Chatter Suppression in Boring Process Using Passive Damper
During machining process, chatter is an unavoidable phenomenon. Boring bars possess the cantilever shape and due to this, it is subjected to chatter. The adverse effect of chatter includes the increase in temperature which will leads to excess tool wear. To overcome these problems, in this investigation, Cartridge brass (Cu – 70% and Zn – 30%) is passively fixed on the boring bar and also clearance is provided in order to reduce the displacement, tool wear and cutting temperature. A conventional all geared lathe is attached with vibrometer and pyrometer is used to measure the displacement and temperature. The influence of input parameters such as cutting speed, depth of cut and clearance on temperature, tool wear and displacement are investigated for various cutting conditions. From the result, the optimum conditions to obtain better damping in boring process for chatter reduction is identified. Keywords—Boring, chatter, mass damping, passive damping.
Experimental Investigation of Chatter in Boring Operation Using Shim
In boring process, casted, forged, or extruded holes in components are finished with a boring bar having cutting insert at its frontend. Dynamic and static deflections are always there in the boring bar due to its slenderness. The generating force for chatter is supplied by the cutting process itself, so it creates problems in achieving desired productivity. The main goal of this research work is to amend the rendition of boring tool with the help of shim having good damping capacity, which is placed under the tool insert. Here, brass shim is used and experiments are performed with and without shim one by one on CNC machine. Whole experimental data of acceleration is collected using CoCo80 dynamic signal analyzer. Using this data, various plots like time response plot, frequency response plot, Poincare plot, orbit plot are obtained to check for motion behavior. Surface roughness is also measured using surface roughness tester. The proposed concept shows effective chatter suppression strategy in boring operation.
On the Development of a Simple and Robust Active Control System for Boring Bar Vibration in Industry
Vibration in internal turning is a problem in the manufacturing industry. A digital adaptive controller for the active control of boring bar vibration may not be a suficient solution to the problem. The inherent delay in a digital adaptive controller delays control authority and may result in tool failure when the load applied by the workpiece on the tool changes abruptly, e.g. in the engagement phase of the cutting edge. A robust analog controller, based on a lead-lag compensator, with simple adjustable gain and phase, suitable for the industry application, has been developed. Also, the basic principle of an active boring bar with embedded actuator is addressed. The performance and robustness of the developed controller has been investigated and compared with an adaptive digital controller based on the feedback filtered-x algorithm. In addition, this paper takes into account those variations in boring bar dynamics which are likely to occur in industry; for example, when the boring bars is clamped in a lathe. Both the analog and the digital controller manage to reduce the boring bar vibration level by up to approximately 50 dB.