, hold the pressure for 30 ~60min, until there are no larger air holes, take it out for use;

b. Rubber inner mandrel molding: inject rubber glue into the rubber inner mandrel forming mold for molding;

c. Vulcanization and demoulding: Naturally vulcanize the rubber glue at room temperature for 22-26 hours, then raise the temperature to 95-100°C and keep it for 1.0-1.5h, and finally raise the temperature to 195-205°C and keep it for 1.0-1.5h; after cooling to room temperature Demoulding to obtain a rubber inner mandrel.

Further, in the step 2), the ply angles are 0°, ±15°, ±30°, ±45°, ±60° and 90°.

Further, in the step 5), the resin injection temperature is 20-150° C., and the injection pressure is 0.1-0.8 MPa.

Further, in the step 5), the curing condition of the resin is: heat preservation at 100-150°C for 1-4 hours, then heat up to 180-200°C for 1-4 hours, and finally heat up to 210-250°C for 2-10 hours.

Further, in the step 1), the molding material of the rubber inner core mold is R10301 silicone rubber; the release agent is silicone grease or PMR-70.

Further, in the step 2), the fiber reinforced material is glass fiber cloth or carbon fiber cloth.

Further, in the step 4), the resin is double horse resin or epoxy resin.

A composite connecting skirt molding die designed to realize the above method, comprising an inner die and an outer die, the outer wall of the inner die is coaxially fitted with a rubber inner mandrel, and the outer die is coaxially fitted on the The outer periphery of the rubber inner mandrel, the top of the inner mold is connected with a pressing plate, the top surface of the pressing plate is connected with the top of the outer mold, the bottom of the inner mold is connected with a deflector, and the bottom of the deflector is connected with a Cover plate, the outer periphery of the cover plate is connected to the bottom of the outer mold, the rubber inner core mold and the outer mold, inner mold, pressure plate, and deflector form a connecting skirt molding cavity, the A glue injection port communicated with the mold cavity is opened on the cover plate, and a glue outlet communicated with the mold cavity is opened on the top of the outer mold.

A rubber inner mandrel molding die for forming a composite material connecting skirt designed to realize the above method, comprising a forming inner mold, the outer circumference of the forming inner mold is coaxially fitted with a first outer mold, and the top outer mold of the forming inner mold is A second outer mold is connected along the edge, and the inner mold, the first outer mold, and the second outer mold form a molding cavity of a rubber inner mandrel, and a discharge port is provided on the second outer mold.

Compared with prior art, the present invention has following advantage:

First, the present invention adopts silicone rubber-assisted RTM process to carry out the molding of composite material connection skirt, because adopt double-sided mold to make, make product have stable size, good quality consistency, and the advantages such as controllable fiber and resin content, solve manual The degree of squeegee caused by squeegee is not easy to control, and it also avoids the phenomenon of fiber overhead, delamination and wrinkles at the corners of the connecting skirt; at the same time, co-curing and expandable rubber mandrels are used to reduce the porosity of the product and improve the product’s durability. Fiber volume content and mechanical properties.

Second, this molding method is integrated, the product has uniform appearance color, good internal bonding, high precision, and does not need to machine the fiber layer to avoid damage to the fiber by machine adding; and it can form a composite with a rib structure The material is connected to the skirt, which improves the structural efficiency of the product.

Third, the forming mold uses a rubber mold as the inner core mold. During the curing process, as the temperature rises, the rubber inner core mold expands, and the preform is uniformly pressurized throughout the process, so that the resin can fully infiltrate the preform. It ensures the uniform distribution of resin inside the product, increases the fiber volume content of the product, and greatly improves the mechanical properties of the material.

Description of drawings

Fig. 1 is a schematic cross-sectional structure diagram of a connecting skirt forming mold made of composite material.

Fig. 2 is a schematic cross-sectional structure diagram of a rubber inner core mold molding die.

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings and examples, so as to facilitate a clearer understanding of the present invention, but they do not limit the present invention.

Shown in Fig. 1 is a kind of composite material connecting skirt molding die used in the following examples, comprising an inner mold 1 and an outer mold 2, a rubber inner mandrel 3 is fitted coaxially on the outer wall of the inner mold 1, and the outer mold 2 The coaxial sleeve is set on the outer periphery of the rubber inner core mold 3, the top of the inner mold 1 is connected with the pressure plate 4, the top surface of the pressure plate 4 is connected with the top of the outer mold 2, the bottom of the inner mold 1 is connected with the deflector 5, and the deflector The bottom of 5 is connected with cover plate 6, and the outer peripheral edge of cover plate 6 is connected with the bottom of outer mold 2, and rubber inner mandrel 3 and outer mold 2, inner mold 1, pressure plate 4, and deflector 5 form a connecting skirt forming The mold cavity 7, the cover plate 6 is provided with a glue injection port 8 communicating with the mold cavity 7, the top of the outer mold 2 is provided with a glue outlet 9 communicated with the mold cavity 7, and the top surface of the inner mold 1 and the bottom surface of the pressure plate 4 are opened. There is a sealing groove 10 for installing the sealing strip, and there are also sealing grooves between the deflector 5 and the cover plate 6, and between the deflector 5 and the bottom surface of the inner mold 1 respectively.

