JP2006175495A - Electrode tip adjusting device, and electrode tip changing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the efficiency of welding work by elongating the time interval for changing electrode tips. <P>SOLUTION: A tip projection adjusting section 72 in an electrode tip adjusting and changing device 12 comprises a first lock nut turning tool 73 for turning a lock nut 44 in the clockwise and counterclockwise directions with respect to a chuck body 40 in the state that the lock nut 44 of an electrode tip holder 10 is oriented downward, and a projection specifying piece 74 provided below the lock nut 44 on the axis by a specified distance when the lock nut 44 is turned by means of the first lock nut turning tool 73. When the lock nut 44 has been loosened, the tip end portion of the electrode tip 46 is brought into contact with the projection specifying piece 74 and uprightly stands still, and the electrode tip 46 is projected from the electrode tip holder 10 by the specified distance. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electrode tip adjusting device and an electrode tip changing device for adjusting and exchanging an electrode tip with respect to an electrode tip holder for holding an electrode tip used in an electric welding operation.

  For example, in a vehicle manufacturing factory, in order to efficiently perform a large amount of spot welding on the outer plate and frame of a vehicle, an industrial robot equipped with an electrode tip holder is used to automate a considerable part of the welding work. is doing.

  By the way, since the electrode tip mounted on the electrode tip holder is inevitably consumed due to discharge or the like, the tip is polished at an appropriate interval, and when the consumption becomes more severe, the electrode tip is replaced. Although this replacement work may be performed manually with the robot stopped, manual replacement may cause inefficiencies due to variations in work time for each worker, automating the replacement work and shortening the replacement time. Is desired. In addition, since the welding operation is interrupted while the replacement operation is being performed, it is desired to reduce the number of electrode tip replacements.

  In order to automatically replace the electrode tip, there is a method in which a tip punching plate is engaged with the end of the electrode tip, the electrode tip is clamped and fixed by a clamp mechanism, and then the robot is operated to remove the electrode tip from the shank. It has been proposed (see, for example, Patent Document 1). In this method, after that, a new electrode chip is mounted on a predetermined chip stand.

  On the other hand, since the electrode tip becomes very high at the time of welding, it is necessary to perform appropriate cooling from the viewpoint of preventing damage and improving welding efficiency. For example, in the spot welding electrode described in Patent Document 2, Cooling liquid is supplied to the inside of the tip electrode tip. In addition, the resistance welding electrode described in Patent Document 3 includes an electrode holder that is in electrical contact with the electrode tip, and the electrode tip is indirectly cooled by supplying a coolant to the inside of the electrode holder.

Japanese Patent No. 3347436 JP 2001-9575 A Japanese Patent Publication No.8-111305

  The electrode tip applied to the tip changer in Patent Document 1 is fixed to the shank using frictional force due to the biting of the tapered shapes, and exchange work is performed on electrode tips of other shapes. I can't. Further, when biting friction is used, it is necessary to push the electrode tip with a considerably strong force, so that a large load is applied to the electrode tip and the shank, and the life is shortened. Further, it requires fine adjustment of the force for pushing the electrode tip, and if it is pushed with an excessive force, it cannot be removed. If the force is too small, the electrode tip may be unintentionally removed during work.

  Since the electrode tip is a consumable item, it is desirable that the electrode tip be inexpensive. However, when supplying the coolant to the inside of the electrode tip in Patent Document 1, it is necessary to process the surfaces of both tapered surfaces with high accuracy in order to keep the taper surfaces in contact with each other. Invite soaring. In practice, it may be necessary to perform so-called actual matching in order to make the tapered surfaces have an appropriate liquid-tight structure due to insufficient accuracy. Furthermore, the shank is exposed when the electrode tip is replaced, and the tapered surface may be damaged, and the damaged shank must be replaced.

  The electrode tip in Patent Document 2 is a small one that is attached to the tip of the shank, and the location that is effectively used as an electrode because it is necessary to provide a shank connection part and a flow passage hole for the coolant is limited to a small range of the tip. Exchanges due to wear must be made frequently. Moreover, since the shank connection portion is not used as an electrode, there is a lot of material waste.

  Also in the electrode tip in Patent Document 3, there are many portions that are not used as electrodes such as heat pipes, rings, hard spheres, and elastic bodies for connection to the electrode holder, and there is a lot of waste when discarding the electrode tip. Further, since the electrode tip is held by an elastic force, there is a concern that the electrode tip may be detached or inclined when the workpiece is held with a strong force.

  The present invention has been made in view of such problems, and can increase the efficiency of the overall welding operation by extending the interval between electrode tip replacements or shortening the time required for electrode tip replacement. An object of the present invention is to provide an electrode tip adjusting device and an electrode tip changing device.

