JP2010216756A - Method of burning test of ceramics molding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of burning ceramic moldings capable of obtaining a large number of the ceramic moldings having heat curves which are displaced form each other in a short time. <P>SOLUTION: The method of a burning test of the ceramic moldings is executed by disposing a tunnel furnace 1 keeping prescribed temperatures at each of places along moving directions 4 of a plurality of the ceramic moldings 11 from an inlet 2 toward an outlet 3, moving the plurality of ceramic moldings 11 from the inlet 2 to the outlet 3 in a state of being arranged along the moving direction 4 to the inside of the tunnel furnace 1, and further moving the ceramic moldings 11 in a state that speed can be changed while uniformly keeping distances between the ceramic moldings 11 longitudinally arranged in the moving direction 4. The method has a process for burning the ceramic moldings 11 in a state that heat curves as historical temperatures of the ceramic moldings 11 are displaced from each other with respect to each of the ceramic moldings 11. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for a firing test of a ceramic molded body, which is used for searching for an ideal heat curve for passing through a ceramic molded body in a firing step of manufacturing a ceramic product.

  Ceramics have unique properties not found in metals and plastics. For example, ceramics are provided with excellent formability that can be formed into any shape and porosity with countless fine pores in a network, so that the honeycomb is composed of micron-order thin partition walls. As a structure, it is used for an exhaust gas purification catalyst carrier, an exhaust gas filter, and the like.

  In order to manufacture ceramic products, ceramic raw materials and organic binders are kneaded to prepare a clay, and a ceramic molded body having a desired shape is made from this clay by extrusion molding or injection molding. A series of steps in which the body is fired at a high temperature passes. Among these steps, the step in which the present specification focuses, the step of firing the ceramic molded body, the so-called firing step, uses a kiln having a high temperature inside the furnace. The kiln is introduced in detail in Non-Patent Document 1, for example.

  In the firing step, it is desirable to cause an ideal heat curve (temperature curve) to pass through the ceramic molded body in order to cope with the characteristics of ceramics that react, sinter, and expand / contract due to temperature changes. The heat curve affects the firing of ceramic compacts such as maximum temperature / minimum temperature, temperature fluctuation such as temperature increase / decrease, temperature increase / decrease rate, and length of time to maintain it at a specific temperature. There are a number of factors that affect

  The ideal heat curve differs depending on the shape of the ceramic molded body and the composition of the kneaded material used as the material. Therefore, the shape of the ceramic molded body and the composition of the clay used as a material influence the success or failure of firing of the ceramic molded body.

  The batch-type single kiln has the advantage of being able to adapt to heat curves that have subtle temperature changes because the temperature inside the kiln can be changed freely, but only the number of ceramic compacts that can be accommodated in a single kiln. Since it cannot be fired at once, it is not suitable for mass production.

  The continuous tunnel furnace is suitably used at the manufacturing site of ceramic products because the ceramic molded body can be continuously fired by moving a carriage on which the ceramic molded body is placed in the tunnel furnace. In the firing process using the tunnel furnace, the temperature setting in each place in the tunnel furnace is such that a series of heat curves (temperature curves) can be passed when the ceramic molded body completes the movement from the inlet to the outlet.

  When setting the temperature in the tunnel furnace, many factors are taken into consideration, such as opening / closing of the entrance / exit of the tunnel furnace, arrangement of a combustion burner for heating, and an exhaust method. Patent Document 1 discloses a tunnel furnace including a combustion burner and combustion gas exhaust means in a predetermined form so that a ceramic molded body moving in the tunnel furnace passes a desired heat curve. Patent Document 2 discloses a tunnel furnace in which the interior of the furnace is divided into small rooms by a partition plate, and the temperature changes in each small room are linked.

  In an actual manufacturing site, all of the ignition and control of the combustion burner, the air flow control, and the movement control of the carriage in the tunnel furnace must be performed within a short period of time during which the production line is stopped. As a technique that meets this demand, Patent Document 3 discloses an automatic temperature raising method for a tunnel furnace that automatically raises the temperature in the tunnel furnace.

JP-A-1-249665 JP-A-1-225890 JP 7-294149 A

"Ceramics furnace" Co-authored by Katsumi Nagasaka and others, Kyoritsu Publishing Co., Ltd.

  Regarding firing of ceramic molded bodies using a tunnel furnace, those relating to tunnel furnace structure and temperature setting methods as shown in Patent Documents 1 to 3, or carts on which ceramic molded bodies are placed, firing temperature determination methods, etc. Many techniques have been disclosed. However, there is no disclosure regarding a method for efficiently searching for an ideal heat curve to be passed through the honeycomb formed body in order to manufacture a high-quality product.

