GB1268006A - Hydraulic pressure casting machine - Google Patents

Abstract

1,268,006. Pressure casting machines. WOTAN-WERKE G.m.b.H. 7 July, 1969 [6 July, 1968], No. 34063/69. Heading B3F. [Also in Division Fl] An hydraulic intensifier for increasing the hydraulic pressure in the working cylinder space 3 on one side of a moulding piston 2 near the end of its stroke comprises a stepped piston 12 which when fluid pressure is supplied through a line 15 and valve 14 to the larger face 13 thereof displaces a valve member 22 against a seat 24 to cut off the low pressure fluid supply through lines 7, 8 to space 3; the pressure therein then being intensified whilst the pressure in an annular chamber 18 of the intensified cylinder is connested to atmosphere. The initial portion of the working stroke of piston 2 is effected by moving a valve 5 to the right so as to connect a pump delivery line to lines 7, 8 and space 3 and to the underside of a servo piston 33. Towards the end of the stroke of piston 2 a pressure rise in a line 25 actuates a pressure switch 26 to operate valve 14 which connects the feed line 15 to the end 13 of the intensifier piston 12. On removal of the mould at the end of the casting operation the pressure in chamber 3 automatically falls to a level at which valve 14 assumes the position shown and return of piston 2 is effected by switching valve 5 to pressurize chamber 4 whereby chamber 3 exhausts through holes 23 of valve 22 until at the end of the return stroke of piston 2 a pressure rise in chamber 4 opens a valve 35 to admit pressure through line 34 to piston 33 which returns valve 22 to the . initial position shown.