JP2006007152A - Voltage cable, robot arm, coating robot and coating system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a voltage cable with which at least one among flexibility improvement and disconnection prevention can be realized in a robot arm equipped with a voltage cable. <P>SOLUTION: The robot arm has a plurality of arm members 16, 18, a spray gun 28 which is provided inside the top end arm 18 and which is equipped with a power receiving section 26, a voltage generator 24 for supplying high voltage to the power receiving section 26 and the voltage cable 30 for supplying voltage generated by the voltage generator 24 to the power receiving section 26. The voltage cable 30 has a tubular body made of an insulating material and an electrically conductive liquid with which the inside of the tubular body is filled up. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a voltage cable for supplying a voltage generated by a voltage generation unit to a power receiving unit provided at a position separated from the voltage generation unit, a robot arm including the voltage cable, a painting robot, and a painting system.

  In recent years, robots are used for various processes. One example is an electrostatic coating robot (for example, Patent Document 1). In this method, a spray gun is attached to the tip of the robot arm, and the workpiece is coated by spraying paint while driving the robot arm. At this time, in order to negatively charge the paint, a high voltage is supplied to the spray gun from the voltage generator via the voltage cable.

  The voltage generator is usually provided at a position slightly away from the spray gun (for example, inside the robot arm or at the base end). Therefore, the voltage cable connecting the voltage generator and the spray gun is often inserted into the arm of the robot arm.

JP-A-4-90867

  Here, the robot arm needs to take various postures according to the painting position, and is driven at high speed and precisely. At that time, the voltage cable inserted into the arm must be able to move flexibly according to the movement of the arm.

  However, the conventional voltage cable is made of a conductive metal wire such as a copper wire coated with an insulator, and has poor flexibility. In particular, when a high voltage is supplied, a large-diameter conductive metal wire is often used, but there is a case where the flexibility is low and the movement of the robot arm cannot be followed. In addition, torsional stress and tensile stress are intermittently applied to the voltage cable by the movement of the robot arm. Therefore, the voltage cable may be disconnected while the robot arm is repeatedly driven.

  Therefore, an object of the present invention is to provide a voltage cable that can move more flexibly, and a robot arm, a painting robot, and a painting system using the voltage cable. Another object of the present invention is to provide a voltage cable, a robot arm, a painting robot, and a painting system that do not cause disconnection.

  The voltage cable of the present invention is a voltage cable for supplying a voltage generated in the voltage generating unit to a power receiving unit provided at a position separated from the voltage generating unit. And a conductive liquid filled in the liquid crystal.

  In a preferred aspect, the power reception unit moves relative to the voltage generation unit, and the voltage cable is connected to each of the voltage generation unit and the power reception unit. In another preferred embodiment, the tube body has seal portions that are provided at both ends of the tube body and seal the conductive liquid inside the tube body. Desirably, it is provided at both ends of the tube body and has a connector part for connecting the voltage generating part and the power receiving part respectively. The connector part contacts the connector part, and the connector part is electrically connected to the conductive liquid through the seal part. In another preferred embodiment, the tubular body is made of polyester. In another preferred embodiment, the tubular body is made of a fluororesin.

  Another robot arm according to the present invention includes an arm member, a power receiving unit provided at a part of the arm member, a voltage generating unit provided at a position separated from the power receiving unit, and a voltage generated by the voltage generating unit. A robot arm having a voltage cable to be supplied to the power receiving unit, wherein the voltage cable includes a tube made of an insulating material and a conductive liquid filled in the tube.

  In a preferred aspect, the voltage cable is inserted into the arm member. In another preferred aspect, the arm member has one or more joints in the insertion range of the voltage cable.

  Another painting robot according to the present invention is provided with the above-described robot arm, drive means for driving the arm member, and a part of the arm member. The paint robot is charged with the voltage received by the power receiving unit and sprayed. And a painting machine.

