| 摘要 |
The method and apparatus automate the observation of the dry line on the wire of the Fourdrinier paper machine on whose visual observation by eye the conventional control of the paper machine is based. In the invention, the position of the dry line and its such values which deviate from normal, and the quantities which express its form, are reproduced to the operator repeatedly. In order to carry out this, it is formed, as one essential feature of the invention, the image of the plane of the wire with an opto-electric camera and the electric, discrete image information is transmitted into a computer. While the conventional observation of the dry line is based on reflections from the pulp surface which are brighter than the other surface, these, however, disturb an instrumental observation and check an interpretation of the result of observation. These drawbacks are eliminated by the second essential feature of the invention which is the illumination of the wire in the manner presented, so that direct reflections from the pulp surface to the camera do not occur and on the contrary, the pulp surface is observed and found darker than the web surface following it whereby the dry line is observed and interpreted as the borderline between surfaces of an essentially uniform brightness each. The system may be, further on, applied to control, by feedback, the actuating variables which have an effect on the dry line, especially the headbox lip.
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