Patent GB-1305981-A (GB)
IPC: B26F1/40
Filed: 1970-02-16
Abstract: 1305981 Cutting-out presses BRITISH UNITED SHOE MACHINERY CO Ltd 16 Feb 1970 [14 Feb 1969] 7269/70 Heading B4B A cutting-out press for use in cutting out workpieces from lays of material 14 in a succession of cutting strokes across the width of the material using a cutting die 16 positioned by an operator comprises a lower platen 12 for supporting the material and a smaller upper platen 30 which is mounted on a carriage 22 movable along a beam 18 by means of a screw 60 and an hydraulic motor 66, an hydraulic piston-andcylinder device 42, 28 for moving the upper platen towards the lower platen and photoelectric cell and light source means 161, 162 and 163, 164 arranged to provide a light screen A, B and C, D adjacent the upper platen, interruption of the light screen being effective to cause operation of the hydraulic motor 66. The carriage 22 is provided with rollers 24 adapted to run on rails 20 secured to the beam 18. The cylinder 28 is slidably mounted in a bearing block 26 fixed on the carriage, the cylinder being prevented from turning via four tubes 32, Fig. 2, secured at the lower ends to a slideway 34 and connected at their upper ends to return springs 36. A fixed piston 44 is mounted within the cylinder and connected to a hollow piston-rod 42, Fig. 1. The upper platen 30 is movable in the slideway 34 between a forward operative position and a rearward inoperative position by means of a pneumatic ram 70, Fig. 3. The hydraulic liquid is supplied to the piston 44 and motor 66 by a pump 50, Fig. 1. A further light screen is arranged to extend across the entire width of the press and is formed by lamps 150 and photo-electric cells 152. In use, with the press at rest, the upper platen 30 is in a rearward position in which it actuates a back limit switch BLS by means of a cam 170, Fig. 2 and the carriage 22 is positioned midway between limit switches L.H.L.S. and R.H.L.S., Fig. 1. When an operator passes his hands through the light screen provided by photo-electric cells 150 a holding circuit is energized so that a die can be positioned on the material. Removal of the operator's hands then causes relays in a circuit (Figs. 6a, 6b, not shown) to be energized thereby actuating solenoid valves (Fig. 5, not shown) to cause air to be fed to the cylinder 70 and so move the upper platen to its forward position. As the platen reaches the end of its forward stroke, a switch F.L.S. (Figs. 1 and 2) is actuated thereby stopping its movement and initiating its downward movement to engage the die. Upon completion of the cut a switch LLS, Fig. 2, is actuated thereby causing the upper platen to rise until a limit switch U.L.S. (Figs. 1 and 2) is operated causing the upper platen to be returned to its rear position. If during movement, the operator's hands are again passed through the light screen various relays are actuated causing the platen to be returned to its rear position. If the operator passes his hands through the light screen during the downward movement of the platen circuitry is provided for immediately raising the platen and returning it to its rear position. In order to control movement of the carriage along the beam 18 by means of the screw 60, the further light screens A, B, C, D. Fig. 1 formed by the lamps-andphoto-cell arrangements 161, 162, 163, 164 are used, the photo-cells sensing light from a reflective tape 166 carried along an angle arm 168 Fig. 2. When the die is required to be positioned to the left or right of its position shown in Fig. 1, one or other of the light screens A, B or C, D, is interrupted and causes the motor 66 to be operated so that the carriage is moved, after a short interval determined by a timer, in the direction of the operator's hand. When the light screen (i.e. A, B or C, D) again reaches the new position of the operator's hand, various relays are actuated to cause movement of the carriage to be stopped in readiness for a further cutting operation. The reflective tape 166 and the mountings of the photo-cell arrangement 161, 162, 163, 164 may be adjusted in order to vary the angle of the light screens and so accommodate the different way in which different operators hold a die. In a modification, Fig. 7, the carriage is adapted to be connected to a slide 200 by means of a solenoid (7SOL, Fig. 8). The slide is provided with lamp-and-photo-cell arrangements 161<SP>1</SP>, 162<SP>1</SP>, 163<SP>1</SP>, 164<SP>1</SP> and 150<SP>1</SP>, 152<SP>1</SP> which operate in a similar manner as that described in the previous embodiment. With the apparatus in the position shown in Fig. 7, the solenoid 7SOL is energized to connect the carriage to the slide and upon the operator passing his hands through the light screen formed by the photo-cell 162<SP>1</SP> to place the die on the material and then removing his hands, the solenoid 7 is released and allows the carriage to move until it is stopped by operating a switch CPS located over the die and completes a cutting stroke. After the cutting stroke the carriage moves to its initial position where the carriage is then re-connected with the slide. Upon the operator repositioning the die and thereby interrupting the light screen formed by photocells 161<SP>1</SP>, 162<SP>1</SP>, the carriage and slide move together until the light screen formed by photocells 163<SP>1</SP>, 164<SP>1</SP> is interrupted by the operator's hands. The carriage then moves relative to the slide as described above to effect a cutting stroke.