Title of Invention

METHOD OF MANUFACTURING METAL MADE CATALYST SUPPORT AND METAL MADE CATALYST SUPPORT

Abstract ABSTRACT (l65/jVlAS/99) A method of manufacturing metal made catalyst support and a metal made catalyst support In a metal made catalyst support (20) according to an embodiment shown in Fig. 4a, a winding terminal portion (28) is aligned with a butt weld portion (26) while in a metal made catalyst support (20) according to a comparative example shown in Fig. 4b, the winding terminal portion (28) is not aligned with the butt weld portion (26). According to the present invention, since the unwelded portion due to the butt weld portion of an outer cylinder (25) is overlapped to the unwelded portion due to the winding terminal portion, there appears only one unwelded portion as compared with a related art structure in which there appear two unwelded portions, so that it is possible to ensure a sufficient effective weld length. Also since the welding is performed in a state in which the winding terminal portion is aligned with the butt weld portion, it is possible to facilitate the setup for welding, and hence to easily enhance the productivity. (Figures 4a and 4b)
Full Text


TECHNICAL FIELD The present invention relates to a method of manufacturing a metal made catalyst support and a metal made catalyst support,
BACKGROUND ART
A metal catalyzer has been known as one means for purifying an exhaust gas. For example, the concrete structure of such a metal catalyzer has been described in Japanese Patent Laid-open No. HEI-4-29750 entitled "Metal Support for Exhaust Gas Purifying Catalyst".
The above structure will be briefly described with reference to Fig. 3 of the above document. A honeycomb portion 1 is formed by winding a flat sheet 10 and a corrugated sheet 11 overlapped thereon in a roll shape, and band-like brazing filler metal members 2A and 2B are wrapped around the honeycomb portion 1. In such a state, the honeycomb portion 1 is inserted in an outer cylinder 3, and is joined to the outer cylinder 1 with the brazing filler metal members 2A and 2B.
The above brazing process, however, requires works of wrapping the brazing filler metal members 2A and 2B and also requires a heater for heating and melting the brazing filler metal. This causes a problem that the number of working steps is increased.

A welding process has been proposed in place of the above-described brazing process.
Fig. 6 shows the principle of a related art welding process. Referring to Fig. 6, a honeycomb portion 10 is inserted in an outer cylinder 101 and is fillet-welded to the outer cylinder 101 by a laser welding process using a laser beam 103.
The laser beam ^03, which forms a very small beam spot, is effective to make narrower the width of each weld bead and hence to suppress thermal strain. Accordingly, the laser welding process is suitable for welding a flat sheet 104 formed of a heat-resisting steel sheet having a thickness of 0.2 mm or less.
Figs. 7a to 7d are views illustrating a method of manufacturing a metal made catalyst support by a related laser welding process.
Fig. 7a is a perspective view of a honeycomb portion 102. Since the honeycomb portion 102 is formed by winding a flat sheet 104 and a corrugated sheet 105 overlapped thereon in a roll shape, a winding terminal portion 106 is inevitably formed on the outermost peripheral surface of the honeycomb portion 102.
Fig. 7b is an enlarged view of the winding terminal portion 106. At the winding terminal portion 106, the terminal of the outermost portion of the flat sheet 104 is drooped on a portion 104a, which is wound precedently to the outermost portion by one turn, of the flat sheet 104.
Fig. 7c is a partial enlarged view showing a state in

which the honeycomb portion 102 has been inserted in an outer cylinder 101. As shown in Fig. 7c, the outermost portion and the preceding portion 104a of the flat sheet 104 are not brought in close-contact with the inner surface of the outer cylinder 101. That is to say, an approximately triangular hollow portion 107 remains in the winding terminal portion 106.
Fig. 7d shows a state in which the outermost portion and the preceding portion 104a of the flat portion 104 are welded to the outer cylinder 101. Reference numeral 108 indicates weld beads. As shown in Fig. 7d, there appears an unwelded portion having a length B at the winding terminal portion 106.
The appearance of the above unwelded portion is undesirable; however, it cannot be perfectly eliminated unless the shape of the winding terminal portion 106 is improved. The shape of the winding terminal portion is improved by, for example, gradually reducing the heights of waveforms of the corrugated sheet 105 by secondary machining, to thereby increase the manufacturing cost. In view of the foregoing, the present invention is intended to design the metal catalyst support such that a necessary joining strength can be obtained only by the weld beads 108 of a portion obtained by subtracting the unwelded portion from the entire circumference.
However, even if the metal made catalyst support is designed such that the appearance of an unwelded portion is allowable, there occur the following problems:

(1) If there are present irregularities on the inner
surface of the outer cylinder 101, there may appear an
unwelded portion in the area of the irregularities (see a
portion B2 in Fig. 4b to be described later). In this case,
since the unwelded portion due to the irregularities is
added to the above-described unwelded portion due to the
hollow of the winding terminal portion, it may fail to
obtain a specific joining strength. To eliminate these
irregularities, there may be taken a measure of employing
the outer cylinder 101 with a flat inner surface such as a
seamless pipe or of flattening the inner surface of the
outer cylinder 101 by secondary machining; however, such a
measure is disadvantageous in increasing the manufacturing
cost.
(2) Since the size of the hollow portion 107 of the
winding terminal portion 106 varies depending on the
thickness of each of the flat sheet 104 and the corrugated
sheet 105, there appears an unwelded portion if the depth of
the hollow portion 107 is equal to or more than a specific
value; while there does not appear any unwelded portion if
the depth of the hollow portion 107 is less than the
specific value. Of course, it is preferable in terms of
joining strength that there does not appear any unwelded
portion.
The present inventors have studied to develop a method of manufacturing a metal made catalyst support, which is capable of ensuring a sufficient joining strength while employing an usual, inexpensive outer cylinder with

irregularities on its inner surface, and a honeycomb portion in which a gap is liable to occur at a winding terminal portion.
In the course of development, it has been revealed that the depth of a hollow of the winding terminal portion varies depending on the thickness of each of the flat sheet and corrugated sheet used; and heights and pitch of the corrugated sheet, and that welding for the hollow is made possible by laser welding using a laser beam if the depth of the hollow is small while welding for the hollow is made impossible if the depth of the hollow is large to such an extent that the laser beam passes through the hollow. This has led to the present invention.
DISCLOSURE OF THE INVENTION
According to an invention "■ ' there is
provided a method of manufacturing a metal made catalyst support including the steps of: preparing an outer cylinder formed by winding a flat sheet into a cylindrical shape and welding, from outside, butted ends of the flat sheet to each other into a butt weld portion, and a honeycomb portion formed by winding a flat sheet and a corrugated sheet overlapped thereon in a roll shape; measuring or predicting a depth of a hollow at a winding terminal portion of the honeycomb portion; and inserting, if the depth of the hollow is more than a specific value, the honeycomb portion into the outer cylinder in a state in which the winding terminal portion is aligned with the butt weld portion, and

fillet-welding the honeycomb portion to the outer cylinder; or inserting, if the depth of the hollow is equal to or less than the specific value, the honeycomb portion in the outer cylinder in a state in which the winding terminal portion is offset from the butt weld portion, and fillet-welding the honeycomb portion to the outer cylinder.
That is to say. when the depth of the hollow of the winding terminal portion is more than the specific value, the winding terminal portion of the honeycomb portion is purposely aligned with the butt weld portion of the outer cylinder. Meanwhile, when the depth of the hollow is equal to or less than the specific value, the winding terminal portion of the honeycomb portion is purposely offset from the butt weld portion of the outer cylinder.
According to an invention ■ , there is
provided a metal made catalyst support including: an outer cylinder formed by winding a flat sheet into a cylindrical shape and welding, from outside, butted ends of the flat sheet to each other into a butt weld portion; and a honeycomb portion formed by winding a flat sheet and a corrugated sheet overlapped thereon in a roll shape, the honeycomb portion being inserted in the outer cylinder and fillet-welded thereto, wherein a winding terminal portion of the honeycomb portion is aligned with a butt weld portion of the outer cylinder.
Since the unwelded portion due to the butt weld portion of the outer cylinder is overlapped to the unwelded portion due to the winding terminal portion, it is possible to

