Method for manufacturing a honeycomb structure and honeycomb structure

Abstract

Provided is a method for manufacturing a honeycomb structure and a honeycomb structure. The method for manufacturing a honeycomb structure can manufacture a honeycomb structure with excellent dimensional accuracy. The method for manufacturing a honeycomb structure according to an embodiment includes: a preparation step in which a honeycomb molded body is prepared; a storage step in which the honeycomb molded body is stored in a state in which the temperature and humidity have been adjusted; and a fitting step in which the honeycomb molded body after the storage step is inserted into a metal pipe that has been heated, and then the metal pipe is cooled.

Description

Technical Field

[0001] This invention relates to a method for manufacturing a honeycomb structure and a honeycomb structure. Background Technology

[0002] Since the interior of a honeycomb structure allows for fluid flow, its application in applications such as heat exchangers and exhaust gas filters has been studied. As a method for manufacturing such a honeycomb structure, for example, a method has been proposed whereby a honeycomb molded body is produced by extrusion molding and then inserted into an outer cylinder component to fit it into the outer cylinder component (see Patent Document 1). In recent years, there has been a growing desire to improve the dimensional accuracy of honeycomb structures. However, the dimensional accuracy of the honeycomb structure described in Patent Document 1 still has room for improvement.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: International Publication No. 2021 / 171670 Summary of the Invention

[0006] The main objective of this invention is to provide a method for manufacturing a honeycomb structure that can produce a honeycomb structure with excellent dimensional accuracy.

[0007] The method for manufacturing a honeycomb structure according to the embodiments of the present invention includes: a preparation step, in which a honeycomb molded body is prepared; a storage step, in which the honeycomb molded body is stored in a state where the temperature and humidity have been adjusted; and an insertion step, in which the honeycomb molded body after the storage step is completed is inserted into a heated metal tube, and then the metal tube is cooled.

[0008] In one embodiment, the method for manufacturing the honeycomb structure further includes an outer surface processing step after the preservation step and before the fitting step, wherein the outer surface of the honeycomb molded body is processed.

[0009] In one embodiment, the honeycomb molded body comprises SiC.

[0010] In one embodiment, the method for manufacturing the honeycomb structure further includes an impregnation step after the outer surface processing step and before the fitting step. In this step, the supply body containing Si is heated so that molten metal containing Si is impregnated into the honeycomb molded body in a state where the supply body containing Si is in contact with the honeycomb molded body.

[0011] In one embodiment, the method for manufacturing the honeycomb structure further includes an impregnation step after the preservation step and before the outer surface processing step. In this step, the supply body containing Si is heated so that molten metal containing Si is impregnated into the honeycomb structure while it is in contact with the honeycomb molded body.

[0012] In one embodiment, during the above-mentioned preservation process, the temperature variation is less than 10°C and the humidity variation is 8 g / m³. 3 The following items should be stored for at least one hour.

[0013] Another aspect of the present invention relates to a honeycomb structure comprising: a honeycomb molded body and a metal tube inserted therein. The metal tube has: a large-diameter portion in contact with the honeycomb molded body and a small-diameter portion not in contact with the honeycomb molded body. When the inner diameter of the small-diameter portion is set to 100%, the inner diameter of the large-diameter portion is 100.1% or more and 101.0% or less.

[0014] In one embodiment, the small-diameter portion is located at the end of the metal tube.

[0015] Invention Effects

[0016] According to embodiments of the present invention, it is possible to manufacture honeycomb structures with excellent dimensional accuracy. Attached Figure Description

[0017] Figure 1 This is an explanatory diagram illustrating a method for manufacturing a honeycomb structure according to one embodiment of the present invention, and showing the steps for preparing the honeycomb molded body.

[0018] Figure 2 Showing the Figure 1 The process of processing the outer surface of a honeycomb molded body.

[0019] Figure 3 Showing will Figure 2 The process of inserting a honeycomb molded body into a heated metal tube.

[0020] Figure 4 This is a schematic diagram showing the structure of a honeycomb structure according to one embodiment of the present invention.

