Arch piece and pultrusion and mold pressing combined forming method thereof

Abstract

The invention discloses a forming method combining pultrusion and mould pressing of a bow slice, basalt fiber and glass fiber are guided and mixed, and then the mixture and a prepared gum dipping material are pultruded to form the bow slice, and the pultrusion process comprises the steps of feeding materials on a basalt fiber yarn roll and a glass fiber yarn roll which are respectively arranged on a creel; glue feeding is completed through the resin pre-soaking tank, then the glue sequentially passes through the pre-forming pultrusion die and the forming die, the glue is pulled to the cutting device to be cut by the traction device, and finally the glue is placed in the mold pressing device to be subjected to mold pressing forming. By means of high-efficiency production of the pultrusion process and combination of the mold pressing process, the modulus and strength of the bow piece are effectively improved, the porosity of the bow piece is reduced, and meanwhile the defect problems that the surface of the bow piece is sunken, and the center of the bow piece cannot be infiltrated thoroughly are solved.

Description

Technical Field

[0001] This invention relates to the field of composite material processing technology, and in particular to a bow-shaped sheet and a molding method combining pultrusion and compression molding. Background Technology

[0002] The bow limb is one of the core components of a crossbow. Currently, most mature bow limbs are made of a mixture of glass fiber and resin, known as glass limb bow limbs. Their advantages include relative inexpensiveness, durability, no maintenance requirements, moderate elasticity, and good impact resistance, making them suitable for various environments. Their disadvantages include relatively high weight, noticeable vibration, and moderate efficiency. These disadvantages of glass limb bow limbs are inherent to the material and are difficult to completely overcome; they will exist to varying degrees. However, their high cost-effectiveness makes them widely used. In addition, basalt fiber, as a newer material, can also be used in bow limb production, possessing good elastic modulus and tensile strength, but it is more expensive.

[0003] In the prior art, patent CN101491948B discloses a method for manufacturing a crossbow slat, comprising the following steps: A. Impregnating 50-70 parts by weight of fiber with 90-110 parts by weight of matrix resin; B. Pultruding the matrix resin and fiber from step A through a slat forming mold at a pultrusion speed of 10-50 cm / min to produce a semi-finished product, with the mold temperature controlled in three stages; C. Grinding and spraying the semi-finished product obtained in step B to form a slat. This invention has a simple manufacturing process, is easy to operate, and has low cost, making it suitable for widespread application.

[0004] Patent CN117841406A discloses a method for forming bow-shaped parts of basalt fiber thermosetting composite material, including the following steps: first, applying a release material to the cavity of the lower mold; then, laying the part to be injected and molded from basalt fiber; laying a breathable material on the part to be injected and molded; and then preheating the mold in an oven at 100℃~125℃ for 10 minutes. 15 minutes; Preparation of injection molding compound: Mix thermosetting resin and anhydride curing agent at a ratio of 100:88 to form a mixture, stir to obtain a resin with a viscosity of 600-800 mPa·s, maintain the temperature at 25-35℃, then inject the uniformly mixed resin into the mold cavity through the injection tube until it completely fills the part to be injection molded. After injection, close the discharge port, and then place the mold in an oven at 120℃-130℃ for 20 minutes. After 25 minutes of thermosetting, the composite bow segments are obtained by removing and cooling. This invention eliminates the need for prepreg tape, making it simple, convenient, and quick, and improving efficiency by facilitating the molding of parts.

[0005] In order to solve one of the above problems, this application provides a bow sheet and a molding method combining pultrusion and compression molding. Summary of the Invention

[0006] The purpose of this invention is to solve the problems existing in the prior art, and to propose a bow sheet and a molding method combining pultrusion and compression molding. Under the premise of high-efficiency production of pultrusion process, the combination of compression molding process effectively improves the modulus and strength of the bow sheet, reduces the porosity of the bow sheet, and also solves the defects such as surface depression of bow sheet and incomplete wetting of bow sheet center.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: a molding method combining bow sheet pultrusion and compression molding, comprising the following steps: S1. Raw material preparation: Basalt fiber yarn rolls and glass fiber yarn rolls are placed on yarn racks respectively, and basalt fiber and glass fiber are drawn out separately and mixed after being guided. The composite volume ratio of basalt fiber to glass fiber is 30:70. S2. Preparation of impregnation material: Thermosetting resin is poured into a resin prepreg tank and the temperature is maintained at 65-75°C. The thermosetting resin is selected from epoxy resin, vinyl ester resin or modified phenolic resin, and its viscosity is 13000-15000 mPa·s. The thermosetting resin is mixed with additives. S3. Pultrusion molding: The mixed fibers are sequentially fed into the resin prepreg tank, the preforming pultrusion mold and the molding mold, and after being pulled by the traction equipment, the prepreg is cut out by the cutting equipment. The temperature of the preforming pultrusion mold is controlled at 65-75℃ and the temperature of the molding mold is controlled at 75-85℃. S4. Compression molding: The cut prepreg is placed into a compression molding machine and molded for 30-35 minutes at a temperature of 150-180℃ and a pressure of 10-15 tons. After cooling, the bow sheet is obtained.

