JP2006021299A - Robot wrist mechanism, and left and right arrangement-changing method of rotating arm - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make it possible to avoid interference with a circumferential object and to rotate an arm body by the roughly same quantity left and right from its position by reversing the arm body in an offset state from a standard axis in the case necessary to arrange a work holding device, etc. in a robot working area. <P>SOLUTION: Drawn parts 14, 15 passing control cables 10, 11 at the point of time to come out of a hollow driving shaft 3C are provided at two points on the hollow driving shaft 3C with an interval of 180 degrees. Mounting parts of a stopper to prevent excessive rotation of the arm body 3B are also provided at two points with an interval of 180 degrees. Connectors 23, 24 free to separate are interposed between the drawn parts 14, 15 and motors 8, 9 to be driven. It is possible to set movement of the arm body in a state not to be influenced by the circumferential object while never changing an extending route of a conduit cable even after reversion. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a wrist mechanism of a robot and a left / right rearrangement method of a rotary arm, and more particularly, a hollow drive shaft having an arm body of a rotary arm that rotates about a reference axis at the base end and centering on the reference axis A wrist mechanism that is offset from the base axis to one side of the reference axis and extends along the reference axis, and a mechanism that can be rearranged to avoid the arm body in an unevenly distributed state from interfering with surrounding objects, and This relates to a rearrangement method.

  An articulated arc welding robot generally has six axes, and superimposes the rotation, tilting, and turning of each axis to hold the welding torch in a desired posture, and its tip is aimed. Displace to position. FIG. 11A shows an example of the robot 30, and the six shaft portions shown in the robot 30 are as follows.

  They are a sixth shaft portion 7 for turning or rotating a welding torch (not shown) mounted in the direction of arrow 31, and a tilting arm 5 for supporting the sixth shaft portion in the direction of arrow 28 such as swinging. The fifth shaft portion 6 that provides the operation, the fourth shaft portion 33 that rotates the upper arm 3 provided with the fifth shaft portion at the tip in the direction of the arrow 32, and the non-extension of the upper arm 3 that often has a substantially horizontal posture. A third shaft portion 36 for rotating and raising the rotating portion 3A in the direction of arrow 35 with respect to the lower arm 34 tilting in an upright state, and a third shaft for tilting the lower arm 34 in the direction of arrow 38 with respect to the swivel base 37. This is a first shaft portion 41 for turning the biaxial portion 39 and the swivel base 37 horizontally as indicated by an arrow 40 on the base.

  In such a welding robot, the arm main body 3B of the upper arm 3 rotating around the fourth axis 2 may be unevenly distributed on either the left or right side. An example of such a form is also disclosed in Japanese Patent Laid-Open No. 2002-370190, which is not uncommon at present. More specifically, the upper arm 3 is formed by a rotating portion mainly including a hollow drive shaft 3C and an arm main body 3B integrated therewith in addition to the non-rotating portion 3A.

  The arm body 3B is offset to the right side when viewed from one side of the fourth axis 2 from the hollow drive shaft 3C having the fourth axis 2 as the center at the base end, in the example of FIG. In this state, it is extended along the fourth axis 2. The tip of the arm body 3B cantileverally supports a tilting arm 5 that tilts about a crossing axis 4 that is perpendicular to the fourth axis 2 and that is horizontal.

  The reason why such a cantilever offset type upper arm 3 is adopted is as follows. (1) As shown in FIG. 12B, a welding wire, welding power, shield air, and the like are supplied to the welding torch 42. For this reason, the conduit cable 43 that is indispensable is placed as much as possible on the fourth axis 2 as shown in the plane arrow of (a), and the cable touches or becomes entangled with another device in the robot operation area. It can be done as little as possible.

  Further, (2) when the tilting arm 5 tilts with respect to the upper arm 3, a large space is secured vertically so as to allow the conduit cable 43 to bend upward or downward as shown in (b). (3) Since one space 44 is vacated as shown in FIG. 12A, maintenance work for inspection and replacement of the conduit cable 43 can be easily performed. Incidentally, in (b), the tilting arm 5 is shown in a standard vertical posture, but (a) is in a state where the tilting arm 5 is in a horizontal posture which is on the extension line of the upper arm 3. It is drawn.

