US2995164A - Method for decorticating logs - Google Patents

Method for decorticating logs Download PDF

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Publication number
US2995164A
US2995164A US668981A US66898157A US2995164A US 2995164 A US2995164 A US 2995164A US 668981 A US668981 A US 668981A US 66898157 A US66898157 A US 66898157A US 2995164 A US2995164 A US 2995164A
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Prior art keywords
logs
decorticating
drum
container
containers
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Expired - Lifetime
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US668981A
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English (en)
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Bott Rudolf
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Individual
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Individual
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Priority to DEP11592A priority Critical patent/DE1014733B/de
Priority to FR1159603D priority patent/FR1159603A/fr
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Priority to US668981A priority patent/US2995164A/en
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
    • B27L—REMOVING BARK OR VESTIGES OF BRANCHES; SPLITTING WOOD; MANUFACTURE OF VENEER, WOODEN STICKS, WOOD SHAVINGS, WOOD FIBRES OR WOOD POWDER
    • B27L1/00—Debarking or removing vestiges of branches from trees or logs; Machines therefor
    • B27L1/02—Debarking or removing vestiges of branches from trees or logs; Machines therefor by rubbing the trunks against each other; Equipment for wet practice
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
    • B27M—WORKING OF WOOD NOT PROVIDED FOR IN SUBCLASSES B27B - B27L; MANUFACTURE OF SPECIFIC WOODEN ARTICLES
    • B27M1/00—Working of wood not provided for in subclasses B27B - B27L, e.g. by stretching
    • B27M1/02—Working of wood not provided for in subclasses B27B - B27L, e.g. by stretching by compressing

