Patent Publication Number: US-7896265-B2

Title: Coating apparatus

Description:
This application is based on and claims the benefit of priority from Japanese Patent Application Nos. 2007-244497, 2007-244499, and 2007-244500, filed on 20 Sep. 2007, the content of which is incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a coating apparatus. Specifically, it relates to a rotary atomization coating apparatus that conducts electrostatic coating by spraying liquid coating from the top of a rotary atomization head to. 
     2. Related Art 
     Conventionally, the rotary atomization coating apparatus is known as, for example, a coating apparatus for coating the body of a vehicle. This rotary atomization coating apparatus supplies electrically-conductive coating (liquid coating) to the rotary atomization head as it rotates the rotary atomization head, applying a high voltage thereto. This leads a liquid coating to be charged, atomized, and then sprayed from the top of the rotary atomization head and thereby conducting electrostatic coating. 
     For example, the above-mentioned coating apparatus is installed at the top of a robot arm and provided with a rotary atomization head, a drive mechanism for rotating this rotary atomization head, and a housing for accommodating these components. Problems to be solved by the invention 
     However, in the structure disclosed in Unexamined Japanese Patent Application, First Publication No. 2006-167518, the coating apparatus is entirely integrates. Accordingly, it is necessary to detach the entire coating apparatus from the robot arm when the coating apparatus is repaired or adjusted. Therefore, it occasionally takes time to repair and adjust the coating apparatus. 
     In addition, a channel is provided in the housing in such a structure. This causes a problem that the inside of the channel is hardly checked. Moreover, the channel is formed in the housing. This causes a problem that the outer diameter and thereby increasing the weight of the entire coating apparatus. 
     Moreover, in the structure disclosed in Unexamined Japanese Patent Application, First Publication No. H10-71345, the top face of the coating apparatus is approximately flat, and two air nozzles are formed thereon. These two air nozzles formed on the approximately-flat top face causes a problem that the direction to which air is ejected from the external air nozzle is unstable whereby the coating pattern is hardly set. 
     Furthermore, in the structure of Unexamined Japanese Patent Application, First Publication No. S58-193752, the external air nozzle is located at the rear side of the internal air nozzle to the coating spray direction, and a step is formed between these two air nozzles. Therefore, the step generates whirlpools in the flow of air ejected from the external air nozzle, whereby back whirlpools occurs to possibly cause a contaminated coating nozzle. 
     A first object of the present invention is to provide a coating apparatus that can facilitate repair and adjustment thereof. In addition, a second object of the present invention is to provide a coating apparatus that can easily check air and coating channels and be reduced in weight. Moreover, a third object of the present invention is to provide a coating apparatus that can easily set a coating pattern and prevent contamination of a coating nozzle. 
     SUMMARY OF THE INVENTION 
     The coating apparatus of the present invention (for example, coating apparatus  1 ) conducts electrostatic coating by supplying liquid coating to the rotary atomization head as this rotary atomization coating apparatus rotates the rotary atomization head, applying a high voltage thereto and thereby charging and atomizing liquid coating and then spraying it from the rotary atomization head (rotary atomization head  21 ). The carting apparatus comprises a body part (for example, body part  10 ); a head part (for example, head part  20 ) detachably installed to the body part; and a connection part (for example, connection ring  50 ) for connecting the body part with the head part, wherein the body part is provide with a cascade (for example, cascade  41 ) that boosts and outputs electric power and a plurality of first channels (for example, tubes  13  and passage  435 ) in which at least one of an optical signal representing the revolutions of the rotary atomization head, air, and coating circulates, the head part is provided with the rotary atomization head, an electric power transmission line (for example, electric power transmission line  26 ) that transmits electric power output from the cascade, and a second channel (for example, passage  202 ). On the connecting face of the body part, at least part of the cascade projects, and an end face of the first channel (for example, third port  433 ) is exposed. On the connecting face of the head part, the electric power transmission line is connected, and an insertion part (for example, cascade insertion part  24 ) in which the projected part of the cascade is inserted is formed, and an end face of the second channel (for example, fourth port  201 ) connected to the end face of the first channel is exposed. 
     According to this invention, the body part and the head part approach each other to fix by connection part. Then, while the projected part of the cascade is inserted in the insertion part to connect the cascade with the electric power transmission line, the end face of one of the first channels is connected to the end face of the second channel. Since the coating apparatus is thus divided into the body part and the head part, the coating apparatus can be easily repaired and adjusted. Even if the coating apparatus is installed on a robot arm, it is not necessary to detach the entire coating apparatus from the robot arm, so that it is possible to detach only the head part, when the coating apparatus is repaired and adjusted. Thus, the electric power output from cascade can be transmitted through the electric power transmission line. In addition, while an optical signal, air, and coating circulating in the first channels circulates to the second channel, those circulating in the second channel to the first channel can be circulated. Since the coating apparatus is thus divided into the body part and the head part, the coating apparatus can be easily repaired and adjusted. Even if the coating apparatus is installed on a robot arm, it is not necessary to detach the entire coating apparatus from the robot arm, so that it is possible to detach only the head part, when the coating apparatus is repaired and adjusted. 
