Needle Bar Research Articles

Optimization research of RoHS compliance based on product lifecycle

As the European Union enacted the RoHS Directive, more and more companies are going to adapt themselves to RoHS compliance, which for many companies increases difficulty in controlling the content of hazardous substances as well as the cost of product. Meeting the requirements of the RoHS and lowering the cost are aims of the work. This paper has presented two models based on product lifecycle. One is zero-one integer linear programming model, and the other one is fuzzy zero-one integer linear programming model. In the end, we shall respectively apply the two models which are substantiated by Matlab to a needle bar of an industrial sewing machine.

Simulation Tests of the Feeding System Dynamics on a Warp Knitting Machine with Four Needle Bars

The article describes simulation tests of the basic element forming a spacer knitted struc- ture in a newly-designed warp knitting machine with 4 guide needle bars. It refers to a concept of forming 3D knitted fabrics already developed. In the first part of the article, the introduction, a geometric-kinematic model of the feeding and knitting zones is described. In the next part, the main one, a dynamic model of the key area isolated, that is the arrange- ment: beam-whip roll-guide needle bar of the filling, is presented. The method of perform - ing simulation tests of the model is described. Its susceptibility to input values in the range of values accepted was studied. The times of phases of the kinematic cycle, stiffness, damp- ing, initial load of the model elements and their mass were changed, variations in the initial values were registered: forces in warp threads, as well as the driving force and power. The significance of the research results for further stages of constructing 3D warp knitting ma - chines, mainly for the selection of driving actuators of the machine, is highlighted.

Modeling and Simulation Research of Time-Dependent Reliability Model of Link Rod in Needle Bar Mechanism

The time-dependent reliability model of Mechanical Component is influenced by many parameters such as stress, load, strength, strength degeneration and lifetime index. This paper builds the time-dependent reliability model when life is measured by the loading numbers. The variety law of mechanical component’s reliability with the lifetime is derived from the built model and simulation of link rod in needle bar mechanism used in the sewing machine. The result shows that the time-dependent reliability model is effective and the reliability of component decreases obviously with the loading numbers when the strength degeneration is considered.

Numerical Analysis of Sewing Air Floating Needle Bar Based on Slit Type Guide Rail

For the large air bearing capacity and high rigidity, the author put forward a kind of slit type guide rail which based on gas film clearance throttle,through establishing the guide physical model,fitting the gas film surface ,and building a flotation control equation, refering to the finite difference method and dichotomy,solved the gas film pressure distribution based on Matlab numerical calculation,analysed the bearing capacity of gas floating needle bar under different eccentricity and the stiffness.The results show that: the gas floating guide,if a slit’s width is 0.2 to 0.26,and the cumulative length of the slit for half of the perimeter of the inner surface,the slit intermittently arrange six along circumference,has the best static performance.The larger the needle bar eccentric,the bigger the flotation capacity and stiffness,it is capable of carrying the load of the needle bar,and the air tightness of the structure is good,throttling effect is obvious.

Study on dynamic needle thread tensions in a single needle lock stitch (SNLS) sewing machine. II. Effect of sewing speed, thickness of fabric plies, thread linear density and pre-tensions of threads

This paper reports on the effect of pre-tensions on needle and bobbin threads, sewing speed, thickness of fabric plies and the linear density of the threads on the tension peaks occurring on needle thread during sewing on a single needle lock stitch machine. The needle thread tensions are measured at two locations: above the needle bar (bottom segment) and above the needle thread tensioner (top segment). A factorial design approach is used to study the four parameters. The role of bobbin tension is studied in a separate experiment, while keeping the pre-tension on the needle thread constant. The highest tension observed on the needle thread is the stitch tightening tension which is directly affected by the pre-tension set on the needle thread disc tensioner. Heavier threads develop lower tightening tension which may affect the seam balance. The thickness of fabric plies does not affect the needle thread tension. Sewing speed has marginal influence on the stitch tightening tension near the needle thread tensioner. The pre-tension on the bobbin thread affects only the needle thread tension when the take up lever pulls up the needle thread loop to release it from the rotary shuttle hook gib.

Study on dynamic needle thread tensions in a single needle lock stitch (SNLS) sewing machine. I. Effect of stitch length, check spring tension, fabric feed timing and needle thread in-take length

This paper, the first of a two-part series, aims to find the effect of stitch length, check spring tension, fabric feed timing and needle thread in-take length on tension peaks occurring on a spun polyester needle thread during a sewing cycle of a SNLS sewing machine. The pre-tensions on the bobbin and needle threads and sewing speed were kept constant. A PC interfaced measuring instrument was fabricated to measure dynamic sewing tension on needle thread above the needle bar. Four prominent tension peaks were detected. Longer stitch length causes higher tension peaks; and shorter length stitch requires higher pre-tension to obtain a balanced stitch. The check spring tension has no effect on tightening tension. Incorrect timing of feed dog can cause very high tightening tension. The change in the position of thread length guide alters the friction of needle thread at critical guides which determines the length of thread to be released through tensioner; release of longer length of thread results in lower tension peaks (1, 2 and 4) and vice versa.

