Quench and chill rapid compression molding tooling and method for thermoplastic prepreg articles

Abstract

This invention discloses a rapid heating and cooling molding die and method for thermoplastic prepreg products, comprising a template, a mold core, and first pads; wherein the template includes an upper template and a lower template; wherein the mold core includes an upper mold core and a lower mold core; a plurality of first pads are disposed between the upper mold core and the lower mold core; between the upper template and the upper mold core, an upper cooling plate and a first electromagnetic heating plate for heating the upper mold core are sequentially disposed; between the lower template and the lower mold core, a lower cooling plate and a second electromagnetic heating plate for heating the lower mold core are sequentially disposed. This invention enables rapid heating and rapid cooling, and allows the same mold to produce prepreg products of various thicknesses, exhibiting high versatility and flexibility; it also allows for flexible adjustment of deformation, effectively reducing the problem of thermal deformation of the mold, ensuring greater uniformity of product thickness, and offering high ease of use.

Description

Technical Field

[0001] This invention belongs to the field of thermoplastic composite prepreg product molding technology, specifically relating to molding dies and methods for preparing thermoplastic prepreg products. Background Technology

[0002] Carbon fiber reinforced resin matrix composites possess excellent specific strength, specific modulus, corrosion resistance, and energy absorption properties, playing an increasingly important role in the automotive, rail transportation, and aerospace industries. Thermoplastic composites, with their high impact resistance, recyclability, resistance to various organic solvents, and low specific gravity, have gradually become well-known. However, the high viscosity of thermoplastic resins makes molding difficult, and finding simple, easy, and low-cost manufacturing processes has always been a research focus in the field of modern composite materials. The molding process for continuous fiber thermoplastic composite products is particularly challenging.

[0003] Compared to thermoplastic composites, epoxy prepreg molding processes have evolved over many years, resulting in various stable and scalable technologies such as tube winding, compression molding, autoclave molding, and filament winding. In contrast, thermoplastic prepreg molding processes are relatively immature, with fewer options available. Currently, the two main molding processes are laser winding and compression molding. The biggest obstacle limiting the manufacture of thermoplastic prepreg products is the processing temperature; commonly used thermoplastic prepregs require molding temperatures above 350℃, significantly higher than thermosetting materials.

[0004] In recent years, the carbon fiber industry has developed rapidly, but the development laws of the carbon fiber industry have been ignored. Low-level repetitive construction has led to a low level of industrial concentration, specifically manifested in severe low-level and homogenized phenomena; small-scale production lines, with most companies having only a production capacity of a few hundred tons; and a significant gap between the industry and advanced levels in terms of technology, equipment, and downstream product development and application. Therefore, developing high-performance prepreg composite molding equipment and breaking through product upgrading is an urgent task for the prepreg industry to develop towards high-end products and industrial security. Summary of the Invention

[0005] Purpose of the invention: In order to overcome the shortcomings of the prior art, the present invention provides a rapid cooling and heating molding die for preparing thermoplastic prepreg products, and also provides a rapid cooling and heating molding method for preparing thermoplastic prepreg products.

[0006] Technical solution: The present invention provides a rapid cooling and heating molding die for thermoplastic prepreg products, which includes a template, a mold core and a first pad;

[0007] The template includes an upper template and a lower template; the mold core includes an upper mold core and a lower mold core; a plurality of the first pad blocks are disposed between the upper mold core and the lower mold core;

[0008] Between the upper template and the upper mold core, an upper cooling plate and a first electromagnetic heating plate for heating the upper mold core are also provided in sequence;

[0009] Between the lower template and the lower mold core, a lower cooling plate and a second electromagnetic heating plate for heating the lower mold core are also provided in sequence.

[0010] Preferably, the first electromagnetic heating plate is provided with a first electromagnetic coil, which is connected to a high-frequency current generator; the second electromagnetic heating plate is provided with a second electromagnetic coil, which is connected to a high-frequency current generator.

[0011] Preferably, both the upper cooling plate and the lower cooling plate are water-cooled plates.

[0012] Preferably, the upper cooling plate is further provided with a third high-pressure water cooling pipe; the third high-pressure water cooling pipe is a one-way straight pipe that penetrates the upper cooling plate; the lower cooling plate is further provided with a fourth high-pressure water cooling pipe; the fourth high-pressure water cooling pipe is a one-way straight pipe that penetrates the lower cooling plate.

[0013] Preferably, a first thermocouple is provided in the middle of the upper mold core, and the first thermocouple is signal-connected to the first electromagnetic heating plate; a second thermocouple is provided in the middle of the lower mold core, and the second thermocouple is signal-connected to the second electromagnetic heating plate.

[0014] Further preferably, the upper mold core is also provided with a first high-pressure water cooling pipe; the first high-pressure water cooling pipe is a one-way straight pipe that penetrates the mold; the lower mold core is also provided with a second high-pressure water cooling pipe; the second high-pressure water cooling pipe is a one-way straight pipe that penetrates the mold.

[0015] More preferably, the mold core is a male and female mold comprising an upper mold core and a lower mold core, wherein the lower mold core located below is a concave mold and the upper mold core located above is a convex mold.

[0016] Further preferably, several first pads disposed between the upper mold core and the lower mold core are replaceable or adjustable first pads.

[0017] Preferably, the first pads are evenly distributed around the periphery where the upper mold core and the lower mold core meet.

[0018] Preferably, the thickness of the first pad is 0.5 to 10 mm.

[0019] Preferably, the template and mold core are made of air-cooled hardening hot work die steel; the template and mold core have a surface hardness of 50-70 HRC.

[0020] Preferably, the first electromagnetic coil is evenly distributed on the first electromagnetic heating plate; the second electromagnetic coil is evenly distributed on the second electromagnetic heating plate.

[0021] More preferably, the upper cooling plate and the upper template are connected by a plurality of second pads; the lower cooling plate and the lower template are connected by a plurality of second pads.

