Non-contact Multi-feed Detection Device for Sheet-fed Printing Presses
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Solution Overview
Problem
Existing multi-feed detection devices in sheet-fed printing presses experience detection errors due to wear and deformation over long-term use, requiring frequent maintenance and inspection.
Innovation Solution
A multi-feed detection device with a swingable arm member and non-contact measuring means, including a target and a laser-based non-contact sensor, measures the positional relation between the sensor and target, allowing for accurate detection of overlapping sheets without physical contact, and features a turnable support shaft to move the arm between operational and retreat positions, along with biasing and adjusting mechanisms to maintain contact pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If contact-based detection mechanisms (potentiometer working end and striker, or electric contacts) are used to detect multi-feed, then the detection device can reliably detect overlapping sheets, but the components experience wear deformation over long-term use which increases detection errors and requires periodic maintenance
Solution Approach 1:
The patent replaces the mechanical contact-based detection system (potentiometer working end and striker, or electric contacts) with a non-contact optical detection system using a laser beam. The laser beam passes through a sheet stack, and when an additional sheet is fed, it disrupts the beam path, triggering detection. This substitution eliminates mechanical wear and deformation issues while maintaining reliable detection capability.
2Measurement precision
If a gauge plate is inserted between the arm and operating pin to adjust clearance, then the detection device can accurately detect multi-feed conditions, but the gauge plate experiences deformation and dirt attachment over time which increases detection errors and requires maintenance
Solution Approach 1:
The patent eliminates the mechanical gauge plate component by using a non-contact optical detection system. The laser beam provides a stable reference for detection without requiring physical adjustment components that can deform or accumulate dirt. This substitution maintains measurement precision while completely eliminating the maintenance issues associated with gauge plates.
3Reliability
If non-contact measuring means (laser sensor) is used to measure positional relation without contact, then the device achieves accurate detection without wear or deformation, but the device complexity increases due to additional components
Solution Approach 1:
The patent extracts and eliminates the complex mechanical adjustment components (gauge plate, operating pin, contact levers) by using a simplified non-contact optical detection system. The laser sensor directly detects sheet presence without requiring mechanical intermediaries, reducing overall device complexity while improving reliability.
Solution Approach 2:
The patent introduces a laser beam as an intermediary for detection, which serves as a non-contact mediator between the detection system and the sheets. This intermediary enables accurate detection without physical contact, avoiding wear and deformation of mechanical components while maintaining system simplicity.
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 device reduces detection errors and maintenance efforts by enabling accurate non-contact detection of overlapping sheets, minimizing downtime and resource allocation for periodic maintenance.
Implementation Method 1
non-contact measuring means for measuring, in a non-contact manner, a positional relation between the non-contact measuring means and the target
Data Source
AI summary
A multi-feed detection device includes: an arm member (14 to 17) supported swingably and configured to come into contact with a traveling sheet (1); and detecting means (25 to 27) for detecting whether a plurality of the traveling sheets (1) are overlapped and fed, on the basis of swing of the arm member (14 to 17). The detecting means (25 to 27) includes: a detection plate (27) attached to an arm (15); and a non-contact sensor (26) configured to measure, in a non-contact manner, the positional relation between the non-contact sensor (26) and the detection plate (27), the positional relation being changed by swing of the arm (15).