Optimization of milling parameters considering high efficiency and low carbon based on gravity search algorithm

According to the characteristics of NC milling, an approach for optimization of milling parameters considering high efficiency and low carbon based on gravity search algorithm is proposed. Taking the carbon emission and processing time as the objectives, the cutting rate, feed per tooth, and cutting width as the optimization variables. A multi-objective optimization model of NC milling parameters is established. An non-dominated sorting gravity search algorithm (NSGSA) is used to solve the multi-objective model, and the position update backoff operation is introduced. Finally, taking NC machining process as an example, the multi-objective optimization results and the single objective optimization results are compared respectively, the actual data show that when the optimization objective is high efficiency and low carbon, the processing time and carbon emissions are 173 and 192 respectively. The comparison results show that the combination of processing parameters obtained by multi-objective optimization is the best, the optimal parameter combination obtained by NSGSA algorithm is verified by grey correlation analysis, and the grey correlation degree of the optimal solution set is 0.81, which is the largest in all solution sets. This approach can help the decision-makers flexibly select the corresponding milling parameters, and provide decision-makers with flexible selection decisions suitable for various scenarios.

Embedded Sensor System for Five-degree-of-freedom Error Detection on Machine Tools

Any linear stage of machine tool has inherent six-degree-of-freedom (6-DOF) geometric errors. Its motion control system, however, has only the position feedback. Moreover, the feedback point is not the commanded cutting point. This is the main reason why the positioning error along each axis and the volumetric error in the working space are inevitable. This paper presents a compact 5-DOF sensor system that can be embedded in each axis of motion as additional feedback sensors of the machine tool for the detection of three angular errors and two straightness errors. Using the derived volumetric error model, the feedback point can be transferred to the cutting point. The design principle of the developed 5-DOF sensor system is described. An in-depth study of systematic error compensation due to crosstalk of straightness error and angular error is analyzed. A prototype has been built into a three-axis NC milling machine. The results of a series of the comparison experiments demonstrate the feasibility of the developed sensor system.

SPIF process of axisymmetric parts made of AA1060-H14 aluminum alloy tested on 2 axis-NC lathe machine

This paper deals with an experimental and numerical study focused on the SPIF process of a dome part manufactured by means of a 2-axis NC lathe machine. The main objective is to enhance the understanding of a set of parameters in connection with ISF operations applied to this type of machine unusually used in incremental forming processes, despite the high degree of development of NC lathe machines. Nowadays 4 and 5 axis lathe centers are widely used in industrial applications. This makes NC lathe machines useful in SPIF process especially in the case of axisymmetric parts. The present results, covering thinning, appearance of cracks, surface quality and FLD diagram; prove the efficiency of NC turning machines to perform SPIF application of parts commonly manufactured by a 3-axis NC milling machine.

DEVELOPMENT OF A HIGH-SPEED MIRROR-LIKE FINISH POLISHING TECHNOLOGY FOR MINUTE PARTS BASED ON A LINEAR MOTOR

As high speed, high acceleration and stable drive on machine tools is constantly growing in demand, the use of linear motors in machine tools has increased. On the other hand, in order to achieve a high degree of quality, the need for mirror-like finish surfaces on industrial products has also considerably increased. This research explores the use of linear motors to develop a high-speed fine polishing process that achieves a mirror-like finish surface on small parts. The first stage of this process consisted in developing a polishing device, which was composed of a NC milling machine, a linear motor drive and a polishing head. Specifically, a polishing head attached to a linear motor drive was coupled with the spindle of a NC milling machine. A substitute for a small linear motor drive was obtained from a commercially available shaver, while the polishing head was made of propylene. The polishing head elaboration process, linear motor drive properties, lapping agent and the optimum polishing conditions were investigated in several experiments. The evaluation consisted in the high-speed polishing of minute areas on flat surfaces using the selected optimum conditions. It is concluded that, (1) the proposed system was able to achieve a mirror-like finish surface, (2) when compared to polishing with an ultrasonic motor, the machining time of the proposed system was reduced by half, (3) the proposed system was able to achieve a mirror-like finish on a 3 mm square sided area.

MACHINE TOOL DISTORTION ESTIMATION DUE TO ENVIRONMENTAL THERMAL FLUCTUATIONS ― A FOCUS ON HEAT TRANSFER COEFFICIENT

Thermally induced errors have been approached in multiple ways due to the influence these have over the positional accuracy of a machine tool. Here, approaches regarding environmental thermal fluctuations surrounding a machine tool remain to be explored in detail. These fluctuations have been explored in terms of the heat transfer coefficient and thermal radiation of the machine shop walls, as well as in terms of seasonality and varying thermal gradients. This paper presents additional considerations regarding environmental temperature perturbations, as heat transfer coefficient fluctuations in the machine shop were thought to play a significant role in machine tool thermal deformation a broader term for these phenomena, environmental thermal fluctuations, was defined and evaluated. Specifically, an environmental thermal data survey of a machine shop was explored. This data was then applied to a NC milling machine and a CNC jig borer FEM analyses and compared to experimental data. FEM simulations were then used to demonstrate that convection regimes and heat transfer coefficient values at a machine shop have a significant influence over machining precision. Here, under maximum and minimum heat transfer coefficient values, the NC milling machine and CNC jig borer simulations results showed an error of cut difference up to 36.5 μm and 18.17 μm, respectively. In addition, as the importance of the heat transfer coefficient was highlighted, considerations regarding machine tool surface color were deemed relevant and were described.

Complex surface finishing control on NC milling machines

On the basis of the analysis of cutting forces operating in the contact area of a ball mill with the surface under machining there are offered dependences for the technological parameters definition. The use of the dependences obtained allows increasing productivity of volumetric milling areas left unprocessed after semifinish milling without use of additional adaptive devices