Shown in Fig. 2 is a kind of rubber inner mandrel forming die used in the following embodiments, comprising molding inner mold 14, the outer circumference coaxial sleeve of molding inner mold 14 is equipped with first outer mold 15, and molding inner mold 14 tops The second outer mold 16, the inner mold 14, the first outer mold 15, and the second outer mold 16 are connected along the edge to form a rubber inner mandrel molding cavity 17, and the second outer mold 16 is provided with a discharge port 18.

Example 1

The size and performance parameters of the composite material connecting skirt for the motor casing prepared in this embodiment are as follows in Table 1:

Table 1

serial number project unit index 1 Flange inner diameter mm φ400.0 2 End wall thickness mm 6.0 3 skirt height mm 100.0 4 Barrel wall thickness mm 3.0 5 Axial pressure kN ≥500.0 6 fiber volume content % ≥60

The molding method of the composite material connecting skirt comprises the following steps:

1) Making a forming mold: making an outer mold, an inner mold, and a rubber inner core mold. The shape is matched, the shape of the inner mold is matched with the inner shape of the rubber inner mandrel; then a layer of release agent is evenly applied on the outer wall of the inner mold, and the release agent is silicone grease or PMR-70. The rubber inner core mold is set on the outer wall of the inner mold;

Among them, the process of forming the rubber inner mandrel by using the rubber inner mandrel molding die is as follows:

a. Preparation of rubber glue: use R10301 rubber, prepare 5kg of rubber glue according to the mass ratio of rubber emulsion: vulcanizing agent = 90-99%: 1-10%, preferably 90%: 10%, stir evenly, at room temperature Put the rubber glue into the vacuum box, evacuate until the vacuum degree is -10 ~ -20Kpa, preferably -10Kpa, keep the pressure for 30 ~ 60min, preferably 30min, until there are no larger pores, take it out for use;

b. Rubber inner mandrel molding: clean the surface of the forming inner mold and evenly apply silicone grease, then assemble with the first outer mold and the second outer mold respectively, and inject rubber glue into the rubber inner mandrel from the discharge port to form forming in the mold;

c. Vulcanization and demoulding: after the glue injection, vulcanize the rubber glue at room temperature for 22-26 hours, preferably 24 hours; then raise the temperature to 95-100°C, preferably 100°C, keep it warm for 1.0-1.5h, preferably 1.0h; finally Heat up to 195-205°C, preferably 200°C, keep warm for 1.0-1.5h, preferably 1h; naturally cool to room temperature and demould to obtain a rubber inner mandrel;

2) Preform layer: cut 40 pieces of carbon fiber cloth or glass fiber cloth and apply the setting agent according to (0°) ₂ / (±15°, ±30°, ±45°, ±60°) ₉ /90° The order of ₂ is to lay layer by layer on the rubber inner mandrel from the inside to the outside (the 0° direction of the fiber layup is defined as the inner mold ring direction), and lay until the wall thickness of the end face is 6.0mm, and the wall thickness of the barrel section is 3.0mm, trim off the excess The fiber cloth is wrapped with a vacuum bag and then vacuumed and compacted until all the fibers are compacted without wrinkles, and the preform is obtained;

3) Preheating and vacuuming of the forming mold: Clamp and assemble the outer mold 2 and the inner mold 1, that is, firstly install a sealing strip in the sealing groove 10 of the inner mold 1, and then sequentially pass the pressure plate 4 and the inner mold 1 through The first screw 11 is fastened, the outer mold 2 and the pressure plate 4 are tightened by the second screw 12, the deflector 5 and the inner mold 1 are fastened, and finally the cover plate 6 and the outer mold 2 are tightened by the third screw 13 for fastening; then the forming mold is heated to 130°C and vacuumized;

4) Resin pretreatment: Stir the Shuangma resin at 20-150°C, preferably 130°C, and then vacuumize;

5) Glue injection and curing: inject the pretreated Shuangma resin into the mold cavity from the two injection ports at the same time under the pressure of 0.1-0.8MPa, preferably 0.5MPa, and then cure the resin as follows Curing system: 100-150°C, preferably 150°C, keep warm for 1-4h, preferably 4h; then raise the temperature to 180-200°C, preferably 180°C, keep warm for 1-4h, preferably 2h; 220°C, keep warm for 2-10 hours, preferably 6 hours, the rubber inner mandrel expands as the temperature rises, and uniformly pressurizes the preform, so that the resin can fully infiltrate the preform;

6) Demoulding and trimming: Trimming the composite material connecting skirt products to obtain the finished composite material connecting skirt.

