The present invention relates to an article with a wood appearance composite portion and a method for manufacturing the article with the composite portion.
It is often desirable to manufacture products that possess the look and feel of natural wood. Products with the look and feel of natural wood include vehicle components, such as steering wheels, instrumentation bezels, interior trim pieces, shift knobs, spoke covers, and other components with “Class A” surfaces that are visible in a motor vehicle. Manufacturing these components from natural wood can be costly because of the low availability of desirable natural wood material and generally cannot be accomplished with mass production techniques.
The present invention relates to a steering wheel that includes a steering wheel armature with a rim portion. A wood composite portion is formed by a wood composite material injection molded onto the rim portion. The wood composite material comprises a thermoplastic or thermoset plastic and/or a cellulose-based material in a resin matrix that can be pre-colored, if desired. The composite portion has an outer surface impregnated with the mold grain design. The design is configured to have a natural wood grain appearance. Alternatively, instead of the wood composite portion, a composite portion could be formed by a composite material, thermoplastic resin or thermoset resin without wood. Also, the composite portion could alternatively be formed by a composite material injection molded onto a spoke portion of the steering wheel.
The present invention also relates to an article forming a class A surface in a vehicle. The article includes a wood composite portion comprising a wood composite material. Alternatively, instead of the wood composite portion, a composite portion could be formed by a composite material without wood. A core portion is insert molded in the composite material. The composite portion has an outer surface with grooves that have been impregnated in through the molding process. The grooves are configured to resemble a natural wood grain. A coating portion comprises at least one layer of wood stain or base coat may comprise a vehicle component 20 with a surface 22 that is disposed on the outer surface of the composite portion. The composite material comprises a cellulose-based material in a percentage by weight such that the composite portion accepts wood stain or base coat. Alternatively, lower levels of cellulose based material can be used in conjunction with a pretreatment such as an adhesion promoter, fluorination, flame, or plasma treatment.
The present invention further relates to a method of manufacturing a steering wheel. The method includes the step of providing a mold having a mold cavity at least partially defined by an inner surface of the mold. The mold cavity is further defined by a wood grain design in the form of grooves on the inner surface of the mold. The method also includes the steps of providing a steering wheel armature and positioning the steering wheel armature in the mold cavity. The method further includes the step of injecting a wood composite material into the mold cavity and onto a rim or spoke portion of the steering wheel armature. The composite material comprises a cellulose-based material in a resin matrix. There is a wood grain design impregnated on an outer surface of the composite material in the configuration resembling a natural wood grain.
Further features of the present invention will become apparent to those skilled in the art to which the present invention relates from reading the following description of the invention with reference to the accompanying drawings, in which:
Referring to
According to the present invention, the article 10 may comprise a vehicle with a surface component 20 that is a class A surface in a vehicle (not shown). Referring to
The steering wheel 30 includes an armature 32 that comprises a rim portion 34 (shown partially in
Referring to
The skin 44 may be attached to the substrate 42 and may have any desired material construction. For example, the skin 44 may be a natural leather, such as a top grain leather or split grain leather. Optionally, the skin 44 may be a synthetic material, such as a synthetic leather. By “synthetic leather”, it is meant a material that is formed from a coated synthetic fabric or sheet material that simulates the appearance and feel of natural leather. Examples of synthetic leathers that can be used in accordance with the present invention are polymer-coated woven fabrics and polymer-coated non-woven fabrics. Portions of the skin 44 may be sewn together to help secure the skin to the steering wheel 30 and to further enhance the appearance of the steering wheel. Optionally, a padding material (not shown), such as a foam material, may be added between the substrate 42 and skin 44 to provide the steering wheel 30 with a soft feel. Alternatively, the skin 44 may be formed by a self-skinning foam, such as a self-skinning urethane foam.
In the embodiment illustrated in
Referring to
The material used to form the continuous portion 54 may, for example, comprise thermoplastic and thermosetting materials that may be readily molded onto the rim portion 34 and adhered to the rim portion 34 to resist twisting of the material. However, it should be noted that this material has adequate stiffness to resist twisting without being adhered to the rim portion 34. One material that may be used to form the continuous portion 54 of the composite material 52 is polypropylene. Other examples of materials that may form the continuous portion 54 of the composite material 52 include polyurethane, polyethylene, acrylonitrile-butadiene-styrene, polycarbonate, copolymers of polyethylene and polypropylene, and blends thereof. Other materials well known in the art can also be selected. The addition of wood pulp to the resin yields a composite “wood” wheel. Those skilled in the art will appreciate that it may be desirable to select virgin plastic or polymer materials to form the continuous portion 54.
The cellulose-based material forming the discontinuous portion 56 may comprise a woodmeal, sawdust or wood fiber. The composite material 52 may be provided in the form of resin pellets that include a mixture of the continuous and discontinuous portions 54 and 56, e.g., polypropylene and sawdust. The weight percentage of the discontinuous portion 54, i.e., the cellulose-based fiber material, may be from about 5 to about 75 percent by weight. It is only limited by the ability to injection mold the part. The weight percentage of the cellulose-based fiber material may be selected such that the composite material 52 accepts or absorbs wood stain or a base coat. For example, the weight percentage of the cellulose-based fiber material in the composite material 52 may be from about 50 to about 65 percent by weight.
