Beating-up mechanism
The main function of the beating-up mechanism is to push the weft yarn introduced into the shed to the cloth fell, so that it can be closely interlaced with the warp yarn to form a fabric.
2. Types of beat-up mechanism
At present, water-jet looms mainly use connecting rod beat-up.
The connecting rod beat-up mechanism uses rods to convert the rotation of the main shaft of the loom into the swing of the reed. The most widely used is the four-link beat-up mechanism, and there are also six-link beat-up mechanisms based on the four-link. In addition, in order to adapt to certain fabric varieties, there are also some special multi-link beating mechanisms. Here we mainly introduce the four-link beating mechanism. The four-link beating-up mechanism has a simple structure, is easy to manufacture, is suitable for high-speed operation, and is widely used in shuttleless looms.
Figure 3-15 is a casual diagram of the four-link beat-up mechanism of a water-jet loom. A is the spindle, AB is the crank, BC is the connecting rod (hand), and D is the rocker shaft. Together they form a crank-rocker mechanism. The leisure characteristics of the four-bar linkage beat-up mechanism can be expressed by the leisure of point C. If the extension line C1 C2 connecting the two extreme positions of connecting rod BC passes through the center of the spindle, it is called an axial beating mechanism; otherwise, it is called a non-axial beating mechanism. Weft mechanism. The degree e to which the main axis center deviates from the C1 C2 line is called non-axial deflection. If the spindle center A is located above the C1 C2 line, then e is a positive value and the back dead center position is less than 180°; otherwise, it is a negative value and the back dead center position is The position is greater than 180°.
The ratio L/R of the length L of the connecting rod BC to the length R of the crank AB and the size of the non-axial deflection e all affect the relaxation of point C, that is, the relaxation of the reed. Among them, the main influence is the ratio L/R. According to the ratio L/R, the beat-up mechanism can be divided into long hand-held beat-up mechanism, medium hand-held beat-up mechanism and short hand-held beat-up mechanism. Generally speaking, when L/R>6, it is called a long-hand beating mechanism; when L/R=3~6, it is called a medium-hand beating mechanism; when L/R<3, it is called a short-hand beating mechanism. According to the linkage mechanism leisure analysis method, the leisure law of point C can be obtained. The shorter the connecting rod BC is, when the crank is at the front dead center (0°), the leisure acceleration of the reed is large, which is conducive to beating up. Therefore, the short hand beat-up mechanism is suitable for the weaving of wide and heavy fabrics, such as on water-jet looms. ,L/R<3, holding hands is quite short. However, the shorter the hand is, the greater the change in the acceleration of the reed will be, which will intensify the vibration of the loom and is not conducive to high speed. It is usually supplemented by a light reed base to adapt to high speed and reduce vibration. Medium and long hand-held beat-up mechanisms are mostly used on light-weight and narrow-width looms.
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