US20010015302A1 - Double-walled structure and method of producing the same - Google Patents

Double-walled structure and method of producing the same Download PDF

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Publication number
US20010015302A1
US20010015302A1 US09/789,979 US78997901A US2001015302A1 US 20010015302 A1 US20010015302 A1 US 20010015302A1 US 78997901 A US78997901 A US 78997901A US 2001015302 A1 US2001015302 A1 US 2001015302A1
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US
United States
Prior art keywords
inner tube
sound
absorbing
tubular
absorbing element
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
Application number
US09/789,979
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English (en)
Inventor
Mats Lundgren
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Lindab AB
Original Assignee
Lindab AB
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Filing date
Publication date
Application filed by Lindab AB filed Critical Lindab AB
Assigned to LINDAB AB: reassignment LINDAB AB: ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: LUNDGREN, MATS
Publication of US20010015302A1 publication Critical patent/US20010015302A1/en
Abandoned legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F13/00—Details common to, or for air-conditioning, air-humidification, ventilation or use of air currents for screening
    • F24F13/02—Ducting arrangements
    • F24F13/0263—Insulation for air ducts
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N1/00—Silencing apparatus characterised by method of silencing
    • F01N1/24—Silencing apparatus characterised by method of silencing by using sound-absorbing materials
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N13/00—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00
    • F01N13/18—Construction facilitating manufacture, assembly, or disassembly
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F13/00—Details common to, or for air-conditioning, air-humidification, ventilation or use of air currents for screening
    • F24F13/02—Ducting arrangements
    • F24F13/0245—Manufacturing or assembly of air ducts; Methods therefor
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F13/00—Details common to, or for air-conditioning, air-humidification, ventilation or use of air currents for screening
    • F24F13/02—Ducting arrangements
    • F24F13/0281—Multilayer duct
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F13/00—Details common to, or for air-conditioning, air-humidification, ventilation or use of air currents for screening
    • F24F13/24—Means for preventing or suppressing noise
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F13/00—Details common to, or for air-conditioning, air-humidification, ventilation or use of air currents for screening
    • F24F13/24—Means for preventing or suppressing noise
    • F24F2013/242—Sound-absorbing material

