Plastic and nonmetallic article shaping or treating: processes – Forming articles by uniting randomly associated particles – Autogenously or by activation of dry coated particles
Reexamination Certificate
1998-07-22
2001-11-06
Ortiz, Angela (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
Forming articles by uniting randomly associated particles
Autogenously or by activation of dry coated particles
C264S254000, C264S302000, C264S303000, C264S311000
Reexamination Certificate
active
06312633
ABSTRACT:
BACKGROUND OF THE INVENTION
a) Field of the Invention
The present invention concerns a method of producing dashboards, door or side trim panels for motor vehicles with a predetermined breaking line for an airbag as well as dashboards, door or side trim panels for motor vehicles from a slush membrane.
b) Description of the Related Art
It is known that the cover for an airbag in the dashboard of a motor vehicle can be designed as a separate flap with a hinge connection to the dashboard. This flap corresponds in appearance to a glove compartment door, but it is usually smaller, and it is opened from the inside when the propelling unit of the airbag is deployed. This flap is manufactured as a separate part. One problem here is that the decorative trim must be applied very carefully to the cover in a highly labor-intensive procedure, and it must be foamed to adhere well to it, so that parts of the airbag flap will not become detached in the explosive opening of the airbag and thus possibly injure the passenger. A disadvantage of designing the airbag flap as a separate part is the high cost of the individual flap and the difficulty of matching its color, finish and grain to the surrounding surface of the instrument panel.
There have been attempts to solve this problem by providing an integrated opening line for the airbag in the instrument panel without using a cover flap. The flap design here is achieved by punching or stamping the backing part out of sheet metal or by reducing the thickness of certain zones in the case of injection molded backings. When the propelling unit is deployed, the flap defined by the predetermined breaking line ruptures the foam and film enclosing the backing. To accomplish this, the thickness of the film must be reduced along the proposed tear line, namely by notches, cuts or grooves in the front and/or reverse sides.
If the thickness is reduced on the reverse side of the film, the result is an “invisible” airbag cover.
However, the technology for reducing the thickness of the film from its reverse side has not yet been developed to a mass production level. Attempts have been made in the past to achieve the reduction in thickness from the reverse side in the form of notching or grooving by using a laser, by producing a drawing cut or by stamping with a hot knife blade.
It may also be desirable for visual reasons to achieve a reduced thickness of the film from the visible side, i.e., from the grainy side. In this case, the predetermine breaking line in the form of a groove or notch serves to produce a visual effect. The predetermined breaking line is intentionally used here to distinctly emphasize the airbag flap by creating a shadow groove. Even with this method of creating a predetermined breaking line for an airbag flap, methods known in the past are labor-intensive and cost-intensive, because after manufacturing the actual film, the predetermined breaking lines must be created separately in the form of grooves or notches in the film using tools. This alters the grain and finish.
OBJECTS AND SUMMARY OF THE INVENTION
Therefore, the primary object of the present invention is to create a method of the type defined in the preamble, whereby a predetermined breaking line for an airbag flap is created in a single operation together with the creation of the film. Another object of the present invention is to create dashboards, door or side trim panels for motor vehicles from a slush membrane, where a predetermined breaking line for an airbag flap is produced.
These objects are achieved with a method of producing dashboard, door or side trim panels for motor vehicles with a predetermined breaking line for an airbag flap which comprises the steps of introducing slush material into a mold which can be heated to a molding temperature and which determines the shape of the slush membrane, distributing the slush material and depositing it on the heated mold surface by rotation of the mold, the distributed and deposited material being then sintered and gelled; after cooling the mold, removing the slush membrane from the mold by unmolding. To create the predetermined breaking line, a mold is used having a divider on its mold surface at the location of the predetermined breaking line to be created. The method further uses the step of controlling rotation and/or position of the mold during the application of the powder and/or gelation of the slush material. A reduction in layer thickness of the slush material to an extent that establishes a predetermined breaking line is achieved.
Further, in accordance with the invention, in a dashboard, door or side trim panels for motor vehicles made of a slush membrane, which is introduced into a mold that can be heated to the molding temperature and determines the shape of the slush material, which is distributed and deposited on the heated mold surface by rotating the mold, then is sintered and gelled and removed from the mold after cooling the mold, where a local reduction in the layer thickness of the slush material is achieved by means of a divider on the mold surface, an improvement comprises that the local reduction in layer thickness of the slush material is used as a predetermined breaking line for an airbag behind the dashboard, or side trim panels of the vehicle.
It has been found that a known slush method with additional modifications is suitable for achieving the objects proposed here, and slush membranes produced by this method having a local reduction in layer thickness of the slush material as the predetermined breaking line can be used for an airbag behind the dashboard, door or side trim panels.
In a method according to German Patent No. 4,029,254 C2, dividers are provided in a slush mold. With these dividers it is possible to achieve a reduced thickness in the membrane, which is sintered after a first slush process, so that a predetermined area of the membrane sintered initially can be separated from the remaining area there and then removed. In a second slush process using a powder of a different color, another membrane that is visible is formed in the removed area, and an invisible membrane is formed on the reverse side of the membrane sintered initially and left in the mold. This produces a sharp separation of two color areas of multi-colored slush membranes on the visible side.
With a two-colored slush membrane, the areas where the membrane sintered initially is visible are approximately twice as thick as the other areas. Due to the fact that another membrane is sintered onto the membrane sintered initially in the areas remaining in the mold, a curvature of the remaining membrane is formed at the dividers, although there is hardly any reduction in thickness. With the known method, the dividers serve to guide a parting-off tool which thermally separates the slush membrane by melting and thus makes it possible to remove the slush membrane in an area intended for a different color. The local reduction in thickness of the material due to the shaping effect of the divider is an unwanted side effect, but it was not necessary at all to achieve a mechanical reduction in thickness of the material to produce a predetermined breaking line because of the thermal separation of the areas.
In considering the possibilities for creating a predetermined breaking line, it has been found that the side effect derived from German Patent No. 4,029,254 C2 for producing areas of reduced material thickness by means of the known dividers can also be used in principle to create a defined predetermined breaking line for an airbag flap. To do so, it is necessary to produce a zone of reduced material thickness of the slush membrane through the design of the dividers and/or by the procedure during the entire slush process.
In a first embodiment of the invention, the height of the dividers is slightly smaller than the average thickness of the slush membrane. When the mold is rotated while the powder is being applied and/or during gelation, the slush material is distributed on the mold in such a way as to yield a mostly uniform flat surface on
André Walter
Kiesel Gerd Henning
Benecke Kaliko AG
Ortiz Angela
Reed Smith LLP
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