PATENT ABSTRACT
An exemplary embodiment provides a winder for an electrode assembly of a rechargeable battery capable of improving productivity by shortening a winding cycle. A winder for an electrode assembly of a rechargeable battery according to an exemplary embodiment includes: a nip roll catching and feeding a positive plate and a negative plate, and a separator; a rotor disposed below the nip roll to rotate; and a plurality of winding cores arranged in the rotor at a regular interval in a rotation direction of the rotor to rotate and move forward or backward from the rotor, wherein the center of the nip roll, the center of any one winding core among the plurality of winding cores, and one surface of an electrode assembly of another winding core which is winding-completed form a straight line.

PATENT DESCRIPTION
RELATED APPLICATIONS 
     This application claims priority to and the benefit of Korean Patent Application No. 10-2010-0052013 filed in the Korean Intellectual Property Office on Jun. 1, 2010, the entire contents of which are incorporated herein by reference. 
     BACKGROUND 
     1. Field 
     The described technology relates generally to a winder for an electrode assembly of a rechargeable battery winding a positive plate and a negative plate, and a separator of the rechargeable battery and an electrode assembly manufacturing method using the same. 
     2. Description of the Related Art 
     A rechargeable battery includes a positive plate and a negative plate, both formed by applying an active material onto a current collector, and a separator interposed therebetween. The electrode assembly of the rechargeable battery is formed by stacking the positive plate, the separator, and the negative plate and then winding the assembly into a jelly roll. A winder is used to manufacture the electrode assembly in the jelly roll form. The winder includes a pair of nip rolls, a rotor that rotates below the nip roll, and three winding cores that rotate while being disposed at first, second, and third positions of an equilateral triangle, respectively and move backward or forward from the rotor. The first position is vertically below the nip roll and the second and third positions form a symmetric structure at both right and left sides of an extension line linking the nip roll and the first position with each other while maintaining an interval of 120° in a rotation direction of the rotor. 
     While manufacturing the electrode assembly of the rechargeable battery using the winder, the rotor moves three winding cores to the first, second, and third positions in sequence. In this case, a first winding core winds the positive plate and the negative plate and the separator at the first position and then moves from the first position to the second position to complete a finishing process of the wound electrode assembly. While in the second position, a cutting process of the separator is performed and the electrode assembly is then removed by moving backward from the second position to the third position. The first winding core prepares for a new winding by moving forward from the third position to the first position. 
     After winding, the winding core at the first position moves to the second position and another winding core at the third position moves backward to the first position. Therefore, the separator connecting the nip roll and the winding core at the second position deviates from the winding core at the first position by maintaining an inclined state in a vertical direction. Accordingly, a control roll is provided at the side between the first and second positions to push the separator connecting the nip roll and the winding core at the second position towards each other so as to adjust the separator to be vertical between the nip roll and the winding core of the first position. While the separator is in the vertical state, the winding core at the first position moves forward from the rotor to start new winding by using the separator, and the positive plate and the negative plate. 
     In the winder for the electrode assembly of the rechargeable battery, after winding is completed at the first position of the rotor, in order to start new winding, the separator should be adjusted to be in the vertical state by using the control roll, This results in the structure of the winder being complicated and the time when an empty winding core is moving is lengthened. Therefore, a winding cycle is lengthened which results in decreased productivity. 
     The above information disclosed in this Background section is only for enhancement of understanding of the background of the described technology and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art. 
     SUMMARY 
     The described technology has been made in an effort to provide a winder for an electrode assembly of a rechargeable battery which improves productivity by shortening a winding cycle. 
     Further, the described technology has been made in effort to provide a winder for an electrode assembly of a rechargeable battery which shortens a waiting time of an empty winding core by the time of starting a new winding after the previous winding is completed. 
     Further, the described technology has been made in an effort to provide an electrode assembly manufacturing method using a winder for an electrode assembly of a rechargeable battery. 
     An exemplary embodiment provides a winder for an electrode assembly of a rechargeable battery that includes: a nip roll catching and feeding a positive plate and a negative plate, and a separator; a rotor disposed below the nip roll to rotate; and a plurality of winding cores arranged in the rotor at a regular interval in a rotation direction of the rotor to rotate and move forward or backward from the rotor, wherein the center of the nip roll, the center of any one winding core among the plurality of winding cores, and one surface of an electrode assembly of another winding core which is winding-completed form a substantially straight line. 
