Patent Application
20110210596
The present disclosure relates generally to the field of seating for vehicles. More specifically, this disclosure relates to one-piece seat structures and processes using cold forming to create seat structures.
Seat structures (e.g., seat back frames, seat base cushion frames, low seat structures, back frame seat belt towers, etc.) can provide strength to a seat assembly to meet strength and/or durability requirements that are commonly covered by governmental regulations (e.g., FMVSS, ECE) or suggested and/or dictated by other groups (e.g., by vehicle manufacturers, insurance groups, etc.). Seat structures also can be configured to meet the desires of customers (and hence vehicle manufacturers) for seat assemblies that provide increased functionality or utility (e.g., rotating, folding, sliding, etc.) while improving user-adjustable comfort. Achieving the desired material, structural, functional, and utility characteristics (e.g., strength, stiffness, thickness, microstructure, stress, strain, durability, etc.) typically requires the use of additional components, which can have an undesirable impact on mass, cost, and comfort. Seat structures are typically designed by balancing structural and functional characteristics against mass, comfort, and cost.
Generally, it is known to construct a seat structure by separately forming individual members using a conventional stamping process (e.g., a multiple station progressive stamping die), and then coupling those formed members, e.g., using a welding (e.g., laser, GMAW) process or the like to couple the formed members. This method of construction has several disadvantages, at least some of which are as follows. First, the welding process for joining formed components, especially laser welding, requires tight tolerances with respect to parameters (e.g., gap) to produce a reliable structural weld, which can require complex and expensive fixtures or tooling during the manufacturing cycle. Second, concerns about reduced reliability resulting from the tight tolerances may cause manufacturers to couple the members with redundant welds to increase reliability, which adds to piece cost and cycle time of manufacture. Third, individual stamping dies or tooling may be required to produce each individual member, which adds to piece cost and maintenance cost. Fourth, a higher number of individual members used to construct a seat structure results in a higher likelihood that the lack of one member will stop the entire production process of a seat structure. Fifth, this method of construction requires significant part handling downstream in the manufacture process, which adds to the piece cost. Sixth, this method of construction can inhibit optimization of mass and strength, as the desire to reduce costs by having as few parts as possible in the assembly can cause manufacturers to structurally overdesign portions of the seat structure to achieve part reduction. Seventh, some conventional methods of coupling (e.g., GMAW, fasteners) require overlaps and/or the addition of material, such as extra parts or filler material, which negatively impacts mass and cost. Eighth, the coupling of multiple individual stamped members typically requires a significant number of welds, for example, a conventional four member back frame structure may require more than twenty welds to couple the members into one assembly. The need for this high quantity of welds in combination with conventional weld fixtures (e.g., a rotating carousel fixture) result in slow manufacturing cycle times.
There is a need to design and form structural components with reduced mass and reduced cost, while meeting or exceeding increased strength and durability requirements. Additionally, because the structural components of a seat assembly of a vehicle provide safety related functionality, there is always a need to increase reliability of the processes and components that are in the load path during a dynamic vehicle impact event. There also is a need for additional functionality with a minimal impact on comfort, mass, and cost. Additionally, the cost to handle or modify the component increases significantly as a product moves downstream in its manufacturing cycle, hence there is a desire to reduce or eliminate downstream operations.
A one-piece seat structure for use in a vehicle seat assembly, the one-piece seat structure comprising: a first portion having a first set of material, structural, functional, and utility characteristics (e.g., strength, stiffness, thickness, microstructure, stress, strain, durability, etc.); a second portion having a second set of material, structural, functional, and utility characteristics (e.g., strength, stiffness, thickness, microstructure, stress, strain, durability, etc.); wherein the first set of material characteristics differs from the second set of material characteristics; and wherein the one-piece seat structure is formed from a tailor welded blank using a cold-forming process, the tailor welded blank constructed from the first portion coupled to the second portion. The number of different portions with different characteristics can vary and will go from two to multiple portions. Also, the one-piece seat structure may be formed from a monolithic blank (uniform material property and thickness) using a cold-forming process. The needed structural performances are achieved via specific topography (stiffeners geometry) obtained within the forming of the one-piece structure. Also, the one-piece seat structure can be formed from a blank partially or entirely made (or formed) from a heat treatable material. In this embodiment, the one-piece structure will be first formed using a cold-forming process and then needed structural performances will be obtained by applying some of the post cold-forming heat treatment processes to the seat structure.
In one exemplary embodiment, a vehicle seat assembly includes a seat back rotatably coupled to a seat base; wherein at least one of the seat base and seat back comprises a one-piece structure comprised of: a first portion having a first set of characteristics and a second portion having a second set of characteristics, wherein the first set of characteristics differs from the second set of characteristics; and wherein the one-piece seat structure is formed from a tailor welded blank and a monolithic blank using a cold-forming process, the tailor welded blank constructed from the first portion coupled to the second portion.
