JPH04150949A - Preparation of metal carrier - Google Patents

Abstract

PURPOSE:To rationalize the flow of exhaust gas by a method wherein a corrugated foil prepared so as to change the height of the corrugations of the corrugated foil corresponding to the specific layer of a honeycomb body and a flat foil are alternately superposed one upon another and wound in a vortex shape to prepare a honeycomb body wherein the cell density of a specific range of a layer is different from that of other layer. CONSTITUTION:A flat foil 2 and a corrugated foil 1 are alternately superposed one upon another and wound in a vortex shape to prepare a metal carrier having a honeycomb body 2. At this time, the corrugated foil 1 prepared so as to change the height of the corrugations of the corrugated foil 1 corresponding to a specific range of the layer of the honeycomb body 8 and the flat foil 2 are alternately superposed one upon another to be wound in a vortex shape. By this method, the honeycomb body wherein the cell density of the specific range of the layer C is different from that of other layer is formed. As a result, the flow of the exhaust gas passing through the honeycomb body becomes rational and the catalyst supported on the honeycomb body acts uniformly and efficiently.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a metal carrier for a catalyst having a circular, racetrack or elliptical cross section, which is installed in the exhaust gas system of an automobile engine or the like to purify the exhaust gas. This relates to a manufacturing method.

(Prior art) Conventionally, a support structure in which a precious metal catalyst such as platinum is supported on a honeycomb made of ceramics such as cordiolite has been used to purify exhaust gas from automobile engines, etc., and this is still the mainstream. The honeycomb carrier made of aluminum has relatively high exhaust resistance, and in order to prevent the honeycomb body from breaking, a stainless steel mesh is inserted as a buffer between the outer cylinder supporting the honeycomb body, but this is limited by its heat resistance. Metal supports that do not have these drawbacks have recently attracted attention and have begun to be put into practical use.

This metal carrier is generally made by winding or laminating a heat-resistant stainless steel flat plate having a thickness of about 50 mm and a corrugated plate to form a cylindrical honeycomb body.
This is inserted into a heat-resistant stainless steel outer cylinder tube, and then the flat plate/corrugated plate and the honeycomb body/outer cylinder are joined together by brazing, resistance welding, laser welding, electron beam welding, etc.

This metal carrier (1) efficiently purifies exhaust gas;
The supported catalyst must act as homogeneously as possible, so that the flow of exhaust gas must flow uniformly into the metal support. In addition, (2) in order to mount it on an automobile, it is necessary to have a cross section of various shapes, such as a circle, a racetrack shape, or an oval shape, depending on the place of use. The present invention relates to a method for manufacturing a metal carrier corresponding to the above (1) and (2). First, regarding the inflow of exhaust gas into the metal carrier (1), the exhaust gas has a velocity distribution in the radial direction due to fluid resistance with the pipe wall. That is, the speed tends to be high near the center of the carrier, and slow near the outer peripheral layer.

As a result, the catalyst near the center performs more purifying action,
It is unreasonable to say that the purification effect of the catalyst near the outer layer is small. In particular, when the catalyst deteriorates due to poisoning, although the catalyst near the outer layer is good, the catalytic action near the center loses and the metal carrier must be replaced, which is uneconomical.

In order to eliminate this unreasonableness, it is necessary to make the exhaust gas flow uniformly into the metal carrier, but in conventional metal carriers, a corrugated plate of a certain height is wound spirally around a flat plate. Since the cell density at each section of the cross section is the same, the velocity distribution of the exhaust gas flows into the metal carrier without being improved, resulting in the above problem.

In order to solve this problem, a guide plate for rectification is sometimes installed on the inlet side of the metal carrier, but this increases pressure loss, which is unreasonable, and its shape, dimensions, installation method, and durability may be affected. There are problems and impractical aspects.

Next, regarding the cross section of the metal carrier (2), if it is a circle, it is sufficient to wrap a flat plate and a corrugated plate around the axis, but if it is an oval, the height of the corrugated plate to be wound is the short axis. It must change continuously in the major axis and its transition areas. In addition, in the case of an oval, the flow of exhaust gas is difficult in the vicinity of the long diameter part due to its shape, and it is easy to flow in the vicinity of the short diameter part, which causes the problem that the purification effect of the catalyst is not uniform as described above. That is, in the case of an oval type carrier, the problem of forming the shape and the problem of making the exhaust gas flow uniform coexist, and it is necessary to solve both problems at the same time.

