JP2012237315A - Exhaust emission control device, and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inorganic fiber mat capable of favorably reducing scattering of fibers without increasing an amount of an organic binder, and to reduce an irritating feeling and a discomfort feeling during assembling work when the inorganic fiber mat is assembled to another member to make a product, thus improving a work environment of an assembling worker.SOLUTION: The inorganic fiber mat is manufactured by a method including a cutting process of cutting an inorganic fiber aggregate and a heat treatment process of heat-treating the surface of the inorganic fiber aggregate. By cutting the inorganic fiber aggregate 21 into a predetermined shape by a carbon dioxide laser machining device 41, the cutting process and the heat treatment process for heat-treating the cutting surface thereof are simultaneously performed. The inorganic fiber aggregate 21 is cut by the carbon dioxide laser machining device 41 while multiple sheets thereof are overlapped.

Description

  The present invention relates to an inorganic fiber mat. In detail, it is related with the structure for reducing the fiber scattering property in an inorganic fiber mat.

  Conventionally, a catalytic converter has been used as an exhaust gas treatment device for purifying exhaust gas discharged from an internal combustion engine. This catalytic converter is configured such that a holding sealing material is interposed between a catalyst carrier (exhaust gas treatment body) carrying a catalyst and a metal shell (casing) housing the catalyst carrier. It is common. As this holding sealing material, an inorganic fiber mat, which is made of ceramic fiber such as alumina-silica type and impregnated with an organic binder and formed into a mat having a predetermined thickness, may be employed.

  In this catalytic converter, the holding sealing material has a heat insulating effect, prevents leakage of unpurified exhaust gas from between the shell and the catalyst carrier, and prevents damage due to contact between the shell and the catalyst carrier. Play.

  Here, since the inorganic fibers constituting the holding sealing material (inorganic fiber mat) are very fine fibers, the fibers are scattered from the surface of the holding sealing material during the assembly operation of the catalytic converter, thereby deteriorating the working environment. There is a fear.

  In this regard, Patent Document 1 discloses that the dispersion of short alumina fibers can be suppressed by controlling the average fiber diameter and the minimum fiber diameter in a specific range in an alumina fiber assembly.

  Patent Document 2 discloses that by using the alumina fiber aggregate of Patent Document 1 as the holding sealing material, it is possible to suppress the amount of inorganic fibers scattered during the assembly operation of the catalytic converter. Furthermore, the said patent document 2 discloses that scattering of inorganic fiber can be suppressed also by increasing the quantity of the organic binder contained in a holding sealing material.

JP 2003-105658 A JP 2006-342774 A

  However, it is difficult to say that an alumina fiber assembly in which the average fiber diameter and the minimum fiber diameter are controlled within a specific range as in Patent Document 1 can sufficiently reduce the amount of inorganic fibers scattered, leaving room for improvement. It had been.

  Further, when the amount of the organic binder is increased as in Patent Document 2, the scattering of inorganic fibers can be considerably reduced, but the hardness of the holding sealing material is increased and the workability when wound around the catalyst carrier is reduced, and the work The efficiency will be reduced. Furthermore, when the amount of the organic binder in the holding sealing material is large, there may be a problem such as an odor generated by burning the organic binder in the initial use of the catalytic converter. Further, the holding sealing material having a large amount of organic binder may reduce the repulsive force of the holding sealing material when the organic binder burns and disappears due to the use of a catalytic converter, and may cause the catalyst carrier to fall off.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an inorganic fiber mat suitable for use as a holding sealing material or the like, which can satisfactorily reduce fiber scattering regardless of the increase in the amount of organic binder. It is to provide.

Means and effects for solving the problems

  The problems to be solved by the present invention are as described above. Next, means for solving the problems and the effects thereof will be described.

  According to the 1st viewpoint of this invention, the exhaust-gas purification apparatus of the following structures is provided. That is, the exhaust gas purification device includes an inorganic fiber mat that is obtained by cutting an inorganic fiber aggregate and heat-treating at least a part of the surface other than the cut surface by laser irradiation. The exhaust gas purification device is connected to the exhaust pipe.

  Thereby, when at least a part of the surface is heat-treated, the fibers on the surface are melted and fused to other fibers, and are not easily scattered. Therefore, fiber scattering from the inorganic fiber mat can be effectively reduced. Further, by heating the surface, the tip of the fiber exposed on the surface melts and changes to a rounded shape. This can reduce irritation and discomfort when touching the surface with a hand. Furthermore, since the fiber scattering can be satisfactorily reduced without increasing the amount of the organic binder, it can be easily adapted to the need for reducing the amount of the organic binder. Further, since the amount of the organic binder can be reduced, an increase in the hardness of the inorganic fiber mat can be avoided, and the assembly workability is excellent. Furthermore, it is possible to suppress problems such as odor generated by burning the organic binder in the initial use of the exhaust gas treatment apparatus.

