Patent Application
20190099832
The present disclosure relates generally to friction elements and more particularly to corrosion protection for use in joining adjacent workpieces.
The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
A variety of structures being joined often require corrosion protection, and this is especially true for automotive assemblies such as body panels. One such technique for joining structures is a friction element welding process, where heat is generated by rotation of a friction element (i.e., fastener) under application of an axial force. The friction element is connected to the structures during partial melting of the friction element, or portions thereof, and the mating structure.
Referring to
One known method and friction element for use in this type of friction welding for automotive body parts/panels is the EJOWELD® friction welding method and rivet-type friction element. However, this method can present issues since the interface between the head 4 of the friction element 1 and the structures being joined (upper piece 2/lower piece 3) may be exposed to environmental substances that can penetrate the interfaces and eventually cause corrosion.
This corrosion issue in joined assemblies using a friction welding method and related friction elements, among other mechanical joining issues, is addressed by the present disclosure.
In one form of the present disclosure, a corrosion barrier for use under heads of a plurality of friction elements in a structural assembly is provided. As used herein, the term “structural assembly” includes both structures that carry load and those that do not carry any appreciable loads, e.g. fairings/facia. The corrosion barrier defines a plurality of spaced apertures extending along a length of the corrosion barrier and a corresponding plurality of perforations concentrically located around the spaced apertures.
According to various forms of the corrosion barrier, the plurality of spaced apertures may define a circular geometry configured to receive the plurality of friction elements. The plurality of perforations may also define a circular geometry. The area between each of the spaced apertures and each of the perforations may define a washer configured for placement under the heads of the plurality of friction elements. The plurality of spaced apertures and perforations may be evenly spaced.
In one variation, the corrosion barrier defines a rectangular geometry having upper and lower longitudinal edges and a plurality of locating apertures disposed along the upper and lower longitudinal edges. In this form, a width of the corrosion barrier may be about 10 mm greater than a diameter of each of the heads of the friction elements.
In another variation, the area between the each of the spaced apertures and each of the perforations defines a removable member, and the perforations are configured to separate the removable member from the corrosion barrier as a function of at least one of material properties of the corrosion barrier, a size of the spaced apertures, and a spacing of the spaced apertures.
In another form of the present disclosure a friction element strip assembly is provided that comprises a plurality of friction elements and a corrosion barrier for use under heads of the plurality of friction elements. The corrosion barrier defines a plurality of spaced apertures extending along a length of the corrosion barrier and a corresponding plurality of perforations concentrically located around the spaced apertures. The plurality of spaced apertures may define a circular geometry configured to receive the plurality of friction elements. The plurality of perforations may also define a circular geometry. The area between each of the spaced apertures and each of the perforations may define a washer configured for placement under the heads of the plurality of friction elements. The plurality of spaced apertures and perforations may be evenly spaced.
In one variation, the corrosion barrier defines a rectangular geometry having upper and lower longitudinal edges and a plurality of locating apertures disposed along the upper and lower longitudinal edges. In another form, a width of the corrosion barrier is about 10 mm greater than a diameter of each of the heads of the friction elements.
In another variation, an area between the each of the spaced apertures and each of the perforations defines a removable member, and the perforations are configured to separate the removable member from the corrosion barrier as a function of at least one of material properties of the corrosion barrier, a size of the spaced apertures, and a spacing of the spaced apertures.
In yet another form, the present disclosure provides a method of installing a corrosion barrier under heads of a plurality of friction elements in a structural assembly. The method comprises the steps of:
locating a plurality of friction elements within a corresponding plurality of spaced apertures in a corrosion barrier to form a friction element strip assembly, the fastener strip assembly defining a corresponding plurality of perforations concentrically located around the spaced apertures;
loading the friction element strip assembly into the two workpieces;
securing the friction element strip assembly; and
removing an area of the corrosion barrier such that only a removable member between the apertures and the perforations remains under the heads of the friction elements.
In one variation, the corrosion barrier defines a rectangular geometry having upper and lower longitudinal edges and a plurality of locating apertures disposed along the upper and lower longitudinal edges, wherein the locating apertures are aligned with pins before loading the friction element strip assembly into the two workpieces. The area of the corrosion barrier that is not installed under the heads of the friction elements may be recycled. In another form, the friction element strip assembly is gravity fed into an installation machine prior to locating the plurality of friction elements.
Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.
In order that the disclosure may be well understood, there will now be described various forms thereof, given by way of example, reference being made to the accompanying drawings, in which:
The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.
