Diagonal Grinding for Perfect Surfaces—Precisely Control the Grinding of Crankshafts
The requirements for modern engines have soared in recent years. Improved performance and efficiency, while ensuring lower consumption, requires the best quality of all components. Crankshafts must have perfect surfaces not only at the end faces of the connecting rod and main bearings, but also at the transitional radii between the bearing face and the collar, in order to guarantee high tensile strength.
Due to the fact that internal stresses are released into the component during machining, which cause the dimensions of the component to change, the machining operation is still frequently broken down into pre-grinding and finishing of the crankshaft – leading to longer process times. It is important to not neglect the wear of the grinding wheels since the transition between the radii and the flat lateral collar put a substantial amount of stress on the grinding wheel. The grinding of the cylinder diameter and the machining of the flat collar on the crankshaft have different requirements. While the central diameter receives its perfect, parallel surface in a multistage process (from rough-machining to finish-machining, then fine finish-machining and sparking out), the somewhat coarser collar machining requires significantly fewer processing steps.
Increasing the Pace of the Complete Process
All of this is taken into account during diagonal grinding and ultimately leads to the holistic crankshaft grinding process, during which both the grinding speed and the movement of the axes can be controlled independently - always perfectly adapted to the respective crankshaft grinding subprocess (pre-grinding or finishing, resp. diameter or shoulder grinding).
The independent, highly precise control of the grinding speed and the movement of the axes allowed the drastic reduction of the processing times in crankshaft production.
For example, the preliminary grinding of pin bearings, center bearings, and split-sleeve bearings is completed in approximately one third less time than with double plunge grinding, which is often used. The grinding process for a crankshaft with seven bearings now takes only 20 minutes instead of the 35 that was required before. The tool costs are also reduced, because the grinding wheel edges are impacted in a different way. This reduces tool consumption per component by about one third.
- Pre-grinding and finishing in a single clamping operation
- Low wear of grinding wheels leads to decreased tool costs
- Processing times are reduced by more than 40% compared to double plunge grinding
- Grinding the main and pin bearings as well as the shoulders in a complete process