Hollow article and its manufacturing method and apparatus thereof

A hollow article made of thermoplastic resin, integrally formed by blow molding, comprising:

• a first wall and a second wall confronting across a spacing,
• an integral rib disposed between said first wall and said second wall, wherein said integral rib comprises
• a first flat rib projecting from said first wall to a fusion portion,
• a first hollow rib adjacent to each of two side ends of said first flat rib,
• a second flat rib projecting from said second wall to said fusion portion,
• a second hollow rib adjacent to each of two side ends of said second flat rib,
• wherein said first flat rib and said second flat rib are fused to each other at said fusion portion, and wherein said first hollow rib and said second hollow rib are fused to each other at said fusion portion.

A method of blow molding a hollow article having a first wall and a second wall confronting across a spacing, with an integral rib disposed between said first wall and said second wall, comprising the steps of:

• opening a split mold, wherein said split mold has a first mold half with a cavity, a slide core and a pair of support cores on either side of said slide core, and a second mold half with a cavity, a slide core and a pair of support cores on either side of said slide core;
• extruding a parison of molten thermoplastic resin between said split mold;
• closing said split mold;
• deforming said parison with each said sliding core and each of said pair of support cores and forming a first recess and a second recess, wherein a leading end of said first recess and a leading end of said second recess are fused;
• retracting each of said slide cores;
• introducing a pressure substance into said parison;
• inflating said parison along a cavity surface of said split molds and said support cores and forming said integral rib between said first wall and said second wall, wherein said integral rib comprises a pair of flat ribs and a pair of hollow ribs;
• and
• cooling said split mold, opening said split mold and removing said hollow article.

A method of blow molding a hollow article having a first wall and a second wall confronting across a spacing, with an integral rib disposed between said first wall and said second wall, comprising the steps of:

• opening a split mold, wherein said split mold has a first mold half with a cavity, and a second mold half with a cavity, a slide core and a pair of support cores on either side of said slide core;
• extruding a parison of molten thermoplastic resin between said split mold;
• closing said split mold;
• deforming said parison with said sliding core and said pair of support cores and forming a recess, wherein a leading end of said recess is fused to an inner surface of an opposing wall side;
• retracting said slide core;
• introducing a pressure substance into said parison;
• inflating said parison along a cavity surface of said split molds and said support cores and forming said integral rib between said first wall and said second wall, wherein said integral rib comprises a flat rib and a pair of hollow ribs;
• and
• cooling said split mold, opening said split mold and removing said hollow article.

An apparatus for blow molding a hollow article from thermoplastic resin having a first wall and a second wall confronting across a hollow space, and an integral rib disposed for providing structural support and absorbing impact between said first wall and said second wall, comprising:

• a split mold with a first mold half and a second mold half;
• a slidably engageable slide core for forming a flat rib disposed in at least one of said mold halves;
• a pair of support cores disposed on at least one of said mold halves for forming a hollow rib and adjacent to each of two side ends of said slide core;
• and
• a means of retracting said sliding core.