JP2010167468A - Method of manufacturing exhaust system part for automobile - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To manufacture with good productivity exhaust system parts for an automobile such as a catalyst converter having a connection part and a cone part by applying diameter reduction processing to a pipe end of a metal pipe storing an inner insertion member such as a catalyst carrier without generating wrinkles or cracks at a diameter reduction processing portion. <P>SOLUTION: Diameter reduction processing is carried out by reciprocating a processing roller in an axial direction while moving the processing roller in the radial direction of the metal pipe using the processing roller arranged at the outer circumference of the pipe end of the metal pipe storing the inner insertion member such as the catalyst carrier and relatively revolving around it. The exhaust system parts for automobile such as the catalyst converter are manufactured by forming the cone part and the connection part at both the pipe ends of the metal part. The diameter reduction processing is carried out by the processing roller while a wound body comprising a plate-like material having elasticity such as a spring steel plate is inserted to the inner side of the pipe end of the metal pipe to be processed as a metal core. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a catalytic converter, DPF (particulate material for a diesel vehicle), which contains an intercalation material such as a catalyst carrier, a filter and a silencer for treating exhaust gas discharged from an internal combustion engine such as an automobile engine. The present invention relates to a method of manufacturing an exhaust system part for automobiles such as a removal filter and a muffler.

Generally, automobile exhaust system parts such as catalytic converters, DPFs, and mufflers include a relatively large-diameter main body 1c, a relatively small-diameter connection 1a connected to an exhaust pipe, as shown in FIG. Consists of a container 1 constituted by a tapered cone part 1b having a small diameter for a while from the main body part 1c toward the connection part 1a, and an intercalating material such as a catalyst carrier, a filter and a silencer housed in the container. Has been. In the following, a description will be given taking as an example a catalytic converter containing a catalyst carrier as an intercalating material.
Conventionally, such a catalytic converter separately includes a cylindrical main body 1c in which a catalyst carrier is accommodated and a cone 1b having a connecting portion 1a formed by pressing a tube end of a cylindrical tube. The cone portions 1b were welded and joined to both ends of the main body portion 1c that was prepared and accommodated with the catalyst carrier.

However, from the viewpoint of simplifying the manufacturing process and improving durability, in recent years, after the catalyst carrier is accommodated in a cylindrical tube that is longer than the catalyst carrier, both ends of this cylindrical tube can be seen in FIG. The main body portion 1c, the cone portion 1b, and the connecting portion 1a are integrally formed by spinning.
Usually, in the catalytic converter, since the ratio of the diameter of the main body 1c and the connecting portion 1a is large, the amount of diameter reduction processing is large in the production of the catalytic converter container, and multi-pass spinning processing is performed. Yes.

For the purpose of suppressing wrinkles during processing, adjusting the thickness of the processed portion, or improving the dimensional accuracy of the processing inner and outer surfaces, for example, a cored bar is used as shown in FIG.
However, when machining with multiple passes, the core metal functions effectively only in the final pass, and hardly functions in the intermediate process. In addition, since a jig for holding the cored bar is required, the cored bar utilization technique for reducing the diameter of the pipe end is not always realistic.
Therefore, when performing a spinning process for reducing the diameter of the pipe end, molding is often performed by pressing a roller against a hollow pipe body without using a cored bar.

When performing the spinning process without using the cored bar, it is necessary to keep the original shape of the tube against the processing force of the roller in order to perform the process normally.
However, on the other hand, in such a tube processed product, it is required to reduce the thickness of the tube wall for the purpose of weight reduction and the like. If the tube wall becomes thinner than the diameter of the tube, the stiffness of the tube is insufficient. As a result, the shape accuracy of the tubular product is lowered. Also, if the tube to be processed is elastically bent or undulated when the spinning process is advanced, the roller collides with the deformed part, so that the spun part is wrinkled or deformed and spinning. Processing cannot be continued. That is, it becomes a defective product as seen in FIG.
Such a phenomenon in which the shape accuracy is lowered and the processing cannot be continued is more likely to occur as the tube body is thinner or as the processing speed is increased.