2C6-3 IMPROVEMENT OF NEEDLE BAR IN TEXTILE MACHINE BY HITTING PROCESS

The research conducted was to study the hitting process of a needle bar used within textile machinery and how to improve its efficiency and performance. A needle bar consists of a brass bar attached with a number of small pins. The primary focus was learning technique while straightening the needle bar. In order to join pins and brass bar together, the soldering is applied. The result from the heat transfer during soldering process can cause the brass pins to bend, which is undesirable for finished product. A soldering expertise uses hitting movement technique to modify and straighten the brass bar. Even though soldering process is the only step in making the brass bar; however, its method is considered very complicated and requires refinement and specialization from the maker.

Finite element analysis of penetration force for needle during tufting process

Tufted carpet is one of the most used carpets. The penetration force of needle is an important factor in tufting process. Few know how to calculate the penetration force during the tufting, although the principle is one of the least understood processes. This paper presents our research on using finite element method (FEM) to study the penetration force of needle during tufting. In this study, the model is developed using ABAQUS software, and the material properties of nonwoven fabric are approximately modeled by linear elastic orthogonal anisotropic continuum. The required engineering constants were obtained from experimental test. A user-defined subroutine VUMAT for characterizing the constitutive relationship of the orthogonal anisotropy nonwoven fabric and the damage evolution was compiled and connected with a commercial software package ABAQUS/Explicit to calculate the penetration force. At the same time, needle penetration force was tested by sensor mounted on needle bar of tufting machine. It was found that there is an approximate agreement of the penetration force between FEM calculations and experimental results. The reasonable agreement proves the validity of finite element analysis model, which could be used to calculate the impact response of the needle penetration stress precisely. The finite element model has been verified experimentally and can be used to study the influence of the key tufting parameters such as the backing material properties and the needle geometry on penetration force, which is vital for designing needle and driving mechanism.

Investigation on the impact and compression-after-impact properties of warp-knitted spacer fabrics

The paper reports an experimental study on the influence of spacer fabrics' structures, that is, different surface stitches, fabric thicknesses, and diameters of spacer yarns, on the impact and compression-after-impact properties of warp-knitted spacer fabrics. Low-velocity impact tests, damage deformation characterizations, and compression tests after impacts were performed on six spacer-fabric specimens knitted on a double needle bar Raschel knitting machine. The impact method was flat-sphere (a flat striker contacted with a fabric wrapped on a hemispherical steel anvil). Deformation processes of typical spacer fabrics, force–displacement/time and energy–time curves, impact damage, and residual strength were analyzed and discussed; moreover, peak force, absorbed energy, damage depth, and the drop-off rate of residual strength were involved to estimate impact and compression-after-impact properties of the spacer fabrics with different structures. The results show that with the closed surface structure and coarser spacer yarns, the fabrics have the characteristics of lower peak forces, higher energy-absorption ability, lower damage depths, and higher drop-off rates of residual strength. Fabrics with higher thickness are of the features above but they do have lower drop-off rates

Yarn Feeding Change Analysis for Needle Bar Transverse Shifting of Carpet Tufting Machine

The needle bar transverse shifting would likely form the stop mark on the tufted carpet. Focus on this problem, through analysis the change in yarn feeding path and loop pile forming, construct the mathematical model of length change of yarn feeding in path and usage of loop pile forming while needle bar shifting. Base on the mathematical model analysis key influence for yarn feeding path change. The analyze result is useful for yarn feed compensation solution

Yarn Feeding Change Analysis for Needle Bar Transverse Shifting of Carpet Tufting Machine

The needle bar transverse shifting would likely form the stop mark on the tufted carpet. Focus on this problem, through analysis the change in yarn feeding path and loop pile forming, construct the mathematical model of length change of yarn feeding in path and usage of loop pile forming while needle bar shifting. Base on the mathematical model analysis key influence for yarn feeding path change. The analyze result is useful for yarn feed compensation solution

Knitting Crafts and Products Design of the Double-Faced Jacquard Stitch

Jacquard stitch is widely used in clothing and many other areas in recent years. The paper describes the structural features, classification and knitting crafts of the jacquard stitch. Particularly are the knitting process and the locus of needles on the needle bar. However, newly design by the fancy appearance formation regularity is the emphasis of this paper. The design principle is according to the arrangement of color yarns and the drafting of new stitches. Cotton and polyester blended yarns are taken as the raw materials with several colors. Finally, a style of the double-faced jacquard stitch of the complementary yarns and a style of the sesame points are finished on the double-needle bar by the flat knitting machine.

Knitting Crafts and Products Design of the Double-Faced Jacquard Stitch

Jacquard stitch is widely used in clothing and many other areas in recent years. The paper describes the structural features, classification and knitting crafts of the jacquard stitch. Particularly are the knitting process and the locus of needles on the needle bar. However, newly design by the fancy appearance formation regularity is the emphasis of this paper. The design principle is according to the arrangement of color yarns and the drafting of new stitches. Cotton and polyester blended yarns are taken as the raw materials with several colors. Finally, a style of the double-faced jacquard stitch of the complementary yarns and a style of the sesame points are finished on the double-needle bar by the flat knitting machine.

