Double-wall bottle and method and apparatus for molding the same

• US 5,921,416 A
• Filed: 01/26/1996
• Issued: 07/13/1999
• Est. Priority Date: 05/07/1993
• Status: Expired due to Term

• Current Assignee: Nissei ASB Machine Company Limited
• Original Assignee: Nissei ASB Machine Company Limited
• Inventors: Uehara, Shinichi
• Primary Examiner(s): Weaver, Sue A.
• Application Number:
  US08/545,651
• Time in Patent Office: 1,264 Days
• Field of Search: 215/12.1, 215/12.2, 215/385, 215/902, 264/156, 264/513, 264/516, 425/525, 425/529, 425/533, 425/534, 425/538, 220/461
• US Class Current: 215/12.1
• CPC Class Codes: B29C 2793/0045 Perforating
• CPC Class Codes: B29C 2949/0715 the preform having one end closed
• CPC Class Codes: B29C 2949/0817 of the body
• CPC Class Codes: B29C 2949/22 at neck portion
• CPC Class Codes: B29C 2949/3014 partially
• CPC Class Codes: B29C 2949/3016 at body portion
• CPC Class Codes: B29C 2949/302 at bottom portion
• CPC Class Codes: B29C 2949/3026 having two or more components
• CPC Class Codes: B29C 2949/3028 having three or more components
• CPC Class Codes: B29C 2949/303 having more than three components
• CPC Class Codes: B29C 2949/3034 having two or more components being injected
• CPC Class Codes: B29C 2949/3036 having three or more components being injected
• CPC Class Codes: B29C 2949/3038 having more than three components being injected
• CPC Class Codes: B29C 49/06 Injection blow-moulding
• CPC Class Codes: B29C 49/18 using several blowing steps B29C49/16 takes precedence
• CPC Class Codes: B29C 49/24 Lining or labelling
• CPC Class Codes: B29C 49/50 having cutting or deflashing means
• CPC Class Codes: B29C 49/62 Venting means
• CPC Class Codes: B29K 2067/00 Use of polyesters or derivatives thereof, as moulding material
• CPC Class Codes: B29K 2995/0053 bi-axially
• CPC Class Codes: B65D 1/0215 : multilayered B65D81/3837 takes precedence
• CPC Class Codes: Y10S 215/902 : Vent

Abstract

This invention relates to a method of molding a double-wall bottle consisting of an outer bottle (12) and an inner bottle (14). A outer bottle (12) is first formed from a first preform by biaxial Stretch blow molding. After this molding step, a plurality of air vent holes (24) are formed in a biaxially orientated region of the outer bottle (12). Next, a second preform (70) and the outer bottle (12) are set together within a first blow cavity mold (100). Subsequently, the inner bottle (24) is formed by biaxial stretch blow molding from the second preform (70) while the air within the outer bottler (12) is expelled through the air vent holes (24). Circumferential concave ribs (22) are formed around the entire circumference of the outer bottle (12), and at least one of the air vent holes (24) is formed in a region either inside or outside the region in which the circumferential concave ribs are formed.

Claims

1. A method of molding a double-wall bottle, comprising the steps of:

biaxial stretch blow molding a first preform to form an outer bottle having body and bottom portions;

forming air vent holes in the bottom portion and the body portion of said outer bottle;

setting a second preform and said outer bottle into a first blow cavity mold, said second preform being placed inside of said outer bottle after having formed said outer bottle, said second preform having a body portion of an outer diameter smaller than the diameter of an opening of said first preform and having a bottom portion, the body portion of the outer bottle having a longitudinal direction and a circumferential direction; and

biaxial stretch blow molding said second preform to form an inner bottle within said outer bottle;

wherein said step of forming said air vent holes is prior to said step of biaxial blow molding said second preform and includes a step of forming air vent holes at different positions in the longitudinal and circumferential directions of said body portion of said outer bottle in a predetermined pattern for enabling venting through said holes during said step of blow molding said second preform into said inner bottle;

wherein, during said step of biaxial stretch blow molding said inner bottle, the air within said outer bottle is vented by expelling air via said air vent holes formed at said body and bottom portions of said outer bottle; and

wherein the step of biaxial stretch blow molding said second preform takes place inside a blow mold, said blow mold having means for venting the air from said air vent holes including said air vent holes formed in said predetermined pattern, and said step of expelling includes a step for using the means for venting to expel air from the air vent holes including the air vent holes formed in the predetermined pattern.

