Metal pipe and structural member using metal pipe

• US 10,442,468 B2
• Filed: 03/28/2017
• Issued: 10/15/2019
• Est. Priority Date: 04/01/2016
• Status: Active Grant

• Current Assignee: Nippon Steel Corporation
• Original Assignee: Nippon Steel Corporation
• Inventors: Hirose, Satoshi
• Primary Examiner(s): Daniels, Jason S
• Application Number:
  US16/088,479
• Publication Number:
  US 20190118865A1
• Time in Patent Office: 931 Days
• Field of Search: 2961466, 29618709, 29618712, 293121, 293122
• CPC Class Codes: B60J 5/042 Reinforcement elements
• CPC Class Codes: B60J 5/0443 Beams
• CPC Class Codes: B60R 19/04 formed from more than one section in a side-by-side arrangement
• CPC Class Codes: B60R 19/18 characterised by the cross-section; Means within the bumper to absorb impact
• CPC Class Codes: B60R 2019/1813 made of metal
• CPC Class Codes: B62D 21/02 comprising longitudinally or transversely arranged frame members
• CPC Class Codes: B62D 21/152 Front or rear frames
• CPC Class Codes: B62D 21/157 for side impacts
• CPC Class Codes: B62D 29/007 predominantly of special steel or specially treated steel, e.g. stainless steel or locally surface hardened steel
• CPC Class Codes: C21D 9/08 for tubular bodies or pipes
• CPC Class Codes: F16F 7/12 using plastic deformation of members F16F9/30 takes precedence; yieldable means for mounting bumpers on vehicles B60R19/26; yieldable or collapsible steering columns B62D1/192
• CPC Class Codes: F16F 7/123 Deformation involving a bending action, e.g. strap moving through multiple rollers, folding of members F16F7/125, F16F7/128 take precedence
• CPC Class Codes: F16F 7/128 characterised by the members, e.g. a flat strap, yielding through stretching, pulling apart

Abstract

A metal pipe has a circular cross section with an outer diameter D and a length not less than 6D. The metal pipe includes a high-strength portion (1A) and low-strength portions (1B). The high-strength portion (1A) is disposed along the entire circumference of the metal pipe to extend a dimension, as measured in the longitudinal direction of the metal pipe, that is not less than (⅔)D and not more than 3D of the metal pipe. The high-strength portion (1A) has a yield strength not less than 500 MPa (or a tensile strength not less than 980 MPa). The low-strength portions (1B) are disposed along the entire circumference of the metal pipe to be arranged in the longitudinal direction of the metal pipe to sandwich the high-strength portion (1A). The low-strength portions (1B) have a yield strength of 60 to 85% of that of the high-strength portion (1A).

Claims

1. A metal pipe comprising:

a circular cross section with an outer diameter D and a length not less than 6D,

the metal pipe further comprising;

a high-strength portion disposed along an entire circumference of the metal pipe to extend a dimension, as measured in a longitudinal direction of the metal pipe, that is not less than ⅔

D and not more than 4/3D, the high-strength portion having a yield strength not less than 500 MPa; and

low-strength portions disposed along the entire circumference of the metal pipe to be arranged in the longitudinal direction of the metal pipe to sandwich the high-strength portion, the low-strength portions having a yield strength of 60 to 85% of that of the high-strength portion.

2. The metal pipe according to claim 1, wherein a dimension of the low-strength portions as measured in the longitudinal direction of the metal pipe is not less than ⅗

D.

3. The metal pipe according to claim 1, wherein the high-strength portion is located in a middle of the metal pipe as determined along the longitudinal direction.

4. The metal pipe according to claim 1, wherein the metal pipe is curved.

5. A vehicle body, bumper or vehicle door comprising:

a metal pipe having a circular cross section with an outer diameter D, the metal pipe further comprising;

connections configured to be connected to another member, the connections being portions of the metal pipe located at two positions separated from each other by 6D or more in a longitudinal direction of the metal pipe;

a high-strength portion disposed between the connections along an entire circumference of the metal pipe to extend a dimension, as measured in the longitudinal direction, that is not less than ⅔

D and not more than 4/3D, the high-strength portion having a yield strength not less than 500 MPa; and

low-strength portions disposed along the entire circumference of the metal pipe to be arranged in the longitudinal direction of the metal pipe to sandwich the high-strength portion, the low-strength portions having a yield strength of 60 to 85% of that of the high-strength portion.

6. The vehicle body, bumper or vehicle door according to claim 5, wherein a dimension of the low-strength portions of the metal pipe as measured in the longitudinal direction of the metal pipe is not less than ⅗

D.

7. The vehicle body, bumper or vehicle door according to claim 5, wherein the high-strength portion of the metal pipe is located midway between the two connections.

8. The vehicle body, bumper or vehicle door according to claim 5, wherein the metal pipe is curved to be convex toward an outside of a vehicle.

9. The vehicle body according to claim 5, wherein the vehicle body has a space-frame structure.