Machining of a flat baseplate is key to create a good pump and motor alignment. To ensure this the mounting pads on a baseplate require corresponding surfaces shall be flat, parallel and in the same plane. As baseplates are manufactured by means of welding beams and plates together, stresses in the construction will appear that make the baseplate bend. These stresses can be reduced through applying the process of stress-free annealing. However, even after relieving the stresses the mounting pads are not parallel and in the same plane positioned.
A common mistake, to save time and money during the production process, is to mount the baseplate on the milling machine and pulling it straight on the machine bed. When after the milling process the clamping devices are loosened, the baseplate moves back to its tension free form and mounting pads move towards an undesired position.
To guarantee that the baseplate mounting pads remain parallel and in the same plane after the baseplate machining has been finished, Rodelta makes use of an extra positioning plates, see picture below, welded under the baseplate at fixed distances from the mounting locations in combination with an extra machining step in the process of manufacturing baseplates.
After welding and stress-free annealing, the baseplate will be placed upside-down on the machine bed with these positioning plates facing upwards and supported by machine jacks and lightly fixed (not under tension).
In this position the positioning plates will all be milled so that their surfaces are flat, parallel and in the same horizontal plane.
Subsequently the baseplate will be turned on the milled correction support plates and again secured to the machine bed. The baseplate is now attached without tensioning and the machining of the mounting pads can be carried out. After machining, the baseplate will remain in its tension-free shape when the clamps are loosened so that the positions of the mounting pads remain parallel and in the same plane.
During the pump assembly phase when placing the pump and motor, the pump and motor must always be aligned with a laser. In the baseplate design a 3mm alignment space is incorporated at motor side for correct alignment by using motor shims.