HK1209385B - Device for filling magazines with electrode caps - Google Patents

Description

The invention relates to a device for turning, positioning and inserting electrode caps for welding electrodes into a dedicated electrode cap magazine.

In the automotive industry, in particular, in the manufacture of bodywork in automated production lines, point welding is often used to join metal plates. To join bodywork parts together, welding robots are usually used. These welding robots are equipped with welding pins, whose pin arms are equipped with a point-welding electrode, the so-called electrode caps. These welding pins are brought to the welded plates, positioned in each one. The precise positioning of the weld to the various welded plates is automated and computer-aided.

During the welding process, electricity flows between the electrode caps through the body panels to be welded and adjacent to each other, causing a change in the contact surfaces of the electrode caps. The contact surface is often covered with a layer of brittle material which causes a change in the welding conditions.

To avoid this change being countered by an uneconomic increase in current, the electrode caps are regularly reworked depending on their load and the resulting deformation by milling.

After a certain number of post-processing operations, the material has been removed from the electrode cap to such an extent that it must be replaced. For this purpose, the worn electrode caps are removed from the welding electrode shafts.

These magazines are arranged so that the welding pins, by closing in a defined position, take on new electrode caps and attach them to the welding electrode in their position by pressing the welding pin arms against each other.

Since the cartridges must be in a defined position to be accessed by the welding pin, it is necessary to leave these cartridges in their position and to refill the cartridges manually at the point of use (see DE10200704/505).

As no persons are allowed in the operating areas of the active robots and it is therefore not possible for safety reasons to do this refilling in the course of operation, this usually requires a break in the process. To counter this disadvantage, changeable magazines have been developed.

The patent describes the storage of the electrode caps to be stored in so-called cap guides, which are arranged in a so-called magazine, corresponding to their shape.

The draw-off opening shall be open in the direction of access of the welding spindle so that each welding cap is arranged with its opening in the direction of access and is free throughout its access.

However, this does not eliminate the disadvantage of interrupting the process, since after the installation of a new magazine, the coordinates of the welding movement must also be reprogrammed.

The cartridges must be kept in a full condition according to the state of the art in order to make a quick change in the robot cell.

The purpose of the invention is to propose a device for turning, positioning and inserting electrode caps of welding electrodes into a dedicated electrode cap magazine, which is intended to avoid as far as possible the difficulties of previously known solutions and in particular to ensure process safety.

According to the invention, this task is solved by a device according to claims 1 to 15. The device is described in detail in Figures 1 to 4 and in the example below.

In this case, Figure 1 shows the device 3 in the uncoupled state without a magazine 15, Figure 2 shows the device 3 in the uncoupled state with a magazine 15, Figure 3 shows the device 3 in the uncoupled state without a magazine 15 in explosion mode and Figure 4 shows the magazine connector 14 on the reverse.

The device 3 of the invention consists of an electrode head-turning channel 1 connected at one end to a coil. The electrode caps are positioned and supported by the coil on the end of the coil on its bore-hole front side.

From this position, the electrode caps are passed to the electrode head turning channel 1 in a defined position. This electrode head pivot channel 1 is designed so that the electrode heads are rotated 90° about their Z-axis. The electrode head-end channel 1 is preferably firmly connected to the coil to transmit the vibrations of the coil to the electrode head-end channel 1 and to better support the electrode heads.

The other end of the electrode head channel 1 is located opposite the upper end of the conduction shaft 2. The electrode head drainage channel 1 is located on the conduction shaft 2 in such a way that the vibrations of the coil are not transmitted to the rest of the system and the openings of the electrode head drainage channel 1 and the conduction shaft 2 are facing each other in such a way that a safe transfer of the electrode caps can take place.

The distance between electrode head channel 1 and conduction shaft 2 shall be chosen so that these assemblies do not touch even when the transformer is switched on, but the gap width shall be kept as small as possible.