  According to the present invention, since the liquid is used as the core wire of the voltage cable, the flexibility can be further improved. As another effect of the present invention, since a liquid that does not cause fatigue failure is used as the core wire of the voltage cable, disconnection can be prevented.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1A shows a conceptual diagram of a voltage cable 30 according to an embodiment of the present invention, and FIG. 1B shows an XX end view in FIG. 1A. The voltage cable 30 is a cable that supplies a voltage generated from the voltage generator 24 to a power receiving unit 26 provided at a position separated from the voltage generator 24. This voltage cable is particularly suitable when the power receiving unit 26 moves relative to the voltage generating device 24, and is a cable that can follow the movement even when the power receiving unit 26 moves relatively.

  The voltage cable 30 includes a tube body 34 and a conductive liquid 36 filled in the tube body 34. The tube body 34 is made of an insulating material and has a voltage resistance enough to withstand the supplied voltage. In addition, it is flexible enough to follow the relative movement of the power receiving unit 26. As a material of the tubular body 34, for example, polyester, fluorine resin, or the like can be used. These materials have excellent solvent resistance and high voltage resistance. In particular, since polyester has high flexibility in addition to these advantages, it can be used more suitably.

  The conductive liquid 36 is a liquid having conductivity and functions as a core wire of the voltage cable 30. The conductivity required by the conductive liquid 36 depends on the voltage value to be supplied, the length of the voltage cable 30, the inner diameter (cross-sectional area) of the tube 34, etc. For example, a relatively low conductivity may be used. As the conductive liquid 36, for example, water containing impurities can be used. Impurities include substances that melt in water and can be ionized, such as NaCl. Moreover, tap water (usually about 100 μS / cm to 200 μS / cm) can also be used as the conductive liquid 36 that is easier to obtain.

  Thus, by using the conductive liquid 36 as the core wire of the voltage cable 30, the flexibility of the voltage cable 30 can be improved. That is, if the core wire is liquid, it can always follow the deformation of the shape of the tubular body 34 that is the container, and the voltage cable 30 can perform various movements. In addition, when the liquid core wire is used, even if the tubular body 34 is curved or bent, the fatigue damage does not occur unlike the metal core wire, and disconnection can be prevented. Therefore, the reliability of the voltage cable 30 can be further improved.

  As shown in FIG. 2, a plurality of tube bodies 34 filled with the conductive liquid 36 may be used in one voltage cable 30. FIG. 2 is an end view of the voltage cable 30 in which a large number of tubes 34 and a conductive liquid 36 are accommodated inside an outer tube 48 that is a sheath.

  At both ends of the voltage cable 30, connector portions (not shown) that connect to the voltage generator 24 and the power receiving portion 26 are provided. The connector portion is made of a conductive metal and is electrically connected to the conductive liquid 36 inside the tube body 34. This electrical connection may be direct or indirect. That is, one end of the connector portion may be in direct contact with the conductive liquid 36 or may be in electrical contact with another member that is in contact with the conductive liquid 36.

  Further, seal members (not shown) are also provided at both ends of the voltage cable 30. The sealing member seals the conductive liquid 36 inside the tube body 34 alone or in cooperation with other members. When sealing alone, at least a part of the sealing member is made of a conductive metal. The conductive metal contacts both the conductive liquid 36 and the connector portion inside the tube body 34, and mediates electrical connection between them. Further, when the conductive liquid 36 is sealed in cooperation with another member, for example, the connector portion, if the other member is in direct contact with the conductive liquid 36, the seal portion is not necessarily directly connected to the conductive liquid 36. It does not have to be in contact. In that case, the seal portion may be made of an insulating material.

  Next, the electrostatic coating system 10 which is a suitable application example of this voltage cable is demonstrated using FIG. FIG. 3 is a schematic configuration diagram of the electrostatic coating system 10. The electrostatic coating system 10 includes a transport base 22 for placing and transporting the workpiece 20 and an electrostatic coating robot 11 for coating the workpiece 20. The conveyance table 22 is a table on which a vehicle body or the like that is the workpiece 20 is placed, and can move according to an instruction from a control device (not shown).

