HALF NUT OF MOLD CLAMPING DEVICE

PROBLEM TO BE SOLVED: To solve problems in a mold clamping device of an injection molding machine wherein, as mechanical backlash normally occurs between when moving in the mold clamping direction and when moving in the mold opening direction, an opening amount of molds differs by the amount of backlash when opening the molds by being pressed by foaming pressure due to the high foaming pressure and when opening the molds by the force of the mold clamping device due to the low foaming pressure, causing variation in thickness of molded articles and unstable quality depending on the foaming state of molten resin. SOLUTION: The compound mold clamping device has a spring 32 pressing a half nut to a movable platen 16 between a nut pressing member 23 and the half nut 22. An engaging part of a tie-bar with the half nut is in a serrated state formed of tilted tooth flanks and vertical tooth flanks, the tilted tooth flanks and the vertical tooth flanks of the engaging part come into contact with each other when engaged to eliminate the backlash between the movable platen and the tie-bar. COPYRIGHT: (C)2011,JPO&INPIT