Servo transfer feeder and method for controlling servo transfer feeder

A method for controlling a servo transfer feeder configured to transfer a workpiece between an upstream press and a downstream press, the workpiece being held by a holding member, the method comprising:

• providing a basic cam curve, a maximum velocity, and a maximum acceleration, the basic cam curve having been generated so that a moving time and a moving distance can be arbitrarily set, and a velocity and an acceleration of the holding member at a starting point and an end point are 0, and the maximum velocity and the maximum acceleration being set as motion limit values when the holding member moves;
• setting the moving distance when the holding member performs each motion among a first lift motion, an advance motion, a first down motion, a second lift motion, a return motion, and a second down motion;
• calculating a first moving time of each motion while limiting the basic cam curve at the set moving distance of each motion using the maximum velocity;
• calculating a second moving time of each motion while limiting the basic cam curve at the set moving distance of each motion using the maximum acceleration;
• comparing the first moving time with the second moving time to select the first moving time or the second moving time, whichever is longer, and inputting the selected moving time and the moving distance of each motion to the basic cam curve to generate a motion cam curve of each motion;
• combining at least six motion cam curves that have been generated to generate a transfer motion;
• and
• outputting a position instruction based on the transfer motion to move the holding member between the upstream press and the downstream press.

A servo transfer feeder configured to transfer a workpiece between an upstream press and a downstream press, the workpiece being held by a holding member, the servo transfer feeder comprising:

• a storage section that stores a basic cam curve, a maximum velocity and a maximum acceleration, the basic cam curve being generated by arbitrarily setting a moving time and a moving distance of the holding member, and the maximum velocity and the maximum acceleration being set as motion limit values when the holding member moves;
• a moving time calculation section that respectively calculates different moving times as to the moving distance of the holding member by limiting the basic cam curve respectively to the maximum velocity and the maximum acceleration;
• and
• a cam curve generation section that generates a motion cam curve as to the holding member by reflecting the moving distance and a longer one of the different moving times to the basic cam curve,
• wherein the holding member moves between the upstream press and the downstream press, based on the motion cam curve.