Definitions

  • the present invention relates to a double-walled structure, such as a silencer, for use in a ventilation duct system.
  • the invention also concerns a method of producing such a double-walled structure.
  • Double-walled sound-absorbing structures for use in ventilation duct systems are well known.
  • a per se well-functioning double-walled silencer is known, for instance, from a catalogue entitled “Ventilation 95, Manual and Catalogue” published by Lindab AB in 1995.
  • Page 4/6 describes the general construction of a circular silencer.
  • This prior-art silencer is composed of a circular inner tube of perforated sheet metal, a surrounding circular spirally-wound lock-seam tube of sheet metal, and an intermediate layer of sound-absorbing mineral wool. Between the perforated inner tube and the sound-absorbing material there is a protective layer, such as fiber cloth or fabric of e.g. glass wool, for preventing mineral wool from being drawn into the duct.
  • U.S. Pat. No. 5,911,457 to Hultberg et al discloses a method for producing a double-walled structure, such as a silencer according to U.S. Pat. No. 5,801,342 to Hultberg et al, which to some extent resembles a silencer of the above type.
  • a perforated metal strip is wound together with a strip of air-permeable fabric to form a tube the outside of which is coated with said fabric.
  • the coated, perforated tube is provided on its outside with a tubular layer of sound-absorbing material and then inserted into a casing for completing the silencer.
  • An object of the present invention is to provide a double-walled structure with improved sound-absorbing properties which is further developed in relation to prior art.
  • a further object of the invention is to provide a method of producing an inventive double-walled structure.
  • a double-walled sound-absorbing structure in particular a silencer, comprising an inner tube having a center axis, an outer casing which is arranged at a distance from said inner tube and encloses the same, and a tubular sound-absorbing element which is arranged between said inner tube and said casing, wherein said tubular element has an increasing density radially outwards from said center axis of said inner tube.
  • a method of producing a double-walled structure which comprises an inner tube having a center axis, an outer casing which is arranged at a distance from said inner tube and encloses the same, and a tubular sound-absorbing element which is arranged between said inner tube and said casing; said method comprising the steps: that said sound-absorbing element is arranged on the outside of said inner tube in such manner that the density of said element increases radially outwards from said center axis of said inner tube; and that said inner tube with said sound-absorbing element arranged thereon are enclosed in said outer casing.
  • the double-walled structure is adapted to absorb sound which propagates from the inner tube towards the casing.
  • An advantage of letting the density of the sound-absorbing element of the inventive double-walled structure increase radially outwards from the center axis of the inner tube is that the sound-absorbing properties of the double-walled structure will be improved.
  • Comparative tests of inventive double-walled structures with a radially increasing density and double-walled structures whose sound-absorbing insulation has a constant density, have been carried out.
  • the method used for testing is “Standard ISO 7235” which is well known to those skilled in the art. The tests showed that improved sound absorption by from one dB up to as much as 10 dB is obtained in the frequency range 100-1500 Hz, in which the greatest improvement is achieved between 200 and 1000 Hz where the difference is 4-10 dB.
  • the sound-absorbing element comprise two or more layers of sound-absorbing material
  • the element can, in a simple manner in terms of manufacture, be given an increasing density radially outwards from the center axis of the inner tube.
  • the layers can consist of different materials having different density.
  • An advantage of arranging, according to one embodiment of the invention, a tubular cylinder which is rigid and sound-permeable, between and coaxially with two neighboring layers of sound-absorbing material is that one layer of sound-absorbing material can be wound round another layer, without affecting the density thereof.
  • the air permeability allows transmission of sound in the radial direction from the center axis of the double-walled structure.
  • one or more layers consist of a tubular casing.
  • a tubular casing can be circular in cross-section or consist of e.g. two tubular casing halves which are semicircular in cross-section. The use of tubular casings facilitates the work in assembling the double-walled structure.
  • one or more layers consist of a sound-absorbing material which is wound at least one turn round the outer circumferential surface of the inner tube. This permits variation of the density in the sound-absorbing material in a simple manner owing to the possibility of varying the degree of firmness with which each layer is wound.
  • the sound-absorbing element comprises a material with a density gradient, whereby only one layer and only one turn of winding or layer round the outer circumferential surface of the inner tube is necessary.
  • the sound-absorbing element is advantageously made of a yieldable material to facilitate the work in mounting it in the double-walled structure. Moreover it is possible to readily achieve variations in the density of the element in the winding speed when producing double-walled structures with wound sound-absorbing elements.
  • the sound-absorbing element is made of a fiber material, such as mineral wool.
  • a fiber material makes is possible to provide a sound-absorbing element and, thus, a double-walled sound-absorbing structure having a low weight. This is, of course, an advantage in connection with long sound-absorbing double-walled structures in the form of entire ducts, since for instance the mounting work is facilitated.
  • the double-walled structure has an inner tube, which according to a preferred embodiment is made to be sound permeable and which is provided with perforations, the sound in the duct can be better transmitted to the sound-absorbing element for more efficient absorption.
  • the perforations are distributed over essentially the entire wall of the inner tube.
  • the method of producing the inventive double-walled structure has advantages which correspond to the advantages of the actual double-walled structure, especially as regards rational production of the same.
  • FIGS. 1 - 8 illustrate an embodiment of a double-walled sound-absorbing structure and its components, and assembly of the same, where
  • FIG. 1 shows a perforated inner tube and a sound-absorbing element for composing a double-walled sound-absorbing structure
  • FIG. 2 shows the inner tube and the sound-absorbing element fixed to its outer circumferential surface
  • FIG. 3 shows the inner tube and the sound-absorbing element which is fixed thereto and which has been wound one turn round the inner tube
  • FIG. 4 shows the inner tube and the sound-absorbing element which is fixed thereto and which has been wound a plurality of turns round the inner tube
  • FIG. 5 shows the inner tube with the completely wound sound-absorbing element
  • FIG. 6 shows the inner tube with the sound-absorbing element wound round the same, partly inserted into an outer casing
  • FIG. 7 shows the inner tube with the sound-absorbing element wound round the same, completely inserted into the casing
  • FIG. 8 is a cross-sectional view of the double-walled structure in FIG. 7.
  • FIGS. 9 - 13 are cross-sectional views of the inventive double-walled structure according to alternative embodiments.
  • FIGS. 1 - 8 A double-walled sound-absorbing structure 1 and the production thereof according to a preferred embodiment of the invention are shown in FIGS. 1 - 8 .
  • the double-walled structure consists of a silencer for use in a ventilation duct system.
  • the silencer 1 comprises an inner tube 10 , a sound-absorbing element 20 , an outer casing 30 and two end pieces 40 .
  • the inner tube 10 is circular in cross-section and has a first and a second open end 11 , 12 (see FIG. 1).
  • the inner tube 10 can be made by spirally lock-seaming a strip of sheet metal.
