Defect detection device and production system

Patent metadata

Field	Value
Publication number	US-10339645-B2
Application number	US-201715720077-A
Country	US
Kind code	B2
Filing date	Sep 29, 2017
Priority date	Jul 8, 2014
Publication date	Jul 2, 2019
Grant date	Jul 2, 2019

Abstract

Provided is a defect detection device capable of measuring the volume of surface defects. The defect detection device includes: an imaging device configured to image an image of an inspection object; a binarization processing unit configured to subject the image to first and second binarization processing by use of different first and second binarization thresholds, so as to calculate first and second sizes for an identical defect in the image; a ratio calculation unit configured to calculate a first ratio of the second size to the first size; and a depth determination unit configured to determine a depth of the defect depending on the first ratio.

First claim

What is claimed is:

1. A defect detection device comprising:
a camera configured to image an image of an inspection object;
a binarization processor configured to subject the image to first and second binarization processing by use of a first binarization threshold and a second binarization threshold different from the first binarization threshold, so as to calculate first and second sizes for an identical defect in the image;
a ratio calculation processor configured to calculate a first ratio of the second size to the first size; and
a depth determination processor configured to determine a depth of the defect depending on the first ratio,
wherein the first binarization threshold is larger than the second binarization threshold, and
a size of the identical defect includes at least one of a defect area and a defect length.

2. The defect detection device according to claim 1 , further comprising:
a volume calculation processor configured to calculate a volume of the defect depending on the depth of the defect determined, and calculate a sum of volumes of all defects in the image; and
a quality determination processor configured to determine whether the inspection object is fine or inferior according to the sum of the volumes of the all defects.

3. The defect detection device according to claim 1 , wherein:
the binarization processing processor subjects the image to third binarization processing by use of a third binarization threshold different from the first binarization threshold and the second binarization threshold, so as to calculate a third size for the identical defect in the image;
the ratio calculation processor calculates a second ratio of the third size to the first size; and
the depth determination processor determines a depth of the defect depending on the first and second ratios.

4. The defect detection device according to claim 1 , wherein the depth determination processor compares the first ratio with each of a plurality of thresholds different from each other to determine depths of the defect several times, so as to comprehensively evaluate the depth of the defect according to the depths determined several times.

5. The defect detection device according to claim 1 , wherein:
the inspection object is a cylinder block of an engine; and
the defect includes at least a pit and a blowhole.

6. A production system comprising:
a defect detection device comprising:
a camera configured to image an image of an inspection object;
a binarization processor configured to subject the image to first and second binarization processing by use of a first binarization threshold and a second binarization threshold different from the first binarization threshold, so as to calculate first and second sizes for an identical defect in the image;
a ratio calculation processor configured to calculate a first ratio of the second size to the first size;
a depth determination processor configured to determine a depth of the defect depending on the first ratio; and
a volume calculation processor configured to calculate a volume of the defect depending on the depth of the defect determined, and calculate a sum of volumes of all defects in the image, and
a gun body and a spray gun attached to the gun body configured to arrange a processing condition for the inspection object according to the sum of the volumes of the all defects,

wherein the first binarization threshold is larger than the second binarization threshold, and
a size of the identical defect includes at least one of a defect area and a defect length.

Assignees

• Nissan Motor

Inventors

• Shibayama Hirohisa
• Shiotani Eiji
• Sakurai Satoru
• Sugiyama Kiyokazu
• Shimizu Akira
• Terada Daisuke
• Noshi Yoshitsugu
• Utsumi Yoshito

Classifications

• G01N2201/10

  Scanning · CPC title

• G01N21/88

  Investigating the presence of flaws or contamination · CPC title

• G06T7/507

  from shading (G06T7/586 takes precedence) · CPC title

• G01N2021/9548

  Scanning the interior of a cylinder · CPC title

• G01N21/954

  Inspecting the inner surface of hollow bodies, e.g. bores · CPC title