Joint structure that can optimize the length variation of a supply line, and industrial robots with the joint structure

Abstract

Joint structure of an industrial robot, the industrial robot comprising the following: an upper arm (16); a forearm (22) with a forearm base (20) which is rotatably connected to the upper arm; a supply line (28) extending from a lateral side of the upper arm and being inserted into a lateral side of the forearm base; a first fastening element (44) that secures the supply line to an upper section of the lateral side of the upper arm; and a second fastening element (46) that secures the supply line to the lateral side of the forearm base, where the range of motion of the forearm in relation to the upper arm is variable, wherein the supply line has a length range corresponding to the range of motion of the forearm between the lateral side of the upper arm and the lateral side of the forearm base, and wherein the supply line (28) has a length section for adjusting the length range corresponding to a change in the range of motion of the forearm (22), wherein a receiving section (38 or 42) for receiving the length section of the supply line (28) is formed in the upper arm (16) and in the forearm (22), and the length section is received in or held by the upper arm or the base of the forearm.

Description

GENERAL STATE OF THE ART1. Field of the invention

[0001] The present invention relates to a joint structure that can optimize the length clearance of a supply line, and to an industrial robot with the joint structure. 2. Description of the state of the art

[0002] In an industrial robot with an upper arm, a forearm rotatably connected to the upper arm, and a wrist element rotatably attached to the forearm, there are two movement patterns: one in which the forearm's center of rotation is positioned above a straight line connecting the centers of rotation of the upper arm and wrist, and another in which the forearm's center of rotation is positioned below this straight line. To achieve the greatest possible range of motion at the rear of the robot, the range of rotation angle of the forearm relative to the upper arm is often extended recently, allowing both of the above two movement patterns to be used.

[0003] As a relevant prior art document, for example JP 2003-225883 A discloses a configuration in which an outer plastic cable guide 20 is arranged in a cable entry hole 10b with an elongated shape, an inner plastic cable holder 21 for holding a cable 7 is carried in the outer cable guide 20 to move in the circumferential direction, and the inner cable holder 21, which extends downwards from the outer cable guide 20, is positioned at a height corresponding to a connecting part 8a of a frame 8.

[0004] JP 2002-239968 A discloses a configuration with a second arm 14 and a third arm 15, in which a movable first stopper 32 abuts a stationary first stopper 37 when the third arm 15 is rotated clockwise, a movable second stopper 36 abuts a stationary second stopper 38 when the third arm 15 is rotated counterclockwise, and the stationary first stopper 37 and the stationary second stopper 38 are arranged on a housing 31 of the second arm 14 at positions that are deflected in both the radial and circumferential directions.

[0005] Furthermore, JP 2010-089186 A discloses a robot controller configured to prevent an incorrect setting of a movement range of a physical stopper with respect to a motion control range of a software controller and to set multiple motion control ranges within a predetermined movement range of an arm.

[0006] In an industrial robot, a power cable extending from the robot controller is typically connected to a motor that controls each axis of the robot. In this case, the length and position of the (movable) power cable around a joint between the upper and lower arms are determined such that any stress generated in the power cable remains within an acceptable range, even when the upper arm is operated with a relatively wide range of motion. Consequently, the power cable can sag considerably laterally and outwards.

[0007] On the other hand, the actual robot is not normally operated in the state where the forearm's center of rotation is positioned below the straight line connecting the centers of rotation of the upper arm and wrist. In such a state, it is desirable to restrict the forearm's range of motion, thereby reducing the length of the supply line extending laterally.

[0008] DE 10 2013 222 453 A1 relates to a cable guidance device for guiding at least one supply line along a manipulator arm comprising several links connected by at least three joints, comprising: - at least one holder configured to attach at least one, in particular fixed, section of the supply line to at least one of the links of the manipulator arm, and - a controllable drive device configured to actively adjust at least one other, in particular movable, section of the supply line relative to the manipulator arm; and an industrial robot with such a cable guidance device.

[0009] DE202011004786U1 describes a guide system for supply lines for a handling device, in particular for an industrial robot, with a base and a chain-, hose- or belt-like strand in or on which the supply lines can be arranged, wherein the strand is guided in a compensating section in two sections connected to each other via a deflection bend, each with an end-end connection point, a first connection point stationary relative to the base of the guide system and a second connection point movable relative to the base, the second connection point being movable back and forth relative to the first connection point via a travel path between a deflection position in which the strand is extended and a return position in which the strand is retracted, and the guide system having a return device for returning the strand to the return position, characterized in thatthat the return device has a deflection guide with a deflection element, in which the deflection arc is laterally supported for its guidance over the travel path, wherein the deflection element is arranged to be movable back and forth with at least one path component in the direction of the travel path relative to the base between the deflection position and the return position. BRIEF SUMMARY OF THE INVENTION

[0010] Consequently, one object of the present invention is to provide a joint structure that can optimize a length clearance (a length sagging outwards) of the supply line corresponding to a range of motion of a forearm, and an industrial robot with the joint structure.

