WO2015086199A1

WO2015086199A1 - Film hinges made of fibre-reinforced plastics and manufacturing process

Info

Publication number: WO2015086199A1
Application number: PCT/EP2014/072124
Authority: WO
Inventors: Philipp Seidl; Nikolaus Feichtenschlager
Original assignee: Lisa Dräxlmaier GmbH
Priority date: 2013-12-11
Filing date: 2014-10-15
Publication date: 2015-06-18
Also published as: DE102013020494B4; MY196091A; DE102013020494A1

Abstract

A method for producing a fibre-reinforced plastic component (30) comprising a film hinge (31), wherein the method comprises the steps of: melting a plastic laced with fibres in an injection moulding tool (1); foaming the plastic using a foaming agent; injecting the foamed plastics material into a component mould (20) which has a part for forming a film hinge (31); solidifying the plastic component (30) and removing it from the component mould (20). A component (30) comprising a film hinge (31) made from a fibre-reinforced foamed plastic. A film hinge (31) made from a fibre-reinforced foamed plastic.

Description

FILM CHARNERS OF FIBER REINFORCED PLASTICS AND

PRODUCTION METHOD

Technical area

The invention relates to a method for producing a synthetic material component with a film hinge, such

Component and a film hinge made of plastic, in particular for use in vehicle construction.

Background of the invention

From DE 10 2009 056 111 AI a transport device for receiving coffee cups with a film hinge is known. DE 103 08 246 AI describes a bearing shell made of plastic, by means of an injection molding process

is manufactured and has a film hinge. Because the

Stretching of the film hinge during assembly is particularly low, fiber reinforced materials can be used without the risk of destroying the

Film hinge during assembly is. Also from the US 2005/0244773 AI is a part with a film hinge

previously known.

DE 102 50 765 AI describes a method for producing a hinged flap during injection molding of a molded part of a glass fiber reinforced plastic. By forming a notched portion between a main body of the molding and a flap into which a strip of flexible material is inserted, a hinge is made. The hinge is made in a separate working cut by injecting a flexible plastic such as TPE. The reason for this and for the resulting multi-part of the component in the prior art is that the production of film hinges

glass reinforced plastics was previously not possible because they break after only a few opening and closing attempts.

On the other hand, fiber reinforced, especially glass fiber reinforced, plastics are often desirable due to the strengths and stiffnesses achieved by the fibers, and are indispensable in some applications, particularly in the automotive industry.

General description of the invention

An object of the invention is to provide a method for producing a fiber-reinforced plastic component with a film hinge with reduced manufacturing costs, reduced component weight and / or a reduced number of component components, such a plastic component and a corresponding film hinge.

The object is achieved with a method according to claim 1, a component according to claim 12 and a film hinge according to

Claim 15 solved. The dependent claims indicate embodiments of the invention.

The invention aims to provide a component of a

fiber reinforced plastic with a film hinge,

preferably in one piece, to provide. This will be a

fiber-containing plastic melted in an injection mold. The fibers can be added to the plastic melt in the injection mold or the plastic can with already contained fibers in the

Injection mold are introduced. Preferably, the Plastic as granules before and is introduced about a funnel in the injection mold. The tool may in this case be, for example, a rod casting system or a hot runner system provided with a needle closure. Preferably, screw extruders are used, wherein the supplied plastic or the supplied Kunststoffstoffgranulat by

Rotating the screw and supplying heat from the outside, for example by heating bands, and by (internal)

Scherwärme is melted into a thermoplastic mass and transported through the screw flights.

The plastic is made by means of a foaming agent

frothed. This happens, for example, during the so-called physical foaming during or after the Aufschmelzung by a gas, preferably nitrogen, is introduced under pressure into the melt. Alternatively or additionally, the foaming can be achieved by means of a blowing agent added to the plastic. This procedure is called chemical foaming.

The foamed plastic melt is injected into a cavity of a component mold having a portion for forming a film hinge. The component form is effectively the template for the component. It has the cavity whose contour corresponds to the component. For this purpose, the component form is expediently multi-part,

preferably in two parts, provided to allow easy opening and closing of the component. The injection of the plastic melt takes place in the closed state. To remove the solidified component, the component form is opened.

