Patent Publication Number: US-2009234191-A1

Title: Bending Part Coupling Assembly for the Endoscope Insertion Portion and Manufacturing Method Thereof

Description:
TECHNICAL FIELD 
     The present invention relates to a bending part coupling assembly forming a framework structure of an endoscope insertion portion, and a manufacturing method thereof. 
     BACKGROUND ART 
     A bending portion to be operated to be bent is arranged in an endoscope insertion portion, and this bending portion includes a bending part coupling assembly forming a framework structure thereof. In this bending part coupling assembly, a plurality of cylindrical bending parts are arranged side by side coaxially with respect to each other, and the bending parts adjacent to each other are coupled to swing by a pair of coupling portions provided at positions symmetrical with respect to a central axis. These coupling portions are formed by providing tongue piece portions protruding from both ends of each bending part, superimposing the tongue piece portions of the bending parts adjacent to each other, and riveting them to allow relative rotation thereof. 
     Further, Jpn. Pat. Appln. KOKAI Publication No. 7-128599 discloses formation of a coupling portion by interposing a steel ball between two superimposed tongue piece portions in place of riveting the tongue piece portions to improve assembling properties of a bending part coupling assembly. 
     DISCLOSURE OF INVENTION 
     However, in a conventional bending part coupling assembly, precise minute components must be very accurately assembled even in the case of such a bending part coupling assembly as disclosed in Jpn. Pat. Appln. KOKAI Publication No. 7-128599. Therefore, manufacture of the bending part coupling assembly is dependent on highly skilled manpower or requires a large-scale high-performance automatic assembling apparatus, and hence improving manufacturing efficiency of the bending part coupling assembly is difficult. 
     In view of the above-explained problem, it is an object of the present invention to provide a manufacturing method of a bending part coupling assembly for an endoscope insertion portion having a high manufacturing efficiency, and a bending part coupling assembly for an endoscope insertion portion suitable for manufacture based on such a manufacturing method. 
     In a first aspect of the present invention, a manufacturing method of a bending part coupling assembly for an endoscope insertion portion including a plurality of cylindrical bending parts arranged side by side coaxially with respect to each other and at least one coupling portion coupling the two bending parts adjacent to each other includes: a first step of forming in one plate material having elasticity a bending part coupling assembly preparing portion including a plurality of bending part preparing portions for formation of the plurality of bending parts and at least one coupling portion preparing portion for formation of at least the single coupling portion by punching in such a manner that the bending part coupling assembly preparing portion is supported by a support portion extending from an edge of the plate material; a second step of bending at least a portion of the coupling portion preparing portion to cross a plane parallel to the plate material; a third step of U-bending the bending part coupling assembly preparing portion at least once to form the bending part coupling assembly preparing portion into a cylindrical shape; and a fourth step of O-bending the U-bent bending part coupling assembly preparing portion to form the bending part coupling assembly preparing portion into a cylindrical shape. 
     In the manufacturing method of the bending part coupling assembly for the endoscope insertion portion, the entire bending part coupling assembly including both ends can be integrally manufactured from one plate material by punching and bending, thereby improving manufacturing efficiency of the bending part coupling assembly. 
     In a second aspect of the present invention, the entire bending part coupling assembly preparing portion is simultaneously processed in at least one of the first to fourth steps. 
     In the manufacturing method of the bending part coupling assembly for the endoscope insertion portion, the entire bending part coupling assembly preparing portion is processed at a time and hence a processing time for the bending part coupling assembly can be reduced. 
     In a third aspect of the present invention, the plate material is fed progressively to processing positions where the respective steps are carried out to be continuously processed in the first to fourth steps. 
     In the manufacturing method of the bending part coupling assembly for the endoscope insertion portion, the plate material is progressively passed to the processing position where each step is carried out to be continuously processed, thereby improving mass production efficiency of the bending part coupling assembly. 
     In a fourth aspect of the present invention, the plate material includes a longitudinal axis, and the processing is carried out with a longitudinal direction of the bending part coupling assembly preparing portion crossing a longitudinal direction of the plate material in the first to fourth steps. 
     In the manufacturing method of the bending part coupling assembly for the endoscope insertion portion, the processing is carried out with the longitudinal direction of the bending part coupling assembly preparing portion crossing the longitudinal direction of the plate material, and an entire length of a manufacturing line can be reduced as compared with an example where the longitudinal direction of the bending part coupling assembly preparing portion is parallel to the longitudinal direction of the plate material. 
     In a fifth aspect of the present invention, a core material is arranged in the U-bent bending part coupling assembly preparing portion to O-bend the bending part preparing portion along an outer peripheral surface of the core material in the fourth step. 
     In the manufacturing method of the bending part coupling assembly for the endoscope insertion portion, the core material is used in O-bending, thus improving processing performance of O-bending. 
     In a sixth aspect of the present invention, the manufacturing method of the bending part coupling assembly for the endoscope insertion portion further includes: a fifth step of joining both abutted side ends of the O-bent bending part preparing portion after the fourth step. 
     In the manufacturing method of the bending part coupling assembly for the endoscope insertion portion, both side ends of the bending part preparing portion are joined, and the bending part coupling assembly with improved strength can be manufactured as compared with an example where both side ends are not joined. 
     In a seventh aspect of the present invention, the manufacturing method of the bending part coupling assembly for the endoscope insertion portion further includes: a step of forming a connecting portion preparing portion for formation of a connecting portion connected with a distal end forming portion, a insertion tube portion, or an operating portion of an endoscope in the bending part preparing portion provided in at least one end of the bending part coupling assembly preparing portion before the third step. 
