Laminated Glass Tubes and Their Manufacture

A glass tube manufactured according to a method comprising:

• nesting a smaller tube within a larger tube;
• filling a space which is formed between the smaller and larger tube with colored, patterned, or clear glass rods or bars to form an assembly;
• attaching the assembly to a linear motion mechanism;
• using the linear motion mechanism to pass the assembly through a high-temperature furnace having a temperature above the glass transition temperature of the glasses used to build the assembly, causing the glasses to collapse towards each other once they reach a plastic state, and causing the outer tube and inner tube to seal against the colored, patterned, or clear glass rods or bars that were held captive;
• whereby the glass tube produced by the method has dimensional uniformity as perceived visually throughout the glass tube.

A machine for manufacturing a glass tube, comprising:

• a platform configured to hold a glass preform assembly;
• a linear motion mechanism configured to raise or lower the platform at a controlled rate such that the preform assembly passes through a high-temperature furnace;
• a stage or pedestal configured to support a bottom of the glass preform assembly as the glass preform assembly is heated to a plastic state by the high-temperature furnace;
• and
• a mechanism configured to raise or lower the stage or pedestal at a controlled rate to control a rate of passage of the glass out of the high-temperature furnace.