JP2023055541A - Manufacturing method for exhaust system component - Google Patents

Abstract

To provide a manufacturing method for an exhaust system component capable of suppressing damage during welding of the exhaust system component having a thick wall part.SOLUTION: One aspect of the present disclosure is a manufacturing method for an exhaust system component constituting a flow path for exhaust gas. The manufacturing method for the exhaust system component comprises steps of: heating a first cylindrical body and a second cylindrical body in a state where the first cylinder and the second cylinder are connected; and after the heating step, welding the first cylindrical body and the second cylindrical body. In the heating step, a thick part of the first cylindrical body, which is thicker in a radial direction than the other portions, is heated preferentially over the other portions.SELECTED DRAWING: Figure 4

Description

The present disclosure relates to a method of manufacturing an exhaust system component.

An exhaust system part that forms an exhaust gas flow path is configured by a plurality of cylinders (that is, pipe members) that are connected by welding. The connected cylindrical bodies include parts having thick portions, such as joints (see Patent Document 1).

JP 2015-161308 A

When connecting cylinders constituting exhaust system parts by welding, stress is generated if there is a temperature variation in the objects to be welded. Such stress may cause damage such as cracks in exhaust system components.

Temperature variations during welding can be suppressed by heating the parts before welding. However, it is difficult to reduce temperature variations in thick portions such as the joints described above, because the temperature does not easily rise due to heating.

An object of one aspect of the present disclosure is to provide a method for manufacturing an exhaust system component that can suppress breakage during welding of the exhaust system component having a thick portion.

One aspect of the present disclosure is a method of manufacturing an exhaust system component that configures an exhaust gas flow path. A method for manufacturing an exhaust system component includes a step of heating the first cylinder and the second cylinder while the first cylinder and the second cylinder are connected, and after the heating step, the first cylinder and the second cylinder. and welding the two cylinders together. In the heating step, the thick portion of the first cylindrical body, which is thicker in the radial direction than the other portions, is heated preferentially over the other portions.

According to such a configuration, the first cylinder and the second cylinder are welded in a state in which the temperature difference between the thick part and the other parts is reduced. The generation of stress in the body is suppressed. As a result, it is possible to suppress damage during welding of exhaust system components having thick portions.

In one aspect of the present disclosure, the first cylindrical body may be mainly made of ferritic stainless steel. With such a configuration, the coefficient of thermal expansion of the first cylindrical body is reduced, and the oxidation characteristics can be improved in cycles in which high temperature conditions are repeated.

In one aspect of the present disclosure, the first cylindrical body has a cylindrical main body portion and a first end portion having an outer diameter larger than that of the main body portion and being welded to the second cylindrical body of the main body portion. and a brim provided continuously with the second end of the side. The collar portion may constitute the thick portion. According to such a configuration, it is possible to suppress the generation of stress in the collar portion used for fastening and the breakage of the joint due to this stress.

In one aspect of the present disclosure, the second cylindrical body may be a catalyst case that stores a catalyst. With such a configuration, damage to the catalyst case made of a material with a small thermal expansion coefficient can be suppressed.

In one aspect of the present disclosure, in the heating step, a heat source that sends hot air to the inside of the first cylinder and the second cylinder, and a guide device that guides the hot air to the thick portion may be used. According to such a configuration, it is possible to preferentially heat the thick portion relatively easily.

In one aspect of the present disclosure, in the heating step, the hot air may be guided to the thick portion by making the hot air collide with a guiding device. According to such a configuration, it is relatively easy to change and adjust the position for guiding the hot air, so that the production efficiency of the exhaust system parts can be improved.

FIG. 1 is a schematic diagram of an exhaust system component in an embodiment. FIG. 2 is a schematic partial cross-sectional view showing an example of a fastening state of the exhaust system parts of FIG. FIG. 3 is a flow diagram of a method for manufacturing an exhaust system component according to the embodiment. FIG. 4 is a schematic diagram showing one step in the method of manufacturing the exhaust system part of FIG. FIG. 5 is a schematic diagram showing one step in the method of manufacturing the exhaust system part of FIG.