     In the manufacturing method of the bending part coupling assembly for the endoscope insertion portion, the connecting portion preparing portion is formed in the bending part preparing portion at the end of the bending part coupling assembly preparing portion to form the connecting portion at the end of the bending part coupling assembly. Therefore, additional processing for forming the connecting portion does not have to be performed after U- or O-bending, thereby further improving manufacturing efficiency of the bending part coupling assembly. 
     In an eighth aspect of the present invention, the manufacturing method of the bending part coupling assembly for the endoscope insertion portion further includes: a step of forming a wire receiver preparing portion for formation of a wire receiver through which a wire is inserted in at least one of the plurality of bending part preparing portions before the third step. 
     In the manufacturing method of the bending part coupling assembly for the endoscope insertion portion, the wire receiver preparing portion is formed in the at least one of the plurality of bending part preparing portions to form the wiring receiver in the bending part. Therefore, additional processing for forming the wire receiver does not have to be carried out after U- or O-bending, thereby further improving manufacturing efficiency of the bending part coupling assembly. 
     In a ninth aspect of the present invention, the wire receiver preparing portion is formed in each bending part preparing portion on one end side of the bending part coupling assembly preparing portion and the wire receiver preparing portion is not formed in each remaining bending part preparing portion on the other end side at the step of forming the wire receiver preparing portion. 
     In the manufacturing method of the bending part coupling assembly for the endoscope insertion portion, the wire receiver preparing portion is formed at each bending part preparing portion on the one end side of the bending part coupling assembly preparing portion and the wire receiver preparing portion is not formed in each remaining bending part preparing portion on the other end side so that the wire receiver is formed in each bending part on the one end side of the bending part coupling assembly and the wire receiver is not formed in each remaining bending part preparing portion on the other end side. Therefore, a bending portion can be formed based on the one end side of the bending part coupling assembly, and an insertion tube portion can be formed based on the other end side. In the manner, the bending part coupling assembly which is entirely integrally manufactured based on punching and bending can be used to form a framework structure of the entire endoscope insertion portion, thereby improving manufacturing efficiency of the endoscope insertion portion. 
     In a tenth aspect of the present invention, a bending part coupling assembly for an endoscope insertion portion includes: a plurality of cylindrical bending parts arranged side by side coaxially with respect to each other; and at least one coupling portion coupling the two bending parts adjacent to each other, wherein the bending parts and the coupling portion are integrally formed from one plate material having elasticity, the coupling portion includes a hinge portion that is formed in at least a portion of the coupling portion and arranged to cross a cylindrical surface including circumferential surfaces of the two bending parts coupled through the coupling portion to allow relative swing of the two bending parts, the bending part at one end of the bending part coupling assembly includes a distal end side connecting portion connected with a distal end forming portion of an endoscope, and the bending part at the other end of the bending part coupling assembly includes a proximal end side connecting portion connected with a insertion tube portion or an operating portion of the endoscope. 
     The endoscope bending part coupling assembly is suitable for manufacture based on the manufacturing method of the bending part coupling assembly for the endoscope insertion portion in the first aspect of the present invention. 
     In an eleventh aspect of the present invention, the bending part includes a discontinuous portion extending in the entire bending part along an axial direction of the bending part. 
     The endoscope bending part coupling assembly is suitable for manufacture based on the manufacturing method of the bending part coupling assembly for the endoscope insertion portion in the first aspect of the present invention. 
     In a twelfth aspect of the present invention, the bending part includes a joint portion extending in the bending part along an axial direction of the bending part. 
     The endoscope bending part coupling assembly is suitable for manufacture based on the manufacturing method of the bending part coupling assembly for the endoscope insertion portion in the sixth aspect of the present invention. 
     In a thirteenth aspect of the present invention, at least one of the plurality of bending parts includes a wire receiver through which a wire is inserted. 
     The endoscope bending part coupling assembly is suitable for manufacture based on the manufacturing method of the bending part coupling assembly for the endoscope insertion portion in the eighth aspect of the present invention. 
     In a fourteenth aspect of the present invention, each bending part on one end side of the bending part coupling assembly includes the wire receiver, and each remaining bending part on the other end side does not include the wire receiver. 
     The endoscope bending part coupling assembly is suitable for manufacture based on the manufacturing method of the bending part coupling assembly for the endoscope insertion portion in the ninth aspect of the present invention. 
     In a fifteenth aspect of the present invention, an endoscope includes the above bending part coupling assembly for the endoscope insertion portion. 
     The endoscope includes the same effect as the bending part coupling assembly for the endoscope insertion portion. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a perspective view showing an endoscope according to a first embodiment of the present invention. 
         FIG. 2  is a perspective view showing a bending part coupling assembly, a distal end forming member, and a connection ring according to the first embodiment of the present invention. 
         FIG. 3  is a schematic view showing a pressing machine used in the manufacturing method of the bending part coupling assembly according to the first embodiment of the present invention. 
         FIG. 4A  is a top view and a side view for explaining steps  1  to  6  in the manufacturing method of the bending part coupling assembly according to the first embodiment of the present invention. 
         FIG. 4B  is a top view and a side view for explaining steps  7  to  11  in the manufacturing method of the bending part coupling assembly according to the first embodiment of the present invention. 
         FIG. 4C  is a transverse cross-sectional view for explaining O-bending in the manufacturing method of the bending part coupling assembly according to the first embodiment of the present invention. 
         FIG. 5  is a top view for explaining a manufacturing method of a bending part coupling assembly according to a second embodiment of the present invention. 