  • the inner tube 10 is provided with perforations 13 , and its outer circumferential surface 14 is preferably covered by an air-permeable fabric (not shown).
  • the sound-absorbing element 20 is a rectangular sheet or web.
  • the sheet 20 is made of a yieldable, sound-absorbing material, such as mineral wool, and has a first and a second short side 21 , 22 .
  • the sound-absorbing element 20 is along one short side 21 held in place on the outer circumferential surface 14 of the inner tube 10 in such manner that the short side 21 is parallel with the center axis 20 of the inner tube 10 .
  • This can be provided, for instance, by means of clamps or forks (not shown) which are removed after completion of the winding.
  • the inner tube 10 is rotated in a direction R in such manner that the sound-absorbing element 20 is wound round the inner tube 10 .
  • the width B of the sound-absorbing element 20 is somewhat smaller than the length L of the inner tube 10 , and therefore the inner tube 10 will at its two ends 11 , 12 protrude a distance outside the applied sound-absorbing element 20 .
  • the element 20 is wound symmetrically relative to the two ends 11 , 12 of the inner tube 10 . It is also evident from FIG. 3 that the first short side 21 of the yieldable sound-absorbing sheet 20 is compressed under the beginning of the next turn of winding, whereby a relatively smooth transition between the turns of the sheet 20 is obtained.
  • FIGS. 3 and 4 show how during the winding phase a force F is applied to the sound-absorbing element 20 in its longitudinal direction.
  • the sheet 20 is compressed more and more, whereby its turns are given higher and higher density. It is shown in FIGS. 4 and 5 that the sound-absorbing element 20 has been applied in such manner that for each turn or layer, the thickness decreases and the density increases radially outwards from the center axis C of the inner tube 10 .
  • the element 20 is along its second short side 22 held in place against the interiorly situated layer of the element 20 until the inner tube 10 and the element 20 are inserted into the outer casing 30 .
  • FIGS. 6 and 7 show the casing 30 which is circular in cross-section and has a first and a second end 31 , 32 .
  • the casing 30 can, like the inner tube 10 , be manufactured, for instance, by spirally lock-seaming a strip of sheet metal.
  • the inner tube 10 and the sound-absorbing element 20 wound round the same are jointly inserted into the casing 30 which is then closed at both ends 31 , 32 by means of the end pieces 30 for completion of the silencer 1 .
  • one of the end pieces 40 can be mounted on the casing 30 even before the inner tube 10 and the sound-damping element 20 are inserted (not shown).
  • FIG. 8 is a cross-sectional view of the silencer 1 described above.
  • FIGS. 9 - 13 are cross-sectional views of double-walled sound-absorbing structures according to alternative embodiments of the invention. Each of these embodiments comprises the inner tube 10 , the sound-absorbing element 20 and the outer casing 30 .
  • the design of the sound-absorbing element 20 differs, but in all embodiments the density increases radially from the center axis C of the inner tube 10 according to the invention.
  • the element 20 consists of two coaxial, spirally wound layers 21 , 22 of sound-absorbing material.
  • the inner layer 21 closest to the inner tube 10 is more loosely wound than the outer layer 22 and will thus have a lower density than the latter (provided that the materials in their unwound state have the same density).
  • the layers 21 , 22 can be made of the same material or of different materials with, for instance, different density.
  • a tubular cylinder 23 is placed between the inner layer 21 and the outer layer 22 , coaxially therewith.
  • the cylinder 23 which has essentially the same length as the width of each of the layers 21 , 22 , is made of, for instance, metal wire netting.
  • the meshes of the wire netting are preferably about 10 ⁇ 10 mm. Thanks to the cylinder 23 , which is rigid, the outer layer 22 can be wound without affecting the density of the inner layer 21 .
  • FIGS. 10 and 11 are cross-sectional views of a double-walled structure with a sound-absorbing element 20 , whose layers consist of so-called tubular casings 24 a, 25 a (FIG. 10) which are circular in cross-section or of tubular casing halves 24 b, 24 c, 25 b, 25 c (FIG. 11) which are semicircular in cross-section.
  • the tubular casings 24 a - c arranged closest to the inner tube 10 have a lower density than the tubular casings 25 a - c arranged closest to the outer casing 30 .
  • FIGS. 10 Each layer in the embodiments according to FIGS.
  • tubular casing 24 a or tubular casing halves 24 b, 24 c is lined with a fabric which forms the inner tube 10 .
  • an applied inner layer 26 can be combined with an outer layer 27 which is a tubular casing.
  • the sound-absorbing element 20 is formed of a layer of an insulating mat 28 which has been wound one turn round the inner tube 10 .
  • the insulating mat 28 has in itself a density gradient in such a direction that, when the mat 28 is wound round the inner tube 10 , a sound-absorbing element 20 with a density increasing radially outwards from the center axis C of the inner tube 10 is provided.
  • the insulating mat 28 is a tubular casing, alternatively two or more tubular casing parts, with a built-in density gradient.
  • the inside of the tubular casing 28 is lined with a fabric which forms the inner tube 10 .
  • the invention has been described above with reference to some embodiments chosen by way of example, but it will be appreciated that modifications are feasible within the scope of the invention as defined in the appended claims.
  • more than two layers can be used.
  • different types of layer such as tubular casings and windings, can be combined to further alternative embodiments of the double-walled structure.
  • the sound-absorbing element could also comprise more than one insulating mat or tubular casing of the kind which in itself has a density gradient.
  • the choice of materials for different layers in the sound-absorbing element can be varied to achieve the desired density gradient.
  • a double-walled structure or silencer can be formed with four layers of the following materials: melamine (10 kg/m 3 ), polyester (22 kg/m 3 ), glass wool (20-30 kg/m 3 ) and rock wool (80 kg/m 3 ) in this order, seen from inside the circumferential surface of the inner tube.
  • the melamine layer eliminates the need for a special protective layer, such as a fiber cloth or fabric, on the inner tube.
  • a special protective layer such as a fiber cloth or fabric
  • the elements included in the double-walled structure can be non-circular in cross-section, such as oval or rectangular.
  • the inner tube can be circular and the casing rectangular.
  • tubular casing parts such as tubular casing halves which are internally semicircular in cross-section and externally rectangular in cross-section, can be used.
  • a double-walled structure need not be straight like in the embodiments shown by way of example.
  • a sound-absorbing structure provided with end pieces has been described above, but within the scope of the invention also longer double-walled structures are feasible, which are not provided with end pieces but constitute entire ventilation ducts.
  • the method in which a sound-absorbing material is wound round the inner tube can be varied by the sound-absorbing material being either spirally wound or formed as one or more narrow strips which are wound along a helical line in one or more layers.
  • the actual winding can take place by the inner tube being rotated, by the sound-absorbing material being wound round a stationary inner tube or by the material being wound round a rotating tube.
  • the intermediate tubular cylinder which is used in the embodiment according to FIG. 9 can be made of a wire netting of metal or some other rigid material, or of a perforated, e.g. spirally lock-seamed, tube.
  • inventive double-walled structure is applicable to other systems than ventilation duct systems, such as silencers for vehicles, compressors and the like.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Exhaust Silencers (AREA)
  • Pipe Accessories (AREA)
US09/789,979 2000-02-22 2001-02-21 Double-walled structure and method of producing the same Abandoned US20010015302A1 (en)