  In the exhaust gas purification device, the inorganic fiber aggregate is preferably cut by a laser.

  Thereby, since cutting of the inorganic fiber aggregate and heat treatment of the cut surface (formation of the melted portion) can be simultaneously performed with the laser by cutting with the laser, the inorganic fiber mat can be easily manufactured. Further, by performing laser cutting, the cut surface (which is a surface on which fibers are easily scattered) is heat-treated without leakage. Accordingly, the fibers on the entire cut surface can be reliably melted, and the scattering of the fibers can be effectively reduced.

  In the exhaust gas purification apparatus, it is preferable that a plurality of the inorganic fiber aggregates are simultaneously cut by the laser in a state where a plurality of the inorganic fiber aggregates are stacked.

  Thereby, a some inorganic fiber aggregate is cut | disconnected at a time by cut | disconnecting in the state which accumulated the several inorganic fiber aggregate, and the cut surface can be heat-processed. Therefore, the production efficiency is further improved. Moreover, since it is non-contact cutting by laser, even when a plurality of inorganic fiber aggregates are stacked to increase the thickness, it can be cut to an accurate dimension.

  In the exhaust gas purifying apparatus, it is preferable that the inorganic fiber mat has a crystallization ratio of the heat-treated surface of 30% or more and 80% or less.

  Thereby, fiber scattering can be reduced favorably.

  The exhaust gas purification apparatus preferably has the following configuration. That is, this exhaust gas purification apparatus includes a casing and an exhaust gas treatment body. The inorganic fiber mat is disposed between the casing and the exhaust gas treating body.

  According to a second aspect of the present invention, there is provided a method for manufacturing an exhaust gas purification device that includes an inorganic fiber mat and is connected to an exhaust pipe to purify exhaust gas. The method for manufacturing the exhaust gas purifying apparatus includes a cutting step and a heat treatment step. In the cutting step, the inorganic fiber aggregate is cut to create an inorganic fiber mat. In the heat treatment step, at least a part of the surface of the inorganic fiber mat other than the cut surface is heat treated with a laser.

  Thereby, when at least a part of the surface is heat-treated, the fibers on the surface are melted and fused to other fibers, and are not easily scattered. Therefore, fiber scattering from the inorganic fiber mat can be effectively reduced. Further, by heating the surface, the tip of the fiber exposed on the surface melts and changes to a rounded shape. This can reduce irritation and discomfort when touching the surface with a hand. Furthermore, since the fiber scattering can be satisfactorily reduced without increasing the amount of the organic binder, it can be easily adapted to the need for reducing the amount of the organic binder. Further, since the amount of the organic binder can be reduced, an increase in the hardness of the inorganic fiber mat can be avoided, and the assembly workability is excellent. Furthermore, it is possible to suppress problems such as odor generated by burning the organic binder in the initial use of the exhaust gas treatment apparatus.

  In the method for manufacturing the exhaust gas purification apparatus, the inorganic fiber aggregate is preferably cut by the laser in the cutting step.

  Thereby, since cutting of the inorganic fiber aggregate and heat treatment of the cut surface (formation of the melted portion) can be simultaneously performed with the laser by cutting with the laser, the inorganic fiber mat can be easily manufactured. Further, by performing laser cutting, the cut surface (which is a surface on which fibers are easily scattered) is heat-treated without leakage. Accordingly, the fibers on the entire cut surface can be reliably melted, and the scattering of the fibers can be effectively reduced.

  In the method for manufacturing the exhaust gas purification apparatus, it is preferable that in the cutting step, the inorganic fiber aggregates are simultaneously cut by the laser in a state where a plurality of the inorganic fiber aggregates are stacked.

  Thereby, a some inorganic fiber aggregate is cut | disconnected at a time by cut | disconnecting in the state which accumulated the several inorganic fiber aggregate, and the cut surface can be heat-processed. Therefore, the production efficiency is further improved. Moreover, since it is non-contact cutting by laser, even when a plurality of inorganic fiber aggregates are stacked to increase the thickness, it can be cut to an accurate dimension.

  In the method for manufacturing the exhaust gas purifying apparatus, it is preferable that the crystallization ratio of the surface of the inorganic fiber mat heat-treated in the heat treatment step is 30% or more and 80% or less.

  Thereby, fiber scattering can be reduced favorably.

  Preferably, the method for manufacturing the exhaust gas purification device includes a step of arranging the exhaust gas treating body around which the inorganic fiber mat is wound inside a casing of the exhaust gas purification device.

