Workpiece damage due to cutting edge corner engagement: immediately before entering (a) and immediately after entering of the cutting edge corner (b)

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... tests have shown that a heavily worn cutting edge corner results in undefined cutting conditions that no longer allow precise cutting of the fibres and thus cause workpiece damage. The proof that the cutting edge corner determines the quality is provided in Fig. 1 by two frames from the image of a high-speed camera (vc = 80 m·min -1 , f = 0.125 mm, α = 14°, γ = 5°, d = 25.4 mm). It is clearly visible that no workpiece delamination occurs before the entry of the cutting edge corner. Due to the process intervention of the cutting edge corner, delamination of the surface layer occurs at the tool ...

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... frequency response in two different sections. These natural frequencies are always harmonic frequencies, i.e. integer multiples of the fundamental frequency, which in this case corresponds to the rotational frequency of the tool ftool. The higher spindle speed of n = 1989 min -1 corresponds to a cutting speed of vc = 200 m·min -1 at d = 32 mm. Fig. 10 shows that, at this spindle speed, the force curve fluctuates based on the fibre orientation during machining. When using the higher tool speed compared to the previous test series, no wave-like profile occurs. In direct comparison to Fig. 7, both higher process forces and a higher torque can be measured. The description of the ...

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... based on the fibre orientation during machining. When using the higher tool speed compared to the previous test series, no wave-like profile occurs. In direct comparison to Fig. 7, both higher process forces and a higher torque can be measured. The description of the roundness error shows clearly recognisable transitions at θ ≈ 0° and θ ≈ 110°. Fig. 11 shows a bore without visible delamination phenomena. Chatter marks or a wave-like surface profile are also not visible on the bore wall. Due to the high cutting speed, it can be assumed that the matrix's glass transition temperature is reached, resulting in a smoother surface. Considering the frequencies presented in Fig. 12, the ...

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... θ ≈ 0° and θ ≈ 110°. Fig. 11 shows a bore without visible delamination phenomena. Chatter marks or a wave-like surface profile are also not visible on the bore wall. Due to the high cutting speed, it can be assumed that the matrix's glass transition temperature is reached, resulting in a smoother surface. Considering the frequencies presented in Fig. 12, the harmonics can always be found in the range 0 Hz < f < 1000 Hz. The frequencies f = 840.4 Hz and f = 906 Hz are significant. The left chart shows the entire amplitude spectrum, whereas the right chart shows a larger resolution in the range between 820 Hz < f < 980 Hz. The cutting edge engagement and the reaching of the final ...

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... engagement and the reaching of the final diameter can be precisely determined using the force curves for the entire process. By examining different spindle speeds, an average feed per tooth can be calculated according to Table 2. It can be seen that for n ≤ 1000 min -1 a constant feed per tooth results by actuating with a feed force of Ff = 20 N. Fig. 13 shows a new cutting edge, which is already highly asymmetrical, and Fig. 14 a cutting edge after 16 drilled bores. By comparing these cutting edges, an even wear can be seen after 16 bores, which results in a smoothing of the cutting edge and a more symmetrical profile. Furthermore, in Fig. 14 an area can be seen on the right side at ...

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... using the force curves for the entire process. By examining different spindle speeds, an average feed per tooth can be calculated according to Table 2. It can be seen that for n ≤ 1000 min -1 a constant feed per tooth results by actuating with a feed force of Ff = 20 N. Fig. 13 shows a new cutting edge, which is already highly asymmetrical, and Fig. 14 a cutting edge after 16 drilled bores. By comparing these cutting edges, an even wear can be seen after 16 bores, which results in a smoothing of the cutting edge and a more symmetrical profile. Furthermore, in Fig. 14 an area can be seen on the right side at the cutting edge corner that was not engaged in the process. This illustrates ...

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... results by actuating with a feed force of Ff = 20 N. Fig. 13 shows a new cutting edge, which is already highly asymmetrical, and Fig. 14 a cutting edge after 16 drilled bores. By comparing these cutting edges, an even wear can be seen after 16 bores, which results in a smoothing of the cutting edge and a more symmetrical profile. Furthermore, in Fig. 14 an area can be seen on the right side at the cutting edge corner that was not engaged in the process. This illustrates the difference between the condition influenced by abrasive wear and the condition of a new cutting edge. Previous investigations have shown that the asymmetrical cutting edge in new condition shown in Fig. 13 has a ...

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... Furthermore, in Fig. 14 an area can be seen on the right side at the cutting edge corner that was not engaged in the process. This illustrates the difference between the condition influenced by abrasive wear and the condition of a new cutting edge. Previous investigations have shown that the asymmetrical cutting edge in new condition shown in Fig. 13 has a positive effect on the cutting process, as the transition to the flank face described in [17] has a very short contact length [8,9]. Due to the actuating movement in radial direction, it can be assumed that the cutting edge profile from Fig. 14, which has changed due to wear, causes a strong enlargement of the mentioned area. ...

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... Previous investigations have shown that the asymmetrical cutting edge in new condition shown in Fig. 13 has a positive effect on the cutting process, as the transition to the flank face described in [17] has a very short contact length [8,9]. Due to the actuating movement in radial direction, it can be assumed that the cutting edge profile from Fig. 14, which has changed due to wear, causes a strong enlargement of the mentioned area. Therefore, it can be assumed that the cutting process does not occur due to a limited actuating force (≙ feed force). This is because the flank face only presses against the bore wall without the cutting edge rounding engaging. This issue could be ...

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... the cutting edge's wedge angle results in a smaller effective angle η while the process parameters remain the same. This would have the consequence that the effective movement changes more in the direction of the cutting movement and thus the separating cutting edge areas engage even with symmetrical cutting edges. This process is illustrated in Fig. 15. Due to the described change in the feed direction, the cutting edge is subjected to a more even and symmetrical load compared to a conventional processes, which means that asymmetrical waterfall wear can be avoided. The possibility of achieving a real self-sharpening effect of the cutting edge with this process is given due to the ...