     The center of the nip roll, the center of any one winding core among the plurality of winding cores, and one surface of an electrode assembly of another winding core which is winding-completed may form a substantially vertical line. 
     A link line linking the center, of the nip roll, the center of the one winding core, and one surface of the electrode assembly of another winding core may be spaced from the rotation center of the rotor by a predetermined distance. 
     The winding core may include a first winding core, a second winding core, and a third winding core that are arranged at a regular interval in the rotation direction of the rotor, and the first winding core, the second winding core, and the third winding core may be sequentially positioned at a first position vertically below the nip roll, and a second position and a third position that are arranged at a regular interval in the rotation direction of the rotor at the first position. 
     The center of the nip roll, the center of any one winding core positioned at the first position among the first winding core, the second winding core, and the third winding core, and one surface of an electrode assembly of a winding core positioned at the second position may form the vertical line. 
     Another exemplary embodiment provides a method for manufacturing an electrode assembly of a rechargeable battery that includes: a first step of mounting a positive plate and a negative plate, and a separator fed from a nip roll on a winding core at a first position below the nip roll among three winding cores arranged at a regular interval in a rotation direction of a rotor; a second step of winding in the winding core at the first position; a third step of moving the winding-completed winding core from the first position to a second position; a fourth step of finishing and cutting an electrode assembly of the moved winding core at the second position; a fifth step of moving the winding core loading the finished/cut electrode assembly from the second position to a third position; a sixth step of removing an electrode assembly of the moved winding core at the third position from the winding core; and a seventh step of moving the winding core removed with the electrode assembly to the first position, wherein at the first step, the center of the nip roll, the center of the winding core at the first position, and one surface of an electrode assembly wound at the second position are arranged in a substantially straight line. 
     At the first step, the center of the nip roll, the center of the winding core at the first position, and one surface of an electrode assembly wound at the second position may be arranged in a substantially vertical line. 
     According to the exemplary embodiments, since the center of a nip roll, the center of a first winding core (first position), and one surface of an electrode assembly mounted on a winding core (second position) that is winding-completed and moved are formed in a straight line, it is possible to directly mount a positive plate, a negative plate, and a separator by moving forward one winding core (first position) supplied with being empty. That is, it is possible to shorten a waiting time of the empty winding core by the time of starting new winding after winding is completed. Accordingly, it is possible to shorten a winding cycle and improve productivity in manufacturing the electrode assembly. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of a winder for an electrode assembly of a rechargeable battery according to an exemplary embodiment; 
         FIG. 2  is a perspective view of first, second, and third winding cores and a rotor in a winder of  FIG. 1 ; 
         FIG. 3  is a flowchart of a method of manufacturing an electrode assembly of a rechargeable battery according to an exemplary embodiment; 
         FIG. 4  is a state diagram of mounting in a first winding core, finishing/cutting in a second winding core, and removal in a third winding core; 
         FIG. 5  is a winding operation state diagram of a first winding core following  FIG. 4 ; 
         FIG. 6  is a rotating operation state diagram of a rotor after the winding-completion of a first winding core following  FIG. 5 ; 
         FIG. 7  is a state diagram of mounting in a third winding core, finishing/cutting in a first winding core, and removal in a second winding core following  FIG. 6 ; 
         FIG. 8  is a winding operation state diagram of a third winding core following  FIG. 7 ; 
         FIG. 9  is a rotating operation state diagram of a rotor after the winding-completion of a second winding core following  FIG. 8 ; 
         FIG. 10  is a state diagram of mounting in a second winding core, finishing/cutting in a third winding core, and removal in a first winding core following  FIG. 9 ; 
         FIG. 11  is a winding operation state diagram of a second winding core following  FIG. 10 ; and 
         FIG. 12  is a rotating operation state diagram of a rotor after the winding-completion of a second winding core following  FIG. 11 . 
     
    
    
     DETAILED DESCRIPTION 
     The present invention will be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. As those skilled in the art would realize, the described exemplary embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. The drawings and description are to be regarded as illustrative in nature and not restrictive. Like reference numerals designate like elements throughout the specification. 