     The coating apparatus of the present invention (for example, coating apparatus  1 ) conducts electrostatic coating by supplying liquid coating to the rotary atomization head as this rotary atomization coating apparatus rotates the rotary atomization head, applying a high voltage thereto and thereby charging and atomizing liquid coating and then spraying it from the rotary atomization head (rotary atomization head  21 ). The coating apparatus comprises a main body (for example, head part  20  and body part  10 ); a rotary atomization head (for example, rotary atomization head  21 ) installed on the top side of the main body; a plurality of channels (for example, tubes  13  and passages  435  and  202 ) extending from the bottom side to the top side of the main body, in the plurality of channels, air and coating circulating, wherein 
     wherein the outer diameter of the central part of the main body is smaller than that of the both end sides thereof, at least parts of the plurality of channels are transparent tubes (for example, tubes  13 ), and the tubes are arranged on the outer peripheral face along the central part of the main body. 
     According to the present invention, since the outer diameter of the central part of the main body is smaller than that of the both end sides thereof, the coating apparatus can be lightened. In addition, at least parts of the plurality of channels are transparent tubes, and these tubes are arranged on the outer peripheral face along the central part of the main body. Thus, air and coating channels can be easily checked by visually checking the situation in these tubes and installing the measuring instrument to these tubes. For example, in the case in which a problem occurs when the coating color of a vehicle is changed, the flow condition of coating can be easily checked by visually checking the tube in which this coating circulates. Moreover, in the case in which a problem regarding coating range control occurs, the flow condition of air can be easily checked by exchanging the tube in which air circulates for the tube to which a measuring instrument is installed. 
     In this case, it is preferable to further provide a cover part (for example, cover part  12 ) that covers the central part of the main body. 
     According to the present invention, the cover part that covers the central part of the main body is provided, whereby contamination of the translucent tube can be prevented while the coating apparatus is driven. On the other hand, when the coating apparatus is checked, the translucent tube can be easily checked by detaching only the cover part. 
     The coating apparatus of the present invention (for example, coating apparatus  1 ) conducts electrostatic coating by supplying liquid coating to the rotary atomization head as this rotary atomization coating apparatus rotates the rotary atomization head, applying a high voltage thereto and thereby charging and atomizing liquid coating and then spraying it from the rotary atomization head (rotary atomization head  21 ). The coating apparatus comprises a first circular air nozzle (for example, a first air nozzle  74 ) formed, surrounding the rotary atomization head; a second circular air nozzle (for example, second air nozzle  75 ) formed, surrounding the first air nozzle and located at the rear side from the first air nozzle to the coating spray direction; and a slope (for example, slope  76 ) stretching from the second air nozzle to the first air nozzle. 
     According to the present invention, the first circular air nozzle is provided, surrounding the rotary atomization head, and the second air nozzle is further provided, surrounding the first air nozzle. In addition, the slope is provided, extending from the second air nozzle to the first air nozzle. Thus, air is ejected forward from the second air nozzle along the slope to generate an air curtain, so that an air ejection direction can be stable, whereby the coating pattern can be easily set. In addition, whirlpools can be prevented from generating in the flow of air, and thereby causing no returning whirlpools of coating, so that the contaminated nozzle part can be prevented. 
     According to this invention, the body part and the head part approach each other to fix by connection part. Then, while the projected part of the cascade is inserted in the insertion part to connect the cascade with the electric power transmission line, the end face of one of the first channels is connected to the end face of the second channel. Thus, the electric power output from cascade can be transmitted through the electric power transmission line. In addition, while an optical signal, air, and coating circulating in the first channels circulates to the second channel, those circulating in the second channel to the first channel can be circulated. Since the coating apparatus is thus divided into the body part and the head part, the coating apparatus can be easily repaired and adjusted. Even if the coating apparatus is installed on a robot arm, it is not necessary to detach the entire coating apparatus from the robot arm, so that it is possible to detach only the head part. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view that shows operation of the coating apparatus according to a first embodiment of the present invention; 
         FIG. 2  is a side view of the coating apparatus according to the first embodiment of the present invention; 
         FIG. 3  is a part enlarged section view of the coating apparatus according to the first embodiment of the present invention; 
         FIG. 4  is a front view of the top flange part of the coating apparatus according to the first embodiment of the present invention; 
         FIG. 5  is a perspective view that describes the procedure for connecting the body part and the head part of the coating apparatus according to the first embodiment of the present invention; 
         FIG. 6  is a perspective view that shows operation of the coating apparatus according to a second embodiment of the present invention; 
         FIG. 7  is a side view of the coating apparatus according to the second embodiment of the present invention; 
         FIG. 8  is a part enlarged section view of the coating apparatus according to the second embodiment of the present invention; 
         FIG. 9  is a perspective view that describes the procedure for detaching the cover part of the coating apparatus according to the second embodiment of the present invention; 
         FIG. 10  is a perspective view that shows a schematic structure of the coating apparatus according to the third embodiment of the present invention; 
         FIG. 11  is a side view of the coating apparatus according to the third embodiment of the present invention; 
         FIG. 12  is a sectional view of the top part of the coating apparatus according to the third embodiment of the present invention; 
         FIG. 13  is a diagram that shows the state in which assist air is ejected by the coating apparatus according to the third embodiment of the present invention; 
         FIG. 14  is a diagram that shows the state in which shaping air is ejected by the coating apparatus according to the third embodiment of the present invention; and 
         FIG. 15  is a diagram for showing a relationship among the ejection amount of shaping air, that of assist air, and the coating pattern diameter according the third embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Each embodiment of the present invention is described in more detail with reference to the accompanying drawings. 
     First Embodiment 
       FIG. 1  is a perspective view that shows operation of the coating apparatus  1  according to a first embodiment of the present invention.  FIG. 2  is a side view of the coating apparatus  1 . The coating apparatus  1  conducts electrostatic coating for a vehicle&#39;s body  2 , and comprises a columnar body  10  installed on the top of a robot arm  3 , a head part  20  detachably installed on the top of this body part  10 , and a connection ring  50  as a connection part that connects the body part  10  with the head part  20 . 
       FIG. 3  is a part enlarged section view of the coating apparatus  1 . The body part  10  is provided with a long main part  11  of the body part to which the tubes  13  as the plurality of first channels are connected, and a cover part  12  that covers the outer peripheral face of the central part of this main part  11  of the body part. 
     The main part  11  of the body part is provided with a base part  30 , a cascade accommodation part  40  installed in this base part  30  and accommodating the cascade  41 . 
     The base part  30  is provided with a discoid bottom part  31 , and a wall part  32  arranged on the outer periphery of this bottom part  31 . A threaded part  33  is provided on the outer peripheral face of the wall part  32 , and a cylindrical holder  34  is threadably mounted on this threaded part  33 . A concave part  35  is formed over the periphery thereof inside the top side of this holder  34 . 
     The cascade accommodation part  40  is in long shape, and a bottom flange part  42  and a top flange part  43 , in the shape of guard, are formed on the bottom side and the top side thereof. 
     A through-hole  44  is formed, being extended from the bottom side to the top face of the cascade accommodation part  40 , and accommodates the cascade  41 . Specifically, the cascade  41  is accommodated, so that a space exists between most of the outer peripheral face of cascade  41  and the inner peripheral wall face of the through-hole  44 . 
     The cascade  41  is connected to a low voltage cable  45  passing through the base part  30  and then extends, and electric power supplied through this low voltage cable  45  is boosted and then output. The top side of this cascade  41  axially projects from the approximate center of the top face of the top flange part  43 , and a cascade cover  46  is installed on the top of this cascade  41 . 
     A first port  401  is provided on the outer peripheral face of the cascade accommodation part  40 , and connected to the above-mentioned tubes  13  through the joints  402 . 
     The bottom flange part  42  is fixed to the base part  30 , sealing the open face of the base part  30 . A plurality of tube insertion holes  421  through which the above-mentioned tubes  13  are inserted are formed in this bottom flange part  42 . 
     A plurality of second ports  431  are provided, being circularly arranged on the bottom face of top flange part  43 . These second ports  431  are connected to the above-mentioned tubes  13  through the joints  432  respectively. In addition, a protrusion  434  is formed on the outer peripheral face of the top flange part  43  over the periphery thereof. 
       FIG. 4  is a front view of the top flange part  43 . The third ports  433  as the end face of one of the first channels are provided on the top face of top flange part  43 , being circularly arranged. These third ports  433  are provided, being evenly exposed to the top face of top flange part  43 , and communicated with the second ports  431  and the first port  401  respectively through the passage  435  as one of the first channels. The second port  431  shown in  FIG. 3  is communicated with the through-hole  44  that accommodates the cascade  41 , and other second ports (not shown) are communicated with the third ports  433 . In addition, a locating pin  436  is provided, projecting on the outer side of the top face of the top flange part  43 . 
     Returning to  FIG. 3 , the connection ring  50  is in a cylindrical shape, and a protrusion  51  is formed over the inner peripheral face along the bottom side of the connection ring  50 . In addition, a threaded part  52  is formed on the inner peripheral face along the top side of the connection ring  50 . The protrusion  51  of the connection ring  50  is latched to the protrusion  434  of the top flange part  43 , whereby the connection ring  50  is restricted to move to a top side, but it is allowed to be rotatable. 
     A plurality of tubes  13  are transparent and pass through the flange face of the robot arm  3  from a light supply source (not shown), a compressed air supply source (not shown), and a coating supply source (not shown), and then extend to the inside of the base part  30 . In addition, these tubes  13  are inserted through to tube insertion holes  421  in the cascade accommodation part  40 , extends along the outer peripheral face in the cascade accommodation part  40 , and are then connected to the second ports  431  and the first port  401 . 
