EP0820358A1 - Mesure et tri de morceaux de bois fondes sur la densite - Google Patents

Mesure et tri de morceaux de bois fondes sur la densite

Info

Publication number
EP0820358A1
EP0820358A1 EP96911425A EP96911425A EP0820358A1 EP 0820358 A1 EP0820358 A1 EP 0820358A1 EP 96911425 A EP96911425 A EP 96911425A EP 96911425 A EP96911425 A EP 96911425A EP 0820358 A1 EP0820358 A1 EP 0820358A1
Authority
EP
European Patent Office
Prior art keywords
specific gravity
members
wood
sort
trees
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.)
Withdrawn
Application number
EP96911425A
Other languages
German (de)
English (en)
Inventor
Gevan R. Marrs
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.)
Weyerhaeuser Co
Original Assignee
Weyerhaeuser Co
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Weyerhaeuser Co filed Critical Weyerhaeuser Co
Publication of EP0820358A1 publication Critical patent/EP0820358A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B07—SEPARATING SOLIDS FROM SOLIDS; SORTING
    • B07C—POSTAL SORTING; SORTING INDIVIDUAL ARTICLES, OR BULK MATERIAL FIT TO BE SORTED PIECE-MEAL, e.g. BY PICKING
    • B07C5/00—Sorting according to a characteristic or feature of the articles or material being sorted, e.g. by control effected by devices which detect or measure such characteristic or feature; Sorting by manually actuated devices, e.g. switches
    • B07C5/34—Sorting according to other particular properties

Definitions

  • This invention relates generally to sorting wood members, such as, trees or logs within a collection of such members based on measuring each member's specific gravity and allocating each member to a sort category based on the specific gravity.
  • wood raw materials (trees, bucked logs, lumber, chips) having variable specific gravities or densities can be allocated to different end uses based, at least in part, on the density. For example, in manufacturing lumber when higher strength is sought, the sawmill will seek to cut denser logs (higher specific gravity) since denser wood will yield stronger lumber. In using wood chips to produce pulp and paper products it is known that certain product grades will accommodate less dense wood while other grades require denser wood.
  • the present invention involves the recognition that there is tree-to-tree variation in specific gravity in a collection of trees coming from the same growing region, as well as from a plurality of growing regions, the location of wood from within the tree, and the age of the tree. While others have sorted groups of trees and/or parts of trees based on their expected (or predicted) average specific gravity, it has not been suggested that each member within a collection should have its specific gravity detected and sorted according to its individual measurement. According to accepted convention, the forest products industry defines
  • specific gravity or "wood specific gravity” as the ratio of the mass of dry wood to its green wood volume (expressed as the mass of water displaced by that volume). Because of the amount of absorbed water in green wood, wood specific gravity is roughly half that of its actual specific gravity, whose scientific definition is the ratio of its density (mass divided by volume at the same state) to the density of water. In this description the term “specific gravity” will mean “unextracted wood specific gravity” (i.e., wood specific gravity, including the mass of extractives like lignin).
  • Older trees (20+) are harvested to create the raw material source for chips going to the production of the fluff pulp grades, where the average specific gravity will be about 0.46.
  • an allocation of tree tops, cores (from peeling veneer), and the younger harvested trees (usually thinnings) will go to the lower specific gravity sort while the outer, basal, older age trees, and sawmill residual chips will go to the higher specific gravity sort. Since individual logs are not measured to detect their particular specific gravities before allocation in a pulp manufacturing setting, the difference in average specific gravity of any two or more sorts will be less than it could be if individual logs or log segments were measured and allocated according to their particular specific gravities.
  • one object of the invention is to measure and allocate to a specific gravity sort category substantially all members of a population of available logs or trees.
  • Another object is to provide specific gravity sort categories with more absolute differences between sorts.
  • a further object is to increase and/or decrease the average specific gravity of members within the predetermined sort categories.
  • the invention is practiced in one form by measuring the specific gravities of a collection of individual wood members, such as logs, where each member is then allocated to a sort category based on its measured specific gravity. Thereafter requirements of the end uses will serve to determine demand for the members in each of the sort categories.
  • Figure 1 is a schematic representation illustrating the collection of individual wood members and transport to a central measuring and sorting site.
  • Figure 2 is a schematic representation of a pulp mill wood yard where the present invention is illustrated and used to form chip piles with each having a predetermined average wood specific gravity.
  • Figure 3 illustrates a device for providing a measure of a log's specific gravity.
  • FIG. 1 what is shown is a pulp and paper manufacturing facility typical of one presently existing in North America and the geographical territory surrounding it from which will come the trees harvested to provide the wood raw material. While many pulp mills are utilizing recycled wood fiber as a portion of their raw material requirement, most all rely primarily on surrounding commercial timberlands. From the ti berlands, whether owned and managed by the pulp mill owner, or owned by others will come the trees that are transported to the pulp mill.
  • harvesting plans are developed that can take into account the variable specific gravities within the stands of trees with the potential to be harvested. Of course, age, size, species and other factors will be considered.
  • a pulp mill continuously acquires raw material, it can acquire whole trees from timberlands (either from fee ownership or contracted timber), logs from logging contractors with their source of timber, or wood chips from outside suppliers. Ultimately this raw material arrives at the mill site for processing. Typically the full length trees will need to be cut into suitable lengths for subsequent handling and processing. Very typically when the site is for pulp and paper processing the trees and long logs will be cut into 4 and 8 foot segments. These are then debarked and sent to chipping stations where wood chips are produced. The wood chips then become the raw material for pulp digesters where they are "cooked” in order to delignify them and generate the wood pulp fibers.
  • Trees and logs from all sources are delivered to a log yard where they can be stored and/or sorted according to known typical categories such as size and species.
  • the pulp mill calls for chips with properties determined by the products selected for production, normally they are conveyed from a chip pile having a collection of chips with the desired properties, such as species, specific gravity, etc.
  • the present invention interposes a specific gravity measurement and allocation step for each member of the log population to be converted into chips. After all long trees and logs are converted into the standard length for further processing, in a process step referred to as "slashing," each individual member will have its specific gravity determined at a specific gravity measuring station. Thereafter debarking and chipping take place.
  • the average specific gravity in the low density pile can be decreased to 0.42 and raised in the higher density pile to 0.49 thereby providing sources of chips more beneficial to those selected products favoring relatively higher or lower wood densities.
  • the difference in specific gravity of piles sorted by age and site only is limited to about 0.03.
  • FIG 3 one example of a suitable device for measuring specific gravity is shown.
  • a pneumatic nail or pin gun is illustrated at 10 and can be operated at low pressure. It can rapidly imbed a reusable or disposable pin (e.g. nails) into the wood and the depth of penetration (or conversely height remaining above the surface) is correlated to specific gravity.
  • a single pin or probe would be used repeatedly, rather than being used once and disposed, and the resulting height will be automatically sensed and the log marked or otherwise sorted into the preselected specific gravity category as described above.
  • Other specific gravity detecting means could be utilized, some of which could employ electromagnetic radiation as non-contact detecting means. Such means are presently commercially available.

