DE102020112790A1 - Manufacture of a radome for a motor vehicle - Google Patents

Abstract

The invention is based on an indirect injection of a blank 3 comprising a plastic film with a first spray material 6, in which the first spray material 6 is fed through a spray medium feed 8 and then first hits an impact element 7, which deflects the first spray material 6 towards the blank 3 causes. The spray agent feed 8 is preferably oriented in such a way that it lies above the blank 3 in the direction of gravity 9. The method according to the invention reduces the scrap that arises from an at least partial deformation and / or displacement of the blank 3.

Description

The present invention relates to a method for producing a cover for a radar device, a radome, for a motor vehicle.

Radar devices are increasingly used in motor vehicles, particularly in the course of automating motor vehicles, in order to measure distances to objects and / or other road users and / or a relative speed of the motor vehicle relative to an object or other road users. The data correspondingly collected by the radar device are then used to signal possible dangers to the driver of the motor vehicle or directly to control at least individual functions of the motor vehicle. Since the motor vehicle is used in a wide variety of environments, it is essential to protect the radar device from environmental influences such as moisture, corrosive chemicals and the like. For this purpose, covers are known which close an opening in the surface of the motor vehicle in which at least one antenna of the radar device is formed. These covers are usually constructed from a material comprising a plastic which is at least partially transparent to electromagnetic waves with wavelengths in the radar range.

For example, from the DE 10 2006 046 436 B3 known to use an at least partially metallized film as a base for a radome, which is injected in front and behind with a plastic. However, it has been found that the film can deform, particularly when the base is first molded, which makes the created radome unusable.

Proceeding from this, the invention is based on the object of overcoming the disadvantages known from the prior art and, in particular, of specifying a method for producing a cover for a radar device which reduces the rejects produced.

This object is achieved with the features of the independent claim. Advantageous further developments are the subject of the dependent claims.

1. a) Einlegen eines Rohlings umfassend eine Kunststofffolie in eine Spritzform, so dass der Rohling an einem Kern der Spritzform anliegt;
2. b) Schließen der Spritzform, so dass ein erster Hohlraum zur Vorspritzung des am Kern anliegenden Rohlings entsteht, so dass der erste Hohlraum an einer dem Kern gegenüberliegenden ersten Seite des Rohlings ausgebildet ist;
3. c) Einbringen von erstem Spritzmaterial in den Hohlraum zur Bildung eines vorgespritzten Rohlings, wobei das erste Spritzmaterial einseitig von einer Spritzmaterialzuführung in den ersten Hohlraum eingebracht wird und der erste Hohlraum so gestaltet ist, dass das erste Spritzmaterial auf ein Prallelement stößt, bevor es in Richtung auf den Rohling umgeleitet wird und dort eine erste Kunststoffschicht bildet.

The method according to the invention for producing a cover for a radar device in a motor vehicle comprises the following steps:

1. a) inserting a blank comprising a plastic film into an injection mold, so that the blank lies against a core of the injection mold;
2. b) closing the injection mold, so that a first cavity is formed for the pre-injection of the blank resting against the core, so that the first cavity is formed on a first side of the blank opposite the core;
3. c) Introducing the first spray material into the cavity to form a pre-sprayed blank, the first spray material being introduced into the first cavity on one side by a spray material supply and the first cavity being designed so that the first spray material hits an impact element before it moves in the direction is diverted onto the blank and forms a first plastic layer there.

The cover is particularly suitable and intended for closing an opening in a surface of the motor vehicle, so that in the installed state at least one antenna of a radar device is formed in the opening, covered by the cover. The cover protects the radar device and in particular at least one antenna of the radar device from environmental influences to which the motor vehicle is exposed, for example in the form of moisture, snow, corrosive chemicals, etc.

The first spray material preferably comprises a plastic, in particular a polycarbonate (PC) and / or an acrylonitrile-butadiene-styrene copolymer (ABS). The plastic film is in particular a multilayer plastic film. In step a), the plastic film is placed in the injection mold against a core of the injection mold and, in the process, deformed if necessary. Then in step b) the injection mold is closed, which forms a first cavity on a side of the blank which is opposite the core of the injection mold. Here, too, the plastic film may be deformed. Alternatively or additionally, the plastic film can already be deformed before step a) so that a certain geometry is achieved. For example, the cover can be shaped so that it can be used in a radiator grille of a motor vehicle, for example in the form of a brand emblem of the manufacturer of the motor vehicle.

