Method for identifying variation factor portion of springback amount

Patent metadata

Field	Value
Publication number	US-11911816-B2
Application number	US-201917422276-A
Country	US
Kind code	B2
Filing date	Oct 17, 2019
Priority date	Feb 1, 2019
Publication date	Feb 27, 2024
Grant date	Feb 27, 2024

Abstract

A method for identifying a variation factor portion of a springback amount, including: performing press forming analysis under first press forming conditions, and calculating a residual stress distribution in a press formed part; performing springback analysis on the press formed part, and calculating a first springback amount; performing press forming analysis under second press forming conditions, and calculating a residual stress distribution in the press formed part; replacing a value of residual stress in a partial area of the residual stress distribution; performing springback analysis on the press formed part for which the value of the residual stress has been replaced, and calculating a second springback amount; obtaining a difference between the second springback amount and the first springback amount; and identifying a portion in the press formed part that is a factor for variation in springback amount of the press formed part based on the obtained difference.

First claim

The invention claimed is:

1. A method for identifying a variation factor portion of a springback amount, the method identifying a portion in a press formed part that is a factor for variation in a springback amount when variation occurs in the springback amount in the press formed part due to scattering in press forming conditions, and comprising:
performing press forming analysis under first press forming conditions set in advance, and calculating a residual stress distribution in a press formed part at a press forming bottom dead center;
performing springback analysis on the press formed part for which the calculated residual stress distribution has been set, and calculating a first springback amount to be caused in the press formed part;
performing press forming analysis under second press forming conditions set differently from the first press forming conditions within a range of the scattering in press forming conditions, and calculating a residual stress distribution in the press formed part at the press forming bottom dead center;
replacing a value of residual stress in a partial area of the residual stress distribution in the press formed part calculated under the first press forming conditions with a value of residual stress in an area corresponding to the partial area of the residual stress distribution in the press formed part calculated under the first press forming conditions;
performing springback analysis on the press formed part for which the value of the residual stress has been replaced, and calculating a second springback amount;
obtaining a difference between the second springback amount and the first springback amount; and
identifying a portion in the press formed part that is a factor for variation in springback amount of the press formed part based on the obtained difference.

2. The method for identifying the variation factor portion of the springback amount according to claim 1 , wherein the press forming conditions include mechanical properties of a blank material, a thickness and a shape of the blank material, temperature of the blank material, sliding characteristics between the blank material and a tool of press forming, a relative position of the blank material with respect to the tool of press forming, a position and a shape of a positioning device for the blank material, mechanical properties of a material of the tool of press forming, a shape of a surface of the tool of press forming, an internal structure of the tool of press forming, blank holder force, a blank holder position, a position and a shape of a device for applying blank holder force to component parts of the tool of press forming, an initial relative position of the component parts of the tool of press forming, relative speed of movement of the tool of press forming, vibration of the tool of press forming, temperature of the tool of press forming, atmospheric temperature, atmospheric components, a pressurizing device, and electromagnetic environments.

3. A method for identifying a variation factor portion of a springback amount, the method identifying a portion in a press formed part that is a factor for variation in a springback amount when variation occurs in the springback amount in the press formed part due to scattering in press forming conditions, and comprising:
press forming a first press formed part under first press forming conditions in advance;
creating a first press formed part model from three-dimensional shape measurement data obtained by measuring a surface shape of the first press formed part after die release;
performing mechanical analysis in a state in which the first press formed part model is sandwiched by a tool-of-press-forming model until reaching a press forming bottom dead center;
acquiring residual stress distribution in the first press formed part at the press forming bottom dead center under the first press forming conditions;
press forming a second press formed part under second press forming conditions different from the first press forming conditions within a range of the scattering in press forming conditions in advance;
creating a second press formed part model from three-dimensional shape measurement data obtained by measuring a surface shape of the second press formed part after die release;
performing mechanical analysis in a state in which the second press formed part model is sandwiched by the tool-of-press-forming model until reaching the press forming bottom dead center,
acquiring residual stress distribution in the second press formed part at the press forming bottom dead center under the second press forming conditions;
performing springback analysis on the first press formed part for which the acquired residual stress distribution in the first press formed part has been set, and calculating a first springback amount;
replacing a value of residual stress in a partial area of the acquired residual stress distribution in the first press formed part with a value of residual stress in an area corresponding to the partial area of the acquired residual stress distribution in the second press formed part;
performing springback analysis on the first press formed part for which the value of the residual stress has been replaced, and calculating a second springback amount;
obtaining a difference between the second springback amount and the first springback amount; and
identifying a portion in the first press formed part that is a factor for variation in springback amount of the first press formed part based on the obtained difference.

4. The method for identifying the variation factor portion of the springback amount according to claim 3 , wherein the press forming conditions include mechanical properties of a blank material, a thickness and a shape of the blank material, temperature of the blank material, sliding characteristics between the blank material and a tool of press forming, a relative position of the blank material with respect to the tool of press forming, a position and a shape of a positioning device for the blank material, mechanical properties of a material of the tool of press forming, a shape of a surface of the tool of press forming, an internal structure of the tool of press forming, blank holder force, a blank holder position, a position and a shape of a device for applying blank holder force to component parts of the tool of press forming, an initial relative position of the component parts of the tool of press forming, relative speed of movement of the tool of press forming, vibration of the tool of press forming, temperature of the tool of press forming, atmospheric temperature, atmospheric components, a pressurizing device, and electromagnetic environments.

Assignees

• Jfe Steel Corp

Inventors

• Urabe Masaki

Classifications

• B21D22/02 Primary

  Stamping using rigid devices or tools · CPC title

• B21D22/20

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

• G06F30/10

  Geometric CAD · CPC title

• G06F30/23 Primary

  using finite element methods [FEM] or finite difference methods [FDM] · CPC title

• B21D22/24 Primary

  involving two drawing operations having effects in opposite directions with respect to the blank · CPC title