Experimental investigation and optimization of ends-together pneumatic splice chambers

Abstract

Pneumatic splice chambers are the industry method for splicing yarns. Most investigations in the literature occurred with ends-opposed splice chambers. For several applications, ends-together splicing is industrially interesting to consider. In this paper, we determine the importance of some process and splice chamber design parameters for ends-together splice chambers. We find that splicing pressure can be maximized, splicing duration needs to exceed a minimum duration and optimum splice length depends on yarn type and chamber design. Important splice chamber design parameters are chamber size and both yarn inlet and air inlet size relative to chamber size. This study also demonstrates the usefulness of three-dimensional printing to evaluate new splice chamber designs.Splicing yarns is an important part of automatic winders in textile machinery. More recently, the warp yarn creels can be removed by using automatic splicers. This opens up the perspective for changing the warp yarn type during weaving. This calls for an automatic splicer that can splice a wide range of yarns.The principle of pneumatic splicers is simple. Two yarns ends are put parallel to each other in a small chamber on top of an air inlet. A cover is placed over the chamber, after which an air jet is introduced at high speed through the bottom air inlet. The jet is highly turbulent. Due to the air-yarn interaction in this turbulent flow, the yarn ends first open and then join together in a splice.Several pneumatic splicers are available. When comparing splice performance between splicers, the following properties are used in the literature: RSS or Retained Splice Strength, which is the strength of a splice divided by the strength of the original yarn; RSE or Retained Splice Elongation, which is the elongation at break of a splice divided by elongation at break of the original yarn; RSD or Retained Splice Diameter, which is the diameter of the splice divided by the diameter of the original yarn; and RYA or Retained Yarn Appearance, which is a qualitative/subjective parameter of the appearance of the splice compared to the original yarn.Most existing research is for ends-opposed splice chambers in which the two yarns enter the splice chamber from opposing sides, while ends-together splicing is rare. The different splicing options are illustrated in Figure 1. First we will present the results of a literature review regarding the influence of machine parameters on the splice properties. Wet splicing, whereby a fine mist is added into the air flow, results in a larger RSS. 1 The splice nozzle type (air inlet) influences the RSS as well. 2 For the air pressure used to splice, it is found 3-5 that a minimum pressure is required for a successful splice, a further increase in pressure rapidly increases RSS until a maximum RSS is reached and usually Ghent University, Belgium

Numerical prediction and experimental analysis of ends-together yarn splicing

“…By extending the cutting position by 1.5 or 3 mm we observe higher strength at inlet pressure of 15 bar than at inlet pressure of 10 bar for all chambers. In De Meulemeester et al, 11 it was found that splice strength increases rapidly from zero after a certain minimum pressure, but then often reaches a plateau after which the strength no longer increases. For chambers 1 and 3 the splice strength reached a maximum at 12 bar, while the splice strength in chamber 2 kept increasing all the way up to the maximum achievable pressure of 15 bar.…”

“…The resulting average splice strength of 20 samples, as in De Meulemeester et al, 11 is listed in Tables 2 and 3.…”

“…The splice chambers used in the CFD study presented above were three-dimensional (3D) printed and tested on a splicing machine, as in De Meulemeester et al 11 The splicing machine can be used at pressures from 5 to 15 bar with splice duration from 10 to 5000 ms and has a fixed scissors position. The setup is given in Figure 10.…”

“…The basis of this paper is an experimental study on ends-together yarn splicing chambers, by De Meulemeester et al 11 . As opposed to the typical untwisting stage in most ends-opposed splicers, no untwisting stage is present in this study.…”

Numerical and experimental study on the joint forming mechanism in the pneumatic splicing process

“…In the experimental study performed by Baykaldi et al, 8 the breaking strength was found to be affected by splicing air pressure, splicing duration, twist factor, and linear density for cotton/elastane yarns, and the parameters that affected breaking elongation and the diameter of the spliced yarn are the inlet air pressure and twist factor. De Meulemeester et al 9 concluded that a high strength spliced joint was the consequence of maximum air inlet pressure, minimum splicing duration, and optimized chamber structure by employing a Design of Experiment (DOE) method. Although those works have been done to facilitate optimizing the configuration parameters of the splicing process, they lack direct understanding of the filament motion.…”