1 is a schematic cross-sectional view showing a catalytic converter including a holding sealing material according to an embodiment of the present invention. The perspective view explaining the operation | work which assembles | attaches a catalyst carrier to the shell of a catalytic converter. The perspective view which shows a mode that an inorganic fiber aggregate | assembly is cut | disconnected with a carbon dioxide laser. FIG. 4A is a scanning micrograph showing the state of the cut surface when the inorganic fiber aggregate is laser cut. FIG. 4B is a scanning micrograph of a cut surface obtained by cutting the inorganic fiber aggregate with a punching blade. The side view which shows the test apparatus used for the fiber scattering property test. The graph which shows the result of having performed the fiber scattering property test of the sample cut | disconnected with the laser. The graph which shows the result of the fiber scattering property test of the sample which cut | disconnected with the laser and also irradiated the surface of the front side and the back side with the laser. The graph which shows the relationship between the crystallization rate of each sample used by the fiber scattering property test, and the fiber scattering rate.

  Next, embodiments of the invention will be described. FIG. 1 is a schematic cross-sectional view showing a catalytic converter provided with a holding sealing material according to an embodiment of the present invention, FIG. 2 is a perspective view illustrating an operation of assembling a catalyst carrier to the shell of the catalytic converter, and FIG. It is a perspective view which shows a mode that cut | disconnects with a carbon dioxide laser.

  As shown in FIG. 1, a catalytic converter (exhaust gas purification device) 11 of this embodiment includes a catalyst carrier (exhaust gas treatment body) 12, a shell (casing) 13 that accommodates the catalyst carrier 12, a catalyst carrier 12, And a holding sealing material 14 interposed between the shell 13 and the shell 13.

  The catalyst carrier 12 is formed, for example, in a columnar shape, and has a honeycomb structure having a large number of cells therein. The catalyst carrier 12 is made of ceramics such as silicon carbide, silicon nitride, cordierite, and mullite. Further, the wall surface of the cell of the catalyst carrier 12 is coated with a catalyst such as platinum, palladium, rhodium, etc., and when the exhaust gas of the vehicle engine (internal combustion engine) 31 passes through the cell of the catalyst carrier 12, Hazardous substances in exhaust gas are detoxified.

  As shown by a chain line in FIG. 2, the holding sealing material 14 has a substantially rectangular shape, and its length (length in the longitudinal direction) is substantially equal to the outer peripheral length of the catalyst carrier 12. Further, a convex portion 14a is formed at one end in the longitudinal direction of the holding sealing material 14, and a concave portion 14b is formed at the other end. The convex portion 14a and the concave portion 14b have contour shapes corresponding to each other, and are configured so that the concave portion 14b and the convex portion 14a can be fitted to each other. The holding sealing material 14 is composed of an inorganic fiber mat obtained by cutting an inorganic fiber aggregate into a predetermined shape.

  As shown in FIG. 2, the shell 13 is formed in a cylindrical shape with both ends opened, and its inner diameter is slightly larger than the outer diameter of the catalyst carrier 12. In the present embodiment, the shell 13 is made of a metal material.

  In order to assemble the catalytic converter 11 having the above configuration, first, the holding sealing material 14 is wound around the outer peripheral surface of the catalyst carrier 12. At this time, the convex portions 14a are fitted into the concave portions 14b of the holding sealing material 14, whereby the longitudinal ends of the holding sealing material 14 are connected to each other to be endless. Next, the catalyst carrier 12 around which the holding sealing material 14 is wound is press-fitted inside the shell 13 using the elasticity of the holding sealing material 14.

  As shown in FIG. 1, exhaust pipe connecting portions 15 and 16 are connected to the opening portions at both ends of the shell 13 by, for example, welding. One exhaust pipe connecting portion 15 is connected to an exhaust port of an engine 31 of the vehicle via an exhaust pipe 32 schematically indicated by a chain line. The other exhaust pipe connecting portion 16 is connected to a muffler (not shown) for noise reduction via the exhaust pipe 33.

  With this configuration, exhaust gas discharged from the engine 31 is introduced into the shell 13 of the catalytic converter 11. Inside the shell 13, the catalyst carrier 12 is held by the restoring force of the holding sealing material 14, and the exhaust gas passes through the catalyst carrier 12 and is rendered harmless.

  Since the space between the outer peripheral surface of the catalyst carrier 12 and the inner peripheral surface of the shell 13 is sealed by the holding sealing material 14, the exhaust gas introduced into the shell 13 passes through the catalyst carrier 12 without leakage. become. Further, for example, even when vibration or impact is applied to the shell 13 as the vehicle travels, it can be buffered by the elastic force of the holding sealing material 14, and damage to the catalyst carrier 12 can be prevented.

