Patent Application
20120025566
The present invention relates generally to the interior of vehicles and their method of manufacture, and more particularly, to interior panels of a vehicle, such as may be disposed on a door, dashboard, seat, ceiling, sidewall, instrument panel, center console and other trim panels.
Automobile interiors typically have a decorative skin, such as fabric or leather, with an underlying support structure or substrate. Interposed between the skin and substrate is typically a cloth or mesh spacer to provide added softness to the decorative skin. A significant drawback of the cloth or mesh spacer is that it is too weak to maintain its shape if parts are cut out, for example, for various profiles. Because of this drawback, designers have limited aesthetic and functional design options available. For example, sharp edges or small radii in panels are avoided because the relatively weak cloth or mesh at corners becomes misshaped and compressed. Also, because of the compression, a panel using cloth spacers and having small radii exhibits a harder and less desirable feel.
The current trend for many luxury vehicles is to pressure bond a thick leather skin with a spacer material to the instrument panel. This bonding process presents several drawbacks, including difficulties in bonding leather to the spacer material or to the carrier and aesthetic problems such as lack of smoothness and uniformity. The scrap rate is very high and costly. Furthermore, since a decorative skin made of a thick leather sheet, typically from 1.0 to 1.5 mm in thickness, does not allow the deployment of an airbag unless the decorative skin is weakened, a score line is often employed. However, when the decorative skin is scored, a witness line, known as “read-through,” can be observed opposite the side that was weakened, resulting in non-desirable aesthetics.
The spacer material that is typically used also presents several problems. Standard spacer materials typically have a tear strength greater than 70N (ISO 13937-2) and may be as high as 500N (ISO 13937-2), and are difficult to laser score due to non-homogeneity of the material. Moreover, the typical materials used cause surface defects and a high scrap rate.
It is also problematic to bond thin leather skin alone to the entire surface of the instrument panel, since doing so results in all surface defects from dust, adhesive, etc. showing through the thin leather skin. Adding a typical spacer fabric would require the laser scoring of the carrier and spacer fabric. The result would be undesirable “A” surface read-through from the weakening.
Thus there is a need for improved leather wrap materials and a method to improve perceived quality and reduce total cost of the bonding a soft leather to an instrument panel.
In accordance with aspects of the present invention, a self-tearing interior wrap for vehicles and methods of manufacture are disclosed. The self-tearing interior wrap is especially suited for use as a decorative trim panel, such as may be disposed on a door, dashboard, seat, ceiling, sidewall, instrument panel, center console, etc., in passenger automobiles and trucks.
In accordance with one embodiment, a self-tearing wrap material includes a thin skin and a soft foam material of specified dimensions, wherein neither the skin nor the foam material is weakened, such as is commonly achieved by scoring or the like. Skin thickness is less than 1.0 mm and may range from about 0.3 mm to 0.9, more preferably from about 0.3 mm to 0.55 mm, and most preferably about 0.4 mm. Skin of such thickness can be considered and is defined herein as “self-tearing”.
In one embodiment, a soft foam material, which may be an open or closed cell foam, having a tear strength of about 9N to about 32N according to JIS K6767, elongation of 200% to 450% (JIS K6767), density of 2 to 6 lb./cu. ft. (JIS K6767), and thickness of 1.0 mm to 4.0 mm (JIS K6767), is employed. In one embodiment the foam is a polypropylene foam. It will be apparent to a skilled artisan that any suitable foam may be employed, such as polyurethane, PVC foam and the like. The foam preferably permits hand wrapping of the perimeter and corners.
The combination of thin skin and foam having the aforementioned characteristics provides a self-tearing wrap for an instrument panel whereby only the substrate carrier needs to be scored for seamless airbag deployments.
This wrap may be advantageously cut and sewn to any desirable width and length. The foam layer may be skived to hold virtually any desirable profile. The wrap is preferably wrapped onto a substrate and adhered by an adhesive, the substrate typically being made of plastic. This wrap is then incorporated into a vehicle as a panel or trim. The panel may also have a protective airbag affixed thereto. Surprisingly, the self-tearing skin and foam layer provide an aesthetically acceptable wrap without the need for weakening the wrap when used in conjunction with a pre-weakened substrate for facilitating airbag deployment.
Methods of producing a self-tearing wrap for an interior trim panel are also disclosed in further aspects of the invention. One such method commences with receiving a thin outer leather skin having a thickness of less than 1.0 mm and a foam layer having a thickness of about 4.0 mm or less. The outer skin which may be leather is adhered to the foam layer and the foam layer is skived to suit a desired profile. It can be appreciated that the foam layer and/or the leather skin can also be skived prior to adhering it to the outer skin. Based on measurements associated with a selected profile, a skiving machine with an appropriate blade is employed for this procedure. The bilaminate wrap is not weakened before it is applied to the substrate.