     An optical signal supplied from the light supply source, air supplied from the compressed air supply source, and liquid coating supplied from the coating supply source circulate in these tubes  13  and reach the second ports  431  and then the fourth ports  201  through the passage  435 . In addition, the tube  13  extending from the light supply source accommodates an optical fiber, and an optical signal is transmitted through this optical fiber. 
     The cover part  12  is in a cylindrical shape and is allowed to be divided into two parts along the main part  11  of the body part. Specifically, the cover part  12  is consisting of two half-cylindrical cover pieces  12 A and  12 B. The top edges of the cover pieces  12 A and  12 B are inserted between the inner peripheral face of the connection ring  50  and the outer peripheral face of the top flange part  43  in the main part  11  of the body part. Moreover, the bottom edge of the cover pieces  12 A and  12 B engages with a concave part  35  on the top side of the holder  34  of the main part  11  of the body part. 
     The head part  20  is in an approximate dog-leg shape, in which the top end thereof bends, and is provided with an air motor (not shown), the rotary atomization head  21  rotationally driven by this air motor, a coating supply part (not shown) that supplies coating the rotary atomization head  21 , and an air cap  22  surrounding the rotary atomization head  21  (See  FIG. 2 ). The threaded part  23  is formed on the outer peripheral face along the bottom side of the head part  20 , and the threaded part  52  of the connection ring  50  is threadably mounted on the threaded part  23  of this head part  20 . 
     On the bottom face of the head part  20 , the fourth ports  201  as the end face of the second channel are arranged respectively at the position corresponding to the third ports  433  provided in the top flange part  43  in the body part  10 . These fourth ports  201  are provided, being evenly exposed to the bottom base of the head part  43 , and communicated with the above-mentioned coating supply part, the air motor, the rotation atomization head, and the air cap  22  through the passage  202  as the second channel. 
     Accordingly, an optical signal, air, and liquid coating that have reached to the fourth ports  201  circulate in this passage  202 , and be then supplied to the coating supply part, the air motor, the rotary atomization head  21 , and the air cap  22 . In addition, an optical signal, air, and liquid coating output from the coating supply part, the air motor, the rotary atomization head  21  and then circulating in the passage  202  reaches the fourth ports  201  and then circulate to the passage  435  and the tubes  13 . 
     In addition, a plurality of O rings  204  surrounding the fourth ports  201  respectively are installed on the bottom face of the head part  20 . 
     The passage in which the coating circulates and the passage in which air circulates are connected to the coating supply part. This coating supply part is provided with a coating valve that, by air pressure, opens and shuts the passage in which coating circulates. 
     The air motor is connected to the passage in which air circulates, and the rotary atomization head  21  can be rotated at high speed by supplying air to this air motor. This air motor is further connected to the optical fiber that transmits an optical signal. The revolutions of the air motor are output as an optical signal through this optical fiber. The air cap  22  is connected to the passage in which air circulates. The flow rate of air ejected from the air cap  22  changes by changing the flow rate of air supplied to this air cap  22 , so that the coating range is adjusted. 
     On the bottom face of head part  20 , the cascade insertion part  24  as the insertion part in which the top side of the cascade  41  is inserted and a locating pin insertion hole  203  in which the locating pin  436  is inserted are formed. The connecting terminal  25  of the electric power transmission line  26  is provided on the bottom face of the cascade insertion part  24  and electrically connected to the rotary atomization head  21 . The electric power output from the cascade is transmitted to the rotary atomization head  21  through this electric power transmission line  26 . 
     Hereinafter, operation of the coating apparatus  1  will be explained. First, air is supplied from the air supply source to the air motor to rotate the rotary atomization head  21  at high speed. In addition, current from the low voltage power supply is boosted by the cascade  41  to apply high voltage current to the rotary atomization head  21 . 
     Then, air is supplied to the coating supply part to open the coating valve. The coating is discharged from this coating supply part to the inner circular face of the rotary atomization head  21 , applied with high voltage to be charged, atomized by the centrifugal force of the rotary atomization head  21 , and then sprayed from the rotary atomization head  21  toward a workpiece. Electrostatic coating is conducted in this way. 
     Hereinafter, the procedure for connecting the body part  10  with the head part  20  of the coating apparatus  1  is explained in reference to  FIG. 5 . First, the body part  10  and the head part  20  approach each other, and then the locating pin  436  is inserted in the locating pin insertion hole  203  while the projected part of the cascade  41  is inserted in the cascade insertion part  24 . This leads to determine the relative position of the body part  10  and the head part  20 . 
     Then, by rotating connection ring  50  the threaded part  52  of the connection ring  50  is threadably mounted on the threaded part  23  of the head part  20 . Then, the bottom face of head part  20  abuts the top face of body part  10 , whereby the third ports  433  are connected to the fourth ports  201 . At this point, the O rings  204  installed on the bottom side of head part  20  are firmly attached to the top face of body part  10 , whereby the airtightness between the third ports  433  and the fourth ports  201  is maintained. Meanwhile, the top face of the cascade  41  inserted in the cascade insertion part  24  is connected to the connecting terminal  25  of the cascade insertion part  24 . 
     The present embodiment provides the following effects. (1) The body part  10  and the head part  20  approach each other to be fixed by the connection ring  50 . Then, the projected part of the cascade  41  is inserted in the cascade insertion part  24  to connect the cascade  41  with the connecting terminal  25  of the electric power transmission line, and then the third ports  433  are connected to the fourth ports  201 . Thus, the electric power output from cascade  41  can be transmitted through the electric power transmission line. In addition, an optical signal, air, and coating that circulate in the tubes  13  and the passage  435  can be circulated in the passage  202 , and those that circulate in passage  202  can be circulated in the tubes  13  and the passage  435 . Since the coating apparatus  1  is thus divided into the body part  10  and the head part  20 , the coating apparatus  1  can be easily repaired and adjusted. Even if the coating apparatus  1  is installed on a robot arm 3 , it is not necessary to detach the entire coating apparatus  1  from the robot arm  3 , so that it is possible to detach only the head part  20 , when the coating apparatus  1  is repaired and adjusted. 
     (2) The O rings  204  is installed on the bottom face of the head part  20 , so that the installation condition of the O rings  204  can be easily checked, and the airtightness between the third ports  433  and the fourth ports  201  can be maintained. 
     Second Embodiment 
       FIG. 6  is a perspective view that shows operation of the coating apparatus  1  according to a second embodiment of the present invention.  FIG. 7  is a side view of the coating apparatus  1 . The coating apparatus  1  conducts electrostatic coating for a vehicle&#39;s body  2 , and comprises a body part  10  as a columnar body installed on the top of a robot arm  3 , a head part  20  as a body detachably installed on the top of this body part  10 , and a connection ring  50  connecting the body part  10  with the head part  20 . 
       FIG. 8  is a part enlarged section view of the coating apparatus  1 . The body part  10  is provided with a long main part  11  of the body part to which the tube  13  as the plurality of channels is connected, and a cover part  12  that covers the peripheral face of the central part of this main body part  11  of the body part. 
     The main part  11  of the body part is provided with a base part  30 , a cascade accommodation part  40  installed in this base part  30  and accommodating the cascade  41 . 
     The base part  30  is provided with a discoid bottom part  31 , and a wall part  32  arranged on the outer periphery of this bottom part  31 . A threaded part  33  is provided on the outer peripheral face of the wall part  32 , and a cylindrical holder  34  is threadably mounted on this threaded part  33 . A concave part  35  is formed over the periphery thereof inside the top side of this holder  34 . 
     The cascade accommodation part  40  is in long shape, and a bottom flange part  42  and a top flange part  43 , in the shape of guard, are formed on the bottom side and the top side thereof. As a result, the outer diameter of the central part of the body part  10  is smaller than that of the bottom side and the top side thereof. 
     A through-hole  44  is formed, stretching from the bottom side to the top face of the cascade accommodation part  40 , and accommodates the cascade  41 . Specifically, the cascade  41  is accommodated, so that a space exists between most of the outer peripheral face of cascade  41  and the inner peripheral wall face of the through-hole  44 . 
     The cascade  41  is connected to a low voltage cable  45  passing through the base part  30  and then extends, and electric power supplied through this low voltage cable  45  is boosted and output. The top side of this cascade  41  axially projects from the approximate center of the top face of the top flange part  43 , and a cascade cover  46  is installed on the top of this cascade  41 . 
     A first port  401  is provided on the outer peripheral face of the cascade accommodation part  40 , and this first port  401  is connected to one of the above-mentioned tubes  13  through one of the joints  402 . 
     The bottom flange part  42  is fixed to the base part  30 , sealing the open face of the base part  30 . A plurality of tube insertion holes  421  through which the above-mentioned tubes  13  are inserted are formed in this bottom flange part  42 . 
     A plurality of second ports  431  are provided, being circularly arranged on the bottom face of top flange part  43 . These second ports  431  are connected to the above-mentioned tubes  13  through the joints  432  respectively. In addition, a protrusion  434  is formed over the outer peripheral face of the top flange part  43 . 
     The third ports  433  are provided on the top face of top flange part  43 , being circularly arranged. These third ports  433  are provided, being evenly exposed to the top face of top flange part  43 , and communicated with the second ports  431  and the first port  401  respectively through the passage  435  as a channel. The second port  431  shown in  FIG. 8  is communicated with the through-hole  44  that accommodates the cascade  41 , and other second ports (not shown) are communicated with the third ports  433 . In addition, a locating pin  436  is provided, projecting on the outer side of the top face of the top flange part  43 . 
     The connection ring  50  is in a cylindrical shape, and a protrusion  51  is formed over the inner peripheral face along the bottom side of the connection ring  50 . In addition, a threaded part  52  is formed on the inner peripheral face along the top side of the connection ring  50 . The protrusion  51  of the connection ring  50  is latched to the protrusion  434  of the top flange part  43 , whereby the connection ring  50  is restricted to move to a top side, but it is allowed to be rotatable. 
