A Comparison of the Probes with a Cantilever Beam and a Double-Sided Beam in the Tool Edge Profiler for On-Machine Measurement of a Precision Cutting Tool

This paper describes a comparison of the mechanical structures (a double-sided beam and a cantilever beam) of a probe in a tool edge profiler for the measurement of a micro-cutting tool. The tool edge profiler consists of a positioning unit having a pair of one-axis DC servo motor stages and a probe unit having a laser displacement sensor and a probe composed of a stylus and a mechanical beam; on-machine measurement of a tool cutting edge can be conducted with a low contact force through measuring the deformation of the probe by the laser displacement sensor while monitoring the tool position. Meanwhile, the mechanical structure of the probe could affect the performance of measurement of the edge profile of a precision cutting tool. In this paper, the measurement principle of the tool edge profile is firstly introduced; after that, slopes and a top-flat of a cutting tool sample are measured by using a cantilever-type probe and a double-sided beam-type probe, respectively. The measurement performances of the two probes are compared through experiments and theoretical measurement uncertainty analysis.

Development of High-Performance Polycrystalline CVD Diamond-Coated Cutting Tools Using Femtosecond Lasers

Pulse laser grinding (PLG), an edge-shaping process, was developed previously to implement high-performance cutting tools. In this study, two femtosecond (fs) lasers with wavelengths of 1045 nm and 257 nm were used to conduct PLG on chemical vapor deposited (CVD) diamond-coated tool edges, as the fs laser is reported to have less thermal impact and the potential to improve the material crystallinity. We investigated the effects of the laser parameters on the tool edge formation and microstructural changes. The results show that although the infrared fs laser could – compared to the conventional nanosecond (ns)-laser PLG – naturally suppress surface thermal damage, the roughness of the processed surface remained relatively high with an Rz of 0.21 μm. However, under the optimal laser parameters proposed in this paper, an ultraviolet fs-laser PLG was used to obtain a much smoother edge, reducing Rz to approximately 0.08 μm. Moreover, scanning electron microscopy images indicated that the longitudinal machining marks on the ns-laser-processed surface were significantly reduced, with virtually no attached debris on the surface. Furthermore, from the Raman spectra, a significant increase in the diamond peak intensity was observed, indicating that the crystallinity of the CVD diamond (CVDD) was improved following ultraviolet-fs-laser PLG. These results demonstrate that edge shaping and structural modification of polycrystalline CVDDs can be integrated into ultraviolet-fs-laser PLG.

Control of Fine Cutting Chips to Improve the Processing Environment in CFRP Drilling

Carbon fiber reinforced plastic (CFRP) is increasingly used in aerospace, automobile, and other industries. With the improvement of carbon fiber reinforced thermoplastic molding technology using thermoplastic resin, it is expected that the applications of CFRP will be expand further. Because of the following issues, CFRP is known as a difficult-to-cut material. i) Machining CFRP is difficult. ii) Its finished surface deteriorates due to delamination and uncut fiber. iii) It has a shortened tool life due to severe tool wear. In addition to these issues, we has been problem presentation of fine cutting chips generated by machining. Because these fine cutting chips may scatter in the atmosphere and adversely affect the human body and machine tools, we have established a chip disposal technology that suppresses these issues to improve the processing environment. A previous study reported that shape of the tool edge is responsible in suppressing the generation of fine cutting chips. Here, we experimentally investigated the effects of tool edge shapes on the chip collection rate and tool life. An attempt was made to determine whether the same effect can be obtained by using the outside dust-collection method which is known that the dust collection efficiency is low. We revealed that the chip collection rate increases if a tool that suppresses the generation of fine cutting chips is used instead of a conventional tool; furthermore, the tool life is insensitive to coating. In contrast, a comparison of our results with previous findings indicates that the tool with a sharpened cutting edge has a longer tool life than the conventional twist drill with honing. A high cutting chip collection rate was obtained, even with the outside dust-collection method, which led to an improvement in the working environment.

