Planetary drive axles used in heavy duty equipment like aircraft towing tractors and amphibious vehicles, consist of many different components which must generally withstand heavy loads. Therefore the fabrication, as well as the painting of these components, is subject to the most stringent technical requirements.
Optimum integration into the manufacturing flow
For blast cleaning of the various components after flame and laser cutting, this axle manufacturer integrated two Rösler wire mesh belt shot blast machines into his overall manufacturing setup. The two blast systems had to be adapted to the local space conditions and were placed in the immediate vicinity of the respective cutting stations. This allows the blast cleaning of parts with lengths of up 88 inches (2200 mm) and weights of up to 550 lbs (250 kg) per running meter without long transport distances and, therefore, without the need for costly transport racks. Since the parts are still relatively hot (270° F/130° C), the inlet and outlet transport conveyors had to be equipped with wire mesh belts. The blast chamber is equipped with four Hurricane® H28 blast turbines with an installed power of 11 kW each. This “firepower” provides plenty of blast intensity and results in short cycle times. Since wear resistance was a major customer requirement, the inlet, blast and outlet chambers were lined with wear resistant material, and the wire mesh belts were made from manganese steel. To comply with the demand for a high degree of automation - with only one person operating the machines - the continuous feed shot blast machines are equipped with special control panels, providing the operator with a wide range of operating alternatives.
Paint preparation with a special roller conveyor shot blast machine
After welding the axles they must be painted (primarily for corrosion protection). In an intermediate manufacturing step the welding seams must be cleaned by removing welding slag and other impurities from the parts surface which until recently was done manually. To improve the paint preparation quality and make it more cost effective, the customer also invested in a Rösler roller conveyor blast cleaning system, designed for complex welding constructions. This had to be integrated into an existing building, as well as into an already operational manufacturing setup. Since the building layout did not allow the installation of a monorail hanger system, the customer chose a custom engineered roller conveyor shot blast machine RRBK 11/11-So designed for axles with dimensions of up to 4000 x 1000 x 1000 mm LxWxH (160 x 40 x 40 inches). This shot blast machine is equipped with eight Hurricane® H 32 blast turbines. The placement of the turbines, determined with a special 3D computer simulation, ensures that even with very complex parts geometries all welding seams are absolutely clean. Thirty different blast cleaning programs stored in the control panel allow an easy adaptation of the shot blast process to various components for blast cleaning.
The high parts weight of up to 800 lbs (400 kg) per running meter required the special engineering of the transport system. High part weights of up to 3,530 lbs (1.6 metric Ttons) was also the reason for reversing the transport direction of the roller conveyor. This allows removing the finished parts from the inlet roller conveyor at the load station and eliminates the requirement for a material handling station at the exit roller conveyor. The processing time per axle amounts to six minutes maximum.