  By the way, when the surrounding object 45 such as a device for holding a workpiece or another robot as shown in FIG. 13A exists in the operation area of the welding robot 30 and must be unluckily brought close to the upper arm 3. There is. When the arm body 3B of the cantilever offset type is adopted for the upper arm 3, if the touch of the surrounding object 45 occurs, the operation of the robot is out of the question or the surrounding object is shifted to an inconvenient position. And so on.

  If such a situation is assumed, the upper arm body shown in FIG. That is, when the arm body is removed from the hollow drive shaft (not shown) and replaced with a symmetrical arm body 3B, an extra space 46 can be formed between the surrounding object 45 and the side of the upper arm 3. In this case, not only the burden and cost of storing two types of arm bodies must be increased, but also troublesome work is required for replacement.

  A possible way to eliminate such disadvantages and inconveniences is to reverse the upper arm 3 that can be rotated around the fourth axis 2 from the state of FIG. 13A by 180 degrees as shown in FIG. 13B. That is. The prior literature described above discloses a left-right mishandling operation according to this kind of procedure. If rotation of about ± 190 degrees, for example, is allowed from the state before reversal and the state after reversal, the intended purpose is achieved.

  By the way, if it is set to ± 190 degrees, the tilting arm 5 and the sixth shaft part 7 can be swung slightly over 360 degrees regardless of the rotation to the left or right, and the welding torch can take any posture. Because it can be given. However, the reason why the angle does not exceed about 190 degrees on one side is to prevent the twisting of the control cable and conduit cable, which will be described later, and to prevent them from getting stuck around the arm. It is.

By the way, the upper arm 3 is rotated 180 degrees in the direction of the arrow 32 around the fourth axis 2, and the sixth shaft 7 that is upside down by the rotation and a sixth shaft driving motor 9 (described later). 16 (see the right part in FIG. 16) can be returned to the normal posture by tilting the tilting arm 5 in the direction of arrow 28 by 180 degrees (FIG. 11B). See also)). Even if the above-described extra space 46 is secured, the separation distance _{Ltw from} the surroundings (work holding device 45) of the sixth shaft portion 7 can be left. Of course, it is possible to bring it closer to the workpiece. In the robot disclosed in the above-mentioned prior document, even if the arm body can be reversed, the motor of the sixth shaft portion is left on the surrounding object side, and the self-correction is not completed.

  In any case, the problem is that the control cables 10 and 11 for the motors 8 and 9 for individually driving the fifth shaft portion 6 shown in FIG. 12 and the sixth shaft portion 7 provided earlier than the fifth shaft portion 6 are shown. However, whether or not the upper arm 3 cannot be pulled as the rotation angle of the upper arm 3 is increased. Of course, as can be seen from (a) of FIG. 14, a loosening avoiding portion 12 for avoiding the pulling at the time of rotation of the upper arm 3 is provided on the outer periphery of the hollow drive shaft 3 </ b> C, and rotation of about ± 190 degrees is allowed. A length is provided that does not cause excessive tension in the control cable when following the rotation of the upper arm 3.

  Incidentally, the control cable covered with the protective tube 13 from the lower arm 34 up to the shoulder 20 to the vicinity of the connectors 23 and 24 including the slack portion 12 is a flange at the front end of the hollow drive shaft 3C. 16 is passed through a drawer portion 14 (see also FIG. 14B). In some cases, the clamp 17 is secured before the lead-out portion, so that the cable fluttering at the loosening-preventing slack portion 12 when the upper arm is rotated is suppressed, and from the lead-out portion 14 to the connectors 23 and 24. Consideration is made to reduce the damage of the cables 10 and 11 so that the influence of the rotation of the upper arm 3 is not significantly different from the left and right.

  Even if the control cable is laid in such a form, if the upper arm 3 is inverted and an attempt is made to ensure at least ± 180 degrees of rotation with reference to that, it is clear from the following description of FIG. Thus, the control cable must have a length that can withstand rotation of +180 degrees and -360 degrees. That is, the control cable is required to have a length that allows a total movement of 540 degrees.