  Therefore, in order to suppress elastic deformation due to insufficient rigidity of the tube to be processed, to prevent the generation of wrinkles and cracks, and to improve the shape accuracy and processing speed, a processing roller is provided on the outer periphery of the rotating metal tube. When a spinning process is performed to reduce the diameter of the tube without pressing, a filler made of foamed resin is interposed inside the tube, and the tube is shrunk together with the filler by the processing roller. The diameter machining is proposed in Patent Document 1.

JP 2006-346695 A

In the method proposed in Patent Document 1, elastic deformation due to insufficient rigidity of the tube to be processed is suppressed, and generation of vibrations, wrinkles, cracks, and the like during molding is prevented, and shape accuracy and processing speed are reduced. A certain effect that improvement can be achieved is obtained.
However, when the pressure is applied to the foam resin filled inside the tube to be processed, the internal bubbles are crushed and deformed. Therefore, the repulsive force to the outside decreases, which is insufficient to supplement the rigidity of the tube to be processed. That is, when the amount of deformation is small, the filled foamed resin functions as it follows the deformation of the tube to be processed, but when the amount of deformation increases, the repulsive force corresponding to the amount of deformation is expected to be expressed. Can not.

In addition, the foamed resin filled inside the tube to be processed has a form in which the shape is deformed and filled into a shape along the tube end shape along with the diameter reduction processing of the tube end. For this reason, it is not easy to take out the foamed resin from the tube end opening, resulting in poor productivity. Moreover, it is impossible to reuse the foamed resin used as the filler. Therefore, the foamed resin utilization technique proposed in Patent Document 1 results in high costs.
The present invention has been devised in order to solve such problems, and a reduced diameter portion is formed at the tube end of a metal tubular body that accommodates an intercalation material such as a catalyst carrier, a filter, and a silencer. High-accuracy catalytic converter that suppresses elastic deformation due to insufficient rigidity of the tube to be processed, prevents wrinkles and cracks, improves shape accuracy and processing speed, and spins with high productivity. It aims to manufacture automobile exhaust system parts such as DPF and muffler at low cost.

In order to achieve the object, the method for manufacturing an exhaust system part for an automobile according to the present invention uses a processing roller that is arranged on the outer periphery of a pipe end of a metal pipe body that accommodates an insertion material and relatively revolves around the pipe end. A diameter reduction process is performed by reciprocating the processing roller in the radial direction while moving the processing roller in the radial direction of the metal tube body to form a cone portion and a connection portion at both ends of the metal tube body. When manufacturing an exhaust system part for an automobile, a diameter reduction process is performed by the processing roller in a state where a wound body made of a plate material having elasticity is inserted into a pipe end inside the pipe body made of metal as a core metal. It is characterized by giving.
A wound body using a spring steel plate as the plate material having elasticity is preferably used as the core metal.
Further, after accommodating an insertion material such as a catalyst carrier through a buffer material made of non-expandable fibers or the like inside the metal tube cut to a predetermined length, the end of the metal tube May be sequentially subjected to diameter reduction processing, or may be subjected to diameter reduction processing at one end of the metal tube body, and then the insertion material may be accommodated, and then the other end of the metal tube body may be subjected to diameter reduction processing. Good.

  In the manufacturing method of exhaust system parts for automobiles such as the catalytic converter of the present invention, the processing roller is pressed against the end portion of the metal pipe body that accommodates the insertion material such as the catalyst carrier to reduce the diameter, and the cone portion and When forming the connecting portion, a wound body made of a plate material having elasticity, such as a spring steel plate, is inserted as a cored bar. Since a wound body made of a spring steel plate or the like becomes a core metal having a variable diameter, it effectively functions as a core metal at all stages when performing diameter reduction processing with multiple passes. Moreover, even when the tube to be processed is a thin material, elastic deformation due to insufficient rigidity of the tube to be processed can be suppressed. In addition, it is possible to prevent vibrations, wrinkles, cracks and the like during molding, and improve the shape accuracy and processing speed. Furthermore, not only the removal of the cored bar after processing is easy, but also the winding body can be reused as the cored bar, so that the spinning process can be performed with high productivity. As a result, it is possible to manufacture automobile exhaust system parts such as highly accurate catalytic converters at low cost.