[0021] Figure 5 express Figure 4 A cross-sectional view of the central section of a honeycomb structure.

[0022] Symbol Explanation

[0023] 1…Honeycomb molded body, 2…Metal tube, 21…Large diameter section, 22…Small diameter section, D1…Inner diameter of the large diameter section, D2…Inner diameter of the small diameter section. Detailed Implementation

[0024] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings; however, the present invention is not limited to these embodiments.

[0025] A. Overview of the manufacturing method of honeycomb structures

[0026] Figure 1 This is an explanatory diagram illustrating a method for manufacturing a honeycomb structure according to one embodiment of the present invention, and showing the steps for preparing the honeycomb molded body; Figure 2 Showing the Figure 1 The process of processing the outer surface of the honeycomb molded body; Figure 3 Showing will Figure 2 The process of inserting a honeycomb molded body into a heated metal tube; Figure 4 A schematic diagram showing the structure of a honeycomb structure according to one embodiment of the present invention; Figure 5 express Figure 4 A cross-sectional view of the central section of a honeycomb structure.

[0027] One embodiment of the present invention relates to a method for manufacturing a honeycomb structure, comprising: a preparation step in which a honeycomb molded body 1 is prepared; a storage step in which the honeycomb molded body 1 is stored in a state where temperature and humidity have been adjusted; and an insertion step in which the honeycomb molded body 1, after the storage step, is inserted into a heated metal tube 2, and then the metal tube 2 is cooled. Preferably, the method for manufacturing a honeycomb structure further includes an outer surface processing step after the storage step and before the insertion step, in which the outer surface of the honeycomb molded body 1 is processed. More preferably, the method for manufacturing a honeycomb structure further includes an impregnation step after the outer surface processing step and before the insertion step, in which the supply body containing Si is heated to contact the honeycomb molded body 1, thereby impregnating the honeycomb molded body 1 with molten metal containing Si.

[0028] The inventors of this invention discovered that the environment in which a honeycomb molded body is placed before the fitting process (especially before the outer surface processing process) affects the dimensional accuracy of the honeycomb structure, thus completing this invention. In one embodiment of this invention, the honeycomb molded body is stored in a state where temperature and humidity have been adjusted before the fitting process (especially before the outer surface processing process). Therefore, the state of the honeycomb molded body after the storage process, especially its moisture absorption, can be stabilized. As a result, after the storage process (especially the outer surface processing process), the honeycomb molded body can be easily adjusted to the desired size range, improving the dimensional accuracy of the honeycomb structure.

[0029] In one embodiment of the present invention, the variation in humidity (absolute humidity) during the preservation process is, for example, 8 g / m³. 3 The following is preferred: 5g / m3 The preferred value is 2g / m 3 The following refers to the variation in humidity (absolute humidity): the difference between the maximum and minimum humidity values ​​during the preservation process. If the variation in humidity (absolute humidity) is below the upper limit mentioned above, the moisture absorption of the honeycomb molded body after the preservation process can be stabilized, and the dimensions of the honeycomb molded body can be stably adjusted to the desired range after the preservation process (especially the outer surface processing process). Typically, the lower limit of the variation in humidity (absolute humidity) during the preservation process is 0 g / m³. 3 above.

[0030] The humidity (absolute humidity) during the preservation process is set, for example, ±4.0 g / m³. 3 Additionally, a humidity setting of ±2.5g / m² can be used. 3 Additionally, a humidity setting of ±1.0 g / m² can be used. 3 Typically, the humidity is set at 0 g / m³. 3 Above 20.0g / m 3 Set arbitrarily and appropriately within the following range.

[0031] In one embodiment of the present invention, the temperature variation during the preservation process is, for example, 10°C or less, preferably 8°C or less, more preferably 5°C or less, and even more preferably 2°C or less. The temperature variation refers to the difference between the maximum and minimum temperature values ​​during the preservation process. If the temperature variation is below the aforementioned upper limit, the dimensions of the honeycomb molded body can be more stably adjusted to the desired range after the preservation process (especially the outer surface processing process). Typically, the lower limit of the temperature variation during the preservation process is 0°C or more.

