JP4582343B2 - Ceramic compact processing equipment - Google Patents

Description

  The present invention relates to a ceramic molded body processing apparatus suitable for improving the strength of a ceramic molded body. Examples of the ceramic molded body include a ferrite molded body used as a core of a coil device.

  As disclosed in Patent Document 1, the ferrite molded body is generally manufactured by the following process. First, a ferrite powder is kneaded with a binder such as PVA (polyvinyl alcohol) to produce granules having a structure in which ferrite powder is aggregated with the binder. Next, these granules are put into a predetermined mold and subjected to pressure molding to obtain a ferrite molded body. And after drying a ferrite molded object, a required characteristic, for example, a magnetic characteristic, is ensured by baking.

  By the way, in order to use the ferrite molded body as the core of the coil device, it is necessary to process the ferrite molded body into a desired shape. For example, when trying to obtain a drum-shaped core, it is necessary to scrape a cylindrical ferrite molded body with a disk-shaped grindstone to form a winding core portion around which a conducting wire is wound. Since the ferrite molded body is extremely hard at the stage after firing and becomes difficult to process, it is desirable to process at the stage before firing.

  However, since the ferrite molded body before firing is in a state where the granules are simply pressed together, it is extremely brittle and has low strength. For this reason, when processing a ferrite molded object, there exists a possibility of producing breakage, such as a chip and a crack. In addition, there is a risk of breakage when an impact is accidentally applied during handling at a stage before firing, such as when the ferrite compact is transported to a firing furnace.

Particularly, in recent years, with the downsizing and thinning of the coil device, the size of the ferrite molded body used as the core of the coil device has been reduced. For example, the ferrite molded body is thin. For this reason, the ferrite compact tends to be damaged at the stage before firing, and there is an increasing need to increase the strength in order to prevent the damage.
JP 2003-282343 A

  The subject of this invention is providing the ceramic molded object processing apparatus suitable for improving the intensity | strength of a ceramic molded object in the step before baking.

  In order to solve the above-mentioned problems, the present invention is a ceramic molded body processing apparatus used for an unfired ceramic molded body containing a water-soluble binder, and a water vapor supply chamber for applying water vapor to the ceramic molded body, There is provided a ceramic molded body processing apparatus comprising a drying chamber for drying a ceramic molded body, and a transport means for transporting the ceramic molded body from the water vapor supply chamber to the drying chamber.

  As a result of diligent research to find out the cause of the low strength of the ceramic molded body before firing, the inventors found that the failure of the binder film inside the ceramic molded body is a major factor. I found out. That is, even when an unfired ceramic molded body containing a binder is produced by pressure molding, the binder films are only pressed against each other inside the ceramic molded body, and are not sufficiently bonded. It has become. For this reason, the strength of the ceramic molded body is low.

  If the water-soluble binder is adopted as the binder of the ceramic molded body and the ceramic molded body processing apparatus of the present invention is applied, the strength of the ceramic molded body can be improved. Hereinafter, specifically, water vapor is first applied to the ceramic molded body in a water vapor supply chamber provided in the processing apparatus. Thereby, water vapor | steam is osmose | permeated inside from the surface of a ceramic molded object, the film | membrane of a water-soluble binder is moistened, and a film | membrane of a binder can be joined.

  Next, the ceramic molded body to which water vapor is applied is conveyed from the water vapor supply chamber to the drying chamber by a conveying means.

  Next, the ceramic molded body is dried in a drying chamber. Thereby, unnecessary moisture can be removed from the bonded binder film and solidified. Therefore, it is possible to improve the strength of the entire ceramic molded body.

  The steam supply chamber is preferably provided with a preheating means for preheating the ceramic molded body.

  Moreover, the ceramic molded object processing apparatus may process a ceramic molded object by a batch processing system, and may process a ceramic molded object by a continuous processing system.

  As described above, according to the present invention, it is possible to provide a ceramic molded body processing apparatus suitable for improving the strength of a ceramic molded body at a stage before firing.

  Hereinafter, the ceramic molded body processing apparatus according to the present invention will be described together with the ceramic molded body manufacturing process so that the ceramic molded body processing apparatus can be understood more.

  FIG. 1 is a flowchart showing an example of a process for producing a ceramic molded body. Here, as an example of the ceramic molded body, a ferrite molded body used for the core of the coil device is treated.

