JP4503862B2 - Processing method of terminal exhaust pipe - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for processing a terminal exhaust pipe in which exhaust gas from an engine of a vehicle or the like is discharged into the atmosphere.
[0002]
[Prior art]
FIG. 9 shows a conventional example of a terminal exhaust pipe 1 arranged at a site where exhaust gas of an engine such as a vehicle is discharged into the atmosphere. When the exhaust gas after noise reduction is finally discharged into the atmosphere by the muffler 2, it passes through the terminal exhaust pipe 1. In consideration of risk prevention and appearance, etc., a pipe expansion member 3 having a diameter larger than that of the separate exhaust pipe body 1a is attached to the final end of the exhaust pipe body 1a by a welded portion P. The pipe expansion member 3 is formed to have a base end inner diameter that is greater than or equal to the outer diameter of the exhaust pipe body 1a that is extrapolated, and is tapered from the large diameter pipe expansion member 3. As the terminal exhaust pipe, such a structure, a type in which a separate part to be externally attached to the exhaust pipe main body is attached by band fastening, fixing with a bolt and nut, and the like are generally used.
[0003]
In the manufacture of terminal exhaust pipes, the conventional structure that integrates a separate expanded member with the exhaust pipe body requires work such as welding and caulking, and the number of parts increases. There were difficulties such as requiring a surface treatment such as plating in a later process.
[0004]
[Problems to be solved by the invention]
Accordingly, the present inventor has studied a low-cost and high-efficiency processing method for a terminal exhaust pipe through which engine exhaust gas is discharged into the atmosphere, and has aimed to provide it at a low cost.
[0005]
[Means for Solving the Problems]
Result of studying the above problems, forms the terminal of the tube expanded pipe portion (1c), and the processing of the expanded portion terminal exhaust pipe substantially by forming an inner folded double tube over the entire area of (1c) (10) Developed the law . The expanded pipe (1c) here has continuous pipes. The continuous pipe means that the expanded pipe (1c) at the end is the same as the exhaust pipe body (1a) and is not a separate member. ing. “Over the entire area of the expanded pipe portion (1c)” means a state in which the double pipe exists from the final end until it almost reaches the tapered section (1b) .
[0006]
Such a method of processing the terminal exhaust pipe (10) is obtained by press-fitting a core (6) composed of a small diameter part (6a), a tapered part (6b) and a large diameter part (6c) . and expanding process of forming the expanded pipe portion (1c) by expanding the end portion to the reduced pipe expanded pipe portion (1c) tip by press molding using the outer shape and the female mold after the contraction tube (7) reduced pipe a step, a cutting step of arranging cut the reduced pipe portion (1d) tip is pressed tube expansion portion (1c) tip projections of the punch (8) to the contraction pipe portion of the upper (1d) (8a) in contact with it implements and inwardly folding the molding step of folding inward of the reduced pipe portion (1d) of the expanded pipe portion (1c) in the described order by. Expanding process is a so-called bulging employs the press and general-purpose hydraulic pressure Engineering method of press-fitting the core into the tube. For the tube contraction process at the tip of the tube part, a press using a tube-shaped forming die or general-purpose hydraulic processing is preferable . Inwardly folding-back molding process, a method of press-fitting a punch tip in contact with the reduced pipe portion (1d) is preferable.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in the order of steps with reference to the drawings. First, as shown in a side view of the main part in FIG. 1, the end of the raw pipe (4) is expanded by a pipe expanding process, and the end of the exhaust pipe main body (1a) is expanded through a tapered section (1b) ( 1c) is formed in a continuous state. The degree of pipe expansion can be freely designed according to the design specifications within the pipe expansion allowance. As shown in FIG. 2, the expansion portion (1c) is formed by a small-diameter hole portion (5a) , a tapered portion (5b) , a large-diameter hole portion (5c) into which the element tube (4) can be inserted. The raw material pipe (4) is placed in the outer mold (5) , and the small diameter part (6a) and the tapered part are similar in shape to the outer mold 5 and have a small diameter by the thickness of the exhaust pipe after molding. The core (6) consisting of (6b) and the large diameter part (6c) is press-fitted.
