JPH06344042A - Method and device for forming curl pipe - Google Patents

Abstract

PURPOSE:To provide a method and a device for forming a curl pipe in order to pricely manufacture a curl pipe having a curled part on one end. CONSTITUTION:A curl die 12 is provided with an annular R-groove having a first curled part curling downward toward the bottom and a second curled part curling upward from the bottom in the direction opposite from the first curled part. A cylindrical pipe 11 is inserted over a mandrel 15, and the lower part is abutted on the first curled part of the R-groove. A collar 16 is placed on the pipe 11, and when a load is applied to the collar 16, the lower end of the pipe 11 begins to curl along the R-groove. Then, the lower end of the pipe 11 is abutted on the inside wall in the space of a spacer 13. When a load is further applied, the lower end of the pipe 11 is extended upward without going inside from its position. Through these operations, the curled part of a curl pipe is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a curl pipe molding method and apparatus for manufacturing a curl pipe applied to an exhaust manifold connected to an engine of a vehicle and having a folded portion at one end. .

[0002]

2. Description of the Related Art Generally, an engine of a vehicle is provided with an exhaust manifold for guiding exhaust gas from the engine to an exhaust system. FIG. 3 is a configuration diagram showing a configuration example of the exhaust manifold. This exhaust manifold is
A branch in which one end is inserted into a cylindrical manifold body 1, a flange 2 arranged at each exhaust port portion of an engine cylinder head, and a hole provided in each flange 2 and the other end is connected to the manifold body 1. And a pipe 3. Further, an outlet flange 4 for connecting an exhaust system is provided at the opening of the manifold body 1.

Since the exhaust gas passes through the exhaust manifold, the manifold body 1 becomes hot after a lapse of time after the engine is started. Then, the manifold body 1 is deformed in the direction indicated by the arrow in FIG. 3, that is, in the direction from the central branch pipe 3 to the end side branch pipe 3, so that the branch pipe 3 connected to the manifold body 1 is A force that acts to deform the flange 2 is exerted. When the flange 2 is deformed, the exhaust gas may leak from the connecting portion between the flange 2 and the branch pipe 3.

Therefore, in order to prevent the deformation of the flange 2, various measures have been proposed. One of them is a method of using a curl pipe as the branch pipe 3 as disclosed in Japanese Patent Laid-Open No. 5-39717. The curl pipe is a pipe having a folded portion 5 at one end as shown in FIG.

Such a curled pipe is provided with a folded portion 6
Are connected to the manifold main body 1 and the holes provided in the flange 2 so that they are connected to the manifold main body 1 side. FIG. 5 shows a branch pipe 3 using such a curl pipe.
FIG. 3 is a cross-sectional view showing a configuration of an exhaust manifold in which No. 1 is used. The central branch pipe 32 is not a curl pipe.

In an exhaust manifold having such a curl pipe, when the manifold body 1 is going to be deformed in its axial direction, the folded portion 5 at the connecting portion between the manifold body 1 and the branch pipe 31 follows the deformation. Displace. As a result, the force to deform the flange 2 is not transmitted to the flange 2. Therefore, the deformation of the flange 2 is prevented.

[0007]

However, there is still no effective method for manufacturing such a curled pipe, particularly, a method for accurately forming the folded-back portion 5. Note that FIG.
A method for manufacturing a flare pipe having a flare portion at one end as shown in (B) is established.

Therefore, an object of the present invention is to provide a curl pipe molding method and apparatus for manufacturing a curl pipe with high accuracy.

[0009]

According to a first aspect of the present invention, there is provided a curl pipe forming method, wherein a curl pipe descends while curving toward a bottom portion and a direction opposite to the first curving portion from the bottom portion. A curl type having an annular groove having a second curved portion that rises while curving in a vertical direction, the step of bringing the lower end of the pipe into contact with the first curved portion, and erecting the pipe of the material; And a step of applying a load toward the curved portion of No. 1.

In the curl pipe forming apparatus according to the second aspect of the present invention, the curl pipe forming apparatus is arranged such that it curls toward the bottom portion and falls down.
A curl mold including an annular groove having a curved portion and a second curved portion rising from the bottom while curving in a direction opposite to the first curved portion;
Load means for applying a load toward the curved portion of the.

In the curl pipe forming apparatus according to the third aspect of the present invention, the curl pipe forming apparatus first descends while curving toward the bottom.
Curl type having an annular groove having a curved portion and a second curved portion rising from the bottom in a direction opposite to the first curved portion, and the outer periphery of the annular groove and the bending of the pipe of material. A spacer having a wall portion arranged along the portion of the non-curved pipe between the non-curved portion and a load means for applying a load toward the first curved portion to the pipe is provided.

[0012]

According to the curl pipe forming method of the first aspect of the invention and the curl pipe forming apparatus of the second aspect of the invention, the lower end of the loaded pipe is curved along the annular groove. Therefore, the folded portion of the curl pipe is accurately formed.

Further, according to the curl pipe molding apparatus of the present invention, the position of the lower end of the pipe curved along the annular groove by the spacer is between the non-curved portion of the pipe. Are regulated so that the distance is constant.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view for explaining a curl pipe molding method according to an embodiment of the present invention. As shown in FIG. 1 (A), when the material pipe 11 is formed into a curl pipe, a curl mold 12 in which a curled concave portion (R groove) is formed in an annular shape having a predetermined diameter is used.

The inside of the R groove of the curl die 12 (the one of the two quarter circles forming a semicircle, which is closer to the core metal 15 when viewed in cross section) forms the first curved portion, and the R groove is formed. The outer side (of the two 1/4 circles forming a semicircle in the sectional view, which is farther from the core metal 15) forms the second curved portion. Second of curl type 12
The portion forming the curved portion of is called a shoulder portion 17. The height h of the shoulder portion 17 may be smaller than the curl type dimension R. That is, the upper surface of the shoulder portion 17 may be lower than the illustrated position.

