A temperature control method for mesh monofilament laying

Abstract

The present invention provides a temperature control method for mesh monofilament layup, comprising: measuring the relationship between the heating length of an infrared radiation heating device and the energy required to heat a prepreg; calculating the energy generated by the infrared radiation heating device on the prepreg surface; calculating the infrared radiation heating device power required to heat the prepreg during movement; and calculating the heating time required to heat the prepreg to a desired temperature when the device moves at a fixed speed under a fixed heating power. The present invention achieves bidirectional regulation of heating power along with layup speed during the movement of the layup device, thereby controlling both speed and temperature, two of the layup process parameters. This overcomes shortcomings of hot air heating, such as slow response speed, slow heating rate, and inaccurate temperature control.

Description

Technical Field

[0001] The present invention belongs to the fields of fiber winding, automatic fiber placement and grid placement, and in particular relates to a grid monofilament laying and temperature control method. Background Art

[0002] Automated composite molding includes technologies such as automated fiber placement, automated tape placement, and filament winding. Factors such as temperature and humidity in the manufacturing environment can significantly impact product quality. Excessively high or low temperatures can affect the viscosity of the prepreg, hindering its adhesion to the mold surface and the bonding between prepreg layers. Therefore, precise control of the prepreg temperature during manufacturing is crucial.

[0003] The current method for heating prepregs in China mainly uses hot air to heat the prepregs. The air temperature can be controlled by controlling the air outlet temperature, which is convenient for operation. However, there are the following shortcomings:

[0004] 1. Large heat loss. The hot air has poor directionality and is easily lost due to the inability to blow to the prepreg surface. The hot air without direction will blow to the automated molding equipment, causing damage to the equipment.

[0005] 2. Low heat exchange efficiency and slow response speed. The hot air and prepreg are heated mainly by convection heat transfer, which has low heating efficiency, slow temperature response, and a long heating time for the prepreg.

[0006] 3. The heating process is unstable, making it difficult to precisely control the prepreg surface temperature. The relationship between the relevant factors during the heating process is uncertain, making it impossible to precisely control the prepreg surface temperature based on known conditions. Summary of the Invention

[0007] In order to solve the above problems, the present invention discloses a grid monofilament laying and winding temperature control method, which accurately controls the temperature when laying the grid unit monofilament.

[0008] The technical solutions for achieving the purpose of the present invention are:

[0009] A method for controlling temperature of mesh monofilament laying and winding, comprising the following steps:

[0010] Step 1: Determine the relationship between the heating length of the infrared radiation heating device and the energy required to heat the prepreg;

[0011] Step 2: Calculate the energy generated by the infrared radiation heating device on the prepreg surface;

[0012] Step 3: Calculate the power of the infrared radiation heating device required to heat the prepreg during movement;

[0013] Step 4: Calculate the heating time required for the prepreg to reach the required temperature when the equipment moves at a fixed speed and at a fixed heating power.

[0014] Compared with the prior art, the present invention has the following significant advantages:

[0015] The external heater used in the present invention has strong radiation directionality, less heat damage, high heating efficiency, and fast response speed, which can well meet the precise temperature control requirements of the laying process; the present invention is designed for 5mm grid monofilament laying, with strong pertinence and adaptability.

[0016] The present invention calculates the heating power of the infrared radiation heating device and the heating time of the prepreg respectively, and can be applied to different heating environments, thereby expanding the application scope of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of the grid monofilament laying and temperature control system used in the present invention;

[0018] Figure 2 Schematic diagram of the heating effect of the infrared radiation heating device on the prepreg yarn;

[0019] List of figures: 1-mould surface, 2-pressing roller, 3-infrared radiation heating device, 4-power regulator, 5-programmable controller, 6-infrared radiation heating area on the prepreg yarn. DETAILED DESCRIPTION

[0020] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are intended only to illustrate the present invention and are not intended to limit the scope of the present invention. It should be noted that the terms "front," "rear," "left," "right," "up," and "down" used in the following description refer to directions in the accompanying drawings, and the terms "inward" and "outward" refer to directions toward or away from the geometric center of a particular component, respectively.

[0021] In this embodiment, the prepreg is transferred to the pressure roller 2 of the laying equipment, and the prepreg is laid on the mold surface 1 through the pressure roller 2; at the same time, an infrared radiation heating device 3 is provided above the prepreg, wherein the infrared radiation heating device 3 is provided with a power regulator 4; the power regulator 4 is electrically connected to the programmable controller 5.

[0022] The temperature control method for mesh monofilament laying and winding according to this embodiment is carried out in the following four steps:

[0023] (1) Determine the relationship between the heating length of the infrared radiation heating device and the energy required to heat the prepreg;

[0024] (2) Calculate the energy generated by the infrared radiation heating device on the prepreg surface;

[0025] (3) Calculate the power of the infrared radiation heating device required to heat the prepreg during movement;

[0026] (4) Calculate the heating time required for the prepreg to reach the required temperature when the automatic placement equipment moves at a fixed speed under a fixed heating power.

[0027] Each of the above steps is described in detail below.

