GB739332A - Split pole parallel dielectric heating bonding process - Google Patents

Abstract

739,332. Dielectric heating. MANN, J. W., and RUSSELL, G. F. Jan. 7, 1954, No. 489/54. Class 39 (3). [Also in Group VIII] In bonding by dielectric heating articles having a wide and vertically arranged adhesive plane disposed between abutting pieces of the dielectric material to be joined, high-frequency lines of force are established flowing parallel with the plane adjacent to upper and lower edges thereof so as to set quickly portions of the adhesive to provide continuous barriers of set adhesive bordering the entire length of the upper and lower edges thereby trapping unset adhesive lying therebetween, and permitting the unset adhesive to set cold while still held between the barriers. Alternatively, the lower edge only is thus bonded, the remaining adhesive being permitted to set cold. In Fig. 7, blocks of wood 3 with vertical glue lines C3 between them are heated by circular rod electrodes A2, B2 placed in pairs opposite one another against the lower and upper surfaces at right angles to the gluelines and connected in pairs to a coil 6 of a R.F. generator as shown, so that the electric field is set up between adjacent electrodes of opposite polarity along the upper and lower edges of the blocks and only a weak field is set up between the upper and the lower edges of the wood. The wooden blocks may be moved through the field either horizontally and perpendicularly to the length of the electrodes, or in the direction of the length of the electrodes; and in the latter case, fresh blocks with adhesive may be added at intervals. The spacing of one pair of electrodes from an adjacent pair B2 should be normally not less than the vertical width of the adhesive plane C3 ; and where the glue line is 1 inch high the spacing of the electrodes may be 3-4 inches, but where the glue line is <SP>1</SP>/ 10 high, the spacing may be 30 inches. The electrodes may be flat plates, bars or non-circular rods. With more widely spaced electrodes, the field penetrates the wood deeper. A glue plane may be 1 inch wide and up to 50 feet long. Squeezing out of the adhesive at the edges of the articles is thus minimized, and any adhesive squeezed out is set solid during the heating so that finished panels, e.g. for furniture, may be piled directly one on another. Specification 647,045 is referred to.