Flat Knitting Machine Movable Thread Guides Tension Control
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Solution Overview
Problem
Flat knitting machines face challenges in maintaining constant yarn tension ratios, especially with elastic knitting threads or when inserting weft threads, due to fixed thread guide distances that cannot be adjusted during the carriage stroke, leading to uneven thread tensions and poor quality of reverse edges in knitted fabrics.
Innovation Solution
The implementation of movable thread guides that can adjust their distance along the needle bed in both directions of movement, allowing for independent control of thread tension through separate drive devices and optional deflection rollers, brakes, and clamps to ensure consistent yarn feeding and storage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If stationary thread catching and thread storage devices are provided on the flat knitting machine, then thread tension differences are reduced, but the thread tension ratios cannot be adequately compensated for elastic knitting threads or when inserting weft threads
Solution Approach 1:
The patent makes the thread guide device movable instead of stationary, allowing it to move together with the carriage along the needle bed. The distance between the thread guide and yarn guide element can be dynamically adjusted during the carriage stroke by controlling their relative speeds, enabling real-time compensation of thread tension ratios for elastic threads and weft insertion while maintaining reliability
Solution Approach 2:
The patent changes the parameter of thread guide distance from fixed to variable. By adjusting the distance between the thread guide and yarn guide element during the carriage stroke through differential speed control, the system can compensate for thread elasticity and weft insertion requirements, transforming a static parameter into a dynamic one that adapts to different knitting conditions
2Device complexity
If the distance between thread guide and yarn guide element is constant during the entire carriage stroke, then the structure is simple, but the different thread tension ratios cannot be adequately compensated
Solution Approach 1:
The patent introduces dynamic movement capability to the thread guide device, allowing it to move independently relative to the yarn guide element during the carriage stroke. This dynamic adjustment of distance between components enables proper thread tension compensation without requiring overly complex mechanisms, as the movement is coordinated with the existing carriage motion
Solution Approach 2:
The movable thread guide device serves multiple functions: it guides the knitting thread, stores the thread loop, and dynamically adjusts thread tension through its movement. By combining these functions in a single device that moves with the carriage, the patent avoids increasing overall system complexity while achieving reliable thread tension ratio compensation
3Ease of operation
If the insertion thread guide is moved at higher speed than the feed thread guide, then the weft thread is pushed towards the insertion thread guide without tension, but the control system becomes more complex
Solution Approach 1:
The patent implements differential speed control where the insertion thread guide can move at different speeds than the feed thread guide during the carriage stroke. This dynamic speed variation allows the weft thread to be pushed toward the insertion point without tension, improving insertion quality. The control complexity is managed by coordinating this differential movement with the existing carriage stroke timing
Solution Approach 2:
The patent employs periodic acceleration and deceleration of the insertion thread guide relative to the feed thread guide during the carriage stroke. This periodic differential movement creates the necessary conditions for tension-free weft thread pushing at specific moments while maintaining synchronized operation overall, balancing operational quality with control system complexity
Data Source
AI summary
The invention relates to a flat knitting machine, which comprises at least one needle bed and at least one drop-in yarn guide (11) which is movable along the at least one needle bed and is provided with a yarn guide mechanism (16) for embedding the at least one knitting yarn (15) into a needle (17) in the needle bed; and at least one feed type yarn guide (10) feeding the at least one knitting yarn (15) to the at least one drop-in yarn guide (11), wherein the two yarn guides (10, 11) can be movable jointly along the at least one needle bed so that their mutual spacing (A) can be adjusted in each movement direction (12, 13) of the yarn guides (10, 11) during the associated movement along the at least one needle bed.