Monte Carlo Simulations in Validation of Measurement Uncertainty of Cutting Force During Machining by Turning (original) (raw)
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IOP Conference Series: Materials Science and Engineering, 2018
In this article an outlook is given of our and other recent approaches of research and representation of the mathematical models of some physical phenomena that occur in the cutting process. The focus is on the mathematical power model reliability which can be evaluated by the uncertainty parameters based on all error contributors and presented along with the model. An algorithm is proposed for the recommended steps during experimental modelling of the cutting process and uncertainty estimation. The significance of certain errors sources from the measurement software, hardware and the cutting process itself is stressed.
Recording of real cutting forces along the milling of complex parts
Mechatronics, 2006
In this paper, a data acquisition system that simultaneously allows the recording of cutting forces and cutting tool position (coordinates X, Y and Z) is presented. Thus, the geometry of the surface being machined and the values of the cutting forces generated during the surface milling can be correlated. In this manner, two usual problems in milling experimentation are solved. First, those derive from the continuous changes in the feed rate value due to the special look ahead functions (being on-line applied by the numerical control in all high-speed milling centres), which affects the correlation between part geometry and forces. Second, those originate by the presence of unexpected stocks coming from previous semi-finishing operations, which changes the value of cutting forces respect to those calculated taking into account the theoretical tool engagement into the part. The objective of this work is the development of a diagnostics tool for allowing the detection of potential milling problems by researchers, making more profitable the performance of machining test on real complex parts. This tool can be used in the optimization of the milling of test-parts, machining real geometries that incorporate problems different from those observed in the linear tests at constant linear feeds (in end-milling conditions). The final goal of the system is the generation of cutting forces maps as a function of the geometry of real workpieces, which is an advance respect the usual forces recording in function of time or tool rotation typical of linear machining tests. In order to do that, the system incorporates a dynamometric plate for the measurement of the three components of the cutting force, as well as an acquisition card connected to the analog output of the position control loops. After machining, the file containing position and force data is postprocessed and chromatic and vector maps are generated. The force analysis utility has been applied to three cases, in order to assess its feasibility in machining research projects. The first example shows a reduction of the number of tests and therefore machining time (even by 18 times) in the validation of a mechanistic cutting force model. Second example is focused on the detection of unexpected tool engagement conditions in complex parts. And the last one addresses to the milling of thin walls, for investigation of static and dynamic milling problems.
2003
The ability to monitor the behaviour of machine tools and cutting processes is important both from a research perspective as well as in industrial applications such as adaptive control, condition monitoring, process optimization and quality control. The division of Manufacturing Engineering at Lulei University of Technology has been carrying out research in the area of hgh speed and multi axis (5-axis) machming since the mid 1990s. Ths European and nationally funded research, much of it carried out with Nottingham University and Sandvlk Coromant, as well as in manufacturing companies in Sweden and the UK, has focused on understanding the possibilities offered by 5-axishgh-speed machining, as well as understanding the machining process. This initially empirical work has become more qualitative through the development of an instrumented machine tool test bed based on a 5-axis Leichti Turbomill equipped with a 24,000 rpm spindle and fast controller. The machine installation costs appro...
Operational Method for Identification of Specific Cutting Force During Milling
MM Science Journal
Specific cutting force is a key parameter that is important for estimating cutting forces that occur during machining. This information is important for various applications. The most important application is estimation of the stability limit valid for the specific configuration of the machine tool, tool and workpiece. There are a number of procedures used to predict the specific cutting force through various preliminary tests. This paper focuses on an operational method during milling that allows estimation of the specific cutting force using direct information from the machine tool control system. The specific cutting force is calculated as the ratio between the material removal rate and the power measured on the spindle. The method enables easy in-process identification of the specific cutting force that is valid for the specific workpiece material and the specific cutting edge geometry. The method is demonstrated on practical examples.
A Sensor-Integrated Tool for Cutting Force Monitoring
CIRP Annals - Manufacturing Technology, 1997
This paper describes the development of a new concept of cutting tools using strain gages for the measurement of forces in turning operations. The basic idea is the integration of the sensor within the tool shank, in order to obtain a system which is easy to use, easy to install and capable of transmitting data to the CNC through wireless equipment. In particular, the output signal of the measurement bridge is amplified and sent to an external data acquisition system by infra-red transmission. The present paper reports the design principles and the results of some machining tests illustrating the behaviour of the tool in different cutting conditions.
Real-time determination of cutting force coefficients without cutting geometry restriction
International Journal of Machine Tools & Manufacture, 2011
The determination of the cutting force coefficients is a critical point in the case of using the mechanistic cutting force model for predicting the forces during milling processes. The main reason is that the computations require a series of experiments with special geometrical conditions, and the validity of the results is limited. In this paper a cutting force predicting method, based on the mechanistic cutting force model will be introduced, together with an algorithm for determining the cutting force coefficients in the course of a single experiment without restrictions in regard to the cutting geometry. Besides the fact that the proposed method lifts the geometrical restrictions of the previously published solutions, it makes it possible to calculate the coefficients just when they are needed for force prediction right at the machining process, to avoid the problem of the limited validity of the coefficients. In this case the real-time measuring of the cutting forces is needed, while the forthcoming forces can be predicted with an appropriate look-forward algorithm, which is also presented.
Processing noisy cutting force data for reliable calibration of a ball-end milling force model
Measurement, 2005
Machine tool vibrations are common in machining and often result in noisy cutting force measurement. These noisy measurement data compromise the calibration accuracy of empirical cutting force models if they are directly used to determine the empirical model parameters. In this paper, reliable calibration of a ball-end milling force model from noisy cutting force data is addressed. The pertinent section of a noisy cutting force signal measured from a model calibration test cut is first fitted to a polynomial function to reduce signal fluctuation. The empirical parameters of the cutting force model are then solved using an iterative two-stage numerical procedure. Two solution methods with distinct characteristics have been developed and implemented in the present work: the forward and the backward solution method. The former method is a direct solution method and applicable to cutting force data with relatively low levels of noise. The latter method, although an approximate solution method, is more tolerant to the increased noise magnitude in the force data. The applicability of these two solution methods for reliably determining valid empirical parameters of the ball-end milling force model from noisy cutting force data was demonstrated and evaluated.
New method to characterize a machining system: application in turning
International Journal of Material Forming, 2009
Many studies simulates the machining process by using a single degree of freedom spring-mass system to model the tool stiffness, or the workpiece stiffness, or the unit tool-workpiece stiffness in modelings 2D. Others impose the tool action, or use more or less complex modelings of the efforts applied by the tool taking account the tool geometry. Thus, all these models remain two-dimensional or sometimes partially three-dimensional. This paper aims at developing an experimental method allowing to determine accurately the real three-dimensional behaviour of a machining system (machine tool, cutting tool, tool-holder and associated system of force metrology six-component dynamometer). In the work-space model of machining, a new experimental procedure is implemented to determine the machining system elastic behaviour. An
Procedia Engineering, 2015
The development activities in machining are targeted towards improvement of the quality of the end product as well as the appearance and surface finish for geometric and work accuracy. The present work proposes a step-by-step integrated metrology scheme for evaluation of the machine tool structure before, during and after machining that affect the cutting processes. The techniques of high precision measurement are considered as realistic evaluation of the system process accuracy in compliant with the international standards of the geometrical product specification and quality. Hence, both contact and optical measurement techniques are proposed as an application for the machining industry to assess precision and quality.