JP2012045631A - Wiring device for rotary joint of robot - Google Patents

Abstract

PROBLEM TO BE SOLVED: To specify a part where an excess current has flowed regardless of the duration, in a structure using a flexible printed wiring board as wiring between two members that are joined by a rotary joint of a robot.SOLUTION: Extensions 14b, 14c of an FPC board 14 for transmitting electric signals between relatively rotating members of a robot are rejoined, after cut off in an intermediate part, through a substrate 61 on which poly switches 71-74 are loaded and through a substrate 64 on which poly switches 75-78 are loaded. A heat responsive seal 60 is stuck to a connection part on the surface of the extension 14a of the FPC board 14 that is situated away from the poly switches 71-78, wherein a connector 33 is connected with the extension 14a at the connection part. The heat responsive seal 60 is arranged in a manner covering all conductive wires 27. In the heat responsive seal 60, a detection temperature is set so that the heat responsive seal responses to heat generated by the conductive wires 27 when excess current flows on the conductive wires 27.

Description

  The present invention is used for wiring between two members coupled by a rotary joint of a robot, and particularly relates to a wiring device for a rotary joint of a robot using a flexible printed wiring board.

  Industrial robots are configured by sequentially connecting a plurality of arms to a base through rotary joints. Usually, an end effector such as a hand is attached to the wrist which is the tip of the arm. In such industrial robots, cables are provided to supply power to motors that serve as drive sources such as arms and end effectors, and to transmit and receive control signals between the drive sources and the robot controller. The

  As such a cable, a flexible printed wiring board (hereinafter referred to as FPC) is used, and the relative rotation of two members (base and arm, arm and arm, arm and wrist, etc.) is inhibited at the rotating joint. It has been proposed to have a wiring structure that does not. However, the FPC has a drawback that it is weaker than a normal lead wire due to overcurrent due to the fact that a plurality of conductive wires are arranged close to each other and the conductive wires are formed of copper foil or the like. There is.

  For this reason, when an FPC is used, when an overcurrent occurs in the wiring in the robot, there is a possibility that the conductive wire of the FPC through which the overcurrent flows may cause a failure such as disconnection. Higher than when used. As a result, the necessity for performing repairs such as replacement by specifying an FPC including a conductive wire in which an overcurrent has passed becomes higher than when a normal conductive wire is used.

  On the other hand, as a technique for detecting overcurrent, for example, a circuit protection device described in Patent Document 1 can be cited. Patent Document 1 discloses a configuration in which a heat-sensitive paint is applied to the surface of a PTC (Positive Temperature Coefficient) thermistor provided so as to be able to cut off a current flowing through a motor. According to this configuration, the PTC thermistor self-heats when an overcurrent flows through the motor, and the heat-sensitive paint changes color due to the heat. The discoloration is confirmed as a trace of continuous energization of the motor.

Japanese Patent Application Laid-Open No. 10-023655

  Since the PTC thermistor has a small resistance value even in a steady operation state where the temperature is low, a slight amount of heat is generated by the current flowing during the steady state. Therefore, when a highly sensitive paint is used as the heat-sensitive paint applied to the surface of the PTC thermistor, it may be discolored over time by receiving heat in a steady operation state for a long time. When the color change over time is caused in this way, it becomes impossible to leave an energization trace when an important overcurrent occurs. Therefore, in the technique described in the cited document 1, there is only an option of using a low-sensitivity paint as the heat-sensitive paint.

  Patent Document 1 aims to leave an energization trace when an overcurrent flows continuously through a motor, so there is no problem even if a heat-sensitive paint with low sensitivity is used. On the other hand, the overcurrent flowing through the wiring of the robot does not always flow continuously, and for example, the overcurrent may flow for a short time due to the influence of external noise. When a heat-sensitive paint with low sensitivity is used, it may be impossible to leave a trace of an overcurrent that flows for a short time. In a robot, such an overcurrent for a short time can cause a later failure. Therefore, it is necessary to detect an overcurrent that flows only for a short time. For this reason, in order to leave a trace of the overcurrent that has flowed in the wiring in the robot, that is, in order to specify the portion where the overcurrent has flowed in the wiring in the robot, Can not.

  Further, as described above, in current robots, a rotating joint wiring device (retainer) that employs an FPC is used as a cable for transmitting electrical signals between the arms. In such a rotary joint wiring device, there are overlapping portions so that the FPCs form a layer due to the structure. In the portion where the FPC overlaps, a plurality of conductive lines are densely arranged (in the layer direction). When a highly sensitive heat-sensitive paint is simply used for the rotary joint wiring device having such a configuration in consideration of the problems in the cited document 1, the following problems occur. That is, in places where the conductive wires are densely packed, not only the heat-sensitive paint corresponding to the conductive wire through which the overcurrent flows, but also the heat-sensitive paint corresponding to the conductive wire (in the adjacent layer) that exists near the conductive wire. It is difficult to tell which conductive wire has changed the color of the heat-sensitive paint due to heat transfer to the heat. Therefore, when an abnormality such as an overcurrent occurs, it becomes difficult to specify a portion where the overcurrent flows.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a portion where an overcurrent flows in a configuration using a flexible printed wiring board as a wiring between two members coupled by a rotary joint of a robot. It is an object to provide a wiring device for a rotary joint of a robot that can be specified regardless of the duration of the overcurrent.

  According to the first aspect of the present invention, the wiring case includes a cylindrical casing and a core member, and is configured to be combined so that the core member is accommodated on the inner peripheral side of the casing. The housing is attached to one member that rotates relative to the robot. The core member is attached to the other member that rotates relative to the robot. The flexible printed wiring board has a strip shape in which a plurality of conductive wires are arranged, and an intermediate portion thereof is housed in a wiring case so as to be wound around the outer periphery of the core member. With such a configuration, an electric signal can be transmitted between one member and the other member of the robot that rotate relative to each other without hindering the relative rotation.

