DE19948664A1 - Injection of plastic around fiber mat in injection molding tool, for molding fiber reinforced plastics, comprises injecting plastic onto one side of mat, then the other, after slightly moving tool faces apart - Google Patents

Abstract

A fiber mat (11) is placed with one face against a first tool half (21) and held while plastic is fed into a space between the mat and the second tool half (22). Plastic passes through the coarse mesh mat to reach the surface of the first tool half. The first tool half is then slightly raised away from the fiber mat and the resulting gap filled with further plastic material (13).

Description

The invention relates to a method for insert molding a fiber mat Plastic in an injection mold, the fiber mat with one of their Surfaces adjacent to a first mold half of the injection mold is fixed in this and then a plastic material in the Space between the fiber mat and the second mold half of the injection molding tool is introduced.

The technical environment becomes an example referred to DE 197 32 425 A1.

In particular, long fiber reinforced plastic components can be manufactured bar that prefabricated and suitably shaped fiber mats with plastic overmolded material. Technically, a fiber mat can be used for this first on one of its two sides in a first plastic injection molding injection molded tool and then in a second art Injection molding tool are inserted, in which on the other side the plastic material is applied to the fiber mat. At least this however, the experimental procedure is relatively complex since two Injection molding tools are needed to implement the finished product Component between the two tools is time-consuming, and since Er aiming for an intimate connection between the one in the first injection molding plant plastic material applied and in the second injection molding machine the applied plastic material in the latter tool only reheated applied plastic material, d. H. be softened got to.  

Another method for encapsulating a fiber mat with plastic is in of the aforementioned DE 197 32 425 A1. Accordingly, one preformed thermoplastic hard film to increase the wettability of de pretreated surface, after which this thermoplastic hard film together with a fiber mat that is applied to the pretreated surface in an injection mold is inserted. This is then a polyurethane on the pretreated surface as well as on the fiber mat in one by the Mold geometry given wall thickness. This too The process is fairly straightforward because of the pre-production of the thermoplastic hard film complex, although despite the special measures to achieve a reaching connection between the thermoplastic hard film and the injected polyurethane an intimate connection is hardly attainable.

To show a method according to the preamble of claim 1, with wel chem a possibly suitably preformed fiber mat in a single spray casting tool without the use of an elaborately preformed plastic Component can be encapsulated with plastic, is the task of the present Invention.

The solution to this problem is characterized in that the fiber mat is so coarse-meshed that part of the plastic material introduced through the fiber mat to the first half of the mold, and that at then the first half of the mold at least partially slightly the fiber mat is lifted, after which in the resulting Gap between the fiber mat and the first half of the mold Plastic material is introduced. Advantageous further training is content of subclaims.  

According to the invention, the molding of the fiber mat is carried out in one Injection mold, and this is done successively on the two (Top) surfaces of the fiber mat (i.e. initially on the back thereof and then applied to the front) plastic material, wherein care is taken that the fiber mat itself with the art material is soaked. These measures lead to a special the intimate bond of the applied on both sides of the fiber mat Plastic materials and increase the stability of the art so manufactured fabric component with integrated fiber mat, especially long fiber mat, considerably.

Of course, it is necessary to apply the plastic masses or materials on the two sides of the fiber mat one after the other feed, otherwise the fiber mat will be deformed in the injection mold or would be molded into the plastic material in an undefined position. For this reason, the first step is the first waiter the surface or side (e.g. back) of the fiber mat the (first) plastic material sprayed on, the fiber mat with its second surface or side (e.g. front) on the first mold half of the injection molding machine stuff is present. Between the first side of the fiber mat and the second The mold half of the injection mold is the cavity, as usual Lich is filled with the (first) plastic material. The latter arises due to the relative coarseness of the fiber mat, this one, too that the fiber mat is or is soaked with plastic material. On closing must be on the other, second surface or side (e.g. front the side) of the fiber mat, a cavity can also be created from the Apply plastic material to the surface of the fiber mat to be able to. For this purpose - as indicated - the one facing this surface first mold half at least partially abge from the fiber mat  raised so that a gap is formed in the other plastic material can be introduced.

