Patent GB-784179-A (GB)
Title: Extrusion apparatus particularly for making boards or similar shapes from comminutedmaterial and binder
IPC: B27N3/28
Filed: 1955-08-16
Abstract: 784,179. Extruding wood-resin compositions. BIBBY, R. D. Aug. 16, 1955 [Oct. 6, 1954], No. 23520/55. Class 87(2). Boards, furniture panels and similar objects are manufactured from wood chips and a thermosetting resin binder by extrusion in an apparatus which is adjustable to produce objects of different dimensions and density. The extrusion passage is confined between platens and side members which are movable and the platens are so disposed that they define entry, intermediate and trailing sections 24, 25, 26 which are respectively substantially parallel, divergent and convergent, Fig. 15. The material is rammed into the section 24, which may be very slightly convergent, where it is given the required shape and is cured in the intermediate and trailing sections 25, 26. A suitable binder material is urea-formaldehyde to which may be added an extender such as flour and lubricants. The ram drive is through a heavy flywheel 30, Fig. 5, driven by V-belts 29 from a motor 27, to a shaft 33 and thence by a bevel pinion 38 to a large bevel gear 42 on the bottom end of a vertical shaft 43 which carries an inner eccentric 46 at its upper end fixed to it by wedges 47, Fig. 4. The inner eccentric 46 is enclosed in an outer eccentric 48, Fig. 6, rotatable in a bushing 52 in a member 53 which is transversely slidable in a crosshead 54. The relative position of the inner and outer eccentrics 46, 48 is adjustable and retained by a key or wedge 50 which fits into corresponding slots 49 in the peripheries of the eccentrics. Thus the length of stroke may be adjusted. The crosshead 54 is movable longitudinally under the guidance of wheels 55 which run in grooves in crosshead guides-57 and its movement reciprocates a ram plate 60 fixed to it and carrying a ram head 61, which enters the shaping section 24, and a slide spacer 62 under the opening of a feed hopper 22. The hopper 22 is movably mounted by wheels 69 on tracks 70, upturned at their ends to limit its travel in both directions, and cleaning is thus facilitated, for which purpose a gate 73 is also provided in the hopper. The size of the feed passage from the hopper may be varied by a sliding plate 76 movable by a hand-wheel 77 through a rack and pinion. Rotary feed members 79 extend across the width of the hopper and may be as in Fig. 14, in which blades 90 project from a square shaft 89, the upper feed members rotating in the direction of the arrow, so that the longer edges 92 of the blades engage the material. One feed member 79 rotates in the opposite direction to the others to mix the material. The feed members 79 are rotated by a motor 80 through chains 83, 85, 87. The ram 60, 61 slides on the upper surface of the lower platen of a pair of platens 95 which is extended back for the purpose and the material is forced by the ram into the space between the platens, the faces of which are treated to reduce friction e.g. by chromium plating. The platens are heated by the circulation of fluid through passages 97 or by other means e.g. electrical, electronic or high frequency and are backed by insulating layers 99. The passage between the platens is closed along the sides by metal blocks extending along their length and fitting between them which are adjustable by threaded rods to vary the width of the passage. Yokes 107, which fit between lugs 108 on frame standards 109 and are secured by pins 110, hold down the upper platen 95 by removing the pins 110 on one side and using the pins 110 on the other side as pivots the yoke may be swung back and the parts thus exposed for cleaning. Fig. 11 shows means for varying the depth of the passage in which the lower platen 95 is raised or lowered by moving wedges 120 inwards or outwards. Each wedge 120 is bored for screw-threaded reception of a shaft 127 which extends through a lubricating collar 128 and bearing 129 to a square-sectioned end portion 130 for a hand-wheel or crank, whereby the shaft may be turned to screw in or out of the wedge 120 which it thus moves to lower or raise the lower platen 95. If a dog 132 on the shaft end is moved from its position shown in dotted lines in Fig. 11 to its position shown in full a pin 136 extending from it enters a hole in a wheel 138 which is connected by chain drive to similar wheels on shafts, corresponding to 127, which, by their rotation, move wedges in or out ; thus the operation of one crank or handwheel can be made to move all the wedges at once. With the dog 132 in the dotted position individual adjustment is possible. The simultaneous wedge adjustment operates also for the lower platens 153, 169 in the curing sections 25, 26. A cable 143 is led to a spring-controlled winding drum 145 to the outer face of which is fixed an indicator dial 149 on which, in conjunction with a pointer 150 frictionally engaged to its shaft 146, indicates the relative positions of the wedge and lower platen. In the section 24, where the pressure is greater, friction between the co-operating wedge surface is reduced by a series of rollers 123, but in the other two sections suitable metal facing plates are adequate. The delivery ends of the upper and lower platens 169, or both, may be resiliently pressed to cause a convergence towards the exit, e.g. by coil springs surrounding projecting rods 171 and compressed between collars on the rods and U-shaped retainers 174, and the pressure may be adjusted by altering the position of the collars. Alternatively pneumatic cylinders may be used, with relief valve adjustment. The machine may be adjusted to produce slabs of different sizes by lateral adjustment of the edge blocks or by replacing them by edge blocks of different dimensions. While three platen sections are required, either the lower or the upper platen may be unitary. The separate sections may be joined by hinges. The platens may be curbed or otherwise shaped across their width to extrude non-rectangular shapes. Longitudinal passages may be formed in the extruded products.