阅读说明：本技术 一种使用软模加压的复合材料锥段成型模 (Composite material conical section forming die pressurized by using soft die ) 是由 徐云研 曹恒秀 柯常宜 张志斌 赵丁丁 夏海祥 蔡克甲 叶周军 张兵 章宇界 张 于 2020-11-20 设计创作，主要内容包括：本发明公开了一种使用软模加压的复合材料锥段成型模,包括设置在模具主体和刚性外模之间的橡胶软模,所述橡胶软模用于在成型过程中向对应于法兰增厚区的铺层在模具主体上的复合材料预浸料段进行加压。本发明在橡胶软模外设置刚性外模限位,橡胶软模内侧为卸压面,使软模膨胀压力与热压罐内压力一致；进一步橡胶软模在环向分段拼接而成,消除打压过程中橡胶内部张力引起的成型压力损失；并且,橡胶软模内侧边缘位于壁厚渐变区中心,使工艺边界与设计边界位置错开,避免增厚区边缘纤维屈曲。综上,本发明设计了实体橡胶软模加压,解决了复合材料锥段大壁厚转角位置压实困难的问题。(The invention discloses a composite material conical section forming die pressurized by using a soft die, which comprises a rubber soft die arranged between a die main body and a rigid outer die, wherein the rubber soft die is used for pressurizing a composite material prepreg section which is paved on the die main body and corresponds to a flange thickening area in the forming process. The invention arranges a rigid external mold limit outside a rubber soft mold, and the inner side of the rubber soft mold is a pressure relief surface, so that the expansion pressure of the soft mold is consistent with the pressure in a hot-pressing tank; the rubber soft mold is formed by annularly and sectionally splicing, so that the molding pressure loss caused by the internal tension of the rubber in the pressing process is eliminated; and the edge of the inner side of the rubber soft mold is positioned in the center of the wall thickness gradual change area, so that the position of the process boundary is staggered with that of the design boundary, and the buckling of fibers at the edge of the thickening area is avoided. In conclusion, the invention designs the solid rubber soft mold for pressurization, and solves the problem that the corner position of the large wall thickness of the composite material conical section is difficult to compact.)

1. The composite material conical section forming die pressurized by using the soft die is characterized by comprising a rubber soft die (3) arranged between a die main body (1) and a rigid outer die (2), wherein the rubber soft die (3) is used for pressurizing a composite material prepreg section which is laid on the die main body (1) and corresponds to a flange thickening area (5) in the forming process.

2. The composite material cone forming die as claimed in claim 1,

the rubber soft mold (3) is arranged on the corresponding laying prepreg of the flange thickening area (5);

the rigid outer die (2) is arranged at the end part of the die main body (1) and on the rubber soft die (3) and used for limiting the end part of the flange and limiting the expansion of the rubber soft die (3) so that the expansion amount is released to the inner side surface (7) of the rubber soft die (3).

3. The composite material cone segment forming die as claimed in claim 2, wherein the outer side face (6) of the rubber soft die (3) is limited by the rigid outer die (2).

4. The composite material conic section molding die using soft die pressing according to claim 2, wherein the inner side face (7) of the rubber soft die (3) is a pressure relief face.

5. The composite material conical section forming die as claimed in claim 1 or 2, wherein the soft rubber die (3) is formed by splicing in circumferential sections.

6. The composite material conical section forming die as claimed in claim 5, wherein the rubber soft die (3) is divided into 6 to 16 sections in the circumferential direction.

7. The composite material conical section forming die as claimed in claim 5, wherein the adjacent two sections of the soft rubber dies (3) are not connected and fixed.

8. The composite material cone forming die as claimed in claim 2, wherein the lateral outer side face (6) of the soft rubber die (3) is provided with outer pressure relief surfaces (10) at intervals without steel die constraint.

9. The composite material cone forming die as claimed in claim 1 or 2, wherein the side of the flange thickening region (5) close to the cone is a wall thickness gradually-changing region, and the inner side surface (7) of the soft rubber die (3) is close to one side edge of the cone and is positioned between two side edges (9) of the wall thickness gradually-changing region.

10. The composite material conic section molding die as claimed in claim 1, further comprising a vacuum bag provided on the mold body (1) and integrally covering the rigid outer mold (2), the flexible rubber film (3) and the composite material prepreg used for the product (4).

Technical Field

The invention relates to a composite material conical section forming die, in particular to a composite material conical section forming die pressurized by a soft die.