[0022] Preferably, the width of the plurality of second pads is 1 to 10 cm.

[0023] Preferably, the spacing between adjacent second pads is 1 to 10 cm.

[0024] Preferably, each second pad is fixed to the corresponding upper or lower cooling plate using M10 countersunk bolts.

[0025] More preferably, it also includes a heat-induced deformation correction structure; the heat-induced deformation correction structure includes:

[0026] Several first fastening screws located in the middle of the mold, these screws sequentially pass through the upper mold plate, the upper cooling plate, and the first electromagnetic heating plate, and are then fastened to threaded inner holes in the upper mold core; and

[0027] Several second fastening screws are located in the middle of the mold. These screws pass through the lower template, the lower cooling plate, and the second electromagnetic heating plate in sequence, and are then fastened to the threaded inner hole on the lower mold core.

[0028] The first fastening screw causes the upper mold core to deform through the tightening force; the second fastening screw causes the lower mold core to deform through the tightening force.

[0029] Preferably, the thickness of the upper and lower templates is greater than or equal to 7 cm.

[0030] Preferably, the upper template and the upper cooling plate are heat-insulated from each other; the lower template and the lower cooling plate are heat-insulated from each other.

[0031] This invention also provides a rapid cooling and heating molding method for thermoplastic prepreg articles, which uses any of the rapid cooling and heating molding dies described above, and includes the following steps:

[0032] Step 1): After the thermoplastic prepreg is cut and stacked, it is placed into the rapid molding die. The thickness of the finished prepreg is controlled by adjusting the thickness of the first pad. When the rapid molding die is closed, only contact pressure is applied instead of full pressure, and electromagnetic heating is started at the same time for rapid heating.

[0033] Step 2): When the rapid molding die reaches the preset temperature threshold, it is kept warm for a preset time so that the temperature of the die can be conducted to the prepreg, thereby melting the resin therein.

[0034] Step 3): Close the rapid molding die, apply full pressure and vacuum, so that the prepreg is formed in the heated extrusion process;

[0035] Step 4): After the product is formed, cool water is injected into the one-way straight high-pressure water cooling pipes of the upper and lower water cooling plates for rapid cooling and shaping.

[0036] Step 5): Open the mold and remove the product.

[0037] More preferably, the above-mentioned rapid cooling and heating molding method for thermoplastic prepreg products further includes the following steps:

[0038] The thermal deformation of the upper mold core is corrected by adjusting the torque of several first fastening screws, thus achieving the deformation of the upper mold core; and

[0039] The thermal deformation of the lower mold core is corrected by adjusting the torque of several second fastening screws, thus achieving the deformation of the lower mold core.

[0040] More preferably, in step 1), the heating rate for rapid heating by starting electromagnetic heating is 10-50℃ / min; and in step 4), the cooling rate for rapid cooling and shaping is 20-80℃ / min.

[0041] More preferably, in step 4), after the product is formed, while injecting cooling water into the one-way direct high-pressure water cooling pipes of the upper and lower water cooling plates, cooling water is also injected into the one-way direct high-pressure water cooling pipes of the upper and lower mold cores for rapid cooling and shaping.

[0042] Beneficial effects: The rapid cooling and heating molding die and molding method for preparing thermoplastic prepreg products provided by this invention have the following advantages compared with the prior art:

[0043] (1) High-melting-point and high-viscosity resin can achieve full melting and flow again during the product molding process. The resin melt impregnates the fiber more evenly and effectively reduces the air bubble porosity in the product through extrusion, thus greatly reducing the presence of air bubbles.

[0044] (2) This rapid heating and cooling molding die can meet the requirements of rapid heating, effectively solving the problem that the temperature of the mold is not high enough due to the heating of the mold temperature oil, and the thermoplastic prepreg resin cannot reach the processing temperature; at the same time, the heating rate can reach 10-50℃ / min, which improves the heating speed and effectively alleviates the problem that the original slow heating speed affects the production cycle, as well as the problem that the prepreg resin undergoes thermal oxidation side reaction during the long heating waiting process.

[0045] (3) Rapid cooling of thermoplastic prepreg products is achieved. The cooling rate can reach 20-80℃ / min, which effectively avoids the problem of thermal degradation caused by waiting for the mold to cool down for a long time. At the same time, it effectively reduces the crystallinity of crystalline resin during production, improves toughness, and effectively reduces the problem of slow crystallization of resin caused by slow cooling of products, which leads to a decrease in product performance.

[0046] (4) By using several replaceable or adjustable first pads between the upper mold core and the lower mold core, the thickness of the first pads can be flexibly changed / adjusted, so that the same mold can produce a variety of prepreg products with different thicknesses, which has high versatility and flexibility.

[0047] (5) Based on the structure provided by the present invention, the torque of several first fastening screws can be flexibly adjusted to correct the thermal deformation of the upper mold core and achieve the deformation of the upper mold core. Correspondingly, the torque of several second fastening screws can be flexibly adjusted to correct the thermal deformation of the lower mold core and achieve the deformation of the lower mold core. Based on this thermal deformation correction structure, the corresponding upper and lower mold cores can be deformed by the reverse pulling of the fastening screws / bolts, and the corresponding deformation can be flexibly adjusted, effectively reducing the problem of thermal deformation of the mold and ensuring the uniformity of the product thickness to a greater extent.

