Rocking type flying shears with stationary shearing function

Rocking type flying shears comprising:

• a first blade having an upper cutting edge;
• a second blade having a lower cutting edge;
• a main crank shaft coupled to said first and second blades with a first eccentricity (r1) controlling movement of said first blade up and down and a second eccentricity (r2) controlling movement of said second blade up and down to effect shearing;
• a rocking crank shaft mounted for swaying motion with a third eccentricity (r3);
• a rocking type flying shear body coupling said first blade to said main crank shaft for effecting said up and down movement of said first blade, said second blade being mounted for sliding movement along said shear body, said body having rocking pins thereon;
• means coupling said rocking crank shaft to said rocking pins for transmitting said swaying motion to said blades;
• a motor;
• a gear train including at least two synchronizing gears for transmitting the drive force of said motor simultaneously to said main and rocking crank shafts;
• a phase converter including a first clutch for coupling said main and rocking crank shaft for setting the shears for operation in a first mode in which material to be sheared is in repose and a second mode in which material to be sheared is moving, the change between modes being achieved by rotating the main and rocking crank shafts 180.degree. with respect to each other while said first clutch is open;
• and
• a torque actuator and a second clutch coupled to one of said crank shafts for rotating said one shaft to effect said change of mode,
• the ratio r1/r3 satisfying the formula ##EQU2##