Patent Publication Number: US-9425004-B2

Title: Reinforced pin which hinge couples a rotatable shaft to the transfer link in a circuit breaker

Description:
CROSS-REFERENCE TO A RELATED APPLICATION 
     Pursuant to 35 U.S.C. §119(a), this application claims the benefit of earlier filing date and right of priority to Korean Patent Application Nos. 10-2013-0124176, filed on Oct. 17, 2013, and 10-2013-0129523, filed on Oct. 29, 2013, the contents of which are all hereby incorporated by reference herein in its entirety. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a circuit breaker and a method of fabricating a pin for a switching mechanism thereof, and more particularly, to a circuit breaker having a pin capable of hinge-coupling and insulating a link of a switching mechanism for switching a moving contact and a method of fabricating a pin for the switching mechanism thereof. 
     2. Description of the Conventional Art 
     In general, circuit breaker is a type of electrical device for manually switching an electrical circuit using a handle, or sensing an abnormal current when a short current or fault current occurs to automatically break a circuit, thereby protecting a load device and circuit. 
     Hereinafter, a circuit breaker in the related art will be described below with reference to  FIG. 1 . 
     A circuit breaker in the related art may include a stationary contact  10 , a movable contact  20  rotatably provided to be brought into contact with or separated from the stationary contact  10 , and a switching mechanism  30  configured to revolve the movable contact  20  to switch a circuit within a case (not shown). 
     The switching mechanism  30  may include a pin for hinge-coupling a shaft  74  rotatably provided therein, a transfer link  90  configured to transfer a driving force from the shaft  74  to the movable contact  20 , and a pin  80  for hinge-coupling the shaft  74  to the transfer link  90 . 
     In this case, referring to  FIG. 1 , the circuit breaker is formed with a plurality of phases, and a pair of the stationary contact  10  and the movable contact  20  are provided for each phase. 
     Accordingly, the switching mechanism  30  should be formed with a structure capable of switching a plurality of the movable contacts  20 . 
     Consequently, the movable contact  20  and the transfer link  90  hinge-coupled to the movable contact  20  are provided for each phase. 
     Furthermore, a shaft arm  74   b  protruded in a radial direction from a shaft rotation axis  74   a  is formed on the shaft  74  for each phase. 
     The shaft arm  74   b  is hinge-coupled to the transfer link  90  for each phase. 
     Here, the pin  80  is formed of an insulating material to prevent dielectric breakdown from occurring from a particular phase to another phase. 
     According to the foregoing configuration, when a handle of the switching mechanism  30  is rotated in a counter clockwise direction on the drawing and closed, the movable contact  20  and the switching mechanism  30  are brought into contact with each other by the switching mechanism  30  to connect a circuit. 
     On the contrary, when an abnormal current occurs on a line, the trip mechanism (not shown) is operated to release the restriction of a latch  62  of the switching mechanism  30 . 
     When the restriction of the latch  62  is released, the movable contact  20  is rapidly separated from the stationary contact  10  by an elastic force of the tension spring  50  of the switching mechanism  30 . 
     On the other hand, when an abnormal current is removed, the movable contact  20  and the stationary contact  10  are brought into contact with each other again through the manipulation of the switching mechanism  30 . I 
     During the process, the pin  80  hinge-couples the shaft  74  to the transfer link  90  to transfer a driving force received from the shaft  74  to the movable contact  20  through the transfer link  90 . 
     Furthermore, the pin  80  insulates the shaft  74  from the transfer link  90  for phase-phase insulation. 
     However, according to a circuit breaker in the related art, a wear resistance of the pin  80  formed of an insulating material is lower than that of the shaft  74 . In other words, a hardness of the pin  80  is lower than that of the shaft  74 . Due to this, when switching operations are repeated, a contact portion of the pin  80  to the shaft  74  is worn and damaged. As a result, a contact pressure between the movable contact  20  and the stationary contact  10  may be reduced, thereby increasing a contact resistance thereof. 
     SUMMARY OF THE INVENTION 
     Accordingly, an object of the present disclosure is to provide a circuit breaker and a method of fabricating a pin for a switching mechanism thereof capable of hinge-coupling and insulating a link of the switching mechanism to secure an insulating performance and wear resistance thereof, thereby suppressing the abrasion and damage of the pin, and solving a contact pressure reduction and contact resistance increase problem between a movable contact and a stationary contact. 
     According to the present disclosure, in order to accomplish the foregoing object, there is provided a circuit breaker, including a stationary contact installed in a fixed manner; a movable contact configured to be brought into contact with or separated from the stationary contact; and a switching mechanism configured to switch the movable contact, wherein the switching mechanism includes a shaft rotatably installed therein; a transfer link configured to transfer a driving force from the shaft to the movable contact; and a pin configured to hinge-couple the shaft to the transfer link and insulate them from each other, and the pin is installed with a wear resistant member at a portion brought into contact with the shaft. 
     The pin may include an insulating member formed in a cylindrical shape, and the wear resistant member may be formed with a pipe, and attached to a portion brought into contact with the shaft of the insulating member. 
     The wear resistant member may be installed on the insulating member in a fixed manner not to be released therefrom. 
     The insulating member may be inserted into the wear resistant member, and at least one end portion of the wear resistant member may be deformed to burrow into the insulating member. 
     The wear resistant member may be formed of a material having a wear resistance greater than that of the insulating member. 
     The insulating member may be formed of a polyethylene material, and the wear resistant member may be formed of a stainless steel material. 