  Also, one end of the flexible printed wiring board is led out from the core member into one member and connected to the connector without being overlapped like the intermediate portion. The other end portion of the flexible printed wiring board is led out from the housing into the other member and connected to the connector without being overlapped similarly to the one end portion. The heat-sensitive member is a part on a plurality of conductive lines on the surface of the flexible printed wiring board, and is attached to a connection part (one end side or a part on the other end side) with the connector. The heat-sensitive member is configured to be sensitive to heat generated by the conductive wire when an excessive current flows in the conductive wire as compared to the current flowing in the steady operation state of the robot.

  A thermistor having a positive temperature coefficient (PTC thermistor) is provided so as to be interposed in series in a transmission path of an electrical signal transmitted through a conductive wire of a flexible printed wiring board. When the thermistor is heated by overcurrent or overheating, the temperature inside the element rises, and when the element temperature rises above a predetermined detection temperature, the resistance value suddenly increases. That is, the thermistor functions as an overcurrent protection element that limits the overcurrent to a minute value when an overcurrent flows through the conductive wire. As such a thermistor, for example, a polyswitch (registered trademark) which is a polymer PTC thermistor can be used.

  With such a configuration, for example, when an electrical signal transmitted between members is abnormal due to the influence of external noise or a robot controller malfunction, and an excessive current flows in a predetermined conductive line, the conductive line is Temporarily generates heat. Thereby, the part located on the heat-conductive member among heat sensitive members is sensitive. At this time, the overcurrent also flows through the thermistor corresponding to the conductive wire through which the overcurrent flows. As a result, the resistance value of the thermistor increases abruptly, the path through which the overcurrent flows is immediately electrically interrupted, and the heat generation of the conductive line through which the overcurrent flows is reduced. For this reason, it can suppress as much as possible that the part located on the other conductive wire adjacent to the conductive wire by heat_generation | fever of the conductive wire in which the overcurrent flowed among heat sensitive members.

  The intermediate portion of the flexible printed wiring board is wound so as to form a layer in the wiring case. For this reason, the flexible printed wiring board has a portion overlapping in the layer direction at the intermediate portion. If a heat-sensitive member is provided in the overlapped intermediate portion, if the conductive wire of one flexible printed wiring board generates heat, the conductive wire of the other flexible printed wiring board that overlaps it will also be heated. It becomes difficult to specify the part where the current flows. Furthermore, the overlapping portions of the flexible printed wiring boards rub against each other according to the relative rotation between the members, and the heat sensitive member may be sensitive to the frictional heat.

  On the other hand, in this means, the heat sensitive member is attached to the connection portion of the flexible printed wiring board with the connector. Moreover, the flexible printed wiring board of this means is not piled up in each edge part. That is, the heat sensitive member is provided in the connection part with the connector which does not overlap so that a layer may be formed among flexible printed wiring boards. Therefore, according to the present means, even when there is an overlapping portion in the layer direction in the flexible printed wiring board, it is possible to prevent the occurrence of a situation in which it becomes difficult to specify the conductive wire through which the overcurrent flows. The occurrence of a situation in which the heat-sensitive member erroneously responds due to frictional heat can be prevented. Furthermore, an overcurrent energization trace will be confirmed based on the sensitive state of the heat sensitive member attached to the connection portion of the flexible printed wiring board connected to the connector, which is a portion led out of the housing of the wiring case. . For this reason, it becomes possible to easily confirm the overcurrent energization trace without removing the flexible printed wiring board from the wiring case.

  The above-described situation in which an electrical signal is abnormal occurs rarely, for example, once every several years. On the other hand, since the thermistor has a small resistance value even in a steady operation state, a small current continues to flow, and a little heat is generated accordingly. If the heat sensitive member is attached to the surface of the thermistor as in the prior art, the heat sensitive member may be exposed to a slight amount of heat generated by the thermistor in a steady operation state, and may become sensitive over time. . Therefore, in this means, the thermistor is provided at a position separated from the heat sensitive member. As a result, the heat sensitive member is not exposed to the heat generated by the thermistor constantly. Therefore, it is possible to prevent a situation in which an overcurrent that has occurred rarely occurs and the heat-sensitive member has already been sensitized, and it is no longer possible to leave an overcurrent energization trace. Can do.

  As described above, the heat-sensitive member of the present means is not exposed to the heat generated by the thermistor in a steady operation state, and there is no risk of erroneous sensitivity due to the overlap in the layer direction of the flexible printed wiring board. Therefore, a highly sensitive member can be used as the heat sensitive member. If a highly sensitive material is used as the heat-sensitive member, it is possible to leave an energization trace even for a momentary overcurrent. That is, it is possible to specify the portion where the overcurrent flows regardless of the duration of the overcurrent.

  According to the second aspect of the present invention, a plurality of strip-shaped flexible printed wiring boards connected at one end are provided. The plurality of strip-shaped flexible printed wiring boards are not bent from one end to the other end of the flexible printed wiring board having a constant width dimension from one end to the other end. The flexible printed wiring board is formed by making one or more cuts that are equally divided into two or more in the width direction.

  By bending such a plurality of strip-shaped flexible printed wiring boards at a portion close to the connected portion, the plurality of strip-shaped flexible printed wiring boards are arranged so as to overlap each other, thereby allowing the flexible printed wiring board to be overlapped. Is configured. According to such a configuration, the flexible printed wiring board before bending has a long and narrow rectangular band shape, so that there is almost no material loss when the flexible printed wiring board is punched from a flexible printed wiring board of a large sheet. .

  According to the said structure, the part which a some strip-shaped flexible printed wiring board overlaps exists reliably. However, the heat-sensitive member is attached to a connection portion between the one end connected to the flexible printed wiring board and the connector. That is, the heat sensitive member is attached to a portion where a plurality of strip-shaped flexible printed wiring boards do not overlap. For this reason, even if it is the structure of this means in which the part where a plurality of strip-like flexible printed wiring boards overlap certainly exists, the occurrence of the situation where it becomes difficult to specify the conductive wire through which the overcurrent flowed is prevented. In addition, it is possible to prevent the occurrence of a situation in which the heat-sensitive member is erroneously sensitive to frictional heat. Furthermore, it is possible to easily confirm the overcurrent energization trace.