In order to obtain a metal carrier with an oval cross section that does not have such problems, we not only overlap and wind a flat plate and a corrugated plate, but also
For example, Japanese Patent Publication No. 57-55888 and Utility Model Application Publication No. 62-1
A method as disclosed in Japanese Patent No. 80821 is known.

In other words, in the former method, the oval-shaped outer shell is divided into halves, and half-shell bodies (outer cylinders) are placed above and below, and a cylindrical wound honeycomb body with a cylindrical space in the center is inserted into these half-shell bodies (outer cylinders). However, it is proposed that an oval-shaped honeycomb carrier is made by pressing the half-shells together and joining them from above and below. However, according to this method, the original circular honeycomb body is reduced (shorter diameter side) and expanded (longer diameter side) in the axial direction, but the amount of squeezing of the corrugated plate at each part of the reduced part is not constant. The height of the corrugations changes without any change and the cell density is disturbed, and furthermore, the height of the corrugated plate cannot be increased at the enlarged portion, that is, on the long diameter side, so it is unreasonable to be unable to reduce the cell density and make the exhaust gas flow easily.

The latter (Sho 62-180Et21) is formed by laminating a flat plate and a corrugated plate to form a honeycomb body with an oval cross section. At this time, the shell and outer cylinder are placed at a position that roughly bisects the short diameter direction of the shell. The carrier structure is made by arranging deformation prevention plates with the same expansion coefficient and welding them to a shell divided into two parts, but because the honeycomb body of the laminated structure is housed in the divided shell body and the deformation prevention plates are provided, the structure is different. There is a problem that it becomes complicated and productivity is not good.

(Problems to be Solved by the Invention) As mentioned above, none of the prior art methods has been found to streamline the flow of exhaust gas and produce a metal carrier having a circular, racetrack, or oval cross section. .

In view of the current situation, the present invention intentionally changes the height of the corrugated plate before winding, so that the flow of exhaust gas is rational and the m1 plane is circular, racetrack-shaped, or oval. It is an object of the present invention to provide a method for manufacturing a metal carrier.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides the following features: (1) When manufacturing a metal carrier having a honeycomb body by alternately stacking flat foils and corrugated foils and winding them in a spiral shape, By alternately stacking corrugated foil produced by changing the wave height of the corrugated foil and flat foil corresponding to the layers in a specific range of the honeycomb body and winding them in a spiral, the layers in a specific range can be formed. A method for producing a metal carrier characterized by forming a honeycomb body having a different cell density.

(2) The cross-section of the honeycomb body is created by making the wave height of the corrugated foil continuously higher in the circumferential direction from the shorter diameter side to the longer diameter side, and changing the wave height continuously lower from the longer diameter side to the shorter diameter side. The method for producing a metal carrier as described in the preceding item, characterized in that the metal carrier has an oval shape.

(3) Corrugated foil and flat foil manufactured by continuously changing the wave height of the corrugated foil that corresponds to a specific range of layers by rough rolling the corrugated foil that has been processed to a certain wave height. The method for manufacturing a metal carrier according to item (1) above, wherein a honeycomb body is formed by overlapping and winding the layers in a specific range with different cell densities.

(4) Corrugated foil processed to a constant wave height is further rolled down to continuously and periodically change the wave height of the corrugated foil corresponding to a specific range of layers. The method for manufacturing a metal carrier according to item (2) above, characterized in that an oval-shaped carrier is produced by overlapping and winding the foils.

The main points are as follows.

The present invention will be explained in detail below.

The metal carrier constituting the present invention is stainless steel whose main component is Cr-AN, and Ni, Cu, etc. may be added as necessary, but the composition has excellent corrosion resistance and heat resistance. That is, the flat plates and corrugated plates forming the honeycomb body are manufactured from the above-mentioned steel having approximately the same composition and have a thickness of 30 to 11 mm.
00t is preferably a foil of around 5°.

The present invention uses such foil plates (bands), one of which is a flat plate, and the other is a flat plate with corrugated edges, which are superimposed and wound in a spiral shape, so that the cross section is as shown in Figure 1. The honeycomb carrier is formed into a circular shape as shown, an oval shape as shown in FIG. 5, or a racetrack shape.

In manufacturing a honeycomb body, first, as shown in FIG. 2, a flat plate is fed between rolls 3 and 4, which rotate and mesh with each other, and the corrugations are processed. The amount of engagement between the rolls 3 and 4 is determined by the rolling reduction (not shown).
For example, corrugation can be adjusted by moving the roll 3 up and down and changing the relative position with respect to the roll 4 using the adjusting device. In other words, the wave height h of the processed corrugated sheet 1 is
The corrugation increases as the amount of engagement between the rolls 3 and 4 increases, and decreases as the amount of engagement decreases.

It is natural that the cell density increases as the wave height h of the corrugated plate 1 decreases because the number of cells per unit area increases, and conversely, as the wave height h increases, the cell density decreases.

First, a method for manufacturing a metal carrier having a circular cross section using such a corrugated plate 1 will be described.

As shown in FIG. 3, exhaust gas flows into the metal carrier 5 from the direction of arrow A, and the velocity distribution at this time is as shown by curve B, where the velocity is high near the center C and near the outer layer. is slower. For this reason, as shown in Figure 1, the cell density near the center C is increased to make it difficult for the exhaust gas to flow.
On the contrary, the cell density near the outer layer is lowered to make it easier for exhaust gas to flow, thereby allowing the exhaust gas to flow over the entire surface of the carrier.

For this purpose, when processing the corrugated sheet 1 in the vicinity of the center C as shown in FIG. When machining, corrugation increases the amount of biting of the machining rolls 3 and 4.

In addition, at the position where the height h of the corrugation is changed, a detector (not shown) detects the amount of rotation of the roll 3 or 4, and the corrugation height of the corrugated plate 1 is changed as shown in FIG.

Further, the amount of biting is calculated and determined in advance from the cell density to be provided near the center C and near the outer layer.

By overlapping the corrugated plate 1 processed in this way with the flat plate 2 and winding it around the central axis, the C
A honeycomb body 8 having a high cell density near the outer layer and a low cell density near the outer layer and having a circular cross section is formed.

Next, a method of manufacturing a honeycomb body 6 having an elliptical cross section as shown in FIG. 5 will be described.

In the case of an elliptical shape, the wave height h increases continuously in the circumferential direction from the shorter diameter side to the longer diameter side. In the method for manufacturing the corrugated sheet 1 for this purpose, in the case of the corrugated sheet 1 on the shorter diameter side, the biting amount is shallower, and the biting amount is continuously increased toward the longer diameter side. In this way, corrugation can be made by stacking the processed corrugated plate 1 on the flat plate 2 and winding it around one axis or around a straight axis, as shown in Figure 6, to create a honeycomb with an arbitrary elliptical cross section. body 6 can be manufactured.

Next, a method for manufacturing a honeycomb body in which the cell density is adjusted as described above by rolling down the corrugated plate 1 having a constant wave height will be described.

As shown in FIGS. 7 and 8, in the honeycomb body 6 manufacturing line, the corrugated sheet 1 and the flat sheet 2, which are supplied separately, are
Before overlapping and winding to form a honeycomb body, corrugated sheet 1
is passed between rolling rolls 7 and 8, and the gap between both rolls 7 and 8 is adjusted to apply pressure to the corrugated sheet 1 and control the wave height.

That is, as shown in FIG. 8, when the corrugated sheet 1 is rolled down by the rolls, one or both of the rolls 7 and 8 is moved up and down to adjust the roll gap between the two rolls 7 and 8. ' Short axis end 9 in the short axis direction x-x'.
Reduction of the portion corresponding to the 9' portion (that is, this short diameter end 9.
9' exists in the vertical direction for each winding of the flat plate 2) is large, that is, the wave height is rolled down and the wave height h2 is small. 1
As the part corresponding to the 0' part is approached, the rolling reduction is reduced, and the roll gap is automatically controlled to be equal to or higher than the original wave height h1 before rolling.

In this way, in the present invention, since the wave height is controlled by applying pressure to the corrugated sheet 1 before winding, the corrugated sheet and the flat sheet are successively overlapped and wound to form an oval honeycomb body. At the time, the corrugated plate 1 at the short diameter end 9.9' of each winding
The wave height h2 is small, and the major diameter end 10.10' is smaller than this part.
Since the corrugated sheet is processed so that it returns to the original wave height h1 which gradually increases toward the part, the corrugated sheet at the short diameter end 9.9' -
of a flat plate.

The lamination thickness is the thinnest and becomes thicker as the distance from it increases, resulting in an oval honeycomb body.

