Thermoplastic composite mold pressing process and mold

Abstract

According to the thermoplastic composite material mold pressing process provided by the invention, electrode conduction type heating and composite material self-resistance heating are organically combined, and a mode of independently using a mold temperature controller or self-resistance heating in the prior art is replaced, so that the problem that heating efficiency and temperature uniformity are difficult to consider at the same time is fundamentally solved; and the accuracy of temperature control over materials such as carbon fibers in the mold pressing process can be remarkably improved. The invention further provides a thermoplastic composite material mold pressing mold for executing the process, system assemblies with the whole set of functions of heating, cooling, vacuumizing and the like are designed and integrated, efficient and accurate machining of thermoplastic composite material products can be achieved, and the cost is low.

Description

Technical Field

[0001] The present invention belongs to the technical field of thermoplastic fiber reinforced composite material forming, and particularly relates to a thermoplastic composite molding process and a mold. Background Art

[0002] Currently, when manufacturing carbon fiber components such as aircraft inlets and high-performance automotive parts, the processes adopted can generally be divided into two categories: thermoplastic forming and thermosetting forming. Among them, the thermoplastic composite molding process is more flexible in regulating temperature and pressure and has higher production efficiency. However, in existing molding, the heating of composite blanks generally adopts a separate mold temperature controller heating or self-resistance heating by electrification. Both of these methods have some obvious disadvantages. For example, when using a mold temperature controller for heating, it is difficult to improve in terms of the maximum heating temperature and efficiency due to the limitations of the equipment itself, and the energy consumption is relatively high; although the self-resistance heating method has an extremely fast temperature rise and the maximum temperature is not limited, its heating process is difficult to control, which is not conducive to the uniformity of the blank temperature. Therefore, how to improve the heating method in molding, overcome the defects of the existing technology, and improve the quality of the final product is an urgent technical problem to be solved in this field. Summary of the Invention

[0003] In view of this, in response to the technical problems existing in this field, the present invention provides a thermoplastic composite molding process, which specifically includes the following steps:

[0004] Step 1: Prepare a single-layer thermoplastic composite blank or a multi-layer thermoplastic composite blank formed by welding for performing molding; cut the blank according to the designed size;

[0005] Step 2: Send the prepared thermoplastic composite blank to the molding station, fix it in a mold including an upper mold and a lower mold, and then close the mold. The mutually cooperating dynamic seal components provided on the outer periphery of the upper mold and the lower mold of the mold are closed; an external vacuum pump evacuates the mold through the vacuum pipeline on the dynamic seal component of the lower mold of the mold to form a negative pressure environment;

[0006] Step 3: Turn on the heating electrodes respectively provided in the upper mold and the lower mold and electrically connected to an external power source, so that the thermoplastic composite realizes conductive heating through the upper and lower mold heat conduction plates in direct contact with it; at the same time, the heating electrodes of the upper and lower molds also form a heating circuit with the thermoplastic composite and the external power source, so that the thermoplastic composite realizes self-resistance heating; the two heating methods cooperate with the cooling pipelines provided in the upper mold and the lower mold of the mold to precisely adjust the temperature rise curve during the molding process; during heating, nitrogen or inert gas is provided into the mold through the air holes provided on the mold and connected to an external gas source to protect the environment and prevent the resin material in the composite from being oxidized;

[0007] Step 4: Perform a molding operation on the thermoplastic composite blank under predetermined temperature and vacuum conditions;

[0008] Step Five: After the molding operation is completed, stop heating, and cool down the thermoplastic composite blank and the upper and lower mold heating electrodes through the cooling pipes.

[0009] Step Six: After cooling is completed, open the mold and take out the molded thermoplastic composite.