In the gap between the fiber mat and the first half of the mold Injection mold can be used to apply the additional plastic material on the second surface (e.g. front) of the fiber mat of this art material material by means of a suitable injection device from the side of the second half of the mold are introduced through the fiber mat, d. H. that the appropriate injection device through the fiber mat penetrates. Alternatively, the other plastic material from the side of it half of the mold in the gap between the fiber mat and it Most of the mold halves are introduced, which means higher quality art fabric components can be manufactured than in the first-mentioned method, however, this complicates the structure of the injection mold itself becomes.

Basically, it can be on the front and on the back Plastic material applied to the side of the fiber mat around the same mat act rial, but it is also possible to use different plastics to use materials. Then, however, the two materials should be one have a certain minimum affinity, d. H. the two materials should be inning be connectable or adhere well to one another. Is it im first process step applied or injected plastic mat rial, for example, around PC / ABS (= polycarbonate-acrylonitrile-butadiene-styrene), so can as a second plastic material, for example PC, which is used in the the rest both in a clear translucent form and in opaque form leadership is available.

If the fiber mat is to be completely encapsulated with plastic, it is of course necessary, the so-called first half of the mold  stuff on which the fiber mat still during the first process step is present for the second process step, in which the further art material is injected completely from the (second) surface of the Take off the fiber mat. However, should only be applied to partial areas of this (second) Surface plastic material are applied, or should be on this in second process step with the plastic material side a specially shaped cavity is created or ready in the injection mold be made, it may be necessary that the first half of the mold Injection mold is formed in several parts and divisible, so that individual Parts of these mold halves are lifted at different distances from the fiber mat can be.

In the following, the invention is explained in more detail on the basis of highly simplified depictions of the principles. In the sequence of figures 1 a- 1 d is shown a fiction, according manufactured, reinforced with a fiber mat plastic component in the following on each other method steps. The Fig. 2a, 2b gene zei the Herstelllvorgang this plastic component in an injection molding tool in two successive steps, while in the Fig. 3a, 3b, the plastic injection devices for the injection molding tool according to Fig. 2a, 2b rensschritten in two successive procedural are shown.

Reference number 10 (cf. FIG. 1d) denotes a plastic component which is to be produced by the method according to the invention and which, among other things, consists of a preformed fiber mat 11 , on the two surfaces of which plastic material 12 , 13 is or is applied, ie it not only on the back of the fiber mat 11, the plastic material 12 , but also on the front of the fiber mat 11, the plastic material 13 are brought on, so that the fiber mat 11 is ultimately encapsulated on both sides with plastic material 12 , 13 .

This quasi double-sided encapsulation of the fiber mat 11 takes place in a single injection molding tool 20 (see FIGS . 2a, 2b) which, as usual, has two mold halves 21 , 22 , between which in a cavity not shown (and consequently also not designated) the plastic component 10 is manufactured.

In a first processing or process step, the preformed fiber mat 11 , as it is shown as a starting component in FIG. 1a in perspective and in FIG. 1b in a side view, with its surface on the left in FIGS. 1b, 2a, 2b fixed to the first mold half 21 on the left in these figures in the exposed cavity of the injection molding tool 20 . Thereafter, the injection mold 20 is closed as usual, that is, for example. The first mold half 21 is moved in the opposite direction of the arrow 30 to the second mold half 22 , so that said cavity with the fiber mat 11 arranged therein is closed off from the environment. Plastic material is then introduced via an injection nozzle 23 into the space between the fiber mat 11 and the second mold half 22 into the cavity of the injection mold 20 , which is then deposited as a plastic material 12 on the so-called rear side of the fiber mat 11 adjacent to this space. This is shown figuratively in Fig. 2a.