  As shown in FIG. 3, the holding sealing material 14 cuts the inorganic fiber aggregate 21 into a predetermined shape by the carbon dioxide laser processing device 41, and the surfaces other than the cut surfaces (surfaces on the front side and the back side) Irradiated while scanning with a laser of the carbon dioxide laser processing apparatus 41. The inorganic fiber aggregate 21 is formed by molding, for example, silica fiber, alumina fiber, alumina-silica-based fiber or the like into a mat having a predetermined thickness. The thickness of the inorganic fiber aggregate 21 may be, for example, 5 mm or more and 20 mm or less.

  The inorganic fiber aggregate 21 may be impregnated with an appropriate binder resin (for example, an organic binder) in order to bind the fibers. The inorganic fiber aggregate 21 may be subjected to a known needling process in order to improve its durability and strength.

  The carbon dioxide laser processing apparatus 41 shown in FIG. 3 has a configuration in which laser light is generated by a laser oscillator (not shown), and this laser light 42 is transmitted to the condensing unit 43 through an optical path formed by a reflection mirror or the like. Yes. A condensing lens 44 is installed in the condensing unit 43, and the collection of the inorganic fibers as a workpiece is performed by irradiating the laser beam 42 from the nozzle unit 45 while condensing the laser light 42 with the condensing lens 44. The body 21 can be melted and cut. Moreover, when the laser beam 42 is irradiated with the nozzle portion 45 separated from the inorganic fiber aggregate 21 by a predetermined distance, the surface layer can be heat-treated without cutting the inorganic fiber aggregate 21.

  In this embodiment, as shown in FIG. 3, a plurality of the inorganic fiber aggregates 21 are set in a carbon dioxide laser processing apparatus 41 in a state of being stacked, and cut so as to have the shape of the holding sealing material 14 shown in FIG. . As a result, a plurality of semi-finished products that are cut into a predetermined shape and whose cut surfaces are heat-treated can be obtained at a time. Thereafter, the inorganic fiber aggregates after the cutting and heat treatment are set one by one in the carbon dioxide gas laser processing apparatus 41, and the front and back surfaces of the nozzle portion 45 are separated from the laser light 42 in a state where the nozzle portion 45 is more separated than when cutting. Scan with. Thereby, surfaces (surfaces facing the thickness direction of the inorganic fiber mat) other than the cut surface can be heat-treated with a laser. In addition, the crystallization rate of the surface (cut surface and front and back surfaces) of the inorganic fiber mat thus obtained is 80% or less.

  Since the holding sealing material 14 made of the inorganic fiber mat obtained as described above has its side surface (cut surface) and the front side surface and the back side surface melted and fused with other fibers. Can be suppressed. Therefore, the working environment during the assembling work of the catalytic converter 11 as shown in FIG. 2 can be improved. Further, since the end of the fiber of the holding sealing material 14 is sharpened like a needle and exposed to the surface, the feeling of irritation and discomfort felt when the operator touches the holding sealing material 14 during assembly work or the like. Can be reduced.

  4A is a scanning micrograph of the cut surface obtained by laser cutting the inorganic fiber assembly 21, and FIG. 4B is a scanning micrograph of the cut surface obtained by cutting the inorganic fiber assembly 21 with a punching blade. is there.

  When the inorganic fiber aggregate 21 is cut with a punching blade, as shown in FIG. 4 (b), it is observed that many thin fibers constituting the mat are cut and the ends thereof are exposed on the cut surface. . The photograph of FIG. 4B suggests that when the inorganic fiber aggregate 21 is cut with a punching blade, the fibers that are cut and have a short fiber length are easily detached from the cut surface.

  On the other hand, when the inorganic fiber aggregate 21 is laser-cut, as shown in FIG. 4A, a large number of melted portions of various sizes formed by melting the fibers are formed over the entire cut surface. Is observed. A large melted part is adhered across a plurality of fibers, and many of them have a flat shape that is crushed in a direction perpendicular to the cut surface. It can be seen that the fibers exposed on the cut surface are fused to each other through such a large melting portion to form a crosslinked structure. Furthermore, it can be seen that almost all of the end portions of the fibers are melted at the cut surface, and are rounded and slightly thickened.

Next, a fiber scattering test conducted by the present inventor in order to confirm the effect of the present invention will be described. An inorganic fiber assembly (trade name: MAFTEC blanket) manufactured by Mitsubishi Chemical Corporation was used for the preparation of a sample for the fiber scattering test. This Maftec blanket is an inorganic fiber aggregate of 72% by weight of alumina and 28% by weight of silica formed into a mat shape, the average fiber diameter is 5 μm, the organic content is 0%, the surface specific gravity is 1160 g / cm ² , The thickness is about 7.1 mm.