Applications Claiming Priority (2)

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SE0000559A SE515765C2 (sv) 2000-02-22 2000-02-22 Dubbelväggig konstruktion och sätt att tillverka densamma
SE0000559-5 2000-02-22

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Cited By (9)

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US20070074930A1 (en) * 2005-10-05 2007-04-05 Arrowhead Products Corporation Lightweight polymer muffler apparatus and method of making same
US20080202151A1 (en) * 2005-05-31 2008-08-28 Carrier Corporation Method and Apparatus for Reducing the Noise Level Outputted by Oil Separator
US8393436B2 (en) * 2011-04-15 2013-03-12 Arrowhead Products Corporation Flexible muffler for use in aircraft environmental control systems and method of manufacture
US9382826B1 (en) * 2015-01-09 2016-07-05 Dayco Ip Holdings, Llc Noise attenuating member for noise attenuating units in engines
US10753627B1 (en) * 2005-07-13 2020-08-25 Qc Manufacturing, Inc. Air cooling system for a building structure
US10980391B2 (en) 2017-04-28 2021-04-20 Owens Corning Intellectual Capital, Llc Appliance with acoustically insulated ductwork
US11092350B1 (en) 2019-11-22 2021-08-17 Qc Manufacturing, Inc. Multifunction adaptive whole house fan system
JP2021162177A (ja) * 2020-03-30 2021-10-11 イビデン株式会社 燃焼装置用消音器
US11668328B2 (en) 2020-07-27 2023-06-06 Carrier Corporation Noise reduction device for outlet side of fan and heat exchange system including the same

