Patent ID: 6892560

Claim:
A mold clamping apparatus comprising: a mold having a longer side and a shorter side and in which a mold opening force is generated by applying a pressure for opening the mold to an inside of said mold; a frame including a holding portion for holding said mold resisting a generated mold opening force and an open portion allowing said mold to be inserted into/taken out from said holding portion in a direction of the shorter side of said mold; a mold moving device that moves said mold to insert/take out said mold into/from said holding portion through the open portion in said frame; and a mold opening/closing device that opens/closes the mold located outside the frame, wherein said frame comprises an overhang portion and a base portion, composing the holding portion, and a post portion for joining the overhang portion to the base portion, and molding parameters of respective portions of the frame are set up so that a stress index value K calculated according to the following expression is in a range of 0.2 to 15: K =[(6Φ E/D 2 )+(Φ /D )](1+(0.0188 D/C+ 0.243)( D/R) 1.18 ) wherein C is a maximum width of the overhang portion; D is a maximum width of the post portion; E is a minimum distance from the post portion to the center in the mold to which a pressure is applied; R is a maximum curvature radius of a connecting corner portion between the overhang portion or base portion and the post portion; and Φ is a width of a projection plane perpendicular to a direction of a mold opening force as a portion to which a pressure in the mold is applied.