EP2212051A1

EP2212051A1 - Welding robot electrode extraction device and extraction assembly

Info

Publication number: EP2212051A1
Application number: EP08864538A
Authority: EP
Inventors: Roger Louzier
Original assignee: Individual
Current assignee: Individual
Priority date: 2007-10-09
Filing date: 2008-10-08
Publication date: 2010-08-04
Also published as: DE202008017801U1; WO2009080917A1; FR2921855A1; FR2921855B1

Abstract

The invention relates to a device for extracting an electrode (35, 36) attached to an electrode holder of a spot welding robot gripper. The device comprises a support (16) in which there slides an extractor (13) intended to press against the electrode (35, 36), a housing (10, 11) to accommodate the electrode (35, 36) and at least one electrode backstop means (23, 24, 25, 26) in the form of a cone frustum so as to impart, to the said electrode, under the action of the extractor (13) a helical extraction movement with respect to the electrode holder, the electrode being held in position by means of an immobilizing module (50, 51).

Description

SOLDER ROBOT ELECTRODE EXTRACTION DEVICE AND EXTRACTION ASSEMBLY

The technical sector of the present invention is that of spot welding robots and in particular the devices for extracting and loading electrodes.

Various devices for extracting and charging electrodes are known and reference may be made to patents FR-2870149, FR-2760391, US-5495663, FR-2651457 and EP-0267109.

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. In this embodiment, 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.

Generally, when these devices for extracting solder electrodes are complete, the assembly they form has the disadvantage of being much too important to be easily located in a site or placed on a robot arm whose primary function is to present the parts to be welded within range of the spot welding tool.

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.

According to a feature of the invention, the counter-support means is in the form of a frustoconical roller mounted free to rotate relative to the support. According to another characteristic, the device comprises two support means defining together with the extractor three non-aligned contact points with said electrode.

According to yet another feature, the support comprises two electrode housings each provided with counter-support means.

According to yet another characteristic, the two housings are open at each end, towards two opposite directions relative to the support. According to yet another feature, 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.

According to one embodiment, 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.

Other features and advantages of the invention will be better understood on reading the following description in connection with the drawings in which: - Figure 1 shows a general view of the assembly according to the invention for the purpose of above,

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, and FIG. 5 is a general view showing the distribution structure of the new electrodes.

As can be seen in Figure 1, the assembly 1 according to the invention 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. For more precision on the welding robot, reference can be made to the documents analyzed above, the detailed description of this robot is not necessary for the understanding of the invention.

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. As seen in the figure, 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. In these cartridges, 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. For this purpose, 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. Likewise, 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.

As seen in the figure, the 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. Of course, 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.

(30a-30d) and cylindrical rollers 31a and 31b whose purpose is to guide the extractor 13 in its horizontal displacement.

In 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.

On the right part of the figure, there is the bore 19 receiving the roller 24 mounted on the axis 33b, the bore 20 receiving the roller 23 mounted on its axis 33a. The illustrated view makes it possible to understand that these two rollers are mounted with their large visible base to print the electrode downward movement relative to a direction perpendicular to the plane of the figure.

On the left part of the figure, the hole 21 receiving the roller 25 mounted on the axis is similarly noted.

13b, the bore 22 receiving the roller 26 mounted on its axis

13a. 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 operation is as follows during the extraction down of the electrode by considering the right part of FIG. 3. When an electrode of the robot's welding clamp is to be changed, it is presented a first time in the cavity 18a of the extraction module for the extraction of the upper electrode, then in the cavity 18b of the same module for the extraction of the lower electrode. Under the action of the motor 5, the spur 13 is displaced in translation along the arrow F in the bore 17 to abut against the electrode (not shown) inserted into the bore

18a through the serrated portion 15a.

The electrode is then pressed against the support means 23 and 24 for example.

Of course, when the used electrode is introduced into one of the cavities 18a or 18b a signal, either electrical or mechanical, is given to the motor 5 of the extraction module

6. This signal causes the forward movement of the spur 13 which is guided inside the body 16 by the cylindrical rollers 31a and 31b. In this forward movement, 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. When the spur

13 is moved forwardly, the electrode, in contact with the spur 13 and the conical rollers 23 and 24 is driven both in rotation and in translation, and this helical type movement allows to extract the electrodes without deteriorate the welding tongs. This helical movement is reversed when the electrode of the other clamp is processed.

