Effect of Changing Belt Tension on Machining Surface of CNC Lathe Spindle

Abstract

Computer numerical control (CNC) lathes are optimized for machining workpieces into rotating shafts or cylindrical shapes of structures. However, because rotating mechanical parts are used on CNC lathes, vibration from spindles, servomotors, hydraulic pumps, and feed screws occurs. Therefore, periodic preventive maintenance is required to minimize vibrations. Additionally, alignment, balance, and adjustment operations are necessary for parts that perform linear or rotational movements. Thus, this study adjusts the tension of the V-belt that drives the spindle of the CNC lathe, analyzes the primary components and the vibrations occurring at the spindle and servomotor, and measures the surface roughness to identify the cutting quality according to the impact of the belt tension. The experimental results show that the peak value of the vibrating component increases as the cutting speed increases. We demonstrate that the optimal vibration characteristics and excellent surface roughness values are achieved at a relatively looser belt tension than the standard value. In particular, at a feed speed of 0.05 mm/rev, a cutting speed of 250 m/min, and a depth of cut of 0.8, the surface roughness in loose tension was reduced by up to 143.9% compared to tight tension. Additionally, the optimum processing quality is achieved at a cutting depth of 0.6 and 0.8 mm, corresponding to a turning insert nose R-value of 0.4 mm, and at cutting speeds ranging from 200 to 250 m/min.

Influence of the Material Mechanical Properties on Cutting Surface Quality during Turning

“…The turning insert for finishing was replaced after the machining of one workpiece to minimize tool wear. Figure 1a-c show the experimental process of material preparation for cutting and surface roughness measurement, while Table 2 lists the specifications of the DOOSAN LYNX220 CNC lathe used in the experiment [13]. The tool holder used in the experiment was SVJBR 2525 M16, and VBMT 160404 VF was used as the turning insert [24].…”

“…The parameters used in cutting studies are essentially the cutting conditions [11,12]. The reason for this is that the characteristics of chip discharge change depending on the cutting conditions, and the chip discharge characteristics have a significant effect on cutting resistance and surface roughness during machining [13,14].…”