  The electrode tip adjustment device according to the present invention includes a chuck body having a tapered inner peripheral surface in which an inner diameter hole expands toward a tip, a cylindrical lock nut screwed into a thread portion of the chuck body, and the inner diameter hole A collet that holds the rod-shaped electrode tip inserted into the inner diameter portion by being pressed in the axial direction when the lock nut is screwed into the screw portion, and the split stitch is elastically deformed to be reduced in diameter. A lock nut rotating means for rotating the lock nut in the left-right direction with respect to the chuck body in a state where the lock nut is directed downward, and the lock nut by the lock nut rotating means And a protruding amount defining piece provided on the shaft below the lock nut by a defined length.

  When the lock nut is rotated in the direction of loosening the lock nut by the lock nut rotating means, the electrode tip descends by its own weight and comes into contact with the protruding amount defining piece, so that an appropriate protruding amount is obtained. Thereafter, the electrode tip is held by the collet when it is rotated by the lock nut rotating means in the direction of tightening the lock nut. Therefore, since the amount of protrusion is automatically adjusted without changing the electrode tip, the number of electrode tip replacements is reduced, and the efficiency of the overall welding operation can be improved.

  The electrode tip exchange device according to the present invention includes a chuck body having a tapered inner peripheral surface whose inner diameter hole expands toward the tip, a cylindrical lock nut that is screwed into a threaded portion of the chuck body, and the inner diameter hole. A collet that holds the rod-shaped electrode tip inserted into the inner diameter portion by being pressed in the axial direction when the lock nut is screwed into the screw portion, and the split stitch is elastically deformed to be reduced in diameter. The electrode tip holder is lowered and the electrode tip holder is lowered in a state where the lock nut is directed downward and the electrode tip is removed, and the electrode is installed upright at a predetermined loading position. A lowering insertion means for inserting a tip into the collet; and the lock nut is attached to the chuck body in a state where the electrode tip is inserted into the collet by the lowering insertion means. Characterized in that it comprises a lock nut rotating means for rotating to screw it to.

  In this way, after the electrode tip is pulled out, the electrode tip is lowered by the lowering insertion means to be inserted into the collet, and then the lock nut is rotated by the lock nut rotating means to easily and quickly remove the electrode tip. Can be installed. Therefore, the replacement work of the electrode tip is shortened, and the overall efficiency of the welding work can be improved.

  The lock nut rotating means includes a movable means that can be programmed to move and rotate the electrode tip holder, and a fixed tool that engages with an outer diameter portion of the lock nut, and the fixed tool and the lock nut are engaged. The lock nut may be rotated relative to the chuck body by rotating the electrode tip holder by the moving means in the combined state. By using the movement means that can be programmed in this way, an appropriate operation corresponding to the position and orientation of the fixed tool can be easily realized, and a simple tool such as a spanner is adopted as the fixed tool. Can do.

  In addition, the automatic loading unit includes an automatic loading unit configured to vertically install another electrode chip at the loading position after the electrode chip holder with the electrode chip mounted is separated from the loading position by the moving unit. The means may include a cartridge that holds a plurality of electrode tips in a line and holds them upright, and a feed mechanism that intermittently feeds the cartridges so that the electrode tips are sequentially arranged at the loading position. Thus, not only the electrode tip replacement work but also the loading work is automated with a simple configuration, and the efficiency of the welding work can be improved by saving labor.

  According to the electrode tip adjustment device according to the present invention, the electrode tip is applied to the electrode tip holder, and by loosening the lock nut, the electrode tip descends by its own weight and comes into contact with the projection amount defining piece so that the proper projection amount is obtained. It becomes. Therefore, the protrusion amount is automatically adjusted without changing the electrode tip, and the number of electrode tip replacements is reduced, so that the efficiency of the overall welding operation can be improved.

  Furthermore, according to the electrode tip exchange device according to the present invention, the electrode tip is inserted into the collet by being applied to the electrode tip holder, and lowering the electrode tip by the lowering insertion means after removing the electrode tip, By rotating the lock nut, the electrode tip can be easily and quickly mounted. Therefore, the replacement work of the electrode tip is shortened, and the overall efficiency of the welding work can be improved.

  Hereinafter, an electrode tip adjusting device and an electrode tip changing device according to the present invention will be described with reference to FIGS.

  As shown in FIG. 1, the electrode tip adjustment / exchange device 12 according to the present embodiment is used in a welding system 20. The welding system 20 is installed in a process of spot welding the vehicle frame 14 that is sequentially conveyed by the production line, and includes an industrial articulated robot (moving means) 22 having an electrode tip holder 10 at the tip, and an electrode. It includes a chip adjustment / exchange device 12, a chip dresser 26, and a control device 28 for controlling the entire system. A coolant can be supplied and recovered from the coolant supply source 30 to the electrode tip holder 10. A suitable radiator may be provided in the middle of the cycle path for circulating the coolant. The recovery pipe 52b is not necessarily connected to the coolant supply source 30, and may be connected to, for example, a drain groove.