[0032] The temperature during the preservation process is, for example, set at ±5.0°C, or, for example, set at ±4.0°C, or, for example, set at ±2.5°C, or, for example, set at ±1.0°C. Typically, the set temperature is arbitrarily and appropriately set within the range of 0°C to 30°C.

[0033] In one embodiment of the present invention, the storage time in the storage process is, for example, 1 hour or more, preferably 5 hours or more. If the storage time is at or above the lower limit mentioned above, the state of the honeycomb molded body after the storage process, especially the moisture absorption, can be made more stable.

[0034] The following details the process of manufacturing a honeycomb structure.

[0035] B. Preparation process

[0036] like Figure 1As shown, firstly, a honeycomb molded body 1 is prepared. The honeycomb molded body 1 has a plurality of compartments 14. The compartments 14 extend from the first end face to the second end face of the honeycomb molded body 1 in the axial direction (length direction) of the honeycomb molded body 1 (see reference). Figure 5 The compartment 14 has any suitable shape in the cross-section of the honeycomb molded body 1 in a direction orthogonal to the axial direction. Examples of cross-sectional shapes for the compartments include triangles, quadrilaterals, pentagons, hexagons, and other polygons. The cross-sectional shapes and dimensions of the compartments may all be the same, or at least some may be different.

[0037] The honeycomb molded body 1 in the figure has a cylindrical shape. The outer diameter and length of the honeycomb molded body can be appropriately set according to the purpose. The honeycomb molded body 1 in the figure includes: an outer peripheral wall 11, and a partition wall 13 located inside the outer peripheral wall 11.

[0038] The outer peripheral wall 11 has a cylindrical shape. The outer surface of the honeycomb molded body 1 is the outer peripheral surface of the outer peripheral wall 11. The thickness of the outer peripheral wall 11 can be appropriately set according to the application of the honeycomb structure. The thickness of the outer peripheral wall 11 before the outer surface processing step can be, for example, 1 mm to 10 mm, or, for example, 2 mm to 8 mm.

[0039] The partition 13 defines a plurality of compartments 14. More specifically, the partition 13 has a first partition 13a and a second partition 13b that are orthogonal to each other, and the first partition 13a and the second partition 13b define a plurality of compartments 14. Except for the portions of the first partition 13a and the second partition 13b that contact the outer peripheral wall 11, the compartments 14 have a quadrilateral cross-sectional shape.

[0040] The configuration of the honeycomb molded body is not limited to the above-described configuration. The honeycomb molded body can adopt any suitable configuration depending on the application of the honeycomb structure. Although not illustrated, the honeycomb molded body may have a hollow region at the center of its cross-section in a direction orthogonal to the axial direction (length direction). That is, the honeycomb molded body can be, for example, cylindrical (specifically, cylindrical, elliptical, or rectangular). Furthermore, the partitions of the honeycomb molded body have a first partition extending along the radial direction and a second partition extending along the circumferential direction, which can define multiple compartments.

[0041] The cell density (i.e., the number of cells per unit area) in the cross-section of the honeycomb structure in a direction orthogonal to the axial direction can be appropriately set according to the purpose. For example, the cell density can be 4 cells / cm². 2 ~320 compartments / cm 2 If the cell density is within this range, the strength and effective GSA (geometric surface area) of the honeycomb structure can be adequately ensured.

[0042] The thickness of the partition wall 13 can be appropriately set according to the application of the honeycomb structure. Typically, the thickness of the partition wall 13 is thinner than the thickness of the outer peripheral wall 11. The thickness of the partition wall 13 can be, for example, 0.1 mm to 1.0 mm, or, for example, 0.2 mm to 0.6 mm. If the thickness of the partition wall is within such a range, the mechanical strength of the honeycomb structure can be sufficient, and the opening area (the total area of ​​the cells in the cross section) can be sufficient.

