Vehicle bumper beam with varied strength zones

Patent metadata

Field	Value
Publication number	US-10399519-B2
Application number	US-201715625475-A
Country	US
Kind code	B2
Filing date	Jun 16, 2017
Priority date	Jun 16, 2017
Publication date	Sep 3, 2019
Grant date	Sep 3, 2019

Abstract

A bumper assembly may include a pair of crush cans and a bumper beam. The pair of crush cans are for securing to a vehicle body. The bumper beam is secured to the crush cans and includes a first end and a second end each extending outboard of one of the crush cans, and a middle portion extending between the first and second ends. The bumper beam is thermally treated to provide the first and second ends with less tensile strength than the middle portion. The middle portion may have a tensile strength between 1000 MPa and 1900 MPa. Each of the first and second ends may have a tensile strength between 600 MPa and 900 MPa.

First claim

What is claimed is:

1. A vehicle bumper assembly comprising:
a pair of crush cans for securing to a vehicle body; and
a bumper beam secured to the crush cans at a first beam surface of a first end and a second beam surface of a second end each end extending inboard and outboard of one of the crush cans, and a middle portion extending between the first and second ends,
wherein the bumper beam is thermally treated to provide the first and second ends with less tensile strength than the middle portion.

2. The assembly of claim 1 , wherein the middle portion has a tensile strength between 1000 MPa and 1900 MPa.

3. The assembly of claim 1 , wherein each of the first and second ends has a tensile strength between 600 MPa and 900 MPa.

4. The assembly of claim 1 , wherein each of the first end and the second end is of a tensile strength to provide deformation substantially equal to a width of the bumper beam when subjected to an impact force between 5,000 and 15000 pounds.

5. The assembly of claim 1 further comprising a pair of bumper supports each disposed between one of the pair of crush cans and the bumper beam.

6. The assembly of claim 1 , wherein the first end and the second end are formed to define a strength zone in which the tensile strength of each of the ends provides for an amount of deformation to absorb energy greater than an amount of deformation to absorb energy of the middle portion when subjected to an impact.

7. The assembly of claim 1 , wherein each of the first end and the second end extend inboard relative to an adjacent crush can up to one inch.

8. The assembly of claim 1 , wherein each of the crush cans has a length substantially equal to approximately seven inches.

9. A bumper assembly comprising:
a first crush can for securing to a portion of a vehicle body;
a first bumper support mounted to the first crush can;
a second crush can spaced from the first crush can for securing to another portion of the vehicle body;
a second bumper support mounted to the second crush can; and
a bumper beam mounted to the first bumper support at a first beam surface and including:
a thermally treated first strength zone extending along the bumper beam inboard and outboard of the first beam surface;
a thermally treated second strength zone extending inboard and outboard of the second crush can; and
a thermally treated third strength zone extending between the first strength zone and the second strength zone, wherein the third strength zone is of a tensile strength greater than the first strength zone and a tensile strength of the second strength zone.

10. The assembly of claim 9 , wherein the first strength zone is further defined as a zone in which a microstructure includes portions of one of more of ferrite, pearlite, martensite, and bainite, and wherein the third strength zone is further defined as a zone including a fully martensitic structure.

11. The assembly of claim 9 , and wherein the third strength zone is heated during thermal treatment to have a tensile strength between 1000 MPa and 1900 MPa.

12. The assembly of claim 9 , wherein the first strength zone is of a tensile strength to provide bumper beam deformation substantially equal to a width of the bumper beam when subjected to an impact force between 5,000 and 15,000pounds.

13. The assembly of claim 9 , wherein the first crush can has a length of approximately seven inches.

14. The assembly of claim 9 , wherein the first strength zone extends inboard relative to an adjacent crush can up to one inch.

15. A method to create a vehicle bumper beam comprising:
heating a portion of a blank to a first temperature to define a first strength zone;
heating a second portion of the blank to a second temperature to define a second strength zone; and
transferring the blank after heating to a die to form a vehicle bumper beam,
wherein the second strength zone spans inboard and outboard on either side of a vehicle crush can supporting the bumper beam and includes a microstructure having one or more of ferrite, pearlite, martensite, and bainite.

16. The method of claim 15 , wherein the first temperature is above an upper critical temperature of the blank.

17. The method of claim 15 , wherein the second temperature is between a lower critical temperature and an upper critical temperature of the blank.

Assignees

• Ford Global Tech Llc

Inventors

• Sohmshetty Raj
• Telukunta Rohit
• Nusier Saied
• Baccouche Mohamed Ridha

Classifications

• B60R2019/1826

  of high-tension steel · CPC title

• B60R19/18

  {characterised by the cross-section;} Means within the bumper to absorb impact · CPC title

• C21D8/0294

  involving a localised treatment · CPC title

• C21D1/673

  for die quenching · CPC title

• B21D22/022

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