Abstract
With the development of manufacturing industry, the high precision size measurement for the holes on the surface of mechanical parts is required. A method for measuring size of the hole based on double projection is proposed in this paper. The CCD camera separately collects grating images which projected onto the part surface in two directions. The phase-shift method is used to calculate the phase of grating images in two directions, and the reconstructed three-dimensional shapes in the two directions are merged to measure the hole dimension. Experiment results show that the measurement accuracy of the thickness is 0.04mm, and the hole size can reach to 0.1 mm.
Highlights
The structure of mounting hole is necessary in all kinds of mechanical parts
Grating projection is one of the methods to realize the inspection of the holes and obtain the thickness of steel plate or part without contact
When the method is used for the measurement of deep holes, the shadow area is formed due to the occlusion of the edge of the holes, which leads to the interruption of the grating, and the shadow area cannot be reconstructed accurately
Summary
The structure of mounting hole is necessary in all kinds of mechanical parts. The accurate measurement of hole size plays an important role in machining and assembly. Neither the noise is effectively suppressed nor the local phase information be accurately obtained by the wavelet transform method, so that the size of reconstruction accuracy for the hole is lower. Li et al [12] extracted the phase information of the wheel by the phase shift method to achieve wheel contour reconstruction and wheel tread wear and surface defects were accurately detected. Y. Jin et al.: Measurement Method for the Size of the Hole on the Part Surface Based on Grating Image Processing full-cycle method [13], N-frame average algorithm [14], N + 1 step phase shift algorithm [15], and arbitrary equal step phase shift algorithm [16]. The phase-shift method is used to solve the phase of the two directions, and the reconstructed three-dimensional morphology is fused to realize the accurate measurement of part thickness and holes
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