[0048] (6) In the structural design provided by the present invention, in order to effectively avoid the thermal deformation of the upper and lower templates themselves from offsetting the above-mentioned tensile deformation / deformation amount: on the one hand, the upper and lower templates themselves are thicker than 7cm, which can effectively ensure that the upper and lower templates will not be deformed by reverse tension; on the other hand, a second pad is used to connect the upper and lower cooling plates and the upper and lower templates, thereby effectively reducing the contact surface between the upper cooling plate and the upper template, as well as between the lower cooling plate and the lower template. The upper template and the upper cooling plate are mutually insulated, the lower template and the lower cooling plate are mutually insulated, and the upper and lower cooling plates are temperature-barriered to the upper and lower templates, which further enhances the heat barrier effect, minimizes heat conduction, effectively reduces the amount of mold deformation due to heat, and ensures to the greatest extent that the upper and lower templates themselves will not undergo thermal deformation due to heat or offset the above-mentioned tensile deformation / deformation amount; at the same time, by limiting the size and spacing of the second pads, the barrier pads are reasonably combined and arranged to ensure that the cooling plates are less or even not deformed by compression to the greatest extent. Based on the above-mentioned structure, the rapid cooling and heating molding die provided by the present invention remains stable even when the working temperature is as high as 300-450℃, effectively solving the problem that the die is severely deformed due to excessive heating temperature, which affects the thickness accuracy of the product.

[0049] (7) Based on the structure provided by the present invention, the upper mold is composed of three modules: upper mold core, first electromagnetic heating plate and upper cooling plate. The lower mold also includes three modules: lower mold core, second electromagnetic heating plate and lower cooling plate. This facilitates equipment installation and subsequent maintenance, and has high convenience and ease of use. Attached Figure Description

[0050] Figure 1 This is a schematic diagram of the overall structure of one of the rapid cooling and heating molding dies provided in the embodiment;

[0051] Figure 2 for Figure 1 The provided exploded view of the structure of the rapid cooling and heating molding die;

[0052] Figure 3 for Figure 2 Schematic diagram of the upper and middle mold core;

[0053] Figure 4 for Figure 2 A schematic diagram of the structure of the lower mold (including the lower mold core, the second electromagnetic heating plate, and the lower cooling plate);

[0054] Figure 5 (a) is Figure 2 A schematic diagram of the structure of the first electromagnetic heating plate in the middle;

[0055] Figure 5(b) is Figure 2 Schematic diagram of the structure of the second electromagnetic heating plate;

[0056] Figure 6 (a) is Figure 2 Schematic diagram of the upper and middle cooling plates;

[0057] Figure 6 (b) is Figure 2 Schematic diagram of the middle and lower cooling plates;

[0058] Figure 7 This is a schematic assembly diagram of one type of upper mold core and lower mold core provided in the embodiment;

[0059] Figure 8 for Figure 1 Schematic diagram of the structure of the middle and lower mold and the lower template;

[0060] Figure 9 This is a schematic diagram of a thermal deformation correction structure in a rapid heating and cooling molding die provided in the embodiment.

[0061] Figure 10 for Figure 8 Schematic front view of the structure;

[0062] Figure 11 for Figure 10 A schematic cross-sectional view of the AA-direction structure. Detailed Implementation

[0063] The technical solution of the present invention will be further described in detail below with reference to the embodiments and accompanying drawings.

[0064] This embodiment provides a rapid cooling and heating molding die for preparing thermoplastic prepreg products, such as... Figure 1 and Figure 2 As shown, it includes a template, a mold core, and a first pad block;

[0065] The template includes an upper template 11 and a lower template 21; the mold core includes an upper mold core 14 and a lower mold core 24; and a plurality of the first pad blocks 3 are disposed between the upper mold core 14 and the lower mold core 24.

[0066] Between the upper template 11 and the upper mold core 14, an upper cooling plate 12 and a first electromagnetic heating plate 13 for heating the upper mold core 14 are also provided in sequence.

[0067] Between the lower template 21 and the lower mold core 24, a lower cooling plate 22 and a second electromagnetic heating plate 23 for heating the lower mold core 24 are also provided in sequence.

[0068] In this embodiment, the upper mold includes, from top to bottom, an upper cooling plate 12, a first electromagnetic heating plate 13, and an upper mold core 14; the lower mold includes, from bottom to top, a lower cooling plate 22, a second electromagnetic heating plate 23, and a lower mold core 24; the first electromagnetic heating plate 13 is used to heat the upper mold core 14; the second electromagnetic heating plate 23 is used to heat the lower mold core 24.

[0069] The upper template 11 and the lower template 21 are fixedly connected by bolts. In this embodiment, the upper template 11 and the lower template 21 are fixedly connected by settlement bolts.

[0070] Based on the above structural construction, such as Figure 2 , Figure 3 , Figure 4 , Figure 7 and Figure 8 As shown, in the rapid heating and cooling molding die provided by this invention, the upper die is divided into an upper die core, a first electromagnetic heating plate, and an upper cooling plate (also known as an upper water cooling plate), and the lower die is divided into a lower die core, a second electromagnetic heating plate, and a lower cooling plate (also known as a lower water cooling plate). Because the electromagnetic coil has high power during operation and needs to withstand high temperatures for a long time, the part of the die prone to failure is the electromagnetic heating part. Based on the above-mentioned die-splitting structure, it is convenient for the initial electromagnetic coil arrangement and construction, and also facilitates the diagnosis and maintenance when the electromagnetic coil fails later, effectively improving the usability and maintainability of the die.

[0071] This invention enables thermoplastic resin to be fully melted in a short time and then impregnated into fiber bundles through secondary extrusion. The resin is then rapidly cooled by cooling water, which slows down the cooling and crystallization of crystalline resin, thereby obtaining thermoplastic prepreg products with good impregnation effect and appearance.

[0072] In this invention, the template and mold core are made of air-hardening hot work die steel such as H11 or H13 American air-hardening hot work die steel; in the mold material provided in this embodiment, after the metal material is heat-treated, the template and mold core are templates and mold cores with a surface hardness of 50 to 70 HRC.

[0073] In the rapid cooling and heating molding die provided in this embodiment, such as Figure 5 (a) and Figure 5 As shown in (b), the first electromagnetic heating plate 13 is provided with a first electromagnetic coil, which is connected to a high-frequency current generator; the second electromagnetic heating plate 23 is provided with a second electromagnetic coil, which is connected to a high-frequency current generator.

