DE102018103778B4 - Thermoforming process as well as mold and plastic film for carrying out this thermoforming process - Google Patents

Abstract

Thermoforming process for producing a plastic molded part (1) from a plastic film (2) or plastic plate in a mold (3) which has at least a first mold part (4) and at least a second mold part (5) (4, 5) on circumferential clamping edges (6; 7), between which the plastic film (2) or plastic plate to be deformed can be tightly clamped, can be placed against one another, and of which the first mold part (4) is a positive mold (10). trained formation carries, wherein at least one pressure inlet opening (8) are provided in the partial area of the second molding tool part (5) surrounded by the clamping edge (7), characterized in that the plastic film (2) or plastic plate is used, which in its during Forming process the partial area acting on the positive mold (10) has at least one passage opening (9) and that the diameter of the at least one passage opening (9) and / or the w During the forming process, the gas pressure introduced via the at least one pressure inlet opening (8) and / or the distance between the plastic film (2) or plastic plate and the positive mold (10) at the beginning of the forming process and / or the distance between the at least one passage opening (9) at least a pressure inlet opening (8) in the second mold part (5) is / are selected such that the plastic film (2) or plastic plate, when gas pressure is introduced via the at least one pressure inlet opening (8), at least in its at least one through opening ( 9) has the subarea sealingly against the positive mold (10).

Description

The invention relates to a thermoforming process for producing a plastic molded part from a plastic film or plastic plate in a mold, which has at least a first mold part and at least a second mold part, the circumferential clamping edges, between which the plastic film or Plastic plate can be tightly clamped, can be placed against one another, and of which the first mold part carries a shape designed as a positive mold, at least one pressure inlet opening being provided in the partial area of the second mold part surrounded by the clamping edge.
The invention also relates to a molding tool and a plastic film or plate for carrying out the method mentioned at the outset.

For environment detection, a radar device with a radar antenna is increasingly being used in motor vehicles, which is protected on the motor vehicle in a radar dome or the like molded plastic part. Thin heating wires are drawn into these radar domes to protect the transparent radar dome against icing or snow. These heating wires look similar to those that are provided, for example, in the rear window of a motor vehicle. However, the heating wires integrated in the comparatively small radar dome are much finer and the wire used is often thinner than a hair and accordingly sensitive. This heating wire runs out of two contact points in the radar dome, which are then used for contacting. In the area of the heating wire points serving for contacting, a hole must be provided in the plastic molded part serving as the radar dome in order to contact the contact points of the heating wire there. Such lens-shaped, convex or otherwise spherically shaped plastic molded parts are usually molded using the high-pressure process. For this purpose, a foil blank already provided with heating wire is placed in a mold, the foil blank being kept tight at its peripheral edge. The mold has in one mold half a shape corresponding to the desired contour of the plastic molded part and designed as a positive mold, while in the other mold half there is usually a central air opening for supplying the high pressure. While the lower mold half, which has the positive mold, is heated to approximately 120 °, the plastic film to be molded regularly has a temperature of approximately 150 ° before these two parts are pressed against one another. Since the gas pressure subsequently required for high-pressure molding can escape into the lower mold half via the through-holes to be provided in the plastic film, the through-holes required in the plastic molded part are usually only incorporated after the shaping process. However, there is a risk that the sensitive heating wires will be damaged, particularly at their contact points, and that the plastic molded part will subsequently become unusable.

From the US 2013/0 134 625 A1 A deep-drawing process is previously known, which is determined using a polypropylene label film for producing a container, for example a margarine pan. The aim is good adhesion of the label to the container and a bubble-free deformation of the film used without air pockets. According to the main claim 14 in US 2013/0 134 625 A1 the film provided as a label is preformed using a top stamp of a deep-drawing mold by means of a partial vacuum. Before the actual deep drawing, the label film is placed in the shaped body and the deep drawn film is placed over it in such a way that the shaped body is sealed airtight. A partial vacuum or vacuum is then suitably applied to the shaped body. Due to the pressure difference, suction is exerted on the thermoforming film. A heating element is attached over the film surface, which heats the film until it deforms in the direction of the shaped body. The temperature and negative pressure are selected so that the film presses positively against the molded body with the inserted label and connects to the label. After eliminating the pressure difference and cooling, the labeled deep-drawn container can be removed. The individual process steps of the previously known deep-drawing process are shown in 4th of the US 2013/0 134 625 A1 presented in different versions.

