JP2010120066A - Method for forming tube end flange - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To eliminate the risk of breakage caused by vibration or the like and to evade the increase in weight and the number of parts. <P>SOLUTION: The method is provided with: a diameter widening stage where the diameter of the opening end part in a tube body 5 is widened; a deletion stage where the symmetrical parts in the radial direction of the tube wall 52 in the diameter-widened opening end part is deleted so as to form a pair of opposite projecting parts 521, 522; and a bending stage where both the projecting parts 521, 522 are bent to a position almost orthogonal to the tube body 5 so as to be a tube end flange. In the deletion stage, the symmetrical parts in the radial direction of the tube wall 52 are deleted to an expanded curve along the outer form of the tube end flange in which the peak reaches the vicinity of the base end of the tube wall 52. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for forming a pipe end flange, and more particularly to a method for forming a pipe end flange that can be used to connect a vehicle exhaust pipe.

  11 and 12 show an example of a conventional exhaust pipe connection structure. In FIG. 12, substantially diamond-shaped connection flanges 61 and 62 are fixed to the outer periphery of the pipe ends of the upstream exhaust pipe 1 and the downstream exhaust pipe 2 by welding. The connecting flanges 61 and 62 are connected by a bolt 64 and a nut 65 via a gasket 63.

Patent Document 1 discloses a structure in which flange members are welded and fixed to the outer peripheries of one exhaust pipe and the other exhaust pipe inserted into one end opening thereof, and these flange members are connected by bolts and nuts. It is shown.
JP-A-8-75063

  However, in the above conventional structure, the connecting flanges 61 and 62 need to be fixed to the outer periphery of the exhaust pipes 1 and 2 by welding, so that stress concentrates on the welded joints and cracks occur due to vehicle vibration or the like. In addition to being easy, there is a problem that the welding process requires labor and cost.

  Accordingly, the present invention solves such problems, and when used for connecting exhaust pipes, there is no risk of damage due to vibration or the like, and an increase in weight, number of parts, and cost can be avoided. An object of the present invention is to provide a molding method.

  In order to achieve the above object, in the first aspect of the present invention, a diameter expanding step for expanding the opening end (51) of the pipe body (5), and a cylinder wall (52 for the expanded opening end (51). ) In the radial direction, and a pair of opposing convex portions (521, 522) is formed, and both convex portions (521, 522) are substantially orthogonal to the tubular body (5). And a bending step of bending the tube end flanges (12, 22).

  In the first invention, since the pipe end flange can be formed integrally with one end of the pipe body, it is not necessary to fix a separate flange to the outer circumference of the pipe end of the pipe body by welding as in the prior art. Therefore, if this is used for an exhaust pipe, for example, stress is not concentrated on the welded joint portion of the flange, and cracking damage is not caused by vehicle vibration or the like. In addition, according to the present invention, no labor is required for the welding process, and a significant increase in weight, the number of parts, and an increase in cost can be avoided.

  In this 2nd invention, in the said deletion process, the radial direction symmetrical part of the cylinder wall (52) followed the external shape of the pipe end flange (12, 22) in which the vertex reaches near the base end of the cylinder wall (52). Delete to unfold curve. In the second aspect of the present invention, a pipe end flange having an appropriate outer shape can be obtained by merely bending both convex portions to a position substantially orthogonal to the pipe body without requiring subsequent processing.

  In addition, the code | symbol in the said parenthesis shows the correspondence with the specific means as described in embodiment mentioned later.

  As described above, according to the method for forming a pipe end flange of the present invention, when used for connecting exhaust pipes, there is no risk of damage due to vibration or the like, and an increase in weight and number of parts can be avoided.

  FIG. 1 shows an example in which an upstream exhaust pipe and a downstream exhaust pipe are connected by a pipe end flange formed by the method of the present invention. In FIG. 1, pipe end flanges 12, 22 extending outward are formed at the opening edge of the downstream end 11 opening of the upstream side exhaust pipe 1 and the upstream end 21 opening edge of the downstream side exhaust pipe 2, respectively. The tube end flanges 12 and 22 are coupled and connected by bolts 41 and nuts 42 through seal members 3 inserted into the recessed receiving portions 13 and 23.

  Hereinafter, the molding process of the pipe end flange 12 will be described. As shown in FIG. 2, the diameter of one open end 51 of the circular tubular body 5 serving as the exhaust pipes 1 and 2 is increased by a bulge punch and a die (not shown) in a stepped manner with a fixed length L. As an example, the diameter of the open end 51 of the tubular body 5 having an outer diameter φ1 of 48.6 mm and a thickness of 1.2 mm is increased to φ2 = 61 mm (first diameter expanding step). This diameter expansion step is performed in a plurality of steps as necessary. In the present embodiment, following the first diameter expanding step, the outer diameter of the opening end 51 is expanded to φ3 = 67.4 mm by a bulge punch and a die (FIG. 3, second diameter expanding step). Then, the third diameter expansion process is performed subsequent to the second diameter expansion process, and the outer diameter of the opening end 51 is expanded to φ4 = 74.0 mm by the bulge punch and the die (FIG. 4). Further, following the third diameter expansion step, the outer diameter of the opening end 51 is expanded to φ5 = 80.3 mm by a bulge punch and die (FIG. 5, fourth diameter expansion step).

  After finishing the fourth diameter expansion step, the radially symmetrical position of the cylindrical wall 52 of the expanded opening end 51, which is 180 ° apart, is deleted in the development curve so that the vertex reaches the base end of the cylindrical wall. (Delete process). This unfolded curve is a curve that becomes a pipe end flange of a predetermined shape when a convex portion described later is unfolded horizontally in the bending process. The above deletion is performed, for example, by polishing using a sander or by laser cutting. As a result, a pair of chevron-shaped convex portions 521 and 522 are left on the cylindrical wall 52 at positions that are separated from each other by 180 °. Although it is not always necessary to delete in the arc shape in the deletion process, according to this, the mountain-shaped convex portions 521 and 522 are obtained, so that a pipe end flange having an appropriate outer shape can be obtained simply by bending as described later. .

  After the deletion step, the convex portions 521 and 522 of the cylindrical wall 52 are bent outward by a bend punch. In the present embodiment, this bending step is performed in two steps. In the first bending step (FIG. 7), the mountain-shaped portions 521 and 522 are bent outward by about 45 °, and in the subsequent second bending step, the mountain-shaped portions 521 and 522 are bent outward to a horizontal position of approximately 90 °. (FIG. 8). As a result, as shown in FIG. 10, the tube end flange 12 in which the convex portions 521 and 522 extend to the left and right is formed at the opening edge of the circular tube body 5.

  After the second bending step (FIG. 8), an annular region having a constant width along the outer periphery of the tube end of the tube end flange 12 is recessed by a certain amount (for example, 2 mm) to form the accommodating portion 13. (FIG. 9). Thereafter, the bolt insertion holes 14 are formed on the plate surfaces of the left and right convex portions 521 and 522 of the pipe end flange 12 by a drilling machine. The process for forming the pipe end flange 22 is the same.

  If the pipe body 5 in which the pipe end flanges 12 and 22 are formed in this way is used as the upstream exhaust pipe 1 and the downstream exhaust pipe 2, as described above, the housing portion 13 of the pipe end flanges 12 and 22 is sealed. With the member 3 interposed, both the exhaust pipes 1 and 2 can be hermetically connected by a bolt 41 and a nut 42 that are passed through the bolt insertion hole 14.

  According to the present embodiment, the pipe end flanges 12 and 22 can be integrally formed at one end of the exhaust pipes 1 and 2, so that a separate flange is fixed to the outer periphery of the pipe end of the exhaust pipe by welding as in the prior art. There is no need to do. Therefore, there is no problem that stress is concentrated on the welded joint of the flange and cracking damage occurs due to vehicle vibration or the like, and the welding process is troublesome, and a significant increase in weight and number of parts can be avoided. . Note that the present invention is not limited to use in a vehicle exhaust pipe.

It is a cross-sectional view of the connected vehicle exhaust pipe in one embodiment of the present invention. It is a side view which shows the manufacturing process of a pipe end flange. It is a side view which shows the manufacturing process of a pipe end flange. It is a side view which shows the manufacturing process of a pipe end flange. It is a side view which shows the manufacturing process of a pipe end flange. It is a side view which shows the manufacturing process of a pipe end flange. It is sectional drawing which shows the manufacturing process of a pipe end flange. It is sectional drawing which shows the manufacturing process of a pipe end flange. It is sectional drawing which shows the manufacturing process of a pipe end flange. It is a front view which shows the manufacturing process of a pipe end flange. It is a cross-sectional view of the connected vehicle exhaust pipe which shows a prior art example. It is a longitudinal cross-sectional view along the XII-XII line of FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Upstream exhaust pipe, 12 ... Pipe end flange, 2 ... Downstream exhaust pipe, 22 ... Pipe end flange, 41 ... Bolt, 42 ... Nut, 5 ... Pipe body, 51 ... Open end, 52 ... Tube wall, 521, 522 ... convex portions.

Claims (2)

A diameter expanding step for expanding the opening end of the tubular body, a deletion step for forming a pair of opposed convex portions by deleting the radially symmetric portion of the cylindrical wall of the expanded opening end, A method for forming a pipe end flange, comprising a step of bending a convex portion outwardly substantially perpendicular to the pipe body to form a pipe end flange. 2. The pipe end flange according to claim 1, wherein, in the deleting step, the radially symmetric portion of the tube wall is deleted into a developed curve along the outer shape of the tube end flange, the apex of which is close to the proximal end of the tube wall. Molding method.

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