[0010] Correspondingly, the present invention also provides a thermoplastic composite molding die for performing the above process, which includes an upper mold and a lower mold of the die; heating electrodes electrically connected to an external power source are provided in both the upper mold and the lower mold of the die, which are used to generate heat by energization and conductively heat the thermoplastic composite through the upper and lower mold heat conducting plates in direct contact with the thermoplastic composite; at the same time, the heating electrodes of the upper and lower molds also form a heating circuit with the thermoplastic composite and the external power source to achieve the self-resistance heating of the thermoplastic composite; cooling pipes are provided in both the upper mold and the lower mold of the die, which are used to adjust the temperature conditions during the molding process and cool down the heating electrodes and the thermoplastic composite; air holes connected to an external gas source are provided on the lower mold of the die, which are used to provide a gas protection environment for the die cavity after clamping to prevent the resin material in the composite from oxidizing, and a sealing spring pad is provided at the air holes; dynamic sealing components that cooperate with each other are provided on the outer peripheries of the upper mold and the lower mold of the die, and a vacuum pumping pipe connected to an external vacuum pump is provided on the dynamic sealing component of the lower mold of the die, which is used to provide a negative pressure environment for the die after clamping.

[0011] Further, the die is a flat die. A stepped upper mold ceramic plate is provided in the center of the upper mold plate of the die, and the upper mold heating electrode is provided on the stepped sunken edge; a flat lower mold ceramic plate is provided on the lower template, and the lower mold heating electrode is provided at its end; a ceramic backing plate and a damping module are provided below the lower mold heating electrode to connect the lower template, and the damping module is used to keep the die always tightly pressed when the thickness of the composite changes during the molding process; the upper mold heat conducting plate and the lower mold heat conducting plate are respectively provided on the corresponding ceramic plates, and a pressure-bearing insulating backing plate is provided at the edge of the heat conducting plate, and the distance between the upper and lower molds can be replaced and adjusted according to the thickness of the composite; the cooling pipes extend inside the upper and lower mold ceramic plates and the heat conducting plates respectively.

[0012] Further, the dynamic sealing components between the upper mold and the lower mold of the die are sealed by a sealing ring, and the two can exhaust gas by relatively moving a certain stroke.

[0013] The thermoplastic composite molding process provided by the present invention combines electrode conduction heating and composite self-resistance heating organically, replacing the way of using a mold temperature controller or self-resistance heating alone in the existing process. Fundamentally, it solves the problem that it is difficult to balance heating efficiency and temperature uniformity, and can significantly improve the accuracy of temperature control of materials such as carbon fiber during the molding process. The present invention also provides a thermoplastic composite molding die for implementing this process, which designs and integrates system components including heating, cooling, vacuum pumping and other full functions, can achieve efficient and precise processing of thermoplastic composite products, and has a lower cost. Brief Description of the Drawings

[0014] Figure 1 is a flowchart of the process provided by the present invention;

[0015] Figure 2 is a schematic structural diagram of the mold provided by the present invention. Detailed Embodiments

[0016] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0017] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0018] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "installation", "connection", and "connection" should be understood in a broad sense. For example, 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 directly connected, or indirectly connected through an intermediate medium, and it can be the internal communication of two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0019] The thermoplastic composite molding process provided by the present invention, as Figure 1 shown, specifically includes the following steps:

[0020] Step 1: Prepare a single-layer thermoplastic composite blank or a multi-layer thermoplastic composite blank formed by welding for compression molding; cut the blank according to the designed dimensions;

[0021] Step 2: Send the prepared thermoplastic composite blank to the compression molding station, fix it in a mold including an upper mold and a lower mold, and then close the mold. The mutually cooperating dynamic seal components provided on the outer peripheries of the upper mold and the lower mold of the mold are closed; an external vacuum pump passes through the vacuum extraction pipeline on the dynamic seal component of the lower mold of the mold to evacuate the mold and form a negative pressure environment;

