System and method for forming fused quartz glass

A method for making a fused quartz glass vessel, the method comprising the steps of:

• (a) providing a starting body made of fused quartz glass, the starting body having an interior cavity;
• (b) positioning the starting body on a base plate;
• (c) in a first forming stage,
• (i) inserting a first insert device into the interior cavity of the starting body to form a first assembled structure,
• (ii) heating the first assembled structure to a predetermined temperature at which the fused quartz glass of the starting body has a viscosity in a range of 105 to 1013 poise, and
• (iii) deforming the fused quartz glass of the starting body at the predetermined temperature or in the viscosity range of 105 to 1013 poise around the first insert device to form an intermediate body made of fused quartz glass;
• and
• (d) in a second forming stage,
• (i) removing the first insert device and inserting a second insert device into an interior cavity of the intermediate body to form a second assembled structure, the second insert device having an overall size different from that of the first insert device, and
• (ii) heating the second assembled structure to the predetermined temperature while simultaneously pressing an exterior surface of the intermediate body by a pressing plate to cause deformation of the intermediate body around the second insert device to form a fused quartz glass vessel.

A forming assembly for forming fused quartz glass comprising:

• a base plate configured to support a body made of fused quartz glass;
• a pressing plate configured to press on the body during heating of the body;
• a first insert device and a second insert device, each of the first and second insert devices being configured to be separately received within the body;
• and
• a heating device configured to heat the body to a temperature in a range of 1200° C. to 1700° C. such that the fused quartz glass has a viscosity in a range of 105 to 1013 poise.