By the term "film hinge" may be an area, preferably rectilinear extent, with tapered

Wall thickness to be understood. The wall thickness is determined so that the nature of the film hinge, including in particular the flexibility and Strength, a hinge-like pivoting of the component allows without this breaks. More specifically, the component has a first component portion and a second component

Component section, which are connected to each other via the film hinge. The two component sections can be pivoted relative to one another via the film hinge, which can also be referred to as a "film hinge." For this purpose, the film hinge preferably has a material thickness in the range from 0.5 to 0.8 mm, more preferably approximately 0.65 mm on.

It is important that the film hinge itself, as part of the component, consists of a fiber-reinforced, foamed plastic. The term "component" can be understood here to mean that, in addition to the film hinge one or more

Sections are present, which have a much lower flexibility compared to the hinge, until the complete disappearance of the bending ability, and the

preferably have a special functionality, for example, by serving as fasteners.

After injection of the foamed KunstStoffmasse in the component form this is solidified, and then the component can be removed from the component form.

Due to the change in viscosity of the plastic melt during the foaming process and the change in the

Flexural rigidity on the finished component makes it possible to use different hinge geometries of materials

realize that this was not possible in the past. In particular, fiber-reinforced plastic components can be manufactured which are based on integral, i. one-piece fashion, containing a movie hinge. The improved

The strength of the fiber-reinforced plastic is combined here with the flexibility of a film hinge. In addition, the finished Kunstoffoffbauteil further advantages that arise due to the foaming. This includes, in particular, the lower weight and the lower material consumption, at substantially the same level Load capacity. These properties play a major role, in particular in vehicle construction, in which lightweight construction is becoming increasingly important, especially in the field of electromobility. The production of a one-piece component from a

Film-reinforced fiber-reinforced plastic reduces manufacturing time and effort, improves durability and reduces wear

Maintenance vulnerability compared with multipart

fiber reinforced plastic components.

Preferably, the plastic is reinforced with glass fibers, since this is extremely robust to mechanical stress. The basis is thermoset and

Thermoplastic plastics, in particular polyamide, in

Consideration. Foaming gives the material sufficient flexibility in the area of the film hinge.

In one embodiment, the foaming agent comprises a gas which is melted under pressure into the melted or in

Plastic melting in the

Injection mold is introduced. Nitrogen and / or carbon dioxide are particularly suitable as foaming gases. The

Injection molding tool may have a special mixing zone, in which the gas is injected, or the gas can be approximately in the worm gear for melting and

Transporting the plastic provided snail

be introduced. The use of a gas as

Foaming agent leaves the in the injection mold

plastic to be introduced, so that a conventional method based thereon can be modified with relatively simple means.

The gas fraction is preferably in the range of 0.2% to 0.4%. The gas fraction preferred here was considered to be a suitable compromise from the retention of the original

Component feature and the addition of the necessary

Flexibility found in the hinge area. In one embodiment, the foaming agent includes

Propellant, which is added to the plastic before Aufschmelzung. With this chemical foaming that can

Foaming the plastic even with a conventional injection mold, which does not provide a gas insertion under pressure, accomplish.

Preferably, the plastic is injected into the component mold via one or more injection points, the injection points not being located directly on the region of the component form intended to form the film hinge. In general, the dimensioning and positioning of the injection point (s) should be adapted to the component volume. This can be done, for example, under

Considering short flow paths and a constant

Melt flow can be determined during the filling process. It has been found that a constant and error-free filling of the hinge geometry best

is realized when the or the injection points are not directly on the hinge. Furthermore, it has been found that the quality of the component to be produced, including the hinge is then particularly well ensured when the diameter of the sprue bar or the sprue bars of

Injection mold not larger than twice the

maximum wall thickness of the component is.

Preferably, the plastic is a polyamide suitable for

foamed KunstStoffbauteile in vehicle construction is very suitable. It combines in an excellent way the requirements for strength and stability of the component, as well as the

Flexibility in the field of film hinge. For the same reason, the fiber content may be between 10% and 40%, preferably at substantially 30%.

In order to generate optimum component quality in all areas, it is advantageous to keep the filling process as good as possible short. For this reason, high or very high Anspritzgeschwindigkeiten are preferred. Preferably, the fill time is in the range of 0.5 to 1 second, more preferably less than 0.8 second. The specific one

Spray pressure can then rise to about 1400 bar, which is a result of the high Anspritzgeschwindigkeit. For optimum hinge results, the tool temperature should preferably not fall below 40 ° C in the affected area. For the further course of the process, it may be advantageous if there is no emphasis phase. The final geometry in this case is defined by the internal melt pressure.

