Loom Timing & Shedding PDF
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Uploaded by CleanestIambicPentameter698
BUC University
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Summary
This document discusses the timing of loom operations, including shedding, in various weaving techniques. It explains how the crank shaft's position affects the operation of the loom's components and describes different types of shedding mechanisms. The document also covers different weaving patterns and how they impact the timing.
Full Transcript
Loom Timing & shedding Crank The loom pulley (machine pulley) gets motion directly from the motor pulley. The crank shaft, which has a special design, is connected with the loom pulley. (Ratio ????) The revolution per minute (r.p.m.) of the crank shaft is equal with the loom...
Loom Timing & shedding Crank The loom pulley (machine pulley) gets motion directly from the motor pulley. The crank shaft, which has a special design, is connected with the loom pulley. (Ratio ????) The revolution per minute (r.p.m.) of the crank shaft is equal with the loom speed (number of picks inserted per minute or picks/minute). The beat up operation is done by the reed which is carried by the sley and the latter is connected with the crank shaft. One revolution of crank shaft causes one beat up. Therefore, if 200 picks are being inserted per minute, 200 beat ups are required in one minute. Thus the r.p.m. of the crank shaft has to be 200. In case of plain weave, the shafts return to the same position after every two picks. Therefore, two shedding cams can be mounted on the bottom shaft for controlling the healds. However, for other weaves where more than two healds are required, a cam shaft (also known as tappet shaft) is used. For example, in case of 3×1 twill weave, shedding cycle extends over 4 pick. In this case, 4 shedding cams are mounted on cam shaft which rotates at 50 r.p.m. At 0, the reed reaches the forward most position and performs the beat up. On the other hand, at 180, the reed moves to the backward most position. The sley (and reed) moves forward and backward continuously during the entire 360. However, the healds do not move continuously. When the shed is completely open, the healds remain stationary for certain time so that shuttle can pass through the shed without any obstruction. This is called the ‘dwell’ period. Two types of timing of shedding (early and late) are generally used 1. Paddle/ treadle loom: hand loom 2. Tappet shedding mechanism 3. Dobby shedding mechanism 4. Jacquard shedding mechanism 5. Combined shedding
