US3744147A - Artificial seasoning of timber - Google Patents

Artificial seasoning of timber Download PDF

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Publication number
US3744147A
US3744147A US00855880A US3744147DA US3744147A US 3744147 A US3744147 A US 3744147A US 00855880 A US00855880 A US 00855880A US 3744147D A US3744147D A US 3744147DA US 3744147 A US3744147 A US 3744147A
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boards
rollers
lumber
drying
hold
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US00855880A
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English (en)
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J Pless
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Individual
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B15/00—Machines or apparatus for drying objects with progressive movement; Machines or apparatus with progressive movement for drying batches of material in compact form
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B2210/00—Drying processes and machines for solid objects characterised by the specific requirements of the drying good
    • F26B2210/16—Wood, e.g. lumber, timber

Definitions

  • the invention relates to an improved method of preventing bowing, cupping twisting or springing of boards or planks of lumber.
  • the boards or planks are passed between spaced pairs of rollers arranged to hold the lumber in a fixed plane.
  • the lumber is there fore held in this plane while it is setting.
  • the drying schedule includes intermittent exposure of the lumber to microwave radiation in an electronic kiln I dryer.
  • a method of drying boards or planks of lumber in which the lumber is heated to reduce the moisture content to the desired final level includes: passing the lumber between pairs of rollers arranged to hold the lumber in a fixed plane for at least that part of the drying process after the fibre saturation point has been reached, the unsupported length of lumber between adjacent pairs of rollers being not more than five feet, each pair of the rollers being either fixed or resiliently biased toward one an other and the spacing between the rollers in each pair, or the biasing force urging the rollers together, being such that substantially no compressive force is applied to correctly sawn lumber moving between the rollers, whereby the lumber sets in a straightened condition and cupping, bowing, twisting or springing of the lumber is prevented.
  • the rollers are situated within an electronic kiln drying tunnel but they may also be positioned toward the end of a high temperature convection heat drying process where lumber is subjected to alternating treatment with dry air at a temperature above 100 C and with wet steam.
  • the rollers are made of a material which is harder than the lumber passing between them, for example cement, stone, glass, porce- -lain or metal.
  • the spacing between the rollers in each pair is determined by the standard thickness of the lumber being fed through the process, and the number of pairs of rollers will depend on the speed at which the lumber is moving and the distance between each pair of rollers.
  • the width of the rollers depends onthe number of pieces of lumber being fed through side by side and the width of each piece.
  • rollers are fixed, the rollers of each pair are spaced apart just sufficiently for the standard size lumber to pass between them and hence any oversize lumber is compressed between the rollers. If the rollers are resiliently biased toward one another, the pressure between the rollers is kept low enough not to compress the standard size lumber. Excessive pressure must be avoided at low moisture content levels since the lumber has lost some of its elasticity and is setting, and excessive pressure will therefore cause splitting.
  • the rollers are preferably driven and thereby act to move the lumber during the drying process.
  • the movement may include a forward and backward motion in the electronic kiln or between steam and dry air chambers in a convection process.
  • the distance between the rollers in each pair must then be such that sufficient frictional contact'between the rollers and the lumber occurs to prevent slippage.
  • FIG. 1 is a side elevational view of a electronic kiln drying process embodying the invention
  • FIG. 2 is a perspective view of a detail of the electronic kiln shown in FIG. 1.
  • lumber is fed into a kiln drying tunnel 1 on a conveyer 2.
  • the initial portion of the tunnel comprises a pre-heating chamber 9 in which lumber is dried approximately to its fibre saturation point (around 25 percent moisture content).
  • This chamber is filled with relatively low power microwave radiation to permit dielectric heating of the lumber over a relatively long period.
  • the tunnel is split into much shorter sections comprising alternate high power microwave drying chambers 3 and control sections 4.
  • Each microwave chamber has its own waveguide 5 and microwave generator 6.
  • Microwave energy is launched through the roof of each chamber to produce a rapid burst of dielectric heating as the lumber moves through the chamber.
  • the power consumption of electrical energy per cu. ft. varies according to the density and thickness of the lumber and lies between 2 and 15 kilowatts per cubic foot. As much energy as possible is fed into each chamber without damaging the timber.
  • the maximum permitted energy concentration is previously calibrated using lumber having known density, thickness and moisture contents. Above the permitted maximum and steam pressure within the lumber becomes too great and the wood ruptures.
  • control sections 4 lie between the microwave chambers, the control sections being preferably three times as long as the microwave chambers.
  • control rollers 7 If, for example, 1 inch boards of Perana pipe are being fed through the kiln, the maximum distance between adjacent pairs of rollers should not exceed three feet. On the other hand, for 2 inch boards of Hemlock, the adjacent roller pairs may be up to five feet apart.
  • the purpose of the rollers is to hold the boards or planks in a fixed plane during the drying process. Before entering the kiln, the boards have already been dried to their fibre saturation point and the control rollers are therefore only acting on the boards or planks in the latter stages of the drying schedule. It has been found that these rollers almost completely eliminate any cupping, bowing, twisting or springing of the lumber after it is fed out of the kiln.
  • a three foot long reinforced steel tubing roller may have a diameter of 2% inches.
  • Such a roller would be able to withstand pressures of 1,000 tons per square inch and hence any oversize lumber will be squashed between the rollers during its passage through the kiln. Normally, however, the pressure on the lumher is fairly low, the rollers merely acting to hold the lumber straight while it sets.
  • the control chambers may also include watersprays for spraying the surface of the lumber to control the rate of evaporation. The surface is thus kept moist until the centre of the lumber dries out.
  • a steam pipe 8 runs the complete length of the tunnel and maintains a high ambient temperature. Since the drying is effected by dielectric heating which drives steam out from the centre of the lumber, the high ambient temperature helps to minimise the amount of power consumed in reducing the moisture content to a given level.
  • a method of drying wooden boards in which the wood is heated to reduce the moisture content to the desired final level including: passing the boards between fixed pairs of rollers arranged to hold the boards in a fixed plane for at least that part of the drying process after the fibre saturation point of the wood has been reached, the unsupported length of boards between adjacent pairs of rollers being not more than five feet, and the spacing between the rollers in each pair being such that substantially no compressive force is applied to the correctly sawn boards moving between the rollers, whereby the boards set in a straightened condition and cupping, bowing twisting or springing of the boards is substantially prevented.
  • the method of claim 4 including the step of maintaining temperatures of C and a relative humidity of at least 35 percent in said control sections.
  • a method of drying boards in which the boards are heated to reduce the moisture content to the desired final level including: the step of passing the boards between pairs of rollers arranged to hold the boards in a fixed plane during that part of the drying process after the fibre saturation point of the boards has been reached, the unsupported length of boards between adjacent pairs of rollers being not more than 5 feet, each pair of the rollers being resiliently biased toward one another, the biasing force urging the rollers together being such that substantially no compressive force is applied to the correctly sawn boards moving between the rollers, whereby the boards set in a straightened condition and cupping, bowing, twisting or springing of the lumber is substantially prevented.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Drying Of Solid Materials (AREA)
US00855880A 1968-09-06 1969-09-08 Artificial seasoning of timber Expired - Lifetime US3744147A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB4260968 1968-09-06

