Patent Publication Number: US-2023150149-A1

Title: Insulating unit and robot

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of priority to Japanese Patent Application No. 2020-068429 filed on Apr. 6, 2020 with the Japan Patent Office, which is incorporated as a part of this application by reference in its entirety. 
     TECHNICAL FIELD 
     The present disclosure relates to an insulating unit and a robot. 
     BACKGROUND ART 
     Conventionally, among end effectors attached to a robotic arm, there is an end effector for performing a welding operation. Since such an end effector is a high-voltage electric apparatus, an electrical insulation is necessary between the end effector and the robotic arm. For example, Patent Document 1 discloses an industrial robot provided with an electric insulating member between a final reduction gear at a tip-end part of a robot body part and a wrist flange. The wrist flange provides a mechanical interface, and is configured so that the electric apparatus (end effector) is attached thereto. 
     Reference Document(s) of Conventional Art 
     [Patent Document] 
     [Patent Document 1] JP1999-114873A 
     DESCRIPTION OF THE DISCLOSURE 
     For example, in Patent Document 1, when attaching the insulating member to the existing robot body, removal and installation of the wrist flange are necessary. That is, a change in the structure of the robot body is necessary, and therefore, the installation of the insulating member takes time and effort. 
     One purpose of the present disclosure is to provide an insulating unit and a robot capable of simplifying installation of an insulating member to a robotic arm. 
     In order to achieve the above purpose, an insulating unit according to one aspect of the present disclosure is an insulating unit disposed so as to intervene between a tip-end member of a robotic arm and an end effector attached to the tip-end member, which includes an intermediate member fixed to the tip-end member, the end effector being attachable to the intermediate member, and an insulating member that is disposed between the intermediate member and the tip-end member, and insulates the intermediate member from the tip-end member. The intermediate member includes at least one first mounting hole into which a first bolt that fixes the intermediate member to the tip-end member is inserted, and at least one second mounting hole into which a second bolt that fixes the end effector to the intermediate member is inserted. The first mounting hole and the second mounting hole are disposed so that, in a state where the intermediate member is fixed to the tip-end member, the positions of the second mounting holes match with the positions of tip-end mounting holes for attachment of the end effector respectively, the tip-end mounting holes being formed beforehand in the tip-end member. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is a side view illustrating one example of a configuration of a robot according to Embodiment 1. 
         FIG.  2    is an exploded perspective view illustrating one example of a configuration of an insulating unit according to Embodiment 1. 
         FIG.  3    is a cross-sectional side view illustrating one example of the configuration of the insulating unit according to Embodiment 1. 
         FIG.  4    is a cross-sectional side view illustrating one example of a configuration of Modification 1 of the insulating unit according to Embodiment 1. 
         FIG.  5    is a cross-sectional side view illustrating one example of a configuration of Modification 2 of the insulating unit according to Embodiment 1. 
         FIG.  6    is an exploded perspective view illustrating one example of a configuration of an insulating unit according to Embodiment 2. 
         FIG.  7    is a cross-sectional side view illustrating one example of the configuration of the insulating unit according to Embodiment 2. 
     
    
    
     MODES FOR CARRYING OUT THE DISCLOSURE 
     Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that each embodiment which will be described below is to illustrate a comprehensive or concrete example. Further, among components in the following embodiments, components which are not described in the independent claims which indicate the top concept are described as arbitrary components. Moreover, each figure in the accompanying drawings is a schematic figure, and it is not necessarily illustrated exactly. Further, in each figure, the same reference characters are assigned to substantially the same components, and therefore, the redundant explanation may be omitted or simplified. 
     Embodiment 1 
     A configuration of a robot  1000  according to Embodiment 1 is described.  FIG.  1    is a side view illustrating one example of the configuration of the robot  1000  according to Embodiment 1. As illustrated in  FIG.  1   , the robot  1000  includes a robotic arm  1 , an end effector  2 , and an insulating unit  100 . The robotic arm  1  is fixedly disposed on an upper surface of an installation part  3  formed on a support surface, such as a floor surface etc. Although in this embodiment the installation part  3  is a table which is formed on the floor surface and has a horizontal upper surface, it is not limited to this configuration, and, for example, it may be a part of the floor surface. Note that the installed location of the robotic arm  1  is not limited to the floor surface, but it may be any kind of place (e.g., a stand such as a shelf, a wall, or a ceiling). 
     The end effector  2  is a component which applies an action to a processing object of the robot  1000 , and it is attached to a tip end of the robotic arm  1 . Although not limited to this configuration, the end effector  2  is an electric apparatus to which voltage is applied, and in this embodiment, it is a spot welding gun which is one example of an electric apparatus which handles high voltage. The robot  1000  performs a spot welding work on a workpiece W by using the end effector  2 . The end effector  2  is attached to the tip end of the robotic arm  1  via the insulating unit  100 . The insulating unit  100  is attached to the tip end of the robotic arm  1 , and the end effector  2  is attached to the insulating unit  100 . The insulating unit  100  electrically insulates the end effector  2  from the robotic arm  1 . 
     A configuration of the robotic arm  1  is described. As illustrated in  FIG.  1   , the robotic arm  1  is a component which freely moves the end effector  2 , and includes an arm body  10  and a base part  20 . The base part  20  supports the arm body  10  so as to be stewed, and is fixed to the upper surface of the installation part  3 . 
     The arm body  10  includes links  11 - 16  which are serially disposed from the base part  20  toward the tip end of the arm body  10 , joints JT 1 -JT 6  which sequentially connect the links  11 - 16  so as to be rotatable, and arm drives D 1 -D 6  which rotate the respective joints JT 1 -JT 6 . The joints JT 1 -JT 6  are rotary joints. 
     The link  11  is connected with the base part  20  via the joint JT 1 . A flange surface  161   a  which is an end face of the link  16  constitutes a mechanical interface for connecting it with the end effector  2 . In this embodiment, the flange surface  161   a  is connected to the insulating unit  100 , and therefore, it is indirectly connected with the end effector  2  via the insulating unit  100 . The arm drives D 1 -D 6  use electric power as their power sources. The arm drives D 1 -D 6  each include an electric motor which is a driving source, and a reduction gear which transmits a rotational driving force of the electric motor while decreasing a rotational speed of the electric motor and increasing the rotational driving force of the electric motor. For example, the electric motor may be a servomotor. For example, the arm drive D 6  includes an electric motor M 6  and a reduction gear R 6 . Note that the number of joints of the arm body  10  is not limited to six, but it may be seven or more, or five or less. The arm drive D 6 , the electric motor M 6 , and the reduction gear R 6  are examples of a drive. 