2. A double-wall bottle molding method according to claim 1, wherein:

said means for venting in said first blow mold comprises configuring said first blow cavity mold as a plurality of split molds than can freely open and close with respect to each other;

at least one of said split molds has an air expulsion groove communicating from a cavity surface of said split mold to an outer surface thereof, formed in a parting surface of said split mold; and

during said step of expelling, the air expelled from within said outer bottle via said air vent holes is exhausted out of said first blow cavity mold via said air expulsion groove.

3. A double-wall bottle molding method according to claim 2, wherein:

during said step of biaxial stretch blow molding said outer bottle, a plurality of circumferential concave ribs are formed at a plurality of positions along the longitudinal axial direction of said outer bottle, in such a manner as to extend around the entire circumference of said outer bottle and be indented toward the interior of said outer bottle;

during said step of forming air vent holes in said predetermined pattern, at least one of said air vent holes is formed within the region in which said circumferential concave ribs are formed in said outer bottle;

during said setting step, part of said circumferential concave rib of said outer bottle is arranged to correspond to said air expulsion groove in said split mold; and

during said step of expelling during said step of biaxial stretch blow molding said inner bottle, air is exhausted via gaps between said cavity surface of said first blow cavity mold and said circumferential concave ribs.

4. A double-wall bottle molding method according to claim 3, wherein:

circumferential convex ribs are formed in the cavity surface of said first blow cavity mold at positions corresponding to said circumferential concave ribs of said outer bottle; and

during said step of biaxial stretch blow molding said inner bottle, a mating between said circumferential concave ribs and- said circumferential convex ribs prevents deformation of said outer bottle.

5. A double-wall bottle molding method according to claim 2, wherein:

during said step of biaxial stretch blow molding said outer bottle, circumferential concave ribs are formed at a plurality of positions along the longitudinal axial direction of said outer bottle, in such a manner as to extend around the entire circumference of said outer bottle and be indented toward the interior of said outer bottle; and

during said step of forming said air vent holes, at least one of said air vent holes is formed outside of the

region in which said circumferential concave ribs are formed in said outer bottle.

6. A double-wall bottle molding method according to claim 5, wherein:

circumferential convex ribs are formed in the cavity surface of said first blow cavity mold at positions corresponding to said circumferential concave ribs of said outer bottle; and

during said step of biaxial stretch blow molding said inner bottle, a mating between said circumferential concave ribs and said circumferential convex ribs prevents deformation of said outer bottle.

7. A double-wall bottle molding method according to claim 2, wherein:

said split mold is formed in such a manner that said means for venting comprises air expulsion grooves that communicate from a cavity surface thereof to an outer wall and are formed in a parting surface of said split mold, and also a circumferential groove that communicates with said air expulsion grooves is formed in said cavity surface; and

during said setting step, said air vent holes of said outer bottle are positioned to correspond to said circumferential groove.

8. A double-wall bottle molding method according to claim 2, wherein:

coolant passageways are formed in said split mold, and said inner bottle molded within said outer bottle by biaxial stretch blow molding is cooled by said split mold via said outer bottle.

9. A double-wall bottle molding method according to claim 1, wherein:

said first blow cavity mold is configured of a plurality of split molds that can freely open and close with respect to each other;

said means for venting comprises air vent holes formed in each of said split molds in a pattern corresponding to said predetermined pattern for communicating from a cavity surface thereof to an outer surface; and

during said setting step, said air vent holes of said outer bottle are positioned to correspond with said air vent holes in said split molds.

10. A double-wall bottle molding method according to claim 9, wherein:

coolant passageways are formed in said split mold and said inner bottle that is molded within said outer bottle by biaxial stretch blow molding is cooled by said split mold via said outer bottle.

11. A double-wall bottle molding method according to claim 1, wherein:

said first blow cavity mold is configured of a plurality of split molds including a bottom mold;

said step of forming said air vent holes includes a step of forming at least some of said air vent holes in a bottom portion of said outer bottle, substantially corresponding to a parting surface of said bottom mold; and

during said step of expelling and venting during said step of biaxial stretch blow molding said inner bottle, air expelled via said air vent holes formed in said bottom portion of said outer bottle is exhausted via gaps on said parting surface of said bottom mold.