Background

At present, the carrier rocket load-bearing structure for spaceflight uses a large amount of high-strength composite materials, and has the main advantages that the composite material has a good weight reduction effect, and the effective load of single launch can be increased. As an important bearing structure of the rocket body final power cabin, the composite material conical section is used for supporting effective loads such as satellites. The typical structure of the composite material conical section is a thin-wall conical section, the front end and the rear end are thickened flanges, and a wall thickness transition area is arranged between the flanges and the conical section. In order to improve the strength of the interface position on the flange, the wall thickness of the flange usually reaches 5-8 mm; the profiles of the connecting parts of the conical sections and the flanges are severely changed due to the limitation of the internal space of the power cabin. Due to the factors, the prepreg in the thickened area of the flange is difficult to compact, and the loose and fiber buckling are easy to generate after curing. And the prepreg compaction and fiber straightening in the thickening area are realized by optimizing a pressurizing mode.

Through the search and discovery of the prior patent documents, the utility model patent of CN205929161U discloses a locatable soft mold for realizing the accurate manufacture of composite materials; through embedding the metal positioning block in the rubber and applying mechanical connection, the accurate positioning of the rubber soft mold is realized, so that the soft mold is uniformly expanded after being heated, and more accurate size is provided. However, in order to ensure the accurate positioning of the rubber soft mold, the positioning steel plate and the metal block are adopted to limit the position of the soft mold, so that the free expansion of the rubber is blocked, and the forming pressure of the composite material is mainly determined by the pressure generated by the thermal expansion effect of the rubber, namely the pressure linearly increases along with the temperature increase. In autoclave processes, precise control of pressure at multiple specific temperature points cannot be achieved.

Disclosure of Invention

The invention aims to provide a composite material conical section forming die which is pressurized by using a soft die. In the forming die, an outer rigid outer die is used for limiting the thermal expansion of rubber at a corresponding position and releasing the expansion amount to a pressure relief surface; the pressure relief surface is in contact with air pressure, so that the internal stress of the rubber is consistent with the air pressure. Because the air pressure in the autoclave is even, the pressure in the rubber soft mould can also be kept even, so that even and controllable curing pressure is provided for the thick flange, and the improvement of the internal quality is realized.

The purpose of the invention is realized by the following technical scheme:

the invention relates to a composite material conical section forming die pressurized by using a soft die, which comprises a rubber soft die 3 arranged between a die main body 1 and a rigid outer die 2, wherein the rubber soft die 3 is used for pressurizing a composite material prepreg section which is corresponding to a flange thickening area 5 and is laid on the die main body 1 in the forming process.

As an embodiment of the invention, the soft rubber mold 3 is arranged on the layered prepreg corresponding to the flange thickening area 5; the rigid outer die 2 is arranged at the end part of the die body 1 and on the soft rubber die 3 and used for limiting the flange end part of the product 4 and limiting the expansion of the soft rubber die 3, so that the expansion amount is released to the inner side surface 7 of the soft rubber die 3.

As an embodiment of the invention, the outer side surface 6 of the soft rubber mold 3 is limited by the rigid outer mold 2.

In one embodiment of the present invention, the inner side surface 7 of the soft rubber mold 3 is a pressure relief surface. The inner side surface 7 is not limited by a rigid outer die, so that the expansion pressure of the soft die is consistent with the pressure in the hot pressing tank.

As an embodiment of the invention, the soft rubber mold 3 is formed by splicing in a ring-shaped section.

As an embodiment of the invention, the soft rubber mold 3 is divided into not less than 6 segments in the circumferential direction. The concrete application can be divided into 6-16 sections.

As an embodiment of the invention, the two adjacent sections of the soft rubber molds 3 are not connected and fixed. This arrangement is used to eliminate the loss of molding pressure caused by the internal tension of the rubber when the autoclave is pressurized.

As one embodiment of the present invention, the lateral outer side 6 of the soft rubber mold 3 is provided with outer pressure relief surfaces 10 at intervals without steel mold constraint. The soft die can apply tension to the fibers when expanding outwards through the pressure relief surface, so that the fibers are prevented from buckling.

As an embodiment of the invention, one side of the flange thickening area 5 close to the conical section is a wall thickness gradually-changing area, and one side edge of the inner side surface 7 of the soft rubber mold 3 close to the conical section is positioned between two side edges 9 of the wall thickness gradually-changing area. The arrangement ensures that the edge of one side of the inner side surface 7 close to the conical section is far away from the edges of two ends of the wall thickness gradual change area as far as possible, so that the position of the process boundary is staggered with that of the design boundary, and the buckling of fibers at the edge 9 of the wall thickness gradual change area is avoided.

