Method and apparatus for detecting and counteracting a deformation of the stock discharge gap in a headbox of a paper machine

A method for detecting and counteracting deformation of a stock discharge gap in the headbox of a paper machine defined between an apron beam member having an underlying supporting frame and a cooperating roof member having an overlying supporting frame comprising:

• (a) ultrasonically measuring the stock discharge gap between the apron beam member and the roof member at at least two locations along the length of the stock discharge gap;
• (b) obtaining the difference between the measurement results for at least two locations along the length of the stock discharge gap;
• and
• (c) adjusting the temperature of at least one of said supporting frames in response to the obtained difference in measurement results so as to reduce the magnitude of any deformation in the stock discharge gap.

An apparatus for detecting and counteracting deformation of a stock discharge gap in the headbox of a paper machine comprising:

• (a) stock delivery means including an apron beam member and a roof member positioned in spaced-apart relation and cooperating to define a stock discharge gap therebetween;
• (b) at least two ultrasonic transducer means mounted in said members at different locations along the length of the stock discharge gap, each being positioned for transmitting ultrasonic pulses to the oppositely positioned member and to thereby measure the stock discharge gap at such location;
• (c) control means connected to each of said transducer means and operable for obtaining the difference between the measurement results for at least two locations along the length of the stock discharge gap;
• and
• (d) temperature adjusting means operatively connected to said control means and responsive to the obtained difference in measurement results for adjusting the temperature of at least one of said apron beam member and roof member so as to reduce the magnitude of any deformation in the stock discharge gap.

An apparatus for detecting and counteracting deformation of a stock discharge gap in the headbox of a paper machine comprising:

• (a) stock delivery means including an apron beam member and a roof member positioned in spaced-apart relation and cooperating to define a stock discharge gap therebetween, the apron beam member having an underlying supporting frame and the roof member having an overlying supporting frame;
• (b) at least two ultrasonic transducer means mounted in said members at different locations along the length of the stock discharge gap, each being positioned for transmitting ultrasonic pulses to the oppositely positioned member and to thereby measure the stock discharge gap at such location;
• (c) control means connected to each of said transducer means and operable for obtaining the difference between the measurement results for at least two locations along the length of the stock discharge gap;
• and
• (d) temperature adjusting means operatively connected to said control means and responsive to the obtained difference in measurement results for adjusting the temperature of at least one of said supporting frames so as to reduce the magnitude of any deformation in the stock discharge gap.