Welding joining method and welding joined body

Patent metadata

Field	Value
Publication number	US-2021170695-A1
Application number	US-202017028076-A
Country	US
Kind code	A1
Filing date	Sep 22, 2020
Priority date	Dec 10, 2019
Publication date	Jun 10, 2021
Grant date	—

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.

6 . A welding joined body including a joined portion obtained by bonding, by pressure, end portions of tubular members made of crystalline resin to each other in a molten state, wherein:
a weld bead remains in a vicinity of the joined portion, the weld bead being discharged from the joined portion in pressure bonding such that the weld bead projects inwardly in a tubular radial direction; a rate of change in crystallinity in the tubular radial direction in a belt-shaped predetermined region extending outwardly in the tubular radial direction when the predetermined region is viewed in a circumferential direction is a predetermined value or less, the predetermined region being set in a corresponding one of the tubular members so as to start from a boundary portion between the weld bead and an inner peripheral surface of the corresponding one of the tubular members.

7 . The welding joined body according to claim 6 , wherein:
when a belt-shaped region extending in the tubular radial direction when the belt-shaped region is viewed in the circumferential direction is taken as a large region, the belt-shaped region being set in the corresponding one of the tubular members so as to include the boundary portion between the weld bead and the inner peripheral surface of the corresponding one of the tubular members, a plurality of regions obtained by equally dividing the large region in the tubular radial direction is taken as medium regions, a plurality of regions obtained by equally dividing each of the medium regions in a tubular axial direction such that the regions are arranged in the tubular axial direction is taken as small regions, and a value obtained by adding up crystallinities of the small regions included in the each of the medium regions is taken as a crystallinity of the each of the medium regions, the predetermined region is set in a range, in the large region, which starts from the boundary portion and in which crystallinities of the medium regions linearly change in the tubular radial direction; and the rate of change in crystallinity is an inclination of an approximate straight line obtained by linearly approximating the crystallinities changing linearly within the predetermined region.

Assignees

• Toyota Motor Co Ltd

Inventors

• Baba Youichiro

Classifications

• B29C65/1412

  Infrared [IR] radiation · CPC title

• B29C66/1142

  Single butt to butt joints · CPC title

• B29C65/8253

  by the use of waves or particle radiation, e.g. visual examination, scanning electron microscopy, or X-rays (B29C65/8292 takes precedence) · CPC title

• B29C66/73921

  characterised by the materials of both parts being thermoplastics · CPC title

• B29C65/1432

  direct heating of the surfaces to be joined · CPC title