A spacer 13 that can move up and down along a shaft 14 is installed on the upper portion of the curl die 12. The spacer 13 has a width smaller than the width f of the R groove,
There is an annular space with a height less than the curl height c in the product (see FIG. 1 (C)). The outer wall of the two surfaces forming the space is provided so as to be continuous from the outer side of the R groove, and the inner wall can secure a clearance a (see FIG. 1C) in the product. It is provided in the position.

Further, a cylindrical core metal 15 having a diameter corresponding to the diameter of the pipe 11 as a material and having a height larger than the length of the pipe 11 as a material is formed in the center of the R groove whose axis is annular. Will be installed to match. Then, a collar 16 which constitutes a load means together with a load applying section (not shown) is used.

Next, the curl pipe forming method will be described with reference to the explanatory view of FIG. FIG. 2 is a relationship diagram showing the relationship between the feed amount (mm) of the material pipe 11 and the load applied to the material pipe 11. First, a metal pipe (pipe 11 as a material) cut to a certain size is used as a core metal 1
5 and push in the pipe 11 until the lower end hits. Next, the collar 16 is placed on the pipe 11. Then, a load is applied to the collar 16.

Then, the lower end of the pipe 11 has a curled mold 1
It is pressed against the R groove 2 and spreads along the inside of the R groove of the curl die 12. That is, the lower end of the pipe 11 is formed into a flare shape (state during the flare forming period in FIG. 2).

When a load is further applied, the lower end of the pipe 11 curls along the outside of the R groove (the state of transition from flare to curl in FIG. 2). Then, after a period in which the pipe 11 conforms to the shape of the shoulder portion, the lower end of the pipe 11 moves inward (toward the core bar 15). Therefore, the lower end of the pipe 11 hits the inner wall of the space in the spacer 13.

Since the spacer 13 can be slid upward, when the load is further applied, the lower end of the pipe 11 pushes the spacer 13 upward (state before elastic buckling in FIG. 2). Therefore, the folded-back portion extends while the distance g between the lower end of the pipe 11 and the unprocessed portion of the pipe 11 remains constant. When the height of the folded portion reaches the desired height, the load is stopped.

When the load applied to the pipe 11 exceeds a certain value, the pipe 11 buckles. Therefore, it is necessary to complete the forming before buckling occurs. Therefore, the size of R of the product is the load when buckling occurs (buckling load)
However, there is no problem when obtaining the curl pipe used for the exhaust manifold.

In the above molding process, the clearance a in the product is secured by the spacer dimension e. The curl width b is ensured by the curl die sizes R and f. The curl height c and the total height d are determined by the total length of the material pipe 11 and the feed amount.

[0024]

As described above, according to the first aspect of the invention, the curl pipe forming method applies the material pipe to the curl mold having the annular groove having the predetermined shape defined by the shoulder portion. Since it is a method of contacting and making it stand upright and applying a load to the upright pipe, the folded portion of the curled pipe can be easily formed. At that time, the outer shape accuracy of the curl pipe is ensured by the second curved portion defined by the shoulder portion.

According to the second aspect of the present invention, the curl pipe molding device has a curl die having an annular groove having a predetermined shape defined by the shoulder portion, and the material pipe is pressed into the curl groove. With the configuration including the load means, it is possible to provide the curled pipe in which the folded-back portion can be easily formed.

According to the third aspect of the present invention, since the curl pipe molding device further comprises a spacer for controlling the position of the lower end of the material pipe, the clearance of the folded portion of the curl pipe is ensured. In particular, it is possible to provide a curled pipe in which the material pipe can be easily formed.

[Brief description of drawings]

FIG. 1 is a sectional view for explaining a curl pipe molding method according to an embodiment of the present invention.

FIG. 2 is a relationship diagram showing a relationship between a feed amount of a pipe and a load applied to the pipe.

FIG. 3 is a configuration diagram showing a configuration example of an exhaust manifold.

FIG. 4 is a perspective view showing the shapes of a curl pipe and a flare pipe.

FIG. 5 is a cross-sectional view showing a configuration of an exhaust manifold using a curl pipe.

[Explanation of symbols]

 11 Pipe 12 Curl Type 13 Spacer 15 Core Bar 16 Color 17 Shoulder Part

Claims (3)

[Claims] 1. A curl pipe molding method for molding a material pipe into a curl pipe having a folded portion at one end thereof, wherein a first curved portion that descends while curving toward a bottom portion and a first curved portion from the bottom portion. Stands upright by bringing the lower end into contact with a first curved portion of a curl mold (12) including an annular groove having a second curved portion that rises while curving in the opposite direction, and erecting the pipe. And a step of applying a load to the pipe toward the first curved portion. 2. A curl pipe molding apparatus for molding a material pipe into a curl pipe having a folded-back portion at one end, wherein a curl pipe descends while curving toward a bottom portion and a first curving portion from the bottom portion. Is a curl type (12) including an annular groove having a second curved portion which rises while curving in the opposite direction, and a load means (1) for applying a load toward the first curved portion to the pipe.
6) The curl pipe molding apparatus, which is provided with. 3. A curl pipe molding device for molding a material pipe into a curl pipe having a folded portion at one end, wherein a curl pipe descends while curving toward a bottom portion, and a first curving portion from the bottom portion. Is arranged along the pipe between the outer periphery of the annular groove and the pipe and a curl mold (12) including an annular groove having a second curved portion that rises while curving in the opposite direction. A spacer (13) having a wall portion and a load means (16) for applying a load to the pipe toward the first curved portion.
A curl pipe molding device characterized by comprising: