GB857851A - Air press - Google Patents

Abstract

857,851. Shoe presses. STANDARD ENGINEERING CO. Ltd. Jan. 10, 1957 [Oct. 10, 1955], No. 28767/55. Class 17(1) A shoe press comprises an inflatable bag 2 or resilient pad for pressing a member which is to be attached by element against a lasted shoe held in position by a retractable clamping member 3 associated with a retractable locking means 6. Therefore, a first pneumatic ram 4 for operating the clamping member, a second pneumatic ram 5 for operating the locking member, a pneumatic timing cylinder 7 and piston 8 which in a forward and return stroke operates valves 12, 10 associated respectively with bladder 2 and ram 5 to delay inflation of the bladder (or application of thrust to the resilient pad) until after ram 4 has moved member 3 to clamping position and to delay of the second pneumatic ram 5 until the bladder has been substantially deflated (or thrust withdrawn from the resilient pad) and ram 4 has been reversed, and a control valve 15 for controlling the supply of air to cylinder 7. In the rest position shown, valve 12 is closed so that bladder 2 is open to exhaust, and valve 10 is held open by cam 9 on piston 8 so that compressed air from pipe 17 operates single acting ram 5 to hold clamp 6 open. When treadle 16 is depressed air passes via 17, 15, 18 to operate single acting ram 4 which moves member 3 to clamping position, and to cylinder 7, whereupon piston 8 is advanced, first moving cam 9 from valve 10 which closes, and then opening valve 12. Closing of valve 10 opens ram 5 to exhaust so that clamping means 6 is moved to lock member 3, and when valve 12 is opened air from 17 inflates bladder 2. When the treadle is again depressed line 18 is opened to exhaust, releasing pressure on ram 4, and permitting air from line 22 to return piston 8, valve 12 then closes, deflating the bladder, and finally valve 10 is opened by cam 9 to operate ram 5 and release the clamping means. In a modified construction valve 12 is operated by a lost motion device comprising a cam which is slidable on the rod of piston 8, is moved to open valve 12 only when engaged by cam 9 fixed to the rod, and is returned, so that valve 12 closes, only when engaged by a collar on the end of the piston rod immediately before cam 9 opens valve 10. A tap in line 22 may be used to adjust the speed of return of piston 8, thereby adjusting the time allowed for the cement to set. In a further construction cylinder 7 is single acting, valve 15 is non-reversing, line 22 is omitted, and a regulator, which may be by-passed, is included in the exhaust line from the cylinder. If desired cylinder 7 may control the sequence of operations, and a second timing cylinder control the period of inflation, being connected to a reversing control valve and arranged to operate a valve in the pressure line to cylinder 7. Alternatively the second timing cylinder may time the release of the actuating member of the control valve, and a chamber may be arranged in series with the cylinder to delay build up of pressure. Connection to the chamber and valve may then be by way of flow regulators, and alternative flow regulators and a change-over cock may be incorporated to vary the timing.