[0022] Step 3: Turn on the heating electrodes respectively provided in the upper mold and the lower mold and electrically connected to an external power source, so that the thermoplastic composite realizes conductive heating through the upper and lower mold heat conduction plates in direct contact with it; at the same time, the heating electrodes of the upper and lower molds also form a heating circuit with the thermoplastic composite and the external power source, so that the thermoplastic composite realizes self-resistance heating; the two heating methods cooperate with the cooling pipelines provided in the upper mold and the lower mold of the mold to precisely adjust the temperature rise curve during the compression molding process; while heating, nitrogen or inert gas is provided into the mold through the air holes provided on the mold and connected to an external gas source to protect the environment and prevent the resin material in the composite from oxidizing;

[0023] Step 4: Perform compression molding on the thermoplastic composite blank under the conditions of a predetermined temperature and vacuum degree;

[0024] Step 5: After the compression molding operation is completed, stop heating, and cool down the thermoplastic composite blank and the heating electrodes of the upper and lower molds through the cooling pipelines;

[0025] Step 6: After cooling is completed, open the mold and take out the thermoplastic composite that has completed compression molding, which can be sent to the corresponding station to continue to perform processes such as Figure 1 heating and hot stamping as shown.

[0026] Correspondingly, the present invention also provides a thermoplastic composite compression molding mold for performing the above process, as Figure 2As shown in the figure, it includes the upper die and the lower die of the mold; in the upper die and the lower die of the mold, there are respectively an upper die heating electrode 2-3 and a lower die heating electrode 2-7 electrically connected to an external power supply, which are used for generating heat by energization and conducting heating to the blank 2-12 through the upper and lower die heat conducting plates 2-14 and 2-13 in direct contact with it; at the same time, the upper and lower die heating electrodes 2-3 and 2-7 also form a heating circuit with the thermoplastic composite material and the external power supply to realize the self-resistance heating of the thermoplastic composite material; cooling pipes are provided in both the upper die and the lower die of the mold, which are used to adjust the temperature conditions during the molding process through the circulation of cooling liquid or gas and to cool the heating electrodes and the thermoplastic composite material blank; the lower die of the mold is provided with air holes connected to an external gas source, which are used to provide a nitrogen or inert gas protection environment in the mold cavity after mold closing to prevent oxidation of the resin material in the composite material, and a sealing spring pad is provided at the air holes; a dynamic sealing component 2-5 that cooperates with each other is provided on the outer periphery of the upper die and the lower die of the mold, and a vacuum pumping pipe 2-6 connected to an external vacuum pump is provided on the dynamic sealing component 2-5 of the lower die of the mold, which is used to provide a negative pressure environment in the mold after mold closing.

[0027] In a preferred embodiment of the present invention, the equipment adopts a flat mold as shown in Figure 2 the figure. A stepped upper die ceramic plate 2-2 is provided in the center of the upper die template 2-1 of the mold, and the upper die heating electrode 2-3 is provided on the stepped sunken edge; a flat lower die ceramic plate 2-11 is provided on the lower template 2-10, and the lower die heating electrode 2-7 is provided at its end; a ceramic backing plate 2-8 and a damping module 2-9 are provided below the lower die heating electrode 2-7 to connect the lower template, and the damping module 2-9 is used to keep the mold always tightly pressed when the thickness of the composite material changes during the molding process; the upper die heat conducting plate 2-14 and the lower die heat conducting plate 2-13 are respectively provided on the corresponding ceramic plates, and a pressure-bearing insulating backing plate 2-4 is provided at the edge of the heat conducting plate, and the distance between the upper and lower dies can be replaced and adjusted according to the thickness of the composite material; the cooling pipes extend inside the upper and lower die ceramic plates and the heat conducting plates respectively.

[0028] In a preferred embodiment of the present invention, the dynamic sealing components 2-5 of the upper die and the lower die of the mold are kept sealed through a sealing ring, and the two can realize exhaust by relative movement for a certain stroke.

[0029] It should be understood that the magnitudes of the sequence numbers of the steps in the embodiments of the present invention do not mean the order of execution. The order of execution of each process should be determined by its function and internal logic, and should not constitute any limitation to the implementation process of the embodiments of the present invention.

