Injection-molding machine with alarm device

Claim 1

In an injection-molding machine having two relatively movable mold portions which define at least one cavity provided with inlet means for admitting a hardenable plastic material to form at least one molded article, the combination therewith of: a take-off member reciprocably mounted for interposition between said mold portions in an open condition thereof and movement into a discharge position remote from the path of said mold portions, said take-off member being provided with holding means forming a seat for a molded article and with an air chamber adjacent said seat; drive means for periodically reciprocating said member in synchronism with the movement of said mold portions, the latter being reclosed preparatorily to performance of a new molding opeRation upon removal of said take-off member to said discharge position; conduit means terminating at said air chamber; a vacuum source and a high-pressure source alternately connectable to said air chamber by way of said conduit means; switchover means controlled by said drive means for connecting said vacuum source to said air chamber during a transfer phase terminating upon the removal of said member to said discharge position and for connecting said high-pressure source to said air chamber during a subsequent unloading phase whereby a molded article is entrained from said cavity by said take-off member on said seat and is thereafter dislodged therefrom; pressure-sensing means connected to said conduit means for detecting the development of a vacuum in said air chamber during said transfer phase, said pressure-sensing means being coupled to said switchover means for deactivation during said unloading phase; and alarm means connected to said pressure-sensing means for operation thereby in the absence of a vacuum during said transfer phase.