WO1989005718A1

WO1989005718A1 - Process and compression mould for manufacture of composite parts

Info

Publication number: WO1989005718A1
Application number: PCT/SE1988/000682
Authority: WO
Inventors: Gunnar Westerlund
Original assignee: Ab Volvo
Priority date: 1987-12-16
Filing date: 1988-12-14
Publication date: 1989-06-29
Also published as: SE8705017L; SE8705017D0; SE460271B

Abstract

A method and mould tool for producing plastic composite products having large surface areas, e.g. floors for automotive vehicles. A batch of material comprising plastics material which has fibres admixed therewith is sprayed onto a mould surface (10) on one mould half (1). A second multi-part half (13) is pressed in stages against the material, as the material is charged to the mould surface.

Description

Process and compression mould for manufacture of composite parts

The present invention relates to a method for manufac¬ turing composite components, in which a mixture of plastics material and reinforcing material is pressed between mould halves. The invention also relates to a mould tool for carrying out the method, said tool comprising first and second mould halves which can be brought together so as to define a mould cavity there¬ between.

Certain vehicle parts have been produced from composite materials within the vehicle manufacturing industry for some considerable time. This manufacture is primarily concerned with such vehicle body parts as wings, engine covers, rear deak lids (boot covers) and like vehicle parts made from reinforced thermoεetting resins, prefer¬ ably reinforced polyester plastics, and then primarily in respect of motor vehicles which are produced in relatively small numbers. Other methods generally known in the art for manufacturing vehicle parts such as those afore- mentioned include wet pressing, injection and SMC-preεεing methods. The two first mentioned methods are used in con¬ junction with preform glass-fibre reinforcements in which the glass fibres have been bonded together to form a readily handled body having a shape which conforms to that of the finished product. In the case of the wet pressing method, this preform is placed in the bottom part of a mould and wetted with liquid plastic, which is poured over the preform with the form open, whereafter the mould is closed. In the case of injection methods, the plastic is injected into the mould cavity subsequent to closing the mould. When applying SMC-pressing methods there is used a starting material which comprises a mixture of fibres. resin and filler, which forms a leather-like sheet. A number .of such sheets are placed on part of a otrld sur- . face and flow plastically during the pressure ρha.se, to fill the mould cavity.

A common feature of the aforedescribed methods is that they require the provision of an intermediate product, which consequently requires the provision of intermediate . storage facilities, and none of these methods is suitable for direct application in the series manufacture of com¬ ponents which have large surfaces. When using the^" wet pressing method to produce large surface components, there is a risk that the plastics material first applied will begin to harden before the mould is closed, unless a slowly hardening plastics mixture is used. This would render the process too long for rational series produc¬ tion. he injection method is also too slow to fulfil present day requirements of rational production processes. The SMC-method is encumbered with a multiple of drawbacks, one of which is that the spread of mechanical strength values throughout the finished product is too excessive, due to unfavourable material flow.

The object of the present invention is to provide a method which can be used to manufacture composite products having large surfaces, and particularly surfaces which are seve¬ ral square meters in area, e.g. complete vehicle floors, while avoiding the drawbacks of the aforesaid methods and while enabling such products to be produced rationally and in series.

This object is achieved in accordance with the invention by spraying onto a mould surface of one mould half a batch of material which comprises a liquid plastics mixture having reinforcing fibres admixed therewith, and by press¬ ing the mould batch in stages between said mould surface and another, multi-part mould half. A mould tool for carrying out the method will have at least one mould half which is divided into several sepa¬ rate parts which can be moved individually in relation to the other mould half, so that the tool can be closed in stages, as material is sprayed onto the mould surface of the other mould half.

This combination of the known "spray-up" technique with εtagewise pressing of the material affords several advan- tageε. The fact that both fibres and liquid matrix mate¬ rial (plastics) are charged directly to the moulding tool eliminates the need to store semi-manufactured products or preforms and thus provides the shortest route from raw materials to finished product. The fact that the material is pressed in stages means that said material need only lie against the mould surfaces for a very short period of time before being compressed. This enables large surface components to be produced from reactive quick-setting thermosetting resin systems, therewith resulting in short process times. The departure of gases, such as styrene and solvent, from the mould batch is restricted, since the whole of the mould batch is never exposed, therewith bene- fitting the environment.

