A method for rapid hot press forming of a composite board

Abstract

This invention provides a method for rapid hot pressing of composite sheets, applicable to molds where the temperature can be adjusted by switching the medium entering the mold pipeline. The method includes: placing the sheet material; adjusting the mold temperature to between the Tg and Tm values ​​of the thermoplastic in the composite sheet; first-stage mold closing: heating the composite sheet; second-stage mold closing: heating and pressing the composite sheet into shape; mold cooling: cooling and solidifying the composite sheet; and removing the finished product: opening the mold and removing the finished product after the mold has cooled to room temperature. The advantages of this invention are that it avoids the diffusion of harmful gases and fumes into the production environment and allows for rapid and stable processing of thin parts and composite sheets with high surface precision requirements.

Description

[Technical Field]

[0001] This invention relates to the field of hot pressing forming technology for composite panels, and in particular to a method for rapid hot pressing forming of composite panels. [Background Technology]

[0002] The hot pressing process for composite panels typically involves heating the material outside the mold in an external furnace before placing it into the mold, or using an infrared heating plate inserted into the hot pressing mold for heating before hot pressing. However, using an external furnace to heat the composite panel before placing it into the mold for hot pressing can lead to the following problems:

[0003] 1. Difficult to clamp and position: When the heating furnace heats the composite material to above Tg (glass transition temperature), the material softens, making clamping and positioning difficult and unsuitable for more precise products;

[0004] 2. Poor temperature reproducibility: The temperature of the heated composite board continuously drops during the process of moving it from the heating furnace to the mold, and it is easily affected by the external environment, resulting in large temperature variations of the board during hot pressing. In particular, the heat loss of thinner composite boards is faster, and the impact on hot pressing is greater.

[0005] 3. Decreased product quality: When high Tg (glass transition temperature) composite boards are heated to high temperatures, the resin and additives in the boards will volatilize, resulting in resin loss, which in turn leads to a decrease in the mechanical properties and surface appearance quality of the hot-pressed products.

[0006] 4. Environmental pollution: When high-Tg (glass transition temperature) composite boards are heated to high temperatures, the resin and additives that volatilize will produce dense smoke, polluting the production environment.

[0007] While using an infrared heating pan inserted into the hot pressing mold avoids the problem of difficulty in clamping and positioning, all the other aforementioned issues remain. Therefore, these two hot pressing methods are generally only suitable for composite materials with simple shapes, a thickness of 1.5mm or more, a low Tg (glass transition temperature), and low requirements for product precision and appearance.

[0008] In view of this, the present invention provides a method for rapid hot pressing of composite sheets to solve the above problems. [Summary of the Invention]

[0009] The technical problem this invention aims to solve is the issue that hot-pressing composite panels using external heating before placing them into a mold or inserting an infrared baking pan into the mold results in difficulties in clamping and positioning the product, poor temperature reproducibility, reduced product quality, and environmental pollution. This invention provides a method for rapid hot-pressing of composite panels to address these problems.

[0010] The solution to the technical problem of this invention is: a method for rapid hot pressing and forming of composite sheets, applied in a mold with a rapid heating and cooling mold piping system, comprising the following steps:

[0011] S1: Inserting the board material: Place the cut composite board material into the mold;

[0012] S2: Adjust mold temperature: Select the corresponding medium to enter the mold pipeline to adjust the mold temperature. The mold temperature depends on factors such as the Tg (glass transition temperature) and Tm (melting temperature) of the thermoplastic in the composite board and the product pressing shape, so that the mold temperature reaches between the Tg (glass transition temperature) and Tm (melting temperature) of the thermoplastic in the composite board.

[0013] S3: First stage mold closing: Control the distance between the mold and the composite material. This distance depends on factors such as the product pressing shape. Utilize the temperature of the mold to heat the composite material through thermal radiation and convection.

[0014] S4: Second stage mold closing: The mold closing speed in this stage is adjusted according to the thickness of the composite material and the shape of the product. The mold closes while simultaneously heating the composite material using heat conduction and pressing it into shape.

[0015] S5: Mold cooling: Select the appropriate medium to enter the mold pipeline, the mold begins to cool down, and the composite material is cooled at the same time until the mold closing pressure slowly decreases to zero. The composite material is cooled in the mold and pressed into shape under the mold pressure.

[0016] S6: Remove the finished product: After the mold has cooled to room temperature, open the mold and remove the finished product.

[0017] Preferably, the thermoplastic in the composite sheet is PC (polycarbonate), with a Tg (glass transition temperature) of 100-150°C and a Tm (melting temperature) of 220°C. The medium passing through the mold pipeline in S2 is water vapor at 160-170°C, and the medium passing through the mold pipeline in S5 is water at 15-30°C.

