The crankshaft is a part with very complex geometry and strong dynamic load. JUNKER is a high-speed grinding machine manufacturer with international leading technology. It has been developing JUCRANK series crankshaft grinding machines since the early 1990s.
The machines of this series are ground on the principle of oscillating grinding with the connecting rod and have achieved great success in the automotive industry and in the supply of spare parts. The machine adopts a high-tech grinding solution: the rough grinding and fine grinding of crankshaft main journals, connecting rod journals, flanges and shaft heads can be completed in one clamping with a high-hardness, high-wear-resistant CBN grinding wheel .
If grinding a forged or cast crankshaft, the amount of grinding of the crankshaft is known, and the amount of grinding is almost the same in all parts. The price of new crankshafts is high, so from the engine repairer side, there is a lot of interest in restoring used crankshafts. Each crankshaft has a "unique" geometry due to the different levels of wear in various parts of the old crankshaft. Therefore, before starting grinding, careful measurements must be taken, and dimensional data of each part must be collected before grinding. This ensures the desired dimensional tolerances for all main journals, pin journals and shaft ends. So far, the radial runout of the crankshaft is generally measured based on the axis of the crankshaft. Then, manually straighten the crankshaft if necessary. Afterwards, each journal is ground with its axis as the reference center (using an eccentric jig). Using the above-described method of grinding a crankshaft is very time-consuming and labor-intensive, because the crankshaft must be clamped several times during the grinding process. In addition, this method cannot achieve the purpose of improving the position of the crankshaft connecting rod journal (crank radius).
In order to improve the machining efficiency of crankshafts, JUNKER has developed a grinding machine with integrated measuring device for grinding used crankshafts. The use of this new type of grinding machine proves that pre-grinding dimensional prediction and intermediate measurements during grinding of old crankshafts can be dispensed with on dedicated measuring equipment.
Likewise, the workpiece clamping process associated with these inspections during grinding is also omitted. Since the dimension monitoring during the grinding process is real-time monitoring, the grinding quality of the crankshaft is greatly improved. Process technology The process of oscillating and grinding the connecting rod necks can grind the connecting rod necks with symmetrical arrangement in one clamping, and can obtain extremely high precision and economic benefits.
The diameter of the connecting rod is obtained by interpolation grinding of the C axis (rotational motion of the workpiece) and the X axis (feed axis). The swing stroke of the X-axis is the stroke of the engine piston. This process technology and the control software equipped with the machine tool cooperate with each other to ensure that the old crankshafts of 1-8 cylinder engines can be dimensioned and ground in one clamping. Machining scheme of deformed varieties The design scheme of this machine tool can realize the overall grinding of a large number of different types of crankshafts.