     A plurality of tubes  13  are transparent and pass through the flange face of the robot arm  3  from a light supply source (not shown), a compressed air supply source (not shown), and a coating supply source (not shown), and then extend to the inside of the base part  30 . In addition, these tubes  13  are inserted through to tube insertion holes  421  in the cascade accommodation part  40 , extends along the outer peripheral face in the cascade accommodation part  40 , and are then connected to the second ports  431  and the first port  401 . 
     An optical signal supplied from the light supply source, air supplied from the compressed air supply source, and liquid coating supplied from the coating supply source circulate in these tubes  13  and reach the second ports  431  and then the fourth ports  201  through the passage  435 . In addition, the tube  13  extending from the light supply source accommodates an optical fiber, and an optical signal is transmitted through this optical fiber. 
     The cover part  12  is in a cylindrical shape and is allowed to be divided into two parts along the main part  11  of the body part. Specifically, the cover part  12  is consisting of two half-cylindrical cover pieces  12 A and  12 B. The top edges of the cover pieces  12 A and  12 B are inserted and sandwiched between the inner peripheral face of the connection ring  50  and the outer peripheral face of the top flange part  43  in the main part  11  of the body part, and it is maintained by this connection ring  50 . Moreover, the bottom edge of the cover pieces  12 A and  12 B engages with a concave part  35  on the top side of the holder  34  of the main part  11  of the body part, and it is maintained by this holder  34 . 
     The head part  20  is in an approximate dog-leg shape, in which the top end thereof bends, and is provided with an air motor (not shown), the rotary atomization head  21  rotationally driven by this air motor, a coating supply part (not shown) that supplies coating to the rotary atomization head  21 , and an air cap  22  surrounding the rotary atomization head  21  (See  FIG. 7 ). The threaded part  23  is formed on the outer peripheral face along the bottom side of the head part  20 , and the threaded part  52  of the connection ring  50  is threadably mounted on the threaded part  23  of this head part  20 . 
     On the bottom face of the head part  20 , the fourth ports  201  are arranged respectively at the position corresponding to the third ports  433  provided in the top flange part  43  in the body part  10 . These fourth ports  201  are provided, being evenly exposed to the bottom base of the head part  43 , and communicated with the above-mentioned coating supply part, the air motor, the rotation atomization head, and the air cap  22  through the passage  202  as a channel. 
     Accordingly, an optical signal, air, and liquid coating that have reached to the fourth ports  201  circulate in this passage  202 , and are then supplied to the coating supply part, the air motor, the rotary atomization head  21 , and the air cap  22 . In addition, an optical signal, air, and liquid coating output from the coating supply part, the air motor, the rotary atomization head  21  and then circulating in the passage  202  reaches the fourth ports  201  and then circulate to the passage  435  and the tubes  13 . 
     In addition, a plurality of O rings  204  surrounding the fourth ports  201  respectively are installed on the bottom face of the head part  20 . 
     The coating supply part is connected to the passage in which the coating circulates and that in which air circulates. This coating supply part is provided with a coating valve that, by air pressure, opens and shuts the passage in which coating circulates. 
     The air motor is connected to the passage in which air circulates, and the rotary atomization head  21  can be rotated at high speed by supplying air to this air motor. This air motor is further connected to the optical fiber that transmits an optical signal. The revolutions of the air motor are output as an optical signal through this optical fiber. The air cap  22  is connected to the passage in which air circulates. The flow rate of air ejected from the air cap  22  changes by changing the flow rate of air supplied to this air cap  22 , so that the coating range is adjusted. 
     The cascade insertion part  24  in which the top side of the cascade  41  is inserted and a locating pin insertion hole  203  in which the locating pin  436  is inserted are formed on the bottom face of head part  20 . The connecting terminal  25  of the electric power transmission line  26  is provided on the bottom face of the cascade insertion part  24  and electrically connected to the rotary atomization head  21 . The electric power output from the cascade is transmitted to the rotary atomization head  21  through this electric power transmission line  26 . 
     Hereinafter, operation of the coating apparatus  1  will be explained. First, air is supplied from the air supply source to the air motor to rotate the rotary atomization head  21  at high speed. In addition, current from the low voltage power supply is boosted by the cascade  41  to apply high voltage current to the rotary atomization head  21 . 
     Then, air is supplied to the coating supply part to open the coating valve. The coating is discharged from this coating supply part to the inner circular face of the rotary atomization head  21 , applied with high voltage to be charged, atomized by the centrifugal force of the rotary atomization head  21 , and then sprayed from the rotary atomization head  21  toward a workpiece. Electrostatic coating is conducted in this way. 
