A study on the milling temperature and tool wear of difficult-to-machine 508III steel

Abstract

Difficult-to-machine 508III steel is widely applied in the water-chamber heads of steam generators for nuclear power stations of AP1000 nuclear islands. The dominant machining process for these components is heavy-duty cutting. Since 508III endures significant mechanical impacts and alternating thermal loads during milling, the cutting temperature is relatively high. High temperatures reduce the surface quality of the workpieces and accelerate insert wear, which shortens the insert service life and reduces cutting efficiency. In this article, the welding set and amplifying circuit of thermocouples were designed. Coated cemented carbide inserts were adopted. The wired half-artificial thermocouple method was utilized to conduct 508III steel milling temperature tests. The influence regularity of cutting parameters on the milling temperature was analyzed, and the regression model of the milling temperature was constructed, which provided boundary conditions for insert simulation analysis. Second, finite element simulations of the milling process and milling inserts were carried out to analyze the temperature variation regularity and insert temperature distribution during milling. The simulation results were compared with the experimental results for validation. Finally, the wear behavior of the 508III milling insert was characterized by analyzing the wear condition of both the rake surface and flank surface of the milling insert, as well as the wear amount of the flank surface. The interactive influence regularity between the insert wear and milling temperature was explored. The milling temperature distribution and insert wear state obtained from the simulation agreed with the experimental results. The availability and reliability of the designed milling temperature test system were validated, which provides theoretical foundations and technical support for developing inserts and improving the cutting efficiency of difficult-to-machine materials.

Upgraded closed-form cutting force models for general-helix cylindrical milling tools with application to cutting power and energy demand modeling

“…This means that the time-dependent true integration intervals Dz p (t) = z p, 2 (t) À z p, 1 (t) will differ for different segments. On mirrowing the analytical procedure in Ozoegwu and Eberhard 44 in evaluating the integrals in equations ( 3)-( 5), the arising upgraded closed-form cutting force models which no longer require the screening functions g p (t) retain most of the symbolic representations in equations ( 1)-( 10) except for modifications of the trigonometric functions C 1p (t), S 1p (t), C 2p (t), and S 2p (t) to C 1p (t) = cos u (2) p (t) À cos u (1) p (t), S 1p (t) = sin u (2) p (t) À sin u (1) p (t), C 2p (t) = cos (2u (2) p (t)) À cos (2u (1) p (t)),…”

“…with the limit angles u (1) p (t) and u (2) p (t) for the engaged segments (i.e. either mod(u p (t), 2p) or mod(u pÀ1 (t), 2p) is (or both are) in ½u s , u e ) given as…”

Core temperature measurement using ultrasound for high precision manufacturing processes

“…The dimensional accuracy and surface integrity of manufactured workpieces are directly affected by temperature variations during manufacturing and these two specifications are indicators of the conformance of the manufactured workpieces to the design intent. 1–4 Therefore, there is a need to have a system in place for temperature control and/or to compensate for the effect of temperature variation.…”

Analytical modeling of tool failure boundary map in milling titanium alloy

“…Titanium alloy Ti6Al4V, as a typical difficult-to-machine material in aerospace, has poor thermal conductivity, low plasticity, high chemical activity, and small elastic modulus, which leads to small cutting deformation, high cutting temperature, large cutting force per unit area, and serious tool adhesion during cutting process, resulting in serious tool wear and poor surface quality, 1,2 affecting the development of titanium alloy cutting field. The tool failure boundary map provides a safe operating area for cutting tools by adding different types of failure boundaries, so as to ensure that the combination of cutting parameters in the safe area does not fail before the scheduled replacement time of the tool.…”