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Schema of upper mechanisms of sewing machine. Needle bar mechanism and thread feeder mechanism with additional balancing mechanism.
Source publication
This paper deals with the modeling and optimization of mechanical system, focusing on industrial sewing machines in order to reduce the vibrations by balanc-ing. It presents creation of model of mechanisms and their optimization using Modelica language through software MathModelica and Mathematica. Both ad-vantages and drawbacks of this approach ar...
Context in source publication
Context 1
... mass is near the axis of rotation so balancing using rotatory balancers can´t help much. Significant reduction of the total force is possible to achieve using a balancing me- chanism and one rotatory balancer. In our case it consists from connecting rod that is mounted on the crank shaft on the opposite side of the needle bar crank and balancer (fig. 4). The balancer has small stroke but large mass. Also there is one rotatory ba- lancer placed on the crank ...
Citations
... However, there is still a clear gap in implementing these approaches in synthesizing mechanisms of sewing machines. As few examples in this context, vibrations reduction of industrial sewing machines by eccentric balancing of crank mechanism of the needle bar is presented in [1], [2]. The authors of deal with method of balancing optimization of a very complex set of sewing machine mechanisms using Adams and Mathematica Softwares [3]. ...
Sewing is one of the most commonly used manufacturing processes in the world. In the textile industry, development of sewing machines with optimal mechanical performance is very important. Obviously, the quality of sewing, increase of the needle transmission force and the optimal mechanical advantage are greatly dependent on the design criteria of the needle driving mechanism. Therefore, in this paper, first a newly developed needle driving mechanism of a sewing machine is introduced. Then, the concepts of transmission angle and mechanical advantage are described. Next, the multiobjective constrained optimization of this mechanism using the genetic algorithm is explained. The objective functions of the optimization problem are considered in such a way to fulfil some of the most important design criteria such as reducing the needle generated heat, reducing undesirable vibrations and increasing the mechanical performance. The obtained results confirm improvement of the required design criteria of the newly developed mechanism in this study. It is also concluded that improving the mechanical advantage of about 14% causes an increase in the value of the needle jerk about 30%. This clearly states that higher mechanical advantage, is achieved by the cost of increasing the needle jerk.