[0008] Furthermore, as described above, a yarn separating device is installed between the yarn frame and the resin prepreg tank, and the mixed fibers enter the resin prepreg tank through the yarn separating device for full impregnation.

[0009] Furthermore, as described above, several prepreg radial yarn rolls are installed on the yarn rack. Glass fiber yarn rolls and basalt fiber yarn rolls are placed separately on different prepreg radial yarn rolls or placed in proportion on the same prepreg radial yarn roll.

[0010] Furthermore, as described above, a temperature-controlled water circuit is installed at the bottom of the resin prepreg tank, which is connected to a mold temperature controller to stably control the resin temperature in the prepreg tank at 65-75℃.

[0011] Furthermore, as described above, both the preforming pultrusion die and the forming die are equipped with heating rods and temperature probes. The heating rods are used to regulate the temperature, and the temperature probes are used to monitor the temperature in real time.

[0012] Furthermore, as mentioned above, the molding die is made of chrome-plated steel.

[0013] Furthermore, the additives mentioned above are one or a mixture of two or more of the following: internal release agent, active epoxy toughening agent, flexible epoxy resin, and defoamer. The additives are used to improve the release efficiency, impact resistance, and surface smoothness of the arch plates.

[0014] Furthermore, when the additives mentioned above are a mixture, the mass ratio of each component to the thermosetting resin is as follows: 20%-30% active epoxy toughening agent, 8%-15% flexible epoxy resin, 5%-8% defoamer, and the internal release agent is adjusted according to the mold coating material, with an addition amount of 1%-5% of the thermosetting resin mass, and the addition amount does not exceed 5% of the thermosetting resin mass, so as to avoid affecting the fiber-resin interface bonding strength of the bow sheet.

[0015] A bow sheet is obtained by the aforementioned bow sheet pultrusion and molding method.

[0016] Furthermore, the bow piece as described above, by weight, comprises 50-80 parts of thermosetting resin, 30-75 parts of basalt fiber, and 5-25 parts of additives; wherein the weight ratio of basalt fiber to glass fiber matches the composite volume ratio of the two.

[0017] Compared with the prior art, the beneficial effects of the present invention are: the pultrusion process ensures the continuous, directional arrangement and initial impregnation of fibers, forming a high-quality preform; the subsequent molding process completes the final curing at higher temperatures and pressures, which can further eliminate air bubbles and compact the composite material, thereby synergistically improving the modulus and strength, and significantly reducing porosity.

[0018] The high pressure of the molding process forces the resin to flow and completely fill the mold cavity, thus eradicating the stubborn problems such as "surface depression" and "incomplete center wetting" caused by resin shrinkage or poor flow.

[0019] The specific volume ratio of basalt fiber to glass fiber (30:70) effectively improves the overall performance of the product by utilizing the high modulus of basalt fiber without excessively increasing costs, thus optimizing the cost-effectiveness.

[0020] Precise control of process parameters (resin viscosity, mold temperature, molding pressure / time) ensures process stability, resulting in good product consistency and a high pass rate. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the production line of the present invention.

[0022] In the diagram: 1. Yarn frame; 2. Yarn separating device; 3. Resin prepreg tank; 4. Preforming pultrusion mold; 5. Molding mold; 6. Traction equipment; 7. Cutting equipment; 8. Molding equipment; 9. Heating rod; 10. Temperature probe. Detailed Implementation

[0023] In the description of this invention, it should be understood that the terms "upper," "lower," "front," "rear," "left," "right," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0024] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "fixed," "installed," "connected," "set," etc., should be interpreted broadly. For example, when an element is said to be "fixed to" another element, it can be directly on the other element or there may be an intervening element. When an element is said to be "installed" on another element, it can be directly installed on the other element or there may be an intervening element. When an element is said to be "connected" to another element, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a communication between the two elements.