A method of forming a one-piece seat structure, the method comprising the steps of: constructing a tailor welded blank by coupling a first portion having a first set of characteristics to a second portion having a second set of characteristics, wherein the first set of characteristics differs from the second set of characteristics or a monolithic blank; and forming the one-piece seat structure from a tailor welded blank or monolithic blank using a cold-forming process.
Referring generally to the FIGURES, there are disclosed one-piece seat structures 5 for use within a seat assembly 12 for use in a motor vehicle 10 and processes for forming the seat structures 5. Based on the present disclosure, a one-piece seat structure 5 can be configured to achieve, for example, desired strength, durability, functionality, utility, mass, cost, and/or user comfort characteristics.
A tailored welded blank 16 formed in accordance with the present invention offers the ability to, for example, integrate components, minimize scrap, reduce handling, reduce cost and optimize strength and mass. For example, mass and cost can be optimized by flexibly optimizing the material (i.e., mechanical properties) and thickness at differing sections of a tailored welded blank 16 to meet requirements of strength and manufacturing. The tailored welded blank 16 can then be formed through a cold-forming process to produce a one-piece structural component 5, which may have complex geometry yet require fewer secondary operations and less expensive fixtures or tooling. The one-piece seat structure 5 can be optimized for cost and mass, which meets or exceeds strength and durability requirements and the strength and durability of conventional seat structures. Also, this optimization of mass can allow for construction of a smaller seat 12, which in turn can provide increased space within the vehicle 10 for cargo or comfort. The mass reduction of seat components can have a ripple effect for vehicle manufacturers, as mass reduction affects the design of other components (e.g., brakes, powertrain) and can allow for other components that are lower mass, smaller, more efficient, etc., which can lead to other cost savings in the vehicle 10.
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The tailored welded blank 16 can be constructed by coupling the portions 42 directly into the shape of the blank 16 by using any of various suitable techniques. For example, the portions 42 can be obtained by cutting sections 54 of desired size and shape from one coil of sheet material 46 or from multiple coils of sheet material 46 (e.g., wherein the properties of the sheet material are uniform on each given coil, but differ from one coil to the next). The portions cut 54 from the coil(s) 46 then can be positioned in a desired configuration and coupled together to form the tailored welded blank 16, which will then be shaped using the cold-forming process 50. Tailored welded blanks 16 can be configured in a variety of ways by, for example, varying the shape, size, quantity, material, and thickness of the portions 54, as well as varying the relative positions of different portions prior to coupling.
Alternatively, the portions cut from the coil(s) 54 (e.g., portions made from different materials with different material thicknesses) can be coupled together (e.g., laser welded) and then rolled again into a single coil of steel to form a tailored welded coil 56 having material of different properties along its width. The tailored welded coil 56 can then be partially unrolled, a section 58 cut therefrom, and the section 58 can be trimmed by any appropriate (including conventional) means to form an entire tailored welded blank 16. As another alternative, sections 58 can be cut from the tailored welded coil 56 (and possibly other coils), and those sections 58 can then be positioned in a desired configuration and coupled together to form the tailored welded blank 16, which will then be shaped using the cold-forming process 50. Another alternative would be to continuously feed a tailored welded coil 56 directly into a die 60 (e.g., progressive, transfer) to form a tailored component 62. Blanks 16 formed from tailored welded coils 56 can be configured in a variety of ways by, for example, varying the coil 56 strip widths, varying the shape, size, quantity, material, and/or thickness of the portions 42, as well as varying the relative position of different portions 42 prior to coupling.
The portions 42 that are coupled to form the tailored welded blank 16 (or to form the tailored welded coil 56 that ultimately becomes the tailored welded blank 16) can have different characteristics. For example, the portions 42 may be made from different materials and/or they may have different thicknesses. Tailored welded blanks 16 are flexible in regard to varying the properties (e.g., blank size, shape, mechanical properties, thickness, etc.) of the different portions 42 to be coupled, which optimizes the mass and structural characteristics of the one-piece structure 5 by allowing each portion 42 to be designed to meet a specific strength. Tailored welded blanks 16 reduce part cost by minimizing scrap through more efficient nesting of the portions 42, and tooling cost by requiring simpler and/or less tooling, than conventional seat structures, to achieve reliable welds. The tooling of tailored welded blanks 16 may be simpler and less expensive, because the blanks 16 being coupled are not formed prior to coupling, thus have more dimensionally stable coupling features which allows for less complex (less expensive) fixtures to achieve the necessary joining (e.g., weld, etc.) parameters (e.g., gap, etc.) to produce a reliable weld. This increase in weld reliability also allows for the reduction of redundant welds, which further reduces cost and cycle time. The more mass-optimized tailored welded blank 16 may be cold formed (i.e., pressed between tooling at conventional ambient temperature) to form a mass and cost optimized one-piece seat structure 5. The one-piece seat structure 5 requires fewer (than conventional structures) if any secondary operations, as the tooling may produce complex geometry, which significantly reduces the handling as compared to conventional structures.