     Hereinafter, the procedure for detaching the cover part  12  from the coating apparatus  1  is explained in reference to  FIG. 9 . First, the holder  34  is rotated to be retreated, whereby retention of the bottom edge of the cover part  12  by the holder  34  is released. Next, after the cover part  12  is moved to the bottom side of the coating apparatus  1 , the top edge of cover part  12  is extracted from between the connection ring  50  and the top flange part  43 , whereby retention of the top edge of the cover part  12  by this connection ring  50  is released. Then, the cover part  12  is divided into the cover pieces  12 A and  12 B. The cover part  12  is detached in this way. 
     The present embodiment provides the following effects. (3) Since the outer diameter of the central part of the main body  11  of the body part is smaller than that of the both end sides thereof, the coating apparatus can be lightened. In addition, at least parts of the plurality of channels are transparent tubes  13 , and the tubes  13  are arranged on the outer peripheral face along the central part of the main body. Thus, air and coating channels can be easily checked without detaching the coating apparatus from the robot arm  3  by visually checking the situation in the tubes  13  and installing the measuring instrument to these tubes. For example, in the case in which a problem occurs when the coating color of a vehicle is changed, the flow condition of coating can be easily checked by visually checking the tube  13  in which this coating circulates. Moreover, in the case in which a problem regarding coating range control occurs, the flow condition of air can be easily checked by exchanging the tube in which air circulates for the tube  13  to which a pressure instrument and a flow instrument is installed. 
     (4) The cover part  12  that covers the central part of the main body  11  of the body part is provided, whereby contamination of the tube  13  can be prevented while the coating apparatus is driven. On the other hand, when the coating apparatus  1  is checked, the tube  13  can be easily checked by detaching only the cover part  12 . 
     Third Embodiment 
       FIG. 10  is a perspective view that shows a schematic structure of the coating apparatus  1  according to one embodiment of the present invention.  FIG. 11  is a side view of the coating apparatus  1 . The coating apparatus  1  conducts electrostatic coating for a vehicle&#39;s body  2 , and comprises a columnar body  10  installed on the top of a robot arm  3  and a head part  20  in an approximate dog-leg shape and detachably installed on the top of this body part  10 . 
       FIG. 12  is a sectional view of the top part of the head part  20 . The head part  20  is provided with an air motor  61 , the rotary atomization head  21  rotationally driven by this air motor  61 , the coating supply part (not shown ) that supplies coating to the rotary atomization head  21 , an air cap  22  surrounding the rotary atomization head  21 , and a housing  65  that accommodates these components. 
     The air motor  61  is provided with a cylindrical pivot  63 , a motor housing  64  that maintains this shaft  63  rotatably, wherein the shaft  63  is rotated at high speed by air supplied from the air supply source (not shown). 
     The coating supply part is connected to the passage in which the coating circulates and that in which air circulates. This coating supply part is provided with a coating valve that, by air pressure, opens and shuts the passage in which coating circulates. The coating valve is opened and shut by changing the pressure of air supplied to this coating supply part to adjust the amount of coating to be supplied to the rotary atomization head  21 . 
     The motor housing  64  is provided with a housing main part  641  surrounding the outer peripheral face of the pivot  63  and an insertion part  642  fixed to this housing main part  641  and inserted through the inside of the pivot  63 . That is, the shaft  63  is held rotatably between the housing main part  641  and the insertion part  642  of the motor housing  64 . 
     The insertion part  642  is provided with a coating supply channel  643  in which coating supplied from the above-mentioned coating supply part circulates and cleaning solution supply channel  644  in which a cleaning solution circulates. The coating supply channel  643  and the cleaning solution supply channel  644  reaches the top of insertion part  642 . 
     The rotary atomization head  21  has an approximate conic shape in which the inner diameter increases toward the top side thereof, and it is installed on the top of the pivot  63 . 
     The air cap  22  is installed on the housing  65 . This air cap  22  is provided with an internal air cap  71  surrounding the rotary atomization head  21 , a shaping air cap  72  surrounding the internal air cap  71 , and an assist air cap  73  surrounding the shaping air cap  72 . 
     The internal air cap  71  is in an approximate cylindrical shape in which the outer diameter decreases toward the top side thereof, and the top of this internal air cap  71  is located adjacent to the top of the rotary atomization head  21 . 
     The shaping air cap  72  is in an approximate cylindrical shape in which the outer diameter decreases toward the top side thereof, and the top of this shaping air cap  72  is located adjacent to the top of the rotary atomization head  21 . A space between the shaping air cap  72  and the internal air cap  71  is the first circular air nozzle  74  surrounding the rotary atomization head  21 . This first air nozzle  74  is located adjacent to the rotary atomization head  21 . 
     A plurality of the first air passages  741  communicated with the first air nozzle  74  is formed in the internal air cap  71 . These first air passages  741  are provided with air from the air supply source (not shown). 
     When air is supplied from the air supply source to the first air passages  741 , this supplied air is ejected from the first air nozzle  74  toward the top edge of the rotary atomization head  21  to be shaping air. 