     On the other hand, according to the present disclosure, there is provided a method of fabricating a pin for a circuit breaker switching mechanism, the method including forming an insulating member in a cylindrical shape; forming a wear resistant member in a pipe shape capable of surrounding one side of the insulating member; disposing the wear resistant member at one side of the insulating member; and deforming both end portions of the wear resistant member to burrow into the insulating member so as to fix the wear resistant member to one side of the insulating member. 
     The cross-section of both end portions of the wear resistant member may be formed perpendicular to an inner circumferential surface thereof in the step of forming the wear resistant member. 
     The wear resistant member may be formed such that a cylindrically shaped material thereof is drilled in a length direction, and the drilled material is cut by a predetermined length, and a burr of the cut material is removed. 
     Both end portions of the wear resistant member may be pressed and deformed by a press in the step of fixing the wear resistant member to one side of the insulating member. 
     The press may include an inclined surface formed to be brought into contact with an edge between the cross section of both end portions and an outer circumferential surface of the wear resistant member. 
     The press may press both end edges of the wear resistant member to the inclined surface by a predetermined dimension in an axial direction of the wear resistant member. 
     The predetermined dimension may be a value for preventing a bending phenomenon from occurring on the outer circumferential surface of the wear resistant member. 
     The press may include a die installed in a fixed manner; and a punch installed to face the die so as to move toward the die. 
     The die may include a first press surface facing the punch; and a first groove formed perpendicular to the first press surface, with which an end of the wear resistant member is engaged, and into which an end of the insulating member protruded from an end of the wear resistant member is inserted, and 
     The punch may include a second press surface facing in parallel to the first press surface; and a second groove formed perpendicular to the second press surface, with which the other end of the wear resistant member is engaged, and into which the other end of the insulating member protruded from the other end of the wear resistant member is inserted. 
     The first groove may include a first insertion portion formed in an engraved cylindrical shape in a direction perpendicular to the first press surface; and a first chamfer portion inclined to the first press surface and an inner circumferential surface of the first insertion portion, respectively. 
     The second groove may include a second insertion portion formed in an engraved cylindrical shape in a direction perpendicular to the second press surface; and a second chamfer portion inclined to the second press surface and an inner circumferential surface of the second insertion portion, respectively. 
     In this case, the first chamfer portion and the second chamfer portion may be the inclined surfaces. 
     The pin may be formed such that an end of the wear resistant member is engaged with the first chamfer portion, and an end of the insulating member protruded from an end of the wear resistant member is inserted into the first insertion portion. 
     Furthermore, the pin may be formed such that the other end of the wear resistant member is engaged with the second chamfer portion, and the other end of the insulating member protruded from the other end of the wear resistant member is inserted into the second insertion portion. 
     At least either one of the die and the punch may include an excessive compression prevention protrusion protruded toward the other one. 
     The excessive compression prevention protrusion may be brought into contact with the other one when the die and the punch press both end portions of the wear resistant member not to allow the first and the second press surfaces to get closer more than a predetermined distance. 
     The excessive compression prevention protrusion may include a first excessive compression prevention protrusion protruded toward the second press surface on the first press surface; and a second excessive compression prevention protrusion protruded to face the first excessive compression prevention protrusion on the second press surface. 
     The first excessive compression prevention protrusion and the second excessive compression prevention protrusion may be brought into contact with each other when the die and the punch press both end portions of the wear resistant member. 
     The sum of a protrusion length of the first excessive compression prevention protrusion and a protrusion length of the second excessive compression prevention protrusion may be provided to be the same as the predetermined distance. 
     A pair of the first excessive compression prevention protrusions may be formed to be located at opposite sides to each other by interposing the first groove therebetween. 
     A pair of the second excessive compression prevention protrusions may be formed to be located at opposite sides to each other by interposing the second groove therebetween to correspond to the pair of the first excessive compression prevention protrusions. 
     The predetermined distance may be a value for preventing a bending phenomenon from occurring on the outer circumferential surface of the wear resistant member. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention. 
       In the drawings: 
         FIG. 1  is a perspective view illustrating the inside of a circuit breaker in the related art; 
         FIG. 2  is a cross-sectional view illustrating a circuit breaker according to the present disclosure; 
         FIG. 3  is a perspective view illustrating a switching mechanism in  FIG. 2 ; 
         FIG. 4  is a cross-sectional view illustrating the process of forming an insulating member in  FIG. 3 ; 
         FIG. 5  is a perspective view illustrating the process of forming a wear resistant member in  FIG. 3 ; 
         FIG. 6  is an assembly view illustrating an insulating member and a wear resistant member in  FIGS. 4 and 5 ; 
         FIG. 7  is a cross-sectional view subsequent to the assembly of  FIG. 6 ; 
         FIG. 8A ,  FIG. 8B  and  FIG. 8C  are cross-sectional views illustrating the process of pressing an insulating pin with a press; 
         FIG. 9  is a cross-sectional view illustrating the insulating pin of  FIG. 3  fabricated by the pressure process of  FIG. 8A ,  FIG. 8B  and  FIG. 8C ; 
         FIG. 10  is a cross-sectional view in  FIG. 9 ; 
         FIG. 11  is a perspective view illustrating a press in  FIG. 8A ,  FIG. 8B  and  FIG. 8C ; and 
         FIG. 12  is a cross-sectional view illustrating another embodiment of an insulating pin in  FIG. 3 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Hereinafter, a circuit breaker and a method of fabricating a pin for switching mechanism thereof (hereinafter, referred to as an “insulating pin”) will be described in detail based on an embodiment illustrated in the accompanying drawings. 
       FIG. 2  is a cross-sectional view illustrating a circuit breaker according to the present disclosure, and  FIG. 3  is a perspective view illustrating a switching mechanism in  FIG. 2 . 