The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features.
Referring to
Each friction element 10 also defines a head 14 as shown. The plurality of perforations 24 define a geometric shape configured to correspond to the geometric shape of the head 14, and more specifically the shape of a distal face 16. As shown, the plurality of perforations 24 define a circular geometry to correspond to a circular distal face 16 of the friction element 10. However, this circular geometry should not be construed as limiting the scope of the present disclosure since other shapes may be employed, such as by way of example, square, hexagonal, and other polygonal geometries. Generally, the perforations 24 create a controlled fracture location along the corrosion barrier 20 and can be in the form of scoring or a scribe, which allows the material to separate at the perforations 24.
In still another form of the present disclosure, the corrosion barrier 20 could be configured without the perforations 24 and the rotational speed of the friction weld element (i.e., friction element 10) at installation would shear the corrosion barrier 20 proximate the heads of the friction elements 10. This could be accomplished, for example, with a predetermined rotational speed at installation versus the material and thickness of the corrosion barrier 20. Therefore, the perforations 24 may not be needed in another form of the present disclosure.
An area of the corrosion barrier 20 between the each of the spaced apertures 22 and each of the perforations 24 defines a removable member 26 configured for placement under the heads 14 of the plurality of friction elements friction elements 10 to form a local corrosion barrier. In one form, this removable member 26 is a washer as shown. Installation of the corrosion barrier 20 and how the removable members 26 are removed to form individual/local washers/elements under the friction element heads 14 is described in greater detail below.
The size and spacing of the plurality of spaced apertures 22 and perforations 24 depends on the structural assembly, and in one form, the plurality of spaced apertures 22 and perforations 24 are evenly spaced to correspond to evenly spaced friction elements friction elements 10. Alternatively, the spaced apertures 22 and perforations 24 may not be evenly spaced as a function of the design of the structural assembly. In still another form, the spaced apertures 22 and perforations 24 may be evenly spaced but with different sizes/shapes and/or unevenly spaced with the same or different sizes/shapes. Each of these variations is to be construed as being with the scope of the present disclosure.
In one form of the present disclosure, a width W of the corrosion barrier 20 is about 10 mm greater than the diameter of the heads 14 of each of the friction elements friction elements 10. However, other widths may be employed while remaining within the scope of the present disclosure. Materials for the corrosion barrier 20 may include, by way of example, thermoplastic polymer, a closed cell foam, a wax-dipped fiber mat, or a non-ferrous metal.
Referring now to
It should be understood that this shape and configuration of a friction element strip assembly 30 is only exemplary and that other configurations (e.g., not rectangular and/or without locating apertures 36) may be employed while remaining within the scope of the present disclosure. The function of the friction element strip assembly 30 is to deliver the friction elements friction elements 10 to the structural assembly for installation, using the innovative corrosion barrier 20 according to the teachings of the present disclosure.
Referring to
In
As shown, the plurality of friction elements 10 are located and placed within the corresponding plurality of spaced apertures 22 of the corrosion barrier 20 to form the friction element strip assembly 30. The plurality of friction elements 10 are aligned with and placed into optional apertures/clearance holes 44 of the upper workpiece 40. In one form, the friction element strip assembly 30 is gravity fed into an installation machine (not shown). After the friction elements 10 are located, an installation tool from the friction welding equipment (described above) progressively installs the friction elements 10 to the workpieces 40, 42, as shown in
In
As shown in
The portion of the corrosion barrier that remains after removal is referred to as a remnant 52, which may be recycled.
Referring to
Referring now to
Next, the method includes a step 74 of installing the friction element strip assembly to two work pieces. Optionally, an area of the corrosion barrier is removed in step 76 such that only the removable member between the apertures and the perforations remains under the heads of the friction elements. (
It should be understood that the friction element weld process illustrated and described herein is merely exemplary, and thus the teachings of the present disclosure are also applicable to other joining technologies and applications, such as for example, resistance welding, and riveting, among others. Therefore, the friction element weld process should not be construed as limiting the scope of the present disclosure. Such variations should be construed as falling within the scope of the present disclosure.
The description of the disclosure is merely exemplary in nature and, thus, variations that do not depart from the substance of the disclosure are intended to be within the scope of the disclosure. Such variations, such as those disclosed in U.S. application Ser. No. 15/382,607, which is commonly assigned with the present application and incorporated herein by reference in its entirety, are not to be regarded as a departure from the spirit and scope of the disclosure.
