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The movement characteristics of yarn in the profiled reed groove of an air-jet loom can have a great impact on the performance of the fabric. Unstable yarn movement tends to lead to weft defects, as short wefts or weft breaks may occur, which could deteriorate the quality of the final fabric. In this paper, the characteristics of the yarn movement in a profiled reed groove are numerically studied. The arbitrary Lagrangian–Eulerian method is used to solve the two-way airflow–yarn interaction and the yarn is simulated with the ball–socket model. A fluctuation ratio is defined to characterize the unsteadiness of the yarn movement. Our simulation first investigates the effect of the gap ratio of the profiled reed groove (β) on the yarn movement then compares the movements of different yarn kinds. The simulation results indicate that a larger β not only decreases gas leaks (thus saves gas consumption), but also stabilizes the yarn movement. Our simulation results also show that the movement of the yarn of polypropylene is more stable than the other two weft-yarn materials. An experiment is also conducted to validate our numerical results, which shows a favorable agreement between them. Our numerical results of the yarn movement in the profiled reed groove can provide a valuable insight into the optimization of the weft insertion system of the air-jet loom. [ABSTRACT FROM AUTHOR]

Traditional proportional–integral–derivative (PID) control performance optimization is an essential method to improve a loom's warp tension control performance. This work proposes an improved genetic algorithm optimized PID control scheme to overcome the decline in control performance of the traditional PID control algorithm in a loom's warp tension control system. Through the decoupling analysis of loom motion mechanism, the establishment of warp tension model and the optimization of fitness evaluation mechanism of genetic algorithm can effectively overcome the problems of local optimal solution and algorithm degradation of genetic algorithm. Simulation experiments were carried out with the traditional PID, the integral separation PID, and the genetic PID in warp tension control. The results show the advantage of the genetic-PID algorithm to control warp tension stability. Ultimately, according to the functional characteristics of the loom mechanism, a tension control platform for experimental studies was established. The test results show that the maximum fluctuation range of warp tension is within [−2, +6] at the test speed of 850 rpm, which meets the requirements of long-term stable and reliable control of warp tension under different weaving conditions. [ABSTRACT FROM AUTHOR]

In air-jet weaving looms, the main nozzle pulls the yarn from the prewinder by means of a high velocity air flow. The flexible yarn is excited by the flow and exhibits high amplitude oscillations. The motion of the yarn is important for the reliability and the attainable speed of the insertion. Fluid-structure interaction simulations calculate the interaction between the air flow and the yarn motion and could provide additional insight into yarn behavior. However, the use of an arbitrary Lagrangian–Eulerian approach for the deforming fluid domain around a flexible yarn typically results in severe mesh degradation, vastly reducing the accuracy of the calculations or limiting the physical time that can be simulated. In this research, the feasibility of using a Chimera technique to simulate the motion of a yarn interacting with the air flow from a main nozzle was investigated. This methodology combines a fixed background grid with a moving component grid deforming along with the yarn. The component grid is, however, not constrained by the boundaries of the flow domain allowing for large deformations with limited mesh degradation. Two separate cases were investigated. In the first case, the yarn was considered to be clamped at the main nozzle inlet. For the second case, the yarn was allowed to move axially as the main nozzle pulled it from a drum storage system. [ABSTRACT FROM AUTHOR]

Defect identification and classification has been a focal point in fabric inspection research, and remains challenging because of new microstructure defects occurring in twill grey panting fabrics weaved on modern looms such as Air jet looms and Rapier looms. The twill fabric defects that occur commonly on these auto looms are mostly localized microstructure defects such as looseweft and stitches. This paper focusses on the application of DC suppressed Fourier power spectrum obtained from Fourier Transform for the analysis of fabric images in terms of significant frequency contents, which depict the periodicity of fabric along with their magnitudes, magnitude sums between peaks and the fabric cover factor of the woven fabric, in order to identify the fabric faults. The analysis was carried out on real twill weave grey fabric of different fabric specifications by collecting as many as 27 statistical features along with fabric cover factor obtained from the marginals of DC suppressed Fourier power spectrum which were used as inputs to the neural network implementing Levenberg-Marquardt Back-propagation algorithm. The results of the neural network, optimized with 27(40) neurons in the input, a hidden layer and 3(2) neurons in the output layer respectively for the two fabric classes namely S1(S2), for identification of grey fabric defects are encouraging. The neural network converged in less than 35 iterations and gave a classification accuracy of almost 100% when compared to the NN classification rate of 89.28% without considering fabric cover factor. The details of the experimentation and the results thereof are presented in this paper. [ABSTRACT FROM PUBLISHER]

Random-velour needling technology uses not only a modified needle loom in which the bed-plate is replaced by a moveable brush conveyor but also specially designed needles known as fork needles are employed. In this study, in order to measure the net force exerted on fork needles and contributing forces due to factors such as vibration, inertia and resistances of brush and fibrous matt, a twin force measuring unit was developed. It was found that the magnitude of the contributing forces is strongly related to factors such as loom vibration, needle inertia and rigidity of both the conveyor surface and the fibrous matt. Quantification of the net punching force and the related factors are of vital importance in the engineering design of fork needles and random-velour looms, which in turn leads to production of high performance products at lower costs. [ABSTRACT FROM PUBLISHER]

The flow field inside an air-jet loom main nozzle is studied numerically, by means of a two-dimensional model implemented in the commercial computational fluid dynamics (CFD) code Fluent. In order to determine which physical model could allow a better prediction of the nozzle behavior, preliminary simulations were carried out on a basic geometry configuration, changing flow models and comparing results with available experimental data. Having done the model setup, simulations aimed at evaluating drag force on the weft yarn were performed on various geometry configurations; in particular, the influence of acceleration tube length, shape and size on drag force was evaluated. Results gave some guidelines for future prototyping and experimentation. [ABSTRACT FROM AUTHOR]

This paper deals with the three-dimensional computer simulation of the weft insertion process as a possible solution to avoid costly weaving trials when researching this process. A three-dimensional mathematical model of the yarn was developed, in which the behavior of the yarn was described by the Second Law of Newton. For this mathematical model, a second order differential equation needed to be solved. To this end, an explicit integration using Euler's method was chosen. In order to validate the model, high-speed camera recordings were performed on a test stand and compared with simulations of the same test stand. A very good resemblance was found between simulation and camera recordings. This is the first time that a three-dimensional model for the weft insertion on air-jet looms has been successfully tested. [ABSTRACT FROM AUTHOR]

In this study, a mechanism model is introduced then kinematic design and analysis equations are presented for a rotary dobby. Heald frame motion curve is obtained and analyzed. Mechanism parameters affecting heald frame motion are discussed. It is shown that heald frame motion characteristics were mainly determined by the design of modulator mechanism. Eccentric mechanism of a rotary dobby also had a significant effect on heald frame motion. [ABSTRACT FROM AUTHOR]

In this paper, we use an oblique scanning method with an image scanner to capture the fabric surface image on the running air-jet loom and to develop a new approach to measure the fluctuation of the cloth fell point during weaving. Based on our theoretical analysis of the cloth structure formation process, we also propose a fluctuation index of woven fabric in the cloth fell as an evaluation parameter for stable beating-up motion during weaving. [ABSTRACT FROM AUTHOR]

Presents a study that examined the processibility and properties of polyester and cotton blends on the H1 technology needle loom from Fehrer AG. Methodology; Characterization of the surface mechanical properties of blended H1 webs; Measurement of the physical properties of needle-punched nonwovens.