Guiding device for an umbilical member of a robot and a robot having the guiding device

A guiding device, with high rigidity, for an umbilical member and a robot having the guiding device, by which interference between the umbilical member and another component or external equipment is minimized. The guiding device or an adaptor includes a first plate member fixed to a third wrist element, a second plate member opposing to and parallel to the first plate member, and a connecting member for connecting the first and second plate members. The first and second plate members and the connecting member define a first opening for introducing the umbilical member into the adaptor. The second includes a fixed portion fixed to an end effector and an extended portion extending from the fixed portion and offset from the third wrist axis. A second opening is formed on the extending portion of the second plate member, through which the umbilical member may extend.

BACKGROUND ART

1. Technical Field

The preset invention relates to a guiding device, for an umbilical member including a cable and/or a tube of an industrial robot, and to a robot having the guiding device.

2. Description of the Related Art

When an industrial robot is used for an operation, the robot is required to be provided with an umbilical member including a cable and/or a tube for transmitting power or a signal to an end effector attached to the end of a wrist element of the robot. When the umbilical member is arranged around the wrist element of a robot arm, the umbilical member may contact the arm or another external equipment and may be worn or damaged. In order to avoid such an inconvenience, several configurations has been proposed.

For example, Japanese Unexamined Patent Publication No. 2001-150382 discloses a configuration in which a clamp arranged on a suitable site near a wrist element holds an umbilical member. The clamp is attached to a point of a rotation axis of an arm such that the clamp holding the umbilical member may be rotated relative to the wrist element. As the clamp is rotated according to the motion of each axis of the wrist element, the umbilical member is prevented from winding on to the arm.

Japanese Unexamined Patent Publication No. 2003-136462 discloses that an intermediate member having a two connecting members for connecting two flanges is arranged between a wrist flange and an end effector. The umbilical member extends through the intermediate members or between the two connecting members.

Further, Japanese Unexamined Patent Publication No. 7-124886 discloses a coupling member having an opening in the center thereof, through which the umbilical member may extend. The coupling member has a generally cylindrical shape and is arranged at a rotational joint of the robot for transmitting a rotary force. One end surface, and a side surface, of the coupling member have wide openings. The umbilical member is introduced into the coupling member from the opening of the side surface and led out from the opening of the end surface.

In the configuration disclosed in Japanese Unexamined Patent Publication No. 2001-150382 in which the clamp holds the umbilical member, the umbilical member, positioned near the clamp, does not contact the arm or the wrist of the robot. However, the umbilical member positioned at a place other than near the clamp may contact the arm or the wrist. Therefore, it is necessary to loosen the umbilical member between each clamp, with the result that the loosened umbilical member may contact the external equipment. Further, in order to avoid interference between each clamp when the wrist rotates, an operating range of the wrist must be limited.

In the configuration disclosed in Japanese Unexamined Patent Publication No. 2003-136462, the rigidity of the intermediate member is low because the connecting member of the intermediate member is divided into two parts. Therefore, the end effector vibrates when the robot is activated. In order to avoid the vibration, an operating speed of the robot must be restricted, resulting in a cycle time of the operation increasing.

Further, in the configuration disclosed in Japanese Unexamined Patent Publication No. 7-124886, in which the coupling member is arranged between the wrist flange and the end effector, the coupling member has an opening on generally the center of a surface of the coupling member fixed to the end effector. When the umbilical member is arranged through the coupling member, the umbilical member must be drawn from the center of the surface fixed to the end effector, resulting in the umbilical member interfering with the end effector.

SUMMARY OF THE INVENTION

Therefore, an object of the present invention is to provide a rigid guiding device for an umbilical member for minimizing the possibility of interfere between the umbilical member and other component or equipment and a robot having the guiding device.