[0074] The first electromagnetic coil is evenly distributed on the first electromagnetic heating plate 13; the second electromagnetic coil is evenly distributed on the second electromagnetic heating plate 23. In some embodiments, specifically, the first electromagnetic heating plate 13 has an S-shaped groove, and the first electromagnetic coil is disposed in the S-shaped groove; the second electromagnetic heating plate 23 has an S-shaped groove, and the second electromagnetic coil is disposed in the S-shaped groove.

[0075] In this embodiment, the input and output terminals (also referred to as input and output) of the first and second electromagnetic coils (also referred to as the first and second heating coils, or the first and second electromagnetic heating coils) are connected to an external high-frequency current device. By adjusting the current power, the heating rate of the corresponding upper and lower mold cores is controlled, thereby flexibly and effectively controlling the heating rate of the entire mold. Specifically, in this embodiment, when the current power is set to 55KW, it takes approximately 40 minutes to heat from room temperature to 380℃. Multiple locations were measured, and the temperature difference between the diagonal and opposite sides was approximately 10-15℃; the temperature difference between the center and the surrounding areas was 5-10℃.

[0076] Based on this structural design, this mold can be rapidly heated to a temperature, such as 200–500°C, using electromagnetic coils. When the heating coils are evenly distributed inside the mold, the heating is more uniform. In this invention, the heating coils are connected to a high-frequency current generator. Inputting a high-frequency current causes the corresponding heating coil to heat up, which in turn heats the corresponding electromagnetic heating plate. The mold heating principle in this invention utilizes induction heating (electromagnetic induction heating, similar to an induction cooker). The mold's heating rate depends on the input current power, which can range from 5 to 100 kW.

[0077] In the rapid cooling and heating molding die provided in this embodiment, a first thermocouple 15 is provided in the middle of the upper mold core 14, and the first thermocouple 15 is connected to the first electromagnetic heating plate 13 by signal; a second thermocouple 25 is provided in the middle of the lower mold core 24, and the second thermocouple 25 is connected to the second electromagnetic heating plate 23 by signal.

[0078] In this embodiment, under this structure and configuration, the temperature data of the first / second thermocouples inserted on the upper / lower mold cores can be read in real time through a system such as a PLC system. This allows for more flexible control of the electromagnetic heating current, duration, and interval period, enabling the use of either continuous high-current output or intermittent current output to ensure stable heating temperature. Alternatively, during initial operation, the device can be made to output maximum current via analog signals to meet the need for rapid heating. By combining the real-time temperature data of the first / second thermocouples, and once the temperature approaches the target temperature, intermittent current output can be flexibly adopted to maintain stable heating temperature.

[0079] In the rapid cooling and heating molding die provided in this embodiment, such as Figure 6 (a) and Figure 6 As shown in (b), both the upper cooling plate 12 and the lower cooling plate 22 are water cooling plates;

[0080] The upper cooling plate 12 is also provided with a third high-pressure water cooling pipe 17; the third high-pressure water cooling pipe 17 is a one-way straight pipe that penetrates the upper cooling plate 12; the lower cooling plate 22 is also provided with a fourth high-pressure water cooling pipe 27; the fourth high-pressure water cooling pipe 27 is a one-way straight pipe that penetrates the lower cooling plate 22.

[0081] The term "penetration" here refers to drilling the pipe-related hole directly from one side of the component to the other, rather than using an S-shaped bend. This is because the mold operates at a high temperature, and an S-shaped bend would cause a large amount of water to vaporize, which would be detrimental to the subsequent injection of water into the cold zone.

[0082] The upper cooling plate 12 and the upper template 11 are connected by a number of second pads 4; the lower cooling plate 22 and the lower template 21 are connected by a number of second pads 4.

[0083] In this invention, the width of the aforementioned second pads 4 is 1 to 10 cm; the spacing between adjacent second pads 4 is 1 to 10 cm; each second pad 4 is fixed to the corresponding upper or lower cooling plate with an M10 countersunk bolt.

[0084] In this invention, both the upper and lower cooling plates are equipped with high-pressure water-cooled pipes, which are also unidirectional straight-through pipes (also known as unidirectional high-pressure water-cooled straight-through pipes). The upper and lower cooling plates simultaneously serve to cool the corresponding first and second electromagnetic heating plates and prevent heat transfer to the external press. During the molding process, before the product is formed, the upper and lower cooling plates do not circulate cooling water for cooling.

[0085] To further enhance the heat insulation effect, second pads 4 are used to connect the upper / lower cooling plates and the upper / lower templates in this invention. This effectively reduces the contact area between the upper cooling plate 12 and the upper template 11, as well as between the lower cooling plate 22 and the lower template 21, thus more effectively achieving the heat insulation function. In this invention, the width of the second pads 4 is 1-10 cm, and the second pads 4 are arranged in combinations with a spacing of 1-10 cm between adjacent pairs. This ensures that heat transfer is minimized and that the cooling plates experience minimal or no extrusion deformation. Furthermore, in this embodiment, each second pad is fixed to the corresponding cooling plate using M10 countersunk bolts.

[0086] In this invention, it is important to emphasize that during the heating and molding process, cooling water is not circulated through the upper and lower cooling plates; cooling water is only circulated through the upper and lower cooling plates to cool the mold. That is, when the mold is heated, the upper and lower cooling plates are not in operation; when the mold is cooled, the upper and lower cooling plates are in operation (circulating cooling water for cooling).

[0087] In this embodiment, the width of the plurality of second pads 4 disposed between the upper cooling plate 12 and the upper template 11, and between the lower cooling plate 22 and the lower template 21 is 5cm, and the spacing between adjacent second pads 4 is 3cm.

[0088] In some preferred embodiments, the upper mold core 14 is further provided with a first high-pressure water cooling pipe 16; the first high-pressure water cooling pipe 16 is a one-way straight pipe that penetrates the mold;

[0089] The lower mold core 24 is also provided with a second high-pressure water cooling pipe 26; the second high-pressure water cooling pipe 26 is a one-way straight pipe that passes through the mold.

