JP5502014B2 - Electrode abnormality detection device for automatic welding robot - Google Patents

Description

  The present invention relates to an automatic welding robot that performs welding with a welding torch, and more particularly, to an electrode abnormality detection device that can easily detect abnormality such as wear and displacement of electrodes arranged in a welding torch.

  It has a welding torch in which an electrode is disposed in the opening of the cylindrical tip, and a torch moving device that moves the welding torch three-dimensionally, and the welding torch is moved by the torch moving device. Automatic welding robots that perform welding are widely used in various welding fields. In such an automatic welding robot, the welding torch is moved to a predetermined abnormality inspection position by the torch moving device, and the electrode is brought into contact with a predetermined contact to detect an abnormality such as a positional deviation. Proposed. The apparatus described in Patent Document 1 is an example thereof, and a contact between a welding wire that is a consumable electrode and a contact is energized to detect contact therebetween. In addition, Patent Document 2 describes a positional deviation of an electrode when the electrode is replaced with respect to a welding torch used for plasma welding or TIG welding, which is a non-consumable electrode type arc welding method (see paragraph 6). ).

JP 2000-288733 A JP 2010-115669 A

  However, since the abnormality detection apparatus described in Patent Document 1 performs abnormality detection with the automatic welding robot itself, a dedicated program is required for each automatic welding robot and is inferior in versatility. Moreover, in patent document 1, in order to detect the presence or absence of contact with a contactor using the welding wire contact detection function with which the automatic welding robot is equipped, contact with a workpiece | work and an electrode is assumed like patent document 2. The technique described in Patent Document 1 cannot be applied to a welding torch used for non-consumable electrode type plasma welding or TIG welding that has not been performed to detect abnormalities such as misalignment.

  The present invention has been made against the background of the above circumstances, and its object is to easily detect abnormalities such as electrode misalignment of an automatic welding robot and to perform automatic welding by a non-consumable electrode type arc welding method. It is an object of the present invention to provide an electrode abnormality detection device excellent in versatility that can be easily applied to various automatic welding robots including robots.

  In order to achieve this object, the first invention has a welding torch in which an electrode is disposed in the opening of the cylindrical tip, and a torch moving device for moving the welding torch three-dimensionally. In the automatic welding robot that performs welding by moving the welding torch by the torch moving device, the electrode abnormality detecting device detects an abnormality related to the electrode, and (a) is arranged at a predetermined abnormality inspection position. A torch abutting member having a reference abutting surface against which the tip of the welding torch abutted and moved to the abnormality inspection position by the torch moving device; and (b) to the abnormality inspection position. A contact driving device for driving the contact disposed so as to face the electrode of the welding torch moved from a predetermined original position until it contacts the tip of the electrode; and (c) Contact A stroke sensor that detects a movement stroke St during the movement from the original position to a contact position that contacts the electrode, and (d) an abnormality determination unit that detects an abnormality related to the electrode based on the movement stroke St; It is characterized by having.

  According to a second aspect of the invention, in the electrode abnormality detection device for an automatic welding robot according to the first aspect of the invention, when the welding torch contacts the reference contact surface, the torch contact member is pushed and displaced by the welding torch. It is characterized by having a shock absorber that allows this.

  According to a third aspect of the present invention, there is provided the electrode abnormality detecting device for an automatic welding robot according to the first or second aspect of the invention, wherein (a) the welding torch abuts on the reference abutment surface provided on the torch abutment member (B) the abnormality determining means detects the contact of the welding torch with the reference contact surface by the contact detection sensor; The contactor is driven by a driving device to detect the movement stroke St, and an abnormality is determined based on the movement stroke St.

  According to a fourth aspect of the present invention, in the electrode abnormality detection device for an automatic welding robot according to any one of the first to third aspects, the abnormality determination means determines the wear limit of the electrode based on the movement stroke St. And

  According to a fifth aspect of the present invention, there is provided the electrode abnormality detecting device for an automatic welding robot according to the fourth aspect, wherein the abnormality determining means (a) moves the welding torch to the abnormality inspection position immediately after replacing the electrode. An initial position setting means for detecting the stroke St and setting the movement stroke St as an initial position Dp; and (b) moving the welding torch to the abnormal inspection position at a predetermined wear inspection timing, and A consumption amount detecting means for detecting St and obtaining a difference [St−Dp] between the movement stroke St and the initial position Dp as a consumption amount δ, and (c) the consumption amount δ is predetermined. It is characterized in that it is determined that the wear limit is greater than or equal to the wear limit value δs.

  According to a sixth aspect of the present invention, in the electrode abnormality detecting device for an automatic welding robot according to the fifth aspect of the invention, the consumption amount detecting means sets a next consumption inspection timing based on a difference between the consumption amount δ and the consumption limit value δs. It is characterized by that.

  A seventh aspect of the invention is the electrode abnormality detection device for an automatic welding robot according to any one of the first to sixth aspects of the invention. (A) A tip contact surface having a predetermined size is provided at the tip of the contactor. (B) Immediately after exchanging the electrode, the abnormality determining means moves the welding torch to the abnormality inspection position to detect the movement stroke St and moves the abnormality. When the stroke St is equal to or larger than a predetermined displacement determination value Ds, it is determined that the electrode is displaced in a direction parallel to the reference contact surface.

