Performance increase of metal bonded CBN tools by cryogenic cooling

与传统工具相比，金属结合剂CBN砂轮具有更高的导热系数，因此有可能改变磨削过程中的热平衡，从而有利于降低工件温度。向零件输入较低的热可以改善零件质量并提高生产率。冷介质冷却技术(低温冷却)有可能增加工件和刀具之间的温差，从而增强接触区的散热和金属粘结CBN刀具的性能潜力。冷却温度对切屑形成、热产生和热分布的影响还不是很清楚。出于这些原因，拟议项目的目的是确定通过实施低温冷却来提高金属结合剂CBN磨具生产率的技术背景。创新的方法是通过使用冷介质来具体影响磨削过程的热平衡。因此，砂轮的温度可以降低，因此更多的热量将转移到刀具中。这一目的有助于在科学水平上更好地理解磨削过程。基于这一基本认识，可以科学地评估这项备受讨论的低温冷却技术的潜力。直到今天，金属粘结CBN工具的使用还不是很普遍，因为可以抵消这些工具高昂采购成本的优势还没有完全量化。对于热关键过程，如齿轮制造中的钢的仿形磨削，可以显著提高生产率和经济效益。

Compared to conventional tools, metal bonded CBN grinding wheels possess an increased thermal conductivity and therefore offer the potential to alter the heat balance during grinding in benefit of a lower workpiece temperature. A lower heat input into the part results in an improved part quality and enables an increase in productivity. The technology of cooling with cold media (cryogenic cooling) offers the potential to increase the temperature difference between workpiece and tool and thereby to enhance the heat dissipation from the contact zone and the performance potential of metal bonded CBN tools. The influence of the cooling temperature on the chip formation, the resultant heat generation and heat distribution is not sufficiently known. For these reasons the aim of the proposed project is to identify the technological background for an increase in productivity of metal bonded CBN grinding tools by implementation of cryogenic cooling. The innovative approach is to specifically influence the heat balance of the grinding process by using cold media. Thereby the temperature of the grinding wheel can be lowered and consequently more heat will migrate into the tool. This aim contributes to a better understanding of the grinding process on a scientific level. Based on this fundamental understanding the potential of the much discussed technology of cryogenic cooling can be evaluated scientifically. The use of metal bonded CBN tools is not very common until today, because the advantages that could balance out the high acquisition costs of these tools are not fully quantifiable yet. For thermally critical processes like the profile grinding of steel in the gearing manufacturing the possibility to significantly increase productivity and economic efficiency is facilitated.