JPS5917313B2 - Pipe end connection head structure in double-wound steel pipe and its forming method - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to refueling in vehicles, pattern equipment, and other various devices.
This invention relates to a pipe end connection head of a double-wound steel pipe used as a supply path for air supply, etc., and a method for forming the same.

As shown in FIGS. 1 and 2, the double-wound steel pipe 1 generally has a depth of about 0 at the end edge of the winding over the length of the pipe during forming.
．． A linear depression 2 of about 0.7 mm to 0.1 mm is inevitably formed.

As shown in FIG. 6, the pipe end connection head of the conventional double-wound steel pipe 11 is made by expanding the pipe end of the cut double-wound steel pipe 11 by pressing from the outside of the pipe end in the axial direction. Since the protruding head 13 is formed, these linear depressions 2 remain on the pressing sheet surface 14 after the connection head is formed, and therefore, when the protruding head 13 is pressed against the open opening surface of the mating mounting base, the protruding head 13 is formed. There was a tendency for leakage to occur through the linear depressions 2 in the pressed sheet surface 14.

In addition, in the conventional connection head forming method, as shown in FIG. 6, an annular groove 15 is formed near the tip of the pressing sheet surface 14, and the leading edge connected to this forms a protrusion 16 on the outside, so that the pressing sheet surface 14 has an uneven shape, which poses a problem of inducing leakage from the uneven portions.

Furthermore, since it is necessary to tighten with an excessive tightening torque due to the above-mentioned leakage tendency at the pressing sheet surface 14, there is a drawback that the bulging head 13 is deformed into a flat shape.

The present invention very effectively solves this problem, and includes a pipe end connection head for a double-wound steel pipe that can completely prevent leakage from the suppression sheet surface with a relatively small tightening torque, and a method for manufacturing the same. It provides:

The pipe end connection head structure of the double-wound steel pipe according to the present invention is as follows:
The pressing seat surface of the connection bulge head provided at the end of the double-wound steel pipe is a smooth inclined surface consisting of a tapered thin-walled wall structure that slopes toward the end, making it secure even with relatively small tightening torques. It can be tightened to prevent leakage from the suppression sheet surface.

Further, in the method for forming a pipe end connection head of a double-wound steel pipe according to the present invention, the outer circumferential surface near the pipe end of the double-wound steel pipe is
A tapered, thin-walled, smooth sloped surface that slopes toward the tube end is processed to eliminate linear depressions, and then the tube end is press-processed from the outside of the tube end in the axial direction to create the smooth surface. Because it is molded into a bridge-like bulging head with an inclined surface as a pressed sheet surface,
The wall thickness tapers toward the tube end, which also prevents leakage due to the annular groove and uneven shape of the pressing sheet surface.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. As shown in FIG. When the pressed sheet surface 4 of the double-wound steel pipe is in the state of a double-wound steel pipe, the outer circumferential surface 1' near the end of the pipe is cut or drawn by a punch member to form a thin tapered wall that slopes toward the end of the pipe. It is formed with a smooth surface made of walls.

That is, the pressing sheet surface 4 of the tube end connection head according to the present invention is formed as a smooth surface with no linear depression 2 due to the winding end edge and no unevenness on the tip edge, and its wall thickness is equal to that of the tube end. It has a wall structure that gradually tapers toward the sides.

4 and 5 are explanatory views of the processing steps related to the method of forming the pipe end connection head, in which the double-wound steel pipe 1 of FIG.
As shown in the figure, the outer circumferential surface 1' near the tube end, which corresponds to the pressing sheet surface after the bulging head is formed, is cut in advance with a cutter member or drawn with a punch member 5, so that the outer peripheral surface 1' is turned toward the tube end side. It is processed into a tapered, thin-walled, smooth inclined surface 4'.

Therefore, no linear depression at the winding end edge remains on the smooth inclined surface 4'.

Next, as shown in FIG. 5, the vicinity of the tube end of the double-wound steel pipe 1 processed into a smooth inclined surface is pressed with a chuck 6' for forming a bulging head and a punch member 7 so that the smooth inclined surface 4' is pressed into a sheet. Pressing is performed from the outside of the tube end in the axial direction so as to position it on the surface 4, and the tube is formed into a bridge-like bulging head as shown in FIG.

Examples of the connecting head forming method according to the present invention will be shown below.

Double-wound steel pipe...Material: 5pcc-i Dimensions: Outer diameter: 8.0mm Wall thickness: 0.7mm Length: 750mm Smooth sloped surface processing Pipe end of the above double-wound steel pipe (suppressing sheet after bulging head molding) (corresponding to the surface) is processed by crank-type drawing press processing to create an inclination angle of 20 degrees and a tip wall thickness of 0. : Forming a bulging head on a smooth slope of 3++ m. With a machining allowance of 7.0 mm for the tube end, the bulging head was molded using a crank press method. As a result, a linear depression was formed at the end edge of the winding end. A bulged head having an outer diameter of 10.7 mm and a head height of 6.211!7+1 was obtained, which had a smooth pressed sheet surface with no unevenness at the tip edge.

In the pipe end connection head of the double-wound steel pipe according to the present invention, the pressing sheet surface 4 is formed as a smooth surface without linear depressions or uneven shapes, and the pressing sheet surface is configured to have a tapered thin wall structure. Therefore, even with a relatively small tightening torque, it is possible to reliably prevent leakage from the 4 parts of the pressing sheet surface, and also to eliminate flattening deformation of the bulging head due to tightening, and various other excellent effects can be obtained. .

[Brief explanation of the drawing]

Fig. 1 is a side view of a double-wound steel pipe, Fig. 2 is an enlarged partial cross-sectional view of Fig. 1, and Fig. 3 is a side view including a partial cross section of the connecting head of the double-wound steel pipe at both ends according to the present invention. , 4 and 5 are process views for forming the connecting head of the present invention, and FIG. 6 is a partial sectional view of a conventional connecting head. 1...Double-wound steel pipe, 1'...Outer peripheral surface near the pipe end, 3
...Bulging head, 4'... Smooth inclined surface, 4... Pressing sheet surface.

Claims (1)

[Claims] 1. The pressing sheet surface 4 of the connecting bulging head 3 provided at the tube end of the double-wound tube 1 is made into a smooth inclined surface consisting of a tapered thin wall structure that slopes toward the tube end. Pipe end connection head structure 2 for a double-wound steel pipe, characterized in that the outer circumferential surface 1' of the double-wound steel pipe 1 near the pipe end is preliminarily formed with a tapered thin-walled smooth inclined surface that slopes toward the pipe end. Processed into 4′,
Thereafter, the tube end side is subjected to a compression process from the outside of the tube end in the axial direction to form a bridge-like bulging head 3 with the smooth inclined surface 4' as the compression sheet surface 4. A method for forming a pipe end connection head in a double-wound steel pipe.