Process turning disc with a cable guide

A process turning disc includes a first flange configured to support a cable package in a first direction and a second flange configured to support a cable package in a second direction opposite to the first direction. A connecting member connected to the first and the second flanges is configured to support a cable package in a third direction perpendicular to the first direction. A cable guide is fastened to the process turning disc in a detachable manner and includes a cable clamp configured to support a cable package in a fourth direction opposite to the third direction. The cable guide further includes two sliding surfaces configured to support a cable package in the first and the second directions outside of the cable clamp. A bending movement of the cable package is thereby allowed in a plane perpendicular to the axis of rotation of the process turning disc.

FIELD OF THE INVENTION

The present invention relates to a cable guide attached to a process turning disc in an industrial robot.

BACKGROUND OF THE INVENTION

A process turning disc is a machine part which rotates along with the last axis of an industrial robot and on which a robot tool is mounted. During operation of the robot there are relative movements between a robot arm and the robot tool, and therefore electrical power, pressurized air and any other necessary power source or process fluid is provided to the robot tool via flexible cables and conduits. There typically is a cable package rigidly attached to the robot arm and to the robot tool, but bending and turning more or less freely between the two parts. In order to prolong the service life of the cable package, the bending and turning paths of the same are often constrained in different directions.

A process turning disc may comprise a passage constraining the movement of a cable package between a robot arm and a robot tool as disclosed e.g. in WO2010/052031. In FIG. 6 of WO2010/052031 an embodiment with an open passage for the cable package is shown. In this embodiment a cable clamp is used for preventing the cable package from escaping the passage. However, a cable clamp according to WO2010/052031 exposes the cable package to an extensive wear and is likely to shorten the service life of the same.

SUMMARY OF THE INVENTION

An object of the invention is to provide a process turning disc with improved cable guiding means.

This object is achieved by a process turning disc.

According to a first aspect of the invention there is provided a process turning disc comprising a first flange configured to support a cable package in a first direction, and a second flange configured to support a cable package in a second direction which is opposite to the first direction. A connecting member connected to the first and the second flanges is configured to support a cable package in a third direction which is perpendicular to the first direction. A cable guide is fastened to the process turning disc in a detachable manner and comprises a cable clamp which is configured to support a cable package in a fourth direction which is opposite to the third direction. The cable guide further comprises two sliding surfaces configured to support a cable package in the first and the second directions outside of the cable clamp.

By integrating the sliding surfaces to the detachable cable guide the support for the cable package can be extended outside of the flanges of the process turning disc. These extensions can be made of light-weight material in contrast to heavier material of the process turning disc itself.

According to one embodiment of the invention the first direction is parallel with an axis of rotation of the process turning disc. With this configuration the cable package bends in a plane perpendicular to the axis of rotation of the process turning disc and the bending movement is thereby facilitated.

According to one embodiment of the invention the sliding surfaces extend over a sector of at least 30 degrees, such as at least 50 degrees or at least 70 degrees, about the axis of rotation of the process turning disc. Sliding surfaces extending over a large sector support the cable package over a large range of bending movement and improves thereby the guiding properties of the cable guide.

According to one embodiment of the invention the cable guide comprises a back rest for constraining bending of a cable package away from the connecting member, and a curved surface between the cable clamp and the back rest with a radius of curvature of at least 10 mm, such as at least 20 mm or at least 30 mm. The back rest together with the curved surface limit the bending curvature of the cable package and prolongs thereby the service life of the same.

According to one embodiment of the invention an industrial robot comprises a process turning disc according to any of the preceding embodiments. The process turning disc described hereinbefore is especially adapted to be used on a last axis of an industrial robot between a gear box of the last axis motor and a robot tool.

According to one embodiment of the invention the first direction is parallel with a last robot axis. With this configuration the cable package bends in a plane perpendicular to the last robot axis and the bending movement is thereby facilitated.

According to one embodiment of the invention the industrial robot further comprises a flexible cable package. The process turning disc described hereinbefore is especially adapted for guiding a flexible cable package between a robot arm and a robot tool.

