Stress features for crack redirection and protection in glass containers
A glass container comprises a glass body comprising a first region under a compressive stress extending from a surface of the glass body to a depth of compression and a second region extending from the depth of compression into a thickness of the glass body, the second region being under a tensile stress. The glass container also includes a localized compressive stress region having a localized compressive stress extending from the surface to a localized depth of compression within the body. The localized depth of compression is greater than the depth of compression of the first region. The glass container also includes a crack re-direction region extending in a predetermined propagation direction, wherein the crack re-direction region possesses a higher tensile stress than the tensile stress in the second region in a sub-region of the crack re-direction region, the sub-region extending substantially perpendicular to the predetermined propagation direction.
1. A method of making a glass container having a first surface and a second surface separated by a thickness, the method comprising:
forming a first region under a compressive stress on the first surface of the glass container, wherein the first region extends from the first surface to a depth of compression in the glass container;
forming a second region under a central tension, the second region extending from the depth of compression into the thickness, wherein the central tension is sufficient for self-propagation of a crack at the first surface from an origination point of the crack; and
forming a crack re-direction region in the first surface, wherein:
the crack re-direction region extends in a predetermined propagation direction for the crack, and
the crack re-direction region comprises a higher central tension than a remainder of the glass article in a direction substantially perpendicular to the predetermined propagation direction such that, upon the crack propagating and reaching the crack re-direction region, the crack is redirected along the predetermined propagation direction,
wherein the glass container comprises a body having an interior surface and an exterior surface, the interior surface defining an interior volume having an axis, wherein the predetermined propagation direction is substantially perpendicular to the axis, and
wherein the thickness of the glass container varies within the crack re-direction region such that the crack re-direction region comprises a thin region extending substantially parallel to the axis where the thickness is less than an average thickness of the glass container within the crack re-direction region.
2. The method of claim 1 , wherein the crack-redirection direction region extends around at least a portion of an outer circumference of the glass container.
3. The method of claim 2 , wherein the thickness of the glass article in the crack re-direction region varies sinusoidally parallel to the axis.
4. The method of claim 2 , wherein the crack re-direction region extends around an entirety of the outer circumference of the glass container.
5. The method of claim 1 , wherein the first surface is the exterior surface of the glass container.
6. The method of claim 1 , wherein the first surface is the interior of the glass container.
7. The method of claim 1 , wherein forming the first and second regions comprises:
forming the glass container from a glass composition; and
forming the first region and the second region by subjecting the first surface of the glass container to chemical tempering.
8. The method of claim 7 , wherein the glass composition comprises an aluminosilicate glass composition.
9. The method of claim 7 , wherein forming the glass article from the glass composition comprises:
forming a glass tube comprising the glass composition; and
converting the glass tube into the glass container, wherein forming the crack re-direction region occurs during the conversion of the glass tube into the glass container.
10. The method of claim 9 , wherein forming the crack re-direction region comprises scanning a pulsed laser beam in a predetermined pattern while the glass tube is heated to a softening temperature of the glass composition during the converting of the glass tube into the glass container.
11. A method of forming a glass container having a crack re-direction region, the method comprising:
providing a stock material formed from a glass composition, the stock material comprising glass tubing;
converting the glass tubing into a glass article having a body extending between an interior surface and an exterior surface defining an interior volume;
forming a compressively stressed layer in the glass article, the compressively stressed layer extending from at least one of the interior surface and the exterior surface to a depth of compression in a thickness of the body; and
forming the crack re-direction region within the glass article, wherein the crack re-direction region comprises a sub-region having a higher central tension than a remainder of the glass article, wherein the sub-region extends in a direction substantially perpendicular to a predetermined propagation direction and the thickness of the sub-region is less than an average thickness of the body,
wherein forming the crack re-direction region comprises forming the sub-region of the crack re-direction region during the converting of the glass tubing into the glass article, and
wherein forming the sub-region comprises contacting the glass tubing during the conversion of the glass tubing into the glass article with a shaping element.
12. The method of claim 11 , wherein forming the sub-region comprises scanning a pulsed laser beam in a predetermined pattern on the glass article.
