GB489583A - Improvements in riveting presses and the like - Google Patents

Abstract

489,583. Kydraulic presses. FORICHON, G. S. April 20, 1937, No. 11240. Convention date, April 21, 1936. [Class 69 (ii)] [Also in Group XXII] In a riveting or like press wherein the riveting- tool is moved by a liquid column of constant volume acted on in succession by a low power approach piston and a high power working piston, the latter is combined with amplifying means which transmits to the tool two successive and increasing forces. The riveting-tool 3 slides within a cylinder 8 which communicates with the chambers 17<1>, 17<2> and forms with them the chamber for a constant volume of liquid through which pressure is applied to the tool by plungers acting thereon. The approach movement of the tool is produced by a piston 5 actuated by compressed air, the transmission liquid flowing from chamber 17<1> into chamber 32 through a valve aperture 25, into the chamber 17<2> through an orifice 33 and so into the chamber 8. The valve 26, closing aperture 25, is initially held open by a piston 30 which is raised when the pressure increases and allows the valve to close when pressures on both sides of the aperture 25 are stabilized. Compressed air is then supplied to the rear of the working piston 6<1> which slides within the hollow piston 5. The first stage of the working stroke is effected by the head 6<2> of the piston sliding in fluid-tight engagement within a cylinder 20, the space 172 being fed with liquid from chamber 17<1> through the valve 25 which is held open by the reduced pressure in chambers 32, 17<2>. The head 6<2> then moves free of the cylinder 20, the valve 26 closes, and the remainder of the stroke is effected under increased pressure by displacement of liquid by the shank 63 of smaller diameter. In a modification, the head 6<2>, Fig. 8, is joined to the shank 6<3> by a part 6<4> of still smaller diameter. The approach stroke is effected by the piston 5 delivering fluid through the ports 34, 33 to the cylinder 8. During the first movement of the piston 6, the space behind the head 6<2> is in engagement with the chamber 17<1> due to the part 64 of reduced diameter, but the shank 6<3> enters into fluid-tight engagement with a joint 21 at the point when the head 6<2> leaves the cylinder 20, and the operation is continued under increased pressure by displacement of the fluid by the shank 6<3>. In a further modification, fluid is initially delivered by a byepass 47 to both sides of the piston 10, Fig. 13, of the ram 3 which thus acts differentially. When the head 6<2> passes a chamber 17<3>, fluid is delivered to the rear face only of the piston, the working stroke is continued under increased pressure. Specification 437,913 is referred to.