Analysis of force overtime failure of pneumatic servo welding tongs

Pneumatic circuit diagram of welding tongs.

Safety function protects the device from starting, load voltage US2 is disconnected

Structure in which the safety function stops when US2 is turned off

Structure of the safety function stop without closing US2 1. Nominal pressure, 5 ... 10 bar. 2. Maximum operating pressure, 12 bar. 3. Permissible overpressure (t = 1 sec. without damage), 16 bar max. 1 sec. 4. Operating medium at main air inlet 1 of the controller, dry air, unlubricated, pressure dew point at least 10 K below the medium temperature. 5. Operating voltage – load – logic supply 24 V ±10 %, 24 V ±10 %. 6. Operation (load and logic supply). <4 A, only if no other modules and valves are connected to the fieldbus node. 7. Maximum permissible load current of the digital outputs, 250 mA. 8. Ambient temperature, 0 ... +50 °C. 9. Storage temperature, -10 ... +60 °C. 10. Medium temperature, 5 ... +40 °C. 11. Maximum permissible relative humidity, without condensation, 90 % 12. Protection class, IP 65. 13. Electromagnetic compatibility – Radiated interference – Interference immunity. 14. Shock, vibration resistance ----- Severity level 1. 1) A 5 µm filter (0Z1) must be installed in front of the main compressed air connection of the servo box. 2) All connections must be sealed with suitable protective caps. Unused ProfiNet connections must be sealed with suitable plugs. 3) The component is intended for use in an industrial environment. Loading the basic parameter set The basic parameters include the optimized parameters – Position control – Force control – 7. Axis operation – Suitable cylinder type – Electrode cap parameters 1. Open a new project The folder containing the standard parameter files will be opened (..DefaultPaeter) 2. Select the parameter file xxx.spz

A standard parameter set should be stored for all types of welding guns. For example: If using a X100 gun model with a diameter of 140mm, use the parameter file "X100_d140m.spz". 3 Set the maximum electrode force Insert the maximum electrode force from the data sheet or nameplate of the gun

4 Load data into the controller

Instructions for replacing the "90" cylinder displacement Step 1: Unscrew and remove the 4 screws on the sealing cover of the circuit part.

Step 2: Unscrew and remove the 4 screws that secure the circuit board.

Step 3: Remove the circuit board - remove the wire plug - be careful to keep

Clean the two O-rings! Step 4: Remove the circlip at the bottom of the cylinder.

Step 5: Remove the cable socket

Step 6 Remove the two screws securing the displacement sensor.

Step 7: Carefully pull the cable to remove the sensor.

Step 8: Install the new displacement sensor into the cylinder - Be careful to align the screw holes - Use Loc thread glue - Tighten the screws to 0.7 Nm

STEP 9: Route the sensor cable out the top through the internal cable guide.

Step 10: Install the socket into the cylinder (do not install the retaining ring), then insert the plug of the cable into the circuit board. Use tweezers if necessary.

Step 11: Fix the circuit board Note: - Do not pinch the cables! - The seal is positioned correctly Use Loctite 243 on the screws, do not use thread glue on the screws pointed by the arrows in the picture. The tightening force of the screws is 0.7 Nm

Step 12: Put the cover of the circuit board on the board and pay attention to the position of the sealing paper.

Step 13: Use Loctite 243 on the screws. The tightening force of the screws is 2 Nm.

Step 14: Install the circlip

Step 15: Put a DOM label on the cylinder to identify the new sensor. Instructions for replacing the "100/125/140/160" cylinder displacement sensor Step 1: Use a 3.0 Allen wrench to loosen the four screws on the cover and remove it. Remove the cover

Step 2: Loosen the 4 screws and remove the circuit board. Use a 2.5" Allen wrench here. Remove the circuit board

Step 3: Remove the two plugs from the circuit board. CAUTION! Be careful not to drop the seal of the pressure sensor. Check that the seal is in the correct position.

Step 4: Use a wrench to unscrew the sealing connector on the end cap.

STEP 5: Use a wrench to unscrew the cable socket and carefully remove it.

Step 6: Loosen the two hexagon socket screws that secure the displacement sensor and pull the cable out of the displacement sensor.

Step 7: Insert the plug into the new displacement sensor, making sure the plug is oriented correctly.

Step 8: Place the new displacement sensor into the cylinder, paying attention to the position of the mounting screw holes to fix the sensor. Step 9: Place the new sensor into the cylinder until it bottoms out. - Note the position of the mounting screw holes - Use Loctite to tighten the screws - The tightening force of the screws is 0.7 Nm

Step 10: Route the displacement sensor cable through the guide.

Step 11: Pass the cable of the cable socket through the hole and tighten the cable socket. Pay attention to the tips in the picture (the direction of the socket)!

STEP 12: Insert the plug into the board. Use tweezers if necessary.

Step 13: Fix the circuit board Note: - Do not pinch the cables! - The seal is positioned correctly Use Loctite 243 on the screws, do not use thread glue on the screws pointed by the arrows in the picture. The tightening force of the screws is 0.7 Nm

Step 14: Note the position of the seal. The 4 screws here need to be tightened with Loctite 243. The tightening force of the screws is 2 Nm.

STEP 15: Use a file brush to clean the seal fasteners.

STEP 16: Install the retaining seal and tighten using a torque of 135 Nm.

Incorrect force calibration causes "force timeout" (boost timeout) which is generally caused by the following reasons:

Unable to reach the set pressure within 2 seconds. Check the air supply and see if the pressure is high enough. 1. Insufficient supply pressure 2. Incorrect cylinder model. The model set in the software does not match the actual model used 3. The proportional flow valve MPYE is faulty, resulting in insufficient flow 4. "Force calibration" is incorrect

"Force calibration" is incorrect,

The pressure ratio of the welding clamp is about 4.0, that is, the main cylinder outputs a pressure of about 4000N, which can make the electrode cap pressure reach about 1000N. This ratio is too large, so when using a large welding pressure value, the pressure generated by MPYE cannot reach the welding pressure.

The "force calibration" status after calibration is as follows:

The pressure ratio is about 1.4, that is, the main cylinder outputs 1400N pressure, which can make the electrode cap pressure reach about 1000N. After changing the pressure calibration, the welding clamp returns to normal

Editor: Huang Fei