As an embodiment of the invention, one side edge of the inner side surface 7 of the soft rubber mold 3 close to the cone section is positioned at the central position 8 of the wall thickness gradual change area.

As an embodiment of the present invention, the forming mold further comprises a vacuum bag disposed on the mold body 1, and the vacuum bag completely covers the composite prepreg used for the rigid outer mold 2, the flexible rubber film 3 and the product 4.

Compared with the prior art, the invention has the following beneficial effects:

1) the invention adopts the rubber soft mold to pressurize, so that the pressure is uniformly applied to the surface of the product;

2) the invention arranges a rigid external mold limit outside a rubber soft mold, and the inner side of the rubber soft mold is a pressure relief surface; the expansion pressure of the soft die is kept consistent with the pressure in the hot-pressing tank through the inner pressure relief surface;

3) according to the invention, the rubber soft die is spliced in a circumferential sectional manner, so that the molding pressure loss caused by the internal tension of the rubber in the pressing process is eliminated;

4) the edge of the inner side of the rubber soft mold is positioned in the center of the wall thickness gradual change area, so that the position of a process boundary is staggered with that of a design boundary, and the buckling of fibers at the edge of the thickening area is avoided;

5) the invention designs solid rubber soft mould pressurization, and solves the problem that the corner position of the large wall thickness of the composite material conical section is difficult to compact;

6) compared with the existing rigid mould pressurizing form, the invention adopts the rubber soft mould with higher adaptability to the product profile, can avoid uneven overall pressure caused by local bridging of the rigid mould, enables the pressure to be uniformly and stably applied to the product surface, and can obviously improve the compaction degree of the prepreg.

Drawings

Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:

FIG. 1 is a schematic view of the overall structure of a mold in example 1;

FIG. 2 is a schematic view of a single block back end rubber soft mold of example 1;

FIG. 3 is a schematic view of a single block front rubber soft mold of example 1;

FIG. 4 is a schematic view of an exemplary product;

FIG. 5 is a schematic view showing the entire structure of a mold in example 2;

FIG. 6 is a schematic view of a single block back end rubber soft mold of example 2;

the method comprises the following steps of 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10, wherein the main body of the die is 1, the rigid outer die is 2, the soft rubber die is 3, the product is 4, the thickened area of the flange is 5, the outer side surface is 6, the inner side surface is 7, the center position of the gradually-changed area of the wall thickness is 8, the edge of the gradually-changed area of the wall thickness is 9, and.

Detailed Description

In order that the objects and advantages of the invention will become more apparent, the invention is further described in detail below with reference to examples, which will assist those skilled in the art in further understanding the invention, but are not to be construed as limiting the invention in any way. It should be noted that variations and modifications can be made by persons skilled in the art without departing from the spirit of the invention. All falling within the scope of the present invention.

Example 1

The embodiment relates to a composite material conical section forming die using soft die pressurization, which comprises a die main body 1, a rigid outer die 2 and a rubber soft die 3, as shown in figure 1;

and the mould main body 1 is used for supporting the product 4 to be layered and cured by using the prepreg.

And the rigid outer die 2 is arranged at the end part of the die body 1 and the soft rubber die 3 and used for limiting the flange end part of the product 4 and limiting the expansion of the soft rubber die 3 so that all expansion amounts are released to the inner side surface 7. In the mold of the embodiment, the rigid outer mold 2 is arranged on the outer side surface 6 of the rubber soft mold 3 for limiting; the inner side surface 7 of the soft rubber mould 3 is not limited by the rigid outer mould 2 and is used as a pressure relief surface in the curing process, so that the expansion pressure of the soft rubber mould 3 is consistent with the pressure in the hot-pressing tank.

The rubber soft mold 3 is arranged on the layer-spread prepreg corresponding to the flange thickening area 5 of the product 4; the curing process is thermally expanded to provide curing pressure to the flange thickening region 5 of the product 4. The inner side surface 7 of the rubber soft membrane 3 is used as a pressure relief surface, so that the expansion pressure of the soft membrane is consistent with the pressure in the hot pressing tank.

And the product 4 is obtained by laying a prepreg on the mould main body 1 and curing and molding the autoclave. During curing, the flange thickening area 5 is pressed through the solid rubber soft mold 3.

The forming die further comprises a vacuum bag arranged on the die main body 1, and the rigid outer die 2, the rubber soft film 3 and the composite material prepreg (a product 4 is formed by vacuum curing and forming of an autoclave) are completely wrapped by the vacuum bag.