         FIG. 6  is a top view for explaining steps  10  to  16  in a manufacturing method of a bending part coupling assembly according to a third embodiment of the present invention. 
         FIG. 7A  is a transverse cross-sectional view for explaining steps  4 ,  5 , and  9  in the manufacturing method of a bending part coupling assembly according to a modification of the third embodiment of the present invention. 
         FIG. 7B  is a transverse cross-sectional view for explaining O-bending in the manufacturing method of the bending part coupling assembly according to the modification of the third embodiment of the present invention. 
         FIG. 7C  is a transverse cross-sectional view for explaining caulking in the manufacturing method of the bending part coupling assembly according to the modification of the third embodiment of the present invention. 
     
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     A first embodiment according to the present invention will now be explained with reference to  FIGS. 1 to 4C . 
     As shown in  FIG. 1 , an endoscope  10  according to the embodiment includes an elongated insertion portion  12  to be inserted into a body cavity. The insertion portion  12  is formed by sequentially coupling a distal end forming portion  14 , a bending portion  16  to be operated to be bent, and a long insertion tube portion  18  having flexibility from a distal end side. An operating portion  20  to be held and operated by an operator is coupled with a proximal end of the insertion portion  12 , and a vertical bending operation knob  21   a  and a lateral bending operation knob  21   b  for bending the bending portion  16  are arranged on the operating portion  20 . 
     Referring to  FIGS. 1 and 2 , the bending portion  16  includes bending part coupling assembly  22  forming a framework structure of the bending portion  16 . As will be explained later, the entire bending part coupling assembly  22  including both ends respectively connected with a proximal end side of the distal end forming portion  14  and a distal end side of the insertion tube portion  18  is integrally formed from one plate material having flexibility. In this bending part coupling assembly  22 , from the distal end forming portion  14  side, first to fifth cylindrical bending parts  26  including a small wall thickness are coaxially arranged side by side, and the bending parts  26  adjacent to each other are coupled with each other by first to fourth pairs of coupling portions  28 , each pair of which are placed at symmetrical positions with respect to a central axis of the bending portion  16 . 
     The coupling portion  28  includes a tabular hinge portion  30 , and this hinge portion  30  is arranged to be orthogonal to a cylindrical surface including a circumferential surface of each bending part  26  and extends in an axial direction of the bending part coupling assembly  22 . Through bending deformation of each hinge portion  30  of each pair of the coupling portions  28  in a substantially central part thereof, the two bending parts  26  coupled with this pair of the coupling portions  28  can swing. The first to fourth pairs of the coupling portions  28  are sequentially shifted and arranged at 90° in the axial direction of the bending part coupling assembly  22  as seen in the central axis direction of the bending part coupling assembly  22 . That is, the swing direction of the bending part  26  on the front end side of one bending part  26  is orthogonal to the swing direction of the bending part  26  on the rear end side of the one bending part  26 . Combining swings of such bending parts  26  enables the bending part coupling assembly  22  to bend in an arbitrary direction. 
     Further, the coupling portion  28  that couples the bending parts  26  adjacent to each other includes a pair of holding portions  32  arranged between the hinge portion  30  and the bending part  26 . The holding portion  32  is arranged on an end face of the bending part  26  along the above cylindrical surface entirely, extends from the end face of the bending part  26  in the axial direction of the bending part coupling assembly  22 , extends in the circumferential direction of the bending part coupling assembly  22 , and is coupled with an end of the hinge portion  30  via a bent shape  34 . Here, a bend line of the bent shape  34  is parallel to the axial direction of the bending part coupling assembly  22 . Therefore, the pair of holding portions  32  are separated from each other, a substantially central part of the hinge portion  30  whose end is coupled through the bent shape  34  thereto is constricted to reduce a width of the tabular shape, and this constricted portion facilitates a bending deformation. 
     Furthermore, first to fifth pairs of wire receivers  36  through which an operation wire for bending the bending portion  16  is inserted are respectively formed in the first to fifth bending parts  26 . These wire receivers  36  have a conformation that each portion between respective slits extending in the circumferential direction and arranged side by side in the bending parts  26  protrudes in a V-like shape toward the inner side in a radial direction. Moreover, the first to fifth pairs of wire receivers  36  are arranged at vertical positions and lateral positions alternately in the axial direction of the bending part coupling assembly  22  with respect to an observation viewing field of the endoscope  10 . In the embodiment, the pair of wire receivers  36  formed in each bending part  26  are aligned with formation positions of the coupling portions  28  on the proximal end side of the bending part  26  in the axial direction of the bending part coupling assembly  22 . Respective operation wires for vertical and lateral bending operations are inserted through the wire receivers  36  formed at vertical and lateral positions, and the bending portion  16  can be thereby operated to be bent in the vertical and lateral directions. 
     It is to be noted that, as will be explained later, each bending part  26  is formed by deforming a bending part preparing portion having a long plate shape made of one plate material into a cylindrical shape and abutting both side ends of this portion with each other. Therefore, a discontinuous portion  38  that extends over the entire length of the bending part  26  in the axial direction of the bending part coupling assembly  22  is formed in a cylindrical wall of the bending part  26 . 
     A distal end side of the first bending part  26  at the most distal end is fitted on the proximal end side of a distal end forming member  39  forming the distal end forming portion  14 . Additionally, a fixing hole  40  is formed in the cylindrical surface on the distal end side of the first bending part  26 , and the distal end side of the first bending part  26  is fixed on the proximal end side of the distal end forming member  39  by a fixing pin  41  disposed in this fixing hole  40 . On the other hand, the proximal end side of the fifth bending part  26  at the most proximal end is fitted on the distal end side of a connection ring  42  arranged at the distal end of the insertion tube portion  18 . In this manner, in the bending part coupling assembly  22  according to the embodiment, the distal end side of the first bending part  26  at the most distal end forms a distal end side connecting portion  43  connected with the distal end forming portion  14 , the proximal end side of the fifth bending part  26  at the most proximal end forms a proximal end side connecting portion  44  connected with the insertion tube portion  18 . 