  In the fifth and seventh inventions, the term “immediately after replacing the electrode” may be after the electrode is replaced and before the welding operation is performed. In addition, the replacement of the electrode includes not only a case where the electrode is replaced with another new electrode but also a case where the same electrode is reused after re-polishing.

  In such an electrode abnormality detection device for an automatic welding robot, when the welding torch is moved to the abnormality inspection position by the torch moving device, its tip is brought into contact with the reference contact surface of the torch contact member, The contact driving device drives the contact from the original position until it contacts the tip of the electrode, and the movement stroke St of the contact at that time is detected by a stroke sensor. Based on the movement stroke St, the displacement of the electrode Abnormalities such as wear are automatically detected by the abnormality determining means. That is, the automatic welding robot only needs to move the welding torch to the abnormal inspection position by the torch moving device, and the contact driving device and the stroke sensor are disposed at the abnormal inspection position separately from the automatic welding robot. Also, the abnormality judgment means can be configured separately from the automatic welding robot and has excellent versatility that can be easily applied to various automatic welding robots regardless of the type of automatic welding robot such as non-consumable electrode type Is obtained. Further, since the contactor is driven until it abuts against the electrode, and the movement stroke St at that time only needs to be detected by the stroke sensor, the apparatus is simple and inexpensive.

  In the second invention, the welding torch is provided with a shock absorber that allows the welding torch to be displaced by being pushed by the welding torch when the welding torch contacts the reference contact surface. The impact applied to the torch moving device when contacting the contact surface is reduced, and the welding torch is always brought into contact with the reference contact surface without imposing a heavy load on the torch moving device. In addition, it is possible to improve the detection accuracy of abnormalities related to the electrodes.

  In the third invention, a contact detection sensor for detecting that the welding torch contacts the reference contact surface is provided on the torch contact member, and the contact detection sensor causes the welding torch to be connected to the reference contact surface. Since the movement stroke St is detected after the contact is detected and the abnormality of the electrode is determined, the abnormality determination is performed in a state where the welding torch is always in contact with the reference contact surface. Thus, the abnormality detection accuracy is improved. Further, since the contact detection sensor is provided on the torch contact member separately from the automatic welding robot, high versatility is maintained.

  4th invention-6th invention is related with the non-consumable electrode type welding torch substantially, such as plasma welding and TIG welding, and in order to determine the consumption limit of an electrode based on movement stroke St, the consumption limit of an electrode Will be automatically detected. Thereby, the welding failure etc. resulting from consumption of an electrode can be prevented appropriately. In addition, the electrode can be used to the limit as much as possible, compared with the case where the electrode is periodically replaced or re-polished according to the welding time, welding length, number of times of welding, etc. Thus, the operating rate of the automatic welding robot can be increased.

  In the fifth aspect of the invention, the welding torch is moved to the abnormality inspection position immediately after the electrode is replaced to detect the movement stroke St, and the movement stroke St is set as the initial position Dp, while the welding stroke is set at a predetermined consumption inspection timing. The torch is moved to the abnormality inspection position to detect the movement stroke St, and the difference [St−Dp] between the movement stroke St and the initial position Dp is obtained as the consumption amount δ, and the consumption amount δ is determined in advance. Since the exhaustion limit is determined when the exhaustion limit value δs or more, the exhaustion limit can be appropriately detected.

  In the sixth aspect of the invention, since the next wear inspection timing is set based on the difference between the wear amount δ and the wear limit value δs, it is possible to prevent the wear amount δ from significantly exceeding the wear limit value δs and causing poor welding or the like. However, the operating rate of the automatic welding robot can be increased by moving the welding torch to the abnormality inspection position and minimizing the number of times to determine the wear limit.

  According to the seventh aspect of the present invention, a tip contact surface of a predetermined size is provided at the tip of the contact, and immediately after replacing the electrode, the welding torch is moved to the abnormality inspection position to detect the movement stroke St, and the movement stroke Since it is determined that the electrode is displaced when St is greater than or equal to a predetermined displacement determination value Ds, the displacement of the electrode or the displacement of the welding torch itself is automatically detected. Thereby, the welding failure etc. by the position shift of an electrode or a welding torch can be prevented appropriately.

It is a schematic block diagram explaining an example of the automatic welding robot provided with the electrode abnormality detection apparatus which is one Example of this invention. It is a functional block diagram explaining the function regarding the abnormality determination of the electrode with which the electronic controller for abnormality detection of FIG. 1 is equipped. 3 is a flowchart for specifically explaining signal processing by various means in FIG. 2. FIGS. 2A and 2B are diagrams showing a contact state between the contact of the electrode abnormality detection device of FIG. 1 and the electrode immediately after replacement, in which FIG. 1A is a normal contact state without displacement and FIG. 1B is an electrode displacement. This is the contact state of the case. FIGS. 2A and 2B are diagrams for explaining an operation when determining an electrode wear limit with the electrode abnormality detection device of FIG. 1, in which FIG. 1A shows an initial position Dp immediately after electrode replacement, and FIG. FIG.

