Ngk Insulators, Inc.

Kazuhiro Miyahara

Keiji Yasuda

Koji Ogura

Toyoshiro Miyajima

Yasuhiro Ito

Kazuo Nakasako

Tetsuo Kamijyo

Toshifumi Sugiura

Masahumi Yamaguchi

Tatsuya Yuino

Masashi Ohtaka

In a method of firing ceramic formed bodies including a binder by using a firing furnace having one or more burners in which a firing output changes alternately between a high output state and a low output state, an air ratio of the burner is maintained at a level of more than 3 in a temperature range from a temperature at which the binder begins to burn out to a temperature at which an ignition loss reaction ends. Further, a firing apparatus has a control means for controlling the burners according to the firing method mentioned above.

Method of firing ceramic formed bodies

A process for controlling combustion of burners arranged in a plurality of respective control zones divided in a furnace, includes the step of repeating a cycle of successively subjecting the burners to combustion for a short time. At least one temperature sensor is fitted in each control zone, a time period during which each burner is subjected to combustion is controlled according to a difference between a temperature detected by the corresponding temperature sensor and a preset temperature in a respective control zone. An apparatus is also disclosed for effecting such a controlling process.

Process for controlling combustion of burners in furnace and an

A method for controlling temperature in a heating kiln is able to maintain the temperature uniformly at a set temperature of the kiln. Output of each burner provided in the kiln is controlled on the basis of temperatures at plural positions affected by plural burners to make the temperature in the kiln substantially equal to a set temperature of the kiln. Mean values of temperatures at the plural positions are calculated and the burners are controlled to bring the mean values into coincidence with the set temperature. Alternatively, contribution rates .alpha.1 and .alpha.2 are determined which correspond to the influence of one burner on the temperature of the thermocouple for the other burner. Handicap temperatures TH1 and TH2 are then calculated by substituting temperatures T1 and T2 of the one and the other burners in equations TH1=T1+(T2-T1) .alpha.1 and TH2=T2+(T1-T2) .alpha.2. The burners are then controlled to make the handicap temperatures coincide with the set temperature.

Temperature control method for heating kiln

A pusher cylinder for a tunnel kiln is used for moving kiln cars loaded with products such as molded ceramic green products to be sintered in the tunnel kiln. A piston rod of the pusher cylinder is made to have a length more than twice a stroke of the pusher cylinder. With such an arrangement, even if foreign substances such as tar are attached to the piston rod extended into the tunnel kiln, the substances do not enter the pusher cylinder in the fully retracted position of the piston rod. As a result, there is no longer any risk of the pusher cylinder itself and a packing for a piston of the cylinder being damaged by such foreign substances. Therefore, the life span of the pusher cylinder and packing until they need to be replaced is remarkably prolonged.

Pusher cylinder for tunnel kiln

A method for firing a ceramic honeycomb structure by a single furnace at a predetermined temperature in a predetermined atmosphere, while controlling combustion of a burner means for heating the ceramic honeycomb structure from the outside thereof. To this end, temperatures at the inside and outside portions of the ceramic honeycomb structure are detected, and the outside temperature thereof is regulated relative to the inside temperature thereof, based on the detected temperatures. The method ensures stable firing to produce a high-quality ceramic honeycomb structure, in which a pore-forming agent is uniformly burnt throughout the inside and outside of the product and the difference in the diameter of fine holes between those inside and those outside thereof is minimized so as to eliminate occurrence of cracks within and at end portions of the ceramic honeycomb structure.

Method of firing ceramic honeycomb structure

Method of manufacturing ceramic honeycomb-structural body

A process for firing ceramic shaped bodies is disclosed, which comprises the step of making a heating temperature in a temperature range up to a decomposing temperature of a shaping aid contained in the ceramic shaped body smaller than that in a temperature range from the decomposing temperature to a firing temperature. A tunnel kiln is also disclosed, which comprises a preheating zone, a firing zone, a waste heat zone, combustion burners provided at the firing zone, an exhaust means provided at an inlet side of the preheating zone for evacuating combustion gases from the combustion burners outside the kiln, and another exhaust means provided at an outlet side of the preheating zone for evacuating the combustion gases outside the kiln.

