(1) Crankshaft medium frequency induction hardening

The medium frequency induction hardening of the crankshaft will adopt the microcomputer monitoring closed-loop medium frequency induction heating device, which has the characteristics of high efficiency, stable quality and controllable operation.

(2) Crankshaft soft nitriding

For high-volume production of crankshafts, in order to improve product quality, a microcomputer-controlled nitrogen-based atmosphere gas soft nitriding line will be used in the future. The nitrogen-based atmosphere gas soft nitriding production line consists of a front washing machine (cleaning and drying), a preheating furnace, a soft nitriding furnace, a cooling oil tank, a post-cleaning machine (cleaning and drying), a control system, and a gas-making gas distribution system.

(3) Crankshaft surface strengthening technology
 
Ductile iron crankshaft fillet rolling strengthening will be widely used in crankshaft machining. In addition, the composite strengthening process such as round roll rolling strengthening and journal surface quenching will also be applied to crankshaft machining. Forging steel crankshaft reinforcement will be more The ground is journalled with rounded corners.

Analysis of Grinding Process of Crankshaft Thrust Surface Grinding
 
When grinding the quenched steel crankshaft thrust surface, the following three types of burns may occur:

1. tempering burn If the temperature of the grinding zone does not exceed the phase transition temperature of the quenched steel, but the transformation temperature of martensite has been exceeded, the thrust surface table

The layered metal tempered martensite structure will be transformed into a lower hardness tempering structure (sorceite or stellite), which is called temper burn.

2. Quenching burns

If the temperature of the grinding zone exceeds the phase transition temperature, and the quenching effect of the coolant, the surface metal is quenched twice, causing the surface metal to have a secondary quenched martensite structure, the hardness of which is higher than that of the original tempered martensite. High, in its lower layer, due to slower cooling, there is a tempering structure (sordonite or tonite) with a lower hardness than the original tempered martensite. This type of burn is called quenching burn.

3. Annealing burns

If the temperature in the grinding zone exceeds the phase transition temperature and no coolant enters in the grinding zone, the surface metal will produce an annealed structure and the surface hardness will drop sharply. This burn is called an annealed burn. In the crankshaft forming grinding, it is mostly such a burn.

Improve the way to burn burns

Grinding heat is the root cause of grinding burns, so there are two ways to improve the grinding burn: one is to reduce the generation of grinding heat as much as possible; the other is to improve the cooling conditions and try to make less heat generated into the workpiece.