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The multiple portions (P1 through P6) 64, 66, 68, 70, 72, 74 are coupled through a conventional process (e.g.; laser welding, etc.) into a tailored welded blank 16 prior to forming. The simple geometry of each portion improves weld reliability, by having more dimensionally stable weld features (e.g., gap, etc.), and decreases tooling cost, by allowing for less complex tooling which would be required to compensate for a less dimensionally stable part. The conventional method of coupling components post forming drives this dimensional instability and requires more expensive fixtures to assure reliable welds. The increased weld reliability of tailored welded blanks 16 allows for the elimination of redundant welds, which are required on conventional structures due to the less reliable welds. An exemplary tailored welded blank 16 comprising of six portions may be coupled with six welds, while another embodiment of a tailored welded blank 16 comprising of four portions may be coupled with four welds, which is a significant improvement over conventional four member back frame that could have more than twenty welds. The tailored welded blank 16 also has an improved nesting, which reduces scrap and cost.
According to other embodiments, the number, position, and configuration of respective portions 42, as well as the properties (e.g., mechanical, thickness) of the respective portions 42, may be varied to, for example, satisfy specific design requirements (e.g., cost, mass, strength).
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As utilized herein, the terms “approximately,” “about,” “substantially”, and similar terms are intended to have a broad meaning in harmony with the common and accepted usage by those of ordinary skill in the art to which the subject matter of this disclosure pertains. It should be understood by those of skill in the art who review this disclosure that these terms are intended to allow a description of certain features described and claimed without restricting the scope of these features to the precise numerical ranges provided. Accordingly, these terms should be interpreted as indicating that insubstantial or inconsequential modifications or alterations of the subject matter described and claimed are considered to be within the scope of the invention as recited in the appended claims.
It should be noted that the term “exemplary” as used herein to describe various embodiments is intended to indicate that such embodiments are possible examples, representations, and/or illustrations of possible embodiments (and such term is not intended to connote that such embodiments are necessarily extraordinary or superlative examples).
The terms “coupled,” “connected,” and the like as used herein mean the joining of two members directly or indirectly to one another. Such joining may be stationary (e.g., permanent) or moveable (e.g., removable or releasable). Such joining may be achieved with the two members or the two members and any additional intermediate members being integrally formed as a single unitary body with one another or with the two members or the two members and any additional intermediate members being attached to one another.
References herein to the positions of elements (e.g., “top,” “bottom,” “above,” “below,” etc.) are merely used to describe the orientation of various elements in the FIGURES. It should be noted that the orientation of various elements may differ according to other exemplary embodiments, and that such variations are intended to be encompassed by the present disclosure.
It is important to note that the construction and arrangement of the one-piece seat structure as shown in the various exemplary embodiments is illustrative only. Although only a few embodiments have been described in detail in this disclosure, those skilled in the art who review this disclosure will readily appreciate that many modifications are possible (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters, mounting arrangements, use of materials, colors, orientations, etc.) without materially departing from the novel teachings and advantages of the subject matter described herein. For example, elements shown as integrally formed may be constructed of multiple parts or elements, the position of elements may be reversed or otherwise varied, and the nature or number of discrete elements or positions may be altered or varied. The order or sequence of any process or method steps may be varied or re-sequenced according to alternative embodiments. Other substitutions, modifications, changes and omissions may also be made in the design, operating conditions and arrangement of the various exemplary embodiments without departing from the scope of the present invention.
This application claims the benefit of and priority to U.S. Provisional Patent Application No. 61/106,045, filed Oct. 16, 2008, titled: ONE-PIECE SEAT STRUCTURES AND PROCESSES USING COLD FORMING TO CREATE SEAT STRUCTURES, in the name of Zekavica et al. and U.S. Provisional Patent Application No. 61/228,836, filed Jul. 27, 2009, titled: ONE-PIECE SEAT STRUCTURES AND METHOD OF FORMING, in the name of Zekavica et al., which are incorporated by reference herein.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/US09/61027 | 10/16/2009 | WO | 00 | 5/10/2011 |
| Number | Date | Country | |
|---|---|---|---|
| 61228836 | Jul 2009 | US | |
| 61106045 | Oct 2008 | US |