     A manufacturing method of the bending part coupling assembly  22  according to the embodiment will now be explained. An outline of the manufacturing method of the bending part coupling assembly  22  will be described with reference to  FIG. 3 . In manufacturing the bending part coupling assembly  22 , a plate material  45  having elasticity is used. As the plate material  45 , for example, a metal plate material, e.g., a stainless steel plate material, a spring steel plate material, a non-iron-based spring plate material e.g., phosphorus bronze spring plate material, a resin plate material, or a composite plate material obtained by laminating these plate materials or adding a reinforcing material in these plate materials is used. The plate material  45  is wound around an uncoiler  46 . Further, the plate material  45  led out from the uncoiler  46  is straighten into a plane by a lever  47 . The plate material  45  led out from the leveler  47  is introduced into a progressive die  50  of a pressing machine  49  by a feeding device  48 . 
     This progressive die  50  is formed of a punch holder  51  as an upper die and a die holder  52  as a lower die. First to eleventh punches  58   a ,  58   b ,  58   j ,  58   k  are arranged side by side at equal intervals on a punch plate  54  of the punch holder  51 , and first to eleventh dies  60   a ,  60   b , . . . ,  60   j ,  60   k  are arranged side by side at equal intervals on a die plate  56  of the die holder  52 . The first to eleventh punches  58   a , . . . ,  58   k  and the first to eleventh dies  60   a ,  60   k  respectively face each other to form first to eleventh processing positions P 1 , P 2 , . . . , P 10 , P 11 . The plate material  45  is intermittently fed by a distance corresponding to each gap between the respective processing positions P 1 , . . . , P 11  by the feeding device  48 , and supplied progressively to the respective processing positions P 1 , . . . , P 11  to be continuously processed. 
     Respective steps in the manufacturing method of the bending part coupling assembly  22  will now be explained in detail with reference to  FIGS. 4A to 4C . An entire bending part coupling assembly preparing portion  66  for formation of the bending part coupling assembly  22  is simultaneously processed at the respective processing positions P 1 , . . . , P 11 . That is, at the respective processing positions P, . . . , P 11 , first to fifth bending part preparing portions  68  for formation of the first to fifth bending parts  26  and first to fourth pairs of coupling portion preparing portions  70  for formation of the first to fourth pairs of coupling portions  28  are simultaneously processed, whilst the plate material  45  is fed progressively. Further, a longitudinal direction of the bending part coupling assembly  22  is orthogonal to a longitudinal direction of the plate material  45 , i.e., a feed direction of the plate material  45 . 
     Step  1  (First Processing Position P 1 ) 
     A pair of pilot holes  61  are formed at both ends with respect to a width direction of the plate material  45 . This pair of pilot holes  61  serves for positioning the progressively fed plate material  45  at the respective processing positions P 2 , . . . , P 11 . 
     Step  2  (Second Processing Position P 2 ). 
     In steps  2  and  3 , first to fifth pairs of wire receiver preparing portions  62  for formation of the first to fifth pairs of wire receivers  36  are formed. 
     Here, the two wire receiver preparing portions  62  in one pair of wire receiver preparing portions  62  are arranged side by side to be apart from each other in the longitudinal direction of the plate material  45  by a distance corresponding to a length between the two wire receivers  36  in the circumferential direction of the bending part coupling assembly  22 . Furthermore, the first to fifth pairs of wire receiver preparing portions  62  are arranged side by side to be apart from each other in the width direction of the plate material  45  by a length corresponding to a length between pairs of wire receivers  36  adjacent to each other in the axial direction of the bending part coupling assembly  22 . Moreover, the second and fourth pairs of wire receiver preparing portions  62  are arranged to be shifted toward the distal end side in the longitudinal direction of the plate material  45  by a length corresponding to ½ of the length between the two wire receivers  36  in the circumferential direction of the bending part coupling assembly  22  with respect to the first, third, and fifth pairs of wire receiver preparing portions  62 . 
     In step  2 , a pair of slits  64  that respectively define a distal end surface and a proximal end surface of the wire receiver  36  are formed. This pair of slits  64  extend in the longitudinal direction of the plate material  45 , and are arranged side by side with respect to each other. Here, a length of the slit  64  in the longitudinal direction of the plate material  45  corresponds to a length of the wire receiver  36  in the circumferential direction of the bending part coupling assembly  22 , and a gap between one pair of slits  64  corresponds to a length of the wire receiver  36  in the axial direction of the bending part coupling assembly  22 . 
     Step  3  (Third Processing Position P 3 ) 
     A portion between one pair of slits  64  is bent into a V-like shape from the side serving as an outer peripheral surface of the bending part  26  toward the side serving as an inner peripheral surface of the same (from a rear side toward a front side of a page space), thereby forming the wire receiver preparing portion  62 . 
     Steps  4  to  6  (Fourth to Sixth Processing Positions P 4 , P 5 , and P 6 ) 
     In the respective steps  4  to  6 , in the plate material  45 , punching planned portions of the plate material  45  are gradually punched to form the bending part coupling assembly preparing portion  66  for formation of one bending part coupling assembly  22  along the width direction of the plate material  45 . That is, in the plate material  45 , first to fifth bending part preparing portions  68  for formation of the first to fifth bending parts  26  and first to fourth coupling portion preparing portions  70  for formation of the first to fourth coupling portions  28  are formed along the width direction of the plate material  45 . 
