JP3105040B2 - Method for producing metal catalyst carrier for purifying exhaust gas - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a metal catalyst carrier used in an exhaust gas purifying apparatus (catalytic converter) for an internal combustion engine mounted on an automobile or the like.

[0002]

2. Description of the Related Art Catalysts used in exhaust gas purification devices (catalytic converters) for internal combustion engines mounted on automobiles and the like include:
It is roughly classified into a pellet type and a monolith type according to the shape of the carrier. What occupies the mainstream of the monolith type is two types, one having a ceramic carrier and one having a metal carrier, and among those having a metal carrier, a metal having high heat resistance such as heat-resistant stainless steel is used. foil thin plate and without, remains one tabular, also on the other one with pleated waveform, wound spirally their combined <br/> ne heavy, the center This is a honeycomb-shaped carrier having a large number of small holes in the axial direction.
Then, a catalytic coating containing a catalytic substance such as a noble metal is applied to the resultant to form a catalyst. Since the metal catalyst carrier generally has a smaller heat capacity than the ceramic carrier, the time required for warming up is short, and the catalyst reaches the activation temperature quickly and exhibits the exhaust gas purification function quickly. And has the advantage of less resistance to the flow of exhaust gas as compared to pellet-type carriers, and has recently come to be used relatively frequently.

FIGS. 3 to 5 show a first prior art metal carrier. In FIG. 3, a flat heat-resistant metal foil 1 and a corrugated foldable heat-resistant metal foil 2 are superimposed and spirally wound around a cylindrical metal core 3 to form a cylindrical honeycomb. The carrier 4 is formed. Since the diameter is relatively large as it is, if it is mounted under the floor of the body of the car, the minimum ground height is reduced. Therefore, the cylindrical cored bar 3 is pulled out and then pressed vertically. It is common to form a flat race track-shaped honeycomb carrier 5 as described above and use the direction of the minor axis as the vertical direction.

FIGS. 6 and 7 show a second prior art. As in the first prior art, after forming a simple cylindrical honeycomb-shaped carrier 4 as an intermediate molded body, the honeycomb-shaped carrier 4 is not pressed vertically to form a racetrack shape, but a plate-shaped core metal. At both ends of the plate 6, a flat heat-resistant metal foil 1 and a heat-resistant metal foil 2 with a corrugated fold are attached, and the plate-shaped cored bar 6 is rotated as shown by an arrow, as shown in FIG. By winding the metal foils 1 and 2 around a plate-shaped cored bar 6, a flat race track-shaped honeycomb-shaped carrier 7 is manufactured from the beginning.

[0005]

The first problem shown in FIGS. 3 to 5 is as follows.
In the prior art, since the cylindrical honeycomb-shaped carrier 4 is pressed vertically by a press to form the race-track-shaped honeycomb-shaped carrier 5, even if lateral displacement is allowed between the respective layers of the honeycomb structure, Since the flat heat-resistant metal foil 1 in the outer peripheral portion hardly extends, the outer peripheral length of the race-track-shaped honeycomb carrier 5 after the press molding is almost equal to the outer peripheral length of the cylindrical honeycomb carrier 4. Despite being the same, when changing from a circle to a racetrack shape, the relatively inner layers tend to be longer in length, so that the inner layers are regular as shown in FIG. In some cases, the stratified structure collapses, and the irregularly shaped portion 8 is distorted into a loose shape.

[0006] This problem is to prevent the shape from collapsing.
When the ends and side edges of the rolled-up metal foils 1 and 2 are joined to each other by a method such as spot welding or laser welding before the press forming as illustrated at a point 9 and then pressed and formed, Since the lateral displacement is not allowed, irregular torsional deformation and distortion are further caused, and in the state of the cylindrical honeycomb-shaped carrier 4, a part of a large number of small holes formed in the axial direction as the honeycomb structure becomes part of the race track. In some cases, the honeycomb-shaped carrier 5 may be partially closed.

This phenomenon is caused by intermediate molding as shown in FIG.
In the state of the cylindrical honeycomb carrier 4 as a body, the marking strip 1 having a constant width in the diameter direction with a color paint on the side surface.
After drawing 0, 11, and 12 , when this cylindrical honeycomb-shaped carrier 4 is pressed and formed in the vertical direction to form a track-shaped honeycomb-shaped carrier 5 as a final molded body , As shown in FIG. 4, the strips 10, 11, and 12 are deformed, and the strips 10 ', 11', and 1 in the form of strips whose widths are not constant but collapsed.
It can be understood from 2 '. Therefore,
It turns out that it is impossible to manufacture the honeycomb-shaped carrier 4 having a cylindrical shape and then forming it into the honeycomb-shaped carrier 5 having a racetrack shape.