To this end, according one aspect of the present invention, there is provided a guiding device for supporting an umbilical member corresponding to the motion of a robot, the robot having: a forearm; wrist elements rotatably mounted to the end of the forearm; an end effector attached to one of the wrist elements; and a flexible umbilical member connected the end effector, wherein the guiding device comprises: a first plate member fixed to the wrist element; a second plate member fixed to the end effector, the second plate member opposing to the first plate member and being apart from the first plate member by at least the diameter of the umbilical member; and a connecting member for connecting the first and second plate members; and wherein the first and second plate members and the connecting member form a passage through which the umbilical member may extend; the first and second plate members and the connecting member define a first opening for introducing the umbilical member into the passage; and the second plate member has a second opening for leading out the umbilical member from the passage.

Preferably, the second opening is directed generally parallel to the rotation axis of the wrist element.

Concretely, the second plate member may include a fixed portion fixed to the end effector and an extended portion extending from the fixed portion and away from the rotation axis of the wrist element and the second opening is formed on the extending portion. In this case, the second opening is preferably formed on a side opposing to the first opening in relation to the rotation axis of the wrist element.

It is preferable that the connecting member is distant from the rotation axis of the wrist element such that the connecting member is positioned at the same side as the second opening in relation to the rotation axis.

It is preferable that the second plate member further includes a holder arranged near the second opening for holding the umbilical member.

According to another aspect of the present invention, there is provided a robot having the guiding device according to the invention.

DETAILED DESCRIPTION

Embodiments of the invention will be described with reference to the drawings.

FIG. 1shows a total configuration of a guiding device of the invention and indicates a robot1from the end of a forearm to an end effector. As shown, a wrist12is attached to the end of the forearm10of the robot1. The wrist12is constituted by a first wrist element14mounted to the end of the forearm10and rotatable about a first wrist axis50along the longitudinal direction of the forearm10, a second wrist element16mounted to the first wrist element14and rotatable about a second wrist axis52perpendicular to the first wrist axis50and a third wrist element18mounted to the second wrist element16and rotatable about a third wrist axis54perpendicular to the second wrist axis52. A guiding device for an umbilical member or an adaptor20is attached to the end of the third wrist element18. Further, an end effector30such as a welding gun or a handling tool is attached to the adaptor20.

Power and a signal are sent to the end effector30by means of an umbilical member32constituted by a cable, a tube and the like. The umbilical member32is arranged along a base (not shown) of the robot1, the forearm arm10and the wrist12and connected to the end effector30.

As shown inFIGS. 1 and 3, the guiding device or the adaptor20includes a first plate member21fixed to the third wrist element18, a second plate member22fixed to the end effector30, opposing to the first plate member21and being apart from the first plate member21by at least the diameter of the umbilical member32, and a connecting member23for connecting the first and second plate members21and22. The first and second plate members21and22and the connecting member23form a passage24through which the umbilical member32may extend. The first and second plate members21and22and the connecting member23define an inlet or a first opening25for introducing the umbilical member32into the adaptor20, i.e., between the first and second plate members21and22. Also, as shown inFIG. 3, the second plate member22includes a fixed portion22afixed to the end effector30and an extended portion22bextending from the fixed portion22aand away from the first opening25. Further, an outlet or a second opening26is formed on the extending portion22bthrough which the umbilical member32may extend. In other words, the second opening26is positioned on the second plate member22and is offset from the third wrist axis54to some extent. Preferably, the second opening26is formed on an opposing side to the first opening25in relation to the third wrist axis54such that the umbilical member32introduced into the first opening25may be easily drawn from the second opening26across the third wrist axis54.

Next, the arrangement of the umbilical member32will be described. As shown inFIG. 1, the umbilical member32, arranged from the robot base (not shown) and along the forearm10, is held by a first holder34arranged on the first wrist element14. The first holder34may fix the umbilical member32or may slidably hold the umbilical member in the longitudinal direction of the umbilical member. The first holder34may be attached to the first wrist element14by means of a suitable fixture36as shown inFIG. 1. The fixture36may be fixed to the first wrist element14or may be configured to move along the first wrist element14and rotate about the first wrist axis50. Further, the first holder34may be fixed to the fixture36or may be configured such that to rotate relative to the fixture36about an axis perpendicular to the first wrist axis50.

