Weft Insertion Research Articles

The Stability of Weft Insertion of CRT – 83 Carpet Rapier Loom

CRT- 83 carpet rapier loom is a kind of high-grade rigid rapier loom，the weft yarn will give looms to demand higher stability of the weft insertion. Theoretical analysis based on the theory research of the stability of clamping weft and weft handover shows that the rapier deformation，slipping force and the depth of clamping are main factors influencing the stability of weft insertion.In order to obtain reasonable process of weft insertion，concerned with the following factors：the grip length and outrigger length of rapier，release times of clip yarn device，initial deformation angle of spring piece.

Investigation on Tensile Properties of Weft Insertion Warp Knitted Fabric Reinforced Composites

Warp knitted fabrics possess a number of changes in the structures, so they do have great advantages on the property design of composites. The three kinds of weft insertion warp knitted fabrics are knitted on a Raschel latch needle warp knitting machine with glass continuous-filament yarns. The warp knitted fabric/ unsaturated polyester resin composite laminates are produced by manual molding technology. The tensile properties of composites in the course, wale and diagonal directions are tested on the universal material testing machine. The results show that the tensile stress/strain curves of the composites were nonlinear. The tensile properties of the composites possess obvious anisotropic characteristics. The tensile strengths and elastic modulus of the warp knitting composites depend on the needle space number of inlaid yarn, fabric density and structure.

Design and Implementation of Yarn Tension Measurement System during Weft Insertion on Air-Jet Loom

Yarn tension during weft insertion is one of important factors which affect fabric properties. In air jet loom, many components have an influence on yarn tension, such as clamp, main nozzle, sub nozzle, brake, and the drum. In this paper, a measurement system for yarn tension experiment which based on a 32-bit Cortex-M3 embedded processor was designed and implemented. The system can control components at fixed time interval which is set by a supervisory computer, acquire yarn tension converted by a contacted electromagnetic induction tension sensor, and then transmit tension data to software system by Ethernet module. An experiment is conducted for research character of yarn tension driven by air flow. The experiment results indicate that the nozzle pressure and yarn diameter play an important role in yarn tension during weft insertion on air-jet loom. Besides, the delay of magnetic value is also considered under different nozzle pressure.

Research on Electric Weft Insertion Method for the Rapier Loom

This paper, on analyses of the shortages of the traditional rapier loom weft insertion system such as unalterable motion rules and high machining accuracy requirements, introduces a new electric weft insertion method to the modern high-speed rapier loom, which converts single-direction rotation of a motor to linear reciprocation of a rapier with help of the spatial linkage. The new method can satisfy different weft insertion requirements by controlling the speed of the motor rotation, so that it greatly improves the weaving adaptivity of the loom for different wefts. The test results show that this new controlling method not only meets the technical requirements, enabling the gripper head to move without rigid and flexible impact, but also has good high-speed motion characteristics, in line with the requirements of high-speed weft insertion.

Model for Yarn Transport Systems

In textile production the yarn is being withdrawn from cross-wound packages in warping and weft insertion. During unwinding there appear forces in the yarn that are approximately proportional to the square of the unwinding velocity. During unwind the yarn tension is not constant, but it oscillates within some interval. This is especially noticeable in over-end unwinding from a static cross wound packages, where the yarn is being withdrawn with a high velocity in the direction of the package axis. Even when the yarn is not strongly stressed, so that the tension does not exceed a few percent of the breaking strength, the yarn still can break sometimes. This is why we think that a cross-wound package is not an ideal form of a package and that such packages are not always made without flaws.

Flexibility Analysis of the Cross Axis and Furcated Frame in the Spatial 4-Bar Linkage Weft Insertion Mechanism

In this paper, the flexibility of the cross axis and furcated frame of high speed rapier loom was considered through the change of the two components’ material. Corresponding neutral documents were generated in ANSYS, then with the ANSYS-ADAMS co-simulation, those neutral documents were imported into ADAMS. The motion curves of sword belt were received. Through the map analysis and comparison, the relationship of changing the two components’ material and the motion curves of sword belt were found. The simulation results show that, in consideration of the flexible components, rational selection of the component material can greatly reduce the impact on Spatial four bar linkage weft insertion mechanism, thereby enhance the quality of the fabric.

The Implementation of the Air Jet Loom High-Precision Weft Insertion Control System Based on FPGA

With the respect of the problem of that the control precision of air jet loom weft insertion control system can not satisfy the requirement of the high-speed loom, this article presented a high-precision weft insertion control system taking FPGA as the control core, and it designed hardware circuit and software framework. This control system generates weft insertion control signal which is figured out through the parallel execution of the FPGA program. The practice shows that the system owns the features of high control precision, good consistency and so on, and it has a significant importance to the high-speed development of air jet loom.

