DE102014017922A1 - Method for component connection of a plastic component with a joining partner - Google Patents

Abstract

The invention relates to a method for component connection of a plastic component (1) made of a thermoplastic material with a joining partner (3), in which the thermoplastic base material (15) is plasticized in a thermal joining process with heat input and the joining partner (3) to form a material. and / or positive connection in the plasticized base material (15) is pressed. According to the invention, in the shaping of the plastic component (1), electrically conductive joining fibers (11) are integrated into its thermoplastic base material (15). The heating of the plastic component base material (15) takes place in the joining process by applying electric current to the joining fibers (11).

Description

The invention relates to a method for component connection of a plastic component made of a thermoplastic material with a joining partner according to the preamble of claim 1.

In the production of such a composite component, a mechanical joining technique, that is to say blind riveting or screwing, is used in common practice, if appropriate in combination with gluing in order to increase the bonding strength.

In contrast, in a generic joining method, a thermal joining process is used in which the thermoplastic base material of the plastic component is plasticized with heat and then the joining partner is pressed to form a material and / or positive connection with a predetermined joining force in the plasticized base material. In the case of a metallic joining partner, the thermal joining process may be a heat conduction welding, in which the metallic joining partner is heated and is connected with the application of the joining force and melting of the plastic component with this. By special structuring of the metal surface of the joining partner, the connection strength can be additionally increased.

In the above prior art, the component production and the joining process usually takes place sequentially at locally separate locations. Particularly in the case of mechanical joining technologies (punching, drilling, screwing) there is a risk of elimination of the fiber-reinforced plastic as well as fiber damage, which can have a strength-reducing effect on the component connection. In addition, the use of additional adhesives is often required. In the above-mentioned thermal joining process external and often inefficient heat sources (laser, induction, infrared, ultrasound, circulating air) are required, resulting in losses in the form of heat radiation to the environment.

From the DE 10 2006 058 198 as well as from the WO 2011/050787 A2 It is known to apply electric current to the carbon fibers of a fiber-reinforced plastic component in use as surface heating. In addition, from the DE 10 2009 028 456 B3 a method for producing a fiber-reinforced plastic component known. In this method, a semifinished fiber on electrically conductive fibers, such as carbon fibers, on. These are subjected to heating with electric current to assist in impregnation of thermoplastic material. In this method, contacting takes place with subsequent resistance heating of the dry fibers. The fiber-reinforced plastic part produced in this way still has dry, non-impregnated fibers on the contact surfaces.

The object of the invention is to provide a method for component connection between a plastic component and a joining partner, in which a perfect component composite can be provided in process-technically simple manner and while saving energy.

The object is solved by the features of claim 1. Preferred embodiments of the invention are disclosed in the subclaims.

According to the characterizing part of claim 1 electrically conductive joining fibers are integrated into the thermoplastic base material of the plastic component in the shaping of the plastic component. The heat input into the plastic base material required for the thermal joining process takes place by applying electric current to the joining fibers. This is designed so that at least at the joining zone between the plastic component and the joining partner plasticizes the base material. Subsequently, the joining partner can be pressed with a predetermined joining force and to form a material and / or positive connection in the plasticized base material. After cooling, the component composite solidifies, without damaging the optionally integrated in the base material continuous and / or short fibers.

In the joining process according to the invention joining partners of different material combinations can be interconnected, such as plastic plastic, plastic-metal or plastic-ceramic. By means of the electrically conductive joining fibers, an efficient heat source is also provided in which the electrical energy is almost completely converted into heat. In addition, a targeted heat input can be made possible by appropriate pre-positioning of the joining fibers in the base material of the plastic component. The joining speed is increased in comparison to common joining processes, since the joining process can be carried out at the same time by means of homogeneous heat input at all connection points. In addition, a joining of difficult or impossible to reach places (one-sided accessibility is possible) feasible. In terms of process technology, additional operations, additional material (drilling, adhesive application) as well as additional system technology for the joining process can be dispensed with.

To prepare the thermal joining process, first the two joining partners are fixed to one another by applying clamping forces (that is to say a joining force). The electric Conductive joining fibers may be, for example, carbon fibers, metal wires / fibers or conductively coated fibers.