       FIG. 1  is a schematic diagram of a winder for an electrode assembly of a rechargeable battery according to an exemplary embodiment. Referring to  FIG. 1 , the winder according to the exemplary embodiment includes a positive plate feeding roll  11  and a first travel roll  12 , a negative plate feeding roll  21  and a second travel roll  22 , first and second separator feeding rolls  33  and  34  and third and fourth travel rolls  35  and  36 , one pair of nip rolls  41 , and a rotor  43  feeding and travelling a positive plate  10  and a negative plate  20  and first and second separators  31  and  32  in a strip shape, respectively. The positive plate  10  and the negative plate  20  and the first and second separators  31  and  32  are fed to the rotor  43  via the nip roll  41  while being wound and caught on the first, second, third, and fourth travel rolls  12 ,  22 ,  35 , and  36 , respectively. 
     The nip roll  41  catches the positive plate  10  and the negative plate  20  and the first and second separators  31  and  32  fed through the first, second third, and fourth rolls  12 ,  22 ,  35 , and  36  that are stacked and feeds them to the rotor  43 . For example, the nip roll  41  may be formed by a rotating driving roll and a support roll supporting the driving roll and rotating by the driving roll. The rotor  43  is rotatably mounted on a bracket  42  provided below the nip roll  41  and is mounted with a plurality of winding cores that independently rotates while being disposed in a equilateral triangle at one side and move backward or forward from the rotor  43 . For example, the rotor  43  is mounted with three winding cores, i.e., first, second, and third winding cores  51 ,  52 , and  53 . 
     Each of the first, second, and third winding cores  51 ,  52 , and  53  is disposed at any one of first, second, and third positions P 1 , P 2 , and P 3  in the rotor  43 . Even though the positions of the first, second, and third winding cores  51 ,  52 , and  53  are changed by rotating the rotor  43 , the first, second, and third positions P 1 , P 2 , and P 3  maintain the same state as shown in  FIG. 1 . That is, the first, second, and third positions P 1 , P 2 , and P 3  form the equilateral triangular structure at one side of the rotor  43  and maintains a set position with respect to a center C 1  of the nip roll  41 . For example, the first position P 1  is vertically below the nip roll  41  and the second and third positions P 2  and P 3  is set while maintaining an interval of 120° in a rotation direction of the rotor  43  at the first position P 1 . 
     For convenience, when described in more detail with reference to the state of  FIG. 1 , the center C 1  of the nip roll  41 , the center C 2  of the first winding core  51  positioned at the first position P 1 , and one surface C 3  of an electrode assembly EA of the second winding core  52  that is positioned at the second position P 2  and winding-completed form a substantially straight line. Since the first position P 1  is positioned vertically below the center C 1  of the nip roll  41 , the center C 1  of the nip roll  41 , the center C 2  of the first winding core  51 , and one surface C 3  of the electrode assembly EA of the second winding core  52  forms the substantially straight line. Further, a line linking the center C 1  of the nip roll  41 , the center C 2  of the first winding core  51 , and one surface C 3  of the electrode assembly EA of the winding-completed second winding core  52  is spaced from a rotation center C 4  of the rotor  43  by a set distance D. Before cutting the first and second separators  31  and  32  and by moving to the second position P 2  after winding-completed at the first position P 1 , the line linking the centers C 1  and C 2  and one surface C 3  coincides with the first and second separators  31  and  32  that reaches one surface C 3  of the electrode assembly EA of the second winding core  52 . 
       FIG. 2  is a perspective view of first, second, and third winding cores and a rotor in a winder of  FIG. 1 . Referring to  FIG. 2 , the first, second, and third winding cores  51 ,  52 , and  53  has clamps  511 ,  521 , and  531  opened to be mounted with the positive plate  10  and the negative plate  20  and the first and second separators  31  and  32  for winding, respectively. The rotor  43  further includes an arm member  431  formed at the center in parallel with the first, second, and third winding cores  51 ,  52 , and  53  and a support member  432  at the provide at the end of the arm member  431  and supporting each of clamps  511 ,  521 , and  531  of the first, second, and third winding cores  51 ,  52 , and  53 . Accordingly, the arm member  431  and the support member  432  can prevent the first, second, and third winding cores  51 ,  52 , and  53  winding the electrode assembly from being dropped while being separated from the rotor  43 . 