  In batch-type single furnaces, in order to search for one ideal heat curve, nearly infinite heat curve candidates must be verified one by one, and several tens of hours are spent on one firing In view of this, it is not possible to meet today's production situation that requires the product to respond to a short life cycle.

  On the other hand, as described in Patent Document 3, in a tunnel furnace, it is necessary to rely on the experience and intuition of skilled workers just to set the temperature in the tunnel furnace for a known heat curve. There is. Therefore, it is desired to develop a method for searching for an ideal heat curve using the temperature setting of the tunnel furnace in operation as it is. In addition, the number of tunnel furnaces in one facility is limited, and a tunnel furnace dedicated to heat curve search cannot be provided, so it is desirable to search for an ideal heat curve in a short period such as a production line outage period. ing.

  For example, when firing a honeycomb-shaped ceramic molded body composed of partition walls of micron order thickness, the allowable range such as the rate of temperature rise and the time for maintaining at a predetermined temperature is narrow, and the ideal heat curve is Built on a delicate balance of conditions. Therefore, in firing this honeycomb-shaped ceramic molded body, the occurrence rate of defective products often increases when the heat curve slightly shifts.

  In such a case, when the temperature setting of the tunnel furnace cannot be changed, it may be dealt with by adding an additive to the clay as a material or changing the shape of the ceramic molded body. However, such a measure means that a product that is originally desired cannot be manufactured, and thus a method for accurately finding an ideal heat curve has been demanded.

  In view of the above problems, an object of the present invention is to provide a method for firing a ceramic molded body in which a large number of ceramic molded bodies that have passed heat curves that are shifted from each other can be obtained in a short time.

  In order to solve the above-mentioned problems, the present inventors have intensively studied a method for firing a ceramic molded body using a tunnel furnace, and as a result, completed the present invention. That is, according to the present invention, a method for firing test of a ceramic molded body shown below is provided.

[1] A tunnel furnace in which a predetermined temperature is maintained at each position along the moving direction of the plurality of ceramic molded bodies from the inlet toward the outlet is provided, and the plurality of ceramic molded bodies are disposed inside the tunnel furnace. The ceramic molded body is moved along the moving direction from the inlet to the outlet, and the ceramic molded body moves at the same time while maintaining the same distance from the other ceramic molded bodies arranged before and after the moving direction. The ceramic molded body is fired by a step of firing the ceramic molded body so that a heat curve that is a history of the elapsed temperature of the ceramic molded body is shifted from each other for each ceramic molded body. Test method.

[2] The ceramic molded body firing test method according to [1], wherein the movement of the ceramic molded body is performed by using a conveying unit that places and moves the ceramic molded body.

[3] The movement of the ceramic molded body is performed by placing a plurality of types of ceramic molded bodies on one of the transporting means, whereby the heat curve of the plurality of types of ceramic molded bodies is changed. The method for firing a ceramic molded article according to [2], wherein the distribution is obtained simultaneously.

  According to the method for firing test of a ceramic molded body of the present invention, a large number of ceramic molded bodies that have passed heat curves that are shifted from each other can be obtained in a short time.

FIG. 2 is a schematic diagram (upper stage) of the tunnel furnace and a graph (lower stage) showing an example of temperature settings determined at each position in the tunnel furnace. It is the figure which represented typically the trolley | bogie which is one Embodiment of the conveyance means which moves the inside of a tunnel furnace, and a mode that the honeycomb molded object is mounted in this. The temperature distribution in the region A where the temperature is constant is represented by a line graph, and the position and the surface temperature of the ceramic molded body moving in the region A are plotted on the line graph. In the region A shown in FIG. 3, after the ceramic compact has moved at a constant low speed to the position plotted in FIG. It is a figure showing a curve. The temperature distribution in the region B in the tunnel furnace where the temperature rises intermittently is represented by a line graph, and the position and surface temperature of the ceramic molded body moving in the region B are plotted on the line graph. . In the region B shown in FIG. 5, after the ceramic compacts have moved to a position plotted in FIG. 5 at a constant speed, the ceramic compacts are temporarily stopped and moved again at the same speed all at once. It is a figure showing the done heat curve. In the region B shown in FIG. 5, when the ceramic molded body moves at a constant speed to the position plotted in FIG. 5, simultaneously moves at a constant high speed, and again simultaneously moves at a constant low speed. It is a figure showing the heat curve which each ceramic molded object passed. The temperature distribution in the region C in the tunnel furnace where the temperature continuously rises is represented by a line graph, and the position and surface temperature of the ceramic molded body moving in the region C are plotted on the line graph. . In region C shown in FIG. 8, the heat that has passed through each ceramic compact when the ceramic compact has moved to a position plotted in FIG. 8 at a constant speed, and then temporarily stopped and moved again at the same speed. It is a figure showing a curve. In the region C shown in FIG. 8, when the ceramic molded body moves at a constant speed to the position plotted in FIG. 8, simultaneously moves at a constant high speed, and again moves at a constant low speed at the same time. It is a figure showing the heat curve which each ceramic molded object passed. It is a line graph showing the temperature distribution of the tunnel furnace used for the Example. In an Example, it is a figure showing the heat curve which the honeycomb molded object mounted in the No. 1-9 trolley | bogie passed. It is a figure showing the heat curve which the part of the frame A in FIG. 12 expanded and the honeycomb molded object mounted in the No. 1-9 trolley | bogie passed.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to the following embodiments, and changes, modifications, and improvements can be added without departing from the scope of the present invention.