     As seen clearly from a contour outline at the processing position P 6 , the first to fifth bending part preparing portions  68  respectively have a long plate shape extending in the longitudinal direction of the plate material  45  and are arranged side by side with respect to each other in the width direction of the plate material  45  based on punching in press processing. Moreover, the first to fifth bending part preparing portions  68  respectively includes the first to fifth wire receiving preparing portions  62 . 
     The coupling portion preparing portions  70  are parallel to a plane of the plate material, provided on the plane, and include tabular hinge portion preparing portions  72  extending in the width direction of the plate material  45 . Additionally, each coupling portion preparing portion  70  includes a pair of holding portion preparing portions  74  arranged between the bending part preparing portion  68  and the hinge portion preparing portion  72 . These holding portion preparing portions  74  are led out in the width direction of the plate material  45  from the bending part preparing portion  68 , extend in the longitudinal direction of the plate material  45 , and are coupled with the end of the hinge portion preparing portion  72  via a bent shape preparing portion  76 . The bent shape preparing portion  76  has a linear shape that is to be bent with respect to the pair of holding portion preparing portions  74  and parallel to the width direction of the plate material  45 . 
     Both coupling portion preparing portions  70  of pair of coupling portion preparing portions  70  are arranged side by side in the longitudinal direction of the plate material  45 . Further, each first coupling portion preparing portion  70  between the first and second bending part preparing portions  68  is aligned with each second wire receiver preparing portion  62  of the second bending part preparing portion  68  in the width direction of the plate material  45 . Further, each second coupling portion preparing portion  70  between the second and third bending part preparing portions  68  is aligned with each third wire receiver preparing portion  62  of the third bending part preparing portion  68  in the width direction of the plate material  45 . Each of the third and fourth coupling portion preparing portions  70  is likewise arranged. 
     Furthermore, a fixing hole preparing portion  78  for formation of the fixing hole  40  of the first bending part  28  is formed in the first bending part preparing portion  68 . Moreover, a distal end side connecting portion preparing portion  79  for formation of the distal end side connecting portion  43  connected with the distal end forming portion  14  is formed on the end side of the first bending part preparing portion  68 . Additionally, a proximal end side connecting portion preparing portion  80  for formation of the proximal end side connecting portion  44  connected with the insertion tube portion  18  is formed on the end side of the fifth bending part preparing portion  68 . 
     It is to be noted that, after the sixth step ends, the bending part coupling assembly preparing portion  66  is supported with respect to both ends of the plate material by a pair of support portions  81 . The pair of support portions  81  extend inwardly in the axial direction from both ends (both edges) of the plate material  45  in the width direction, and are coupled with central parts of the respective first and fifth bending part preparing portions  68  with respect to the longitudinal direction of the plate material  45  on the end sides of the respective first and fifth bending part preparing portions  68 . 
     Step  7  (Seventh Processing Position P 7 ) 
     In the bent shape preparing portion  76  of the coupling portion preparing portion  70 , the hinge portion preparing portion  72  is bent to be orthogonal to the plane of the plate material  45  from the side serving as the outer peripheral surface of the bending part  26  toward the side serving as the inner peripheral surface thereof (from the rear side toward the front side of a page space). As a result, the hinge portion preparing portion  72  becomes substantially orthogonal to the holding portion preparing portion  74 . 
     Steps  8  and  9  (Eighth and Ninth Processing Positions P 8  and P 9 ) 
     In steps  8  and  9 , a line running through the pair of support portions  81  and extending in the width direction of the plate material  45  serve as a bottom line, and the bending part coupling assembly preparing portion  66  is subjected to U-bending from the side serving as the outer peripheral surface of the bending part  26  toward the side serving as the inner peripheral surface thereof (from the rear side toward the front side of a page space) to reach a final curvature from a plane state. It is to be noted that a side end of the planar bending part coupling assembly preparing portion  66  with respect to the longitudinal direction of the plate material  45  is subjected to U-bending in step  8  (first U-bending) and a central portion of the bending part coupling assembly preparing portion  66  with respect to the longitudinal direction of the plate material  45  is subjected to U-bending in step  9  (second U-bending). 
     Step  10  (Tenth Processing Position P 10 ) 
     The U-bent bending part coupling assembly preparing portion  66  is further subjected to O-bending to form the cylindrical bending part  26 . At this time, each cored bar  82  is respectively protruded inwardly along the width direction from both side ends with respect to the width direction of the plate material  45  so that the cored bar  82  is arranged in the U-bent bending part coupling assembly preparing portion  66 , and the bending part coupling assembly preparing portion  66  is subjected to O-bending along an outer peripheral surface of the cored bar  82 . As shown in  FIG. 4C , the cored bar  82  is formed by extending a groove portion  85  that accommodates the wire receiver preparing portion  62  on an outer peripheral surface portion of a columnar main body portion  84  along a longitudinal direction of the main body portion  84 . It is to be noted that both side faces of the bending part preparing portion  68  formed based on O-bending face and about with each other. 
     Step  11  (Eleventh Processing Position P 11 ) 
     The pair of support portions  81  formed at both ends with respect to the width direction of the plate material  45  are stricken down to separate the bending part coupling assembly preparing portion  66  from the plate material  45 , thereby obtaining the bending part coupling assembly  22 . 
     Therefore, the embodiment includes the following effect. 