     For example, the joint JT 1  couples a base-end part of the link  11  to the base part  20  so as to be rotatable on a vertical rotation axis perpendicular to the upper surface of the installation part  3 . The joint JT 2  couples a base-end part of the link  12  to a tip-end part of the link  11  so as to be rotatable on a horizontal rotation axis along the upper surface of the installation part  3 . The joint JT 3  couples a base-end part of the link  13  to a tip-end part of the link  12  so as to be rotatable on a horizontal rotation axis. The joint JT 4  couples a base-end part of the link  14  to a tip-end part of the link  13  so as to be rotatable on a rotation axis of the axial center in the longitudinal direction of the link  13 . The joint JT 5  couples a base-end part of the link  15  to a tip-end part of the link  14  so as to be rotatable on a rotation axis in a direction perpendicular to the rotation axis of the link  14 . The joint JT 6  couples a base-end part of the link  16  to a tip-end part of the link  15  so as to be rotatable on a twist rotation axis A 6 . 
     The arm body  10  described above can freely move the position of the link.  16  to an arbitrary three-dimensional position and can freely move the posture of the link  16  to an arbitrary three-dimensional posture, within a range where the arm body  10  can operate. 
     A configuration of the insulating unit  100  and the peripheries of the insulating unit  100  is described.  FIG.  2    is an exploded perspective view illustrating one example of the configuration of the insulating unit  100  according to Embodiment 1.  FIG.  3    is a cross-sectional side view illustrating one example of the configuration of the insulating unit  100  according to Embodiment 1.  FIG.  3    illustrates a cross section including the twist rotation axis A 6 . As illustrated in  FIGS.  2  and  3   , the link  16  includes a tip-end member  161 , and a bolt  162  for fixing the tip-end member  161 . 
     The tip-end member  161  is a member which constitutes the mechanical interface with the end effector  2 , and is connected to the reduction gear R 6  disposed inside a cover  151  of the link  15 . 
     The reduction gear R 6  includes a main body R 61  which includes a reduction gear mechanism therein, an output shaft R 62  of the main body R 61 , and an end flange R 63  connected to the output shaft R 62 . The main body R 61  is connected to a rotation driving shaft of the electric motor M 6  (see  FIG.  1   ), and transmits the rotational driving force transmitted from the electric motor M 6  to the output shaft R 62  in a state where a rotational speed is lowered and the driving force is raised. The output shaft R 62  rotates on the rotation axis A 6  by the rotational driving force. 
     The end flange R 63  is connected to an end of the output shaft R 62  so that it integrally rotates with the output shaft R 62 . The end flange R 63  rotates along the circumferential direction of a circumferential edge of the end flange R 63  centering on the rotation axis A 6 . One principal surface R 63   a  of two principal surfaces of the end flange R 63  exposes outside from the cover  151 , and a plurality of flange fixing holes R 63   b  are formed in the principal surface R 63   a.  In this embodiment, although each flange fixing hole R 63   b  is an internally threaded hole which is threadedly engageable with the bolt  162 , it is not limited to this configuration, but it may be any kind of holes, such as a simple hole, a hole with a key, or a hole with a key groove. 
     The tip-end member  161  is a plate-like member, and, for example, it is a circular flange. A plurality of member fixing holes  161   c  and a plurality of tip-end mounting holes  161   d  are formed in the tip-end member  161 . The plurality of member fixing holes  161   c  are holes for fixing the tip-end member  161  to the end flange R 63  by using the bolts  162 . That is, the plurality of member fixing holes  161   c  are holes for fixing the tip-end member  161  to the arm body  10 . In this embodiment, the number of member fixing holes  161   c  is eight. Each member fixing hole  161   c  is a hole which penetrates the tip-end member  161  between the two principal surfaces  161   a  and  161   b  of the tip-end member  161 . The principal surface  161   a  is a flange surface of the link  16 . Below, both the expressions of “the principal surface  161   a ” and the flange surface  161   a ″ will be used suitably. 
     Each member fixing hole  161   c  includes a counter sinking part in the principal surface  161   a,  and its diameter is partially increased near the principal surface  161   a.  The plurality of member fixing holes  161   c  are disposed so that the positions of the plurality of member fixing holes  161   c  match with the positions of the plurality of flange fixing holes R 63   b.    
     The tip-end member  161  is disposed so that the principal surface  161   b  is adjacent to the principal surface R 63   a  of the end flange R 63 . Further, the bolt  162  is inserted into the member fixing hole  161   c  and the flange fixing hole R 63   b  in this order, and is thrusted into the flange fixing hole R 63   b . Therefore, the tip-end member  161  is fixed to the end flange R 63 , and can rotate on the rotation axis A 6 , together with the end flange R 63 . The rotation axis A 6  is one example of a rotation axis of the robotic arm  1 . The counter sinking part of each member fixing hole  161   c  accommodates the head of the bolt  162  so that the head does not project from the principal surface  161   a.    
     The plurality of the tip-end mounting holes  161   d  are holes for fixing the end effector  2  to the tip-end member  161 . The plurality of the tip-end mounting holes  161   d  may be formed in the tip-end member  161  by the time the robotic arm  1  is shipped, for example, during manufacturing the robotic arm  1 , That is, the plurality of tip-end mounting holes  161   d  are holes for attaching the end effector  2  which are formed. beforehand in the tip-end member  161 . In this embodiment, the number of tip-end mounting holes  161   d  is six. Each tip-end mounting hole  161   d  is formed in the principal surface  161   a  at a position different from the eight member fixing holes  161   c  (in detail, at a position radially outward of the rotation axis A 6  with respect to the eight member fixing holes  161   c ). Although each tip-end mounting hole  161   d  extends toward the principal surface  161   b  from the principal surface  161   a,  it does not reach the principal surface  161   b.  Each tip-end mounting hole  161   d  is an internally threaded hole which is threadedly engageable with a bolt  22  for fixing the end effector  2  and does not penetrate the tip-end member  161 . Note that the tip-end mounting holes  161   d  may penetrate the tip-end member  161 . 
     The end effector  2  includes a fitting part  21  configured to be attached to the tip-end member  161 . The fitting part  21  is a plate-like member, and, for example, it is a flange. A plurality of tool mounting holes  21   c  are formed in the fitting part  21 . In this embodiment, the number of tool mounting holes  21   c  is the same as the number of tip-end mounting holes  161   d,  which is six. Each tool mounting hole  21   c  penetrates the fitting part  21  between two principal surfaces  21   a  and  21   b  of the fitting part  21 . The six tool mounting holes  21   c  are disposed so that the positions of the six tool mounting holes  21   c  match with the positions of the six tip-end mounting holes  161   d , 
     For example, the end effector  2  is disposed at the tip-end member  161  in a state where the principal surface  21   b  of the fitting part  21  is adjacent to the principal surface  161   a  of the tip-end member  161 , and the tool mounting holes  21   c  are aligned with the tip-end mounting holes  161   d  in the direction of the rotation axis A 6 , respectively. The bolt  22  is inserted into the tool mounting hole  21   c  and the tip-end mounting hole  161   d  in this order, and is thrusted into the tip-end mounting hole  161   d.  Therefore, the fitting part  21  may be fixed to the tip-end member  161 . 