After testing, the performance indicators of the above formed composite connecting skirt are shown in Table 2:

Table 2

serial number project unit result 1 Axial pressure kN 620.7 2 fiber volume content % 65.0

It can be seen from the data in Table 2 that the prepared composite skirt has good mechanical properties and a large fiber volume content.

Example 2

The size and performance parameters of the composite material connecting skirt for the engine case prepared in this embodiment are as follows in Table 3:

table 3

serial number project unit index 1 Flange inner diameter mm φ1200 2 End wall thickness mm 12.0 3 skirt height mm 250.0 4 Barrel wall thickness mm 8.0 5 Axial pressure kN ≥1000.0 6 fiber volume content % ≥60

The molding method of the composite material connecting skirt comprises the following steps:

1) Making a forming mold: making an outer mold, an inner mold, and a rubber inner core mold. Shape matching, the shape of the inner mold matches the inner shape of the rubber inner mandrel; then apply a layer of release agent evenly on the outer wall of the inner mold, and set the rubber inner mandrel on the inner mold outer wall;

Among them, the process of forming the rubber inner mandrel by using the rubber inner mandrel molding die is as follows:

a. Preparation of rubber glue: use R10301 rubber, prepare 5kg of rubber glue according to the mass ratio of rubber emulsion: vulcanizing agent = 95%: 5%, stir evenly, put the rubber glue into a vacuum box at room temperature, and vacuumize When the vacuum degree is -20Kpa, keep the pressure for 45 minutes, and take it out until there are no larger pores;

b. Rubber inner mandrel molding: clean the surface of the forming inner mold 14 and apply silicone grease evenly, then assemble with the first outer mold 15 and the second outer mold 16 respectively, and inject the rubber glue into the rubber from the discharge port 18 Forming in the inner core mold forming mold;

c. Vulcanization and demoulding: After the glue injection, the rubber glue is naturally vulcanized at room temperature for 24 hours, then heated to 100°C for 1.0h, and finally heated to 200°C for 1h; naturally cooled to room temperature and then demoulded to obtain the rubber inner Mandrel;

2) Preform layer: cut 80 pieces of carbon fiber cloth, apply the setting agent in the order of (0°) ₄ / (±15°, ±30°, ±45°, ±60°) ₁₈ /90° ₄ , layer by layer from the inside to the outside on the rubber inner mandrel (the direction of 0° of the fiber layer is defined as the ring direction of the inner mold), and cover until the wall thickness of the end face is 12.0mm, and the wall thickness of the barrel section is 8.0mm. Trim off excess fiber cloth, Vacuum compaction after wrapping with vacuum bags until all the fibers are compacted and wrinkle-free, and the preform is obtained;

3) Vacuuming the forming mold: Clamp and assemble the outer mold and the inner mold, that is: first install a sealing strip in the sealing groove of the inner mold, then fasten the pressure plate and the inner mold with screws 2 in turn, and tighten the outer mold Fasten the pressure plate with the screw 1, fasten the guide plate and the inner mold, and finally fasten the cover plate and the outer mold with the screw 3; then vacuumize the forming mold;

4) Resin pretreatment: Stir the epoxy resin evenly at room temperature and then vacuumize;

5) Glue injection and curing: inject the pretreated epoxy resin into the mold cavity from the two injection ports at the same time under the pressure of 0.3MPa for molding. After the glue injection is completed, the resin is cured according to the following curing system: 80°C Keep warm for 4 hours, then heat up to 100°C for 4 hours, and finally heat up to 120°C for 6 hours. The rubber inner mandrel expands as the temperature rises, and the preform is uniformly pressurized so that the resin can fully infiltrate the preform;

6) Demoulding and trimming: Trimming the composite material connecting skirt products to obtain the finished composite material connecting skirt.

After testing, the performance indicators of the above formed composite connecting skirt are shown in Table 4:

Table 4

serial number project unit result 1 Axial pressure kN 1427.0 2 fiber volume content % 72.1

It can be seen from the data in Table 4 that the prepared composite skirt has good mechanical properties and a large fiber volume content.

