JP2007136498A - Method for manufacturing catalytic converter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a catalytic converter by which working time is shortened, fraction defective is reduced and also a cone part is easily formed even when it has high diameter reduction rate. <P>SOLUTION: This method of manufacturing the catalytic converter 10, 20 in the inside of a pipe stock 1 of which a catalyst carrier 3 for cleaning exhaust gas is housed and in which the cone part 1d whose diameter is gradually or step-by-step reduced toward the end part 1b of the tube stock 1 from the housing part 1c of the catalyst carrier 3 is integrally formed includes: a first stage where the diameter of the tip part 1a of the tube stock 1 in which the catalyst carrier 3 is housed is reduced by a tube diameter reducing device provided with a tube diameter reduction die 2 for pressing and forming the outer peripheral surface of the tube stock 1 from the side of the outside diameter; and a second stage where the diameter of the tip part 1a the diameter of which is reduced in the first stage is further reduced and also the cone part 1d is formed by reducing the diameter of the tube stock 1 simultaneously or successively toward the housing part 1c from the tip part 1a. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a catalytic converter, and more particularly, to a method for manufacturing a catalytic converter in which a cone portion whose diameter is gradually or stepwise reduced from an accommodating portion of a catalyst carrier toward an end portion of a raw tube.

  A catalytic converter is an exhaust gas purification device for redox purification of harmful substances in automobile exhaust gas by the action of a catalyst. For example, a catalyst carrier for exhaust gas purification is accommodated inside an elementary pipe, and a housing part for the catalyst carrier A cone part that is gradually or stepwise reduced in diameter toward the end of the raw tube has been developed.

Conventionally, a spinning method and a shrink method have been adopted as a method of manufacturing such a catalytic converter. The spinning method is a method of integrally forming a cone part by reducing the diameter of a pipe containing a catalyst carrier by a spinning roller (for example, see Patent Documents 1 and 2). This is a construction method in which a cone tube is integrally molded by reducing the diameter of a raw tube containing a catalyst carrier by a reduction pipe device having a reduction pipe mold that presses the outer peripheral surface from the outer diameter side (for example, Patent Document 3, 4).
JP-A-2005-930 JP 2001-107725 A JP 2004-358494 A JP 2002-97944 A

  However, when the catalytic converter as described above is manufactured by the spinning method or the conventional shrink method, there are the following problems.

  In the spinning method, the raw pipe is gradually drawn and formed by a spinning roller, and the amount of processing per process is small. Therefore, when forming a cone part with a high diameter reduction rate, it is necessary to repeat several steps sequentially. In addition, a finishing cut is also required after spinning. Therefore, when a cone portion having a high diameter reduction rate is formed by the spinning method, the processing time becomes long. Furthermore, in such a case, a core misalignment is likely to occur when the element tube is contracted, and the tip portion of the element tube is likely to be thick, so the defect rate is high.

  On the other hand, in the conventional shrink construction method, the cone portion is formed by reducing the diameter of the raw tube containing the catalyst carrier in one step by the contraction device. Therefore, when trying to mold a cone part having a high diameter reduction rate by a conventional shrink construction method, the catalyst carrier is distorted and easily broken when the base pipe is reduced in diameter. Therefore, in the conventional shrink method, it is difficult to mold a cone portion having a high diameter reduction rate.

  The present invention has been made in view of the above problems, and its object is to reduce the processing time, reduce the defect rate, and easily mold even a cone portion with a high diameter reduction rate. Another object of the present invention is to provide a method of manufacturing a catalytic converter that can be used.

  In order to solve the above problems, the present invention has improved the conventional shrink method. That is, according to the present invention, a catalyst carrier for exhaust gas purification is accommodated inside a raw tube, and a cone portion that gradually or stepwise decreases in diameter from the catalyst carrier containing portion toward the end of the raw tube. A method for producing a catalytic converter that is integrally molded, wherein the distal end of the raw tube in which the catalyst carrier is accommodated by a reduced tube device that includes a reduced tube mold that presses the outer peripheral surface of the raw tube from the outer diameter side The first step of reducing the diameter of the part and the diameter of the tip portion reduced in the diameter of the first step are further reduced by the tube-reducing device, and the raw tube is simultaneously or gradually moved from the tip portion toward the housing portion And a second step of forming the cone part by sequentially reducing the diameter.