Study of a Electromagnetic Weft Insertion in Textile Machine

Based on the in-depth study of traditional weft insertion apparatus, the electromagnetic technology was introduced into the textile machines. A new textile machine was researched whose shuttle was moved by the electromagnetic force. The electromagnetic force was generated by electromagnetic coil. The electromagnetic shuttle was moved fast in the shuttle path by the electromagnetic force. Through this technique, the weft insertion movement was accomplished and a defect was remedied that aroused by the traditional weft insertion apparatus. The weaving question which is width of cloth was solved by the new technique. At the same time, the structure of electromagnetic weft shuttle and the working which is the single shuttle and two weft was designed. The speed impact factors of electromagnetic shuttle was study in the angle of mechanics. The control method is the acceleration in the first half and the deceleration in the second half.

Twin optical sensor based instrument for the measurement of weft velocity in air-jet weaving

A previous paper described the effectiveness and application advantages provided by a single opto-electronic sensor based instrument for weft velocity measurement in air-jet weaving. Consideration of further refinement of the instrument, particularly for improving the smoothness of the weft velocity curve obtained by using it, indicated possible advantages of developing it as a twin sensor based design. This would enable two time related data streams and their analysis by use of the cross-correlation technique, which would primarily help in reducing errors of weft velocity determination due to possible variation of the uniformity of center distance between yarn markings. This paper reports on the evaluation of the performance of the modified instrument which was found to be superior to that of the single sensor based device. More significantly, given the ease with which a large number of repetitive measurements can be made using it, this development also led to the very useful outcome that it enables obtaining a close estimate of the ‘true’ weft velocity curve for a given set of weft insertion settings. The overall size of the modified sensor has remained the same as before, so mounting it on the weaving machine is just as simple as before.

Yarn motion during unwinding from packages

We study the motion of yarn modelled as a one-dimensional inelastic string. In textile production, the yarn is being withdrawn from cross-wound packages in warping and weft insertion. During unwinding, there appear forces in the yarn that are approximately proportional to the square of the unwinding velocity. The yarn tension is not constant, but it oscillates within some interval. This is especially noticeable in over-end unwinding from a static cross-wound package. Even when the yarn is not strongly stressed, so that the tension never exceeds a few percent of the breaking strength, the yarn can still break sometimes. The production process requires as large warping and weaving speeds as possible; therefore, it is necessary to improve our understanding of the cross-wound package unwinding and to find the necessary modifications of the yarn unwinding process. In addition to empirical tests, it has proved useful to study yarn unwinding by mathematical modelling and computer simulations. We state the equations of motion that describe the yarn unwinding and develop a mathematical model that permits to simulate the process of unwinding.

Analysis of Rod Length Change in the Rapier Weft Insertion Mechanism Transmitted by Spatial Four Bars

In order to analysis kinematics characteristic of space four bar linkage weft insertion mechanism and the influence on movement law by connecting rod length change, mathematical models of every parts of the mechanism were proposed by the method of analysis, and through MATLAB programming, motion curves were obtained. The length range of connecting rod and rocker, and the impact of changes in length were also studied, and some corresponding conclusions were drawn. The motion characteristic curve of it has been in accord with the weft inserting requirements. The study of kinematics, especially the discussion of connecting rod length changes will pave the way for the further study of dynamics.

Study of a New Electromagnetic Weft Insertion Mechanism Based on the PLC

Based on the in-depth study of traditional weft insertion mechanism, the electromagnetic technology was introduced into the textile machinery, a new weft insertion mechanism was designed whose shuttle was moved fast in the shed by the electromagnetic force. The electromagnetic force was generated by electromagnetic coils. Meanwhile, the PLC control system which control the new electromagnetic weft insertion mechanism was devised to achieve the high speed of the shuttle.

Flow Field Simulation of the Solo-Supported High Pressure Gas Device of Double-Layer Air Jet Looms

A research program is currently underway with the purpose of developing a double-layer air jet looms with solo-supported gas device. Issues related to the design and feasibility analysis of the solo-supported high pressure gas device are discussed. The results of simulations show that assistant nozzle is necessary during weft insertion motion, but too many assistant nozzles would cause the flow velocity reduce. And it is confirmed that flow channel with one main and four assistant nozzles is one of the best designs to keep the flow velocity at the middle line of flow channel more than 90m/s and make the loom work swimmingly.

