Abstract:
The present invention discloses a cord and a wire puller, which is used to pass through narrow pipes or the like. The cord includes a first guide wire section and a second guide wire section. The first guide wire section includes a plurality of first guide wires, and the first guide wire section has a first segment in which the first guide wires are intertwisted with each other. At least a part of the first guide wires extends from the first segment to a transitional segment. The second guide wire section includes a plurality of second guide wires, and the second guide wire section has a second segment in which the second guide wires are intertwisted with each other. At least a part of the second guide wires extends from the second segment to the transitional segment, in which the first and second guide wires are intertwisted with each other.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates generally to wire pullers and cords which can be used to pass through pipes or other narrow passages. 
         [0003]    2. Description of the Related Art 
         [0004]    Wire pullers can be used to draw a long cable or the like through pipes or other narrow passages in a building. In the case of passing through a long narrow passages, e.g. with a length more than 30 meters, the wire pullers need to be provided with sufficient compressive strength and tensile strength to bear the friction from the pipes and other resistances. In addition, the distal ends of the wire pullers also need to remain flexible. Therefore, it is required to provide different physical properties to different segments of the wire pullers. For instance, the segment close to the distal end can be provided with smaller outer diameter to remain flexible, while the segment remote from the distal end can be provided with larger outer diameter to have better structural strength. 
         [0005]    For this purpose, the Taiwanese invention patent no. TW 483208 discloses a wire puller and it shows the flexibility of the distal end of the wire puller can be enhanced by varying the pitch of the threads or by varying the elongation of the distal end thereof during the elongation process. Thereby, different segments of the wire puller can have different physical properties. 
         [0006]    Nevertheless, it requires higher processing skills to implement the above-mentioned process in extrusion molding treatment of the resin wire pullers. It is so because the processing parameters in a part of the segments of the wire puller are different from those in the other part thereof, and yet these segments need to be extruded continually. As a result, such extrusion molding treatment usually leads to lower yield and higher cost. 
       SUMMARY OF THE INVENTION 
       [0007]    It is a main objective of the present invention to provide a wire puller and a cord which have different physical properties at different segments and are easy processing. 
         [0008]    To achieve the above and other objectives of the present invention, a wire puller is provided. The wire puller has a first guide wire section, a wire holder and a second guide wire section. The first guide wire section includes a plurality of first guide wires, and the first guide wire section has a first segment in which the first guide wires are intertwisted with each other. At least a part of the first guide wires extends from the first segment to a transitional segment. The wire holder is disposed on an end of the first guide wire section opposite to the transitional segment. The second guide wire section includes a plurality of second guide wires, and the second wire section has a second segment in which the second guide wires are intertwisted with each other. At least a part of the second guide wires extends from the second segment to the transitional segment in which the first and second guide wires are intertwisted with each other. 
         [0009]    The wire puller may also include a second wire holder disposed on an end of the second guide wire section opposite to the transitional segment. 
         [0010]    To achieve the above and other objectives of the present invention, a cord is further provided. The cord includes a first guide wire section and a second guide wire section. The first guide wire section includes a plurality of first guide wires, and the first guide wire section has a first segment in which the first guide wires are intertwisted with each other. At least a part of the first guide wires extends from the first segment to a transitional segment. The second guide wire section includes a plurality of second guide wires. The second guide wire section has a second segment in which the second guide wires are intertwisted with each other. At least a part of the second guide wires extends from the second segment to the transitional segment in which the first and second guide wires are intertwisted with each other. 
         [0011]    In the aforesaid wire puller and the cord, there are “n” strips of the first guide wires in the first guide wire section, and there are also “n” strips of the second guide wires in the second guide wire section. There are “a” strips of the first guide wires among all the first guide wires extending from the first segment to the transitional segment, and there are “b” strips of the second guide wires among all the second guide wires extending from the second segment to the transitional segment, in which a, b and n are positive integers, and n is a sum of a and b. 
         [0012]    Each of the aforesaid wire puller and the cord can further include a positioning means for fastening the first and second guide wires in the transitional segment in a manner that the first and second wires cannot spirally rotate about each other. 
         [0013]    In the aforesaid wire puller and the cord, the positioning means can comprise a first positioning sleeve and a second positioning sleeve. The first positioning sleeve is engaged at an intersection between the first segment and the transitional segment. The second positioning sleeve is engaged at an intersection between the second segment and the transitional segment. 
         [0014]    Based on the above-mentioned design, the manufacturer can choose suitable first and second guide wire sections subject to the desired properties. In the circumstance that the first and second guide wire sections are made of plastic, the first and second guide wire sections can be extruded separately and then partially intertwisted with each other. Such process requires lower processing skills and can therefore lead to higher yield and lower cost. 
         [0015]    The following detailed description will further explain the full scope of applications for the present invention. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those with the proper technical knowledge from this detailed description. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    The present invention can be understood more fully by referring to the detailed description below, as well as the accompanying drawings. However, it must be understood that both the descriptions and drawings are given by way of illustration only, and thus do not limit the present invention. 