[0018] Preferably, the thermoplastic in the composite board is PSU (polysulfone), with a Tg (glass transition temperature) of 190°C and a Tm (melting temperature) of 288°C. In S2, the mold pipeline can first pass water vapor at 160-170°C. When the mold temperature rises to 150°C, hot kerosene at 250-280°C is then used to pass through the mold pipeline to achieve rapid heating. In S5, the medium passing through the mold pipeline is water at 15-30°C.

[0019] Preferably, the distance between the mold and the composite material in S3 is 1mm to 5mm.

[0020] Preferably, the mold closing speed in S4 is 0.1 mm / sec to 3 mm / sec.

[0021] Preferably, before changing the medium in the mold pipeline, the mold pipeline can be dried with air to drain the medium from the mold pipeline, so as to prevent the mold pipeline from bursting due to the reaction between different media when changing the medium in the mold pipeline.

[0022] The beneficial effects of this invention are that it can quickly and stably process thin parts and composite boards with high surface precision requirements, while avoiding the diffusion of harmful gases and dust into the production environment. [Attached Image Description]

[0023] Figure 1 This is a flowchart of the steps of a method for rapidly hot-pressing composite sheet material according to the present invention.

[0024] Figure 2 This is a flowchart of the steps in Embodiment 1 of the present invention.

[0025] Figure 3 This is a flowchart of the steps in Embodiment 2 of the present invention.

[0026] Figure 4 This is a schematic diagram of the composite board placed in a mold and awaiting hot pressing.

[0027] Figure 5 This is a schematic diagram of the finished product after hot pressing.

Detailed Implementation Methods

[0028] To further illustrate the technical means and effects of the present invention, the following detailed description is provided in conjunction with the embodiments of the present invention and their accompanying drawings.

[0029] This invention provides a method for rapid hot pressing and forming of composite panels, applied to a hot pressing mold 1 with a rapid heating and cooling mold piping system. This rapid heating and cooling mold piping system connects an external pipe (not shown in the figure) to the inlet 20 and outlet 21 of the original mold piping 2, allowing the medium entering the mold piping 2 to be controlled by a valve (not shown in the figure). According to the required temperature of the mold 1, the medium entering the mold piping 2, such as steam, hot kerosene, air, or water, is controlled by the valve (not shown in the figure) to achieve rapid heating and cooling of the mold temperature, thereby achieving the purpose of rapidly heating and cooling the mold 1.

[0030] The thermoplastic in the composite sheet 3 can be PC (polycarbonate), PMMA (polymethyl methacrylate), PPS (polyphenylene sulfide), PA series such as PA6 (nylon 6) or PA66 (nylon 66) or PA12 (nylon 12)..., PSU (polysulfone) and other thermoplastics. The method of rapid hot pressing and molding of composite sheet of the present invention is described below with reference to Examples 1 and 2.

[0031] Example 1

[0032] In Example 1, the thermoplastic in the composite sheet 3 is PC (polycarbonate), with a Tg (glass transition temperature) of 100-150°C and a Tm (melting temperature) of 220°C. The method for rapidly hot-pressing the composite sheet includes the following steps:

[0033] S110: Inserting the board material: Place the cut composite board material 3 into the mold 1;

[0034] S120: Adjust mold temperature: Use 160-170℃ water vapor to enter mold pipe 2 to adjust the mold temperature so that the mold temperature reaches between the Tg (glass transition temperature) of PC (polycarbonate) of 100-150℃ and the Tm (melting temperature) of 220℃.

[0035] S130: First stage mold closing: The distance between the composite plate 3 and the mold 1 is controlled between 1mm and 5mm. The temperature of the mold 1 is used to heat the composite plate 3 through heat radiation and convection.

[0036] S140: Second stage mold closing: The mold closing speed of the mold 1 in the second stage is controlled at 0.1mm / sec to 3mm / sec. While the mold 1 is closing, it uses heat conduction to heat the composite board 3 and press the composite board 3 into shape.

[0037] S150: Mold cooling: Water at 5-30℃ is introduced into mold pipe 2, mold 1 begins to cool down, and composite board 3 is cooled at the same time until the mold closing pressure slowly decreases to zero. Composite board 3 is cooled in mold 1 and pressed and shaped under mold pressure.

[0038] S160: Remove the finished product: After the mold 1 is cooled to room temperature, open the mold and remove the finished product 4.

[0039] Example 2

[0040] In Example 2, the thermoplastic in the composite sheet 3 is PSU (polysulfone), with a Tg (glass transition temperature) of 190°C and a Tm (melting temperature) of 288°C. The method for rapid hot pressing of the composite sheet includes the following steps:

[0041] S210: Inserting the board material: Place the cut composite board material 3 into the mold 1;

[0042] S220: Adjusting the mold temperature: First, use 160-170℃ steam to enter the mold pipe 2 to adjust the mold temperature and make the mold temperature rise rapidly. When the mold temperature rises to 150℃, replace it with air to blow the mold pipe 2 dry. Then replace it with hot kerosene at 250-280℃ to make the mold temperature reach between the Tg (glass transition temperature) of PSU (polysulfone) of 190℃ and the Tm (melting temperature) of 288℃.