First, as shown in step S1, a ceramic powder is prepared. Here, since it is going to process a ferrite molded object, a ferrite powder is used as a ceramic powder. The ferrite powder is obtained by the following method, for example. First, a raw material powder mainly composed of Fe ₂ O ₃ , NiO, CuO, and ZnO is prepared. Next, after sufficiently mixing the raw material powder, it is pre-sintered by calcining to obtain a pre-sintered body. Then, the temporary sintered body is pulverized with a ball mill or the like to obtain ferrite powder made of pulverized powder. The particle size of the ferrite powder is 2 μm, for example.

  Next, as shown in step S2, granules are produced from the ceramic powder and a water-soluble binder. Specifically, after adding a binder to the ceramic powder and kneading sufficiently, granulation is performed by a spray dryer to obtain granules having a structure in which the ceramic powder is aggregated with the binder. Furthermore, the particle size of the granules is made uniform by a wire mesh. As an example of a water-soluble binder, PVA (polyvinyl alcohol), a polyacrylic acid polymer, etc. can be mentioned, for example. The particle size of the granules is, for example, 100 μm.

  Next, as shown in step S3, a ceramic compact is produced from the granules by pressure molding. Specifically, after putting the granule in a mold having a predetermined shape, the mold is closed and pressure is applied to obtain a ceramic molded body. Examples of the shape of the ceramic molded body include a columnar shape and a prismatic shape.

  Next, a step of preheating the ceramic molded body by applying a ceramic molded body processing apparatus to the ceramic molded body produced by pressure molding (step S4), and a step of applying water vapor to the ceramic molded body (step S5). And the step (step S6) of drying a ceramic molded object is performed.

  FIG. 2 is a diagram showing an embodiment of a ceramic molded body processing apparatus according to the present invention. The ceramic molded body processing apparatus shown in FIG. 2 includes a water vapor supply chamber 2, a drying chamber 3, and a conveying means 41. The steam supply chamber 2 and the drying chamber 3 are provided with doors 51 and 53, respectively. Each of the doors 51 and 53 functions as a carry-in port and a carry-out port for the ceramic molded body, and plays a role of preventing outside air from flowing in from outside.

  Furthermore, the water vapor supply chamber 2 and the drying chamber 3 are also partitioned by a door 52. The door 52 is provided to block water vapor and heat between the water vapor supply chamber 2 and the drying chamber 3.

  The water vapor supply chamber 2 includes a preheating means 21 for preheating the ceramic molded body 1, a water vapor supply means 22 for applying water vapor to the ceramic molded body 1, and an exhaust means 23. An example of the preheating means 21 is a heater that is disposed on the top surface of the water vapor supply chamber 2 and radiates heat.

  As an example of the water vapor supply means 22, there is an injection nozzle (hereinafter denoted by reference numeral 22) that is arranged on the top surface of the water vapor supply chamber 2 and injects water vapor. The injection nozzle 22 is connected to the water vapor generator 61. The water vapor generator 61 generates water vapor at a preset temperature.

  The exhaust means 23 plays the role of not retaining excess steam in the steam supply chamber 2 and the role of recovering and reusing excess heat. An example of the exhaust means 23 is an exhaust duct that exhausts air including water vapor inside the water vapor supply chamber 2.

  Next, the drying chamber 3 is provided with a drying means 31 for drying the ceramic molded body 1 and an exhaust means 33. An example of the drying means 31 is a heater that is disposed on the top surface of the drying chamber 3 and radiates heat.

  The exhaust means 33 plays a role of not retaining the steam released from the ceramic molded body 1 in the drying chamber 3 and a role of recovering and reusing excess heat. As an example of the exhaust means 33, an exhaust duct that exhausts air including water vapor as in the exhaust means 23 of the water vapor supply chamber 2 can be cited.

  Finally, the transport means 41 plays a role of transporting the ceramic molded body 1 from the outside to the water vapor supply chamber 2, the drying chamber 3, and further to the outside again. The conveying means 41 has a configuration suitable for intermittently feeding the ceramic molded body 1 over time. Specifically, the transport unit 41 includes a plurality of trays 411 and pushers 412. The trays 411 have the same length dimension X1 and can be loaded with a certain number of ceramic molded bodies 1 respectively. As indicated by an arrow A4, the pusher 412 has a function of pushing out the tray 411 by the tray length dimension X1 for each operation.

  Next, the usage method of such a ceramic molded object processing apparatus is demonstrated. In the ceramic molded body processing apparatus, all of the doors 51 to 53 are closed in the initial state. First, the door 51 is opened, and the tray 411 on which the ceramic molded body 1 is placed is pushed out to the water vapor supply chamber 2 by the pusher 412.