Embodiments to which the present disclosure is applied will be described below with reference to the drawings.
[1. First Embodiment]
[1-1. composition]
<Exhaust system parts>
An exhaust system component 10 shown in FIG. 1 is provided in an exhaust gas flow path of an internal combustion engine. Specifically, the exhaust system component 10 constitutes a part of an exhaust gas purification device that purifies exhaust gas. The exhaust system component 10 includes a first cylinder 20 and a second cylinder 30 .

(First cylindrical body)
The first tubular body 20 is a joint that is fastened to another tubular body P by a fastening component such as a V-band clamp V shown in FIG. 2, for example.

The first cylindrical body 20 is mainly made of ferritic stainless steel. Specifically, the first cylindrical body 20 is formed by casting ferritic stainless steel. As shown in FIG. 1 , the first cylindrical body 20 has a body portion 21 and a collar portion 22 .

The body portion 21 is a cylindrical member through which exhaust gas flows. The thickness of the body portion 21 is substantially constant in the axial direction. The first end portion 21A of the main body portion 21 is welded to the second cylindrical body 30 at a welding portion W. As shown in FIG. A collar portion 22 is provided axially outside the second end portion 21B of the body portion 21 opposite to the first end portion 21A.

The collar portion 22 is a ring-shaped portion having an outer diameter larger than that of the body portion 21 . The collar portion 22 protrudes radially outward from the second end portion 21B of the body portion 21 . The collar portion 22 constitutes a thick portion having a larger radial thickness than other portions of the first cylindrical body 20 (that is, portions other than the collar portion 22).

That is, the end portion of the first cylindrical body 20 opposite to the second cylindrical body 30 is a thick portion having a greater radial thickness than the other portions of the first cylindrical body 20 . In addition, as shown in FIG. 2, the flange portion 22 is provided with a groove 22A for arranging a gasket.

(Second cylindrical body)
A second cylindrical body 30 shown in FIG. 1 is a catalyst case that stores a catalyst. The catalyst stored in the second cylindrical body 30 reforms or collects environmental pollutants in the exhaust gas through contact with the exhaust gas, thereby purifying the exhaust gas.

Like the first cylinder 20, the second cylinder 30 is mainly made of ferritic stainless steel. Specifically, the second cylindrical body 30 is made of a ferritic stainless steel plate. By using ferritic stainless steel for both the first cylindrical body 20 and the second cylindrical body 30, durability can be improved by welding the same material. In addition, ferritic stainless steel has a smaller coefficient of thermal expansion (that is, less thermal expansion) than austenitic stainless steel, and has excellent oxidation properties at high temperatures (that is, less likely to oxidize).

The thickness of the second cylindrical body 30 is substantially constant in the axial direction. One end of the second cylinder 30 is inserted into the first cylinder 20 and connected to the first cylinder 20 by welding.

<Manufacturing method of exhaust system parts>
The method for manufacturing an exhaust system component shown in FIG. 3 includes an arrangement step S10, a heating step S20, a moving step S30, and a welding step S40.

(Placement process)
In the arranging step S10, the first tubular body 20 and the second tubular body 30 that are not welded are arranged in the heating device 100, as shown in FIG.

The heating device 100 has a heat source 110 , an air guide passage 120 and a guide fixture 130 . The heat source 110 generates hot air H by, for example, a heating wire and an air blower, and sends the hot air to the inside of the first cylindrical body 20 and the second cylindrical body 30 through the air guide path 120 .

The guide device 130 guides the hot air H to the thick portion of the first cylindrical body 20 . The guide device 130 has a collision portion 131 , a shaft portion 132 and a support member 133 .

The collision part 131 is a cone-shaped member that expands in diameter from the heat source 110 toward the inside of the first cylindrical body 20 . The maximum outer diameter of the collision part 131 is smaller than the inner diameter of the first cylindrical body 20 . A portion of the collision portion 131 is arranged inside the air guide passage 120 .

The shaft portion 132 is attached to the center portion of the collision portion 131 . The shaft portion 132 extends in the axial direction of the air guide passage 120 . The support member 133 supports the shaft portion 132 . The support member 133 is attached inside the air guide passage 120 . The position of the collision part 131 can be adjusted by adjusting the positions of the shaft part 132 and the support member 133 .

The internal spaces of the collision portion 131 and the shaft portion 132 may communicate with the inside of the air guide passage 120 . That is, the hot air H may be supplied inside each of the collision part 131 and the shaft part 132 .

In the placement step S10, the guiding device 130 is inserted into the first cylindrical body 20 so that the collision portion 131 of the guiding device 130 overlaps the thick portion (that is, the collar portion 22) of the first cylindrical body 20 in the radial direction. . Specifically, the collision portion 131 is arranged so that the side surface of the collision portion 131 faces the thick portion in the radial direction of the first cylindrical body 20 .

Further, in the arranging step S<b>10 , the first cylinder 20 is arranged such that the second end 21</b>B of the first cylinder 20 is connected to the air guide passage 120 . The second cylinder 30 is arranged to be connected to the first end 21A of the first cylinder 20 .

(Heating process)
In the heating step S<b>20 , the heating device 100 is used to heat the first cylinder 20 and the second cylinder 30 from the inside while the first cylinder 20 and the second cylinder 30 are connected.

The hot air H supplied into the first cylinder 20 from the air guide passage 120 passes through the insides of the first cylinder 20 and the second cylinder 30 and is discharged from the second cylinder 30 to the outside. Further, in the heating step S<b>20 , the hot air H is guided to the thick portion of the first cylindrical body 20 by making the hot air H collide with the colliding portion 131 of the guide device 130 .

That is, by changing the course of the hot air H so as to follow the side surface of the collision portion 131, the hot air H is caused to collide with the inner peripheral surface of the thick portion. As a result, the first cylindrical body 20 is heated around the thick portion, and the flange portion 22, which is the thick portion, is heated preferentially over the main body portion 21, which is the other portion. That is, the amount of heat received by the thick portion is greater than the amount of heat received by the other portions of the first cylindrical body 20 and the second cylindrical body 30 .

(moving process)
In the moving step S30, after the heating step S20, the heat source 110 is removed from the air guide passage 120 and moved to a position away from the first cylinder 20 and the second cylinder 30, as shown in FIG.

As a result, the heat source 110 can be protected from welding fumes, spatter, and the like generated when the first cylinder 20 and the second cylinder 30 are welded together. In addition, it is possible to suppress deterioration in weldability due to disturbance of the welding gas flow during welding by hot air generated from the heat source 110 .

As a specific method of moving heat source 110 , a method of swinging heat source 110 from a use position connected to air guideway 120 to a storage position protected by protective cover 140 can be exemplified. Accordingly, when the first cylinder 20 and the second cylinder 30 are welded together, the protective cover 140 is positioned between the welding point and the heat source 110 . As a result, the protective cover 140 functions as a shielding member, making it difficult for the welding fumes, spatter, etc. described above to hit the heat source 110 .

(Welding process)
In the welding step S40, the first cylinder 20 and the second cylinder 30 are welded after the moving step S30. Specifically, the welding portion W where the first end portion 21A of the main body portion 21 of the first cylindrical body 20 and the second cylindrical body 30 overlap is welded over the entire circumferential direction.

[1-2. effect]
According to the embodiment detailed above, the following effects are obtained.
(1a) Since the first cylinder 20 and the second cylinder 30 are welded while the temperature difference between the thick part and other parts is small, the first cylinder 20 and the second cylinder 30 The generation of stress is suppressed in As a result, damage during welding of the exhaust system component 10 having a thick portion can be suppressed.

(1b) Since the first cylindrical body 20 is mainly made of ferritic stainless steel, the coefficient of thermal expansion of the first cylindrical body 20 is reduced, and the oxidation characteristics can be improved in cycles in which high temperature conditions are repeated.

(1c) Since both the first cylindrical body 20 and the second cylindrical body 30 are mainly made of ferritic stainless steel, the same material is welded, and the difference in thermal expansion between the first cylindrical body 20 and the second cylindrical body 30 is reduced. can be reduced. Furthermore, since ferritic stainless steel has a smaller coefficient of thermal expansion than austenitic stainless steel, the dimensional difference when the first cylindrical body 20 and the second cylindrical body 30 thermally expand and contract is reduced. As a result, breakage of the first cylinder 20 and the second cylinder 30 is suppressed.