     Further, the winder according to the exemplary embodiment further includes first and second yokes  611  and  621  that selects any one of the first, second, and third winding cores  51 ,  52 , and  53 . The yokes  611  and  612  select by rotating the rotor  43  and selecting a winding core so as to move the selected winding core backwards toward the rear of the rotor  43  or move the selected winding core forward toward the front of the rotor  43 . First and second cylinders  612  and  622  connected with the first and second yokes  611  and  621 , respectively achieve these movements. Therefore, the first, second, and third winding cores  51 ,  52 , and  53  are provided with grooves  512 ,  522 , and  532  that selectively couple with the first and second yokes  611  and  621  in the rear of the rotor  43 , respectively. 
     Referring to  FIG. 2 , by rotating the rotor  43 , the first, second, and third winding cores  51 ,  52 , and  53  may be respectively positioned at the first, second, and third positions P 1 , P 2 , and P 3 . In this case, the groove  532  of the third winding core  53  is positioned at the third position P 3  and is coupled to the second yoke  621  to move backward or forward the third winding core  53  by a second cylinder  622 . Further, the groove  512  of the first winding core  51  is positioned at the first position P 1  and is coupled to the first yoke  611  to move forward or backward the first winding core  51  by a first cylinder  612 . 
     At the third position P 3 , the second cylinder  622  moves forward while being separated from the second yoke  621  and moves backward while the second yoke  621  is coupled to the groove  532  of the third winding core  53  which moves forward, such that the completed electrode assembly may be removed from the third winding core  53 . At the first position, the first cylinder  612  moves backward while being separated from the first yoke  611  and moves forward while the first yoke  611  is coupled to the groove  512  of the first winding core  51  which moves backward, such that the positive plate  10  and the negative plate  20 , and the first and second separators  31  and  32  may be mounted on the first winding core  51 . 
     In the exemplary embodiment, the known technology may be applied to a configuration of rotating the rotor  43  of the winder, rotating each of the first, second, and third winding cores  51 ,  52 , and  53 , and opening and closing the clamps  511 ,  521 , and  531 . Therefore, a detailed description thereof will be omitted. 
       FIG. 3  is a flowchart of a method of manufacturing an electrode assembly of a rechargeable battery according to an exemplary embodiment. Referring to  FIG. 3 , the manufacturing method according to the exemplary embodiment can manufacture a positive plate  10  and a negative plate  20 , and first and second separators  31  and  32  as the electrode assembly EA of the rechargeable battery while passing through steps shown in  FIGS. 3 and 4  to  12  by using a winder disclosed in  FIGS. 1 and 2 . The manufacturing method of  FIG. 3  includes a first step ST 1  to a seventh step ST 7  as shown in  FIGS. 4 to 12  and the steps are performed in the same manner for first, second, and third winding cores  51 ,  52 , and  53 . Meanwhile, in  FIGS. 4 to 12 , a dot mark (•) marked with a dot at the centers of first, second, and third winding cores  51 ,  52 , and  53  represents a move-forward state of the winding core and an x mark (           ) marked with x at the centers represents a move-backward state of the winding core.
     In the manufacturing method of the exemplary embodiment, at the first step ST 1 , the positive plate  10  and the negative plate  20 , and the first and second separators  31  and  32  fed from a nip roll  41  are mounted on a winding core at a first position P 1 . In this case, the winder arranges the center C 1  of the nip roll  41 , the center C 2  of the winding core at the first position P 1 , and one surface C 3  of an electrode assembly EA wound at a second position P 2  in a straight line and facilitates the mounting of the positive plate  10  and the negative plate  20 , and the first and second separators  31  and  32  on the winding core at the first position P 1 . At the step ST 2 , the plate  10  and the negative plate  20 , and the first and second separators  31  and  32  are wound on the winding core at the first position P 1 . At the third step ST 3 , the winding-completed winding core moves from the first position P 1  to the second position P 2 . At the fourth step ST 4 , an electrode assembly EA of the moved winding core at the second position P 2  is finished and cut. At the fifth step ST 5 , the winding core loading the finished/cut electrode assembly EA moves from the second position P 2  to a third position P 3 . At the sixth step ST 6 , an electrode assembly EA comprising the moved winding core at the third position P 3  is removed from the winding core. At the sixth ST 6 , the winding core removed with the electrode assembly EA moves to the first position P 1  and prepares a new winding cycle. Hereinafter, the steps will be described in more detail with reference to  FIGS. 4 to 12 . 
       FIG. 4  is a state diagram of mounting in a first winding core, finishing/cutting in a second winding core, and removal in a third winding core. Hereinafter, the first winding core  51  will be described with reference to  FIGS. 3 and 4 . At the first step ST 1 , the positive plate  10  and the negative plate  20 , and the first and second separators  31  and  32  fed from the nip roll  41  are mounted on the first winding core  51  by moving forward the winding core (for convenience, referred to as “first winding core  51 ”) at the first position P 1  below the nip roll  41 . In this case, by rotating a rotor  43  (for convenience, “clockwise direction” will be described as an example), the center C 1  of the nip roll  41 , the center C 2  of the winding core  51  at the first position P 1 , and one surface C 3  of the electrode assembly EA wound at a second position P 2  are arranged in a substantially straight line, in more detail, a substantially vertical line. That is, since the first and second separators  31  and  32  are connected to the second winding core  52  through the nip roll  41 , the first and second separators  31  and  32  are positioned at the center C 2  of the first winding core  51 . Therefore, the first winding core  51  moves forward from a previous position to be easily mounted with the positive plate  10  and the negative plate  20 , and the first and second separators  31  and  32  through a clamp  511 . After winding is completed, in order to start new winding at the first position P 1 , when the positive plate  10  and the negative plate  20 , and the first and second separators  31  and  32  are mounted, the empty winding core  51  is retained in the backwards position until the winding core is in the first position. As a result, the winding cycle is shortened and in addition, the productivity of manufacturing the electrode assembly EA is improved. In this case, the previously wound electrode assembly EA is taped and finished in the second winding core  52  at the second position P 2 , the first and second separators  31  and  32  are cut, and the previously wound electrode assembly EA is removed from the third winding core  53  by moving backward the third winding core  53  at the third position P 3 . 
       FIG. 5  is a winding operation state diagram of a first winding core following  FIG. 4 . Referring to  FIGS. 3 and 5 , the first winding core  51  will be described below. At the second step ST 2 , by the rotation of the first winding core  51  at the first position P 1 , the positive plate  10  and the negative plate  20 , and the first and second separators  31  and  32  mounted on the first winding core  51  are wound. In this case, the second winding core  52  at the second position P 2  maintains the loading of the finished and cut electrode assembly EA and the third winding core  53  at the third position P 3  maintains the backward position of the corresponding electrode assembly EA. 
       FIG. 6  is a rotating operation state diagram of a rotor after the winding-completion of a first winding core following  FIG. 5 . Referring to  FIGS. 3 and 6 , the first winding core  51  will be described below. At the third step ST 3 , the first winding core  51  loading the electrode assembly EA, which has its winding completed by the rotation of the rotor  43 , moves from the first position P 1  to the second position P 2 . Further, the center C 1  of the nip roll  41 , the center C 2  of the third winding core  53  at the first position P 1 , and one surface C 3  of the electrode assembly EA wound at the second position P 2  are arranged in the straight line, in more detail, the vertical line. That is, since the first and second separators  31  and  32  are connected to the first winding core  51  through the nip roll  41 , the first and second separators  31  and  32  are positioned at the center C 2  of the third winding core  53 . In this case, the second winding core  52  at the third position P 3  maintains the loading of the finished and cut electrode assembly EA and the third winding core  53  at the first position P 1  maintains the backward position of the corresponding electrode assembly EA. 
       FIG. 7  is a state diagram of mounting in a third winding core, finishing/cutting in a first winding core, and removal in a second winding core following  FIG. 6 . Referring to  FIGS. 3 and 7 , the first winding core  51  will be described below. At the fourth step ST 4 , the electrode assembly EA wound on the moved first winding core  51  is finished and cut. In this case, the second winding core  52  at the third position P 3  moves backward to be removed with the finished and cut electrode assembly EA and the third winding core  53  at the first position P 1  moves forward to be mounted with the first and second separators  31  and  32 . At the third step, since the first and second separators  31  and  32  are positioned at the center C 2  of the third winding core  53 , at the fourth step ST 4 , the third winding core  53  moves forward from backward to be mounted with the positive plate  10  and the negative plate  20 , and the first and second separators  31  and  32  through the clamp  531 . 
       FIG. 8  is a winding operation state diagram of a third winding core following  FIG. 7 . Referring to  FIGS. 3 and 8 , the third winding core  53  will be described below. The third winding core  53  at the first position P 1  winds the positive plate  10  and the negative plate  20 , and the first and second separators  31  and  32  mounted on the third winding core  53  by its self rotation. In this case, the first winding core  51  at the second position P 2  maintains the loading of the finished and cut electrode assembly EA and the second winding core  52  at the third position P 3  maintains the backward position of the corresponding electrode assembly EA. 
       FIG. 9  is a rotating operation state diagram of a rotor after the winding-completion of a second winding core following  FIG. 8 . Referring to  FIGS. 3 and 9 , the third winding core  53  will be described below. The third winding core  53  loading the electrode assembly EA which is winding-completed by the rotation of the rotor  43  moves from the first position P 1  to the second position P 2 . Further, the center C 1  of the nip roll  41 , the center C 2  of the second winding core  52  at the first position P 1 , and one surface C 3  of the electrode assembly EA wound at the second position P 2  are arranged in the substantially straight line, in more detail, the substantially vertical line. That is, since the first and second separators  31  and  32  are connected to the third winding core  53  through the nip roll  41 , the first and second separators  31  and  32  are positioned at the center C 2  of the second winding core  52 . In this case, the first winding core  51  at the third position P 3  maintains the loading of the finished and cut electrode assembly EA and the second winding core  53  at the first position P 1  maintains the moving-backward of the corresponding electrode assembly EA. 
       FIG. 10  is a state diagram of mounting in a second winding core, finishing/cutting in a third winding core, and removal in a first winding core following  FIG. 9 . Referring to  FIGS. 3 and 10 , the first winding core  51  will be described below. At the fifth step ST 5 , the electrode assembly EA of the first winding core  51  is removed by moving backward the first winding core  51  while in the third positions P 3 . In this case, the second winding core  52  at the first position P 1  moves forward to be mounted with the first and second separators  31  and  32  and the third winding core  53  at the second position P 2  finishes the wound electrode assembly EA and cuts the first and second separators  31  and  32 . At the third step, since the first and second separators  31  and  32  are positioned at the center C 2  of the second winding core  52 , the second winding core  52  moves forward from the backward position to be mounted with the positive plate  10  and the negative plate  20 , and the first and second separators  31  and  32  through the clamp  521 . 
       FIG. 11  is a winding operation state diagram of a second winding core following  FIG. 10 . Referring to  FIGS. 3 and 11 , the second winding core  52  will be described below. The second winding core  52  at the first position P 1  winds the positive plate  10  and the negative plate  20 , and the first and second separators  31  and  32  mounted on the second winding core  52  by its self rotation. In this case, the third winding core  53  at the second position P 2  maintains the loading of the finished and cut electrode assembly EA and the first winding core  51  at the third position P 3  maintains the backward position of the corresponding electrode assembly. 
       FIG. 12  is a rotating operation state diagram of a rotor after the winding-completion of a second winding core following  FIG. 11 . Referring to  FIGS. 3 and 12 , the first winding core  51  will be described below. At the sixth step ST 6 , the first winding core  51  with the electrode assembly EA removed from the third position P 3  to the first position P 1  to prepare the new winding cycle. Further, the center C 1  of the nip roll  41 , the center C 2  of the first winding core  51  at the first position P 1 , and one surface C 3  of the electrode assembly EA wound at the second position P 2  are arranged in the substantially straight line, in more detail, the substantially vertical line. That is, since the first and second separators  31  and  32  are connected to the second winding core  52  through the nip roll  41 , the first and second separators  31  and  32  are positioned at the center C 2  of the first winding core  51 . In this case, the third winding core  53  at the third position P 3  maintains the loading of the finished and cut electrode assembly EA and the first winding core  51  at the first position P 1  maintains the backward position of the corresponding electrode assembly EA. 
     While this disclosure has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.