  Next, the door 51 is closed, the ceramic molded body 1 is preheated inside the water vapor supply chamber 2, and the temperature of the ceramic molded body 1 is raised. In the illustrated embodiment, as a technique for preheating the ceramic molded body 1, a technique is used in which heat is radiated from the preheating means 21 made of a heater and the ceramic molded body 1 is directly heated. A technique of indirect heating with a wave or the like can also be employed.

  Next, water vapor is applied to the ceramic molded body 1 while the temperature of the ceramic molded body 1 is sufficiently increased. In the illustrated embodiment, as a method for applying water vapor to the ceramic molded body 1, a method of injecting water vapor onto the surface of the ceramic molded body 1 by the injection nozzle 22 is employed. It is also possible to adopt a method of leaving for a certain period of time. The temperature of the water vapor is preferably set in the range of 60 ° C to 90 ° C, more preferably in the range of 70 ° C to 80 ° C. Moreover, although it depends on the dimension or shape of the ceramic molded body, the time for which water vapor is applied is set, for example, in the range of 15 minutes to 480 minutes.

  Next, the door 52 is opened, and the tray 411 on which the ceramic molded body 1 is placed is pushed out from the steam supply chamber 2 to the drying chamber 3 by the pusher 412.

  Next, the door 52 is closed and the ceramic molded body 1 is dried inside the drying chamber 3. In the illustrated embodiment, as a technique for drying the ceramic molded body 1, a technique of increasing the temperature of the ceramic molded body 1 to a predetermined drying temperature by a drying means 31 made of a heater and releasing water vapor from the ceramic molded body 1. In addition to this, it is also possible to employ a method of heating with a microwave or the like. The drying temperature and drying time are set to 120 ° C. and 1 hour, for example, although depending on the size or shape of the ceramic molded body.

  Finally, the door 53 is opened, and the tray 411 on which the ceramic molded body 1 is placed is pushed out from the drying chamber 3 by the pusher 412.

  As described above, in the ceramic molded body produced by pressure molding, the defect of the binder film inside the ceramic molded body is a major factor for reducing the strength. FIG. 3 (a) schematically shows the state of the binder at the stage of pressure molding. Referring to FIG. 2 (a), a film of a binder 8 is formed around the ceramic powder 7. However, even by pressure molding, the films of the binder 8 are merely pressed against each other and are not sufficiently bonded. For this reason, the intensity | strength seen as the whole ceramic molded object will become low.

  As a technique for joining the films of the binder 8 during the pressure molding, a technique in which the binder is softened by adjusting the moisture content of the binder in advance is considered. However, if pressure molding is performed in a state where the moisture content of the binder is increased, the granules adhere to the mold, and the pressure molding cannot be performed smoothly.

  Therefore, in the ceramic molded body processing apparatus shown in FIG. 2, water vapor is applied to the ceramic molded body 1 in the water vapor supply chamber 2. Thereby, water vapor permeates from the surface of the ceramic molded body 1 to soften the binder film, whereby the films of the binder 8 can be joined to each other as shown in FIG. .

  Thereafter, the ceramic molded body 1 is conveyed from the water vapor supply chamber 2 to the drying chamber 3, and the ceramic molded body 1 is dried in the drying chamber 3. Thereby, since unnecessary moisture can be blown from the binder inside the ceramic molded body 1, as shown in FIG. 3C, the film of the binder 8 can be contracted and solidified in a joined state. Therefore, the strength of the ceramic molded body as a whole is improved.

  Furthermore, the mechanism of strength improvement will be described from the viewpoint of the entire structure of the ceramic molded body. First, as shown in FIG. 4A, the ceramic powder 7 is in contact with the binder 8 by pressure inside the ceramic molded body 1 at the stage where the pressure molding is performed.

  Next, when water vapor is applied to the ceramic molded body 1, as shown in FIG. 4B, the binder 8 contained in the ceramic molded body 1 takes in the water vapor and expands. At that time, the ceramic powder 7 receives a compressive stress due to the expansion of the binder 8, but the ceramic molded body 1 is not destroyed because the structure of the ceramic molded body 7 is loosened.

  Thereafter, when the ceramic molded body 1 is dried, as shown in FIG. 4C, the binder 8 is dried and contracts, and a tensile stress A <b> 2 is generated in the entire ceramic molded body 1. Also by this tensile stress A2, the strength of the ceramic molded body 1 can be improved.

  Furthermore, as a result of investigations by the inventor, if water vapor is applied to the ceramic molded body to cause condensation on the surface of the ceramic molded body, the surface of the ceramic molded body may collapse and the shape of the ceramic molded body cannot be maintained. There is sex.