     In the manufacturing method of the bending part coupling assembly  22  according to the embodiment, the bending part coupling assembly preparing portion  66  is formed in one plate material  45  having elasticity based on punching in such a manner that it is supported by the pair of support portions  81  extending from both ends of the plate material  45  with respect to the width direction. Here, the bending part coupling assembly preparing portion  66  includes the first to fifth bending part preparing portions  68  for formation of the first to fifth bending parts  26  and the first to fourth pairs of coupling portion preparing portions  70  for formation of the first to fourth pairs of coupling portions  28 . Further, the hinge portion preparing portion  72  of the coupling portion preparing portion  70  is bent to be orthogonal to the plane parallel to the plate material  45 . Furthermore, to form the bending part coupling assembly preparing portion  66  into a cylindrical shape, the bending part coupling assembly preparing portion  66  is subjected to U-bending twice and further subjected to O-bending. As explained above, in the manufacturing method of the bending part coupling assembly  22  according to the embodiment, the entire bending part coupling assembly  22  including both ends respectively connected with the proximal end side of the distal end forming portion  14  and the distal end side of the insertion tube portion  18  can be integrally manufactured from the single plate material  45  by press processing alone, thereby improving manufacturing efficiency of the bending part coupling assembly  22 . 
     Here, the bending part coupling assembly  22  according to the embodiment includes the first to fifth cylindrical bending parts  26  that are coaxially arranged side by side with respect to each other and the first to fourth coupling portions  28  that couple the bending parts  26  adjacent to each other, and these bending parts  26  and coupling portions  28  are integrally formed from the single plate material  45  having elasticity. Moreover, each bending part  26  includes the discontinuous portion  38  extending in each entire bending part  26  along the axial direction of the bending part  26 . Additionally, each coupling portion  28  includes the hinge portion  30 , and this hinge portion  30  is formed on each of both end sides of the bending parts  26  adjacent to each other and arranged to cross a cylindrical surface having circumferential surfaces of the bending parts  26  coupled with each other through the coupling portion  28 , thereby allowing relative swing of the bending parts  26 . Further, the bending part  26  provided at the most distal end of the bending part coupling assembly  22  includes the distal end side connecting portion  43  connected with the distal end forming portion  14 , and the bending part  26  provided at the most proximal end of the bending part coupling assembly  22  includes the proximal end side connecting portion  44  connected with the insertion tube portion  18 . Such a bending part coupling assembly  22  is suitable for manufacture based on the manufacturing method of the bending part coupling assembly  22  according to the embodiment. 
     Further, at the processing positions P 1 , . . . , P 11 , the entire bending part coupling assembly preparing portion  66  is simultaneously processed, thereby reducing a processing time for the bending part coupling assembly  22 . 
     Furthermore, the plate material  45  is fed progressively to the processing positions P 1 , . . . , P 11  where the respective steps are carried out to be continuously processed, thus improving mass production efficiency of the bending part coupling assembly  22 . 
     Moreover, the longitudinal direction of the bending part coupling assembly preparing portion  66  is orthogonal to the longitudinal direction of the plate material  45 , and an entire length of a manufacturing line can be shortened as compared with an example where the longitudinal direction of the bending part coupling assembly preparing portion  66  is parallel to the longitudinal direction of the plate material  45 . 
     Additionally, the cored bar  82  is arranged in the U-bent bending part coupling assembly preparing portion  66 , the bending part preparing portion  68  is subjected to O-bending along the outer peripheral surface of the cored bar  82 , and hence the processing performance of O-bending is improved. 
     Further, at the time of striking down the pair of support portions  81 , the distal end side connecting portion  43  connected with the distal end forming portion  14  has been formed at one end of the bending part coupling assembly  22  and the proximal end connecting portion  44  connected with the insertion tube portion  18  has been formed at the other end of the bending part coupling assembly  22  by forming the distal end side connecting portion preparing portion  79  in the bending part  26  at one end of the bending part coupling assembly preparing portion  66  and the proximal end side connecting portion preparing portion  80  in the bending part  26  at the other end of the bending part coupling assembly preparing portion  66 . As explained above, additional processing for formation of the distal end connecting portion  43  and the proximal end connecting portion  44  does not have to be carried out after press working, thus further improving manufacturing efficiency of the bending part coupling assembly  22 . 
     Furthermore, each wire receiver  36  is formed in the bending part  26  by forming each wire receiver preparing portion  62  in the bending part preparing portion  68  based on slit processing and bending. In this manner, additional processing for formation of the wire receiver  36  does not have to be performed after press processing, thereby further improving manufacturing efficiency of the bending part coupling assembly  22 . 
     Here, the bending part  26  of the bending part coupling assembly  22  according to the embodiment includes the wire receiver  36 , and such a bending part coupling assembly  22  is suitable for manufacture based on the manufacturing method of the bending part coupling assembly  22  according to the embodiment. 
       FIG. 5  shows a second embodiment according to the present invention. Like reference numerals denote structures having the same functions as those in the first embodiment, thereby omitting an explanation.  FIG. 5  shows steps corresponding to steps carried out at the processing positions P 10  and P 11  depicted in  FIG. 4B . 