Although the invention for the production of components in the field of automotive engineering, in particular in the field of

Interior of automobiles, is particularly suitable, it is understood that the invention also in others

Areas can be implemented, for example in the

Transport sector in general, in particular aviation and shipping, in furniture, home automation, etc ..

However, the present invention is particularly suitable for the production of components for vehicles, since it is very much on an attractive appearance over a long service life at high

Manufacturing productivity arrives. Lightweight construction is also becoming increasingly important in this area. In addition, other advantages and features of the invention will become apparent from the following description of the preferred embodiments. The features described there and above can be implemented alone or in combination, insofar as the

Features do not contradict. The following description of the preferred embodiments will be made with reference to the accompanying drawings.

In a further aspect, the invention comprises a

Component with a film hinge made of a fiber-reinforced, foamed plastic. As a plastic, a polyamide can be selected, which is reinforced with glass fibers. The Material thickness of the film hinge is for example in the range between 0.5 and 0.8 mm and is preferably about 0.65 mm. Moreover, according to yet another aspect, the invention comprises a living hinge of one

fiber reinforced, foamed plastic.

Brief description of the drawings

Figures la to lc show the cross section of a

Injection mold with component shape in different

Procedural stages.

Figure 2a is a three-dimensional view of one

exemplary component; FIG. 2b shows the area of a film hinge enlarged in cross section.

Figures 3a and 3b are interior views of a two-part component form.

Description of embodiments

Figures la to lc show an injection mold 1 and a component mold 20 for producing a component 30 with a film hinge of a foamed, fiber-reinforced

Plastic in different process stages.

The injection mold 1 has a funnel 2 and a cylinder 3 around which a heating tape 4 is laid and in which a worm 5 is rotatably provided.

Generally plastic material granules are introduced via the hopper 2 in the cylinder 3 during plasticizing. The granules are melted by rotating the screw 5 and supplying heat from outside through the heating bands 4 and by shearing heat to a thermoplastic composition and through

Helical flights 5 ', which are formed by thread-like screw walls 5'', transported in a screw antechamber 6. The molten thermoplastic molding material becomes due to a forward movement of the screw 5 in a

Cavity 21 of the component mold 20 injected. At the end of the injection process, if necessary, a holding pressure phase with subsequent cooling phase becomes active, which determines the dimensional accuracy, shrinkage and the distortion of the component 30. At the end of the cooling phase, the component mold 20 is opened and the finished component 30 is ejected.

Preferably, the granules, which is supplied via the hopper 2, already with fibers, preferably glass fibers, added. Alternatively, reinforcing fibers may be introduced into the cylinder 3 via a separate access, not shown in the figures.

In contrast to an injection molding process without gas loading, gas, preferably nitrogen, is now introduced into the melt via an injector, which is indicated by an arrow 7 in FIG. 1a. Alternatively or additionally, in the granules that is supplied via the hopper 2, a blowing agent may be included. The gas and / or propellant now leads to a foaming of the plastic directly in the cylinder 3, either already in the screw flights 5 ', but at the latest in the screw antechamber 6, takes place.

After foaming the plastic melt, which is indicated by small bubbles in the antechamber 6, the

Melt is injected by a forward movement of the screw 5 in the cavity 21 of the component mold 20, as shown in the figure lb. At the end of the injection process, the cooling phase immediately becomes active. The holding pressure phase takes over according to a preferred embodiment, the gas pressure in the melt, which compensates for the shrinkage and the delay. At the end of the cooling phase, the component mold 20 is opened and the finished component 30 is ejected; see. this figure lc. The component form is provided in two parts, it has a lower component mold half 22 and an upper component mold half 23. A concrete example of a component form shown only schematically in FIGS. 1 a to 1 c is shown in FIGS

Figures 3a and 3b shown. The associated component is

shown in three dimensions in Figure 2a.

The plastics material component shown in FIG. 2 a has a first component half 32 and a second component half 33, which are connected via a film hinge 31. The

Film hinge 31 is in cross section in the figure 2b

shown enlarged. The thickness of the film hinge 31 is here for example about 0.65 mm, whereby this has sufficient flexibility and at the same time is not so brittle despite fiber reinforcement that it breaks when actuated. At the same time, the component halves 32 and 33 are sufficiently rigid.

The two component mold halves 22 and 23 are relative

provided to each other movably, so that the component 30 can be ejected after completion and the component mold 20 is closed fluid-tight when filling the cavity 21, so that the plastic melt can be injected under high pressure.

