초록 ▼

A mold suitable for use in simultaneous molding of a large number of articles at a time by hot-runner molding technique. The mold has a hot-runner block in which disposed are a plurality of gates through which the molten resin is delivered to the molding cavities formed in a cavity block which is us

A mold suitable for use in simultaneous molding of a large number of articles at a time by hot-runner molding technique. The mold has a hot-runner block in which disposed are a plurality of gates through which the molten resin is delivered to the molding cavities formed in a cavity block which is usually kept at a low temperature. The gate area of the hot-runner block is kept in contact with the cavity block, for the safe deliver of the resin to the molding cavities, in the injection step and, therefore, is cooled by the cavity block. Consequently, when the injection is completed, the gate area has been cooled to such a low temperature as to cause a solidification of the resin in the gate area. The hot-runner block is then separated from the cavity block and brought into contact with a hot gate-temperature recovering block, so that the gates are heated to remelt the solidified resin, before the next batch of injection is performed, so as to recover the fluidity of the resin.

대표청구항 ▼

A hot-runner mold comprising: a hot-runner block having means for maintaining a predetermined high temperature of said hot-running block, a molten resin supply port, gates and molten resin passages through which said gates are communicated with said molten resin supply port; a cavity block having a

A hot-runner mold comprising: a hot-runner block having means for maintaining a predetermined high temperature of said hot-running block, a molten resin supply port, gates and molten resin passages through which said gates are communicated with said molten resin supply port; a cavity block having a contact surface which is contacted by said gates and having means for maintaining a predetermined low temperature of said cavity block and molding cavities having respective molten resin pouring ports; and a gate-temperature recovering block positioned within said cavity block such that a portion of its surface lies in the same plane as said contact surface of said cavity block, said gate-temperature recovery block having a heating means disposed therein, said heating means being capable of maintaining a higher temperature than the temperature of said cavity block, said gate temperature recovery block functioning to recover a predetermined high temperature at said gates, upon contacting the portion of said hot-runner block around said gates; wherein said hot-runner block and said cavity block are movable relative to each other such that, at least during the injection, said gates of said hot-runner block and said molten resin pouring ports of said cavity block are brought into alignment with each other and, after the completion of the injection, said gates and said molten resin pouring ports are moved relatively away from each other, while said gate-temperature recovering block is put into contact with said portion of said hot-runner block around said gates, over at least a portion of the period in which said gates and said molten resin pouring ports are kept away from each other.