PSI - Issue 19

Shota Hasunuma et al. / Procedia Structural Integrity 19 (2019) 194–203 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

196

3

Fig. 2 shows the relationship between the surface roughness and cutting speed. The surface roughness was measured using a laser microscope(Optelics Hybrid, Lasettec). The relationship between the residual stress and cutting speed is shown in Fig. 3. The residual stress was measured using a X-ray diffraction method. A comparison of specimens produced with different cut depth at v = 45.2 m/min revealed that the effect of the cut depth on the surface roughness and residual stress was weak. The surface roughness decreased and residual stress increased with increasing the cutting speed. Then, residual stress increased with the cutting speed. More detailed measurement was carried out for No.1 and 4 specimens. Figs. 4 and 5 show surfaces of No.1 and 4 specimens, respectively. Observations were made using a laser microscope. Scratches on the No.1 specimen are larger than those on the No.4 specimen comparing Fig.4 (a) and Fig.5 (a). The number of cracks of No. 1 specimen is larger than that of No.4. Fig. 4(b) and Fig. 5(b)shows close up images of Fig. 4(a) and Fig. 5(a), respectively. Fig. 4(c) and Fig. 5(c) show cross section images of the A- A’ and B - B’ line s in Fig. 4 (b) and Fig. 5 (b), respectively. Scratch on the No.1 specimen is deeper than that on the No.4 specimen.

Table 3 Machining conditions. No.

Spindle speed n [1/min]

Cutting speed v [m/min]

Cut depth a p [mm]

Feed f [mm/rev]

1 2 3 4

360 570

9.04 14.3 45.2 45.2

0.8 0.8 0.5

0.1 0.1 0.1 0.1

1800 1800

1

0.5 mm 0.8 mm 1 mm Cut depth

2

1.5 Surface roughness Ra ,  m

0.5 mm 0.8 mm 1 mm Cut depth

500

0 Residual stress  r , MPa -500 0

Solid : Axial Open : Circumferential

Fig.2 The effect of machining condition on surface roughness. 0 10 20 30 40 50 60 1 Cutting speed v , m/min

10 20 30 40 50 60 Cutting speed v , m/min

Fig.3 The effect of machining condition on residual stress.

150

A

B

(b)(a )

(c)

100

50 Position,  m

(b)

Loading direction

A-A' B-B'

300  m

20  m

A’

B ’

0

−5

0 5

Hight,  m

Fig.4 Observation of scratch of No.1 using laser micrograph(a). (b) is close up image. Sectional configuration of surface on the A-A' and B-B' lines(c).