  The present invention is preferably applied to a non-consumable electrode type arc welding such as plasma welding or TIG welding, or a consumable electrode type arc welding welding torch in which a welding wire is used as an electrode. The present invention can be applied to various welding torches in which an electrode is disposed in the opening at the tip. The tip of the welding torch is generally cylindrical with a constant diameter, or tapered with a diameter that decreases toward the tip, and an electrode is disposed on the center line. The electrode generally has a longitudinal shape (cylindrical shape or wire) having a circular cross section, and is held concentrically in parallel with the center line of the tip of the torch. The tip of the electrode may be a circular flat surface cut at right angles to the axis, but in the case of a non-consumable electrode type arc welding torch, the taper shape gradually decreases in diameter toward the tip. Alternatively, a tapered shape such as a parabolic shape is appropriate.

  The electrode-related abnormality that can be detected by the electrode abnormality detection device of the present invention is, for example, a positional deviation in the direction perpendicular to the axial center of the electrode, a positional deviation in the axial direction, or a wear limit in the case of a non-consumable electrode. The positional deviation in the direction perpendicular to the axis of the electrode includes an abnormality in the case where each welding torch is displaced. As the torch moving device for moving the welding torch three-dimensionally, an articulated robot or a three-axis orthogonal robot that moves in the xyz direction perpendicular to each other is preferably used. The welding torch is moved to the abnormality inspection position by this torch moving device, and the tip is brought into contact with the reference contact surface. For example, the axial direction of the electrode (generally the same as the center line direction of the welding torch) It is desirable to move the welding torch to the reference contact surface. The reference contact surface is preferably perpendicular to the electrode axis (center line of the welding torch), and the tip of the welding torch contacts the reference contact surface evenly around the center line. It is desirable.

  The reference abutment surface is set upward, for example, parallel to the horizontal plane, and the welding torch having a posture in which the tip portion is directed downward is lowered straight from the upper side to the lower side in the vertical direction to bring it into perpendicular contact with the reference abutment surface. However, for example, the reference contact surface can be set to be perpendicular to the horizontal plane, and the welding torch in the horizontal orientation can be moved in the horizontal direction to contact the reference contact surface vertically. Is possible.

  The abnormality inspection position may be stored in advance in the control device of the automatic welding robot by teaching or the like. The contact driving device that contacts the tip of the electrode with the contact arranged to face the electrode of the welding torch moved to the abnormality inspection position is the axis of the electrode (the center line of the welding torch). ) Is configured to drive the contacts in parallel. The contact, for example, has a cylindrical shape, and is arranged in parallel with the axis of the electrode, that is, in parallel with the driving direction by the contact driving device, and is a flat circular tip perpendicular to the center line of the cylindrical shape. The contact surface is configured to contact the tip of the electrode. The contact drive device is configured to have a linear movement mechanism such as a feed screw mechanism, for example. When the wear limit is detected as in the fourth aspect of the invention, the tip of the contact does not necessarily have to be circular, but may be rectangular, oval, etc.

  According to the present invention, an electronic control device or the like provided separately from an automatic welding robot has a function of an abnormality determination means, and an electrode abnormality detection device is configured separately from the automatic welding robot, so that various automatic welding robots can be used. On the other hand, excellent versatility that can be easily applied is obtained, but it is also possible to give the function of the abnormality determination means to an electronic control device that controls the automatic welding robot. In that case, the operation of the contact driving device may be controlled by an electronic control device of an automatic welding robot and the electric signal of the stroke sensor may be supplied to the electronic control device.

  In the second aspect of the invention, a shock absorber is provided that allows the torch contact member to be displaced when the welding torch contacts the reference contact surface. For example, the welding torch contacts the reference contact surface. However, if the automatic welding robot is equipped with a torque limiter or the like so that an excessive load does not act, the shock absorber is not necessarily required. In the case of providing a shock absorber, it is desirable that the contact driving device and the stroke sensor are disposed on the torch contact member and moved integrally with the torch contact member. The shock absorber is configured using, for example, an elastic body such as rubber or a spring, or an air spring.

  In the third invention, a contact detection sensor for detecting that the welding torch has contacted the reference contact surface is provided. However, the contact detection sensor is not always necessary in the implementation of other inventions. It is also possible to estimate that the welding torch has come into contact with the reference contact surface from the operating state and elapsed time, and drive the contact by the contact driving device to detect the movement stroke St. As the contact detection sensor, for example, a touch sensor, a load sensor, a piezoelectric conversion element, or the like is preferably used.

  In the fifth invention, immediately after the electrode is replaced, the movement stroke St is detected, the initial position Dp is set, the amount of consumption δ is obtained based on the initial position Dp, and the consumption limit is determined, but when the electrode is replaced When there is no large variation in the axial position of the electrodes, it is not always necessary to set the initial position Dp, and when the movement stroke St detected at a predetermined consumption inspection timing exceeds a predetermined consumption limit movement stroke. You may make it determine with an exhaustion limit.