1. Basic embodiment of method for firing test of honeycomb formed body of the present invention:
The method for firing test of the ceramic molded body of the present invention (hereinafter referred to as “method of firing test of the present invention”) includes a step of continuously moving and firing a plurality of ceramic molded bodies in a tunnel furnace. The heat curves in which the respective ceramic molded bodies elapse are fired so that they deviate from each other.

  The “heat curve” here means a history of the temperature at which the ceramic compact has passed during movement in the tunnel furnace, and is also called a temperature curve or a temperature history. Further, the “heat curve distribution” refers to a collection of heat curves for each honeycomb formed body when a plurality of one type of honeycomb formed body is fired.

1-1. Tunnel furnace:
An example of the tunnel furnace 1 is schematically shown in the upper part of FIG. The tunnel furnace 1 has an inlet 2 and an outlet 3, and the ceramic compact 11 moves from the inlet 2 to the outlet 3 in the tunnel furnace 1.

  In the lower part of FIG. 1, an example of the temperature distribution in the tunnel furnace 1 is shown in a graph. In the tunnel furnace 1, a predetermined temperature is maintained at each position along the moving direction 4 from the inlet 2 to the outlet 3.

  In the firing test method of the present invention, the maximum value and the minimum value of the temperature in the tunnel furnace 1 correspond to the maximum temperature and the minimum temperature of the heat curve in which the ceramic molded body 11 passes. Further, the undulation of the temperature along the direction from the inlet 2 to the outlet 3 in the tunnel furnace 1 corresponds to the undulation of the temperature along the time axis of the heat curve in which the ceramic molded body 11 passes. When the temperature distribution in the tunnel furnace 1 is as shown in the lower part of FIG. 1, a heat curve that undulates in the order of low temperature-high temperature-low temperature is obtained. Alternatively, when it is desired to obtain a heat curve in which the temperature rises and falls in the order of low temperature-high temperature-low temperature-high temperature-low temperature, the temperature distribution in the tunnel furnace 1 is low temperature-high temperature- Low temperature-high temperature-low temperature. The maximum and minimum temperatures in the tunnel furnace 1 and the undulations of the high and low temperatures are the undulations of the maximum and minimum temperatures of the heat curve and the undulations of the temperature, which is ideal for the ceramic molded body that is the subject of the firing test. It is preferable to make it correspond.

  About the tunnel furnace 1, there is no limitation in the specific form about a structure and a function, such as shapes, such as length and width, and the installation of heating and cooling. That is, the tunnel furnace 1 may have any form as long as it belongs to the category of the tunnel furnace in which the honeycomb formed body 11 is moved and the honeycomb formed body 11 is continuously fired.

1-2. Ceramic compact:
In the firing test method of the present invention, the shape, material, and the like of the ceramic molded body 11 are not particularly limited, and any object can be used. For example, in the firing test method of the present invention, since many ceramic molded bodies 11 that have passed through heat curves slightly shifted from each other as described below are obtained, cracks and deformation are likely to occur during firing. It is excellent in the firing test of the honeycomb-shaped ceramic molded body 11 composed of thin partition walls.

1-3. Movement of ceramic compact:
As shown in the upper part of FIG. 1, in the firing test method of the present invention, by moving a plurality of ceramic molded bodies 11 in the tunnel furnace 1 along the moving direction 4 from the inlet 2 to the outlet 3, The ceramic molded body 11 is fired. The apparatus for moving the ceramic molded body 11 is not particularly limited. FIG. 2 schematically shows a state in which the carriage 22 on which the ceramic molded body 11 is placed moves along the moving direction 4 as an example of the form in which the ceramic molded body 11 is moved. As shown in FIG. 2, when the carts 22 adjacent to each other in the front-rear direction are connected to each other, the distance between the ceramic molded bodies 11 placed thereon is kept constant.