[0028] 1. The relationship between the heating length of the infrared radiation heating device and the energy required to heat the prepreg. The prepreg laying process needs to be carried out at an appropriate temperature, and the appropriate temperature varies depending on the type of prepreg. By measuring the surface temperature of the prepreg and obtaining the temperature difference of the heating, the required energy can be calculated. Since 5mm prepreg yarn is used for monofilament laying during the mesh monofilament laying process, the heating area of ​​the heating lamp can be obtained after measuring the heating length of the heating device. The specific calculation method is as follows:

[0029] Q 升 =5C 预 (T-T0)m0l (1)

[0030] Among them, Q 升 The energy required to heat the prepreg, J;

[0031] C 预 Indicates the specific heat capacity of the prepreg, J / (kg·K);

[0032] T represents the suitable laying temperature of prepreg, K;

[0033] T0 represents the surface temperature of the prepreg, K;

[0034] m0 represents the mass of prepreg per unit area, kg / mm 2 ;

[0035] l represents the heating length of the heating device, mm.

[0036] 2. Calculate the energy generated by the infrared radiation heating device on the prepreg surface: The heat generated by the infrared radiation heating device on the prepreg surface is not entirely used to heat the prepreg. Some heat is lost through radiation. Therefore, the energy generated by the infrared radiation heating device on the prepreg surface is calculated as follows:

[0037] Q 总 =Q 升 +Q 损 (2)

[0038] Among them, Q 总 is the total energy generated by the infrared radiation heating device on the prepreg surface;

[0039] Q损 is the heat lost in the heat transfer process, mainly including radiation energy,

[0040] Where σ is the Boltzmann constant, σ=5.669×10 -8 W / mm 2 ·K 4 ;

[0041] ε is the emissivity of the prepreg surface;

[0042] t represents the radiation time, s.

[0043] 3. Calculate the power of the infrared radiation heating device required to heat the prepreg during movement: In actual use, the infrared radiation heating device will move at a constant speed along with the placement equipment. To ensure that the prepreg can be heated to the predetermined temperature during the movement of the heating device, the heating power of the heating device must meet the heating requirements. After measuring the speed of the equipment movement, the heating time at the same position of the prepreg can be calculated, and the required heating power can be obtained:

[0044]

[0045] Where,

[0046] Where v is the uniform motion speed of the placement equipment, mm / s;

[0047] At this point, it is concluded

[0048]

[0049] 4. Calculate the heating time required for the prepreg to reach the desired temperature when the placement equipment is moving at a fixed speed under a fixed heating power: For an infrared radiation heating device with a known heating power, to ensure that the prepreg can be heated to the desired temperature while the placement equipment is moving at a constant speed, the prepreg heating time must be sufficient. Since the heating distance of the prepreg is fixed, the heating time can be calculated by calculating the operating speed of the equipment. The resulting equation is:

[0050]

[0051] Thus, it is concluded

[0052]

[0053] So the heating time is:

[0054]

[0055] Example:

[0056] When the heating length l of the infrared radiation heating device is 3 mm and the ambient temperature is 15° C., the energy required for heating the prepreg is 30 J according to the relationship between the heating length of the infrared radiation heating device and the energy required for heating the prepreg.

[0057] To ensure the prepreg heats up while the placement equipment is moving at a constant speed, the heating power and equipment speed can be designed based on the calculation method for the infrared radiation heating device power required to heat the prepreg during movement and the calculation method for the heating time required to heat the prepreg to the required temperature when the equipment moves at a fixed speed and at a fixed heating power. If the placement equipment moves at 20mm / s, the minimum heating power required for heating is 200W. If the heating power is constant at 600W, the placement speed cannot exceed 60mm / s.

[0058] The technical means disclosed in the solution of the present invention are not limited to the technical means disclosed in the above-mentioned embodiment, but also include technical solutions composed of any combination of the above technical features.

Claims

1. A temperature control method for mesh monofilament winding, characterized in that: The steps include: Step 1: Determine the relationship between the heating length of the infrared radiation heating device and the energy required to heat the prepreg: Q 升 =5C 预 (T-T0)m0l Among them C 预 represents the specific heat capacity of the prepreg, T represents the suitable laying temperature of the prepreg, T0 represents the surface temperature of the prepreg, m0 represents the mass of the prepreg per unit area, and l represents the heating length of the heating device; Step 2: Calculate the energy generated by the infrared radiation heating device on the prepreg surface; The energy generated by the infrared radiation heating device on the surface of the prepreg is: Q 总 =Q 升 +Q 损 where Q 损 is the heat lost in the heat transfer process, Q 升 The energy required to heat the prepreg; The amount of heat lost during the heat transfer process is: Where σ is the Boltzmann constant and ε is the emissivity of the prepreg surface; Step 3: Calculate the power of the infrared radiation heating device required to heat the prepreg during movement: Among them, P 热 Indicates the power of infrared radiation heating device required to heat the prepreg, C 预 represents the specific heat capacity of the prepreg, and v is the uniform motion speed of the placement equipment; Step 4: Calculate the heating time required for the prepreg to reach the required temperature when the equipment moves at a fixed speed and at a fixed heating power: The heating power and equipment operating speed are designed according to the calculation method of the infrared radiation heating device power required to heat the prepreg during movement and the calculation method of the heating time required to heat the prepreg to the required temperature when the equipment moves at a fixed speed under fixed heating power.

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