# Patent

## Title
Method for stitching vehicle interior components and components formed from the method

## Abstract

A method of applying stitching to an interior component is provided herein. The method including the steps of: a) penetrating an outer skin layer, a substrate layer and an intermediary layer of the interior component with an awl to form a piercing therethrough; b) retracting the awl from the outer skin layer, the substrate layer and the intermediary layer; c) inserting a needle through the piercing through the substrate layer, the intermediary layer and the outer skin layer to grasp a thread positioned on the outer skin layer; d) pulling the thread through the outer skin layer, the intermediary layer and the substrate layer; e) looping the thread with a previous stitch passed through the outer skin layer, the intermediary layer and the substrate layer; f) advancing the interior component to another position; and g) repeating steps a-f until a predetermined amount of stitches are applied to the interior component.

## Background
CROSS REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of U.S. Provisional Application Ser. No. 61/505,833, filed Jul. 8, 2011, the contents of which are incorporated herein by reference thereto.


BACKGROUND
This invention relates to an interior structure for a vehicle interior. More particularly, the invention relates to an apparatus for stitching vehicle interior components.
Currently, most stitching found in an automotive interior is of the functional variety, wherein two or more pieces of material (leather, vinyl, TPO, cloth, etc) are cut from a pattern and sewn together (cut-n-sew) prior to being wrapped around a component such as a seat cushion, head rest, arm rest, console lid, instrument panel substrate, etc. Such functional stitching is very labor intensive and is normally used only where required on low and mid-class vehicles. Functional stitching on decorate components such as instrument panel retainers and door panels has typically been restricted to higher class vehicles due to cost.
In recent years, automotive original equipment manufacturers (OEMs) have shown an interest in applying the “stitched” look to more vehicles over a wider range of price classes. A simulated non-functional stitch has been used in some applications; however, the ability to offer a simulated stitch in a contrasting color is not production feasible at this time. Additionally, more OEMs are requested that a real or “live” stitch be used on decorate components to provide the look and feel of a true cut-n-sew component.
Accordingly, it is desirable to provide a live, non-functional stitch on decorative automotive trim components.
SUMMARY OF THE INVENTION
A method of applying stitching to an interior component, comprising an outer skin layer, a substrate layer and an intermediary layer located between the outer skin layer and the substrate layer is provided. The method including the steps of: a) penetrating the outer skin layer, the substrate layer and the intermediary layer with an awl to form a piercing therethrough; b) retracting the awl from the outer skin layer, the substrate layer and the intermediary layer; c) inserting a needle through the piercing through the substrate layer, the intermediary layer and the outer skin layer to grasp a thread positioned on the outer skin layer; d) pulling the thread through the outer skin layer, the intermediary layer and the substrate layer; e) looping the thread with a previous stitch passed through the outer skin layer, the intermediary layer and the substrate layer; f) advancing the interior component to another position; and g) repeating steps a-f until a predetermined amount of stitches are applied to the interior component.
Also provided herein is an interior component of a vehicle formed by the above method.



BRIEF DESCRIPTION OF THE DRAWINGS
Other features, advantages and details appear, by way of example only, in the following description of embodiments, the description referring to the drawings in which:
FIG. 1 is a cross-sectional view of an interior portion of a component stitched in accordance with an exemplary embodiment of the present invention; and
FIG. 2 is a flow chart illustrating a method according to one exemplary embodiment of the present invention.



