Self-aligning mold for injection molding of hollow plastic products

A mold for injection molding and controlling the dimensions of a hollow plastic product having a rim, a base and a side wall therebetween, comprising

• a first mold part and a second mold part, which when assembled by axial movement with respect to each other, define a mold cavity for forming said plastic product;
• wherein a base-forming portion of the first mold part includes a brink that protrudes in a direction towards the second mold part, and a 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 said brink and said labrum, the throttle having a variable width, which at any throttle position is defined by the distance between said brink and said labrum;
• wherein the mold cavity defines a gate located within an area encompassed by the throttle;
• wherein 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 said axial misalignment, for the purpose of forcing the first and second mold parts into alignment;
• wherein at least one of the mold parts defines an axial conduit and having an axially protractable and retractable ram-shaped element within the conduit, with a front portion of the ram-shaped element defining a part of the mold cavity;
• and
• wherein the mold further comprises means for retracting the ram-shaped element during injection after an initial amount of plastic material has been injected into the mold cavity.

A mold for injection molding, laminating and controlling the dimensions of a hollow plastic product having a rim, a base and a side wall therebetween, comprising

• a first mold part and a second mold part, which when assembled by axial movement with respect to each other, define a first mold cavity for forming said plastic product;
• a third mold part, which, when assembled with the first mold part by axial movement with respect to each other while the first mold part is retaining a first layer of said plastic product formed by plastic material inserted into the first mold cavity, defines a second mold cavity for forming a second layer of said plastic product;
• wherein the base-forming portion of the first layer of plastic material retained by the first mold part includes a brink or a labrum formed in the first mold cavity by said second mold part, with said brink of said labrum protruding in a direction toward the third mold part, and the base-forming portion of the third mold part includes a labrum or a brink respectively that protrudes in a direction toward the first mold part to define a throttle situated between said brink and said labrum, the throttle having a variable width, which at any throttle position is defined by the distance between said brink and said labrum;
• and
• wherein the throttle width varies when the first and third mold parts are not axially aligned to thereby, during injection, admit more material into the side wall-forming portion of the second mold cavity that is the thinnest as a result of said axial misalignment, for the purpose of forcing the first mold parts into axial alignment.

A mold for injection molding and laminating a hollow plastic product having a rim, a base and a side wall therebetween, comprising

• a first mold part and a second mold part, which when assembled by axial movement with respect to each other, define a first mold cavity for forming said plastic product;
• wherein the first mold cavity includes primary flow channels for directing injected plastic material from the base-forming portion of the first mold cavity toward the rim-forming portion of the first mold cavity, with the first mold cavity thickness at the primary flow channels being generally thicker than the prevailing mold cavity thickness between the primary flow channels;
• the mold further comprising
• a third mold part, which, when assembled with the first mold part by axial movement with respect to each other while the first mold part is retaining a first layer of said plastic product formed by plastic material inserted into the first mold cavity, defines a second mold cavity for forming a second layer of said plastic product;
• wherein the first layer of plastic material is so shaped by the first mold cavity as to define secondary flow channels in the second mold cavity for directing plastic material injected into the second mold cavity from the base-forming portion of the second mold cavity toward the rim-forming portion of the second mold cavity.

A mold for injection molding, laminating and controlling the dimensions of a hollow plastic product having a rim, a base and a side wall therebetween, comprising

• a first mold part and a second mold part, which when assembled by axial movement with respect to each other, define a mold cavity for forming said plastic product;
• wherein a base-forming portion of the first mold part includes a brink that protrudes in a direction toward the second mold part, and a base-forming portion of the second mold part inclues a labrum that protrudes in a direction toward the first mold part to define a throttle situated between said brink and said labrum, the throttle having a variable width, which at any throttle position is defined by the distance between said brink and said labrum;
• wherein the mold cavity defines a gate located within an area encompassed by the throttle;
• and
• wherein 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 said axial misalignment, for the purpose of forcing the first and second mold parts into alignment;
• the mold further comprising
• a third mold part, which, when assembled with the first mold part by axial movement with respect to each other while the first mold part is retaining a first layer of said plastic product formed by plastic material inserted into the first mold cavity, defines a second mold cavity for forming a second layer of said plastic product.

A mold for injection molding and controlling the dimensions of a hollow plastic product having a rim, a base and a side wall therebetween, comprising

• a first mold part and a second mold part, which when assembled by axial movement with respect to each other, define a mold cavity for forming said plastic product;
• wherein a base-forming portion of the first mold part includes a brink that protrudes in a direction toward the second mold part, and a 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 said brink and said labrum, the throttle having a variable width, which at any throttle position is defined by the distance between said brink and said labrum;
• wherein the mold cavity defines a gate located within an area encompassed by the throttle;
• wherein 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 said axial misalignment, for the purpose of forcing the first and second mold parts into alignment;
• and
• wherein the brink, when the first and second mold parts are aligned and assembled, does not project into and beyond the labrum.