[0090] The term "penetration" here refers to drilling the pipe-related hole directly from one side of the component to the other, rather than using an S-shaped bend. This is because the mold operates at a high temperature, and an S-shaped bend would cause a large amount of water to vaporize, which would be detrimental to the subsequent injection of water into the cold zone.

[0091] In this embodiment, specifically, the upper mold core 14 and lower mold core 24 are made of H11 American air-hardening hot work die steel, which achieves a surface hardness of 65 HRC after heat treatment. The upper and lower mold cores themselves are not heated, but rather passively transfer heat. The invention includes a thermocouple installed at the center of each of the upper and lower mold cores, allowing for flexible adjustment of the corresponding electromagnetic heating power by monitoring the center temperature of the upper and lower mold cores. Simultaneously, each mold core has an independent thermocouple associated with the first and second electromagnetic heating plates, enabling individual temperature control of the upper and lower mold cores, or coordinated control, providing greater flexibility. Furthermore, in some preferred embodiments, the upper and lower mold cores are equipped with unidirectional high-pressure water cooling pipes for convenient subsequent cooling.

[0092] Based on this structural design, in this invention, the upper / lower mold cores themselves are not heated; heating is achieved through heat conduction via their corresponding first / second electromagnetic heating plates. The first / second thermocouples located in the middle of the upper / lower mold cores are each connected to the first / second electromagnetic heating plates, facilitating real-time reading of the mold's actual temperature by the subsequent control system (such as a PLC system). Furthermore, since each of the upper / lower mold cores has a corresponding thermocouple, and the temperature data from these thermocouples is associated with the first / second electromagnetic heating plates, the upper / lower mold cores can be individually or controlled in conjunction with each other, offering high flexibility. Meanwhile, in some preferred embodiments, high-pressure water cooling pipes are provided in both the upper and lower mold cores, and these pipes are all unidirectional straight pipes that pass through the mold instead of being arranged in an S-shape. This is because the mold itself is extremely hot during operation, and when the high-pressure water pump injects cooling water into the high-pressure water cooling pipes, the water will quickly vaporize. Through the above-mentioned structural construction, the water or water vapor can stay in the mold for the shortest time, quickly achieve heat exchange, and have higher and better cooling efficiency in the later stage.

[0093] Under this structure and configuration, when rapidly cooling the mold, cooling water is injected into the one-way direct high-pressure water cooling pipes (i.e., the third high-pressure water cooling pipe 17 and the fourth high-pressure water cooling pipe 27) of the upper and lower water cooling plates by a high-pressure pump, which enables rapid cooling and shaping. The cooling rate can reach 20℃ / min to 80℃ / min. When a faster cooling rate is required, while the high-pressure pump is injecting cooling water into the one-way direct high-pressure water cooling pipes (i.e., the third high-pressure water cooling pipe 17 and the fourth high-pressure water cooling pipe 27) of the upper and lower water cooling plates, the high-pressure pump is also injecting cooling water into the one-way direct high-pressure water cooling pipes (i.e., the first high-pressure water cooling pipe 16 and the second high-pressure water cooling pipe 26) of the upper and lower mold cores, thereby achieving even faster (greater / faster cooling rate) cooling and shaping. With the above structure and construction, the present invention flexibly and effectively reduces the situation of directly injecting water into the upper and lower mold cores, while taking into account the needs of different rapid cooling rates in different application scenarios, and minimizing the fatigue damage that may occur in the upper and lower mold cores during rapid heating and cooling cycles. The structure is reasonable, ingenious and flexible.

[0094] In some preferred embodiments, such as Figure 3 , Figure 4 , Figure 7 and Figure 8 As shown, the mold core is a male and female mold including an upper mold core 14 and a lower mold core 24, wherein the lower mold core 24 located below is a concave mold and the upper mold core 14 located above is a convex mold.

[0095] In this invention, the mold core is constructed as a male and female mold, with the female mold located at the bottom. This effectively prevents excessive resin loss due to compression when the resin is heated and melted.

[0096] In this invention, several first pads 3 disposed between the upper mold core 14 and the lower mold core 24 are all replaceable or adjustable first pads 3.

[0097] In this invention, such as Figure 4 and Figure 8 As shown, the first pads 3 are evenly distributed around the periphery of the mating area between the upper mold core 14 and the lower mold core 24, such as the four corners; the thickness of the first pads 3 is 0.5-10mm; the first pads 3 are positioned by positioning posts 31. In this embodiment, specifically: to ensure that the first pads are always placed in a fixed position and have a uniform distribution, the first pads 3 used for adjusting the gap have a hollow hole in the middle, and the positioning posts 31 used for positioning are fixed on the lower mold core. When installing the first pads 3 used for adjusting the gap, they are directly inserted into the corresponding positioning posts 31, thereby achieving the positioning function. In this embodiment, the positioning posts 31 are positioning cylinders (also called positioning rods).

[0098] In this invention, based on the above-described structure, the thickness of the molded product can be flexibly adjusted by using the first pads located around the upper and lower mold cores. In this invention, the thickness of the first pad 3 can be adjusted from 0.5 to 10 mm, and the first pad 3 is positioned by a smaller positioning cylinder with a diameter of 8 mm.

[0099] The rapid cooling and heating molding die provided by the present invention further includes a heat deformation correction structure; the heat deformation correction structure includes: a plurality of first fastening screws 19 located in the middle part of the die, passing through the upper template 11, the upper cooling plate 12 and the first electromagnetic heating plate 13 in sequence, and fastened to the threaded inner hole opened on the upper mold core 14; and a plurality of second fastening screws 29 located in the middle part of the die, passing through the lower template 21, the lower cooling plate 22 and the second electromagnetic heating plate 23 in sequence, and fastened to the threaded inner hole opened on the lower mold core 24.

