# US 2014/0196505 A1 · Glass preform heating furnace

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- Number: US 2014/0196505 A1
- Document ID: US20140196505A1
- Status: Published application
- Kind: A1
- Application number: 14/129,673
- Filed: 2012-06-13
- Published: 2014-07-17
- Earliest claimed: 2011-06-29
- Assignees: Sumitomo Electric Industries, Ltd.
- Inventors: Tadashi Enomoto; Iwao Okazaki; Takashi Yamazaki; Masatoshi Hayakawa
- Web page: https://patentgrep.com/patent/US20140196505A1

## CPC

- C03B 37/029: Furnaces therefor
- C03B 37/01257: {Heating devices therefor}
- F27B 17/00: Furnaces of a kind not covered by any of groups F27B1/00 - F27B15/00 (structural combinations of furnaces F27B19/02)
- H05B 3/62: Heating elements specially adapted for furnaces (H05B3/60 takes precedence; arrangements of elements for electric heating in or on furnaces using ohmic resistance heating F27D11/02)
- C03B 2205/63: Ohmic resistance heaters, e.g. carbon or graphite resistance heaters
- H05B 2203/025: Heaters specially adapted for glass melting or glass treatment
- C03B: MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- F27B: FURNACES, KILNS, OVENS OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
- H05B: ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL

## Abstract

The present invention provides a glass preform heating furnace in which the occurrence of arching is suppressed. The glass preform heating furnace is equipped with a susceptor (3); a slit heater (4); an insulator; and a furnace body, wherein, in the case that the space between the slit heater (4) and the susceptor or between the slit heater (4) and the conductive member closest to the slit heater is D, that the maximum value of the electric field in this space is E1, that the number of the slits in the slit heater is N, that the slit width of the slit heater is S, and that the maximum value of the electric field in the slit space is E2, the values of D, N and S are set so that E1≧E2 is established.

## Claims

### Claim 1

A glass preform heating furnace comprising:
a susceptor to which a glass preform is supplied;
a slit heater in which slits are cut in a cylindrical member enclosing the susceptor from the upper and lower ends of the cylindrical member alternately;
an insulator enclosing the exterior of the slit heater; and
a furnace body enclosing the whole,
wherein,
in the case that the space between the slit heater and the susceptor or between the slit heater and the conductive member closest to the slit heater is D, that the maximum value of the electric field in this space is E1, that the number of the slits in the slit heater is N, that the slit width of the slit heater is S, and that the maximum value of the electric field in the slit space is E2,
the values of D, N and S are set so that E1≧E2 is established.

### Claim 2 (depends on 1)

The glass preform heating furnace of claim 1,
wherein the slit heater is a single-phase slit heater, and the slit width S of the single-phase slit heater is set to 8×(D/N) or more.

### Claim 3 (depends on 1)

The glass preform heating furnace of claim 1,
wherein the slit heater is a three-phase slit heater, and the slit width S of the three-phase slit heater is set to 9×(D/N) or more.

### Claim 4 (depends on 3)

The glass preform heating furnace of claim 3,
wherein the slit width S of the three-phase slit heater is set to 12×(D/N) or more.

### Claim 5 (depends on 1)

The glass preform heating furnace of claim 1,
wherein the slit width S of the slit heater is satisfied at least in the slits adjacent to the terminal sections of the slit heater.

### Claim 6 (depends on 1)

The glass preform heating furnace of claim 1,
wherein argon gas or nitrogen gas is supplied into the furnace body.