Vision-Based Sheet Alignment in Multi-Punch Presses
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Solution Overview
Problem
Existing multi-punch presses face challenges in achieving high precision and production efficiency for cutting and separating metal sheet discs with printed patterns, particularly when the printing pattern is not aligned correctly with the punch dies, leading to potential defects and increased production costs due to the need for additional notches and complex inspection methods.
Innovation Solution
A multi-punch press with an integrated image acquisition and processing system that frames and analyzes the metal sheet's printing pattern in real-time, calculating shifts and tilts to adjust the sheet's position accurately before cutting, eliminating the need for additional notches and complex retracting devices, and ensuring each printed portion is aligned correctly with the punch dies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the printing pattern is not aligned correctly with the punch dies, then the production efficiency decreases and defects increase, but adding complex inspection methods and additional notches increases device complexity
Solution Approach 1:
The patent replaces complex mechanical inspection systems with a vision-based detection system using cameras and image processing algorithms. The system captures images of the printing pattern, processes them computationally to detect alignment deviations, and provides feedback for correction, substituting mechanical measurement devices with optical and computational components.
Solution Approach 2:
The patent creates a digital copy (image) of the printing pattern on the metal sheet using a camera system. This optical copy is then processed through image algorithms to detect alignment deviations without physically touching or marking the sheet, avoiding the need for additional notches or mechanical test features.
2Productivity
If manual adjustment of abutting means is used to align the sheet, then flexibility is maintained, but production efficiency decreases due to manual intervention
Solution Approach 1:
The patent implements a closed-loop feedback system where the vision detection system continuously monitors the alignment between the printing pattern and punch dies, calculates deviation values, and feeds this information back to the control system. The control system automatically adjusts the abutting means based on this feedback, eliminating manual intervention while maintaining alignment precision.
Solution Approach 2:
The system performs self-alignment by automatically detecting printing pattern deviations and adjusting the sheet position without operator intervention. The abutting means are equipped with actuators that respond to control signals generated by the image processing system, enabling the equipment to self-correct alignment issues during production.
3Measurement precision
If additional notches are added to the sheet for inspection purposes, then measurement precision improves, but the manufacturing process becomes more complex and time-consuming
Solution Approach 1:
The patent replaces mechanical or physical marking methods (such as punching notches or applying reference marks) with a non-contact optical imaging system. The camera captures the existing printing pattern and uses image processing to extract alignment information, eliminating the need to modify the sheet with additional notches or features.
Solution Approach 2:
The vision system serves multiple functions: it detects alignment deviations, measures printing pattern positions, monitors sheet quality, and provides data for process optimization. This multi-functional system replaces what would otherwise require multiple specialized inspection devices or physical measurement features.
Data Source
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AI summary
An inspection method (2) is provided for inspecting a sheet in a press (1), wherein the press (1) comprises a punching unit (4) which is suitable for receiving a sheet (2) provided with a plurality of printed portions (3) arranged in a regular manner according to a printing pattern and for cutting the sheet in dwell steps thereof, separating into several steps a plurality of printed discs. The method comprises: - providing abutting means (22, 23, 24) arranged upstream of the punching unit (4) to receive the sheet (2) to be cut and adjust the position of the sheet (2), - advancing in a first direction (Dl) the thus adjusted sheet (2) to the punching unit (4) to obtain the plurality of printed discs; - processing at least one acquired image of the sheet (2) to detect an arrangement of the printing pattern in the sheet (2); - comparing the detected arrangement of the printing pattern with a nominal arrangement of the printing pattern to obtain a shift of the printing pattern in the sheet (2) with respect to said nominal arrangement; - acquiring at least one image of the sheet (2) upstream of the abutting means (22, 23, 24) during advancement of the sheet (2) in a second direction (D2). To detect said arrangement of the printing pattern the method further comprises: - identifying a top edge (2a), a bottom edge (2b) and a side working edge (2c) of the sheet (2) and further identifying a top graphic mark (20), which is arranged in a top corner (18) defined between the top edge (2a) and the side working edge (2c), and a bottom graphic mark (21) which is arranged in a bottom corner (19) between the side working edge (2c) and the bottom edge (2b); - calculating a longitudinal shift and a top side shift of the top graphic mark (20) and a bottom side shift of the bottom graphic mark (21); and wherein said adjusting the position of the sheet (2) in said abutting means (22, 23, 24) comprises translating and/or rotating said sheet (2) as a function of said longitudinal shift, and/or said top side shift and/or said bottom side shift to position said printing pattern in said nominal position so as to obtain in said punching unit (4) printed discs in which each printed portion (3) is arranged in a desired position.