  The ceramic molded body 11 is moved by changing the speed at the same time while maintaining the same distance from other ceramic molded bodies 11 arranged before and after the moving direction 4. In other words, all the ceramic molded bodies 11 move at the same speed at the same time, and the change of the moving speed is made simultaneously for all the ceramic molded bodies 11. For example, the plurality of ceramic molded bodies 11 are initially moved at 5 m / hr, and the speed is changed so as to move at a speed of 10 m / hr from a certain point in time. Depending on the manner of movement of the ceramic molded body 11, the heat curves that each ceramic molded body 11 passes are shifted from each other.

  The movement of the ceramic molded body 11 includes, for example, continuous movement and intermittent movement described below.

1-3-1. Continuous movement:
The continuous movement is a movement mode in which the position of the ceramic molded body 11 continues to change except when stopped, as literally. In the case of continuous movement, the moving speed of the ceramic molded body 11 may be the distance that the honeycomb molded body 11 moves per unit time.

1-3-2. Intermittent movement:
The intermittent movement is a movement mode in which the position of the ceramic molded body 11 changes only during movement that is determined with a predetermined time interval. In the firing step of the ceramic molded body 11 using the tunnel furnace 1, the ceramic molded body 11 is placed in a mortar, the mortar is connected from the inlet 2 to the outlet 3 in the tunnel furnace 1, and a new mortar is added for a predetermined time. There is a case where a method of sequentially pushing into the tunnel furnace 1 at intervals is used. In such a method, the ceramic molded body 11 performs an intermittent movement that advances by the length of the mortar along the movement direction 4 at predetermined time intervals.

  During intermittent movement, the speed at which the ceramic molded body 11 moves is determined by dividing the movement distance in one movement performed at time intervals by the time interval from the previous movement to the current movement. Can be defined as being calculated. For example, the second movement following the first movement of the ceramic molded body 11 is performed 30 minutes after the first movement, and when the movement distance of the second movement is 3 m, The moving speed of the ceramic molded body 11 is 6 m / hr (0.1 m / min).

  For example, in the movement of the honeycomb molded body 11, the first to third movements are performed at a 3 m pace at 30 minute intervals, and the fourth to sixth movements are performed at a 3 m pace at 60 minute intervals. The speed in the first to third movements is 6 m / hr, and the speed in the fourth to sixth movements is 3 m / hr. In this case, it can be defined that the change in the moving speed of the honeycomb formed body 11 occurs immediately after the third movement, and at the time when the counting of the time interval before the next fourth movement starts. Next, the shift of the heat curve will be described in detail.

1-4. Forming heat curve distributions that are offset from each other:
The shift of the heat curve in which the ceramic molded body 11 passes will be described for each mode of temperature change along the moving direction 4 in the tunnel furnace 1. Here, the heat curve shown in the lower part of FIG. 1 in which the ceramic molded body 11 passes due to movement in the regions A, B, and C, which are partial regions in the tunnel furnace 1, will be described.

1-4-1. Temperature constant range:
In FIG. 3, the temperature distribution in the region A in the tunnel furnace 1 shown in the lower part of FIG. 1 is represented as a line graph. In region A, the temperature is constant. Further, in FIG. 3, the positions and surface temperatures of the ceramic molded bodies 11a to 11c at a certain time are plotted on a line graph.

1-4-1-1. Low speed to high speed change:
In FIG. 4, in the region A, when the ceramic molded bodies 11a to 11c move at the same low speed to the position plotted in FIG. 3, and simultaneously move at the same high speed, the ceramic molded bodies 11a to 11c. Represents the heat curve that has passed. The time required for the movement of the region A becomes shorter in proportion to the distance moved at high speed, that is, the length of the distance from the position plotted in FIG. 3 to the end point of the region A. Therefore, the heat curve when passing through the region A becomes shorter in the order of those far from the end point of the region A at the time shown in FIG. 3, that is, in the order of the ceramic molded bodies 11a, 11b, and 11c. Deviation from each other.

1-4-1-2. Changing the speed between low speed-high speed-low speed:
Although not shown, the ceramic molded bodies 11a to 11c move at the same low speed to the positions plotted in FIG. 3 and then change the speed so that they move at the same high speed, and are closest to the outlet 3. When the speed is simultaneously changed so that the ceramic molded body 11a moves at the previous low speed before reaching the end point of the area A, the moving time at the high speed and the moving time at the low speed in the area A are respectively The same for all ˜11c. At this time, the heat curves in which the ceramic molded bodies 11a to 11c all pass in the region A are the same.