[0025] Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Example 1 Reference Figure 1 As shown, the present invention provides a molding method combining pultrusion and compression molding of bow plates, combining... Figure 1It is known that the core equipment used is: yarn frame 1 (containing several prepreg radial yarn bobbins, with glass fiber yarn rolls and basalt fiber yarn rolls placed separately on different prepreg radial yarn bobbins or placed in proportion on the same prepreg radial yarn bobbin), yarn separating device 2, resin prepreg tank 3 (with a temperature-controlled water circuit installed at the bottom, which is connected to the mold temperature controller to stably control the resin temperature in the prepreg tank at 65-75℃), preforming pultrusion mold 4, molding mold 5 (made of chrome-plated steel), traction equipment 6, cutting equipment 7, and molding equipment 8. Among them, the preforming pultrusion mold and the molding mold are equipped with heating rods 9 (for temperature control operation) and temperature probes 10 (for real-time temperature measurement).

[0028] Step S1. Fiber Preparation Continuous basalt fiber (preferably 600TEX, density 2.6-2.8 g / cm³) and continuous glass fiber (preferably 600TEX, density 2.5-2.6 g / cm³) are selected as reinforcing materials. The two types of fiber yarn rolls are placed on the pre-impregnated radial yarn bobbins of the yarn rack, and the basalt fiber and glass fiber are drawn out respectively. The fiber direction is adjusted by the guide roller to make the basalt fiber and glass fiber uniformly mixed at a volume ratio of 30:70 (the tension of each fiber can be adjusted by the tension controller on the yarn rack to ensure a stable mixing ratio).

[0029] Step S2. Preparation of impregnation material When selecting thermosetting resins, epoxy resins (such as E-51 epoxy resin, which has good compatibility with fibers and excellent mechanical properties after curing) should be given priority. Vinyl ester resin (with excellent corrosion resistance) or modified phenolic resin (with excellent high temperature resistance) can also be selected according to the application requirements.

[0030] Additives are added to thermosetting resins to improve the demolding efficiency, impact resistance, and surface smoothness of the arch plates. These additives can include internal release agents (such as zinc stearate, for easy demolding after molding), active epoxy toughening agents (such as polyetheramine toughening agents, to improve arch plate toughness), flexible epoxy resins (such as carboxyl-terminated nitrile rubber modified epoxy resin, to reduce brittleness), and defoamers (such as silicone defoamers, to reduce air bubbles during impregnation). When using mixed additives, the mass ratio of each component to the thermosetting resin is: active epoxy toughening agent 20%-30%, flexible epoxy resin 8%-15%, defoamer 5%-8%, and the internal release agent is adjusted according to the mold coating material, with an addition amount of 1%-5% of the thermosetting resin mass, and not exceeding 5% of the thermosetting resin mass to avoid affecting the fiber-resin interface bonding strength of the arch plates.

[0031] Resin preparation and temperature control: Mix the thermosetting resin and additives, and stir at 25-30℃ for 15-20 minutes to ensure uniform mixing. After preparation, the resin viscosity should be controlled at 13000-15000 mPa·s (tested at room temperature of 25℃ using a rotational viscometer). Pour the prepared resin into the resin prepreg tank, and stabilize the temperature in the tank at 65-75℃ using a heating device (at this temperature, the resin has moderate fluidity, which can fully impregnate the fiber and avoid premature curing).

[0032] Step S3. Pultrusion molding For mold preparation, the length of the preforming pultrusion mold is controlled at 30-50cm (for initial shaping of fiber morphology), and the length of the molding mold is controlled at 80-150cm (for resin curing and dimensional fine-tuning). The temperature of the preforming pultrusion mold is raised to 65-75℃ and the temperature of the molding mold is raised to 75-85℃ using a heating rod, and the temperature is monitored in real time using a temperature probe, with the temperature fluctuation range controlled within ±2℃.

[0033] In the pultrusion process, the mixed fibers are separated by a yarn separating device (to ensure uniform fiber dispersion and avoid entanglement) and then enter the resin prepreg tank. The impregnation time is controlled at 3-5 minutes to ensure that each yarn is fully coated with resin. The impregnated fibers enter the preforming pultrusion mold, where the guiding structure scrapes away excess resin (controlling the resin volume ratio to 30%-33%) and initially shapes it into a bow-shaped preform. The bow-shaped preform then enters the molding mold, where the resin is initially cured at a set temperature (curing degree reaches 60%-70%). Finally, it is pulled out of the molding mold by a traction device (traction speed 1-2 m / min to ensure molding stability) and cut into prepreg lengths of 50-100 cm by a cutting device (adjusted according to the final bow-shaped dimensions).

[0034] Step S4. Compression molding Prepreg pretreatment: Place the cut prepreg at room temperature for 10-15 minutes to allow the resin to penetrate more evenly.