[0043] The porosity of the outer peripheral wall 11 and the partition wall 13 can be appropriately set according to the purpose. Their porosity is, for example, 15% or more, preferably 20% or more, and, for example, 50% or less, preferably 45% or less. It should be noted that, for example, the porosity can be determined using mercury intrusion porosimetry. If the porosity of the outer peripheral wall and the partition wall is within such a range, capillary force can be used to impregnate the honeycomb molded body during the impregnation process.

[0044] The densities of the outer peripheral wall 11 and the partition wall 13 can be appropriately set according to the purpose. Their densities are, for example, 1.7 g / cm³. 3 The above, preferably 1.8 g / cm³ 3 The above, and for example 2.6 g / cm³ 3 The preferred value is 2.8 g / cm³. 3 The following should be noted: for example, the density can be determined using mercury intrusion porosimetry. If the densities of the outer wall and the partition wall are within such a range, then voids can be formed inside the outer wall and the partition wall with the aforementioned porosity.

[0045] The aforementioned honeycomb molded body 1 contains SiC as a main component. It should be noted that, in this specification, the term "SiC" includes not only pure SiC but also SiC containing unavoidable impurities. In addition to SiC, the constituent materials of the honeycomb molded body may also contain Al and / or Si. The SiC content in the honeycomb molded body is, for example, 50% by mass or more, preferably 85% by mass or more, and for example, 100% by mass or less, preferably 95% by mass or less.

[0046] In one embodiment, the honeycomb molded body contains an adhesive in addition to the aforementioned inorganic components (SiC, Al, and / or Si). This improves the moldability of the honeycomb molded body. Examples of adhesives include methylcellulose, hydroxypropyl methylcellulose, hydroxypropoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, and polyvinyl alcohol. The adhesive can be used alone or in combination. A combination of methylcellulose and hydroxypropoxycellulose is preferred. The adhesive content in the honeycomb molded body is, for example, 0% by mass or more, preferably 2.0% by mass or more, for example 15.0% by mass or less, and preferably 10.0% by mass or less. If the adhesive content is within the above range, the moisture absorption of the honeycomb molded body after the storage process can be more stable.

[0047] The aforementioned honeycomb molded body can be manufactured using the following method. First, a binder and water or organic solvent are added to an inorganic material powder containing SiC powder as needed. The resulting mixture is then kneaded to form a blank. The blank is shaped (typically by extrusion molding) into the desired shape and dried to produce a honeycomb molded body (dried honeycomb body). Next, the honeycomb molded body is cut to a specified length as needed. The length of the honeycomb molded body is, for example, 3 mm to 200 mm, or, for example, 5 mm to 100 mm, or, for example, 10 mm to 50 mm. Based on this, a honeycomb molded body can be obtained.

[0048] C. Preservation process

[0049] Next, the honeycomb molded body 1 is stored under the conditions (temperature, humidity, time) described in section A above. In one embodiment, the honeycomb molded body 1 is placed in a temperature and humidity controlled room where the temperature and humidity can be adjusted, thereby performing the storage process. The moisture absorption of the honeycomb molded body may be affected by the environment of the process before the mating process. If the moisture absorption of the honeycomb molded body increases, the honeycomb molded body expands and becomes larger. Therefore, if the honeycomb molded body is subjected to, for example, an outer surface processing process without considering the moisture absorption of the honeycomb molded body, the moisture absorption (expansion) of the honeycomb molded body may cause a deviation from the target value of the outer dimensions (outer diameter) of the honeycomb molded body in the outer surface processing process. According to one embodiment of the present invention, since the storage process is performed, the moisture absorption (expansion) of the honeycomb molded body after the storage process can be stabilized. Therefore, the conditions and target values ​​of the outer surface processing process can be set with regard to the moisture absorption (expansion) of the honeycomb molded body after the storage process, and the honeycomb molded body can be stably adjusted to the desired outer dimension range (outer diameter range). As a result, a honeycomb structure with excellent dimensional accuracy can be manufactured.

