GB847515A - Improvements in or relating to the production of prefabricated concrete structural members - Google Patents

Abstract

847,515. Casting concrete beams. ALWEG-FORSCHUNG G.m.b.H. Feb. 15, 1957 [Feb. 18, 1956], No. 5234/57. Class 87(2). A concrete beam may be cast curved, Fig. 2, by applying forces to the side walls 23 of the mould through adjustable horizontal elements 25 backed by reinforced concrete pillars 21. A core 24 is in two parts each of which is inserted from one end. A twist may be imparted to the beam by varying the adjustment of the higher elements 25 with respect to the lower, the bottom of the mould being shaped in conformity. A mould base 22 is moveable between the pillars 21, on wheels 30 running on a track 31 which can be raised and lowered by hydraulic cylinders 32, Fig. 7. The mould base comprises a rigid frame 42 which carries, between the mould walls 23, planking 43 covered with sheet metal 44, this construction permitting the bottom of the mould to be bent. The beam is moulded upside down, and if intended for a mono-rail structure the face to which the rail is to be fixed is shaped by the bottom of the mould. A cover for the mould is carried by a structure 37 which may be raised and lowered by an arrangement involving pulleys 36 mounted as shown on a frame 35. Alternatively, the superstructure and mould cover may be dispensed with and the top face of the casting shaped by a scraper. A wheeled truck 40 for concrete can travel on rails 39. Each of the retaining elements 25, Fig. 13, has ball ends 90 fitting at one end in a socket on a bar 28, reinforcing the side wall 23 of the mould, and at the other end in a socket at the end of a cylinder 85 inside a bushing 81 and threaded through its base 88 by a spindle 89. The spindle is grooved at 94 and a forked slide 92 can engage the groove and hold the spindle against axial movement. When the slide is raised out of the groove by a catch 52 the spindle 89 and cylinder 85 can be moved axially as a whole to give course adjustment ; the slide engages the groove when in alignment and accuracy of adjustment is then secured by turning the screwed spindle, the end of which is squared at 41 or fitted with a hand-wheel. A gauge rod 95 and optical fitting 96 provide a visual indication of the adjustment. To cast a beam which, besides being curved, is also twisted, the bottom of the mould may be shaped by using specially shaped planks 43 or by using adjusting spindles 60, Fig. 12, engaging the threaded nuts of hand-wheels 61, whereby the slope of transverse members 59 on which the base sheet 44 is carried may be manipulated. Each half of the core 24 is guided and positioned by rollers 71, 72 which are mounted in framelike inserts 64, 65, Fig. 10, which are clamped between the side walls 23 of the mould by bolts 70 in flanges 69 hooked over the wall edges, Fig. 12. The cores are accurately positioned by supports 48, Fig. 7, adjustable by hand wheels 29. To withdraw the core halves from the cast beam a hydraulic device may be used, adapted for introduction into the hollow core and fitted with supporting arms adapted to bear against the sides of the mould. The mould walls may be lined with wire netting carrying a layer of felt to permit air and water to be sucked away through flexible piping. A shaft may be arranged in the hollow interior of the core carrying out-ofbalance weights to impose vibration. Vibrators 34 are also raised by hydraulic means 33, Fig. 7 when concrete is poured into the mould. Shaker members may also be traversed along the top of the walls. Cage-like reinforcement, not shown, is placed on the mould base, which is positioned between the mould walls. The rails 31 are lowered and the base then rests on shoulders 45 of the pillars 21. The core is then inserted and the inserts 64, 65 removed. The shape of the mould is adjusted by the elements 25 and the spindles 60 and the beam is cast. When the core has been removed the side walls are retracted and the base frame is pulled out on its rails and withdrawn from under the cast beam, which is left supported on chocks while the setting of the concrete is completed.