Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K11/00—Resistance welding; Severing by resistance heating
  • B23K11/30—Features relating to electrodes
  • B23K11/3072—Devices for exchanging or removing electrodes or electrode tips

Definitions

• the technical sector of the present invention is that of spot welding robots and in particular the devices for extracting and loading electrodes.
• the patent FR-2870149 of the present applicant describes a device for extracting used electrodes in which there is provided a rotary extraction block comprising extraction jaws applied around the electrode in relation to a cam in order to print a movement helical to extract the used electrode.
• the electrode is held by the jaws which requires specific means to close them on the electrode.
• Patent FR-2760391 also of the applicant describes a device in which the extraction module is double that is to say two superimposed and coaxial elements to allow the simultaneous extraction of two electrodes. Extraction of the electrode always requires the use of extraction jaws.
• US-5495663 discloses a used electrode extraction device in which the electrode is taken between two jaws and to extract the electrode causes a translation of the jaws and thus ensure a tear force of it. It is understood that with such a device must ensure the immobilization of the gripper of the robot.
• FR-2651457 discloses an assembly for changing worn electrodes and replace them with new electrodes.
• the extraction of the electrode is carried out by ensuring the blocking of the electrode in the extraction module and then print to this module a rotational movement and then translation. So we see that this is the entire module.
• Patent EP-0267109 describes an extraction system in which articulated forks are provided which are introduced between the electrode and the electrode holder. By operating in rotation one fork relative to the other is separated, following a translation this electrode. This embodiment involves specific means to ensure the rotation of one fork relative to the other, which makes this complex and fragile system.
• the object of the present invention is to provide an integrated electrode extraction device in an assembly ensuring the replacement of used electrodes by new electrodes.
• the subject of the invention is therefore an electrode extraction device fixed on an electrode holder of a spot welding robot clamp, characterized in that it comprises a support in which slides an extractor intended to come into operation. pressing on the electrode, a receiving housing of the electrode and at least one means of counter-support of the electrode being in the form of a truncated cone in order to print to said electrode under the action of the extractor a helical extraction movement with respect to the electrode holder.
• the counter-support means is in the form of a frustoconical roller mounted free to rotate relative to the support.
• the device comprises two support means defining together with the extractor three non-aligned contact points with said electrode.
• the support comprises two electrode housings each provided with counter-support means.
• the two housings are open at each end, towards two opposite directions relative to the support.
• the extractor is in the form of a spur having two claws provided at each end with a serrated surface for printing the electrode a rotational movement.
• the subject of the invention is also an assembly for extracting used electrodes and for loading new electrodes of spot welding robot clamps, characterized in that it comprises an electrode extraction device and at least one electrode extraction device. a new electrode charger attached to the support of the extraction device to form a compact assembly adapted to be attached to the robot.
• the electrode charger comprises a stop cooperating with an electrode presence detector, said stop being subjected to the action of a spring to occupy a first position bearing on an electrode and a second position. intended to obscure a detector in the absence of the electrode.
• a first advantage of the present invention lies in the fact that the extraction of used electrodes only requires a mechanical movement of translation.
• Another advantage of the present invention results in the extreme compactness of the assembly ensuring its implementation in a production line without any modification thereof.
• Another advantage of the invention lies in its technical simplicity to obtain automatic operation and install it either stationary or on a robot arm, which does not provide any existing devices.
• the device according to the invention proposes a light and space-saving solution of a replacement system for used electrodes of spot welding tongs.
• FIG. 2 is an exploded view showing the structure of the extraction device according to the invention
• FIG. 3 represents a sectional plan view of the extraction device
• FIG. 4 is a view showing the position of the electrode in the extraction device
• FIG. 5 is a general view showing the distribution structure of the new electrodes.
• the assembly 1 consists of two components, an automatic extractor 2 and two automatic loaders 3 and 4 compactly combined to be easily integrated into a site or be easily mounted on a welding robot arm (not shown), either to be fixed permanently or to be loaded when it becomes necessary to automatically replace the used electrodes.
• a welding robot arm not shown
• the extraction module 2 consists of two elements, a motor means 5 which makes it possible to ensure the movement of the extraction mechanism, and a mechanical assembly 6 which makes it possible to extract the used electrodes whatever the diameter of the electrode to extract.
• the extraction module is connected to the loading module in a cross arrangement on a plate 7 described below.
• the loading module 3 or 4 is composed of rotary chargers, called cartridges, which can be single or double row of new electrodes.
• the electrodes are arranged in U-shaped cells, adapted to the electrodes that will have to be loaded on the welding clamp.
• the extraction module is provided with a body covered by a cover 8 fixed to this body by screws 9 (9a-9c) and shows two indentations 10 and 11 in which are introduced the clamps (not shown) of the robot to replace worn electrodes.
