US 3,961,927 A · Apparatus and method for moulding glass objects

Abstract

A method of shaping glass to a desired form comprises delivering molten glass on to a porous support member while feeding a gas under pressure through the porous support member from the reverse side thereof, so as to support the molten glass out of contact with the support member on a cushion of gas, allowing the glass to assume a shape approximating to that of the support member under the forces of surface tension, gravity and gas cushion pressure, cooling the glass while thus supported on the gas cushion to a temperature at which it is so conditioned that it can be shaped by contact with a solid surface without any substantial surface damage, and shaping the conditioned glass by a shaping process which involves contact with a solid surface. The shaping process may be a moulding process, which can be carried out either in the porous support member or in a separate mould to which the glass is transferred. The gas, e.g. nitrogen or nitrogen + 5% hydrogen, may be fed to the porous support member at ambient temperature. Alternatively, for controlling the rate of heat transfer from the supported glass, the temperature and/or flow rate of the gas may be controlled, or the temperature of the environment of the porous support member may be controlled, e.g. using a muffle. The shaping process may alternatively be a rolling process, the glass flowing from a channel-shaped porous support member to a pair of rollers.

Claims50

Dependent claims

A method of shaping glass to a desired form in which delivered molten glass can be brought to a suitable viscosity condition for shaping independently of the viscosity of delivery, the method comprising:

feeding gas under pressure through minute, tortuous, gas flow channels of a porous wall of a support member, located at least at the base of the support member, from the reverse side of said wall into a support cavity defined by a cavity surface presented by the support member;
delivering molten glass into the support cavity, while so feeding the gas under a pressure
sufficient to support the glass, while it is in a viscosity condition wherein it can distort or flow, out of contact with the cavity surface on a cushion of gas, but
insufficient to induce perceptible gas stream or blast to blow from the cavity surface so as to push the glass actively away from the cavity surface;
maintaining the glass floating freely in the support cavity on the established gas cushion support of the glass, out of contact with the cavity surface, for a hold time during which
the glass in the support cavity is allowed to assume, under the forces of surface tension, gravity and gas cushion pressure, a shape approximating to that of the support cavity and having a fire-finished glass surface, and
the glass is cooled to a viscosity condition such that it can be further shaped by contact with a solid surface without any substantial surface damage to the fire-finished glass surface formed on the gas cushion;
and
shaping the so conditioned glass by a shaping process which involves contact with such a solid surface.

6 more elements

Apparatus for shaping glass to a desired form in which delivered molten glass can be brought to a suitable viscosity condition for shaping independently of the viscosity of delivery, the apparatus comprising:

a support member having a porous wall located at least at the base thereof and presenting minute, tortuous, gas flow channels, said support member presenting a cavity surface defining a support cavity;
means for delivering molten glass into said support cavity;
means for feeding gas through said porous wall of said support member, from the reverse side thereof into said support cavity at a pressure
sufficient to support the glass, while it is in a viscosity condition wherein it can distort or flow, out of contact with the cavity surface on a cushion of gas, but
insufficient to induce a perceptible gas stream or blast to blow from the cavity surface so as to push the glass actively away from that cavity surface;
said gas feeding means and said support cavity being cooperable to maintain the glass floating freely in the support cavity on the established gas cushion support of the glass, out of contact with the cavity surface, for a hold time during which
the glass in the support cavity is allowed to assume, under the forces of surface tension, gravity and gas cushion pressure, a shape approximating to that of the support cavity and having a fire-finished glass surface;
and
the glass is cooled to a viscosity condition such that it can be further shaped by contact with a solid surface without any substantial surface damage to the fire-finished glass surface formed on the gas cushion;
and
means for subsequently shaping the so conditioned glass by a shaping process which involves contact with a solid surface.

8 more elements

Dependencies are inferred from the claim text.

Apparatus and method for moulding glass objects

Life of this patent

Apparatus and method for moulding glass objects

Life of this patent

Abstract

Claims50