DE102005047465A1 - Joining together two plastic parts, especially car key halves, comprises passing current through a conductor on a joining surface so that the surfaces adjacent to the conductor are melted and bonded together - Google Patents

Abstract

Joining together two plastic parts (K1, K2) comprises passing current through a conductor (D) on a joining surface (F) so that the surfaces adjacent to the conductor are melted and bonded together. An independent claim is also included for a car key comprising two plastic half-shells welded together as above.

Description

The The present invention relates to a method for connecting two Plastic parts by means of heating a conductive Element between the plastic parts, as well as a manufactured by the process Plastic workpiece.

It is hitherto known plastic parts by means of gluing, clamping or weld together to connect by laser.

method for welding of plastic parts, in particular by means of laser, are well known.

That's how it is DE 200 23 490 U1 a device for welding plastic known. In this case, a connection between a first joining surface of a component and a second joining surface of a second component is produced by means of a laser, the joining surfaces of the first and second component defining cross sections and connected to a joining field of adjoining field sections by means of a laser. The joining surfaces are joined by guiding the laser beam along the boundary surfaces of both joining surfaces.

Out EP 0 773 164 A1 For example, a method for sealing a packaging material film is known. Here are two types of special sections integrated into the film, which are heated by a laser and thereby fuse together.

Out DE 199 19 191 A1 is another method for connecting two surfaces, in particular of thermoplastic material known. In the so-called pass-through welding process, the hidden surface is repeatedly scanned through the covering surface with a laser beam in the pass and thereby heated stepwise. This preheating is repeated until the melting temperature is reached. In the area of the concealed surface, a melt thus simultaneously forms over the entire seam length, which wets the covering surface and likewise transfers it into the melt by heat conduction. With the beginning of material softening, the surfaces are moved against each other until they stop. As a result, both surfaces weld in principle as if they had been simultaneously plasticized over the entire seam length, which significantly increases the tightness and strength of the seam.

adversely At these mentioned procedures is that in each case a special plastic in larger quantities must be used, which completes the laser beams and converts into heat. As a result, in the design and manufacture of the plastics to be connected to a transmissive and non-transmissive Material in the choice of materials and thus in the possible Design of a plastic part must be respected. At the same time be taken to ensure that inside the plastic parts located Components such as electronic assemblies or components in the Use of the laser is not damaged become.

These The object is achieved by the features of patent claims 1 and 9. Advantageous developments The invention will become apparent from the dependent claims, the further description and the attached figures.

It become by the invention two components, consisting of different or the same plastic materials, but which have the property of thermal liquefaction must have, therefore preferably thermoplastic, interconnected, preferably inseparably connected.

In a joining area, d. H. the area in which the two components, preferably inseparable, to be connected to each other, is an electrically conductive zone present, which in a preferred embodiment almost nationwide at the interface is arranged, present.

In a further embodiment The invention is an electrically conductive element, preferably in the form of a wire on one of the components in the almost entire area the interface or also arranged only partially at defined locations of the joining surface, preferably this is embedded in the component at the interface, or it is located in / on / at the joining zone between both components.

In a preferred embodiment of the invention, the wire with one of the components sprayed, preferably in a 2K injection molding process.

After this the components are assembled, the wire is electrically contacted and flowed through with electricity. By the current flow is heated the wire and converted the electrical energy into heat. As a result, the plastic of the two plastic parts around the wire melted around and through this melt is the plastic Both components merged together.

The use and heating of the wire then leads to an inseparable connection bond between the components.

In a further embodiment of the invention, the wire is through a electrically conductive plastic replaced. A component is in a preferred embodiment of the invention in 2-K injection molding produced. So that the conductive Plastic produced directly with the component in one operation can be.

Especially advantageous in this invention is that in the production and the welding process medium Electricity must not be taken to ensure that the workpiece is made from the two components and the element oriented correctly to the Verschweißungsstelle must be spent. It only needs a contact of the Wire or the electrically conductive plastic.

in the Further, the invention with reference to specific embodiments described in more detail, in particular by means of a key for a motor vehicle.

It shows 1 and 2 in each case a key according to the invention for a motor vehicle in section.

First, will Specifically, the use of a wire for welding both plastic shells K1 and K2 described.

1 shows a section through a key according to the invention for a motor vehicle, which is produced by the method according to the invention.

