Abstract:
A paper bobbin for winding yarn has an outer periphery provided with two annular protruding portions each adjacent to one of two ends of the paper bobbin respectively; since each protruding portion is protruded a height from the outer periphery of the paper bobbin, the two annular protruding portions may help the paper bobbin not only to lower the frequency of fiber breakage at initial stage of a yarn winding operation, but also to contribute to get a high quality of yarn and an increase in yield.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a paper bobbin for yarn, and more particularly to a cylindrical paper bobbin having two annular protruding portions to protect a yarn being wound from fibers damaged, fluffs occurred or fiber breakage at initial stage of a yarn winding operation. 
     2. Description of Related Art 
     Referring to  FIG. 1 , a conventional paper bobbin  10  for winding yarns has a hollow cylindrical body  11 , of which outer periphery (particularly in those areas respectively adjacent to the two ends of the hollow cylindrical body  11 ) has a smooth surface without any protruding structure. 
     To wind yarns around the paper bobbin  10 , the paper bobbin  10  is mounted around a stationary shaft  30 , and a frictional surface  41  of a rotary shaft  40  is brought into close contact with the outer periphery of the hollow cylindrical body  11  of the paper bobbin  10 , as indicated by the circled area of “A” in  FIG. 1 . 
     Then, the rotary shaft  40  is rotated as a driving shaft such that the paper bobbin  10  is rotated along with the rotary shaft  40  by friction resulting from the rotating frictional surface  41 . Once the tangential velocity of the outer periphery of the hollow cylindrical body  11  of the paper bobbin  10  reaches that of the frictional surface  41  of the rotary shaft  40 , yarns are introduced and wound around the paper bobbin  10 . 
     The paper bobbin  10  is a passive component to be rotated by the rotary shaft  40 . When the frictional surface  41  of the rotary shaft  40  has a constant tangential velocity, the angular velocity of the paper bobbin  10  if rotated is in inverse proportion to the overall outer diameter of the paper bobbin  10  wound with yarns. As more and more layers of yarn are winding around the paper bobbin  10 , so the angular velocity of the paper bobbin  10  is also slowed down as more significant. 
     At initial stage of a yarn winding operation, the overall outer diameter of the paper bobbin  10  wound with yarns is still relatively small; in other words, the overall outer diameter is imperceptible on the increase with the amount of yarn wound around the paper bobbin  10 . During this stage of the yarn winding operation, the rotary shaft  40  therefore drives the paper bobbin  10  to be rotated at a very high angular velocity to carry out the yarn winding operation. 
     When wound at high speed, however, the yarn is pulled by a strong winding force as well as subject to a high tension. Resulted in that the yarn has fibers damaged or fluffs occurred, and more seriously, fiber breakage is often happened, repeatedly. Should any of these problems be occurred, the spinning process must be stopped to reconnect the yarn. 
     In addition, as the hollow cylindrical body  11  of the conventional paper bobbin  10  has a smooth outer periphery without any protruding structure, as shown in  FIG. 1 , a complete contact between the hollow cylindrical body  11  of the paper bobbin  10  and the frictional surface  41  of the rotary shaft  40  takes place at the initial stage of the yarn winding operation. And, because of the large area of contact, friction-based acceleration of the paper bobbin  10  generates noise as loud as 95 dB, which causes noise pollution in a spinning factory. 
     SUMMARY OF THE INVENTION 
     In light of the above, it is a primary object of the present invention to disclose a paper bobbin for winding yarn, comprising a hollow cylindrical body of which outer periphery has two annular protruding portions spaced apart at a distance; wherein each annular protruding portion is protruded from the outer periphery of the hollow cylindrical body to a height (H) ranging from 0.5 to 2.0 mm, preferably from 0.5 to 1.5 mm, and more preferably from 0.8 to 1.2 mm. 
     It is another objective of the present invention to disclose a paper bobbin for winding yarn, comprising a hollow cylindrical body of which outer periphery has two annular protruding portions spaced apart at a distance and two annular grooves spaced apart at a distance; wherein each annular protruding portion is protruded from the outer periphery of the hollow cylindrical body to a height (H) ranging from 0.5 to 2.0 mm, and each annular groove of the paper bobbin has a groove width (W) ranging from 4 to 15 mm, preferably from 4 to 12 mm, and more preferably from 4 to 8 mm. 
     The paper bobbin of the present invention produces the following advantageous effects at initial stage of a yarn winding operation, where the paper bobbin is driven by a high-speed rotary shaft to reel in yarn: 
     1. The tension of the yarn being wound is effectively reduced; 
     2. The yarn is protected from fiber breakage by high tension; or more particularly from fibers damaged or fluffs occurred; 
     3. The fibers of the yarn are less likely to break, meaning the quality and yield of the yarn can be ensured; and 
     4. The noise generated in the initial stage of the yarn winding operation is reduced, e.g., from about 95 dB to about 80 dB; thus, noise pollution in the spinning factory is ameliorated. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a partially sectional view to show how yarns are wound around a conventional paper bobbin; 
         FIG. 2  is a partially sectional view of a cylindrical paper bobbin according to the present invention; and 
         FIG. 3  is a partially sectional view to show how yarns are wound around the paper bobbin in  FIG. 2 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     As shown in  FIG. 2  and  FIG. 3 , a paper bobbin  20  according to the present invention is disclosed to use in winding yarns, which includes a seamless hollow cylindrical body  21  formed by winding multiple layers of synthetic paper together. And particularly, a structural improvement on the paper bobbin  20  of the present invention is that an outer periphery of the hollow cylindrical body  21  is provided with two identical annular protruding portions  22  which are each other spaced apart at a distance. 
