Stretch rod system for liquid or hydraulic blow molding

1. A method of forming a plastic container from a preform, said method comprising:

heating a preform to a temperature between 190° F. and 250° F.;

heating a mold cavity to a temperature between 250° F. and 350° F.;

inserting said preform within said mold cavity;

actuating a stretch initiation rod system to engage an interior portion of the preform to define a stretch initiation area;

introducing a pressurized fluid into said preform to expand said preform to closely conform to said mold cavity; and

actuating a central exterior rod such that a locating feature formed on said central exterior rod engages an exterior feature of said preform to generally maintain a predetermined orientation of said preform during at least a portion of said introducing said pressurized fluid.

2. The method according to claim 1 , further comprising:

actuating said stretch initiation rod system following at least a portion of said introducing said pressurized fluid to create a headspace within the container.

3. The method according to claim 1 , further comprising:

actuating said stretch initiation rod system following at least a portion of said introducing said pressurized fluid to create a fluid pressure spike within the container.

4. The method according to claim 1 , further comprising:

maintaining a predetermined pressure within said preform following said introducing said pressurized fluid such that said preform is held against said mold cavity for a predetermined duration.

5. The method according to claim 4 wherein said predetermined duration is between 0.1 seconds and 1.5 seconds.

6. The method according to claim 1 wherein said pressurized fluid comprises a liquid commodity that remains in the plastic container.

7. The method according to claim 1 wherein said preform is made from a thermoplastic, a high density polyethylene, a polypropylene, a polyethylene naphthalate (PEN), a PET/PEN blend, a copolymer, various multilayer structures, and any combination or blend thereof.

8. A method of forming a plastic container from a preform, said method comprising:

heating a preform;

inserting said preform within a mold cavity having a central longitudinal axis;

introducing a pressurized liquid into said preform to expand said preform to closely conform to said mold cavity; and

actuating a central exterior rod such that a locating feature formed on said central exterior rod engages an exterior feature of said preform to prevent said preform from slipping off said central exterior rod and to generally maintain a concentricity of said exterior feature of said preform with respect to said cavity central longitudinal axis during at least a portion of said introducing said pressurized liquid without substantial modification of said exterior feature of said preform.

9. The method according to claim 8 , further comprising:

actuating a stretch initiation rod system to engage an interior portion of the preform and actuating said stretch initiation rod system following at least a portion of said introducing said pressurized liquid to create a headspace within the container.

10. The method according to claim 8 , further comprising:

actuating a stretch initiation rod system to engage an interior portion of the preform and actuating said stretch initiation rod system following at least a portion of said introducing said pressurized liquid to create a fluid pressure spike within the container.

11. The method according to claim 8 , further comprising:

maintaining a predetermined pressure within said preform following said introducing said pressurized liquid such that said preform is held against said mold cavity for a predetermined duration.

12. The method according to claim 11 wherein said predetermined duration is between 0.1 seconds and 1.5 seconds.

13. The method according to claim 8 , further comprising the step of retracting said central exterior rod towards a bottom of said mold cavity after said engaging of said central exterior rod and during at least a portion of said introducing said pressurized liquid,

wherein said introducing, said engaging and said retracting maintain a concentricity of said exterior feature of said preform with respect to said cavity central longitudinal axis.

14. The method according to claim 8 wherein said heating a preform includes heating the preform to a temperature between 190° F. and 250° F.

15. The method according to claim 8 , further comprising:

heating the mold cavity to a temperature between 250° F. and 350° F.