  In the sixth invention, the next wear inspection timing is set based on the difference between the wear amount δ and the wear limit value δs. In the fifth invention, for example, based on the welding time, the number of times of welding, or the welding length. It is also possible to perform a wear test at a predetermined interval. Further, at the initial stage of replacement of the electrode, the consumption amount δ is calculated by performing a consumption test at a predetermined interval (welding time, number of weldings, welding length, etc.) so as not to exceed the wear limit value δs. Then, from the next time, the consumption inspection timing can be set based on the change amount of the consumption amount δ. Also in the implementation of the sixth invention, the change history of the consumption amount δ is stored, and the next consumption inspection timing is determined based on the change amount of the consumption amount δ and the difference between the consumption amount δ and the consumption limit value δs. By setting, it is possible to set the wear inspection timing so as to minimize the number of wear inspections while preventing the occurrence of welding failure due to electrode wear, further improving the operating rate of the automatic welding robot be able to. For example, when the difference between the current consumption amount δ and the consumption limit value δs is large, the consumption inspection timing is set so that the consumption inspection interval becomes relatively long based on the change amount of the consumption amount δ, and the current consumption amount When the difference between δ and the consumption limit value δs becomes small, it is desirable to set the consumption inspection timing so that the consumption inspection interval becomes relatively short based on the change amount of the consumption amount δ.

  The tip contact surface of the contact according to the seventh aspect of the invention is suitably circular, and the diameter of the contact is appropriately set according to the allowable displacement. That is, the radius of the circular tip contact surface corresponds to the allowable positional deviation dimension. When the electrode has a simple cylindrical shape, the sum of the radial dimension of the electrode and the radial dimension of the tip contact surface of the contact becomes the allowable positional deviation dimension. In this case, since the contact between the contact and the electrode becomes impossible, the position deviation determination value Ds is appropriately set to a value larger than the normal movement stroke St in which the contact contacts the electrode. On the other hand, when the tip of the electrode has a tapered shape such as a tapered shape, if the position shifts beyond the radial dimension of the contact surface of the contact tip, the tip of the electrode is displaced from the contact surface of the contact tip and the travel stroke St gradually increases, and the movement stroke St increases in accordance with the position displacement dimension. Therefore, the positional deviation determination value Ds is appropriately set according to the radial dimension of the contact surface of the tip of the contact, the tapered shape of the electrode tip, and the allowable positional deviation dimension. In addition, when the position displacement direction of the electrode is biased in a substantially constant direction, the shape of the tip contact surface is appropriately determined, for example, the tip contact surface of the contact may be a square or the like.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic configuration diagram in which an electrode abnormality detection device 10 according to an embodiment of the present invention is disposed in an automatic welding robot 12. The automatic welding robot 12 includes a welding torch 14 that performs non-consumable electrode type arc welding such as plasma welding and TIG welding, and a torch moving device 16 such as an articulated robot that moves the welding torch 14 three-dimensionally. And a welding electronic control device 18 for controlling the operation of the welding torch 14 and the torch moving device 16, and arc welding is performed by moving the welding torch 14 according to a predetermined moving path. . An electrode 22 is detachably attached to the welding torch 14 by an unillustrated chuck or the like in the opening at the tip of the cylindrical nozzle 20. The electrode 22 is a cylindrical rod-like member, which has a tapered tip 24 and is held by the chuck or the like so that the axis S and the center line of the nozzle 20 are substantially coincident with each other. The electrode 22 is made of a heat-resistant conductor such as tungsten.

  The electrode abnormality detection device 10 includes a torch contact member 30 disposed at a predetermined abnormality inspection position in the vicinity of the automatic welding robot 12, that is, within a range in which the welding torch 14 is movable. The torch contact member 30 is provided with an upper block 34 having a substantially horizontal upward reference contact surface 32, an insulating plate 36 provided below the upper block 34, and further below the insulating plate 36. The lower unit base 38 is integrally fixed to each other, and the lower unit base 38 is disposed on the shock absorber 40. The shock absorber 40 supports the torch contact member 30 so that it can be displaced in the vertical direction by a predetermined amount of displacement, and is configured using an elastic body such as rubber or a spring, an air spring, or the like.

  The automatic welding robot 12 moves the welding torch 14 above the abnormality inspection position by the torch moving device 16 and lowers the nozzle 20 as indicated by the white arrow A in a vertically downward posture. The tip of the nozzle 20 is brought into contact with the reference contact surface 32 substantially perpendicularly. As a result, the electrode 22 held in the nozzle 20 is also positioned at the abnormality inspection position in a posture that is substantially parallel to the vertical direction and the tip portion 24 faces downward. In the welding electronic control unit 18 of the automatic welding robot 12, a movement path for moving the welding torch 14 to the abnormality inspection position is stored in advance by a teaching function or the like. The shock absorber 40 allows the torch contact member 30 to be pushed and displaced downward by the welding torch 14 when the welding torch 14 contacts the reference contact surface 32, and the shock at the time of contact. In addition, the contact state between the welding torch 14 and the reference contact surface 32 is ensured.

