Patent GB-1240283-A (GB)
Title: Method and apparatus for high speed cutting of profiled steel sections
IPC: B26D1/60
Filed: 1968-09-19
Abstract: 1,240,283. Flying shear. NIPPON STEEL CORP. 19 Sept., 1968 [23 Sept., 1967 (2)], No. 44592/68. Heading B3W. A flying shear for cutting profiled steel sections comprises a vertically-reciprocable, eccentrically-driven press head 18 which cooperates with a die set 19 mounted on a slide 23 reciprocable along the feed path P of the stock by an arm 24 pivotable between the positions arrowed. The die set 19 is slidable relative to the slide and is connected at one end to a gauging stop 21 and at the other to the piston-rods of air cylinders 22. A swell period is provided between the impact of the stock against the stop and the initiation of cutting, the moment of said initiation being corrected in accordance with variation in the speed at which the stock is fed and/or the location of the die set. In use, stock is fed along path P through slot (39) in the die set (Fig. 3, not shown) and the slide 23 is simultaneously advanced in the same direction by the arm 24. The feed of the stock and the speed of travel of the slide are so arranged that the leading end of the stock contacts the gauging stop when the slide has reached the position in which it is shown in Fig. 2 when the speed of the gauging stop is the same as or only slightly slower than that of the stock to prevent damage to the leading end on impact. The slide is driven by a pin 25 eccentrically mounted on a drive shaft 8, Fig. 1, and slidable along a slot 26 in the arm 24, the arm being pivotable about a fixed shaft 27 and connected to the slide by means of a pin 28. The speed of the slide is varied by adjusting the eccentricity e of the pin 25 by means of a screw 30. The slidable mounting of the die set on the slide 23 allows the die set to move relative to the slide when the stock hits the gauging stop 21 at which point acceleration of the slide 23 ceases. With the die set and the stock travelling at the same speed and a dwell period having elapsed since the stock hit the stop, the press head descends and actuates the apertured cutters of the die set to cut the stock. The gauging stop is raised to allow the cut length to be disengaged from the die set, the air cylinders 22 are actuated to retract the die set to the Fig. 2 position relative to the slide and the arm 24 returns the slide to the righthand limit of its travel as seen in Fig. 2. The press head 18 and arm 24 are driven by a motor 1 through a stepless speed changer 2. To ensure that the stock has reached the gauging stop before the press head is actuated, a roller MR for measuring the feed speed of the stock is connected to a pilot generator 31 which controls the rotary speed of the drive motor 1. A more refined control system (Fig. 6, not shown) comprises a pulse generator fixed to the shaft 7 (Fig. 1) which feeds signals to a gate circuit through which a die set position detection device feeds pulses to a computer. According to the difference between these positions and prescribed positions a motor 36 is driven to adjust the speed ratio of the speed changer 2 through which the motor 1 drives the shear.