Patent GB-652507-A (GB)
Title: Machines for treating wood surfaces
IPC: B24B7/12
Filed: 1948-10-14
Abstract: 652,507. Wire-brushing wood surfaces; rotary brushes. DEHN, S. G. (Davidson Plywood & Lumber Co.). Oct. 14, 1948, No. 26780. [Classes 19 and 60] A machine for treating the surfaces of wooden products includes a plurality of rotatable brushes adapted to engage the surfaces of the products which are moved by conveyer means past said brushes, said brushes being arranged in group formation contiguous to the path of movement of the conveyer means, their axes of rotation being disposed at oblique angles to said path. The machine is particularly used to accentuate the grain, e.g. of plywood panels, the brushing removing the soft surface fibres and leaving the hard fibres outstanding in sharp relief ; the outstanding hard fibres may be polished by the brushing. A machine comprises cylindrical wire brushes 16, each rotated by an individual motor 17, arranged in a sequence of groups 25-30 along the longitudinal axis of a frame 18 above a conveyer belt 19. The successive groups of brushes are oppositely inclined, e.g. at 30 degrees to the line of travel of the workpieces. The brushes in each group are set so as to overlap slightly. Each brush 16 has an internal sleeve 43 slidably fitting a shaft 42 and retained thereon by pins 44 engaging notches 45 so that the brush can be turned end for end to equalize wear; the shaft 42 is journalled in bearing boxes 41 supported by brackets 40 on a carrier plate 35 vertically adjustable, by screw 37, on a flanged plate 33 bolted to a support bar 32 secured diagonally to the machine frame 18. The plate 33 has raised slideways 34 for the plate 35, and a rib 49 on the plate 35 slides in a way 50 in the plate 33. The vertical adjustment serves for compensation of wear of the brush and for accommodating work of different thickness; the plate 35 is secured in adjusted position by locking bolts 38. The groups may be adjusted so that they scour progressively to a greater depth, the last group 30 being set so close to the work that they polish rather than scour. Each shaft 42 carries a V-Belt pulley 48 driven through V-belt 53 by a motor 17. The motors 17 are staggered vertically so that they can be disposed directly above their respective brushes. Each motor 17 is secured to the machine frame 18 by a floating mounting 54 having at one end trunnions 55 pivoted in brackets 56, the opposite end of the mounting being supported on compression springs 57, the tension thus applied to the belts 53 being limited by bolts 58 threaded in members 59. The motors 17 are preferably reversible, and in each group of brushes the brushes disposed mainly on one side of the centre line of the conveyer belt rotate oppositely to those disposed mainly on the other side of said centre line, thus minimizing sideways thrust on the work piece; the brushes in group 25 rotate oppositely to those corresponding brushes in group 25, the brushes in group 27 rotate in the same direction as the corresponding brushes in group 26, the brushes in group 28 rotate oppositely to the corresponding brushes in group 27, the brushes in group 29 rotate in the same direction as the corresponding brushes in group 28, and the brushes in group 30 rotate oppositely to the corresponding brushes in group 29. This provides a variety of angles of attack of the bristles on the workpiece, and ensures thorough scouring out of the soft fibres. Further, after the machine has been in operation for some time the bristles acquire a non-radial set and lose efficiency; all the motors 17 are then reversed simultaneously so that the bristles are again presented efficiently. The conveyer belt 19 passes around a drum 62 at the outlet end of the machine, around a take-up pulley 63, and around a pulley at the intake end of the machine. The drum 62 is driven from a variable speed mechanism 65 in turn driven by V-belts 66 from a suitable power source. The conveyer belt 19 passes between pairs of rollers which support it and hold the work in place upon it. The lower rollers 71 are fixed in relation to the machine frame 18; the upper rollers 72 are movable vertically to accommodate workpieces of various thicknesses, their journals 73 rotating in journal boxes 74 secured to slide bars sliding in guides 76. The upper ends of the slide bars are pivotally secured to lever arms 77, pivoted at 79 on brackets 80, and carrying weights 78. Movement of the lever arms 77 is limited by adjustment screws 81 threaded in frame members 82. Specification 652,508 is referred to.