The wave height h2 of the short diameter side corrugated plate 1 can be expressed as (major axis - short axis)/2/total number of turns - thickness of the flat plate. The roll gap is successively adjusted from large to small, small to large, from the long diameter side to the short diameter side and in the opposite direction, and the short diameter portion is continuously adjusted to be equal to or higher than the wave height. Each distance from the major axis end to the minor axis end is determined by designing the target shape in advance.
Find it by calculation. For example, an oval honeycomb body with a core length of 150 mm and a core width of 90 mm has a thickness of 50 tons! n(
0.05mm) flat plate and wave height (h 1) 1.2ta
In order to manufacture a corrugated sheet of m in diameter by winding it 120 times, the wave height h2 on the shorter diameter side needs to be 70011n (0.7mm), and the rolling reduction ratio at this time is (1,2-0,7)/ 1.2xlo
It becomes o-41.7 (%).

The honeycomb body 6' constructed by winding flat plates and corrugated plates in this manner is inserted into an oval outer cylinder 11 as shown in FIG. At this time, the outer diameter of the honeycomb body 6' is set slightly larger than the inner diameter of the outer cylinder 11, and the oval shape of the honeycomb body is shaped by inserting the honeycomb body so that it receives compressive force. It becomes possible to improve the joining accuracy of corrugated plates. Outer cylinder 1 of honeycomb body 6'
The insertion into the outer tube 1 is not limited to this, and there is no problem in compressing and shaping the outer cylinder by external force after insertion. After inserting the honeycomb body into the outer cylinder, a joining process such as brazing is performed, and the carrier becomes a product.

If it is not possible to increase the amount of reduction of the corrugated sheet as described above due to cell density, it is preferable to wind the corrugated sheet and flat sheet that have been rolled down by an allowable amount around a flat core.

That is, if the minimum height h2 of the corrugated plate in the above embodiment is 1 m, the total number of windings will be approximately 43 times, and the winding thickness on the major diameter side will be 1.25X2X43-107.5, which is 150-
107.5 = 42.5mra shortfall. Therefore width 4
By inserting a 2.5III flat core and winding a corrugated plate and a flat plate with adjusted wave height around it, the desired major diameter is 150 + nm.
It is possible to manufacture an oval carrier with a short diameter of 90 m.

(Effects of the Invention) As explained above, according to the present invention, it is possible to manufacture an oval type carrier in which the catalyst supported on the honeycomb body acts uniformly and also allows the catalyst to act efficiently.

[Brief explanation of the drawing]

Figure 1 is an end front view of a carrier with a circular cross section and a reasonable cell density. Figure 2 is a conceptual diagram showing how corrugated sheets are produced by rolls. Figure 3 is a conventional cross-sectional view of a carrier with a circular cross section. A diagram showing the inflow of exhaust gas into a certain carrier. Figure 4 is an external view of the corrugated plate used in the carrier in Figure 1. Figure 5 is an end view of an oval type carrier. Figure 6 is an illustration of an oval type carrier. Manufacturing situation diagram, Figure 7 is an explanatory diagram of the situation in which an oval type carrier is manufactured while controlling the wave height of the corrugated plate, Figure 8 is an explanatory diagram of the situation in which the wave height of the corrugated plate is reduced, and Figure 9 is a diagram of the carrier. FIG. 1... Corrugated plate h... Wave height 5... Metal carrier 7.8... Rolling down rolls 10, 10'... Long diameter end 2... Flat plate 3.4... Corrugated Roll 6...honeycomb body 9.9'...minor diameter end 11...outer cylinder

Claims (4)

[Claims] (1) When manufacturing a metal carrier having a honeycomb body by stacking flat foil and corrugated foil alternately and winding them in a spiral, the wave height of the corrugated foil corresponding to a specific range of layers of the honeycomb body is changed. Production of a metal carrier characterized by forming a honeycomb body in which the cell density of the layers in a specific range differs from others by alternately stacking corrugated foil and flat foil and winding them in a spiral shape. Method. (2) The wave height of the corrugated foil is continuously increased in the circumferential direction from the short axis side to the long axis side, and the wave height is continuously changed from the long axis side to the short axis side to create a cross section of the honeycomb body. 2. The method of manufacturing a metal carrier according to claim 1, wherein the metal carrier has an oval shape. (3) Corrugated foil processed to a constant wave height is further rolled down to continuously change the wave height of the corrugated foil corresponding to a specific range of layers, and the corrugated foil and flat foil are stacked. 2. The method for manufacturing a metal carrier according to claim 1, wherein a honeycomb body is formed by winding the metal carrier in such a manner that a specific range of layers has a different cell density. (4) Corrugated foil processed to a constant wave height is further rolled down to continuously and periodically change the wave height of the corrugated foil corresponding to a specific range of layers. 3. The method for producing a metal carrier according to claim 2, wherein the oval carrier is produced by overlapping and winding the foils.