Manufacturing method for double tube having a hole formed therein, and mold for implementation thereof
View Patent ↗To provide manufacturing method for a double tube having a hole formed therein and a mold for implementing such method, which reduce the time required for manufacturing, do not leave shavings in the gap between the outer tube and the inner tube, and offer highly accurate hole positioning. The manufacturing method for a double tube having a hole formed therein pertaining to the present invention uses a mold in which a punch is located in at least one of the split mold halves that form the outer circumferential surface, an indentation is formed by drawing the punch into the mold, and fluid pressure is applied between the outer tube and the inner tube of the double tube located within the mold to form a hole in the circumferential wall of the outer tube via such indentation. Furthermore, the punch is placed in the mold in a watertight fashion.
1. A manufacturing method for a double tube having inner and outer tubes with a hole formed in the outer tube, which comprises:
forming the double tube;
placing the formed double tube into a mold having two split mold halves, where a punch is located in at least one of the split mold halves that form an outer circumferential surface of the mold;
forming an indentation by drawing said punch into said mold;
applying fluid pressure between the outer tube and the inner tube of the double tube located within the mold, and forming the hole in the circumferential wall of said outer tube by means of such indentation.
2. The manufacturing method for a double tube having a hole formed therein according to claim 1 , wherein said outer tube is caused to expand in diameter by said fluid pressure.
3. A manufacturing method for a double tube having a hole formed therein, wherein such method uses a mold in which a punch is located in at least one of the split mold halves that form an outer circumferential surface of the mold, an indentation is formed by drawing said punch into said mold, fluid pressure is applied between the outer tube and the inner tube of the double tube located within the mold, and a hole is formed in the circumferential wall of said outer tube by means of such indentation, and said indentation is formed before said fluid pressure is applied between said outer tube and said inner tube.
4. The manufacturing method for a double tube having a hole formed therein according to claim 3 , wherein said outer tube is caused to expand in diameter by said fluid pressure.
5. A manufacturing method for double tube having inner and outer tubes with a hole formed in the outer tube, which comprises:
forming the double tube;
placing the formed double tube into a mold having two split mold halves, where a punch is located in at least one of the split mold halves that form an outer circumferential surface of the mold;
applying fluid pressure between the outer tube and the inner tube of the double tube located within the mold; and
forming the hole by means of an indentation after said fluid pressure is applied between said outer tube and said inner tube.
6. The manufacturing method for a double tube having a hole formed therein according to claim 5 , wherein said outer tube is caused to expand in diameter by said fluid pressure.
7. The manufacturing method for double tube having a hole formed therein according to claim 5 , wherein said indentation is formed by a punch protruding into said mold by an amount less than the thickness of the circumferential wall of the said outer tube, and then a hole is formed in the circumferential wall of said outer tube by drawing said punch into said mold.
8. The manufacturing method for a double tube having a hole formed therein according to claim 7 , wherein said outer tube is caused to expand in diameter by said fluid pressure.