The end US 2013/0 134 625 A1 Previously known methods presuppose the deep-drawing of the plastic film with the aid of a vacuum and, on the other hand, there is no provision for the plastic film to be deformed by means of high pressure.

From the DE 10 2011 103 824 A1 Another method for producing in-mold decorated plastic molded parts is described above. For this purpose, the known production device comprises a die-cutting and injection molding device and a decorative film punching device which has an adjusting device which is designed such that the decorative film is arranged in a precise manner in the die-cutting and injection molding device. Even with that DE 10 2011 103 824 A1 The thermoforming process of the known thermoforming process is achieved by means of vacuum.

From the DE 10 2011 117 985 A1 a method for producing a plastic part is already known. This plastic part comprises an injection molded layer and a film element with at least a dielectric layer and at least one electrically conductive layer. The electrically conductive layer forms at least one electrical functional structure in a functional area, which can be contacted in a contacting area. The injection molded layer is applied to the film element at least in some areas in the functional area, but not in the contact area. After the film element has been provided, at least one reinforcing element is applied in such a way that the at least one reinforcing element covers the contact area at least in regions. The film element is then introduced into an injection molding tool and back-injected with an injection molding material such that the injection molding layer is applied to the film element at least in some areas in the functional area, but not in the contacting area. In this previously known method, too, the forming process is not carried out by means of high pressure of the film element.

It is therefore an object of the invention to provide a thermoforming process of the type mentioned at the outset, as well as a molding tool and a plastic film or sheet for carrying out such a thermoforming process, which allow the production and completion of such a plastic molded part having such through-holes.

The solution to this problem according to the invention in the case of the thermoforming method of the type mentioned at the outset is, in particular, that a plastic film or plastic plate is used which has at least one passage opening in its partial region acting on the positive mold during the forming process, and that the diameter of the at least one passage opening and / or the gas pressure introduced via the at least one pressure inlet opening during the forming process and / or the distance between the plastic film or plastic plate and the positive mold at the beginning of the forming process and / or the distance between the at least one passage opening and the at least one pressure inlet opening in the second mold part is / are that the plastic film or plastic plate, when gas pressure is introduced via the at least one pressure inlet opening, seals against the positive at least in its partial area having the at least one passage opening shape.

The thermoforming process according to the invention provides for the production of a plastic molded part from a plastic film or plastic plate, the finished plastic molded part having to have at least one passage opening. To produce the plastic molded part, a plastic film or plastic plate is placed in a mold that has at least one first mold part and at least one second mold part. Each of these mold parts has a circumferential clamping edge, the mold parts being able to be placed so close to one another at their clamping edges that the plastic film or plastic plate to be deformed can be clamped between them. The second mold part has at least one pressure inlet opening. In order to provide the finished plastic molded part with at least one corresponding passage opening, it is provided according to the invention that a plastic film or plastic plate is used for the thermoforming process, which has at least one such passage opening in its partial area acting on the positive mold during the forming process. In order to avoid that the high pressure required to apply the hot plastic film or plastic plate to the positive mold can escape through the at least one through opening into the first mold part, the diameter of the at least one through opening and / or during the forming process is over the at least one Pressure inlet opening introduced gas pressure and / or the distance of the plastic film or plastic plate to the positive mold at the beginning of the forming process and / or and / or the distance of the at least one passage opening to the at least one pressure inlet opening in the second mold part selected such that the plastic film or plastic plate when gas pressure is introduced via the at least one pressure inlet opening of the second mold part, at least in its partial region having the at least one through opening, it bears sealingly against the positive mold. Since the plastic film or plastic plate can thus contact the positive mold with its at least one passage opening at the very beginning of the shaping process, the high pressure required for pressing the plastic film or plastic plate onto the positive mold is hardly reduced. Since a finished plastic molded part can already be removed from the molding tool after the shaping process has ended, which plastic molded part already has the passage openings required, for example, for contacting, subsequent incorporation of such passage openings into the plastic film or plastic plate can be dispensed with Forming process thus enables the production of such plastic molded parts in a simple manner.