At the same time, the conduction shaft 2 is used as a buffer for the magazine 15 to be filled, so that a certain number of electrode caps are always available to fill a magazine 15. The guide shaft 2 shall be covered on the front with a transparent shaft view window 14, preferably an acrylic glass window.

In the upper part of the conduction shaft 2 a sensor 16 is located, which is used to monitor the filling of the electrode caps in the conduction shaft 2. As soon as the desired minimum filling level is exceeded and the sensor 16 no longer receives a signal, the wave transmitter is switched on and two additional electrode caps are fed into the conduction shaft. Preferably, this sensor 16 is run as an inductive sensor.

This conduction shaft 2 is connected at its lower end to the magazine filling unit 3 and this magazine filling unit 3 is thus filled from above by the conduction shaft 2 with electrode caps.

The magazine filling unit 3 has a magazine connector 4 at one end.

The housing of the magazine connector is similar in design to the housing which attaches the magazine 15 to a cap changer on the machine side and thus ensures a fixed connection between the magazine 15 to be filled and the magazine connector 4.

In the magazine connector 4 two restraint sensors 18 are located to detect the correct position of the magazine 15 in the magazine connector 4 and in the channel of the magazine connector 4 two ball pressure pieces 19 are placed in working order to prevent the accidental fall of electrode caps from the magazine connector 4.

Through a channel corresponding to the electrode cap shape in the conduction shaft 2, the electrode caps are conveyed through the magazine connector 4 to the magazine 15 to be filled.

In the magazine filling unit 3 a sensor 11 is located below the conduction shaft 2 to detect the electrode caps falling from the conduction shaft 2. On the opposite side of the magazine connector 4 a cylinder 8 is arranged, preferably as a pneumatic cylinder, and is fixed to the magazine filling unit 3 by means of the supports 13. The pressure plate 9 connected to the piston rod of cylinder 8 is placed between cylinder 8 and the electrode cap in the channel of the magazine filling unit 3.

If an electrode cap is present in front of the pressure plate 9 in the magazine filling unit 3, it is detected by the sensor 11, preferably an inductive sensor, the cylinder 8 is discharged and the electrode cap is pushed through the magazine connector 4 into the magazine 15.

The signal processing and valve control is carried out by a control which is preferably located in the control box of the valve gear.

In the direction of operation behind the sensor 11, a ball pressure piece 17 shall be so arranged that the electrode caps fed from the conduction shaft 2 do not leave the position and thus the detection range of the inductive sensor 11 unintentionally. The front cover of the magazine filling unit 3 shall be made by means of a transparent cover 10, preferably made of acrylic glass.

In a special design of the solution of the invention, this cover is designed as a maintenance opening.

For this purpose, this cover 10 can be inserted and removed by means of a swallowtail guide. These solutions allow the cover 10 to be removed quickly and can be repaired in the event of a failure or maintenance without any installation effort.

The mounting assembly, consisting of components 5, 6 and 7, is used to adjust the cap filling device relative to the rotor conveyor in all three axes. The sensor 11 must detect a cap, thus ensuring that an electrode cap is located directly in front of the pressure plate 9. The two sensors 18 must detect the stopping levers of the magazine 15 to ensure that a magazine 15 is in the position intended for it at the magazine port 4. If conditions 1 and 2 are met, a switch intended as a starting condition, preferably operated as a foot switch, must be operated to ensure the desired start.

Once conditions 1-3 are met, electrode caps are pushed into the magazine 15 and once the magazine 15 is filled, the cylinder 8 does not reach its rear end position, which is detected by a terminal contact on cylinder 8 and the filling process is interrupted by the control.

If a further filling operation is to be started, the foot switch shall be actuated again and conditions 1 and 2 shall be met.

When using two-shaft cartridges 15, each shaft of the cartridge 15 is filled separately, i.e. the first shaft of the cartridge is filled, the cartridge is then rotated 180° on its X-axis, repositioned and the filling process is restarted to fill the second shaft.