12. A double-wall bottle molding method according to claim 1, wherein:

during said step of forming said air vent hole, heated hole-piercing members are driven forward and backward relative to said outer bottle to form said air vent hole.

13. A double-wall bottle molding method according to claim 1, wherein:

said step of forming said air vent holes are implemented within a second blow cavity mold used during said biaxial stretch blow molding of said first preform into said outer bottle, and said air vent holes are formed by hole-piercing members protruding from a cavity surface of said second blow cavity mold.

14. A double-wall bottle molding method according to claim 1, wherein:

said step of forming said air vent holes is implemented by driving heated hole-piercing members forward and backward relative to said outer bottle, after said outer bottle has been removed from a second blow cavity mold used during said biaxial stretch blow molding of said first preform into said outer bottle.

15. A double-wall bottle molding method according to claim 14, wherein:

said step of forming said air vent holes is implemented by rotating said outer bottle intermittently, driving said heated hole-piercing members forward and backward relative to said outer bottle when said rotation is stopped, whereby said air vent holes are formed at a plurality of locations around the circumferential direction of said outer bottle.

16. A double-wall bottle molding method according to claim 1, further comprising the steps of:

adjusting the temperature of said second preform to a suitable temperature for expansion, before said step of setting said second preform in said first blow cavity mold; and

inserting said outer bottle in such a manner that said outer bottle surrounds said second preform, after said temperature adjustment step;

wherein;

during said setting step, said second preform and said outer bottle are set simultaneously in said first blow cavity mold.

17. A double-wall bottle molding method according to claim 1, wherein:

said first blow cavity mold is configured of a plurality of split molds including a bottom mold, and said step of setting in said first blow cavity mold includes a step of mounting said outer bottle on said bottom mold.

18. A double-wall bottle molding method according to claim 1, further comprising a step of forming said first and second preforms of the same material and next to each other.

19. A double-wall bottle molding method according to claim 1, wherein during said steps of venting and expelling, air is vented from said air holes in said bottom portion at a faster rate than air is vented from said air vent holes in said body portion.

20. A double-wall bottle molding method according to claim 1, wherein the steps of biaxial stretch blow molding the inner bottle and expelling air are performed substantially instantaneously.

21. A method of molding a double-wall bottle, comprising the steps of:

biaxial stretch blow molding a first preform to form an outer bottle having body and bottom portions;

forming air vent holes in the bottom portion of said outer bottle;

setting a second preform and said outer bottle into a first blow cavity mold, said second preform being placed inside of said outer bottle, said second preform having a body portion of an outer diameter smaller than the diameter of an opening of said first preform and having a bottom portion, the body portion of the outer bottle having a longitudinal direction and a circumferential direction; and

biaxial stretch blow molding said second preform to form an inner bottle within said outer bottle;

wherein said step of forming said air vent holes includes a step of forming said air vent holes at different positions in the longitudinal and circumferential directions of said body portion of said outer bottle;

wherein said first blow cavity mold is configured of a plurality of split molds that can freely open and close with respect to each other;

wherein at least one of said split molds has an air expulsion groove communicating from a cavity surface of said split mold to an outer surface thereof, formed in a parting surface of said split mold;

wherein said air expulsion groove of said split mold is formed such that the shape thereof on the side facing said cavity surface is of a longitudinally extended groove extending over the length of the region in which said air vent holes are formed along the longitudinal direction of said outer bottle; and

wherein during said step of biaxial stretch blow molding said inner bottle, the air within said outer bottle is expelled via said air vent holes formed at said body and bottom portions of said outer bottle and is exhausted to the outside of said mold via said longitudinally extended groove shared by said air vent holes.