     As illustrated in  FIGS. 2 and 3 , a circuit breaker according to the present disclosure may include a stationary contact  10  installed in a fixed manner within a case (C); a movable contact  20  configured to be brought into contact with or separated from the stationary contact  10 ; and a switching mechanism  130  configured to rotate the movable contact  20  so as to switch a circuit. 
     The stationary contact  10  and the movable contact  20  may be brought into contact with each other to form a conduction path so as to receive power from the side of a power source and transfer it to the side of a load, and separated from each other to break the circuit. 
     The stationary contact  10  may be installed in a fixed manner within the case (C), and connected to the side of a power source or load. 
     The movable contact  20  may be hinge-coupled to the case (C) at one side thereof, and hinge-coupled to a transfer link  90  which will be described later at the other side thereof, and connected to the side of a load or power source. Here, a portion hinge-coupled to the case (C) is a movable contact rotation shaft  22 . 
     The switching mechanism  30  may include a handle  40  provided for a user to perform a switching operation, a tension spring  50  for generating a driving force to allow the movable contact  20  to be brought into contact with or separated from the stationary contact  10 , and a link apparatus  160  for transferring a driving force to the movable contact  20 . 
     An end of the handle  40  may be hinge-coupled to an inner portion of the case (C), and the other end thereof may be protruded from the case (C). 
     Furthermore, a first spring fastening portion  42  may be provided at one side of the handle  40  separated from a handle rotation shaft (not shown). 
     In this case, when the circuit breaker is switched from a closing operation (ON) to an opening operation (OFF or TRIP), the first spring fastening portion  42  may move around an axis formed between a rocker rotation axis  64  and a second spring fastening portion  68   a  which will be described later from one side in a direction opposite to the one side. 
     The tension spring  50  may be supported by the first spring fastening portion  42  at one end thereof, and supported by the second spring fastening portion  68   a  which will be described later at the other end thereof. 
     The link apparatus  160  may include a latch  62  for performing a trip operation, a rocker  66  for performing the role of a driving member joint with respect to the entire link apparatus  160 , and a connecting link  70  for connecting the rocker  66  to a shaft  74  which will be described later, a shaft  74  for performing the role of a driving member joint with respect to the movable contact  20  while at the same time performing the role of a follower member joint with respect to the rocker  66 , and a transfer link  90  for connecting the shaft  74  to the movable contact  20 . 
     The latch  62  may be hinge-coupled to an inner portion of the case (C) at one side thereof, and installed to be engaged with a separate latch holder (H) at the other side thereof. 
     In this case, the latch  62  may be engaged with the latch holder (H) to perform the role of a fixed supporting position for operating the other constituent elements of the link apparatus  160  when the circuit breaker is in a closing operation (ON) or artificial opening operation (OFF). 
     Furthermore, the latch  62  may be released from the latch holder (H) to be rotated when the circuit breaker is in an opening operation (TRIP) due to an accident. Due to this, the latch  62  may perform the role of a link member connected to the other constituent elements of the link apparatus  160 . 
     The rocker  66  may be rotatably installed in the latch  62  at one side thereof, and hinge-coupled to the connecting link  70  at the other side thereof. 
     In this case, a second spring fastening portion  68   a  for supporting the other end of the tension spring  50  may be provided in a pin  68  for hinge-coupling the rocker  66  to the connecting link  70 . Due to this, a driving force due to the tension spring  50  is applied to the pin  68 , and the rocker  66  may perform the role of a driving member joint with respect to the entire link apparatus  160 . However, the second spring fastening portion  68   a  may be formed on another constituent element such as the rocker  66 , or the like. 
     The shaft  74  may be rotatably installed in the case (C) at one side thereof, and hinge-coupled to the connecting link  70  at the other side thereof. 
     Furthermore, the shaft  74  may be hinge-coupled to the transfer link  90  by an insulating pin  180  which will be described later at separated portions of the one side and the other side thereof. 
     In this case, the shaft  74  may transfer a driving force received from the rocker  66  through the connecting link  70  to the movable contact  20  through the transfer link  90 . In other words, the shaft  74  may perform the role of a driving member joint with respect to the movable contact  20  while at the same time performing the role of a follower member joint with respect to the rocker  66 . 
     The connecting link  70  may be hinge-coupled to the other side of the rocker  66  at one side thereof, and hinge-coupled to the other side of the shaft  74  at the other side thereof as described above. 
     The transfer link  90  may be hinge-coupled to at separated portions of the one side and the other side of the shaft  74  by an insulating pin  180  which will be described later at one side thereof as described above, and hinge-coupled to the other side of the movable contact  20  at the other side thereof. 
     The insulating pin  180  may hinge-couple the shaft  74  to the transfer link  90  as well as insulate the shaft  74  and the transfer link  90  from each other. 
     Here, for the sake of convenience of explanation, portions hinge-coupled thereto by the insulating pin  180  may be referred to as a shaft connecting port  74   c  and a transfer link connecting port  90   c . In other words, separated portions of the one side and the other side thereof may be referred to as the shaft connecting port  74   c , and one side of the transfer link  90  may be referred to as the transfer link connecting port  90   c.    
       FIG. 4  is a cross-sectional view illustrating the process of forming an insulating member in  FIG. 3 , and  FIG. 5  is a perspective view illustrating the process of forming a wear resistant member in  FIG. 3 , and  FIG. 6  is an assembly view illustrating an insulating member and a wear resistant member in  FIGS. 4 and 5 , and  FIG. 7  is a cross-sectional view subsequent to the assembly of  FIG. 6 , and  FIG. 8A ,  FIG. 8B  and  FIG. 8C  are cross-sectional views illustrating the process of pressing an insulating pin with a press, and  FIG. 9  is a cross-sectional view illustrating the insulating pin of  FIG. 3  fabricated by the pressure process of  FIG. 8A ,  FIG. 8B  and  FIG. 8C , and  FIG. 10  is a cross-sectional view in  FIG. 9 , and  FIG. 11  is a perspective view illustrating a press in  FIG. 8A ,  FIG. 8B  and  FIG. 8C . 
