GB1005312A - Control apparatus for a hydraulic flash-butt welding machine - Google Patents

Abstract

1,005,312. Hydraulic control apparatus. H. A. SCHLATTER A.G. Oct. 23, 1961 [Oct. 26, 1960], No. 37845/61. Heading F1P. [Also in Division B3] Control apparatus for a flash-butt welding machine having at least one hydraulic ram for forward feed of the work comprises a main valve controlling a conduit from the ram return space to an outlet, a hydraulic fluid pressure operated cylinder and piston device operatively connected to the main valve for forcing it on to its seat, and conduit connections for the cylinder by which its working space can be connected to a source of hydraulic fluid pressure. A pair of pistons 3, 4 in cylinders 1, 2 are connected to the movable carriage of the welder, the working spaces 7, 8 communicating through a conduit 9 with a cylinder 10, the larger face of the differential piston therein being connected to a supply of compressed air or to atmosphere by a magnetically-operated valve 17 and the conduit 9 and the smaller face of the piston being connected to a hydraulic fluid source through a magnetically operated valve 13 and non-return valve 12. The return spaces 23, 24 of cylinders 1, 2 communicate through a conduit 25 with a device 20 including a main valve 22 connected to a piston 21 in a cylinder 20a in turn connected to a piston 37 in a cylinder 20b. The conduit 25 is connected to a slow discharge conduit 35 and via the valve 22 to a low pressure discharge conduit 32. The working space of cylinder 20a is connected through a magnetically-operated valve 27 with the conduit 25 or with the space 31 in contact with conduit 32. In operation hydraulic fluid is supplied through valve 13 to cause pistons 3, 4 to slowly advance the work during flashing, the fluid in spaces 23, 24 discharging through conduit 35. The said fluid acts on the valve 22 and through conduit 28 and valve 27 acts on the working face of piston 21 which has a larger effective area than that of the valve and so retains the valve closed. The valve 17 is operated to supply air to the large face of the differential piston in cylinder 10 which causes extra pressure to be applied to pistons 3, 4. The valve 27 is operated to place the working space of cylinder 20a in communication with the space 31 and valve 22 is thus moved rapidly to the left so that the work parts are rapidly abutted when fluid from spaces 23, 24 escapes to conduit 32. After welding hydraulic pressure is supplied via conduit 33 to return the pistons 3, 4 and compressed air is supplied to cylinder 20b to return valve 22.