Method for making metal pipe with eccentric expanded open end
A manufacturing method, open end technology, applied in the direction of metal extrusion dies, etc., can solve the problems of reducing mechanical strength, crack cross section, shrinkage, etc.
Inactive Publication Date: 2002-05-01
NISSHIN STEEL CO LTD
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Problems solved by technology
This thin wall creates problems such as cracks or section shrinkage
Locally thinned walls also reduce the mechanical strength of the product
Method used
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[0026] As the raw metal pipe M, a high-frequency welded metal pipe having an outer diameter of 25.4 mm, a wall thickness of 1.0 mm, and a length of 350 mm was used. By forcibly inserting the coaxial expansion punch 10 into the open end of the original metal pipe M, the open end of the original metal pipe M is plastically deformed into a coaxially expanded state M 1 . Afterwards, by forcibly inserting the eccentric expansion punch 20 into the coaxial expansion opening M 1 Make the coaxial expansion open end M 1 Plastic deformation into a state of eccentric expansion M 2 . The open end of the raw metal tube M is expanded coaxially and then eccentrically by means of punches 10, 20 made of hardened tool steel, which are drawn in four steps under the conditions shown in Table 1. Lubricant diffuses into these punches.
[0027]
Combination of working modes
coaxial expansion
open end step
eccentric expansion
open end step
first step
se...
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Abstract
A method of manufacturing a metal pipe with an eccentrically expanded open end comprises the steps of plastically deforming to a coaxially expanded state so that an axial wall length at a side to be eccentrically expanded is longer than an axial wall length at the opposite side to be expanded without eccentricity. The coaxially expanded open end is then plastically deformed to an eccentrically expanded state by forcibly inserting an eccentrically expanding punch into the coaxially expanded open end. The eccentrically expanding punch has a boundary between a conical tip and a cylindrical body inclined with a predetermined angle theta so as to bring the cylindrical body into contact with an inner wall of the coaxially expanded open end at a side to be eccentrically expanded earlier than the opposite side to be expanded without eccentricity. When the coaxially expanded open end is plastically deformed to an eccentrically expanded state, metal flow is suppressed at a side to be eccentrically expanded, but metal flow from the opposite side to be expanded without eccentricity to the former side is promoted. Consequently, the open end is plastically deformed to the eccentrically expanded state without any thickness deviation along a circumferential direction.
Description
technical field [0001] The invention relates to a method of manufacturing a metal tube having an open end that is eccentrically flared with respect to its axis. Background technique [0002] A metal tube with an eccentrically flared open end used as a supply line for automotive fuel, etc. Hitherto, such metal tubes have been manufactured by expanding the open end of the raw metal tube, or by joining one metal tube with an extruded open end to another metal tube with an expanded open end. However, this process is too complicated, resulting in an increase in manufacturing cost. In this regard, different methods have been tried, such as radially expanding the raw metal tube at its open end by forced insertion of a conical expanding punch. [0003] In conventional expansion methods, an expansion punch is forcibly inserted into a raw metal tube 1 with an open end perpendicular to its axis, as in figure 1 shown. The open end is plastically deformed into the coaxially expanded ...
Claims
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IPC IPC(8): B21C37/16B21D41/02
CPCB21D41/02B21C37/16
Inventor 大塚雅人石川半二
Owner NISSHIN STEEL CO LTD