Definitions

  • the present invention relates to a new method and apparatus for decorticating logs, particularly when the lumber is to be used for producing fibrous materials.
  • the customary method of softening the cambium zone of the logs by floating the logs for a long time in water may be adequate for some types of lumber and may sometimes permit a relatively easy removal of the bark without any great loss in wood, many other types of lumber will resist such simple treatment. In all such cases it is necessary to subject the lumber to a special preliminary treatment to soak and soften the cambium zone of the logs sufiiciently so that it will no longer retain the bark as tenaciously on the wood and permit the bark to be easily stripped off the logs in the subsequent mechanical process. When the bark is to be completely stripped from the logs without first subjecting them to such preliminary treatment, the loss of a considerable amount of valuable wood is unavoidable.
  • Such special soaking treatment to soften the cambium zone of the lumber must, however, comply with certain conditions. Primarily it is necessary to make the soaking period as short as possible as otherwise the whole decorticating process will be uneconomical. Furthermore, especially on logs which are to be used for producing fibrous materials, the soaking operation must be carried out to such an extent that the bark may be removed from the logs completely and economically, and without leaving thereon any residue Worth mentioning. Last but not least, it must be carefully observed that during the soaking process the logs themselves will absorb as little as possible of the turbid or coloring substances dissolved from the bark by the liquids or the steam condensate used in the process since this would affect the degree of whiteness of the fibrous materials to be made of the logs.
  • the present invention also relies upon the basic method of inserting precut log sections into closed containers and soaking and softening the cambium zoneof the logs by means of moist heat, and of thereafter stripping the bark from the logs, it is distinguished from the known methods by subjecting the log sections in the different containers for a considerable length of time, for example, for 3 to 8 hours, depending upon the type of Wood, to the influence of water to which in certain cases chemical neutralizing agents may be added, and which in the course of the treatment is heated to a temperature of to 105 C., and preferably to to C., and by thereafter removing the bark from the logs while in a hot and moist condition in a decorticating drum of a type known as such.
  • An important feature of the invention is also the fact that only a relatively small quantity of water, preferably about 0.1 cubic meter per each cubic meter of stacked timber, has to be circulated through each container.
  • the operation of the method according to the invention may be carried out at a maximum of economy if the apparatus is provided with a plurality of pretreatment containers, the number of which corresponds to the quotient of the time required for soaking the cambium zone of the lumber and the time required for decorticating one charge of lumber in the decorticating drum.
  • the containers are thus filled one after the other with a charge of timber, and the time required for each filling operation and the interval between successive filling operations is gauged as as to correspond to the length of time required for one complete operation of the decorticating drum on one such charge of logs.
  • the drum used according to the invention may be of a type known as such.
  • the logs before being decorticated were heated by means of hot water or steam.
  • the hot water then leached out the bark and took up the coloring substances therefrom.
  • This colored water was then absorbed by the Wood of the logs, thereby discoloring or darkening the wood so that its value for a subsequent production of fibrous material was considerably reduced.
  • this disadvantage may be overcome by first treating each charge of logs in a separate container by means of water of a relatively low temperature so that the outer portions of the logs will be saturated with clear water, the coloring substances will not be leached out of the bark, and the fibers of the wood will not become discolored.
  • Another important feature of the new method is its low consumption of water, which, for example, amounts to no more than /5 to A of the quantity required by previous methods. Furthermore, the final production output of an apparatus according to the invention is much higher than that of one of the known apparatus of similar size.
  • the superiority of the new method both insofar as its rate of output, the quality of the decorticated lumber and the degree of decortication are concerned will be particularly apparent if the pretreatment of the logs is carried out in a plurality of containers, each of which is filled with aseparate charge of logs within the period required for one complete decorticating operation.
  • FIG. 1 shows a side view, partly in cross section, of
  • FIG. 2 shows a plan view thereof.
  • the apparatus consists primarily of a plurality of pretreatment containers 1 to 5 arranged adjacent to each other, a decorticating drum 7 which is rotatably mounted so as to be partly immersed in a container 6, and an inclined runway 8 which perm-its the decorticating drum to be quickly emptied.
  • Each of the pretreatment containers 1 to 5 has a substantially rectangular shape and has at its upper side a cover 9 which is adapted either to be pivoted upwardly or lifted up entirely to permit such chamber to be filled with logs 13.
  • each container 1 to 5 also has a discharge gate 12 which is pivotable toward the outside.
  • each container 1 to 5 supports a false bottom plate 14 which is pivotable upwardly toward the discharge :gate 12 by means of a rope, chain or the like 16 connected to its free end 15 and adapted to be drawn upwardly by a suitable draw gear, crane or the like, not shown.
  • a separate vessel 17 is provided underneath the bottom of each container and connected thereto so as to communicate with the inside thereof.
  • This vessel is adapted to receive the circulating liquid on its return from the respective container.
  • the liquid is then passed by a pump 18 from vessel 17 to a heater 19 and then through a conduit 21 to a sprinkling system 22 mounted in the upper part of containers 1 to 5.
  • Heater 19 is preferably heated by means of exhaust steam supplied under a pressure of up to- 8 atmospheres from a steam pipe 23 through a temperature control valve 24-.
  • a valve system 25 is provided between container 17 and pump 18 and connected to a feed line 26.
  • a decorticating drum 7 is mounted, operating in the usual manner known in the art.
  • a chute 27 is mounted underneath gates 12 on the frame supporting thecontainers 1 to 5 and extends entirely across these containers and at a downwardly inclined angle toward drum 7.
  • chute 27 guides the material 13 from the respective container .-1 to 5 toward and into an opening 29 in the outer wall 28 of drum 7.
  • This opening 29 may be closed by means of a cover 31 which may be lifted and lowered, for example, by a suitable hoist or the like, and should be firmly secured to drum 7 before its operation is started.
  • an inclined runway 8 is provided at one side of drum 7 consisting of two or more parallel rails 33 which extend from a point within container 6, on which drum 7 is mounted so as to dip deeply into the same, to a level above the ground from which drum 7 can be conveniently emptied through opening 29 after cover 31 has been removed.
  • suitable means may be provided, as indicated diagrammatically at 34, which may, for example, consist of a winch or the like, not shown, a pair of pulleys 36 on a common shaft 35, a pair of draw sleeves 38 over the ends of shafts 37 of drum 7, and a pair of ropes or cables connected to draw sleeves 38 and extending over pulleys 36 to the winch.
  • the individual pretreatment containers 1 to- 5 are filled alternately and at certain periodic time intervals relative to each other with the material to be treated. These time intervals are gauged so that each interval corresponds to the period of revolution of drum 7 as required for decortic-ating one charge of one of containers 1 to 5 plus the time required for filling and emptying the drum. Due to such order of succession of filling the individual containers and pretreating their charges of logs there will always be one pretreated charge ready and available in one container to be further treated in the decorticating drum 7.
  • a charge consisting of 16 cubic meters of stacked logs of medium thickness was filled into one of the containers 1 to 5 which was then closed. This required approximately 30 minutes. Approximately 1.5 cubic meters of water of a temperature of about 45 C. was then filled into the container and circulated therethrough. With-in 45 minutes of such circulation the water was heated to a temperature at the discharge point of 90 C. and maintained at such temperature for 4 hours. The logs were then removed from the container and dumped into the decorticating drum 7. This operation required approximately 3 minutes. The logs were removed from drum 7 substantially clean of any residue of bark and then either subjected to further treatment or stacked.
  • the decorticating drum 7 could always be refilled with a new charge of soaked logs immediately after it was emptied of the previous charge. Accordingly, a charge of soaked logs is introduced into the decorticating drum every 80 minutes.
  • the total output of the five containers of the decorticaiting apparatus within a period of 24 hours amounted to 280 to 300 cubic meters of stacked logs at a tot-a1 water consumption of about 0.08 cubic meter of water per each cubic meter of stacked lumber.
  • the degree of whiteness of the unbleached wood fibers of the logs as measured by a photoelectric meter, a so-called photo volt meter, was about 3.5% higher than the degree attainable with the conventional processes in which the logs were treated with steam and cold Water.
  • a method of decorticating logs of any shape comprising the steps of first saturating the outer layers of the logs in a watery liquid of relatively low temperature substantially without bleaching out any coloring substances of the bark so that said liquid will remain substantially clear and will not discolor the Wood of said logs, then gradually heating said watery liquid to a temperature near the boiling point and maintaining such temperature for a period of approximately four to ten hours, and immediately thereafter removing the bark from said logs by the action of frictional forces while the logs are still in a hot and moist condition.
  • a method of decorticating logs of any shape comprising the steps of first saturating the outer layers of the logs in a watery liquid, then gradually heating said liquid to a temperature near the boiling point and maintaining such temperature for a period of 4 to hours, depending upon the particular type of wood, and immediately thereafter inserting the logs into a decorticating drum and removing the bark from the logs in said drum while said logs are still in a hot and moist condition.
  • a method of decortica-ting logs of any shape in a continuous operation comprising the steps of periodically inserting separate charges of logs into a plurality of containers at spaced time intervals, saturating the outer layers of the logs in each container in a watery liquid of a rela tively low temperature, then gradually heating said watery liquid to a temperature near the boiling point and maintaining such temperature in each container for a period of approximately four to ten hours depending upon the particular type of wood, then subjecting the charge of logs of the first container to a decorticating process immediately after being removed from said container and While still in a hot and moist condition, immediately thereafter subjecting the charge of logs of the second container to said decortica-ting process, continuing such operation with the charges of the remaining containers, and successively refilling the emptied containers and pretreating the logs therein while the charges of the other containers are being deconticated.
  • a method of decorticating logs of any shape in a continuous operation comprising the steps of periodically inserting separate charges of logs into a' plurality of containers at spaced time intervals, saturating at least the outer layers of the logs in each container in a watery liquid at a temperature of approximately 45 C., then gradually heating said watery liquid to a temperature near the boiling point thereof and maintaining such temperature in each container for a period of 4 to 10 hours, depending upon the particular type of wood, then subjecting the charge of logs of the first container to a decorticating process by first removing the pretreated logs from said first container, inserting said charge directly into a decortieating drum, and immediately thereafter removing the bark from the logs in said drum while still in a hot and moist condition, and then emptying said logs from said drum, immediately thereafter filling said drum with a second charge of logs from the second container and decorticating said logs, then while continuing such operation with the charges of the remaining containers periodically refilling the containers from which the logs have been removed and pret

