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The most important task of a car body is to protect the occupants. To ensure this occupant contactor, the body must be torsionally rigid and be able to accommodate the other add-on parts.
A safe and stable car body is created by countless welding points on the body, the doors, the bonnet, etc. Each component contributes its part to the stiffness of the vehicle and thus to the contactor of the occupants. These spot-welded joints are now produced fully automatically, with consistent precision and quality.
This is exactly where Electric cylinders are used. They ensure that the welding gun generates an even force. For a spot weld to meet the quality requirements, the welding electrodes must constantly compress the weld metal with a defined force during each welding process and maintain the force during the welding process. The repeat accuracy, process reliability and durability are are just as important quality criteria for the welding gun drive used as the cleanly placed welding spots without damaging the surrounding surfaces; i.e. welding spatter does not occur when a welding gun application is functioning optimally.
The mechanical design of our electric cylinders is variable, depending on whether you need an X- or C-tongs to fit exactly into the respective welding gun design.
The design of the electric cylinders depends on:
Flexible options for motor feedback, pin assignment and temperature sensors enable plug-and-play operation on the market-leading control systems for welding robots.
Two variants are available for the integration of electric cylinders:
| Design/selection criteria | Conventional | Market standard | Future-proof | |
| Pneumatic cylinder | Planetary roller screw with grease lubrication | Solutions from SEW-EURODRIVE Ball screw with patented oil bath lubrication | ||
| Service life | Depending on maintenance | Dependent on regreasing | Lifetime | |
| Speed | Up to 3 m/s | Up to 1.5 m/s | Up to 0.75 m/s | |
| Space requirement and weight | Low | Medium | Medium | |
| Noise level | High | Medium | Low | |
| Energy efficiency | 7 - 10 % 1 | 60 - 80 % 2 | 86 - 92 % | |
| Force accuracy | Low | Force sensor required | +/- 150 N | |
| Positioning accuracy | Medium | High | High | |
| Maintenance | Regular seal maintenance every 1.2 million cycles | Regular relubrication every 2 million cycles | Maintenance-free for life | |
| Controllability in the process (speed, force, starting behaviour) | No speed control | Average controllability, slip-stick effect at the start of the stroke | Simple and precise controllability | |
| Environmental impact | Very low efficiency1 | Higher grease requirement, low efficiency | Used oil only accumulates at the end of the service life, very high efficiency | |
| Characteristic stability over the service life, with temperature changes, etc. | Risk of leakage in the compressed air system, speed depends on the compressed air | Very good stability, independent of temperature | Very good stability, independent of temperature | |
| Addendum devices required | Compressed air supply, pressure reducers, sensors, pneumatic control unit | Cables for motor feedback and power supply, servo controller, local relubrication tools | Cable for motor feedback and power supply, servo inverter | |
| Welding spot quality | Repeat accuracy, positioning and force control dependent on air leakage, design less precisely controllable | High repeat accuracy, positioning and force control | High repeat accuracy, positioning and force control | |
| Reliability of the overall system | Approx. 11 million cycles with regular testing and sealing | 15 million cycles with lubricant change after 7.5 million cycles | 20 million cycles | |
| Electric cylinder Size | Hub | Maximum feed rate | Peak feed force | Durable Feed force | Weight |
| mm | m/s | kN | kN | kg (with stroke length 160 mm) | |
| 50 | 70 - 600 | 0.75 | 2.65 - 8 | 0.6 - 3.2 | 5.8 - 13.6 |
| 63 | 60 - 600 | 0.45 | 10 | 2.4 - 5.2 | 8.8 - 18.6 |
| 71 | 100 -1200 | 0.45 | 18 - 24 | 6.2 - 12 | 21.6 - 48.7 |
| Electric cylinder | A | B | H | Y | L |
| 50 Lengths S/M/L | 73 | 217 | 70 / 100 / 150 / 200 / 300 / 400 / 600 | 221.5 / 251.5 / 301.5 / 351.5 / 451.5 / 581.5 / 781.5 | Overall length S: 174.5 Overall length M: 223.5 Overall length L: 262.5 |
| 63 Lengths S/M/L | 88 | 245.5 | 60 / 100 / 160 / 180 / 200 / 400 / 600 | 235.5 / 275.5 / 335.5 / 355.5 / 375.5 / 607.5 / 807.5 | Overall length S: 252.8 Overall length M: 302.8 Overall length L: 352.8 |
| 71 Lengths S/M/L | 115 | 295 | 100 / 160 / 200 / 400 / 600 / 800 / 1000 / 1200 | 326 / 386 / 426 / 686 / 886 / 1146 / 1346 / 1546 | Overall length S: 229 Overall length M: 254 Overall length L: 304 |
| Electric cylinder | A | B | H | Y | L |
| Size 50 Lengths S/M/L | 73 | 120.7 | 70 / 100 / 150 / 200 / 300 / 400 / 600 | 221.5 / 251.5 / 301.5 / 351.5 / 451.5 / 581.5 / 781.5 | Overall length S: 156.4 Overall length M: 195.4 Overall length L: 234.4 |
| Size 63 Overall lengths S/M | 88 | 245,5 | 60 / 100 / 160 / 180 / 200 / 400 / 600 | 235.5 / 275.5 / 335.5 / 355.5 / 375.5 / 607.5 / 807.5 | Overall length S: 163.7 Overall length M: 214.2 |
| Size 71 Lengths S/M/L | 115 | 295 | 100 / 160 / 200 / 400 / 600 / 800 / 1000 / 1200 | 326 / 386 / 426 / 686 / 886 / 1146 / 1346 / 1546 | Overall length S: 211 Overall length M: 236 Overall length L: 286 |