The second prior art shown in FIGS. 6 and 7 has been conceived in order to solve the problem of the first prior art. Metal foil 1,
After wound up as a honeycomb-shaped carrier 7 of racetrack 2 from the beginning, that extracts the core metal 6 from its center, which performs finish forming is pressed against the amount corresponding to the vertical direction of the thickness of the core bar 6 In the press molding, since the displacement between the layers is smaller than that of the first conventional technique, no significant distortion deformation occurs, but it has been found that another problem also occurs in the second conventional technique.

The second problem of the prior art is that when the flat heat-resistant metal foil 1 and the corrugated foldable heat-resistant metal foil 2 are superimposed and wound around the plate-shaped metal core 6, In the vicinity of both edges 13 and 14 of the plate-shaped cored bar 6, metal foils 1 and 2
Is applied with sufficient tension, and the metal foils 1 and 2
Although they are strongly pressed against the metal foils 3 and 14, the tension acting on the metal foils 1 and 2 becomes weaker at the portions corresponding to the upper and lower surfaces 15 and 16 of the plate-shaped metal core 6, and as shown in FIG. Since the foils 1 and 2 are lifted and loosened from the upper and lower surfaces 15 and 16 of the plate-shaped cored bar 6, large gaps 17 and 18 are generated, the pressing force between the respective layers is small, and the positions of the respective layers are uncertain and separated from each other. It means that it will be in an easy state.

This problem of the second prior art is caused by the fact that the plate-shaped metal core 6 is flat. When the metal core 6 is flat, the upper and lower surfaces 15, 16 are formed. Unless theoretically infinite tension is applied to the metal foils 1 and 2 in the corresponding portions, a sufficient pressing force to press the metal foils 1 and 2 vertically cannot be obtained. When excessive tension is applied to the metal core 6, the pressing force of the metal foils 1 and 2 in the vicinity of both end edges 13 and 14 of the plate-shaped cored bar 6 becomes excessive, the metal foil 2 is deformed, and the nearby small axial holes are formed. Is crushed, there is a natural limit to the tension that can be applied, and it is impossible to eliminate the gaps 17 and 18 after all.

As a countermeasure against this problem in the second prior art, the height of the folds of the heat-resistant metal foil 2 having the corrugated folds is determined by the upper and lower surfaces 15 and 16 of the plate-shaped cored bar 6. There is a method in which the height of the fold is partially changed so that the height gradually increases toward a portion corresponding to the vicinity of the center. For this purpose, the heat-resistant metal foil 2 having a corrugated fold is used everywhere. Since a material having the same wave height cannot be used, it is necessary to perform a complicated pretreatment of partially changing the wave height of the metal foil 2 by a roller or the like before winding the metal foils 1 and 2 around the cored bar 6. This raises another problem that this raises costs.

[0012]

According to the present invention, as a means for solving the above-mentioned problems, the cross-sectional shape is determined at any position in the direction of the central axis.
Oite be rounded rhombic shape having uniformly corners, the length of the cross-sectional shape of the rhombus
A groove is formed on the pair of radial edges in the direction of the central axis.
Using the core metal that is, of the pair of edges of said metal core one
Insert one end of a flat heat-resistant metal foil into the groove formed on the side
At the other end of the pair of edges.
The inserted one end of the heat-resistant metal foil that has been pleated waveform into the groove
And insert the two metal foils around the cored bar.
Ri as overlapping, the intermediate product put come wound around the core metal while applying a slight tension on these metal foils
After forming the withdrawn the core metal from a central portion of the intermediate product, further the intermediate molded into a flat shape
By pressing the body minor diameter direction of the cross-sectional shape, said
A method for producing a metal catalyst carrier for purifying exhaust gas is provided, wherein the intermediate molded body is formed into a honeycomb-shaped carrier having a racetrack cross section .

[0013]