When the drawer portion 14 is positioned on the upper side, the neutral position (represented as A ₀ ) is _{assumed to be} rotated ± 180 degrees (represented as A ₊₁₈₀ and A ₋₁₈₀ ) as shown in (b) and (c). The behavior is natural (changes from FIG. 14 (a) to FIG. 16 and FIG. 17), but (c) is regarded as neutral and rotated by ± 180 degrees (A ₋₁₈₀₊ ) as in (d) and (e). ₁₈₀ = A ₀ and A _{-180 -180} = A _-360 ) must be allowed. Although (d) has returned to (a), (e) has been rotated 360 degrees away from (a), and the control cable has a slack amount that can withstand 360 degrees. Must be secured.

  As described above, the control cable is not rotated more than ± 190 degrees from the viewpoint of suppressing twisting of the control cable, and it is not preferable to allow the rotation of 360 degrees although it is only on one side. In any case, in order to prevent the robot from over-rotating more than ± 190 degrees, a mechanical stopper mechanism such as a stopper 18 is usually attached to the shoulder 20 surrounding the hollow drive shaft 3C as shown in FIG. Is introduced.

  More specifically, a dog 19 is implanted in the hollow drive shaft 3C. When the dog 19 accompanying the rotation of the hollow drive shaft comes into contact with the stopper 18 projecting inward from the shoulder 20 from above or below, the hollow drive shaft 3C Further rotation of the shaft is prevented (see FIGS. 16 and 17).

  Since the stopper and dog are thick and the dog cannot rotate up to ± 180 degrees, some contrivance is applied. Briefly, as shown in FIG. 18A, an auxiliary ring 25 (see also FIG. 14) is fitted to a part of the outer periphery of the hollow drive shaft 3C, and a notch extending in the circumferential direction is provided at one portion thereof. 26 or a long groove is formed. The inner dog 19A planted in the hollow drive shaft 3C is allowed to face the notch 26, and the movement between them is allowed. The outer ring 19B is provided on the auxiliary ring 25. Even if the outer dog 19B is allowed to rotate less than 180 degrees by hitting the stopper 18, the inner dog 19A, that is, the hollow drive shaft 3C can rotate more than 180 degrees.

  According to the above description, even in the counterclockwise rotation from (a) to (b) in FIG. 18 to (c) and in the clockwise rotation from (a) to (d), it is about ± 190 degrees. The upper arm 3 can be rotated. However, if it is inverted as shown in FIG. 13 (b), that is, if it is inverted 180 degrees from (a) through (b) to (c) in FIG. Although it can be rotated about 190 degrees clockwise through (e) to (f), in the counterclockwise rotation as shown in (c) to (d), the outer dog 19B can be Collides with the stopper 18.

FIG. 20 shows a case where 180 degrees are reversed from (a) to (b) in the clockwise direction, but it is not possible to rotate counterclockwise by about 190 degrees from (b) through (c) to (d). Even if possible, in the clockwise rotation as shown in (b) to (e), the outer dog 19B collides with the stopper 18 before rotating 10 times. Even if the neutral is placed in the state of A ′ ₀ in FIG. 21A, that is, even if the inner dog 19A is positioned in the middle of the notch 26, it is obtained by reversing 180 degrees in the respective directions. FIG. 21 implicitly teaches that a rotation of ± 190 degrees starting from (c) and (e) is impossible as in the case of FIGS.

  As can be seen from the above description, the operation described with reference to FIG. 15 is impossible as long as there is a mechanical stopper that prevents excessive twisting of the control cable or the like. That is, even if the control cable can be given a length that can withstand rotation of +180 degrees to -360 degrees, the behavior of FIG. 19 and FIG. It becomes impossible.

  Even if it can be realized by any method, the control cable must allow rotation of -180 degrees, of course +180 degrees, and accordingly, the protective tube is attached to the outer surface of the hollow drive shaft at the slack for avoiding the pulling. Will increase the chances of rubbing. Deterioration of the control cable will progress in several months, and it will be necessary to increase the number of maintenance inspection opportunities, such as increasing the frequency of replacement.