  The electrostatic painting robot 11 includes a robot arm 12 having a plurality of joints. The robot arm 12 is roughly divided into a proximal arm 14 connected to a base 13 installed on the ground, an intermediate arm 16 connected to the proximal arm 14, and a distal arm 18 connected to the intermediate arm 16. Is done. Each arm 14, 16, 18 is provided with a plurality of motors as drive means, and can be moved in multiple directions by driving the motors according to instructions from the control device. This movement is performed at high speed and with precision so that the workpiece 20 can be uniformly coated. In particular, the position and direction of the distal arm 18 greatly affects the position and direction of a spray gun (not shown in FIG. 3), which will be described later, and therefore higher speed than the proximal arm 14 and the intermediate arm 16 is achieved. , Precision is required.

  Both the proximal arm 14 and the intermediate arm 16 have a single joint, and the proximal arm 14 can rotate and rotate, and the intermediate arm 16 can rotate. Here, the turning motion refers to a turning motion centered on the long axis of the arm, and the rotating motion refers to a rotating motion centered on the axis in the short axis direction of the arm. The proximal arm 14 and the intermediate arm 16 move in multiple directions by performing a rotating operation and a turning operation to position the distal arm 18.

  The distal arm 18 is an arm having a plurality of joints. Each joint is provided with a motor, and can rotate and rotate. The tip position and direction of the tip arm 18 can be changed by the movement of the plurality of joints. That is, the distal arm 18 can be bent and twisted by a combination of movements of the joints.

  Inside the robot arm 12, a spray gun 28, a voltage generator 24 that generates a high voltage, and a voltage cable 30 that supplies the generated high voltage to the power receiving unit 26 of the spray gun 28 are provided. This will be described with reference to FIG. FIG. 4 is a schematic diagram showing the internal configuration of the robot arm 12.

  A spray gun 28 is provided inside the distal end of the distal arm 18. The spray gun 28 sprays negatively charged paint to coat the workpiece. Inside the spray gun 28 is provided a power receiving unit 26 that receives a supply of voltage, and the paint is negatively charged by the voltage received by the power receiving unit 26. The negatively charged paint is sprayed by a sprayer provided inside the spray gun 28 and adheres to the workpiece 20 by electrostatic force.

  The voltage generating device 24 that generates a voltage to be supplied to the power receiving unit 26 is provided at a position away from the power receiving unit 26, specifically, at a tip position of the intermediate arm 16. The voltage generator 24 boosts a relatively low voltage (for example, about 24 volts) supplied from an external power source to generate a high voltage (for example, about −90,000 volts).

  The voltage generated by the voltage generator 24 is supplied to the power receiving unit 26 via the voltage cable 30. The voltage cable 30 is a cable in which a conductive liquid 36 is filled in a tube body 34 made of an insulating material (see FIG. 1B). In the present embodiment, tap water is used as the conductive liquid 36. Tap water is used because it is very easy and cheap to obtain. In the present embodiment, a voltage is supplied for charging the paint, and almost no current needs to be transmitted. Therefore, tap water with low conductivity can be used as the core wire of the voltage cable 30.

  Moreover, the tubular body 34 in the present embodiment is made of polyester. The reason why polyester is used is that polyester has high flexibility, voltage resistance, and solvent resistance. The inner diameter of the tube body 34 is large enough to supply the voltage to be supplied. In other words, the inner diameter is such that the resistance value of the voltage cable 30 as a whole is small enough to supply a specified voltage value. Moreover, the outer diameter of the tubular body 34 is large enough to satisfy the required flexibility and voltage resistance. Here, the required flexibility means a degree of flexibility that can follow the movement of the tip arm 18. That is, the voltage cable 30 is inserted into the tip arm 18 and needs to be deformed according to the movement of the tip arm 18. As described above, the distal end arm 18 has a large number of joints and performs bending and turning operations. Therefore, the tubular body 34 needs to be flexible enough to follow the bending and turning operations.

