1. Technical Field
The preset invention relates to a managing structure for an umbilical member including a cable and/or a tube connected to a work tool, such as a hand or a welding torch, attached to an industrial robot.
2. Description of the Related Art
Generally, in an industrial robot (hereinafter referred to simply as a robot), a work tool, such as a hand or a welding torch, is attached to an end of a wrist of the robot. Alternatively, a camera or a force sensor may be attached to the end of the wrist of the robot. In this specification, the camera or the sensor attached to the wrist of the robot is also referred as a kind of “a work tool”. Many of the work tools must be supplied with electrical energy, an electrical signal, air, assist gases or a welding wire. Further, a cable and/or a tube are used to supply the work tool. There are many kind of configuration of the cable and/or the tube. For example, a plurality of cables may be collected in one conduit, or, some line elements may be bundled. Also, the conduit or the line elements may be bundled with a servo control cable for controlling a servomotor for driving each axis of the robot. Further, they may constitute a composite cable. In the present specification, the bundled articles is referred to simply as “an umbilical member”.
In the prior art, when such an umbilical member is arranged on the robot and connected to the work tool mounted near an end of a wrist of the robot, the umbilical member is contained in a robot arm before a forearm of the robot. Then, the umbilical member is arranged over the forearm, and toward the end of the wrist, while the umbilical member is supported by a hanger attached to the outside of the robot arm.
Such a managing structure for the umbilical member is widely used for a robot having another tool such as a hand. However, in such a configuration in which the umbilical member is arranged over the forearm of the robot, when the orientation of the work tool is greatly changed by rotation of a wrist axis of the robot, it is difficult to make the motion of the umbilical member stable. As a result, the frequency of the maintenance of the wire or the tube may be increased by the deterioration of the life, or damage to, the wire or the tube. Further, the unstable motion of the umbilical member may cause interference between the umbilical member and a peripheral equipment.
In order to resolve such a problem, a configuration in which the umbilical member is contained in the forearm of the robot is proposed, as in Japanese Unexamined Patent Publication (Kokai) No. 2004-98174, for example. The above problem may be solved by this configuration to some extent, however, a robot must be individually prepared to correspond to an operation of a system using the robot, whereby the production cost of the robot becomes larger.
An object of the present invention is to resolve the above problems. In other words, one object of the invention is to provide a managing structure for an umbilical member, by which the motion of the umbilical member is not so changed even when the orientation of the work tool is greatly changed by rotation of the wrist axis of the robot, whereby the stress applied to a wire or a tube constituting the umbilical member may become smaller. Also, another object of the invention is to provide a managing structure for an umbilical member capable of easily changing the arrangement of the umbilical member at an installation site of the robot, so as to flexibly allow the modification of a system including the robot.
In order to resolve the above problems, in the present invention, the work tool is rotatably supported about an axis parallel to a final axis (j6 axis) of the robot. The umbilical member for the work tool extends within a hollow portion of a speed reduction mechanism for a first wrist element and is introduced toward the outside from an opening formed on a side of a front part of the forearm (or the first wrist element). Then, the umbilical member is supported by a suitable holding means and is connected to the work tool.
Concretely, according to one embodiment of the present invention, there is provided a managing structure for an umbilical member of an industrial robot, the robot having: a forearm having a base; a first wrist element mounted to the base of the forearm and rotatable about a first axis extending in the longitudinal direction of the forearm; a second wrist element mounted to the first wrist element and rotatable about a second axis generally perpendicularly intersecting with the first axis; and a work tool mounted to the second wrist element and rotatable about a third axis generally perpendicular to the second axis and spaced from the first axis by a predetermined distance, the umbilical member including a wire and/or a tube connected to the work tool, wherein the managing structure comprises: a speed reducer having a hollow portion for rotating the first wrist element about the first axis, the speed reducer being arranged between the base of the forearm and the first wrist element such that an axis of rotation of the speed reducer coincides with the first axis; and a holding part, for holding the umbilical member, arranged on a side of the first wrist element, the umbilical member extends through the hollow portion of the speed reducer, is drawn from a first opening formed near the holding part, and is connected to the work tool after at least one of components constituting the umbilical member is held by the holding part.