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  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Wood Science & Technology (AREA)
  • Forests & Forestry (AREA)
  • Mechanical Engineering (AREA)
  • Chemical And Physical Treatments For Wood And The Like (AREA)
US668981A 1957-07-01 1957-07-01 Method for decorticating logs Expired - Lifetime US2995164A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
DEP11592A DE1014733B (de) 1957-07-01 1954-03-22 Verfahren und Anlage zur Entrindung von Holzstaemmen
FR1159603D FR1159603A (fr) 1957-07-01 1956-06-04 Procédé pour l'écorçage de rondins de bois
US668981A US2995164A (en) 1957-07-01 1957-07-01 Method for decorticating logs

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US668981A US2995164A (en) 1957-07-01 1957-07-01 Method for decorticating logs

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US2995164A true US2995164A (en) 1961-08-08

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DE (1) DE1014733B (fr)
FR (1) FR1159603A (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5103883A (en) * 1989-12-27 1992-04-14 Kone Oy Method for the debarking of logs
US5505240A (en) * 1995-03-15 1996-04-09 The Failure Group, Inc. Method and apparatus for the treatment of logs

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1402138A (en) * 1920-03-27 1922-01-03 Berkey George Phelps Method and apparatus for loosening bark from pulp wood
US2038658A (en) * 1932-07-30 1936-04-28 Wikmanshytte Bruks Aktiebolag Method and apparatus for removing bark from timber by means of fluid jets
DE750425C (de) * 1941-11-28 1944-12-21 G M B H Maschf Vorrichtung zum Entleeren von Holzentrindungstrommeln
DE1001481B (de) * 1955-03-04 1957-01-24 Papierfabrik Frohnleiten Carl Daempfkammer fuer die Nassentrindung von Holz

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE610954C (de) * 1932-07-30 1935-03-20 Wikmanshytte Bruks Aktiebolag Verfahren und Vorrichtung zum Entrinden von Baumstaemmen

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1402138A (en) * 1920-03-27 1922-01-03 Berkey George Phelps Method and apparatus for loosening bark from pulp wood
US2038658A (en) * 1932-07-30 1936-04-28 Wikmanshytte Bruks Aktiebolag Method and apparatus for removing bark from timber by means of fluid jets
DE750425C (de) * 1941-11-28 1944-12-21 G M B H Maschf Vorrichtung zum Entleeren von Holzentrindungstrommeln
DE1001481B (de) * 1955-03-04 1957-01-24 Papierfabrik Frohnleiten Carl Daempfkammer fuer die Nassentrindung von Holz

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5103883A (en) * 1989-12-27 1992-04-14 Kone Oy Method for the debarking of logs
US5505240A (en) * 1995-03-15 1996-04-09 The Failure Group, Inc. Method and apparatus for the treatment of logs

Also Published As

Publication number Publication date
FR1159603A (fr) 1958-06-30
DE1014733B (de) 1957-08-29

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