Process technology of grinding used crankshaft wit

New machine tool grinding technology of used crankshaft

new machine tool grinding technology of used crankshaft:

crankshaft is a part with very complex geometry and strong dynamic load. Yongke company is a high-speed grinding machine manufacturer with international leading technology. It has developed jucrank series crankshaft grinding machines since the early 1990s. This series of machine tools adopt the principle of oscillating grinding with the connecting rod journal, and have achieved great success in the automotive industry and its spare parts supply field. This machine tool adopts a high-tech grinding scheme: CBN grinding wheel with high hardness and high wear resistance can be used to complete the woven bag of crankshaft main journal in one clamping. It is one of the materials that are gradually more often used now. 1. Rough and fine grinding of connecting rod journal, flange and shaft head. If a forged or cast crankshaft is ground, the grinding amount of the crankshaft is known, and the grinding amount of each part is almost the same. The price of new crankshafts is very high. Therefore, from the perspective of engine repairers, they are very interested in repairing used crankshafts. Due to the different wear degree of each part of the old crankshaft, each crankshaft has a "unique" geometry. Therefore, before starting grinding, it is necessary to carefully measure, collect the dimensional data of each part, and then carry out grinding. This ensures that all main journals, connecting rod journals and shaft ends obtain the desired geometric tolerances. So far, the radial runout of crankshaft is generally measured based on the axis of crankshaft. Then, if necessary, manually straighten the crankshaft. Finally, each journal is ground with its axis as the reference center (using eccentric fixture). Adopting the above crankshaft grinding method is very time-consuming and labor-consuming, because the crankshaft must be clamped many times in the grinding process. In addition, this method can not achieve the purpose of improving the crankshaft connecting rod journal (crank radius) position. In order to improve the processing efficiency of crankshaft, Yongke company has developed a grinder with integrated measuring device for grinding used crankshaft. The use of this new grinder proves that the pre grinding dimension prediction and the intermediate measurement in the grinding process of the old crankshaft can be omitted on the special measuring equipment. Similarly, the workpiece clamping process related to these inspections during grinding is also omitted. Because the dimension monitoring in the grinding process is real-time monitoring, the grinding quality of crankshaft is greatly improved

process technology

the swing grinding process of connecting rod journal can grind the connecting rod journal with symmetrical arrangement in one clamping, and can obtain extremely high precision and economic benefits. The diameter dimension of the connecting rod journal is formed by interpolation and grinding of the c-axis (rotary movement of the workpiece) and the x-axis (feed shaft). The swing stroke of the x-axis is exactly the stroke of the engine piston. This process technology and the control software equipped with the machine tool cooperate with each other, which can ensure that the old crankshaft of 1~8 cylinder engine can complete dimension measurement and grinding in one clamping

processing 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. It can grind all kinds of crankshafts with rotating diameter up to 220mm and length up to 900mm. Two grinding spindles with driving power of 3OkW are installed on a grinding wheel frame. The two spindles are arranged at an angle of 60 degrees and can be swung to the grinding position in turn. Without re clamping, CBN grinding wheel is used to complete the high-speed grinding of crankshaft main journal and connecting rod journal. 5. The fluctuation range of power supply voltage shall not exceed ± 10% of the rated voltage; The automatic balancing device of the wheel ensures extremely high roundness and grinding accuracy (in a few years) μ M)

1. First measure

according to the wear trace of the crankshaft, before regrinding to the required accuracy, it is necessary to measure the following geometric accuracy: Based on a datum plane, measure the axial spacing, connecting rod journal diameter and main journal diameter of all shafts of the crankshaft; Angular position of crankshaft; The stroke height of the connecting rod journal and the diameter of the shaft head (for installing the shaft end sealing ring). In order to ensure the reliable operation of internal combustion engine, the roundness error of crankshaft main journal and connecting rod journal should be less than 2 ~ 3 μ m。 Based on the reference shaft, the radial runout of the main journal shall not exceed 50 μ m。 The shape of main journal and connecting rod journal can be cylindrical, spherical or convex. The axial spacing of each journal shall not exceed the specified size by 0.2mm

2. Then grind

all the geometric shapes of the crankshaft are given by the control program of the grinder, which just reflects the high flexibility of the machine tool. The 160 TC series CNC system of GE Fanuc company can grind the connecting rod journal only by giving a few parameters. The software used by the machine tool is Yongke's new liquid resin injection molding technology for making basic aerospace components such as wing boxes; Developed by the company itself

3. Alternate measurement and grinding

in the automatic grinding cycle, the crankshaft will be measured, roughly ground, then measured and finally finely ground. The machine operator should first select the appropriate scheme on the console. In order to determine the axial position of the crankshaft, the probe first touches the end face of the shaft end of a main journal. The other probe measures the position and diameter of each connecting rod journal. The numerical control system obtains the initial data about the geometric input size, which is used to automatically correct the zero point. If the collected geometric data is not completely accurate (for example, the position of the connecting rod journal is not very accurate), the CNC system can automatically recognize it in time and consider it when writing the grinding program

4. The optimized grinding process improves the accuracy of crankshaft grinding.

through one-time clamping, the crankshaft main journal, connecting rod journal, flange and shaft end can be machined, and the extremely high geometric accuracy between the grinding parts can be obtained. First, grind each main journal, then support the grinded main journal by multiple center frames, then grind the connecting rod journal, and finally measure each main journal again and grind it to the final qualified size. The repair and grinding of the shaft journal installed with the body seal that can effectively repair the harmful heavy metal ions in the soil is also included in the automatic grinding process. It takes about 10min to measure a typical six cylinder crankshaft and 4min to grind it. The quality of the repaired crankshaft can be tested on a special measuring machine