This fiber mat 11 is relatively coarse-meshed, so that the plastic material 13 introduced into the injection mold cavity in the first method step penetrates into the fiber mat 11 and thus soaks until part of this plastic material reaches the first mold half 21 . After this first method step, the looks (so far not yet finished) plastic component 10 is thus the same as in Fig. 1c, Fig. 2a. Here you can see the plastic material 12 applied to the right-hand surface (or to the rear side) of the fiber mat 11 ; Furthermore, what is not shown in the figures is the fiber mat 11 impregnated with plastic material 13 .

In the subsequent second processing or process step, which is shown in Fig. 2b, the first mold half 21 is slightly lifted from the Fa sermatte 11 , which is equivalent to the fact that the first mold half 21 is moved slightly to the left according to arrow direction 30 . By appropriate design of the Spritzgiesswerk tool 20 is not shown but the cavity of the injection mold 20 ge genüber around remains closed. Of course, the fiber mat 11 with the applied plastic material 12 , that is, the plastic component 10 manufactured so far, remains in the cavity of the injection molding tool 20 , but the original fixation of the fiber mat 11 on the first mold half 21 is released. The result of this is that the plastic component 10 remains in contact with the second mold half 22 with its rear side, ie with the side on which the plastic material 12 is located. This results in particular from the fact that the layer of plastic material 12 is still connected to the associated injection nozzle 23 , which is provided in the second mold half 22 . In this regard, reference is made in advance to FIGS . 3a, 3b, which will be explained in more detail later.

Since, as just described, the plastic component 10 remains in the cavity of the injection mold 20 in the cavity of the injection molding tool 20 when the first mold half 21 is lifted off the fiber mat 11 against the second mold half 22 (on the right in FIGS . 2a, 2b) ) Injection molding tool 20 or in its cavity a gap between the fiber mat 11 and the first mold half 21 . In the following, further plastic material is injected into this gap space, specifically via an appropriately arranged injection nozzle 24 . Corresponding to the respective geometrical relationships, the figures in the figures are thus.

1b-1d and 2a, 2b the left-hand surface or front of the fiber mat 11 the (further) plastic material 13 applied.

At this time, the applied in the first step of the process and introduced into the fiber mat 11 itself plastic material 12 is not yet fully cured, so that the now applied (further) plastic material 13 can enter into an intimate connection with this plastic material 12 applied first. The result or the finished plastic component 10 , as can subsequently be removed from the injection mold 20 after removal of the injection channels, is shown in FIG. 1d. As can be seen, the fiber mat 11 is now injected with plastic, that is, in the fiber mat 11 itself and on the back of the initially applied plastic material 12 and on the front side of the plastic material 13 is provided, these two materials being best connected to each other.

With reference to FIGS . 3a, 3b, a possible arrangement of the injection nozzles for the plastic materials 12 , 13 in the injection mold 20 is explained below. The simplest tool construction is obtained if (different from the illustration in FIGS. 2a, 2b, in which the injection nozzle 23 on the non-movable mold half 22 and the injection nozzle 24 on the movable mold half 21 are provided) both the injection nozzle 23 for the (first) plastic material 12 , as well as an injection nozzle (s) 24 for the further plastic material 13 in the non-movable second mold half 22 of the injection mold 20 is or are. Fig. 3a shows the first step in which the second injection nozzles 24 are closed by means of a slide 301 and the first plastic material 12 through the first injector 23 cavity injection mold is introduced into the. FIG. 3b shows the second step in which the first injection nozzle 23 closed by means of a slider 301, and the other plastic material 13 through the second injection nozzles 24 through the fiber mat 11 and into the injection mold cavity, on the other side of the fiber mat 11 is brought into the gap between this and the first mold half 21 .

From these two FIGS . 3a, 3b it can also be seen that - as explained above in connection with the second method step - when the first mold half 21 is lifted off the fiber mat 11, this together with the (first) plastic material 12 already applied to the second Mold half 22 remains in contact, so that the gap mentioned above can form between the fiber mat 11 and the first mold half 21 . The fiber mat 11 with the plastic material 12 is (also) held against the second mold half 22 by the first injection nozzle 23 or by the associated injection channel; further by the slide 301 of the second injection nozzles 24 , which must keep the injection channels free, via which the further plastic material 13 can pass through the fiber mat 11 into the said gap space between the fiber mat 11 and the first mold half 21 .