[Action] for cross-sectional shape of the core is a round diamond-shaped corners, this
Edge the metal bar so that it overlaps around the metal core.
When winding the two types of metal foil which is Attach, the edges corresponding to both ends of the major axis part of the cross-sectional shape, greater pressing force to the layers of the metal foil occurs, of course, both of the short diameter portion of the cross-sectional shape content Oite the relatively flat portion corresponding to <br/> end also, the core metal is crowned
Because it has become, unreasonable the magnitude of the tension required for the metal foil
Acts without significant pressure sufficiently between the layers of metal foil obtained <br/> is Ru. Therefore, no gap is generated between the overlapping metal foils, and the metal foil is not loosened and the position is not fixed.
Insert the end of the metal foil into the groove formed on the edge of the cored bar.
The metal foil of the part inserted in the groove
The metal foil is pressed down, and the end of the metal foil is
It is securely installed in the groove. Large required thereby
The tension of the size reliably acts on the metal foil. Metal foil cored
After the formation of the intermediate molded body by raising the winding around the intermediate mold
Pull out the metal core from the center of the body and cut the
When pressed by a press in the direction of the minor axis of the surface, the shape becomes a flatter racetrack shape. The gas flow path is reliably formed. In addition, the cross-sectional shape of the metal core is evenly rounded in the direction of the central axis.
When the cross section is strictly elliptical due to the diamond shape,
The innermost metal foil does not adhere to the surface of the core metal
Between the flat surface of the metal core and the innermost metal foil.
A small gap occurs. The existence of this minute gap,
The edge of the metal foil is the groove formed in the edge of the core bar.
Can slide in the direction of
The work of removing the core is easy, and
The molded article does not collapse.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The cross-sectional shape for carrying out the method of the present invention is square.
Cored bar 20 is illustrated in FIG. 1 is a round diamond shape of. In the core metal 20 of the illustrated example, 80 mm and the total length L, 10 mm thickness S of the Hisashi Naka portion, near the central portion in the upper surface 21 and lower surface 22 round
With the Mino radius of curvature R and 215 mm, the cross-sectional shape long
The radius of curvature r of the roundness of the left and right edges 23 and 24 in the radial direction is set to 1.5 mm. The cross-sectional shape of the core 20 is
The shape is the same at any position in the central axis direction. Both edges 2
Grooves 2 and 3 for inserting the ends of the metal foils 1 and 2
5 and 26 are provided in the central axis direction .

[0015] When carrying out the process of the invention, as shown in FIG. 2, the grooves 25 and 26 of opposite ends 23 and 24 of the core 20 of the round diamond shaped cross-section corners, flat plate-shaped heat The end of the heat-resistant metal foil 2 or the corrugated foldable heat-resistant metal foil 2 is inserted and attached. Metal foil inserted in grooves 25, 26
The ends of 1 and 2 are overlaid with other metal foil
Therefore, it is securely held in the groove to be held down.
You. As a result, the core bar 20 is rotated in the direction of the arrow while applying a tension to the metal foils 1 and 2 such that the folds of the metal foil 2 do not cause abnormal deformation even in the vicinity of both end edges 23 and 24 of the core bar 20. Then, the metal foils 1 and 2 are wound on the metal core 20 so as to overlap each other.

[0016] For cross-sectional shape of the core metal 20 is rounded lozenge-shaped corners, the pressing force between the metal foil 1 and 2 in the vicinity of both edges 23, 24 of the core 20 increases, of course, the upper and lower Since the portions corresponding to the surfaces 21 and 22 are protruded curved surfaces, a sufficient pressing force can be obtained, and the layers are in close contact with each other so that no gap is generated. The position of each layer is definitely determined, and the metal foils 1 and 2 do not float unnecessarily at that position. Unlike the second conventional technique, only a slight tension is applied to the metal foils 1 and 2, and the portions corresponding to the upper and lower surfaces 21 and 22 of the cored bar 20 have a pressing force required for the close contact between the layers. As a result, it is not necessary to increase the tension too much. Accordingly, no excessive pressing force is generated in the metal foils 1 and 2 near the both end edges 23 and 24 of the metal core 20, so that there is no possibility that many small holes 27 in the axial direction are crushed. In addition, core metal 2
When the cross section of 0 is completely elliptical, the gold
In the state of the intermediate molded body in which the metal foils 1 and 2 are wound up,
The innermost layer portions of the metal foils 1 and 2 adhere to the surface of the cored bar 20
Therefore, the work of extracting the cored bar 20 in the direction of its central axis is easy.
If it is not easy to pull it out, the intermediate molded body will lose its shape
There is a danger. On the other hand, in the present invention, the core metal
Since the cross-sectional shape of the base metal 20 is a rhombus with rounded corners,
The plane part of the surface and the innermost layer of the metal foils 1 and 2
A small gap is generated between them. This minute gap exists
As a result, the work of extracting the core metal 20 from the intermediate molded body can be performed.
This makes it difficult for the intermediate molded body to collapse
You.

[0017] In addition, winding a metal foil 1 and 2 on top of the metal core 20
After forming the intermediate molded body having a flat shape by raising, the core metal 20 is removed from the center of the intermediate molded body in the next step, and is pushed in the vertical direction , that is, in the short diameter direction of the cross-sectional shape of the intermediate molded body. Although pressure is applied, no abnormal deformation or twisting occurs at that time, the cross-sectional shape changes to a regularly flat race track shape, and a number of small holes 27 in the axial direction are not deformed. Since it remains in the form, it does not significantly increase the flow resistance of the exhaust gas as a catalyst carrier. The direction of the grooves 25 and 26 formed on both end edges of the cored bar 20
Is the direction in which the metal core 20 is removed from the intermediate molded body, that is, the intermediate component.
The grooves 25 and 26 are aligned with the center axis direction of the shape and the like.
The ends of the metal foils 1 and 2 held inside
It can slide in the grooves 25 and 26 of the cored bar 20.