           [0017]      FIG. 1  is an explosive drawing in side view of a cord in accordance with the first embodiment of the present invention; 
           [0018]      FIG. 2  is a side view of the cord in accordance with the first embodiment of the present invention; 
           [0019]      FIG. 3  is an explosive drawing in side view of a cord in accordance with the second embodiment of the present invention; 
           [0020]      FIG. 4  is a side view of the cord in accordance with the second embodiment of the present invention; 
           [0021]      FIG. 5  is a side view of a wire puller in accordance with the preferred embodiment of the present invention; 
           [0022]      FIG. 6  is an enlarged side view showing part of the wire puller in accordance with the preferred embodiment of the present invention, in which the positioning sleeve is shown in profile; 
           [0023]      FIG. 7  is an enlarged side view showing part of the wire puller in accordance with the preferred embodiment of the present invention, in which the cord is bent; 
           [0024]      FIG. 8  is an explosive drawing in side view of a cord in accordance with the third embodiment of the present invention; 
           [0025]      FIG. 9  is a side view of the cord in accordance with the third embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0026]    Please refer to  FIGS. 1 and 2  for the cord in accordance with the first embodiment of the present invention. The cord has a first guide wire section  10  and a second guide wire section  20 . 
         [0027]    The first guide wire section  10  includes three strips of first guide wires  11  and has a first segment A, in which these three first guide wires  11  are intertwisted with each other. One of the first guide wires  11  extends from the first segment A to a transitional segment B, but the other two first guide wires  11  do not extend to the transitional segment B. 
         [0028]    The second guide wire section  20  includes three strips of second guide wires  21  and has a second segment C, in which these three second guide wires  21  are intertwisted with each other. Two of the second guide wires  21  extend from the second segment C to the transitional segment B, while the other second guide wire  21  do not extend thereto. 
         [0029]    Thus, both the first and second guide wire sections are composed of three strips of guide wires, respectively, and there are also three strips of guide wires extending to the transitional segment. Because the first and second guide wires are intertwisted with each other in the transitional segment, the friction between these wires and the axially overlapping structure make them remain better axial compressive strength and tensile strength in the transitional segment. 
         [0030]    The first and second guide wires can be made of resin, which can be but not limited to polyesters, polyolefins such as polypropylene and polyethylene, polyamides and copolymers thereof. Generally, the first and second guide wires have good compressive and tensile strengths and can be radially bent. Preferably, the guide wires can be resilient so as to return to their original shape after they are released from bending force. In possible embodiments, each of the guide wires can be composed of multiple intertwisting thin fibers. 
         [0031]    To meet different needs, the materials, lengths, pitches, thicknesses, guide wire amounts, flexibilities and other properties of the first and second guide wire sections need not to be entirely the same. For example, the outer diameter D 1  of the first guide wire section  10  is different from the outer diameter D 2  of the second guide wire section  20 . 
         [0032]    Please refer to  FIGS. 3 and 4  for a cord in accordance with the second embodiment of the present invention. The cord also has a first guide wire section  10  and a second guide wire section  20 . The second embodiment is different from the first embodiment in that the second guide wire section  20  includes only two second guide wires  21 , and only one of the second guide wires  21  extends to the transitional segment B. And thus the transitional segment B is composed of one first guide wire  11  and one second guide wire  21  intertwisting with the first guide wire  11 . As such, the properties of the transitional segment B can be varied by adjusting the amount of the guide wires extending thereto and are therefore different from the first embodiment. Likewise, the first and second guide wire sections  10 ,  20  are different in their outer diameters D 1 , D 2  and the amounts of the guide wires, and therefore the physical properties such as flexibilities and hardnesses thereof are also different. 
         [0033]    In the afore-mentioned embodiments, both the first and second guide wire sections have only a part of their guide wires extending to the transitional segment. In other possible embodiments, all the first guide wires can be extended to the transitional segment and intertwisted with the second guide wires. In other possible embodiments, all the second guide wires can be extended to the transitional segment and intertwisted with the first guide wires. 
         [0034]    Please refer to  FIG. 5  for a wire puller in accordance with the preferred embodiment of the present invention. The middle section of the wire puller is a cord similar to that of the afore-mentioned first embodiment. That is, the cord includes a first guide wire section  10  and a second guide wire section  20 . The cord further includes a positioning means for fastening the first and second guide wires  11 ,  21  in the transitional segment in a manner that the first and second guide wires  11 ,  21  cannot spirally rotate about each other. In the present embodiment, the positioning means includes a first positioning sleeve  31  and a second positioning sleeve  32 . The first positioning sleeve  31  is engaged at an intersection between the first segment A and the transitional segment B. The second positioning sleeve  32  is engaged at an intersection between the second segment C and the transitional segment B. As shown in  FIG. 6 , the inner periphery of the first positioning sleeve  31  is formed with friction patterns to increase the engagement force. One section of the first positioning sleeve  31  is engaged with the first guide wires  11  in the first segment A, and the other section of the first positioning sleeve  31  is engaged with the first and second guide wires  11 ,  21  in the transitional segment B. These two sections of the first positioning sleeve  31  have different inner diameters in order to accommodate first segment A and the transitional segment B having different outer diameters. The second positioning sleeve  32  has a structure similar to the first positioning sleeve  31 . 