(1d) Since the first cylindrical body 20 is a joint having the flange portion 22, it is possible to suppress generation of stress in the flange portion 22 used for fastening and breakage of the joint due to this stress.
(1e) Since the second cylindrical body 30 is the catalyst case, damage to the catalyst case made of a material with a small coefficient of thermal expansion can be suppressed.

(1f) By using the heat source 110 that sends hot air and the guide device 130 that guides the hot air to the thick part, the thick part can be preferentially heated relatively easily.
(1g) Making the hot air collide with the guiding device 130 makes it relatively easy to change and adjust the position for guiding the hot air, so that the production efficiency of the exhaust system parts 10 can be improved.

[2. Other embodiments]
Although the embodiments of the present disclosure have been described above, it is needless to say that the present disclosure is not limited to the above embodiments and can take various forms.

(2a) In the method of manufacturing an exhaust system component according to the above embodiment, the material of the first cylinder and the second cylinder is not limited to ferritic stainless steel.

(2b) In the method of manufacturing an exhaust system component according to the above embodiment, the first cylindrical body is not limited to a joint having a flange. Also, the second cylinder is not limited to the catalyst case. Furthermore, the thick portion may be provided on both the first cylinder and the second cylinder. Also, the thick portion may include a portion other than the collar portion of the first cylindrical body.

(2c) In the method of manufacturing an exhaust system component according to the above embodiment, the hot air may be guided to the thick portion by means other than colliding with the guiding device. Also, the first cylinder and the second cylinder may be heated by means other than hot air. For example, the thick portion may be preferentially heated by attaching a heater directly to the thick portion.

(2d) The function of one component in the above embodiments may be distributed as multiple components, or the functions of multiple components may be integrated into one component. Also, part of the configuration of the above embodiment may be omitted. Also, at least a part of the configuration of the above embodiment may be added, replaced, etc. with respect to the configuration of the other above embodiment. It should be noted that all aspects included in the technical idea specified by the wording in the claims are embodiments of the present disclosure.

DESCRIPTION OF SYMBOLS 10... Exhaust system components 20... 1st cylinder 21... Main-body part 21A... 1st end part,
21B... second end, 22... flange, 22A... groove, 30... second cylindrical body, 100... heating device,
DESCRIPTION OF SYMBOLS 110... Heat source, 120... Air guide path, 130... Guidance tool, 131... Collision part, 132... Shaft part,
133... Support material, 140... Protective cover.

Claims (6)

A method for manufacturing an exhaust system component that configures an exhaust gas flow path, comprising:
a step of heating the first cylinder and the second cylinder while the first cylinder and the second cylinder are connected;
a step of welding the first cylindrical body and the second cylindrical body after the heating step;
with
The method for manufacturing an exhaust system component, wherein, in the heating step, a thick portion of the first cylindrical body having a larger thickness in a radial direction than other portions is heated preferentially over other portions. A method for manufacturing an exhaust system component according to claim 1,
The method for manufacturing an exhaust system part, wherein the first cylindrical body is mainly made of ferritic stainless steel. A method for manufacturing an exhaust system component according to claim 1 or claim 2,
The first cylindrical body is
a cylindrical main body;
a collar portion having an outer diameter larger than that of the main body portion and provided continuously to a second end portion of the main body portion opposite to a first end portion welded to the second cylindrical body;
has
The method of manufacturing an exhaust system component, wherein the flange portion constitutes the thick portion. A method for manufacturing an exhaust system component according to any one of claims 1 to 3,
The method of manufacturing an exhaust system component, wherein the second cylindrical body is a catalyst case that stores a catalyst. A method for manufacturing an exhaust system component according to any one of claims 1 to 4,
A method of manufacturing an exhaust system part, wherein the heating step uses a heat source for sending hot air to the insides of the first and second cylindrical bodies, and a guide device for guiding the hot air to the thick portion. A method for manufacturing an exhaust system component according to claim 5,
The method for manufacturing an exhaust system part, wherein in the heating step, the hot air is caused to collide with the guide device to guide the hot air to the thick portion.

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