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EP1411218A3 (de) * 2002-10-15 2004-05-26 ATJ Autotechnik Gmbh Verfahren zur Herstellung isolierter Körper
DE10248781B3 (de) * 2002-10-15 2004-02-19 Atj Autotechnik Gmbh Verfahren zur Herstellung isolierter Körper
US9567087B1 (en) * 2015-12-16 2017-02-14 Hamilton Sundstrand Corporation Honeycomb acoustic liner
RU191178U1 (ru) * 2019-01-24 2019-07-29 Антон Геннадьевич Вайс Звукоизолированный воздуховод

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US20080202151A1 (en) * 2005-05-31 2008-08-28 Carrier Corporation Method and Apparatus for Reducing the Noise Level Outputted by Oil Separator
US8276398B2 (en) * 2005-05-31 2012-10-02 Carrier Corporation Methods and apparatus for reducing the noise level outputted by oil separator
US11821651B1 (en) 2005-07-13 2023-11-21 Qc Manufacturing, Inc. Air cooling system for a building structure
US10753627B1 (en) * 2005-07-13 2020-08-25 Qc Manufacturing, Inc. Air cooling system for a building structure
US7546899B2 (en) * 2005-10-05 2009-06-16 Arrowhead Products Corporation Lightweight polymer muffler apparatus and method of making same
US20070074930A1 (en) * 2005-10-05 2007-04-05 Arrowhead Products Corporation Lightweight polymer muffler apparatus and method of making same
US8393436B2 (en) * 2011-04-15 2013-03-12 Arrowhead Products Corporation Flexible muffler for use in aircraft environmental control systems and method of manufacture
US9382826B1 (en) * 2015-01-09 2016-07-05 Dayco Ip Holdings, Llc Noise attenuating member for noise attenuating units in engines
WO2016111921A1 (en) * 2015-01-09 2016-07-14 Dayco Ip Holdings, Llc Noise attenuating member for noise attenuating units in engines
CN105960512A (zh) * 2015-01-09 2016-09-21 戴科知识产权控股有限责任公司 用于发动机中的噪声衰减单元的噪声衰减部件
KR20170102458A (ko) * 2015-01-09 2017-09-11 데이코 아이피 홀딩스 엘엘시 엔진 내 소음 감쇄 유닛을 위한 소음 감쇄 부재
KR102269213B1 (ko) 2015-01-09 2021-06-24 데이코 아이피 홀딩스 엘엘시 엔진 내 소음 감쇄 유닛을 위한 소음 감쇄 부재
US10980391B2 (en) 2017-04-28 2021-04-20 Owens Corning Intellectual Capital, Llc Appliance with acoustically insulated ductwork
US11193687B2 (en) 2019-11-22 2021-12-07 Qc Manufacturing, Inc. Multifunction adaptive whole house fan system
US11415333B2 (en) 2019-11-22 2022-08-16 Qc Manufacturing, Inc. Fresh air cooling and ventilating system
US11435103B2 (en) 2019-11-22 2022-09-06 Qc Manufacturing, Inc. Multifunction adaptive whole house fan system
US11609015B2 (en) 2019-11-22 2023-03-21 Qc Manufacturing, Inc. Multifunction adaptive whole house fan system
US11092350B1 (en) 2019-11-22 2021-08-17 Qc Manufacturing, Inc. Multifunction adaptive whole house fan system
US12038188B2 (en) 2019-11-22 2024-07-16 Qc Manufacturing, Inc. Multifunction adaptive whole house fan system
JP2021162177A (ja) * 2020-03-30 2021-10-11 イビデン株式会社 燃焼装置用消音器
JP7405672B2 (ja) 2020-03-30 2023-12-26 イビデン株式会社 燃焼装置用消音器
US11668328B2 (en) 2020-07-27 2023-06-06 Carrier Corporation Noise reduction device for outlet side of fan and heat exchange system including the same

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Publication number Publication date
SE515765C2 (sv) 2001-10-08
EP1128032A2 (en) 2001-08-29
SE0000559D0 (sv) 2000-02-22
SE0000559L (sv) 2001-08-23

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Owner name: LINDAB AB:, SWEDEN

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:LUNDGREN, MATS;REEL/FRAME:011558/0365

Effective date: 20010129

STCB Information on status: application discontinuation

Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION