Knitting Yarn Stop Detection Using Loop Count Timing
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Solution Overview
Problem
Conventional yarn detection systems in knitting lines, especially those with discontinuous operation, struggle to distinguish accidental stops from controlled stops without dedicated sensors, leading to potential defects and increased complexity and cost.
Innovation Solution
The method employs pulse signals from existing loop count sensors to detect accidental yarn stops by calculating and updating a threshold time interval based on the machine's speed, allowing for real-time comparison and machine intervention without additional sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If mechanical sensors are used to detect yarn stops, then cost is reduced, but response quickness deteriorates and yarn-feeding tension is interfered with
Solution Approach 1:
The patent replaces mechanical yarn-stop sensors with an electronic detection system that uses the existing loop count sensor signals. The control unit analyzes the timing intervals between consecutive loop detection signals to identify yarn stops, eliminating mechanical sensing components while improving response speed and avoiding interference with yarn tension.
2Speed
If electronic sensors are used to detect yarn stops, then response quickness is improved and yarn tension is not interfered with, but system cost and complexity increase
Solution Approach 1:
The patent makes the existing loop count sensor serve a dual function: counting loops for yarn feeder control and detecting yarn stops by analyzing timing intervals. This eliminates the need for separate dedicated stop sensors, reducing system complexity and cost while maintaining fast electronic response capability.
Solution Approach 2:
The system uses its own existing sensor signals to detect yarn stops, making the loop count sensor self-sufficient for multiple detection purposes. The control unit processes the timing information from the same sensor that monitors loop counts, eliminating dependency on additional sensing components.
3Device complexity
If existing loop count sensor signals are used to detect stops, then dedicated sensors are eliminated, but the method is not suitable for discontinuous operation where controlled stops occur
Solution Approach 1:
The patent stores reference timing interval data during a preliminary learning phase when the knitting machine operates normally. These reference values represent the expected timing between loop detections under various operating conditions. During actual operation, detected timing intervals are compared against these pre-stored references to distinguish accidental stops from controlled pauses in discontinuous operation modes.
Solution Approach 2:
The system continuously monitors the actual timing intervals between loop detection signals and compares them with stored reference intervals. When a significant deviation is detected, the system identifies it as an accidental yarn stop. This feedback mechanism enables the system to adapt to discontinuous operation modes while maintaining accurate stop detection capability.
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
This approach effectively detects accidental yarn stops in both continuous and discontinuous knitting operations, reducing the risk of defects and operational complexity while eliminating the need for dedicated sensors, thus lowering costs and improving response time.
Implementation Method 1
the motion of the yarn is detected by a photoelectric sensor
Data Source
Figure 1
Figure 2~3
AI summary
A knitting line comprises a plurality of yam feeders (A1, A2, ..., An) from which a downstream machine (KM) draws respective yarns (F1, F2, ..., Fn). The machine (KM) is provided with selection means (Z1, Z2, ..., Zn) adapted to vary the state of selection of the yam feeders (A1, A2, ..., An) in relation to the angular position of the machine (KM). Each of the yam feeders (A1, A2, ..., An) is provided with a stationary drum (12) and with a yam count sensor (S3) arranged to generate a pulse per each yam loop unwound from the drum (12). A selection signal (SEL_ON/OFF) is periodically sent to the yam feeders (A1, A2, ..., An), which is indicative of the state of selection of the individual feeders in relation to the angular position of the machine (KM). For each of the selected feeders, a treshold time interval (MWT) is continuosly calculated, which corresponds to the maximum interval between two successive pulses, above which it should be regarded that an accidental stop of the yam has occurred, and is updated in real time as a funcion of the yarn-drawing speed, the delay (DT) from the last pulse is continuosly measured and compared with the updated treshold time interval (MWT), and the downstream machine (F_stop) is stopped when the measured delay (DT) exceeds the updated treshold interval (MWT).