The present invention relates to a riveted joint.
By means of a riveted joint, two components can be joined together in a form-fitting manner by a plastically shapeable connecting element, namely the rivet, which is usually cylindrical. One application of riveted joints is for non-releasable joining of metal parts, such as steel beams, aircraft parts or ship parts.
One of the components to be joined by means of a riveted joint has a rivet shaft, usually cylindrical, or a rivet head, which is passed through a rivet through-hole in the other component. The riveted bolt is shaped in width after passing the riveted bolt through the hole, so that the two components are joined together inseparably in a form-fitting manner.
In the case of riveted joints based on plastic, i.e., joints in which at least the plastically shapeable riveted bolt is made of plastic, the shaping of the riveted bolt, which is often used to form the riveted joint, is achieved under the influence of heat.
The riveted bolt, which is typically made of a thermoplastic material, for example, is heated to a predetermined melting point, e.g., by means of a hot gas nozzle, and then is shaped to form a rivet head by means of a cold ram.
If the same type of plastic is used for the two components that are to be joined together by means of a riveted joint, an integrally bonded joint is formed between the heated rivet head and the holding part. Even when using different plastics that are plastically shapeable in the same temperature range, an integrally bonded joint of the parts comes about due to the melting of the rivet in at least some areas following its thermoplastic shaping, thereby decreasing or preventing relative rotatability or mobility of the joined parts.
In one aspect, an embodiment provides a riveted joint based on plastic, in which the components that are joined together are movable with respect to one another in the plane perpendicular to the rivet.
In some implementations, a riveted joint based on plastic has two components: a rivet part and a holding part provided for it. A riveted bolt, preferably cylindrical in design, is formed on the rivet part, extending essentially perpendicular to the plane of the rivet part. The holding part has a rivet through-hole, which is provided for the riveted bolt and has a larger bore accordingly. A sliding layer is provided on the side of the holding part facing away from the rivet part and should counteract the formation of a physically bonded joint.
Following thermoplastic shaping of the rivet which is passed through the through-hole, direct contact between the rivet head and the holding part is prevented or reduced, so that the holding part, which is preferably made of the same plastic as the rivet, is less likely to form an integrally bonded joint with the rivet head in the area of its surface facing the rivet head.
The sliding layer thus prevents or impedes the formation of an integrally bonded joint between the holding part and the rivet part, so that the connection joining the two parts is formed essentially only on the basis of the form-fitting joining of the rivet head to the holding part. Depending on the design of the riveted bolt and the rivet through-hole, the two components, i.e., the rivet part and the holding part, are movable relative to one another in the plane perpendicular to the rivet shaft, preferably being rotatable about the axis formed by the rivet.
According to a first embodiment, the at least one riveted bolt and/or the rivet part is/are made of a thermoplastic material. The sliding layer arranged on the holding part is essentially heat-resistant, at least in the temperature range of elastic shapeability of the riveted bolt. Consequently, the sliding layer then retains its function even when it comes in direct contact with the heated riveted bolt or rivet head.
According to another embodiment, the sliding layer covers at least one edge area adjacent to the rivet through-hole in the form of a ring. The radial extent of the sliding layer here corresponds essentially to the radial extent of the undercut of the rivet head that can be shaped from the riveted bolt. This increases the likelihood that the entire area of the undercut formed by the rivet head does not come into a direct contact position with the holding part when the riveted joint is assembled. The sliding layer here forms a dividing layer between the undercut of the rivet head and the surface of the holding part facing the rivet head.
According to another embodiment, the holding part and the rivet part are movable relative to one another when the riveted joint is formed. Depending on the embodiment of the riveted bolt and the rivet through-hole, which may be formed as an essentially circular hole or in the form of an elongated slot, for example, the components that are joined together by a riveted joint are displaceable relative to one another, for example, and in some implementations, are designed to be rotatable relative to one another. The relative rotation of the rivet part and the holding part here is preferably about the axis formed by the riveted bolt.
