Manufacturing method for bent member and hot-bending apparatus for steel material

Patent metadata

Field	Value
Publication number	US-10543519-B2
Application number	US-201515313310-A
Country	US
Kind code	B2
Filing date	May 27, 2015
Priority date	May 27, 2014
Publication date	Jan 28, 2020
Grant date	Jan 28, 2020

Abstract

A manufacturing method for a bent member of the present invention includes a holding step of holding one end portion of a long steel material having an opening end in a longitudinal direction by a chuck, a feeding step of feeding the steel material in the longitudinal direction with the one end portion as a head after the holding step, a heating step of performing high-frequency induction heating on a portion of the steel material in the longitudinal direction to form a heated portion, a bending step of moving the chuck in a three-dimensional direction to apply a bending moment to the heated portion, and a cooling step of injecting a cooling medium to the heated portion to cool the heated portion after the bending step. When the heating step is started, the chuck is cooled by the cooling medium in a state where a heating amount applied to the one end portion when the heated portion is formed on the one end portion is greater than that of an upstream side adjacent portion adjacent to the upstream side of the one end portion as seen along a feeding direction of the steel material.

First claim

The invention claimed is:

1. A manufacturing method for a bent member, comprising the steps of:
a holding step of holding one end portion of a long steel material having an opening end in a longitudinal direction by a chuck;
a feeding step of feeding the steel material along the longitudinal direction with the one end portion as a head after the holding step;
a heating step of forming a heated portion by high-frequency induction heating to an exterior portion of the steel material in the longitudinal direction;
a bending step of applying a bending moment to the heated portion by moving the chuck in a three-dimensional direction; and
a cooling step of cooling the heated portion by injecting a cooling medium to the heated portion after the bending step,
wherein when the heating step is started,
the chuck is cooled by the cooling medium, and
a heating amount, which is applied to the one end portion when the heated portion is formed on the one end portion, is greater than that of an upstream side adjacent portion which is adjacent to an upstream side of the one end portion as seen along a feeding direction of the steel material,

wherein a part of the chuck is located in an interior of the steel member when the heating step is started.

2. The manufacturing method for a bent member according to claim 1 ,
wherein the heating amount applied to the one end portion when the heated portion is formed on the one end portion is greater than that of the upstream side adjacent portion when the heating step is started by changing at least one of a feeding speed of the steel material in the longitudinal direction in the feeding step and a heating amount which is applied to the portion in the heating step.

3. The manufacturing method for a bent member according to claim 1 ,
wherein the heating amount applied to the one end portion when the heated portion is formed on the one end portion is greater than that of the upstream side adjacent portion by starting the feeding step after a predetermined time from the heating step is started.

4. The manufacturing method for a bent member according to claim 1 , further comprising:
a temperature measuring step of measuring a temperature of the steel material at a plurality of points in the longitudinal direction,
wherein in the feeding step, a feeding speed of the steel material in the longitudinal direction is determined based on a temperature measurement result obtained in the temperature measuring step.

5. The manufacturing method for a bent member according to claim 1 ,
wherein a heating amount applied to the other end portion of the steel material in the longitudinal direction when the heated portion is formed on the other end portion is greater than that of a downstream side adjacent portion adjacent to a downstream side of the other end portion as seen along the feeding direction of the steel material.

6. The manufacturing method for a bent member according to claim 5 ,
wherein the heating amount applied to the other end portion when the heated portion is formed on the other end portion is greater than that of the downstream side adjacent portion by changing at least one of a feeding speed of the steel material in the longitudinal direction in the feeding step and a heating amount in the heating step before the high-frequency induction heating stops in the heating step.

7. The manufacturing method for a bent member according to claim 6 ,
wherein the heating amount applied to the other end portion when the heated portion is formed on the other end portion is greater than that of the downstream side adjacent portion by stopping a feeding of the steel material in the feeding step before the high-frequency induction heating stops.

8. The manufacturing method for a bent member according to claim 1 ,
wherein a heating amount in the heating step is controlled to satisfy all the conditions of:
a first condition in which a heating temperature of a click of the chuck is 500° C. or lower;
a second condition in which a heating temperature of the heated portion is higher than an Ac3 point when the bending moment is applied to the heated portion in the bending step; and
a third condition in which a highest arrival temperature of the steel material is lower than or equal to a temperature at which a particle-coarsening of the steel material proceeds or is lower than or equal to a temperature at which a toughness of the steel material decreases.

9. The manufacturing method for a bent member according to claim 1 ,
wherein the heating step includes:
a first heating step of forming a first heated portion at a position between the one end portion and the other end portion of the steel material;
a second heating step of forming a second heated portion at a position on the upstream side of the first heated portion of the steel material; and
a heating stop step of forming a non-quenching portion between the first heated portion and the second heated portion, by stopping the high-frequency induction heating between the first heating step and the second heating step,
wherein a heating amount which is applied to the second heated portion is greater than a heating amount which is applied to the first heated portion when the second heating step is started.

10. The manufacturing method for a bent member according to claim 9 ,
wherein a width dimension of the non-quenching portion is 0.15 times or more and 1.40 times or less of a heating width by the high-frequency induction heating as seen along the longitudinal direction.

11. A hot-bending apparatus for a steel material, comprising:
a chuck which holds one end portion of a long steel material having an opening end in a longitudinal direction;
a drive mechanism which moves the chuck in a three-dimensional direction;
a feeding mechanism which feeds the steel material along the longitudinal direction with the one end portion as a head;
an induction heating mechanism which performs high-frequency induction heating on an exterior portion of the steel material in the longitudinal direction to form a heated portion;
a cooling mechanism which injects a cooling medium to the heated portion to cool the heated portion; and
a controller which controls the chuck, the drive mechanism, the feeding mechanism, the induction heating mechanism, and the cooling mechanism,
wherein when the heated portion is formed on the one end portion by the induction heating mechanism the controller controls to satisfy the conditions of:
a heating amount is greater than that of an upstream side adjacent portion adjacent to an upstream side of the one end portion as seen along a feeding direction of the steel material; and
the cooling mechanism cools the chuck by the cooling medium, and

wherein a part of the chuck is located in an interior of the steel material when the high-frequency induction heating is started.

12. The hot-bending apparatus for a steel material according to claim 11 ,
wherein the controller controls to cause a heating amount applied to the other end portion of the steel material in the longitudinal direction by the induction heating mechanism to be greater than that of a downstream side adjacent portion adjacent to a downstream side of the other end portion as seen along the feeding direction of the steel material when the heated portion is formed on the other end portion.

13. The hot-bending apparatus for a steel material according to claim 11 ,
wherein the controller controls the induction heating mechanism to form:
a first heated portion at a position between the one end portion and the other end portion of the steel material;
a second heated portion at a positi

Assignees

• Nippon Steel & Sumitomo Metal Corp
• Nippon Steel Corp

Inventors

• Okada Nobuhiro
• Kubota Hiroaki
• Tomizawa Atsushi

Classifications

• B21D9/04 Primary

  the mandrel being rigid · CPC title

• B21D37/16

  Heating or cooling · CPC title

• B21D7/16 Primary

  Auxiliary equipment, e.g. for heating or cooling of bends · CPC title

• B21D7/08

  by passing between rollers or through a curved die · CPC title

• B21D7/162 Primary

  Heating equipment · CPC title