Landscapes

  • Paper (AREA)
  • Debarking, Splitting, And Disintegration Of Timber (AREA)
  • Chemical And Physical Treatments For Wood And The Like (AREA)
  • Veneer Processing And Manufacture Of Plywood (AREA)
  • Dry Formation Of Fiberboard And The Like (AREA)

Abstract

Un système de mesure et de tri est fondé sur la détection de la densité de chaque morceau d'une population de morceaux de bois, tels que des bûches ou arbres et sur l'affectation de chaque morceau mesuré à une catégorie de tri à laquelle est affectée une fourchette de densité. Les morceaux triés sont ensuite utilisés comme matière première pour un usage en aval selon les besoins relatifs à la densité.
EP96911425A 1995-04-12 1996-03-25 Mesure et tri de morceaux de bois fondes sur la densite Withdrawn EP0820358A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
US42219195A 1995-04-12 1995-04-12
US422191 1995-04-12
PCT/US1996/004106 WO1996032208A1 (fr) 1995-04-12 1996-03-25 Mesure et tri de morceaux de bois fondes sur la densite

Publications (1)

Publication Number Publication Date
EP0820358A1 true EP0820358A1 (fr) 1998-01-28

Family

ID=23673773

Family Applications (1)

Application Number Title Priority Date Filing Date
EP96911425A Withdrawn EP0820358A1 (fr) 1995-04-12 1996-03-25 Mesure et tri de morceaux de bois fondes sur la densite

Country Status (4)

Country Link
EP (1) EP0820358A1 (fr)
AU (1) AU5431596A (fr)
CA (1) CA2215785A1 (fr)
WO (1) WO1996032208A1 (fr)

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA1326908C (fr) * 1988-06-29 1994-02-08 Gratien Beauchemin Appareil de mesure de taux d'humidite de bois debite et methode connexe
WO1990011488A1 (fr) * 1989-03-29 1990-10-04 Visionsmart Inc. Procede et systeme de classement de bois debites en temps reel
DE4109690C2 (de) * 1991-03-23 1995-08-03 Minda Industrieanlagen Gmbh Verfahren zur maschinellen Sortierung von Nadelschnittholz
DE4209314C1 (fr) * 1992-03-23 1993-02-11 Fagus-Grecon Greten Gmbh & Co Kg, 3220 Alfeld, De

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9632208A1 *

Also Published As

Publication number Publication date
CA2215785A1 (fr) 1996-10-17
WO1996032208A1 (fr) 1996-10-17
AU5431596A (en) 1996-10-30

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