In addition, the rivet through-opening is designed as an essentially round borehole or as an elongated slot and/or as an elongated coulisse, e.g., in the manner of an elongated slot. Especially versatile use of certain embodiments of the riveted joint, e.g., as a rotationally movable joint or optionally a one-dimensional or two-dimensional guide can thus be implemented. The mutual displacement and/or rotation of the interconnected components, as universally as possible, can be made available, depending on the geometric design of the rivet through-hole.
According to another embodiment, a film made of wax, in particular peppermint wax, is provided for the sliding layer. The surface of the holding part facing the rivet part may be coated very easily with such a wax, preferably with a thin film of wax. Peppermint wax has the thermal stability adequate for thermoplastic shaping of certain embodiments of the rivet.
Alternatively, instead of a wax, a corresponding oil which forms a lubricant film may also be used.
According to another independent aspect, some embodiments provide a method for forming a riveted joint based on plastic and having at least one rivet part and a corresponding holding part. A riveted bolt is integrally molded on the rivet part, passing through a rivet through-hole in the holding part to form the riveted joint. The method for forming the riveted joint is characterized in that before thermoplastic shaping of the riveted bolt in a rivet head, a sliding layer is provided on the side of the holding part facing the rivet head.
The sliding layer, preferably comprising a thin film of lubricant, may be applied to the holding part, e.g., in the form of a film of wax, at the time of manufacturing of the holding part. Alternatively, it is also conceivable for the sliding layer to be applied only immediately before a thermoplastic shaping process for the riveted bolt. The latter is advantageous, for example, when using an oil film that can be sprayed on as the sliding layer, e.g., after passing the riveted bolt through the rivet through-hole.
An embodiment of the riveted joint based on plastic is suitable in particular for use in replaceable attachable brushes for electric toothbrushes. It is used here for implementation of a rotationally movable connection of a rotationally movable toothbrush head with a toothbrush neck. In this way, a permanent heavy-duty joint which is rotationally movable in particular is established between a brush neck and a brush head that can be rotated by an electric motor.
The present invention is not limited to use in the field of toothbrushes, but instead may be used universally for any type of plastic riveted joints.
Additional goals, features and advantageous possible applications are derived from the following description of exemplary embodiments on the basis of the drawings. All the features described here and/or illustrated in the drawings constitute the subject matter of the present description in their logical combination, even independently of the patent claims.
According to this embodiment of the riveted bolt 18, the holding ring 12 of the holding part 10 has a rivet through-hole 16 into which the riveted bolt 18 is to be inserted to form the riveted joint. In addition, a handle or shaft 24 is integrally molded on the holding ring 12, representing a toothbrush neck, for example. The base 14 may be connected to other parts, such as a toothbrush head, or parts having other functions, e.g., toothbrush bristles, may be attached to the base 14 and/or to the rivet part 20.
A sliding layer 22 is provided on the top side of the ring-shaped holding part 10 in the area around the rivet through-opening 16. This sliding layer covers at least a radial area around the rivet through-opening 16, an area which corresponds at least to the radial extent of the undercut formed by the rivet head 26. Depending on the manufacturing process, the sliding layer 22 may be designed as a film of heat-resistant wax or oil, for example. It is conceivable here in particular that the sliding layer 22 also covers the entire top side of the ring-shaped holding part 10.
A form-fitting connection is achieved between the two components 12, 14 by thermoplastic shaping of the rivet 18 to form a rivet head 26, as shown in
Finally,
Number | Date | Country | Kind |
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10 2006 012 043.4 | Mar 2006 | DE | national |
This application is the national stage of International Application No. PCT/EP2007/000282, filed Jan. 13, 2007, which claims priority to German Application No. DE102006012043.4, filed Mar. 16, 2006.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/EP07/00282 | 1/13/2007 | WO | 00 | 9/15/2008 |