     The tip-end member  161  as described above is a structural member of the arm body  10 , and is a reinforcement member having the strength to support the end effector  2 . Further, the tip-end member  161  is a rotatable action member. Such a tip-end member  161  is made of metal, such as iron, having conductivity. 
     The insulating unit  100  includes an intermediate member  200  and a first insulating member  300 . The intermediate member  200  is fixed to the tip-end member  161 , and is configured to be attachable to the end effector  2 . The first insulating member  300  is disposed between the intermediate member  200  and the tip-end member  161 , and is configured to insulate the intermediate member  200  from the tip-end member  161 . 
     In this embodiment, the intermediate member  200  includes a first intermediate member  210  and a second intermediate member  220 . Each of the intermediate members  210  and  220  is a plate-like member, and in this embodiment, it is a disk. 
     The first insulating member  300  is made of material with electrical insulation. In this embodiment, the first insulating member  300  is a plate-like member made of bakelite, and, in detail, is a disk thinner than the intermediate members  210  and  220 . For example, the first insulating member  300  is cloth bakelite or paper bakelite. Note that the material which forms the first insulating member  300  is not limited to bakelite, but it may be any kind of material with electrical insulation. Also the configuration of the first insulating member  300  is not limited to the plate-like configuration, and it may be any configuration as long as it can realize electrical insulation between members on both sides of the first insulating member  300 . For example, the first insulating member  300  may be a film-like member. 
     At least one insertion hole  301  is formed in the first insulating member  300 . In this embodiment, the number of insertion holes  301  is two or more, and, in detail, it is the same as the number of tip-end mounting holes  161   d , which is six. The six insertion holes  301  are disposed so that the positions of the six insertion holes  301  match with the positions of the respective six tip-end mounting holes  161   d.    
     The first insulating member  300 , the first intermediate member  210 , and the second intermediate member  220  are disposed in this order in a direction separating from the tip-end member  161  along the rotation axis A 6 , 
     At least one first mounting hole  211  and at least one third mounting hole  212  are formed in the first intermediate member  210 . In this embodiment, the number of first mounting holes  211  and the number of third mounting holes  212  are two or more. In detail, the number of first mounting holes  211  is the same as the number of tip-end mounting holes  161   d,  which is six, and the number of third mounting holes  212  is eight. Each first mounting hole  211  is a hole for fixing the first intermediate member  210  to the tip-end member  161  by using a bolt  231 . The configuration, such as the nominal diameter and the screw pitch, of the bolt  231  is the same as the bolt  22 . Each third mounting hole  212  is a hole for fixing the second intermediate member  220  to the first intermediate member  210  by using a bolt  232 . The bolt  231  is one example of a first bolt, and the bolt  232  is one example of a. third bolt. 
     Each first mounting hole  211  penetrates the first intermediate member  210  between two principal surfaces  210   a  and  210   b  of the first intermediate member  210 . Each first mounting hole  211  includes, in the principal surface  210   a,  a counter sinking part  211   a  which can accommodate a head  231   a  of the bolt  231 , and its diameter is partially increased near the principal surface  210   a . The six first mounting holes  211  are disposed so that the positions of the six first mounting holes  211  match with the positions of the six tip-end mounting holes  161   d.    
     The eight third mounting holes  212  are formed in the principal surface  210   a  at positions different from the six first mounting holes  211 . In this embodiment, the eight third mounting holes  212  are disposed at positions radially inward of the rotation axis A 6  with respect to the six first mounting holes  211 . Although each third mounting hole  212  extends toward the principal surface  2101 ) from the principal surface  210   a,  it does not reach the principal surface  210   h.  Each third mounting hole  212  is threadedly engageable with the bolt  232 , and is an internally threaded hole which does not penetrate the first intermediate member  210 . Note that the third mounting hole  212  may penetrate the first intermediate member  210 . 
     Here, the insulating unit  100  has, in each first mounting hole  211 , a cylindrical second insulating member  400  which matches with an inner circumferential surface of the first mounting hole  211 . The second insulating member  400  permits insertion of a shank  231   b  of the bolt  231 . The second insulating member  400  is disposed at a part of the first mounting hole  211  other than the counter sinking part  211   a.  Further, the insulating unit  100  has, inside the counter sinking part  211   a  of each first mounting hole  211 , a third insulating member  500 , having an annular plate shape which is the shape of a. washer, corresponding to the bolt  231 . The third insulating member  500  permits insertion of the shank  231   b  of the bolt  231 , but does not permit insertion of the head  231   a  of the bolt  231 . Although the second insulating member  400  and the third insulating member  500  are made of material having electrical insulation, and, for example, they may be made of Bakelite similar to the first insulating member  300 , they are not limited to this configuration. 
     The first intermediate member  210  is disposed at the tip-end member  161  in a state where the principal surface  210   h  is adjacent to the principal surface  161   a  of the tip-end member  161 , and the first mounting holes  211  are aligned with the tip-end mounting holes  161   d  in the direction of the rotation axis A 6 . At this time, the first insulating member  30 ( )is disposed between the first intermediate member  210  and the tip-end member  161  in a state where the insertion holes  301  are aligned with the tip-end mounting holes  161   d  in the direction of the rotation axis A 6 . The third insulating member  500  is disposed inside the counter sinking part  211   a  of the first mounting hole  211  so that the third insulating member  500 , the second insulating member  400  of the first mounting hole  211 , the insertion hole  301 , and the tip-end mounting hole  161   d  are lined up in a single file. The shank  231   b  of the bolt  231  is inserted into the third insulating member  500 , the second insulating member  400 , the insertion hole  301 , and the tip-end mounting hole  161   d  in this order, and is thrusted into the tip-end mounting hole  161   d.    
     Therefore, the first intermediate member  210  is fixed to the tip-end member  161  in a state where the first insulating member  300  is sandwiched between the first intermediate member  210  and the tip-end member  161 . The third insulating member  500  intervenes between the head  231   a  of the bolt  231  and an inner surface of the counter sinking part  212   a  to insulate the head  231   a  from the first intermediate member  210 . The second insulating member  400  intervenes between the shank  231  b of the bolt  231  and the inner circumferential surface of the first mounting hole  211  to insulate the shank  231   b  from the first intermediate member  210 . The insulating members  400  and  500  insulate the bolt  231  from the first intermediate member  210 . The first insulating member  300  intervenes between the first intermediate member  210  and the tip-end member  161  to insulate the first intermediate member  210  from the tip-end member  161 . Note that, as illustrated in  FIG.  3   , a washer may be disposed between the head  231   a  and the third insulating member  500 . The washer reduces interference of the head  231   a  with the third insulating member  500  upon the thrust-in. 
