Fig.2 Forming process of boundary notch of the cemented carbide cutting tools.
3 EXPERIMENT CONDITIONS AND TESTING MEASURES
The lathe C6130 and reversible cutting tool are used in the experiment. Five cutter materials are employed. Main mechanical parameters of cutter material are shown in Table 1.
The machining piece is the friction-welded line of the single hydraulic pillar. The width of the welded line is 15mm and the machining allowance is 5.5mm. Besides, the above pillar is welded with 270SiMn and 45# steel. The relatively mechanical performances of the welded line are shown in Table 2.
Based on manufacturing experience and relative information in China and other countries about similar machining process, the chosen machining and tool geometry parameters are shown in Table 3.
The boundary notch dimensions of the cemented carbide cutting tools (boundary notch height VN and width C are directly attained by tool microscope. In order to ensure reliability of the results, repeated experiments are carried out. The recurrent performance is good.
4 EXPERIMENT RESULTS AND ANALYSIS
4.1 Cutter Materials
For different cutter materials, as shown in Fig. 3, the machining performance and the ability to resist boundary notch are distinctly different.
From Fig. 3, we can find the boundary notch dimensions are relatively large when YD10,YD15 and YW are used. Whereas the boundary notch dimension is smallest when YTS25 is used. Because of the asymmetry allowances impacts and vibrations will take place. YTS25 cutter has better impact-resisting performance and boundary notch dimension. Therefore, YTS25 cutter material is selected to do the following experiments.
Table 1 Material Performances of Cutters
Type Material Performance Remark
HRA σb(kg/mm2) Γ(g/cm2)
YD10
YD15
707
YW2
YTS25 ≥92
≥90.5
≥92
≥91
≥91 ≥130
≥125
≥145
≥150
≥200 12.4~112.8
11.5~12.1
11.8~12.5
12.7~1.3.3
12.8~13.2 North tools
North tools
ZiGong
Zhugong
Zhuzhou
Table 2 Mechanical Performances of Cutters
Item Tensile strength Elongation rate Shrinkage rate Impact toughness
σb
(kg/mm2) δ
(%) T
(%) Αk
(kg/cm2)
270SiMn 100 12 40 5
45# 61 16 40 5
Welding Line 64.6~82 5.5~ 13 37.6~46.2 3.5~6.4
Table 3 Cutting Parameters
Cutting velocity V (m/min) 75
Cutting depth αp (mm) 5.5
Feed rate f(mm/r) 0.3
Rake angle 原文请找腾讯752018766 γ0 (□ 10
Clearance angle α0 (□ 8
Cutting edge angle Kr (□ 845 ; 75 ; 90
Edge inclination λs (□ -5
Negative chamfer bα1 (mm) 0.1; 0.2; 0.3
Cutter corner radius rε(mm) 0.2; 0.4; 0.8
4.2 Influences of Cutting Edge Angle
The results of the variet毕业论文
http://www.751com.cn y boundary notch are shown as in Fig. 4 when the cutting edge angle is changed. From Fig. 4 we can find that, with the lessening of the cutting edge angle Kr , the dimensions of the boundary notch decrease. The reason is that with the lessening of the cutting edge angle Kr , the length of the cutting edge that acts on cutting becomes larger and the average loads on the cutting edge become lighter.
4.3 Influences of Cutter Corner Radius rε
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