During the extrusion of transparent pipes, the consistency of the outer diameter and wall thickness directly determines the finished product’s assembly and pressure-bearing performance. Manual sampling can only be performed intermittently and cannot capture dimensional fluctuations during the continuous extrusion process; conventional optical inspection is easily affected by refraction through the transparent pipe walls, resulting in measurement errors. The dual-spectral opposed-beam measurement solution utilizes the differing attenuation characteristics of light in different wavelength bands as it passes through the tube wall to eliminate interference from refraction in transparent media, thereby enabling simultaneous online measurement of the tube’s outer diameter and wall thickness.

The extruded transparent tubing is continuously fed forward; a dual-spectral light source emits light from one side through the tubing, while a receiver on the other side simultaneously captures two sets of spectral signals. The algorithm performs a differential calculation on the two sets of spectral data to compensate for the refractive effects of the transparent tube wall, while simultaneously extracting information on the tube’s outer contour and wall thickness to calculate the outer diameter and wall thickness in real time. If the dimensions exceed the preset tolerance range, the system outputs an alarm signal, prompting the production line to adjust the extrusion parameters.

Temperature fluctuations and slight vibrations occur at the pipe production site, and tiny air bubbles may be present inside the pipe walls, which can easily cause fluctuations in single-spectrum measurements. The dual-spectrum fusion algorithm filters out this type of interference noise to maintain measurement stability. The entire solution is non-contact throughout the process, preventing scratches on the outer surface of the pipes. It is suitable for continuous, uninterrupted extrusion production lines, and measurement data is automatically stored for convenient product quality traceability.

This solution can simultaneously monitor multiple dimensional parameters and, compared to single-optical inspection methods, offers greater adaptability to transparent workpieces. Real-time feedback data can assist in closed-loop adjustments of the extrusion equipment, reducing the production of non-conforming products and improving the yield rate of finished goods.

In the transparent pipe extrusion industry, the dual-spectral opposed-beam measurement solution addresses the challenges of optical measurement in transparent media, providing a stable and viable technical approach for full-dimensional online inspection of continuously extruded products.