[0100] Alternatively, it can be said that the heat-induced deformation correction structure includes several first fastening screws 19 located in the middle of the mold, and several second fastening screws 29 located in the middle of the mold. The ends of the several first fastening screws 19 pass through the upper template 11, the upper cooling plate 12 and the first electromagnetic heating plate 13 in sequence, and are then fastened to the threaded inner hole opened on the upper mold core 14. The ends of the several second fastening screws 29 pass through the lower template 21, the lower cooling plate 22 and the second electromagnetic heating plate 23 in sequence, and are then fastened to the threaded inner hole opened on the lower mold core 24.

[0101] The first fastening screw 19 is tightened starting from the upper template 11, and the upper mold core 14 undergoes a certain deformation (also known as deformation amount) through the tightening tension.

[0102] The second fastening screw 29 is tightened from the lower template 21, and the tightening force causes the lower mold core 24 to undergo a certain deformation (also known as deformation amount).

[0103] In this invention, the thickness of the upper template 11 and the lower template 21 is greater than or equal to 7 cm; and the upper template 11 and the upper cooling plate 12 are mutually heat-insulated; the lower template 21 and the lower cooling plate 22 are mutually heat-insulated.

[0104] In practical production applications, even if the mold material has a very small coefficient of thermal expansion, thermal deformation will still occur as the mold size and temperature increase. Considering the expansion caused by heating, the temperature is highest in the center of the mold, resulting in the greatest expansion. In the rapid heating and cooling molding die provided by this invention, to ensure the uniformity of the molded product thickness, such as... Figure 9 , Figure 10 and Figure 11 As shown ( Figure 9 The upper mold plate 11, upper cooling plate 12, first electromagnetic heating plate 13, and lower mold plate 21, lower cooling plate 22, and second electromagnetic heating plate 23 are not explicitly shown. At the center of the mold, several first fastening screws 19 are sequentially connected to the upper mold plate 11, upper cooling plate 12, first electromagnetic heating plate 13, and upper mold core 14, and several second fastening screws 29 are sequentially connected to the lower mold plate 21, lower cooling plate 22, second electromagnetic heating plate 23, and lower mold core 24. In this structural configuration provided by the present invention, the first fastening screws 19 are tightened starting from the upper mold plate 11, and the tightening force causes a certain deformation (also referred to as deformation amount) in the upper mold core 14. Similarly, the second fastening screws 29 are tightened starting from the lower mold plate 21, and the tightening force causes a certain deformation (also referred to as deformation amount) in the lower mold core 24.

[0105] Furthermore, in order to better achieve the deformation of the corresponding upper and lower mold cores by means of the pulling force of the first and second fastening screws (also known as fastening bolts) through the locking tension, the following structural construction is further adopted to better ensure that the upper and lower mold plates themselves will not deform (because the thermal deformation of the upper and lower mold plates themselves will offset the amount of tensile deformation): On the one hand, the mold steel used for the upper mold plate 11 and the lower mold plate 21 in this invention has a thickness of more than 7cm, and the upper / lower mold plates themselves are relatively thick, which can effectively ensure that the upper / lower mold plates will not be deformed by reverse pulling; on the other hand, the upper mold plate 11 and the upper cooling plate 12 are mutually heat-insulated, the lower mold plate 21 and the lower cooling plate 22 are mutually heat-insulated, and the upper / lower cooling plates and the upper / lower mold plates have a good temperature barrier effect, thereby ensuring to the greatest extent that the upper / lower mold plates themselves will not undergo thermal deformation due to heat. Based on the above structural design, the rapid heating and cooling molding die provided by this invention can still flexibly correct the thermal deformation (also known as deformation) of the upper / lower mold cores when the working temperature is as high as 300-450℃ by adjusting the torque of the aforementioned first and second fastening screws (in this embodiment, the first and second fastening screws are each 5 bolts). In this embodiment, both the first fastening screw 19 and the second fastening screw 29 are 5 M12 screws / bolts. Of course, the first fastening screw 19 and the second fastening screw 29 can also be set to 7, 8, 11, etc., depending on the actual application requirements. In this embodiment, the mold steel used for the upper mold plate 11 and the lower mold plate 21 is 10cm thick.

[0106] This embodiment also provides a rapid cooling and heating molding method for thermoplastic prepreg products, which uses any of the rapid cooling and heating molding dies described above, and includes the following steps:

[0107] Step 1): After the thermoplastic prepreg is cut and stacked, it is placed into the rapid molding die. The thickness of the finished prepreg is controlled by adjusting the thickness of the first pad (also known as the gap pad). When the rapid molding die is closed, only contact pressure is applied instead of full pressure, and electromagnetic heating is started at the same time for rapid heating.

[0108] Step 2): When the rapid molding die reaches the preset temperature threshold (also known as the set temperature), it is kept warm for a preset time so that the temperature of the die is conducted to the prepreg, thereby melting the resin therein; (In this embodiment, the prepreg is the product of continuous fibers being impregnated with resin; the resin can be a thermoplastic resin such as polyetheretherketone, polyphenylene sulfide, or polyetherketoneketone).

[0109] Step 3): Close the rapid molding die, apply full pressure and vacuum, so that the prepreg is formed in the heated extrusion; (vacuuming here refers to vacuuming the inside of the die, that is, vacuuming the mold cavity. Thermoplastic prepreg itself is not sticky and the layers are not bonded together. Vacuuming is used to remove the gas in the prepreg).

[0110] Step 4): After the product is formed, cooling water is injected into the one-way straight high-pressure water cooling pipes of the upper and lower water cooling plates through a high-pressure pump for rapid cooling and shaping.

[0111] Step 5): Open the mold and remove the product.

[0112] In certain preferred embodiments of the rapid cooling and heating molding method for thermoplastic prepreg articles, the method further includes the following steps:

[0113] The step of adjusting the torque of several first fastening screws to correct the thermal deformation (also known as the deformation amount) of the upper mold core, thereby achieving the deformation of the upper mold core; and

[0114] The step of adjusting the torque of several second fastening screws to correct the thermal deformation (also known as the deformation amount) of the lower mold core is to achieve the deformation of the lower mold core.