  The manufacturing method of the catalytic converter having such a configuration is configured such that the cone portion is formed in the second step after the diameter of the tip portion of the raw pipe is reduced in the first step. Therefore, as compared with the case where the cone part is formed by shrinking the raw pipe in one step as in the conventional shrink construction method, the catalyst carrier is less likely to be distorted, and even a cone part with a high diameter reduction rate is easy. Can be molded. Further, in the manufacturing method of the catalytic converter having such a configuration, the machining amount is large and the finishing cut is not required as compared with the spinning method, so that the machining time can be shortened. Furthermore, in the manufacturing method of the catalytic converter having such a configuration, since the outer peripheral surface of the raw tube is press-formed from the outer diameter side by the contraction type, the misalignment hardly occurs, and the distal end portion of the raw tube becomes thick. The defect rate is low because it is hard to become.

  According to the present invention, in the method of manufacturing a catalytic converter, the processing time can be shortened, the defect rate can be lowered, and even a cone portion having a high diameter reduction rate can be easily formed.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  1 is a schematic explanatory view of the first embodiment, FIG. 2 is a cross-sectional view taken along line AA of FIG. 1A, and FIG. 3 is a schematic explanatory view of the second embodiment. In the catalytic converter 10 of the first embodiment, a cone portion 1d that gradually decreases in diameter from the accommodating portion 1c of the catalyst carrier 3 toward the end portion 1b of the raw tube 1 is integrally formed, while the catalyst of the second embodiment. The converter 20 is integrally formed with a cone portion 1 d that gradually decreases in diameter from the accommodating portion 1 c of the catalyst carrier 3 toward the end portion 1 b of the raw tube 1. However, in each figure, the same code | symbol is attached | subjected and demonstrated to the same or similar location.

  As shown in FIGS. 1-3, the manufacturing method of the catalytic converter which concerns on each embodiment of this invention all includes the 1st process and the 2nd process.

  That is, in the first step, the diameter of the distal end portion 1a of the raw tube 1 in which the catalyst carrier 3 is accommodated is reduced by the reduced pressure device provided with the reduced pressure mold 2. The contraction tube mold 2 is composed of a plurality of pressing members 2a so as to press-mold the outer peripheral surface of the raw tube 1 from the outer diameter side (see FIG. 2). In order to reduce the diameter of the distal end portion 1 a, the distal end portion 1 a of the fixed raw tube 1 is reduced in diameter by narrowing it with the reduced tube mold 2. However, the configuration of the present invention is not limited to such a form. For example, the distal end portion 1a is moved so as to be pushed into the fixed reduced tube mold 2 to reduce the diameter, or the fixed distal end portion 1a. However, the diameter may be reduced by moving the contracted tube mold 2 so as to be pushed. Further, the diameter may be reduced by moving the both ends so as to press each other without fixing the distal end portion 1a and the reduced tube mold 2.

  By such a first step, in the case of the first embodiment, the tip portion 1a is shaped so as to gradually reduce the diameter (see FIG. 1A), and in the case of the second embodiment, the tip portion 1a. Is formed so as to be reduced in a stepwise manner (see FIG. 3A).

  Next, in the second step, the distal end portion 1a that has been reduced in diameter in the first step is further reduced in diameter by the above-described reduced tube device, and the raw tube 1 is simultaneously or sequentially moved from the distal end portion 1a toward the housing portion 1c. The cone portion 1d is formed by reducing the diameter. In order to mold the cone portion 1d, the tip portion 1a whose diameter is reduced in the first step is moved so as to be pushed into the fixed tube mold 2. However, the configuration of the present invention is not limited to such a form. For example, after the tube-shaped mold 2 is removed from the tip portion 1a whose diameter has been reduced in the first step and the tip portion 1a is moved, the element is further removed. The diameter of the tube 1 may be reduced by narrowing the tube 1 from the distal end portion 1a toward the housing portion 1c with the reduced tube mold 2.

  By such a second step, in the case of the first embodiment, a cone portion 1d that gradually decreases in diameter from the housing portion 1c toward the distal end portion 1a is integrally formed in the base tube 1 (see FIG. 1B). In the case of the second embodiment, a cone portion 1d whose diameter is gradually reduced from the housing portion 1c toward the tip portion 1a is integrally formed in the raw tube 1 (see FIG. 3B). When the cone portion 1d is thus formed, the catalyst carrier 3 is restricted from moving toward the end portion 1b by the reduced cone portion 1d. For this reason, when the cone portions 1d are formed on both ends of the housing portion 1c, the movement of the catalyst carrier 3 is restricted from both ends. Therefore, in such a case, the catalyst carrier 3 is positioned and fixed in the housing portion 1c at the same time as the cone portion 1d is formed. Moreover, in each embodiment, it has the structure where exhaust gas cannot flow into the buffer member 4, and the gas attack to the buffer member 4 can also be prevented.

  By the way, as shown in FIG.1 and FIG.3, it is preferable to provide the clearance gap 5 between the contraction type | mold 2 and the accommodating part 1c. In such a case, distortion generated in the catalyst carrier 3 due to the gap 5 can be reduced. Further, it is preferable that the buffer member 4 is provided between the base tube 1 and the catalyst carrier 3 so that the catalyst carrier 3 is protected by being wound around the buffer member 4 such as a mat. In such a case, the strain generated in the catalyst carrier 3 by the buffer member 4 can be absorbed.

  As described above, each of the embodiments of the present invention is an improvement of the conventional shrink method, and specifically, after reducing the diameter of the distal end portion 1a of the raw tube 1 in the first step, The cone portion 1d is formed in two steps. Therefore, compared to the case where the raw tube 1 is pressed and contracted in one step from the tip 1a to the accommodating portion 1c of the catalyst carrier 3, the catalyst carrier 3 is less likely to be distorted and the cone portion has a high diameter reduction rate. Even 1d can be easily molded. Further, in the manufacturing method of the catalytic converter having such a configuration, the machining amount is large and the finishing cut is not required as compared with the spinning method, so that the machining time can be shortened. Furthermore, in the manufacturing method of the catalytic converter having such a configuration, since the outer peripheral surface of the raw tube 1 is pressed from the outer diameter side by the reduced tube mold 2, misalignment hardly occurs, and the tip of the raw tube 1 Since the part 1a does not easily become thick, the defect rate is low.

It is a schematic explanatory drawing of 1st embodiment which concerns on this invention. It is the sectional view on the AA line of Fig.1 (a). It is a schematic explanatory drawing of 2nd embodiment which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Elementary tube 2 Reduced tube type 3 Catalyst support 4 Buffer member 5 Crevice 10, 20 Catalytic converter

Claims (1)

A catalyst in which a catalyst carrier for exhaust gas purification is accommodated inside a raw tube, and a cone portion that is gradually or stepwise reduced in diameter from the catalyst carrier accommodating portion toward the end of the raw tube A method for manufacturing a converter, comprising:
A first step of reducing the diameter of the tip of the raw tube containing the catalyst carrier by a reduced tube device including a reduced tube mold that press-molds the outer peripheral surface of the raw tube from the outer diameter side;
Further reducing the diameter of the tip portion reduced in diameter in the first step by the tube-reducing device, and simultaneously or sequentially reducing the diameter of the raw tube from the tip portion toward the accommodating portion, thereby reducing the cone portion. A second step of molding;
The manufacturing method of the catalytic converter characterized by including.

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