  On the other hand, the torch contact member 30 is provided with a bottomed hole 42 so as to open to the reference contact surface 32 of the upper block 34, and moves to the abnormality inspection position inside the bottomed hole 42. A contact 44 and a contact driving device 46 are disposed so as to face the electrode 22 of the welded torch 14. That is, the bottomed hole 42 is provided so as to penetrate the insulating plate 36 from the upper block 34 to the lower unit base 38, and the contact driving device 46 is disposed upward at the bottom of the bottomed hole 42. A cylindrical contact 44 is attached to the output rod 48 protruding upward. The contact driving device 46 is configured to have a linear moving mechanism such as a feed screw, and moves the contactor 44 in the vertical direction by rotating the feed screw in both forward and reverse directions with an electric motor, for example. It is controlled by the abnormality detection electronic control unit 60. The cylindrical contact 44 is disposed on the output rod 48 in such a posture that the center line O is in a substantially vertical direction, and the upper end (tip) thereof is a flat circular shape that is substantially perpendicular to the center line O. A tip contact surface 50 is provided, and when driven upward from the original position indicated by the solid line in FIG. 1, the tip contact surface 50 is brought into contact with the tip of the electrode 22 as indicated by the alternate long and short dash line. It is done. When the contact driving device 46 reaches the contact position where the contact 44 contacts the electrode 22, the contact driving device 46 stops further driving of the contact 44 based on the load (resistance). When the electrode 22 is correctly attached to the welding torch 14, the contact 44 is moved to the abnormality inspection position so that the axial center S of the electrode 22 as shown in FIG. The center line O is disposed at a position that substantially coincides with the center line O.

  The reference contact surface 32 is provided with a touch sensor 52 that outputs an electrical signal (contact signal) when the tip of the welding torch 14 is brought into contact with the reference contact surface 32. Is provided with a stroke sensor 54 for detecting a moving stroke St when the contactor 44 moves from the original position (lower end) to the contact position (upward end). The touch sensor 52 corresponds to a contact detection sensor, and includes, for example, a pressure sensitive conductor. The stroke sensor 54 may detect the amount of linear movement of the output rod 48 or may detect the amount of rotation of a feed screw that linearly moves the output rod 48. The detection signals of the touch sensor 52 and the stroke sensor 54 are supplied to the abnormality detection electronic control device 60 that detects the positional deviation and the wear limit of the electrode 22. The abnormality detection electronic control device 60 is also connected to a display device 56 such as an abnormality display lamp or a buzzer, and displays an abnormality when a position shift or a wear limit is detected.

  Each of the abnormality detection electronic control device 60 and the welding electronic control device 18 includes a microcomputer having a CPU, a RAM, a ROM, an input / output interface, and the like, and can exchange necessary information with each other. It is connected so that signal transmission is possible via a signal cable or radio. The information output from the abnormality detection electronic control device 60 to the welding electronic control device 18 includes, for example, a movement command for moving the welding torch 14 to the abnormality inspection position in order to detect an abnormality of the electrode 22, and the like. The information supplied from the device 18 to the abnormality detection electronic control device 60 includes, for example, a signal indicating that the electrode 22 has been automatically replaced, the welding time and the number of weldings necessary for determining the wear inspection timing of the electrode 22, and welding. Information about length, etc.

  As shown in FIG. 2, the abnormality detection electronic control device 60 functionally includes a movement command means 62, an inspection position determination means 64, and an abnormality determination means 70. The abnormality determination unit 70 further includes a stroke detection unit 72, a position deviation determination unit 74, an initial position setting unit 76, a consumption amount detection unit 78, and a consumption determination unit 80. FIG. 3 is a flowchart specifically explaining signal processing executed by the various functions shown in FIG. 2. Step S5 corresponds to the movement command means 62, step S6 corresponds to the inspection position determination means 64, and step S7. Is equivalent to the stroke detection means 72, steps S1, S9, S13 are equivalent to the positional deviation determination means 74, steps S1, S10 are equivalent to the initial position setting means 76, and steps S3, S11, S15, S17 are consumption amounts. Steps S <b> 16 and S <b> 19 correspond to the consumption determination unit 80.

  In step S1 of FIG. 3, it is determined whether or not the electrode 22 of the welding torch 14 has been replaced. If the electrode 22 has been replaced, step S2 and subsequent steps are executed. If not, step S3 is executed. The electrode 22 may be replaced either when the electrode 22 is replaced with a new one, or when the tip 24 of the electrode 22 is polished and reused. When the electrode is automatically replaced by the welding electronic control unit 18, Based on the electrode replacement information, the determination in step S1 is YES. In addition, when the electrode replacement is performed manually by an operator, the electrode replacement may be input by operating a switch or the like (not shown). When the electrode is exchanged, the electrode exchange flag F is set to 1 in step S2, and then step S5 and subsequent steps are executed. In step S3, it is determined whether or not it is a predetermined consumption inspection timing for inspecting the consumption of the electrode 22, and if it is not the consumption inspection timing, the process ends. If it is the consumption inspection timing, the electrode replacement flag F is set in step S4. After setting to 0, step S5 and subsequent steps are executed. The consumption inspection timing is set in steps S11 and S17.