Claims (10)

1. a composite joint skirt forming method, comprises the following steps:

1) be made into mould: make external mold, internal mold, and rubber inner core mould, the profile of described rubber inner core mould coordinates with the interior shape of composite joint skirt, the interior shape of described external mold coordinates with the profile of composite joint skirt, and the profile of described internal mold coordinates with the interior shape of described rubber inner core mould; Then even smearing release agent on described internal mold outer wall, is loaded on described internal mold outer wall by described rubber inner core die sleeve;

2) laying: fibre reinforced materials is cut into different size and angle and is coated with and spread after setting agent, it is successively spread and is overlying on described rubber inner core mould, paving is covered to compacting after certain thickness, until corrugationless obtains preform;

3) mould preheating and vacuumizing: described external mold and internal mold are carried out to matched moulds assembling, then mould heated and vacuumize processing;

4) resin pretreatment: vacuumize after resin agitating is even;

5) injecting glue and curing: will carry out moulding in pretreated resin injection die cavity; After injecting glue, resin is heated up and solidify, rubber inner core mould, along with temperature raises and expands, evenly pressurizes to preform, thereby makes resin fully infiltrate preform;

6) demoulding and pruning: after the demoulding, formed body is carried out to overlap pruning, obtain composite joint skirt.

2. composite joint skirt forming method according to claim 1, is characterized in that: in described step 1), the forming method of described rubber inner core mould comprises the following steps:

A, preparation rubber glue: by rubber latex: the mass ratio preparation rubber glue of vulcanizing agent=90～99%:1～10%, rubber liquid cement agitation is evacuated to-10～-20Kpa after evenly, pressurize 30～60min, stand-by compared with taking out after gross blow hole to no longer occurring;

B, rubber inner core mold forming: rubber glue is injected to rubber inner core mould and carry out moulding;

C, sulfuration and the demoulding: by room temperature natural vulcanization 22～26h of rubber glue, be then warming up to 95～100 ℃ of insulation 1.0～1.5h, be finally warming up to 195～205 ℃ of insulation 1.0～1.5h; Be cooled to the demoulding after room temperature, obtain rubber inner core mould.

3. composite joint skirt forming method according to claim 1 and 2, is characterized in that: described step 2) in, laying angle is 0 °, ± 15 °, and ± 30 °, ± 45 °, ± 60 ° and 90 °.

4. composite joint skirt forming method according to claim 1 and 2, is characterized in that: in described step 5), resin injection temperature is 20～150 ℃, and injection pressure is 0.1～0.8MPa.

5. composite joint skirt forming method according to claim 1 and 2, it is characterized in that: in described step 5), resin solidification condition is: 100～150 ℃ of insulation 1～4h, be then warming up to 180～200 ℃ of insulation 1～4h, and be finally warming up to 210～250 ℃ of insulation 2～10h.

6. composite joint skirt forming method according to claim 1 and 2, is characterized in that: in described step 1), the moulding material of described rubber inner core mould is R10301 silicon rubber; Described releasing agent is silicone grease or PMR-70.

7. composite joint skirt forming method according to claim 1 and 2, is characterized in that: described step 2) in, described fibre reinforced materials is glass fabric or carbon cloth.

8. composite joint skirt forming method according to claim 1 and 2, is characterized in that: in described step 4), described resin is bismaleimide resin or epoxy resin.

9. one kind for realizing the composite joint skirt mould that method designs described in claim 1, comprise internal mold (1) and external mold (2), it is characterized in that: on described internal mold (1) outer wall, coaxial laminating is set with rubber inner core mould (3), described external mold (2) coaxial package is in the periphery of described rubber inner core mould (3), described internal mold (1) top is connected with pressing plate (4), the end face of described pressing plate (4) is connected with the top of described external mold (2), the bottom of described internal mold (1) is connected with deflector (5), the bottom of described deflector (5) is connected with cover plate (6), the periphery of described cover plate (6) is along being connected with the bottom of described external mold (2), described rubber inner core mould (3) and described external mold (2), internal mold (1), pressing plate (4), and deflector (5) surrounds joint skirt shaping mold cavity (7), on described cover plate (6), have the gum-injecting port (8) being communicated with described die cavity (7), described external mold (2) top has the gum outlet (9) being communicated with described die cavity (7).

10. one kind for realizing the rubber inner core mould of the composite joint skirt moulding that method designs described in claim 1, it is characterized in that: comprise moulding internal mold (14), the periphery coaxial sleeve of described moulding internal mold (14) is equipped with the first external mold (15), described moulding internal mold (14) outer, top is connected with the second external mold (16), described internal mold (14), the first external mold (15), and second external mold (16) surround rubber inner core mold forming die cavity (17), described the second external mold is provided with discharge port (18).