Optimization of guide pads for the BTA deep hole drilling of high alloyed steels by microfinishing

被引:14
作者
Biermann D. [1 ]
Abrahams H. [1 ]
Goeke S. [1 ]
机构
[1] Institute of Machining Technology, Technische Universität Dortmund, 44227 Dortmund
关键词
BTA deep hole drilling; High alloyed steels; Microfinishing; ta-C-Coating;
D O I
10.1007/s11740-013-0505-z
中图分类号
学科分类号
摘要
The boring and trepanning association deep hole drilling of materials with a high tendency to adhesion, such as high alloyed-steels, is characterized by a poor surface quality of the bore hole. Material particles adhere to the guide pads that are positioned on the circumference of the drill head and that are normally responsible for the outstanding workpiece quality. In order to prevent this mechanism the guide pads were coated with an innovative amorphous and tetrahedral bonded (ta-C)-coating. This coating has a reduced friction coefficient of 0.1 against steel and a hardness coefficient of about 7,000 HV. To use the benefits of this ta-C-coating the pre- and the after-treatment of the uncoated carbide substrate and ta-C-coated guide pads are essential. For these process steps a microfinishing process was carried out as an alternative to the conventional treatment by polishing and brushing. The microfinishing of the uncoated guide pads effects a smooth surface that is necessary for an optimum bonding strength of the ta-C-coating at the carbide substrate. Furthermore the chamfer edge in the lead-in-area is rounded which reduces the mechanical load at this specific area during the process. The finishing process of the coated guide pads reduces the coating defects and improves the friction coefficient. Thus, the wear behavior of the guide pads is improved because of the better friction conditions during the drilling process of high alloyed steels. © 2013 German Academic Society for Production Engineering (WGP).
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页码:33 / 40
页数:7
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