     Assist air cap  73  surrounds the bottom side of the shaping air cap  72 , and the top of this assist air cap  73  is located on the bottom side of the shaping air cap  72 . A space between assist air cap  73  and shaping air cap  72  is the second circular air nozzle  75  surrounding the first air nozzle  74 . Thus, the second air nozzle  75  is located at the rear side from the first air nozzle  74  to the coating spray direction. The outer peripheral face of the shaping air cap  72  is the slope  76  stretching from the second air nozzle  75  to the first air nozzle  74 . 
     A plurality of second air passages  751  communicated with the second air nozzle  75  is formed in the shaping air cap  72 . These second air passages  751  are provided with air supplied from the air supply source (not shown). 
     When air is supplied from the air supply source to the second air passages  751 , this supplied air is ejected from the second air nozzle  75  along the slope  76  to be assist air. 
     Hereinafter, operation of the above-mentioned coating apparatus  1  will be explained. First, air is supplied from the air supply source to the air motor  61  to rotate the rotary atomization head  21  at high speed. In addition, current (not shown) from the low voltage power supply is boosted to apply high voltage current to the rotary atomization head  21 . 
     Then, air is supplied to the coating supply part to open the coating valve is opened, and thereby supplying coating from this coating supply part to the coating supply channel  643 . Accordingly, coating is discharged from the coating supply channel  643  to the inner circular face of the rotary atomization head  21 , applied with high voltage to be charged, atomized by the centrifugal force of the rotary atomization head  21 , and then sprayed from the rotary atomization head  21  to a workpiece. Electrostatic coating is conducted in this way. 
     At this point, while shaping air is ejected from the first air nozzle  74 , assist air is ejected from the second air nozzle  75 . By adjusting the ejection amount of shaping air and assist air properly, the pattern diameter of the coating pattern is adjusted. 
     For example, when assist air is ejected from the second air nozzle  75 , it narrows the pattern diameter of coating to be sprayed as shown in  FIG. 13 . Accordingly, the pattern diameter of the coating decreases to D 1 . 
     On the other hand, when shaping air is ejected from the first air nozzle  74 , assist air further narrows the pattern diameter of coating to be sprayed as shown in  FIG. 14 . Accordingly, the pattern diameter of the coating decreases to D 2  which is smaller than D 1 . 
     Hereinafter, the combination of the ejection amount of shaping air and assist air is explained.  FIG. 15  is a diagram for showing a relationship among the ejection amount of shaping air, that of assist air, and the coating pattern diameter. In  FIG. 15 , the ejection amount of shaping air increases as it changes from S 0  to S 6 , the ejection amount of the assist air increases as it changes from A 0  to A 7 , and the coating pattern diameter increases as it changes from P 0  to P 10 . 
     When the ejection amount of shaping air and assist air decreases, the pattern diameter increases. On the other hand, when the ejection amount of shaping air and assist air increases, the pattern diameter decreases. 
     Moreover, when the ejection amount of shaping air is small, the influence of the ejection amount of assist air high that the pattern diameter significantly changes in accordance with the ejection amount of assist air. On the other hand, when the ejection amount of shaping air is large, the influence of the ejection amount of assist air is low, and the pattern diameter does not changes too much even if the ejection amount of the assist air is changed. 
     In  FIG. 15 , the area surrounded by solid line is a large diameter area of the coating pattern. By decreasing the coating speed of the coating apparatus and increasing the ejection amount of coating, the coating pattern diameter can be increased. Therefore, the cycle time can be shortened, and the cost can be decreased by reducing the number of coating apparatuses. On the other hand, the area surrounded by dashed-dotted line is a small diameter area of the coating pattern. The film thickness of the coated part can be ensured, and additionally, the waste of materials due to overspraying can be reduced. Therefore, the running cost can be decreased. 
     The present embodiment provides the following effects. (5) The first circular air nozzle  74  is provided, surrounding the rotary atomization head  21 , and the second air nozzle  75  is further provided, surrounding the first air nozzle  74 . In addition, the slope  76  is provided, stretching from the second air nozzle  75  to the first air nozzle  74 . Thus, air is ejected forward from the second air nozzle  75  along the slope  76  to generate an air curtain, so that an air ejection direction can be stable, whereby the coating pattern can be easily set. In addition, whirlpools can be prevented from generating in the flow of air, and thereby causing no returning whirlpools of coating, so that the contaminated nozzle part can be prevented. 
     While preferred embodiments of the present invention have been described and illustrated above, it is to be understood that they are exemplary of the invention and are not to be considered to be limiting. Additions, omissions, substitutions, and other modifications can be made thereto without departing from the spirit or scope of the present invention. Accordingly, the invention is not to be considered to be limited by the foregoing description and is only limited by the scope of the appended claims. While preferred embodiments of the present invention have been described and illustrated above, it is to be understood that they are exemplary of the invention and are not to be considered to be limiting. Additions, omissions, substitutions, and other modifications can be made thereto without departing from the spirit or scope of the present invention. Accordingly, the invention is not to be considered to be limited by the foregoing description and is only limited by the scope of the appended claims.