[0115] Based on the structure of the rapid molding die provided by the present invention, in step 1), the heating rate of the electromagnetic heating for rapid heating can reach 10-50℃ / min to achieve rapid heating; in step 4), the cooling rate of the rapid cooling and shaping can reach 20-80℃ / min to achieve rapid cooling.

[0116] In some preferred embodiments, in step 4), after the product is formed, cooling water is injected into the one-way direct high-pressure water cooling pipes (i.e., the third high-pressure water cooling pipe 17 and the fourth high-pressure water cooling pipe 27) of the upper and lower water cooling plates by a high-pressure pump, while cooling water is injected into the one-way direct high-pressure water cooling pipes (i.e., the first high-pressure water cooling pipe 16 and the second high-pressure water cooling pipe 26) of the upper and lower mold cores by a high-pressure pump for rapid cooling and shaping.

[0117] Experiments were conducted on the rapid cooling and heating molding method for thermoplastic prepreg products provided in the above-described embodiments: Specifically, in step 1), after the thermoplastic prepreg is cut and stacked, it is placed into the rapid molding mold. The thickness of the prepreg product is adjusted to 0.1 mm by adjusting the thickness of the first pad 3 (also known as the gap pad) to 0.1 mm. Furthermore, in step 1), 0.1 MPa is applied when the rapid molding mold is closed, and the heating program is started for rapid heating via electromagnetic heating. In step 2), when the rapid molding mold reaches the preset temperature threshold 3... At 90℃, a pre-set heat preservation time of 60s is performed to ensure that the mold temperature can be conducted to the prepreg so that the resin melts; in step 3), the mold is then closed, a full pressure of 1.6MPa is applied and a vacuum is drawn so that the prepreg is formed in the heated extrusion; in step 4), after the product is formed, cooling water is injected into the one-way direct high-pressure water cooling pipes of the upper water cooling plate 12 and the lower water cooling plate 22 by a high-pressure pump for rapid cooling and shaping; in step 5), the mold is finally opened and the CF / PEEK product (i.e., carbon fiber / polyetheretherketone product) is taken out.

[0118] Experiment: A comparative experiment was conducted using a conventional mold in a conventional press (model Taitian TT-SZ100T / MY) and the rapid cooling and heating mold provided in this embodiment for preparing thermoplastic prepreg products.

[0119] Among them: conventional molds use electric heating (i.e., electric heating rod heating), with a heating rate of 10-30℃ / min; conventional molds also use natural cooling, with a cooling rate of 2-10℃ / min.

[0120] When using a conventional mold, the corresponding processing steps are as follows: (1) Heat to 390℃ at room temperature at a rate of 15℃ / min. (2) When the temperature reaches 390℃, apply a pressure of 0.1MPa and hold for 30 minutes. (3) At 390℃, apply a pressure of 2.0MPa and hold for 60 minutes. (4) Allow to cool naturally while maintaining a pressure of 2.0MPa at a cooling rate of approximately 3℃ / min. (5) Cool to 100℃, release the pressure, and remove the molded sheet.

[0121] When using the rapid heating and cooling molding die provided in this embodiment, the corresponding rapid heating and cooling process is as follows: (1) Heating from room temperature to 390℃ at a rate of 40℃ / min. (2) When the temperature reaches 390℃, using a pressure of 0.1MPa, holding for 30min. (3) At 390℃, using a pressure of 2.0MPa, holding for 60min. (4) Rapid cooling, maintaining a pressure of 2.0MPa, with a cooling rate of approximately 50℃ / min. (5) Cooling to 100℃, depressurizing, and removing the molded sheet. The comparative experimental results are as follows:

[0122] Table 1: Comparative experimental data of conventional molds and rapid heating and cooling molds used in conventional presses

[0123]

[0124]

[0125] Multiple comparative experiments have shown that the rapid heating and cooling molding die provided by this invention remains stable even at working temperatures as high as 300-450℃. Its key indicators such as porosity, crystallinity, and thickness accuracy are superior to existing technologies. The porosity can reach 0.8-1.4%, the crystallinity can reach 18-32%, and the thickness accuracy can reach ±0.15mm. This effectively solves the problem of severe heat deformation of the die due to excessive heating temperature, which affects the thickness accuracy of the product.

[0126] The term "rapid heating" in this text refers to rapid heating and temperature rise. In this embodiment, electromagnetic induction heating is used to achieve rapid heating of the mold, with a heating rate of 10℃ / min to 50℃ / min. The term "rapid cooling" refers to rapid cooling and temperature reduction. In this embodiment, water is injected into the upper / lower cooling plates under pressure to achieve rapid cooling of the mold, with a cooling rate of 20℃ / min to 80℃ / min. Furthermore, based on the structure and construction provided by this invention, the direct injection of water into the upper and lower mold cores is significantly reduced. This minimizes fatigue damage to the upper and lower mold cores during rapid heating and cooling cycles while also meeting the needs of different rapid cooling rates in various application scenarios. The structure is reasonable, ingenious, and flexible.

[0127] The " / " in this text indicates "or". The cooling plate mentioned in this text can also be called a water-cooled plate or water-cooling plate. The first pad mentioned in this text can also be called a gap pad. The second pad mentioned in this text can also be called a barrier pad. The pad mentioned in this text can also be called a gasket. The rapid cooling and heating molding die and method for thermoplastic prepreg products described in this text can also be called a rapid cooling and heating molding die and molding method for preparing thermoplastic prepreg products. The electromagnetic coil mentioned in this text can also be called a heating coil or electromagnetic heating coil.

[0128] The above embodiments do not constitute a limitation of the present invention. Any changes and modifications made by those skilled in the art without departing from the technical concept of the present invention shall fall within the protection scope of the present invention.