In the above-mentioned patent document, the control cable is removed prior to reversing the arm body, and consideration is given not to accumulate excessive twist in the cable. However, the control cable is not limited to the fourth shaft portion. All subsequent parts are removed from the third shaft part in front of the third shaft part. In addition, a separation operation between the arm main body and each of the mechanisms ahead of the arm main body is also imposed. In consideration of these points, it is desirable to propose a self-guided procedure with fewer man-hours and a mechanism therefor.
JP 2002-370190 A

  The present invention has been made in view of the above problems, and its purpose is to offset the fourth axis as a reference axis during the robot operation when the surrounding objects such as the work holding device are forced to be arranged in the robot operation area. If there is a possibility that the arm body of the upper arm in the state may interfere with surrounding objects, offsetting it to the opposite side makes the movement of the arm body unaffected by surrounding objects, and a conduit that is likely to interfere with surrounding objects That is, the cable extension path can be kept unchanged even after inversion.

  Furthermore, it is not necessary to prepare a symmetrical arm body separately for reverse offset, and even if the arm body is turned 180 degrees, a rotation of ± 190 degrees, for example, prevents mechanical over-rotation. It is allowed without being disturbed by the stopper, and the control cable protected by over-rotation prevention should not be changed even if it is reversed. The present invention provides a robot wrist mechanism that realizes a reversal operation procedure that does not require a mechanism and a mechanism therefor, and a method for changing the left and right positions of a rotating arm.

  In the present invention, the arm body of the rotary arm that rotates around the reference axis is offset from the hollow drive shaft having the reference axis at the base end to one side of the reference axis so as to be along the reference axis. Extends and the tip of the arm body cantileverally supports a tilting arm that tilts about a crossing axis perpendicular to the reference axis, and if there is a crossing axis or any other shaft that precedes it, it can be driven individually The control cable of the motor to be applied is applied to a robot wrist mechanism that is laid so as to face each motor after leaving the slack portion for avoiding the squeezing at the time of rotation of the rotary arm at a part of the outer periphery of the hollow drive shaft. Referring to FIG. 1, the feature is that the drawer portions 14 and 15 that pass through the control cables 10 and 11 at the time of exiting from the hollow drive shaft 3C are 180 degrees apart from the arm body side end of the hollow drive shaft. Two places. The mounting portions 21 and 22 of the stopper 18 projecting inwardly from the shoulder 20 storing the hollow drive shaft 3C and contacting the arm over-rotation preventing dog 19 projecting from the surface of the hollow drive shaft 3C (FIG. 2) are provided 180 degrees apart. The control cables 10 and 11 are provided with connectors 23 and 24 that enable the cable to be disconnected between the drawer portion 14 and the corresponding motors 8 and 9.

  The invention of the method for rearranging the left and right rotating arms proceeds according to the following procedure. The arm body 3B is set to an intermediate reference position at which the right-hand swing limit rotation angle and the left-hand swing limit rotation angle are substantially equal. The connectors 23 and 24 interposed between the slack preventing slack portion 12 and the motors 8 and 9 to which the control cables 10 and 11 are connected are disconnected. The control cables 10 and 11 are removed from the lead-out portion 14 formed on the arm main body side end of the hollow drive shaft 3C, and the cable on the side of the slack portion for avoiding the twisting is made free. The arm body 3B is rotated 180 degrees to the right or left. The stopper 18 that protrudes inward of the shoulder 20 that houses the hollow drive shaft 3C is removed from the current mounting portion 21, and is replaced with an unused mounting portion 22 provided in the shoulder 20 at a distance of 180 degrees from the mounting portion. Then, after passing the cable on the side of the loosening portion for avoiding the pulling in the free state through the unused drawing portion 15 separated by 180 degrees from the drawing portion 14 from which the control cables 10 and 11 are removed, the connectors 23 and 24 are connected. This is what I did.

  Two pull-out sections that pass when the control cable exits the hollow drive shaft are provided 180 degrees apart on the arm drive side end of the hollow drive shaft, so the arm body is inverted to avoid interference with surrounding objects. However, the control cable can be exchanged with other drawers. Even if the necessary amount of rotation is performed on the basis of the drawer part, the extension route of the conduit cable is not changed, and the behavior of the control cable relative to the movement of the arm body can be made almost the same as before reversal, Eventually, it is not necessary to give an excessive amount of slack for avoiding pulling.

  Since the stopper mounting portions for contacting the arm over-rotation prevention dog are also provided at two positions separated by 180 degrees, the stoppers can be arranged using other mounting portions even if the arm body is reversed. Even when the left and right rotations are performed on the basis of the reverse direction, the torsional allowable amount of the control cable can still be secured substantially equal to the left and right, and the required rotation angle of the upper arm can be given in each rotation direction.