In the shaping of the plastic component, the electrical contact points of the joining fibers for the electrical power supply can preferably already be exposed by its base material. Electric current is applied at the contact points of the joining fibers and thus the thermal joining process is injected. The electrically conductive joining fibers heat up and the surrounding plastic base material until it plasticizes. Subsequently, the joining partner is pressed with a predetermined joining force on the plasticized base material, whereby the material and / or positive connection between the two joining partners is generated. This leads to the flow / backflow of the solid or cold joining partner surface. An increase in strength is possible by the separate structuring of the surfaces of the joining partner (creation of undercuts).

In a first variant, the electrically conductive joining fibers are positioned only in the region of the joint to which the joining partner is to be connected, while the adjoining base material remains free of joining fibers outside the joint. Optionally, a plurality of spaced apart joints may be provided on the plastic component through which the joining fibers extend in series or parallel connection.

This results in a targeted heating of at least one joining zone or a targeted partial contacting of certain joining fibers. This means that not the entire plastic component is heated, but only the relevant zones for connection to the joining partner.

Optionally, the base material of the plastic component consist of a pure thermoplastic material or reinforced with short fibers thermoplastic. The molding of the plastic component can take place in an injection molding process, in which the thermoplastic fibers in the region of a connection point for connection to the joining partner by means of a clamping frame is fixed in position inserted into the injection mold cavity. Subsequently, the injection molding process takes place, in which the fixed joining fibers are integrated in the correct position in the base material of the plastic component. Alternatively, the fixing of the joining fibers in the injection mold cavity can be effected by means of a coarsely meshed, permeable fabric or fabric in which the electrically conductive joining fibers are sewn. The carrier fabric can be fixed in the injection molding tool to ensure a correct position integration of the joining fibers in the base material of the plastic component.

Alternatively, the plastic component can be produced in a so-called thermoplastic RTM process or in a transfer molding in which a still dry, that is not yet impregnated by matrix material semi-finished fiber is placed in a mold cavity. Subsequently, the liquid starting component of a thermoplastic matrix material is injected into the mold cavity, whereby the semifinished fiber product is embedded in the matrix material.

Before carrying out the thermoplastic RTM process, the semifinished fiber product can be provided with the electrically conductive joining fibers, wherein the semifinished fiber product remains partially exposed from the matrix material after the thermoplastic RTM process to form the electrical contact points. Alternatively, the entire semi-finished fiber product from electrically conductive joining fibers, such as carbon fibers, may be provided.

In the above thermoplastic RTM process and / or generally in the plastic injection molding process, the shaping of the plastic component takes place under pressure and heat. In order to assist the shaping, the joining fibers, optionally in dual function, can also be supplied with electrical current already during shaping, in order to achieve additional heat input into the respective shaping tool.

Alternatively, the plastic component can also be produced from an organo-sheet integration in which an endless-fiber-reinforced semifinished product is used. The electrically conductive joining fibers can preferably be introduced into the semifinished fiber product by static pressing or semi-continuous methods, such as interval hot pressing. In this way, the joining fibers can be targeted to place in the semifinished fiber, for example, in the melt-direct process or film stacking. It is also conceivable to integrate the electrically conductive joining fibers in a continuous process on a double belt press.

The advantageous embodiments and / or further developments of the invention explained above and / or reproduced in the dependent claims can be used individually or else in any desired combination with one another, for example in the case of clear dependencies or incompatible alternatives.

The invention and its advantageous embodiments and further developments and advantages thereof are explained in more detail below with reference to drawings.

Show it:

1 in a perspective partial view by way of example a component composite according to a first embodiment;

2 and 3 respectively views showing a method of making the in 1 illustrate composite component shown;

4 a fabric with electrically conductive joining fibers fixed therein;

5 . 6 and 6a in each case further variants of a plastic component;

7 in a perspective view of a composite component according to a second embodiment;

8th and 9 each views, the production of the composite component from the 7 illustrate; such as

10 to 13 each views from above, which roughly schematically each show a plastic component with extending therein electrically conductive fibers.