  First, the inorganic fiber aggregate was cut with a carbon dioxide laser processing apparatus 41 as shown in FIG. 3 to prepare a sample. As the carbon dioxide laser processing apparatus 41, a device with a rated output of 1 kW, a wavelength of 10.6 μm, a minimum condensing diameter of 100 μm, and a maximum processing speed of 30 m / min is used. In this experiment, the output is 100 W and the wavelength is 10. 6 μm and the light collection diameter were set to 100 to 200 μm.

  In this experiment, four samples (first to fourth samples) were prepared by changing the output of the laser when cutting the inorganic fiber aggregate 21 in various ways. Specifically, the laser output at the time of cutting was 50 W for the first sample, 100 W for the second sample, 200 W for the third sample, and 300 W for the fourth sample. In any sample, the processing speed was 500 mm / min, and the distance between the nozzle portion 45 for irradiating the laser beam and the inorganic fiber aggregate 21 was 1 mm.

  Furthermore, as a comparative example, a sample cut with a punching blade (fifth sample) and a sample cut with a punching blade and sealed with an adhesive tape (sixth sample) were prepared. The cut shape of each of the first to sixth samples was a square of 100 mm × 100 mm.

  And about each of said 1st-6th sample, the fiber scattering property test was done using the testing apparatus shown in FIG. This test apparatus 51 has a configuration in which a sample support arm 54 is pivotally supported at the upper end of a support column 53 erected vertically on a base 52. The length of the sample support arm 54 is as follows. 92 cm. A scale plate 55 indicating the lifting angle of the sample support arm 54 is attached to the column 53. A vertical wall member 56 is fixed at a position where it can collide with the sample support arm 54.

  With this configuration, as shown in FIG. 5, the sample support arm 54 is in a horizontal posture (a lifting angle of 90 degrees) and is locked by an appropriate lock mechanism. And the said sample 60 is fixed to the front-end | tip part (82 cm-92 cm part from a rotation center) of the sample support arm 54, The lock | rock of the said locking mechanism is cancelled | released. Then, the sample support arm 54 rotates downward due to its own weight, and collides with the vertical wall member 56 fixed to the column 53 when the sample support arm 54 assumes a vertical posture indicated by a chain line. From the change in weight of the sample 60 before and after this operation, the amount of fibers scattered from the sample 60 during the rotation and collision of the sample support arm 54 (fiber scattering amount) is calculated.

  When the above fiber scattering test was performed for the first to sixth samples, the results were as shown in the graph of FIG. As shown in this graph, it can be seen that the fiber scattering rate is significantly improved in all of the first to fourth samples cut with the laser as compared with the case of cutting with the punching blade (fifth sample). Further, in the comparison when the output of the laser processing apparatus is changed, it can be seen that the fiber scattering rate is the best when the output is 50 W (first sample).

  In addition, about the 1st-6th sample, the mullite content of the cut surface was measured and the crystallization rate was computed. Moreover, about the 1st-4th sample obtained by cut | disconnecting with a laser, it measured together also about the diameter of the part (melting part) which the fiber melted | dissolved in the cut surface, and calculated the average value. .

The crystallization rate was calculated as follows. That is, a portion of the cut surface of the inorganic fiber aggregate was collected and powdered using a mortar, and X-ray diffraction was performed. In this diffraction, an X-ray diffractometer having an X-ray source of CuK _α- ray and an X-ray output of 40 kV and 20 mA was used. The diffraction lines of interest are mullite diffraction lines (16.4 °) and γ-Al ₂ O ₃ diffraction lines (45.4 °), and the scanning angle range is 15.5 ° to 17 ° for mullite. Γ-Al ₂ O _{3 was set} to 43 ° to 49 °. The scanning speed was 0.2 ° / min, and sampling was performed 0.01 ° at a time. The diverging slit was 1.0 °, the light receiving slit was 0.15 mm, the scattering slit was 1.0 °, and the monochromator slit was 0.6 mm.

Then, from the results of the above X-ray diffraction, it was calculated integrated intensity I _B of the integrated intensity of mullite I _A and γ-Al ₂ O _3. The integration ranges for calculating the integrated intensity were 16.1 ° to 16.6 ° for mullite and 43.8 ° to 48.4 ° for γ-Al ₂ O ₃ . The integrated intensities I _A and I _B were calculated by subtracting the background white X-ray count value from the actual count value. Then, the integrated intensity ratio Y calculated according to the equation Y = I _A / I _B, this by multiplying the coefficient c of a calibration curve equation, to calculate the crystallization rate X (X = cY). In the case of the inorganic fiber aggregate used in this sample, c = 1.60.

