DE10106183A1 - Making components by re-forming continuous fiber-reinforced boards or pre-pregs, melts them only locally, for re-formation - Google Patents

Abstract

The invention relates to a method for forming continuously fiber-reinforced plastic blanks. So far, the entire board has been melted to form continuously fiber-reinforced plastic boards. This leads to fiber reorientation in the entire board, even if the actual forming takes place only at local locations and otherwise it is essentially a reconsolidation of the board. The solution to the problem is to melt the plastic circuit board only locally, and thus only locally. This is shown in Figure 1. Only a small local area (1) of the continuously fiber-reinforced plastic board is melted. After the desired temperature has been reached, the heated area is formed. In the deformed area (2) the fibers have reoriented. In the remaining area of the plastic board (3), which was not heated, the original fiber orientation is retained.

Description

The invention relates to a method for local forming of components continuously fiber-reinforced plastic boards, according to the preamble of Claim 1.

Continuously fiber-reinforced semi-finished plastic products, so-called organic sheets, can today be economically manufactured using double-band press technology or prepreg technology (DE 197 34 417 C1). These serve as the starting material for the manufacture of thin-walled, heavy-duty structural components. To produce two- or three-dimensional molded parts, the semi-finished products must first be heated above the melting temperature of the thermoplastic by means of a heating station. Forming is carried out by positioning heated sheets between the upper and lower tools in a press and immediately closing the mold halves, which are tempered if necessary. During the cooling of the molded part to the mold temperature, the plastic solidifies, so that the fully consolidated molded part can be removed after opening the press [Ziegmann, G .: Forming in the diaphragm method. In "Fiber composite materials with a thermoplastic matrix". Bartz, WJ (Ed), Expert Verlag, Renningen Malmsheim ( 1997 ), pp. 143-160], [O'Bradaigh, CM, Pipes, RB, Mallon, PJ: Issues in Diaphragm Forming of Continuous Fiber Reinforced Thermoplastic Composites. Polymer composites. 12 ( 1991 ) 4, pp. 246-256], [Breuer, UP: Contribution to the Forming Technology of Reinforced Thermoplastics. Progress reports VDI-2/433, Düsseldorf: VDI-Verlag 1997 ], [Börger, H .: Forming with positive / negative pressing tools (Match Mold process). In "Fiber composite materials with a thermoplastic matrix". Bartz, WJ (Ed), Expert Verlag, Renningen Malmsheim ( 1997 ), pp. 132-142].

The complete plastic board in one is known from the prior art separate radiator field outside the press, usually with infrared radiators heat and then reshape in a single-cavity mold.  

This leads to the following problems: The subsequent shaping warps the reinforcing structure and, in addition to the reorientation of the fibers in the shaping zone ( 6 ), the fibers in the rest of the board ( 7 ) are also reoriented, see FIG. 2. The properties of the fiber composite Which are defined by the predefined fiber orientations of the board ( 4 , 5 ) are significantly influenced by the reorientation of the fibers. Even deviations from a few degrees of angle lead to significant changes in the mechanical properties of the composite [Ehrenstein, GW: fiber composite plastics. Munich. Carl Hanser Verlag 1992 ], [Erhard, G .. Construction with plastics. Munich. Carl Hanser Verlag 1998 ]. Heating the entire circuit board also leads to an unnecessarily high energy consumption and extended process times, since the heating power can only be insufficiently focused with convective heating and with radiation sources. The use of contact heating poses problems due to the fact that the melted polymer adheres to the heating plates. No other heating options known from the field of welding fiber-reinforced plastics, such as vibration heating or inductive heating, have yet been used [Rudolf R .; Mitschang P .; Neitzel M .: Welding of high-performance thermoplastic composites Polymers & Polymer Composites Vol. 7 ( 1999 ), No. 5, pp. 309-315]. By influencing the fiber orientation over a large area, only one component can ever be formed from a blank without further measures (DE 199 44 164). Other major disadvantages of today's procedure are the difficult handling of the melted and thus limp boards and the need for hold-down or tracking systems for crease-free forming.

The object of the invention is a locally limited by a modified heating Forming of the board and thus a local reorientation of the Enabling reinforcement fibers without the basic properties of the rest To influence circuit board. This approach is intended to save energy and contribute to simplified litigation.

This object is achieved by the method having the features of claim 1.  