1-4-2. Areas where temperature rises and falls intermittently:
FIG. 5 is a line graph showing the temperature distribution in the region B in the tunnel furnace 1 shown in the lower part of FIG. In region B, the temperature rises intermittently. On the line graph, the positions and surface temperatures of the ceramic molded bodies 11a to 11c moving in the region B are plotted. Here, the region B where the temperature rises intermittently will be described as an example, but the same idea can be understood in the region where the temperature falls intermittently.

1-4-2-1. Changing the speed at which to pause:
In FIG. 6, in the region B, the ceramic molded bodies 11a to 11c move at a constant speed to the positions plotted in FIG. 5, temporarily stop, and then move all at once at the same constant speed. In the case, it represents a heat curve in which the ceramic molded bodies 11a to 11c have passed. When the ceramic compacts 11a to 11c are in such a moving mode that temporarily stops at the same time, the time required to pass through the region B is the same for all the ceramic compacts 11a to 11c. Further, the heat curve is deviated between the ceramic molded body 11a at the high temperature position plotted in FIG. 5 and the honeycomb molded bodies 11b and 11c at the low temperature position at the same time.

  As in the case of the honeycomb molded bodies 11b and 11c shown in FIG. 6, some of the ceramic molded bodies 11 arranged in the moving direction 4 that pass through the same heat curve may be partially obtained. Thus, even when a part of the same heat curve is obtained, it belongs to the technical scope of the firing test method of the present invention.

1-4-2-2. Changing the speed between low speed-high speed-low speed:
In FIG. 7, in the region B, the ceramic compacts 11a to 11c move at the same low speed to the positions plotted in FIG. 5 and then simultaneously change the speed so as to move at the same high speed, and When the speed is changed at the same time so that the ceramic molded body 11a closest to the outlet 3 moves at the previous low speed before reaching the end point of the region B, it represents a heat curve in which the ceramic molded bodies 11a to 11c have passed. In this case, the heat curve differs depending on whether the ceramic molded body 11 is moved at a high speed at a low temperature or a high temperature, or over both low and high temperatures. In the case shown in FIG. 7, the movement at high speed is limited to a place where the ceramic molded body 11a is at a high temperature, the ceramic formed body 11b extends to both a low temperature place and a high temperature place, and the ceramic 11c is limited to a low temperature place. ing. Therefore, the heat curves through which the ceramic molded bodies 11a to 11c pass are shifted from each other.

  Although not specifically illustrated as a modified form from the case of FIG. 7, for example, when the ceramic molded body 11a reaches the end point of the region B before the speed is changed from high speed to low speed again, the ceramic molded body 11a is Compared with the ceramic molded bodies 11b and 11c, the distance traveled at a low speed is increased by the amount the distance traveled at a high speed is shortened, so that the elapsed time of the heat curve is lengthened.

1-4-3. Area where temperature rises and falls continuously:
In FIG. 8, the temperature distribution in the region C in the tunnel furnace 1 shown in the lower part of FIG. 1 is represented by a line graph. In region C, the temperature rises continuously. On the line graph, the positions and surface temperatures of the ceramic molded bodies 11a to 11c moving in the region C are plotted. Here, the region C where the temperature is continuously increased will be described as an example, but the same idea can be understood in the region where the temperature is continuously decreased.

1-4-3-1. Changing the speed at which to pause:
In FIG. 9, the ceramic compacts 11a to 11c move at a constant speed to the positions plotted in FIG. 8 and then temporarily stop and again the same speed as in the speed change mode shown in FIG. Represents a heat curve in which the ceramic molded bodies 11a to 11c have passed. It can be understood that the heat curve shown in FIG. 9 is basically considered as an inclination of the heat curve shown in FIG.

  However, in the region B shown in FIG. 5, since the temperature is constant at the portions before and after the position X where the temperature is switched from the low temperature to the high temperature, the same heat curve as in the honeycomb formed bodies 11 b and 11 c shown in FIG. 6. Can elapse. On the other hand, in the region C shown in FIG. 8, since the temperature continuously increases along the moving direction 4, the ceramics arranged in front from the time when the ceramic molded bodies 11a to 11c are simultaneously changed in speed at different positions. It inevitably deviates from the heat curve in which the molded body 11 has passed. Therefore, at the time of temporary stop at the position plotted in FIG. 8, the heat curves of all the ceramic molded bodies 11a to 11c are shifted from each other as shown in FIG.