[0011] According to one aspect of the present invention, an articulated structure of an industrial robot is provided, wherein the industrial robot comprises: an upper arm; a forearm with a forearm base rotatably connected to the upper arm; and a supply line extending from a lateral side of the upper arm and inserted into a lateral side of the forearm base, wherein a range of motion of the forearm relative to the upper arm is variable, wherein the supply line has a length clearance corresponding to the range of motion of the forearm between the lateral side of the upper arm and the lateral side of the forearm base, and wherein the supply line has a length section for adjusting the length clearance corresponding to a change in the range of motion of the forearm, wherein the length section is received in or held by the upper arm or the forearm base.

[0012] In a preferred embodiment, the joint structure comprises a first fastening element that secures the supply line to an upper section of the lateral side of the upper arm, and a second fastening element that secures the supply line to the lateral side of the forearm base.

[0013] In this case, the second fastening element can be configured such that at least one position and orientation of the second fastening element can be adjusted in relation to the forearm base.

[0014] In a preferred embodiment, the joint structure comprises a physical stopper that limits the range of motion of the forearm relative to the upper arm, wherein the physical stopper is configured to switch the range of motion of the forearm between a first range of motion and a second range of motion which is wider than the first range of motion.

[0015] According to another aspect of the present invention, an industrial robot comprising the above joint structure is provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The above and other problems, features and advantages of the present invention will become more apparent from the following description of preferred embodiments thereof, together with reference to the accompanying drawings, in which: Fig. 1 shows a main section of an industrial robot according to a preferred embodiment of the present invention; the Fig. 2a to 2c show a front view, side view and top view of a joint structure of the robot. Fig. 1 are; Fig. Figure 3 shows an example in which the range of motion of a robot's forearm is greater than that of Fig. 1 is; the Fig. 4a to 4c show a front view, side view and top view of a joint structure of the robot. Fig. 3 are; Fig. 5 is a perspective view showing the joint structure of Fig. 1 shows; and Fig. 6. A perspective view is shown, which illustrates the joint structure of Fig. 3 shows. DETAILED DESCRIPTIONS

[0017] Fig. Figure 1 shows a main section of an industrial robot (hereinafter also referred to simply as "robot") 10 according to a preferred embodiment of the present invention. The robot 10 is, for example, a multi-jointed robot with six axes. The robot 10 has a base (not shown) that is installed on a floor, etc.; a rotating body 12 that is connected to the base to rotate about a generally vertical axis; an upper arm 16 that is connected to the rotating body 12 to rotate about an upper arm axis of rotation 14; and a lower arm 22 with a lower arm base 20 that is connected to the upper arm 16 to rotate about a lower arm axis of rotation 18.A wrist element 26 is attached to a front end of the forearm 22 to rotate about three axes that intersect at a wrist pivot center 24, and a working tool (not shown), such as a robot hand or a welding torch, may be attached to a front end of the wrist element 26.

[0018] In the robot 10, a power supply line 28, formed by a cable, etc., is arranged to supply energy to a motor, such as a servomotor, for driving each axis (upper arm 16, lower arm 22, and wrist element 26, etc.). This power supply line extends from a robot controller (not shown) for controlling the robot 10 and is connected to each motor. The power supply line 28 generally extends from the rotating body 12 along the longitudinal direction of the upper arm 16, is inserted into a lateral side of the upper arm 16, extends along or near a lateral side of a connecting part (or joint structure) 30 between the upper arm 16 and the lower arm base 20, and is inserted into a lateral side of the lower arm base 20.Furthermore, the supply line 28 is positioned to have adequate length clearance near the joint structure 30 (between the lateral side of the upper arm 16 and the lateral side of the forearm base 20), corresponding to the range of motion of the forearm 22. The length clearance is determined, for example, such that excessive stress is not exerted on the supply line 28 when the forearm 22 is moved within its range of motion, and that the supply line 28 does not sag far outwards from the joint structure.

