Method and device for homogenizing glass

Patent metadata

Field	Value
Publication number	US-2020131069-A1
Application number	US-201916662610-A
Country	US
Kind code	A1
Filing date	Oct 24, 2019
Priority date	Oct 26, 2018
Publication date	Apr 30, 2020
Grant date	—

Abstract

A known method for homogenizing glass includes the following steps: providing a cylindrical blank composed of the glass, having a cylindrical outer surface which extends between a first end face and a second end face, forming a shear zone in the blank by softening a longitudinal section of the blank and subjecting it to a thermal-mechanical intermixing treatment, and moving the shear zone along the longitudinal axis of the blank. To reduce the risk of cracks and fractures during homogenizing, it is proposed that a thermal radiation dissipator is used that at least partially surrounds the shear zone, the lateral dimension of which in the direction of the longitudinal axis of the blank is greater than the shear zone and smaller than the length of the blank, the thermal radiation dissipator being moved synchronously with the shear zone along the longitudinal axis of the blank.

First claim

1 . A method for homogenizing glass, comprising:
(a) providing a cylindrical blank composed of the glass, having a cylindrical outer surface which extends along a longitudinal axis of the blank over a length of the blank between a first end face and a second end face; (b) forming a shear zone in the blank by softening a longitudinal section of the blank and subjecting it to a thermal-mechanical intermixing treatment; and (c) moving the shear zone along the longitudinal axis of the blank,
wherein a thermal radiation dissipator is used that at least partially surrounds the shear zone, the lateral dimension of which in the direction of the longitudinal axis of the blank is greater than the shear zone and smaller than the length of the blank, the thermal radiation dissipator being moved synchronously with the shear zone along the longitudinal axis of the blank.

2 . The method according to claim 1 , wherein between the thermal radiation dissipator and the cylindrical outer surface of the blank a clearance in the range of 15% to 80% of the diameter of the blank is established.

3 . The method according to claim 1 , wherein the thermal radiation dissipator comprises a wall with a glass layer, facing the shear zone, composed of a quartz glass that is transparent to infrared radiation from the NIR wavelength range.

4 . The method according to claim 1 , wherein the thermal radiation dissipator comprises a layer composed of opaque quartz glass.

5 . The method according to claim 4 , wherein the layer composed of opaque quartz glass borders the glass layer or merges into the glass layer.

6 . The method according to claim 4 , wherein the opacity of the layer composed of opaque quartz glass is caused by a porosity of the quartz glass in the range of 2 to 8%.

7 . A device for homogenizing a cylindrical blank composed of glass having a cylindrical outer surface which extends along a longitudinal axis of the blank over a length of the blank between a first end face and a second end face, comprising:
(a) a supporting and rotating means with a first supporting element for the mounting and rotating of the first end face of the blank at a first rotational speed, and a second supporting element for the mounting and rotating of the second end face of the blank at a second rotational speed, wherein the first and the second supporting element define a working distance (D) and a working axis (A) of the supporting and rotating means; (b) a heating means for softening a longitudinal section of the blank; and (c) a displacement means for generating a relative motion between heating means and blank along the working axis (A),
wherein the heating means comprises a heat source and a thermal radiation dissipator, wherein the thermal radiation dissipator has a lateral dimension in the direction of the working axis (A) which is smaller than the working distance (D).

8 . The device according to claim 7 , wherein the thermal radiation dissipator is adjusted to the diameter of the blank that is to be processed such that between the cylindrical outer surface of the thermal radiation dissipator and the blank a clearance in the range of 15% to 80% of the diameter of the blank is obtained.

9 . The device according to claim 7 , wherein the thermal radiation dissipator has a reflective internal surface facing the shear zone.

10 . The device according to claim 9 , wherein the reflective internal surface is formed by a glass layer composed of a quartz glass that is transparent to infrared radiation from the NIR wavelength range.

11 . The device according to claim 10 , characterized in that the transparent quartz glass of the glass layer transmits at least 50% of the incident NIR radiation power at a sample thickness of 10 mm.

12 . The device according to claim 7 , wherein the thermal radiation dissipator comprises a layer composed of opaque quartz glass.

13 . The device according to claim 12 , wherein the layer composed of opaque quartz glass borders the glass layer or merges into the glass layer.

14 . The device according to claim 12 , wherein the opacity of the layer composed of opaque quartz glass is caused by a porosity of the quartz glass in the range of 2 to 8%.

15 . The device according to claim 7 , wherein the thermal radiation dissipator consists of quartz glass, which has been produced synthetically from silicon-containing starting substances by pyrolysis or hydrolysis.

Assignees

• Heraeus Quarzglas

Inventors

• Thomas Stephan
• Vydra Jan
• Trommer Martin
• Huenermann Michael
• Langner Andreas
• Lehmann Walter
• Hengster Stefan
• Becker Klaus

Classifications

• C03B20/00 Primary

  Processes specially adapted for the production of quartz or fused silica articles {, not otherwise provided for (C03B19/01, C03B19/066, C03B19/106, C03B19/12, C03B19/14, C03B37/00 take precedence)} · CPC title

• C03B19/1469

  Means for changing or stabilising the shape or form of the shaped article or deposit · CPC title

• C03C2203/52

  Heat-treatment · CPC title

• C03B5/185 Primary

  Electric means · CPC title

• C03B2207/20

  Specific substances in specified ports, e.g. all gas flows specified · CPC title