  With regard to such a problem, in the ceramic molded body processing apparatus shown in FIG. 2, water vapor is applied to the ceramic molded body 1 in a state where the ceramic molded body 1 is preheated by the preheating means 21, so that dew condensation occurs when water vapor is applied. This can be suppressed.

  Preferably, the ceramic molded body is preheated so that the temperature of the ceramic molded body is in the range of 60 ° C to 100 ° C. If the temperature of the ceramic molded body is lower than 60 ° C., condensation may occur when water vapor is applied. Moreover, when the temperature of the ceramic molded body is higher than 100 ° C., the ceramic molded body is dried too much, and even if water vapor is applied thereafter, there is a possibility that water vapor is not taken into the binder inside the ceramic molded body.

  Furthermore, in the ceramic molded body processing apparatus shown in FIG. 2, since the steam supply chamber 2 and the drying chamber 3 are formed separately, a suitable spray nozzle, heater, etc. are provided for each of the steam supply chamber 2 and the drying chamber 3. Equipment can be granted. If the steam supply chamber and the drying chamber are formed integrally, the ceramic molded body is dried in the same chamber after water vapor is applied to the ceramic molded body in one chamber. Equipment is needed.

  Moreover, in the ceramic molded body processing apparatus shown in FIG. 2, since the water vapor supply chamber 2 and the drying chamber 3 are disposed adjacent to each other, the water vapor supply chamber 2 does not contact the ceramic molded body 1 with outside air. It is suitable for conveying to the drying chamber 3. If the ceramic molded body 1 is brought into contact with the outside air during the transfer from the steam supply chamber 2 to the drying chamber 3, condensation may occur on the surface of the ceramic molded body 1 depending on the temperature or humidity of the outside air. . In particular, the ceramic molded body 1 to which water vapor is applied in the water vapor supply chamber 2 is in a state where it swells and its surface tends to collapse, so that dew condensation is prevented during conveyance from the water vapor supply chamber 2 to the drying chamber 3. Is important.

  Returning again to FIG. After performing steps S4 to S6 by the ceramic molded body processing apparatus, the ceramic molded body is processed into a desired shape as shown in step S7. For example, when it is going to obtain the drum-shaped core used for a coil apparatus, a cylindrical molded object is shaved with a disk-shaped grindstone, and the core part for winding conducting wire is formed.

  Finally, the ceramic compact is conveyed to a firing furnace, and the ceramic compact is fired as shown in step S8. Thereby, the ceramic powder contained in the ceramic molded body is sintered, and necessary characteristics such as electrical or magnetic characteristics are ensured.

  About the damage when processing the ceramic molded body in step S7 or the damage when transporting the ceramic molded body to the firing furnace in step S8, the strength of the ceramic molded body is improved by the ceramic molded body processing apparatus. This can be prevented.

  Next, the experimental data of the ceramic molded body processing apparatus regarding the point which improves the intensity | strength of a ceramic molded body is demonstrated. In the experiment, PVA was used as a water-soluble binder, and seven cylindrical ferrite compacts were produced by pressure molding. These were processed as samples 1 to 7 with a ceramic molded body processing apparatus. About sample 1, water vapor | steam was not applied and only the drying process (120 degreeC-1 hour) was performed in the drying chamber of the ceramic molded object processing apparatus.

  Samples 3, 4, 5, and 6 were preheated in a steam supply chamber, and then steamed at temperatures of 60 ° C., 70 ° C., 80 ° C., and 90 ° C. for 10 minutes, respectively. Thereafter, the same drying treatment as that of Sample 1 was performed.

  The remaining samples 2 and 7 were preheated in the steam supply chamber, and then steamed at temperatures of 45 ° C. and 100 ° C. for 15 minutes, respectively. Thereafter, the same drying treatment as that of Sample 1 was performed.

  About each sample 1-7 obtained in this way, fracture strength was measured, without baking. The fracture strength was measured by placing a ferrite molded body on a flat plate in such a manner that its outer peripheral surface is in contact with the flat plate and applying force to the outer peripheral surface of the ferrite molded body from above. The experimental results are shown in Table 1 below.

  Referring to Table 1, when only the drying treatment was performed without applying water vapor to the ferrite molded body (Sample 1), the fracture strength was a low value of 3.7 kgf. On the other hand, when water vapor was applied to the ferrite compact and further subjected to a drying treatment (samples 3 to 6), the fracture strength was significantly improved and became a high value of 6.3 kgf to 7.8 kgf.

  If the temperature of the water vapor is too low, only a small amount of water vapor can be taken into the water-soluble binder inside the ferrite molded body, and as a result, the fracture strength may not be improved (Sample 2).

