A method of making a glass sheet comprises laminating a high CTE core glass to a low CTE clad glass at high temperatures and allowing the laminate to cool creating compressive stress in the clad glass, and then ion exchanging the laminate to increase the compressive stress in the outer near surface regions of the clad glass. The core glass may include ions that exchange with ion in the clad glass to increase the compressive stress in inner surface regions of the clad glass adjacent to the clad glass/core glass interfaces. The glass laminate may be formed and laminated using a fusion forming and laminating process and fusion formable and ion exchangeable glass compositions.

Methods for producing glass articles from laminated glass tubing include introducing the glass tubing to a converter. The glass tubing includes a core layer under tensile stress, an outer clad layer under, and an inner clad layer. The methods include forming a feature the glass article at a working end of the laminated glass tubing and separating a glass article from the working end of the laminated glass tubing, which may expose the core layer under tensile stress at the working end of the glass tubing. The method further comprises remediating the exposed portion of the core layer by completely enclosing the core layer in a clad layer. Systems for re-cladding the exposed portion of the core layer as well as glass articles made using the systems and methods are also disclosed.

Provided is a sleeve for glass tube molding that, without reducing the mechanical strength of the sleeve shaft, can prevent foreign objects such as rust from generating off the sleeve shaft and can prevent foreign objects such as rust from adhering to molten glass. The sleeve for glass tube molding is equipped with a sleeve shaft having a through-hole, and is equipped with a pipe member comprising a material having superior rust resistance to the sleeve shaft. The pipe member is provided with a main body portion, and a tapered portion. The through-hole is provided with an insertion portion into which the main body portion is inserted, and a contact portion with a tapered shape whereat the outer peripheral surface of the tapered portion comes into contact with one end of the through-hole. A portion or all of the inner surface of the through-hole is covered by inserting the pipe member into the through-hole.

An apparatus for producing composite glass tube with a plurality of glass layers includes a plurality of cylindrical containers of increasing inner dimensions concentrically arranged and stationary. Each cylindrical container includes a side wall, bottom wall, and a delivery ring. Adjacent cylindrical containers define an annular chamber, a flow control region, and an annular flow channel therebetween. The apparatus includes at least one flow control valve positioned in the flow control region and translatable relative to the adjacent cylindrical containers. Translation of the flow control valves relative to the cylindrical containers is operable to change an impedance to flow of molten glass through the flow control region, thereby modifying an overall flow rate or circumferential distribution of molten glass from the cylindrical containers. Systems and methods for producing composite glass tube using the apparatus are also disclosed.

An apparatus for producing composite glass tube with a plurality of glass layers includes a plurality of cylindrical containers of increasing inner dimensions concentrically arranged and stationary. Each cylindrical container includes a side wall, bottom wall, and a delivery ring. Adjacent cylindrical containers define an annular chamber, a flow control region, and an annular flow channel therebetween. The apparatus includes at least one flow control valve positioned in the flow control region and translatable relative to the adjacent cylindrical containers. Translation of the flow control valves relative to the cylindrical containers is operable to change an impedance to flow of molten glass through the flow control region, thereby modifying an overall flow rate or circumferential distribution of molten glass from the cylindrical containers. Systems and methods for producing composite glass tube using the apparatus are also disclosed.

An apparatus for forming glass tubing is described. The apparatus for forming glass tubing comprises an endless former with an outer surface and an inner passage defining an inner surface. The apparatus for forming glass tubing further comprises two chambers from which molten glass may flow. One chamber flows molten glass to the outer surface of the endless former and another chamber flows molten glass to the inner surface of the endless former. The two flows of molten glass meet at the bottom of the former to form glass tubing.

A laminated or single layer glass cylinder and its method of making are disclosed. The laminated cylinder glass is a precursor component to enable making subsequent drawn tubing having high optical quality. The laminated cylinder glass may comprise a first layer of glass as a clad glass and a second layer of glass as a core glass. The second layer of glass may be bound to the first layer of glass. The second layer may have a higher CTE from about 510.sup.7/ C. to about 10010.sup.7/ C. than the first layer of glass. The first layer and second layer of glass may have different softening points within about 200 C. of each other. In some embodiments, the first layer and second layer of glass may have different softening points from about 50 C. to about 200 C. of each other.

An apparatus for forming glass tubing is described. The apparatus for forming glass tubing comprises an endless former with an outer surface and an inner passage defining an inner surface. The apparatus for forming glass tubing further comprises two chambers from which molten glass may flow. One chamber flows molten glass to the outer surface of the endless former and another chamber flows molten glass to the inner surface of the endless former. The two flows of molten glass meet at the bottom of the former to form glass tubing.

A laminated or single layer glass cylinder and its method of making are disclosed. The laminated cylinder glass is a precursor component to enable making subsequent drawn tubing having high optical quality. The laminated cylinder glass may comprise a first layer of glass as a clad glass and a second layer of glass as a core glass. The second layer of glass may be bound to the first layer of glass. The second layer may have a higher CTE from about 510.sup.7/ C. to about 10010.sup.7/ C. than the first layer of glass. The first layer and second layer of glass may have different softening points within about 200 C. of each other. In some embodiments, the first layer and second layer of glass may have different softening points from about 50 C. to about 200 C. of each other.

A method and a device for encasing gemstones, such as diamonds, in glass. In order for their optical effects and appearance to be maximized, the gemstones are placed at a defined position and at a defined orientation. A suction cannula is provided for that purpose with an opening to fit the gemstone and to hold the gemstone by vacuum. Guide elements, such as spirals or meshes, are carried on the suction cannula so as to assure even distancing from the walls of the glass tube into which the gemstone is inserted.