1-4-3-2. Changing the speed between low speed-high speed-low speed:
In FIG. 10, in the region C, the ceramic compacts 11a to 11c are moved at the same low speed to the positions plotted in FIG. When the speed is changed at the same time so as to move at the previous low speed, it represents a heat curve in which the ceramic molded bodies 11a to 11c have passed. The heat curve shown in FIG. 10 can be basically understood as an inclination of the heat curve shown in FIG. In the region C, since the temperature continuously increases along the moving direction 4, the ceramic molded bodies 11 arranged in front from the time when the ceramic molded bodies 11 a to 11 c are simultaneously changed in speed at different positions. The inevitably deviates from the heat curve. Therefore, as shown in FIG. 10, the heat curves of all the ceramic molded bodies 11a to 11c are shifted from each other.

  The mode of changing the moving speed of the ceramic molded body 11 described so far is only a part of a specific example, and various speed changing modes are adopted depending on the situation in the actual firing test. it can.

  As can be understood from the above, according to the firing test method of the present invention, a large number of ceramic molded bodies 11 that have passed through mutually shifted heat curves can be obtained simultaneously. Therefore, in the firing test method of the present invention, an ideal heat curve for obtaining a high-quality product can be efficiently searched within a limited short period such as a production line rest period.

  Further, when a slight shift in the heat curve has a significant effect on the success or failure of firing of the ceramic molded body 11, the distance between the ceramic molded bodies 11 along the moving direction 4 is shortened to move the ceramic molded body 11. And preferred. As a result, the width of the deviation of the heat curve in which the ceramic molded bodies 11 are lined up and down is reduced.

2. Embodiments in which the ceramic molded body is moved by a transportation means:
In the firing test method of the present invention, a conveying means 21 for placing and moving the ceramic molded body 11 can be used. In FIG. 2, as one embodiment of the conveying means 21, a cart 22 on which the ceramic molded body 11 can be placed and moved is shown.

  Further, in the embodiment in which the ceramic molded body 11 is moved by the transporting means 22, it is preferable to place and move a plurality of types of ceramic molded bodies 11 on one transporting means 21. Thereby, the heat curve distribution about several types of ceramic molded object 11 can be obtained simultaneously. For example, in the case of the heat curve distribution shown in FIG. 10, depending on the shape and material of the ceramic molded body 11, there is an ideal heat curve through which the ceramic molded body 11 a passes, or a heat curve through which the ceramic molded body 11 b passes. This is because there may be an ideal.

3. Form of method of firing test of ceramic molded body:
3-1. Ceramic compact:
(Examples 1-3)
A ceramic material composed of talc, alumina, kaolin, and silica, water, and an organic pore former compounded so as to be converted into cordierite by firing is kneaded into a clay, and this clay is made into a metal mold. A honeycomb-shaped ceramic molded body 11 (hereinafter referred to as “honeycomb molded body 11”) having a plurality of cells penetrating in the longitudinal direction and having a cylindrical appearance was produced. In the honeycomb molded bodies 11 of Examples 1 to 3, the thickness of the partition walls, the porosity, the number of cells per inch square in a direction perpendicular to the cell penetration direction, the outer diameter, and the total length are shown in Tables 1 to 3. Further, either one of both ends of the cell penetrating the honeycomb formed body 11 was plugged with a slurry mainly composed of ceramics. In the plugging, when the honeycomb formed body is viewed from one end face, the plugged cell ends and the unplugged cell ends are alternately arranged. In addition, the clay used in Example 3 was obtained by further adding flammable coke that burns at a temperature of less than 500 ° C. to the clay used in Examples 1 and 2.

3-2. Tunnel furnace:
The tunnel furnace 1 used had a length from the inlet 2 to the outlet 3, that is, a furnace length of 150 m. The temperature distribution in the tunnel furnace 1 was measured by moving a carriage 22 equipped with a temperature measuring device at a constant speed of 1 m / hr. FIG. 11 shows the temperature distribution in the tunnel furnace 1.

3-3. Dolly:
As the transport means 21, a carriage 22 having a length of 1.25 m in the moving direction 4 was used (see FIG. 2).