  This is because the control cable can be disconnected between the drawer and the motor by the connector, but this also allows the control cable to remain on the robot during the reversing operation, It is possible to provide a mechanism for changing the right hand with a simple structure, and to make the wrong operation extremely easy.

  In the left / right repositioning method of the rotating arm, the arm body is set to an intermediate reference position where the limit rotation angles in the left and right directions are approximately equal, the connector is disconnected, the control cable is removed from the drawer, and the arm body is rotated 180 degrees. Therefore, it is not necessary to remove the main attachment from the robot during the reversing operation of the arm body. If the stopper is changed from the current mounting portion to the unused mounting portion and the connector is connected, the reversing operation is very simple and no additional parts or jigs are required.

  Hereinafter, a method for changing the left and right positions of a robot wrist mechanism and a rotating arm according to the present invention will be described in detail with reference to the drawings showing the embodiments. FIG. 1A is an upper half view of a 6-axis arc welding robot 1 to which the present invention is applied. The general configuration is as described above with reference to FIGS. 11 to 14. In the present invention, the fourth axis 2 to be noted is referred to as a reference axis. The upper arm 3 that rotates about the axis is called a rotary arm, and the arm body 3B that constitutes the upper arm 3 is located at the base end of the hollow drive shaft 3C that has the reference axis 2 as the center and is on one side of the reference axis (toward To the right).

  A tilting arm 5 that tilts around a cross axis 4 orthogonal to the fourth axis 2 is cantilevered at the tip of the arm body 3B. The crossing axis is the fifth axis, and the motor 8 that individually drives the fifth axis 6 and the other axis provided before that, that is, the sixth axis 7 for turning the welding torch, Nine control cables 10 and 11 are laid to face each motor.

Then, as shown in FIG. 2, the rotary arm 3 is in the reference position of A ₀ from (a) to (b), or from (a) to (c), and to the left or right direction of (d). On the other hand, the slack avoiding loosening portion 12 (see FIG. 1A) is left on a part of the outer periphery of the hollow drive shaft 3C so that it can be rotated to a required angle. That is, a part of the control cable is covered with the protective tube 13, but is partially wound around the hollow drive shaft 3C before reaching the arm body 3B.

  Based on such a configuration, in the present invention, even if the reference posture of the rotary arm 3 is changed by 180 degrees, the extension route of the conduit cable (not shown) is not changed and the work is fixed. The main object is to allow the reference posture of the arm body 3B to be reversed by 180 degrees so that interference with surrounding objects such as the robot can be avoided. At that time, the torsional allowable amount of the control cable can be kept substantially equal to the left and right, and an increase in the slack amount of the control cable can be avoided as much as possible.

  The control cable is used for power supply, braking, grounding, position / speed torque control, sensor power, sensor data backup power supply, and the like, and is an indispensable cable together with a conduit cable for feeding a welding wire. Two lead-out portions 14 and 15 shown in FIG. 1 (b) that pass when the control cable is taken out to the arm body are provided at two positions separated by 180 degrees. These are a drawer 14 used when the arm body is in the position before reversal, and another drawer 15 used when it is in the position after reversal opposite to that. In either case, the portion of the control cable covered by the protective tube 13 is hooked as shown in FIG. 1A, and the behavior of the control cables 10 and 11 on the downstream side from the position with the rotation of the arm body 3B is observed. The intention is to keep things as small as possible.

  In addition, since the hollow drive shaft 3C is provided with the flange 16 for integrating the arm main body, it is possible to easily form the lead-out portions 14 and 15 by cutting out a part thereof. Naturally, since the lead-out portion is provided at the arm body side end of the hollow drive shaft 3C, even if the protective tube 13 is secured to the flange 16 by the clamp 17 at the front portion thereof, the above-described loosening-preventing slack portion 12 is hollow. It can be formed only on the outer peripheral surface of the drive shaft 3C.

  The drawer portions 14 and 15 provided on the flange 16 exert an effect of making the behavior of the control cables 10 and 11 independent with the flange 16 as a boundary. If the behavior on the hollow drive shaft side affects the control cable extending on the arm body side, or vice versa, the behavior of the cable becomes difficult to predict, and the control cable may become tangled unnecessarily. The pulling part contributes to the canopy in order to avoid the occurrence of a situation in which pulling that does not occur appears.