     The bending part coupling assembly  22  according to the embodiment is formed of seven bending parts  26   a  and  26   b  and six pairs of coupling portions  28  at the processing position P 11 . Moreover, wire receivers  36  are formed in the three bending parts  26   a  on the distal end side, and these three bending parts  26   a  form the framework structure of the bending portion  16 . The distal end side of the bending part  26   a  provided at the most distal end is fitted on and fixed to the proximal end side of the distal end forming member  39 , thereby forming the distal end side connecting portion  43 . It is to be noted that the fixing hole  40  is not formed in the distal end side connecting portion  43  according to the embodiment. On the other hand, the wire receivers  36  are not formed in the four bending parts  26   b  on the proximal end side, and these four bending parts  26   b  form the framework structure of the insertion tube portion  18 . The proximal end side of the bending part  26   b  provided at the most proximal end is connected with the distal end of the operating portion  20  of the endoscope  10 , thereby forming the proximal end side connecting portion  44 . 
     In the manufacturing method of the bending part coupling assembly  22  according to the embodiment, the entire bending part coupling assembly preparing portion  66  including first to seventh bending part preparing portions  68   a  and  68   b  and first to sixth pairs of coupling portion preparing portions  70  is simultaneously processed. The manufacturing method of the bending part coupling assembly  22  according to the embodiment is substantially the same as the manufacturing method of the bending part coupling assembly according to the first embodiment. That is, after forming the pilot hole  61  in the first step, wire receiver preparing portions  62  are formed at positions corresponding to the first to third bending part preparing portions  68   a  alone and the wire receiver preparing portions  62  are not formed at positions corresponding to the fourth to seventh bending part preparing portions  68   b , in the second and third steps. Subsequent steps are the same as those in the first embodiment. 
     Therefore, the embodiment includes the following effect. 
     In the manufacturing method of the bending part coupling assembly  22  according to the embodiment, the wire receiver preparing portion  62  is formed in each bending part preparing portion  68   a  on one end side of the bending part coupling assembly preparing portion  66  and the wire receiver preparing portion  62  is not formed in the bending part preparation portions  68   b  on the other end side so that the wire receiver  36  is formed in each bending parts  26   a  on one end side of the bending part coupling assembly  22  and the wire receiver  36  is not formed in the remaining bending parts  26   b  on the other end side. As the result, one end side of the bending part coupling assembly  22  enables forming the bending portion  16 , and the other end side of the same enables forming the insertion tube portion  18 . In this manner, using the bending part coupling assembly  22  that is entirely integrally manufactured from one plate material by press processing alone enables forming the entire framework structure of the endoscope insertion portion  12 , thereby improving manufacturing efficiency of the endoscope insertion portion  12 . 
     Here, bending parts  26  on the distal end side of the bending part coupling assembly  22  according to the embodiment includes the wire receiver  36 , and remaining bending parts  26  on the proximal end side does not include the wire receiver  36 . Therefore, the bending part coupling assembly  22  according to the embodiment is suitable for manufacture based on the manufacturing method of the bending part coupling assembly  22  according to the embodiment. 
       FIG. 6  shows the third embodiment according to the present invention. Like reference numerals denote structures having the same functions as those in the first embodiment, thereby omitting an explanation.  FIG. 6  is the explanatory drawing of steps after the step carried out at the processing position P 10  depicted in  FIG. 4B . 
     The bending part  26  of the bending part coupling assembly  22  according to the embodiment is formed by deforming the bending part preparing portion  68  having the long plate shape into the cylindrical shape, and abutting and joining both side ends thereof with each other as will be explained later in detail. Therefore, the joint portion  83  extending in the axial direction of the bending part  26  is formed in each bending part  26 . 
     Respective steps in the manufacturing method of the bending part coupling assembly  22  according to the embodiment will now be explained in detail with reference to  FIG. 6 . 
     Steps  1  to  10   
     Based on the same procedure as in steps  1  to  10  in the first embodiment, the O-bent bending part coupling assembly preparing portion  66  is formed wherein both side ends of the bending part preparing portion  68  are abutted with each other. 
     Steps  11  to  15  (Eleventh to Fifteenth Processing Positions P 11 , . . . , P 15 ) 
     In steps  11  to  15 , abutted portion formed of both side ends of each of the first to fifth bending part preparing portions  68  in the first to fifth bending part preparing portions  68  are sequentially jointed. 
     Specifically, the laser emission unit  86  is arranged at each of the eleventh to fifteenth processing positions P 11 , . . . , P 15 , and the abutted portions are subjected to laser welding in the order of the first, fourth, second, fifth, and third bending part preparing portions  68  in steps  11  to  15 . 
     Step  16  (Sixteenth Processing Position) 
     As in step  11  in the first embodiment, the pair of support portions  81  formed at both ends with respect to the width direction of the plate material  45  is stricken down to separate the bending part coupling assembly preparing portion  66  from the plate material  45 , thereby obtaining the bending part coupling assembly  22 . 
     Therefore, the embodiment includes the following effect. 
     In the manufacturing method of the bending part coupling assembly  22  according to the embodiment, both side ends of the bending part preparing portion  68  subjected to O-bending to be abutted with each other are joined. Therefore, as compared with the example where the abutted portions in the bending part preparing portion  68  are not joined, the bending part coupling assembly  22  having improved strength can be manufactured. 
     Here, each bending part  26  in the bending part coupling assembly  22  according to the embodiment includes the joint portion  83  extending in each bending part  26  in the axial direction of the bending part  26 , and it is suitable for manufacture based on the manufacturing method of the bending part coupling assembly  22  according to the embodiment. 
       FIGS. 7A to 7C  show the modification of the third embodiment according to the present invention. Like reference numerals denote structures having the same functions as those in the first embodiment, thereby omitting the explanation. 
     Both side ends of the bending part  26  in the bending part coupling assembly  22  according to the embodiment are joined by caulking. 
     Respective steps in the manufacturing method of the bending part coupling assembly  22  according to the embodiment will now be explained in detail with reference to  FIGS. 7A to 7C . 
