With the rapid development of automatic production line, product quality inspection has become one of the most important projects. After all, the qualified rate of products is the ultimate production goal. Compared with the bugs of traditional optical detection, automatic visual detection technology adopts more appropriate detection technology to better solve these problems.
The traditional visual inspection adopts high-resolution CCD industrial camera and ordinary industrial lens. Because the ordinary industrial lens has the characteristics of near large far small and edge distortion, the imaging proportion of the object will change in varying degrees in the actual imaging process, the edge is not fixed, and the measurement results will change in the measurement process after calibration, As a result, the accuracy of measuring angles and dimensions is not high.
By placing an aperture in the middle of the lens, the double telecentric lens makes the light in and out of the lens parallel, and filters out the other diffuse light sources. In this way, no matter how the object distance changes, the magnification will not change. This characteristic can solve more than the stability of the edge of the measured object, At the same time, it can solve the influence of uncontrollable jitter of the production line on the system accuracy, and can be used for many high-precision on-line detection requirements.
In image processing, the presence or absence of the edge is judged by the change of gray value. Due to the particularity of the structure of the spring itself, no matter whether the falling light source or backlight is used, the image with the same gray value of the measured object can not be obtained. Especially at the corner reflection, the gray value opposite to other areas is often obtained, resulting in the final measurement result showing that the corner is broken, This result will lead to the direct failure of the detection work.
After shooting with dual telecentric lens and parallel light source, the image continuity is very good, the gray value comparison is very obvious, both the detection size and defects are clear at a glance, the effect meets the needs of high-precision detection, the processing is very simple, and there is almost no detection error.
The depth of field of ordinary industrial lens is relatively small, and the spring itself has a certain height. It often occurs that the depth of field of the lens can not be fully covered and can not be clearly imaged at the same time. In this case, measurement and detection cannot be carried out, which is a problem that optical detection has no way to solve in this field. When we use double telecentric lens, due to its parallel light characteristics, the depth of field can be several times or even dozens of times compared with ordinary lens, which can completely solve this problem.
After long-term testing, improvement and improvement, the technical team of Shandong Hongbao Automation Co., Ltd. continues to repeat the disk. The visual inspection technology has reliable product quality and high stability, which can fully meet the inspection requirements of the required industry.