     At least one second mounting hole  221  and at least one fourth mounting hole  222  are formed in the second intermediate member  220 . In this embodiment, the number of second mounting holes  221  and the number of fourth mounting holes  222  are two or more. In detail, the number of second mounting holes  221  is the same as the number of tip-end mounting holes  161   d , which is six. The number of fourth mounting holes  222  is the same as the number of third mounting holes  212 , Which is eight. Each second mounting hole  221  is a hole for fixing the end effector  2  to the second intermediate member  220  by using the bolt  22 , Each fourth mounting hole  222  is a hole for fixing the second intermediate member  220  to the first intermediate member  210  by using the bolt  232 . The bolt  22  is one example of a second bolt. 
     Each second mounting hole  221  is formed in a principal surface  220   a  of two principal surfaces  220   a  and  220   b  of the second intermediate member  220 . Although each second mounting hole  221  extends toward the principal surface  220   b  from the principal surface  220   a,  it does not reach the principal surface  220   b . Each second mounting hole  221  is an internally threaded hole which is threadedly engageable with the bolt  22  and does not penetrate the second intermediate member  220 . Note that the second mounting hole  221  may penetrate the second intermediate member  220 . The configuration of each second mounting hole  221  is the same as the tip-end mounting hole  161   d . The six second mounting holes  221  are disposed so that the positions of the six second mounting holes  221  match with the positions of the six first mounting holes  211 , the six tip-end mounting holes  161   d , and the six tool mounting holes  21   c.    
     In detail, in a state where the second intermediate member  220  is attached to the first intermediate member  210  by using the fourth mounting holes  222  and the bolts  232  (i.e., a state where the second intermediate member  220  is fixed to the first intermediate member  210  and the tip-end member  161 ), the positions of the six second mounting holes  221  are aligned with the positions of the six first mounting holes  211  and the six tip-end mounting holes  161   d.  In more detail, the phase centering on the rotation axis A 6  of the six second mounting holes  221  becomes in agreement with (i.e., the same as) the phase centering on the rotation axis A 6  of the six first mounting holes  211  and the six tip-end mounting holes  161   d.  This phase is a phase in the rotational direction centering on the rotation axis A 6 . Further, a distance from the rotation axis A 6  of the six second mounting holes  221  is the same as a distance from the rotation axis A 6  of the six first mounting holes  211  and the six tip-end mounting holes  161   d.    
     That is, in a state where the second intermediate member  220  is fixed to the first intermediate member  210  and the tip-end member  161 , the first mounting hole  211  and the second mounting hole  221  are disposed so that the phase of the tip-end mounting holes  161   d  centering on the rotation axis A 6  becomes in agreement with the phase of the second mounting holes  221  centering on the rotation axis A 6 . Below; “the phase in the rotational direction centering on the rotation axis A 6 ” and “the phase centering on the rotation axis A 6 ” may also simply be referred to as “the phase.” 
     Each fourth mounting hole  222  penetrates the second intermediate member  220  between the principal surfaces  220   a  and  220   b  of the second intermediate member  220 . The eight fourth mounting holes  222  are disposed so that the positions of the eight fourth mounting holes  222  match with the positions of the eight third mounting holes  212 . 
     The second intermediate member  220  is disposed at the first intermediate member  210  in a state where the principal surface  220   b  is adjacent to the principal surface  210   a  of the first intermediate member  210 , and the fourth mounting holes  222  are aligned with the third mounting holes  212  in the direction of the rotation axis A 6 . Further, the bolt  232  is inserted into the fourth mounting hole  222  and the third mounting hole  212  in this order, and is thrusted into the third mounting hole  212 . Therefore, the second intermediate member  220  is fixed to the first intermediate member  210 . Since the second intermediate member  220  becomes only conductive with the first intermediate member  210 , it is electrically insulated from the tip-end member  161 . 
     As described above, the insulating unit  100  is attached to the tip-end member  161  by fixing the first intermediate member  210 , the second intermediate member  220 , and the first insulating member  300  to the tip-end member  161 . 
     The end effector  2  is attached to the insulating unit  100  attached to the tip-end member  161 . in detail, the end effector  2  is disposed at the tip-end member  161  in a state where the principal surface  21   b  of the fitting part  21  is adjacent to the principal surface  220   a  of the second intermediate member  220 , and the tool mounting holes  21   c  are aligned with the second mounting holes  221  in the direction of the rotation axis A 6 . Further, the bolt  22  is inserted into the tool mounting hole  21   c  and the second mounting hole  221  in this order, and is thrusted into the second mounting hole  221 . Therefore, the fitting part  21  is fixed to the second intermediate member  220 . Since the fitting part  21  is only conductive with the second intermediate member  220  and the first intermediate member  210 , it is electrically insulated from the tip-end member  161 . Therefore, the end effector  2  is attached to the tip-end member  161  in a state where it is electrically insulated from the tip-end member  161 , via the insulating unit  100 . 
     The configuration and the layout of the second mounting holes  221  are similar to the configuration and the layout of the tip-end mounting holes  161   d  of the tip-end member  161 . Thus, various kinds of end effectors  2  may be attached to the second intermediate member  220 , similar to the case where they are attached to the tip-end member  161 . 
     Further, a change in the mechanical interface coordinate system is suppressed between a first case which is a case where the end effector  2  is attached to the second intermediate member  220 , and a second case which is a case where the end effector  2  is directly attached to the tip-end member  161 . 
     The mechanical interface coordinate system is a coordinate system for defining the position and the orientation of the end effector  2  attached to the link  16 . In the mechanical interface coordinate system, a mechanical interface surface which is a surface to which the fitting part  21  of the end effector  2  is attached is a reference, and, for example, the origin of the mechanical interface coordinate system is an intersection of the mechanical interface surface and the rotation axis A 6 , In this case. Zm-axis of the mechanical interface coordinate system is the rotation axis A 6 , Xm-axis and Ym-axis are axes on the mechanical interface surface, where the Xm-axis, the Ym-axis, and the Zm-axis are perpendicular to each other. 
     In the first case, the mechanical interface surface is the principal surface  220   a  of the second intermediate member  220 , and in the second case, the mechanical interface surface is the flange surface  161   a.  Since the phase of the six second mounting holes  221  is the same as the phase of the six tip-end mounting holes  161   d,  the Xm-axis, the Ym-axis, and the Zm-axis of the mechanical interface coordinate system are the same, and the position of the origin of the mechanical interface coordinate system differs in the Zm-axis, between the first case and the second case. Therefore, the change in the mechanical interface coordinate system is reduced between the first case and the second case. 
     Even when the robotic arm  1  is controlled by any of an automatic control, a manual control, and a combination of these controls, the mechanical interface coordinate system is used for the control of the arm body  10  for making the end effector  2  into a desired position and a desired orientation. 
     Between the first case and the second case, the change in the mechanical interface coordinate system set to a control program of the robotic arm  1  is a minor change, such as only a correction of the home position in the Zm-axis direction, or is not necessary. For example, when the insulating unit  100  is attached to the existing robotic arm  1 , required works for the hardware and software are simple and minor. 