• a blocking module of the robot gripper described in relation with FIGS. 6 and 7 is fixed on this cover 8.
• FIG. 2 shows in section the end of a gripper 40 of a welding robot integral with an extension 41 extended by a frustoconical portion 42 forcibly engaging in a blind hole 43 of the same shape. formed in the mass of an electrode 44.
• Other means of fixing the electrode are known that it is not necessary to further detail. However, it is understood that to extract a used electrode, it is necessary to block the extension 41 to prevent the transmission of forces to the clamp itself.
• the extraction device will therefore comprise an extraction module of the electrode and a locking module of the extension, these two modules being preferably both integral with the same support.
• FIG. 3 shows an exploded view of the extraction module 6 linked to the motor 5 ensuring, via a coupling 12, the translation of an extractor 13 directed in the plane of the figure to the left for extracting a used electrode, or to the right to evacuate this electrode which falls by its own weight when it has been extracted from the clamp 40.
• the extractor 13 is made here in the form of a spur having two claws 14a and 14b provided at each end with a serrated surface 15 for printing to the electrode a rotational movement as will be explained hereinafter .
• the extractor comprises a support 16 of elongated shape provided with a transverse blind bore 17 in which slides the extractor 13 intended to bear against the electrode.
• the bore 17 is extended by six transverse holes 18a-18b, 19-22.
• the holes 18a-18b each constitute a receiving housing of the electrode (not visible in this figure).
• the holes 19 and 20 constitute the separate receiving housing of a first support means 23 and a second support means 24 of the electrode is in the form of a truncated cone.
• the bores 21 and 22 constitute separate receiving housings of a third counter-support means 25 and a fourth counter-support means 26 of the electrode.
• These backing means 23, 24, 25 and 26 are for example made in the form of frustoconical rollers.
• rollers 23 and 24 are arranged in the same direction while the rollers 25 and 26 are arranged in the opposite direction.
• This arrangement makes it possible to process a gripper of the robot whose electrode must be changed in one direction and to treat the other gripper of the robot in the other direction, which makes it possible not to have to return the grippers of the robot.
• these frustoconical rollers could be arranged in the same direction without changing the structure of the means according to the present invention.
• the support 16 is completed by the plates 27 and 28 and the cover 29 fixed to this support by means of screws 30.
• Figure 4 there is shown a partial section showing a detail of embodiment in the blind bore 17 where the six holes 18a-18b, 19, 20, 21 and 22 are visible in which the rollers are inserted. It can be seen on the right-hand part of this figure that the first gripper of the robot is intended to be inserted into the bore 18a in order to extract a first electrode in a first direction and that the second gripper of the robot is intended to to be inserted into the bore 18b to extract the second electrode.
• This left part illustrates the extraction of the other electrode of the welding clamp upwards in a direction perpendicular to the plane of the figure.
• the electrode is then pressed against the support means 23 and 24 for example.
• This signal causes the forward movement of the spur 13 which is guided inside the body 16 by the cylindrical rollers 31a and 31b.
• the conical end 15a of the spur 13 progressively takes over the electrode to be extracted, by placing it on the frustoconical rollers 23 and 24 of the cavities 18a and 18b.
• These frustoconical rollers are rotatably mounted on pins 33a and 33b.
• the invention can be realized with a single counter-support means.
• the cylindrical rollers 31a and 31b are intended to ensure good guidance of the spur 13 during its movement to the left.
• Figure 5 there is shown a section at the electrodes 35 and 36 engaged in holes 18a and 18b not designated for reasons of convenience.
• the two electrodes are shown to better highlight the operation of the clamp.
• the electrode 35 is compressed by the end 14a of the spur with the claws 15a bearing against the side wall of the electrode.
• the electrode 35 thus comes into intimate contact with the rollers 24 and 23 (only 24 is visible in this figure), which causes with the translation of the spur the rotation and the translation of the electrode and thus its separation from the welding tongs.
• the process proceeds in the same way for the other electrode with the end
• the invention also relates to an assembly incorporating an extraction module and an electrode loading module.
• FIG 6 there is shown an upper blocking module 50 fixed on the cover 8 in the perforations 52 and 53 and a lower blocking module 51 similarly fixed to the lower part of the housing.
• the opening of the blocking module is aligned with the imprints 10 and 11.
• FIG. 7 is an exploded view of the upper blocking module 50 but it goes without saying that the lower module 51 has the same structure. It consists essentially of a cover 54 which is fixed on the extraction module jaws 55 and 56 and a cylinder 57 for actuating these jaws. For this purpose, the fixing pins 58 and 59 are screwed into the perforations 52 and 53 of the cover
• the jaws 55 and 56 are rotatably mounted about the axes 60 and 61. According to the invention, the jaw 55 is associated with an intermediate piece 62 and a jaw 63 by means of a screw 64 through the The jaw 56 comprises a jaw 66 fixed by means of the screw 67 through the lumen 68. It will be understood that the jaws 63 and 66 are adapted to the shape of the extensions of the jaws 55. electrodes to ensure versatility of the blocking module.
• a finger 69 subjected to the action of the cylinder 57.
• This finger 69 has in section a trapezoidal end whose side faces abut against the jaws to impress them with a rotational movement around 60 and 61. This rotation brings the jaws 63 and 66 closer together and thus clamping the elongation of the clamp when the electrode is to be changed.
