GB702282A - Improvements in or relating to machines organised for applying pressure to shoe bottom parts - Google Patents

Abstract

702,282. Boots &c. BRITISH UNITED SHOE MACHINERY CO., Ltd., and KESTELL, T. A. April 15, 1952 [April 13, 1951], No: 8591/51. Class 17(1) In machines in which pressure is applied to shoe bottoms such as in sole moulding, sole laying and levelling and lasted bottom ironing, and where the power means act through mechanical connections a yieldable hydraulic device is provided which causes the pressure to be applied first at a low value and then at a predetermined higher value at which the device yields. As applied to the shoe bottom press described in Specification 216,937, [Class 17(i)], the device replaces the heavy spring power transmission unit and is arranged to prevent full load falling on the operating toggles until the levers are 20 degrees from the straight. The device comprises a cylinder 101 which slides over a piston 111 having a valve unit 113 in its end. The valve has a ball 129 held seated on a shoulder 127 against a spring 143 by a rod 163 loaded by a spring 161 and arranged to be lifted by a lever 171 actuated by a rod 177 controlled by a cam on the main driving shaft. A spring 109 tends to keep the device extended. The device is pivotally connected to the machine frame by the engagement of screws in holes in projecting bosses 153 of the piston 111. In operation, the power transmitting toggles of the prior machine engage an abutment 103 with the valve 113 open so that the cylinder 101 moves up the piston 111 withlittle resistance so that the shoe is engaged by a low pressure until the toggle links are within 20 degrees of straight at which point the lifting lever 171 is actuated to allow the spring 161 to close the valve 113 thus locking the piston and cylinder together until the pressure is sufficient to blow the valve 113 against the spring 161. The arrangement is such that the device operates for both pads of the prior machine and the rapid return of the cylinder 101 is facilitated by ports 117 in the upper part of the piston which allows the fluid to enter the part of the cylinder and to return through passages in a sleeve 185 as the device again extends. The pressure at which the valve 113 blows determines the pressure applied to the work and is set by tensioning the spring 161 through a handwheel 159 the setting being indicated by a pointer 221 moving over a plate 223.