This paper describes the mechanism of long pitch helix type chip formation of twist drill drillable deep hole under continuous high feed rate. The long pitch helix type chip forms after the segment ...type chip formation. In drilling S 50 C, when the top of chip catches the flute surface after the contact with the drilled hole, the cutting ratio becomes small. If the frictional force is kept in same level, the long pitch helix type chip formes. However, the crack occurred at the second main cutting edge progresss under insufficient plasticity of chip and then the segment type chip formes. However, the crack did not progress and then the long pitch helix type chip formes when the cutting temperature at the point 1.0 mm rear from the first main cutting edge on the flute becomes apprmoximately 400°C. In order to form the long pitch helix type chip in early stage, the following conditions can be considered : (i) Enlargement of frictional force between chip and the flute (Prevention of crack progress). (ii) Change of cutting ratio under no constraint by the drilled hole and the flute (Reduction of cutting ratio change by them). In order to realize these conditions, the drill with chamfered margin and the drills with zero-degree rake angle were tested. These drills showed the effective results.
This paper describes the mechanisms of chip formation, chip removal from cutting edge and chip exhaust out of drilling hole of the twist drill drillable deep hole under continuously high feed rate. ...The web of this drill is three times thicker than that of the conventional one. Then the flute is nallow. The chip is a conical helix type at first, succesively changes to segment type, and then to a long pitch helix type. The segment type chip lines up in the flute and the long pitch helix type chip is along the flute. So, the segment type chip and the long pitch helix type chip are exhausted out of the drilling hole very well. While the depth of hole is still shallow at the beginning of deep hole drilling, the conical helix type chip is scarcely constrained by the flute. The hole becomes deeper, the chip requires larger area to grow and are constrained by the flute. Then, both moment and frictional force are applied on the chip by the flute and the drilling hole, and the cutting ratio changes. When the workmaterial has enogh plasticity, the chip changes to the long pitch helix type chip due to large oblique angle of the first main cutting edge. When its plasticity is poor, the chip becomes the segment type chip. The segment type chip is same as the head of the long pitch helix type chip.
Application of an adaptive information processing system to chip form classification on the basis of acoustic emission (AE) signals is described. The system is composed of an AE sensor, a spectrum ...analyzer and an adaptive empirical modeler which automatically determines the relations between features of AE power spectrum and the chip form.
Turning machinability tests were performed on the magnesium alloy castings MC2 by measuring the cutting resistance, the cutting ratio, the shear angle, the surface roughness and the chip formation. ...Regardless of the side rake angle, both the tangential and the traversing force of the alloy were independent of the cutting speed, and were affected remarkably by increasing the feed. The tangential force decreased with increasing the side rake angle. The traversing force showed a negative value with acceleration of the feed using the side rake angle of 30°bit. Both the cutting ratio and the shear angle increased with acceleration of the cutting speed and the feed, and 0.54 to 0.82 as the cutting ratio and 30.2°to 44.6°as the shear angle. The machined surface finishing showed smoother with increasing the cutting speed and decreasing the feed, and was superior or nearly to that calculated theoretically. Both the large and small spiral coil type chips were easily treatable. There was no trouble in the flaming during cutting. The MC2 alloy had excellent machinability in the high speed heavy cutting.
Lathe turning may produce long, continuous chips, or short, broken chips. Broken chips carry away heat and may reduce tool temperature. Continuous chips may snarl and interfere with machine ...operation. Inside diameter turning or thread cutting may be unusually susceptible to snarls from continuous chips. Other researchers have constructed acoustic emission (AE) chip form monitors. A mathematical model and its advanced continuous simulation language (ACSL) embodiment are described. A simulation study suggests that straight forward modifications hold promise of in-process chip length sensors that
can be used for feedback control.
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