Screw Thread Measurement by Camera Inspection System

Optical Simulation of Omnidirectional Inspection System for Screw Threads

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.625.706 ◽

2014 ◽

Vol 625 ◽

pp. 706-711

Author(s):

Keun Park ◽

Chang Hun Lee ◽

Seung Woo Ra

Keyword(s):

Surface Defects ◽

Optical Measurement ◽

Optical Simulation ◽

Inspection System ◽

Light Illumination ◽

Screw Thread ◽

Simulation Based ◽

Screw Threads ◽

Optical Paths

Machine vision systems have been used in the automatic inspection of screw threads using backlight illumination for the inspection of the screw thread profiles. In this study, an alternative inspection system based on front light illumination is developed to directly obtain thread images so that surface defects can be measured. To realize such an inspection system, an omnidirectional optical measurement device is proposed to obtain 360oimages of screws for inspection of whole thread regions. Optical simulation based on ray tracing is then performed to analyze optical paths and to optimize the image quality of the designed optical system.

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Study on the Inspection Method of Gas Valve’s External Taper Screw Thread Based on Image Domain

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.189-193.4195 ◽

2011 ◽

Vol 189-193 ◽

pp. 4195-4200

Author(s):

Xue Chang Zhang ◽

Xu Zhang ◽

Junhua Chen

Keyword(s):

High Performance ◽

Ccd Camera ◽

Inspection System ◽

Screw Thread ◽

Inspection Method ◽

Image Domain ◽

Dimension Measurement ◽

Automatic Visual Inspection ◽

Manual Testing ◽

Feature Dimension

The failure of the gas valve’s external screw taper thread is a very serious problem which may result in accidents. Routine inspection on the threads is thus necessary. The efficiency of traditional manual testing methods can not meet the production requirements. An automatic visual inspection system for gas valve’s external screw taper thread is presented in the paper. The system consists of a high-performance 200 mega pixels CCD camera, a LED backlight and a holder of gas valve. Through image acquisition, image processing, edge detection and feature dimension measurement, the system can effectively measure the parameters of taper thread such as half of thread angle, depth of thread, taper angle of thread on image domain. Due to the lead angle and installation error, actual half of thread angle is different from the theoretical values. Three methods are presented in the paper for the half of thread angle. Through analysis, Method 3 and Method 2 can be used to measure half of thread angle. The system can meet the testing requirements of the external screw taper thread and has wide application perspective.

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Microdensitometer—computer correlation analysis of ultrastructural periodicity

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100081024 ◽

1978 ◽

Vol 36 (2) ◽

pp. 32-33

Author(s):

D.R. Ensor ◽

C.G. Jensen ◽

J.A. Fillery ◽

R.J.K. Baker

Keyword(s):

Correlation Analysis ◽

Background Noise ◽

Computer Control ◽

Optical Diffraction ◽

Screw Thread ◽

Straight Line ◽

Computer Storage ◽

Correlation Process ◽

Electron Microscope Image ◽

Fixed Beam

Because periodicity is a major indicator of structural organisation numerous methods have been devised to demonstrate periodicity masked by background “noise” in the electron microscope image (e.g. photographic image reinforcement, Markham et al, 1964; optical diffraction techniques, Horne, 1977; McIntosh,1974). Computer correlation analysis of a densitometer tracing provides another means of minimising "noise". The correlation process uncovers periodic information by cancelling random elements. The technique is easily executed, the results are readily interpreted and the computer removes tedium, lends accuracy and assists in impartiality.A scanning densitometer was adapted to allow computer control of the scan and to give direct computer storage of the data. A photographic transparency of the image to be scanned is mounted on a stage coupled directly to an accurate screw thread driven by a stepping motor. The stage is moved so that the fixed beam of the densitometer (which is directed normal to the transparency) traces a straight line along the structure of interest in the image.

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