         [0035]    In other possible embodiments, the positioning means can be provided with only one positioning sleeve, which can be placed at one of the ends of the transitional segment or at a position between the two ends of the transitional segment. The positioning means can also be a forced-tight device which may includes a tapered ring and a tapered nut engaged with the tapered ring so as to fasten the first and second guide wires in a forced-tight manner. Other possible positioning means includes but not limited to coating adhesives on the transitional segment, tape winding and tacking. Or, the first and second guide wires in the transitional segment can be formed with complementary patterns such as teeth and notches, such that when the first and second guide wires are intertwisted, the teeth also match and engage with the notches. 
         [0036]    In the present embodiment, two positioning sleeves are provided to engage two ends of the transitional segment respectively. These two positioning sleeves can both provide engaging force to fasten the first and second guide wires, and therefore the length of the individual positioning sleeve can be shortened. Such fact can lead to an advantage in the fact that the guide wires adjacent to the shortened positioning sleeve can remain better flexibility when the cord is bent as shown in  FIG. 7 . The longer the positioning sleeve is, the less flexible the guide wires adjacent to the positioning sleeve are. It is noticed that the more the positioning sleeves are disposed on the transitional segment, the shorter the individual positioning sleeve can be made, which can make the first and second guide wires not only tight but also flexible. 
         [0037]    To pull a wire, the wire puller is further provided with a first wire holder  40  and a second wire holder  50 . The first wire holder  40  is disposed on an end of the first segment A opposite to the transitional segment B. The second wire holder  50  is disposed on an end of the second segment C opposite to the transitional segment B. The first and second wire holders  40 ,  50  can have the same or similar shapes. In the present embodiment, the first wire holder  40  has a jacket  41  mount on the end of the first segment A, and an eye  42  formed on the jacket  41  to connect the wire. The second wire holder  50  has a jacket  51  mount on the end of the second segment C, another jacket  52 , a cord  53  disposed between the jackets  51 ,  52  such as a steel cable, and an eye  54  formed on the jacket  52 . Compared with the first wire holder  40 , the second wire holder  50  is more superior in its flexibility. In other possible embodiments, the wire puller can be provided with only one wire holder. 
         [0038]    It is noticed that the cord of the present invention can be applied not only to the above-mentioned wire pullers, but also to other fields including but not limiting to the circumstance of cleaning or detecting objects in narrow passages. Under such circumstances, the wire holder is not necessary and therefore can be omitted. In addition, the cord of the present invention can also be provided with more than two guide wire sections. In possible embodiments, a cord can have three guide wire sections, at least two of which are provided with the transitional segment as above mentioned. 
         [0039]    Please refer to  FIGS. 8 and 9  for a cord in accordance with the third embodiment of the present invention. The first guide wire section  10  further includes a first axial wire  12  extending along a central line thereof. The second guide wire section  20  further includes a second axial wire  22  extending along a central line thereof. The first guide wires  11  are not only intertwisted with each other in the first segment A, but also spirally wound about the first axial wire  12 . In other words, the first axial wire  12  is the geometric center of the first guide wires  11 . Likewise, the second guide wires  21  are not only intertwisted with each other in the second segment C, but also spirally wound about the second axial wire  22 . Preferably, at least one of the first and second axial wires  12 ,  22  extends into the transitional segment B. For instance, both the first and second axial wires  12 ,  22  extend into the transitional segment B in the present embodiment, and the first and second guide wires  11 ,  21  in the transitional segment B are further wound about the first and second axial wires  12 ,  22 . In other possible embodiments, the first and second axial wires do not extend into the transitional segment, and thus the first and second guide wires are only intertwisted with each other. The first and second axial wires can be made of resin including but not limiting to polyesters, polyolefins such as PP and PE, polyamides and copolymers thereof. Or, the first and second axial wires can also be made of other materials such as steel or fiber glass. 
         [0040]    Based on the above-mentioned design, the manufacturer can choose suitable first and second guide wire sections subject to the desired properties. In the circumstance that the first and second guide wire sections are made of plastic, the first and second guide wire sections can be extruded separately and then partially intertwisted with each other. Such process requires lower processing skills and can therefore lead to higher yield and lower cost. 
         [0041]    The invention described above is capable of many modifications, and may vary. Any such variations are not to be regarded as departures from the spirit of the scope of the invention, and all modifications which would be obvious to someone with the technical knowledge are intended to be included within the scope of the following claims.