The figure which shows the principal part of the FPC board which shows one Embodiment of this invention Cross-sectional view of a rotary joint wiring device shown together with a rotary joint structure A side view of the outer cover as viewed from the direction of the arrow AA in FIG. Exploded perspective view of wiring device for rotary joint Partial perspective view of a plurality of stacked FPC boards Enlarged cross section of FPC board Sectional drawing which shows the overlapping form of several FPC board Plan view of FPC board before bending Plan view of cut FPC board before bending Plan view of cut and crease line on FPC board before bending The figure which shows the process of bending an FPC board (the 1) The figure which shows the process of bending FPC board (the 2) The figure which shows the process of bending FPC board (the 3) Perspective view of industrial robot

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 14 shows a configuration of a general industrial robot. The robot 1 shown in FIG. 14 is configured as, for example, a six-axis vertical articulated robot. The robot 1 includes a base 2, a shoulder portion 3 supported by the base 2 so as to be rotatable in the horizontal direction, a lower arm 4 rotatably supported by the shoulder portion 3 in the vertical direction, and a lower arm 4. A first upper arm 5 supported rotatably in the vertical direction, a second upper arm 6 supported rotatably by the first upper arm 5, and a vertical direction supported by the second upper arm 6 The wrist 7 is rotatably supported on the wrist 7 and the flange 8 is rotatably supported on the wrist 7 by twisting. An end effector (hand) is attached to the flange 8 which is the arm tip, although not shown.

  As an end effector, in addition to a hand, a camera of a visual inspection device or the like can be considered. A visual inspection device is a device that captures a desired inspection point of a workpiece with a camera, transmits the captured image information to the robot controller, and displays the captured image signal received by the robot controller on the display. The quality of assembly and processing is inspected by visually checking the captured image.

  As described above, the shoulder 3 is on the base 2, the lower arm 4 is on the shoulder 3, the first upper arm 5 is on the lower arm 4, the second upper arm 6 is on the first upper arm 5, and the wrist. 7 is supported by the second upper arm 6 and the flange 8 is supported by the wrist 7 so as to be rotatable by a rotating joint. FIG. 2 shows a rotary joint structure for the second upper arm 6 of the wrist 7 among the rotary joint structures of these parts. In FIG. 2, the second upper arm 6 is configured by covering an arm base frame 9 with a plurality of outer covers 10. A shaft hole 9 a is formed at the tip of the arm base frame 9 of the second upper arm 6. On the other hand, a cylindrical shaft portion 7a protrudes from the wrist 7 side. The shaft portion 7 a is fitted into the shaft hole 9 a of the arm base frame 9 of the second upper arm 6 and is supported by the cross roller bearing 11 so as to be relatively rotatable. The wrist 7 is supported on the second upper arm 6 by such a rotary joint structure so as to be pivotable in the vertical direction. However, the shoulder portion 3, the lower arm 4, the first upper arm 5, and the second upper arm 6 are supported. The rotary joints of other robot elements such as the flange 8 have the same structure.

  The shoulder 3, the lower arm 4, the first upper arm 5, the second upper arm 6, the wrist 7 and the flange 8, which are the above-described pivotable or twistable robot elements, are respectively actuators such as servo motors (see FIG. (Not shown) as a drive source. To supply power to these servo motors, send control signals from the robot controller to the servo motor drive circuit, or send rotation detection signals from the servo motor rotary encoder to the robot controller. A cable (not shown) is passed through the robot from 2 to the wrist 7 at the tip.

  If the end effector attached to the flange 8 is a hand, power is supplied to the servo motor that is the actuator of the hand, and control signals and rotation detection signals are sent and received between the servo motor of the hand and the robot controller. A cable is passed through the robot. When the end effector is a camera of a visual inspection apparatus, a cable for supplying power to the camera or transmitting a captured image signal of the camera to the robot controller is passed through the robot.

  Of the wiring passing through the cable inside the robot, the wiring device 12 for rotating joints shown in FIGS. The rotary joint wiring device 12 of FIGS. 2 to 4 is of the wrist 7 rotary joint, but wiring devices used for other rotary joints have the same configuration. The rotary joint wiring device 12 includes a strip-like long flexible printed wiring board 14 housed in a wiring case 13. Hereinafter, the flexible printed wiring board 14 is referred to as an FPC board 14.

The wiring case 13 of the rotating joint wiring device 12 includes a transparent plastic first cylindrical casing 15 having both sides opened and a transparent plastic first circle integrally formed with a circular core member 16 at the center. It consists of a plate 17 and a second disc 18 which is also made of transparent plastic.
The first disk 17 and the second disk 18 are for closing the open surfaces on both sides of the housing 15. The first disc 17 has a circular fitting protrusion 17 a that fits inside the housing 15. The second disk 18 has an annular fitting rib 18 a that fits outside the housing 15. The second disk 18 is fixed to the core member 16 of the first disk 17 with a screw 19 and integrated with the first disk 17. The integrated first disk 17 and second disk 18 constitute a reel 20 having a core member 16 at the center.

  When the reel 20 is formed by integrating the first disc 17 and the second disc 18, the circular fitting protrusion 17 a is fitted inside the housing 15 and the annular fitting rib 18 a is arranged in the housing 15. The housing 15 is arranged so as to be sandwiched between the first disc 17 and the second disc 18 so as to be fitted to the outside of the disc. At this time, a slight gap is formed between the housing 15 and the first disk 17 and the second disk 18, so that the housing 15 and the reel 20 are relatively moved. The wiring case 13 is constructed so as to be rotatable.

  An arc-shaped holding groove 16a is formed in the core member 16 located at the center of the wiring case 13, and a stopper 21 is fitted in the holding groove 16a. On the other hand, a slit 15a is formed in the housing 15 so as to draw an arc from its inner peripheral surface to its outer peripheral surface. The housing 15 is formed with a deep groove 15b extending from the slit 15a to the opposite side in one direction. The deep groove 15 b has a distal end portion whose outer peripheral side surface portion is opened outward on the outer peripheral surface of the housing 15, and a bottom surface portion is also opened outward on the end surface of the housing 15.