     Steps  1  to  3   
     As in steps  1  to  3  in the first embodiment, the pair of pilot holes  61  and the pair of wire receiver preparing portions  62  are formed in the plate material  45 . 
     Step  4  (see  FIG. 7A ) 
     A joint hole preparing portion  87  is formed by punching on the distal end side of the pair of wire receiver preparing portions  62  in the longitudinal direction of the plate material  45 . This joint hole preparing portion  87  will be arranged at one side end of the bending part preparing portion  68  having the long plate shape. 
     Step  5  (see  FIG. 7A ) 
     A joint protrusion preparing portion  88  formed of a large-diameter portion  90  on the proximal end side and a small-diameter portion  92  on the terminal end side is formed by burring on the rear end side of the pair of wire receiver preparing portions  62  with respect to the longitudinal direction of the plate material  45 . This joint protrusion preparing portion  88  will be arranged at the position of the other side end of the bending part preparing portion  68  having the long plate shape corresponding to the joint hole preparing portion  87 . 
     Steps  6  to  8   
     As in steps  4  to  6  in the first embodiment, the bending part preparing portion  68  and the coupling portion preparing portion  70  are formed by punching. 
     Step  9  (see  FIG. 7A ) 
     The other side end of the bending part preparing portion  68  where the joint protrusion preparing portion  88  is arranged is displaced by the amount corresponding to the thickness of the plate material  45  from the side serving as the outer peripheral surface of the bending part  26  toward the side serving as the inner peripheral surface of the same (from the rear side toward the front side of the page space) by step-bending exposing to the bending part preparing portion  68 . 
     Steps  10  to  12   
     As in steps  7  to  9  in the first embodiment, bending of the hinge portion preparing portion  72  in the coupling portion preparing portion  70  and U-bending of the bending part coupling assembly preparing portion  66  are carried out. 
     Step  13  (see  FIG. 7B ) 
     As in step  10  in the first embodiment, O-bending is performed. At this time, the other side end of the bending part preparing portion  68  displaced by step-bending is superimposed on the inner side of the one side end of the bending part preparing portion  68 , and the joint protrusion preparing portion  88  on the other side end is fitted in the joint hole preparing portion  87  on one side end. 
     Steps  14  to  18  (see  FIG. 7C ) 
     In steps  14  to  18 , both side ends of the bending part preparing portion  68  are joined by caulking at respective processing positions in the order of the first, fourth, second, fifth, and third bending part preparing portions  68 . That is, each cored bar die  94  is protruded inwardly in the width direction from both side ends with respect to the width direction of the plate material  45  so that the cored bar die  94  is arranged in the O-bent bending part coupling assembly preparing portion  66 . The cored bar die  94  is used to support the proximal end side of the joint protrusion preparing portion  88  from the inner side of the bending part preparing portion  68 , and the conical punch  96  is pushed into the small-diameter portion  92  at the terminal end of the joint protrusion preparing portion  88  from the outer side of the bending part preparing portion  68  to open the small-diameter portion  92 . As the result, the joint protrusion preparing portion  88  at the other side end of the bending part preparing portion  68  is engaged with one side end of the bending part preparing portion  68 . In this manner, both side ends of the bending part preparing portion  68  are joined. 
     Step  19   
     As in step  11  in the first embodiment, the pair of support portions  81  formed at both ends with respect to the width direction of the plate material  45  are stricken down to separate the bending part coupling assembly preparing portion  66  from the plate material  45 , thereby obtaining the bending part coupling assembly  22 . 
     Besides, resistance welding, the adhesive, and others may be used to join both side ends of the bending part coupling assembly preparing portion  66 . 
     Although the bending part coupling assembly  22  including a number of the bending parts  26  and the pair of coupling portions  28  has been explained in the foregoing embodiment, the numbers of the bending parts  26  and the pair of coupling portions  28  are appropriately selected in accordance with the desired length of the bending portion  16  or the insertion tube portion  18 . 
     Further, the connecting portion formed at the end of the bending part coupling assembly  22  has the various kinds of conformations, e.g., the soldering hole, the locking hole, the groove, the protrusion, and others in accordance with conformations of the connection member of the distal end forming portion  14 , the insertion tube portion  18  or the operating portion  20 . 
     Furthermore, the number of times of U- or O-bending may be increased or decreased in accordance with the bending amount. 
     Moreover, the number of the wire receivers formed in each bending part in the bending portion is not restricted to two, and the four wire receivers may be formed at equal intervals in the circumferential direction of the bending part. Although the wire receiver preparing portion  62  for formation of the wire receiver is formed by bending the portion between the slits  64  into the V-like shape in each embodiment, the present invention is not restricted thereto, and this portion may be bend into the arc shape. 
     Additionally, the U-like shape described in U-bending in each of the embodiments according to the present invention is not restricted to the shape having both sides parallel to each other and the bottom having the semi-arc shape, and any shape is adopted as long as it has both side surfaces and the bottom surface and the opened upper portion. 
     Further, the O-like shape described in O-bending in each of the embodiments according to the present invention is not restricted to the shape having both side faces of the bending part preparing portion abutted to each other, and may be the substantially cylindrical shape where both side faces are slightly apart from each other due to elasticity of the plate material forming the bending part preparing portion. 
     Furthermore, punching of the plate material is not restricted to punching based on press processing, and punching may be carried out by irradiating the energy line of, e.g., the laser processing device whose movement with respect to the plate material is NC-controlled. It is to be noted that manufacturing the bending part coupling assembly by pressing processing alone is preferable in terms of cost.