22. A method of molding a double-wall bottle, comprising the steps of:

biaxial stretch blow molding a first preform to form an outer bottle having body and bottom portions;

forming air vent holes in the bottom portion of said outer bottle;

setting a second preform and said outer bottle into a first blow cavity mold, said second preform being placed inside of said outer bottle, said second preform having a body portion of an outer diameter smaller than the diameter of an opening of said first preform and having a bottom portion, the body portion of the outer bottle having a longitudinal direction and a circumferential direction;

biaxial stretch blow molding said second preform to form an inner bottle within said outer bottle;

wherein said step of forming said air vent holes includes a step of forming said air vent holes at different positions in the longitudinal and circumferential directions of said body portion of said outer bottle, the number and/or total opening area of said air vent holes formed in said bottom portion and body portion is set to be such that an opening ratio per unit area of said bottom portion is larger than an opening ratio of said body portion; and

wherein, during said step of biaxial stretch blow molding said inner bottle, the air within said outer bottle is expelled via said air vent holes formed at said body and bottom portions of said outer bottle.

23. A double-wall bottle consisting only of an outer bottle having a biaxially orientated body portion and a bottom portion, and an inner bottle positioned within said outer bottle, wherein:

a plurality of air vent holes are formed in said body portion and said bottom portion of said outer bottle, and an opening ratio of said air vent holes per unit area is set to be larger in said bottom portion than in said body portion.

24. An apparatus for molding a double-wall bottle, comprising:

a means of forming an outer bottle having body and bottom portions by biaxial stretch blow molding a first preform;

a means of forming air vent holes in said body and bottom portions of said outer bottle in a predetermined pattern for enabling venting through said holes;

a means of setting a second perform and said outer bottle into a first blow cavity mold, said second preform being placed inside of said outer bottle, said second perform having a body portion of an outer diameter smaller than the diameter of an opening of said first preform and having a bottom; and

a means of forming an inner bottle within said outer bottle by biaxial stretch blow molding said second preform while expelling the air within said outer bottle through said air vent holes,

wherein said first blow cavity mold includes means for venting the expelled air from the air vent holes including the air vent holes formed in the predetermined pattern.

25. An apparatus according to claim 24, comprising:

a first blow molding machine that injection-molds said first preform and forms said outer bottle by biaxial stretch blow molding from said first preform while retaining the heat with which said first preform is injection-molded;

a second blow molding machine that injection-molds said second preform and forms said inner bottle by biaxial stretch blow molding from said second preform while retaining the heat with which said second preform is injection-molded and which is placed within said outer bottle; and

a conveyor means that supplies and conveys said outer bottle, ejected from said first blow molding machine, to said second blow molding machine at a determine that matches the timing of the biaxial stretch blow molding of said inner bottle.

26. An apparatus according to claim 25, wherein:

said air vent hole forming means is provided partway along a path along which said outer bottle is supplied and conveyed to said second blow molding machine.

27. An apparatus for molding a double-wall bottle according to claim 24, wherein the means for venting vents air faster from the air vent holes in the bottom portion than the air vent holes in the body portion.

28. An apparatus for molding a double-wall bottle according to claim 24, wherein the means for forming the inner bottle comprises means for expanding the inner bottle substantially instantaneously.

29. An apparatus for molding a double-wall bottle, comprising:

means for forming an outer bottle having body and bottom portions by biaxial stretch blow molding a first preform;

means for forming air vent holes in said body and bottom portions of said outer bottle;

means for setting a second preform and said outer bottle into a first blow cavity mold, said second preform being placed inside of said outer bottle, said second preform having a body portion of an outer diameter smaller than the diameter of an opening of said first preform and having a bottom;

means for forming an inner bottle within said outer bottle by biaxial stretch blow molding said second preform while expelling the air within said outer bottle through said air vent holes;

wherein said apparatus further comprising;

a first blow molding machine for injection-molding said first preform and forming said outer bottle by biaxial stretch blow molding from said first preform while retaining the heat with which said first preform is injection-molded;

a second blow molding machine for injection-molding said second preform and forming said inner bottle by biaxial stretch blow molding from said second preform while retaining the heat with which said second preform is injection-molded and which is placed within said outer bottle;

a conveyor means for supplying and conveying said outer bottle, ejected from said first blow molding machine, to said second blow molding machine at a timing that matches a timing of the biaxial stretch blow molding of said inner bottle; and

wherein a number N (where N≦

1) of said second blow molding machines and a number M (where M>

N) of said first blow molding machines are connected by said conveyor means.