Press load measuring apparatus and method for press machine

A press load measuring apparatus for a press machine, in which a slide is driven by a crank mechanism, comprising:

• a plurality of strain gauges attached to a plurality of columns of the press machine respectively, the plurality of strain gauges configured to detect respective strains generated in the plurality of columns in association with a press load acting on the slide of the press machine;
• an acceleration detector configured to detect the acceleration of the slide;
• an inertial force calculator configured to calculate a slide inertial force G by using the following expression G=−M·α, where M is a mass of the slide and a member connected to the slide that is a preset mass and α is the acceleration of the slide in an upward direction to be detected by the acceleration door;
• and
• a press load calculator configured to calculate press loads before calibration based on strains detected by the strain gauges attached to the respective columns of the plurality of columns, eliminate the calculated slide inertial force from the press loads before the calibration, and calculate calibrated press loads.