Patent ID: 7179075
Filing Date: 2007-02-20
Classification: B29C

Abstract:
1. A vertical injection molding machine comprising: a tail stock mounted with a mold opening/closing servo-motor; a movable die plate having a movable-side die disposed on a lower surface side thereof; a tie bar for tying said tail stock to said movable die plate; a fixed die plate disposed between said tail stock and said movable die plate and having a fixed-side die disposed on an upper surface side thereof; a ball screw mechanism for converting rotation of said mold opening/closing servo-motor into a rectilinear motion; a toggle link mechanism linked with an upper surface side of said tail stock and a lower surface side of said fixed die plate and driven to be stretched/folded by a rectilinear motion of a rectilinear movement member of said ball screw mechanism, said toggle link mechanism being driven to be stretched through said ball screw mechanism by said mold opening/closing servo-motor in a mold opening state so as to move down said tail stock to thereby move down said tie bar and said movable die plate together with said tail stock to thereby perform mold closing; and a foreign matter determination unit for comparing a measured torque value of said mold opening/closing servo-motor in a foreign matter detection region where said mold opening/closing servo-motor is subjected to speed feedback control along a position axis in a mold closing process, with a standard torque characteristic curve in a state where there is no foreign matter between said dies, so as to determine whether there is a foreign matter between said dies or not, said foreign matter determination unit changing over a criterion for determining whether there is a foreign matter or not, in the boundary of a torque value 0 in said standard torque characteristic curve.