  Further, the diameter of the melted part was measured as follows. That is, about the sample cut | disconnected by the laser, the part including the laser cut surface was cut out with the cutter knife, and was extract | collected. This was set in a scanning electron microscope, and a photograph was taken at a magnification of 100 times at the central portion in the sample thickness direction on the laser cut surface. And the average value (average diameter) of each maximum length and minimum length was calculated | required about the part which the fiber melt | dissolved and became substantially spherical shape confirmed in the photograph, and this is said the said substantially spherical part (melting part) Of the diameter. This diameter was determined for all of the substantially spherical portions (melted portion) observed in the photograph, and the average was taken as the average value of the diameter of the molten portion.

  FIG. 6 also shows the crystallization ratio and the diameter of the melted portion obtained as described above. From this result, it can be seen that the fiber scattering can be satisfactorily reduced by cutting with a laser so that the crystallization rate of the cut surface is in the range of approximately 80% or less. Further, it can be seen that when the crystallization rate is in the range of 30% to 80%, the fiber scattering rate can be reduced as the crystallization rate decreases.

  Next, four samples (seventh to tenth samples) in which heat treatment was performed on the surfaces (surfaces on the front side and the back side) other than the cut surfaces of the inorganic fiber aggregates were created. In these four samples, the laser output and the processing speed at the time of cutting were set in exactly the same manner as in the first to fourth samples. Moreover, the same inorganic fiber aggregate as the said 1st-6th sample was used for the 7th-10th sample, and the cut shape was made into the square of 100 mm x 100 mm similarly to the 1st-6th sample.

  And in these 7th-10th samples, the laser of the said laser processing apparatus was further irradiated to surfaces (surface of a front side and a back side) other than a cut surface. That is, the surface on the front side and the back side were entirely heat-treated by irradiating while scanning the laser with the nozzle being separated from the surface layer of the cut inorganic fiber aggregate by a predetermined distance. The distance between the inorganic fiber aggregate (irradiated surface) and the nozzle portion 45 that irradiates the laser light 42 was constant at 100 mm.

  During the laser irradiation, the laser output was constant at 100 W in any of the seventh to tenth samples. On the other hand, the processing speed was adjusted so that the crystallization rate of the surface after irradiation was comparable to the crystallization rate of the cut surface in the corresponding first to fourth samples. Eventually, the processing speed was set to 2000 mm / min for the seventh sample, 1500 mm / min for the eighth sample, 1000 mm / min for the ninth sample, and 500 mm / min for the tenth sample.

  And about each of said 7th-10th sample, the fiber scattering property test was done using the testing apparatus shown in FIG. The graph of FIG. 7 shows the fiber scattering rate obtained by this fiber scattering test. The graph of FIG. 7 also shows the results of the fifth and sixth samples described above in addition to the seventh to tenth samples.

  In addition, the crystallization rate of the laser irradiated portion was calculated for the seventh to tenth samples as in the first to fourth samples. Furthermore, the diameter of the portion (melted portion) where the fiber melted on the cut surface and became substantially spherical was also measured.

  FIG. 7 shows the crystallization rate and the diameter of the melted portion. As shown in the measurement results, the crystallization ratios of the seventh to tenth samples are substantially the same as the corresponding first to fourth samples (FIG. 6), and the value is about 80% or less. Show. In addition, the diameter of the melted portion of the seventh to tenth samples is substantially the same size as the corresponding first to fourth samples.

  As shown in the graph of FIG. 7, the seventh to tenth samples cut with laser and further irradiated with laser on the front and back surfaces are all compared with the case of cutting with a punching blade (fifth sample). The fiber scattering rate has been greatly improved. FIG. 8 shows the crystallization rate for the fifth sample cut with a punching blade, the first to fourth samples subjected to laser cutting, and the seventh to tenth samples subjected to laser cutting and laser irradiation. The relationship of fiber scattering rate was shown.

  Regarding the points where the laser beam is irradiated to the surface other than the cut surface, the fiber scattering rate of the seventh to ninth samples is further improved as compared with the sample (first to third samples) only for laser cutting. For the 10th sample (crystallization rate around 75%), the fiber scattering rate is slightly worse than the corresponding 4th sample, but still the fiber scattering rate is sufficiently higher than the 5th sample cut with the punching blade. It turns out that it is improving.

  By combining the above results, it is possible to obtain knowledge that the scattering of the fibers can be reduced satisfactorily by performing laser irradiation so that the crystallization rate of the irradiated portion is 80% or less, preferably 70% or less. .

  Further, the sixth sample shown as a reference example shows a good fiber scattering rate (0.05%) equivalent to the seventh sample having the lowest fiber scattering rate despite being cut with a punching blade. However, when the cut surface is sealed with tape as in the sixth sample, the amount of organic increases by the amount of the tape. In the case of the sixth sample in FIG. 7, the increase in organic content due to sealing of the cut surface with tape was calculated to be about 4%. On the other hand, the first to fourth samples and the seventh to tenth samples can reduce the fiber scattering rate without increasing the organic content as described above. Therefore, it is possible to satisfactorily meet the needs for reducing the organic content.

