Welding joining method and welding joined body

Patent metadata

Field	Value
Publication number	US-11235535-B2
Application number	US-202017028076-A
Country	US
Kind code	B2
Filing date	Sep 22, 2020
Priority date	Dec 10, 2019
Publication date	Feb 1, 2022
Grant date	Feb 1, 2022

Abstract

Provided is a welding joining method for joining end portions of first and second pipes made of polyamide resin by bonding the end portions to each other by pressure in a molten state. The welding joining method includes: a placing step of placing an infrared radiation lamp between the first and second pipes placed to face each other at an interval; a heating and melting step of heating and melting the end portions of the first and second pipes by emitting infrared; and a pressure bonding step of cooling down the molten end portions in a state where the molten end portions are bonded to each other by pressure.

First claim

What is claimed is:

1. A welding joining method for joining end portions of tubular members made of crystalline resin by bonding the end portions to each other by pressure in a molten state, the welding joining method comprising:
preparing an infrared emission unit configured to change characteristics of infrared to be emitted;
a placing step of placing the infrared emission unit between the end portions of the tubular members, the end portions being placed to face each other at an interval in a tubular axial direction;
a heating and melting step of heating and melting the end portions of the tubular members by emitting the infrared from the infrared emission unit; and
a pressure bonding step of cooling down the molten end portions of the tubular members in a state where the end portions are bonded to each other by pressure, wherein:
in the heating and melting step, the characteristics of the infrared emitted from the infrared emission unit are controlled so that a crystallinity along a tubular radial direction in a region starting from a boundary portion in a welding joined body after cooling does not suddenly change, the boundary portion being a part between a peripheral surface of a corresponding one of the tubular members and a weld bead discharged from a joined portion in pressure bonding such that the weld bead projects in the tubular radial direction.

2. The welding joining method according to claim 1 , wherein:
the infrared emission unit is an infrared radiation lamp configured to change an output of the infrared to be emitted from a low output to a high output by changing a power supply amount; and
the heating and melting step includes
a heating step of heating the end portions of the tubular members by emitting low-output infrared from the infrared radiation lamp for a first predetermined time, and
a melting step of, after the heating step, melting the end portions of the tubular members by emitting high-output infrared from the infrared radiation lamp for a second predetermined time.

3. The welding joining method according to claim 2 , wherein the first predetermined time is 60 to 90 seconds, and the second predetermined time is 5 to 30 seconds.

4. The welding joining method according to claim 1 , wherein:
the infrared emission unit is configured to change a peak of a wavelength of the infrared to be emitted from a near-infrared region to a far-infrared region; and
the heating and melting step includes
a heating step of heating the end portions of the tubular members by mainly emitting far-infrared from the infrared emission unit for a predetermined time, and
a melting step of, after the heating step, melting the end portions of the tubular members by mainly emitting near-infrared from the infrared emission unit for a time shorter than the predetermined time.

5. The welding joining method according to claim 2 , wherein, in each of the end portions of the tubular members, a heating range heated in the heating step is wider than a melting range melted in the melting step.

Assignees

• Toyota Motor Co Ltd

Inventors

• Baba Youichiro

Classifications

• F16L47/02 Primary

  Welded joints; Adhesive joints · CPC title

• H05B2203/032

  Heaters specially adapted for heating by radiation heating · CPC title

• B29C65/1432

  direct heating of the surfaces to be joined · CPC title

• B29C65/1419

  Mid-infrared radiation [MIR] · CPC title

• B29C66/91411

  of the parts to be joined, e.g. the joining process taking the temperature of the parts to be joined into account · CPC title