Method and apparatus for producing moulded parts from curable plastic material.

p0001The invention relates to a method for producing a relatively thin-walled and large-area F ormteiles of hardenable, in particular laminated material, for example plastic, in which the material is filled into a closed, at least by a stretchable foil and a positive and / or negative mold limited mold space and the same is distributed by vacuum and / or pressure uniformly over the mold surface and to an apparatus for performing the method.

p0002From DE-OS 32 06 905 describes a process for producing reinforced moldings made of laminated material, for example plastics material is known in which on the molding surface of a positive or negative form a stretchable film and against chemical influences of the material as well as against the thermal mechanical stresses is the forming process resistant, is placed or clamped. Then, based on this film a layer of fiber mats, for example Glaserfaser- or carbon fiber mats, which is used to form the actual supporting layer of the molded part. After the preparation of this support layer, a second film is placed on the same, which consists of the same material as the first film and the products to be in the edge region outside the

p0003Molding is sealed to the first film or clamped together with it. Before the final sealing of the two films a predetermined amount of a curable plastic is between them is filled, the distributed after the application of a vacuum to the mold cavity uniformly over the mold surface and forms the supporting layer of the molded article after curing. If necessary, it is possible to be cured plastic and subsequently sealing introduce films joined together between the two and to distribute by vacuum and / or pressure in the mold cavity or over the mold surface.

p0004In this and other known processes for the production of moldings of curable, laminated material flawless moldings should only be achieved if it is ensured and it is achieved that the material reaches all parts of the molded article and all fiber mats are properly impregnated with plastic. This is when the molded parts are relatively thin-walled and large-area, difficult to achieve. This requires, for example, form a special floating zone between two fiber mats, which consists for example of a Sisalmatte, a wire mesh or a PUR-spun. This particular flow zone increases inevitably but again the wall thickness of the molded part. On the other hand brings this flow zone with it, that produced plastic moldings are not transparent.

p0005The invention is therefore the object of disclosing a method for producing a relatively thin-walled and large-area molding of hardenable, in particular laminated material, such as plastic, is ensured by means of which even at very low wall thicknesses, that the

p0006Material well, but especially in the time available, and evenly distributed over the mold surface so that particular inlaid fiber mats are soaked properly. Furthermore, a device is to be created, with which this method can be performed.

p0007To achieve this object it is proposed according to the invention in a method of the kind described above, that indicates, in a distributed grooves positive and / or negative mold which is at least partially retracted in the same form-fit fitting foil by pressure and / or vacuum in the grooves and flow channels are formed in that the material is introduced through the flow channels under pressure and / or vacuum evenly in the mold cavity and distributed over the mold surface and that in the end of the distribution or molding operation, the necked in the grooves carrier sheet by pressure and / or vacuum the plane of the mold surface is moved back.

p0008Such a process ensures that very thin, in particular reinforced moldings can be prepared properly. When using plastic as a curable material, transparent moldings with very thin wall thickness, for example less than 1.0 mm, can be achieved.

p0009Other features of the method according to the invention and an apparatus for performing the method are described in claims 2 - 13 disclosed.

p0010The invention will now be described in a drawing in a simplified, not to scale illustrated embodiment with reference to a. show case<ul><li>Fig. 1 shows a section through a device for implementing the method according to the invention in the basic position,</li><li>Fig. 2 shows the device of Fig. 1 in the flow position, and</li><li>Fig. 3 is a plan view of a positive or negative trained shape.</li></ul>

p0011In the drawing, one consisting for example of wood mold 1 is shown, which mold surface 2 is formed for ease of illustration as a flat surface. The figures show only the central or inner area of ​​the mold 1, which may be externally provided with a rim, not shown. In the mold surface 2 a plurality of grooves 3 are worked, which have rectangular cross-section in this embodiment. Registered 3 the grooves extend at a predetermined distance parallel to each other (Fig. 3). The shape and size of the cross section of the grooves 3 can be largely selected as desired. Due to tests carried out the cross-section of such a groove 3 should be at least 4 mm². A size 40 mm² should be inexpedient.