Flexural rigidity on the finished component makes it possible for the first time, a variety of hinge geometries

Fiber-reinforced KunstStockmaterialien, with which this was not previously possible to realize. By foaming the KunstStoffmaterials can be a reduction of

Achieve component weight. The integration of hinge and rigid component units despite fiber reinforcement leads to a reduction of the number of parts

Reduction of production time. For the production of foamed, fiber reinforced

It is preferable that the injection molding of the component is realized either by means of a rod casting system or a needle valve hot runner system. Reason for this measure is that the gas pressure or the

Melt pressure in the sprue system should not expand early or should not outgas during the production process. The dimensioning of the injection point and the sprue system should be adapted to the component volume. This also applies to the number of injection points. The diameter of the sprue bar is preferably in any area more than twice the wall thickness, as it may otherwise lead to inflation of the sprue bar, which in turn

Endformproblemen can lead. A key aspect in optimizing injection is short flow paths and a constant melt flow during the filling process to allow consistent, consistent filling of the hinge geometry. This is the location of the injection points

preferably not directly on the hinge.

To select the material of the plastic can be different

Criteria with regard to the component geometry and the

Manufacturing process are taken into account. First feature for the production of film hinge components

glass fiber reinforced plastics is the foamability of the base material. In this case, PA 6 GF 15 and PA 6 GF 30 have proved to be suitable by way of example. In the case of

physical foaming, the gas content depends on

Material type, the filler content, the desired

Weight reduction, etc. Here, gas loadings of 0.2 to 0.4% have been found to be suitable. To be optimal

To ensure component quality in all areas, the filling process should be kept as short as possible. This requirement requires a high to very high injection speed. The filling time is preferably not more than 0.8 s and the screw speed is preferably about 110 mm / s. The specific spray pressure then rises to about 1400 in cash. For optimum film hinge results, the tool temperature in the affected area should not be below 40 ° C. The cooling time is crucial for the subsequent component quality and should be adapted to the geometry to be generated and tuned. It is important that there is no wave formation and no outgassing or puffing. For most components with film hinge geometries, this phase is not defined by the film hinge but by the rest of the component. In some cases, the full functionality of the film hinge geometry unfolds

Glass fiber reinforcement only after sufficient storage of the component; this is especially true

Materials that develop their final mechanical properties only after conditioning.

Claims

1. A process for producing a fiber-reinforced

Artificial material (30) with film hinge (31), the method comprising the steps of:

Melting a fiberized plastic in an injection mold (1);

Foaming the plastic by means of a

Foaming agent;

Injecting the foamed plastic material into a component mold (20) having a section for forming a film hinge (31);

Solidifying and removing the KunstStoffbauteils (30) from the component mold (20).

2. The method according to claim 1, characterized in that the fiber-reinforced plastic is a glass fiber reinforced

Plastic is.

3. The method according to claim 1 or 2, characterized

characterized in that the foaming agent comprises a gas which is pressurized into the molten or melted plastic in the injection mold (1).

is introduced.

4. The method according to claim 3, characterized in that the gas content is in the range of 0.2% to 0.4%.

5. The method according to any one of the preceding claims, characterized in that the foaming agent a

Having blowing agent, with which the plastic before

Melting is offset.

6. The method according to any one of the preceding claims, characterized in that the plastic is injected via one or more injection points in the component mold (20), wherein the injection points are not directly to the for Formation of the film hinge (31) provided area of the component form (20) are located.

7. The method according to any one of the preceding claims, characterized in that the diameter of the sprue bar of the injection mold (1) is not greater than twice the maximum wall thickness of the KunstStoffbauteils (30).

8. The method according to any one of the preceding claims, characterized in that the plastic is a polyamide.

9. The method according to any one of the preceding claims, characterized in that the fiber content between 10% and 40%, preferably substantially 30%.

10. The method according to any one of the preceding claims, characterized in that the filling time of the component mold (20) is in the range of 0.5 to 1 second, preferably less than 0.8 seconds.

11. The method according to any one of the preceding claims, characterized in that the material thickness of

Film hinge (31) is in the range between 0.5 and 0.8 mm, preferably about 0.65 mm.

12. component (30) with a film hinge (31) made of a fiber-reinforced, foamed plastic.

13. Component (30) according to claim 12, characterized in that the plastic is a polyamide and reinforced with glass fibers.

14. component (30) according to claim 12 or 13, characterized

characterized in that the material thickness of the film hinge (31) is in the range between 0.5 and 0.8 mm, preferably about 0.65 mm.

15. Film hinge (31) made of a fiber-reinforced, foamed plastic.