Claims
- 1. Apparatus for producing a double-walled structure, comprising a joiner that couples a fluid-permeable material with a strip of perforated material to form a composite strip;
- a forming head that helically bends said composite strip to form a tube having an inside surface comprising the perforated strip and an outside surface comprising the strip of fluid permeable material;
- a cutting unit that separates said tube into tube sections of predetermined length;
- a filler applicator that applies a filler material on the outside of at least one of said tube sections to form an assembly; and a casing applicator that disposes a casing around said assembly.
- 2. The apparatus of claim 1, further including edge forming rollers that secure abutting longitudinal edge portions of said helically bent strip of fluid permeable material by forming said abutting edge portions into a helical lock seam.
- 3. The apparatus of claim 1, wherein said joiner includes a reel on which said strip of fluid-permeable material is wound, and guiding plates that feed said composite strip into said forming head.
- 4. The apparatus of claim 1, wherein said double-walled structure is a silencer for use in a ventilation duct system.
Parent Case Info
This application is a division of application Ser. No. 08/788,246, filed Jan. 27, 1997, U.S. Pat. No. 5,801,342.
US Referenced Citations (13)
Foreign Referenced Citations (7)
Number |
Date |
Country |
546790A1 |
Jun 1993 |
EPX |
1146971 |
Nov 1957 |
FRX |
1307015 |
Sep 1962 |
FRX |
1211608 |
Aug 1989 |
JPX |
206768 |
Aug 1939 |
CHX |
2122256 |
Jan 1984 |
GBX |
WO9407620 |
Apr 1994 |
WOX |
Non-Patent Literature Citations (1)
Entry |
Brochure, LindabSilencer, Lindab Ltd., 1988. |
Divisions (1)
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Number |
Date |
Country |
Parent |
788246 |
Jan 1997 |
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