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US3744147A true US3744147A (en) 1973-07-10

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US00855880A Expired - Lifetime US3744147A (en) 1968-09-06 1969-09-08 Artificial seasoning of timber

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US (1) US3744147A (enrdf_load_stackoverflow)
GB (1) GB1264318A (enrdf_load_stackoverflow)

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3958340A (en) * 1973-10-19 1976-05-25 Jess Edward Meyers Method and apparatus for drying wigs
US5162629A (en) * 1991-01-18 1992-11-10 Production Machinery, Inc. Radio-frequency veneer dryer
US5423260A (en) * 1993-09-22 1995-06-13 Rockwell International Corporation Device for heating a printed web for a printing press
US20030189039A1 (en) * 1998-06-09 2003-10-09 Peter Vinden Method for increasing the permeability of wood
US7676953B2 (en) * 2006-12-29 2010-03-16 Signature Control Systems, Inc. Calibration and metering methods for wood kiln moisture measurement
US20110056087A1 (en) * 2009-09-04 2011-03-10 Tinsley Douglas M Dual Path Kiln Improvement
US7963048B2 (en) * 2005-05-23 2011-06-21 Pollard Levi A Dual path kiln
US7987614B2 (en) * 2004-04-12 2011-08-02 Erickson Robert W Restraining device for reducing warp in lumber during drying
WO2015058027A1 (en) * 2013-10-17 2015-04-23 Triglia Joseph P Jr System and method of removing moisture from fibrous or porous materials using microwave radiation and rf energy
US9709415B2 (en) 2004-12-31 2017-07-18 Google Inc. Transportation routing
US10619921B2 (en) 2018-01-29 2020-04-14 Norev Dpk, Llc Dual path kiln and method of operating a dual path kiln to continuously dry lumber
US11143454B2 (en) 2013-10-17 2021-10-12 Joseph P. Triglia, Jr. System and method of removing moisture from fibrous or porous materials using microwave radiation and RF energy
US11384980B2 (en) 2013-10-17 2022-07-12 Joseph P. Triglia, Jr. System and method for reducing moisture in materials or plants using microwave radiation and RF energy
FR3151080A1 (fr) * 2023-07-13 2025-01-17 Innovation & Development Company Dispositif à micro-ondes pour l’extraction et le séchage en continu de produits organiques solides