  A connector member 42 and a seal member are provided at both ends of the tube body 34. This will be described with reference to FIG. FIG. 5 is a longitudinal sectional view in the vicinity of the end portion of the tubular body 34.

  The seal member 40 seals the conductive liquid 36 inside the tube body 34 at both ends of the tube body 34. In the present embodiment, the seal member 40 is realized as a rod-shaped member made of a conductive metal. This is inserted into the inside from the end of the tube 34. The diameter of the seal member 40 is slightly larger than the inner diameter of the tube body 34 so that the seal member 40 can be brought into close contact with the inner wall of the tube body 34 when inserted into the tube body 34. The end face of the seal member 40 on the side inserted into the tube body 34 is in contact with the conductive liquid 36 inside the tube body 34, and the conductivity between the seal member 40 and the conductive liquid 36 is ensured.

  The connector members 42 are also provided at both ends of the tube body 34, and are connected to the voltage generator 24 and the power receiving unit 26, respectively. The connector member 42 is made of a conductive metal, and an insertion hole 44 into which the voltage generator 24 or the connector of the power receiving unit 26 is inserted is formed at the center thereof. The connector member 42 is fixed to a seal member 40 protruding from the end of the tube body 34, and is electrically connected to the conductive liquid 36 inside the tube body 34 via the seal member 40. Then, the voltage generator 24 or the power receiving unit 26 is inserted into the insertion hole 44, whereby the voltage generating device 24 and the power receiving unit 26 are electrically connected via the conductive liquid 36.

  The configurations of the connector member 42 and the seal member 40 described here are merely examples, and other configurations are possible as long as electrical connection with the conductive liquid 36 and sealing of the conductive liquid 36 into the tube 34 can be realized. There may be. Therefore, for example, the function of a conductive liquid seal and a connector may be realized by a single member. Moreover, you may improve a sealing performance more by using an elastic body for a part of sealing member. Alternatively, the entire sealing member may be made of an insulating material such as an elastic body, and the connector portion may pass through the elastic body and directly contact the conductive liquid.

  Next, the flow of coating in this electrostatic coating system will be briefly described. When performing electrostatic coating, first, the workpiece 20 is placed on the transport table 22 and placed at a predetermined position. The control device drives the robot arm 12 of the electrostatic coating robot 11 to adjust the position of the spray gun 28 and to spray paint from the spray gun 28. Further, a low voltage is supplied to the voltage generator 24 from an external power source. The voltage generator 24 boosts the supplied low voltage to generate a high voltage. The generated high voltage is supplied to the power receiving unit 26 of the spray gun 28 via the voltage cable 30. The spray gun 28 is sprayed onto the workpiece 20 after the paint is negatively charged by the high voltage received by the power receiving unit 26.

  At this time, the spray gun 28 and consequently the tip arm 18 continue to move at a high speed so that the workpiece 20 can be uniformly coated. Depending on the target position of coating, the tip arm 18 bends or turns a part of the tip arm 18 to adjust the position and direction of the spray gun 28.

  In this case, the voltage cable 30 inserted into the tip arm 18 is moved, bent, or turned according to the movement of the tip arm 18. Here, the voltage cable using the conventional metal core wire is poor in flexibility and sometimes cannot follow the movement of the tip arm 18. Therefore, the moving speed and moving range of the tip arm 18 must be limited according to the flexibility of the voltage cable, and the high speed and precision of the tip arm 18 are reduced.

  On the other hand, in the present embodiment, since the conductive liquid 36 is used as the core wire, it has extremely high flexibility and can easily follow movements such as movement, bending, and turning. Therefore, high-speed and precise driving of the tip arm 18 can be reliably realized. In addition, since the voltage cable 30 according to the present embodiment can withstand a posture such as bending, it is possible to cause the tip arm 18 to take a posture that could not be realized by a conventional metal core wire. Therefore, the moving speed and moving range of the tip arm 18 can be improved.