  In step S <b> 5, a movement command for moving the welding torch 14 to the abnormality inspection position is output to the welding electronic control device 18. In step S6, it is determined whether or not the welding torch 14 has been moved to the abnormality inspection position. Specifically, it is determined whether the tip of the welding torch 14 is in contact with the reference contact surface 32 of the torch contact member 30 and a contact signal is supplied from the touch sensor 52. Then, when it is detected by the touch sensor 52 that the welding torch 14 has reached the abnormality inspection position, step S7 is performed, and the contact 44 is driven upward from the original position by the contact driving device 46 to thereby drive the electrode 22. The movement stroke St from the original position to the contact position is detected by a signal supplied from the stroke sensor 54.

  In the next step S8, it is determined whether or not the electrode replacement flag F is 1. In the case of F = 1, that is, immediately after the electrode replacement in which F = 1 is set in step S2, step S9 and the following are executed. If F = 1 is not satisfied, that is, if the wear inspection timing is F = 0 in step S4, step S15 and subsequent steps are executed. In step S9, whether the electrode 22 is displaced in a direction parallel to the reference contact surface 32, that is, a direction perpendicular to the axis S, depending on whether or not the movement stroke St is greater than or equal to a preset displacement determination value Ds. Judge whether or not. FIG. 4A shows the case where the electrode 22 is correctly positioned at the abnormality inspection position, that is, the case where the axis S of the electrode 22 and the center line O of the contactor 44 are substantially coincident with each other. The tip is brought into contact with the approximate center of the tip contact surface 50 of the contactor 44. On the other hand, FIG. 4B shows that the axis S of the electrode 22 is perpendicular to the axis S by a displacement φ (> radius r of the tip contact surface 50) with respect to the center line O of the contact 44. When the tip end of the electrode 22 is deviated from the tip contact surface 50 of the contactor 44, the moving stroke St of the contactor 44 is increased by the dimension e as compared with the case (a). . Therefore, according to the radius r of the tip contact surface 50, the taper angle of the tip 24 of the electrode 22, and the allowable displacement dimension φmax, the moving stroke St when the displacement dimension φ reaches the allowable displacement dimension φmax is expressed as follows: What is necessary is just to set beforehand as the said position shift determination value Ds. The allowable positional deviation dimension φmax is appropriately determined according to the required accuracy with respect to the welding position (line). The radius r of the tip contact surface 50 is appropriately set according to the allowable positional deviation dimension φmax, the taper angle of the tip 24, etc., and is about 0.5 mm in this embodiment. In this embodiment, the contactor 44 has a cylindrical shape with a fixed diameter, but it is also possible to provide a small-diameter columnar part at the tip (upper end) or a frustoconical part. is there.

  If the determination in step S9 is YES (positive), that is, if St ≧ Ds, it is determined that the electrode 22 is misaligned, and the misalignment display lamp of the display device 56 is turned on or a buzzer is turned on in step S13. To inform the operator that the electrode 22 is misaligned. The displacement of the electrode 22 is not only when the electrode 22 is displaced relative to the welding torch 14 but also when the welding torch 14 itself is displaced, that is, for welding by the welding electronic control unit 18. This includes abnormalities related to positioning control of the torch 14. In step S <b> 14, a stop command for stopping the operation of the automatic welding robot 12 is output to the welding electronic control device 18.

  On the other hand, if the determination in step S9 is NO (No), that is, if the electrode 22 is not misaligned with St <Ds, specifically, if the misalignment dimension φ is within the allowable misalignment dimension φmax, step S10 And the moving stroke St at that time is set as an initial position Dp that serves as a reference when the consumption amount δ of the electrode 22 is obtained. For example, FIG. 5 (a) shows that the displacement dimension φ≈0 immediately after electrode replacement, the moving stroke St is smaller than the displacement determination value Ds, the determination in step S9 is NO, and step S9 follows. When step S10 is executed, the movement stroke St is set as the initial position Dp. In the next step S <b> 11, initial setting of a consumption inspection timing for detecting consumption of the electrode 22 is performed. The wear inspection timing is determined by the welding time, the number of times of welding, or the welding length until the consumption stroke δ of the electrode 22 is detected after obtaining the movement stroke St, and the electrode 22 reaches the wear limit value δs regardless of the welding conditions. A constant value is set in advance so that there is no such thing. It is also possible to update this initial set value by learning correction or the like. In the next step S12, a movement command for returning the welding torch 14 from the abnormality inspection position to the original position by the automatic welding robot 12 is output to the welding electronic control unit 18, and a series of electrode abnormality detection processing is completed. .

  When the determination in step S8 is NO, that is, in the case of the consumption inspection timing with the electrode replacement flag F = 0, first, step S15 is executed, and the movement stroke St detected in step S7 and the initial position Dp set in step S10. [St-Dp] is calculated as a consumption amount δ. FIG. 5B shows a state in which the tip of the electrode 22 is consumed by the consumption amount δ and the movement stroke St is larger than the initial position Dp by the consumption amount δ as compared with FIG. In the next step S16, it is determined whether or not the electrode 22 has reached the wear limit depending on whether or not the wear amount δ is greater than or equal to a predetermined wear limit value δs. The wear limit value δs is appropriately set with a predetermined margin so that arc welding cannot be performed properly due to wear of the electrode 22 and welding failure does not occur.

