Low-temperature glass container blowing process
A method of forming a glass container includes providing a glass parison having a tubular wall that includes an inside surface, which defines an interior parison cavity open at one axial end of the tubular wall, and an outside surface. The tubular wall includes an expandable blow portion that has a forming viscosity between 10 7.5 Pa·s and 10 5.5 Pa·s and is also in an isoviscous state. The glass parison is blow molded into a glass container by introducing a compressed gas into the interior parison cavity to thereby cause the expandable blow portion of the tubular wall to expand outwardly into a portion of a wall that defines the glass container.
1 . A method of forming a glass container, the method comprising:
providing a glass parison having a tubular wall that includes an inside surface, which defines an interior parison cavity open at one axial end of the tubular wall, and an outside surface, the tubular wall comprising an expandable blow portion having a forming viscosity between 10 7.5 Pa·s and 10 5.5 Pa·s and also being in an isoviscous state in which any temperature gradients within the expandable blow portion of the tubular wall of the glass parison translate into a maximum viscosity difference of 10 2 Pa·s or less; and
blow molding the glass parison into a glass container by introducing a compressed gas into the interior parison cavity while the expandable blow portion of the tubular wall has the forming viscosity and is in the isoviscous state to thereby cause the expandable blow portion of the tubular wall to expand outwardly into a portion of a wall that defines a glass container.
2 . The method set forth in claim 1 , wherein the tubular wall of the glass parison further includes a finish portion adjacent to an opening of the interior parison cavity, and wherein the finish portion of the tubular wall is not outwardly expanded during blow molding of the glass parison but instead retains a finish portion shape to provide a finish rim of the glass container.
3 . The method set forth in claim 2 , wherein the finish portion has a temperature that is less than a temperature of the expandable blow portion when the expandable blow portion is in the isoviscous state.
4 . The method set forth in claim 1 , wherein any temperature gradients within the expandable blow portion of the tubular wall translate into a maximum viscosity difference of 10 0.5 Pa·s or less.
5 . The method set forth in claim 1 , wherein any temperature gradients within the expandable blow portion of the tubular wall translate into a maximum viscosity difference of 10 0.02 Pa·s or less.
6 . The method set forth in claim 1 , wherein the glass parison is comprised of soda-lime-silica glass that includes 60 wt % to 80 wt % SiO 2 , 8 wt % to 18 wt % Na 2 O, and 5 wt % to 15 wt % CaO.
7 . The method set forth in claim 6 , wherein the soda-lime-silica glass of the glass parison further includes aluminum oxide in an amount up to 3 wt %.
8 . The method set forth in claim 1 , wherein providing the glass parison further comprises:
producing molten glass that is composed of a glass having glass transition temperature;
delivering a gob of glass obtained from the molten glass to a mold cavity of a blank mold;
shaping the gob of glass into the glass parison in the mold cavity of the blank mold by either pressing the gob of glass with a plunger or blowing the gob of glass with a compressed gas;
cooling the glass parison to a temperature below the glass transition temperature of the glass; and
heating the glass parison from the temperature below the glass transition temperature of the glass to bring the expandable blow portion of the tubular wall of the glass parison to a temperature corresponding to the forming viscosity and also to the isoviscous state.
9 . The method set forth in claim 1 , wherein providing the glass parison further comprises:
producing molten glass that is composed of a glass having a glass transition temperature;
delivering a gob of glass obtained from the molten glass to a mold cavity of a blank mold;
shaping the gob of glass into the glass parison in the mold cavity of the blank mold by either pressing the gob of glass with a plunger or blowing the gob of glass with a compressed gas; and
cooling the glass parison to bring the expandable blow portion of the tubular wall of the glass parison to a temperature corresponding to the forming viscosity and also to the isoviscous state.
10 . The method set forth in claim 1 , wherein providing the glass parison further comprises:
producing molten glass that is composed of a glass having a glass transition temperature;
obtaining a gob of glass from the molten glass;
bringing the gob of glass to a temperature corresponding to the forming viscosity and also to the isoviscous state; and
shaping the gob of glass while at the forming viscosity and also at the isoviscous state to form the glass parison.
