New processing technology of grinding shaft parts-Peel Grinding

What is Peel Grinding?

Peeling grinding usually uses a CBN wheel with a width of 4-6mm or so, and a 10-15°chamfering area is set in the abrasive layer. Its width is generally 1-2mm, and the width of the outer circular part is 3-5mm. The chamfered area is used for rough grinding to remove the allowance, while the outer circular part is used for fine grinding to obtain the size and precision of the machined surface. During grinding, the grinding wheel rotates at a high speed (usually 90-150 m/s) and moves axially with a certain grinding cutting depth to achieve axial feed (>100mm/min), stripping the material from the surface of the workpiece, similar to turning processing. Because the grinding wheel is very thin, the workpiece speed during grinding needs to be high enough to avoid spiral marks.

Advantages of Peel Grinding

1. High grinding efficiency.

2. High grinding accuracy.

3. When processing different workpieces, there is no need to change the tooling, only need to change the machine tool processing program, reduce the adjustment time of the machine tool, improve the processing flexibility, improve the processing efficiency.

4. Can process different materials of the workpiece on the same platform, with good processing flexibility.

Peeling grinding uses a very thin CBN grinding wheel Without the use of traditional forming grinding wheels, the complex shape of the workpiece can be easily grinded by CNC program control.

5. Can process slender shafts which are prone to deformation and vibration in the grinding process.

Application of Peel Grinding

1.Replace the traditional forming plunge feed grinding: the CBN grinding wheel for peeling grinding does not need to change the grinding wheel and dressing tool frequently when processing different workpiece, reduces the grinding setting and adjustment time, and improves the processing flexibility; At the same time, the contact area between the grinding wheel and the workpiece is smaller, so the required grinding force is smaller, and the grinding vibration and workpiece deformation caused by excessive grinding force are avoided, and the machining accuracy is improved;

Traditional Form Plunge Feed Grinding                    Peel Grinding

2.Replace hard turning or as a hard turning after the process: the use of CBN grinding wheel for peeling grinding can improve the dimensional accuracy of the workpiece and surface machining quality

Prerequisites for peeling grinding

Peeling grinding has a lot of advantages, to give full play to its advantages, must be “good horse with good saddle”. Therefore, a successful peeling and grinding requires the following prerequisites:

1. Due to the high grinding speed required by peeling grinding, any vibration may cause grinding striations and even burns. Therefore, whether the workpiece clamping system or the grinding wheel spindle system, the grinding system of the whole grinding machine needs to have a good rigidity

2. Due to the high grinding speed of peeling, the dynamic balance of the grinding wheel is very important. The grinding wheel usually needs to be balanced twice. One is the dynamic balance of the grinding wheel during the production process, and the other is the automatic calibration dynamic balance after it is installed on the machine

3. Due to the extremely high temperature generated during high-speed grinding, it is necessary to have a large enough flow of coolant, and the flow rate should be consistent with the speed and direction of the grinding wheel as far as possible to ensure adequate cooling

4. The cooling system also requires high pressure and is often equipped with high pressure flushing nozzles, especially when grinding soft and sticky materials. These cooling devices are especially important to prevent the surface of the grinding wheel from becoming clogged with chips, resulting in increased load on the grinding wheel

5. If the VIT CBN grinding wheel is used for peeling and grinding, the online dressing system and contact dressing mode need to be used. A series of dressing processes, from the contact between the grinding wheel and the roller, to roughing and finishing, need real-time monitoring.

Using VIT CBN wheel for peeling grinding

(1) Compared with electroplated CBN wheel, VIT CBN wheel has the following advantages:

1. Easy to dress.

2. Very good self-sharpening performance.

3. The shape and precision of grinding wheel can be guaranteed by dressing.

4. Multi-porosity structure, ensure good penetration of coolant, take away chips.

5. Longer lifespan.

6. The substrate of the grinding wheel can be reused only by replacing and bonding the new CBN abrasive layer.

(2) Keys to choose VIT CBN wheel for Peel Grinding

Vitrified CBN grinding wheels used for peeling grinding require a high material removal rate and produce as little grinding heat as possible under the premise of efficient processing to avoid a series of grinding problems such as burns and cracks. Therefore, it is required that the ceramic CBN grinding wheel has a more open organization to ensure enough chip space. At the same time, the normal micro-crushing of the passivated abrasive particles is also required to ensure the sharpness of the grinding wheel, so as to obtain efficient cutting performance. In addition, for peeling grinding, in the case of high speed grinding, the chamfering area of the grinding wheel is easy to edge collapse, abrasive particles are easy to fall off, resulting in a low grinding wheel life, and will affect the quality and precision of the workpiece surface. Therefore, how to achieve high efficiency and ensure the service life of the grinding wheel is the key to select the ceramic CBN grinding wheel for peeling and grinding. However, the traditional CBN grinding wheel with ceramic bond is difficult to ensure that the grinding wheel has a high porosity because of its bond system characteristics.