According to one embodiment of the invention the cable clamp presses the cable package against the connecting member such that a section of the cable package becomes fixedly attached to the process turning disc. By this measure a movement of the cable package in a longitudinal direction of the same in relation to the cable clamp is prevented. This is likely to prolong the service life of the cable package.

According to one embodiment of the invention the industrial robot further comprises a roller arranged around the cable package and being rotatable in relation to the same. The roller protects the cable package from direct contact with surrounding robot parts and facilitates the movements of the cable package by rolling against any robot parts it comes into contact with.

According to one embodiment of the invention the roller is configured to interact with the sliding surfaces. The roller rolls against the sliding surfaces of the cable guide and facilitates thereby the bending movement of the cable package. At the same time the roller protects the cable package from direct contact against the sliding surfaces.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1shows an arm and a wrist of a six axis industrial robot, andFIG. 2shows a schematic presentation of the same. A first flange20of a process turning disc10is mounted directly on a gear box of the last robot axis, in the present case the sixth robot axis40, and a robot tool50is mounted on a second flange30of the process turning disc10. Between the first and the second flanges20,30there is formed a passage through which a cable package60passes on its way from the robot arm to the robot tool50. A cable guide70prevents the cable package60from escaping the passage by clamping the cable package60against a connecting member between the first and the second flanges20,30. On the other hand the cable guide70allows bending of the robot arm side of the cable package60within certain limits in a plane perpendicular to the sixth robot axis40. The cable guide70comprises two sliding surfaces80which support the cable package60in the direction of the sixth robot axis40under bending movement of the cable package60. Around the cable package60there is provided a roller90which rotates freely in relation to the cable package60and rolls against the sliding surfaces80to therefore facilitate the bending movement of the cable package60.

Referring toFIG. 3, a process turning disc10together with a detachable cable guide70are shown in more detail. A connecting member100connects the first and the second flanges20,30of the process turning disc10together to form a discrete unit. The connecting member100is formed such that a free space is left between the first and the second flanges20,30to receive the cable package60. The first flange20constrains the movement of the cable package60in a first direction towards the robot arm while the second flange30constrains the movement of the cable package60in a second direction towards the robot tool50. The connecting member100constrains the movement of the cable package60in directions perpendicular to the first and the second directions when the cable package60is bent against the connecting member100.

When the cable package60is bent away from the connecting member100the cable guide70prevents the cable package60from escaping the passage between the first and the second flanges20,30. In one end of the cable guide70a cable clamp110presses the cable package60against the connecting member100such that a section of the cable package60becomes fixedly attached to the process turning disc10. In the opposite end of the cable guide70two sliding surfaces80support the cable package60in the direction of the sixth robot axis40when the cable package60bends in a plane perpendicular to the sixth robot axis40. Finally a back rest120integrated to the cable guide70constrains the bending of the cable package60away from the connecting member100. That is, the bending movement of the cable package60in the plane perpendicular to the sixth robot axis40is constrained at one extreme by the connecting member100and at the other extreme by the back rest120. Between these two extremes the cable package60can bend freely.

Between the cable clamp110and the back rest120the cable guide70comprises a curved surface with a relatively large radius of curvature configured to support the cable package60under bending of the same towards the back rest120. The radius of curvature of this surface is preferably at least 10 mm, such as at least 20 mm or at least 30 mm.

Referring toFIG. 4, the sliding surfaces80of the cable guide70extend over a sector130of about 75 degrees about the axis of rotation of the process turning disc10. As is clear from the description hereinbefore, in the case of the present embodiment the axis of rotation of the process turning disc10coincides with the sixth robot axis40.

The cable guide70may preferably be made of aluminium while the process turning disc10may be made of cast iron. The sliding surfaces80of the cable guide70are actually extensions of corresponding sliding surfaces integrated into the process turning disc10. It is advantageous to provide these extensions in a separate part instead of making the process turning disc10itself more complicated and heavy. The light-weight material used for the sliding surfaces80decreases the overall weight of the cable guiding means.

The invention is not limited to the embodiments shown above, but the person skilled in the art may modify them in a plurality of ways within the scope of the invention as defined by the claims.