Application of stitch-bonded multi‐plies made by using the extended warp knitting process: reinforcements with symmetrical layer arrangement for concrete

With the development of the extended stitch‐bonding process, an important modification of the production process for stitch‐bonded fabrics was realized. Through the introduction of a lateral shift of the needle bar, the stitch‐bonding process is essentially being changed compared with the working method used before. This has made possible the manufacturing of optimally adjusted textile semi‐finished products for numerous applications in the field of composite material. One such application – the usage of stitch‐bonded fabrics as a textile reinforcement for concrete – is analyzed in this article. It was observed that promising possibilities for the use of the extended stitch‐bonding process result from overcoming the known restrictions during the production with conventional stitch‐bonding machines. A markedly improved quality of textile reinforcement is achieved through the new binding patterns and the free arrangement of the layers. The reinforcement shows a verifiable better bonding behavior than the conventional method. Therefore, it is guaranteed that there is no spalling on the concrete surface at service load, which is an important prerequisite for the practical use of textile‐reinforced concrete.

Yarn Feeding Compensation Algorithm and Implementation for Needbar Transverse Shifting of Carpet Tufting Machine

The needle bar transverse shifting will likely form the stop mark liked gap on the tufted carpet. This paper proposed the yarn feeding compensation scheme and illustrate implement method in detail. Through analysis the change in yarn feeding path and loop pile forming of carpet tufting machine, construct the mathematical model of length change of yarn feeding in path and usage of loop pile forming while needle bar shifting. According to the mathematical model for yarn feeding compensation, calculate the additional yarn feeding requirement. Base on jacquard control principle, dynamic control the yarn feed actuator to drive the yarn feed roller to delivery additional length yarn, and produce loop pile with predefined pile height, Test result show the compensation is feasible.

Improvements in the warp-knitting process and new patterning techniques for stitch-bonded textiles

Stitch-bonding technology offers a highly effective process of manufacturing reinforcement textiles for composite materials. This innovative technology is based on joining layers of threads and fabric with a knitting thread to create a layered structure, a multi-ply. Thus far, the knitting thread has restricted the positioning of individual layers in the fabric. It has been impossible, until now, to position warp layers symmetrically in one step as the outer layers of the fabric. It has been accomplished as a multi-step process, which in turn compromises productivity and quality. With the needle shift technique as an extension of the stitch-bonding process, all previous restrictions on multi-plies are eliminated. Both outer warp layers can be secured in one procedure by incorporating a shift of the needle bar during the stitching process, creating endless possibilities for the arrangement and patterns in the stitch-bonding process. For the numerical description and diagramming of the new patterning techniques, we have reworked and expanded previous illustration models.

3-D Textiles for Advanced Cement Based Matrix Reinforcement

This article gives a definition for the wording 3-D textiles and presents the latest developments in the field of 3-D textile production. The double needle bar raschel technology has been improved by inserting straight reinforcement yarns inserted bi-axially on both sides of the textile. This is a completely new approach and allows a wide range of new applications. One major application of the bi-axially reinforced spacer fabrics is the `textile reinforced concrete' (TRC). In TRC, ready-made textiles can be used instead of single fibers in order to take full advantage of the fiber strength. As the 3-D textiles can be positioned conforming the load situation in three dimensions, they show a superior behavior from technical and economical point of view. A completely new type of 3-D-fabric is presented — warp knitted spacer fabrics for concrete applications.

Simulation of sewing machine mechanisms using program package ADAMS

Use of programme package ADAMS to simulate the sewing machine mechanisms is presented within this contribution. The simulation of needle bar mechanism was carried out. The influence of velocity changes of the main shaft on velocities and acceleration of sewing needle in the penetration area is described on the basis of simulation results. Achieved data could be used for calculation of needle penetration force. The influence of length modification of needle bar mechanism elements on sewing needle velocity and acceleration is also presented. This analysis could contribute to better understanding of sewing machine activity.

Transient Torque Produced in Arm Shaft of an Industrial Sewing Machine

This study considered the effects of needle penetrating force, needle thread tightening tension, and pressing force of the presser foot on torque produced in the arm shaft of an industrial sewing machine. The results obtained are as follows. (1) Penetrating force, especially the initial triangular wave fluctuation, induces noticeable transient vibration in torque. (2) The penetrating force is considerably more transient than the pressing force. The time ratio of the duration of the penetrating force to the natural period of the motion system is close to 1. (3) Consequently, when estimating torque, it is necessary that the arm shaft of the thread take-up lever and needle bar mechanism motion system be considered as elastic. On the other hand, the arm shaft of the feed mechanism motion system can be treated as a rigid body.

Sewing Dynamics

A measuring system has been developed to capture and analyze forces directly encountered by the needle bar and presser bar from a high speed sewing machine. The forces recorded from the needle bar reflect those encountered by needle penetration and withdrawal. The forces recorded from the presser bar are those transferred by the feed dog as it advances the fabric each sewing cycle. A measuring system known as the ncsu sewing dynamometer is capable of detecting changing sewing parameters, including variations in the material being sewn, increasing plies of fabric, frictional forces on the sewing needle, and the dynamics of the feeding system.