  The multi-joint robot 22 has a 6-axis configuration and can perform a program operation under the action of the control device 28. And can be moved and arranged in an appropriate orientation. In FIG. 1, the electrode tip adjustment / exchange device 12 and the tip dresser 26 are schematically shown larger than the actual size.

  Next, the electrode tip holder 10 will be described. In the description of the electrode tip holder 10, the side connected to the articulated robot 22 is a base end, and the side on the opposite side where the electrode tip 46 is inserted is a front end.

  As shown in FIGS. 2 to 4, the electrode tip holder 10 includes a chuck body 40 having a first taper inner peripheral surface 40 a having an inner diameter hole that gradually increases in diameter toward the distal end side, and the chuck body 40 is articulated. An adapter 42 connected to the robot 22, a cylindrical lock nut 44 that is screwed into the distal male thread portion 40 b of the chuck body 40, and a collet 48 that is fitted to the first taper inner peripheral surface 40 a. The collet 48 is reduced in diameter by being elastically deformed by being pressed in the axial direction when the lock nut 44 is screwed into the distal male screw portion 40b, and securely holds the rod-shaped electrode tip 46 inserted into the inner diameter portion 48f. can do.

  Further, the electrode tip holder 10 includes six bolts 50 for fixing the chuck body 40 to the adapter 42, a first joint 54 connected to a supply pipe 52a for supplying a coolant from the coolant supply source 30, and a coolant. It has the 2nd coupling 56 connected to the collection | recovery pipe 52b which returns a cooling fluid to the supply source 30, and the positioning pin 58 (refer FIG. 4) which prescribes | regulates the angle of the collet 48 with respect to the chuck | zipper main body 40. FIG.

  As shown in FIG. 5, the collet 48 includes three sets of splits 48 a provided at equiangular (120 °) positions, a first tapered outer peripheral surface 48 b that abuts on the first tapered inner peripheral surface 40 a, and the first collet 48. Three groove portions 48c provided on the first taper outer peripheral surface 48b, a second taper outer peripheral surface 48d that decreases in diameter toward the tip side, and an annular shape between the first taper outer peripheral surface 48b and the second taper outer peripheral surface 48d It has a groove 48e and a thin pin groove 48g extending in the axial direction on the base end side. The inner diameter portion 48f of the collet 48 is slightly larger than the outer diameter of the electrode tip 46, and has a smooth cylindrical surface. Further, the first taper inner peripheral surface 40a and the first taper outer peripheral surface 48b are smooth surfaces, respectively, which are in a so-called double taper state when fitted and have a high degree of adhesion. The same applies to the second tapered outer peripheral surface 48d and the second tapered inner peripheral surface 44b described later.

  Each of the three sets of splits 48a has a first slit 60a extending in the axial direction from the distal end surface to the vicinity of the proximal end surface, and a second slit 60b extending in the axial direction from the proximal end surface to the vicinity of the distal end surface. The first slit 60a and the second slit 60b are arranged in parallel near each other, and the distance between the first slit 60a and the second slit 60b is set to be the same width as the width of the first slit 60a and the second slit 60b. Yes. When the collet 48 is pressed by the lock nut 44, the first tapered outer peripheral surface 48b is slightly pushed along the first tapered inner peripheral surface 40a, and the first slit 60a and the second slit 60b are narrowed. In this way, the collet 48 is reduced in diameter.

  The three grooves 48c are provided between the splits 48a in an equiangular (120 °) arrangement, and are substantially U-shaped with both end portions 62a and 62b on the base end side in a side view, and are symmetrical. Is provided. Each groove portion 48c has a depth that reaches the vicinity of the surface of the inner diameter portion 48f, and since the first tapered outer peripheral surface 48b is inclined, the portions of both end portions 62a and 62b on the proximal end side are shallow, and the distal end side is It is deeper.

  The collet 48 is copper or copper alloy that is easily elastically deformed and has high thermal conductivity, and specifically, beryllium copper or the like can be used.

  2 to 4, the chuck body 40 includes a coolant supply port 40c that opens at a position facing the end 62a of each groove 48c, and a coolant recovery port 40d that opens at a position facing the end 62b. And a flange 40e having six mounting holes 40j through which the threaded portions of the bolts 50 pass at equal intervals. The chuck body 40 is further provided radially at equal intervals so as to communicate with the bottom shaft center hole 40f to which the first joint 54 is connected on the base end side and the shaft center hole 40f from the outer surface of the flange 40e. Three radial passages 40g (see FIG. 2), three first axial passages 40h communicating from the base end surface to the coolant supply port 40c, and similarly 3 communicating from the base end surface to the coolant recovery port 40d Second axial passage 40i. The first axial passages 40h and the second axial passages 40i are alternately arranged at equal intervals of 60 °, extend in the axial direction, bend at the tip, and are supplied with a coolant supply port 40c and a coolant recovery port 40d. Communicating with

  The three radial passages 40g are respectively closed by plug members 64 at the openings on the outer surface of the flange 40e. Similarly, the three first axial passages 40h are respectively plugged by plug members 64 at the openings on the base end surface. Eventually, the first joint 54 communicates with each coolant supply port 40c through the shaft center hole 40f, the radial passage 40g, and the first axial passage 40h. Since the supply pipe 52a is connected to the first joint 54, the coolant supplied from the coolant supply source 30 is discharged from the coolant supply port 40c to the end portion 62a of the groove 48c.

