Compression molding apparatus

Claim 1

A compression molding apparatus comprising a rotary compression molding means including a rotating supporting member mounted rotatably about its central axis, a plurality of molding die means mounted on said rotating supporting member at circumferentially spaced intervals, each of said molding die means having an upper die assembly and a lower die assembly cooperating with each other, at least one of the upper die assemblies and one of the lower die assemblies being freely movable with respect to the other, a driving source for rotating said rotating supporting member in a predetermined direction and moving said molding die means through a circular conveying passage including a material charging zone, a molding zone, a cooling zone and an article discharging zone located successively, and a die opening-closing means for moving at least one of said upper and lower die assemblies in a predetermined manner with respect to the other according to the movement of said molding die means; a material feed means for feeding a plastic material to said molding die means in said material charging means; and an article carrying means for carrying the molded article from the molding die means in said article discharging zone, wherein at least one of the upper die assemblies and the lower die assemblies of the molding die means in the rotary compression molding means includes at least one supporting member, a first die member fixed to the forward end portion of the supporting member, a second die member mounted on the forward end portion of the supporting member for free sliding over a predetermined range along a longitudinal axis of the supporting member, at least one restricting member fixed to the forward end portion of the supporting member, and a restrictable member mounted on the second die member for free rotation between a first angular position and a second angular position and elastically biased to the first angular position by a spring means; the restrictable member has formed therein at least one abutting portion and at least one escape portion, at the first angular position, the escape portion is in alignment with the restricting member as viewed in the direction of the longitudinal axis of the supporting member so that the restricting member can be received in the escape portion, and at the second angular position, the abutting portion is in alignment with the restricting member as viewed in the direction of the longitudinal axis of the supporting member so that the abutting portion can abut against the restricting member; and the restrictable member further has provided therein a follower cam means, and a stationary cam means, adapted to act on the follower cam means and rotate the restrictable member from the first angular position to the second angular position against the elastic biasing action of the spring means, is disposed downstream of the cooling zone in the circular conveying passage of the molding die means.