shorten the length of the unwelded portion and hence to ensure a sufficient effective weld length.
Accordingly, the present invention provides a method of manufacturing a metal made catalyst support, comprising the steps of: preparing an outer cylinder formed by winding a flat sheet into a cylindrical shape and welding, from outside, butted ends of the flat sheet to each other into a butt weld portion, and a honeycomb portion formed by winding a flat sheet and a corrugated sheet overlapped thereon in a roll shape; characterized by measuring or predicting a depth of a hollow at a winding terminal portion of the honeycomb portion; and inserting, if the depth of the hollow is more than a specific value determined on welding conditions, the honeycomb portion into the outer cylinder in a state in which the winding terminal portion is aligned with the butt weld portion, and fillet-welding the honeycomb portion to the outer cylinder; or inserting, if the depth of the hollow is equal to or less than the specific value determined on welding conditions, the honeycomb portion in the outer cylinder in a state in which the winding terminal portion is offset from the butt weld portion, and fillet-welding the honeycomb portion to the outer cylinder.
Accordingly, the present invention also provides a metal made catalyst support comprising: an outer cylinder formed by winding a flat sheet into a cylindrical sha; e and welding, from outside, butted ends of the flat sheet to each other into a butt weld portion, and a honeycomb portion formed by winding a flat sheet and a corrugated sheet overlapped thereon in a roll shape, said honeycomb portion being inserted in said outer cylinder characterized in that the honeycomb portion is fillet-welded to the outer cylinder and that a winding terminal portion of said honeycomb portion is aligned with a butt weld portion of said outer cylinder.
With reference to the accompanying drawings, in which

Fig. 1 is a side view of an exhaust system to which the present invention is applied.
Fig. 2 is a sectional view showing essential portions of a silencer to which the present invention is applied.
Fig. 3 is a front view of a metal made catalyst support according to the present invention.
Figs. 4a and 4b are views showing an embodiment and a comparative example of the metal made catalyst support.
Fig. 5 is a view showing another embodiment of the metal made catalyst support.
Fig. 6 is a view showing the principle of a related art welding process.
i
Figs. 7a to 7d are views illustrating maiiufacture of a metal made catalyst support in accordance with a related art laser welding process.
BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will
be described with reference to the accompanying drawings.
It should be noted that the drawings should be viewed in the
orientation of symbols.
Fig. 1 is a side view of an exhaust system to which the
present invention is- applied. An exhaust system 1 includes
an exhaust pipe 2 for introducing an exhaust gas generated

from an internal combustion engine, the silencer 10 as a noise eliminator, and a bracket 5 for mounting the exhaust pipe 2 and the silencer 10 on a body frame 4.
Fig. 2 is a sectional view showing essential portions of the silencer to which the present invention is applied. As shown by the arrangement example in Fig. 2, a silencer 10 includes a casing 11, a plurality of sound absorbing materials 12, a plurality of sound absorbing material retaining cylinders 13, a partition plate 14, a first inner pipe 15 and a second inner pipe 16 penetrating the partition plate 14, a conical pipe 17 formed at the outlet end of the first inner pipe 15, and a metal made catalyst support 20 mounted to the outlet end of the conical pipe 17.
Fig. 3 is a front view of a metal made catalyst support according to the present invention. A metal made catalyst support 20 is formed by winding a flat sheet 21 and a corrugated sheet 22 overlapped thereon in a roll shape, to form a honeycomb portion 23, inserting the honeycomb portion 23 in an outer cylinder 25, and fillet-welding the outermost peripheral portion of the honeycomb portion 23 to the outer cylinder 25 by a laser welding process using a laser beam.
The flat sheet 21 is formed of a stainless steel sheet having a thickness of about 0.1 mm (100 m) ; the corrugated sheet 22 is formed of a stainless steel sheet having a thickness of about 0.1 mm (100 m) ; and the outer cylinder 25 is formed of a stainless steel sheet having a thickness of about 1.5 mm.
The honeycomb portion 23 is adapted to support a metal