  As described above, the inorganic fiber mat used as the holding sealing material 14 of the present embodiment is obtained by cutting the inorganic fiber aggregate 21 and also exposed to the outside (cut surfaces and front and back surfaces). ) Inorganic fibers are heat-treated and fused to each other.

  Thus, the surface of the inorganic fiber mat is heat-treated, so that the fibers on the surface are melted and fused to the surrounding fibers as shown in FIG. Therefore, the scattering of fibers from the inorganic fiber mat can be effectively reduced, and the assembly work environment for assembling the holding sealing material 14 to the catalytic converter 11 as shown in FIG. 2 can be improved. Moreover, since the tip of the fiber melts as shown in FIG. 4A due to the heating of the surface and changes to a rounded shape, it is possible to reduce irritation and discomfort when the operator touches the surface. it can.

  Further, since the scattering of fibers can be satisfactorily reduced without increasing the amount of organic binder, the necessary amount of organic binder can be reduced. Accordingly, since the hardness of the inorganic fiber mat does not increase, the work of winding the holding sealing material 14 around the catalyst carrier 12 as shown in FIG. 2 is simplified, and the assembling workability of the catalytic converter 11 is improved. Further, since the amount of the organic binder is not increased, the problem of odor when the organic binder burns at the beginning of the use of the catalytic converter 11 and the repulsive force of the holding sealing material 14 after the organic binder disappears due to the combustion are reduced, thereby reducing the catalyst carrier. The problem that it cannot be held is less likely to occur.

  In the inorganic fiber mat, the crystallization rate of the heat-treated surface is 80% or less.

  Thereby, fiber scattering can be reduced more favorably.

  Further, a round melted portion is formed on the surface exposed to the outside of the inorganic fiber mat (for example, the cut surface shown in FIG. 4A). The fibers exposed on the surface are cross-linked by the melted part.

  Thereby, since the fiber exposed to the exterior can be bridge | crosslinked by a fusion | melting part, the detachment | leave from the surface of a fiber can be prevented effectively and fiber scattering property can be suppressed favorably. In addition, it is possible to reduce irritation and discomfort when the surface of the inorganic fiber mat is touched by hand.

  The inorganic fiber mat is manufactured by cutting the inorganic fiber aggregate 21 with a carbon dioxide laser processing device 41 as shown in FIG.

  Thereby, the cutting process which cut | disconnects the inorganic fiber aggregate 21 and the heat processing process which heat-processes the cut surface can be performed simultaneously with a laser. Therefore, the inorganic fiber mat can be easily manufactured. Moreover, since it is the heat-melt cutting by a laser, the whole cut surface of the inorganic fiber aggregate 21 is heat-treated without leakage. Therefore, the fibers on the entire cut surface can be reliably melted, and the scattering of the fibers can be further reduced.

  Further, as shown in FIG. 3, the inorganic fiber aggregate 21 is simultaneously cut by a laser in a state where a plurality of the inorganic fiber aggregates 21 are stacked.

  Thereby, many inorganic fiber aggregates 21 can be cut | disconnected at once, and the cut surface can be heat-processed. Therefore, the manufacturing efficiency of the holding sealing material 14 is further improved. In addition, when trying to cut with a punching blade in a state where a plurality of inorganic fiber aggregates 21 are stacked, since the thickness is large, the portion of the inorganic fiber aggregate 21 in contact with the punching blade may be crushed during cutting. Therefore, the dimensional accuracy of the inorganic fiber mat (holding sealing material 14) may be reduced. However, in this embodiment, since it is non-contact cutting by laser, it can be cut to an accurate dimension even when a plurality of inorganic fiber aggregates 21 are stacked.

  Although the preferred embodiment of the present invention has been described above, the above configuration can be modified as follows, for example.

  The inorganic fiber aggregate 21 is not limited to the carbon dioxide gas laser processing apparatus 41, and can be changed to be cut by a laser processing apparatus using, for example, a YAG laser, an excimer laser, a He-Ne laser, a fiber laser, or a diode laser. it can. Further, laser processing of the front and back surfaces of the inorganic fiber aggregate 21 can also be performed using the various laser processing apparatuses described above.

  FIG. 3 illustrates a state in which three inorganic fiber aggregates 21 are stacked and cut, but the number of sheets cut at a time may be one or two, or four or more. However, from the viewpoint of production efficiency, it is preferable to cut a large number of inorganic fiber aggregates 21 at a time.