  Two annular ribs 17b and 17c having different large and small diameters are formed concentrically with the core member 16 on the inner surface of the first disk 17 (the surface constituting the inner surface of the wiring case 13). An annular groove-like portion sandwiched between the annular ribs 17 b and 17 c is used as a guide path 22. A plurality of radial ribs 17 d extending radially from the core member 16 are formed on the inner surface of the first disc 17. The radial ribs 17d are not formed in the guide path 22.

  A sliding aid 23 is disposed in the wiring case 13. The sliding assist device 23 is based on a plastic rotating plate 24 formed in an end ring shape. A protrusion 24 a is provided on one surface of the front and back surfaces of the rotating plate 24. A plurality of support shafts 24b are erected on the other surface of the rotary plate 24 in a line along the arc of the rotary plate 24, and the roller 25 is rotatable on the support shaft 24b. It is supported. At this time, by setting the outer diameter of the roller 25 to be larger than the width of the rotating plate 24, the roller 25 protrudes outward from both inner and outer peripheral edges of the rotating plate 24.

  Further, a protective column 26 having an arc concave surface 26a on the surface facing the other end is erected near one end of the surface on which the support shaft 24b of the rotating plate 24 is erected. The protective column 26 is narrower than the width of the rotating plate 24, and is provided at a position that is set to, for example, about half the width of the rotating plate 24 and is biased toward the outer peripheral edge of the rotating plate 24. Here, a roller 25 is located at the other end of the rotating plate 24 opposite to the end where the protective column 26 is erected, and the roller 25 is located outward from the other end of the rotating plate 24. It protrudes.

  In this way, the sliding assist device 23 in which the plurality of rollers 25 are arranged on the rotating plate 24 slidably fits the protrusion 24a of the rotating plate 24 into the guide path 22 of the first disc 17. And stored in the wiring case 13. The protrusion 24 a of the rotating plate 24 is slidably fitted into the guide path 22, so that the sliding assist device 23 can rotate around the core member 16 around the core member 16. Yes.

  As shown in FIG. 5, a plurality of FPC boards 14 are stacked and accommodated in the wiring case 13. In addition, as shown in FIGS. 6A and 6B, the FPC board 14 is formed of a plastic film, such as a polyimide film 28, on which a plurality of conductive wires 27 are formed. It has a basic structure in which a polyimide film 29 is bonded with an adhesive 30. The conductive line 27 is used as a power supply line or a signal line. In this case, the FPC board 14 includes a power FPC board 14-1 in which the conductive line 27 is used as the power line 27-1, as shown in FIG. 6A, and a conductor as shown in FIG. 6B. There are two types of signal FPC boards 14-2 that are used as signal lines 27-2. The power line 27-1 and the signal line 27-2 are the same in thickness, and the signal line 27-2 is narrower than the power line 27-1 in terms of line width. Further, although the number of power supply lines 27-1 and signal lines 27-2 is four each in FIG. 6, more lines may be formed.

  In the present embodiment, the power FPC board 14-1 is used for supplying power to a servo motor which is an actuator (drive source) for the wrist 7 and the flange 8, and for supplying power to an end effector. ing. The signal FPC board 14-2 is used for transmitting and receiving signals between the servo motor and the robot controller and for transmitting and receiving signals between the end effector and the robot controller.

  As the plurality of FPC boards 14, a required number of power FPC boards 14-1 and signal FPC boards 14-2 are used. For example, when three FPC boards 14 are overlapped, one signal FPC board 14-2 is overlapped so as to be sandwiched between two power FPC boards 14-1 (see FIG. 7). A method of manufacturing the three FPC plates 14-1, 14-2, and 14-1 having such a configuration will be described with reference to FIGS.

  First, the three FPC boards 14-1, 14-2, 14-1 are composed of one FPC board 51 (corresponding to a flexible printed wiring board before bending) as shown in FIG. The shape of the FPC board 51 is a long belt-like shape with a constant width dimension from one end to the other end. The FPC plate 51 is formed with regions 51-1, 51-2, and 51-3 corresponding to the three FPC plates 14-1, 14-2, and 14-1, respectively.

  Subsequently, as shown in FIG. 9, from the vicinity of one end portion (the upper end portion in FIG. 9) of the FPC board 51, the region 51-1 corresponding to the power FPC board 14-1 and the power FPC board 14-1 are equivalent. A cut 51a is made at the boundary with the area 51-3, and a cut 51b is made at the boundary between the area 51-3 corresponding to the power FPC board 14-1 and the area 51-2 equivalent to the signal FPC board 14-2. It is processed into a shape like a so-called warm bath. Thereby, the power FPC board 14-1, the signal FPC board 14-2, and the power FPC board 14-1 are formed. Each of the power FPC board 14-1, the signal FPC board 14-2, and the power FPC board 14-1 has a strip shape and a strip shape having the same width.

  Thereafter, as shown in FIG. 13, the power FPC board 14-1 and the signal FPC board 14 are bent by bending each end of the signal FPC board 14-2 and the power FPC board 14-1 on both the left and right sides. -2 and the power FPC board 14-1 are stacked. Hereinafter, this overlapping method will be described in detail.

  First, as shown in FIG. 10, crease lines 51c, 51d, 51e, and 51f are inserted in each end portion of the signal FPC board 14-2 and the power supply FPC board 14-1 on both the left and right sides so as to be easily folded. . Subsequently, as shown in FIG. 11, the left signal FPC board 14-2 is bent along the fold line 51c and extended rightward. Then, as shown in FIG. 12, the bent signal FPC board 14-2 is folded along the fold line 51d so as to overlap the power FPC board 14-1.

  Next, the right power supply FPC board 14-1 is bent along the fold line 51e and extended to the left. Thereafter, as shown in FIG. 13, the bent power supply FPC board 14-1 is bent along the fold line 51f, whereby the signal FPC board 14-2 (and the power supply FPC board 14-1) is Overlay on. Thereby, the FPC board 14 which piled up the three FPC boards 14-1, 14-2, and 14-1 is manufactured.