[0050] D. External surface machining process

[0051] In one implementation, such as Figure 2 As shown, after the preservation process is completed, an outer surface processing step is performed. This further improves the dimensional accuracy of the honeycomb structure. The time from the completion of the preservation process to the start of the outer surface processing step is, for example, within 8 hours, preferably within 4 hours. During the outer surface processing step, temperature and humidity can be managed in the same way as in the preservation process, or they can be left unmanaged. In the outer surface processing step, the outer surface (outer peripheral surface of the outer peripheral wall 11) of the honeycomb molded body 1 is processed using any suitable cutting method. This allows the outer peripheral wall 11 of the honeycomb molded body 1 to be thinned. Furthermore, in addition to processing the outer peripheral surface of the outer peripheral wall 11, an opening can be formed in the outer peripheral wall 11 during the outer surface processing step.

[0052] As a cutting method, an abrasive stone can be used as an example. The grit size of the abrasive stone is, for example, 100 or more, preferably 90 to 140. The diameter of the abrasive stone is, for example, 20 mm or more, for example, 100 mm or less, preferably 60 mm or less. The circumferential speed of the abrasive stone is, for example, 6.0 seconds or more. It is preferable to perform cutting using the abrasive stone while rotating the honeycomb molded body to be cut. The rotational speed of the honeycomb molded body is, for example, 5 rpm to 500 rpm, preferably 10 rpm to 300 rpm.

[0053] The grit size, diameter, and circumferential speed of the grinding stone can be used in any appropriate combination. For example, when the diameter and grit size of the grinding stone are small, increasing the rotation speed can smoothly process honeycomb molding.

[0054] The thickness of the outer peripheral wall 11 after the outer surface processing is, for example, 0.3 mm to 10 mm, or, for example, 0.5 mm to 5 mm. If the thickness of the outer peripheral wall is within such a range, it is possible to suppress wall damage (e.g., cracks, fissures) caused by external forces.

[0055] The outer diameter of the honeycomb structure after the outer surface processing is, for example, 20mm to 200mm, or, for example, 30mm to 100mm. It should be noted that if the cross-sectional shape of the honeycomb structure is not circular, the diameter of the largest inscribed circle that is inscribed in the cross-sectional shape (e.g., polygon) of the honeycomb structure can be set as the outer diameter of the honeycomb structure.

[0056] The arithmetic mean roughness Ra of the outer surface (outer peripheral surface of the outer peripheral wall 11) of the honeycomb molded body 1, as specified in JIS B 0601:2013, is, for example, 10 μm or less, preferably 5 μm or less. If the Ra of the outer surface (outer peripheral surface of the outer peripheral wall) of the honeycomb molded body is within such a range, then in the honeycomb structure described later, it is not necessary to provide a layer (represented by a gasket layer) between the honeycomb molded body and the metal tube to stably fix the honeycomb molded body inside the metal tube.

[0057] E. Impregnation process

[0058] In one embodiment, an impregnation process is performed after the outer surface processing step. Accordingly, molten metal containing Si is impregnated into the honeycomb molded body, enabling the honeycomb molded body to be constructed from a Si-SiC composite material. In the impregnation process, firstly, a supply containing Si is brought into contact with the honeycomb molded body after the outer surface processing. The supply body only needs to be able to contact the honeycomb molded body during the impregnation process; it can adopt any suitable shape and size and can be positioned at any suitable location.

[0059] As described above, the feedstock contains Si as a main component. In addition to Si, the feedstock may also contain Al. The Si content in the feedstock is, for example, 50% by mass or more, preferably 90% by mass or more, more preferably 95% by mass or more, for example, 100% by mass or less, preferably 97% by mass or less, more preferably 96% by mass or less. If the Si content in the feedstock is within such a range, the molten metal containing Si can be uniformly impregnated into the entirety of the honeycomb molded body during the impregnation process. The amount of feedstock used relative to 100 parts by mass of the honeycomb molded body is, for example, 20 parts by mass or more, preferably 30 parts by mass or more, for example, 80 parts by mass or less, preferably 70 parts by mass or less.

