Electric cylinder for welding tongs used in the automotive industry
Bath lubrication
Unique - maintenance free - patented
No matter what type of welding tongs you use – X-welding tongs for spots that are hard to access, or C-welding tongs for simpler constructions – the electric cylinders by SEW‑EURODRIVE are perfectly suitable for both applications and will provide you with a repeat accurate welding power: Our electric cylinders can provide a peak drive force of up to 10 kN in C-welding tongs, and up to 24 kN in X-welding tongs.
Spot welding – A challenging task
There's no accounting for taste when it comes to the looks of a car body – but when it comes to the importance it's greatest task, protecting the passengers from harm as good as possible, everyone will agree upon it. In order to ensure the safety of the passengers, the car body must be torsionally rigid and the other components must be firmly attached to it. In case of alternative drive and mobility concepts, the need to combine a mixture of different materials, such as steel, aluminum, plastic, and composite materials must also be taken into consideration.+
This secure connection is created by thousands of welding spots on the car body, the doors, the hood, etc. Each component contributes to the rigidity of the vehicle and thus to protecting the passengers. In car body manufacturing, the welding spot connections are performed fully automatic with consistent precision and quality.
For exactly this purpose, electric cylinders are used to evenly generate the force of the welding tongs. In order for a welding spot to meet all quality requirements, the welding electrodes must be constantly pressed together and held with the correct amount of force during the welding procedure.
Repeat accuracy, process reliability and durability are just as important quality criteria for the used welding tongs drive, as accurately positioning the welding spots so that the surrounding surfaces aren't damaged. This includes that welding spatter does not occur when a welding tong application functions optimally.
Spot welding – A challenging task
Elektrozylinder für Schweißzangen | Automobilindustrie
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Wartungsfreie Antriebe für Schweißzangen. Keine Zukunftsmusik sondern Realität. Dank der patentieren Ölbadschmierung des Elektrozylinders von SEW-EURODRIVE!
There's no accounting for taste when it comes to the looks of a car body – but when it comes to the importance it's greatest task, protecting the passengers from harm as good as possible, everyone will agree upon it. In order to ensure the safety of the passengers, the car body must be torsionally rigid and the other components must be firmly attached to it. In case of alternative drive and mobility concepts, the need to combine a mixture of different materials, such as steel, aluminum, plastic, and composite materials must also be taken into consideration.+
This secure connection is created by thousands of welding spots on the car body, the doors, the hood, etc. Each component contributes to the rigidity of the vehicle and thus to protecting the passengers. In car body manufacturing, the welding spot connections are performed fully automatic with consistent precision and quality.
For exactly this purpose, electric cylinders are used to evenly generate the force of the welding tongs. In order for a welding spot to meet all quality requirements, the welding electrodes must be constantly pressed together and held with the correct amount of force during the welding procedure.
Repeat accuracy, process reliability and durability are just as important quality criteria for the used welding tongs drive, as accurately positioning the welding spots so that the surrounding surfaces aren't damaged. This includes that welding spatter does not occur when a welding tong application functions optimally.
The mechanical design of our electric cylinders is variable, so that it exactly fits to the used welding tong construction, whether you use X-tongs or C-tongs.
The design of the electric cylinder is selected depending on:
Available installation space
Required stroke
Required welding power
Required speed
Used control system
C-tonge
C-tonge
More properties of the electric cylinders:
Maintenance-free for the entire service life due to the patented bath lubrication
No regreasing required throughout the entire service life
Very high efficiency
Easy to install
Excellent power density / enhanced heat distribution via bath lubrication
Twice the service life as compared to the market standard
Low costs throughout the service life and higher OEE as compressed air preparation of the electric cylinder is not needed
Easily integrated into control systems using flexible encoder systems and connector options
Exact positioning thanks to ball screws using servo drive technology with high-precision encoders
Perfect force and repeat accuracy throughout the entire service life, with no need of additional sensors
Very low noise as compared to pneumatically operated welding tongs
Twice the service life as compared to the market standard
Low costs throughout the service life and higher OEE as compressed air preparation of the electric cylinder is not needed
Easily integrated into control systems using flexible encoder systems and connector options
Exact positioning thanks to ball screws using servo drive technology with high-precision encoders
Perfect force and repeat accuracy throughout the entire service life, with no need of additional sensors
Very low noise as compared to pneumatically operated welding tongs
System integration via plug-and-play
Flexible options regarding motor feedback, connection assignment, and temperature sensors allow for plug-and-play operation with the market-leading control systems for welding robots.
Two variants to integrate electric cylinders are available:
As 7th axis in the robot controller: With this variant, the motion of the robot (6 axes) and the opening/closing motion of the welding tongs (7th axis) are defined by the robot controller, e.g. KUKA, ABB or Fanuc. An welding controller is additionally required to regulate the welding current.
Using the Bosch Rexroth welding control PRC7300 or PRC7400: A robot controller controls the 6 axes, but out electric cylinder and the welding current are controlled and adjusted to each other by the PRC7300 and PRC7400.
Comparison of the 3 systems
Close table
Convetional
Market standard
Future-proof
Design / selection criteria
Pneumatic cylinders
Planetary screw drive with grease lubrication
Ball screw with bath lubrication
Service life
Depending on maintenance
Depending on regreasing
For the entire service life
Speed
Up to 3 m/s
Up to 1.5 m/s
Up to 0.75 m/s
Weight and required space
Low
Moderate
Moderate
Noise level
High
Moderate
Low
Efficiency
7 – 10%
60 – 80%
86 - 92%
Force precision
Low
Force gauge required
+/- 150 N
Positioning accuracy
Moderate
High
High
Maintenance
Regular tightness maintenance every 1.2 million cycles
Regular relubrication every 2 million cycles
Maintenance-free for the entire service life
Controllability in the process (speed, power, starting behavior)
No speed control
Average control, slip-stick effect at the beginning of a stroke
Easy and precise controllability
Environmental impact
Very low efficiency1
More grease required, low efficiency
Oil only needs to be disposed of after the service life ends, very high efficiency
Characteristic stability in case of temperature changes etc. throughout the service
Risk of leaks in the compressed air system, speed depending on the compressed air
Very high stability, independent of the temperature
Very high stability, independent of the temperature
Additionally required tools
Compressed air supply, pressure reduction, sensors, pneumatics controller
Cables for motor feedback and power supply, servo controller, local relubrication tools
Cables for motor feedback and power supply, servo inverter,
Welding spot quality
Repeat accuracy, positioning and force control depending on air leaks, the construction cannot be controlled very accurately
High repeat accuracy, positioning and force control
High repeat accuracy, positioning and force control
Reliability of the overall system
Ca. 11 million cycles when the cylinders are regularly checked and resealed
Ca. 11 million cycles when the cylinders are regularly checked and resealed
