GB1322953A - Timber grading machine - Google Patents

Abstract

1322953 Grading timber COOK BOLINDERS Ltd 19 Oct 1970 49620/70 Headings G1N and G1S A timber grading machine includes two pairs of opposed conveyors 20, 23, 19, 22 with flat surfaces for feeding and damping timber therebetween, one of the surfaces of each pair being arranged in a common plane, there being a deflecting member 35 between the two pairs for deflecting the timber by a given amount and means 38 for sensing the force applied against the deflecting member by the timber as it passes through the machine. As described three driven chain track conveyors 18, 19, 20 move a piece of timber through the machine, and three further track conveyors 21, 22, 23, urged downwardly by air bags 30, 31, 32 maintain the timber in contact with the driven conveyors. Conveyors 21, 22, 23 are lightly driven merely to maintain their rotation in step with that of the driven conveyors 18, 19, 20. Rollers 35, 39 on levers 36, 40 pivoted at 37, 41 respectively for limited pivoting movement protrude into the path of the timber through the machine to deflect it by an amount determined by the setting of adjusting devices such as 34 for roller 35. Guides 43, 44 direct the deflected timber back between the succeeding pair of conveyors. Load cells 38, 42 give an indication of the force exerted by the timber on the rollers 35, 39 which may be read from a control box 46. So that the signals from the two load cells may be directly compared, that from cell 38 is passed downstream at the same rate as the timber, the signal being delayed by means of magnetic recording on a drum driven at a rate proportional to the conveyors. Zones on a piece of timber giving signals below a particular value may be marked.