[0060] Next, the honeycomb molded body and the supply body are heated together while the supply body is in contact with the honeycomb molded body.

[0061] The heating temperature is, for example, 1200°C or higher, preferably 1300°C or higher, for example, 1600°C or lower, preferably 1500°C or lower. The heating time is, for example, 10 minutes or more, preferably 1 hour or more. If the heating temperature is within the above range and / or the heating time is at or above the lower limit of the above range, molten metal containing Si can be smoothly impregnated into the honeycomb molded body. It should be noted that, typically, the upper limit of the heating time is 10 hours or less, preferably 5 hours or less. If the heating time is below the upper limit of the above range, the manufacturing efficiency of the honeycomb structure can be improved.

[0062] Furthermore, the impregnation process is preferably carried out under reduced pressure. If the impregnation process is carried out under reduced pressure, the molten metal containing Si can be more easily impregnated into the honeycomb molded body. The pressure in the impregnation process is, for example, 500 Pa or less, preferably 300 Pa or less, more preferably 200 Pa or less, representing 10 Pa or more. It should be noted that the impregnation process can also be carried out at atmospheric pressure (0.1 MPa).

[0063] F. Fitting process

[0064] Next, as Figure 3As shown, the honeycomb molded body 1 is fitted into the metal tube 2 through a so-called thermo-pressing process. In this specification, "fitting" means that the honeycomb molded body and the metal tube are fixed in a mutually mating state.

[0065] As the metal tube 2, it is sufficient to cover the outer peripheral wall 11 of the honeycomb molded body 1, and any suitable configuration can be adopted. As the metal tube 2, for example, it can be a tubular component that fits into the outer peripheral wall 11 of the honeycomb molded body 1 and surrounds the covered outer peripheral wall 11 of the honeycomb molded body 1. As the material of the metal tube 2, examples include: stainless steel, iron, titanium alloy, copper alloy, aluminum alloy, brass, with stainless steel and iron being preferred.

[0066] Typically, the length of the metal tube 2 is greater than the length of the honeycomb molded body 1. When the length of the honeycomb molded body is set to 100%, the length of the metal tube is, for example, 100% or more, preferably 110% or more, for example, 1000% or less, and preferably 500% or less. The length of the metal tube 2 is, for example, 3mm to 200mm, and also, for example, 20mm to 150mm, and also, for example, 30mm to 100mm.

[0067] The thickness of the metal tube 2 is, for example, 0.1 mm to 10 mm, or, for example, 0.3 mm to 5 mm, or, for example, 0.5 mm to 3 mm.

[0068] The arithmetic mean roughness Ra of the inner surface (inner circumferential surface) of the metal tube 2, as specified in JIS B 0601:2013, is, for example, 10 μm or less, preferably 5 μm or less.

[0069] In one embodiment, the inner diameter of the metal tube 2 at room temperature (23°C) is less than or equal to the outer diameter of the honeycomb molded body 1. When the outer diameter of the honeycomb molded body 1 at room temperature is set to 100%, the inner diameter of the metal tube 2 at room temperature is, for example, 99.0% to 100%, and also, for example, 99.0% to 99.9%.

[0070] During the fitting process, the metal tube 2, as described above, is expanded by heating until its inner diameter exceeds the outer diameter of the honeycomb molded body 1. The heating temperature is, for example, 600°C or higher, preferably 800°C or higher, for example, 2000°C or lower, and preferably 1200°C or lower.

[0071] Next, the honeycomb molded body 1 is inserted into the heated metal tube 2. When the length of the metal tube 2 is greater than the length of the honeycomb molded body 1, the honeycomb molded body 1 is typically positioned in the center of the metal tube 2 (i.e., the honeycomb molded body does not protrude from the metal tube). Afterward, the honeycomb molded body 1 and the metal tube 2 are cooled to room temperature (23°C).

[0072] Accordingly, the metal tube 2 contracts and comes into contact with the honeycomb molded body 1, and the honeycomb molded body 1 is fixed relative to the metal tube 2. Through the above method, as... Figure 4 and Figure 5 As shown, a honeycomb structure 100 was manufactured.

