## 1 Introduction  
Titanium alloys have been widely used in aerospace, energy and military fields due to their excellent specific strength, specific stiffness, heat resistance, corrosion resistance, etc. In order to meet the advanced requirements for processing efficiency and workpiece surface quality in the aforementioned fields, it is particularly important to adopt high-speed precision milling. However, severe tool wear may occur in high-speed milling, which reduces the processing efficiency and affects machining surface integrity [1]. During milling, the temperature of the milling cutter [2, 3], lubrication mode [4, 5, 6] and the anti-friction performance of the tool [7] are the important factors that affect tool wear. In order to meet the specific requirements of green cutting, increasing research attentions have been directed toward the peripheral milling of titanium alloy workpiece with integral carbide end mills, especially on tool temperatures. The main influential factors of temperature field distribution in the cutting process are heat source intensity, geometric characteristics of heat source, processing parameters, constitutive model of workpiece material, tool holder, undeformed chip thickness, the number of cutting edges involved in the cutting process, etc. Many studies have focused on the aforementioned factors. The time-varying load between tool and chip may directly affect the heat intensity in the RCZ. Hence, [PERSON] et al. [8] used a finite difference method with implicit time discretization to solve the partial differential equations for the heat-masstransfer models of tool, and then established a temperature field of milling that has time-varying chip loads. The complex geometric characteristics and asymmetric heat source may directly influence the distribution of cutting temperature field. For this reason, [PERSON] et al. [9] investigated the effect of cutting-edge geometries and cutting-edge radius on cutting heat source and constructed an analytical model of cutting temperature based on the panel method in the field of fluid mechanics. In order to carry out a more specific research on milling temperature, [PERSON] et al. [10] divided the temperature change period of end mills into temperature increase and decrease phases. Considering the real friction state between chip and tool in the temperature increase phase, the heat flux and tool-chip contact length are obtained via finite element simulation, whereas for the temperature decrease phase, a one-dimensional disc heat convection model is applied. Processing parameters are one of the most important factors that affect cutting temperature. Therefore, [PERSON] et al. [11] developed an end-milling temperature rise model based on the response surface method and assessed the influence of milling parameters on this model. They used a genetic algorithm to optimize the processing parameters to obtain a low temperature rise and found that helix angle is the most crucial milling parameter affecting the peak temperature rise. The constitutive model of workpiece material may affect the flow deformation in the first deformation zone. For this reason, [PERSON] et al. [12] established a new constitutive model of workpiece material under the milling conditions of large strain, high strain rate and high temperature, which can improve the accuracy of cutting temperature resulted by finite element simulation when using the double-helix edge end mills to process Ti6 Al4V. The heat conduction during cutting process may be affected by the tool holder, thus [PERSON] et al. [13] calculated the tool-chip interface temperature using an inverse heat conduction method based on tool and tool holder factors. At the end milling process, the time variations of tool chip contact length may directly affect the undeformed chip thickness and tool temperature distribution. To overcome these challenges, [PERSON] et al.