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Hole-widening machining method, molding tool, molding and machining method

一种孔加工方法、用具的技术，应用在运输和包装、车辆部件等方向，能够解决花费成本及工时、生产性问题等问题，达到抑制延展凸缘破裂、提高分型性、抑制破裂及回弹的效果

Active Publication Date: 2018-04-17
NIPPON STEEL CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, these methods require cost and man-hours, and have problems in productivity.

Method used

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  • Hole-widening machining method, molding tool, molding and machining method
  • Hole-widening machining method, molding tool, molding and machining method
  • Hole-widening machining method, molding tool, molding and machining method

Examples

Experimental program
Comparison scheme
Effect test

Embodiment A

[0173] Experiments were conducted to confirm the effect of preventing cracking of the expanded flange and the effect of reducing springback during the reaming process of the present invention. As the steel sheet S (workpiece), a high-strength hot-rolled steel sheet of 780 MPa class with a thickness of 2.4 mm was prepared.

[0174] For the steel plate S, bottom holes of various sizes and shapes are provided by punching in advance. The hole expanding process was performed by pushing various forming tools into the bottom hole at a speed of 10 mm / sec.

[0175] Regarding the evaluation of the expansion flange fracture during the reaming process, for the inventive example with linear protrusions and the comparative example without linear protrusions, the size of the bottom hole was reduced by 1 mm, depending on whether the bottom hole was reduced to which It is evaluated to the extent that no extended flange fracture occurs.

[0176] Regarding springback, it is unfair if the size of the ...

Embodiment B

[0198] Experiments were conducted to confirm the influence of the number and pitch of the linear protrusions of the molding tool on the effect of preventing cracking of the extended flange and the effect of reducing springback during the reaming process.

[0199] To Figure 4A~Figure 4C Based on the molding tool of the illustrated example of the present invention, the helix angle was fixed at 45 degrees, the number of linear protrusions was changed, and the hole was expanded.

[0200] Here, the numerical index δ for appropriately performing sequential molding of linear protrusions is defined as follows. If it is assumed that the distribution of the index σn is observed at a certain time, the maximum value of the index σn is σmax and the minimum value is σmin, then it is defined as

[0201] δ=|σmax-σmin| / σmax.

[0202] The above δ can be 0.0 <δ Values ​​in the range of <1.0. When δ=0.0, since σmax=σmin, the difference between the mountains and valleys of the index σn does not occur, s...

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Abstract

This hole-widening machining method has a preparation step for preparing a workpiece formed with a pilot hole and a molding tool having a widening diameter part having a wider diameter from a tip endside toward a rear end side and a linear protrusion formed to protrude from the surface of the widening diameter part to the outside, and a hole widening step for gradually widening the pilot hole inthe workpiece by pressing the molding tool into the pilot hole so that the linear protrusion of the molding tool touches a portion of the circumferential edge of the pilot hole at least twice to forma stretch flange.

Description

[0001] This application claims priority based on Japanese Patent Application No. 2015-173669 filed on September 3, 2015 and Japanese Patent Application No. 2016-012360 filed on January 26, 2016, and the entire contents are quoted here. Technical field [0002] In particular, the present invention relates to a method for enlarging a hole by press forming, a forming tool, and a formed product, which are implemented on automotive parts and the like. Background technique [0003] In recent years, the use of high-strength steel sheets has increased for the purpose of improving the fuel efficiency and crash safety of automobiles. There are also cases where complex shapes are required for automotive parts, and good processability, that is, ductility and hole expandability become important. [0004] In the reaming process, for the bottom hole of the workpiece which is pre-set with a bottom hole by punching or cutting, a forming tool is pushed into the forming tool, the diameter of which is ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B21D19/08
CPCB21D19/08B21D19/088B21D53/88B21D19/10B21D28/28
Inventor 新田淳米村繁白神聪安富隆
Owner NIPPON STEEL CORP
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