Another aspect relates to a method of manufacturing an interior trim panel employing the self-tearing wrap. The method comprises receiving a substrate and a self-tearing wrap material, applying adhesives and adhering the wrap to the substrate. The wrap comprises a foam layer that is skived into a desired profile based on measurements related to the profile. For example, the foam layer can be skived to a thickness that matches an area interposed between the thin outer skin and the substrate. As the foam layer is made up of a non-porous material it can hold a shape regardless of the thickness of the material removed from it due to skiving. The substrate is weakened to facilitate airbag deployment. The self-tearing leather skin/soft foam wrap, which is not scored, is bonded to the weakened substrate for a vehicle instrument panel to facilitate deployment of airbags while mitigating the appearance of read through on the A-surface. It will be appreciated that in accordance with this embodiment only the substrate carrier would require weakening for seamless airbag deployment.
The foregoing embodiments provide a soft leather skin with high perceived quality through superior tactile feel when pressed upon. The thinner the leather, the greater the improvement in touch and feel softness, due to the greater effect on feel of the foam. The foregoing embodiments eliminate scoring of the skin and/or foam. In addition, there is realized a lower cost weakening method for the carrier substrate.
In the following description, for purposes of explanation, specific numbers, materials and configurations are set forth to provide a thorough understanding of the invention. It will be apparent to one having ordinary skill in the art that the invention may be practiced without these specific details. In some instances, well-known features may be omitted or simplified so as not to obscure the present invention.
Turning now to the drawings,
The foam layer 24 can comprise an open or closed-cell, non-porous foam structure, which results in a less absorbent, firmer material that may permit skiving various profiles therein. In one embodiment, the foam layer 24 has a tear strength of about 9N to about 32N according to JIS K6767, elongation of 200% to 450% (JIS K6767) and density of 2 to 6 lb./cu. ft. (JIS K6767). Foam layer 24 having the aforementioned properties at the thicknesses disclosed herein may be considered self-tearing. Foam having the foregoing properties is commercially available from Toray Plastics of Front Royal, Va. In one embodiment the foam layer 24 comprises a polypropylene foam having the aforementioned properties. It will be apparent to a skilled artisan that any suitable foam may be employed, such as polyurethane, PVC foam and the like. The thickness of the foam layer 24 may range from about 1.0 mm to about 4.0 mm, more preferably from about 2.0 mm to 3.5 mm, and most preferably from about 2.5 mm to 3.0 mm.
It will be apparent to those having skill in the art that the self-tearing interior wrap 20 may include multiple foam layers 24, which may be of the same or different type.
The total thickness of the self-tearing interior wrap may be from about 1.3 mm to less than about 5.0 mm, more preferably from about 2.3 mm to about 4.05 mm, and most preferably from about 2.9 mm to about 3.4 mm. Leather of the foregoing thicknesses is obtainable using a leather splitting machine as is known in the art. Such leather may also be obtained commercially from Spinneybeck of Getzville, N.Y.
The thin skin 22 of embodiments of the present disclosure facilitates eliminating the need to weaken the skin 22 and/or foam layer 24, for example, for a stress concentrator providing a path for the initiation and propagation of a tear when used in conjunction with a protective airbag. Improved aesthetics result because no read-through witness lines can be observed on the resultant decorative trim or panel. Other advantages include that topcoats and other surface treatments may be used on the skin 22 to provide greater tactile and aesthetic characteristics.
Another design advantage made possible through aspects of the present disclosure is that the foam layer 24 can comprise a closed-cell or non-porous structure, which results in a less absorbent material. This permits the use of less adhesive when wrapping the self-tearing interior wrap 20 to the substrate 30 during manufacturing. A further advantage is realized in that less material is used in making the presently disclosed bilaminate thin leather wrap. Moreover, because no score lines are required, significant process efficiencies are realized due to reduced tooling and processing. In sum, embodiments of the present disclosure provide a cost-effective alternative to standard leather wrap materials.
In accordance with one aspect of the present disclosure, the foam layer 24 can be skived to any desirable profile while maintaining its shape and strength. In a further aspect, the measurements of the profile to be skived into the foam layer 24 can be obtained and the foam layer 24 can be skived in accordance with such measurements. Various profiles in the foam layer 24 can be obtained by using different blades on a skiving/milling machine.
Various contours can be milled/skived into the foam using different blades on the skiving machine. For example, if the outer skin is received as a roll at step 202, different templates can be cut from the resulting bilaminate and sewn together to fit a desired part. If various templates of the outer skin are received at step 202, they may be sewn together after skiving the foam at 212 so that the resulting sewn pieces maintain a uniform profile. In such case, the foam can be partially skived with gradually varying thickness from an outer edge to the inner surface. The leather skin material permits thin constructions and the use of skiving to incorporate various profiles of variable thicknesses into the panels, resulting in reduced manufacturing costs, an increase in the amount of design possibilities, more attractive aesthetics and improved tactile characteristics.
It will be noted that the self-tearing interior wrap obtained from various procedures detailed herein can be cut and sewn with other materials, bilaminates, or other structures, for example, compact sheet materials, to form integrated interior panels, with or without skiving of the foam layer. It is important to note that the foregoing steps for different procedures detailed herein do not recite the use of a scoring or weakening process on the self-tearing interior wrap but rather only the substrate material, which is weakened to facilitate ejection of the airbags.
Although preferred embodiments of the invention are disclosed for illustrative purposes, those skilled in the art will appreciate that many additions, modifications, and substitutions are possible without departing from the scope and spirit of the invention.
