Paper presents some aspects of modeling and simulation of machining focusing on the burr formation in the last phase of the chip creation in the aluminum and titanium alloys. Researches concern the temperature and strain fields distributions in the cutting zone. Finite element method was applied in the numerical calculations basing on the Lagrange’ equation.
The paper describes research concerning the analysis of the chip flow phenomenon during turning process of difficult-tocut materials. In the study a series of tests of roughing turning were carried out. A process of chip formation in the cutting zone was recorded using the high-speed camera Phantom 5.2. The direction and speed of the chips flow were estimated in the computer program for analysis of the point movement e.g. speed and acceleration.
An analysis of the part deformation in the face turning of the grooves was presented. A face-grooving process was performed on the disc-shaped part made of titanium alloy Ti6Al4V. Investigations were performed in two stages. First, experimental studies were conducted to determine the level of the cutting forces for variable wall thickness and cutting data. In the second step of investigations, a computer simulation of the disc flange deformation was performed using finite element method in the NX Siemens software. Based on the analysis of the research results, the dependence of the direction and value of the cutting force on the deformation value has been determined.
The paper describes research concerning the method of the chips forming for the face turning of stainless steel. In the study a series of tests of finishing and roughing turning were carried out. A process of chip formation in the cutting zone was recorded using the high speed camera Phantom 5.2. The direction and speed of the chips flow were estimated in the computer program for analysis of the point movement. An effort was made to determine the approximate trajectory of the chip flow in the XYZ system.
Paper presents some tool life investigations, concerning modeling and simulation of tool wear when turning a difficult-to-cut material like nickel based sintered powder workpiece. A cutting tool made of CBN has its special geometry. The workpiece in the form of disc is an aircraft engine part. The aim of researches is to optimize the cutting data for the purpose to decrease the tool wear and improve the machined surface roughness.
Paper presents researches of cutting force measurements and computer simulation of physical phenomena existing in the cutting zone. Stress distributions in the upper layer after machining were calculated with the numerical software, basing on the FEM method. Optimization of turning process was realized for the purpose to minimize the cutting force and stress values during stainless steel machining, belonging to the difficult-to-cut materials group.
Tool deflection strongly influences on the workpiece quality. Author of the paper built a simulation model of the down milling process of titanium alloy (Ti6Al4V) with a tool made of sintered carbides. Material model consists of strain, strain rate and thermal sensitivity formulations to predict the stress field distribution in the cutting zone. Numerical calculations were experimentally verified on the milling center, equipped with measuring devices: force dynamometer, thermo-vision and high-speed video cameras.
This paper describes the research results of surface quality research after the sintered carbides turning by the tools with
edges made of polycrystalline diamonds (PCD). The research trials were conducted for tools with different nose radii
and the influence of three independent parameters (<i>v</i><sub>c</sub>, <i>f</i>, <i>r</i><sub>epsilon</sub>) affecting the surface roughness were analyzed. The impact of
the binder material content Co (cobalt) on the surface quality during the turning process (according to the values of
surface roughness parameter Ra) is described further on. The values of <i>v</i><sub>c</sub>, <i>f</i>, <i>r</i><sub>epsilon</sub> at which the smallest surface
roughness (for the particular work piece materials) could be achieved were defined. Based on the ANOVA variance
analysis it was possible to find different effects of the research factors on the surface roughness (for the two types of
sintered carbides shafts). For the shaft with 25% Co content, the significant influence is for two parameters: the cutting
speed <i>v</i><sub>c</sub> and the nose radius <i>r</i><sub>epsilon</sub>. For the shaft with 15% Co percentage content, the significant influence is only for the
nose radius <i>r</i><sub>epsilon</sub>.
This paper introduces an example of automated intelligent system for super hard materials turning process that works
according to a designed algorithm. Main task of the proposed system is to supervise the super hard materials turning
process (acronym: ISSSHMT - Intelligent Supervision System of Super Hard Materials Turning) with the maximal metal
removal rate Q<sub>vmax</sub>, the amplitude of natural tool wear and the measurement of values that define the state of the turning
process (e.g. magnitude of cutting force, surface quality, temperature in workspace). Based on the measured values it is
possible to select the optimal machining parameters (<i>v</i><sub>c</sub>, <i>a</i><sub>p</sub>, <i>f</i>), for which desired surface quality and dimensional
precision can be achieved for the maximal metal removal rate Qvmax. Presented system (ISSSHMT) can be used for any
CNC machine – accommodation for workspace and construction of the machine. An example of NC-code program that
allows using the data acquired from the ISSSHMT system by a CNC machine control unit is presented. Optimization of
the process and cost cutting can be achieved with the usage of proper target functions, for products machined with
required precision class.
The results of laser cutting speed influence on the quality of machined surface, defined by the Ra roughness parameter
and the shape errors, in case of machining two types of steel: i) P265GH, ii) 1.4307 are presented in the paper. Two CO2
laser cutters with maximum power of the laser beam 4000W and 3200W were used for the investigation. The
characteristics of the roughness parameter Ra depending on the laser cutting speed <i>v</i><sub>c</sub> are presented. The diagrams of
shape deviation of the machined specimens for the greatest and lowest values of the Ra for the both laser cutters are also
presented. The deviation values from the theoretical profile of the particular samples, taking into account the type of the
cut-out shape profiles (circular, linear) are calculated.