  As shown in FIG. 4, the power FPC boards 14-1 and 14-1 and the signal FPC board 14-2 have different lengths on the other end side, and the signal FPC board 14-2 has a different length. The power supply FPC plates 14-1 and 14-1 are longer. The power FPC boards 14-1 and 14-1 and the signal FPC board 14-2 are bent at a substantially right angle at a portion 14d on one end side in FIG. 4 to form an extension 14a extending upward. ing. Further, the power FPC plates 14-1 and 14-1 are bent at a substantially right angle at a portion 14e on the other end side downward in FIG. 4 to form an extension portion 14b extending downward. Furthermore, a portion 14f on the other end side of the signal FPC board 14-2 is also bent substantially perpendicularly downward in FIG. 4 to form an extension portion 14c extending downward.

  The bent portions 14 d that are one end portions of the power FPC plates 14-1 and 14-1 and the signal FPC plate 14-2 are connected to a core member 16 that is a relative rotation center portion of the reel 20. Further, the bent portion 14e which is the other end portion of the power FPC plates 14-1 and 14-1 and the bent portion 14f which is the other end portion of the signal FPC plate 14-2 are attached to the casing 15. It is connected.

  Specifically, the bent portions 14 d of the power FPC plates 14-1 and 14-1 and the signal FPC plate 14-2 are inserted into the insertion grooves 21 a of the stoppers 21 fitted to the core member 16. Is retained. On the other hand, the bent portion 14e of the power FPC plates 14-1 and 14-1 is inserted into the slit 15a, and the bent portion 14f of the signal FPC plate 14-2 is inserted into the deep groove 15b continuous with the slit 15a. It is inserted by the whole and is held down by pressers 31 and 32 fixed to the casing 15 so as to close the opening on the outer periphery of the slit 15a and the opening on the outer periphery of the tip of the deep groove 15b.

  As shown in FIG. 3, the FPC plate 14 whose both ends are connected to the core member 16 and the housing 15 in this way is an opening between both ends of the sliding aid 23 in the wiring case 13. And the portion located inside the sliding aid 23 is wound around the outer periphery of the core member 16 a required number of times, and the portion located outside the sliding aid 23 is placed inside the sliding aid 23. It is wound as many times as necessary so that the winding direction is opposite to the winding direction. As described above, the FPC plates 14 having different winding directions on both the inner and outer sides of the sliding assisting device 23 are folded in a U shape at the opening portions between both ends of the sliding assisting device 23. A roller 25 provided at the other end of the rotary plate 24 is located inside the U-shaped portion T (substantially arcuate reversing portion, hereinafter referred to as the folded portion T). Yes.

  As shown in FIG. 4, of the extensions 14 a, 14 b, and 14 c of the FPC board 14, the tip of the extension 14 a at one end connected to the core member 16 is connected to the conductive wire 27 of the FPC board 14. A connector 33 is attached. Moreover, in the connection part of the extension part 14a and the connector 33, the surface of the extension part 14a (surface opposite to the side in contact with the connector 33) has a rectangular heat sensitive seal 60 (corresponding to a heat sensitive member). It is affixed. As shown also in FIG. 1, the heat-sensitive seal 60 is arranged on the surface of the extension portion 14a so as to cover all the conductive lines 27 (power supply line 27-1, signal line 27-2). The heat sensitive seal 60 is arranged in such a direction that its longitudinal direction coincides with the longitudinal direction of the connector 33. That is, the longitudinal direction of the heat-sensitive seal 60 is substantially perpendicular to the direction in which each conductive wire 27 extends.

  The heat sensitive seal 60 notifies the temperature rise by a color change. The heat-sensitive seal 60 is a so-called high-sensitivity type, and changes its color in a short time (for example, about several milliseconds to 1 second) when the temperature exceeds a predetermined detection temperature. The heat sensitive seal 60 is of an irreversible type, and once it changes color, it does not return. The detection temperature of the heat sensitive seal 60 is set so that the heat sensitive seal 60 is sensitive to the heat generated by the conductive wire 27 when an extremely large current (overcurrent) flows in the conductive wire 27 compared with the normal state. With such a configuration, the heat-sensitive seal 60 is not sensitive in the steady operation state of the robot 1, and changes its trace when an abnormality occurs in the robot 1 and an overcurrent flows through a predetermined conductive wire 27. It has come to leave in the form of.

  Of the extensions 14b and 14c at the other end of the FPC board 14 connected to the casing 15, the extension 14b at the other end of the short power FPC board 14-1 held by the slit 15a is in the middle. It is cut near the part. However, the cut portion is connected again via the substrate 61. As shown in FIG. 1, FPC connectors 62 and 63 and polyswitches 71 to 74 are mounted on the board 61. Of the cut portion of the extension portion 14 b, the end portion on the side close to the bent portion 14 e is connected to the FPC connector 62. On the other hand, of the cut portion of the extension portion 14 b, the end portion on the side farther from the bent portion 14 e (the side closer to the tip portion) is connected to the FPC connector 63.

  Each terminal of the FPC connector 62 is connected to each terminal of the FPC connector 63 via a wiring pattern formed on the substrate 61 and the poly switches 71 to 74. With such a configuration, the polyswitches 71 to 74 are interposed in series in the transmission path of the power supply (electrical signal) transmitted through the power supply line 27-1 of the power supply FPC board 14-1. . And the connector 34 is attached to the front-end | tip part (lower end part in FIG. 4) of the extension part 14b.

  Of the extensions 14b and 14c at the other end of the FPC board 14 connected to the casing 15, the extension 14b at the other end of the long signal FPC board 14-2 held at the tip of the deep groove 15b. Is cut at the middle part. However, the cut portion is connected via the substrate 64. As shown in FIG. 1, FPC connectors 65 and 66 and poly switches 75 to 78 are mounted on the board 64. Of the cut part of the extension part 14 c, the end part on the side close to the bent part 14 f is connected to the FPC connector 65. On the other hand, of the cut portion of the extension portion 14c, the end portion on the side farther from the bent portion 14f (the side closer to the tip portion) is connected to the FPC connector 66.