11 . The method set forth in claim 10 , wherein bringing the gob of glass to the temperature corresponding to the forming viscosity and also to the isoviscous state comprises:
cooling the gob of glass to a temperature below the glass transition temperature of the glass; and
heating the gob of glass from the temperature below the glass transition temperature of the glass to the temperature corresponding to the forming viscosity and also to the isoviscous state.
12 . The method set forth in claim 10 , wherein bringing the gob of glass to the temperature corresponding to the forming viscosity and also to the isoviscous state comprises:
cooling the gob of glass to the temperature corresponding to the forming viscosity and also to the isoviscous state.
13 . The method set forth in claim 10 , wherein shaping the gob of glass into the glass parison comprises hot-pressing the gob of glass into the glass parison.
14 . The method set forth in claim 1 , wherein providing the glass parison further comprises:
producing molten glass that is composed of a glass having a glass transition temperature;
quenching a portion of the molten glass to form glass frit having a temperature below the glass transition temperature of the glass;
sintering the glass frit to form a solid glass monolith that has a temperature corresponding to the forming viscosity and is also at the isoviscous state;
shaping the solid glass monolith while at the forming viscosity and also at the isoviscous state to form the glass parison.
15 . The method set forth in claim 14 , wherein shaping the solid glass monolith into the glass parison comprises hot-stamping the solid glass monolith into the glass parison.
16 . A method of forming a glass container, the method comprising:
melting a glass feedstock to produce molten soda-lime-silica glass;
delivering a gob of soda-lime-silica glass to a mold cavity of a blank mold;
shaping the gob of soda-lime-silica glass into a glass parison in the mold cavity of the blank mold, the glass parison having a tubular wall that includes an inside surface, which defines an interior parison cavity open at one axial end of the tubular wall, and an outside surface, the tubular wall of the glass parison further comprising an expandable blow portion;
bringing the expandable blow portion of the glass parison to a forming viscosity between 10 7.5 Pa·s and 10 5.5 Pa·s and also to an isoviscous state in which any temperature gradients within the expandable blow portion of the tubular wall of the glass parison translate into a maximum viscosity difference of 10 2 Pa·s or less; and
blow molding the glass parison into a glass container by introducing a compressed gas into the interior parison cavity to thereby cause the expandable blow portion of the tubular wall to expand outwardly against an internal mold surface of a mold cavity of a blow mold.
17 . The method set forth in claim 16 , wherein bringing the expandable blow portion of the glass parison to the forming viscosity and also to the isoviscous state comprises:
cooling the glass parison to bring the expandable blow portion of the tubular wall of the glass parison to a temperature corresponding to the forming viscosity and also to the isoviscous state.
18 . The method set forth in claim 16 , wherein bringing the expandable blow portion of the glass parison to the forming viscosity and also to the isoviscous state comprises:
cooling the glass parison to a temperature below a glass transition temperature of the soda-lime-silica glass; and
heating the glass parison from below the glass transition temperature of the soda-lime-silica glass to bring the expandable blow portion of the tubular wall of the glass parison to a temperature corresponding to the forming viscosity and also to the isoviscous state.
19 . The method set forth in claim 16 , wherein the tubular wall of the glass parison further includes a finish portion adjacent to an opening of the interior parison cavity, and wherein the finish portion of the tubular wall is not outwardly expanded during blow molding of the glass parison but instead retains a finish portion shape to provide a finish rim of the glass container.
20 . A method of forming a glass container, the method comprising:
loading a glass parison into a blow mold that defines a mold cavity, the glass parison having a tubular wall that includes an inside surface, which defines an interior parison cavity open at one axial end of the tubular wall, and an outside surface, the tubular wall comprising an expandable blow portion having a forming viscosity between 10 7.5 Pa·s and 10 5.5 Pa·s and also being in an isoviscous state in which any temperature gradients within the expandable blow portion of the tubular wall of the glass parison translate into a maximum viscosity difference of 10 2 Pa·s or less; and
introducing a compressed gas into the interior parison cavity of the tubular wall of the glass parison to outwardly expand the expandable blow portion of the tubular wall, thereby forming a glass container from the glass parison, the glass container comprising a wall that provides a main body and a finish rim that extends axially from the main body, wherein a thickness of the wall of the glass container in the main body is less than a thickness of the tubular wall of the glass parison.