13. A glass container comprising:
a glass body comprising a first region under a compressive stress extending from a surface of the glass body to a depth of compression and a second region extending from the depth of compression into a thickness of the glass body, the second region under a tensile stress sufficient for self-propagation of a crack from an origination point of the crack in a propagation direction; and
a crack re-direction region on the surface of the glass body, the crack re-direction region extending in a predetermined propagation direction for the crack, wherein the crack re-direction region comprises a greater tensile stress than the tensile stress in the second region in a sub-region of the crack re-direction region, the sub-region extending substantially perpendicular to the predetermined propagation direction such that, upon the crack propagating into the crack re-direction region, the crack is redirected along the predetermined propagation direction,
wherein the predetermined propagation direction is a circumferential direction substantially perpendicular to an axis of the glass container, and
wherein the thickness varies within the crack re-direction region such that the sub-region of the crack re-direction region comprises a thin region extending substantially parallel to the axis where the thickness is less than an average thickness of the glass article.
14. The glass container of claim 13 , wherein the glass container comprises one of a bottle, vial, ampoule, syringe, or cartridge.
15. A method of forming a glass container, the method comprising:
providing a stock material formed from a glass composition;
shaping the stock material into a glass article having a body extending between an interior surface and an exterior surface, the body defining an interior volume;
forming a crack re-direction region within the glass article, wherein the crack re-direction region comprises a sub-region having a higher central tension than a remainder of the glass article, wherein the sub-region extends in a direction substantially perpendicular to a predetermined propagation direction; and
forming a localized compressive stress region in the glass article, the localized compressive stress region having a localized compressive stress extending from the interior surface or the exterior surface to a localized depth of compression within the body, wherein the localized depth of compression is greater than or equal to 2% of a thickness of the body and less than or equal 25% of the thickness of the body, wherein forming the localized compressive stress region comprises locally applying a coolant to a portion of the glass article when the glass article is heated to a starting temperature above a softening temperature of the glass composition.
16. The method of claim 15 , further comprising forming a compressively stressed layer in the glass article, the compressively stressed layer extending from at least one of the interior surface and the exterior surface to a depth of compression into a thickness of the body.
17. The method of claim 16 , wherein forming the compressively stressed layer comprises subjecting the glass article to ion-exchange strengthening after forming the localized compressive stress region to form a first region on the exterior surface under a compressive stress, the first region extending from the exterior surface to the depth of compression, wherein the depth of compression is less than the localized depth of compression.
18. The method of claim 17 , wherein the localized compressive stress region overlaps with the first region on the external surface.
19. The method of claim 18 , wherein the crack re-direction region overlaps with the localized compressive stress region on the external surface.
20. The method of claim 15 , further comprising flame washing an entirety of the exterior surface prior to forming the localized compressive stress region to eliminate conversion flaws induced by the shaping of the stock material into the glass article.
21. The method of claim 15 , wherein locally applying the coolant to the portion of the glass article comprises:
positioning a collar proximate to the portion of the glass article when the glass article is heated to the starting temperature, the collar including at least one feed for the coolant, wherein the collar is shaped in a manner that corresponds to the portion of the glass article; and
providing the coolant to the portion of the glass article to form the localized compressive stress region.
22. The method of claim 21 , wherein the collar comprises contact points that contact the portion of the glass article to control a gap between a fluid manifold of the collar and the portion of the glass article.
23. The method of claim 22 , wherein the glass container comprises a vial having a base, a barrel connected to the base via a heel, a shoulder extending from the barrel, and a neck extending from the shoulder, wherein the portion of the glass article to which the coolant is applied comprises at least one of the neck and the heel.
24. The method of claim 15 , wherein forming the crack re-direction region comprises forming the sub-region of the crack re-direction region during the shaping of the stock material into the glass article, wherein a thickness of the sub-region is less than an average thickness of the body.
25. The method of claim 24 , wherein forming the sub-region comprises scanning a pulsed laser beam in a predetermined pattern on the glass article.
26. The method of claim 24 , wherein forming the sub-region comprises contacting the stock material during the shaping of the stock material into the glass article with a shaping element having a shape corresponding to a predetermined shape of the sub-region.
27. The method of claim 15 , wherein a thickness of a portion of the crack re-direction region is greater than an average thickness of the body.