  The cutting of the inorganic fiber aggregate 21 can be changed so as to be cut by the punching blade, for example, without depending on the laser processing apparatus. In this case, after the cutting step, the cut surface is heated to a temperature equal to or higher than the temperature at which the inorganic fibers melt (for example, in the case of the inorganic fiber aggregate 21 having an alumina-silica composition, 1800 ° C. to 1850 ° C.), for example, by laser irradiation or a burner. If a heat treatment step for heat treatment is performed, an inorganic fiber mat with a small amount of scattered fibers can be obtained. That is, the cut surface of the inorganic fiber aggregate whose length has been shortened by cutting has a large amount of scattered fibers, but it can be effectively prevented by a melting treatment by heating.

  The holding sealing material 14 is not limited to the case where the catalyst carrier 12 of the catalytic converter 11 is held in the shell 13. For example, a DPF (diesel particulate filter) that collects particulate matter generated in a diesel engine is contained in the shell. Can be used for holding purposes.

  Instead of heat-treating the entire surface exposed to the outside of the inorganic fiber aggregate, a part of the surface can be changed to heat-treat. For example, the laser irradiation process with respect to surfaces other than the cut surface of an inorganic fiber aggregate can be omitted. Even in this case, scattering of the fibers can be effectively prevented by heat-treating the cut surface from which the fibers are easily detached.

  Before the inorganic fiber aggregate is cut into the shape of the holding sealing material with a laser, it can be changed to perform a process of irradiating the front and back surfaces with laser.

  The inorganic fiber mat is not limited to being used as a holding sealing material for holding the catalyst carrier or DPF. For example, the inorganic fiber mat can be used as a silencer used in a muffler of a vehicle such as a four-wheeled vehicle or a two-wheeled vehicle. In this case, it is possible to improve the working environment when assembling the silencer between the inner muffler and the outer muffler of the muffler, and to reduce discomfort and irritation when touched by hand. .

  The thickness and cut shape of the inorganic fiber aggregate 21 can be changed as appropriate according to the application and size of the product used.

11 Catalytic converter (exhaust gas purifier)
12 Catalyst carrier (exhaust gas treatment body)
13 Shell (casing)
14 Holding sealing material (inorganic fiber mat)
21 Inorganic fiber assembly 31 Engine (internal combustion engine)
41 Carbon dioxide laser processing equipment (laser processing equipment)

Claims (10)

It comprises an inorganic fiber mat that is formed by cutting an inorganic fiber aggregate and that is heat-treated by laser irradiation on at least a part of the surface other than the cut surface.
An exhaust gas purification device connected to an exhaust pipe. The exhaust gas purification device according to claim 1,
The exhaust gas purifying apparatus, wherein the inorganic fiber aggregate is cut by a laser. The exhaust gas purification device according to claim 2,
The exhaust gas purifying apparatus according to claim 1, wherein a plurality of the inorganic fiber aggregates are simultaneously cut by the laser in a state of being stacked. The exhaust gas purifying device according to any one of claims 1 to 3,
The exhaust gas purifier according to claim 1, wherein the inorganic fiber mat has a crystallization ratio of 30% to 80% on the heat-treated surface. An exhaust gas purification device according to any one of claims 1 to 4,
A casing and an exhaust gas treating body,
The exhaust gas purification apparatus, wherein the inorganic fiber mat is disposed between the casing and the exhaust gas treating body. In the manufacturing method of the exhaust gas purification apparatus configured to include the inorganic fiber mat and connected to the exhaust pipe to purify the exhaust gas,
A cutting step of cutting the inorganic fiber aggregate to create an inorganic fiber mat;
A heat treatment step of heat-treating at least a part of the surface other than the cut surface of the inorganic fiber mat with a laser; and
The manufacturing method of the exhaust-gas purification apparatus characterized by the above-mentioned. It is a manufacturing method of the exhaust-gas purification apparatus of Claim 6, Comprising:
In the cutting step, the inorganic fiber aggregate is cut by the laser. It is a manufacturing method of the exhaust gas purification device according to claim 7,
In the cutting step, the inorganic fiber aggregate is simultaneously cut by the laser in a state where a plurality of the inorganic fiber aggregates are stacked. It is a manufacturing method of the exhaust-gas purification apparatus as described in any one of Claim 6-8, Comprising:
A method for manufacturing an exhaust gas purifying apparatus, wherein the crystallization rate of the surface of the inorganic fiber mat heat-treated in the heat treatment step is 30% or more and 80% or less. It is a manufacturing method of the exhaust-gas purification apparatus as described in any one of Claim 6-9, Comprising:
A method for manufacturing an exhaust gas purification device comprising the step of disposing an exhaust gas treatment body around which the inorganic fiber mat is wound inside a casing of the exhaust gas purification device.