     In the insulating unit  100  according to Embodiment 1 described above, in the state where the first insulating member  300  is disposed between the tip-end member  161  and the first intermediate member  210 , the first intermediate member  210  is bolted to the tip-end member  161  and further, the second intermediate member  220  is bolted to the first intermediate member  210 . Moreover, for the bolting to the tip-end member  161 , the tip-end mounting holes  161   d  which are formed in the tip-end member  161  by the time the robotic arm  1  is shipped are used, and therefore, formation of new holes in the tip-end member  161  is not necessary. Further, the change in the structure of the arm body  10 , such as attachment and detachment of the tip-end member  161 , is not necessary. Moreover, the positions of the second mounting holes  221  after the intermediate members  210  and  220  are attached to the tip-end member  161  match with the positions of the tip-end mounting holes  161   d . Therefore, this simple work allows the attachment of the insulating unit  100 , while maintaining the accuracy of the second mounting holes  221  for attaching the end effector  2 . Further, since the first mounting holes  211  and the second mounting holes  221  are disposed at the different members, the bolts  231  for fixing the first intermediate member  210  and the bolts  22  for fixing the end effector  2  are disposed at the same phase, but they do not interfere with each other. 
     Moreover, in the insulating unit  100  according to Embodiment 1, as illustrated in  FIG.  3   , the first insulating member  300  does not project in a direction DB more than the tip-end member  161  and the first intermediate member  210  which are adjacent thereto on both sides in a direction DA of the rotation axis A 6  (in detail, which contact the first insulating member  300  from both sides). Note that the direction DA is a direction in which the tip-end member  161  and the first intermediate member  210  sandwich the first insulating member  300 , and is one example of a first direction. The direction DB is a direction which intersects with the direction DA, and in this embodiment, it is a direction perpendicular to the direction DA, and is one example of a second direction. 
     However, the configuration of the first insulating member  300  is not limited to the configuration described above. For example, the first insulating member  300  may project, in the direction DB, more than at least one of the tip-end member  161  and the first intermediate member  210 , and, as illustrated in  FIG.  4   , it may project more than both the tip-end member  161  and the first intermediate member  210 . Note that  FIG.  4    is a cross-sectional side view illustrating one example of a configuration of Modification 1 of the insulating unit  100  according to Embodiment 1. 
     In detail, in the direction DA, the first insulating member  300  projects in the direction DB more than a part of the tip-end member  161  adjacent to the first insulating member  300  in the direction DA, and a part of the first intermediate member  210  adjacent to the first insulating member  300  in the direction DA. Further, at least a part of the entire circumferential edge of the first insulating member  300  may project in the direction DB as described above, or, as illustrated in  FIG.  4   , the entire circumferential edge of the first insulating member  300  may project in the direction DB as described above. Therefore, it is suppressed that conductive foreign substances accumulate on the circumferential edge of the first insulating member  300  in the direction DB to make the tip-end member  161  conductive with the first intermediate member  210 . 
     Further, when the first insulating member  300  projects in the direction DB more than the tip-end member  161  or the first intermediate member  210 , the first insulating member  300  may project in the direction DB more than the smaller one in the size in the direction DB among the tip-end member  161  and the first intermediate member  210 , and the first insulating member  300  may not project in the direction DB more than the larger one in the size in the direction DB among the tip-end member  161  and the first intermediate member  210 , for example. That is, the three members described above may be configured so that they form a step shape. This also suppresses that the conductive foreign substances accumulate on the circumferential edge of the first insulating member  300 . 
     Further, although in the insulating unit  100  according to Embodiment 1, as illustrated in  FIG.  3   , the first insulating member  300  is disposed between the first intermediate member  210  and the tip-end member  161 , it is not limited to this configuration. For example, as illustrated in  FIG.  5   , the first insulating member  300  may be disposed between the first intermediate member  210  and the second intermediate member  220 .  FIG.  5    is a cross-sectional side view illustrating one example of a configuration of Modification 2 of the insulating unit  100  according to Embodiment 1. 
     In this case, the second insulating member  400  is disposed inside each fourth mounting hole  222  of the second intermediate member  220 , and, in detail, it is disposed at a part of each fourth mounting hole  222  other than a counter sinking part  222   a.  The third insulating member  500  is disposed inside the counter sinking part  222   a  of each fourth mounting hole  222 , and, in detail, it is disposed between the head  232   a  of the bolt  232  inserted into each fourth mounting hole  222  and the inner surface of the counter sinking part  222   a.    
     The insertion hole  301  of the first insulating member  300  is disposed not at the positions of the tip-end mounting holes  161   d,  but at the position which matches with the position of the fourth mounting hole  222 . The number of insertion holes  301  is the same as the number of fourth mounting holes  222 , which is eight. 
     The first insulating member  300  insulates the first intermediate member  210  from the second intermediate member  220 . The second insulating member  400  insulates a shank  232   b  of the bolt  232  from the second intermediate member  220 . The third insulating member  500  insulates the head  232   a  of the bolt  232  from the second intermediate member  220 . Therefore, the insulating unit  100  can insulate the end effector  2  from the tip-end member  161 . In this modification, the first insulating member  300  is disposed between the second intermediate member  220  and the tip-end member  161 , and insulates the second intermediate member  220  from the tip-end member  161 . In  FIG.  5   , the first insulating member  300  does not project in the direction DB more than the first intermediate member  210  and the second intermediate member  220 , but it is not limited to this configuration. The first insulating member  300  may project in the direction DB more than at least one of the first intermediate member  210  and the second intermediate member  220 . 
     Further, although in Embodiment 1 and Modifications 1-2, in the first intermediate member  210 , the plurality of third mounting holes  212  are disposed at the positions radially inward of the rotation axis A 6  with respect to the plurality of first mounting holes  211 , and in the second intermediate member  220 , the plurality of fourth mounting holes  222  are disposed at the positions radially inward attic rotation axis A 6  with respect to the plurality of second mounting holes  221 , they are not limited to this configuration. The third mounting hole  212  and the fourth mounting hole  222  may be disposed at any positions different from the first mounting hole  211  and the second mounting hole  221 , respectively. For example, the third mounting holes  212  and the fourth mounting holes  222  may be disposed so that their phases are shifted to the equivalent positions in the radial direction of the rotation axis A 6 , respectively, or may be disposed at radially-outward positions, with respect to the first mounting hole  211  and the second mounting hole  221 . 
     Embodiment 2 
     An insulating unit  100 A according to Embodiment 2 is described, The insulating unit  100 A according to Embodiment 2 differs from Embodiment 1 in that an intermediate member  200 A is constituted by a single member. Below, for this embodiment, the differences from Embodiment 1 and Modifications 1-2 will mainly be described, and explanation of the similarities to Embodiment 1 and Modifications 1-2 will be omitted suitably. 