3-4. Dolly movement:
The movement of the honeycomb formed body 11 in the tunnel furnace 1 was performed by placing it on the carriage 22 described above. Nine trucks 22 are arranged along the moving direction 4, and the trucks 22 adjacent to each other in the front and rear are connected to move inside the tunnel furnace 1. The first car 22 and the ninth car 22 are named sequentially from the car 22 at the forefront of the moving direction 4 toward the rear side. The honeycomb molded bodies 11 (Samples 1 to 27) of Examples 1 to 3 were placed on each of the No. 1 to No. 9 carriages 22. Since the trolleys 22 adjacent to each other are connected to each other, the moving speed of the honeycomb formed body 11 placed on the first trolley 22 to the ninth trolley 22 was changed at the same time. In addition, in order to clarify the comparison, Samples 1 to 27 were placed in the same place on each carriage. For example, the sample 1 is placed at the forefront of each of the No. 1 to No. 9 carts, so that the distance between the honeycomb molded bodies 11 of the sample 1 placed on the No. 1 cart 22 and the No. 2 cart 22 is It was kept at 1.25m.

3-5. Changing the moving speed of the ceramic compact:
The movement of the 1st to 9th carriages 22 adopts the above-mentioned intermittent movement pattern. Briefly, the movement of the No. 1-9 bogie 22 was carried out by Steps 1-17, which were advanced 1.25 m at predetermined time intervals. Table 4 shows details of steps 1 to 19.

  The terms in Table 4 will be described. The moving time starts when the first truck 22 enters the tunnel furnace 1 from the entrance 2. The time interval is the time (expressed in minutes (min) or hours (hr)) from 1.25 m forward to 1.25 m forward. The moving speed (m / hr) is calculated by dividing the moving distance 1.25 m in one movement by the time interval (hr). The cumulative number of movements is obtained by integrating the number of times of moving forward 1.25 m at a predetermined time interval after the first carriage 22 enters the tunnel furnace 1 from the entrance 2. The number of times of movement for each process is the number of times of advancement every 1.25 m in each of processes 1 to 19. In the column of “Position of the first car” in Table 4, the distance from the first car 22 to the entrance 2 at the start and end of each of the steps 1 to 19 is described.

  In step 1, the movement of the No. 1 to No. 9 bogies 22 started from the No. 1 bogie 22 from the entrance 2 into the tunnel furnace 1 at intervals of 75 minutes (1.25 hours). First, at time 0, the first movement 22 was advanced 1.25 m from the entrance 2 into the tunnel furnace 1 as the first cumulative movement. Subsequently, when the movement time is 1.25 hours, the forefront of the No. 2 carriage 22 is the tunnel furnace while the No. 2 carriage 22 is pushed into the tunnel furnace 1 as the second cumulative movement. It was placed at a position 1.25 m from 1 entrance 2. When the No. 3 bogie 22 and after entered the tunnel furnace 1, the same operation was performed while pushing the bogie 22 already in the tunnel furnace 1. When the moving time was 10 hours, the last No. 9 bogie 22 was put into the tunnel furnace 1 from the entrance 2 at the 8th cumulative number of times of movement.

  Furthermore, in the process 1, the movement advanced 1.25 m every 75 minutes (1.25 hours) up to the 25th cumulative number of movements. In addition, the No. 1-9 bogie 22 was connected and moved simultaneously. At the time of the 25th cumulative transfer, which is the last movement in Step 1, the movement time was 31.25 hours.

  In Step 2, the movement was performed only once at a time interval of 70 minutes (1.17 hours). Specifically, the movement time was 31.25 hours to 70 minutes (1.17 hours), and when the movement time was 32.42 hours, the 26th movement was performed. Thereafter, the No. 1 to No. 9 carriages 22 were moved according to the schedule shown in Table 4 in the same manner as in Steps 3 to 19.

  At the 120th cumulative number of movements in Step 19, the first truck 22 first exited the tunnel furnace 1 from the outlet 3, and the firing of the honeycomb formed body 11 placed thereon was completed. Furthermore, at the interval of 75 minutes (1.25 hours), from the 121st cumulative number of movements, the vehicle exited from the exit 3 to the tunnel furnace 1 in order from the No. 2 carriage 22. When the cumulative number of movements was 128, the last No. 9 bogie 22 went out of the tunnel furnace 1 from the exit 3.

  The honeycomb formed body 11 placed on the No. 1-9 bogie 22 was fired while moving in the tunnel furnace 1 from the inlet 2 toward the outlet 3 as described above. The honeycomb formed body 11 that has undergone this firing step is referred to as a honeycomb fired body.

  As can be understood from Table 4, the moving speed of the No. 1 to 9 carts 22 is changed when moving from one process to the next, as when moving from process 1 to process 2.

