GB494885A - Improvements in or relating to pressing, bending or veneering wood - Google Patents

Abstract

494,885. Pressing, bending, and veneering wood. PALFI, J. Sept. 22, 1937, No. 25767/36, [Classes 145 (i) and 145 (ii)] Wood, especially in the form of heavy laminated sheets, is pressed, bent, or veneered by enclosing the work 17 and a former 16 into a closable rubber sac 12 which is placed in a pressure-resistant container 11 and evacuated, either prior to or after insertion in the container ; fluid pressure and, if necessary, heat is applied in the container to the sac and its contents, the sac being subsequently withdrawn without releasing the vacuum in it until the work has set, so that a fresh sac may be placed in the container. In the apparatus shown in Fig. 1, a central stiffening board 13 carries on either side base-boards 14, 15 on which are mounted shaped formers 16, 18 over which the work 17 is to be bent. The whole are placed in a rubber sac 12 the end of which is closed by a channel clamp and rod, the sac being then slid into a container 11 on planks 23 mounted on ball-races. The sac is evacuated through a hose 22 either before insertion in the container or subsequently, in which latter case, the evacuation may take place simultaneously with, or subsequently to, the admission to the container of air under pressure from a pipe 28. The container 11 may be fitted with a steam or electrical heater. Fig. 3 shows a modification in which the sac is formed by upper and lower rubber membranes 35 the margins of which are held in grooves in frames 32 by rings 34 ; rubber bands 33 on the meeting faces of the frames forming an air-tight joint between them. Holes and grooves in the boards 13, 14, 15 put all parts of the space in the sac into communication with the pipe 22. In a further modification, the sac consists of a single membrane carried by a frame, the under face of which makes air-tight content with a flat board forming the bottom of the sac.