Research On Key Technology In Tow Preparation For Orbiter Manufacture With Fiber Placement

This paper is aimed at the key technology in the preparation of high-modulus carbon fiber prepreg tow for orbiter manufacture with Automated Fiber Placement(AFP). It contains fiber spreading and damage technology, resin impregnation technology, and resin content controlling technology. The advantages and disadvantages of different spreading methods were analyzed. Ultrasonic assisted spreading and mechanical rollers spreading were put forward. Resin infiltration model was established. The influence of factors such as resin film thickness, fiber tension, resin temperature, the winding speed and the speed ratio on the resin content was studied. Response surface methodology was used to optimization of process parameters. Small batch trial production showed that the prepreg tow production could meet the technical requirement and the need of aerospace. The main research work were as follows:On the basis of previous research, three kinds of fiber spreading methods such as mechanical rollers method, ultrasonic liquid tank method and ultrasonic rods method were compared and analyzed. The effects of three kinds of fiber spreading method on fiber spreading and fiber damage were studied. According to the requirement of less damage to the fiber spreaded, the influence of the process parameters on the damage characteristics of high modulus carbon fiber, such as fiber tension, the number of rollers and the diameter of rollers, and the influence of 3 different degree on different fibers. Experimental results showed that: The greater the fiber tension, the more the number of rollers, the smaller the diameter of rollers, the more serious impact on the fiber damage. Fiber tension should be controlled within 5-20 N, the number of rollers should be controlled in 3-5, and the influence of the diameter of rollers is small. Under same preparation environment, the M series fiber damage is higher than the T series fiber. Under the condition of high damage, the retention tensile strength of the two kinds of fibers were all up to 90% or more of the contrast value, and the parameters of the product parameter can be set according to the high damage experiment parameter.The impregnation process of prepreg tow prepared was analyzed. The model of resin impregnated fiber bundles was established. Through single factor and orthogonal experiment, the influences of factors such as fiber tension, resin film thickness, the speed ratio, the winding speed, resin temperature on the resin content were studied. The optimized process parameters were obtained, and the process stability verification experiment was carried out. The experimental results are consistant with the theoretical expectation, which verifies the correctness and validity of the results.Using response surface method with central composite design, the response model of fiber tension, resin temperature, the winding speed, the speed ration and resin film thickness of prepreg tow quality was established. The influences of process parameters and the interaction on the prepreg tow quality were analyzed. Process parameters were optimized. And through the precision preparation system, small batch trial production was carried out, the width, resin content and damage property of prepreg tow reach to the target are achieved.