Optical Preform Defect Detection on Thermal Conveyor
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing systems for manufacturing containers from preforms struggle to reliably detect defects in the shape or positioning of preforms during conveyor transport, particularly when preforms are not centered or have form defects.
Innovation Solution
A detection device is implemented that uses a laser beam and optical block positioned on an adjustable support, with a target equipped with a photosensitive sensor or reflector, to detect defects in the shape or positioning of preforms as they travel along the conveyor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mechanical detection device is used to detect preform positioning, then it can detect intermediate positions of the mandrel, but it cannot detect preforms that are correctly positioned at the upstream wheel but become incorrectly positioned during turning due to centrifugal force, nor can it detect shape defects
Solution Approach 1:
The patent replaces the mechanical detection device with an optical detection system. The optical unit emits a beam that traverses the path of the hollow bodies, and when a defective preform (either mispositioned or deformed) intersects this beam, it is detected. This optical system can detect both positioning defects that occur during turning and shape defects, providing comprehensive detection coverage that the mechanical device could not achieve.
Solution Approach 2:
The patent introduces an optical beam as an intermediary detection medium. The beam acts as a virtual barrier across the conveyor path, and any preform that deviates from its correct position or has shape defects will intersect this beam, triggering detection. This intermediary approach allows detection of defects without physical contact, enabling detection of both positioning and shape anomalies.
2Productivity
If the preform speed is increased to 1 m/s to achieve high production rate of 50,000 containers per hour, then productivity is improved, but positioning problems occur where preforms are not correctly centered in relation to the mandrel
Solution Approach 1:
The optical detection system is positioned to detect preform defects before the preforms reach the mandrel fitting point. By detecting positioning and shape defects in advance, the system allows for preliminary action (ejection or correction) before the high-speed conveyor causes misalignment issues, thus maintaining both high productivity and positioning precision.
3Adaptability or versatility
If an optical detection system with laser beam is implemented to detect all types of defects, then detection versatility is improved, but device complexity increases
Solution Approach 1:
While the optical system does increase complexity compared to mechanical devices, it replaces a complex mechanical detection mechanism with a simpler optical setup. The optical unit with laser beam and detector provides comprehensive defect detection capability without the mechanical complexity of sensors, actuators, and moving parts required for mechanical detection.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The detection device significantly enhances the reliability of defect detection, allowing for the identification of both positioning and form defects in preforms, even when they are not centered or have suffered deformation, thereby enabling their ejection from the conveyor.
Implementation Method 1
an optical unit incorporating an emitter producing an optical beam
Implementation Method 2
a target positioned at a distance from the optical unit, the target being provided with a photosensitive sensor or a reflector intercepting said optical path
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Disclosed is a device (23) for detecting, on a straight path (TR) defined by a conveyor (1) conveying hollow bodies (2), each having a main axis (X), a shape or positioning defect of a hollow body (2), this device (23) comprising: - an optical unit (24) incorporating an emitter producing an optical beam (25) along an optical pathway of which at least one segment is oriented parallel to the path (TR) and offset laterally, relative to a median plane (M) along which the main axes (X) of the hollow bodies (2) travel, by a distance (D) greater than a half-width (R) of the hollow bodies (2) and by a distance (D) less than twice the width (R) of the hollow bodies (2); - a target (26) positioned at a distance from the optical unit (24) and provided with a photosensor or a reflector (27) intercepting the optical pathway of the beam (25) and capable, respectively, of detecting it or of reflecting it towards an optical receiver incorporated into the optical unit (24).