  A narrow pin hole 66 is provided on the side surface of the chuck body 40 so as to be inserted in the radial direction and into which the positioning pin 58 is inserted. Positioning is performed by engaging with the pin groove 48g.

  The adapter 42 has a stepped cylindrical shape, a flange receiving portion 42a facing the flange 40e, a bite joint 42b integrally provided on the proximal end side, and a second joint 56 communicating with the side surface from the inner diameter portion 42c. And a side hole 42d to be connected. The side surface of the adapter 42 has a hexagonal shape with which a tool such as a spanner can be engaged. The flange receiving portion 42a is provided with six screw holes into which the bolts 50 are screwed through the mounting holes 40j.

  When the chuck body 40 and the adapter 42 are connected by the six bolts 50, the inner diameter portion 42c is kept liquid-tight with respect to the outside and communicates with the second axial passage 40i. Will communicate with each coolant recovery port 40d via the second axial passage 40i. Since the recovery pipe 52b is connected to the second joint 56, the coolant discharged to the one end portion 62a of the groove portion 48c reaches the other end portion 62b along the U shape, and the coolant recovery port 40d. And is recovered by the coolant supply source 30. The coolant does not flow and stay smoothly along the U-shape, and flows over a wide area, improving the cooling efficiency.

  The lock nut 44 has a substantially crown shape, and includes a proximal female thread portion 44a that is screwed into the distal male thread portion 40b of the chuck body 40, a second tapered inner circumferential surface 44b that abuts on the second tapered outer circumferential surface 48d, and an inner diameter side. And an annular projection 44c.

  The annular protrusion 44c is eccentric. In practice, one of the eccentric directions has no protrusion, and the inner diameter surface and the second tapered inner peripheral surface 44b form a continuous surface. The collet 48 engages with the annular groove 48e.

  That is, as shown in FIG. 6, the collet 48 can be easily inserted from one side (right side in FIG. 6) that is eccentric and has no protrusion, and no special tool is required at the time of insertion. Further, after the collet 48 is inserted, the collet 48 is aligned by the second taper outer peripheral surface 48d and the second taper inner peripheral surface 44b, and the annular groove 48e and the annular protrusion 44c are reliably engaged. Since the annular groove 48e and the annular protrusion 44c are engaged in this manner, the collet 48 can be integrally displaced when the lock nut 44 is loosened, and the collet 48 can be prevented from being fixed to the chuck body 40. The diameter of the collet 48 can be increased by releasing the elastic deformation. Further, by fitting the second tapered outer peripheral surface 48d and the second tapered inner peripheral surface 44b, the collet 48 can be accurately pressed along the axial direction when the lock nut 44 is screwed into the chuck body 40. . The outer peripheral portion of the lock nut 44 has a hexagonal shape that can be engaged with a spanner, a wrench, or the like. Since the lock nut 44 does not continuously rotate at a high speed, even if the annular protrusion 44c is eccentric, the lock nut 44 does not shake with the rotation.

  In the electrode tip holder 10 configured as described above, the collet 48 is reduced in diameter by elastically deforming the split 48a, so that the side surface of the electrode tip 46 can be reliably held. Further, by loosening the lock nut 44, the electrode tip 46 can be easily inserted and removed, and the protruding amount of the electrode tip can be adjusted according to the wear amount of the electrode tip 46. Furthermore, the electrode tip 46 can be a simple rod-shaped member, so that the cost can be reduced and the material is not wasted. By replacing the collet 48 with one having a different inner diameter, electrode tips 46 having various diameters can be used.

  Further, since the collet 48 is reduced in diameter and comes into surface contact with the side surface of the electrode tip 46, heat transfer is performed well. Since the coolant supplied to the end 62a flows along the U-shape of the groove 48c, the flow path is relatively long, the collet 48 can be efficiently cooled, and the consumption of the electrode tip 46 is reduced. The welding efficiency can be improved. The groove portion 48c is not limited to the U-shape, and may be formed on a wide surface on the first tapered outer peripheral surface 48b, for example, in an M-shape or the like in order to ensure a longer flow path. Since both end portions 62a and 62b of the groove portion 48c are relatively shallow, the flow passage cross-section becomes an appropriate throttle, and the cooling effect can be increased by increasing the flow rate of the coolant. Since the groove portion 48c has a depth reaching the vicinity of the inner surface of the inner diameter portion 48f, the coolant flows near the surface of the electrode tip 46, and the electrode tip 46 is cooled more efficiently. When the collet 48 is pressed in the axial direction by the lock nut 44, the first taper outer peripheral surface 48b is strongly pressed by the first taper inner peripheral surface 40a, and the groove 48c is kept liquid-tight. Liquid leakage is prevented.