  Each terminal of the FPC connector 65 is connected to each terminal of the FPC connector 66 via a wiring pattern formed on the substrate 64 and poly switches 75 to 78. With such a configuration, the poly switches 75 to 78 are interposed in series in the transmission path of the signal (electric signal) transmitted through the signal line 27-2 of the signal FPC board 14-2. . And the connector 35 is attached to the front-end | tip part (lower end part in FIG. 4) of the extension part 14c.

  The poly switches 71 to 78 are polymer PTC thermistors (thermistors having a positive temperature coefficient). In the poly switches 71 to 78, when heat due to an overcurrent or the like is applied, the temperature inside the element rises, and when the element temperature rises above a predetermined temperature, the resistance value suddenly increases. For this reason, when an overcurrent flows through the conductive wire 27, the polyswitches 71 to 78 limit the overcurrent to a minute value. Moreover, the resistance value change of the polyswitches 71 to 78 is reversible, and returns to the original resistance value when the element temperature decreases. Therefore, the poly switches 71 to 78 function as an overcurrent protection element (fuse) that can be self-recovered (no need to be replaced). For this reason, even if the polyswitches 71 to 78 perform an overcurrent limiting operation due to an overcurrent flowing through the conductive wire 27, the polyswitches 71 to 78 will self-recover after that, leaving a trace of the overcurrent limiting operation. I can't. For this reason, the heat-sensitive seal 60 described above is provided in the present embodiment.

  The extension 14a of the FPC board 14 held by the core member 16 is led out of the wiring case 13 through a slit 18b formed linearly from the outer periphery to the center of the second disk 18. Further, the extended portion 14b of the short power FPC plate 14-1 held in the slit 15a of the housing 15 is outside the wiring case 13 through a portion of the slit 15a that is excluded from being closed by the first disc 17. The extended portion 14c of the long signal FPC board 14-2 that is led out and held at the tip of the deep groove 15b is on the bottom surface side (first disc 17 side) of the tip of the deep groove 15b. The lead is led out of the wiring case 13 from the opening.

  Here, the three FPC boards 14 are not bonded at the portion located in the wiring case 13 and are slidable with respect to each other. As shown in FIG. 3, the length of the non-bonded portion of the FPC plate 14 is the FPC plate positioned outward from the FPC plate 14 positioned inside the U-shaped folded portion T in the open portion of the sliding assist device 23. The FPC plate 14 that is positioned on the outer side in the folded-back portion T is longer than the FPC plate 14 so that the gaps 14 are formed apart from each other.

  The rotating joint wiring device 12 is configured as described above. Here, an example of the assembly procedure of the rotating joint wiring device 12 will be described. First, the first disk 17 is placed on the work table, and the casing 15 is placed on the first disk 17 so as to be fitted to the circular fitting protrusion 17a. Subsequently, the sliding assist device 23 is accommodated in the housing 15 so that the protrusion 24 a of the rotating plate 24 of the sliding assist device 23 is fitted into the guide path 22 of the first disc 17.

  Thereafter, one end of the three FPC plates 14 manufactured as described above is inserted into the insertion groove 21 a of the stopper 21, and the stopper 21 is fitted into the holding groove 16 a of the core member 16. Next, the FPC plate 14 is gently wound around the core member 16 inside the sliding assisting device 23 as many times as necessary, and then the FPC plate 14 is passed through openings between both ends of the sliding assisting device 23 to assist sliding. The inside of the container 23 is taken out from the inside, and then folded back and wound around the outside of the sliding aid 23 with the inside direction and the winding direction reversed, as many times as necessary.

  Subsequently, of the FPC board 14, an extension 14b at the other end of the short power FPC board 14-1 is inserted into the slit 15a of the housing 15 from the outer peripheral side, and the long signal FPC board 14- The extension portion 14c of the other end portion 2 is inserted from the opening on the outer peripheral side of the housing 15 into the inside of the tip portion of the deep groove 15b. Then, a portion from the other end of the short power FPC board 14-1 to the other end of the long signal FPC board 14-2 is inserted into the slit 15a and the deep groove 15b from above. As a result, the extended portions 14b and 14c of the short power FPC board 14-1 and the long signal FPC board 14-2 are led out to the first disk 17 side from the distal ends of the slit 15a and the deep groove 15b, respectively. To the state.

  Subsequently, the second disk 18 is inserted on the housing 15 while inserting the extension portion 14a led upward from the core member 16 into the slit 18b from the outer peripheral side toward the center side. It arrange | positions and the cyclic | annular fitting rib 18a is fitted to the outer periphery of the housing | casing 15. FIG. Finally, the second disk 18 is fixed to the core member 16 with screws 19. As described above, the rotary joint wiring device 12 is assembled.

  Now, as shown in FIG. 2, the wiring case 13 containing the FPC board 14 has the casing 15 attached to a metal holding cylinder 36 and the center of relative rotation of the casing 15 and the reel 20 as the wrist. 7 and the second upper arm 6 are arranged at the rotary joint portion so as to coincide with the center of relative rotation. The flange 36 a of the holding cylinder 36 is fixed to the shaft portion 7 a of the wrist 7 with a screw 37, for example. As a result, the casing 15 is fixed to the wrist 7 (corresponding to one member that rotates relative to the robot) via the holding cylinder 36.

  The wiring case 13 in which the housing 15 is fixed to the shaft portion 7a of the wrist 7 is stored in the cylindrical storage portion 39a of the mounting frame 39 fixed to the arm base frame 9 of the second upper arm 6 by screws 38. ing. The cylindrical storage portion 39a is open at both ends. For example, a T-shaped connecting frame 39b is formed at one end, and the connecting frame 39b is fixed to the core member 16 through the second disk 18 with screws 40. Yes. Thus, the reel 20 is fixed to the second upper arm 6 (corresponding to the other member that rotates relative to the robot) via the connecting frame 39b. The connecting frame 39b is formed with a slit 39c through which the extended portion 14a of the FPC plate 14 led out from the slit 18b of the second disk 18 passes. The outer cover 10 is fixed to the arm base frame 9 and the mounting frame 39 by a plurality of screws 41 so as to cover the mounting frame 39.