catalyst represented by platinum-rhodium which reacts with a unburned component in an exhaust gas and oxidizes (burns) the unburned component, and therefore, such honeycomb portion is called a metal made catalyst support.
A method of manufacturing the metal made catalyst support having the above configuration will be described below.
First, the outer cylinder 25 and the honeycomb portion 23 shown in Fig, 3 are manufactured as follows:
The outer cylinder 25 is formed by bending a flat sheet and welding, from outside, butted ends to each other into a butt weld portion 26 by a TIG (Tungsten Inert Gas) welding process. At this time, since the butt weld portion 26 is deformed by welding heat and thermal contraction, it projects outward. The projecting amount of the butt weld portion 26 varies depending on the welding condition and the like. It should be noted that if the butted ends of the flat sheet are welded from inside, then weld beads project inward and obstruct insertion of the honeycomb portion 23 in the outer cylinder 25. For this reason, in this embodiment, the butted ends of the flat sheet are welded from outside.
The honeycomb portion 23 is formed by spirally winding, outward from the center, the flat sheet 21 and the corrugated sheet 23 overlapped thereon. In the course of winding, both the sheets are suitably fixed to each other by spot welding. At a winding terminal portion 28, the terminal of the flat sheet 21 is only abutted on the inner adjacent portion 21a of the flat sheet 21, and therefore.

any portion of the corrugated sheet 23 is not present at the winding terminal portion 28. As a result, a V-shaped or an asymmetric V-shaped hollow portion 29 is formed at the winding terminal portion 28.
The honeycomb portion 23 is then inserted in the outer cylinder 25, and the outer peripheral portion of the honeycomb portion 23 is fillet-welded to the inner peripheral surface of the outer cylinder 25 by laser welding using a laser beam (see Fig. 6).
Laser welding using a laser beam which forms a small laser spot is suitable for Joining very thin metal sheets to each other; however, it has a problem that if a root gap between two sheets to be welded is small, there occurs a blowby phenomenon of the laser beam because of the small laser spot, which leads to welding failure.
To cope with such a problem, the method of the present invention is characterized by including steps of preparing an outer cylinder formed by winding a flat sheet in a cylindrical shape and welding, from outside, butted ends of the flat sheet, and a honeycomb portion formed by winding a flat sheet and a corrugated sheet overlapped thereon in a roll shape; and measuring or predicting the depth of a hollow of a winding terminal portion of the honeycomb portion.
With respect to the term "prediction", it is experimentally known that a variation in depth of hollows of metal made catalyst supports in one lot is equal to or less than a control value if the material, thickness, and shape

of each sheet (flat sheet, corrugated sheet); heights and pitch of waveforms of the corrugated sheet, total number of turns, winding manner, and spot welding procedure are specified, and therefore, the above control value is adopted as a prediction value.
Meanwhile, a critical value of weldable root gaps (depths of hollows) can be empirically or experimentally decided depending on the material of each sheet. The critical value is taken as "a specific value".
Hereinafter, an exemplary embodiment of the invention described in claim 1 will be described with reference to Figs. 4a and 4b and Fig. 5.
Figs. 4a and 4b show an embodiment and a comparative
example of the metal catalyst support, respectively.
In the embodiment shown in Fig. 4a, when a depth D of e.g., two times the width of the flat plate the hollow is more than a specific value,/the honeycomb
portion 23 is inserted in the outer cylinder 25 in a state
in which the winding terminal portion 28 is aligned with the
butt weld portion 26, and is then fillet-welded to the outer
cylinder 25. At this time, the winding terminal portion 28
is left unwelded. Letting Bl be the length of the unwelded
portion, an effective weld length LI is obtained by
subtracting the length Bl from the length of the 360°
circumference of the inner peripheral portion of the outer
cylinder 25 or the outer peripheral portion of the honeycomb
portion 23.
In addition, to align the winding terminal portion 28
with the butt weld portion 26, the center of the hollow

portion 29 may be substantially aligned with the butt weld portion 26.
In the comparative example shown in Fig. 4b, when the depth D of the hollow is more than the specific value, the honeycomb portion 23 is inserted in the outer cylinder 25 in a state in which the winding terminal portion 28 is not aligned with the butt weld portion 26 (for example, the winding terminal portion 28 is offset clockwise about 80° from the butt weld portion 26), and is then fillet-welded to the outer cylinder 25. In this case, there appears an unwelded portion having a length B2 due to the butt weld portion 26, in addition to the unwelded portion having the length Bl, and consequently, the effective weld length (L2 + L3) is obtained by subtracting the length (Bl + B2) from the 360° circumference.
The effective weld length (L2 + L3) in the comparative example is less than the effective weld length LI in the embodiment. This means that a margin of the joining strength in the comparative example is undesirably smaller than that in the embodiment.
Fig. 5 shows another embodiment of the metal catalyst support. In this embodiment, when the depth D of the hollow is equal to or less than the specific value, the honeycomb portion 23 is inserted in the outer cylinder 25 in a state in which the winding terminal portion 28 is offset from the butt weld portion 26, and is then fillet-welded to the outer cylinder 25.
That is to say, since the depth D of the hollow is