According to the method of the present invention, a state of forming a preform by winding a metal foil 2 to the core 20, the intermediate
Intermediate molding after extracting the core metal 20 from the center of the molded body
When comparing the state in which the body is pressed with a press in the minor axis direction of the cross-sectional shape, there is no large change in the cross-sectional shape between them, and there is almost no displacement between the layers of the metal foils 1 and 2, After being wound up , the layers between the metal foils 1 and 2 and the end edges at the end of the winding are fixed by welding, and then the short diameter of the cross-sectional shape is obtained.
Be molded into a flat race-track cross-sectional shape of the final molded body is pressed in a direction, do not occur partially deformed excessively, it is possible to fix the shape sufficiently welded where necessary This makes it possible to obtain a very robust catalyst support.

[0019]

According to the present invention, the cross-sectional shape is rounded.
The problem of the prior art is solved by using a diamond-shaped core metal, and when the intermediate molded body is pressed in the direction of the minor axis of the cross section,
It does not occur at all abnormal deformation can, flat metallic catalyst carrier of the correct honeycomb shape can be easily obtained. Also,
Prior to this, the intermediate molded body wound on the cored bar
The work of removing the core from the center is also easy,
No mold collapse occurs in the intermediate molded body. Furthermore, on the edge of the cored bar
Do not attach two types of metal foil to the formed groove at the same time.
Each metal is attached separately to each edge.
As a result of the foil being securely attached to the core metal,
The tension acts reliably on the metal foil. Nevertheless,
When extracting the core metal from the intermediate molded body in the central axis direction,
In the groove of the edge of the core metal where the end of the genus foil is capturing it,
Since it can slide in the direction of the groove, the mold of the intermediate molded body
Collapse is prevented. Moreover, according to the method of the present invention,
Since the flow path of the exhaust gas in the central axis direction inside the metallic catalyst carrier as final molded product is reliably formed, touch the metal
Even if the medium carrier is used in the exhaust passage of the internal combustion engine, it does not give a large resistance to the flow of exhaust gas.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a core used in the method of the present invention.

FIG. 2 is a sectional view showing a state in which the method of the present invention is performed.

FIG. 3 is a sectional view showing an intermediate step in the first conventional technique.

FIG. 4 is a conceptual cross-sectional view showing a problem in the first related art.

FIG. 5 is a cross-sectional view showing a problem in the first related art.

FIG. 6 is a cross-sectional view showing an intermediate step in the second conventional technique.

FIG. 7 is a cross-sectional view showing a problem in the second conventional technique.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Flat heat-resistant metal foil 2 ... Heat-resistant metal foil with corrugated folds 3 ... Cylindrical core metal 4 ... Cylindrical honeycomb-shaped carrier 5 ... Race-track-shaped honeycomb-shaped carrier 6 ... Plate-shaped 7 ... race-track-shaped honeycomb-shaped carrier 8 ... irregular-shaped part 10-12 ... marker band 13, 14 ... edge 15, 16 ... upper and lower surfaces 17, 18 ... gap 20 ... cross-sectional shape is square round diamond-shaped metal core 21, 22 ... vertical of surfaces 23, 24 ... edge 25, 26 ... groove 27 ... small hole

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kiyotaka Matsuo 14 Iwatani, Shimowasukamachi, Nishio City, Aichi Prefecture Inside the Japan Automobile Parts Research Laboratory (72) Yukatsu Ozaki 14 Iwatani, Shimowasukamachi, Nishio City, Aichi Prefecture Stock Company (56) References JP-A-4-141239 (JP, A) JP-A-3-56146 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B01J 21/00-37/36 B01D 53/94 B21D 47/00 F01N 3/28

Claims (1)

(57) [Claims] What is the position of the cross-section in the direction of the central axis?
It is a round diamond shaped with evenly corners, major axis direction of the cross-sectional shape of the rhombus
Grooves are formed on the pair of edges in the direction of the central axis, respectively.
Using a cored bar that is located on one of the pair of edges of the cored bar
Insert one end of a flat heat-resistant metal foil into the formed groove
Attached and formed on the other of the pair of edges
Insert one end of a heat-resistant metal foil with a corrugated fold in the groove
The two metal foils around the core metal
As overlapping, it can wound around the core metal while applying a slight tension to their metallic foil attached to form a preform
After form, the from the center of the preform withdrawn the core metal, further said to be a flat shape preform
By pressing the short diameter direction of the cross-sectional shape, said intermediate
A method for producing a metal catalyst carrier for purifying exhaust gas, comprising molding a molded body into a honeycomb-shaped carrier having a racetrack cross section .