Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
1999-07-23
2001-08-14
Crispino, Richard (Department: 1734)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C156S153000, C156S257000, C156S267000, C156S278000, C156S293000, C074S552000, C074S558000, C029S894100
Reexamination Certificate
active
06273981
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATION
This application claims the priority of patent application Ser. No. 198 33 314.5, filed in Germany on Jul. 24, 1998, the subject matter of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
The invention relates to a method for producing a motor vehicle steering wheel, having a ring with at least one segment provided with a cover.
Steering wheels in passenger vehicles and utility vehicles are frequently manufactured not from one type of material alone, but also have so-called covers made of different materials. The unfinished steering wheel part, consisting of a ring with inserted impact-absorbing element, is for the most part made of plastic. The covers can consist, for example, of wood, stone, leather or fabric. As a result, steering wheels can be configured in many different ways and can thus increase the value of the motor vehicle inside space.
The methods known so far require several successive operational steps to attach the covers to the unfinished steering wheel parts. This operation takes place either before or after the impact-absorbing element is inserted into the ring. A disadvantage in this case is that the ring and the impact-absorbing element must be protected during the processing of the cover as they might otherwise be damaged. Consequently, the manufacture of such steering wheels becomes very involved and expensive. If the cover is actually damaged during the application, the complete arrangement of ring with impact-absorbing element and cover frequently cannot be used any more.
It is the object of the present invention to demonstrate a method, which allows a simple and cost-effective production of a steering wheel of the aforementioned type.
SUMMARY OF THE INVENTION
The method according to the invention provides that in the case of a motor vehicle steering wheel with a ring, which has at least one segment with cover, a ring with preferably round cross section and at least one region of reduced circular cross section is initially produced. This region functions to accommodate the cover during a later processing step.
The ring, which is preferably compression-molded from a suitable plastic material, in this case can be produced together with an impact-absorbing element that is fixedly connected to the ring with the aid of one or more spokes.
Chronologically independent of this, two identical unfinished steering wheel parts are respectively manufactured, which correspond to the number of regions. The covers are produced from these unfinished parts during the following processing steps. The arc length of the unfinished parts corresponds to that of the area (2). They have a semicircular cross section, for which the diameter is smaller than that of the circular cross section of the ring. If the cover is to be used in the gripping range, then the unfinished parts can already contain finger indentations.
Following this, a channel-shaped groove is milled into the unfinished part, starting with the level inside surfaces and respectively in longitudinal direction. These grooves correspond to the shape of the ring in the region of the reduced circular cross section.
A decorative layer, e.g. of rare wood, is applied to the convex outside surfaces of the unfinished parts. This decorative layer essentially determines the look of the cover.
The coated, unfinished parts are then joined during the following processing step along their level inside surfaces to form a tubular ring segment.
A coat of lacquer is subsequently applied over the decorative layer of the tubular ring segment. This coat of lacquer protects the decorative layer from outside influences, and additionally provides various design options through the use of different types of lacquer.
The tubular ring segment is then divided into two equal halves. The halves formed in this way together form the cover.
An adhesive is applied to the grooves as well as the parting planes of the halves. The adhesive selection is based on the materials used to produce the ring and the halves.
The two halves are pressed onto the steering wheel ring in the region of the reduced circular cross section. In that case, the arrangement must remain fixed in place until the adhesive has hardened. The two halves then enclose the ring completely in the region of the reduced circular cross section. The circular cross section of the ring in the region provided with the cover approximately corresponds to its circular cross section in the segments without a cover.
In a last processing step, the adhesive residues can be removed in the region of the adhesive joints. This final treatment of the adhesive joints may be necessary if excess adhesive is pushed out of the adhesive joints and hardens on the surface while the two halves are pressed onto the ring. The adhesive residues must be removed with the utmost care, so that the surface of the lacquer coat is not damaged.
The method according to the invention thus makes it possible to manufacture the steering wheel ring and its cover separately and subsequently join the two. Consequently, it is no longer necessary to protect the ring and the impact-absorbing element during the processing of the cover. A considerable reduction in the production expenditure results, which permits a cost-effective production.
Another advantage of the method is that the two steering wheel components can be produced in sufficient numbers to have in stock and, depending on the demand, can be produced quickly.
According to one advantageous embodiment of the method, the unfinished parts for the cover can be produced from two or more different materials. The type and composition of the varied materials in that case is determined by the required characteristics for the cover.
It makes sense if after the removal of the adhesive residues in the region of the adhesive joints, the transitions between ring and cover, as well as between the two halves are reworked. In the process, the transitions can be ground and polished, for example, to remove slight irregularities at the locations where identical and different materials are joined. With this, a clean transition is created between ring and cover and between the two halves of the cover. However, a careful mode of operation is required in this case as well, so that the surface of the ring and the coat of lacquer on the cover are not damaged.
Prior to applying the decorative layer onto the unfinished parts, it is particularly advantageous to drill respectively aligned positioning holes into the unfinished parts, starting from their level inside surfaces. Locating pins are inserted into these bores prior to the joining. As a result, a precise joining of the unfinished parts before the application of the lacquer coat is ensured.
REFERENCES:
patent: 4450650 (1984-05-01), Holden et al.
patent: 5840144 (1998-11-01), Schumacher et al.
patent: 6012354 (2000-01-01), Futschik et al.
patent: 4039138 C1 (1992-02-01), None
patent: 2 142 299 A (1985-01-01), None
Kellermann Andreas
Mertes Peter
Crispino Richard
Hawkins Cheryl N.
Holzindustrie Bruchsal GmbH & Co. KG
Kinberg Robert
Venable
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