     As illustrated in  FIGS. 3 and 9 , the insulating pin  180  may include a wear resistant member  184  installed to surround a contact portion between an insulating member  182  formed in a cylindrical rod shape and the shaft connecting port  74   c  of the insulating member  182 . 
     In this case, the insulating member  182  may be formed of polyethylene, but may be also formed of other materials having an insulating performance. 
     Furthermore, the wear resistant member  184  may be formed of stainless steel, but may be also formed of other materials having a wear resistance larger than that of the insulating member  182 . 
     The insulating pin  180  may be fabricated as follows. 
     First, the insulating member  182  may be formed in a cylindrical rod shape as described above. 
     The insulating member  182  may be formed using a drawing process for allowing a raw material (S1) to pass through a drawing die (D1) and then cutting the raw material (S1) as illustrated in  FIG. 4 . 
     On the other hand, the wear resistant member  184  may be formed in a cylinder shape having a length shorter than that of the insulating member  182 , and a length greater than that of a contact portion to the shaft connecting port  74   c  of the insulating member  182  to surround the circumference of a contact portion to the shaft connecting port  74   c  of the insulating member  182 . 
     The wear resistant member  184  may be formed perpendicular to an outer circumferential surface and an inner circumferential surface of the wear resistant member  184  as illustrated in  FIGS. 5 through 7  prior to pressing the cross section of both end portions at an initial stage. 
     It is not to interfere with the insulating member  182  as illustrated in  FIG. 7  prior to pressing the wear resistant member  184 , and to perform plastic deformation on the end portion in the form of having an excellent release resistance strength as illustrated in  FIG. 10  subsequent to pressing the wear resistant member  184 . 
     For reference, when inclined inner chamfers are formed on the cross section of the end portion and the inner circumferential surface, respectively, contrary to the foregoing description, the wear resistant member  184  may have a release resistance strength subsequent to pressure process lower than when the cross section of the end portion is formed perpendicular to the inner circumferential surface. 
     Subsequently, in order to form the cross section of both end portions perpendicular to an outer circumferential surface and an inner circumferential surface of the wear resistant member  184 , the wear resistant member  184  may be formed such that a cylindrically shaped material (S2) is drilled in a length direction by a drill (D2), and the drilled material (S2′) is cut by a predetermined length, and a burr (BR) of the cut material (S″) is removed as illustrated in  FIG. 5 . 
     For reference, when the cylindrically shaped material (S2) is cut by a predetermined length and then the cut material is drilled in an axial direction, the wear resistant member  184  may be subject to a dimensional deformation problem. 
     Accordingly, the wear resistant member  184  may be preferably formed that the cylindrically shaped material (S2) is drilled in a length direction, and the drilled material (S2′) is cut by a predetermined length, and a burr (BR) of the cut material (S″) is removed as described above. 
     Here, the predetermined length is a length shorter than that of the insulating member  182 , and greater than that of a contact portion to the shaft connecting port  74   c  of the insulating member  182  to surround the circumference of a contact portion to the shaft connecting port  74   c  of the insulating member  182 . 
     Subsequently, the insulating member  182  and the wear resistant member  184  formed as described above may be formed in such a manner that the insulating member  182  is inserted into an inner side of the wear resistant member  184  as illustrated in  FIGS. 6 and 7 . 
     Due to this, it may be disposed such that the wear resistant member  184  is attached to a contact portion to the shaft connecting port  74   c  of the insulating member  182 . 
     Next, at least one end of the wear resistant member  184  may be plastically deformed to burrow into an inner side, namely, toward a central portion thereof from an outer circumferential surface of the insulating member  182  by a pressure process such as a caulking process or the like. 
     In case of the present embodiment, the wear resistant member  184  may be plastically deformed to allow both end portions to burrow into an inner side from an outer circumferential surface of the insulating member  182  with a pressure process using the press  200  as illustrated in  FIGS. 8 and 10 . 
     More specifically, both end portions of the wear resistant member  184  disposed at a contact portion to the shaft connecting port  74   c  of the insulating member  182  as illustrated in  FIG. 7  may be pressed against the press  200  as illustrated in  FIG. 8A ,  FIG. 8B  and  FIG. 8C . 
     Here, the press  200  may press both ends of the wear resistant member  184  in an axial direction of the wear resistant member  184  by a predetermined dimension. 
     The press  200  may include a die  210  installed in a fixed manner, and a punch  220  installed to face the die  210  so as to move toward the die  210  as illustrated in  FIGS. 8 and 11 . 
     The die  210  may include a first press surface  212  which is a plane facing in parallel to a second press surface  222  of the punch  220  which will be described later and a first groove  214  formed perpendicular to the first press surface  212 . 
     The first groove  214  may include a first insertion portion  214   b  formed in an engraved cylindrical shape in a direction perpendicular to the first press surface  212 . 
     Furthermore, the first groove  214  may include a first chamfer portion  214   a  inclined to an inner circumferential surface of the first insertion portion  214   b  and the first press surface  212 , respectively. 
     According to the foregoing configuration, the insulating pin  180  (hereinafter, referred to as an “insulating pin prior to plastic deformation”) in a state that the wear resistant member  184  is disposed at a contact portion to the shaft connecting port  74   c  of the insulating member  182  may be formed such that an end of the wear resistant member  184  is engaged with the first chamfer portion  214   a , and an end of the insulating member  182  protruded from an end of the wear resistant member  184  is inserted into the first insertion portion  214   b.    