Optionally, the composite material 52 can include additives to aid in the molding process. For example, coupling agents may be added to help bond the continuous and discontinuous portions 54 and 56 (e.g., the polypropylene and sawdust) of the composite material 52. Lubricants may be added to the composite material 52 to help improve its flow characteristics. Talc may be added to the composite material to help improve its water absorption characteristics. Other examples of additives include known additives for molding thermoplastic and thermosetting resins, such as, colorants, inorganic fillers, such as carbon black and titanium oxide, nucleating agents, such as calcium carbonate and magnesium carbonate, and stabilizers, such as light stabilizers, UV absorbents, Chlorinated polyolefins for enhanced adhesion, and flame retardants. These additives may be employed in amounts conventionally used in the art. The composite material 52 can also include reinforcing materials, such as fiberglass, fabric, or any other natural or synthetic fiber. Such reinforcing materials may serve to increase the strength of the composite material 52 and permit a reduction in the amount of composite material used to form the article 10.
One example of a product that may be used to form the composite portion 14 is JERTECH WPC 702, which is commercially available from J.E.R. Envirotech Ltd. of Delta, British Columbia, Canada. The exact composition of JERTECH WPC 702 is not known. It is, however, known that JERTECH WPC 702 has the following composition:
Wood Flour (Oak): 40-65% by weight
Filler: 0-5% by weight
Polypropylene Homopolymer: 30-60% by weight JERTECH WPC 702 material has a light wood color and a wood smell. Typical values for physical properties exhibited by JERtech™ WPC 702 are as follows:
Density: 1.07 g/cc
Bulk Density: 0.634 kg/liter
Hardness (Izod Impact-unnotched): 5.9 Kj/m2
MFI (Virgin PP): 35 g/10 min (per ASTM D-1238)
Moisture Content: 0.2% ±0.1%
Mechanical Properties
Tensile Modulus: 618,715 psi/4627 MPa (per ASTM D-638)
Stress at Break: 4959 psi/34.2 MPa (per ASTM D-638)
Strain at Break: 2.3% (per ASTM D-638)
Flexural Properties
Flexural Modulus: 551,870 psi/3806 MPa (per ASTM D-790)
Stress at Break: 8932 psi/61.6 MPa (per ASTM D-790)
Strain at Break: 2.7% (per ASTM D-790)
Another example of a product that may be used to form the composite portion 14 is JERTECH WPC 909, which is commercially available from J.E.R. Envirotech Ltd. of Delta, British Columbia, Canada. The exact composition of JERTECH WPC 909 is not known. It is, however, known that JERTECH WPC 909 has the following composition:
Wood Flour (Pine): 40-65% by weight
Modified Polypropylene: 1-5% by weight
Filler: 10-20% by weight
Polypropylene Homopolymer: 30-60% by weight
JERTECH WPC 909 material has a light wood color and a wood smell. Typical values for physical properties exhibited by JERtech™ WPC 909 are as follows:
Density: 1.07 g/cc
Bulk Density: 0.634 kg/liter
Hardness (Izod Impact-unnotched): 5.9 Kj/m2
MFI (Virgin PP): 35 g/10 min (per ASTM D-1238)
Moisture Content: 0.2% ±0.1%
Mechanical Properties
Tensile Modulus: 618,715 psi/4627 MPa (per ASTM D-638)
Stress at Break: 4959 psi/34.2 MPa (per ASTM D-638)
Strain at Break: 2.3% (per ASTM D-638)
Flexural Properties
Flexural Modulus: 551,870 psi/3806 MPa (per ASTM D-790)
Stress at Break: 8932 psi/61.6 MPa (per ASTM D-790)
Strain at Break: 2.7% (per ASTM D-790)
Yet another example of a product that may be used to form the composite portion 14 is known as FASAL F 347/0, which is commercially available from Fasal Wood KEG of Tulln, Austria. The exact composition of FASAL F 347/0 is not known. It is, however, known that FASAL F 347/0 is a wood fiber reinforced polypropylene homopolymer with a fiber content of 50% by weight. Typical values for physical properties exhibited by FASAL F 347/0 are as follows:
Density: 1.07 g/cc (per ISO 1183)
Impact Strength (Charpy): 5.95 Kj/m2 (per ISO 179)
Tensile Properties
Tensile Strength: 34.5 N/mm2 (per ISO 527)
Tensile Strain: 1.7% (per ISO 527)
Tensile E-modulus: 3750 N/mm2 (per ISO 527)
Flexural Properties
Flexural Strength: 54.7 N/mm2 (per ISO 178)
Flexural Strain: 2.5% (per ISO 178)
Flexural E-modulus: 3885 N/mm2 (per ISO 178)
Referring to
In the embodiment of
In the embodiment of
The isolator base coat 64 covers the entire outer surface 74 and wood grain impregnations 72 in the composite material 52. By wood grain “impregnations” in the composite material or a wood grain that is “impregnated” in the composite material, it is meant to refer to cavities, such as impressions, grooves, recesses, slots, or any other deformation in the composite material, configured and arranged so that the composite material resembles natural wood grain. The isolator base coat 64 may have any desired thickness and may be cured by air drying, thermal (heat) curing, or ultraviolet (UV) curing. As an example, the isolator base coat 64 may have a thickness of about 0.5 thousandths of an inch (mils) and may be UV cured.