New production method for a plain weave figured fabric

A new production method for figured fabric has been developed. The figured fabric generated in this study is a plain weave piled fabric and it shows the same figure on both sides unlike those fabrics woven on dobby or jacquard looms. It is woven by a specialty yarn called the chenille yarn which is obtained by separating each warp of a base fabric woven in leno structure. The base fabric is woven by inserting different colored weft each time in a certain sequence arranged according to the target figure image. A CAD software and a computerized controller have been developed to control all the motions of a conventional rapier loom and to handle the numerous weft insertion schedule efficiently.

Development of fluidic weft insertion sensors

Measuring the speed of weft insertion into the shed of warp threads on a jet loom is a difficult problem, sometimes described as nearly impossible to solve. A solution was found by the author in an inversion of the basic principle of shuttle-less air-jet loom, i.e. using the dragging action between the weft and air flow. Initially, the analogy went as far as using also an air jet – issuing from a nozzle through which the weft passes – as the flow influenced by the weft motion. Recent studies, described in this paper, have shown that better performance is obtained by the weft/air interaction in long, small-diameter channels.

Investigation of Some Handle Properties of Fabrics Woven with Two Folded Yarns of Different Spinning Systems

In this study, in order to observe the effect of spinning systems such as ring, rotor and vortex, and twist direction of the folded yarns on the fabric handle properties, single end yarns were produced in the same yarn count, yarn twist, and twist directions. After that, the single end yarns were folded on the same doubling machine in two twist directions of S and Z. These folded yarns were used as weft yarns in the woven fabrics. In addition to these parameters, four different weft insertion orders were tried (SSSS, ZZZZ, SSZZ, SZSZ) to be observed whether the insertion order makes any difference in the handle values of the fabrics. It was concluded from the study that handle properties of the fabrics produced with ring folded yarns are better than the ones produced with rotor and vortex folded yarns regardless of the weft insertion order. The fabrics produced with SSSS weft insertion order are the softest among all fabrics in all spinning systems. Besides, using the weft insertion order of SZSZ makes the fabric softer than SSZZ.

An investigation into the weft insertion periodic errors in fabric using an image analysis method

One of the effective parameters on the balanced weaving conditions with uniform weft density is the rate of fabric take-up that should be equal to pick-spacing in each cycle. The purpose of this research was to investigate the effect of periodic errors of take-up system on the rate at which the faults occurred in the fabric. While correcting a fault during weaving operation in fabric, some new errors were made periodically using a stepper motor and variations of pick-spacing were measured. When faults were created in the take-up system, generated weft strips in fabric were extracted by the image analysis method. The results show that the periodic faults in the fabric are stopped at a specified level depending on the alternation of the error.

Three-dimensional Simulation of the Dynamic Yarn Behavior on Air-jet Looms

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.

FLAT KNITTING OF A LIGHT EMITTING TEXTILE WITH OPTICAL FIBRES

Abstract Knitted products have a flexibility that offers many attractive possibilities. Combined with technical fibres, this gives interesting and innovative possibilities. Many technical fibres and yarns has however properties such as high stiffness and brittleness which are difficult to process in the practice of weft knitting. This paper is about the experimental product development of a light radiating textile lamp in which optical fibres are used as the only illumination source. The lampshade is produced on an electronic flat knitting machine with special equipment suitable for the feeding of yarn with high stiffness. The work was divided in two parts: exploring the possibilities to knit the desired shape on one hand and experimenting about knitting with optical fibres as a weft insertion on the other hand. The method is an inductive approach; a literature survey, information from suppliers of knitting production equipment and experimental work on a flat knitting machine at The Swedish School of Textiles, Boras, Sweden. Results show that the diamond shaped structure can be knitted in one piece with transparent monofilament yarns. Furthermore it also shows that difficulties occur when knitting with stiff and brittle optical fibres therefore the paper ends with a discussion with suggestions of how to overcome these challenges.

Air-jet 직기 특성이 감성 교직물의 촉감에 미치는 영향

The hand of the sensitive mixture fabrics was analysed and discussed with measured mechanical properties of two kinds of woven fabrics according to the characteristics of air-jet loom. The 16 mechanical properties such as tensile, bending, shear, compression and surface were measured using KES-FB system and their differences of the mechanical properties between domestic and foreign looms were analysed with the deviation according to the position of the specimen. And also these mechanical properties according to the domestic and Japan air-jet looms were analysed and discussed with warp and weft insertion tensions during weaving. This research is aiming to make a data base of fabric mechanical properties and, these analysed data are given to weaver as a basic research data related to the effects of loom characteristics to the sensitive mixture fabrics required from weaving fields.