Apparatus and method for detecting defect of press panel

Patent metadata

Field	Value
Publication number	US-9846144-B2
Application number	US-201514873728-A
Country	US
Kind code	B2
Filing date	Oct 2, 2015
Priority date	Oct 2, 2014
Publication date	Dec 19, 2017
Grant date	Dec 19, 2017

Abstract

An apparatus for detecting a defect of a press panel includes: an acoustic emission sensor unit configured to detect at least one elastic wave signal emitted from the press panel as a detection target during press work, a period measurer configured to measure a period as a section in which there are consecutive signals with a greater voltage than a threshold voltage among the at least one detected signals, and a defect existence determination unit configured to determine that a defect is generated in the press panel when the measured period is greater than a first reference value, and to determine that the press panel is in a normal state when the measured period is smaller than a second reference value which is smaller than the first reference value.

First claim

What is claimed is:

1. An apparatus for detecting a defect of a press panel, the apparatus comprising:
an acoustic emission sensor unit configured to detect at least one elastic wave signal emitted from the press panel as a detection target during press work;
a period measurer configured to measure a period as a section in which there are consecutive signals with a greater voltage than a threshold voltage among the at least one detected signals; and
a defect existence determination unit configured to determine that a defect is generated in the press panel when the measured period is greater than a first reference value and to determine that the press panel is in a normal state when the measured period is smaller than a second reference value which is smaller than the first reference value.

2. The apparatus of claim 1 , wherein:
the first reference value and the second reference value are determined using a period value pre-measured from a plurality of press panels as a comparison target, and
the first reference value and the second reference value refer to a value of a boundary line on distribution of a period of a press panel in which a defect is generated from the comparison target and a period of a press panel in a normal state from the comparison target.

3. The apparatus of claim 1 , further comprising:
an extractor configured to extract from the at least one detected signals: i) at least one parameter among the number of pulses with a greater output voltage than the threshold voltage, ii) energy as the sum of areas of pulses with a greater output voltage than a threshold voltage, and iii) an average frequency generated during the period.

4. The apparatus of claim 3 , wherein:
the defect existence determination unit is further configured to determine whether the press panel is defective using the at least one extracted parameter when the measured period has a value between the first reference value and the second reference value.

5. The apparatus of claim 4 , wherein:
the defect existence determination unit is further configured to:
determine that a defect is generated in a corresponding press panel when the number of pulses and the energy are higher than a reference number among the extracted parameter, and
determine that a defect is generated in the corresponding press panel when the average frequency generated during the period is lower than a reference number.

6. A method for detecting a defect using a press panel defect detection apparatus, the method comprising:
detecting at least one elastic wave signal emitted from the press panel as a detection target during press work;
measuring a period as a section in which there are consecutive signals with a greater voltage than a threshold voltage among the at least one detected signals;
determining that a defect is generated in the press panel when the measured period is greater than a first reference value; and
determining that the press panel is in a normal state when the measured period is smaller than a second reference value which is smaller than the first reference value.

7. The method of claim 6 , wherein:
the first reference value and the second reference value are determined using a period value pre-measured from a plurality of press panels as a comparison target, and
the first reference value and the second reference value refer to a value of a boundary line on distribution of a period of a press panel in which a defect is generated from the comparison target and a period of a press panel in a normal state from the comparison target.

8. The method of claim 6 , further comprising:
extracting from the at least one detected signal: i) at least one parameter among the number of pulses with a greater output voltage than the threshold voltage, ii) energy as the sum of areas of pulses with a greater output voltage than a threshold voltage, and iii) an average frequency generated during the period.

9. The method of claim 8 , wherein the determining that the defect is generated comprises:
determining whether the press panel is defective using the at least one extracted parameter when the measured period has a value between the first reference value and the second reference value.

10. The method of claim 9 , wherein the determining that the defect is generated further comprises:
determining that a defect is generated in a corresponding press panel when the number of pulses and the energy are higher than a reference number among the extracted parameter; and
determining that a defect is generated in the corresponding press panel when the average frequency generated during the period is lower than a reference number.

11. A non-transitory computer readable medium containing program instructions for detecting a defect of a press panel, the computer readable medium comprising:
program instructions that measure a period as a section in which there are consecutive signals with a greater voltage than a threshold voltage among at least one elastic wave signal emitted from the press panel detected as a detection target during press work;
program instructions that determine that a defect is generated in the press panel when the measured period is greater than a first reference value; and
program instructions that determine that the press panel is in a normal state when the measured period is smaller than a second reference value which is smaller than the first reference value.

Assignees

• Hyundai Motor Co Ltd
• Kia Motors Corp
• Unist Academy-Industry Res Corporation

Inventors

• Hwang Jae Ryeon
• Kim Byunghun
• Bien Franklin
• Yoo Hyon Gi
• Jeong Chan Woo
• Quang Nguyen Ngoc
• Zhenyi Liu
• Kim Seul Ki Rom

Classifications

• G01N29/14 Primary

  using acoustic emission techniques {(echo of particles G01N29/046; measuring mechanical vibrations or acoustic waves in solids in general G01H1/00)} · CPC title

• G01N29/4427

  with stored values, e.g. threshold values · CPC title

• G01N2291/0234

  Metals, e.g. steel · CPC title

• G01N2291/0289

  Internal structure, e.g. defects, grain size, texture · CPC title

• G01N29/4436

  with a reference signal (amplitude comparison G01N29/48) · CPC title