       FIG.  6    is an exploded perspective view illustrating one example of a configuration of the insulating unit  1100 A according to Embodiment 2.  FIG.  7    is a cross-sectional side view illustrating one example of the configuration of the insulating unit  100 A according to Embodiment 2. As illustrated in  FIGS.  6  and  7   , the insulating unit  100 A includes the intermediate member  200 A and a first insulating member  300 A. 
     The intermediate member  200 A is a single plate-like member, and in this embodiment, it is a disk. At least one first mounting hole  211 A and at least one second mounting hole  221 A are formed in the intermediate member  200 A. In this embodiment, the number of first mounting holes  211 A is two or more, and, in detail, it is the same as the number of member fixing holes  161   c  of the tip-end member  161 , which is eight. The number of second mounting holes  221 A is two or more, and, in detail, it is the same as the number of tip-end mounting holes  161   d  of the tip-end member  161 , which is six. 
     Each first mounting hole  211 A penetrates the intermediate member  200 A between two principal surfaces  200 Aa and  200 Ab of the intermediate member  200 A. The configuration of each first mounting hole  211 A is similar to the configuration of the fourth mounting hole  222  of the second intermediate member  220  according to Embodiment 1. The eight first mounting holes  211 A are disposed so that the positions of the eight first mounting holes  211 A match with the positions of the eight member fixing holes  161   c.    
     Each second mounting hole  221 A is formed in the principal surface  200 Aa of the intermediate member  200 A. Although each second mounting hole  221 A extends toward the principal surface  200 Ab from the principal surface  200 Aa, it does not reach the principal surface  200 Ab. Each second mounting hole  221 A is an internally threaded hole which is threadedly engageable with the bolt  22  and does not penetrate the intermediate member  200 A. The configuration of each second mounting hole  221 A is similar to the configuration of the second mounting hole  221  of the second intermediate member  220  according to Embodiment 1. 
     The six second mounting holes  221 A are disposed so that the positions of the six second mounting holes  221 A match with the positions of the six tip-end mounting holes  161   d.  In detail, in a state where the intermediate member  200 A is fixed to the tip-end member  161  by using the first mounting holes  211 A and bolts  231 A, the positions of the six second mounting holes  221 A are aligned with the positions of the six tip-end mounting holes  161   d . In more detail, the phase of the six second mounting holes  221 A and the distance of the six second mounting holes  221 A from the rotation axis A 6  are the same as the phase of the six tip-end mounting holes  161   d  and the distance of the six tip-end mounting holes  161   d  from the rotation axis A 6 . That is, in the state where the intermediate member  200 A is fixed to the tip-end member  161 , the first mounting hole  211 A and the second mounting hole  221 A are disposed so that the phase of the second mounting holes  221 A centering on the rotation axis A 6  matches with the phase of the tip-end mounting holes  161   d  centering on the rotation axis A 6 . 
     The first insulating member  300 A has a similar configuration to the first insulating member  300  according to Embodiment 1 except for the number of insertion holes  301 A and the layout of the insertion holes  301 A. The number of insertion holes  301 A is the same as the number of member fixing holes  161   c,  which is eight. The eight insertion holes  301 A are disposed so that the positions of the eight insertion holes  301 A match with the positions of the eight member fixing holes  161   c.    
     The insulating unit  100 A has second insulating member  400 A having a similar configuration to the second insulating member  400  according to Embodiment 1, inside each first mounting hole  211 A. The second insulating member  400 A is disposed at a part of the first mounting hole  211 A other than a counter sinking part  211 Aa. Further, the insulating unit  100 A has a third insulating member  500 A having a similar configuration to the third insulating member  500  according to Embodiment 1, inside the counter sinking part  2111 Aa of each first mounting hole  211 A. 
     The intermediate member  200 A is disposed at the tip-end member  161  in a state where the principal surface  200 Ab is adjacent to the principal surface  161   a  of the tip-end member  161 , and the first mounting holes  211 A are aligned with the member fixing holes  161   c  in the direction of the rotation axis A 6 . At this time, the first insulating member  300 A is disposed between the intermediate member  200 A and the tip-end member  161  in a state where the insertion holes  301 A are aligned with the member fixing holes  161   c  in the direction of the rotation axis A 6 . Note that the bolt  162  which fixes the tip-end member  161  to the end flange R 63  is removed beforehand from the member fixing hole  161   c.  The third insulating member  500 A is disposed inside the counter sinking part  211 Aa, and the third insulating member  500 A, the second insulating member  400 A, the insertion hole  301 A, the member fixing hole  161   c , and the flange fixing hole R 63   b  are lined up in a single file. A shank  231  Ab of a bolt  231 A is inserted into the third insulating member  500 A, the second insulating member  400 A, the insertion hole  301 A, the member fixing hole  161   c,  and the flange fixing hole R 63   b  in this order, and is thrusted into the flange fixing hole R 63   b.  The flange fixing hole R 63   b  is used for fixing the intermediate member  200 A to the tip-end member  161 . 
     Therefore, the intermediate member  200 A is fixed to the tip-end member  161  in a state where the first insulating member  300 A is sandwiched between the intermediate member  200 A and the tip-end member  161 . The third insulating member  500 A insulates a head  231 Aa of the bolt  231 A from the intermediate member  200 A. The second insulating member  400 A insulates the shank  231 Ab of the bolt  231 A from the intermediate member  200 A. The first insulating member  300 A insulates the intermediate member  200 A from the tip-end member  161 . Note that, as illustrated in  FIG.  7   , a washer may be disposed between the head  231 Aa and the third insulating member  500 A. 
     The end effector  2  is attached to the insulating unit  100 A attached to the tip-end member  161 . In detail, the end effector  2  is disposed at the intermediate member  200 A in a state where the principal surface  21   b  of the fitting part  21  is adjacent to the principal surface  200 Aa. of the intermediate member  200 A, the tool mounting holes  21   c  are aligned with the second mounting holes  221 A in the direction of the rotation axis A 6 . Further, the bolt  22  is inserted into the tool mounting hole  21   c  and the second mounting hole  221 A in this order, and is thrusted into the second mounting hole  221 A. Therefore, the fitting part  21  is fixed to the intermediate member  200 A. The fitting part  21  becomes only conductive with the intermediate member  200 A. Therefore, the end effector  2  is attached to the tip-end member  161  via the insulating unit  100 A in a state where it is electrically insulated from the tip-end member  161 . 
     The configuration and the layout of the second mounting holes  221 A are similar to the configuration and the layout of the tip-end mounting holes  161   d.  Thus, various kinds of end effectors  2  may be attached to the intermediate member  200 A similar to the case where they are attached to the tip-end member  161 . 
     Further, the change in the mechanical interface coordinate system is reduced between the first case which is the case where the end effector  2  is attached to the intermediate member  200 A, and the second case which is the case where the end effector  2  is directly attached to the tip-end member  161 . 
