Novel form-flexible handling and joining tool for automated preforming

Abstract

The production rates of carbon fiber reinforced plastic (CFRP) parts are rising constantly which in turn drives research to bring a higher level of automation to the manufacturing processes of CFRP. Resin transfer molding (RTM), which is seen as a production method for high volumes, has been accelerated to a high degree. However, complex net-shape preforms are necessary for this process, which are widely manually manufactured. To face these challenges a new concept for the manufacturing of carbon fiber preforms with a form-flexible gripping, draping and joining end-effector is presented and discussed. Furthermore, this paper investigates the application of this concept, describes the initial build-up of a demonstrator, focusing on material selection and heating technology, and discusses test results with the prototype. This prototype already validates the feasibility of the proposed concept on the basis of a generic preform geometry. After a summary, this paper discusses future in-depth research concerning the concept and its application in more complex geometries.

Development and characterization of a through-air thermobonding process with high heating rate for activating the binder and producing preforms for fibre-reinforced polymers

“…32 The thickness of the fabric is t = 0.75 mm (uncompressed), the density of E-Glass is approx. ρ GF = 2.6 g/cm 3 . Since the density of air ρ Air is much lower than the density of E-glass and can therefore be neglected, equation (1) results in a porosity of the fabric of f = 0.68 (uncompressed), which means that the fabric consists of approx.…”

“…An important part of the measurements is the determination of the air permeability of the stacked plies, the pressure difference and the resulting volume flow rate _ V as a function of the number of plies. The air permeability R is determined in analogy to standard ISO 9237 34 by using equation (3), where A represents the area. The permeability R corresponds to the average flow velocity of the air through the stacked plies.…”

“…The series production of continuous fibre-reinforced polymer (FRP) components with small to medium dimensions by means of Liquid Composite Moulding (LCM) processes, such as Resin Transfer Moulding (RTM) or Vacuum Assisted Resin Infusion (VARI), is based on formed semi-finished fibre products that are referred to as preform. [1][2][3][4][5][6][7][8][9][10][11] The process steps for manufacturing a preform mainly comprise production of flat fabrics (e.g., woven or multiaxial non-crimp fabrics in rolls) and their CAD-supported preparation as single flat layers that are stacked on top of each other. The following main step is the draping or forming of the multi-layer stack into the desired three-dimensional, near-net-shape geometry.…”

Empirically adapted model for the Handling of Variable Geometries with Vacuum-based Granulate Grippers

“…2). Previous research has shown that this combination of gripping principles can achieve a high adaptability for gripping mechanisms and therefore a capability for handling large varieties of objects [20][21][22]. This previous research also examined influences of the airflow rate and vacuum on the state of the granulate material, with a certain solidity of the granulate being reached for the best vacuum seal and thus the highest vacuum.…”

Binders Used for the Manufacturing of Composite Materials by Liquid Composite Molding

“…Subsequently [ 2 , 95 , 96 ], these technologies were improved and modified in order to achieve the required parameters of preforming process and preforms characteristics, while the binder systems were also adjusted to them in order to obtain the best properties for both the preform, including curved, and the finished product. In a comparative study of various commercial DFP tapes, it was found that thermoplastic binders are also suitable for producing bindered tapes with the desired properties, from which preforms with the required fiber volume fraction can be made [ 97 ].…”