Abstract: Disclosed is an injection molding method for producing a shaped, hollow resin article by introducing a pressurized fluid into a molten resin mass injected into a mold cavity, wherein, during the introduction of the pressurized fluid, the temperature of at least one preselected portion of a back surface of the molten resin mass is maintained at a level which is at least 5.degree. C. higher than the temperature of a front surface of the molten resin mass, causing the fluid to flow into the molten resin mass along a line substantially corresponding to a line along which the preselected portion of the back surface extends, so that a shaped, hollow resin article produced has a hollow in a position corresponding to the preselected portion of the back surface. By the method of the present invention, the flow of the pressurized fluid introduced can be surely led to an intended portion in the molten resin mass, so that the location of a hollow in the molten resin mass can be surely controlled.

Abstract: Disclosed is an injection-molded hollow article having large hollow portions 1 which securely provide the strength required by the injection-molded hollow article without depending upon ribs as more solid remaining portions being unstable in position and size.A melted resin and pressurized fluid are injected under pressure into a metal mold cavity 4, a movable core 5 projected into the metal mold cavity 4 is moved and then a support portion 2 is formed at the position from which the movable core 5 is moved.The position and size of the support portion 2 can be determined by selecting the position and size of the movable core 5.

Abstract: A method for the non-resin fluid-assisted injection molding of a resin to produce a shaped resin article having an improved surface finish, which comprises effecting an excess filling of a mold cavity of a sealed mold with a molten resin to form a molten resin mass having opposite, first and second surfaces respectively facing opposite inner walls of the mold cavity, wherein the excess filling is performed in a specific excess filling ratio which corresponds to an excess ratio of a resin by an amount corresponding to 30 to 90% of the difference between the volume of the mold cavity and the volume exhibited by the resin in accordance with the shrinkage thereof when the molten resin filled in the mold cavity is cooled to room temperature, and subsequently introducing a pressurized non-resin fluid into the mold cavity on a side of the first surface of the molten resin mass to thereby press the second surface of the molten resin mass against the cavity inner wall remote from the side of the introduction of the no

Abstract: A shaped article of resin disclosed which possesses a two-ply construction wherein the outer side of a core-layer resin foamed at a void ratio in the range of from 30 to 80% is wrapped with a skin-layer resin. This shaped article of resin is produced by a method which comprises injecting a skin-layer resin into a molding mold and subsequently or simultaneously injecting therein a core-layer resin foamed in advance in a molding device.

Abstract: This invention concerns an injection molding nozzle device (25) provided with an operating valve (31) installed movably in the axial direction inside a nozzle body (4) possessed of a resin passage (12) and enclosing therewith a fluid passage (10) incorporating therein a check valve (11). This injection molding nozzle device is furnished with a fluid discharge open-shut device capable of opening or shutting a fluid discharge passage (17) formed separately of the fluid passage (10) or the check valve (11) of the fluid passage (10).