  Moreover, in the conventional voltage cable, since load, such as a tensile stress and a torsional stress, is repeatedly applied to the metal core wire, there is a possibility that the core wire is broken due to fatigue and disconnection occurs. In particular, the connecting portion between the core wire and the connector member is weak in strength and easily breaks.

  However, in this embodiment, since liquid is used for the core wire, there is no fear of fatigue breakage and disconnection can be prevented. In addition, since the electrical connection between the core wire (conductive liquid 36) and the connector member 42 is realized by the contact between the conductive liquid 36 and the conductive metal, no disconnection occurs.

  As described above, according to the present embodiment, since the conductive liquid is used as the core wire of the voltage cable, the flexibility of the voltage cable can be further improved. Therefore, the moving speed and moving range of the robot arm having the voltage cable can be further improved. Furthermore, disconnection of the core wire can be prevented, and as a result, the reliability of the robot arm can be further improved.

  In the above description, the electrostatic coating robot and the robot arm used therefor are described. However, other robots and robots that supply voltage to the power receiving unit provided at a position separated from the voltage generating unit. You may apply to an arm. In particular, the power receiving unit is suitable for a robot or a robot arm that moves relative to the voltage generation unit or supplies a high voltage.

(A) is a schematic block diagram of the voltage cable which is this Embodiment, (B) is an XX end elevation in (A). It is an end view of the voltage cable which is other embodiment. It is a schematic block diagram of the electrostatic coating system which is embodiment of this invention. It is a figure which shows typically the structure of an electrostatic coating robot arm. It is a cross-sectional view around the connector portion of the voltage cable.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Electrostatic coating system, 11 Electrostatic coating robot, 12 Robot arm, 14 Base end arm, 16 Intermediate arm, 18 End arm, 20 Work piece, 24 Voltage generator, 26 Power receiving part, 28 Spray gun, 30 Voltage cable 34, 36 Conductive liquid, 40 Seal member, 42 Connector member.

Claims (11)

A voltage cable for supplying a voltage generated by the voltage generating unit to a power receiving unit provided at a position separated from the voltage generating unit,
A tube made of an insulating material;
A conductive liquid filled inside the tube;
A voltage cable characterized by comprising: The voltage cable according to claim 1,
The power receiving unit moves relative to the voltage generating unit,
The voltage cable is connected to each of the voltage generation unit and the power reception unit. The voltage cable according to claim 1, further comprising:
A voltage cable having a seal portion provided at both ends of a tubular body and sealing a conductive liquid inside the tubular body. The voltage cable according to claim 3, further comprising:
Provided at both ends of the tube, has a connector part to connect the voltage generating part and the power receiving part,
The seal part is made of a conductive material, and at least a part thereof is in contact with the conductive liquid, and another part is in contact with the connector part.
The voltage cable, wherein the connector portion is electrically connected to the conductive liquid through the seal portion. The voltage cable according to any one of claims 1 to 4,
A voltage cable characterized in that the tube is made of polyester. The voltage cable according to any one of claims 1 to 4,
A voltage cable characterized in that the tubular body is made of a fluorine-based resin. An arm member;
A power receiving unit provided in a part of the arm member;
A voltage generating unit provided at a position separated from the power receiving unit;
A voltage cable for supplying the voltage generated by the voltage generator to the power receiver;
A robot arm having
The voltage cable
A tube made of an insulating material;
A conductive liquid filled inside the tube;
A robot arm characterized by comprising: The robot arm according to claim 7,
The robot arm, wherein the voltage cable is inserted into the arm member. The robot arm according to claim 8, wherein
The arm member has one or more joints in a voltage cable insertion range. The robot arm according to any one of claims 7 to 9,
Driving means for driving the arm member;
A coating machine that is provided in a part of the arm member and charges the paint by the voltage received by the power receiving unit, and sprays the paint.
A painting robot characterized by comprising: A painting system comprising the painting robot according to claim 10.

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