The fixed drum type weft feeder uses a yarn storage drum with a large moment of inertia as the yarn winding and revolving part, which is obviously very disadvantageous for high-speed looms. Therefore, the fixed drum type weft feeder, which replaces the yarn storage drum with the light weight and small volume yarn winding disk as the yarn winding rotating part, has been developed rapidly. At present, there are many structural forms of fixed drum weft feeders, and their principle of action is basically the same.
The weft yarn is unwound from the bobbin at a high speed, and is led out from the hollow tube of the winding reel through the hollow shaft of the yarn tensioner and the motor. When the motor rotates, the hollow shaft drives the yarn winding disc to rotate to wind the yarn onto the yarn storage drum. Because the yarn storage drum is supported on this hollow shaft through rolling bearings, in order to keep the yarn storage drum immobile and provide the necessary yarn passages at the same time, the yarn storage drum and frame on both sides of the winding reel are installed separately The powerful front and rear magnet plates play the role of "fixing" the yarn storage drum on the frame.
The rotation direction of the feeder motor ("Z" direction or "S" direction) must be consistent with the twisting direction of the yarn to ensure that the yarn is wound on the fixed drum as a twisting process. Unwinding is the untwisting process. For a unit length of weft, the amount of twisting and untwisting is equal.
Like the moving drum weft feeder, the fixed drum weft feeder is also equipped with a single-point photoelectric reflective detection device to realize the maximum weft storage detection. The disadvantage of this device is that the mirror surface is prone to malfunction when it is contaminated.
Some fixed-drum weft feeders adopt double-point photoelectric reflection type or double-point mechanical detection device to realize the detection of maximum and minimum weft storage. The dual-point detection device controlled by the microprocessor can achieve the weft storage speed to automatically match the weft yarn demand, so that the winding process of the yarn storage is almost continuous.
The yarn arrangement of fixed drum feeder is also divided into positive and negative ways, and there are many types of mechanisms to realize the movement of yarn. There is a negative yarn arrangement method. 12 taper guide fingers are uniformly protruding on the surface of the cylindrical yarn storage drum. The drum surface slides forward to form a regular arrangement of yarn loops. According to the elasticity of the yarn, the number of characteristics, the friction resistance between the yarn and the drum surface, etc., with the help of the taper adjustment knob, the taper angle formed by the taper guide finger can be changed to adapt to the yarn arrangement requirements of different yarns.
The fixed drum type weft feeder also adopts an active yarn arrangement method. In the active yarn arrangement mode, the yarn loop on the yarn storage drum relies on a special yarn arrangement mechanism to complete the forward movement, and a satisfactory yarn arrangement can be obtained without manual adjustment. Effect. However, the complexity of the mechanism has increased, and noise and vibration will increase during work.