The blank or the pre-sprayed blank can, for example, be lacquered on one or both sides in one or more layers, for example with a layer of colored lacquer and / or a layer of protective lacquer. Surfaces with a metallic appearance can be applied to the blank at least in partial areas, optionally before step a) or already contained in the plastic film. The metallic appearance can be created by applying shiny metallic discrete points on or in at least partial areas of the plastic film and / or by using surface effects in multilayer plastic films. A flat application of a metallic layer is not provided, as this would result in excessive attenuation of the electrical radiation, which the radar device emits and receives, is achieved, which limits the functionality of the radar device.

In step c), the first plastic layer is injection molded in front of the blank. For this purpose, the first spray material is plasticized and then introduced into the first cavity. According to the invention, the first spray material is introduced into the first cavity on one side by a spray material feed, which is preferably above the blank in the direction of gravity, and the first cavity is designed so that the first spray material first hits an impact element before it moves in the direction of the Blank is diverted and forms a first plastic layer there. The first spray material is not applied directly to the blank. This reduces the likelihood that the blank will at least partially detach from the core of the injection mold. In particular, the rejects produced with the method according to the invention are significantly lower, since a partial rearrangement of the blank or the plastic film, which leads to creasing of the plastic film, making the pre-injected blank unusable, is at least reduced by step c). At the same time, a diversion of the first spray material before it is rerouted in the direction of the blank enables a method to be carried out in which the edge of the blank is also enclosed by the first spray material and thus protected from environmental influences. In addition, the diversion of the first spray material improves the optical quality of the cover, since without this diversion the structure of the cover is less homogeneous, since the area where the first spray material is sprayed on can be clearly seen in the case of blanks that are directly molded on in the cover. This is avoided by carrying out the process according to the invention.

The plastic film is preferably designed in multiple layers. This allows the construction of blanks whose properties, in particular optical properties, can be adapted. At the same time it has been found that multilayer plastic films in particular tend to crease, so that the method proposed here facilitates the construction of covers for radar devices based on multilayer plastic films.

Preferably, after step c), a second spray material is applied to form a second plastic layer on the second side of the pre-sprayed blank opposite the first plastic layer. Thus, in step c) the blank is pre-injected and after step c) the blank is back-injected, which enable the blank to be protected on both sides. At the same time, a combined pre- and back-injection allows a variable design of the cover, which can be adapted to different areas of application (with regard to the protection of the blank, the design of the radar device, the design of the motor vehicle) and also to different optical requirements.

Preferably, the core of the injection mold is displaced before the introduction of the second injection molding material, so that a second cavity for receiving the second injection molding material is created.

1. a) Polycarbonat; und
2. b) Acrylnitril-Butadien-Styrol-Copolymer.

The first spray material and the second spray material each comprise at least one plastic. At least one of the spray materials: the first spray material and the second spray material is preferably selected from at least one of the following materials:

1. a) polycarbonate; and
2. b) Acrylonitrile-butadiene-styrene copolymer.

It is thus possible to form one of the injection molding materials from PC and the other from ABS, or to use a mixture of PC and ABS for both the first and the second plastic layer. The mixing ratios between PC and ABS can be selected depending on the application, for example a mixture of 80% by weight PC and 20% by weight ABS is possible.

At least one of the spray materials is preferably mixed with a dye, the first spray material and the second spray material, so that the visual appearance of the cover can be influenced.

After the first plastic layer and / or the second plastic layer have been applied, post-processing of the pre-injected blank or the pre-injected and back-injected blank may be necessary, for example deburring or post-processing of the edges in order to be able to produce cover within certain tolerances, for example. The first and / or second spray material are preferably thermoplastic.

The first spray material is preferably introduced into the first cavity on one side from the spray material feed, which lies above the blank in the direction of gravity. The injection molding of the blank preferably takes place from above in the direction of gravity. It has been found that this further reduces the probability that the blank will at least partially detach itself from the core of the injection mold.

As a precaution, it should be noted that the numerals used here ("first", "second", ...) primarily (only) serve to distinguish between several similar objects, sizes or processes, thus in particular no dependency and / or sequence of these objects, sizes or processes with respect to one another. Should a dependency and / or sequence be necessary, this is explicitly stated here or it is obvious to a person skilled in the art when studying the specifically described embodiment.

• 1 einen Ausschnitt eines Beispiels einer Spritzform mit eingelegtem Rohling vor dem Einbringen des ersten Spritzmaterials; und
• 2: einen Ausschnitt eines Beispiels einer Spritzform mit vorgespritztem Rohling vor Einbringen des zweiten Spritzmaterials.