[0019] The Fig. Figures 2a to 2c show a front view (2a), a side view (2b) and a top view (2c) of the joint structure (or the connecting part between the upper arm 16 and the forearm 22 (the forearm base 20)) of the robot 10, as shown in Fig. Figure 1 shows that a physical stopper (or a mechanical stopper) is arranged on the joint structure 30 to limit the range of motion (or the range of rotation angle) of the forearm 22 relative to the upper arm 16. Specifically, as shown in Fig. As shown in Figure 2a, a first projection 32 is arranged on a part of the forearm base 20 near the upper arm 16, and a second projection 34 is arranged on a part of the upper arm 16 near the forearm base 20 ( Fig. 2b) The shapes and positions of the first and second projections are determined such that the projections come into contact with each other when the rotation angle of the forearm 22 reaches an upper or lower limit within a predetermined range of motion (for example, if the range of the rotation angle is between -180 and +180 degrees, the upper and lower limits are +180 degrees and -180 degrees, respectively), thus preventing the forearm 22 from rotating beyond the range of motion. In the example of the Fig. In sections 2a to 2c, the range of motion of the forearm 22 is defined as a first range of motion, and the first range of motion is narrower than a second range of motion, which in an example of the Fig. 3 to 4c as described below.

[0020] As explained above, in the example of the Fig. In sections 2a to 2c, the range of motion of the forearm 22 is defined as the relatively narrow first range of motion. Consequently, the length of play of the supply line 28 arranged around the joint structure 30, which is required for the movement of the forearm 22, can be relatively short. On the other hand, as in the example described below Fig. 3. If the range of motion of the forearm 22 is determined to be the second range of motion, which is greater than the first range of motion, it is necessary that the length of the supply line 28 be extended accordingly. In this respect, if the supply line 28 has a relatively large length of play, also in the example of the Fig. 1 to 2c, in the case where the range of motion is changed from the first range of motion to the second range of motion, the supply line 28 may sag adversely from the joint structure 30 or may be damaged by being caught by or pulled into the joint structure 30.

[0021] Furthermore, in the way that is in Fig. In the robot 10 shown in Figure 1, the pivot point 18 of the forearm 22 is positioned above a straight line 35 that connects the pivot point 14 of the upper arm 16 and the pivot point 24 of the wrist element 26. Although the robot 10 can also be operated with the pivot point 18 of the forearm 22 positioned below the straight line 35, it is not uncommon for the robot 10 to be operated in such a case. Furthermore, in such a case, it is often desirable to limit the range of motion of the forearm 22 in order to reduce the sagging length of the supply line 28.

[0022] Accordingly, as in Fig. As shown in Figure 2a, the present invention provides for a receiving section in the upper arm 16 and the lower arm 22 (the base 20) for receiving the length portion of the supply line 28 in order to adjust the length play of the supply line. For example, on an upper section (near the lower arm) of the upper arm 16, a frame forming the upper arm 16 has an opening 36 through which the supply line can be inserted, and the supply line 28 is inserted from the opening 36 into a space (or a receiving section 38) within the upper arm 16. As a result, a portion of the length play, which in the example of the Fig. 3 to 4c is required in the space to be received. Similarly, the forearm base 20 can have an opening 40 through which the supply line can be inserted, and a space (or a receiving section 42) can be arranged such that the supply line 28 can be inserted into the space by means of the opening 40. Thanks to one or more such receiving sections, even if the range of motion of the forearm 22 is changed, the operator can adjust (optimize) the length of the supply line required for the movement of the forearm 22.

[0023] In the example of the Fig. In Figures 2a to 2c, the means for adjusting the length play of the supply line 28 is defined as the receiving section, whereas the present invention is not limited in this way. The length play required for adjustment can, for example, be held on the outer surface (or the lateral side) of the upper arm 16 or the lower arm 22 (the lower arm base 20) by using a retaining element, such as a clamp or a cable tie. In this respect, the term "held" means that the held portion of the supply line cannot be moved relative to the upper arm 16 or the lower arm 22. Furthermore, the supply line 28 is normally formed by several cables, and the cables can be configured as a single composite cable, which simplifies the step of adjusting the length play of the supply line 28.

[0024] Fig. Figure 3 shows an example in which the range of motion (or the range of rotation angle) of the forearm 22 is shown in relation to the upper arm 16 of the robot, as in Fig. 1, is extended (or modified) to the second range of motion. As a concrete means of changing the range of motion of the forearm 22, the position of at least one of the physical stoppers 32 and 34 can be changed; alternatively, at least one of the physical stoppers can be replaced by another stopper with a different shape. In the example of Fig. 3 The range of motion of the forearm 22 in relation to the upper arm 16 is extended towards the back (or left side) of the robot.

[0025] The Fig. Figures 4a to 4c show a front view (4a), a side view (2b) and a top view (4c) of the joint structure of the robot 10, as shown in Fig. Figure 3 shows. As explained above, a receiving section 38 or 42 is formed on at least one of the upper arm 16 and the lower arm 22 for receiving the length portion of the supply line 28, which is required to adjust (or extend) the length play of the supply line. Consequently, the operator can adjust the length play, which in the case of Fig. 3 is required, adjust beforehand before the robot 10 is operated by pulling the supply line 28 out of the recording section.