Of the key consists of two plastic shells K1 and K2, which at least a joint F or a joining area F form-fitting with each other and inseparably connected. The two plastic half shells K1 and K2 are preferably made of thermoplastic material. In so far is not to pay attention to that color and other Properties of the plastics must be chosen accordingly, so these fit together. This problem does not arise because of the warming and liquefaction the plastic in the vicinity of the wire connect both Plastic half shells K1 and K2 take place - after cooling down again Plastic. It is advantageous if the plastic half shells K1 and K2 after the melting of the respective plastic in the joint area F be compressed with a defined force.

in the joining area F is an electrically conductive element D, preferably a wire and again preferably a heating wire arranged. This electrically conductive element D is in its Material property electrically conductive with a good heating factor selected, so that the plastic of the plastic half-shells around the electric conductive element D melt around quickly when the electrically conductive element D is traversed by electricity. Once through the electrically conductive element D, speak the wire, electricity flows, The adjoining plastic of plastic half-shells K1 melts and K2 by the heat. By the current flow through the element D is at the same time the heat transfer in the plastic half shells K1 and K2 generated so that the plastic of these two plastic half shells K1 and K2 in the contact surfaces to the element D and the adjacent surfaces of both plastic half-shells also melts to each other. This welds the two plastic half shells K1 and K2 with each other.

It is according to 1 provided that the electrically conductive element D is attached to one of the plastic half-shells K1 or K2, namely the plastic half-shell K1 in a so-called 2K injection molding process.

It can be the electrically conductive Element D but also when joining the plastic half shells K1 and K2 in the joint area F are introduced.

In 2 a further preferred embodiment of the invention is shown. The electrically conductive element D is attached to one of the plastic half-shells K1 or K2, namely the plastic half-shell K1 in a so-called 2K injection molding process. The joining region F is thus preferably in / on / on the surface between the plastic calving tray K2 and the electrically conductive element D. The electrically conductive element D melts in current flow through the electrically conductive element D in the plastic half-shell K1. In this embodiment, preferably, the half-shell K2 made of a different material than plastic; but precautions must be taken so that a mechanical anchoring of the electrically conductive element D and two half-shells K1 and K2 takes place.

In a further advantageous embodiment of the invention, the electrically conductive element D is arranged over the surface of the joining region F of at least one of the plastic half-shells K1 or K2. In this case, the electrically conductive element D is preferably an electrically conductive substance which heats up strongly and rapidly in the case of an applied current, preferably a plastic. The electrically conductive element D heats the plastic of the plastic half-shells K2 and K1 in the joining region F. As a result, the plastic is molten zen and it results after cooling a dimensionally stable connection of the two plastic half shells K1 and K2.

It there is also the possibility the electrically conductive Element D by induction or by means of a laser or To heat plasma jet. In the case of the use of a laser must but at least one of the plastic half shells be laser transparent.

Claims (9)

Method for connecting two plastic parts (K1, K2) by means of an electrically conductive element (D), the element (D) at a joining surface (F) between the plastic parts (K1, K2) is arranged and the element (D) at flow of a Electric current is heated by the same and by the heating of the electrically conductive Element (D) at least one of the two plastic parts (K1, K2) in the electrically conductive Element (D) adjacent surface melts and thus both plastic parts (K1, K2) with each other get connected. Method for connecting two plastic parts (K1, K2) by means of an electrically conductive element (D), the electrically conductive Element (D) at a joining surface (F) between the plastic parts (K1, K2) is arranged and the electric conductive element (D) at flow of a electric current heats up and by the effect of temperature in the plastics of the plastic parts (K1, K2) in the electrically conductive element (D) adjacent Melt layers and thus the plastic parts (K1, K2) with the electrically conductive element (D) and connects to each other by placing in the joining surface (F) between the plastic parts (K1, K2) and the electrically conductive element (D) a melting the plastic of the plastic parts (K1, K2) thus takes place during cooling down the plastic melt the electrically conductive element (D) and the plastics the plastic parts (K1, K2) firmly connected and inseparable get connected. Method for connecting two plastic parts (K1, K2) by means of an electrically conductive element (D), the electrically conductive Element (D) at a joining surface (F) between the plastic parts (K1, K2) is arranged and the electric conductive element (D) at flow of a electric current heats up and by the effect of temperature in the plastics of the plastic parts (K1, K2) in at least the electrically conductive element (D) adjacent Layer to the second plastic part (K2) melts and thus the electrically conductive element (D) melts into the plastic of the second plastic part (K2), wherein the electrically conductive element (D) is firmly connected to the first plastic part (K1) and through the melting of the electrically conductive element (D) in the Plastic of the second plastic part (K2) an inseparable connection the second plastic part (K2) with the first plastic part (K1) over the electrically conductive Element (D) takes place. Method according to one of claims 1 to 3, characterized that a mechanical connection between the electrically conductive element (D) and the second plastic part (K2) by the production in 2K injection molding process he follows. Method according to one or more of the previous ones Claims, characterized in that the element (D) is a wire or a Heating wire or an electrically conductive material is. Method according to claim 4, characterized in that that the more electrically conductive Fabric is a plastic. Method according to one or more of the preceding Claims, characterized in that the plastic parts (K1, K2) plastic half-shells are. Method according to claim 7, characterized in that that the plastic half-shells (K1, K2) are used to form a key for a motor vehicle. key for a Motor vehicle consisting of two plastic half-shells welded together (K1, K2) according to the method features of claims 1 to 8.