Coolant Effect on Grinding Performance in High-Speed Deep Grinding of 40Cr Steel

High-speed deep grinding (HSDG) technology was developed based on high-speed and creep-feed grinding techniques. What mainly distinguishes HSDG from creep-feed grinding is its employment of a significantly higher wheel speed. Because the higher wheel speed results in a decrease in the undeformed chip thickness, HSDG is thus capable of achieving high stock removal rates and producing a high surface quality throughout the workpiece. However, the increase in wheel speed leads to the formation of a strengthened air barrier around the grinding wheel periphery, which is a great obstacle to the impinging of coolant into the grinding zone. Additionally, the higher wheel speed will also generate greater grinding heat in the grinding zone, thus resulting in a higher temperature.'This increases the risk of thermal damage on the workpiece, such as burns and cracks, especially when grinding metals and alloys. In order to take advantage of the full potential of HSDG technology, effective cooling must be employed. Great research efforts have been directed toward investigating effective coolant supply technologies for the HSDG process. 71° Previous works focused on the development of coolant nozzles for high-speed grinding, which could block the air barrier formation and help smoothly guide the coolant entering the grinding zone. There are several drawbacks regarding these nozzles. First, a gap between the wheel and the air-wiper in the nozzle still exists, which affects the coolant supply when operating at an extremely high speed. Second, the air blocking alters the coolant flow direction, thus resulting in an increase of 30-50% in spindle power. Third, special grinding wheels are required if there is direct contact between the wheel and the air wiper. This article will report on the development of a "closed" coolant shoe, which can overcome the limitations of previous coolant nozzles, and the effect of the new nozzle on the grinding performance in HSDG of 40Cr steel.