Pivoting Measuring Block for Fibre Web Tension Stability
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Solution Overview
Problem
Existing measuring blocks for fibre web machines are prone to wobble and have complex structures due to separate travel stops for overloading protection, leading to increased manufacturing and operating costs, and reliability issues due to single or dual sensor setups with geometry differences impairing failure detection accuracy.
Innovation Solution
A measuring block with a pivoting joint and a second support point, featuring smaller sensor devices supported by a bogie structure that provides stability, reduces wobble and allows for duplexed measurements, enabling free placement without compromising accuracy or overloading protection, using a deflecting axle for internal overloading protection and symmetrical sensor placement for reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate travel stops are used for overloading protection, then overloading protection is provided, but the structure becomes complex and costs increase
Solution Approach 1:
The patent merges the overloading protection function directly into the pivot joint structure itself. The pivot joint is designed to absorb overloads through controlled deformation or yield mechanisms, eliminating the need for separate travel stops. This integration maintains reliability while significantly simplifying the overall structure and reducing component count.
Solution Approach 2:
The pivot joint structure is designed to automatically protect against overloads through its inherent mechanical properties. The joint itself provides the protection mechanism through controlled yielding or deformation under excessive load, without requiring external protection devices. This self-service approach reduces complexity while maintaining safety.
2Device complexity
If a single sensor is used, then the structure is simple, but sensor failure cannot be detected
Solution Approach 1:
The patent implements duplexed sensors at different local positions within the measuring block. Each sensor is strategically placed to measure tension from different orientations or locations, providing redundant measurement capabilities. This local distribution of sensors enables failure detection while maintaining reasonable structural complexity.
Solution Approach 2:
The system performs preliminary comparison of sensor readings to detect failures before they affect measurement accuracy. By continuously monitoring both sensors and comparing their outputs against expected relationships, the system can identify sensor failures in advance and alert operators, preventing erroneous measurements.
3Reliability
If two sensors are placed in separate measuring positions, then redundancy is provided, but geometry differences impair failure detection accuracy
Solution Approach 1:
The patent carefully designs the asymmetric placement of two sensors at specific geometric positions where their measurement relationships are well-defined and predictable. The asymmetric configuration allows for mathematical modeling of the expected relationship between sensor readings, enabling accurate failure detection despite the asymmetric geometry. The key is that the asymmetry is controlled and calculable.
4Measurement precision
If larger sensor devices are used, then measurement capability is improved, but the measuring block size increases and wobble increases
Solution Approach 1:
The patent segments the sensing function into multiple smaller sensor units rather than using one large sensor. These smaller sensors are distributed at different positions within the compact measuring block structure. The segmented approach maintains adequate measurement precision through redundancy and geometric distribution while minimizing the size and wobble of individual sensor components.
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 solution results in a simpler, more reliable tension measurement system with reduced wobble and lower costs, enabling accurate tension control and immediate fault detection, while allowing for flexible placement and easy maintenance.
Implementation Method 1
a support piece (16) and a fastening piece (17), which have been fastened to each other in a pivoting manner by means of a joint (18)
Implementation Method 2
sensor devices (19), which have been adapted between the support piece (16) and the fastening piece (17) on the measuring block (15) in order to determine the tension of a fabric
Implementation Method 3
the sensor devices have been supported in a novel and surprising way... the measuring block becomes stable, which reduces wobble in the control of the tension of the fabric
Implementation Method 4
using a deflecting axle for internal overloading protection
Data Source
Figure 1
Figure 2a~2b
Figure 3a~3b
AI summary
The present invention relates to a measuring block for a fibre web machine, which measuring block (15) includes a support piece (16) and a fastening piece (17), which have been fastened to each other in a pivoting manner by means of a joint (18), as well as sensor devices (19), which have been adapted between the support piece (16) and the fastening piece (17) on the measuring block (15) in order to determine the tension of a fabric supported by a roll. There is a second support point (20) between the support piece (16) and the fastening piece (17), and the sensor devices (19) have been adapted in connection with the second support point (20).