DETAILED DESCRIPTION
Turning now to the drawings, wherein to the extent possible like reference numerals are utilized to designate like components throughout the various views, in FIG. 1 it is seen that an interior portion 16 of a vehicle is illustrated. In one implementation interior portion 16 is a portion of an instrument panel of a vehicle.
As best illustrated in FIG. 1, the interior portion 16 is preferably of a multi-layered construction. This multi-layered construction preferably includes an outer skin layer 18 having a substantially smooth outer surface and an underside facing away from the outer surface. The outer skin layer 18 is preferably formed of a plastic material of substantial flexibility and aesthetically pleasing character.
In order to enhance the softness of portion 16, a layer of cushioning support material 20 is provided in the region below the outer skin layer 18. It is contemplated that the cushioning support material 20 may be of any number of different constructions although a foamed material such as cross linked polypropylene (XLPP) foam may be potentially preferred. A substrate panel 22 of dimensionally stable plastic or other suitable material is preferably disposed below the cushioning support material.
According to the potentially preferred embodiment, the cushioning support material 20 and the substrate panel 22 thus serve cooperatively to provide a support structure for the outer skin layer 18.
It is contemplated that XLPP foam forming the cushioning support material 20 may be blown between the outer skin layer 18 and the substrate panel 22 so as to form a multi-layered composite structure of a form substantially as illustrated in FIG. 1. It is also contemplated that the cushioning material 20 may be attached to the outer skin layer 18 in a preliminary cladding operation so as to form a preliminary layered composite which may thereafter be applied across any substrate panel 22 as may be utilized.
In accordance with an exemplary embodiment of the present invention live non-functional stitching can be applied interior portion in one of the following ways:
1) Stitch a pattern on an unformed single or multilayer construction of trim material and wrap the sewn trim sheet around a preformed/precut substrate;
2) Stitch a pattern on a preformed single or multilayer construction of trim material and bond the sewn trim preform to a preformed molded substrate; and
3) Stitch a pattern on a flat or relatively flat single or multilayer trim & substrate component construction.
As the part complexity and size increase, option 1 becomes impractical as unformed trim material can only be applied to relatively flat surfaces.
Option 2 requires that the size and shape of the preformed & stitched skin match that of the molded substrate nearly perfect. Also, option 2 requires that all surfaces in die draw have adequate draft in order to accommodate nesting without damage to the preform. All undercuts with Option 2 require automated or manual edge wrapping to finish.
Option 3 eliminates the fit and finish issues associated with option 2 but is limited by the ability of the sewing machine to reach confined areas of the part while possessing the capability to drive a needle through trim and substrate material of the component. Likewise, any backside features (ribbing, bosses, etc.) required for component structure or attachment cannot be located in the area directly behind/beneath the stitch path.
This application proposes a means to stitch through trim and substrate of a large, contoured soft trim clad automotive interior trim panel to eliminate the manufacturing cost and complexity associated with Option 2 above and be designed and manufactured in such a way that the stitching can be located directly above backside features if required.
Various exemplary embodiments of the invention described herein consists of the use of a chain stitch pattern machine that uses an awl on the upper portion of the head to penetrate the trim and substrate of the interior component. After the awl exits a hole 24 it produced in the component, a needle with a hook protrudes into and through the hole 24 from the lower arm of the machine to grasp the thread held in position by a thread tensioner arm. Once hooked, the thread is pulled through the hole and through the loop from the previous stitch. The needle also advances the part to the next point of awl penetration as it pulls the thread down through the hole 24. The needle then advances to the hook position once again while the awl is engaged with the part so the part does not move and needle can move through the newly formed hole without hesitation once the awl exits the part.
By utilizing an awl to produce the stitch hole, much more robust material constructions can be stitched (composites, metals, etc) with minimal damage to the top surface of the part or the awl. Damage to the thread is minimized by the fact that the thread is not pulled back and forth through the hole multiple times as is the case with the lockstitch pattern. Very large tex threads can be used without concern for needle breakage.
The post bed stitch plate for such a chain stitch machine as described above can be a small as 10 mm×15 mm, a significant reduction from previous robotic chain stitch plate dimension of 16 mm×44 mm (of course, dimensions greater or less than these are considered to be within the scope of exemplary embodiments of the present invention). Access to very tight confines of parts is now possible, particularly through-plane radii wherein minimizing stitch plate length is critical.
The optimal machine configuration for sewing trim/substrate constructions in a manual fashion would be a high post, long arm machine. Manual or fixture guided part feed would be required.
The optimal machine configuration for robotic sewing would be dependent on the part design. The key factor again is the compact size to the stitch plate. Cylinder arm length and post bed height would depend on the application.
To facilitate the stitch location on the part, it is proposed that the backside or ISM side of the retainer be free and clear of any multiplane style line, ribs, bosses or any other obstruction that would prevent passage/contact of the stitch plate along the backside of the part for the entire stitch length. In the event that a backside feature cannot be moved from the stitch path, it is proposed that a separate component be molded which contains said feature and be subsequently attached the substrate after stitching. This secondary attachment could be performed via heat staking, IR welding, adhesives, or any other suitable method.
It is also proposed that the substrate material be locally reduced to a thickness more suitable for stitching should the need arise. For instance, a part with a nominal wall thickness of 2.5 mm could locally be reduced to 1.5 or 2.0 mm at a width of 15 to 20 mm along the stitch path. This depression in the backside of the part would also serve to locate a separate piece containing ribs or bosses as needed prior to attachment. Compression molding of the substrate panel could accommodate a reduction in nominal wall thickness from 2.0 mm to 1-1.5 mm in the stitching area. Of course, dimensions greater or less than the aforementioned values are considered to be within the scope of exemplary embodiments of the present invention.
Referring now to FIG. 2 a flow chart 30 illustrating a method of applying stitching to an interior component according to one exemplary embodiment of the present invention is provided. Here the interior component has an outer skin layer, a substrate layer and an intermediary layer located between the outer skin layer and the substrate layer.
At box 32, the outer skin layer, the substrate layer and the intermediary layer are penetrated with an awl to form a piercing therethrough. At box 34, the awl is retracted after the piercing is formed.
Thereafter and at box 36, a needle is inserted through the piercing (e.g., through the substrate layer, the intermediary layer and the outer skin layer) to grasp a thread positioned on the outer skin layer. Once the step of box 36 is completed, the thread is pulled through the outer skin layer, the intermediary layer and the substrate layer at box 38.
Afterwards and at box 40, the thread is looped with a previous stitch passed through the outer skin layer, the intermediary layer and the substrate layer, unless of course this is the first stitch. Once the step of box 40 is completed, the interior component is advanced or moved to another position relative to the awl and needle at box 42 and then the processes or steps of boxes 32-42 are repeated until a predetermined amount of stitches are applied to the interior component.
While the invention has been described with reference to an exemplary embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the present application.