List of references:

1 electrode head turning channel 2 guide shaft 3 magazine filling unit 4 magazine connector 5 mounting assembly 6 mounting assembly 7 mounting assembly 8 cylinder 9 printing unit 10 magazine viewfinder 11 cap recognition sensor 12 spare parts 13 holder 14 shaft viewfinder 15 magazine 16 filling level sensor 17 ball press 18 ball lift 19 ball press

Claims (15)

1. An apparatus designed to load magazines for electrode caps for welding electrodes, characterised by the fact that it consists of an electrode cap rotating conduit (1) which, on one end, is connected to a heliconveyor at the outlet of which the electrode caps will stand on their drilled front side, and which is designed so that the electrode caps are rotated 90° about their Z axis, and which is mounted, with its other end facing the upper end of the guide duct (2) in such a way that the vibrations of the heliconveyor are not transmitted to the other system components, and that the outlet of the electrode cap rotating conduit (1) and the guide duct (2) are facing each other in such a way that the electrode caps are transported in a safe manner, and that said guide duct (2), with its lower end, is connected to the magazine loading unit (3) which has a magazine connector (4) on the side facing the magazine to be loaded (15) which is designed in such a way that it matches the socket used to fasten the magazine (15) to a cap changer on the machine side, and the magazine connector (4) is equipped with locking lever sensors (18) that detect the correct position of the magazine (15) inside the magazine connector (4), and houses two ball pressure pieces (19) inside the conduit of the magazine connector (4) which are aligned in the direction of operation, and that the magazine loading unit (3) holds at least one sensor (11) below the guide duct (2) which detects the electrode caps dropping out of the guide duct (2), and that a cylinder (8), present on the side opposite to the magazine connector (4), is mounted inside the magazine loading unit (3) by way of a retainer (13), and that a pressure piece (9), connected to the plunger shaft of the cylinder (8), is located in-between the cylinder (8) and the electrode cap present in the magazine loading unit's conduit (3), and a ball pressure piece (17) is located behind the sensor (11) in the direction of operation in such a way as to prevent the electrode caps transported from the guide duct (2) from accidentally moving out of the position and leaving the detection zone of the sensor (11).
2. An apparatus according to claim 1, characterised by the fact that it is held in place by a retainer subassembly (5, 6, 7) in such a way as to allow the cap loading unit to be moved along all three spatial axes in relation to the heliconveyor.
3. An apparatus according to claim 1, characterised by the fact that the electrode rotating conduit (1) is firmly attached to the heliconveyor.
4. An apparatus according to claim 1, characterised by the fact that the electrode cap rotating conduit (1) is connected with the guide duct (1) in such a way as to prevent the vibrations of the heliconveyor from being transmitted to the other components of the system.
5. An apparatus according to claim 1, characterised by the fact that the front side of the guide duct (2) is covered with a transparent duct window (14).
6. An apparatus according to claim 5, characterised by the fact that the transparent duct window (14) is made of acrylic glass.
7. An apparatus according to claim 1, characterised by the fact that the front cover of the magazine loading unit (3) is designed as a transparent cover (10).
8. An apparatus according to claim 7, characterised by the fact that the transparent cover (14) is made of acrylic glass.
9. An apparatus according to claim 1, characterised by the fact that the cover (10) is held in place by a locking element (12).
10. An apparatus according to claim 1, characterised by the fact that the front opening of the magazine loading unit (3) is designed as a maintenance port.
11. An apparatus according to claim 1, characterised by the fact that the front opening of the guide duct (2) is designed as a maintenance port.
12. An apparatus according to claim 1, characterised by the fact that the sensors are designed as inductive sensors.
13. An apparatus according to claim 1, characterised by the fact that the cylinder (8) is designed as a pneumatic cylinder.
14. An apparatus according to claim 1, characterised by the fact that the pressure piece (9) has a milled-out portion on the contact side with the electrode cap that matches the cap contour.
15. An apparatus according to claim 1, characterised by the fact that signal processing and valve control is handled by a control unit located inside the switch box of the heliconveyor.