Converting Machine Calibration for Printed Image Die-Cut Alignment

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Solution Overview

Problem

Converting machines struggle to accurately align pre-printed images on sheets with die-cutting tools due to unknown printed pattern locations, leading to inconsistent image placement on finished boxes.

Innovation Solution

A calibration system with an image sensor, control unit, and memory to detect and correct deviations in the position of pre-printed images, using transfer drives to adjust the sheet's position along the conveyance path, ensuring consistent image placement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a register control system using optical detectors and front leading edge reference is used, then the alignment of sheets is improved, but the position control of printed patterns deteriorates

Engineering Contradiction:
Improvesheet alignmentVSAvoidprinted pattern position
Core Design Contradiction:
Manufacturing precisionVSMeasurement precision

Solution Approach 1:

The patent replaces the mechanical/optical register control system that uses front leading edge reference with an image recognition system using cameras and software to detect printed pattern positions. This substitution enables direct measurement and control of printed pattern locations rather than relying on mechanical sheet alignment references.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces an intermediary image recognition system that detects the actual position of printed patterns and provides feedback to the control system. This intermediary layer bridges the gap between sheet feeding and printed pattern positioning, enabling precise control of pattern locations despite variations in sheet delivery.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Stability of the object's composition

If the position of sheets is controlled rather than the position of printed patterns, then the sheet alignment is improved, but the consistency of image placement deteriorates

Engineering Contradiction:
Improvesheet alignmentVSAvoidimage placement consistency
Core Design Contradiction:
Stability of the object's compositionVSManufacturing precision

Solution Approach 1:

The patent implements a feedback control system where cameras capture images of printed patterns, the control unit determines actual positions, calculates deviations from target positions, and adjusts transfer drive speeds accordingly. This closed-loop feedback enables consistent image placement by continuously correcting position errors.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent makes the transfer drives dynamically adjustable by controlling their speeds individually based on real-time image analysis. This dynamic control allows the system to adapt to variations in sheet delivery and actively maintain consistent printed pattern positioning throughout the converting process.

Inventive Principle:
Principle #15Dynamics

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

Ensures that the printed image is placed at the same position on all boxes by detecting and correcting deviations in real-time, improving the accuracy and consistency of the final product.

Implementation Method 1

an image sensor configured to capture an actual image of an indicia on a sheet passing through the converting machine

Methodology Applied
Scientific EffectLight reflection: Reflection

Data Source

PatentEP4225541B1Calibration system and calibration method for a converting machine
Publication Date: 2026.03.25 BOBST LYON
  • EP4225541B1 patent drawingFigure 1a~1d
  • EP4225541B1 patent drawingFigure 2
  • EP4225541B1 patent drawingFigure 3

AI summary

The present invention relates to a calibration system (30) and a calibration method for a converting machine (20) provided with a die-cutting tool (18') and at least one transfer unit (25) for transporting a sheet (1) along a travel path in a direction of conveyance (D) through the converting machine. The calibration system comprising a first image sensor (33), a memory (36) and a control unit (34). The calibration system is configured to detect an actual position of an indicia (42) on the sheet (1) and compare with a reference position of the indicia (42) stored in the memory (36). A correction program stored in the memory is executed when at least one of the longitudinal displacement (Δxi) and the lateral displacement (Δyi) of the indicia exceeds a predetermined tolerance threshold (Txi, Tyi).