Layered sheet metal with rolled-on solder and process for manufacturing honeycombed body therefrom

Metal sheet with layered structure and method for manufacturing honeycomb body using the metal sheet

The present invention relates to a method for manufacturing a honeycomb body. According to this method, thin metal plates are stacked and/or wound, and they at least partially have a structure for forming channels through which fluid can flow. In particular, the present invention also relates to the use of layered metal sheets for manufacturing such honeycomb bodies, which have an aluminum layer on the outside, and the honeycomb bodies are mainly used in exhaust gas purification equipment of automobiles.

From W089/07488, for example, honeycomb bodies of the aforementioned type are known. The honeycomb body is used as a carrier for a catalyst, which promotes the conversion of exhaust gas, especially exhaust gas components of internal combustion engines, into compounds that do not pollute the environment. The honeycomb body is subjected to high mechanical and thermal loads. In addition to mechanical and thermal loads, these metal sheets are also exposed to corrosive environments. Therefore, it is desirable to use metal sheets with good corrosion resistance to manufacture honeycomb bodies.

It is known from US5366139 to manufacture honeycomb bodies using thin metal sheets first composed of a layered material. This metal sheet has at least one layer made of chromium-containing steel and at least one layer mainly containing aluminum. Such layered metal sheets are subjected to heat treatment, during which the metal sheets are basically homogenized. The so-called homogenization of the metal sheet refers to the diffusion of aluminum in the steel, so basically a single-layer sheet made of aluminum-containing steel is formed.

From DE-OS 2924592, various methods for applying brazing filler metals to such metal sheets or honeycomb bodies made from the metal sheets are known. All these methods require high costs and additional processes.

The object of the present invention is to provide a method of manufacturing a honeycomb body, which has as few steps as possible, but nevertheless can obtain a honeycomb body that is corrosion-resistant and can withstand mechanical loads. In addition, a metal sheet made of composite materials suitable for manufacturing such honeycombs should be created.

In order to achieve the above object, according to the present invention, a method for manufacturing a honeycomb body is provided. According to this method, the metal sheet layers are stacked and/or wound to form contact points, wherein the metal sheet layers at least partially have a structure for It forms a channel through which fluid can flow, and at least a part of the metal sheet layer is first composed of a layered material made by rolling together, this material has at least one layer made of chromium-containing steel and at least one layer Layers mainly containing aluminum, these layers are basically homogenized in the later heat treatment process, and are characterized by: on at least one outer layer of the layered material, solid solder is rolled during the material manufacturing process, so In the later heat treatment, at least at the contact point between the metal sheet layers and/or at the contact point between them and an outer sleeve, a brazing connection is created. According to the present invention, the brazing material is only placed on the part during rolling. Part of the layer material on the composite surface; roll the solder on the two outer layers; the solder is a nickel-based solder; the solder contains between 0.5 and 8% boron; the metal sheet layer has a The width corresponding to the axial length of the honeycomb body, as well as at least one preferably at the edge area of the end face in the honeycomb body, there is a strip of brazing filler metal, which has a width of 2 to 10 mm; heat treatment first It is carried out in a temperature range in which aluminum diffuses into the steel, but the brazing material has not melted, and the temperature is increased to the brazing temperature after the layered material is basically homogenized; brazing; The material is placed on at least one edge area as a solder bar.

To achieve the above object, according to the present invention, there is also provided a metal sheet composed of layered materials made by rolling together. This material has at least one layer made of chromium-containing steel and at least one layer mainly containing aluminum. The layer is characterized in that the brazing filler metal is rolled on at least one outer layer of the layered material.

According to the present invention, the solder is only placed on a part of the composite surface; the solder is rolled on the two outer layers of the layered material; the solder is a nickel-based solder; the solder contains between 0.5 and 8%; The layered material is on at least one edge area of a composite surface formed by rolling on the solder, there is a strip of solder, which has a width of 2 to 10 mm; the solder has a thickness d less than 10 μ ; Roll the brazing filler metal in a manner that is substantially free of protrusions on the formed composite surface; the layered material has a strip-shaped brazing filler metal on two edge regions that are opposite to each other.

When manufacturing the metal sheet according to the present invention, while the supporting metal layers are rolled together, the brazing material necessary for subsequent external connections is also rolled. Therefore, some troublesome processes are eliminated, which must be used for later coating and fixing of the solder. The honeycomb body also only needs to be wound or laminated, and then the brazing process can be performed. It is much simpler to add brazing filler metal in a rolling process in which different layers are rolled together anyway, than adding brazing filler metal to a thin metal plate or honeycomb body in the future.

Various types of soldering devices and layouts for soldering honeycomb bodies are known from the prior art. By arranging the brazing material in strips on the surface of the thin metal plate, almost all the desired configurations of the brazed parts in the future can be obtained. The width of the strip is preferably 2 to 10 mm, especially about 5 mm. Depending on the type of structure, the brazing filler metal strips can be arranged on one or both sides and at one or both edges. In particular, it is also possible to add a solder layer on only half of the metal sheet layer of the honeycomb body, mainly the flat metal sheet layer, and the remaining metal sheets are made without solder.

When nickel-based brazing filler metals are particularly advantageously used as brazing filler rods, they can be placed in a common rolling process at the same time as the aluminum layer is rolled. In this case, the harder nickel filler is pressed into the aluminum layer. In this way, even though it is strip-shaped, it can form a surface with almost no bulge. It is also possible to use solder film or solder wire or spread solder powder. When using solder wire, according to the selected solder, roll type, and process control method, the solder wire is only slightly flattened or deformed into a wide strip when it is rolled.

