Research On Preparing Of Towpreg With High Modulus Carbon Fiber For Fiber Placement

The high modulus carbon fiber towpreg with the properties of small quantities and high quality is used to manufacture aerospace-level composite materials. In this thesis, the dedicated prepreg preparation technology on the background of composite automated fiber placement was studied. The automatic slitting technology applies to mass production of prepreg. It can’t meet the demand of aerospace-level composite fiber placement so that the direct hot-melt preparation technology and technological parameter of high modulus carbon fiber towpreg was studied. The main works were as follows:Firstly, the processing route for preparing high modulus carbon fiber towpreg was analyzed and the overall scheme of preparation system was designed. The system includes a unwinding device, a pre-dispersed and a tension control device, a impregnation of fiber bundles with polymer device, a second dispersed device, a cooling and width keeping device, a plus film device and a winding device. The functional parameters of subsystems were planned respectively and the processing test platform was built.Secondly, the single electromagnetic induction heating mode was explored targeted toward the heating system of the wiping resin roller. Based on the theory analysis, the electromagnetic induction heating platform had been assembled based on the theoretical analysis, and the test on the uniformity of the heating was conducted.Thirdly, the influence of processing parameters on resin content and the width of towpreg was studied, with T300 carbon fiber. The resin content was affected by the tension of the fiber, the temperature of the resin, the line speed of the fiber and the distance between the wiping resin roller and the scraper, and the distance was the main factor. When the distance was less than 0.01 mm, the control precision of resin content could reach to 2.0%. The tension of the fiber, the number of spreading rollers, the diameter of second spreading roller and the keeping width device affected the width of towpreg. These factors needed to be regulated so that the width could be guaranteed. The towpreg prepared by M55 J carbon fiber was damaged seriously. It was necessary to do some research works on the processing parameters further.At last, for the easy-to-be-damaged problem of high modulus carbon fiber, the influence of the roller surface material, the tension of the fiber, the number of rollers and the diameter of rollers was studied by using M55 J high modulus carbon fiber. In order to understand the significance of the factors, orthogonal tests were designed. The results showed that the number of the rollers damages the M55 J most. The fiber tension ranked the second place. The diameter of rollers had the least influence on this fiber. Therefore, the basic parameters were obtained. It turned out that the tension value should be less than 20 N and the number of rollers should be no more than 5. The influence of the roller diameter is relatively small, options could be made according to the requirement of the towpreg width and the resin content.