So that the time interval within which the hot plastic film or plastic plate seals against the positive mold at the start of the forming process can be kept as short as possible, it is advantageous if the plastic film or plastic plate is a preformed semifinished product.

A preferred application example according to the invention provides that the positive form as spherical or spherical shape of the first mold part is formed. In such a molding tool, an approximately spherical plastic molded part can be formed in a simple manner, which can then also be used as a radar dome in a motor vehicle.

The forming process is made considerably easier if the plastic film or plastic plate consists of a thermoplastic. An exemplary embodiment is preferred in which the plastic film or plastic plate is made from a transparent thermoplastic.

A preferred application example according to the invention provides that at least one heating wire is placed on the plastic film or plastic plate or inserted into the plastic film or plastic plate. It is expedient if the contact points of the at least one heating wire penetrate the at least one passage opening in the plastic film or plastic plate.

For the plastic molded part produced in the thermoforming process according to the invention, an application is preferred in which the plastic molded part is designed as a radar dome or the like which can be attached to a motor vehicle and is designed to protect an antenna system from disruptive weather conditions.

For the molding tool or the plastic film or plate used in the above-mentioned thermoforming process, the solutions according to the invention of the above object are described in the applicable patent claims 8 and 9.

The invention is explained in more detail below on the basis of a preferred exemplary embodiment shown schematically here. Further developments according to the invention result from the claims in conjunction with the drawing and the description.

• 1 ein Formwerkzeug zur Durchführung eines Thermo-Umformverfahrens, welches zur Herstellung eines sphärisch geformten Kunststoff-Formteiles aus einer Kunststofffolie oder Kunststoffplatte verwendet wird, welches Kunststoff-Formteil mindestens eine als Durchbruch ausgebildete Durchtrittsöffnung aufweist, wobei das Formwerkzeug hier aus zwei Formwerkzeug-Teilen besteht, die derart aneinander anlegbar sind, dass zwischen ihnen die zu verformende Kunststofffolie oder Kunststoffplatte dichtend eingespannt werden kann, und
• 2 das Formwerkzeug aus 1 in einer auseinandergezogenen Darstellung seiner Formwerkzeug-Teile, wobei zwischen den Formwerkzeug-Teilen sich bereits ein in seiner Formgebung fertiggestelltes Kunststoff-Formteil befindet.

It shows:

• 1 a mold for performing a thermoforming process, which is used to produce a spherically shaped plastic molded part from a plastic film or plastic plate, which plastic molded part has at least one passage opening designed as an opening, the mold here consisting of two mold parts can be placed against one another in such a way that the plastic film or plastic plate to be deformed can be clamped tightly between them, and
• 2nd the mold 1 in an exploded view of its mold parts, wherein there is already a finished plastic molded part between the mold parts.

In the 1 and 2nd is a thermoforming process shown in two steps, that for the production of a plastic molded part 1 from a plastic film 2nd or plastic plate. The thermoforming process sees the use of a molding tool 3rd before that at least a first mold part 4th and at least a second mold part 5 having. How from 1 what is clear are these mold parts 4th , 5 on circumferential clamping edges 6 ; 7 can be placed against each other in such a way that between the mold parts 4th , 5 the plastic film to be deformed 2nd or plastic plate can be tightly clamped. The first mold part has a positive shape 10th trained formation, which the desired shape of the plastic molded part 1 after the forming process. In that of the clamping edge 6 surrounding portion of the first mold part 4th is at least one vent 11 intended. In that of the clamping edge 7 surrounding portion of the second mold part 5 is at least one pressure inlet opening 8th intended.

This means that the molded plastic part produced using the thermoforming process 1 a passage opening 9 has, for example, for contacting the plastic molding 1 embedded heating wires can be used, a plastic film is already used for the thermoforming process 2nd or plastic plate used in their during the forming process, the positive form 10th acting area the at least one passage opening 9 Has. The diameter of the at least one passage opening 9 and / or during the forming process via the at least one pressure inlet opening 8th introduced gas pressure and / or the distance of the plastic film 2nd to positive form 10th at the beginning of the forming process and / or the distance between the at least one passage opening 9 to at least one pressure inlet opening 8th in the second mold part 5 chosen so that the plastic film 2nd when gas pressure is introduced via the at least one pressure inlet opening 8th at least in it the at least one passage opening 9 having partial area sealing to the positive form 10th creates.

How from 1 becomes clear, the plastic film 2nd or plastic plate can also be a semi-finished product adapted to the desired final shape. In the embodiment shown here is the positive form 10th as a spherical or spherical shape of the first mold part 4th educated. The plastic film 2nd or plastic plate is made from a thermoplastic and in particular from a transparent thermoplastic. In the plastic film to be deformed 2nd or plastic plate, at least one heating wire can be integrated over the at least one passage opening 9 can be contacted through. The contact ends of the at least one heating wire can have the at least one passage opening 9 in the plastic film 2nd or push through plastic plate.

The molded plastic part produced in the process shown here 1 is designed as a radar dome or the like, which can be attached to a motor vehicle, to protect an antenna system from disturbing weather conditions.

• Die noch flache Kunststofffolie 2 oder Kunststoffplatte wird zunächst gelocht und mit den als Kontaktierungslöcher vorgesehenen Durchtrittsöffnungen 9 versehen. Sodann wird die Kunststofffolie 2 mit den entsprechenden Heizdrähten versehen. Anschließend erfolgt eine Vorformung der Kunststofffolie 2 oder Kunststoffplatte entsprechend der angestrebten sphärischen Form des fertiggestellten Kunststoff-Formteiles 1. Sodann wird die als Halbzeug vorgeformte erhitzte Kunststofffolie 2 auf das erste und hier untere Formwerkzeug-Teil 4 aufgelegt und das Formwerkzeug 3 geschlossen. Dabei legen sich die Formwerkzeug-Teile 4, 5 an ihren Einspannrändern 6, 7 derart aneinander an, dass dazwischen die zu verformende Kunststofffolie 2 dicht eingespannt wird. Durch eine Druckbeaufschlagung der im Formwerkzeug 3 eingespannten Kunststofffolie 2 durch die wenigstens eine Druckeinlassöffnung 8 wird die Kunststofffolie 2 gegen die Positivform 10 im ersten unteren Formwerkzeug-Teil 4 gepresst, derart, dass die in der als Halbzeug ausgebildeten Kunststofffolie 2 vorgesehenen Durchtrittsöffnungen 9 bereits zu Beginn des Umformvorganges dichtend an der Positivform 10 anliegen und verschlossen sind. Sobald die Kunststofffolie 2 in die entsprechende Form gebracht wurde, kann das die Durchtrittsöffnungen 9 aufweisende Kunststoff-Formteil 1 aus dem Formwerkzeug 3 entnommen werden.

