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US-20260124560-A1 - VARIABLE CRIMPED EXPANDED METAL FILTERS, BI-DIRECTIONALLY EXPANDED METAL FILTERS, COMBINATIONS THEREOF AND EXPANDING METHODS FOR MANUFACTURING EXPANDED SHEET METAL

US20260124560A1US 20260124560 A1US20260124560 A1US 20260124560A1US-20260124560-A1

Abstract

Light weight and efficient airbag filter devices are made from expanded metal strips. In some embodiments, an expanded metal strip is a bi-directionally expanded metal sheet where the blade alternately comes from the top-down direction as well as from the bottom-up direction, so that one continuous strip of steel can be expanded facing up in one section and then facing down in the next section without cutting or removing the strip from the processing line. In some embodiments, an expanded metal strip may be crimped variably based upon the layer's length. In some embodiments, bi-directional expanding may be combined with variable crimping of the individual sections/layers allowing for a single strip of metal to be both expanded in two directions and crimped layer by layer during a continuous process on one sheet of metal.

Inventors

  • Erich Bittner
  • Abad Cruz
  • Karel Sander
  • Steven Huntsman

Assignees

  • ACS INDUSTRIES, INC.

Dates

Publication Date
20260507
Application Date
20251104

Claims (20)

  1. 1 . A filter for an airbag inflator comprising a continuous strip of expanded metal rolled-up about a longitudinal axis to form multiple rolled, overlapping layers, the filter having an inner layer and a plurality of outer layers, wherein each successive layer of the filter is formed by a discrete section of the continuous strip, wherein the continuous strip is bi-directionally expanded such that at least one section is expanded in a top-down direction providing said section with a smooth side on one surface thereof and at least one section is expanded in a bottom-up direction providing said section with a smooth side on an opposing surface, thereby creating a rolled filter with at least one layer having a smooth side facing inwardly and at least one layer having a smooth side facing outwardly.
  2. 2 . The filter of claim 1 wherein the strip of extended metal is flattened.
  3. 3 . The filter of claim 1 wherein the top-down and bottom up bi-directionally expanded sections are adjacent to each other.
  4. 4 . The filer of claim 1 wherein each layer of said filter comprises a plurality of apertures having an average open area (OA), and wherein the OA's decrease from the inner layer to at least one of the outer layers.
  5. 5 . The filter of claim 1 wherein the expanded metal is directional flow expanded metal.
  6. 6 . The filter of claim 1 wherein at least one of the sections of the continuous strip is crimped to create a plenum layer.
  7. 7 . The filter of claim 1 wherein the continuous strip comprises alternating crimped and non-crimped layers.
  8. 8 . The filter of claim 1 wherein the outer layer of the filter is a crimped layer.
  9. 9 . The filter of claim 1 wherein the inner layer of the filter is a crimped layer.
  10. 10 . The filter of claim 1 wherein the filter has a central cavity.
  11. 11 . A filter for an airbag inflator comprising a continuous strip of expanded metal rolled-up about a longitudinal axis to form multiple rolled, overlapping layers, the filter having an inner layer and a plurality of outer layers, wherein each successive layer of the filter is formed by a discrete section of the continuous strip, wherein at least one of the sections of the continuous strip is crimped to create a plenum layer.
  12. 12 . The filter of claim 11 wherein the continuous strip comprises alternating crimped and non-crimped layers.
  13. 13 . The filter of claim 11 wherein the outer layer of the filter is a crimped layer.
  14. 14 . The filter of claim 11 wherein the inner layer of the filter is a crimped layer.
  15. 15 . The filter of claim 11 wherein the continuous strip is bi-directionally expanded such that at least one section is expanded in a top-down direction providing said section with a smooth side on one surface thereof and at least one section is expanded in a bottom-up direction providing said section with a smooth side on an opposing surface, thereby creating a rolled filter with at least one layer having a smooth side facing inwardly and at least one layer having a smooth side facing outwardly.
  16. 16 . The filter of claim 11 wherein the strip of extended metal is flattened.
  17. 17 . The filter of claim 11 wherein the top-down and bottom up bi-directionally expanded sections are adjacent to each other.
  18. 18 . The filter of claim 11 wherein each layer of said filter comprises a plurality of apertures having an average open area (OA), and wherein the OA's decrease from the inner layer to at least one of the outer layers.
  19. 19 . The filter of claim 11 wherein the expanded metal is directional flow expanded metal.