However, it is not absolutely necessary for the injection nozzle (s) 24 to be provided for the further plastic material 13 in the second mold half 22 ; rather, in the second process step described, the further plastic material 13 can also be introduced from the side of the first mold half 21 into the said gap space between the fiber mat 11 and the first mold half 21 , as is shown in principle in FIGS. 2a, 2b. The latter is particularly recommended if the (further) plastic material 13 is optically transparent in the cured state and / or different from the plastic material 12 injected in the first method step.

If the plastic materials 12 , 13 have at least a certain minimum affinity for one another, the method described results in a particularly good material connection through the fiber mat 11 . This enables particularly stable plastic components 10 to be produced, the fiber mat 11 provided as reinforcement also being able to be laid out eccentrically, ie from the neutral fiber, in order to be able to absorb additional forces on / in component 10 , but this and one Numerous other details may be designed differently from the above explanations, without leaving the content of the claims. The fiber mat 11 can also consist of one or more materials) or material (s) that are or are little or not affinity to the plastic materials 12 , 13 used . For example, a metallic fiber mat 11 can be used, as materials 11 with special properties (for example flame-retardant) can be used for the fiber mat 11 . With the method described, there is always an optimal integration of the fiber mat 11 into the overmolded plastic materials 12 , 13 .

Reference list

10th

Plastic component

11

Fiber mat

12th

(first) plastic material

13

(further) plastic material

20th

Injection mold

21

first half of the mold

22

second mold half

23

Injector (for

12th

)

24th

Injector (for

13

)

30th

Arrow direction: movability of

21

301

Slider (in

23

,

24th

)

Claims (7)

1. A method for overmolding a fiber mat with plastic in an injection molding tool, the fiber mat ( 11 ) with one of its upper surfaces on a first mold half ( 21 ) of the injection molding tool ( 20 ) being fixed in this and then a plastic material ( 12 ) in it the space between the fiber mat ( 11 ) and the second mold half ( 22 ) of the injection molding tool ( 20 ) is brought in, characterized in that the fiber mat ( 11 ) is so coarse-meshed that part of the plastic material ( 12 ) introduced through the fiber mat ( 11 ) passes through to the first mold half ( 21 ), and that thereafter the first mold half ( 21 ) is at least partially lifted off the fiber mat ( 11 ), after which the resulting gap between the fiber mat ( 11 ) and the first mold half ( 21 ) additional plastic material ( 13 ) is introduced. 2. The method according to claim 1, characterized in that the further plastic material ( 13 ) by means of a suitable injection device from the side of the two mold halves ( 22 ) through the fiber mat ( 11 ) into the gap between the fiber mat ( 11 ) and first mold half ( 21 ) is introduced. 3. The method according to claim 1, characterized in that the further plastic material ( 13 ) from the side of the first mold half ( 21 ) is introduced into the gap between the fiber mat ( 11 ) and the first mold half ( 21 ). 4. The method according to any one of the preceding claims, characterized in that the further plastic material ( 13 ) ver different from the first injected plastic material ( 12 ), but is affinity to this in terms of sufficient adhesion. 5. The method according to any one of the preceding claims, characterized in that the first mold half ( 21 ) is divisible, so that only one or more parts thereof are lifted off the fiber mat ( 11 ) before the introduction of the further plastic material ( 13 ). 6. The method according to any one of the preceding claims, characterized in that the fiber mat ( 11 ) is suitably preformed before insertion into the injection molding machine having a suitably shaped cavity ( 20 ). 7. The method according to any one of the preceding claims, wherein the fiber mat ( 11 ) consists of one or more material (s), which are little affinity to the plastic materials ( 12 , 13 ).