  It is a mechanical stopper that cannot be ignored in the sense that the arm body 3B is reversed and rotated left and right with reference to its posture. The stopper 18 protrudes inside the shoulder 20 that houses the hollow drive shaft so that the arm over-rotation prevention dog 19 protruding from the surface of the hollow drive shaft 3C is brought into contact therewith. As shown in FIG. 2 (a), the insertion ports 21 and 22 for screwing the stopper 18 are also provided at two positions apart from each other by 180 degrees in the same manner as the drawer portion.

  These are the insertion port 21 that is used when the arm body 3B is in the position before reversal, and another insertion port 22 that is used when the arm body 3B is in the opposite position. The stopper mounting portions 21 and 22 are provided on a shoulder casing or the like, but in FIG. 2, the shoulder skin is drawn thick for convenience. Actually, it is sufficient to form the screw seat on the outer surface or the inner surface in order to form the screwed portion. On the opposite side of 180 degrees, unlike the drawing, even if there is no outer skin at the corresponding position, a screw seat may be given to the bracket by standing or mounting a bracket suitable for forming the mounting portion. If the cover 20a behind the shoulder is opened, the stopper 18 can be inserted toward the mounting portion 22 (see FIG. 5A described later).

  On the other hand, the control cable is not required to be detached from the robot when the arm body is reversed, and unnecessary force or twisting is performed when the arm body is rotated left and right from the reversed state, which is an excessive rotation as seen from the state before the arm body is reversed. Separation is possible in the middle so as not to be applied. Therefore, as shown in FIG. 1 (a), each control cable 10, 11 has connectors 23, 24 that enable the cable to be disconnected between the drawer portions 14, 15 and the corresponding motors 8, 9. Intervened.

According to the robot wrist mechanism configured as described above, the left and right positions of the rotary arm can be changed as follows. First, even the arm body will allo in any position, even as C _i, for example in FIG. 3 (a), in a state where In'nadogu 19A is in contact with the upper end of the notch 26 of the auxiliary ring 25, (b ) Through (), the right and left limit rotation angles are adjusted to the intermediate reference position where the right and left limit rotation angles are substantially equal. This is the reference posture in the operation before reversing without reversing.

  Next, as shown in FIG. 4 (a), the connectors 23, 24 interposed between the slack preventing slack portion 12 and the motors 8, 9 to which the control cables 10, 11 are connected are disconnected. Remove the control cable covered with the protective tube 13 from the lead-out portion 14 of the flange 16 formed on the arm body side end of the hollow drive shaft 3C, remove the clamp 17, and loosen it for pulling avoidance as shown in (b). Leave the cable on the side free.

  Therefore, the upper arm 3 is reversed as shown in FIGS. This is also shown in FIG. For example, the arm body 3B is rotated 180 degrees in the left direction (counterclockwise rotation). At this time, since the control cables 10 and 11 are in a disconnected state, the fifth shaft motor 8 and the sixth shaft motor 9 are in an inoperative state. Since the control cable (not shown) of the fourth axis motor 27 is not disconnected, the upper arm can be rotated 180 degrees in any direction by operation with a teach pendant or the like. Of course, the control system can be released and rotated 180 degrees manually. It is not difficult if a scribing line is provided across the casing of the arm body and the casing of the shoulder to indicate the position before reversal and the position after reversal.

  When the fourth shaft is electrically operated and reversed, the fourth shaft motor can be braked thereafter, and the subsequent operation can be facilitated, which is convenient. The inverted arm body does not have to have exactly the same shape as before the inversion, but if the arm body is manufactured in advance vertically symmetrical, the appearance after the inversion can be kept unchanged. In other words, if the shape or paint is made different between up and down, it will be easier to tell whether the reference posture is before or after reversal.

  As shown in FIG. 5 (a), the stopper 18 protruding to the inside of the shoulder 20 that houses the hollow drive shaft 3C is removed from the current mounting portion 21, and the unused portion provided in the shoulder 180 degrees away from the mounting portion. Change to the mounting portion 22. FIG. 3E schematically shows this. If another stopper is prepared in advance, it can be removed at the current mounting portion and attached at the unused mounting portion at the same time. Finally, as shown in FIG. 5B, the protective tube 13 of the cable on the side of the loosening portion for avoiding the twisting in the free state is passed through the unused drawer portion 15 located above, and the connectors 23 and 24 are passed through. Connecting. When the cable is restored, the posture of the sixth axis motor 9 that is upside down is corrected by the tilt of the tilt arm 5 in the direction of the arrow 28.

