Control of speed and cut in a continuous process line

WALLBOARD and plasterboard as used in the fabrication of modern homes is produced on a continuous process line. It consists of a forming station, several belt sections used for curing and drying, a live roll section used to dry the underside, a punch and knife section used to pierce holes and cut the board to length, an oven curing section, and a trimming and packaging section. In this line an upper and lower layer of paper is used to make an envelope containing a material resembling plaster of Paris. This material starts as a mud, and is cured and dryed in the process. The board is formed and cut to proper length. In order to prevent a loop from forming between belt sections or to prevent the belt sections from tearing the board, the adjacent belt sections should be controlled in speed with respect to each other to within 1 part in 3,000, or to a maximum permissible inaccuracy of 0.03 per cent.