Advanced Modeling of Drilling – Realistic Process Mechanics Leading to Helical Chip Formation

There is considerable interest in the “Industry 4.0 project”. Industry hopes that a general solution of the metal removal problem will be found through the use of highly automated manufacturing data. Scientists hope that the computer will provide better models based on artificial intelligence and machine learning. Initial attempts leveraging existing models did not result in satisfactory results yet — largely because of mathematical, physical and metallurgical reasons. This paper presents a new mathematical-physical model to describe the total process mechanics from volume conservation, to friction, to metal plasticity with self-hardening or softening effects and dynamic phenomena during metal plastic flow. The softening effects are created by high energy corresponding to high strain-rate resulting in high temperatures. Furthermore, the developed equations for strain-rate discontinuities as well as yield shear stress with body forces have an interdependent relationship and lead to plastic deformation with dynamic behavior in the total chip formation zone. This plastic deformation is the only parameter that will not disappear after completing the process. This leads to the opportunity to check the theoretically developed grid deformation and compare it with practical results of the same area. In this publication this new theory will be used to analyze the complex contact and friction conditions between the chip and tool edge of a twist drill during operation. It will be shown that the existing conditions are leading to high wear at the corner edge and flank wear at the tool cutting edge. In addition, the existing temperatures can be estimated and compared with practical measurements, and all these complex and difficult conditions create a helical spiral chip, which could be developed as it will be presented in this paper.

Cutting State Estimation via Chatter Mark on End Milled Surface and Analysis of Its Formation Mechanism Using Voxel Model Simulation

When chatter vibrations occur during cutting, a characteristic pattern called chatter mark appears on the machined surface. In our previous studies, it was estimated that this chatter mark is formed by the tool (or workpiece) vibration in the normal direction with respect to the machined surface. We thus proposed a method to inversely analyze the chatter vibration information during cutting through the chatter mark using two-dimensional discrete Fourier transform. Previous studies confirmed that the analysis results of this method are in good agreement with those of the information obtained via conventional sensing. However, the correctness of the pattern formation mechanism is yet to be directly verified, as it is difficult to measure the cutting phenomenon directly. In this study, the chatter vibration during cutting was measured by the displacement of the tool-shank. Then, based on the results obtained in the static stiffness test, the movement of the tool edge was estimated. A cutting simulation using a voxel model was executed based on this tool-edge movement. When the simulation using the chatter vibration in the normal direction was performed, a chatter mark appeared on the simulated surface. It could thus be confirmed more directly that the analytical model is correct compared with the previous methods.

Influence of tool edge form factor and cutting parameters on milling performance

Tool edge preparation can improve the tool life, as well as cutting performance and machined surface quality, meeting the requirements of high-speed and high-efficiency cutting. In general, prepared tool edges could be divided into symmetric or asymmetric edges. In the present study, the cemented carbide tools were initially edge prepared through drag finishing. The simulation model of the carbide cemented tool milling steel was established through Deform software. Effects of edge form factor, spindle speed, feed per tooth, axial, and radial cutting depth on the cutting force, the tool wear, the cutting temperature, and the surface quality were investigated through the orthogonal cutting simulation. The simulated cutting force results were compared to the results obtained from the orthogonal milling experiment through the dynamometer Kistler, which verified the simulation model correctness. The obtained results provided a basis for edge preparation effect along with high-speed and high effective cutting machining comprehension.

An Analysis of Manufacturing Precision of Involute Worms Using a Kinematical Model

The manufacturing precision of involute worms constitutes a major requirement. On the one hand, the worm constitutes the input element of the worm drive; secondly, the involute helical surface is the basic surface of an involute worm-hob. This paper presents an analytic comparison between the involute surfaces obtained using theoretical equations, kinematic simulation of the cutting and the surface charged with errors. The surface error is considered the distance along the normal direction to the theoretical surface, measured between this and the surface charged with simulated manufacturing errors. The main sources of errors are considered the center-error of the edge plane, the edge profile error and deviation of the axial feed direction from the axis of the worm. The theoretical results allow us to conclude that the influence of the edge profile error is the largest. It is followed by the parallelism error between the feed direction and the axis of the worm, and finally, the center error of the tool edge.