  If the determination in step S16 is YES (positive), that is, if δ ≧ δs, it is determined that the electrode 22 has reached the wear limit, and the wear limit display lamp of the display device 56 is turned on in step S19. A buzzer is sounded to inform the operator that the electrode 22 is at the wear limit. In step S20, a stop command for stopping the operation of the automatic welding robot 12 is output to the welding electronic control unit 18. On the other hand, if the determination in step S16 is NO (negative), that is, if δ <δs and the electrode 22 has not yet reached the wear limit, step S17 is executed, and then the wear inspection timing for detecting wear of the electrode 22 Set. The wear inspection timing is the welding time, the number of times of welding, or the welding length until the movement stroke St is obtained and the wear amount δ of the electrode 22 is detected as in step S11, and greatly exceeds the wear limit value δs. It is determined as appropriate based on the change history of the consumption amount δ, the difference between the current consumption amount δ and the consumption limit value δs, and the like so that the number of inspections for consumption is minimized while avoiding the occurrence of welding defects. For example, when the difference between the current consumption amount δ and the consumption limit value δs is large, the consumption inspection timing is set so that the consumption inspection interval becomes relatively long based on the change amount of the consumption amount δ, and the current consumption amount When the difference between δ and the wear limit value δs becomes small, the wear inspection timing is set so that the wear inspection interval becomes relatively short based on the change amount of the wear amount δ. In the next step S18, a movement command for returning the welding torch 14 from the abnormal inspection position to the original position by the automatic welding robot 12 is output to the welding electronic control unit 18, and a series of electrode abnormality detection processing is completed. .

  In the electrode abnormality detecting device 10 of the automatic welding robot 12 of this embodiment, when the welding torch 14 is moved to the abnormality inspection position by the torch moving device 16, the tip portion thereof is the reference of the torch contact member 30. The contact 44 is brought into substantially vertical contact with the contact surface 32, and the contact 44 is driven upward from the original position by the contact drive device 46 to be brought into contact with the tip of the electrode 22, and the moving stroke of the contact 22 at that time St is detected by the stroke sensor 54, and the positional deviation and the wear limit of the electrode 22 are automatically detected by the abnormality detection electronic control device 60 based on the movement stroke St. That is, the automatic welding robot 12 only has to move the welding torch 14 to the abnormality inspection position by the torch moving device 16, and the contact driving device 46 and the stroke sensor 54 are independent of the automatic welding robot 12 from the abnormality inspection position. The abnormality detecting electronic control device 60 having the function of the abnormality determining means 70 and the like is also provided separately from the welding electronic control device 18 of the automatic welding robot 12, and thus the automatic welding robot 12. Excellent versatility that can be easily applied to various types of automatic welding robots regardless of the type. Further, since the contactor 44 is driven and brought into contact with the electrode 22 and the movement stroke St at that time only needs to be detected by the stroke sensor 54, the electrode abnormality detection device 10 is configured simply and inexpensively.

  Further, in this embodiment, the shock absorber 40 is provided that allows the torch contact member 30 to be displaced downward by being pushed by the welding torch 14 when the welding torch 14 contacts the reference contact surface 32. Therefore, the impact applied to the torch moving device 16 when the welding torch 14 contacts the reference contact surface 32 is reduced, and the welding torch 14 is always attached without applying a large load to the torch moving device 16. It is possible to reliably contact the reference contact surface 32. As a result, the movement stroke St of the contact 44 driven to the contact position contacting the electrode 22 by the contact driving device 46 disposed on the torch contact member 30 is always detected with high accuracy. The detection accuracy of the abnormality relating to the electrode 22 based on the movement stroke St is improved.

  In this embodiment, a touch sensor 52 that detects that the welding torch 14 has come into contact with the reference contact surface 32 is provided on the reference contact surface 32, and the touch sensor 52 allows the welding torch 14 to be connected to the reference contact surface 32. After detecting the contact with the reference contact surface 32, the movement stroke St is detected to determine whether the electrode 22 is abnormal. Therefore, the welding torch 14 is always reliably contacted with the reference contact surface 32. Thus, abnormality determination is performed, and abnormality detection accuracy is improved. Moreover, since the touch sensor 52 is provided in the torch contact member 30 separately from the automatic welding robot 12, high versatility is maintained.

  Further, this embodiment is applied to an automatic welding robot 12 having a non-consumable electrode type welding torch 14 such as plasma welding or TIG welding, and the consumption amount δ is calculated based on the moving stroke St. In order to determine the wear limit of the electrode 22 (steps S16 and S19), the wear limit of the electrode 22 is automatically detected. Thereby, the welding failure etc. resulting from consumption of the electrode 22 can be prevented appropriately. In addition, the electrode 22 can be used as much as possible as compared with the case where the electrode 22 is periodically replaced or re-polished depending on, for example, the welding time, the welding length, the number of weldings, and the like. As a result, the operating rate of the automatic welding robot 12 can be increased.

  In this embodiment, immediately after the electrode 22 is replaced, the welding torch 14 is moved to the abnormality inspection position to detect the movement stroke St, and the movement stroke St is set as the initial position Dp (step S10). The welding torch 14 is moved to the abnormality inspection position at a predetermined consumption inspection timing to detect the movement stroke St, and the difference [St−Dp] between the movement stroke St and the initial position Dp is obtained as the consumption amount δ ( In step S15), when the consumption amount δ is greater than or equal to a predetermined consumption limit value δs, it is determined that the consumption limit is reached (steps S16 and S19), so that the consumption limit can be detected appropriately.