Due to the locally limited heating of the blank to be formed, only the fiber areas that are located within the melted area are allowed to reorient. Fig. 3 shows the reorientation of fibers in the melted zone ( 8 ) and the unaffected fiber orientations ( 4 ) and ( 5 ). Only as much energy is put into the board as is needed for the local heating. Due to the fact that the unheated areas of the board are still solid, this procedure allows easy handling of the board with standard handling systems. The forming itself is limited to the necessary area and therefore does not represent a problem area for the fiber orientation of the environment. Retention and tracking systems can therefore be dispensed with.

Embodiments of the invention are shown in the drawings and are described in more detail below. Show it

Fig. 1 locally deformed board (3) to the heating zone (1) and the reshaping area (2)

Fig. 2 reshaped board with base fiber orientation (4) and (5) re-orientation in the forming region (6) and disorientation in the circuit board (7)

Fig. 3 locally deformed board with base fiber orientation (4) and (5) re-orientation in the forming area (8)

Fig. 4 coupling element made of circuit board ( 10 ) with bearing ( 9 )

Fig. 5 circuit board (11) for multiple forming in a press stroke with 8 local Aufheizstellen (12)

Variants for producing elements of a coupling gear from fiber-reinforced plastic blanks (blanks) in the forming process are described here as exemplary embodiments. When producing such coupling elements ( Fig. 4) from flat boards ( 10 ), only the areas for the installation of the bearings ( 9 ) have to be reshaped. The rest of the board is flat. For the elongated component, the alignment of the fibers in the longitudinal direction is extremely important for the bending properties. The local heating of the board outside the forming tool can be done with the help of panels for conventional heat sources, such as. B. infrared radiators or adapted heating sources (spiral filament) can be performed. Other heating methods, such as B. Contact heating is also conceivable. When using carbon fibers as reinforcing fibers, inductive heating is advantageous because it can be used very quickly, without contact and in a targeted manner. Because of the local heating and the smaller amount of heat required for this, the reduced energy costs are a further advantage. The area to be consolidated (corresponding to the melted area) is also smaller, which allows lower press forces and thus the use of smaller presses.

When using an inductor for energy input, more can process-related advantages can be achieved. The inductor can in that Forming tool can be integrated, creating a separate Heating device and more complex transport unit can be dispensed with. In addition to the financial savings, the cycle time is due to the fast inductive Warming and the loss of temperature loss due to transport clearly be lowered. The handling of a stiff, cold plastic board is much easier than that of a melted board. By the local Heating and reshaping becomes a fiber orientation in the unheated Areas prevented.

Another major advantage can be achieved by using multi-cavity molds. As described, the area of a circuit board that is not to be formed remains unaffected by the deformation during local heating. This means that several identical or different geometries can be formed in one tool during a press stroke. Fig. 5 shows as a circuit board (11) which is exemplary here heated at 8 by local agents in order to provide an appropriate tool in a press stroke the installation space for 8 stock. Four coupling elements can be obtained directly from the formed board by later trimming or punching.

The type of reinforcing fibers (glass, carbon, aramid, polymer, natural fiber, etc.), the reinforcement structure (woven, laid, knitted, braided, etc.) and the matrix (polyamide, polypropylene, polyether ether ketone, etc.) can be used with the fiber reinforced thermoplastic plastic boards vary.

Claims (10)

1. A process for the production of components by reshaping continuously fiber-reinforced plastic boards, characterized in that the fiber-reinforced plastic board is locally melted at one or more locations and then reshaped at these locations. 2. The method according to claim 1, characterized in that the heating outside the forming tool with the help of covers for conventional Heating sources, such as B. infrared heater or customized Heating sources (e.g. spiral filament) occur. 3. The method according to claim 1, characterized in that the heating for carbon fiber reinforced plastic boards using inductive Warming takes place. 4. The method according to claim 1 and 3, characterized in that the inductor is integrated in the forming tool. 5. The method according to claim 1 to 4, characterized in that in the Forming tool of several cavities, so that one on several Place melted blanks locally several times in one press stroke can be reshaped. 6. The method according to claim 1 to 5, characterized in that it is the cavities by an identical or geometrically different Component can act. 7. The method according to any one of the preceding claims, characterized characterized that the semi-finished products are semi-finished products with different reinforcement structures such as fiber fabric, fiber fabric, Fiber mats, knitted fabrics, knitted fabrics or unidirectional Reinforcements.   8. The method according to any one of the preceding claims, characterized characterized that the semi-finished products were completely impregnated or also partially impregnated laminates (so-called prepregs). 9. The method according to any one of the preceding claims, characterized characterized that the plastics used are thermoplastic of any Can be kind. 10. The method according to any one of the preceding claims, characterized characterized in that the reinforcing fibers used in the Semi-finished products of any kind can be, mainly carbon, aramid, Glass, polymer or natural fibers.