Patent ID: 8359887

Claim:
A method of producing sheets of glass having two faces with at least one of said faces presenting a high surface quality, the method comprising: (a) delivering a first stream of glass having a viscosity in the range of about 100 poises to 10,000 poises, said stream of glass having a first face and second face, each face is free from making contact with any surface and thus possibly being destabilized mechanically; (b) treating said delivered stream of glass prior to destabilization by putting a first face into contact with a surface of a treatment device suitable, temporarily, to support the weight of said stream of glass and for accompanying the falling movement of said stream of glass while controlling the interfacial temperature between the stream of glass and the surface of the treatment device thereby, temporarily, creating a controllable reversible interfacial adhesion force between the stream of glass and the surface that is sufficient to prevent a slippage of the stream of glass with respect to the surface in order to stabilize the stream glass and increasing the viscosity of the stream of glass to a range from about 10 9 poise to about 10 11 poise, while maintaining at least a central strip of said second face free from any contact with any surface; (c) using a device or mechanism for controlling glass travel speed to act on the delivered stream after treating, at a suitable distance downstream to provide a sheet of glass; and (d) cooling said sheet of glass; (e) wherein the treating step comprises controlling the interfacial temperature using the following equation: T 1 ⁢ S ⁡ ( t ) - T 2 ⁢ S ⁡ ( t ) T 1 - T 2 = exp ⁡ ( t τ ) × erfc ⁡ ( t τ ) ⁢ ⁢ where ⁢ ⁢ τ = ( b 1 ⁢ b 2 h l ⁡ ( b 1 + b 2 ) ) 2 wherein T 1 s (t) is the temperature of a first material at the interface over time (t), wherein T 2 s (t) is the temperature of a second material at the interface over time (t), hi is the interfacial heat transfer coefficient (W/m2·K), b 1 is (λ·p·cp)½ for the materials, λ is the thermal conductivity of the material (W/m·K), p is the density of the material (kg/m3), cp is the heat capacity of the material (J/kg·K).