Abstract: An electrically heated kiln having a ventilation system in accordance with the present invention includes a hinged upper wall, a lower wall, and side walls forming a firing chamber. The kiln further includes an upper ventilation aperture formed in the upper wall and a lower ventilation aperture formed in the lower wall. A duct connects the lower aperture with the outside environment. An exhaust fan, coupled to the duct, draws incoming air into the kiln through the upper aperture, downwardly through the kiln, and outwardly through the lower aperture into the duct to be expelled outside. The downward movement of the air and kiln gases causes turbulence near the upper portion of the kiln to create a more uniform temperature within the kiln. The apertures are sized and the draw rate is selected so as to provide proper ventilation of the kiln. The draw rate is preferably between 8% and 45% of the kiln volume per minute when measured at room temperature through the lower aperture.

Abstract: An electrically heated kiln having a ventilation system in accordance with the present invention includes a hinged upper wall, a lower wall, and side walls forming a firing chamber. The kiln further includes an upper ventilation aperture formed in the upper wall and a lower ventilation aperture formed in the lower wall. A duct connects the lower aperture with the outside environment. An exhaust fan, coupled to the duct, draws incoming air into the kiln through the upper aperture, downwardly through the kiln, and outwardly through the lower aperture into the duct to be expelled outside. The downward movement of the air and kiln gases causes turbulence near the upper portion of the kiln to create a more uniform temperature within the kiln. The apertures are sized and the draw rate is selected so as to provide proper ventilation of the kiln. The draw rate is preferably between 8% and 45% of the kiln volume per minute when measured at room temperature through the lower aperture.

Abstract: A microcomputer control system for a furnace is disclosed which provides accurate control of the temperature of the furnace such that the temperature can be quickly increased to a predetermined desired temperature without overshooting the desired temperature. The control system determines the tuning constants of the furnace as a function of the system's response to a predetermined input and, thereafter, uses the determined tuning constants to accurately control the temperature of the furnace. The control system employs a novel method for increasing the temperature of a furnace wherein full power is applied to the furnace heat source until the microcomputer makes the determination, based upon the furnace tuning constants, that power supplied to the furnace must be reduced to prevent the temperature of the furnace from overshooting the desired temperature.

Abstract: An efficient method for using a periodic kiln to heat ceramic material to a state of maturation, and the apparatus for carrying out the method, duplicate the action of pyrometric cones. In a microcomputer, data is stored describing the relationship between rates of temperature increase and deformation temperatures for several numbered pyrometric cones. The kiln operator selects the cone number for use in the firing operation and then activates both the apparatus and the kiln's heating elements. Using a thermocouple, the microcomputer periodically measures kiln temperature and calculates the average rate of temperature increase inside the kiln (the rate need not be controlled). The rate is then used, in conjunction with the stored data, to determine the temperature at which the ceramic material will have matured. If the present temperature in the kiln is greater than or equal to this maturation temperature, the microcomputer sounds an alarm or shuts off the heating elements.