[0043] S230: First stage mold closing: The distance between the composite plate 3 and the mold 1 is controlled between 1mm and 5mm. The temperature of the mold 1 is used to heat the composite plate 3 through heat radiation and convection.

[0044] S240: Second stage mold closing: The mold closing speed of the mold 1 in the second stage is controlled at 0.1mm / sec to 3mm / sec. While the mold 1 is closing, it uses heat conduction to heat the composite board 3 and press the composite board 3 into shape.

[0045] S250: Mold cooling: Water at 5-30℃ is introduced into mold pipe 2, mold 1 begins to cool down, and composite board 3 is cooled at the same time until the mold closing pressure slowly decreases to zero. Composite board 3 is cooled in mold 1 and pressed into shape under mold pressure.

[0046] S260: Remove the finished product: After the mold 1 is cooled to room temperature, open the mold and remove the finished product 4.

[0047] Before changing the medium in the mold pipe 2, the mold pipe 2 can be dried with air to remove the medium from the mold pipe 2, so as to prevent the mold pipe 2 from bursting due to the reaction between different media when changing the medium in the mold pipe 2.

[0048] The beneficial effects of this invention are that it can quickly and stably process thin parts and composite boards with high surface precision requirements, while avoiding the diffusion of harmful gases and dust into the production environment.

[0049] It should be noted that the present invention is not limited to the above embodiments. Any simple modifications, equivalent changes and alterations made by those skilled in the art to the above embodiments based on the technical solutions of the present invention shall fall within the protection scope of the present invention.

Claims

1. A method for rapid hot pressing and forming of composite sheets, applied in a mold with a rapid heating and cooling mold piping system, characterized in that, Includes the following steps: S1: Inserting the board material: Place the cut composite board material into the mold; S2: Adjust mold temperature: Select the appropriate medium to enter the mold pipeline to adjust the mold temperature. The factors that determine the mold temperature include the Tg (glass transition temperature) and Tm (melting temperature) of the thermoplastic in the composite sheet and the product pressing shape, so that the mold temperature reaches between the Tg (glass transition temperature) and Tm (melting temperature) of the thermoplastic in the composite sheet. S3: First stage mold closing: Controlling the distance between the mold and the composite material, which depends on factors including the product pressing shape, and using the temperature of the mold to heat the composite material through heat radiation and convection. S4: Second stage mold closing: The mold closing speed in this stage is adjusted according to the thickness of the composite material and the shape of the product. The mold closes while simultaneously heating the composite material using heat conduction and pressing it into shape. S5: Mold cooling: Select the appropriate medium to enter the mold pipeline, the mold begins to cool down, and the composite material is cooled at the same time until the mold closing pressure slowly decreases to zero. The composite material is cooled in the mold and pressed into shape under the mold pressure. S6: Remove the finished product: After the mold has cooled to room temperature, open the mold and remove the finished product.

2. The method for rapid hot pressing and forming of composite panels as described in claim 1, characterized in that: The thermoplastic in the composite sheet is PC (polycarbonate), with a Tg (glass transition temperature) of 100-150°C and a Tm (melting temperature) of 220°C. The medium passing through the mold pipeline in S2 is water vapor at 160-170°C, and the medium passing through the mold pipeline in S5 is water at 15-30°C.

3. The method for rapid hot pressing and forming of composite panels as described in claim 1, characterized in that: The thermoplastic in the composite board is PSU (polysulfone), with a Tg (glass transition temperature) of 190°C and a Tm (melting temperature) of 288°C. In S2, the mold pipeline first passes through water vapor at 160-170°C. When the mold temperature rises to 150°C, hot kerosene at 250-280°C is then passed through the mold pipeline. In S5, the medium passing through the mold pipeline is water at 15-30°C.

4. The method for rapid hot pressing and forming of composite panels as described in claim 1, characterized in that: The distance between the mold and the composite plate in S3 is 1mm to 5mm.

5. The method for rapid hot pressing and forming of composite panels as described in claim 1, characterized in that: The mold closing speed in S4 is 0.1 mm / sec to 3 mm / sec.

6. A method for rapid hot pressing and forming of composite panels as described in claim 1 or 3, characterized in that: Before changing the medium in the mold pipeline, the mold pipeline is first dried with air to drain the medium from the mold pipeline, in order to prevent the mold pipeline from bursting due to the reaction between different media when changing the medium in the mold pipeline.

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