  Before the reversal, the one rotated in the left-right direction as shown in FIGS. 6 and 7 is rotated as shown in FIGS. 8 and 9 after the reversal. In any case, if the reference posture after the reversal of the rotating arm is precisely given by the above-described series of operations for reversal and the control is reset so that this becomes the origin, there is a risk of interference before reversal. The arm body can be moved away from the surrounding object (from (a) to (b) in FIG. 13), and the torsional allowable amount of the control cable can be secured substantially equally from the left and right from the changed reference position. . In FIG. 8 described above, the movement of the upper arm 3 moves in the direction (b) with reference to FIG. 10 (a), and FIG. 9 goes from (a) to (c) in FIG. It is something that moves.

  In this way, the arm body is set to the intermediate reference position where the limit rotation angles in the left and right directions are substantially equal, the connector is disconnected, the control cable is removed from the drawer, and then the arm body is rotated 180 degrees to the right or left. By doing so, it is not necessary to remove the complicatedly wired control cable from the arm or to remove the main moving parts from the robot during the reversing operation of the arm body. The stopper is simply changed to the opposite side by 180 degrees, and if the connector is connected, the reversing operation is completed, and no special additional parts are required.

  As can be seen from the above detailed description, the conduit cable extension path does not change even if the required amount of rotation on the left and right sides of the drawer is changed before and after reversal. Depending on the complex movement of the robot, the conduit cable However, for example, what has deteriorated in a few months will greatly reduce the replacement frequency. The behavior of the control cable with respect to the movement of the arm body is almost the same as before the reversal, and there is no need to change the margin given to the cable.

  When the arm body is reversed, a stopper is installed on the mounting part that is positioned 180 degrees opposite, so that the torsion allowance of the control cable is still approximately equal to the left and right even when turning left and right with reference to the reverse The rotation angle of the upper arm is given in each rotation direction. The control cable can be disconnected between the drawer and the corresponding motor with a connector, so the control cable can be left on the robot at all times. Can be done.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a welding robot to which a robot wrist mechanism according to the present invention is applied, in which (a) is a perspective view of an upper half thereof, and (b) is an enlarged perspective view of a hollow drive shaft. Operation | movement explanatory drawing that a hollow drive shaft can rotate in each direction on either side from an initial state. The operation procedure figure which arranges the hollow drive shaft which existed in the arbitrary position to neutral, inverts 180 degrees after that, and changes a stopper. The procedure for rearranging the left and right rotation arms is shown, (a) is an initial state diagram, and (b) is a state diagram in which a control cable is completely released. FIG. 5A is an operation subsequent to FIG. 4, and FIG. 5A is a work diagram for moving the stopper to an unused mounting portion at a position different by 180 degrees, and FIG. FIG. 2 is a perspective view when the upper arm is rotated 180 degrees counterclockwise from the initial state of FIG. 1. FIG. 2 is a perspective view when the upper arm is rotated 180 degrees clockwise from the initial state of FIG. 1. The perspective view when an upper arm is rotated 180 degree | times counterclockwise on the basis of the time of reversed. The perspective view when an upper arm is rotated 180 degree | times clockwise on the basis of the time of being reversed. Operation | movement explanatory drawing of being able to rotate in each direction on the left and right from the inversion position after changing a stopper. FIG. 3A is a perspective view of an initial state in an installation state of an example of a welding robot, and FIG. The wrist mechanism which consists of the upper arm which showed the hollow drive shaft part of the welding robot in the cross section, the tilting arm, and the 6th axial part is represented, (a) is a top view, (b) is a front view. This represents a state in which a work holding device or the like is close to the side of the upper arm, (a) is a plan view of the arm body in a state where the possibility of interference is extremely high, and (b) is a state in which the possibility of interference is eliminated by a reversing operation. The top view of the arm main body. The laying state of the control cable in an upper arm is represented, (a) is a perspective view explaining connection with each motor side connector, (b) is a single perspective view of a hollow drive shaft. Explanatory drawing showing transition of rotation of a hollow drive shaft. The perspective view when an upper arm is rotated 180 degrees counterclockwise. The perspective view when an upper arm is rotated 180 degree | times clockwise. Explanatory drawing showing the transition of rotation of the hollow drive shaft at the time of presence of the stopper for excessive rotation prevention of a hollow drive shaft. Explanatory drawing of operation | movement when rotating an upper arm 180 degrees in the counterclockwise direction and rotating each right and left from the state. Operation | movement explanatory drawing when turning an upper arm 180 degree | times clockwise and trying to rotate to each right and left from the state. FIG. 5 is a reproduction diagram of a neutral state when the hollow drive shaft is reversed 180 degrees counterclockwise and clockwise when the initial state of the hollow drive shaft is slightly different.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Arc welding robot, 2 ... 4th axis (reference axis) 3 ... Upper arm (rotating arm), 3B ... Arm main body, 3C ... Hollow drive shaft, 4 ... Cross axis, 5 ... Tilt arm, 6 ... 5th axis , 7 ... 6th shaft part, 8, 9 ... Motor, 10, 11 ... Control cable, 12 ... Loosening prevention slack part, 14 ... Drawer part (active drawer part), 15 ... Drawer part (unused drawer part) ), 18 ... Stopper, 19 ... Arm over-rotation prevention dog, 19A ... Inner dog, 19B ... Outer dog, 20 ... Shoulder, 21 ... Insertion port (attachment portion: current attachment portion), 22 ... Insertion port (attachment portion: unused) Mounting portion), 23, 24... Connectors.