The umbilical member32held by the first holder34extends along the second and third wrist elements16and18and is introduced into the first opening25of the adaptor20. At this point, in order to avoid a drop of the umbilical member which may cause the umbilical member to excessively wind around the wrist12and/or contact an external equipment, a cover38may be arranged on the second wrist element16near the adaptor20for supporting the umbilical member32.

The umbilical member32, introduced into the first opening25of the adaptor20, passes through the inside or the passage24of the adaptor20, across the third wrist axis54, and is drawn from the second opening26of the second plate member22to be connected to the end effector30. As shown inFIG. 2, the umbilical member32within the adaptor20is biased such that the umbilical member, after traversing the third wrist axis54, is close to parallel to the third wrist axis. Due to this configuration, the motion of the umbilical member32caused by the rotation of the third wrist axis54, for example from one state as shown inFIG. 4ato another state as shown inFIG. 4b, includes the twisting of the umbilical member up to the second opening26, as well as the bending of the umbilical member within the adaptor20. This case is more advantageous than a case in which only the bending of the umbilical member occurs, as a local strain or distortion hardly occurs in the umbilical member in the former case. Further, as the connecting member23is offset toward the second opening26relative to the third wrist axis54, interference between the connecting member23and the umbilical member32hardly occurs when the third wrist element18rotates. Therefore, an operating range around the third wrist axis54of this case may be wider than a case in which the connecting member23is not offset relative to the third wrist axis54. In addition, as shown inFIGS. 1 and 2, in order to direct the umbilical member32, led out from the second opening26, close to parallel to the third wrist axis54, the umbilical member32is preferably held by a second holder40positioned on the second plate member22near the second opening26.

As the second opening26is not formed on the connecting member23, the rigidity of the adaptor20may be increased. Therefore, the vibration of the end effector30, which may occur when the robot is operated at a high speed, may be avoided.

As the second opening26is formed on the second plate member22and offset relative to the third wrist axis54, the workability of attaching or detaching of the end effector30to or from the second plate member22is improved. Further, as the second opening26is directed in the direction generally parallel to the third wrist axis54, the umbilical member32led out from the second opening26extends closer to parallel to the third wrist axis54. Therefore, a length of an outwardly protruding potion of the umbilical member32around the wrist12may be minimized. In the embodiment as shown inFIG. 2, an angle θ between the umbilical member32led out from the second opening26of the adaptor20and the third wrist axis54is approximately 45 degrees. However, the present invention is not limited to this embodiment. The angle θ may be varied, depending on the motion range of the third wrist axis54, the rigidity of the umbilical member32based on the material of the cable constituting the umbilical member, and/or the shape of the end effector30. As the above angle θ is closer to zero, the length of the protruding portion of the umbilical member32is shorter.

According to the invention, the rigidity of the connecting member between the first and second plate members may be increased more than that of the prior art, resulting in the rigidity of the guiding device, as a whole, being increased. Therefore, an undesirable vibration of the robot may be reduced or eliminated, whereby it is unnecessary to increase a cycle time of the operation by reducing an operation speed of the robot to avoid the vibration. As the second opening of the second plate member is directed in the direction generally parallel to the rotation axis of the wrist element, the length of the outwardly protruding potion of the umbilical member may be minimized. Further, as the second opening is offset relative to the rotation axis of the wrist element, the end effector may be positioned at the center of the wrist element without interference between the end effector and the umbilical member. In addition, as the connecting member is offset toward the second opening relative to the rotation axis of the wrist element, interference between the connecting member and the umbilical member may be avoided, whereby a wide operation range, for the robot, may be ensured.

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.