The finish layers 80 also include first, a glaze coat 82 that completely or partially fills the wood grain impregnations 72 in the composite material 52. The glaze coat 82 may be formed, for example, with an alkyd, polyester, or polyurethane material. The glaze coat 82 may comprise a highly pigmented wood stain for helping to provide the desired color in the impregnated areas for the wood grain appearance portion 50. The glaze coat 82 may, for example, have a thickness of about 0.1-3.0 mils and may be thermal cured, UV cured, or air dried.
The glaze coat 82 may completely fill the wood grain impregnations 72. Alternatively, the glaze coat 82 may partially fill the wood grain impregnations 72 and the finish layers 80 may include a second glaze coat for contrast and depth of image. This alternative is shown in
The first glaze coat 82 and, if included, the second glaze coat 84, give the wood appearance portion 50 the desired stained wood tone. The composite material 52 and/or isolator base coat accepts or absorbs the stain or pigments in the glaze coat(s). This gives the portions of the glaze coat(s) on the surface 74 of the composite portion 14 a stained natural wood appearance. The portions of the glaze coat(s) that fill the wood grain impregnations 72 have a thickness that is greater than the portions of the glaze coats on the surface 74 of the composite portion 14. Typically, the glaze coat 82 is wiped off the surface 75. This highlights the wood grain 70, by providing a darkened appearance similar to that achieved with the wood grain of natural wood when a pigment or stain is applied.
The finish layers 80 may also include another isolator and/or build coat 86 disposed after the glaze coat 82. The isolator and/or build coat 86 is clear or dyed and may be made of the same materials as the isolator coat 64. This coat may also contain pearlescent pigments, mica and small levels of metallic pigments. The isolator coat 86 may, for example, have a thickness of about 0.5-1.0 mils and may be thermal cured, UV cured, or air dried. It may be tinted or clear and can contain pearlescent pigments.
The finish layers 80 may also include another clear isolator coat 90 disposed on the second glaze coat 84. The isolator coat 90 may, for example, have a thickness of about 0.5 mils and may be thermal cured. This coat may also contain pearlescent pigments, mica and small levels of metallic pigments.
The finish layers 80 may also include one or more clear or tinted coats 92. This coat may also contain pearlescent pigments, mica and small levels of metallic pigments.
In the illustrated embodiment, there are two clear coats 92. The clear coats 92 may, for example, be formed from a polyester, urethane, or other suitable material, having a thicknesses of about 3.0-7.5 mils, and may be thermal cured, UV cured, or air dried. More particularly, the first applied clear coat 92 may be partially UV cured (“gel cured”) and, after the second clear coat is applied, both clear coats may be fully UV cured.
The finish layers 80 may further include one or more high-gloss clear or tinted coats 94. In the illustrated embodiment, there are two top coats 94. As an example, the top coats 94 may be formed from a polyurethane, polyester, or other suitable material, and have thicknesses of about 1.0-3.0 mils, and may be UV cured, thermal cured, or air dried. More particularly, the first applied top coat 94 may be partially UV cured (“gel cured”) and, after the second top coat is applied, both top coats may be fully UV cured. After the clear coat 94 has dried, buffing may be desirable.
To manufacture the steering wheel 30, the substrate 42 and the composite material 52 are molded on the armature 32.
Referring to
The steering wheel armature 32 on which the substrate 42 has been molded is then placed into a second mold 140 to mold the composite material 52 onto the rim portion 34 of the armature 32. As shown in
Referring to
The mold 140 also includes hard seals 160 and 162 at opposite ends of the mold space 148. The seals 160 and 162 isolate the heated melt from the substrate 42. The mold 140 further includes an aperture 164 (
Referring to
The sprue gate directs the heated melt from the injection molding machine 110 into the mold cavity 118 and should be located on a non class A surface. The heated melt fills the mold space 148 and surrounds the arcuate segment 58 of the rim portion 34. The melt is then cooled and the steering wheel armature 32, on which the composite material 52 has been molded, is removed from the mold 140.
The finish layers 80 are then applied to the outer surface 74 of the composite material 52 in a conventional manner. For example, the finish layers 80 of the embodiment illustrated in
From the above description of the invention, those skilled in the art will perceive improvements, changes and modifications. For example, the steering wheel, spokes, or composite article could be formed by a two shot co-injection molding process using just one injection molding apparatus. Such improvements, changes, and modifications within the skill of the art are intended to be covered by the appended claims.