In order to eliminate the molding pressure loss caused by the internal tension of the rubber when the autoclave is pressurized, as an improved scheme, the soft rubber mold 3 is formed by splicing in a ring-shaped section; the adjacent two sections of the soft rubber moulds 3 are not connected and fixed. The rubber soft die 3 is divided into at least 6 sections in the circumferential direction; in the embodiment, 6 sections are selected; wherein, the single front end rubber soft mold 3 is shown in fig. 3, and the rear end rubber soft mold 3 is shown in fig. 2; referring to fig. 1, a soft rubber mold 3 is positioned between the rigid outer mold 2 and the composite prepreg laid on the mold body 1, and is in full contact with the prepreg. The surface of the soft rubber mold 3, which is in contact with the rigid outer mold 2, is marked as an outer side surface 6, and the surface, which is not in contact with the mold body 1, the rigid outer mold 2 or the composite prepreg, is marked as an inner side surface 7. In order to avoid buckling of the fibers at the edge 9 of the wall thickness transition region, as a modification, one edge of the inner side 7 of the soft rubber mold 3 is located near the center 8 of the wall thickness transition region of the product 4. The arrangement ensures that the edge of one side of the inner side surface 7 close to the conical section is far away from the edges of the two ends of the wall thickness gradual change area as far as possible, so that the process boundary and the design boundary are staggered, and the fiber buckling of the edge 9 of the wall thickness gradual change area is avoided. In the embodiment, one side edge of the inner side surface 7 of the soft rubber mold 3, which is close to the cone section, is positioned at the central position 8 of the wall thickness gradual change area; equidistant from the two end edges 9 of the region of gradual wall thickness change.

The specific method for using the die comprises the following steps:

s1, cleaning the die body 1, and coating a release agent on the rubber soft die 3 and one side of the sticker product 4 of the die body 1.

S2, laying the product 4 on the mold body 1 with the prepreg.

And S3, placing the rubber soft mold 3 at the position corresponding to the flange of the product 4 and pasting the rubber soft mold firmly.

And S4, fixing the rigid outer die 2 to the die body 1.

And S4, manufacturing a vacuum bag on the mould main body 1, wherein the rigid external mould 2, the rubber soft film 3 and the product 4 are completely covered by the vacuum bag.

And S5, entering an autoclave, vacuumizing in a vacuum bag, and then heating for curing. During the warming process, air or nitrogen is used for pressurization at a specific temperature point. And stopping vacuum after curing and cooling are finished, removing the rigid external mold 2 and the rubber soft mold 3, and taking the product 4 from the mold body 1, wherein the final structure is shown in fig. 4.

Example 2

The embodiment relates to a composite material conical section forming die using soft die pressurization, which comprises a die main body 1, a rigid outer die 2 and a rubber soft die 3, as shown in fig. 5;

and the mould main body 1 is used for supporting the product 4 to be layered and cured by using the prepreg.

And the rigid outer die 2 is arranged at the end part of the die body 1 and the soft rubber die 3 and used for limiting the flange end part of the product 4 and limiting the expansion of the soft rubber die 3, so that the expansion amount is released to the inner side surface 7 and the outer pressure relief surface 10.

In addition, unlike the embodiment 1, in order to better avoid the buckling of the fibers, the lateral outer side surface 6 of the soft rubber mold 3 of the embodiment is provided with outer side pressure relief surfaces 10 at intervals without steel mold constraint (the outer side pressure relief surfaces 10 are not provided in all circles); as shown in fig. 6. This setting makes the soft mould accessible unload and exert the tensile force to the fibre when pressing the face outwards inflation, avoids fibre buckling.

The rubber soft mold 3 is arranged on the layer-spread prepreg corresponding to the flange thickening area 5 of the product 4; the curing process is thermally expanded to provide curing pressure to the flange thickening region 5 of the product 4. The inner side surface 7 of the rubber soft membrane 3 is used as a pressure relief surface, so that the expansion pressure of the soft membrane is consistent with the pressure in the hot pressing tank.

And the product 4 is obtained by laying a prepreg on the mould main body 1 and curing and molding the autoclave. During curing, the flange thickening area 5 is pressed through the solid rubber soft mold 3.

The forming die further comprises a vacuum bag arranged on the die main body 1, and the rigid outer die 2, the rubber soft film 3 and the composite material prepreg (a product 4 is formed by vacuum curing and forming of an autoclave) are completely wrapped by the vacuum bag.

The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes and modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention.