Method of molding a lined plastic storage tank
AssigneeInfiltrator Water Technologies, LLC
InventorsPaul R Holbrook, Roy E Moore, Jr., Bryan A Coppes
Life of this patent
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Abstract
A method of making a plastic tank suitable for containing water comprises forming a tank base which is partially or fully lined with a plastic layer that is different in character or color from the plastic material of the substrate of the tank base. The tank is alternatively formed by injection molding substrate material around the core of a mold which is partially or fully covered by the liner material, and by injecting liner material into the mold to bond it to the tank base substrate in conjunction with retracting part or all of the core, to provide space in the mold for the liner material.
Claims16
A method of making a plastic water storage tank which comprises injection molding a portion of a tank base, with use of a single mold comprised of a core part and a cavity part, the tank base having a side wall and a bottom wall, the interior surfaces of such walls in combination defining a tank concavity, wherein the base of the tank is shaped for nesting within like tank bases and a portion of at least one wall of the base comprises a substrate in combination with a liner made of material which is different from the material of the substrate and wherein the liner forms at least a portion of the interior surface of the concavity, the method characterized by:
- (a) surrounding at least the side wall-defining portion of the mold core with a film of first thermoplastic material;
- (b) inserting the core within the mold cavity to define between the core and cavity a mold space that is suited for injection of thermoplastic, wherein the core is shaped to define the interior surfaces of the side wall and bottom wall of said tank base, and wherein the mold cavity is shaped to define the exterior surfaces of the side wall and bottom wall of the tank base;
- (c) injecting a second thermoplastic into said mold space thereby to form the substrate of the tank base and to cause attachment of said film, as a first portion of said liner, to at least that portion of the substrate that comprises the side wall of the tank base;
- (d) then partially withdrawing the core or an end part of the core from the mold cavity, so that the core or the end part of the core moves away from the portion of substrate which forms the bottom wall of the base, to create an void space between the substrate forming said bottom and the moved portion of the core or core end part;
- (e) injecting a third thermoplastic material into said void space so that the third thermoplastic material attaches to the substrate and to the film which comprises the first portion of the liner, thereby to form a second portion of liner contiguous with the first portion;
- and,
- (f) withdrawing the mold core entirely from the mold cavity and removing the tank base from the mold cavity.
A method of making a plastic water storage tank which comprises injection molding a portion of a tank base with use of a single mold comprised of a core part and a cavity part, the tank base having a side wall and a bottom wall, the interior surfaces of such walls in combination defining a tank concavity, wherein the base of the tank is shaped for nesting within like tank bases and a portion at least one wall of the base comprises a substrate in combination with a liner made of material which is different from the material of the substrate, and wherein the liner forms at least a portion of an interior surface of the concavity, the method characterized by:
- (a) inserting the core within the mold cavity to define between the core and cavity a mold space that is suited for injection of thermoplastic, wherein the core is shaped to define the interior surfaces of the side wall and bottom wall of said tank base, and the mold cavity is shaped to define the exterior surfaces of the side wall and bottom wall of the tank base;
- (b) injecting a first thermoplastic into said mold space thereby to form the substrate of the tank base;
- (c) then partially withdrawing the core or an end part of the core from the mold cavity, so that the core or core end part moves away from the portion of substrate which forms the bottom wall of the base, to create a void space between the substrate and the moved portion of the core or core end part;
- (d) injecting a second thermoplastic material into said void space so that the second thermoplastic material attaches to the substrate as a liner portion;
- and,
- (e) withdrawing the mold core from the mold cavity and removing the tank base from the mold cavity.
Dependencies are inferred from the claim text.