  Next, the electrode tip adjustment / exchange device 12, the tip dresser 26, and the control device 28 will be described in order.

  As shown in FIG. 7, the electrode tip adjustment / exchange device 12 is configured based on a square column 70, and a tip protrusion amount adjustment unit (electrode tip adjustment device) 72 provided on one surface of the square column 70, and the like. And a chip mounting portion (electrode chip exchange device) 75 provided on the surface.

  The tip protrusion amount adjusting portion 72 protrudes laterally from the upper portion of the square pole 70 and has a first lock nut rotating tool 73 having a wrench-shaped portion 73a at the tip, and a lower portion than the first lock nut rotating tool 73. And a protruding amount defining piece 74 provided. The protrusion amount defining piece 74 is formed with a long hole extending in the vertical direction on the mounting surface with respect to the rectangular column 70, and the distance in the height direction from the first lock nut rotating tool 73 is a defined length corresponding to the electrode tip 46. It has been adjusted to be. A chip collection box 72 a is disposed below the chip protrusion amount adjustment unit 72.

  The tip mounting portion 75 protrudes laterally from the upper portion of the square column 70, has the same shape as the first lock nut rotary tool 73, and has a tip end with a spanner-shaped portion 76a, and the second lock nut rotary tool 76. A guide plate 78 extending in a lateral direction (a direction perpendicular to the direction in which the second lock nut rotary tool 76 protrudes) from one lower surface at the tip of the rotary tool 76, and below the second lock nut rotary tool 76 And an automatic chip loading section 80 provided in the apparatus.

  The automatic chip loading unit 80 includes a cartridge 81 that extends in the lateral direction, a cartridge guide 82 that holds the cartridge 81, and a motor (feed mechanism) 84 that intermittently feeds the cartridge 81. The motor 84 rotates the pinion 82 a under the action of the control device 28, and intermittently feeds it laterally while meshing with a rack 80 a provided on the side surface of the cartridge 81.

  A plurality of tip holes 80b are provided at equal intervals on the upper surface of the cartridge 81, and springs 80c are provided on the bottom surface of each chip hole 80b. When the cartridge 81 moves in the lateral direction by the intermittent feed action of the motor 84, the upper end of a new electrode tip 46 previously inserted into the tip hole 80b contacts and slides on the guide plate 78 to press the spring 80c. While being pushed down, it moves. In this way, the electrode tip 46 moves while being guided by the guide plate 78, and when the electrode tip 46 passes through the guide plate 78, the electrode tip 46 is disposed at the center of the spanner-shaped portion 76 a that is the loading position of the electrode tip 46 with respect to the electrode tip holder 10. Then, one intermittent feed by the motor 84 is completed.

  Note that an automatic chip loading unit 85 as shown in FIG. 8 may be used as a modification of the automatic chip loading unit 80. In the automatic chip loading unit 85, the spanner-shaped portion 76a of the second lock nut rotary tool 76 is opened in the lateral direction, and the guide plate 78 in the automatic chip loading unit 80 is omitted. Further, the cartridge 81 does not have to be linear as long as the plurality of electrode chips 46 are substantially arranged in a line, and may be formed in an annular shape, for example.

  As shown in FIG. 9, the chip dresser 26 has a cylindrical main body 26a with a built-in motor, a plate-shaped polishing table 26b projecting sideways from the top, and a support for floatingly supporting the main body 26a in the vertical direction by a spring 26c. A base 26d and a small dish-shaped rotating grindstone 26e provided at the center of the upper surface of the polishing base 26b are provided. The tip dresser 26 is built in the main body 26 a under the action of the control device 28 when the tip of the electrode tip 46 held by the electrode tip holder 10 is lightly pressed onto the rotating grindstone 26 e by the operation of the articulated robot 22. The rotating grindstone 26e is rotated by a motor so that the tip of the electrode tip 46 is polished to form an appropriate substantially truncated cone shape.

  As shown in FIG. 10, the control device 28 includes a robot control unit 86 that controls the articulated robot 22, a motor control unit 88 that intermittently controls the motor 84 of the automatic chip loading unit 80, and a built-in motor of the chip dresser 26. A chip dresser control unit 90 that controls the rotation, a coolant supply source control unit 92 that controls the coolant supply source 30, and a chip state inspection unit 94 that inspects the state of the electrode chip 46 based on a predetermined sensor (not shown). And have. Further, near the tip protrusion amount adjustment unit 72, there is a tip drop detection unit 96 that detects that the electrode tip 46 that has been consumed and has reached the use limit has been removed from the electrode tip holder 10 and collected in the tip collection box 72a. It is connected.