[0035] Molding parameter settings: The upper and lower molds of the molding equipment are equipped with heating devices to raise the temperature to 150-180℃. After the upper and lower molds are closed, apply 10-15 tons of pressure (adjust according to the thickness of the bow piece; 10-12 tons for a thickness of 3-5mm and 12-15 tons for a thickness of 5-8mm).

[0036] Compression curing is performed at the set temperature and pressure for 30-35 minutes to allow the resin to fully cure (curing degree ≥95%). After curing, the temperature is lowered to below 60℃ before the mold is opened and the bow piece is removed. The finished bow piece can be obtained without secondary modification.

[0037] The resulting bow limb, by weight, comprises 50-80 parts thermosetting resin, 30-75 parts basalt fiber, and 5-25 parts additives. The weight ratio of basalt fiber to glass fiber matches the composite volume ratio (based on fiber density conversion, with basalt fiber density calculated at 2.6-2.8 g / cm³ and glass fiber density at 2.5-2.6 g / cm³). The "composite volume ratio" refers to the volume percentage of fiber in the preform, while the "weight parts" refers to the mass proportion of each component in the final bow limb. The two are correlated through fiber density and resin retention rate during the process.

[0038] Example 2 Reference Figure 1 As shown, based on the technical solution of Embodiment 1, a molding method combining bow sheet pultrusion and molding is provided. First, glass fiber yarn rolls and basalt fiber yarn rolls are prepared. The yarn rolls required for pultrusion are divided into two parts: the upper part of the yarn frame is made of glass fiber yarn, and the lower part of the yarn frame is made of basalt fiber.

[0039] Using 600TEX (a unit of linear density for yarn or fiber, where 1TEX equals the weight per 1000 meters of fiber) continuous basalt fiber and 600TEX continuous glass fiber yarn as reinforcing materials, mixed additives are added to epoxy resin. The mass ratio of each additive component to the epoxy resin is as follows: 20% active epoxy toughening agent, 10% flexible epoxy resin, 5% defoamer, and 2% internal release agent. The mixture is stirred at 25-30℃ for 15-20 minutes to obtain a mixed resin with a viscosity of 13000-15000 mPa·s, which is then poured into a resin prepreg tank maintained at 65-75℃. Eight holes are opened in the upper and lower molds of the preforming pultrusion mold and the molding mold to place heating rods and temperature probes. The heating rods of the preforming pultrusion mold are then heated to 70℃, and the heating rods of the molding mold are heated to 80℃.

[0040] Basalt fiber and glass fiber are mixed at a volume ratio of 30:70 and then fed into a resin prepreg tank via a yarn separating device. The impregnation time is controlled at 4 minutes to ensure that each yarn is fully coated with resin. The impregnated fibers are then fed into a 50 cm long preforming pultrusion mold. The flow guiding structure inside the preforming pultrusion mold scrapes away excess resin (controlling the resin volume ratio to 30%) and initially shapes it into a bow-shaped preform. The preform is then fed into a 100 cm long molding mold, where the resin is initially cured at a set temperature (curing degree reaches 65%). Finally, the prepreg is pulled out of the mold by a traction device (traction speed 1.5 m / min) and cut into 80 cm long pieces by a cutting device.

[0041] The prepreg produced by the pultrusion process is left at room temperature for 15 minutes, and then placed into the lower mold of the molding equipment. After the upper and lower molds of the molding equipment are closed, the resin is molded for 30 minutes at a temperature of 160℃ and a pressure of 12 tons to allow the resin to fully cure (curing degree ≥95%). After cooling down to below 60℃, the mold is opened and the 5 mm thick arch sheet is removed.

[0042] Example 3 Reference Figure 1 As shown, based on the technical solution of the above embodiments, a molding method combining bow sheet pultrusion and compression molding is provided, wherein the proportion of each component of the mixed additive is adjusted, while other conditions remain unchanged.

[0043] Under the condition that other conditions remain unchanged in Example 2, the bow sheet sample 1 obtained by using only glass fiber and the bow sheet sample 2 obtained by using only basalt fiber, with basalt fiber and glass fiber mixed at a ratio of 30:70, have a cost reduction of 40%-50% compared to bow sheet sample 2, while the performance is better than that of bow sheet sample 1.

