The track and camber of vehicle axles has a major influence on driving behaviour. In automotive production, track and camber adjustment used to be a time-consuming, manual process. The current generation of machines from AuE Kassel GmbH performs fully automatic track and camber adjustment in less than 60 seconds. Festo components guarantee precision and speed in this process.
In the early days of automotive production, the axles were clamped on steel work tables and adjusted roughly using probes and dial gauges. Final measurement of the chassis was not carried out until the “end of the line”. This last step took up to ten minutes to perform and affected the output rate of the vehicle plant. Today, adjustment is automated and meets the output requirements of manufacturers of vehicles with multi-link rear axles. AuE Kassel GmbH implemented a new rear axle adjustment system for a well-known German car manufacturer in just nine months. Once the axle has been adjusted, it can be installed directly in the vehicle. Based on a gantry design and equipped with drives and valve terminals from Festo, it adjusts track and camber in less than 60 seconds.
Integrated directly in the production process of the car manufacturer, linear conveyor technology transports the axle on a workpiece carrier through the machine in either a longitudinal or a transverse direction. A lifting frame that can be lowered directly above the axle holds all of the Festo components and the tools for adjusting track and camber. After the axle is clamped, counterholders swivel under the subframe mounts of the axle, and later provide the attachment points for the car body. ADNH high-force cylinders with a piston diameter of 100 mm clamp the axle at four positions as accurately as if it were screwed onto the vehicle. The advantage of the ADNH high-force cylinders is in the series connection of two, three or four cylinders with the same piston diameter and stroke. This means that, compared to a conventional cylinder, the force can be doubled, tripled or even quadrupled during the advance stroke. A Festo SMAT sensor on a guide unit detects the level of the wheel hub. The height at which a slide unit must move to the axle can thus be determined.
ADNH high-force cylinders clamp the axle in the system as if it were screwed onto the vehicle.
Powerful argument: the advantage of the high-force cylinders lies in the series connection of up to four cylinders with the same piston diameter and stroke.
In the next step, grippers driven by ADNH high-force cylinders clamp themselves to the hubs. Spring replacement devices actuated by electric motors then drive against the axle and automatically locate the positions where the springs will later sit. Next, the axle is pulsed under load to achieve the setting behaviour on the rubber mountings and joints. The axle is then moved to the K0 position. This is the ideal position of the axle and corresponds to the normal load, when the vehicle is loaded with a defined weight. The track and camber are measured in this position, with a pneumatic cylinder moving directly to the brake disc. The adjusting screws are located independently using track and camber screwdrivers that are also supplied via pneumatic cylinders. The machine detects the relative future position of the wheels automatically using the probes. The adjusting tools adjust the track and camber values in real time and counter with the final screwing torque. The tools then move away and the axle is placed back on the workpiece carrier. The system references itself compared with a master gauge in specified cycles.
To avoid having to interrupt the production process during machine maintenance, the machine can be moved from the conveyor technology area to a specially created maintenance area via racks and guide rails.
A special feature of the new machine are the valve terminals installed directly on lifting frames and vertical slides; this reduces the effort required for tubing and wiring to a minimum. The lifting frame that picks up the axle has two VTSA valve terminals with CPX input modules, separated into the left and right side. In the vertical slide, which carries the hub gripper, there are two smaller VTSA valve terminals with four valves each, which control all the actuators beneath the energy chain of the slide. Thanks to this solution, a supply tube, a power supply and a bus system are all that are needed.