  A connector 33 of one extension portion 14a of the FPC board 14 led out from the second disk 18 of the wiring case 13 is fixed to a predetermined portion in the second upper arm 6, and the second upper arm 6 is connected to the connector 33. Cables wired in the arm 6 are connected via connectors (both not shown). Further, the connectors 34 and 35 of the two other extensions 14b and 14c led out from the housing 15 of the wiring case 13 to the first disk 17 side are fixed to predetermined portions in the wrist 7 and the connector 33 The cables wired in the wrist 7 are connected through connectors (none of which are shown).

  As described above, the cable wired in the second upper arm 6 and the cable wired in the wrist 7 are connected via the rotating joint wiring device 12. With such a configuration, an electric signal can be transmitted between one member (wrist 7) and the other member (second upper arm 6) that rotate relative to the robot without hindering the relative rotation. ing.

According to the above configuration, the following operations and effects can be obtained.
For example, when an abnormal electric signal is transmitted between members due to the influence of external noise or a robot controller malfunction, and an excessive current flows through a predetermined conductive line 27, the conductive line 27 temporarily Fever. As a result, a portion of the heat-sensitive seal 60 located on the heat-generating conductive wire 27 is discolored (sensitive). When the above-described abnormality occurs, the user can confirm which conductive wire 27 has passed the overcurrent by confirming the discolored position of the heat-sensitive seal 60. In this way, when an abnormality occurs, it becomes possible to identify the part where the overcurrent has flowed, and it becomes easier to handle the abnormality thereafter (such as repair or replacement of the FPC board 14).

  When the abnormality occurs, the overcurrent also flows through the polyswitches (71 to 78) corresponding to the conductive wires 27 through which the overcurrent flows. As a result, the resistance value of the polyswitch (71 to 78) increases rapidly, and the path through which the overcurrent flows is immediately electrically cut off. For this reason, it can suppress as much as possible that the part located on the other conductive wire 27 adjacent in the plane direction with respect to the conductive wire 27 in which the overcurrent flowed among the heat sensitive seals 60 is sensitive. That is, it is possible to prevent the occurrence of a situation where the part where the overcurrent flows is erroneously specified.

  The FPC board 14 is wound so as to form a layer in the wiring case 13. For this reason, the FPC board 14 has a portion overlapping in the layer direction in a portion (intermediate portion) accommodated in the wiring case 13. If the heat-sensitive seal 60 is provided in this overlapping portion, when the predetermined conductive wire 27 generates heat, the other conductive wire 27 adjacent (overlapping) in the layer direction to the generated conductive wire 27 Since it is heated by heat generation, it becomes difficult to specify the part where the overcurrent flows. Since the thickness of the FPC board 14 is usually thin, in the portion overlapping in the layer direction, the distance between the conductive lines 27 overlapping in the layer direction is larger than the distance between the conductive lines 27 adjacent in the horizontal direction. The distance of is likely to be shorter. For this reason as well, there is a high need to solve the above-mentioned problems associated with the overlapping in the layer direction. Further, the overlapping portions of the FPC plate 14 rub against each other in accordance with the relative rotation between the members, and the heat sensitive seal 60 may be discolored (sensitive) over time due to the frictional heat.

  On the other hand, in the present embodiment, the heat sensitive seal 60 is attached to a connection portion of the FPC board 14 with the connector 33. The FPC board 14 is not overlapped at the end that is the connection portion with the connector 33. That is, the heat-sensitive seal 60 is provided on a portion of the FPC plate 14 that is not overlapped so as to form a layer. Therefore, even if there is a portion where the FPC board 14 accommodated in the wiring case 13 overlaps in the layer direction, it is possible to prevent the occurrence of a situation in which it is difficult to specify the conductive wire 27 in which the overcurrent flows, and Occurrence of a situation in which the heat-sensitive seal 60 is erroneously sensitive to frictional heat can be prevented.

  Furthermore, according to the present embodiment, the FPC board 14 is excessively affected by the sensitivity of the heat-sensitive seal 60 attached to the connection portion with the connector 33 that is a portion led out of the housing 15 of the wiring case 13. The trace of current flow will be confirmed. For this reason, it is possible to easily confirm the overcurrent energization trace without removing the FPC board 14 from the wiring case 13. Therefore, it is possible to increase the efficiency of the work for identifying an abnormal location when an abnormality occurs.

  In the robot 1, a situation where an abnormality occurs in the electrical signal as described above rarely occurs, for example, once every several years. On the other hand, since the poly switches 71 to 78 have a small resistance value even in the steady operation state, a small current continues to flow, and accordingly, heat is slightly generated. If the heat-sensitive seal 60 is attached to the surface of the polyswitches 71 to 78 as in the prior art, the heat-sensitive seal 60 is always exposed to the slight heat generated by the polyswitches 71 to 78 in the steady operation state. There is a risk of discoloration due to aging. Therefore, in the present embodiment, the poly switches 71 to 78 are provided in a place separated from the heat sensitive seal 60. As a result, the heat-sensitive seal 60 is not exposed to the heat constantly generated by the polyswitches 71 to 78. Therefore, when an abnormal situation in which an overcurrent that rarely occurs flows occurs, the heat-sensitive seal 60 has already been discolored (sensitized), and an overcurrent energization trace cannot be left. It can be prevented in advance.

  The heat sensitive seal 60 is of a so-called high sensitivity type that changes color in a short time when a predetermined detection temperature is reached. As described above, the heat-sensitive seal 60 of the present embodiment is not exposed to the heat generated by the polyswitches 71 to 78 in the steady operation state, and is erroneously caused by the overlap in the layer direction of the FPC board 14. There is no risk of discoloration. Therefore, even if a high-sensitivity heat-sensitive seal 60 is used, it is possible to reliably leave an energization trace even for an instantaneous overcurrent without causing discoloration or color change over time. That is, according to the present embodiment, it is possible to specify the portion where the overcurrent flows regardless of the duration of the overcurrent.