     Due to this, the insulating pin  180  prior to plastic deformation may be placed perpendicular to the first press surface  212  with respect to the length direction. 
     The punch  220  may include a second press surface  222  which is a plane facing in parallel to the first press surface  212  and a second groove  224  formed perpendicular to the second press surface  222  to correspond to the first groove  214 . 
     The second groove  224  may include a second insertion portion  224   b  formed in an engraved cylindrical shape in a direction perpendicular to the second press surface  222 . 
     Furthermore, the second groove  224  may include a second chamfer portion  224   a  inclined to an inner circumferential surface of the second insertion portion  224   b  and the second press surface  222  and, respectively. 
     Due to the foregoing configuration, when the punch moves toward the die, the insulating pin  180  prior to plastic deformation placed on the die may be formed such that the other end of the wear resistant member  184  is engaged with the second chamfer portion  224   a , and the other end of the insulating member  182  protruded from the other end of the wear resistant member  184  is inserted into the second insertion portion  224   b.    
     Here, the first chamfer portion  214   a  is formed to be inclined to an inner circumferential surface of the first insertion portion  214   b  and the second chamfer portion  224   a  is formed to be inclined to an inner circumferential surface of the second insertion portion  224   b.    
     Due to this, the first chamfer portion  214   a  and the second chamfer portion  224   a  deform both ends of the wear resistant member  184  while moving along an inclined surface to burrow into the insulating member  182  when both ends of the wear resistant member  184  is pressed. 
     On the other hand, the die  210  and the punch  220  may include an excessive compression prevention protrusion (B) configured not to allow the first press surface  212  and the second press surface  222  to get closer more than a predetermined distance when pressing both ends of the wear resistant member  184 . 
     The excessive compression prevention protrusion (B) may include a first excessive compression prevention protrusion  216  protruded toward the second press surface from the first press surface  212  and a second excessive compression prevention protrusion  226  protruded to face the first excessive compression prevention protrusion  216  from the second press surface  222 . 
     The sum of a protrusion length from the first press surface  212  of the first excessive compression prevention protrusion  216  and a protrusion length from the second press surface  222  of the second excessive compression prevention protrusion  226  may be formed to be the same as the predetermined distance. 
     Here, the predetermined dimension and the predetermined distance may be a value for preventing a bending phenomenon from occurring on an outer circumferential surface of the wear resistant member  184 . The bending phenomenon refers to a phenomenon a rugged bend are generated on an outer circumferential surface of the wear resistant member  184  when both ends of the wear resistant member  184  is excessively pressed. 
     Subsequently, both ends of the wear resistant member  184  pressed by the press  200  provided as described above may be plastically deformed to burrow into an inner side from an outer circumferential surface of the insulating member  182  as illustrated in  FIG. 10 . 
     Due to this, the wear resistant member  184  may be installed in a fixed manner at a contact portion to the shaft connecting port  74   c  of the insulating member  182  not to be released in a length direction of the insulating member  182 , namely, in an axial direction of the insulating member  182 . 
     Up to now, a method of fabricating the insulating pin  180  according to an embodiment has been described. 
     However, the present disclosure may not be necessarily limited to this, and there may be various modified examples for a method of fabricating the insulating pin  180 . 
     In other words, the insulating member  182  are formed with a drawing process according to the present embodiment, but may be also formed with a cutting process or the like. 
     Furthermore, the cross section of an end portion of the wear resistant member  184  prior to performing a pressure process may be formed perpendicular to an outer circumferential surface and an inner circumferential surface of the wear resistant member  184  according to the present embodiment, but may be also formed with other shapes if it is able to achieve the foregoing objective (when an end portion of the wear resistant member is formed with a pressure process, it is plastically deformed in the form having an excellent release resistance strength). 
     Furthermore, an end portion of the wear resistant member  184  may be deformed and fixed to the insulating member  182  according to the present embodiment, but may be also fixed thereto using an adhesive or the like. 
     Furthermore, the insulating pin  180  may be formed with a method as illustrated in  FIG. 12 . 
       FIG. 12  is a cross-sectional view illustrating another embodiment of an insulating pin in  FIG. 3 . 
     As illustrated in  FIG. 12 , the insulating pin  280  formed with a different method may include a wear resistant member  284  having a protruding portion and an insulating member  282  overlaid on the protruding portion. 
     The wear resistant member  284  having the protruding portion may include a shaft connecting port contact portion  284   a  formed in a cylindrical shape and a protruding portion  284   b  extended and formed in a length direction of the shaft connecting port contact portion  284   a  from at least one end portion of the shaft connecting port contact portion  284   a.    
     In this case, the protruding portion  284   b  may be extended and formed in a length direction of the shaft connecting port contact portion  284   a  from the center of an end portion of the shaft connecting port contact portion  284   a.    
     The protruding portion  284   b  may have a diameter smaller than that of the shaft connecting port contact portion  284   a.    
     The insulating member  282  overlaid on the protruding portion may be formed in a cylindrical shape having a diameter smaller than that of the shaft connecting port contact portion  284   a  and a diameter greater than that of the protruding portion  284   b.    
     Furthermore, a groove portion  282   a  into which the protruding portion  284   b  is inserted may be formed at the center of an end portion of the insulating member  282  overlaid on the protruding portion. 
     The wear resistant member  284  having the protruding portion and the insulating member  282  overlaid on the protruding portion may be fastened in such a manner that the protruding portion  284   b  is inserted into the groove portion  282   a.    