[0030] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirits of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A thermoplastic composite molding process, characterized in that: The specific steps include: Step 1: prepare a single-layer thermoplastic composite blank or a multi-layer thermoplastic composite blank formed by welding required for compression molding; cut the blank according to the designed size; Step 2: Send the prepared thermoplastic composite blank to the molding station, fix it in a mold including an upper and lower mold, and then close the mold. The dynamic sealing components that cooperate with each other and are arranged on the outer periphery of the upper mold and the lower mold are closed; an external vacuum pump exhausts the air in the mold and forms a negative pressure environment through the vacuum pipe on the dynamic sealing component of the lower mold; Step 3: The heating electrodes electrically connected to the external power supply respectively arranged in the upper mold and the lower mold are turned on, so that the thermoplastic composite is heated by conduction through the upper and lower mold heat conducting plates in direct contact with the thermoplastic composite; at the same time, the heating electrodes of the upper and lower molds also form a heating circuit with the thermoplastic composite and the external power supply, so that the thermoplastic composite is heated by self-resistance; the two heating methods cooperate with the cooling pipes arranged in the upper and lower molds of the mold to accurately adjust the temperature rise curve during the molding process; while heating, nitrogen or inert gas is provided to the mold through the air holes connected to the external air source arranged on the mold to protect the environment and prevent the resin material in the composite from oxidizing; Step 4: performing a molding operation on the thermoplastic composite blank under predetermined temperature and vacuum conditions; Step 5: After the molding operation is completed, the heating is stopped, and the thermoplastic composite blank and the upper and lower mold heating electrodes are cooled through the cooling pipe; Step 6: After cooling, open the mold and take out the finished thermoplastic composite product.

2. A thermoplastic composite molding die for performing the process as claimed in claim 1, characterized in that: The invention comprises an upper mold and a lower mold; heating electrodes electrically connected to an external power source are arranged in the upper mold and the lower mold, which are used for heating by electricity and conducting heating through the upper and lower mold heat conducting plates in direct contact with the thermoplastic composite; at the same time, the heating electrodes of the upper and lower molds also form a heating circuit with the thermoplastic composite and the external power source to realize self-resistance heating of the thermoplastic composite; cooling pipes are arranged in the upper and lower molds, which are used for adjusting the temperature conditions during the molding process and cooling the heating electrodes and the thermoplastic composite; the lower mold is provided with air holes connected to an external air source, which are used for providing nitrogen or inert gas protection environment to prevent oxidation of the resin material in the composite in the mold cavity after the mold is closed, and a sealing spring pad is arranged at the air hole; the outer periphery of the upper mold and the lower mold is provided with a dynamic sealing assembly that cooperates with each other, and the dynamic sealing assembly of the lower mold is provided with a vacuum extraction pipe connected to an external vacuum pump, which is used for providing a negative pressure environment in the mold after the mold is closed.

3. The thermoplastic composite molding die according to claim 2, characterized in that: The mold is a flat-plate mold, a step-shaped upper mold ceramic plate is arranged in the center of the upper mold plate of the mold, and the upper mold heating electrode is arranged on the step-shaped sunken edge; a flat-plate-shaped lower mold ceramic plate is arranged in the lower mold plate, and a lower mold heating electrode is arranged at its end; a ceramic pad and a damping module are arranged under the lower mold heating electrode to connect the lower mold plate, and the damping module is used to keep the mold always pressed when the thickness of the composite material changes during the molding process; the upper mold heat conducting plate and the lower mold heat conducting plate are respectively arranged on the corresponding ceramic plates, and the edges of the heat conducting plates are provided with pressure-bearing insulating pads, which can be replaced and the distance between the upper and lower molds can be adjusted according to the thickness of the composite material; the cooling pipes extend inside the upper and lower mold ceramic plates and the heat conducting plates respectively.

4. The thermoplastic composite molding die according to claim 2, characterized in that: The dynamic sealing components of the upper mold and the lower mold are sealed by a sealing ring, and the two can achieve exhaust through relative movement over a certain stroke.

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