The work tool may be a hand including a pair of gripping jaws capable of opening and closing.
A second opening may be formed on the base of the forearm for communicating with the hollow portion of the speed reducer. In this case, a welding torch is used as the work tool and the umbilical member may include a cable for welding current, a tube for supplying shielding gas and a liner for supplying a welding wire. Further, a welding wire feeder may be arranged on the first wrist element and the umbilical member is introduced from the second opening toward the inside of the forearm and the hollow portion of the speed reducer.
The welding wire feeder may also serve as the holding part of the umbilical member. Alternatively, the holding part of the umbilical member may be positioned near the welding wire feeder.
A motor for the welding wire feeder may be contained within the first wrist element.
The above and other objects, features and advantages of the present invention will be made more apparent from the following description of the preferred embodiments thereof, with reference to the accompanying drawings, wherein:
a is a front view of a total configuration of a managing structure for an umbilical member of a first embodiment of the invention;
b is a side view of the first embodiment of
a is a detailed front view around the forearm of the first embodiment;
b is a side view of the first embodiment of
Embodiments of the invention will be described with reference to
a and 2b show a total configuration of the first embodiment of the invention. In particular,
A first opening 15 and a holding means 22 for holding the umbilical member are arranged on the side of the first wrist element 15. The umbilical member 6 is drawn toward the outside of the robot body from the first opening 21 and, then, is held by the holding means 22 near the opening 21. Further, the umbilical member 6 extends to the hand 17 along a second wrist element 16 mounted to the first wrist element 15. As the holding means 22, a conventional fixer or a clamp member may be used. Alternatively, an engaging member, such as a ring through which the umbilical member passes, may be used for allowing the umbilical member to move in the longitudinal direction of the umbilical member and to twist or rotate its longitudinal axis. Alternatively, a connector box having a connecting function may be arranged, for convenience, as described below. In the invention, the connector box having the connecting function is also considered to be one of the holding means for the umbilical member 6.
The servomotor for each axis of the robot 10 is controlled, in a known manner, based on an operating command outputted by a robot control device 20. The robot control device 20 also outputs a gripping command to the hand 17, as well as the operating command to the servomotor, for controlling the opening and closing motions of the gripping jaws 18. When the hand 17 grips an object (for example, an assembly), a signal for informing the grip is sent to the control device 20 via the control cable or the umbilical member 6.
a and 3b show the detail configuration of the forearm and peripherals of the embodiment shown in
In
The second wrist element 16 mounted to the first wrist element 15 may be rotated about a second axis B, generally perpendicularly intersecting with the first axis A, by a servomotor of a fifth axis (not shown) of the robot 10. On the other hand, the hand 17 is rotated about a third axis C, generally perpendicular to the second axis B and spaced from the first axis A by a predetermined distance, by a servomotor of a final axis of the robot 10. An example of a mechanism for rotating the hand or the work tool 17 about the third axis C is described below.
A connector box 23 is positioned near the opening 21. The umbilical member 6 from the speed reducer 30 is connected to the connector box 23 and another umbilical member 6 is arranged from the box 23 to the hand 17. A solenoid valve 24 is arranged at a position within the first wrist element 15 and close to the opening 21. The solenoid valve 24 controls supply or removal of air to or from an air cylinder for opening and closing the gripping jaws 18 of the hand 17.
The umbilical member 6 includes a tube for supplying air, as well as the electrical wire such as a control cable for a servomotor (described below) for driving the final axis. The above solenoid valve 24 is arranged on the tube of the umbilical member. A source of supply/removal of air, not shown, is arranged outside of the robot, whereby the supply/removal of air is controlled by the robot control device 20 in a known manner. Further, a tube extending from the source (not shown) is connected to the umbilical member 6 at an appropriate position such in front of the base 11. As this configuration regarding supply/removal of air is known, the detailed description of it is omitted.
When the handling operation of the robot 10 shown in
When the fifth axis is activated, the second wrist element 16 is rotated about the second axis B. Due to this motion, the hand 17 is pivoted about the second axis, however, the umbilical member 6 is held near the opening 21. Therefore, only a short part of the umbilical member 6, extending from the held position near the opening 21 to the hand 17, follows the motion of the second wrist element 16. The rotation of the second wrist element 16 also does not significantly influence the umbilical member 6.