  The robot control unit 86 includes a welding operation unit 86a that causes the articulated robot 22 to perform a welding operation according to the shape of the frame 14 of the vehicle, and an electrode via a transformer (not shown) when the articulated robot 22 assumes a welding posture. An energization control unit 86b that energizes the chip 46 and a chip dress operation unit 86c that operates the articulated robot 22 so that the tip of the electrode chip 46 abuts the rotating grindstone 26e in a plane. The robot control unit 86 further includes a protrusion amount adjusting operation unit 86d and a chip mounting operation unit 86e.

  The protrusion amount adjusting operation portion 86d engages the hexagonal portion on the outer periphery of the lock nut 44 with the spanner-shaped portion 73a with the electrode tip 46 facing downward, and rotates the electrode tip holder 10 about the axis. This is a control function unit that operates the articulated robot 22.

  The tip mounting operation portion 86e lowers the electrode tip holder 10 in a state where the lock nut 44 is directed downward and the electrode tip 46 is removed, and the hexagonal portion on the outer periphery of the lock nut 44 is changed to the spanner shape portion 76a. A control function unit that engages and operates the articulated robot 22 so as to rotate about the axis of the electrode tip holder 10. The operation of rotating the electrode tip holder 10 about the axis by the protrusion amount adjusting operation unit 86d and the tip mounting operation unit 86e is, for example, a joint shaft 22a (lock nut rotating means) that is close to the tip of the articulated robot 22 and that can be twisted. , See FIG. 1).

  In practice, the control device 28 includes a central processing unit (CPU) as a main control unit, a random access memory (RAM) and a read only memory (ROM) as storage units, and the above-described functional units. Is realized by the CPU reading the program and executing software processing in cooperation with the storage unit and other functional units.

  Next, a welding method for performing a large amount of spot welding on the vehicle frame 14 using the welding system 20 configured as described above will be described. Hereinafter, unless otherwise noted, processing is performed in the order of the step numbers described.

  First, in step S <b> 1 of FIG. 11, the electrode tip holder 10 assembled in advance is attached to the tip of the articulated robot 22. Specifically, the bite joint 42b of the adapter 42 is screwed into the tip steel pipe (not shown) of the articulated robot 22, and the supply pipe 52a is connected to the first joint 54 via the tip steel pipe, and the second The recovery pipe 52b is connected to the joint 56, and the coolant supply source 30 is driven to supply, recover, and circulate the coolant to the electrode tip holder 10. As described above, the coolant discharged from the coolant supply source 30 is sequentially supplied to the supply pipe 52a, the first joint 54, the shaft center hole 40f, the radial passage 40g, the first axial passage 40h, and the groove 48c (end portion 62a → The coolant is recovered in the coolant supply source 30 via the end 62b), the second axial passage 40i, the inner diameter portion 42c of the adapter 42, the second joint 56, and the recovery pipe 52b. In addition, this step S1 can also be included in the process of step S9 and S10 mentioned later, and in this case, a series of welding processes are performed cyclically.

  In step S2, the articulated robot 22 is operated under the action of the welding operation unit 86a and the energization control unit 86b, and welding is performed on a prescribed welding point on the frame 14 of the vehicle. This welding process may be continuously performed on a plurality of welding points, or may be performed continuously on the frames 14 of a plurality of vehicles conveyed on the line.

  After performing welding for a predetermined number of times or for a predetermined time, in step S3, the tip state inspection portion 94 confirms the wear state of the tip portion of the electrode tip 46 and the protruding amount of the electrode tip 46. If it is determined that the tip is worn, the process proceeds to step S4, and if it is determined that the protruding amount is short, the process proceeds to step S5. Otherwise, it is determined to be normal and the process returns to step S2. Note that the branching process in step S3 is not limited to the determination by the chip state inspection unit 94 based on a sensor or the like, and may be based on, for example, the number of weldings or the working time.

  In step S4, after the tip of the electrode tip 46 is brought into contact with the rotating grindstone 26e under the action of the chip dressing operation unit 86c, the tip grinder control unit 90 rotates the rotating grindstone 26e so that the electrode tip 46 has an appropriate shape. Polish to be. After this polishing process, the process proceeds to step S2, and the welding operation is continued.

  On the other hand, in step S5, the outer peripheral hexagonal portion of the lock nut 44 is engaged with the spanner-shaped portion 73a with the electrode tip 46 facing downward under the action of the protrusion amount adjusting operation portion 86d (see FIG. 12).

  In step S6, as shown in FIG. 12, by rotating the electrode tip holder 10 counterclockwise (arrow A1 direction), the lock nut 44 and the chuck body 40 are relatively rotated, and the lock nut 44 is loosened. As described above, the first lock nut rotating tool 73 (and the second lock nut rotating tool 76) is a fixed tool, but the lock nut 44 is rotated by rotating the electrode tip holder 10 by the operation of the articulated robot 22. Acts as a rotating tool for In this case, for example, a rotation amount of about 90 ° is sufficient.