[0008]
Next, the tube contraction process at the tip of the expanded portion (1c) is performed. This step is press molding using a female mold (7) having an outer shape after contraction as seen in FIG. The tip of the expanded pipe (1c) is pressed to forcibly contract. Thereafter, as shown in FIG. 4, the distal end of the contracted tube portion (1d) is cut (arrow C ) by the cutting process to prepare the distal end of the contracted tube portion (1d) as shown in FIG.
[0009]
Inner Hoori barbs forming process of the expanded portion (1c), as shown in FIG. 7, using a punch (8). The tip ridge (8a) of the punch (8) is brought into contact with and pressed into the contracted tube (1d) on the upper portion of the expanded tube (1c) held by the outer mold (5) . FIG. 6 is a sectional view of the completed terminal exhaust pipe (10) . Inside almost over the entire final terminal forms the expanded pipe portion (1c) the tube through the taper portion (1b) to one end of the exhaust pipe body (1a) is directly in a continuous state, and the expanded pipe portion (1c) A double pipe with a folded pipe part (1e) is formed. When the contact with the reduced pipe section the punch (1d) may there adversely affect service performance by also remaining after becoming a product, a step of removing the reduced pipe portion of the vent pipe to (1d) It may be increased or may be folded outward as shown in FIG. The wall surfaces of the double pipes can also be brought into close contact with each other.
[0010]
【The invention's effect】
According to the present invention, a low-cost and high-efficiency processing method for a terminal exhaust pipe that does not require surface treatment of the terminal exhaust pipe or a separate member has been established, and the terminal exhaust pipe can be provided at a low cost. By forming the folded pipe part inside the pipe by pressing the tip of the punch into the contracted pipe part and press-fitting, it is more reliable than a system that simply press-fits from the pipe end part and causes the bent part to buckle. The terminal exhaust pipe bent inward at the designed position is obtained, and the yield is good. Further, since the terminal exhaust pipe has a double structure, it does not require a surface finish to avoid terminal corrosion. The terminal has good strength and appearance.
[Brief description of the drawings]
FIG. 1 is a side view of a main part of a terminal exhaust pipe manufacturing process according to the present invention.
FIG. 2 is a cross-sectional view of a molding apparatus showing a state in which a raw material pipe is placed in an outer mold and a core is press-fitted.
FIG. 3 is a cross-sectional view of a forming apparatus showing a state of a contraction tube.
FIG. 4 is a side view of an essential part of a terminal exhaust pipe manufacturing process in which a tip of a contracted pipe part is cut.
FIG. 5 is a side view of the main part of the terminal exhaust pipe manufacturing process.
FIG. 6 is a cross-sectional view of a main part of the terminal exhaust pipe manufacturing process.
FIG. 7 is a cross-sectional view of a molding apparatus showing a state of a folding molding process.
FIG. 8 is a cross-sectional view of an essential part showing an example of a terminal exhaust pipe of a product.
FIG. 9 is a plan view showing a state of arrangement of a terminal exhaust pipe of a conventional example.
[Explanation of symbols]
1a Exhaust pipe body
1b Taper part
1c Expansion section
1d contraction section
1e folded pipe section 2 muffler <br/> 3 expanded pipe member 4 blank tube 5 outer mold 6 core 7 mold 8 punch
10 Terminal exhaust pipe of the present invention

Claims (1)

Expanding the end of the raw pipe (4 ) to form the expanded pipe (1c) by press-fitting the core (6) consisting of the small diameter (6a), taper (6b) and large diameter (6c) cut a step, the reduced pipe step of reduced pipe the expanded pipe portion (1c) tip by press molding using the outer shape and the female mold after the condensation tube (7), the reduced pipe portion (1d) tip The cutting step to be arranged and the expanded tube portion (1c) by expanding the expanded tube portion (1c) by pressing the protruding ridge (8a) of the punch (8) against the expanded tube portion (1d). processing method of the terminal exhaust pipe and inner folding molding step folding inwardly you carried on the the order of (1c).

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