GB1090577A - Fluid-pressure-operable clamping and like devices - Google Patents

Abstract

1,090,577. Machine tool details. DOWTY TECHNICAL DEVELOPMENTS Ltd. June 24, 1966 [July 3, 1965], No. 28268/65. Heading B3B. [Also in Division F1] Workpieces 12, 13 are clamped on a worktable 14 by a plate 17 which carries a fluid pressure means 11 having a piston rod 20 connected to a rod 21, which is secured to the table. Means 11 comprises a cylinder 16, a first piston 28 having a hollow piston rod 29, a second piston 31 having a hollow piston rod 20, and a ball valve 41. Piston 28 has a cup seal 46 which in its upper position engages a frusto-conical projection 48 formed on an end cap 24. In operation, with piston 28 in the Fig. 2 position, and ball 41 unseated by a rod 27, fluid under pressure passes through a line 15 into a chamber 49, through piston rod 29, into the interior 34 of piston rod 20 and through a part 35. Piston 31 moves upwardly a certain amount, thus providing a light clamping of the workpieces. The pressure builds up in chamber 49, piston 28 moves downwardly, and ball valve 41 closes thus trapping the fluid in passages 39, 34, 36. Seal 46, 48 is broken so that the whole of the face area 44 of piston 28 is subjected to pressure, and piston 28 moves against springs 37, 38 more rapidly, so that when rod 20 penetrates interior 34 of rod 20, the pressure of the trapped fuel is intensified. Piston 31 moves upwardly and the workpieces are more securely clamped. The fluid may be liquid supplied from a reservoir which is pressurized by compressed air, or the fluid may be compressed air.