  From near one end (the upper end in FIG. 9) of one FPC board 51, an area 51-1 corresponding to the power FPC board 14-1, an area 51-2 corresponding to the signal FPC board 14-2, After forming cuts 51a and 51b at each boundary with the region 51-3 corresponding to the power FPC board 14-1, processing into a so-called warmth shape, the signal FPC boards 14-2 and the power FPC on both the left and right sides By bending each end of the plate 14-1, the power FPC plate 14-1, the signal FPC plate 14-2, and the power FPC plate 14-1 were stacked. According to this configuration, since a single elongated rectangular FPC board 51 is simply punched (cut out) from a large sheet of FPC boards, an elongated belt-like flexible print having T-shaped portions at both ends. Unlike wiring boards, there is almost no material loss.

  According to the said structure, the part with which several strip-shaped FPC board 14-1 and 14-2 overlap exists reliably. However, the heat sensitive seal 60 is attached to the connection portion of the FPC board 14 with the connector 33. Thus, even if it is the structure where the part which several strip-shaped FPC board 14-1 and 14-2 overlap exists reliably, it will become difficult to pinpoint the conductive wire 27 by which the overcurrent flowed by it. The occurrence of a situation in which the heat-sensitive seal 60 erroneously responds due to frictional heat can be prevented.

(Other embodiments)
The present invention is not limited to the embodiment described above and illustrated in the drawings, and the following modifications or expansions are possible.
The heat sensitive seal 60 is arranged so that the longitudinal direction thereof coincides with the longitudinal direction of the connector 33, but the present invention is not limited to this, and the heat sensitive seal 60 and the connector 33 may be arranged so that the longitudinal directions thereof do not coincide. In that case, the heat-sensitive seal 60 is disposed obliquely with respect to the direction in which each conductive wire 27 extends. With such an arrangement, in the heat sensitive seal 60, the area of the portion facing each conductive wire 27 increases, so that more portions become objects to be sensitive to heat generated by the conductive wire 27. According to such a configuration, since heat having a predetermined spread is detected by a larger number of parts, it is possible to more accurately identify which conductive line 27 has passed overcurrent. It becomes possible.

  The mounting position of the heat sensitive seal 60 is a portion on the plurality of conductive wires 27 on the surface of the FPC board 14 and the position shown in FIG. 1 and FIG. It is not limited, and can be changed as appropriate. Alternatively, three heat-sensitive seals may be prepared and disposed on the connection portion (two places) of the FPC board 14 and the connector 34 and the connection portion (one place) of the FPC board 14 and the connector 35, respectively.

The flexible printed wiring board in the present invention means all flat cables whose length in the thickness direction is much shorter than that of a normal cable (which is much thinner than that of a normal cable). A cable (FFC) is also included.
Any flexible printed wiring board may be used as long as it has a belt-like shape in which a plurality of conductive wires for transmitting electrical signals are arranged between the relative rotating members of the robot 1. An FPC plate having a band shape in which there is a mark may be used. In this case, it is necessary to appropriately change the configuration other than the FPC board in the wiring device for rotary joints in accordance with the change of the FPC board. Thus, even when an FPC board that does not have a bent portion is used, the FPC board has a portion that overlaps in the layer direction in the wiring case, so that the same operations and effects as those of the above embodiment are obtained. It is done.

The insertion positions of the substrates 61 and 64 for providing the poly switches 71 to 78 are not limited to the positions shown in FIG. 4, and the poly switches 71 to 78 are connected to the transmission path of the electric signal transmitted through the conductive wire 27. If it is a position which can interpose in series, it can change suitably.
The thermistor having a positive temperature coefficient is not limited to the polyswitches 71 to 78.
The heat sensitive member is not limited to the heat sensitive seal 60 and may be, for example, a heat sensitive paint.
In the above embodiment, the example in which the present invention is applied to the 6-axis vertical articulated robot 1 has been described. However, the present invention can be applied to all robots having rotating joints.

  In the drawings, 1 is a robot, 6 is a second upper arm, 7 is a wrist, 12 is a rotary joint wiring device, 13 is a wiring case, 14 is a flexible printed wiring board, 15 is a housing, 16 is a core member, 27 Are conductive wires, 33 to 35 are connectors, 60 is a heat sensitive seal (heat sensitive member), and 71 to 78 are poly switches (thermistors).

Claims (2)

A cylindrical housing attached to one of the relative rotating members of the robot; and a core member attached to the other of the relative rotating members of the robot; and the core on the inner peripheral side of the housing A wiring case configured in combination so as to accommodate the members;
The robot has a belt-like shape in which a plurality of conductive wires for transmitting electrical signals are arranged between the relative rotating members of the robot, and the intermediate portion is wound around the outer periphery of the core member in the wiring case. A flexible printed wiring board that is led out from the core member into the one member without being overlapped, and is led out from the housing to the other member without being overlapped. ,
Connectors to which one end and the other end of the flexible printed wiring board are respectively connected;
A heat-sensitive member that is a part on the plurality of conductive wires on the surface of the flexible printed wiring board and is attached to a connection portion with the connector;
A thermistor having a positive temperature coefficient provided in series with the electric signal transmission path and spaced apart from the heat-sensitive member;
With
The rotation of the robot, wherein the heat sensitive member is configured to be sensitive to heat generated by the conductive wire when an excessive current flows compared to a current flowing through the conductive wire in a steady operation state. Wiring device for joints. The flexible printed wiring board has a shape with a constant width from one end to the other end, and the flexible printed wiring board before the bending from near one end to the other end of the flexible printed wiring board. A plurality of strip-shaped flexible printed wiring boards formed by making one or more cuts that are evenly divided into two or more in the width direction and having one end connected, the plurality of strip-shaped flexible printed wirings By bending the plate at a portion close to the connected portion, the plurality of strip-shaped flexible printed wiring boards are arranged so as to overlap each other,
2. The wiring device for a rotary joint of a robot according to claim 1, wherein the heat sensitive member is attached to a connection portion between the one end connected to the flexible printed wiring board and the connector.

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