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3474544A (en) * 1967-07-07 1969-10-28 Coe Mfg Co The Veneer dryer with plural treating zones

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3474544A (en) * 1967-07-07 1969-10-28 Coe Mfg Co The Veneer dryer with plural treating zones

Cited By (23)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3958340A (en) * 1973-10-19 1976-05-25 Jess Edward Meyers Method and apparatus for drying wigs
US5162629A (en) * 1991-01-18 1992-11-10 Production Machinery, Inc. Radio-frequency veneer dryer
US5423260A (en) * 1993-09-22 1995-06-13 Rockwell International Corporation Device for heating a printed web for a printing press
US20030189039A1 (en) * 1998-06-09 2003-10-09 Peter Vinden Method for increasing the permeability of wood
US6742278B2 (en) * 1998-06-09 2004-06-01 The University Of Melbourne Method for increasing the permeability of wood
US7987614B2 (en) * 2004-04-12 2011-08-02 Erickson Robert W Restraining device for reducing warp in lumber during drying
US11092455B2 (en) 2004-12-31 2021-08-17 Google Llc Transportation routing
US9709415B2 (en) 2004-12-31 2017-07-18 Google Inc. Transportation routing
US9945686B2 (en) 2004-12-31 2018-04-17 Google Llc Transportation routing
US9778055B2 (en) 2004-12-31 2017-10-03 Google Inc. Transportation routing
US7963048B2 (en) * 2005-05-23 2011-06-21 Pollard Levi A Dual path kiln
US8104190B2 (en) 2006-12-29 2012-01-31 Signature Control Systems, Inc. Wood kiln moisture measurement calibration and metering methods
US7676953B2 (en) * 2006-12-29 2010-03-16 Signature Control Systems, Inc. Calibration and metering methods for wood kiln moisture measurement
US8201501B2 (en) 2009-09-04 2012-06-19 Tinsley Douglas M Dual path kiln improvement
US8342102B2 (en) 2009-09-04 2013-01-01 Douglas M Tinsley Dual path kiln improvement
US20110056087A1 (en) * 2009-09-04 2011-03-10 Tinsley Douglas M Dual Path Kiln Improvement
WO2015058027A1 (en) * 2013-10-17 2015-04-23 Triglia Joseph P Jr System and method of removing moisture from fibrous or porous materials using microwave radiation and rf energy
US9879908B2 (en) 2013-10-17 2018-01-30 Triglia Technologies, Inc. System and method of removing moisture from fibrous or porous materials using microwave radiation and RF energy
US10533799B2 (en) 2013-10-17 2020-01-14 Joseph P. Triglia, Jr. System and method of removing moisture from fibrous or porous materials using microwave radiation and RF energy
US11143454B2 (en) 2013-10-17 2021-10-12 Joseph P. Triglia, Jr. System and method of removing moisture from fibrous or porous materials using microwave radiation and RF energy
US11384980B2 (en) 2013-10-17 2022-07-12 Joseph P. Triglia, Jr. System and method for reducing moisture in materials or plants using microwave radiation and RF energy
US10619921B2 (en) 2018-01-29 2020-04-14 Norev Dpk, Llc Dual path kiln and method of operating a dual path kiln to continuously dry lumber
FR3151080A1 (fr) * 2023-07-13 2025-01-17 Innovation & Development Company Dispositif à micro-ondes pour l’extraction et le séchage en continu de produits organiques solides

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Publication number Publication date
GB1264318A (enrdf_load_stackoverflow) 1972-02-23

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