The figures are made with a view to a simple understanding of the invention. Therefore, the figures are only roughly simplified representations that do not reflect a realistic construction of a component connection. So is out of the 1 a component composite shown according to a first embodiment, in which a plastic component 1 by way of example with a sheet metal part 3 connected is. That in the 1 lower plastic component 1 is approximately trough-shaped with a laterally raised circumferential joining flange 5 , The frame-like circumferential joining flange 5 has on its front side an interruption, the mutually facing flange edges 7 is limited. From the two facing flange edges 7 each protrude, from the base material of the plastic component exposed end pieces 9 an electrically conductive joining fiber bundle 11 in front. The joining fiber bundle 11 extends along the circumferential joining flange 5 ( 3 ). The basic material of the plastic component 1 may be made of a pure or possibly reinforced with short fibers thermoplastic. In the 1 is the plastic component 1 at its joining flange 5 material and form-fitting to form a joint zone 10 with a metal surface of the sheet metal part 3 connected.

The following is based on the 2 and 3 a process for the preparation of in the 1 described component composite described. Thus, according to the 2 First, the electrically conductive joining fiber bundle 11 provided and roughly contoured to the later course of the joint flange 5 , For example, by means of a known clamping frame, inserted into an injection mold, whereby the joining fiber bundle 11 in the correct position is fixed in the injection mold. Instead of the clamping frame, a support fabric 4 ( 4 ) are used, on which the joining fiber bundle 11 is fixed. The Tragwebe 4 can with the attached fiber bundle 11 placed in the injection mold and clamped in it.

Subsequently, the shaping of the plastic component takes place 1 in which a liquid starting component of the thermoplastic base material is injected into the injection molding tool. The joining fiber bundle 11 is thus in the correct position in the area of the joint flange 5 of the plastic component 1 integrated, while exposing the two end pieces 9 of the joining fiber bundle 11 which act as electrical contact points in the subsequent thermal joining process to the joining fiber bundle 11 to apply electrical power. In the thermal joining process is by the current application of the joining fiber bundle 11 plasticized the thermoplastic base material in the area of the joint flange. Subsequently, the sheet metal part 3 with a predetermined joining force F ( 3 ) against the joint flange 5 of the plastic component 1 pressed. After cooling, the component composite is completed.

In the 5 . 6 and 6a are each in schematic side sectional views of further embodiments of the plastic component 1 being shown in the 5 the tails 9 of the joining fiber bundle 11 After the molding process, each side is completely exposed. In contrast, in the 6 the contact points kept free by the application of inserts not shown in the injection molding or exposed by means of a machining rework.

In the 6a is another exposure method using depositors 19 held in the injection molding process, the depositors 19 itself from an electrically conductive material (for example, copper, graphite or other metals) and after the injection molding process in the plastic component 11 remain. The following advantages actually result, namely a flush finished component surface, no weakening of the component by cross-section reduction and a simple, process-tolerant contacting of the metal insert 19 with electrodes 21 to transfer the current to the fibers / wire 11 ,

The metallic inserts are preferably geometrically designed to provide an undercut 25 have in order to have a better fit in the plastic composite.

In the 7 a component composite according to a second embodiment is shown. Consequently, the plastic component is made of a fiber-reinforced plastic, in which a semifinished fiber product 13 in the basic material acting as a matrix 15 is embedded. In the 7 is an edge flange 17 of the sheet metal part 3 forming the joining zone 10 with the plastic component 1 connected. At a front edge of the plastic component 1 protrude in the 7 the two end pieces 9 of the joining fiber bundle 11 in front. These are connected to a current source in the thermal joining process described below in analogy to the preceding embodiment.

The production of the component composite from the 7 is based on the 8th and 9 explained. According to the 8th becomes the joining fiber bundle 11 in a first process step in a still dry, that is not yet impregnated by the matrix material semi-finished fiber 13 fixed. In the 8th runs the joining fiber bundle 11 by way of example meandering only in the region of the later joining zone 10 while the remaining portion of the semifinished fiber product 13 free from the joining fiber bundle 11 remains. The semifinished fiber product 13 with the joining fiber bundle fixed thereto 11 is then placed in a mold cavity and with the liquid starting component of the matrix material 15 saturated. After the molding of the plastic component 1 the thermal joining process ( 9 ). In the 9 becomes analogous to 3 the joining fiber bundle 11 subjected to electric current, whereby the matrix material adjacent thereto 15 is heated to its plasticization. Subsequently, the edge flange 17 of the sheet metal part 3 against the plasticized matrix material 15 of the plastic component 1 pressed. After cooling the component composite is the edge flange 17 of the sheet metal part 3 material and / or positive fit with the plastic component 1 connected.

In the following 10 to 13 are in schematic views from above each different variants of the plastic component 1 shown: in the 10 are in semi-finished fiber 13 of the plastic component 1 each side joining fibers 11 integrated, namely at the respective, with green marked joining zones 10 , In the 10 Therefore, only the relevant joint zones for the production of the component composite 10 heated and plasticized, while the adjacent component areas remain largely without heat.

In the 11 are also a total of three spaced joining zones 10 in the plastic component 1 provided. The joining fibers 11 run in series ( 12 ) or in parallel ( 11 ) by the spaced apart joints 10 ,

In the 13 are not additional electrically conductive joining fibers 11 in semi-finished fiber 13 integrated, but is the semi-finished fiber 13 rather, completely composed of electrically conductive joining fibers, such as carbon fibers or the like. In this case, when current is applied, the semi-finished fiber product can be completely heated, that is to say over a large area, to carry out the thermal joining process.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been 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.

Cited patent literature

• DE 102006058198 [0005]
• WO 2011/050787 A2 [0005]
• DE 102009028456 B3 [0005]

Claims (11)

Method for component connection of a plastic component ( 1 ) made of a thermoplastic material with a joining partner ( 3 ), in which in a thermal joining process with heat supply, the thermoplastic base material ( 15 ) and the joining partner ( 3 ) to form a material and / or positive connection in the plasticized base material ( 15 ) is pressed, characterized in that in the shaping of the plastic component ( 1 ) electrically conductive joining fibers ( 11 ) in its thermoplastic base material ( 15 ) and that the heating of the plastic component base material ( 15 ) in the thermal joining process by applying the joining fibers ( 11 ) with electric current. Method according to claim 1, characterized in that the joining fibers ( 11 ) only in the area of a joining zone ( 10 ) for connection to the joining partner ( 3 ) and that the basic material ( 15 ) of the plastic component ( 1 ) outside the joining zone ( 10 ) free of joining fibers ( 11 ), and / or that in the plastic component ( 1 ) the joining fibers ( 11 ) at electrical contact points ( 9 ) of the basic material ( 15 ) are exposed. Method according to claim 1 or 2, characterized in that the plastic component ( 1 ) a plurality of spaced apart joints ( 10 ), and in particular that the joining fibers ( 11 ) in series or parallel connection through the joints ( 10 ). Method according to one of the preceding claims, characterized in that the electrically conductive joining fibers ( 11 ) Are carbon fibers, metal wires or fibers and / or conductive coated fibers, and that in particular copper tracks (analogous to heating foils) or copper wires are used as resistance joining elements, which are easier to apply in comparison to the joining fibers and require significantly lower currents. Method according to one of the preceding claims, characterized in that in the plastic component ( 1 ) a semi-finished fiber product ( 13 ), such as a fiber fabric or the like, in the matrix material ( 15 ), and in particular that the plastic component ( 1 ) is produced in a thermoplastic RTM process in which the still dry, that is not yet of matrix material ( 15 ) impregnated semi-finished fiber products ( 13 ) is inserted into a mold cavity, and then the matrix material ( 15 ) is injected into the mold cavity. Method according to claim 5, characterized in that the semi-finished fiber product ( 13 ) at least partially or completely electrically conductive joining fibers ( 11 ), and / or that the semi-finished fiber product ( 13 ) forming the electrical contact points ( 9 ) of the matrix material ( 15 ) is exposed. Method according to one of the preceding claims, characterized in that the shape of the plastic component ( 1 ) under pressure and heat, and that the joining fibers ( 11 ) are subjected to the heat during the shaping with electric current. Method according to one of the preceding claims, characterized in that the plastic component ( 1 ) is produced from at least one Organoblechteil, which is formed from a continuous fiber-reinforced semi-finished fiber, and that in particular the joining fibers are introduced in static presses or semi-continuous processes, such as the interval hot pressing in the continuous fiber-reinforced semi-finished fiber. Method according to one of the preceding claims, characterized in that the electrical contact points ( 9 ) by applying at least one depositor ( 19 ) are kept free in the injection molding process, or that the electrical contact points ( 9 ) are exposed by exciting post-processing on the component. Method according to claim 9, characterized in that the insert ( 19 ) after the component molding in a demolding section exposing the contact points ( 9 ) is removable. Method according to claim 9, characterized in that the insert ( 19 ) after the component molding is an integral part of the component, and that the insert ( 19 ) the electrical contact point ( 9 ).

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