It must be closed before point A, otherwise the yarn will enter the hook groove and form cut pile; in order to ensure that the loop forming process is accurately in place, the middle of the hook yarn starting point a and the theoretical closing time point A of the reed is taken as the closing of the reed The completion time is shown in Figure 11. Point B is the time of the top dead center of the needle. At this time, the loop-forming hook is in the process of returning and has moved to the near dead center through the vertical position of the tufting needle. The yarn release time N slightly lags behind the needle top dead center 8. Set the lag time to 1/10T, that is, =1/10To. When the LCL tufting machine is looped for three adjacent cycles, the timing step diagram of the reed is shown in Figure 11.
In the figure: MN-spring leaf closing time period; NP-spring leaf not closing time period. The reed closing time in the alternate working cycle of loop pile and cut pile tc=O. 072s, accounting for 48% of the exercise period (0.15s). The unclosed time of the reed ￡=0.078s, which accounts for 52% of the motion cycle. During the time that the reed is not closed, the cylinder completes two actions: the cylinder begins to retreat at point IV and the cylinder extends to point P again. This requires that the cylinders in the jacquard mechanism of the LCL tufting machine in Figure 1 must meet the requirements of the sum of retraction and extension times not to exceed 52% of the mechanical working cycle under working load.
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