Abstract: A hollow stackable product including at least a section of a generally conically contoured sidewall having a number of longitudinal folds of alternating ridges and furrows. Each fold includes a first side strip laterally extending from the top of a ridge to the bottom of an adjacent furrow and a second side strip laterally extending from the bottom of the furrow to the top of the next adjacent ridge. The first side strip has a different lateral orientation than the second side strip. The first side strip has a greater wall thickness than the second side strip; and the first side strip also has a shorter lateral extent than the second side strip. When the product is stacked within a like product, a first product is placed inside a second like product so that the first side strips of the first product are positioned closely adjacent the first side strips of the second product and the second side strips of the first product are positioned closely adjacent the second side strips of the second product.

Abstract: The dimensions of an injection molded hollow plastic product having laminated walls is controlled and the separative forces exerted against mold sections during molding of the products within a cavity of a mold having a core section and a cavity section defining the mold cavity therebetween, are reduced by methods including the steps of (a) injecting a first plastic material into the mold cavity; (b) cooling the injected first plastic material in the mold cavity; (c) injecting subsequent to injecting the first plastic material, a second plastic material into the mold cavity so that the cooled injected first plastic material is sufficiently solidified to stabilize the core section in relation to the cavity section by impeding movement of the core section in relation to the cavity section caused by injecting the second plastic material, whereby the injected second plastic material further fills the mold cavity; and (d) cooling the injected plastic material in the mold cavity to thereby solidify the molded produ

Abstract: In a plastic container, including a base and a thin flexible perimetric side wall extending from the base and terminating in a perimetric rim, the side wall includes a perimetric ledge extending generally in a lateral direction; an upper perimetric wall section extending between an outer edge of the ledge and the rim; a lower perimetric wall section extending toward the base from an inner edge of the ledge; and a perimetric series of longitudinal ribs closely spaced about all of the ledge and extending between the ledge and one of said wall sections for reinforcing the container against extreme flexure when the container is lifted by being gripped at the upper wall section by a thumb and finger while the container contains a substantial weight of material. The ribs are recessed from a brink of the ledge and have an exposed edge that extends between the ledge and the one wall section at an angle that is less than an angle between the ledge and the one wall section.

Abstract: The dimensions of a plastic product are controlled while injection molding the product in a mold cavity of a mold comprising a core section and a cavity section, separated by a parting line and defining the mold cavity.

Abstract: The dimensions of an injected molded hollow plastic product are controlled and the separative force exerted against mold sections during molding of the product are reduced by injecting plastic material continuously from a gate into a mold cavity having flow channels extending through the cavity region until the mold cavity is filled with said injected plastic material, with said injection being under such conditions of injection pressure, injected plastic material temperature, mold cavity temperature, flow channel length, distance between flow channels, flow channel thickness and wall thickness in a thin-cavity region between flow channels that initially injected plastic material solidifies in the thin-cavity regions to thereby stabilize one mold section in relation to the other mold section prior to the mold cavity being filled with the injected plastic material, and to thereby reduce said separative force.

Abstract: A method for injection molding a hollow, plastic product having an end wall and a cylindrical or approximately cylindrical side wall, wherein the end wall includes a fringe region bordering the end wall. A system for performing the method includes a mold-cavity-forming combination of a core section and a cavity section, wherein the core section includes a protractable and retractable ram-shaped contact element, with the end of the contact element that faces the mold cavity including a contact surface that contacts at least a significant part of the fringe region of the end-wall-defining portion of the cavity section. Both the end-wall defining portion and the side-wall defining portion of the core section consist of the contact element.

Abstract: A system and method of controlling hold pressure applied to molding cavities of a stacked multi-parting injection molding system having desynchronized injection periods while cyclic injection molding a plastic material. A combination of the center molding block and an injection system together provide an adjustable feed system. The feed system is adjusted to enable plastic material to be fed from the injection system through a left branch to the left molding cavity. The injection system is pressurized to inject the plastic material through the left branch to fill the left molding cavity. The injected plastic material is confined within the left branch and the left molding cavity; and the confined plastic material is hold pressurized by a movable packing element. A like sequence of steps is followed to hold pressurize the right molding cavity.

Abstract: A system and method of controlling hold pressure to cooling cavities when cyclic injection molding a thermoplastic material by utilizing a combination of a multi-parting mold system and an injection unit which together encompass a bifurcated feed system with a molten core. The mold system includes a center part that joins end parts at parting surfaces to define first and second cooling cavities. The feed system is defined by the injection unit and the center part and includes a runner orifice from the injection unit and bifurcated branches. A valve is located in the runner orifice. The first branch feeds injected thermoplastic material to the first cooling cavity, and the second branch feeds injected thermoplastic material to the second cooling cavity. The valve is closed each time after molten thermoplastic material is separately injected under pressure into each of the cooling cavities to hold pressurize the plastic material in the respective cooling cavities.

Abstract: The dimensions of an injected molded hollow plastic product are controlled and the separative force exerted against mold sections during molding of the product are reduced by injecting plastic material continuously from a gate into a mold cavity having flow channels extending through the cavity region until the mold cavity is filled with said injected plastic material, with said injection being under such conditions of injection pressure, injected plastic material temperature, mold cavity temperature, flow channel length, distance between flow channels, flow channel thickness and wall thickness in a thin-cavity region between flow channels that initially injected plastic material solidifies in the thin-cavity regions to thereby stabilize one mold section in relation to the other mold section prior to the mold cavity being filled with the injected plastic material, and to thereby reduce said separative force.

Abstract: A desynchronously opened, stacked, multi-parting molding system includes left, center and right molding blocks for defining a left molding cavity between the left and center molding blocks and a right molding cavity between the center and right molding blocks; a positioning mechanism for moving the left, center and right molding blocks along a common axis with respect to each other for desynchronously opening and closing the left and right molding cavities by retracting the first means and for simultaneously clamping both molding cavities in a closed position by protracting the first means, a locking mechanism for locking one molding cavity in a closed position while both molding cavities are clamped in a closed position and for maintaining the one molding cavity in a closed position while the other molding cavity is in an open position; and a clamping mechanism within at least one of the molding blocks that define the closed cavity provides axial clamping force while the first means is retracted to open the

Abstract: A system and method of cyclic injection molding a plastic material by controlling hold pressure and transferring plastic material to molding cavities of a stacked multi-parting injection molding system having desynchronized injection periods. The system includes left, left center, center, right center and right molding blocks disposed for movement with respect to each other along a common axis; and defining a left molding cavity between the left and the left center molding blocks, a left center molding cavity between the left center and the center molding blocks, a right center molding cavity between the center and the right center molding blocks, and a right molding cavity between the right center and the right molding blocks.

Abstract: A self aligning mold for injection molding and controlling the dimensions of a hollow plastic product having a rim, a base and a side wall therebetween. The base-forming portion of a first mold part includes a brink that protrudes in a direction toward a second mold part, and the base-forming portion of the second mold part includes a labrum that protrudes in a direction toward the first mold part to define a throttle situated between the brink and the labrum. The throttle has a variable width, which at any throttle position is defined by the distance between the brink and the labrum. The mold cavity gate is located within an area encompassed by the throttle. The throttle width varies when the first and second mold parts are not axially aligned to thereby, during injection, admit more material into the side wall-forming portion of the mold cavity that is the thinnest as a result of the axial misalignment, for the purpose of forcing the first and second mold parts into alignment.

Abstract: A process for injection molding plastic products having a closed end and an open end with laminated walls terminating in a rim at the open end. A first common mold part is combined with a first complementary mold part to assemble a first mold cavity in which the first plastic material is injected until it reaches the portion of the first mold cavity that defines the rim of the product. Portions of the first complementary mold part contact portions of the first common mold part to rigidly secure the mold parts in position in relation to each other in order to impede movement of the mold parts in relation to each other during injection of a first plastic material into the first mold cavity.

Abstract: A system for injection molding a hollow, plastic product having an end wall and a cylindrical or approximately cylindrical side wall, wherein the end wall includes a fringe region bordering the end wall. The system includes a mold-cavity-forming combination of a core section and a cavity section, wherein the core section includes a protractable and retractable ram-shaped contact element, with the end of the contact element that faces the mold cavity including a contact surface that contacts at least a significant part of the fringe region of the end-wall-defining portion of the cavity section. When the contact element is protracted to a forward position so that the contact surface contacts the cavity section, the area of the mold cavity as projected on a plane perpendicular to the mold opening direction is reduced, which thus reduces the clamping force required during the injection of plastic material.

Abstract: A hollow, stackable, injection-molded plastic product having a given stacking height includes a perimetric ledge extending generally in a lateral direction; an upper perimetric side wall extending generally upward from the ledge for a height exceeding the stacking height of the product; a lower perimetric side wall spaced from the upper perimetric side wall by the ledge and extending from the ledge generally downward for a height exceeding the stacking height of the product wherein at the ledge the cross-sectional area defined by the first perimetric side wall is greater than the cross-sectional area defined by the second perimetric side wall; and a rigidifying skirt-shaped perimetric flange extending generally in an upward or downward direction from the perimetric ledge. Thus, the rigidity of the side walls of the product is further enhanced by the flange without having to increase the stacking height of the product beyond what the stacking height would be were it not for the perimetric flange.

Abstract: A molded thin-walled hollow, stackable plastic product, having an open top, a closed bottom and side walls; wherein the side walls include a series of circumferential sections joined by circumferential strips, with the upper of two adjacent wall sections having a greater diameter than the lower adjacent wall section to thereby define a circumferential ridge at the bottom of each upper wall section. The circumferential strip joining a pair of the wall sections is a circumferential isthmus having an isthmus distance, which is the minimum distance between the mold parts defining the isthmus, that is significantly shorter than the predominant thickness of the adjacent wall sections. The isthmuses, which are aligned at an acute angle with respect to each of the joined wall sections, improve the rigidity of the molded thin-walled hollow product. The wall sections include a plurality of spaced protruding ridges extending between adjacent circumferential strips.

Abstract: An improved method of transferring thermoplastic material from an injection unit to a sandwich mold when a transfer of molding material along the central axis of the clamping platens is not suitable. The method utilizes one or more snorkels which have a central axis which is displaced from the central axis of the clamping platens. The method may be adapted to various sandwich molding cycles, and does not have problems with material drooling into the parting surfaces. The method may easily be used, with minor adaptations, in standard horizontally operating injection molding machines.

Abstract: A molded thin-walled hollow, stackable plastic product, having an open top, a closed bottom and side walls; wherein the side walls include a series of circumferential sections joined by circumferential strips, with the upper of two adjacent wall sections having a greater diameter than the lower adjacent wall section to thereby define a circumferential ridge at the bottom of each upper wall section. The circumferential strip joining a pair of the wall sections is a circumferential isthmus having an isthmus distance, which is the minimum distance between the mold parts defining the isthmus, that is significantly shorter than the predominant thickness of the adjacent wall sections. The isthmuses, which are aligned at an acute angle with respect to each of the joined wall sections, improve the rigidity of the molded thin-walled hollow product. The wall sections include a plurality of spaced protruding ridges extending between adjacent circumferential strips.