[0073] G. Honeycomb structure

[0074] The honeycomb structure 100 includes a honeycomb molded body 1 and a metal tube 2 into which the honeycomb molded body 1 is inserted. In one embodiment, the metal tube 2 has a large-diameter portion 21 that contacts the honeycomb molded body 1 and a small-diameter portion 22 that does not contact the honeycomb molded body 1.

[0075] There is no honeycomb structure 1 inside the small-diameter portion 22. Typically, the small-diameter portion 22 is located at the end of the metal tube 2. In the example shown, the small-diameter portion 22 is located at both ends of the metal tube 2; however, it may also be located at only one end of the metal tube 2. The inner diameter D2 of the small-diameter portion 22 is substantially the same along its entire length. The range of the inner diameter D2 of the small-diameter portion 22 is the same as the range of the inner diameter of the metal tube at room temperature described above. The length of the small-diameter portion 22 relative to the total length of the metal tube 2 is, for example, 0% to 90%, and additionally, for example, 10% to 50%.

[0076] The inner surface of the large-diameter portion 21 is in direct contact with the outer surface of the honeycomb molded body 1 (the outer peripheral surface of the outer peripheral wall 11). There is no interlayer between the large-diameter portion 21 and the honeycomb molded body 1. The inner diameter D1 of the large-diameter portion 21 is substantially the same along its entire length. The range of the inner diameter D1 of the large-diameter portion 21 is the same as the range of the outer diameter of the honeycomb molded body described above.

[0077] When the inner diameter D2 of the small diameter portion 22 is set to 100%, the inner diameter D1 of the large diameter portion 21 is 100.1% to 101.0%, preferably 100.2% to 100.8%, and more preferably 100.3% to 100.6%. If the inner diameter of the large diameter portion is within such a range, the performance of the honeycomb structure can be sufficiently ensured.

[0078] The metal tube 2 may further have a connecting portion 23 that connects the large-diameter portion 21 and the small-diameter portion 22. The connecting portion 23 does not contact the honeycomb molded body 1, and the honeycomb molded body 1 is not present inside the connecting portion 23. The inner diameter of the connecting portion 23 gradually increases as it approaches the large-diameter portion 21 from the small-diameter portion 22.

[0079] The aforementioned honeycomb structure 100 is manufactured using the honeycomb structure manufacturing method described in items A to F above, and therefore exhibits excellent dimensional accuracy (outer diameter accuracy). When the honeycomb structure is manufactured using a method that does not include a preservation process, the dimensional accuracy of the honeycomb structure may deviate by several hundred μm in each manufacturing process. On the other hand, in one embodiment of the present invention, since the honeycomb structure is manufactured using a method that includes a preservation process, the dimensional deviation of the honeycomb structure in each manufacturing process is only at the level of tens of μm, and the dimensional accuracy (outer diameter accuracy) is significantly improved.

[0080] H. Variations

[0081] In one embodiment described above, the impregnation process is performed after the outer surface processing step and before the fitting step; however, the order of the outer surface processing step and the impregnation process is not limited to this. The impregnation process can be performed after the preservation step and before the outer surface processing step. In this case, after impregnating the honeycomb molded body with molten metal, the outer surface of the honeycomb molded body is processed, thus improving the processing accuracy. It should be noted that, compared to performing the outer surface processing step after the impregnation step, performing the outer surface processing step before the impregnation step in the above embodiment allows for smoother processing of the outer surface of the honeycomb molded body. Therefore, the order of the outer surface processing step and the impregnation step can be appropriately changed according to the purpose.

[0082] Example

[0083] The present invention will be specifically described below through embodiments; however, the present invention is not limited to these embodiments.

[0084] <Examples 1-4>

[0085] The preform containing SiC powder and binder is extruded into... Figure 1 After shaping as shown, allow it to dry to obtain a honeycomb molded body.

