Automation of continuous composite two-dimensional braiding process

Abstract

This work presents the design of a computer controlled pilot production plant capable of manufacturing hybrid braided/pultruded rod on a continuous basis. The current product design utilizes a high modulus carbon fiber core with a braided over-wrap composed of various materials. Production is accomplished in three phases: core fiber sorting and impregnation, 2D braiding, and resin curing. On-line impregnation of the core strands is accomplished using a pressure-fed impregnation ring. Deposition of the 2D braid is performed by a Maypole braider. Curing of the resin is accomplished using a novel two phase method. An induction heater first increases the temperature of steel wires embedded in the rod core. Next three tunnel ovens provide heat flux to the exterior of the rod. A caterpillar-type puller is used to advance the rod through the process. Prior to this work production was accomplished by manually adjusting machinery operating parameters through controls distributed throughout the production facility. This led to inconsistent quality product. The modifications to production equipment and the development of an automation system which allow one to improve. The modifications to production equipment and the development of an automation system which allow to improve product quality are the main topics of this work. The automation system is based on a PC equipped with several data acquisition cards. A global controller calculates machine set points based on product specifications and measured production rate. Cascade controllers are tasked to regulate machine operations about these set points. The rotational speed of the braider head and puller are monitored using incremental encoders and are under set point element and integral control. The resin flow rate is estimated from weight measurement of the resin reservoir. To regulate the resin dispensing process a calibration curve is used as a set point elements while disturbances are rejected using integral control. The curing oven temperatures are monitored using thermocouples. The oven temperatures are regulated using gain scheduled PI controllers. The modification to the production equipment and the development of the automation system allowed for significant improvements in the product quality.