Claims

1. A rapid cooling and heating molding die for thermoplastic prepreg products, characterized in that: It includes a template, a mold core, and a first pad (3); The template includes an upper template (11) and a lower template (21); the mold core includes an upper mold core (14) and a lower mold core (24); a plurality of first pads (3) are disposed between the upper mold core (14) and the lower mold core (24); the plurality of first pads (3) disposed between the upper mold core (14) and the lower mold core (24) are all replaceable or adjustable first pads (3); Between the upper template (11) and the upper mold core (14), an upper cooling plate (12) and a first electromagnetic heating plate (13) for heating the upper mold core (14) are provided in sequence; Between the lower template (21) and the lower mold core (24), a lower cooling plate (22) and a second electromagnetic heating plate (23) for heating the lower mold core (24) are provided in sequence; The upper cooling plate (12) and the upper template (11) are connected by a number of second pads (4); the lower cooling plate (22) and the lower template (21) are connected by a number of second pads (4); The upper cooling plate (12) is also provided with a third high-pressure water cooling pipe (17); the third high-pressure water cooling pipe (17) is a one-way straight pipe that penetrates the upper cooling plate (12); The lower cooling plate (22) is also provided with a fourth high-pressure water cooling pipe (27); the fourth high-pressure water cooling pipe (27) is a one-way straight pipe that runs through the lower cooling plate (22); The upper mold core (14) is also provided with a first high-pressure water cooling pipe (16); the first high-pressure water cooling pipe (16) is a one-way straight pipe that penetrates the mold; the lower mold core (24) is also provided with a second high-pressure water cooling pipe (26); the second high-pressure water cooling pipe (26) is a one-way straight pipe that penetrates the mold; The upper template (11) and the upper cooling plate (12) are mutually insulated; the lower template (21) and the lower cooling plate (22) are mutually insulated. It also includes structures that correct for heat deformation; The heat-induced deformation correction structure includes: Several first fastening screws (19) located in the middle of the mold, the several first fastening screws (19) passing through the upper template (11), the upper cooling plate (12) and the first electromagnetic heating plate (13) in sequence, and then fastened to the threaded inner hole opened on the upper mold core (14); and Several second fastening screws (29) located in the middle part of the mold pass through the lower template (21), the lower cooling plate (22) and the second electromagnetic heating plate (23) in sequence, and are fastened to the threaded inner hole opened on the lower mold core (24). The first fastening screw (19) causes the upper mold core (14) to deform through the locking tension; The second fastening screw (29) causes the lower mold core (24) to deform by tightening the locking force.

2. The rapid cooling and heating molding die for thermoplastic prepreg products according to claim 1, characterized in that: The first electromagnetic heating plate (13) is provided with a first electromagnetic coil, which is connected to a high-frequency current generator; The second electromagnetic heating plate (23) is provided with a second electromagnetic coil, which is connected to a high-frequency current generator.

3. The rapid cooling and heating molding die for thermoplastic prepreg products according to claim 1, characterized in that: The upper mold core (14) has a first thermocouple (15) in its middle, which is connected to the first electromagnetic heating plate (13); the lower mold core (24) has a second thermocouple (25) in its middle, which is connected to the second electromagnetic heating plate (23); and / or The mold core is a male and female mold including an upper mold core (14) and a lower mold core (24), wherein the lower mold core (24) located below is a concave mold and the upper mold core (14) located above is a convex mold.

4. The rapid cooling and heating molding die for thermoplastic prepreg products according to claim 1, characterized in that: The first pad (3) is evenly distributed around the mating periphery of the upper mold core (14) and the lower mold core (24); and / or The thickness of the first pad (3) is 0.5 to 10 mm.

5. The rapid cooling and heating molding die for thermoplastic prepreg products according to claim 1 or 2, characterized in that: The template and mold core are made of air-hardening hot-work die steel; the template and mold core have a surface hardness of 50-70 HRC; and / or The first electromagnetic coil is uniformly distributed on the first electromagnetic heating plate (13); the second electromagnetic coil is uniformly distributed on the second electromagnetic heating plate (23); and / or The width of the plurality of second pads (4) is 1 to 10 cm; and / or The spacing between adjacent second pads (4) is 1 to 10 cm; and / or Each second pad (4) is fixed to the corresponding upper or lower cooling plate with M10 countersunk bolts.

6. The rapid cooling and heating molding die for thermoplastic prepreg products according to claim 1, characterized in that: The thickness of the upper template (11) and the lower template (21) is greater than or equal to 7 cm.

7. A rapid molding method for thermoplastic prepreg products involving rapid cooling and heating, characterized in that: It uses a rapid heating and cooling molding die as described in any one of claims 1 to 6, and includes the following steps: Step 1): After the thermoplastic prepreg is cut and stacked, it is placed into the rapid molding die. The thickness of the prepreg is controlled by adjusting the thickness of the first pad. When the rapid molding die is closed, only contact pressure is applied instead of full pressure, and electromagnetic heating is started at the same time for rapid heating. The heating rate of electromagnetic heating for rapid heating is 10-50℃ / min. Step 2): When the rapid molding die reaches the preset temperature threshold, it is kept warm for a preset time so that the temperature of the die can be conducted to the prepreg, thereby melting the resin therein. Step 3): Close the rapid molding die, apply full pressure and vacuum, so that the prepreg is formed in the heated extrusion process; Step 4): After the product is formed, cool water is injected into the one-way straight high-pressure water cooling pipes of the upper and lower water cooling plates for rapid cooling and shaping. Step 5): Open the mold and remove the product; It also includes the following steps: The steps of adjusting the torque of several first fastening screws to correct the thermal deformation of the upper mold core and thus achieving the deformation of the upper mold core; and adjusting the torque of several second fastening screws to correct the thermal deformation of the lower mold core and thus achieving the deformation of the lower mold core. In step 4), after the product is formed, cooling water is injected into the one-way direct high-pressure water cooling pipes of the upper and lower water cooling plates, and at the same time, cooling water is injected into the one-way direct high-pressure water cooling pipes of the upper and lower mold cores for rapid cooling and shaping; the cooling rate for rapid cooling and shaping is 20-80℃ / min.

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