     One of the two annular protruding portions  22  is located the place adjacent to one end of the hollow cylindrical body  21 , and the other is adjacent to the other end of the hollow cylindrical body  21 , respectively. 
     Each annular protruding portion  22  is protruded from the outer periphery of the hollow cylindrical body  21  to a height (H) ranging from 0.5 to 2 mm, preferably from 0.5 to 1.5 mm, more preferably from 0.8 to 1.2 mm. 
     Accordingly, no matter the paper bobbin  20  of the present invention has the same outer diameter as that of the conventional paper bobbin  10  shown in  FIG. 1 , the outer diameter of the annular protruding portions  22  is still greater than the outer diameter of the hollow cylindrical body  11  of the conventional paper bobbin  10  by 0.5-2.0 mm. Therefore, at initial stage of a yarn winding operation, referring to the circled area of “B” in  FIG. 3 , only the top of each annular protruding portion  22  of the paper bobbin  20  of the present invention is in contact with the frictional surface  41  of the rotary shaft  40 ; in consequence, a frictional area generated between the paper bobbin  20  and the rotary shaft  40  is substantially smaller than that between the conventional paper bobbin  10  and the rotary shaft  40 . This helps reduce noise pollution in a spinning factory by lowering the noise generated at the initial stage of the yarn winding operation from about 95 dB (when the conventional paper bobbin  10  is used) to about 80 dB. 
     More specifically, at the initial stage of a yarn winding operation, the paper bobbin  20  of the present invention contacts the rotary shaft  40  via the annular protruding portions  22 , whose outer diameter is greater than that of the hollow cylindrical body  11  of the conventional paper bobbin  10  and which keep rotating at the same tangential velocity as the rotary shaft  40 . 
     By contrast, the conventional paper bobbin  10  contacts the rotary shaft  40  via the hollow cylindrical body  11 , whose outer diameter is smaller than that of the annular protruding portions  22  of the paper bobbin  20  of the present invention. Hence, when driven by the rotary shaft  40  at the same tangential velocity, the paper bobbin  20  of the present invention has a much lower angular velocity at the initial stage of a yarn winding operation than the conventional paper bobbin  10  has, and this helps reduce the winding force (or tension) with which the yarn is reeled in. Thus, the annular protruding portions  22  keep the yarn being wound from fibers damaged, fluffs occurred or fiber breakage at the initial stage of a yarn winding operation. 
     Referring to  FIG. 1 , yarn is wound around the conventional paper bobbin  10  by moving spirally back and forth between the two ends of the hollow cylindrical body  11  of the paper bobbin  10 ; as a result, the two ends of the hollow cylindrical body  11  of the conventional paper bobbin  10  are the mostly frequently wound portions. This phenomenon tends to deform the conventional paper bobbin  10  and cause high-tension damage to the yarn at the two ends of the hollow cylindrical body  11 . 
     To solve these problems, referring to  FIG. 2  and  FIG. 3 , another structural improvement on the aforesaid paper bobbin  20  of the present invention is that, in addition to having the two annular protruding portions  22 , the paper bobbin  20  further provides two identical annular grooves  23  each depressed on the outer periphery of the hollow cylindrical body  21  of the paper bobbin  20 . More specifically, one of the two annular grooves  23  is located the place adjacent to one of the two annular protruding portions  22 , and the other is adjacent to the other annular protruding portion  22  of the hollow cylindrical body  21 , respectively. 
     Each annular groove  23  is a recess, which depth recessed into the outer periphery of the hollow cylindrical body  21  preferably ranges from 0.5 to 5.5 mm. In addition, each annular groove  23  has a groove width (W) ranging from 4 to 15 mm, preferably from 4 to 12 mm, more preferably from 4 to 8 mm. 
     When driven by the rotary shaft  40 , the paper bobbin  20  of the present invention has different tangential velocities at different positions. At the annular grooves  23 , whose inner diameter is smaller than the outer diameter of the hollow cylindrical body  21 , a relatively low tangential velocity is obtained at the initial stage of a yarn winding operation. 
     More specifically, each annular groove  23  formed on the paper bobbin  20  is functionally served as a buffer area when the paper bobbin  20  in winding yarns, so that each annular groove  23  allows yarn to be wound in the buffer area at a relatively low tangential velocity during the initial stage of a yarn winding operation. Thus, the annular grooves  23  keep the paper bobbin  20  from deformation and the yarn being wound from damage attributable to high tension. 
     Referring to  FIG. 3 , when the paper bobbin  20  of the present invention is winding with yarn, the paper bobbin  20  is mounted around the stationary shaft  30 , and the frictional surface  41  of the rotary shaft  40  is brought into close contact with the top of each protruding portion  22  of the paper bobbin  20 . Then, the rotary shaft  40 , which serves as a driving shaft, drives the paper bobbin  20  into simultaneous rotation via friction generated by rotation of the frictional surface  41 . Once the tangential velocity of the outer periphery of the hollow cylindrical body  21  of the paper bobbin  20  becomes equal to that of the frictional surface  41  of the rotary shaft  40 , yarn is introduced into one of the annular grooves  23  of the paper bobbin  20  and subsequently wound around the paper bobbin  20 . 
     According to the above, the paper bobbin  20  of the present invention can lower the frequency of fiber breakage at the initial stage of a yarn winding operation and therefore leads to an increase in quality and yield of yarn.