Expanded – threaded – driven – headed – tool-deformed – or locked-thr – Threaded fastener locked to a discreet structure – Design of fastener or substructure restricts rotation
Reexamination Certificate
1999-12-06
2001-06-05
Wilson, Neill (Department: 3627)
Expanded, threaded, driven, headed, tool-deformed, or locked-thr
Threaded fastener locked to a discreet structure
Design of fastener or substructure restricts rotation
C411S324000, C411S437000, C219S098000
Reexamination Certificate
active
06241442
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a fastening means for forming a welded joint between a fastening means and a structure.
For fastening components to a metallic structure, for example, a body of a motor vehicle, fastening means are known which are welded to the metallic structure. Known fastening means comprise a holder and a connecting element. The connecting element can be a weld stud, in particular a Christmas tree stud, which is welded to the structure. A connecting element which can be welded to a component by electric arc welding is known from WO 94/03735. The connecting element is designed in the form of a resilient tube and has a longitudinal slot.
To achieve a high degree of automation, it is known to connect the connecting element to the structure by electric arc welding or resistance welding. Electric arc welding is usually carried out by the lift and strike method.
A holder which consists mainly of a substantially electrically insulating material, in particular a plastic material, is arranged on the connecting element welded to a structure. The holder which can be, for example, a line holder, is hammered or screwed onto the connecting element.
The costs of fitting a fastening element with a welded joint to a structure are relatively high. This problem has already been acknowledged. JP-A1 61-133266 proposes the use of a fastening means in which the holder is connected to the connecting element before a welded joint is formed. The holder, which consists of a substantially electrically insulating material, surrounds a connecting element consisting of a substantially electrically conductive material and having at least one contact face for making electrical contact. In particular, JP-A1 61-133266 proposes that the connecting element, which is designed in the form of a stud, should project from the holder. This creates a sufficiently large electrical contact face. However, the sphere of application of such a fastening means is restricted. The fastening means is used, in particular, for mounting fastening strips which cover the connecting element projecting from the holder.
JP-A1 61-133266 also discloses a fastening means in which the electrical contact face is formed by a projecting peripheral flange formed on the connecting element. To achieve contact between the connecting element and a contact piece of a welding device, the contact piece is tubular in design. To ensure that the tubular contact piece can be brought into electrical contact with the peripheral flange of the connecting element, it is necessary to design the flange so that it projects laterally beyond the holder. For this purpose, it is known to form the holder from a plastics material with a base body and with at least one holding element which is pivotal round an axis formed on the base body from a basic position into a locked position. However, a holder of this type is only suitable for fixing, for example, insulating mats on a body of a motor vehicle.
BRIEF SUMMARY OF THE INVENTION
It is an object of the present invention to provide a method of forming a welded joint which can also be carried out with fastening means having holders of different configurations, in particular holders having no peripheral flange. It is a further object of the invention to provide a fastening means which is constructionally simple in design and is suitable for carrying out a method for forming a welded joint.
The present invention provides a method of forming a welded joint between a fastening means and a structure, in which the fastening means, with a holder consisting of a substantially electrically insulating material which substantially surrounds a connecting element consisting of a substantially electrically conductive material and having at least one contact face for making electrical contact, wherein the holder has at least one through-orifice at least partially overlapping, or aligned with the at least one contact face of the connecting element formed within the holder, is held by a welding device and a contact piece of the welding device is brought into electrical contact with the contact face of the connecting element through the through-orifice of the holder and a welding current is switched on.
The present invention further provides a fastening means, for forming a welded joint with a holder which consists of a substantially electrically insulating material and a connecting element which consists of a substantially electrically conducting material, wherein the holder substantially surrounds the connecting element and the connecting element has at least one contact face for making electrical contact, characterised in that the holder has at least one through-orifice at least partially overlapping the at least one contact face of the connecting element formed inside the holder, wherein the connecting element is formed substantially in the form of a hollow cylinder at least in a region adjacent to the contact face.
With the method according to the invention for forming a welded joint between a fastening means and a structure, it is proposed that the fastening means be held by a welding device and a contact piece of the welding device be brought into contact with a contact face of the connecting element. The contact piece is brought into contact with the contact face of the connecting element through a through-orifice in the holder which consists of a substantially electrically insulating material and surrounds the connecting element. A welding current can be switched on once the contact piece has been brought through the through-orifice in the holder into electrical contact with the contact face of the connecting element. This process control enables fastening means already having a holder which is prefitted on the connecting element and can have various configurations to be obtained. This design also allows improved introduction of a welding current as the contact face can be sufficiently large in design. A further advantage of this process control is that the process according to the invention can be carried out using conventional welding devices.
It is proposed, in particular, that the welded joint be formed by the electric arc welding process. In particular, the welded joint can be formed by the lift and strike process.
Since the contact piece is brought into electrical contact with the contact face of the connecting element through the passage in the holder and a welding current is switched on, this method is also suitable for forming a welded joint by the resistance welding process, as a relatively large force can be introduced into the connecting element through the contact face.
According to a further feature of the invention, a fastening means is proposed, in particular for forming a welded joint according to the invention, which comprises a holder consisting of a substantially electrically insulating material and a connecting element consisting of a substantially electrically conductive material, wherein the holder substantially surrounds the connecting element and the connecting element has at least one contact face for making electrical contact. The holder is designed such that it has at least one through-orifice at least partially overlapping the at least one contact face of the connecting element formed within the holder. This through-orifice enables the contact face to be brought into contact with a contact piece of a welding device. The external configuration of the holder does not obstruct contact. The connecting element is designed such that the contact face is located within the connecting element. The connecting element is designed in the form of a hollow cylinder, at least in a region adjacent to the contact face.
According to an advantageous development of the fastening means, it is proposed that the connecting element be cylindrical in design. In particular, the connecting element can be designed in the form of a stud, preferably in the form of a Christmas tree stud. The connecting element can also have a design of the type known from WO 94/03735. This connecting
Mauer Dieter
Schaty Harald
Emhart Inc.
Murphy Edward D.
Wilson Neill
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