When the sixth axis is activated, the hand 17 is rotated about the third axis C. In this case, as the third axis C is offset from the first axis A, only a twisting force is applied to the umbilical member 6 connected to the hand 17. Therefore, the umbilical member 6 does not flutter due to the motion of the sixth axis.
Conversely, as the umbilical member 6 does not flutter by the motion of the sixth axis, only the rotational motion of the second element 16 about the second axis B, having the relative narrow operating range, should be considered. Therefore, the umbilical member 6 may be arranged such that the umbilical member 6 is drawn from the side of the first wrist element 15. Thus, according to the embodiment, in relation to the rotation of the final axis and the pivoting of the second wrist element about the second axis B, the motion of the umbilical member may be stable. Further, as the umbilical member 6 extends through the hollow portion of the first wrist element 15 and a driving mechanism thereof toward the opening 21 formed on the side of the first wrist element 15, the wire and the tube constituting the umbilical member may twist over a relative long distance within the forearm when the first wrist element 15 rotates about the first axis A. Therefore, the motion of the umbilical member may also be stable.
Next, with reference to
The output gear 45 is positioned in a gear box 43. The input gear 44 is rotatably supported by the output flange 42. Also, the output gear 45 is rotatably supported by the gear box 43 via the bearing 4. The hand 17 is fixed to one end of the output gear 45 away from the servomotor 40. The umbilical member or an air tube 6 is rotatably connected to the other end of the output gear 45. The air tube is also connected to the gear box 43. A wire and a pipe constituting the air tube extend through a hollow portion 47 of the output gear 45 and is connected to the hand 17.
Next,
The umbilical member 60 is constituted, corresponding to an arc welding robot, by using a welding wire enclosed by a liner 61 for supplying the wire, a cable 62 for welding current and a tube 63 for supplying shielding gas. The cable 62 and the tube 63 are directly connected to a welding torch 19 rotatable about the third axis C. As a mechanism for driving the welding torch 19 about the third axis C may be the same as that described using
The welding wire 61 is exposed from the liner just before diverging from the cable 62 and the tube 63 and, then, guided and fed by a feed roller 51 of a wire feeder 50. After that, the wire 61 is enclosed by the liner again and connected to the welding torch 19 with the cable 62 and the tube 63. The feed roller 51 is driven by a motor 52 contained within the first wrist element 15.
Although only the umbilical member connected to the welding torch 19 is shown in
Therefore, a user of the robot may add a necessary wire and a tube for the work tool corresponding to the system on the actual field. Also in this case, such a robot may be provided with a partition or the like, in which the motor control cable 81 may be separated, from a processing unit of the wire and tube 70 for the work tool, without affecting a life of the motor control cable 81.
The user may use the configuration shown in
The wire and tube 70 must have a margin because the wire and tube 70 may be bent when the second wrist element rotates. However, a handling robot, for example, is usually operated such that the robot faces a lower direction, in relation to a horizontal plane, whereby the rotational range of the wrist of the robot may be limited to about 130 degrees. Therefore, the wire and tube around the wrist may be relatively easily arranged along the forearm.
According to the invention, the load applied to the wire and tube, constituting the umbilical member connected to the work tool mounted on the end of the wrist of the robot, may be reduced. Further, the motion of the umbilical member during the operation of the robot may be stable. As a result, a life of the umbilical member may be extended and interference between the umbilical member and peripherals may be avoided. The field work for changing or adding the umbilical member, required when the system is modified, may be easily carried out, by forming the openings (or the first and second openings) on the front part of the forearm (or the first wrist element) and the rear part of the forearm (or the forearm base), through which the umbilical member may extend within the hollow portions of the forearm and the speed reducer. Therefore, it is useful that only the minimum kinds of robot bases are necessary for various modifications of the system.
While the invention has been described with reference to specific embodiments chosen for the purpose of illustration, it should be apparent that numerous modifications could be made thereto, by one skilled in the art, without departing from the basic concept and scope of the invention.
Number | Date | Country | Kind |
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2004-235858 | Aug 2004 | JP | national |