An RTM mold suitable for multi-size axial braiding

Abstract

The application discloses a kind of RTM mould suitable for multi-size axial weaving, including outwardly convex male mould, female mould, stripper ring, several lining plate unit groups, glue injection port and glue outlet, a group of lining plate unit groups are arranged in the female mould, and the lining plate unit group includes several lining plate units, and the lining plate unit is integrally sleeved around the lining plate outside the male mould, the lining plate whole, the male mould and the stripper ring form a containing cavity, the containing cavity is used to accommodate fiber layer and core mould, the glue injection port is communicated with the containing cavity, and the glue injection port is used to inject glue into the containing cavity;The glue outlet is communicated with the containing cavity, and the glue outlet is used to discharge the overflowed glue in the containing cavity;Different groups of lining plate unit groups are replaced to obtain different shapes and sizes of preforms.By replacing lining plates of different sizes, the mould can be used for RTM process of products with different thicknesses and shapes.

Description

TECHNICAL FIELD

[0001] The present application relates to composite material forming manufacturing, in particular to a RTM mold suitable for multi-size axial weaving. BACKGROUND

[0002] Advanced composite material has the advantages of high specific strength, high specific modulus, designability, fatigue resistance, impact resistance, corrosion resistance, etc., which meets the technical requirements of high bearing capacity and low structural mass of solid motor shell, and has been widely used in the development of various solid rocket motor shells. The shell is an important part of the solid rocket engine, and the advantages and disadvantages of its comprehensive performance greatly affect the quality of the engine. The application of new fiber weaving technology to solid rocket engines provides a new opportunity for the development of lightweight high-strength engines.

[0003] However, during the demolding process after the shell is wound, the shell head part is prone to yarn sliding, the head appears to be empty, which causes yarn disorder, and further causes the product structure shape to be inconsistent with the theoretical shape, affecting the quality of the product. As a typical problem in the process of composite material manufacturing, the traditional method is to change the curing process parameters, compensate the mold and adjust the mold pre-tension to reduce or offset the deformation of the component, but changing the curing process parameters is subject to material properties and process parameters, and it is often difficult to make significant changes, and the effect of reducing the curing deformation is not obvious. In addition, a set of molds can only process products of a single shape and size, and do not have general applicability. If the product shape parameters are changed, a new set of molds needs to be designed and manufactured, which wastes resources. SUMMARY

[0004] The purpose of the present application is to provide a RTM mold suitable for multi-size axial weaving with a certain universality.

[0005] Technical scheme: In order to solve the above problems, the present application adopts a RTM mold suitable for multi-size axial weaving, which comprises an outwardly convex male mold, an outer female mold, a demolding ring, a plurality of lining plate unit groups, a glue injection port and a glue outlet. A group of lining plate unit groups is arranged in the outer female mold, and the lining plate unit group comprises a plurality of lining plate units. The lining plate units surround a lining plate whole which is arranged outside the male mold. A containing cavity is formed between the lining plate whole, the male mold and the demolding ring. The containing cavity is used to contain the fiber layer and the core mold. The glue injection port is connected to the containing cavity and is used to inject glue into the containing cavity. The glue outlet is connected to the containing cavity and is used to discharge the overflowed glue in the containing cavity. Different groups of lining plate unit groups are replaced to obtain different shapes and sizes of preforms.

[0006] Further, the end face of the core mold is provided with hooks, which are used to weave the hooked yarns. The demolding ring includes a lower demolding ring, which is provided with grooves. The hooks of the end face of the core mold and the hooked ends of the yarns are placed in the grooves. The metal cover in the RTM mold also serves as a woven core mold. After weaving, the product can be directly placed in the RTM mold together with the product for impregnation process, thereby eliminating the prefabricated body demolding process.

[0007] Further, a plurality of product joints of different sizes corresponding to different groups of lining plate units are also included. The demolding ring further includes an upper demolding ring. The upper end of the lining plate body is provided with a circular outlet. The upper demolding ring is arranged between the circular outlets of the lining plate body. The upper demolding ring is provided with a mold joint for setting a glue outlet. The product joint is sleeved outside the mold joint. The product joint is located at the lower end of the upper demolding ring and is smoothly connected with the core mold.

[0008] Further, the lower demolding ring includes a first lower demolding ring sleeved outside the male mold and a second lower demolding ring sleeved outside the first lower demolding ring. The first demolding ring includes a first connecting part and a first fixing part. The first connecting part is sleeved outside the male mold. The plane where the first fixing part is located is perpendicular to the extension direction of the first connecting part. The first connecting part is provided with a groove at the upper end for placing the hooks of the end face of the core mold and the hooked ends of the yarns. The first fixing part is used to fix the first lower demolding ring. The first connecting part and the first fixing part form a shoulder for setting the second lower demolding ring. The second lower demolding ring includes a second connecting part and a second fixing part. The second connecting part is sleeved outside the first connecting part. The second fixing part is fixed to the upper end of the first fixing part. The second connecting part and the second fixing part form a shoulder for limiting the lining plate unit. The upper end of the lining plate unit is limited by the upper demolding ring. The lower end of the lining plate unit is limited by the second lower demolding ring.