The process shown here schematically essentially provides for the following process steps:

• The still flat plastic film 2nd or plastic plate is first punched and with the through holes provided as contact holes 9 Mistake. Then the plastic film 2nd provided with the appropriate heating wires. The plastic film is then preformed 2nd or plastic plate according to the desired spherical shape of the finished plastic molding 1 . Then the heated plastic film preformed as a semi-finished product 2nd on the first and lower mold part 4th put on and the molding tool 3rd closed. The mold parts lay down 4th , 5 at their clamping edges 6 , 7 so that the plastic film to be deformed is in between 2nd is tightly clamped. By pressurizing the in the mold 3rd clamped plastic film 2nd through the at least one pressure inlet opening 8th becomes the plastic film 2nd against the positive form 10th in the first lower mold part 4th pressed in such a way that the plastic film formed as a semi-finished product 2nd provided through openings 9 sealing the positive mold at the beginning of the forming process 10th close and are closed. Once the plastic film 2nd has been brought into the appropriate shape, the passage openings 9 plastic molding 1 from the mold 3rd be removed.

Because the plastic film used as a semi-finished product 2nd in the area of the through holes 9 already the final shape of the plastic molded part 1 has an approximate shape, has the plastic film 2nd only a comparatively short distance from the first mold part 4th . In comparison to the air volume required for high-pressure forming, it is in the plastic film 2nd provided through holes 9 comparatively small. In contrast, there is the distance between the preferably centrally arranged pressure inlet opening 8th and the passage openings 9 comparatively large, so that there is a good seal between the pressure inlet opening 8th and the passage openings 9 results during the forming process.

Reference list

1

Plastic molding

2nd

Plastic film

3rd

Molding tool

4th

first mold part

5

second mold part

6

Clamping edge of the first mold part 4th

7

Clamping edge of the second mold part 5

8th

Pressure inlet opening

9

Passage opening

10th

Positive form

11

Vent

Claims (9)

Thermoforming process for producing a plastic molded part (1) from a plastic film (2) or plastic plate in a mold (3) which has at least a first mold part (4) and at least a second mold part (5) (4, 5) can be placed against one another on circumferential clamping edges (6; 7), between which the plastic film (2) or plastic plate to be deformed can be tightly clamped, and of which the first mold part (4) is a positive mold (10). trained formation carries, wherein at least one pressure inlet opening (8) are provided in the portion of the second mold part (5) surrounded by the clamping edge (7), characterized in that the plastic film (2) or plastic plate is used, which in its during Forming process the partial area acting on the positive mold (10) has at least one passage opening (9) and that the diameter of the at least one passage opening (9) and / or the w During the forming process, gas pressure introduced via the at least one pressure inlet opening (8) and / or the distance between the plastic film (2) or plastic plate and the positive mold (10) at the start of the forming process and / or the distance between the at least one through opening (9) at least a pressure inlet opening (8) in the second mold part (5) is / are selected such that the plastic film (2) or plastic plate when Gas pressure is sealingly applied to the positive mold (10) via the at least one pressure inlet opening (8) at least in its partial area having the at least one through opening (9). Thermoforming process according to Claim 1 , characterized in that the plastic film (2) or plastic plate is a preformed semi-finished product. Thermoforming process according to Claim 1 or 2nd , characterized in that the positive shape (10) is designed as a spherical or spherical shape of the first mold part (4). Thermoforming process according to one of the Claims 1 to 3rd , characterized in that the plastic film (2) or plastic plate consists of a thermoplastic, in particular a transparent thermoplastic. Thermoforming process according to one of the Claims 1 to 4th , characterized in that at least one heating wire is placed on the plastic film (2) or plastic plate or inserted into the plastic film (2) or plastic plate. Thermoforming process according to one of the Claims 1 to 5 , characterized in that the contact ends of the at least one heating wire penetrate the at least one passage opening (9) in the plastic film (2) or plastic plate. Thermoforming process according to one of the Claims 1 to 6 , characterized in that the plastic molded part (1) is designed as a spherical shell that can be attached to a motor vehicle or the like to protect an antenna system from disruptive weather conditions. Molding tool for carrying out a thermoforming process according to one of the Claims 1 to 7 . Plastic film or plastic plate to carry out the thermoforming process according to one of the Claims 1 to 7 in a mold according to Claim 8 .

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