Patent GB-673357-A (GB)
IPC: B29C48/10
Abstract: 673,357. Hydraulic presses. HEPWORTH IRON CO., Ltd. Dec. 5, 1950, No. 29693/50. Class 69 (ii) [Also in Group V] The socket shaping die 15 of a machine for extruding clay pipes, &c. is actuated towards and away from the extrusion die 11 by means of a main hydraulic cylinder 43 and an auxiliary hydraulic cylinder 28 in the piston rod 19 of the main cylinder, pressure in the auxiliary cylinder causing rapid extension of the die-carrying piston rod 19 and pressure in the main cylinder serving to lock the dies together. With the apparatus in the position shown, clay is extruded from cylinder 10 into the die 15 to form the socket. When the socket die has been filled a fringe of clay, extruded through an aperture 18 in the die 15, contacts a lever 45 and opens a spring-loaded valve 47 thus allowing compressed air from a source 50 to pass to a port 55 in the fixed part of a rotary slide valve A, through a curved passage 80 in the movable part of the valve to a further port 81 in the fixed part and thence to a pneumatic cylinder 83 in the main hydraulic control valve B. The-valve B has two pneumatic cylinders 83, 64 at either end, having a common piston rod 65 which also carries pistons 72, 73 controlling flow of oil to the cylinders 28, 43. The piston 83 A  is of greater area than the piston 64 A  so that the rod 65 moves down to its lower limit when both the cylinders 83, 64 are connected to the compressed air supply. In this position, oil under pressure passes from a source 68 through ports 70, 87 and pipe 40 to the control cylinder 33 of a valve 34. The valve 34 rises off its seat and a projection 41 on the valve moves to seal off the bottom of a tube 27 leading to the auxiliary cylinder 28. Oil, however, can escape from the cylinder 28 through pipe 32, needle valve 89 (non-return valve 77 is shut), pipe 75, ports 74, 85 and exhaust pipe 86. The valve 89 is controlled by a spring adjustable by a knob 92A so that the rate of escape of oil can be adjusted to allow the die 15 to fall under the weight of the pipe extruded from the die 11. Oil from the main cylinder 43 escapes through a passage 42, past the open valve 34 to an exhaust pipe 37. As the die moves down, a projection 94 on the die table encounters the arm 58 of the rotary valve A, moves it to the dotted position shown, and thus connects the cylinders 83, 64 and the valve 47 (now closed) to exhaust pipe 109. The projection 94 next encounters the arm 98 of a second rotary valve D, moves it to the dotted position shown and thus connects the pneumatic control cylinder 91 of the needle valve 89 to the compressed air supply 50. This causes the valve 89 to open to the limit imposed by an adjustable stop 102 thus enabling the oil to escape more easily from the cylinder 28 and the die 15 to move more rapidly. During this downward movement the extruded pipe is cut and removed. Finally the projection 94 actuates a third rotary valve E and connects a pneumatic cylinder 104 in the main valve B to the source of compressed air. This causes a piston 111, mounted to slide on the spindle 65, to press on a fixed collar 112 and move the spindle from its lowest position to an intermediate position in which oil is supplied under pressure from the source 68 to both the pipes 75 and 40. The flow in the pipe 75 is now reversed, the non-return valve 77 opens, and, since the valve 34 is still raised by pressure in the pipe 40, the whole of the oil from pipes 75, 32 passes through the tube 27 into the auxiliary cylinder 28, thus raising the die 15 at full speed. As it rises the valves E and D are reversed and the pneumatic cylinders 91, 104 again connected to exhaust. Finally the rotary valve A is reversed, compressed air is admitted to the cylinder 64 and the piston rod 65 rises to the position shown in the drawing. The control cylinder 33 of the valve 34 is now open to exhaust through the main valve B and the valve is consequently depressed, thus admitting oil past the projection 41, through the passage 42, into the main cylinder 43. The oil acting on the piston 20 of the main cylinder provides the locking force for the dies 11, 15. A handoperated cam 117 can be used to depress the spindle 65 into the downstroke position if the mechanism becomes obstructed. Specification 615,752, [Group V], is referred to.