1、 In this paper, the fiber is the main carrier in the fiber-reinforced composite, and the matrix resin is only the stress transmitter. The orientation, arrangement regularity and fiber content of the fiber in the composite play an important role in the full play of the strength and stiffness of the composite. Generally speaking, the higher the fiber content, the greater the reinforcement effect; the stronger the fiber arrangement order, the more obvious the reinforcement effect. Because the strength and stiffness of fiber-reinforced composites are closely related to fiber orientation, in practical application, the strength and stiffness of the materials can be fully exerted only when the fibers are oriented along the main stress direction of the product. In order to achieve this goal, it is necessary to fully understand the stress distribution of products, especially the direction and magnitude of the main stress, and how to reasonably arrange the orientation and quantity of fibers according to the direction and magnitude of the main stress. 2、 The process of directional laying and molding is generally divided into three stages: 1. Stress analysis of products This stage is to fully understand the structure of the product, the actual use state and carry out stress analysis, analyze the stress state of each part of the product, the direction, quantity and size of the main stress, so as to determine the laying direction and theoretical density of the reinforcement materials to be configured for each part of the product. 2. In this stage of directional laying process, how to achieve the consistency of laying direction and theoretical density of reinforcement materials configured in each part of the product with the requirements of stress analysis. For this reason, the commonly used method is: first, according to the stress state of the products, design a variety of pre impregnated directional laying products, then lay them according to certain procedure requirements, and finally through appropriate adjustment, the pressed blank is formed. The advantages of the pre impregnated products are: (1) the fibers are arranged in a uniform straight line, which can give full play to the strength and rigidity of the fibers; (2) the accurate quantification of the fiber content and resin content and the accurate directional arrangement of the fibers can predict the isotropic properties of the products and the reliability under stress conditions, and improve the performance of the products; (3) the preparation and laying of the pre impregnated materials can be divided into Two systems for process control. 3. The pressing and forming of products in this stage is to put the directional laying product blank into the metal mold, and form the products under high temperature and high pressure according to certain requirements. The process of directional laying molding is basically the same as that of short fiber molding. The main differences are as follows: (1) the compression ratio of the directional laying molded products is small, so the mold does not need to make a large charging cavity; (2) the molding pressure added during the pressing is only used to compress the products and drive away the volatiles, and it only causes local displacement of the materials, so as to realize small-scale adjustment without overcoming the internal friction of the materials, so the molding pressure can be reduced; (3) due to the fact that The molding pressure is low, the requirements of mold material can be slightly low, and the mold structure can be correspondingly simple. 3、 The mechanical properties of products can be divided into short fiber molding, directional laying molding and unidirectional fiber molding according to the fiber orientation. The mechanical properties of the composite prepared by the three processes are analyzed in table 43.37. Table: basic mechanical properties of three types of molding composite short fiber composite (fiber orientation) directional laying composite (fiber orientation) unidirectional composite (fiber orientation) tensile strength MPa mean value 76.8436.0533.0 single value range 39.6-106.0431.0-471.0468.0-603.0 tensile modulus GPA mean value 27.228.839.4 single value range 26.3-28.628.2-29 7.6-31.940.3-43.8 impact Average strength kJ / m2 55.0304383 single value range 38.6-69.5278-356353-405 Poisson's ratio 0.4490.1600.332 density g / cm31.8191.8541.839 rubber content% 37.035.9535.25 remarks: (1) selected material: fiber: high strength yarn 15mm-20mm resin: phenolic modified epoxy resin (epoxy / phenolic = 6 / 4) In directional laying: the longitudinal fiber density is 32 pieces / piece. Mm wide, and the transverse fiber density is 4.8 pieces / piece. Mm wide. Laying layers = longitudinal: transverse = 6:3, unidirectional laying fiber density is 32 pieces / piece. Mm wide (2) molding process: Molding temperature: 80-90 ℃; pressurization time: 105 ℃; molding pressure: 50MPa; heating speed: 30 ℃ / h; molding temperature: 170 ℃ - 180 ℃; holding time: 4-6min / mm; demoulding temperature: less than 60 ℃. 4. Typical application of directional laying molding technology - typical application of directional laying molding technology of blower rotor is blower rotor. The product photo of the blower rotor is shown as follows: 1. The raw material resin used for the blower rotor: 634 epoxy: 616 phenolic = 6:4 (weight ratio) glass fiber: 40 pieces / 20 strands 4114 alkali free roving ratio: resin: fiber = 40:60 prepare the pre impregnated strip, belt and circumferential plate required by the design according to this ratio. See table for impregnation system and quality index of pre impregnated strip and strip. The annular plate is a kind of pre impregnated product used when the rotor is laid with the annular fiber. It is made of pre impregnated strip on the circular sheet winding device by the dry winding process. The prepared pre impregnated strip, belt and circumferential sheet are shown in the figure: impregnation system and quality index items of pre impregnated tape
Temperature control of strip impregnation system, ℃ level 1, level 2, 130160166180 glue liquid specific gravity 0.990.99 traction speed, M / min3.23.2 quality index glue content,% 35-3835-38 volatile matter,% 1-31-3 insoluble resin content,% 1-31-3
Circular winding device
Radial band
Radial plate
2. Rotor directional laying process
The whole process of rotor orientation laying is carried out in a imitated wood pattern. The laying procedure and method shall be carried out according to the sequence number indicated in the drawing, and the combination mode of blade radial belt and the first round of circumferential piece shall be carried out according to the structure shown in the drawing. After the completion of directional laying of the whole rotor, the state before pressing is shown in the figure.
Process procedure of rotor directional laying
1 - wheel along the circumferential plate 2 - blade radial belt
The combination mode of blade radial belt and the first wheel along the circumferential plate
Rough drawing of rotor before pressing
3. Rotor pressing process main process parameters of rotor pressing: molding temperature: 80-90 ℃, pressing time: 105 ℃ (about 50min), forming pressure: 12MPa, heating speed: 30 ℃ / h, forming temperature: 170-180 ℃, holding time: 4-6min / mm, demoulding temperature: & lt; 60 ℃
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