[0044] Compared to existing technologies that directly inject resin into molding dies to mix fibers, bow pieces produced through a pultrusion + molding composite process exhibit reduced porosity, increased elastic modulus, enhanced tensile strength, and a surface flatness error of ≤0.1mm, free from defects such as depressions and incomplete center impregnation. The pultrusion process enables continuous prepreg production, significantly improving production efficiency compared to pure molding, while also ensuring good product consistency and a high pass rate. Furthermore, by adjusting the ratio of the two fibers, resin type, and molding parameters, the process can adapt to the performance requirements of different bow and crossbow specifications (such as competition bows and composite bows), making it widely applicable.

[0045] The components of this invention are ordered according to demand. The raw materials and additives are existing technologies or materials. The relevant technical personnel can directly purchase or order them from the market according to the required product model and specifications.

[0046] All electrical components mentioned in the text are connected to an external main controller and 220V AC mains power or industrial power. The main controller can be a conventional known device such as a computer that plays a control role.

[0047] The above description is merely a preferred embodiment of the present invention, and common knowledge regarding specific structures and characteristics in the solutions is not described in detail here. It will be apparent to those skilled in the art that the present invention is not limited to the details of the above embodiments, and that the present invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered exemplary and non-limiting in all respects. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in this invention, based on the technical solutions and inventive concepts of the present invention, should be covered within the protection scope of this invention.

Claims

1. A molding method combining pultrusion and compression molding of bow plates, characterized in that, Includes the following steps: S1. Raw material preparation: Place basalt fiber yarn rolls and glass fiber yarn rolls on a yarn rack (1), draw out the fibers separately, and mix them in a volume ratio of 30:70 after guiding. S2. Preparation of impregnation material: Pour thermosetting resin into resin prepreg tank (3) and keep the temperature at 65-75℃. The thermosetting resin is selected from epoxy resin, vinyl ester resin or modified phenolic resin, with a viscosity of 13000-15000 mpa.s, and the thermosetting resin is mixed with additives. S3. Pultrusion molding: The mixed fibers are sequentially fed into the resin prepreg tank, the preformed pultrusion mold (4) and the molding mold (5), and after being pulled by the traction device (6), the prepreg is cut out by the cutting device (7). The temperature of the preformed pultrusion mold is controlled at 65-75℃ and the temperature of the molding mold is controlled at 75-85℃. S4. Compression molding: The cut prepreg is placed into the compression molding equipment (8) and molded for 30-35 minutes at a temperature of 150-180℃ and a pressure of 10-15 tons. After cooling, the bow sheet is obtained.

2. The forming method combining pultrusion and compression molding of bow plates according to claim 1, characterized in that, A yarn separating device (2) is installed between the yarn frame and the resin prepreg tank. The mixed fibers enter the resin prepreg tank through the yarn separating device and are fully impregnated.

3. The forming method combining pultrusion and compression molding of bow plates according to claim 2, characterized in that, The yarn rack is equipped with several pre-impregnated radial yarn rolls. Glass fiber yarn rolls and basalt fiber yarn rolls are placed separately on different pre-impregnated radial yarn rolls or placed in proportion on the same pre-impregnated radial yarn roll.

4. The molding method combining pultrusion and compression molding of bow plates according to claim 1, characterized in that, The bottom of the resin prepreg tank is equipped with a temperature-controlled water circuit, which is connected to a mold temperature controller to stably control the resin temperature in the prepreg tank at 65-75℃.

5. The forming method combining pultrusion and compression molding of bow plates according to claim 1, characterized in that, Heating rods (9) and temperature probes (10) are installed in both the preforming pultrusion mold and the forming mold. The heating rods are used to regulate the temperature, and the temperature probes are used to monitor the temperature in real time.

6. The forming method combining pultrusion and compression molding of bow plates according to claim 5, characterized in that, The molding die is made of chrome-plated steel.

7. The forming method combining pultrusion and compression molding of bow plates according to claim 1, characterized in that, The additive is one or a mixture of two or more of the following: internal release agent, active epoxy toughening agent, flexible epoxy resin, and defoamer.

8. The forming method of combining pultrusion and compression molding of bow plates according to claim 7, characterized in that, When the additives are a mixture, the mass ratio of each component to the thermosetting resin is as follows: 20%-30% active epoxy toughening agent, 8%-15% flexible epoxy resin, 5%-8% defoamer, and 1-5% internal release agent.

9. A bow limb, characterized in that, The bow sheet is obtained by a molding method combining pultrusion and compression molding as described in any one of claims 1-8.

10. A bow limb according to claim 9, characterized in that, The bow plate, by weight, comprises 50-80 parts of thermosetting resin, 30-75 parts of basalt fiber, and 5-25 parts of additives; wherein the weight ratio of basalt fiber to glass fiber matches the composite volume ratio of the two.

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