  In the present embodiment, when the next wear inspection timing is set in step S17, the wear amount δ is determined based on the change history of the wear amount δ, the difference between the current wear amount δ and the wear limit value δs, and the like. The wear inspection timing is determined so as to minimize the number of times that the wear limit is determined by moving the welding torch 14 to the abnormal inspection position while preventing the occurrence of poor welding or the like by significantly exceeding the wear limit value δs. Therefore, the operation rate of the automatic welding robot 12 can be increased.

  Further, in this embodiment, a tip contact surface 50 having a predetermined size is provided at the tip of the contactor 22, and immediately after the electrode 22 is replaced, the welding torch 14 is moved to the abnormality inspection position to set the moving stroke St. In order to detect that the electrode 22 is displaced when the movement stroke St is greater than or equal to a predetermined displacement determination value Ds (steps S9, S13), the displacement of the electrode 22 or the welding torch 14 is determined. The displacement of itself is automatically detected. Thereby, the welding failure etc. by the position shift of the electrode 22 or the welding torch 14 can be prevented appropriately.

  As mentioned above, although the Example of this invention was described in detail based on drawing, this is an embodiment to the last, and this invention is implemented in the aspect which added various change and improvement based on the knowledge of those skilled in the art. Can do.

  10: Electrode abnormality detection device 12: Automatic welding robot 14: Torch for welding 16: Torch moving device 22: Electrode 30: Torch contact member 32: Reference contact surface 40: Shock absorber 44: Contact 46: Contact drive device 50: Tip contact surface 52: Touch sensor (contact detection sensor) 54: Stroke sensor 60: Electronic controller for abnormality detection 70: Abnormality determination means 72: Stroke detection means 74: Misalignment determination means 76: Initial position setting means 78: Consumption amount detection means 80: Consumption determination means St: Movement stroke φ: Position displacement dimension Dp: Initial position δ: Consumption amount

Claims (7)

A welding torch in which an electrode is disposed in an opening of a cylindrical tip, and a torch moving device for moving the welding torch three-dimensionally, and the welding torch is moved by the torch moving device; In an automatic welding robot that performs welding, an electrode abnormality detection device that detects abnormality relating to the electrode,
A torch contact member having a reference contact surface that is disposed at a predetermined abnormality inspection position and is brought into contact with the tip of the welding torch moved to the abnormality inspection position by the torch moving device; ,
A contact driving device that drives a contact disposed so as to face the electrode of the welding torch moved to the abnormality inspection position from a predetermined original position until it contacts the tip of the electrode. When,
A stroke sensor that detects a movement stroke St while the contact moves from the original position to a contact position that contacts the electrode;
An abnormality determining means for detecting an abnormality related to the electrode based on the moving stroke St;
An electrode abnormality detection device for an automatic welding robot characterized by comprising: 2. The shock absorber according to claim 1, further comprising a shock absorber that allows the welding torch to be displaced by being pushed by the welding torch when the welding torch contacts the reference contact surface. Electrode abnormality detection device for automatic welding robot as described. A contact detection sensor provided on the torch contact member for detecting that the welding torch has contacted the reference contact surface;
The abnormality determination means drives the contact by the contact driving device to detect the movement stroke St after the contact detection sensor detects that the welding torch contacts the reference contact surface. The abnormality detection device for an automatic welding robot according to claim 1 or 2, wherein the abnormality is detected and an abnormality is determined based on the movement stroke St. The said abnormality determination means determines the wear limit of the said electrode based on the said movement stroke St. The electrode abnormality detection apparatus of the automatic welding robot of any one of Claims 1-3 characterized by the above-mentioned. The abnormality determining means includes
Initial position setting means for detecting the movement stroke St by moving the welding torch to the abnormality inspection position immediately after replacing the electrode, and setting the movement stroke St as an initial position Dp;
The welding torch is moved to the abnormality inspection position at a predetermined consumption inspection timing to detect the movement stroke St, and a difference [St−Dp] between the movement stroke St and the initial position Dp is determined as a consumption amount δ. Consumption amount detection means to be obtained as
5. The electrode abnormality detection device for an automatic welding robot according to claim 4, wherein the wear limit is determined when the wear amount δ is equal to or greater than a predetermined wear limit value δs. 6. The electrode abnormality detection device for an automatic welding robot according to claim 5, wherein the consumption amount detection means sets a next consumption inspection timing based on a difference between the consumption amount δ and the consumption limit value δs. . A tip contact surface having a predetermined size is provided in parallel to the reference contact surface at the tip of the contact,
The abnormality determination means detects the movement stroke St by moving the welding torch to the abnormality inspection position immediately after replacing the electrode, and the movement stroke St is equal to or greater than a predetermined displacement determination value Ds. The electrode abnormality detection device for an automatic welding robot according to any one of claims 1 to 6, wherein the electrode is determined to be displaced in a direction parallel to the reference contact surface. .

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