Blow cylinder with fluid cushion
AssigneeGraham Packaging Company, L.P.
InventorsMarshall Miller, Bernie Klingenmaier
Life of this patent
Estimating the term…
Abstract
Novel blow cylinders use a retract fluid at a minimum pressure, located between a piston head and a wall of a cylinder body, to prevent the piston head from violently impacting the wall when the piston head is moved so that a blow needle engages a parison. The retract fluid at a minimum pressure is also used to move the piston head so that the blow needle disengages the parison.
Claims30
A blow cylinder for blow molding a container from a parison, comprising:
- a cylinder body having a head cavity at a first body end, a rod cavity at a second body end opposite said first body end, and a rod cavity wall;
- said rod cavity extending from said second body end to said rod cavity wall;
- an end cap attached to said cylinder body at said first body end;
- a piston assembly comprising a piston head, a piston rod, and a blow needle;
- said piston head connected to said piston rod;
- said piston rod connected to said blow needle;
- said piston rod slidable within said rod cavity;
- said piston head slidable within said head cavity;
- said piston head cooperating with said head cavity to define a head space between said piston head and said end cap and a heel space between said piston head and said rod cavity wall;
- an extend fluid port fluidly connected with said head space and fluidly connectable to a variable pressure fluid source for supplying an extend fluid;
- a retract fluid port fluidly connected with said heel space;
- and,
- a minimum pressure fluid source for supplying a retract fluid, fluidly connected to said retract fluid port.
A method for blow molding a container from a parison, comprising the steps of:
- providing a blow cylinder comprising
- a cylinder body having a head cavity at a first body end and a rod cavity wall,
- an end cap attached to said cylinder body at said first body end,
- a piston assembly comprising a piston head, a piston rod, and a blow needle,
- said piston head connected to said piston rod,
- said piston rod connected to said blow needle,
- said piston head slidable within said head cavity,
- said blow needle having an extended position, and
- said piston head cooperating with said head cavity to define a head space between said piston head and said end cap and a heel space between said piston head and said rod cavity wall;
- providing a minimum fluid pressure in said heel space;
- and,
- forcing an extend fluid at a pressure greater than said minimum fluid pressure into said head space for moving said blow needle to said extended position to engage a parison.
A blow cylinder for blow molding a container from a parison, comprising:
- extension means for moving a piston assembly to engage the parison by using an extend fluid under a variable pressure in conjunction with a retract fluid under a minimum pressure;
- and,
- retraction means for moving said piston assembly to disengage the container blow molded from the parison by using the extend fluid under the variable pressure in conjunction with the retract fluid under the minimum pressure.
Dependencies are inferred from the claim text.