Patent GB-276469-A (GB)
Title: Method of and apparatus for indicating and if desired controlling the running weight or other characteristics of paper and other material
IPC: G01B5/06
Filed: 1926-06-25
Abstract: 276,469. Jackson, L. Mellersh-, (Atlantic Precision Co.). June 25, 1926. Pulp, regulaiing flow of.-The weight or other characteristic per unit of area of material is determined by relating thereto means which together therewith have electrical characteristics dependent in amount on such weight, and indicating the amount of such characteristics. Apparatus is shown for indicating the running weight of paper during manufacture bv measuring the electrical capacity of a predetermined area of the web. The paper web a passes over a metal plate forming the lower earthed plate of a condenser, the upper plate 10 of which is carried by, but insulated from, a bracket 11 carried by a rock-shaft 12 by means of which it may be raised to permit adjustment of the paper or lowered into operative position. The bracket 11 carries an adjusting-screw 25 which rests on a fixed abutment 30 and by means of which the plate 10 may be adjusted so as to be out of contact with the paper in its lowered position. The lower plate also is arranged to be out of contact with the paper web. A dash-pot enables the plate 10 to be quickly raised by means of the handle 35 and to descend slowly by its own weight on release of the handle. The dash-pot is shown in Fig. 4 and comprises a cylinder 40, pivoted at 41, in which works a piston 42 provided with a small bleeder port 43 and with a large central port 44 normally closed by a spring- pressed valve 45 connected by means of a link 52 to an arm 53 carried by the rock-shaft 12. The condenser formed by the plate 10, the lower plate, and the paper web between them is connected in parallel with coarse and fine adjustment condensers 61, 62, Fig. 3, by means of which a receiving circuit R is tuned to resonance with a screened oscillation-generating circuit S. Change in capacity due to change in weight per unit area of the paper web causes detuning of the circuit R which is indicated by a change in the reading of a thermo-galvanometer or other instrument 65. Resonance mav be restored by adjusting the condensers 61, 62, the amount of such adjustment being a measure of the change of capacity of the condenser 10. In order to correct for changes in capacity due to changes in moisture content of the paper, a supplementary condenser containing dielectric of hygroscopic material is arranged beneath the paper web and connected in the oscillation-generating circuit S. This condenser is described in Specification 276,468, and consists of a lower plate 70, carried by the bars 1, and an upper perforated plate 71. Between the plates 70, 71 is a hygroscopic dielectric material 72 consisting of a ribbon of artificial silk formed from reverted cellulose and having the ends dipped in sealing- wax and the filler threads removed, leaving the warp threads extending between the waxed ends. This element may be treated with a hygroscopic salt such as cobalt chloride. Means for automatically controlling the supply of pulp to the paper-making machine in accordance with the running weight of the web produced is shown in Fig. 8. The shaft 80 of the instrument 65 carries a contact arm 82 playing between two contacts 83 so as to control a motor 85, by means of which the contacts 83 are moved in one direction and the other along a threaded shaft 84, and also a motor 97 which opens or closes the pulpregulating gate 91. The invention is also applicable to the measurement of the running weight of rubber, waterproof fabrics, linoleum, &c. or to the measurement of the variations in the composition of the material. Reference has been directed by the Comptroller to Specification 273,230.