Schematic explaining the shape of a case such as an exhaust gas purification catalyst (converter) Schematic diagram explaining the spinning process The figure explaining the spinning processing method using a mandrel Diagram explaining problems that are likely to occur during spinning The figure explaining the spring steel plate winding body as a diameter variable core metal used by this invention Schematic diagram illustrating the spinning method of the present invention Figure summarizing the results of the examples

The present inventors have reexamined the problem of the technique of Patent Document 1 in which foam resin is used as a core metal when reducing the diameter of a pipe end of a metal pipe body that contains an insertion material such as a catalytic converter. Even when the diameter became smaller, a strong repulsive force was exerted on the outside, and a reusable core bar was repeatedly studied.
In the process, it has been found that a cylindrical wound body made of a plate material having elasticity such as a spring steel plate can be used as a core metal.
The details will be described below in the form of using a wound body made of a spring steel plate as a core metal, taking a catalytic converter as an example.

  In the method of manufacturing a catalytic converter according to the present invention, a wound body of a spring steel plate as a core metal used when spinning a pipe end of a metal pipe housing a catalyst carrier is usually as shown in FIG. The thin plate spring steel plate is a single tube or a plurality of layers. It is necessary that at least the inner plate end overlaps the inner wall of the outer plate. As seen in FIG. 5, it is preferable that the inner plate end is bent inward so that it can easily slide along the outer plate inner wall as the diameter decreases.

As the winding number of the spring steel plate increases, the repulsive force when the diameter is reduced increases. It is the same as a coil spring. Since the wound body is taken out against the increased repulsive force after the end of the diameter reduction process, a wound body having a large number of windings is not necessary. Depending on the characteristics of the spring steel plate, single or double winding is sufficient.
It is sufficient that the length of the cylinder of the wound body is slightly larger than the length of the reduced diameter portion to be applied.

Next, a method for forming the cone portion and the connecting portion by spinning the tube end of the metal tube body that houses the catalyst carrier using the wound body of the spring steel plate as described above will be described in detail.
FIG. 6 is a schematic view when the diameter of the pipe end is reduced by the manufacturing method of the present invention. First, as shown in FIG. 6 (a), a metal tube body containing a catalyst carrier is sandwiched by a chuck of a spinning device (not shown) via a cushioning material, and a spring is attached to the opposite tube end. Insert a rolled steel sheet. At this time, the wound body is inserted in a state where the diameter is reduced by a force resisting the repulsive force to the outside, but after removing the force resisting the repulsive force, the wound body of the spring steel plate is The diameter is increased until it matches the inner diameter of the tube to be processed, and the inner wall of the tube to be processed is held inside from the inside of the tube to be processed.

In this state, as shown in FIGS. 2 and 3, the diameter of the tube end is reduced by the processing roller (see FIG. 6B). At this time, as described above, the wound body of the spring steel plate is held in such a form that it is pressed against the inner wall of the pipe end by its repulsive force, so there is no need to separately hold and support the wound body of the spring steel plate. . The diameter of the wound body is reduced with the diameter reduction of the tube end, and the repulsive force increases with the processing.
In the spinning process, FIGS. 2 and 3 show a mode in which the metal tube is fixed and the processing roller is revolved, but a mode in which the metal tube is rotated may also be used.

The outward pressing force of the cored bar made of a rolled spring steel plate supplements the rigidity of the metal tube to be processed, but this pressing force increases as the diameter reduction process proceeds. Even if the metal tube is thin, elastic deformation caused by insufficient rigidity of the metal tube itself can be suppressed.
When reducing the diameter of the pipe end, cracks are likely to occur if there is no material restriction at the part to be processed. However, if a cored bar is applied, especially when a pressing force is applied as in the present invention, the cored bar is applied. The effect of restraining the material at the part to be processed becomes larger, and not only can cracks be prevented during processing, but also shape accuracy and processing speed can be improved.

After the processing is completed, the wound body of the spring steel plate as the core metal is taken out.
Along with the processing, the diameter of the wound body of the spring steel plate becomes thinner and the repulsive force to the outside becomes larger. For this reason, it is necessary to apply a force greater than the increased repulsive force to further reduce the diameter of the wound body. There is no difficulty in extracting, other than requiring a force greater than the increased repulsive force.
Since the wound body of the extracted spring steel plate is restored to the initial shape, it can be used again as a core for diameter reduction processing of the pipe body.

