JPH0761500B2 - Double tube manufacturing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for manufacturing a double pipe.

[Prior art]

Conventionally, as a method of manufacturing an outer cylinder of a silencer for an internal combustion engine, two front and back laminated plates 1 and 2 as shown in FIG. 2A are wound around a lock seam core metal 3 as shown in FIG. A method for forming a pipe 5 as shown in FIG. 3C by performing lock seam processing on both joint ends 4, or winding one inner plate 6 as shown in FIG. Edge 7
After the lock seam processing to form the inner pipe 8, this is removed from the lock seam core metal 3 and the assembly parts of the partition plate 9 and the inner pipe 10 are internally mounted on this inner seam. A method for manufacturing a double pipe by mounting both joint ends 7 on a processing machine in an inverted state, winding another outer plate 12 around the outer periphery of the inner pipe 8 and performing lock seam processing on the joints 13 at both ends thereof. There is.

[Problems to be solved by the present invention]

As shown in FIG. 2, in the case where the lock seams are simultaneously performed at one place in the state of the two stacked plates, there is a problem that when the backfire occurs, the joint portion 4 is disengaged due to the high internal pressure and the silencer is damaged. .

Also, as shown in FIG. 3, the joints 7, 13 between the inner cylinder 8 and the outer pipe 12
In the case of 180 ° offset, the outer surface of the joint portion 7 of the inner pipe 8 is pressed against the non-joint portion of the outer pipe 12, so that the joint portion 7 can withstand even a high internal pressure when a backfire occurs. Although the above problems can be solved by this, the lock seam processing machine requires two kinds for manufacturing the inner pipe and the outer pipe, and the equipment cost becomes expensive, and another lock is required after the inner pipe is formed. Since it has to be set on the seam processing machine, there is a problem that work efficiency is poor.

Therefore, according to the present invention, as described above, the joint portions of the inner and outer pipes are
It is an object of the present invention to propose a method for producing a double pipe in which a double pipe having a 0 ° phase can be produced by one lock seam processing machine.

[Means for Solving the Problems]

In order to solve the above problems, the present invention wraps an inner plate around a core metal of a lock seam processing machine, connects both joint ends of the inner plate with a lock seam mechanism, and then wraps the inner plate. After rotating the cored bar in a state by a predetermined amount, another outer plate is wound around the outer periphery of the inner plate wound around the cored bar, and the amount joint end of the outer plate is connected by the lock seam mechanism. It is a method of manufacturing a double pipe, which is characterized in that

〔Example〕

Next, the manufacturing method of the present invention will be described with reference to FIG.

First, as shown in FIG. 1 (A), a flat plate-shaped inner plate 14 is cut and formed from a rolled plate material. Next, the inner plate 14 is set on a lock seam processing machine and wound around the core metal 15 from below. Next, the both end joints 16 of the wound inner plate 14 are wound and connected by a lock seam mechanism 15a to form an inner tube 14 '. Next, the cored bar 15 with the inner tube 14 'still set is inverted as shown in (C). Next, another flat plate-shaped outer plate 17 is wound around the cored bar 15 in the inverted state from below to the outer periphery of the inner tube 14 ', and both end joints 18 thereof are tightened by the same lock seam mechanism 15a as described above. Connect
Form the outer tube 17 '. Connect both inner and outer tubes 14 ', 17' to the core metal 1
By removing from 5, an inner and outer double pipe is formed.

The lock seam core metal 15 may be a round shape, an elliptical shape, or another irregular shape depending on the type of pipe to be formed. The relative positions of the joints 16 and 18 of the inner and outer tubes 14 'and 17' are as described above.
It is desirable to make a 180 ° phase, but the phase angle may be other than 180 °.

〔The invention's effect〕

As described above, according to the present invention, by rotating the core metal, the inner and outer double pipes in which the joint ends of the pipes are mutually phased can be manufactured by one lock seam processing machine. The equipment cost is much lower than that using the lock seam processing machine. Moreover, since the outer tube can be formed by winding the inner tube around the cored bar, work efficiency can be improved and productivity can be improved as compared with the conventional one in which the inner tube is once removed from the cored bar.

[Brief description of drawings]

FIG. 1 is a diagram showing a manufacturing process of the present invention, and FIGS. 2 and 3 are diagrams showing two examples of conventional manufacturing processes. 14 …… Inner plate, 14 ′ …… Inner tube, 15 …… Core bar, 16,18 …… Joint part, 17 ′ …… Outer tube

Claims (1)

[Claims] 1. An inner plate is wound around a core metal of a lock seam processing machine, both joint ends of the inner plate are connected by a lock seam mechanism, and then the core metal in a state where the inner plate is wound is predetermined. After rotating both times, another outer plate is wound around the outer periphery of the inner plate wound around the core metal, and both joint ends of the outer plate are connected by the lock seam mechanism. Pipe manufacturing method.