     In this case, the wear resistant member  284  having the protruding portion and the insulating member  282  overlaid on the protruding portion may be fastened by a frictional force due to a surface contact between the protruding portion  284   b  and the groove portion  282   a.    
     However, the wear resistant member  284  having the protruding portion and the insulating member  282  overlaid on the protruding portion may be fastened with a different method. 
     For example, when at least one or more release preventing protrusions (not shown) are formed in a circumferential direction on an outer circumferential surface of the protruding portion  284   b , and at least one or more release preventing grooves (not shown) are formed in a circumferential direction on an inner circumferential surface of the groove portion  282   a  to insert the protruding portion  284   b  into the groove portion  282   a , the release preventing protrusion may be caught in the release preventing groove. Due to this, the wear resistant member  284  having the protruding portion and the insulating member  282  overlaid on the protruding portion are fastened with each other. 
     On the other hand, according to the present embodiment, the press  200  may be formed in such a manner that the first excessive compression prevention protrusion  216  is protruded from the first press surface  212  and the second excessive compression prevention protrusion  226  is protruded from the second press surface  222 . Furthermore, the first excessive compression prevention protrusion  216  and the second excessive compression prevention protrusion  226  may be brought into contact with each other during a pressure process not to allow the first press surface  212  and the second press surface  222  to get closer more than a predetermined distance. 
     However, the present disclosure may not be necessarily limited to this. 
     For an example, only the first excessive compression prevention protrusion  216  may be formed on the press  200 . 
     In this case, the second press surface  222  may be extended and formed in a flat manner up to a portion corresponding to the first excessive compression prevention protrusion  216 . 
     Furthermore, the first excessive compression prevention protrusion  216  may be formed in such a manner that a protrusion length from the first press surface  212  is the same as the predetermined distance. 
     According to the foregoing configuration, when the die  210  and the punch  220  press both ends of the wear resistant member  284 , the first excessive compression prevention protrusion  216  may be brought into contact with second press surface  222 , thereby suppressing the first and the second press surface from getting closer more than a predetermined distance. 
     For another example, the excessive compression prevention protrusion (B) can be omitted as a whole. 
     In this case, the moving distance of the punch  220  may be controlled not to allow the first press surface  212  and the second press surface  222  to get closer than a predetermined distance. 
     For still another example, the first excessive compression prevention protrusion  216  and the second excessive compression prevention protrusion  226  may be formed to be protruded from another portion such as a lateral surface of the die  210 , a lateral surface of the  220 , or the like. In other words, the first excessive compression prevention protrusion  216  and the second excessive compression prevention protrusion  226  may be formed to be protruded from a portion other than the first press surface  212  and the second press surface  222 . 
     On the other hand, according to the present embodiment, a pair of the first excessive compression prevention protrusions  216  may be formed to be located at opposite sides to each other by interposing the first groove  214  therebetween, and a pair of the second excessive compression prevention protrusions  226  may be formed to be located at opposite sides to each other by interposing the second groove  224  therebetween to correspond to the pair of the first excessive compression prevention protrusions  216 . 
     It is to maintain the first press surface  212  and the second press surface  222  in parallel to each other when the first excessive compression prevention protrusion  216  and the second excessive compression prevention protrusion  226  are brought into contact with each other. 
     However, if the first press surface  212  and the second press surface  222  maintain a parallel relation to each other, then the first excessive compression prevention protrusion  216  and the second excessive compression prevention protrusion  226  may be formed in a different shape. 
     For example, when a contact surface between the first excessive compression prevention protrusion  216  and the second excessive compression prevention protrusion  226  has a sufficiently large area, only each one of them may be formed thereon. 
     Next, subsequent to a method of fabricating the insulating pin  180 , the additional description of a constituent element of the circuit breaker according to the present disclosure will be described. 
     In other words, referring to  FIG. 3 , a circuit breaker according to the present disclosure may be formed with a plurality of phases, and a pair of the stationary contact  10  and the movable contact  20  may be provided for each phase. 
     Accordingly, the switching mechanism  130  should be formed with a structure capable of switching a plurality of the movable contacts  20 . 
     Consequently, for the switching mechanism  130 , the transfer link  90  and the insulating pin  180  may be provided for each phase, and the other constituent elements of the switching mechanism  130  may be provided one by one. 
     Here, the shaft arm  74   b  protruded in a radial direction from the shaft rotation axis  74   a  may be formed for the shaft  74  for each phase. 
     The shaft arm  74   b  is hinge-coupled to the transfer link  90  by the insulating pin  180 . 
     On the other hand, on the basis of one phase, the latch  62 , the rocker  66 , the connecting link  70  and the shaft  74  may constitute a 5-joint link mechanism when the circuit breaker performs an opening operation (TRIP) due to an accident. 
     In the 5-joint link mechanism configured with the latch  62 , the rocker  66 , the connecting link  70  and the shaft  74 , a link for virtually connecting the latch rotation axis  62   a  to the shaft rotation axis  74   a  constitutes a stationary joint, and the latch  62 , the rocker  66 , the connecting link  70  and the shaft  74  are able to move. 
     Furthermore, the latch  62 , the rocker  66 , the connecting link  70  and the shaft  74  may constitute a 4-joint link mechanism when the circuit breaker performs a closing operation (ON) or artificial opening operation (TRIP). 
     In the 4-joint link mechanism configured with the latch  62 , the rocker  66 , the connecting link  70  and the shaft  74 , the latch  62  may be fixed by the latch holder (H). 
     Consequently, in the 4-joint link mechanism configured with the latch  62 , the rocker  66 , the connecting link  70  and the shaft  74 , a link for virtually connecting the rocker rotation axis  64  to the shaft rotation axis  74   a  constitutes a stationary joint, and the rocker  66 , the connecting link  70  and the shaft  74  are able to move. 
     Hereinafter, for the sake of convenience of explanation, in the 4-joint link mechanism configured with the latch  62 , the rocker  66 , the connecting link  70  and the shaft  74  is referred to as the 4-joint link mechanism configured with the rocker  66 , the connecting link  70  and the shaft  74 . 
     Furthermore, the shaft  74 , the transfer link  90  and the movable contact  20  may constitute a 4-joint link mechanism. 
     In the 4-joint link mechanism configured with the shaft  74 , the transfer link  90  and the movable contact  20 , a link for virtually connecting the shaft  74  to the movable contact  20  constitutes a stationary joint, and the shaft  74 , the transfer link  90  and the movable contact  20  are able to move. 
     Here, the 4-joint link mechanism configured with the shaft  74 , the transfer link  90  and the movable contact  20  may share the shaft  74  with a 5-joint link mechanism configured with the latch  62 , the rocker  66 , the connecting link  70  and the shaft  74  (or a 4-joint link mechanism configured with the rocker  66 , the connecting link  70  and the shaft  74 . 
     Due to this, the 4-joint link mechanism configured with the shaft  74 , the transfer link  90  and the movable contact  20  may be a link mechanism driven by the 5-joint link mechanism configured with the latch  62 , the rocker  66 , the connecting link  70  and the shaft  74  (or 4-joint link mechanism configured with the rocker  66 , the connecting link  70  and the shaft  74 ). 
     On the drawing, it should be noted that the same reference numerals are designated to the same portions in the related art. 
     The working effect of a circuit breaker and a method of fabricating an insulating pin for a switching mechanism thereof according to the present disclosure will be described. 
     First, the process of switching a circuit breaker from an artificial opening operation (OFF) state to a closing operation (ON) state will be described. 
     In an artificial opening operation (OFF) state illustrated in  FIG. 2 , when the operator rotates the handle  40  in a counter clockwise direction on the drawing, the tension spring  50  can be rotated in a counter clockwise direction on the drawing around the second spring fastening portion  68   a.    
     Accordingly, a spring force may be applied to the second spring fastening portion  68   a  in a left upward direction on the drawing. 
     The spring force may rotate the rocker  66  in a clockwise direction on the drawing, and rotate the shaft  74  in a clockwise direction on the drawing, and as a result, it may be operated as a driving force for rotating the movable contact  20  in a counter clockwise direction on the drawing. 
     As a result, referring to  FIG. 2 , in the 4-joint link mechanism configured with the rocker  66 , the connecting link  70  and the shaft  74 , the rocker  66  may be rotated in a clockwise direction on the drawing. 
     Accordingly, the connecting link  70  may be engaged with the pin  68  provided with the second spring fastening portion  68   a , and moved while being rotated in a counter clockwise direction on the drawing. 
     Accordingly, the shaft  74  may be rotated in a clockwise direction on the drawing. 
     Accordingly, in the 4-joint link mechanism configured with the shaft  74 , the transfer link  90  and the movable contact  20 , the transfer link  90  may be engaged with the insulating pin  180 , and moved while being rotated in a counter clockwise direction on the drawing. 
     Accordingly, the movable contact  20  may be rotated in a counter clockwise direction on the drawing to be brought into contact with the stationary contact  10 . 
     As a result, the circuit breaker may be in a closing operation (ON) state. 
     On the other hand, the process of switching a circuit breaker from a closing operation (ON) state to an artificial opening operation (OFF) state is opposite to the process of switching a circuit breaker from an artificial opening operation (OFF) state to a closing operation (ON) state as described above, and the detailed description thereof will be omitted. 
     Next, the process of switching a circuit breaker from a closing operation (ON) state to an opening operation (TRIP) state due to an accident will be described. 
     Prior to the description, the closing operation (ON) state will be described with reference to  FIG. 2  though not illustrated additionally. 
     When an abnormal current occurs in the closing operation (ON) state, the latch holder (H) may be rotated in a clockwise direction to release the locking of the latch  62 . 
     Accordingly, the latch  62  may be rotated around the latch rotation axis  62   a.    
     Accordingly, the spring force that has been applied to the second spring fastening portion  68   a  in a left upward direction may rotate the latch  62  in a counter clockwise direction, and rotate the shaft  74  in a counter clockwise direction, and thus operated as a driving force for rotating the movable contact  20  in a clockwise direction. 
     As a result, in the 5-joint link mechanism configured with the latch  62 , the rocker  66 , the connecting link  70  and the shaft  74 , the latch  62  may be rotated in a counter clockwise direction. 
     Accordingly, the rocker  66  is restricted by the rocker rotation axis  64 , and thus moved while being rotated in a counter clockwise direction. 
     Accordingly, the connecting link  70  is restricted by the pin  68  provided with the second spring fastening portion  68   a , and thus moved while being rotated in a counter clockwise direction. 
     Accordingly, the shaft  74  may be rotated in a counter clockwise direction. 
     Accordingly, in the 4-joint link mechanism configured with the shaft  74 , the transfer link  90  and the movable contact  20 , the transfer link  90  may be restricted by the insulating pin  180 , and thus moved while being rotated in a clockwise direction. 
     Accordingly, the movable contact  20  may be rotated in a counter clockwise direction, and thus separated from the stationary contact  10 . 
     As a result, the circuit breaker may be in an opening operation (TRIP) state due to an accident. 
     In this case, the opening operation (TRIP) state, when compared to  FIG. 2 , may be in a state that the handle  40  may be rotated in a counter clockwise direction, and the latch  62  is released from the locking of the latch holder (H) and rotated in a counter clockwise direction. 
     On the other hand, the process of rotating the handle  40  in a clockwise direction to engage the latch  62  with the latch holder (H) again so as to switch the circuit breaker to an artificial opening operation (OFF) state as illustrated in  FIG. 2  precedes the process of switching the circuit breaker from a opening operation (TRIP) state due to an accident to an closing operation (ON) state. The following process is the same as the process of switching the circuit breaker from the artificial opening operation (OFF) state to the closing operation (ON) state, and the description thereof will be omitted to avoid redundant description. 
     During the process, the insulating pin  180  may hinge-couple and insulate the shaft  74  and the transfer link  90 . 
     In other words, the insulating pin  180  may be hinge-coupled to the shaft connection opening  74   c  at the wear resistant member  184 , and hinge-coupled to the transfer link connection opening  90   c  at both ends of the insulating member  182  as illustrated in  FIG. 3 . 
     Due to this, the insulating pin  180  may transfer a driving force to the transfer link  90  from the shaft  74 . 
     Furthermore, the insulating pin  180  may be insulated by the insulating member  182 , thereby preventing a current applied to the transfer link  90  from the movable contact  20  from flowing to the shaft  74 . 
     In other words, the insulating pin  180  may perform phase-phase insulation to prevent dielectric breakdown from occurring from a particular phase to another phase through the shaft  74 . 
     Furthermore, the wear resistant member  184  of the insulating pin  180  may be installed between the shaft connection opening  74   c  and a contact portion to the shaft  74  of the insulating member  182 . 
     Due to this, the wear resistant member  184  may protect the insulating member  182  having a hardness lower than that of the shaft  74 , thereby preventing the insulating member  182  from being worn by the shaft  74 . 
     Here, a circuit breaker and a method of fabricating an insulating pin for a switching mechanism thereof according to the present disclosure may include the movable contact  20  configured to be brought into contact with or separated from the stationary contact  10  and the switching mechanism  130  configured to switch the movable contact  20 . 
     The switching mechanism  130  may include the shaft  74  rotatably installed therein, the transfer link configured  90  to transfer a driving force from the shaft  74  to the movable contact  20 , and the insulating pin  180  configured to hinge-couple the shaft to the transfer link and insulate them from each other. 
     The insulating pin  180  may include the insulating member  182  formed in a cylindrical shape, and the wear resistant member  184  formed with a pipe to be attached to a portion brought into contact with the shaft  74  of the insulating member  182 . 
     At least one end of the wear resistant member  184  may be deformed to burrow into the insulating member, and thus installed to be fixed to the insulating member  182 . 
     The wear resistant member  184  may be formed of a material such as stainless steel having a wear resistance greater than that of the insulating member  182  formed of an insulating material such as polyethylene. 
     The insulating pin  180  may be fabricated by a method of fabricating an insulating pin for a circuit breaker switching mechanism, and the method may include the first step of forming the insulating member  182  in a cylindrical shape, the second step of forming the wear resistant member  184  in a pipe shape capable of surrounding one side of the insulating member  182  which is a contact portion to the shaft  74 , the third step of inserting the insulating member  182  into the wear resistant member  184  and disposing the wear resistant member  184  at one side of the insulating member  182 , and the fourth step of deforming both ends of the wear resistant member  184  to burrow into the insulating member  182  so as to fix the wear resistant member  184  to one side of the insulating member  182 . 
     Due to this, phase-to-phase insulation may be carried out, and the abrasion and damage of the insulating pin  180  due to the shaft  74  may be suppressed. As a result, it may be possible to solve a contact pressure reduction and contact resistance increase problem between the movable contact  20  and the stationary contact  10  due to the abrasion and damage of the insulating pin  180 . 
     Furthermore, it may be possible to suppress the wear resistant member  184  from being released from an installation portion, more precisely, a portion brought into contact with the shaft  74  of the insulating member  182 . 
     Furthermore, according to a circuit breaker and a method of fabricating an insulating pin for a switching mechanism thereof in accordance with the present disclosure, the cross section of both end portions of the wear resistant member  184  may be formed perpendicular to an inner circumferential surface thereof by drilling a cylindrically shaped material (S2) in a length direction, and cutting the drilled material (S2′) by a predetermined length, and removing a burr (BR) of the cut material (S″) during the second step. 
     Due to this, compared to a case where the cross section of both end portions of the wear resistant member  184  is not formed perpendicular to an inner circumferential surface thereof, an end portion of the wear resistant member  184  may be deformed to have an excellent release resistance strength during the fourth step. 
     Furthermore, according to a circuit breaker and a method of fabricating an insulating pin for a switching mechanism thereof in accordance with the present disclosure, both end portions of the wear resistant member  184  may be deformed to burrow into the insulating member  182  by the press  200  capable of pressing both end portion edges of the wear resistant member  184  in an axial direction of the wear resistant member  184  during the fourth step. 
     Due to this, the wear resistant member  184  may be easily fixed to the insulating member  182 . 
     Furthermore, the press  200  may include the die  210  installed in a fixed manner; and the punch  220  configured to face the die  210 , and installed to move toward the die  210 . 
     At least one of the die  210  and the punch  220  may include an excessive compression prevention protrusion (B) protruded toward the other one thereof. 
     Due to this, when the die  210  and the punch  220  press both ends of the wear resistant member  184 , the excessive compression prevention protrusion (B) may prevent the die  210  and the punch  220  from getting closer more than a predetermined distance, thereby suppressing the bending phenomenon from occurring on an outer circumferential surface of the wear resistant member  184 .