  20. 20 . The filter of claim 11 wherein the filter has a central cavity.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Patent Application No. 63/716,182, filed Nov. 4, 2024, the entire contents of which is incorporated herein by reference. BACKGROUND OF THE DISCLOSURE (1) Field of the Invention The instant invention relates to rolled or wrapped expanded metal filters, and in particular, rolled or wrapped expanded metal filters for use in airbag inflator assemblies. (2) Description of Related Art Expanded Metal: Expanded metal has found a variety of uses, from mats used for fighting fires to filters for airbag inflators. Expanded metal can be made in a variety of ways. For example, expanded metal can be made by taking a sheet of metal, puncturing the sheet to produce a multiplicity of slits, and pulling the sheet perpendicular to the direction of the slit to elongate the slit and provide an opening in the sheet. Another more common method for making expanded metal is by piercing and cold forming openings, which are often called “diamonds” because of their final shape. The final length of the sheet, with the accompanying holes, is longer than the original and so it is expanded, as well as the openings formed being expanded. Thus, although the details will vary depending on the specific process, expanded metal sheets are typically made by using a row of teeth or bits in a punch to produce perforations in the sheet. The side of the sheet facing the punch (smooth side) will have an indentation around the perforation, and the reverse side of the sheet (rough side) will have a corresponding raised portion, a burr, around the perforation. In some cases, the expanded metal is then flattened to reduce the height of the burrs for various reasons. Expanded metal is well known for use in pyrotechnic airbag inflators as a filter which can both absorb heat and capture slag, cleaning and cooling the explosive airflow before it reaches the air bag. A “Jet Fire” is a turbulent thermodynamic diffusion flame or premixed flame, and results from the combustion of an oxidized fuel (solid or liquid) burning under pressure, and released with significant momentum into a particular direction near to, or above Mach velocity speeds, loaded with burning particulate filled fuel at temperatures normally exceeding 1300° C. This is normally how pyrotechnic airbag inflator systems are designed to function. As noted above, rolled expanded metal filters are known in the art for cooling the combustion gases and filtering slag particles from a jet fire combustion. The present disclosure relates to an improved filter, an improved manufacturing method of the expanded metal and aspects of wrapping the layers of the filter in such a system. SUMMARY OF THE DISCLOSURE According to exemplary embodiments of the invention, light weight and efficient airbag filter devices are made from expanded metal strips having novel bi-directionally expanded metal and/or variably crimped expanded metal sections (layers) which more effectively encapsulate, cool and filter a jet fire and thus mitigate the flames and burning particles (slag) from escaping the airbag system, where a jet fire is by design propagable inside the filter cavity system. In some embodiments, an expanded metal strip is a bi-directionally expanded metal sheet where the blade alternately comes from the top-down direction as well as from the bottom-up direction, so that one continuous strip of steel can be expanded facing up in one section and then facing down in the next section without cutting or removing the strip from the processing line. A rotatable expanding head is disclosed for rotating the expanding blade and fixed die 180 degrees about the strip to change the expanding direction for selected sections/layers of the filter. In some embodiments, an expanded metal strip may be crimped based upon the layer's length and layered position in the filter. In some embodiments, bi-directional expanding may be combined with variable crimping of the individual sections/layers allowing for a single strip of metal to be both expanded in two directions and crimped section by section or in alternating sections during a continuous process on one sheet of metal. While embodiments of the invention have been described as having the features recited, it is understood that various combinations of such features are also encompassed by particular embodiments of the invention and that the scope of the invention is limited by the claims and not the description. BRIEF DESCRIPTION OF THE DRAWING FIGURES While the specification concludes with claims particularly pointing out and distinctly claiming particular embodiments of the instant invention, various embodiments of the invention can be more readily understood and appreciated from the following descriptions of various embodiments of the invention when read in conjunction with the accompanying drawings in which: FIG. 1 is a perspective view of an exemplary airbag filter formed from a contin