[0086] Next, the honeycomb molded body will be stored in a temperature and humidity management room with the temperature and humidity management range shown in Table 1 for the time shown in Table 1.

[0087] Next, the outer surface of the preserved honeycomb structure is machined using a peripheral processing machine. The time between the completion of the preservation process and the start of the outer surface processing process is 0–180 seconds. The honeycomb structure after outer surface processing has an outer peripheral wall (outer diameter 80 mm) and partitions located within the outer peripheral wall, defining multiple compartments. The length of the honeycomb structure is 50 mm. The compartment density in the honeycomb structure is 300 compartments / cm³. 2 The thickness of the partition wall is 0.5 mm, and the thickness of the outer peripheral wall is 2 mm.

[0088] Next, with the Si-containing molded body in contact with the honeycomb molded body, the mixture is heated at 1500°C for 4 hours under reduced pressure (200 Pa) to impregnate the honeycomb molded body with molten metal containing Si.

[0089] Next, the impregnated honeycomb molded body is inserted into a metal tube (stainless steel tube, 80mm in length) that has been heated to 1000°C and expanded. Then, they are cooled to allow the metal tube to shrink (hot pressing fit). In this way, the honeycomb molded body is fitted into the metal tube to obtain a honeycomb structure.

[0090] In a honeycomb structure, the metal tube has a large-diameter portion that contacts the honeycomb molding body, and a small-diameter portion located at the end of the metal tube that does not contact the honeycomb molding body. Table 1 shows the ratio (D1 / D2×100) of the inner diameter D1 of the large-diameter portion when the inner diameter D2 of the small-diameter portion is set to 100%.

[0091] Table 1

[0092]

[0093] Industrial availability

[0094] The method for manufacturing a honeycomb structure according to the embodiments of the present invention can be used in the manufacture of various industrial products, and is particularly preferred for the manufacture of heat exchangers.

Claims

1. A method for manufacturing a honeycomb structure, wherein, include: Preparation process, in which the honeycomb drying body is prepared; In the preservation process, the honeycomb dried body is preserved in a state where the temperature and humidity have been adjusted, wherein the temperature is set to be above 0°C and below 30°C, and the humidity is set to 0 g / m³. 3 Above 20.0g / m 3 The following; and In the fitting process, the honeycomb dried body, after the preservation process, is inserted into a heated metal tube, and then the metal tube is cooled. The process includes an outer surface processing step after the preservation step and before the fitting step, in which the outer surface of the honeycomb drying body is processed.

2. The method for manufacturing a honeycomb structure according to claim 1, wherein, The honeycomb drying body contains SiC.

3. The method for manufacturing a honeycomb structure according to claim 2, wherein, After the outer surface processing step and before the fitting step, an impregnation step is also included. In this impregnation step, the supply body containing Si is heated so that the supply body is in contact with the honeycomb drying body, and molten metal containing Si is impregnated in the honeycomb drying body.

4. The method for manufacturing a honeycomb structure according to claim 2, wherein, The process includes an impregnation step after the preservation step and before the outer surface processing step. In this impregnation step, the supply body containing Si is heated so that the supply body is in contact with the honeycomb drying body, thereby impregnating the honeycomb drying body with molten metal containing Si.

5. The method for manufacturing a honeycomb structure according to any one of claims 1 to 4, wherein, During the preservation process, the temperature variation is below 10°C, and the humidity variation is 8 g / m³. 3 The following items should be stored for at least one hour.

6. A honeycomb structure, which is a honeycomb structure manufactured by the method of manufacturing a honeycomb structure according to any one of claims 1 to 5, wherein, have: Honeycomb drying body; as well as A metal tube, into which the honeycomb drying body is inserted. The metal tube has: a large-diameter portion that contacts the honeycomb drying body, and a small-diameter portion that does not contact the honeycomb drying body. When the inner diameter of the smaller diameter portion is set to 100%, the inner diameter of the larger diameter portion is between 100.1% and 101.0%.

7. The honeycomb structure according to claim 6, wherein, The smaller diameter portion is located at the end of the metal tube.

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