Patent GB-771397-A (GB)
Title: Concrete block forming machine
IPC: B28B3/02
Filed: 1955-03-22
Abstract: 771,397. Moulding concrete blocks. - COLUMBIA MACHINE WORKS, Inc. March 22, 1955 [April 5, 1954], No. 8367/55. Class 87(2). A concrete block forming machine comprises a mould and pallet on a resilient support, means to impart vertical vibration to the mould an impact head vertically movable to and from the mould and a fluid motor operatively joined to the impact head through flexible and resilient members, whereby the fluid motor initiates movement of the impact head towards the mould and when the motor approaches the limit of its stroke it throws the head towards the mould due to the resiliency of the members. The mould 22 is suspended from the free ends of leaf springs 23 (seen endwise in Fig. 1) through lugs 33 which fit between two leaves. Through these lugs, and through spacers between the remaining leaves, screws 31 pass with their lower ends pivotally joined to the forked upper ends of rods 35. The lower ends of the rods 35 have eccentric sheaves 35b which surround eccentrics (not shown) on a drive shaft 38, and the rods 35 therefore act as connecting rods and vibrate the mould in a movement which is substantially vertical under the constraint of the ends of the leaf springs. A ram 44 is fixed to a beam 44a and is brought down on top of the concrete in the mould by the action of hydraulic cylinders 45 with their piston rods 48 connected to the ends of the beam. In order that the ram may strike the concrete with a sharp blow the connection between the rods 48 and the beam 44a is through springs 51, fitting under a head 49, housed in pockets 50. The bottom of the mould 22 is open and the concrete (which is fed from a hopper (not shown)) is supported by a pallet 20. The pallet is supported from a pallet beam 15 from which a platform 16 projects, springs 17 between the pallet and the platform allowing for the vibration movement of the mould. Excessive rocking is prevented by adjustment screws 19. To provide for stripping the moulded block the pallet beam 15 is secured to sleeves 4 which slide on rods between fixed lugs 2, 3 and are joined by a beam 5 operated by a piston rod 6. The piston rod enters a doubleacting hydraulic stripper cylinder 7 which is secured to a bracket 8. Removable bumpers 12 backed by springs 14 are supported from flanges 9 on the bracket. The pallet beam 15 carries stops 53, with adjusting screws 54, aligned with limit pins 52 depending from the beam 44a. With the mould filled and the pallet raised to seal its bottom, hydraulic fluid is forced into the top of each cylinder 45. The initial movement of the piston rod 48 compresses its spring 51 without the beam 44a and ram 44 moving, owing to their inertia. The beam and ram later move downwards, and before they reach their bottom position the vibration of the mould is started. The motion is timed so that the spring 51 does not expand to its original position during the downward movement, and the ram strikes the material in the mould with a heavy blow and compacts it intensely, the shock to which the framework would otherwise be subjected being largely absorbed by the springs. With the ram pressing on the concrete the springs 51 expand to exert slow compression of the material following the impact, the vibration continuing, this stage ending when the limit pins 52 meet the stops 53, at which position the springs 51 are still slightly compressed. The moulded block is removed on the pallet.