• the new electrode charging module consists of two removable cartridges 3 and 4, which may have one or two rows of new electrodes, fixed on a plate 100 also receiving the module. 2, as described in FR-2788999.
• the two used electrodes are extracted one after the other and depending on whether the charging modules are cartridges with one or two rows of new electrodes, the charging of a new electrode at the end of the clamp can take place. either after the extraction of an electrode, to charge on an arm, an electrode of a cartridge to a row, or after extraction of the two electrodes, to simultaneously charge two electrodes of a double row cartridge, which allows supplying new electrodes, simultaneously the two welding clamp arms and thus using a changer for two different robots of the same site.
• This plate 100 is moreover flexibly linked to a link module (not shown) which makes it possible to fix the automatic changer either on a robot arm or on a support fixed to the ground inside the site.
• this connection module consists of a collar which is fixed on a tubular element which can be secured to either platinum attached to the robot arm, or a plate fixed to the ground.
• the loading module 3 has a motor means 105, which drives the cartridges 3 and 4 in rotation at the moment when, the welding tongs being loaded with new electrodes, the latter withdraws from the loading module. The loading station is thus fed with new new electrodes according to a movement whose principle is identical to that described in document FR-2746688.
• Figure 9 shows an exploded view of one of the cartridges 3 component module.
• the drawing of this figure shows a cartridge3 with a row of electrodes.
• Each of the cartridges is rotated by the motor means 105 which causes the rotational movement as soon as the refilled solder clamp exits the loading station.
• the motor means 105 which causes the rotational movement as soon as the refilled solder clamp exits the loading station.
• one or two new electrodes are automatically placed in position at the loading station 106 so that it is permanently powered and can ensure at any time a new loading of new electrodes on the welding tong, without loss of productivity.
• An elastic stop 107 makes it possible to control both the presence of one or two new electrodes 108 at the loading station and the positioning of these electrodes to ensure a still satisfactory loading on the welding clamp.
• the electrodes 108 are inserted in U-shaped cells.
• the electrodes are positioned along the same vertical axis, one is oriented upwards, the other towards at the bottom, which allows the two clamp arms to charge simultaneously.
• the cartridge 3 is dedicated to the upper clamp arm, the electrodes are directed upwards, the cartridge 4 is dedicated to the lower clamp arms, the electrodes are directed downwards.
• An elastic means 109 holds the electrodes centered in the cells, and makes it possible to absorb the variations in diameter tolerances of said electrodes, variations which may possibly create defects in the positioning of the electrodes at the loading station.
• Each cartridge 3 with single or double row of electrodes is linked to its motor means by a motor plate 110 which has in its central portion a longitudinal protrusion 111 oriented axially.
• Cartridges 3 and 4 have a base conformed to this protrusion by a groove (not shown) to ensure their respective positioning with fixing screws.
• the fixing of the cartridge 3 on the connecting plate 110 is provided by an automatic positioning pin 112, held in position on the one hand by the fixed support 114 and on the other hand by the motor plate 110 which has the appropriate machining automatic clipping of the positioning axis 112.
• a pressure on the head of the positioning pin 112 makes it possible to remove the axis from its housing 116, and thus to release the lateral movement of the cartridge 3 and its lid 117, which is always secured to the cartridge, when this lid is in working position.
• a cartridge loaded with new electrodes can then be placed on the motor plate 110 and fixed by replacing the shaft 112.
• the flexible abutment 107 is composed of a support 121, a spring 126, a abutment, and the assembly is attached to the cartridge cover 117.
• FIG 10 there is shown a loading station in which the cartridge 4 is fixed on an articulated portion 100a of the support 100.
• This embodiment allows easy access to the cartridge.
• the connecting plate 110 then becomes vertical, and by the visibility that results, the exact sliding of the cartridge 4 on the plate 110 and its attachment by the axis 112 becomes very easy.
• the support 100 finds the characteristics of its function as described above.
• the rotating cartridges each have two rows of new electrodes.
• the cartridge can be used to feed one or more welding robots of the same site, using electrodes of equal or different diameter, the extractor operating with electrodes of different diameters.
• a cartridge 3 having a first lower loading station 140 corresponding to an electrode row and a second charging station 141 corresponding to another row of electrodes.
• the assembly thus formed composes a very compact automatic electrode changer such that it can be built for a specific use both in a robotic site and on a robot arm.
• This automatic, space-saving and low weight changing device can be used both on a fixed base inside a robotic site with mobile clamps and on a robot arm to change the fixed clamp electrodes.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Resistance Welding (AREA)
• Arc Welding In General (AREA)

Applications Claiming Priority (2)

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• 2007
  • 2007-10-09 FR FR0707059A patent/FR2921855B1/fr not_active Expired - Fee Related
• 2008
  • 2008-10-08 WO PCT/FR2008/001404 patent/WO2009080917A1/fr active Application Filing
  • 2008-10-08 EP EP08864538A patent/EP2212051A1/de not_active Withdrawn
  • 2008-10-08 DE DE202008017801U patent/DE202008017801U1/de not_active Expired - Lifetime

Non-Patent Citations (1)

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