1 / 16

Lumber Manufacturing---Debarking

Lumber Manufacturing---Debarking. Purpose—Increase value of byproducts -- Scrapes and edgings → chips without bark → pulp --Bark particles → burn (energy) Types of debarkers --Drum debarker: removing bark from pulp logs --Ring debarker: removing bark from saw- and veneer logs

darcie
Télécharger la présentation

Lumber Manufacturing---Debarking

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Lumber Manufacturing---Debarking • Purpose—Increase value of byproducts --Scrapes and edgings→ chips without bark → pulp --Bark particles → burn (energy) • Types of debarkers --Drum debarker: removing bark from pulp logs --Ring debarker: removing bark from saw- and veneer logs --Pole shaver: shave bark off utility poles

  2. Drum Debarker • To remove bark from pulp logs Corrugated interior tumbles the logs and scrapes off bark; logs rub against each other to knock off bark; water shower softens bark and washes bark out of the drum. Because of gentle rubbing action very little removal of quality fibers from surfaces.

  3. Ring Debarker • To remove bark from saw- and veneer-logs Logs are centered in a ring of rosser heads with projecting teeth; bark is removed with a pressure about 30 to 50 psi. Bark is removed at high speed with substantial surface removal of wood but does not affect lumber or veneer yield.

  4. Pole Shaver • To move bark from utility poles to obtain smooth surfaces Pole rotates as it passes under a floating peripheral-milling cutterhead, removing the bark with a minimum of wood loss and retaining the natural taper.

  5. Primary Breakdown—Head saws • Band saw: Able to handle large logs, provide straight cuts and thin saw kerf increase lumber yield. • Circular saw: Saw diameter limits log sizes, thick saw blades for stability (1/4”) large saw kerfs reduces lumber yield.

  6. Saw Mills • Scragg Mills Consists two or four circular saws on a common arbor. Distance between blades can be adjusted to produce 4-, 6-, or 8-inch cants. The logs are commonly moved through saws by a conveyor. • Multiple Band Mills Similar to scragg mills except that breakdown is done by 2 or more opposing bandsaws, producing two slabs and one cant if two bands are used. • Chipping Headrigs Logs pass through a set of side cutterheads to remove excess wood into chips, followed by another set of top/bottom cutter- heads to produce a cant. Chips are to be used for pulp & paper.

  7. Chip-N-Saw Designed to process small straight Logs 6 to 16 inches in diameters. Logs first pass through two pairs side and top/bottom) chipping cutterheads to square or shape logs, followed by passing the cant through a series of circular saws mounted on a common arbor to produce multiple pieces lumber.

  8. High-Tech Mills • BOF (Best Opening Face) For high efficiency: Electronic hardware (scanner & computer) and good computer software; machine that is able to position logs quickly & saw accurately with thin kerf.

  9. Resawing • Ripping—Ripping is to saw lumber along the grain. Slabs produced by headrigs are cut with a pair of circular saws (called an edger) to square the edges to a specific width simultaneously. Large slabs are rip into multiple pieces with a series of circular saws mounted on a common arbor (gang saws). • Rough trimming—Trimming is to saw lumber across the grain to a specific length. Rough trimming follows the ripping to cut green lumber into pre-determined lengths, usually done with a pair of hollow ground circular saws.

  10. Sorting & Drying • Sorting—This operation is to sort cut lumber into different grades, species or species groups, thickness, length and sometimes according to moisture content. • Drying (seasoning) --Reasons to dry : Seasoned wood is dimensionally stable Dry wood is durable against inscets & decay Dry is stronger --Air-dried lumber: moisture content >15% ≤19% --Kiln-dried lumber: moisture content ≤15%

More Related