4). Results and evaluation:
4-1. Heat curve:
FIG. 12 shows a heat curve in which the honeycomb formed body 11 placed on each of the No. 1 to 9 bogies 22 has passed. When moving from step 1 to step 2 when the first moving speed is changed, and when moving from step 18 to step 19 when the last moving speed is changed, all of No. 1 to 9 bogies 22 are all used. Was in the tunnel furnace 1. The time interval between the first step 1 and the last step 19 is the same 70 minutes (1.25 hours). From these things, all the stay times in the No. 1-9 bogie 22 in the tunnel furnace 1 are the same. From FIG. 12, it can be seen that the time required for the heat curve in which the honeycomb formed bodies 11 placed on the 1st to 9th carriages 22 have elapsed is the same. FIG. 12 also shows that the heat curve in which each of the first to ninth bogies 22 has shifted is shifted in the middle portion of the heat curve.

  FIG. 13 is an enlarged view of the inside of the frame A in FIG. As is clear from FIG. 13, the honeycomb formed bodies 11 placed on the No. 1 to No. 9 carriages 22 have passed heat curves that are shifted from each other.

4-2. Evaluation of honeycomb fired body quality:
About the samples 1-27 of Examples 1-3, the presence or absence of generation | occurrence | production of the crack in the partition of the honeycomb fired body mounted in each No. 1-9 bogie 22 was inspected. The inspection results are shown in Tables 1 to 3, and are displayed with a circle (◯) when no sharpness occurs, and with a cross (×) when no sharpness occurs.

4-2-1. Relationship between shape of honeycomb molded body and heat curve:
For example, in the second embodiment, when considering the samples 10 to 12 having a common outer diameter of 150 mm and different total lengths, the boundary between the carriage 22 with sharpness and the carriage 22 with no sharpness is 1 for the sample 10. It was between No. 2 carriage 22 and No. 2 carriage 22, in Sample 11, between No. 2 carriage 22 and No. 3 carriage 22, and in Sample 12, between No. 3 carriage 22 and No. 4 carriage 22. That is, it was found that the ideal heat curve of each honeycomb formed body 11 varies depending on the total length of the honeycomb formed body 11. It has been found that the method of the main firing test can accurately grasp the deviation of the ideal heat curve of the honeycomb formed body 11 due to such a change in the shape of the honeycomb formed body 11.

4-2-2. Relationship between material of honeycomb formed body and heat curve:
Samples 10 to 12 of Example 2 and Samples 19 to 21 of Example 3 have the same shape, but the honeycomb molded body 11 of Samples 19 to 21 of Example 3 has additional flammable coke. It is made of a material that is added automatically. When the group of samples 10 to 12 of Example 2 and the group of samples 19 to 21 of Example 3 are compared, Sample 10 and Sample 19, Sample 11 and Sample 20, and Sample 12 are compared between the two groups. Between each of the samples 21, the boundary between the carriage 22 in which the sharpness occurred and the carriage 22 in which the sharpness did not occur was shifted. That is, it was found that the ideal heat curve of each honeycomb formed body 11 varies depending on the material of the honeycomb formed body 11. It has been found that the method of the main firing test can accurately grasp the deviation of the ideal heat curve of the honeycomb formed body 11 due to such a change in the material of the honeycomb formed body 11.

  INDUSTRIAL APPLICABILITY The present invention can be used as a method for firing a ceramic molded body, which is used for searching for an ideal heat curve for passing through a ceramic molded body in a firing step of manufacturing a ceramic product.

1: tunnel furnace, 2: inlet, 3: outlet, 4: moving direction, 11: ceramic molded body (honeycomb molded body), 11a to 11c: ceramic molded body, 21: transport means, 22: carriage.

Claims (3)

  A tunnel furnace in which a predetermined temperature is maintained at each position along the moving direction of the plurality of ceramic compacts from the inlet to the outlet is provided, and the plurality of ceramic compacts are disposed in the tunnel furnace in the moving direction. The ceramic molded body is moved from the inlet to the outlet side by side, and the speed of the ceramic molded body is changed at the same time while maintaining the same distance from the other ceramic molded bodies arranged in the front and rear in the moving direction. A method of firing a ceramic molded body, the method comprising firing the ceramic molded body so that a heat curve, which is a history of the temperature at which the ceramic molded body has passed, is shifted with respect to each of the ceramic molded bodies .   The method of firing test of a ceramic molded body according to claim 1, wherein the movement of the ceramic molded body uses a transport means for placing and moving the ceramic molded body.   The movement of the ceramic molded body is performed by placing a plurality of types of ceramic molded bodies on one transporting means, thereby simultaneously distributing the heat curve of the plurality of types of ceramic molded bodies. A method for firing a ceramic molded body according to claim 2 to be obtained.

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