Workpiece loading method

A workpiece loading method using a piler conveyor comprising a first conveyor which sequentially conveys workpieces by continuous operation at a first speed, a second conveyor which magnetically attracts, on a lower surface, workpieces passed from the first conveyor for sequential conveyance by intermittent operation, and a loading frame where the workpieces are placed, the method using the piler conveyor comprising:

• detecting, by an activation sensor, a front end of the workpiece being conveyed, the activation sensor being attached to a tip of an arm part that is attached to the second conveyor so as to protrude from the end of the second conveyor toward the first conveyor;
• based on a signal from the activation sensor, performing:
• a first step of gradually accelerating the second conveyor to a second speed;
• a second step of operating the second conveyor at the second speed and passing the workpieces from the first conveyor to the second conveyor;
• a third step of gradually decelerating the second conveyor from the second speed for operation;
• and
• a fourth step of stopping the second conveyor and causing the second conveyor to lose a magnetic force and dropping a workpiece positioned above the loading frame onto the loading frame, wherein
• the first speed and the second speed are set at an equal constant speed,
• an end on a downstream side of the first conveyor and an end on an upstream side of the second conveyor are disposed so as to overlap vertically,
• the loading frame is movable along a rail part provided so as to be parallel to a longitudinal direction of the second conveyor, and
• a motor is provided at one end of the rail part and an encoder for detecting a position of the loading frame is attached to an other end of the rail part opposite to the motor.