Bushing balance controller and method for using same

• US 4,657,572 A
• Filed: 03/14/1986
• Issued: 04/14/1987
• Est. Priority Date: 03/14/1986
• Status: Expired due to Term

• Current Assignee: Advanced Glassfiber Yarns LLC (KAGY Holding Co., Inc.)
• Original Assignee: Owens-Corning Fiberglas Corporation
• Inventors: Kreikebaum, Gerhard, Desai, Avinash J.
• Primary Examiner(s): LINDSAY JR, ROBERT
• Application Number:
  US06/839,676
• Time in Patent Office: 396 Days
• Field of Search: 65/1, 65/2, 65/29, 65/160, 65/162, 65/DIG. 4, 373/28, 373/40, 219/485, 219/486, 219/509
• US Class Current: 65/384
• CPC Class Codes: C03B 37/07 Controlling or regulating C03B37/0253 takes precedence ; controlling or regulating in general G05
• CPC Class Codes: H05B 3/0023 for heating by passing the current directly across the material to be heated
• CPC Class Codes: Y10S 65/04 Electric heat

Abstract

The bushing balance controller is an electronic device which measures the voltage drop across each segment of a multiple segment glass fiber forming bushing and measures the current flow in the bushing. The device uses these measurements to produce error signals proportional to the difference in the set point temperature and the instantaneous temperature of each segment of the bushing. The device diverts current from each segment of the bushing whose error signal is greater than the average of the error signals for all segments of the bushing. The device also sums all error signals and passes this signal to a bushing controller which adds current to the bushing when the sum of the error signals falls below a preset value.

Claims

1. An apparatus for balancing the temperature in each segment of a multiple segment glass fiber forming bushing comprising:

(a) a means to develop an error signal for each segment of the bushing, each said error signal being proportional to the difference in the temperature of that segment of the bushing and a set point temperature;

(b) a means to sum all said error signals;

(c) a means to develop an average of all said error signals;

(d) a means to divert current from each segment of the bushing whose error signal is greater than said average error signal; and

(e) a means to supply current to the bushing when said sum of the error signals is greater than a preset value.

2. An apparatus for balancing the temperature in each segment of a multiple segment glass fiber forming bushing comprising:

(a) a means to determine a voltage drop across each segment of a glass fiber forming bushing;

(b) a means to determine a current flow in the bushing;

(c) a means for calculating an error signal for each segment of the glass fiber forming bushing based upon the voltage drop across the segment and the current flowing in the segment;

(d) a means to sum the error signal from all segments of the glass fiber forming bushing;

(e) a means to determine an average error signal;

(f) a means to divert current flowing in each segment of the glass fiber forming bushing when the error signal for that segment exceeds the average error signal; and

(g) a means to supply current to the glass fiber forming bushing when the sum of the error signals is below a preset value.

3. An apparatus for maintaining a constant temperature in each segment of a multiple segment glass fiber forming bushing comprising:

(a) a glass fiber forming bushing compartmentalized into "n" individual segments and constructed of a material which has a linear relationship between resistance and temperature characterized by the relationship

space="preserve" listing-type="equation">R.sub.i =R.sub.o [1+α

(T.sub.i -T.sub.o)]

where

i=1 to n

R_i =instantaneous resistance of the i th segment of the bushing

R_o =resistance of the material at the set point temperature T_o

α

=resistivity change per degree Fahrenheit for the material used in the bushing

T_i =instantaneous temperature of the i th segment of the bushing

T_o =set point temperature of the segment of the bushing

(b) a means to supply electrical current I_B to the bushing;

(c) a current transformer to produce a signal proportional to the current I_B flowing in the bushing;

(d) a means to determine a voltage drop E_i across each segment of the bushing;

(e) a means to determine an error signal X_i for each segment of the bushing having the value;

space="preserve" listing-type="equation">X.sub.i =CI.sub.B -KE.sub.i

where C and K are constants, such error signal also equal to

space="preserve" listing-type="equation">X.sub.i =KI.sub.B R.sub.o α

Δ

T.sub.i

where

Δ

T_i =the difference between the instantaneous temperature T_i of the i th segment of the bushing and the set point temperature T_o ;

(f) a means to determine the sum of all error signals

space="preserve" listing-type="equation">Σ

X=X.sub.1 +X.sub.2 +X.sub.3 + . . . +X.sub.n ;

(g) a means to determine an average error signal

space="preserve" listing-type="equation">X=Σ

X/n

(h) a means to divert current from a section of the bushing when the error signal for that section is greater than the average error signal

space="preserve" listing-type="equation">X.sub.i >

X;

(i) a control means to regulate the supply of electrical current I_B to the bushing such that current is supplied only when the sum of all error signals (Σ

X) is greater than a preset value; and

(j) a means to disable measurement of the voltage drops and current when current is being diverted, and a means to disable current diversion when the voltage drops and current are being measured.

4. A method for balancing the temperature in each segment of a multiple segment glass fiber forming bushing comprising the steps of:

(a) measuring a voltage drop across each segment of a multiple segment glass fiber forming bushing;

(b) measuring the current flowing in the bushing;

(c) calculating an error signal for each segment of the bushing based upon the measured voltage drop and current flow, said error signal being proportional to the difference between the temperature of the segment of the bushing and the set point temperature;

(d) calculating the sum of the error signals for all segments of the bushing;

(e) calculating the average error signal by deviating the sum of the error signals by the number of segments in the bushing;

(f) diverting current from each segment of the bushing whose error signal is greater than the average error signal; and

(g) supplying current to the bushing when the sum of the error signals is below a preset value.

5. A method for maintaining a constant temperature in each segment of a multiple segment glass fiber forming bushing comprising the steps of:

(a) measuring a voltage drop across each segment of a multiple segment glass fiber forming bushing;

(b) measuring a current flow in the glass fiber forming bushing;

(c) calculating an error signal for each segment of the glass fiber forming bushing from the voltage drop across that segment of the bushing and the current flowing through the bushing;

(d) electronically modifying said error signal such that said error signal is proportional to the product of the difference between a present temperature and a set point temperature of that segment of the bushing and the current flowing through the bushing;

(e) summing all error signals;

(f) determining an average error signal from the average of the sum of all error signals;

(g) diverting current from each segment of the bushing when the error signal for that segment of the bushing is greater than the average error signal; and

(h) applying power to the bushing when the sum of the error signals is below a preset value.