small, the winding terminal portion 28 can be welded to the outer cylinder 25. Further, if the projecting amount of the butt weld portion 26 of the outer cylinder 25 is small, the butt weld portion 26 may be weldable to the honeycomb portion 23. In this case, the 360°circumference becomes the effective weld length.
The reason why the winding terminal portion 28 is purposely offset from the butt weld portion 26 is as follows:
If the winding terminal portion 28 is aligned with the butt weld portion 26 even though the depth D of the hollow is equal to or less than the specific value, there may occur the following inconvenience.
In some cases, although the depth D of the hollow is less than the specific value, the added value (D + t), where t is a depth of the inner hollow of the butt weld portion 26 of the outer cylinder, exceeds the specific value. And, if the added value (D + t) exceeds the specific value, there occurs welding failure as shown in Fig. 4a. The effective weld length in the state shown in Fig. 4a is undesirably smaller than that in the state shown in Fig. 5. In addition, the state shown in Fig. 5 allows welding-all-round for the 360°circumference.
In this way, when the depth D of the hollow of the winding terminal portion 28 is more than the specific value, the winding terminal portion 28 of the honeycomb portion is purposely aligned with the butt weld portion 26 of the outer cylinder. This brings about the state shown in Fig. 4a.

Meanwhile, when the depth D of the hollow is equal to or less the specific value, the winding terminal portion 28 of the honeycomb portion is purposely offset from the butt weld portion 26 of the outer cylinder. This brings about the state shown in Fig. 5.
The above-described manufacturing method .
is advantageous in
ensuring a sufficient effective weld length; however, such a method is somewhat complicated because it requires the step of measuring or predicting the depth of the hollow.
Next, an exemplary embodiment of the invention ———
' ■■—^which is intended to reduce the manufacturing
cost, will be described.
Expediting the reduction in the cost of a metal made
catalyst support tends to make larger both the depth D of
the hollow and the depth of the inner hollow of the butt
weld portion 26. In this regard, according to the invention
mm •' the structure of the metal catalyst
support shown in Fig. 4a in which the winding terminal portion 28 is aligned with the butt weld portion 26, is adopted irrespective of the depth D of the hollow and the depth of the inner hollow of the butt weld portion 26.
The adoption of such a structure is effective to eliminate the step of measuring or predicting the depth of the hollow, and hence to improve the productivity. That is to say, since the unwelded portion due to the butt weld portion of the outer cylinder is overlapped to the unwelded portion due to thd winding terminal portion, there appears

only one unwelded portion, so that it is possible to ensure a sufficient effective weld length. Also since welding is performed in the state in which the winding terminal portion is aligned with the butt weld portion, it is possible to facilitate the setup for welding, and hence to easily enhance the productivity.
In carrying out the present invention, the laser welding process using a laser beam is suitable for welding the honeycomb portion to the outer cylinder; however, the laser welding process may be replaced with a different welding process such as an electron beam welding process.
INDUSTRIAL APPLICABILITY The present invention having the above arrangement achieves the following advantageous results.
According to the invention described in claim 1, since the depth of the hollow of the winding terminal portion is more than the specific value, the winding terminal portion of the honeycomb portion is purposely aligned with the butt weld portion of the outer cylinder, and when the depth of the hollow is equal to or less than the specific value, the winding terminal portion of the honeycomb portion is purposely offset from the butt weld portion of the outer cylinder, there appears only one unwelded portion or no unwelded portion, so that it is possible to ensure a sufficient effective weld length.
According to the invention described in claim 2, since the unwelded portion due to the butt weld portion of the

outer cylinder is overlapped to the unwedled portion due to the winding terminal portion, there appears only one unwelded portion, so that it is possible to ensure a sufficient effective weld length. Also since the welding is performed in a state in which the winding terminal portion is aligned with the butt weld portion, it is possible to facilitate the setup for welding, and hence to easily enhance the productivity.


