Influence of chamfer width on cutting performance

The chamfering design of the PCBN tool determines the tool life, especially the chamfering width. In previous articles, we looked at the effects of chamfering angle, coating and even sharpening quality on cutting performance.

       The author has been looking for an article that introduces the width of the chamfer, but is surprised to find that there are few journal articles that describe the width of the chamfer alone.

       The author believes that the reason for this is because: on the one hand, the chamfering width is the most commonly used and preferred method to solve the problem of PCBN tool chipping, and the majority of practitioners are familiar with its mode of action. On the other hand, there is indeed a lack of good quantitative evaluation criteria for measurement.

       However, it is not easy to choose the appropriate chamfer width: the chamfer width is too small, the tool is too sharp, and the tool itself has poor anti-chipping performance, but if the chamfer width is too large, the "actual rake face" with negative rake angle is formed. ”, the chip curls excessively, which increases the cutting load on the tool and also causes tool chipping.

       Therefore, the words "too far too late" to describe the process of adjusting the width of the chamfers are appropriate.

       In the research process, "cutting force" is usually selected as the dependent variable to measure the impression of the independent variable chamfer width parameter change on the cutting performance.

       The author selects the article "Influence of PCBN Tool Chamfer Width on Cutting Force" published by Xia Xiquan, Hefei University of Technology, to introduce the influence of chamfer width.

       Research Background

       In the cutting process, the size of the cutting force directly affects the size of the cutting temperature, and has a great influence on the service life of the tool, the machining accuracy and surface quality of the workpiece. At the same time, in production and processing, the design and use of machine tools, fixtures, and tools must also consider cutting forces.

Over the years, people have continued to study the influencing factors of cutting force.

       Wang Xiaoping used tools with different chamfering widths to perform finite element simulation analysis on cutting stainless steel materials. The results show that the cutting force increases with the increase of the chamfer width.

       Ji Wei conducted a finite element simulation analysis on the turning of nickel-based superalloys by PCBN tools with different chamfering widths. The results show that the cutting force is more stable when the width of the negative chamfer is less than 0.35mm.

       Li Panlai used PCBN tools with different chamfer widths to conduct cutting tests on vermicular graphite cast iron. The results show that as the width of the chamfer increases, the cutting force also increases.

       Chen Tao et al. used PCBN tools with different negative chamfer widths to conduct hard cutting tests on quenched steel GCrl5. The results show that the negative chamfer width has a great influence on the cutting force and cutting temperature.

       The main cutting force, radial cutting force and cutting temperature increase with the increase of the negative chamfer width.

       Choudhury I.A. et al. conducted turning experiments on medium-carbon low-alloy steels using carbide tools. The results show that the main cutting force increases with the increase of the width of the negative chamfer, and the increase of the feed force is more significant, whether in continuous or interrupted turning.

       Khalili K. et al. carried out finite element analysis on the process of cutting low carbon and low alloy steel with carbide tools. The results show that the influence of the chamfer width on the thrust is more significant than the cutting force.

       Compared with the research on cutting other materials, the research on the cutting force of powder metallurgy materials with PCBN tools with different negative chamfering widths is relatively rare.

       In order to study the influencing factors of cutting force, this paper uses PCBN tool to conduct turning test on powder metallurgy valve seat, and analyzes the influence of negative chamfer width of different PCBN tools on cutting force. This study has guiding significance for optimizing the geometric parameters of PCBN tools

       Test plan and conditions

       Finish turning the outer surface of the valve seat ring on a common CA6140 lathe and dry cutting. Cutting forces were measured using a Kistler three-way force measuring system.

       The measuring system consists of Kistler 9527B three-way force measuring instrument, charge amplifier, A/D data converter, Dyno ware force measuring software and so on.

       The test material is the powder metallurgy valve seat ring of model V571, which is recorded as sample A. The chemical composition (except Fe) and physical properties of V57l valve seat ring are shown in Table 1 and Table 2, respectively.

       The dimensions of the workpiece used in the test are as follows: the inner and outer diameters of the upper mouth are D26mm and D33mm, respectively, the inner and outer diameters of the lower mouth are D28.29mm and D33mm, respectively, and the width is 6.05mm.

       The external turning was carried out in the test, and the physical and mechanical properties of the selected PCBN tools were as follows: the CBN content was 85%, the binder was TiN, the CBN particle size was 3μm, the thermal conductivity was 217W/m·K, and the hardness was 4000-5000HV.

       The actual installation angle of the tool and the negative chamfering parameters of the tool are shown in Table 3 and Table 4, respectively.

  Select cutting parameters and tool negative chamfering parameters according to actual production conditions. In order to understand the influence of the negative chamfer width of PCBN tool on the cutting force, a single factor experiment was carried out under the condition that only the negative chamfer width was changed.

       Test Results and Analysis

       The cutting conditions selected for the test are: cutting speed vc=100mm/min, feed rate f=0.08mm/r, cutting depth ap=0.2mm, negative chamfering angle of -20°, negative chamfering width of 0.05, 0.10, 0.15, 0.30mm.

Select cutting parameters and tool negative chamfering parameters according to actual production conditions. In order to understand the influence of the negative chamfer width of PCBN tool on the cutting force, a single factor experiment was carried out under the condition that only the negative chamfer width was changed.

Test Results and Analysis

The cutting conditions selected for the test are: cutting speed vc=100mm/min, feed rate f=0.08mm/r, cutting depth ap=0.2mm, negative chamfering angle of -20°, negative chamfering width of 0.05, 0.10, 0.15, 0.30mm.