Design And Study Of Beat-up Mechanism And Weft Insertion Mechanism Of High-powered Rapier Looms

Among all kinds of shuttleless looms, rapier looms develop fastest and have a brighter future. In China, the proportion of modern high speed weaving machines is very small. To meet the needs of the development of Chinese textile industry, we should do more research on foreign advanced looms, and design new types of rapier loom in our possession. Being the most important mechanism of a rapier loom, beat-up and weft insertion mechanism should get more attention.This paper begins with an overview of the beat-up and weft insertion mechanisms which are used by advanced rapier looms in the world, and then analyzes the kinetic characteristic of these mechanisms. By comparing all kinds of beat-up and weft insertion mechanisms, we find out that the ones which use the spatial spherical crank model are superior, so in the new design ,we deal with the beat-up and weft insertion mechanism in this way.It is widely acknowledged that spatial 4R mechanism is a special form of spatial RSSR mechanism, so, we have to design RSSR mechanism first, and then transfer spatial RSSR mechanism to spatial 4Rmechanism in spherical coordinate system in order to make a detailed analysis. And what's more, the weft insertion mechanism of advanced loom FAST is also used to be a contrast when we design this new machine.In this paper, using D-H coordinate system we write out the kinetic equations of weft insertion mechanism based on equivalence property of motion and the dynamical equations based on Newton-Euler method. According to these equations mentioned above, we can derive the relations of the motion of different components and how these components change under stress.In this new design, we apply cam and counter cam mechanism to the beat-up mechanism. We put forward a new idea of using the modified sine or cosine curve to describe the beat-up curve instead of traditional ones.We scheme out the basic size of this mechanism according to the allowable pressure angle, and derive general formula of the contour line of cam and counter cam after deducing. Finally we can easily get both the main and the vice contour line and their values in polar coordinate system.After the initial design completely finished, it is essential to use virtual prototyping techniques to emulate the prototype in order to get further analysis of the kinetic and dynamical curves. When comparing thebeat-up and weft insertion mechanisms of this new machine with those of advanced loom FAST, it is apparent to come to the conclusion that the kinetic characteristic of the former is superior to the later.Under working condition, load of a rapier loom focuses mainly on the beat-up mechanism, and besides rocking shaft is one of the most critical components to achieve this beat-up function. When at work, the beat-up cam will transmit great force to the roller of the brackets of rocking shaft, and then the force is transmitted from roller axis to rocking shaft. This paper presents the FEA analysis of rocking shaft as well.In a word, the study of this project has great social and economic significance, and the findings of the project can also provide relevant industries some valuable information as reference.