After the diameter reduction processing of one end of the metal tube containing the catalyst carrier is finished, the diameter reduction processing of the other end is similarly performed to complete the production of the catalytic converter.
In the above aspect, after accommodating the catalyst carrier through the buffer material inside the metal pipe body cut to a predetermined length, both ends of the metal pipe body are sequentially subjected to diameter reduction processing, The catalyst carrier may be accommodated after reducing the diameter of one end of the metal tube, and then the diameter of the other end of the metal tube may be reduced.
As the buffer material, it is preferable to use a non-expanded fiber that hardly expands due to heat, such as alumina fiber, in the form of a mat, and wind this mat around the outer periphery of the catalyst carrier and press-fit it into the metal tube.

A ferritic stainless steel ERW pipe having an outer diameter of 150 mm was used as a test metal pipe for containing the catalyst carrier. At this time, three types of steel pipes having a material plate thickness of 0.8 mm, 1.05 mm and 1.2 mm were used.
A single winding body having a diameter of 150 mm and a width of 100 mm made of a cold rolled steel plate for spring (JISG4802, S55C-CSPB) having a thickness of 0.5 mm was used as the core metal.
The spring steel plate wound body is inserted into the pipe ends of the three types of test steel pipes in which a steel pipe that is regarded as a catalyst carrier is press-fitted in a state where a mat made of alumina fiber is wound around the outer periphery of the steel pipe, and the processing roller is rotated at 600 rpm. The diameter of the steel pipe was reduced at a reduction ratio of 60% until the pipe end outer diameter became 90 mm with a feed speed of 6000 mm / min and a pass number of 11 while rotating at a steel tube.

When the thickness of the raw steel pipe was 1.2 mm, it was possible to reduce the diameter to 60%, whether using a cored bar or not.
On the other hand, when the plate thickness of the material steel pipe is 1.05 mm, when the spring steel plate wound body is a core metal according to the present invention, the diameter reduction processing can be performed with a reduction ratio of up to 60%. Without the use of a rotating body, the diameter reduction processing with a diameter reduction ratio of 60% could not be performed (see FIG. 7).

In addition, when the thickness of the raw steel pipe was 0.8 mm, wrinkles were generated and the processing could not be continued before the diameter was reduced to 60% even when the core metal was used or not used. As shown in FIG. 7, wrinkles occurred at the initial stage of machining when no cored bar was used, whereas wrinkles occurred at the later stage of machining when the cored bar was used.
The results are summarized in Table 1. The usefulness of the rolled spring steel plate as the core metal can be understood.

As described above, the pipe body to be processed is subjected to the spinning process in a state in which the wound body of the spring steel plate is inserted as the core metal inside the pipe end of the metal pipe body to be processed that accommodates the insertion material such as the catalyst carrier. The method of manufacturing an exhaust system part for automobiles that prevents the occurrence of wrinkles and cracks has been described by taking a catalytic converter as an example, but the present invention is not limited to the manufacturing method of a catalytic converter, and is used as an internal insertion material. It can be used as a method of manufacturing exhaust system parts such as DPFs and mufflers that contain filters and silencers.
In addition, as for the wound body made of a plate-like material having elasticity as a core metal, anything other than a spring steel plate can be used as long as it can suppress elastic deformation due to insufficient rigidity of the metal tube to be processed during spinning. But it goes without saying.

Claims (2)

  Using a processing roller that is disposed on the outer periphery of the pipe end of the metal tube that accommodates the insertion material and relatively revolves around the tube end, and moves the processing roller in the radial direction of the metal tube in the axial direction. The pipe end of the metal pipe to be processed is manufactured when an exhaust system part for an automobile is manufactured by forming a cone part and a connection part at both pipe ends of the metal pipe body by reciprocating the diameter. A method of manufacturing an exhaust system part for an automobile, wherein a diameter reduction process is performed by the processing roller in a state where a wound body made of a plate material having elasticity is inserted as a cored bar.   The method of manufacturing an exhaust system part for an automobile according to claim 1, wherein the wound body is made of a spring steel plate.