  Since the force applied to the collet 48 is released by this rotation operation, the collet 48 is slightly displaced downward while sliding with respect to the first taper inner peripheral surface 40a, and the inner diameter is slightly expanded. Therefore, the holding force of the electrode tip 46 is released and the electrode tip 46 is lowered by its own weight.

  At this time, when the degree of wear of the electrode tip 46 is small and the electrode tip 46 has a sufficient length, the tip end portion of the electrode tip 46 abuts against the protruding amount defining piece 74 as shown by a two-dot chain line in FIG. Thus, the electrode tip 46 protrudes from the electrode tip holder 10 by a specified amount. In addition, when the degree of wear of the electrode tip 46 is large and the required length cannot be ensured, the electrode tip 46 comes out of the collet 48 and falls downward and is collected in the tip collection box 72a. In this manner, the tip protrusion amount adjusting unit 72 functions as a means for adjusting the protrusion amount of the electrode tip 46 and also functions as a means for extracting the electrode tip 46.

  In step S7, the state of the electrode tip 46 is determined based on the detection result of the tip drop detection unit 96. If it is determined that the electrode tip 46 is upright on the protruding amount defining piece 74, the process proceeds to step S8. If it is determined that the electrode chip 46 has been collected in the chip collection box 72a, the process proceeds to step S9.

  In step S <b> 8, the electrode tip holder 10 is rotated clockwise (in the direction of arrow A <b> 2) to relatively rotate the lock nut 44 and the chuck main body 40 and tighten the lock nut 44. As a result, the electrode tip 46 is securely held by the collet 48 again. At this time, the first taper outer peripheral surface 48b and the first taper inner peripheral surface 40a are kept in contact with each other, and the groove portion 48c is kept liquid-tight to prevent liquid leakage. After the process of step S8, the process returns to step S2, and the welding operation is continued.

  Thus, by loosening the lock nut 44, the electrode tip 46 can be easily pulled out, and the amount of protrusion of the electrode tip can be adjusted according to the amount of wear. Therefore, a relatively long electrode tip 46 can be employed, and the number of replacements of the electrode tip 46 can be reduced, thereby improving the efficiency of the overall welding operation.

  On the other hand, in step S9, the electrode tip holder 10 is disposed above the spanner-shaped portion 76a with the lock nut 44 directed downward under the action of the tip mounting operation portion 86e, and then lowered. By this operation, a new electrode tip 46 installed upright at the loading position is inserted into the collet 48, and the outer peripheral hexagonal portion of the lock nut 44 is engaged with the spanner-shaped portion 76a (see FIG. 13).

  In step S <b> 10, the lock tip 44 is tightened by rotating the electrode tip holder 10 clockwise as in step S <b> 8, and the electrode tip 46 is held by the collet 48.

  In step S11, the electrode tip holder 10 is retracted to a predetermined retracting position, and the motor 84 is intermittently operated under the action of the motor control unit 88 to place the new electrode tip 46 at the loading position to prepare for the next mounting operation. . Thereafter, the process returns to step S2, and the welding operation is continued.

  Although not clearly shown in the flowchart of FIG. 11, at the end of a predetermined welding operation or at the end of work time, the control device 28 detects that fact and moves the multi-joint robot 22 to a predetermined retraction position. The coolant supply source 30 and the like are stopped.

  As described above, according to the electrode tip holder 10, the protruding amount of the electrode tip 46 can be adjusted according to the wear amount, the number of times of replacement of the electrode tip 46 is reduced, and the welding operation is interrupted by the replacement of the electrode tip 46. Time can be shortened and production efficiency can be improved. Further, since the electrode tip 46 is cooled via the collet 48 by the coolant supplied to the groove 48c, the consumption of the electrode tip 46 is reduced, the welding efficiency is improved, and the replacement frequency of the electrode tip 46 is further reduced. be able to.

  In the electrode tip holder 10, the first taper outer peripheral surface 48b and the first taper inner peripheral surface 40a are kept in contact with each other when the protruding amount of the electrode tip 46 is adjusted and mounted, and the groove portion 48c is kept liquid-tight and exposed to the outside. Will not be damaged. Accordingly, it is not necessary to replace the collet 48 as long as the electrode tip 46 has the same diameter.

  Moreover, according to the tip protrusion amount adjusting unit 72 in the electrode tip adjustment / exchange device 12 according to the present embodiment, the electrode tip 46 becomes the protrusion amount defining piece by loosening the lock nut 44 with the first lock nut rotating tool 73. It can drop until it abuts to obtain an appropriate protruding amount, and is suitably used for the electrode tip holder 10. In other words, the tip protrusion amount adjusting unit 72 can quickly adjust the protrusion amount of the electrode tip 46 and can reduce the number of replacements of the electrode tip 46, thereby improving the efficiency of the welding operation.

