Manufacturing method for a synthetic resin hollow member and manufacturing apparatus therefor

A molding apparatus for manufacturing a synthetic resin hollow member by bringing a pair of synthetic resin-made half bodies into abutment each other and joining the half bodies together at their abutting portions comprising:

• a first die having formed lengthwise thereinto a series of molding portions in male-female-female-male sequence with a specific spacing therebetween;
• a second die having formed lengthwise thereinto a series of molding portions in female-male-female sequence with a specific spacing therebetween;
• a die opening and closing means for opening and closing the first and second dies to each other;
• a sliding means for sliding the first and second dies lengthwise a specific distance relative to each other;
• an injection means for injecting molten resin into a plurality of molding cavities formed between the closed first and second dies, wherein there is only one injection means;
• where an injection molding is carried out at each relative sliding operation of the dies, by which first and second half bodies for a present cycle are molded in a combination of male and female molding portions, and first and second half bodies from a preceding cycle are joined together by injecting molten resin between their abutting portions in a combination of female molding portions, and one hollow member constituted by joining first and second half bodies is manufactured at each relative sliding operation of the dies.

A manufacturing method for manufacturing a synthetic resin hollow member having an intermediate element incorporated therein by bringing a pair of synthetic resin-made half bodies into abutment with each other after disposing the intermediate element therebetween, and then joining the mated half bodies at their abutting portions, using a die slide injection molding apparatus comprising:

• a first hollow member die having formed lengthwise thereinto a series of molding portions in male-female-female-male sequence with a specific spacing therebetween;
• a first intermediate element die having an intermediate element molding portion and disposed at an end of the first hollow member die;
• a second hollow member die having formed lengthwise thereinto a series of molding portions in female-male-female sequence with a specific spacing therebetween;
• and a second intermediate element die having an intermediate element molding portion and disposed at an end of the second hollow member die, where the first and second hollow member dies can be mutually opened/closed and slid lengthwise a specific distance relative to each other, and the first and second intermediate element dies are openable and closable to each other but not slideable;
• said manufacturing method comprising following steps:
• a die clamping step for closing and clamping the first and second hollow member dies and first and second intermediate element dies respectively;
• an injection step following the die clamping step for injecting molten resin into molding cavities formed between the hollow member dies and intermediate element dies respectively, thereby forming first and second molding half bodies for a present cycle in a combination of male and female molding portions, and an intermediate element for the present cycle in a combination of the intermediate element molding portions, and joining first and second molding half bodies from a preceding cycle in a combination of female molding portions by injecting molten resin between their abutting portions, wherein there is only one injection means;
• a removal step following the injection step for opening the hollow member dies and removing the hollow member formed by joining half bodies from the previous cycle after assembling therebetween an intermediate element from the previous cycle;
• an intermediate element assembly step for assembling an intermediate element molded for the present cycle to either the first or second half body for the present cycle;
• a die sliding step for sliding the first and second hollow member dies lengthwise a specific distance relative to each other in a direction opposite that in which the dies were slid in the previous cycle;
• and repeating these steps to manufacture one hollow member constituted by joining first and second half bodies after assembling therebetween an intermediate element each time the dies are slid relative to each other.

A molding apparatus for manufacturing a synthetic resin hollow member having a intermediate element incorporated therein by bringing a pair of synthetic resin half bodies into abutment after disposing the intermediate element therebetween, and then joining the mated half bodies at their abutting portions, comprising:

• a first hollow member die having formed lengthwise thereinto a series of molding portions in male-female-female-male sequence with a specific spacing therebetween;
• a first intermediate element die having an intermediate element molding portion and disposed at an end of the first hollow member die;
• a second hollow member die having formed lengthwise thereinto a series of molding portions in female-male-female sequence with a specific spacing therebetween;
• and
• a second intermediate element die having an intermediate element molding portion and disposed at an end of the second hollow member die;
• a die opening and closing means for opening and closing respectively the first and second hollow member dies and first and second intermediate element dies to each other;
• a sliding means for sliding the hollow member dies lengthwise a specific distance relative to each other while holding the intermediate element dies without sliding;
• and
• an injection means for injecting molten resin into a plurality of molding cavities formed between the closed dies, wherein there is only one injection means;
• where an injection molding step is carried out at each relative sliding operation of the dies, by which first and second molding half bodies for a present cycle are molded in a combination of male and female molding portions, an intermediate element for the present cycle is molded in a combination of the intermediate element molding portions, and first and second half bodies from a preceding cycle are joined together by injecting molten resin between their abutting portions in a combination of female molding portions,
• and one hollow member constituted by joining first and second half bodies after assembling therebetween an intermediate element is manufactured at each relative sliding operation of the dies.

A manufacturing method for manufacturing a synthetic resin hollow member using a die slide injection molding apparatus comprising a first die having formed lengthwise thereto a series of molding portions in male-female-female-male sequence with a specific spacing therebetween, and a second die having formed lengthwise thereto a series of molding portions in female-male-female sequence with a specific spacing therebetween, where the dies can be mutually opened/closed and slid lengthwise a specific distance relative to each other;

• said manufacturing method comprising following steps:
• a first die clamping step for closing and clamping the first and second dies;
• a first injection step following the first die clamping step for molding third and fourth half bodies for a present cycle in a combination of male and female molding portions by injecting molten resin into a cavity formed between the dies, and joining together first and second half bodies from a preceding cycle in female molding portions by injecting molten resin between their abutting portions;
• a first removal step following the first injection step for opening the dies and removing a first hollow member formed by joining the first and second half bodies from the previous cycle;
• a first die sliding step following the first injection step for sliding the dies lengthwise a specific distance relative to each other in a direction opposite that in which the dies were slid in the previous cycle;
• a second die clamping step for closing and clamping the first and second dies after the first die sliding step;
• a second injection step following the second die clamping step for molding first and second molding half bodies for the present cycle in a combination of male and female molding portions by injecting molten resin to a molding cavity formed between the dies, and for joining together third and fourth half bodies from the present cycle in a combination of female molding portions by injecting molten resin to their abutting portions;
• a second removal step following the second injection step for opening the dies and removing a second hollow member formed by joining the third and fourth half bodies from the present cycle;
• and
• a second die sliding step following the second injection step for sliding the dies lengthwise a specific distance relative to each other in a direction opposite that in which the dies were slid in the first sliding step;
• and repeating these steps to sequentially manufacture one hollow member of joined first and second half bodies and one hollow member of joined third and fourth half bodies every two times the dies are slid relative to each other, wherein there is only one injection means.

A molding apparatus for manufacturing a synthetic resin hollow member, comprising:

• a first die having formed lengthwise thereinto a series of molding portions in male-female-female-male sequence with a specific spacing therebetween;
• a second die having formed lengthwise thereinto a series of molding portions in female-male-female sequence with a specific spacing therebetween, where the center male molding portion can be used in combination with each of the two center female molding portions in the first die;
• a die opening and closing means for opening and closing the first and second dies to each other;
• a sliding means for sliding the first and second dies lengthwise a specific distance relative to each other;
• and
• an injection means for injecting molten resin into a plurality of molding cavities formed between the closed first and second dies, wherein there is only one injection means;
• wherein at every two relative sliding operations of the first and second dies, a first injection molding step and a second injection molding step are performed,
• the first injection molding step comprising molding third and fourth molding half bodies for a present cycle in a combination of male and female molding portions by injecting molten resin to a cavity formed between the dies, and jointing first and second molding half bodies from a preceding in a combination of female molding portions by injecting molten resin between their abutting portions;
• and
• the second injection molding step comprising molding first and second half bodies for the present cycle in a combination of male and female molding portions by injecting molten resin to a cavity formed between the dies, and jointing third and fourth half bodies for the present cycle in a combination of female molding portions by injecting molten resin between their abutting portions;
• thereby yielding a first hollow member of joined first and second half bodies and a second hollow member of joined third and fourth half bodies, at every two relative sliding operations of first and second dies.