Method for joining fiber-reinforced plastic material

Abstract

A method is provided for joining a fiber-reinforced joining element, formed from a plastic material, to the joining surfaces thereof by way of an ultrasonic welding method. A concentrator and/or at least one insertion element is arranged in the region of the joining surfaces prior to fusing between the joining surfaces, and the concentrator and/or the insertion element are fused together with the joining surfaces in order to form a positive fit joint therewith after hardening.

Claims

1. A method for joining fiber-reinforced joining partners formed of a plastics material, the method comprising the acts of: applying a concentrator in a region between connection faces of the joining partners; and fusing together, via ultrasonic welding, the connection faces such that a materially integral joint is obtained post-curing as a mixing region configured from materials of the joining partners and the concentrator; wherein the joining partners are composed of a thermoplastics material into which a plurality of endless fibers are embedded; wherein the concentrator comprises a fiber-reinforced plastics material; wherein post-curing, the materially integral joint comprises in each case one upper and lower boundary surface, wherein a plurality of reinforcement fibers of the concentrator protrude through the boundary surfaces and into adjacent material regions of the joining partners and contribute toward a strength of the materially integral joint.

2. The method according to claim 1, wherein carbon fibers, carbon-based fibers or glass fibers, respectively, are used as fiber-reinforcements.

3. The method according to claim 1, wherein plastics granulate is used as the concentrator.

4. A method for joining fiber-reinforced joining partners formed of a plastics material, the method comprising the acts of: applying an insert in a region between connection faces of the joining partners; and fusing, via ultrasonic welding, the connection faces such that the insert is embedded in a materially-integral manner into the connection faces and a form-fitting joint is obtained; wherein the joining partners are composed of a thermoplastics material into which a plurality of endless fibers are embedded; wherein the insert comprises a fiber-reinforced plastics material; wherein post-curing, the form-fitting joint comprises in each case one upper and lower boundary surface, wherein a plurality of reinforcement fibers of the insert protrude through the boundary surfaces and into adjacent material regions of the joining partners and contribute toward a strength of the form-fitting joint.

5. The method according to claim 4, wherein carbon fibers, carbon-based fibers or glass fibers respectively, are used as fiber-reinforcements.

6. The method according to claim 4, wherein a plurality of inserts having various shapes and/or material compositions are embedded into the form-fitting joint.

7. The method according to claim 4, wherein the insert has a melting temperature above a melting temperature of the joining partners.

8. The method according to claim 6, wherein the plurality of inserts have melting temperatures above the melting temperatures of the joining partners.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic view of an ultrasonic welding device in which a concentrator in the form of fiber-reinforced or particle-reinforced thermoplastic granulate is used;

(2) FIG. 2 is a schematic view, similar to FIG. 1, of an ultrasonic welding device in which, instead of the concentrator, a dimensionally stable insert having a higher melting temperature than that of the joining partners is embedded into the joint; and

(3) FIG. 3 is a schematic sectional view through a joint between two joining partners that has been produced by the method according to the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

(4) The method will be explained hereunder with reference to FIGS. 1 to 3, wherein the same reference signs indicate functionally and structurally identical elements.

(5) The method is carried out by use of an ultrasonic welding method, using an ultrasonic welding device 30. The ultrasonic welding device 30 has a conventional ultrasonic converter 31 and a sonotrode 32 which, by means of a force F, may be pressed onto the joining partners. By way of the ultrasonic welding device 30, ultrasonic oscillations may be obtained on the boundary surfaces of the two joining partners 10, 20. When ultrasonic oscillations are created, the connection faces 11, 21 of the joining partners 10, 20 are continuously fused. Prior to the planar joining faces being converged and up to the complete linking of the two joining partners 10, 20, a concentrator 1 was introduced between the joining partners 10, 20, specifically between the connection faces 11, 21 of the latter, as is shown in FIG. 1.

(6) Alternatively thereto, in the method illustrated in FIG. 2 a carbon fiber-reinforced thermoplastic insert 2 is embedded into the joint. This insert 2 has a melting temperature which is above the melting temperature of the joining partners such that the insert, upon fusing of the joining partners by means of ultrasound, remains dimensionally stable and is thus embedded in a form-fitting manner into the joint.

(7) It is furthermore provided that as a result of a stationary fusing behavior, a molten layer thickness is configured which is constant or is configured according to the intended use, respectively, and which may be influenced by way of the amplitudes of the sonotrode or else by way of the force profile. Upon configuration of a sufficiently thick molten layer thickness, the impingement with ultrasound is stopped and the weld zone solidifies such that a form-fitting joint 3, which has in each case one upper and lower boundary surface 3a. 3b, is configured. The fused region which is defined by the fused molten layer thickness therebetween configures a transition region 3c, as is schematically shown in FIG. 3. A plurality of reinforcement fibers 3d of the concentrator used, which in each case protrude through the adjacent boundary surface 3a, 3b into the respective adjacent material regions of the thermoplastic plastics material joining partners 10, 20, which are reinforced with endless fibers, and thus contribute toward the strength of the connection, are located in the transition region 3c.

(8) The present exemplary embodiment may be implemented using thermoplastic polyamide which is configured so as to be reinforced with endless fibers. Fiber-reinforced polyamide PA 66 in the form of granulate may be employed as the concentrator 1, for example.

(9) The invention in terms of the implementation thereof is not limited to the preferred exemplary embodiments stated above. Rather, numerous variants which utilize the illustrated solution are contemplated, even if the embodiments are of a fundamentally different type.

(10) The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.