p0012On the provided with the grooves 3 form a surface film 4 is then placed which is made of transparent, as well as light, UV and IR radiation permeable plastic. In addition, these films must be stretchy, but especially good resettable. 4 The film 4 is so large that it extends beyond the edge of the mold, not shown, the first Thereafter, an existing fiber mats such as fiberglass or carbon reinforcement mats 5 up dry on the slide. 4 The reinforcement 5 may consist of one or more fiber mats. This reinforcement 5 ends at the edge of the mold 1. Then, a film 6 is applied on the reinforcement 5, which consists of the same material as the film. 4 This film 6 projects over the edge of the mold 1 also. In the area of ​​the rim, the two films are then connected or 4.6 braced sealingly together.

p0013In the area of ​​the grooves 3 open in the drawing, not shown, channels, which are led outward and connected there to a vacuum device. Once through these channels to the grooves 3 a vacuum is applied, this results in that the film deforms 4 and retracts into the grooves 3, as shown in Fig. 2. It is also possible to apply the film 4 before applying the reinforcement 5 on the upper side or of the free surface with pressure so that the foil 4 is pressed into the grooves of the third A complete or form-fitting filling the grooves 3 by the slide 4 is not absolutely necessary.

p0014As soon as the film 4 has taken the position shown in Figure 2 in the grooves 3, is one curable material, for example plastic, introduced via openings in the boundary not shown in the shape of the formed film formed by the flow channels 4 seventh This plastic can be either performed by pressure in these flow passages 7 and thus distributed over the mold surface 2 in the reinforcement fifth If necessary, it is also possible to apply to the limited of the sheets 4,6 form a vacuum chamber 8, so that the first curable resin is drawn into the flow passages 7 and is distributed from there over the mold surface 2 in the reinforcement fifth Further, it is possible that at the same pressure and vacuum are effective. Through the flow channels 7 is ensured that the curable plastic fills the mold cavity 8 is completely, so that the reinforcement 5 is completely saturated. If needed, the

p0015Channels, can be applied through the vacuum to the mold cavity 8, also be designed as overflow channels.

p0016Once it is ensured that the mold cavity 8 is completely filled with curable plastic, the voltage applied to the grooves 3 vacuum is released. This gives the film 4 raises back into its initial position of FIG. 1. This provision is in this case supported by the vacuum that is applied to the mold space. 8 Once assured that the film 4 has resumed its initial position according to FIG. 1, may, if it is not to plane moldings, initially carried out a deformation of the as yet uncured reinforcement 5 and the laminate in the opposite direction of the mold 1, and then the curing process start or be initiated.

p0017In modification of the described embodiment, it is possible to replace the foil 6 by a shell part or an additional part of the mold first It is not necessary that the impregnated plastic reinforcement 5 cures in the form. 1 This completely impregnated reinforcement 5 can be placed with the associated slides 4.6 in a particular way of working, in which the film package is molded with the impregnated reinforcement 5 through a kind of deep-drawing process. For the case that the mold 1 is associated with an upper part 3 can be incorporated in same, grooves, in which then the film 6 is retracted. Thereby, the flow process of the plastic or the impregnation of the reinforcement 5 can be further improved. It is also possible to make two mold parts which are soaked from each other by a special foil. The inventive method is also applicable when, for example, on a shell part of reinforced plastic a coating that is also called a gelcoat or gel coat, to be applied. Since such a cover layer is extremely thin, the flow operation is also facilitated by the flow channels and accelerate, so that even very large areas can be provided with a very thin layer of a modified liquid resin. Finally, it is possible to replace the positive and / or negative mold by a grooved roll or a grooved conveyor belt, so that a constant cross-sectional shape or semi-finished part can be manufactured continuously.

p0018In modification of the described embodiment, it is also possible to form the grooves or the flow channels 7 in a special glass or paper mat, which is introduced in the reinforcement 5 between the reinforcing mats. After uniformly distributing the cured plastic then the grooves or flow channels 7 formed in the impregnated glass or paper towel being deformed or compressed by pressure and / or vacuum, so that no appreciable influence on the wall thickness is formed. If desired, such a non-woven glass or paper are also used in addition to the grooved shape of the first