Of course, 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. In 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. In the configuration shown, 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

14a of the spur whose claws 15b come to support this electrode 36 in a reverse movement.

The invention also relates to an assembly incorporating an extraction module and an electrode loading module.

In Figure 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. Of course, the opening of the blocking module is aligned with the imprints 10 and 11.

Figure 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

8. 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.

To actuate the jaws 55 and 56, there is provided 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.

In Figure 8, there is shown the position of these two modules. It can be seen that the module 50 is engaged on the elongate 41 in order to block it during the extraction of the electrode 44 by the extraction module 2. Only the spur 31 and the counter-support means 31 of the extraction module are represented. The locking module 50 is represented by the jaws 63, 66 respectively connected to the jaws 55 and 56.

According to the invention and as shown in FIG. 9, 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.

According to the invention, 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. In general, 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. Depending on the type of cartridge, single or double row, 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.

In the cartridge 3, the electrodes 108 are inserted in U-shaped cells. In the case of double-row cartridges, 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. In the case of a single row cartridge, 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.

These cartridges can, if necessary, be extracted from this position in order to be recharged with new electrodes outside the robotic station.

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. When the electrode or electrodes (not shown in the figure) are correctly in position at the loading station 106, the stop 107 is pressed into its housing and covers the sensitive part of the detector 124. In case, the electrode or electrodes are badly engaged or absent from the loading station, the detector 124 is not activated, which signals the malfunction. For safety, the combined action of the resilient means 109 and the specific recessed form of the end of the stop

107 in contact with the new electrode avoids the positioning defects of the new electrodes at the loading station.

In Figure 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. In this movement, 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. By the return of the hinged portion 100a in the horizontal position and its immobilization by an axis 112a, the support 100 finds the characteristics of its function as described above.

In another type of application shown in FIG. 11, the rotating cartridges each have two rows of new electrodes. In this case, 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. In the figure, we see 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.

Claims

1. An electrode extraction device (35, 36) fixed on an electrode holder of a spot welding robot clamp, characterized in that it comprises a support (16) ^' in which slides an extractor ( 13) intended to bear on the electrode (35, 36), a receiving housing (10, 11) of the electrode (35, 36) and at least one counter-support means

(23, 24, 25, 26) of the electrode being in the form of a truncated cone for printing at said electrode under the action of the extractor (13) a helical movement of extraction relative to to the electrode holder, the electrode holder being held by means of a blocking module (50,

51).

Extraction device according to claim 1, characterized in that the counter-support means (23, 24, 25,

26) is in the form of a frustoconical roller mounted free to rotate relative to the support (16).

3. An electrode extraction device (35, 36) according to claim 1 or 2, characterized in that it comprises two support means (23, 24, 25, 26) defining together with the extractor (13). ) three non-aligned contact points with said electrode (35, 36).

4. An electrode extraction device according to one of claims 1 to 3, characterized in that the support (16) comprises two housings (10, 11) of electrode each provided with means of counter-support (23, 24). , 25, 26).

5. An electrode extraction device according to claim 4, characterized in that the two housings (10, 11) are open towards two opposite directions relative to the support (16).

6. electrode extraction device according to one of the preceding claims, characterized in that the extractor (13) is in the form of a spur having two claws (14a, 14b) provided at each end thereof a serrated surface (15a, 15b) for impressing the electrode (35, 36) with rotational and translational movement.

7. Extraction device according to any one of the preceding claims, characterized in that the locking module (50, 51) comprises jaws (55, 56) actuated in rotation by a finger (69) movable in translation.

8. Extraction device according to claim 7, characterized in that the jaws (55, 56) are provided with interchangeable jaws (63, 66).

9. A used electrode extraction and new electrode charging assembly of spot welding robot clamps, characterized in that it comprises an electrode extraction device according to any one of the preceding claims, and at least one charger (3, 4) of new electrodes fixed to the support (16) of the extraction device to form a compact assembly adapted to be fixed to the robot.

Extraction assembly according to claim 7, characterized in that each charger (3, 4) of new electrodes comprises a stop (107) cooperating with an electrode presence detector (124), said stop being subjected to the action of a spring (126) to occupy a first position bearing on an electrode and a second position intended to obscure the detector (124) in the absence of the electrode.