WE CLAIM;
1. A method of manufacturing a metal made catalyst support (20), comprising the steps of: preparing an outer cylinder (25) formed by winding a flat sheet (21) into a cylindrical shape and welding, from outside, butted ends of the flat sheet to each other into a butt weld portion (26), and a honeycomb portion (23) formed by winding a flat sheet (21) and a corrugated sheet (22) overlapped thereon in a roll shape; characterized by measuring or predicting a depth of a hollow at a winding terminal portion (28) of the honeycomb portion; and inserting, if the depth of the hollow s more than a specific value determined on welding conditions, the honeycomb portion (23) into the outer cylinder (25) in a state in which the winding terminal portion (28) is aligned with the butt weld portion (26). and fillet-welding the honeycomb portion (23) to the outer cylinder (25); or inserting, if the depth of the hollow is equal to or less than the specific value determined on welding conditions, the honeycomb portion (23) in the outer cylinder (25) in a state in which the winding terminal portion (28) is offset from the butt weld portion (26), and fillet-welding the honeycomb portion (23) to the outer cylinder (25).
2. A metal made catalyst support (20) comprising: an outer cylinder (25) formed by winding a flat sheet (21) into a cylindrical shape and welding, from outside, butted ends of the flat sheet (21) to each other into a butt weld portion (26), and a honeycomb portion (23) formed by winding a flat sheet (21) and a corrugated sheet (22) overlapped thereon in a roll shape, said honeycomb portion (23) being inserted in said outer cylinder (25) characterized in that the honeycomb portion (23) is fillet-welded to the outer cylinder (25) and that a winding terminal portion (28) of said honeycomb portion (23) is aligned with a butt weld portion (26) of said outer cylinder (25).
3. A method of manufacturing a metal made catalyst support substantially as herein described with reference to figures 1 to 5 of the accompanying drawings.

A. metal made catalyst support substantially as herein described with reference to figures 1 to 5 of the accompanying drawings.


Documents:

0165-mas-1999 abstract.pdf

0165-mas-1999 claims.pdf

0165-mas-1999 correspondence-others.pdf

0165-mas-1999 correspondence-po.pdf

0165-mas-1999 description (complete).pdf

0165-mas-1999 drawings.pdf

0165-mas-1999 form-19.pdf

0165-mas-1999 form-2.pdf

0165-mas-1999 form-26.pdf

0165-mas-1999 form-4.pdf

0165-mas-1999 form-6.pdf

0165-mas-1999 others.pdf

0165-mas-1999 petition.pdf


Patent Number 198885
Indian Patent Application Number 165/MAS/1999
PG Journal Number 23/2006
Publication Date 09-Jun-2006
Grant Date 17-Feb-2006
Date of Filing 09-Feb-1999
Name of Patentee HONDA GIKEN KOGYO KABUSHIKI KAISHA,
Applicant Address 1-1 MINAMI AOYAMA, 2-CHOME MINATO-KU TOKYO
Inventors:
# Inventor's Name Inventor's Address
1 MASAHARU NAKAMORI C/O HONDA R&D CO. LTD., 4-1, CHUO 1-CHOME, WAKO-SHI, SAITAMA
2 KATSUNOURI OOKUBO C/O HONDA R&D CO. LTD., 4-1, CHUO 1-CHOME, WAKO-SHI, SAITAMA
3 MITSUNORI TAKEKAWA C/O. YUTAKA GIKEN CO. LTD. 508-1, YUTAKA-MACHI, HAMAMATSU-SHI, SHIZUOKA
4 YUKINORI KANEDA C/O. YUTAKA GIKEN CO. LTD. 508-1, YUTAKA-MACHI, HAMAMATSU-SHI, SHIZUOKA
5 TOSHIAKI OKADA C/O. YUTAKA GIKEN CO. LTD. 508-1, YUTAKA-MACHI, HAMAMATSU-SHI, SHIZUOKA
PCT International Classification Number B01J35/00
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 10-084562 1998-03-30 Japan