The invention and the technical environment are explained in more detail below with reference to the figures. It should be pointed out that the invention is not intended to be restricted by the exemplary embodiments shown. In particular, unless explicitly stated otherwise, it is also possible to extract partial aspects of the facts explained in the figures and to combine them with other components and findings from the present description and / or figures. In particular, it should be pointed out that the figures and in particular the size relationships shown are only schematic. The same reference symbols denote the same objects, so that explanations from other figures can be used in addition, if necessary. Show it:

• 1 a section of an example of an injection mold with an inserted blank before the introduction of the first injection molding material; and
• 2 : a section of an example of an injection mold with a pre-injected blank before the second injection molding material is introduced.

1 shows a section of an example of an injection mold 1 for producing a cover for a radar device in a motor vehicle, also called a radome. The cover is produced by injection molding or multi-component injection molding with one or more injection molding materials comprising at least one plastic. The injection mold 1 includes a core 2 on which a blank 3 is applied. The blank 3 is formed from a plastic film, which is preferably multilayered. Between the blank 3 and a mold side 4th the injection mold 1 is a first cavity 5 formed, which in the context of injection molding to create a the first cavity 5 filling first plastic layer with a first spray material 6th is filled. The first spray material 6th is preferably a thermoplastic, in particular PC and / or ABS.

The first spray material 6th is not directly on the blank 3 directed, rather the first spray material hits 6th first on an impact element 7th , which is a diversion of the first spray material 6th caused by 90 ° and more before the first spray material 6th in the area of the first cavity 5 occurs in which the blank 3 at the core 2 is applied. So there is a displacement and / or deformation of the blank 3 through the first spray material 6th avoided. At the same time there is a spray material feed 8th through which the first spray material 6th into the first cavity 5 is directed in the direction of gravity 8th above the blank 3 formed so that the introduction of the first spray material 6th not against the action of gravity but with the action of gravity 9 he follows.

2 shows a section of the injection mold 1 after the core 2 was relocated to a second cavity 10 to create, which is used for back injection with a second injection molding material to form a second plastic layer as part of an injection molding process. The back-molding takes place after the pre-molding, so that a pre-molded blank 11th including the blank 3 and a first plastic layer 12th on a first page 13th of the blank 3 is present. The second cavity 10 lies on a second page 14th of the blank 3 who have favourited first page 13th of the blank 3 opposite. The second spray material can come from any direction, but preferably also through the spray agent supply 8th the end 1 are fed. The second spray material is a thermoplastic, in particular PC and / or ABS.

The invention is based on indirect injection molding of a blank 3 comprising a plastic film with a first spray material 6th where the first spray material 6th through a spray agent supply 8th is fed and then initially on a baffle element 7th meets, which deflects the first spray material 6th towards the blank 3 causes. The spray agent supply 8th is aligned so that it is in the direction of gravity 9 above the blank 3 lies. The method according to the invention reduces the scrap caused by an at least partial deformation and / or displacement of the blank 3 arises.

List of reference symbols

1

Injection mold

2

core

3

blank

4th

Mold side

5

first blank

6th

first spray material

7th

Impact element

8th

Spray material feed

9

Gravity

10

second cavity

11th

pre-injected blank

12th

first layer of plastic

13th

first page

14th

second page

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• DE 102006046436 B3 [0003]

Claims (7)

A method for producing a cover for a radar device in a motor vehicle, comprising the following steps: a) inserting a blank (3) comprising a plastic film into an injection mold (1) so that the blank (3) rests against a core (2) of the injection mold (1), b) Closing the injection mold (1), so that a first cavity (5) for the pre-injection of the blank (3) resting on the core (2) is created, so that the first cavity (5) is on a first side opposite the core (2) (13) of the blank (3) is formed; c) Introducing the first spray material (6) into the first cavity (5) to form a pre-sprayed blank (11), the first spray material (6) being introduced into the first cavity (5) on one side from a spray material feed (8) and the The first cavity (5) is designed so that the first spray material (6) hits an impact element (7) before it is diverted towards the blank (3) and forms a first plastic layer (12) there. Procedure according to Claim 1 , in which the plastic film is multilayered. Method according to one of the preceding claims, in which after step c) a second spray material is applied to form a second plastic layer on the second side (14) of the pre-sprayed blank (11) opposite the first plastic layer (12). Procedure according to Claim 3 , in which for this purpose the core (2) of the injection mold (1) is displaced before the introduction of the second injection molding material, so that a second cavity (10) for receiving the second injection molding material is created. Method according to one of the preceding claims, in which at least one of the spray materials: the first spray material (6) and the second spray material is selected from at least one of the following materials: a) polycarbonate; and b) Acrylonitrile-butadiene-styrene copolymer. Method according to one of the preceding claims, in which at least one of the spray materials: a dye is admixed with the first spray material (6) and the second spray material. Method according to one of the preceding claims, in which the first spray material (6) is introduced into the first cavity (5) on one side from the spray material feed (8) which is above the blank (3) in the direction of gravity (9).

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