Process for firing ceramic shaped bodies and a tunnel kiln used therefor

A process for firing ceramic shaped bodies is disclosed, which comprises the steps of placing the ceramic shaped bodies on a truck, and firing the shaped bodies with a combustion gas. Shield members are arranged on the truck such that a jet stream of the combustion gas will not directly contact the ceramic shaped bodies and that a path for the combustion gas jet stream may be formed on the truck. The shield member may be obliquely divided into two sections at the central portion thereof.

Process for firing ceramic shaped bodies and firing tools used therefor

A tunnel furnace height detector used for detecting ceiling heights of a tunnel furnace. The detector includes a plurality of detecting units arranged on a trolley traveling in the tunnel furnace in a manner such that their heights are progressively lowered by predetermined distances. Each of the detecting units includes a support base, and a solid piece pivotally connected to the support base automatically returnable from a pivotally moved position forced by an external force to an original position. The solid piece has one end in contact with a lowered ceiling and the other end closing and opening a measuring circuit system forming a closed circuit.

Tunnel furnace height detector

A tunnel kiln for firing molded ceramic green products includes a gate for feeding a kiln car into and out of the kiln. The gate located at low temperature parts of the kiln includes side walls made of a stainless steel having inclined surfaces and a ceiling made of a stainless steel and having inclined surfaces toward the side walls. The tunnel kiln further includes sand seals at connections between the side walls and the ceiling and receiving bases provided under lower ends of the side walls for receiving pyrolytically decomposed products. The side walls are formed with exhaust ports communicating with the receiving bases so that the pyrolytically decomposed products flow along the inclined surfaces of the ceiling and the side walls are once collected in the receiving bases and exhausted through the exhaust ports of the side walls to the outside of the kiln. With this arrangement, defective ceramic products due to decomposed products attached thereto are completely eliminated.

Tunnel kiln

A process for firing ceramic honeycomb structural bodies at a certain temperature in a given atmosphere is disclosed. The ceramic honeycomb structural bodies are fired, while a gas having a temperature equal to that of an atomsphere surrounding the exterior of the ceramic honeycomb structural bodies is forcedly passed through holes of the ceramic honeycomb structural bodies. By this firing process, a pore-forming agent and/or a shaping aid admixed in the ceramic honeycomb structural bodies can effectively be burnt away and the entire honeycomb structural bodies can uniformly be fired. Thus, fired ceramic honeycomb structural body having desired dimensions can be obtained in a shortened firing time.

Process for firing ceramic honeycomb structural bodies

A trolley transfer unit for a tunnel furnace is to be used between trolleys when ceramic sintered products are loaded onto and unloaded from the trolleys in sintering the products in the tunnel furnace. The trolley transfer unit comprises a bar member for connecting the two trolleys with a predetermined interval, protrusions provided at both ends of the bar member for engaging the trolleys to be connected, and a support bar secured to the bar member and engaging a frame of the other trolley to support the bar member.

Trolley transfer unit for tunnel furnace

A burner unit is used for firing, for example, formed ceramic bodies in a firing furnace. The burner unit includes a burner tile assembly provided in a furnace wall and a burner connected to the burner tile assembly and provided out of the firing furnace. The burner is integrally provided with a connecting burner tile assembly having a tapered step. The burner tile assembly is also provided with a tapered step. The tapered steps of the connecting burner tile assembly and the burner tile assembly are connected through a sealing material to connect the burner to the burner tile assembly. With this arrangement, the burner unit reduces heat dissipation due to a burner construction and enables maintenance to be effected during operation of the burner.

Burner unit for firing furnace

A truck for use in a tunnel kiln is disclosed. The tunnel kiln is used for firing shaped bodies by heating them with use of a plurality of combustion burners provided on sides inside the tunnel kiln. The truck comprises supports. Among them, at least supports with which a combustion stream from the combustion burners directly contacts have a streamlined shape with respect to the combustion stream. By so constructing, turbulence of the combustion stream can be minimized to make temperature distribution more uniform inside the kiln.

Trucks for use in tunnel kilns

A tunnel kiln for firing ceramic shaped bodies including a preheating zone, a firing zone and a cooling zone. Arranged in the preheating zone is a recovery circuit composed of a decomposition product receiving part and a discharge port for discharging the recovered decomposition product.

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Nagoya, Japan

Kazuhiro Miyahara