Patent ID: 8786240

Claim:
A method for controlling an electric cylinder in a device, wherein the device comprises an electric cylinder that moves a rod, a load detector attached to the rod that detects the load for pressurizing applied to a material to be pressed, a servo motor that drives the electric cylinder, and a position detector attached to the servo motor that is electrically connected to a servo amplifier, wherein the servo amplifier is electrically connected to the servo motor and a servo controller and controls the drive of the servo motor, and wherein the servo controller is electrically connected to the load detector and the servo amplifier and outputs a position control command to the servo amplifier so as to control the position of the servo motor, the method comprising: a step S 1 in which the servo controller sets the speed of the rod, sets a load for stopping that is a load set to less than or equal to a target load, and that is used for determining whether the rod should be stopped so that the load for pressurizing does not exceed the target load, and provides a command pulse signal for positioning from the servo controller to the servo amplifier based on the speed of the rod wherein the speed is input into the servo controller, a step S 2 in which the servo amplifier provides current for driving a motor to the servo motor based on the command pulse signal for positioning, a step S 3 in which a servo motor is driven so as to drive the rod by the current for driving a motor, a step S 4 in which a signal for a load for pressurizing, wherein the signal corresponds to the load for pressurizing detected by the load detector, is provided from the load detector to the servo controller, a step S 5 in which the servo controller determines whether the load for pressurizing is bigger than or equal to the load for stopping based on the signal for the load for pressurizing, a step S 6 in which the number of stored pulses is computed if it is determined that the load for pressurizing is bigger than or equal to the load for stopping, wherein the number of stored pulses is the difference between the number of pulses of the command pulse signal for positioning at the determination in step 5 and the number of pulses of the feedback pulse signal that is provided to the servo controller from the servo amplifier based on the signal of an absolute position that is provided to the servo amplifier from the position detector based on the speed of the rotation of the servo motor, and a step S 7 in which a command pulse signal for positioning in the reverse direction is provided to the servo amplifier from the servo controller, wherein the command pulse signal is a position control pulse signal that decreases the number of stored pulses based on the number of stored pulses computed at step 6 .