The method according to the invention is described below with reference to the accompanying drawing, in which Figure 1 is a perspective view of a bottom mould half and a robot spray. Figure 2 is a schematic, perspective view illustrating the various steps of the inventive method, and

Figure 3 is a sketch which illustrates the constructional principles of a mould tool.

In Figures 1 and 2 the reference 1 identifies a bottom mould half or mould part of a mould tool which is refer¬ enced generally with 2 and which has an upper mould half 3 which is divided into four mutually separate mould parts 4, 5, 6 and 7. The mould partε 1, 3 define therebetween a mould cavity for moulding a floor laminate consisting, for' instance, of a polyester plastic reinforced with glass , fibre.

As illustrated in Figures 1 and 2, a robot 8 equipped with a spray/fiber cutter 9 sprays a plastics mixture admixed with glass fibres directly onto the mould surface 10 of the bottom mould half. Respective mould quarters 4-7 are lowered onto and pressed against the bottom mould half 1 and the material thereon rhythmically, in time with the application of material onto said bottom mould half. The

. requisite "mould pressure", in the order of 0.1 bar, can be achieved by loading the mould partε 4-7 individually - with the aid of preεsure exerting devices (not shown), e.g. compressed air piston-cylinder devices, in principle the same manner as that employed with conventional press tables. Lower mould pressures can be achieved, by suitable adaptation of the weight of the mould parts 4-7, such that it will suffice simply to lower the mould partε into place on the bottom mould half.

In Figure 1, the reference poε. 1 indicates the εtep at which material is charged to the bottom mould half. poε. 2 indicates the step in which the material is compacted subsequent to all four mould parts having been placed in position with the aid of a crane 11, poε. 3 indicates the step in which the material is hardened, and pos. 4 indi- cates the step in which the finished floor laminate 12 is removed from the mould, subsequent to lifting away the top mould half.

Figure 3 illustrates schematically a mould tool whose top mould half 13 is divided into five mould parts 14, 15. 16, 17. 18, which are located sequentially in the longitudinal direction of the tool. Although not shown, the mould parts are provided with guides and force exerting devices, for instance hydraulic or compressed air piston-cylinder de¬ vices for displacing the mould partε in the direction of the arrows shown in the Figure, and in opposite directions.

When applying material to the mould surface 10 of the bottom mould half 1, the robot 8 begins, by spraying material onto a region of the surface located opposite the mould part 14. Immediately this region of the surface has been coated with material, the mould part 14 is pressed against the material on the oppositely located region of the mould surface 10. Charging and pressing of material is carried out sequentially and in stages, in a corresponding manner (from left to right as seen in Figure 3), until finally the terminal mould part 18 is pressed against the underlying mould surface.

The mould partε 4-7 and 14-18 respectively may be cold or heated, depending on the type of plastics material to be moulded and on desired hardening times. The heat transfer between mutually adjacent moulds can be limited as far as poεsible, by providing the εides of the mould parts with recesses 20, so that the mould partε will only present small contacting surfaces therebetween, as illustrated in Figure 3.

In addition to those advantages mentioned in the afore¬ going, the division of a mould half into separate sections in the aforedescribed manner affords the additional advan¬ tage of enabling the moulded product to be given a pro¬ nounced undercut, as will be seen from the part 21 located opposite the mould part 14.

Claims

1. A method for producing composite material components, in which a plastics mixture admixed with reinforcing mate¬ rial is pressed between mould halves, characterized by spraying a material batch comprising liquid plastic having reinforcing fibres admixed therewith onto a mould surface on one mould half, and pressing material charged to the mould in stages between said mould surface and a mould surface on a further, multi-part mould half.

2. A mould tool for producing composite material com¬ ponents, comprising first and second mould halves which can be brought together to define a mould cavity there¬ between, characterized in that at least one mould half (3; 13) is divided into several separate parts (4-7; 14-18) which are movable individually in relation to the other mould half (1), such as to enable the mould tool to be closed in stages as material iε applied to the mould surface (10) of the other mould half.