[0009] Further, the inner layer of the male mold is provided with a heating rod and a temperature sensor. The heating rod is used for temperature regulation and constant temperature compensation in the forming process. The temperature sensor is used for real-time temperature measurement. The heating rod can also adjust the RTM temperature to adapt to different base materials.

[0010] Further, the bottom and the middle part of the outer female mold are both circumferentially provided with a plurality of glue injection ports, and the glue injection ports of the bottom and the middle part of the outer female mold work in sections.

[0011] Further, a plurality of first flow channels are arranged between the second lower demolding ring and the lining plate body and are in communication with the glue injection ports. The first flow channels are in communication with each other. A plurality of second flow channels are arranged in the inner wall of the lining plate body and are in communication with the glue injection ports. The second flow channels are in communication with each other. The mold is provided with two layers of annular flow channels in communication with each other. The resin flow front can always be at the same horizontal height, thereby avoiding product defects caused by uneven flow.

[0012] Further, the male mold, the outer female mold and the first lower demolding ring are all mounted on the male mold bottom plate, the male mold bottom plate is provided with a plurality of guide columns, the outer female mold is provided with a plurality of guide holes, the guide columns of the male mold bottom plate are inserted into the guide holes, so that positioning is facilitated when the female mold is mounted; the first lower demolding ring and the second lower demolding ring are both provided with a plurality of threaded holes, a bolt is used to press the first lower demolding ring from the threaded hole of the second lower demolding ring, so that the product after curing and forming is pushed out, and product demolding is realized; a bolt is used to press the male mold bottom plate from the threaded hole of the first lower demolding ring, so that the core mold is lifted, and the core mold and the male mold are separated. The lower demolding ring is divided into two parts: the first lower demolding ring and the second lower demolding ring, the second lower demolding ring is used to separate the product and the metal cover, and the first lower demolding ring is used to separate the metal cover and the male mold. The first lower demolding ring and the second lower demolding ring are both provided with a top wire hole, which is used for demolding process and disassembly.

[0013] Further, the inner wall of the outer female mold and the overall outer surface of the lining plate are both conical, and have a demolding angle.

[0014] Further, the outer female mold upper cover plate is arranged at the top of the outer female mold, and a sealing groove is arranged between the outer female mold upper cover plate and the outer female mold, between the product joint and the mold joint, between the core mold and the male mold, between the outer female mold and the male mold bottom plate, and between the core mold and the male mold bottom plate, and a sealing ring is arranged in the sealing groove.

[0015] Advantages: compared with the prior art, the present application has the following advantages: by replacing the lining plate and the joint of different sizes, the mold can be used for RTM process of products of different thicknesses and shapes; the woven core mold and the RTM male mold are combined, the preform does not need to be demolded after weaving, the process flow is simplified, and problems such as yarn sliding, deformation, diameter shrinkage and end cap collapse are avoided, thereby effectively ensuring the consistency of the design and forming process of the composite material preform. The heating rod arranged in the male mold is used for uniform heating to improve the uniformity of the temperature field in the curing process, and effectively solves the problems of curing deformation of the composite material component. The annular flow channel is used to inject resin, and product defects caused by uneven resin flow are effectively avoided. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 Fig. 1 shows the overall structure of the RTM mold in the present application;

[0017] Figure 2 Fig. 2 shows a sectional view of the RTM mold in the present application;

[0018] Figure 3 Fig. 3 shows the overall structure of the male mold bottom plate in the present application;

[0019] Figure 4 Fig. 4 shows a sectional view of the lining plate in the present application. DETAILED DESCRIPTION

[0020] As Figure 1 and Figure 2 The RTM mold suitable for multi-size axial braiding in the embodiment includes a male mold base plate 1, a male mold 2, a lower stripper ring 3, a metal cover 4, a joint, an upper stripper ring 6, a plurality of liner unit groups, an outer female mold 8, an outer female mold upper cover plate 9, a glue injection valve 10, and a glue outlet valve 11. Except for the liner, the components are connected by bolts. The male mold base plate 1 is provided with guide columns 12 for positioning when the outer female mold 8 is installed. The mold is provided with upper and lower annular flow channels, so that the resin flow front is always at the same level, avoiding product defects caused by uneven flow. The inner wall of the outer female mold 8 and the outer surface of the liner are conical in shape and have a certain demolding angle, which is convenient for loading and unloading.