  Furthermore, according to the tip mounting portion 75 in the electrode tip adjustment / exchange device 12 according to the present embodiment, after the electrode tip 46 is removed, the electrode tip holder is placed against the new electrode tip 46 arranged upright at the loading position. 10 is lowered and inserted, and the electrode nut 46 can be mounted by tightening the lock nut 44 with the second lock nut rotating tool 76, so that the mounting operation can be performed easily and quickly. In other words, in the tip mounting portion 75, the time required for the replacement work of the electrode tip 46 is shortened, and the efficiency of the welding work is improved.

  In the above example, the electrode tip holder 10 is mounted on the articulated robot 22 as a single unit. However, the electrode tip holder 10 may be applied to other spot welding apparatuses such as a so-called C-shaped gun and an X-shaped gun. Of course.

  Of course, the electrode tip adjusting device and the electrode tip changing device according to the present invention are not limited to the above-described embodiments, and various configurations can be adopted without departing from the gist of the present invention.

It is a conceptual diagram of the welding system which welds with respect to the flame | frame of a vehicle. It is a cross-sectional top view of an electrode tip holder. FIG. 3 is a cross-sectional side view taken along the line III-III of the electrode tip holder in FIG. 2. It is a disassembled perspective view of an electrode tip holder. It is a perspective view of a collet. It is a partial cross section perspective view of a lock nut. It is a perspective view of the electrode tip adjustment exchange device concerning this embodiment. It is a perspective view which shows the modification of the automatic loading part in an electrode tip adjustment exchange apparatus. It is a perspective view of a chip dresser. It is a block block diagram of a control apparatus. It is a flowchart which shows the welding method performed with respect to the flame | frame of a vehicle using a welding system. It is a perspective view of the state where the electrode tip holder was engaged with the tip protrusion amount adjusting portion. It is a perspective view of the state where the electrode tip holder was engaged with the tip mounting part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Electrode tip holder 12 ... Electrode tip adjustment exchange device 20 ... Welding system 22 ... Articulated robot 26 ... Tip dresser 28 ... Control device 30 ... Coolant supply source 40 ... Chuck main body 40a ... First taper inner peripheral surface 40b ... Tip Male screw portion 40c ... Coolant supply port 40d ... Coolant recovery port 44 ... Lock nut 44a ... Base end female screw portion 44b ... Second taper inner peripheral surface 44c ... Annular projection 46 ... Electrode tip 48 ... Collet 48a ... Split 48b ... First 1 taper outer peripheral surface 48c ... groove 48d ... second taper outer peripheral surface 48e ... annular groove 72 ... tip protrusion amount adjusting portion 73 ... first lock nut rotating tool 74 ... projection amount defining piece 75 ... tip mounting portion 76 ... second lock nut Rotating tools 80, 85 ... Chip automatic loading section

Claims (4)

A chuck body having a tapered inner peripheral surface with an inner diameter hole expanding toward the tip;
A lock nut screwed into the threaded portion of the chuck body;
A rod-shaped electrode tip fitted into the inner diameter hole, pressed in the axial direction by screwing the lock nut into the threaded portion, and reduced in diameter by elastic deformation of the split, and inserted into the inner diameter portion. A collet to hold,
For an electrode tip holder having
Lock nut rotating means for rotating the lock nut in the left-right direction with respect to the chuck body in a state where the lock nut is directed downward;
When the lock nut is rotated by the lock nut rotating means, a protruding amount defining piece provided on the shaft below the lock nut by a defined length; and
An electrode tip adjustment device comprising: A chuck body having a tapered inner peripheral surface with an inner diameter hole expanding toward the tip;
A lock nut screwed into the threaded portion of the chuck body;
A rod-shaped electrode tip fitted into the inner diameter hole, pressed in the axial direction by screwing the lock nut into the threaded portion, and reduced in diameter by elastic deformation of the split, and inserted into the inner diameter portion. A collet to hold,
For an electrode tip holder having
Lowering and inserting means for lowering the electrode tip holder with the lock nut pointing downward and with the electrode tip removed, and inserting the electrode tip placed upright at a predetermined loading position into the collet When,
Lock nut rotating means for rotating the lock nut so as to be screwed to the chuck body in a state where the electrode tip is inserted into the collet by the lowering insertion means;
An electrode tip exchange device comprising: In the electrode tip exchange device according to claim 2,
The lock nut rotating means includes a program-operable moving means for moving and rotating the electrode tip holder and a fixed tool that engages with an outer diameter portion of the lock nut. The electrode tip changer characterized in that the lock nut is rotated relative to the chuck body by rotating the electrode tip holder by the moving means in the combined state. In the electrode tip exchange device according to claim 3,
Automatic loading means for placing another electrode chip upright at the loading position after the electrode chip holder mounted with the electrode chip is separated from the loading position by the moving means;
The automatic loading means includes a cartridge that holds a plurality of electrode chips in a line and holds them upright;
A feed mechanism for intermittently feeding the cartridge so that the electrode tips are sequentially arranged at the loading position;
An electrode tip changer characterized by comprising:

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