Patent GB-1080876-A (GB)
Title: Continuous lamination of timber
Inventor: CARRUTHERS JOSEPH FORSYTH SCOT
IPC: B27M3/00
Filed: 1963-10-23
Abstract: 1,080,876. Woodworking. NATIONAL RESEARCH DEVELOPMENT CORPORATION. Jan. 20, 1965 [Oct. 23, 1963], No. 41902/63. Heading B5L. A method of continuously laminating timber comprises feeding pieces of timber provided with adhesive on their side surfaces in common at a predetermined speed while held under transverse pressure, the pieces of timber for the respective laminations being fed individually prior to the common feed, the individual feed being at a higher speed than the common feed but not capable of exceeding a predetermined forward pressure so that each piece is pressed against a preceding piece to form an end-to-end joint at a predetermined pressure before it reaches the zone of common feed, the joints being staggered. As illustrated in Fig. 1, the pieces of timber 12 which are thicknessed and coated with glue, are fed into an end thrust unit 11 which drives the pieces so that they abut end-to-end with a predetermined pressure, the ends being formed with finger joints, to side rollers 15 or guide plates. From the rollers 15, the pieces pass between link tracks 16, 17 which effect a bonding pressure on the pieces. Heating elements 19 are provided above and below the space between the tracks to effect drying of the glue. The end thrust unit, Figs. 2, 3 and 4 (not shown) has upper and lower driving rollers 24, 25 for engaging the upper and lower edges of the pieces of timber 12 as they pass through the unit. The pieces are initially guided over a roller 39 and aligned with preceding pieces by tongues 40, Fig. 8 (not shown), on vertical shafts 41, before being guided by rollers 43, 47 and 48 in their passage through the unit. Rollers 43 have ribs 44 which, together with longitudinally extending bars 46 and strips 45 maintain the pieces in spaced apart relationship until they have passed the first of the side rollers 15; they then pass between upper and lower rollers 44, and between the second pair of side rollers 15 which are adjusted so as to press the pieces of timber sideways against one another. Each driving roller 24, 25 is mounted on a lever 26 which is fulcrummed on a bracket 29 and connected to a further lever 28 and an air cylinder 27, whereby the rollers are pressed against the edges of the pieces of timber. The fulcrums 31 for the levers carry gears 32 which are connected by intermediate gears to the rollers, and the fulcrums 31 consist of driving shafts which, for each row of rollers, extend within one another and are connected to respective free-wheel sprockets 32. Chains 33 are entrained around each sprocket and have one end connected to a spring 35 and the other end connected to air cylinders 35, whereby the driving shaft can be rotated to drive the rollers 24, 25 during a stroke of the cylinders, the free-wheel permitting a return stroke of the cylinders under the action of the springs. The upper and lower pair of rollers 24, 25 acting on each piece of timber are so driven by the cylinders that during a driving stroke of one cylinder, the other cylinder is being returned so that the rollers are driven alternately to press its piece of timber into end-to-end abutment with a preceding piece, the pressure being controlled by the pressure in the cylinders. In other embodiments, the return stroke is effected by air pressure cylinders, or a slipping clutch device may be used in the drive to the rollers. A photo-cell device or micro-switch arrangement may be provided to control the cylinders 27 so that when the ends of a piece of timber approach the rollers, the latter are lifted from the timber to prevent damage to the finger joints. The bonding unit, Figs. 5 and 6 (not shown), presses the pieces of timber together by means of the link tracks 16, 17 which carry blocks 71 of polythene or wood and are entrained about driving pulleys 55, 57 and pulleys 56, 58 acted upon by cylinders 68. The operative run of track 16 is supported by a guide channel 59 which is slightly flexible and can be adjusted to have a camber by bolts 61 or eccentrics so that the pressed beam has a longitudinal curve. The operative run of track 17 is supported by a plurality of closely spaced channels 62, each of which is urged towards the timber by a crank 66 on a vertical shaft 65 having a second crank 64 connected to an air cylinder 63. During pressing of the pieces of timber together, the glue between the pieces is dried by dielectric heating applied through top and bottom elements 19, 22 or by microwave heating generated by a magnetron and beamed by a horn on to the pieces of timber.