Method and apparatus for debarking logs

Abstract

Apparatus request for debarking logs comprising a generally horizontal rotary drum debarker having an inlet end, power drive device for continuously rotating the drum of the debarker generally about a horizontal axis, generally horizontal main conveyor element for conveying groups of tree length logs toward the drum, the main conveyor element having a discharge end below the axis of rotation of the drum, drive apparatus for continuously driving the main conveyor element, and auxiliary feed mechanism below the axis of rotation of the drum and between the discharge end of the main conveyor element and the inlet end of the drum for assisting the movement of groups of logs fed by the main conveyor element into the inlet end of the drum. The questions raised in reexamination request No. 90/003,655, filed Dec. 7, 1994, 90/003,826 filed May 8, 1995, and 90/004,552 filed Feb. 12, 1997 have been considered and the results thereof are reflected in this reissue patent which constitutes the reexamination certificate required by 35 U.S.C. 307 as provided in 37 CFR 1.570(e).

We claim:  
     
       1. Apparatus for debarking logs comprising, 
       a generally horizontal rotary drum debarker having an inlet end,  
       power means for continuously rotating the drum of the debarker generally about a horizontal axis,  
       generally horizontal main conveyor means for conveying groups of tree length logs toward said drum, said main conveyor means having a discharge end below the axis of rotation of said drum,  
       drive means for continuously driving the main conveyor means, and  
       auxiliary feed means below the axis of rotation of the drum and between the discharge end of said main conveyor means and the inlet end of said drum for assisting the movement of groups of logs fed by said main conveyor means into said inlet end of the drum, said auxiliary feed means having a low friction region.  
     
     
       2. Apparatus according to claim  1  wherein, said low friction region is substantially at the elevation of the chain of said main conveyor, and has a length in the feed direction which is less than the diameter of the debarking drum. 
     
     
       3. Apparatus according to claim  2  wherein, 
       said low friction region comprises at least one horizontal roller, and  
       means mounting said roller for rotation.  
     
     
       4. Apparatus according to claim  1  wherein, said low friction region comprises a plurality of side by side generally coplanar horizontal rollers mounted for rotation. 
     
     
       5. Apparatus according to claim  1  wherein, said main conveyor has sides with smooth inner surfaces extending upwardly to an elevation above the centerline of the debarker drum along a length of the apparatus beginning upstream of said discharge end of the conveyor and extending along said low friction region. 
     
     
       6. Apparatus for debarking tree length logs comprising, 
       a generally horizontal rotary drum debarker having an inlet end,  
       power means for continuously rotating the drum of the debarker about a generally horizontal axis of rotation,  
       generally horizontal chain conveyor means having a conveying surface below the axis of rotation of the drum for conveying groups of tree length logs toward said drum, said main  chain conveyor means having a chain return headspool at its discharge end,  
       drive means for continuously driving the  said chain conveyor means,  
       a low friction region comprising a horizontal roller below the axis of rotation of the drum and between the discharge end of said mainchain conveyor means and the inlet end of said debarking drum, and  
       drive means for rotating said roller.  
     
     
       7. Apparatus according to claim  6  wherein said drive means for rotating said roller comprises drive means for rotating the roller independently of the drive means for driving the main  said chain conveyor means, so that the roller can be rotated at a surface speed different from the surface speed of said chain conveyor means. 
     
     
       8. Apparatus according to claim  7  wherein said drive means comprises a variable speed hydraulic motor. 
     
     
       9. Apparatus according to claim  6  wherein the distance between the discharge end of the main conveyor  said chain conveyor means and the inlet end of the debarking drum is not substantially greater than several diameters of said roller. 
     
     
       10. Apparatus according to claim  6  wherein said roller comprises a roller having a smooth exterior surface. 
     
     
       11. Apparatus according to claim  6  wherein said roller comprises a roller having circumferentially spaced apart ribs extending generally axially along its exterior surface. 
     
     
       12. Apparatus according to claim  6  wherein said main conveyor  chain conveyor means comprises a conveyor having sides with smooth inner surfaces, said sides extending upwardly to an elevation substantially higher than the elevation of the center line of the debarking drum along a length of the conveyor near the discharge end of the conveyor. 
     
     
       13. Apparatus according to claim  12  wherein said sides are substantially upright. 
     
     
       14. Apparatus according to claim  13  wherein said apparatus has an open top along substantially its entire length to permit loading logs onto the apparatus. 
     
     
       15. Apparatus according to claim  14 , further comprising, a stationary guide plate having an opening therein of a diameter not greater than the inside diameter of the debarking drum, and means mounting said plate between said roller and the inlet end of the debarking drum. 
     
     
       16. Apparatus for debarking logs comprising, 
       a generally horizontal rotary drum debarker having an inlet end,  
       power means for continuously rotating the drum of the debarker,  
       generally horizontal main conveyor means for conveying groups of tree length logs toward said drum, said main conveyor means having a discharge end,  
       drive means for continuously driving the main conveyor means, and  
       auxiliary feed means between the discharge end of said main conveyor means and the inlet end of said drum for assisting the movement of groups of logs fed by said main conveyor means into said inlet end of the drum, and wherein,  
       said main conveyor means comprises a link chain conveyor having a chain return headspool at its discharge end, and  
       said auxiliary feed means comprising means defining a low friction region of short length in the feed direction of logs and close to said headspool for preventing trailing ends of logs from catching in the return position of the chain.  
     
     
       17. Apparatus according to claim  16  wherein, 
       said low friction region is substantially at the elevation of the chain of said main conveyor, and has a length in the feed direction which is less than the diameter of the debarking column.  
     
     
       18. Apparatus according to claim  17  wherein, 
       said low friction region comprises at least one horizontal roller, and  
       means mounting said roller for rotation.  
     
     
       19. Apparatus according to claim  16  wherein, 
       said low friction region comprises a plurality of side by side generally coplanar horizontal rollers mounted for rotation.  
     
     
       20. Apparatus according to claim  16  wherein, said main conveyor has sides with smooth inner surfaces extending upwardly to an elevation above the centerline of the debarker drum along a length of the apparatus beginning upstream of said discharge end of the conveyor and extending along said low friction region. 
     
     
       21. Apparatus for debarking tree length logs comprising, 
       a generally horizontal rotary drum debarker having an inlet end,  
       power means for continuously rotating the drum of the debarker,  
       generally horizontal main conveyor means for conveying groups of tree length logs toward said drum, said main conveyor means having a discharge end,  
       drive means for continuously driving the main conveyor means,  
       a horizontal roller between the discharge end of said main conveyor means and the inlet end of said debarking drum,  
       variable speed hydraulic motor drive means for rotating said roller independently of the drive means for driving the main conveyor means, and wherein,  
       said roller comprising a shaft mounted for rotation in bearings at opposite ends of said roller, and said apparatus further comprises, a motor support outwardly of one of said bearings, means connecting said motor support to said apparatus, means mounting said hydraulic motor on said motor support, and means connecting said motor to said shaft for driving the roller in rotation.  
     
     
       22. Apparatus according to claim  21  further comprising means mounting said bearings for adjustment vertically to adjust the height of said roller, and wherein, said means connecting said motor support to said apparatus comprises a vertically adjustable clamp.