     According to the insulating unit  100 A according to Embodiment 2 as described above, similar effects to the insulating unit  100  according to Embodiment 1 are acquired. Further, since the intermediate member  200 A is comprised of a single member, a reduction of the number of components is possible. Moreover, the member fixing holes  161   c  which are formed in the tip-end member  161  by the time the robotic arm  1  is shipped are used for bolting the intermediate member  200 A to the tip-end member  161 , and therefore, the formation of new holes in the tip-end member  161  is not necessary. Further, the positions of the second mounting holes  221 A after the intermediate member is attached  200 A to the tip-end member  161  become in agreement with the positions of the tip-end mounting holes  161   d.  Further, since the first mounting hole  211 A and the second mounting hole  221 A correspond to the member fixing hole  161   c  and the tip-end mounting hole  161   d  which are different holes, respectively, interference between the bolt  231 A and the bolt  22  is suppressed. 
     Further, in this embodiment, although the first insulating member  300 A is configured so that it does not project in the direction DB more than the intermediate member  200 A and the tip-end member  161  which are adjacent thereto (in detail, which contact thereto) on both sides in the direction DA, it is not limited to this configuration. The first insulating member  300 A. may project in the direction DB more than at least one of the intermediate member  200 A and the tip-end member  161 , or may project at at least a part of the circumferential edge of the first insulating member  300 A. 
     Other Embodiments 
     Although examples of the embodiments of the present disclosure are described above, the present disclosure is not limited to the embodiments and the modifications. That is, various modifications and improvements are possible within the scope of the present disclosure. For example, the scope of the present disclosure also includes the resultant of applying various modifications to the embodiments and the modifications, and a mode established by combining the components in the different embodiments and modifications. 
     For example, in the insulating unit according to the embodiments and the modifications, a positioning member for positioning the intermediate member, the insulating member, and the fitting part  21  of the end effector  2  with respect to the tip-end member  161  may be disposed. For example, the positioning member may be a bar-shaped member, such as a pin, which is penetrated into the tip-end member  161 , the intermediate member, the insulating member, and the fitting part  21 . 
     For example, in the insulating unit  100 , at least two pins may be inserted into insertion holes formed in the tip-end member  161 , and the insulating member  300 , the first intermediate member  210 , the second intermediate member  220 , and the fitting part  21  may be disposed so that the pins are inserted into through-holes formed therein, respectively. Further, in the insulating unit  100 A, at least two pins may be inserted into insertion. holes of the tip-end member  161 , and the insulating member  300 A, the intermediate member  200 A, and the fitting part  21  may be disposed so that the pins are inserted into respective through-holes. Therefore, the intermediate member, the insulating member, and the fitting part  21  are positioned with respect to the tip-end member  161  in the rotational direction centering on the rotation axis A 6 . Further, the high-accuracy positioning becomes possible by configuring so that the insertion hole and the through-hole, and the pin closely fit to each other. The pin may be made of material having electrical insulation, and when the pin has conductivity, a member having electrical insulation may be disposed between the insertion hole and the through-hole, and the pin. 
     Note that a single pin may be configured so that it does not pass through all of the tip-end member  161 , the intermediate member, the insulating member, and the fitting part  21 , but it passes through a part of the members. For example, the single pin may be configured so that it only passes through the members among the tip-end member  161 , the intermediate member, and the fitting part  21  which are adjacent to each other in the direction of the rotation axis A 6 , and the pin may be disposed at each of the adjacent members. 
     Further, although in the embodiments and the modifications the robotic arm  1  is the vertical articulated robotic arm, it is not limited to this configuration, and it may be any kind of robotic arm to which the end effector  2  is attachable. For example, the robotic arm  1  may be a robotic arm of a horizontal articulated type, a polar coordinate type, a cylindrical coordinate type, a Cartesian coordinate type, or other types. 
     Further, although in the embodiments and the modifications the bolt which fixes each member is metal and has conductivity, it is not limited to this configuration, and a non-conductive bolt may be used. In this case, the second insulating: members  400  and  400 A and the third insulating: members  500  and  500 A may be omitted. 
     Moreover, examples of the respective aspects of the art of the present disclosure are given as follows. The insulating unit according to one aspect of the present disclosure is an insulating unit disposed so as to intervene between the tip-end member of the robotic arm and the end effector attached to the tip-end member. The insulating unit includes the intermediate member which is fixed to the tip-end member, the end effector is attachable to the intermediate member, and the insulating member which is disposed between the intermediate member and the tip-end member, and insulates the intermediate member from the tip-end member. The intermediate member includes the at least one first mounting hole into which the first bolt for fixing the intermediate member to the tip-end member is inserted, and the at least one second mounting hole into which the second bolt for fixing the end effector to the intermediate member is inserted. The first mounting hole and the second mounting hole are disposed so that, in a state where the intermediate member is fixed to the tip-end member, the positions of the second mounting holes match with the positions of the tip-end mounting holes for attachment of the end effector respectively, and the tip-end mounting holes are formed beforehand in the tip-end member. 
     According to this aspect, the insulating member is attached to the tip-end member by attaching the intermediate member to the tip-end member by using the first bolt in the state where the insulating member is disposed between the tip-end member of the robotic arm and the intermediate member. At this time, since a change in the structure of the robotic arm, such as the attachment and detachment of the tip-end member, is not necessary, and the intermediate member is fixed by being bolted, the attachment work is simple. Further, the positions of the second mounting holes after the intermediate member is attached match with the positions of the tip-end mounting holes of the tip-end member. Therefore, an error between the position and the orientation of the end effector when being attached to the second mounting hole, and the position and the orientation of the end effector when being attached to the tip-end mounting hole is reduced. Therefore, it is possible to attach the insulating member to the robotic arm by the simple work, while maintaining the attaching accuracy of the end effector. 
     In the insulating unit according to the aspect of the present disclosure, the tip-end member may be rotatable about a rotation axis of the robotic arm, and the first mounting hole and the second mounting hole may be disposed so that, in the state where the intermediate member is fixed to the tip-end member, a phase of the second mounting holes centering on the rotation axis matches with a phase of the tip-end mounting holes centering on the rotation axis. 
     According to this aspect, an error between the phase of the end effector when being attached to the second mounting hole of the intermediate member and the phase of the end effector when being attached to the tip-end mounting hole is reduced. Therefore, the attaching accuracy of the end effector in the rotation direction centering on the rotation axis is maintained. 
     In the insulating unit according to the aspect of the present disclosure, the second mounting hole may be a threaded hole that is threadedly engageable with the second bolt and does not penetrate the intermediate member. 
     According to aspect, it is suppressed that the second bolt penetrates the intermediate member to contact and conduct with the tip-end member. Therefore, secure insulation becomes possible. 