  On the other hand, if the temperature of the water vapor is too high, the ferrite molded body is dried, so that the water-soluble binder inside the ferrite molded body is also dried and the fracture strength may not be improved ( Sample 7).

  The inventors confirmed that when the temperature of the water vapor is in the range of 60 ° C. to 90 ° C., a sufficient amount of water vapor can be taken into the water-soluble binder inside the ferrite molded body, and the fracture strength can be greatly improved. (Samples 3-6).

  Returning again to FIG. The ceramic molded body processing apparatus shown in FIG. 2 employs a batch processing method in which processing on the ceramic molded body is performed without feeding the ceramic molded body. Specifically, the preheating process and the steam application process in the steam supply chamber 2 are performed in a state where the ceramic molded body 1 is stopped without being fed. Thereafter, after the ceramic molded body 1 is transported to the drying chamber, the ceramic molded body is dried in the drying chamber 3 in a state where the ceramic molded body 1 is stopped without being fed. According to such a batch processing method, a ceramic molded body having a stable strength can be obtained. Moreover, the processing conditions can be changed more easily due to the difference in the shape of the ceramic molded body.

  FIG. 5 is a view showing another embodiment of the ceramic molded body processing apparatus according to the present invention. In the drawing, the same reference numerals are assigned to the same components as those shown in FIG. 2 and the description thereof is omitted. In contrast to the ceramic molded body processing apparatus shown in FIG. 2, the ceramic molded body processing apparatus shown in FIG. 5 employs a continuous processing method in which processing on the ceramic molded body is performed while feeding the ceramic molded body. Yes. A specific configuration will be described below.

  The conveying means 42 has a configuration suitable for continuously feeding the ceramic molded body along the conveying path. In the case of the illustrated embodiment, the conveying means 42 is constituted by a belt conveyor (hereinafter, denoted by reference numeral 42). The belt conveyor 42 is continuously formed from the outside to the water vapor supply chamber 2, the drying chamber 3, and again to the outside.

  The water vapor supply chamber 2 and the drying chamber 3 are respectively provided with air curtain devices 56 and 58 that generate an air flow functioning as an air curtain. The air curtain devices 56 and 58 play a role of preventing the outside air from flowing in without interfering with the conveying operation of the ceramic molded body 1 by the belt conveyor 42.

  Further, the air supply device 2 and the drying chamber 3 are also partitioned by an air curtain device 57. The air curtain device 57 plays a role of blocking water vapor and heat between the water vapor supply chamber 2 and the drying chamber 3 without hindering the conveying operation of the ceramic molded body 1 by the belt conveyor 42.

  Next, the usage method of the ceramic molded object processing apparatus shown in FIG. 5 is demonstrated. Feed is continuously applied to the belt conveyor 42 on which the ceramic molded body 1 is placed as time passes. As a result, the ceramic molded body 1 is preheated in the steam supply chamber 2 while being fed to the ceramic molded body 1, applied with water vapor, and the ceramic molded body 1 is dried in the drying chamber 3. According to such a continuous processing method, preheating, steaming and drying can be provided at lower costs. Moreover, there are few restrictions of the dimension of a ceramic molded object processing apparatus compared with a batch processing system.

  As an example of the ceramic molded body to which the present invention is applied, the ferrite molded body used for the core of the coil device has been described, but the present invention is not limited to this.

  The present invention is not limited to this embodiment, and it goes without saying that various modifications and changes can be made within the scope of the claims.

It is a flowchart which shows an example of the manufacturing process of a ceramic molded body. It is a figure which shows one Embodiment of the ceramic molded object processing apparatus which concerns on this invention. It is a figure which shows typically the state of the binder in the inside of a ceramic molded body. It is a figure which shows the structure of a ceramic molded body typically. It is a figure which shows another embodiment of the ceramic molded object processing apparatus which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ceramic molded body 2 Water vapor | steam supply chamber 3 Drying chamber 41, 42 Conveyance means

Claims (3)

A ceramic molded body processing apparatus used for an unfired ceramic molded body containing a water-soluble binder,
A water vapor supply chamber for applying water vapor to the ceramic molded body;
A drying chamber for drying the ceramic molded body;
A conveying means for conveying the ceramic molded body from the water vapor supply chamber to the drying chamber;
The water vapor supply chamber is provided with preheating means for preheating the ceramic molded body,
Ceramic compact processing equipment. It is a ceramic molded object processing apparatus described in Claim 1, Comprising: The ceramic molded object processing apparatus which processes a ceramic molded object by a batch processing system . The ceramic molded body processing apparatus according to claim 1 , wherein the ceramic molded body processing apparatus processes the ceramic molded body by a continuous processing method .

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