## Claims

1. A method of applying stitching to an interior component, comprising an outer skin layer, a substrate layer and an intermediary layer located between the outer skin layer and the substrate layer, the method comprising:
a) penetrating the outer skin layer, the substrate layer and the intermediary layer with an awl to form a piercing therethrough;
b) retracting the awl from the outer skin layer, the substrate layer and the intermediary layer;
c) inserting a needle through the piercing through the substrate layer, the intermediary layer and the outer skin layer to grasp a thread positioned on the outer skin layer;
d) pulling the thread through the outer skin layer, the intermediary layer and the substrate layer;
e) looping the thread with a previous stitch passed through the outer skin layer, the intermediary layer and the substrate layer;
f) advancing the interior component to another position; and
g) repeating steps a-f until a predetermined amount of stitches are applied to the interior component.

2. The method as in claim 1, wherein outer skin layer, is formed from the group consisting of vinyl, leather and thermoplastic polyolefin; and the intermediary layer is a foam and the substrate layer is formed from plastic.

3. An interior component formed by the method of claim 2, wherein the interior component is an interior trim piece of a vehicle.

4. The interior component of claim 3, wherein the interior trim piece is a portion of an instrument panel of the vehicle.

5. An interior component formed by the method of claim 1, wherein the interior component is an interior trim piece of a vehicle.

6. The interior component of claim 5, wherein the interior trim piece is a portion of an instrument panel of the vehicle.

7. The method as in claim 1, wherein outer skin layer, is formed from leather and the intermediary layer is foam and the substrate layer is formed from plastic.