     In the insulating unit according to the aspect of the present disclosure, the intermediate member may include the first intermediate member including a third mounting hole and the first mounting hole that is disposed so as to match with the position of the tip-end mounting hole, the first intermediate member being fixed to the tip-end member, and the second intermediate member including the second mounting hole disposed so as to match with the position of the first mounting hole, and the fourth mounting hole disposed so as to match with the position of the third mounting hole, the second intermediate member being fixed to the first intermediate member. The first bolt may be inserted into the first mounting hole and the tip-end mounting hole in order to fix the first intermediate member to the tip-end member. The third bolt may be inserted into the third mounting hole and the fourth mounting hole in order to fix the second intermediate member to the first intermediate member. 
     According to this aspect, the first intermediate member is fixed to the tip-end member by the first bolt inserted into the first mounting hole and the tip-end mounting hole. The second intermediate member is fixed to the first intermediate member by the third bolt inserted into the fourth mounting hole and the third mounting hole. The end effector is fixed to the second intermediate member by the second bolt inserted into the second mounting hole. Therefore, simplified attachment of the first and second intermediate members is possible by utilizing the tip-end mounting hole of the tip-end member. Further, since the first mounting hole and the second mounting hole are disposed at the different members, the interference between the first bolt for fixing the first intermediate member and the second bolt for fixing the end effector is suppressed. 
     In the insulating unit according to the aspect of the present disclosure, the insulating member may be disposed between the first intermediate member and the tip-end member. 
     According to this aspect, the insulating member can insulate the end effector from the robotic arm by insulating the first intermediate member from the tip-end member. 
     In the insulating unit according to the aspect of the present disclosure, the insulating member may be disposed between the first intermediate member and the second intermediate member. 
     According to this aspect, the insulating member is disposed between the first intermediate member and the second intermediate member, that is, they are disposed between the second intermediate member and the tip-end member. The insulating member can insulate the first intermediate member from the second intermediate member, and thus can insulate the second intermediate member from the tip-end member, thereby insulating the end effector from the robotic arm. 
     In the insulating unit according to the aspect of the present disclosure, the tip-end mounting hole may be a threaded hole threadedly engageable with the first bolt, the first mounting hole may be a hole penetrating the first intermediate member, the second mounting hole may be a threaded hole that is threadedly engageable with the second bolt and does not penetrate the second intermediate member, the third mounting hole may be a threaded hole that is threadedly engageable with the third bolt and does not penetrate the first intermediate member, and the fourth mounting hole may be a hole penetrating the second intermediate member. 
     According to this aspect, the first intermediate member is fixed to the tip-end member by being threadedly engaged with the tip-end mounting hole, the second intermediate member is fixed to the first intermediate member by being threadedly engaged with the third mounting hole, and the end effector is fixed to the second intermediate member by being threadedly engaged with the second mounting hole, Therefore, the fixing work of each member and the end effector is simple. Further, it is suppressed that each bolt penetrates the second mounting hole or the third mounting hole to contact the first intermediate member or the tip-end member. 
     In the insulating unit according to the aspect of the present disclosure, the tip-end member may include the tip-end mounting hole, and at least one member fixing hole into which a bolt that fixes the tip-end member to the robotic arm is inserted. The first mounting holes may be disposed so as to match with the positions of the member fixing holes, respectively. The first bolt may be inserted into the first mounting hole and the member fixing hole in order to fix the intermediate member to the tip-end member. 
     According to this aspect, the intermediate member is fixed to the tip-end member by the first bolt inserted into the first mounting hole and the member fixing hole, The intermediate member is fixed to the tip-end member using the member fixing hole different from the tip-end mounting hole. Therefore, interference between the first bolt and the second bolt is suppressed. 
     In the insulating unit according to the aspect of the present disclosure, the first mounting hole may be a hole penetrating the intermediate member. 
     According to this aspect, the intermediate member is fixed to the tip-end member by the first bolt being inserted. Therefore, the fixing work of the intermediate member is simple. 
     In the insulating unit according to the aspect of the present disclosure, the insulating member may project in the second direction more than at least either one of the tip-end member or the intermediate member that are adjacent to the insulating member on both sides of the insulating member in the first direction that is a direction in which the insulating member is sandwiched by the tip-end member and the intermediate member. The second direction may be a direction that intersects with the first direction. 
     According to this aspect, the insulating member projects in the second direction more than at least one of the tip-end member and the intermediate member which are adjacent to the insulating member on both sides thereof. Therefore, it is suppressed that conductive objects accumulate on the edge of the insulating member in the second direction to make the members on the both sides be conductive with each other. 
     In the insulating unit according to the aspect of the present disclosure, the tip-end member may have the surface including the mechanical interface with the end effector, and may be a part of the robotic arm. 
     According to this aspect, the insulating unit can intervene between the surface which constitutes the mechanical interface and the end effector so that they are insulated from each other. 
     In the insulating unit according to the aspect of the present disclosure, the tip-end member may be rotatable about the rotation axis of the robotic arm, and the tip-end member may be connected to the drive that gives the rotational driving force to the tip-end member. 
     According to this aspect, the tip-end member can constitute the operable reinforcement member of the robotic arm. Further, the tip-end member is connected to the drive. The insulating member can insulate the end effector from the drive by insulating such a tip-end member from the end effector. 
     A robot according to one aspect of the present disclosure includes the insulating unit according to the aspect of the present disclosure at the tip-end member of the robotic arm. According to this aspect, the similar effects to the insulating unit according to one aspect of the present disclosure are acquired. 
     Note that all the numbers used above, such as the order and the quantity are illustrated in order to concretely explain the technique of the present disclosure, and the present disclosure is not limited to the illustrated numbers. Further, the connection relationships between the components are illustrated in order to concretely explain the technique of the present disclosure, and the connection relationship which realizes the functions of the present disclosure is not limited to those relationships. 
     Since the scope of the present disclosure is defined by the appended claims rather than the description of this specification so that the present disclosure may be implemented in various ways without departing from the spirit of the essential features, the embodiments are illustrative but are not restrictive. All the modifications of the claims and all the modifications within the scope of the claims, or the equivalents of the claims and the scope of the claims are intended to be encompassed in the appended claims. 
     DESCRIPTION OF REFERENCE CHARACTERS 
       1  Robotic Arm 
       2  End Effector 
       22  Bolt (Second Bolt) 
       100 ,  100 A Insulating Unit 
       161  Tip-end Member 
       161   c  Member Fixing Hole 
       161   d  Tip-end Mounting Hole 
       200 ,  200 A Intermediate Member 
       210  First Intermediate Member 
       211 ,  211 A First Mounting Hole 
       212  Third Mounting Hole 
       220  Second Intermediate Member 
       221 ,  221 A Second Mounting Hole 
       222  Fourth Mounting Hole 
       231 ,  231 A Bolt (First Bolt) 
       212  Bolt (Third Bolt) 
       300 ,  300 A First Insulating Member 
       301 ,  301 A Insertion Hole 
       1000  Robot 
     D 6  Arm Drive (Drive) 
     M 6  Electric Motor (Drive) 
     R 6  Reduction Gear (Drive)