RESEARCH OF THE SYSTEM OF AUTOMATIC CONTROL OF THE THREAD TENSION SPEED IN THE SPINNING PROCESS

The paper deals with the creation of a mathematical model of the process of stretching the tape, taking into account the tension of the thread. For this purpose, the relationship between the thread tension and the speed of expression of the electric drives is determined. The proposed mathematical model of the process allows one to synthesize highly efficient control systems for spinning equipment.

Mathematical Modelling of Destabilization Stress Factors of Stable-Elastic Fixation of Distal Trans- and Suprasyndesmotic Fibular Fractures

Introduction. Specification of possible stress factors destabilizing the fibula stable osteosynthesis by the intramedullary nail with distal blocking and elastic fixation of distal syndesmosis by the thread with endobuttons by mathematical modelling of distal unstable ankle injuries. Material and Methods. We studied the thread tension during the combined stable-elastic fixation of unstable injuries of the ankle joint in cross-syndesmosis fractures of the fibula (B, C Danis–Weber classification), which includes a one-time stable minimally invasive fixation with the intramedullary nail and elastic fixation by the thread with endobuttons. We used a titanium alloy for the intramedullary nail and polyester for the thread. The deformed state was studied using the methods of mechanics. Results. A model of a fractured fibula blocked with the intramedullary nail and fixed with the elastic thread was developed. A formulation to specify the rational tension forces of the elastic thread depending on the parameters of the fibula and intramedullary blocking nail and on the location of the bone injury was obtained. The effect of foot rotation on the thread tension was investigated. The results of theoretical research should be implemented in medical practice. Conclusions. A mathematical model of the damaged fibula blocked by the intramedullary nail and fixed with the elastic thread was developed. Dependences for calculation of tension of the fixing thread were obtained. A slight increase in thread tension during foot rotation was found.

Dynamic environments do not appear to constrain spider web building behaviour

Many laboratory experiments demonstrate how orb-web spiders change the architecture of their webs in response to prey, surroundings and wind loading. The overall shape of the web and a range of other web parameters are determined by frame and anchor threads. In the wild, unlike the lab, the anchor threads are attached to branches and leaves that are not stationary but move, which affects the thread tension field. Here we experimentally test the effect of a moving support structure on the construction behaviour and web-parameters of the garden cross spider Araneus diadematus. We found no significant differences in building behaviour between rigid and moving anchors in total time spent and total distance covered nor in the percentage of the total time spent and distance covered to build the three major web components: radials, auxiliary and capture spirals. Moreover, measured key parameters of web-geometry were equally unaffected. These results call for re-evaluation of common understanding of spider webs as thread tensions are often considered to be a major factor guiding the spider during construction and web-operation.

Algorithmic and Computer Software for Determination of Thread Tension After Guide Large Curvacity

The conducted studies of the effect of the structure of the threads on the amount of tension when interacting with guides and working bodies of weaving machines and knitting machines, which have a large curvature in the zone of contact with the thread, established a mechanism for the process of increasing the tension of the thread after the guide by changing the radius of curvature of the guide and friction forces in the zone contact. It is proved that the increase in tension is explained by a change in the angle of coverage of the thread of a guide of large curvature, and for complex threads and yarns, the real angle of coverage will be greater than the calculated one, due to deformation of the thread diameter in the contact zone, and for monofilaments it is less than the calculated one due to bending stiffness. The sequential passage of the thread along the guides, from the entry zone to the formation zone of fabric and knitwear, leads to a stepwise increase in tension. In this case, the output parameter of the tension after the previous guide will be the input parameter for the subsequent guide, which makes it possible to use recursion when determining the tension in front of the formation zone. In this regard, research on the computer implementation of the algorithm for determining the thread tension on technological equipment using recursion should be considered relevant.

Study on the mechanics of textile thread in woven

Specialists in the weaving industry are often interested in the question of what tension of the warp and weft threads must be set on the weaving machine to produce a particular fabric. Along with this, they are interested in the question of what is the relationship between these parameters and the structure of the fabric, how much it is necessary to increase or decrease the tension of the warp and weft threads when changing the assortment of fabric. These problems arise because the correct thread tension on weaving machines increases the productivity of equipment and labor, and also improves the quality of the fabrics produced. The current state of the mechanics of a weighty deformable flexible thread on a plane and other forms of guides do not take into account the rigidity of the threads on the friction surface, since this parameter is determined by the type and type of threads, the linear density of the threads and the elastic properties of the threads. Therefore, the article analyzes the work on the mechanics of textile yarn and studies of the tension of the yarns were carried out depending on the radius of friction, angle of friction, coefficient of friction and stiffness of the yarns.

Efficient Design of the Sewing Machine's Shuttle Thread Tension Regulator

The paper presents the tension regulator of the Shuttle thread of the sewing machine, which consists of an arc-shaped plate spring, has two holes, the first for fixing the screw to the side surface of the bobbin cap and the second for the adjusting screw. In this case, the width of the plate spring along the entire length is the same. A disadvantage of the known design of the Shuttle thread tension regulator is that it is not possible to provide thread tension due to changes in the pressure force of the plate spring along its length in the areas of contact with the thread passing between the plate and the side surface.

The impact of sewing thread's tensile behavior and laundering process on the seam puckering of elastic and normal fabrics

PurposeThe aim of the present study is to consider the influence of the tensile behavior of fabric and sewing thread on the seam appearance.Design/methodology/approachIn this study, the formation of seam puckering on two elastic and normal woven fabrics was explored. In order to prepare samples, various sewing threads were applied. Test specimens were sewn under five different thread tension levels. Then the appearance of samples was evaluated subjectively to determine their seam puckering grade before and after the laundering process.FindingsThe obtained outcomes of this study present that although sewing thread tension increment decreases the seam pucker ranking in the similar sewing condition, elastic fabrics have a greater seam pucker grade compared to the normal fabric due to the fabric extension and contraction during sewing and after sewing process, respectively. In addition, the elastic strain of the sewing thread is the key factor that determined sewing thread's tendency to make seam puckering. Moreover, the laundry process due to the relaxation of the sewing thread decreases the seam pucker grade.Originality/valueThe consistency of the tensile property of fabric and sewing thread is a crucial parameter in improving the seam appearance and obtaining a smooth seam.

A model on the viscoelastic behavior of sewn knitted fabrics

Purpose Knitted fabrics have been widely used in a wide range of applications such as apparel industry. Since these fabrics are continuously subjected to the long-term tensile stresses or tensile creep in real conditions, investigation of viscoelastic behavior of sewn knitted fabrics would be important especially at the seamed area. The paper aims to discuss this issue. Design/methodology/approach A lockstitch machine was used to produce sewn samples by knitted fabric. Factors such as stitch per inch (SPI), thread tension and thread type were variables of the model. Tensile creep tests under constant load of 200 N were conducted, and creep compliance parameter D(t) of samples was obtained as a response variable. A successive residual method (SRM) was also used to characterize viscoelastic properties of sewn-seamed fabrics. Findings The instantaneous elastic responses of the seamed samples were less than those of the neat fabric (fabric with no seam). An increase in sewing thread strength increases the instantaneous elastic response of the sample. SPI and thread tension have an optimum value to increase E0. High tenacity polyester thread, due to its higher elastic modulus, caused a larger E0 than polyester/cotton thread in sewn knitted fabric. Characteristics of seam including sewing thread type, SPI and sewing tension have significant influence on T0. Sewn-seamed fabric by high modulus thread shows less viscous strain T0 than the neat fabric (fabric with no seam). Viscous strain T0 decreases as SPI changes from 8 to 4 and/or 12. SPI and thread tension have an optimum value to increase the viscous strain T0. E1 is the same for optimum seamed fabric and fabric sample but T1 is about two times greater for seamed fabric. Retarded time for creep recovery increases by sewing process but characteristics of seam have significant influence on E1 and T1. All sewn knitted fabric samples used in this study could be described by Burger’s model, which is a Maxwell model paralleled with a Kelvin one. Originality/value This paper is going to use a different method named successive residuals to model the creep behavior of seamed knitted fabric. On the whole, this paper paved a way to obtain viscoelastic constants of sewn-seamed knitted fabrics based on different sewing parameters such as the modulus of elasticity of the sewing thread, SPI and sewing thread tension.