[0026] As in Fig. 2b or Fig. As shown in Figure 4b, it is preferred that a first fastening element 44, such as a clamp for securing the supply line 28, is arranged on the lateral side of the upper section (near the forearm) of the upper arm 16. Furthermore, as shown in Fig. 2c or Fig. As shown in Figure 4c, it is preferred that a second fastening element 46, such as a clamp for securing the supply line 28, is arranged on the lateral side of the forearm base 20. Thanks to these fastening elements, the supply line 28 can remain stable or move when the forearm 22 is rotated.

[0027] Furthermore, the Fig. 2c and Fig. In comparison to 4c, it is preferred that at least one of the position and orientation (or the direction of attachment) of the second fastening element 46, which is arranged on the lateral side of the forearm base 20, is changeable or adjustable. If at least one of the position and orientation of the second fastening element 46 is changeable or adjustable, the route of the supply line 28 around the joint structure 30 and the length play can be optimized.

[0028] As in Fig. As shown in Figure 2c, if, for example, the range of motion of the forearm 22 is relatively small, the orientation of the second fastening element 46 can be changed such that the length of the supply line 28 between the first fastening element 44 and the second fastening element 46 is relatively short. However, if the range of motion of the forearm 22 is extended from this state (i.e., the length of the supply line 28 is also extended), the supply line 28 can be captured by or drawn into the joint structure 30, depending on the rotation angle of the forearm 22, as shown in Figure 2c. Fig. 5 are shown as examples.

[0029] Consequently, as in Fig. As shown in Figure 4c, if the range of motion of the forearm 22 is relatively large, it can be changed by altering the orientation of the second fastening element 46 so that the supply line 28 extends from the second fastening element 46 in one direction (the horizontal direction in Fig. 4c) extends perpendicular to the longitudinal direction of the forearm 22, preventing the supply line 28 from being captured by or drawn into the joint structure 30, as in Fig.Figure 6 illustrates this by way of example. In this respect, “adjusting (or changing) at least one of the position and orientation of the fastening element 46” can include changing the position and orientation of the supply line 28 with respect to a body of the fastening element 46 and securing the supply line 28 by a clamp or cable tie, etc., so that the supply line 28 cannot be moved with respect to the body of the fastening element 46 without changing the position and orientation of the body of the fastening element 46.

[0030] As explained above, in the joint structure of the present invention, when the range of motion of the forearm is extended or increased by replacing the physical stopper or changing the position of the physical stopper, the length clearance required for the extended range of motion can be easily adjusted by using the supply line which is received in the receiving section or held on the lateral side of the upper arm or the base of the forearm.

[0031] On the other hand, if the range of motion of the forearm is reduced, the length allowance required for the reduced range of motion can be easily adjusted by including an excess length of the supply line beyond the length allowance required for the reduced range of motion in the receiving section, or by holding the excess length on the lateral side of the upper arm or the base of the forearm.

[0032] According to the present invention, the length and / or route of the supply line in the joint structure between the upper arm and the forearm of the industrial robot can be easily modified depending on a change in the range of motion of the forearm.

Claims

[1] Joint structure of an industrial robot, the industrial robot comprising: an upper arm (16); a forearm (22) with a forearm base (20) which is rotatably connected to the upper arm; a supply line (28) extending from a lateral side of the upper arm and being inserted into a lateral side of the forearm base; a first fastening element (44) that secures the supply line to an upper section of the lateral side of the upper arm; and a second fastening element (46) that secures the supply line to the lateral side of the forearm base, where the range of motion of the forearm in relation to the upper arm is variable, wherein the supply line has a length range corresponding to the range of motion of the forearm between the lateral side of the upper arm and the lateral side of the forearm base, and wherein the supply line (28) has a length section for adjusting the length range corresponding to a change in the range of motion of the forearm (22), wherein a receiving section (38 or 42) for receiving the length section of the supply line (28) is formed in the upper arm (16) and in the forearm (22), and the length section is received in or held by the upper arm or the base of the forearm. [2] Joint structure according to claim 1, characterized by that the second fastening element is configured such that at least one of the positions and orientations of the second fastening element can be adjusted with respect to the forearm base. [3] Joint structure according to claim 1 or 2, characterized by, that the joint structure includes a physical stopper (32, 34) that limits the range of motion of the forearm in relation to the upper arm, wherein the physical stopper is configured to switch the range of motion of the forearm between a first range of motion and a second range of motion which is wider than the first range of motion. [4] Industrial robot (10) comprising the joint structure according to any one of claims 1 to 3.

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