Method for producing press-formed product

Patent metadata

Field	Value
Publication number	US-9358602-B2
Application number	US-201113877105-A
Country	US
Kind code	B2
Filing date	Sep 30, 2011
Priority date	Sep 30, 2010
Publication date	Jun 7, 2016
Grant date	Jun 7, 2016

Abstract

There is provided a useful method for producing a press-formed product without making the structure of a press tool complicated, which product has favorable formability in a level so as to be able to be produced by deep drawing, and which product is produced by press-forming a thin steel sheet with a punch and a die, in which the thin steel sheet is heated to a temperature not lower than an Ac 3 transformation point thereof, and the press-forming is then started, wherein the forming is carried out so that a temperature difference in the thin steel sheet is adjusted to be not higher than 200° C. at a stage when the thin steel sheet has reached one third of a forming height.

First claim

The invention claimed is:

1. A method for producing a formed product by press-forming a thin steel sheet with a punch and a die, comprising:
heating the thin steel sheet to a temperature not lower than an Ac 3 transformation point thereof;
then starting the press-forming; and
cooling the thin steel sheet after starting the press-forming,
wherein the press-forming is carried out so that a temperature difference between different areas of the thin steel sheet is adjusted via the cooling to be not higher than 200° C. at a stage when the thin steel sheet has reached one third of a forming height, and the press-forming is carried out so that the time from the start of the press-forming to the finish of the press-forming is adjusted to be not longer than 0.3 seconds.

2. The production method according to claim 1 , wherein the press-forming is carried out by drawing with a blank holder.

3. The production method according to claim 1 , wherein the cooling comprises controlling a forming start temperature, a temperature of the punch and a temperature of the die.

4. The production method according to claim 1 , wherein the cooling comprises controlling a forming rate.

5. The production method according to claim 1 , wherein the cooling comprises decreasing a heat transfer coefficient between the thin steel sheet, the punch and the die.

6. The production method according to claim 1 , wherein the cooling comprises the press-forming of the thin steel sheet while cooling portions of the thin steel sheet not in contact with a blank holder.

7. A method for producing a formed product by press-forming a thin steel sheet with a punch and a die, comprising:
heating the thin steel sheet to a temperature not lower than an Ac 3 transformation point thereof;
performing a first cooling to the thin steel sheet;
then starting the press-forming; and
performing a second cooling to the thin steel sheet after starting the press-forming,
wherein the press-forming is started at a temperature higher than a martensitic transformation start temperature Ms of the thin steel sheet and not higher than 800° C., and the press-forming is carried out so that a temperature difference between different areas of the thin steel sheet is adjusted via the second cooling to be not higher than 200° C. at a stage when the thin steel sheet has reached one third of a forming height.

8. The production method according to claim 7 , wherein the press-forming is carried out by drawing with a blank holder.

9. The production method according to claim 7 , wherein the second cooling comprises controlling a forming start temperature, a temperature of the punch and a temperature of the die.

10. The production method according to claim 7 , wherein the second cooling comprises controlling a forming rate.

11. The production method according to claim 7 , wherein the second cooling comprises decreasing a heat transfer coefficient between the thin steel sheet, the punch and the die.

12. The production method according to claim 7 , wherein the second cooling comprises the press-forming of the thin steel sheet while cooling portions of the thin steel sheet not in contact with a blank holder.

13. A method of producing a formed product by press-forming a thin steel sheet with a punch and a die, comprising:
heating the thin steel sheet to a temperature not lower than an Ac 3 transformation point thereof;
performing a first cooling to the thin steel sheet;
then start the press-forming; and
performing a second cooling to the thin steel sheet after starting the press-forming,
wherein the press-forming is started at a temperature not higher than a martensitic transformation start temperature Ms of the thin steel sheet, and the press-forming is carried out so that a temperature difference between different areas of the thin steel sheet is adjusted via the second cooling to be not higher than 200° C. at a stage when the thin steel sheet has reached one third of a forming height.

14. The production method according to claim 13 , wherein the press-forming is carried out by drawing with a blank holder.

15. The production method according to claim 13 , wherein the second cooling comprises controlling a forming start temperature, a temperature of the punch and a temperature of the die.

16. The production method according to claim 13 , wherein the second cooling comprises controlling a forming rate.

17. The production method according to claim 13 , wherein the second cooling comprises decreasing a heat transfer coefficient between the thin steel sheet, the punch and the die.

18. The production method according to claim 13 , wherein the second cooling comprises the press-forming of the thin steel sheet while cooling portions of the thin steel sheet not in contact with a blank holder.

Assignees

• Naitou Junya
• Okita Keisuke
• Ikeda Shushi
• Kobe Steel Ltd

Inventors

• Naitou Junya
• Okita Keisuke
• Ikeda Shushi

Classifications

• B21D22/208

  by heating the blank or deep-drawing associated with heat treatment (C21D takes precedence) · CPC title

• B21D24/02

  Die-cushions · CPC title

• B21D37/16 Primary

  Heating or cooling · CPC title

• B21D24/04

  Blank holders; Mounting means therefor · CPC title

• B21D22/20

  Deep-drawing (special deep-drawing arrangements in, or in connection with, presses B21D24/00) · CPC title