[0021] The metal cover also acts as a braiding core mold. After braiding is completed, it can be directly placed in the RTM mold together with the product for impregnation process, saving the preform demolding process. In the embodiment, the metal cover 4 is provided with 48 screws at the bottom for hooking the yarn during braiding. During the RTM process, the screws together with the hooked yarn ends are placed in the grooves reserved in the lower stripper ring. The outer wall of the metal cover 4 is a cylindrical surface to ensure the size of the product after molding, and the inner wall is a conical surface with a demolding angle to facilitate separation from the male mold 2.

[0022] The outer female mold 8 is provided with a group of liner unit groups, which include a plurality of liner units 7. The liner units 7 surround the liner as a whole and are set outside the male mold 2. The liner as a whole is a split structure to facilitate separation from the product after impregnation. The liner can be replaced to realize RTM process of products 13 of various thicknesses and shapes. In the embodiment, the liner unit group includes four pieces of split structure liner units 7. After the RTM process is completed, the demolding can be achieved by splitting and peeling. The outer wall of the liner has a demolding angle, and the inner wall is a cylindrical surface, which maintains the shape of the outer surface of the product while avoiding stretching and extrusion deformation of the product during installation and demolding.

[0023] The male mold 2 is provided with a heating rod 2-1 and a temperature sensing wire 2-2 for temperature sensing and temperature control, and the RTM temperature can also be adjusted to adapt to different matrix materials.

[0024] The lower demolding ring 3 is divided into two parts: a first lower demolding ring 3-1 and a second lower demolding ring 3-2, the second lower demolding ring 3-2 is used for separating the product and the metal cover 4, and the first lower demolding ring 3-1 is used for separating the metal cover 4 and the male mold 2. The first lower demolding ring 3-1 and the second lower demolding ring 3-2 are both provided with a jack hole for demolding process and disassembly. The inner diameter of the circular ring of the second lower demolding ring 3-2 is equal to the outer diameter of the metal cover 4, and a plurality of threaded holes are arranged on the flange surface of the second lower demolding ring 3-2, so that the first lower demolding ring 3-1 can be supported by bolts, thereby pushing out the product after solidification and forming, and realizing product demolding. The outer diameter of the circular ring of the first lower demolding ring 3-1 is equal to the outer diameter of the second lower demolding ring 3-2, and a plurality of countersunk holes and threaded holes are arranged on the flange surface of the first lower demolding ring 3-1, so that the first lower demolding ring 3-1 can be fixed with the male mold bottom plate 1 by bolts, or the bolts can be installed into the threaded holes to support the male mold bottom plate 1, thereby lifting the metal cover 4 and realizing the separation of the metal cover 4 and the male mold 2.

[0025] The mold joint is installed at the center above the male mold 2, is connected with the product metal head 5 through threads, and plays a role of center positioning constraint.

[0026] The glue injection valve 10 has a total of 8, which are connected with the glue injection port and are divided into upper and lower two layers, wherein the lower layer 4 glue injection valves 10 are located on the upper part of the male mold bottom plate 1, and the upper layer 4 glue injection valves 10 are located outside the outer female mold 8. The glue outlet valve 11 has a total of 1, which is connected with the glue outlet and is located on the upper part of the female mold cover plate. In the RTM process, the molten resin flows into the mold from the glue injection valve 10, flows through the flow channel in the mold and the inside of the preform from bottom to top, and flows out from the glue outlet valve 11. In the RTM process, first, the upper layer 4 glue injection valves 10 are closed, the lower layer 4 glue injection valves 10 are used for glue injection, when the resin front passes through the upper layer glue injection valve 10, the lower layer glue injection valve 10 is closed, and the upper layer glue injection valve 10 is used for glue injection. After the molten resin enters the mold through the glue injection valve 10, it will first flow into the annular flow channel, and then enter the preform, so as to ensure that the resin front always maintains the same horizontal plane.

[0027] The male mold bottom plate 1 and the first lower demolding ring 3-1, the second lower demolding ring 3-2 and the outer female mold 8 are provided with 4 flow channels. The resin enters the inside of the mold cavity through the four glue injection valves 10 on the outer female mold 8. The second lower demolding ring 3-2 and the liner body are provided with 4 flow channels connected with each other to form a first annular flow channel 14-1. The resin flows upward and infiltrates the product in a circular manner at the lower part of the product. The inner wall of the liner body is provided with a second annular flow channel 14-2 in the middle and upper parts, which is connected with the four passages on the upper part of the outer female mold 8 through the four passages on the side wall of the liner body, and finally connected with the four glue injection ports on the upper part of the outer wall of the outer female mold 8. The function is that when the product length is long, the resin can be introduced in sections, so that the product can be more fully infiltrated with resin.

[0028] The used preform is fiber preform, glass fiber preform, aramid fiber preform, ultra-high molecular weight polyethylene fiber preform, etc.; the used curing resin is AM-8927A / B, epoxy resin, polydicyclopentadiene, etc. The viscosity of the used curing resin is usually less than 600 mPa·s, and the detection conforms to the relevant provisions of GB / T 22314-2008.

Claims

1. An RTM die suitable for multi-size axial braiding, characterized in that, The device includes an outwardly protruding male mold (2), an outer female mold (8), a demolding ring, several liner unit groups, an injection port, and an outlet. A set of liner unit groups is provided inside the outer female mold (8). The liner unit group includes several liner units (7). The liner units (7) surround and form a liner assembly that is fitted outside the male mold (2). A receiving cavity is formed between the liner assembly, the male mold, and the demolding ring. The receiving cavity is used to receive the fiber layer and the core mold (4). The injection port is connected to the receiving cavity and is used to inject glue into the receiving cavity. The outlet is connected to the receiving cavity and is used to discharge the glue that overflows from the receiving cavity. Different liner unit groups can be replaced to obtain preforms of different shapes and sizes. It also includes several product joints (5) of different sizes corresponding to different groups of liner unit groups. The demolding ring also includes an upper demolding ring (6) and a lower demolding ring. The upper end of the liner is provided with a circular outlet. The upper demolding ring (6) is provided between the circular outlets of the liner. The mold joint for setting the glue outlet is provided on the inner side of the upper demolding ring (6). The product joint (5) is sleeved on the outer side of the mold joint. The product joint is located at the lower end of the upper demolding ring (6) and is smoothly connected to the core mold (4). The lower demolding ring includes a first lower demolding ring (3-1) sleeved outside the male mold and a second lower demolding ring (3-2) sleeved outside the first lower demolding ring. The first lower demolding ring (3-1) includes a first connecting part and a first fixing part. The first connecting part is sleeved outside the male mold. The plane of the first fixing part is perpendicular to the extension direction of the first connecting part. The upper end of the first connecting part is provided with a hook for placing the end face of the core mold and a groove for hooking the end of the yarn. The first fixing part is used to fix the first lower demolding ring. The first connecting part and the first fixing part form a shoulder for setting the second lower demolding ring (3-2). The second lower demolding ring (3-2) includes a second connecting part and a second fixing part. The second connecting part is sleeved outside the first connecting part. The second fixing part is fixed to the upper end of the first fixing part. The second connecting part and the second fixing part form a shoulder for limiting the liner unit. The upper end of the liner unit is limited by the upper demolding ring, and the lower end is limited by the second lower demolding ring.

2. The RTM mold according to claim 1, characterized in that, The inner layer of the male mold is provided with a heating rod (2-1) and a temperature sensor (2-2). The heating rod is used for temperature control and constant temperature compensation during the molding process; the temperature sensor is used for real-time temperature measurement.

3. The RTM mold according to claim 1, characterized in that, The bottom and middle of the external mold are provided with several injection ports in a circumferential direction, and the injection ports at the bottom and middle of the external mold are operated in sections.

4. The RTM mold according to claim 3, characterized in that, A plurality of first flow channels communicating with the injection port are provided between the second lower demolding ring (3-2) and the liner plate as a whole, and the first flow channels are interconnected with each other; a plurality of second flow channels communicating with the injection port are provided in the middle of the inner wall of the liner plate as a whole, and the second flow channels are interconnected with each other.

5. The RTM mold according to claim 1, characterized in that, The male mold (2), the female mold (8), and the first lower demolding ring (3-1) are all installed on the male mold base plate (1). The male mold base plate (1) is provided with several guide posts (12), and the female mold is provided with several guide holes. The guide posts (12) of the male mold base plate are inserted into the guide holes to realize the positioning of the female mold (8). The first lower demolding ring (3-1) and the second lower demolding ring (3-2) are both provided with several threaded holes. The first lower demolding ring is pushed out from the threaded hole of the second lower demolding ring to push out the solidified product and realize the demolding of the product. The male mold base plate is pushed out from the threaded hole of the first lower demolding ring to push up the core mold and realize the separation of the core mold and the male mold.

6. The RTM mold according to claim 1, characterized in that, The inner wall of the external mold and the outer surface of the liner are both conical, with a demolding angle.

7. The RTM mold according to claim 5, characterized in that, A female mold top cover plate is provided on the top of the female mold. Sealing grooves are provided between the female mold top cover plate and the female mold, between the product joint and the mold joint, between the core mold and the male mold, between the female mold and the male mold base plate, and between the core mold and the male mold base plate. Sealing rings are installed in the sealing grooves.

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