Claims (2)

The arm body of the rotating arm that rotates around the reference axis extends from the hollow drive shaft at the base end of the arm body, centered on the reference axis, offset to one side of the reference axis and extends along the reference axis. The tip of the arm body cantileverally supports a tilting arm that tilts around a crossing axis perpendicular to the reference axis, and if there is a crossing shaft or other shafts provided ahead of it, they are individually driven. In the robot wrist mechanism in which the motor control cable is laid so as to face each motor after leaving the slack portion for avoiding the pulling at the time of rotation of the rotary arm in a part of the outer periphery of the hollow drive shaft,
Two lead-out portions that pass when the control cable exits the hollow drive shaft are provided at two positions 180 degrees apart at the arm body side end of the hollow drive shaft,
Two stopper mounting portions that protrude from the shoulder that houses the hollow drive shaft and abut against the arm over-rotation prevention dog protruding from the surface of the hollow drive shaft are provided 180 degrees apart,
A robot wrist mechanism characterized in that each control cable is provided with a connector that enables the cable to be disconnected between the drawer and the corresponding motor. The arm body of the rotating arm that rotates around the reference axis extends from the hollow drive shaft at the base end of the arm body, centered on the reference axis, offset to one side of the reference axis and extends along the reference axis. The tip of the arm body cantileverally supports a tilting arm that tilts around a crossing axis perpendicular to the reference axis, and if there is a crossing shaft or other shafts provided ahead of it, they are individually driven. Left and right arrangement of the rotary arm in the robot wrist mechanism in which the motor control cable is laid so as to face each motor after leaving the slack portion for avoiding the pulling at the time of rotation of the rotary arm at a part of the outer periphery of the hollow drive shaft In the replacement method,
The arm body is set to an intermediate reference position in which the right-hand pull limit rotation angle and the left-hand pull limit rotation angle are substantially equal,
Detach the connector interposed between the slack portion for avoiding the twisting and the motor to which the control cable is connected,
Remove the control cable from the drawer part formed on the arm body side end of the hollow drive shaft, and free the cable on the slack part for pulling avoidance,
Rotate the arm body 180 degrees to the right or left,
Remove the stopper projecting from the inside of the shoulder housing the hollow drive shaft from the working mounting portion, and replace it with an unused mounting portion provided in the shoulder 180 degrees away from the mounting portion.
A robot wrist mechanism characterized in that the connector is connected after passing the cable on the side of the loosening portion for avoiding squeezing in a free state through an unused drawing portion separated by 180 degrees from the drawing portion from which the control cable has been removed. To change the left and right position of the rotating arm.

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