Traditional, for example, the coated brazing material layer with a local thickness greater than 10μ, under certain conditions, causes the mechanical instability of the honeycomb body, because the brazing material flows during the brazing process, which makes the honeycomb body in the clamped state. It may be slack. In contrast, in the case of a rolled metal sheet, the thickness of the brazing filler metal only needs to be about 0.5 to 3 μ, for example.

Due to the reduction of the number of processes, the present invention can provide a layered and brazing filler-added cheap metal sheet product, especially a cheap wide metal sheet product. The sheet metal strips required to make the honeycomb body may have to be cut to different widths from the above-mentioned products in some cases. Therefore, it is necessary to pay attention to the proper spacing of the solder strips when rolling the solder to avoid unnecessary scraps.

Through the designed method and the use of a layered material, this material has at least one layer made of chromium-containing steel and at least one layer mainly containing aluminum. The solder can be a nickel-based solder. The maximum brazing temperature in this case is between 1100 and 1150°C. The brazing filler metal preferably contains between 0.5 to 8% boron, especially 3 to 6% boron. The boron in the solder is used as an accelerating diffusion agent, so with an equivalent brazing connection, the brazing process can be shortened in time. The result of shortening the brazing process is to pass the brazing furnace at a higher operating speed. Since the homogenized metal sheet can reach a high aluminum content, it can compensate for the harmful effect of boron content on the corrosion resistance of the layered material.

It is particularly advantageous that the heat treatment is first performed in a temperature range in which the brazing filler metal has not yet melted. After the layered metal sheets are substantially homogenized, the temperature is raised to the melting point of the solder. The advantage of this method is to ensure that a substantial homogenization of the layered metal sheets is achieved and thus a strong brazed connection is made.

The other advantages and features of the method according to the invention will be explained in detail below with the aid of the drawings. It shows: Figure 1 is a schematic cross-section of a honeycomb according to the prior art; Figure 2 is composed of a layered material and a metal sheet with a layer of brazing material; Figure 3 is composed of a layered material and added with a plurality of pressed brazing materials A schematic perspective view of the metal sheet of the strip; and Figure 4 is a metal sheet composed of three layers of layered materials, one of which is a layer of brazing material.

Figure 1 shows a honeycomb body 1. The honeycomb body 1 is composed of laminated and wound metal sheet layers resistant to high temperature corrosion. This honeycomb body 1 is alternately made of flat and corrugated metal sheet layers 2, 3. The flat and corrugated sheet layers 2, 3 have a layered structure. However, it is also possible to manufacture a honeycomb body partly from homogeneous metal sheet layers and partly from layered materials. In the case of layered materials, as shown in Figure 2, a layer 5 and 6 are applied on both sides of an inner layer 4, which are mainly composed of aluminum. The layered material shown in FIG. 2, as also shown in FIGS. 3 and 4, is in the form before the heat treatment.

The honeycomb body 1 has a structure for forming a channel 7 through which a fluid can flow. Its metal sheet layer is packed into an outer sleeve 8. The outer sleeve 8 preferably has a layer mainly composed of aluminum in at least a partial area of its inner side. However, it is also possible to connect the metal sheet layer separately or in addition by means of general soldering techniques. It is also possible to manufacture the honeycomb body without using a prefabricated outer sleeve, for example by winding a flat metal sheet layer around a structure made of stacked and wound metal sheets and brazing it to itself.

Figures 2, 3 and 4 show different embodiments of the metal sheet according to the invention. However, these implementation forms are only examples. According to the desired location, number and size of the brazing connection, a layer of fiber material, brazing material or other styles of brazing material can be rolled on one or both sides of the outer layered material. The brazing filler metal can also be rolled into the layered material. This is best if, for example, the solder wire should be partially flattened first. A layer made of a material softer than the solder can then be pressed, so that the solder penetrates through the layer until it is on the surface of the layered material. Different from the implementation form of Figures 2 and 3, only the solder 9 rolled on the aluminum layer 5, 6 is shown; 9a, 9b, 9c, and the solder 9; 9a, 9b, 9c can also be rolled on the aluminum layer 5, 6 The outer surface of the metal layer made of another material, such as the one shown in FIG. 4, is rolled on the outer chromium-containing steel layer.

As shown in Fig. 3, it has been repeatedly pursued to arrange the brazing filler metal only in the form of strips 9a, 9b, 9c in the partial area of the composite surface formed by rolling. This can be done on one or both sides of the metal sheet. The strips 9a, 9c are preferably located at at least one edge area of the metal sheet, which will later form a brazed connection on the end face in the honeycomb body to be manufactured, because the metal sheet has an axis with the honeycomb body 1 to be manufactured later. To the same width as the length b. Unlike the location-independent thickness d in the embodiment shown in FIGS. 2 and 3 with one solder layer or some solder strips, the solder may also have a location-dependent thickness. For example, this solution can be formed by rolling solder wire and solder powder.

The method according to the present invention can be used to manufacture a honeycomb body composed entirely or partly of a layered metal sheet layer, and obtain a honeycomb body that can withstand mechanical loads and high temperature corrosion at a low price. This honeycomb body is particularly suitable It is used as an exhaust catalyst for automobiles.