Patent GB-541726-A (GB)
Title: Improvements in or relating to riveting presses and the like
IPC: B21J15/20
Filed: 1940-06-06
Abstract: 541,726. Hydraulic presses ; valves ; riveting and forging metal. FORICHON, G. S. June 6, 1940, No. 9914. Convention date, June 6, 1939. [Classes 69 (ii) and 135] [Also in Group XXII] A press for riveting and the like comprises a fixed anvil 123, Fig. 2b, and a movable tool 126 operated by oil &c. under pressure acting upon a piston 128 to which the tool holder is attached in such a manner that its initial position can be adjusted, the oil being pressed m two stages by a piston 7, Fig. 2a, which produces the approaching motion of the tool 126, and by a piston 10 which effects the final operation of the tool. The pistons 7, 10 are operated by a compressed fluid such as air and their movements are controlled by a valve 16, Figs. 2a, 5, or by a modified form of valve, Fig. 13, the valves in each case being operated pneumatically by an operating device 20 connected by a flexible tube 19 to the valve so that the valve can be operated from the working position. The valve is adapted to operate in turn distributing devices 5, 51, which supply the compressed air to the cylinders of the pistons 7, 10, and control the exhausts also in succession in such a manner that the work can be adjusted between the approaching and working strokes. The valve 16, Fig. 2a, is controlled by a lever 31 on a cam shaft fitted with two raised parts 28, 26 separated by a depressed part 30, the first raised part 28 acting to open a spring pressed valve 21 to relieve the air pressure m pipe 19 and consequently in the right end of the hollow cylinder 15, Fig. 5, in which the valve 16 slides. Since the left end of this cylinder is connected by a pipe 17 with the supply pipe 18 of compressed air the valve 16 is moved by air pressure against the action of a spring 48 to the position shown in Fig. 5, and the compressed air is then connected by a pipe 32 to a cylinder 501 to operate a piston 51 which opens a ball valve 52 to connect the compressed air from a pipe 18<SP>2</SP> to the cylinder of the approach piston 7. The valve 16 is fitted with inclined ramps 45, 46 which act upon pins 37, 38 adapted to rotate the valve through a quarter of a revolution for each sliding movement of the valve. The second sliding movement is obtained when the cam depression 30 permits closing of the valve 21 and the consequent building up of air pressure in the right end 152 of the cylinder 15 by air which passes through a passage 39 and a calibrated aperture 40. A spring 48 then returns the valve 16 to the left and the valve is rotated a quarter of a revolution to connect the compressed air to the distributer 5 which controls the supply of air to the cylinder of the working piston 10. The lever 31 is then released and is returned by a spring which causes the projection 28 to open the valve thereby causing a second movement of the valve to the right, and finally the cam returns to the position shown in Fig. 2a, in which the distributer 5 is connected to exhaust by the final rotation of the valve by the pin- and-ramp mechanism. In a modified valve mechanism Fig. 13, a pair of piston valves 16, 161 are moved in sequence from the position shown towards the right in order to connect compressed air from a pipe 17 first to the approach cylinder and then to the power cylinder via pipes 32, 33 respectively, the pipes being connected to exhaust when the pistons 16, 161 are towards the left. A pipe 19 connects the cylinder 15<SP>2</SP> of valve 16 to a pressure-relieving valve 21 normally closed by a spring 23 and adapted to be opened by a push-button 31 fitted with a hook which engages with a hook on the stem of the valve when the button is pushed slightly to permit the valve 21 to open under air pressure. The pressure in the cylinders 152, 154, is thus released and the air pressure on the pistons causes the piston 16<SP>1</SP> to move to the left against the action of a spring 48<SP>1</SP> which is weaker than the spring 48, and the compressed air then passes via pipe 32 to the approach cylinder. On release of the button 31 the cylinders are again connected to exhaust, and then by pressing on the button 31 strongly so as to cause the hooks to engage so as to move the valve 23 positively from its seat, the air is released quickly from the pipe 19 and is more quickly exhausted from the cylinder 152 than from the cylinder 15<SP>4</SP> so that the piston 16 moves to the right and connects the power cylinder to the compressed air. In a modified form of this valve the valves 16, 161 are formed integrally and in alignment, and the method of actuation is varied somewhat. The approach cylinder 65<SP>3</SP> is arranged at the top of the power cylinder 65 and the ram 10<SP>1</SP> of the power piston 10 passes through the dividing partition 66. At the commencement of operation the piston 4 is depressed to full extent by a push rod 88 formed with grooves 91, 911 adapted to coact with a spring-pressed locking-ball 95. Oil is inserted through an aperture normally closed by a screw 72. The raising of the piston 7 forces oil through an annular chamber 65<SP>1</SP> and passages 83, 71 to an outlet 73 leading by a pipe 3 to the pressure-multiplying device shown in Fig. 2a which actuates the piston 128. The ram 101 works in an inner chamber 62 and forces the oil past apertures 78, 781 and then raises a spring- depressed piston 75 and causes the hollow stem of the piston to close around the passage 83 and the compressed oil passes into the pipe 3 at a greater pressure than the pressure produced by the approach piston. The pipe 3 is connected to a fluid control device 111 which acts to multiply the pressure when the power piston is operating. The approach piston drives oil through a tube 108 attached to a spring-controlled piston 106, and the oil passes by the head 112 of a plug 102 into a cylinder 110<SP>3</SP> leading by passages 103, 105 to the cylinder of the piston 128. When the power piston is operating some of the oil passes outside of an inner hollow tube attached to the piston 106, and the oil acts to advance the piston and its tube 108 passes over a plug 102 with which it forms a tight connection, and the piston 106 and its tube 108 act as a differential piston and the oil passes at a high pressure to the passages 103, 105. A drain plug 104 is fitted to the passage 103. The tool 126 is connected to the operating plunger 128 by means of a screw connection operated by a knob 141 the turning of which permits the starting position of the tool to be adjusted. The extent of the stroke can be varied by rotation of a nut 150 which raises or lowers a key 156 which is star-shaped and formed of two parts connected together. The key controls the position of an abutment 135 which limits the lower position of the plunger 128.