Apparatus and method for severing a glass sheet

Abstract

A method for severing a glass sheet includes preferentially heating a region of the glass sheet to form a softened region. A slit is formed in the softened region of the glass sheet to form a slit region. The slit extends at least partially into a thickness of the glass sheet. Heat is preferentially applied to the slit region of the glass sheet.

What is claimed is: 
     
         1 . A method for severing a strengthened glass laminate comprising a glass core layer fused to each of a first glass cladding layer and a second glass cladding layer, each of the first glass cladding layer and the second glass cladding layer comprising a lower coefficient of thermal expansion than the glass core layer such that the glass core layer comprises a tensile stress, the method comprising:
 preferentially heating a region of the glass laminate to at least a softening temperature of the glass laminate to form a malleable region;   shearing the malleable region of the glass laminate to form a slit extending at least partially into a thickness of the glass laminate and to urge the first glass cladding layer and the second glass cladding layer toward each other; and   preferentially applying heat to the slit.   
     
     
         2 . The method of  claim 1 , wherein the shearing the malleable region of the glass laminate wraps the first glass cladding layer and the second glass cladding layer around the glass core layer. 
     
     
         3 . The method of  claim 1 , wherein the preferentially applying heat to the slit comprises applying heat sufficient to sever the glass laminate into first and second portions. 
     
     
         4 . The method of  claim 1 , wherein
 subsequent to the shearing the malleable region, a first portion of the glass laminate positioned on a first side of the slit and a second portion of the glass laminate positioned on a second side of the slit opposite the first portion are attached to one another by a membrane that is thinner than the glass laminate; and   the preferentially applying heat to the slit severs the membrane to separate the first portion and the second portion of the glass laminate from each other.   
     
     
         5 . The method of  claim 1 , wherein the shearing the malleable region envelops the core glass layer within a shell comprising the first cladding layer and the second cladding layer. 
     
     
         6 . The method of  claim 1 , wherein the shearing the malleable region causes the first cladding layer and the second cladding layer to move into contact with each other. 
     
     
         7 . The method of  claim 1 , wherein the core layer comprises a tension of at least about 30 MPa. 
     
     
         8 . The method of  claim 1 , wherein the core layer comprises a tension of at least about 65 MPa. 
     
     
         9 . The method of  claim 1 , wherein the core layer comprises a tension of at least about 100 MPa. 
     
     
         10 . The method of  claim 1 , wherein:
 the shearing the malleable region comprises passing the malleable region of the glass laminate between a first shearing member and a second shearing member in a traveling direction; and   the first shearing member and the second shearing member are misaligned with one another in the traveling direction to urge an edge of the first cladding layer adjacent to the slit and an edge of the second cladding layer adjacent to the slit toward each other.   
     
     
         11 . The method of  claim 1 , wherein:
 the preferentially heating the region of the glass sheet comprises moving one of a first heating unit and the glass sheet relative to the other;   the forming the slit in the softened region comprises moving one of a shearing unit and the glass sheet relative to the other; and   the preferentially applying heat to the slit region comprises moving one of a second heating unit and the glass sheet relative to the other.   
     
     
         12 . The method of  claim 11 , wherein the first heating unit, the shearing unit, and the second heating unit are coupled to each other such that moving the glass sheet relative to the coupled first heating unit, shearing unit, and second heating unit causes the first heating unit, the shearing unit, and the second heating unit to move successively along a path on the glass laminate. 
     
     
         13 . The method of  claim 11 , wherein the first heating unit, the shearing unit, and the second heating unit are aligned with each other in a traveling direction, and the method further comprises moving the glass laminate relative to the first heating unit, the shearing unit, and the second heating unit in the traveling direction to cause the first heating unit, the shearing unit, and the second heating unit to progress successively along a path on the glass laminate. 
     
     
         14 . The method of  claim 13 , wherein the glass laminate comprises a glass ribbon moving continuously relative to the first heating unit, the shearing unit, and the second heating unit in the traveling direction, and the path extends substantially parallel to a side edge of the glass ribbon. 
     
     
         15 . The method of  claim 1 , comprising maintaining a remote region of the glass laminate disposed away from the malleable region at a temperature below the softening temperature of the glass laminate. 
     
     
         16 . The method of  claim 1 , wherein the preferentially applying heat to the slit comprises directing a flame toward the slit in the glass laminate. 
     
     
         17 . A method for severing a strengthened glass sheet comprising a glass core layer fused to each of a first glass cladding layer and a second glass cladding layer, each of the first glass cladding layer and the second glass cladding layer comprising a lower coefficient of thermal expansion than the glass core layer such that the glass core layer comprises a tensile stress, the method comprising:
 advancing a first heating unit relative to the glass sheet along a path to preferentially heat a region of the glass sheet to at least a softening temperature of the glass sheet to form a malleable region;   advancing a shearing unit relative to the glass sheet along the path to squeeze the malleable region of the glass sheet to wrap the first glass cladding layer and the second glass cladding layer around the glass core layer at a slit; and   advancing a second heating unit relative to the glass sheet along the path to preferentially apply heat to the slit.   
     
     
         18 . The method of  claim 17 , wherein the first heating unit, the shearing unit, and the second heating unit are aligned with one another along an axis such that, in response to movement of the glass sheet in an axial direction, the first heating unit, the shearing unit, and the second heating unit advance successively along the path. 
     
     
         19 . The method of  claim 17 , wherein the path forms a closed loop. 
     
     
         20 . A glass laminate comprising:
 a glass core layer fused to each of a first glass cladding layer and a second glass cladding layer, each of the first glass cladding layer and the second glass cladding layer comprising a lower coefficient of thermal expansion than the glass core layer such that the glass core layer comprises a tensile stress;   wherein the glass core layer is enveloped within a shell comprising the first glass cladding layer and the second glass cladding layer; and   wherein an end portion of the shell is thinner than a remainder of the shell.