Michal Holub

Geometric accuracy of CNC machine tools

The present article is dedicated to the identification and interpretation of geometric errors of CNC machine tools. Identification of geometric errors plays a large role in the construction of the so-called “Error maps”. These maps can be used to describe the behaviour of the machine in the workspace without load or under conditions of finishing operations. Interpreting the error maps represents a tool to check the state of the machine for the user and to offer the important information for the machine manufacturer. From this information it is possible to identify “weak” points of the machine. Simultaneously, the information on the geometrical errors is used to compensate for machine tools. When constructing the maps, a selection of the measuring device and ambient conditions plays an important role. The paper focuses on the use of measuring equipment LaserTRACER and construction of the error map for the workspace of horizontal three-axis milling machine. It also describes the options of how to monitor the workspace of the machine and their mutual evaluation.

Prediction of Machining Accuracy for Vertical Lathes

This article proposes the methodology allowing a prediction of geometric and working accuracy of large CNC machines tools (MT). The presented approach to behavior predicting is applied to kinematics of vertical lathe with an emphasis on different machining conditions. The resultant deflections of a tool and workpiece (WP) are described within the entire workspace of the machine tool with a simulation of different working conditions, whereby it is possible to effectively use the workspace in terms of working accuracy (WA). The results of the presented methodology can be used for selection of the appropriate type of machine tool and machining technology as early as in the tendering stage. This reduces the time required to select and submit a machine tool quotation. The proposed methodology for predicting the geometry and WA has been verified on a vertical lathe (VL) produced by the company TOSHULIN a.s.

Delta Robot Design

The article proposes an approach to the development of a Delta robot which is the most frequently used robot with a parallel kinematic structure for industrial fast pick and place applications. The approach is model based and it summarizes important steps for the successful design of a Delta robot for the given application including description of the kinematics, multi-body dynamics modelling and flexible bodies notes. This is demonstrated on the particular Delta robot developed at Brno University of Technology (BUT).

Device for Measuring of Active Power and Energy at Machine Tools

This article describes developing of device for measuring active power and energy at machine tools. Demands on measuring of electric energy flow in machine tools are more often with requirement to increasing of efficiency. This problematic is very complicated, because there are some types of electric power supply. Machine tools have main supply with harmonic supply with disturbance, direct current supply with high-frequency disturbance and power supply with PWM modulation. This device primary serves for measuring of AC power between inverter and motor, but also is able measure at other places. Developing consist from developing of electronics and algorithm. Both these part are describes in article.

Monitoring of Energy Flows in the Production Machines

The article deals with the development of software tools supporting visualization in order to assess the workload of electrical appliances installed in machine-tools. This enables us a considerably easier orientation and the control of energy consumption. The first part of the article is concerned with the application created for simulation of energy flows in the machine-tool with the help of advanced post-processing. That allows software to select to review only interesting data using peaks identifying algorithm. The second part deals with Sankey diagrams visualizations improvements. The tool developed for visualization was applied to the machine FUEQ 125 Efektiv company TOS Kuřim in cooperation with the Czech Technical University in Prague, Faculty of Mechanical Engineering, VCSVTT - Research Centre for Manufacturing Engineering and Technology.

DELTA - Robot with Parallel Kinematics

A complex solution of a design of the DELTA type robot, i.e. the robot with parallel kinematics, is described in this paper. The project ensued from cooperation with the company Dyger, s.r.o., with the objective to develop a robotic device suitable for high-speed handling of small objects and applicable in many industrial configurations. The task was not only to design the mechanical part of the robot that would work together with the provided hardware and software, but also to develop our own algorithms for calculations of the target positions, singular positions of the mechanism etc.

DUAL NUMBERS ARITHMETIC IN MULTI AXIS MACHINE ERROR MODELING

and thus more convenient setting can be used. As algebraically the properties of , , xx yx zx ň ň ň coincide we can consider these as the coefficient of one element only and thus we can work in the dual numbers algebra, see [Hrdina 2014]. Note that this simplification brings minor complications, particularly the number of remaining terms increases, but, on the other hand, the question of the geometric interpretation of these higher order error terms is also interesting. For instance, one can distinguish the rotation error w.r.t. the x and y axis while translating along the axis x . Let us recall the definition of the dual numbers. It is a set { | , } a b a b     D (3) endowed with the operations summation and multiplication

GEOMETRIC ERRORS COMPENSATION OF CNC MACHINE TOOL

This contribution assesses the possibilities of application of conventional compensation technology on a small three-axis vertical machining centre. Small CNC machine tools are intended for manufacture of small workpieces with dimensional accuracy of up to 0.001 mm. To achieve the required accuracy and reproducibility of manufacture, a variety of software compensations are deployed on machines. The aim of these compensations is to eliminate errors caused by deviations in the machine geometry, thermal expansion and dynamic compliance of the machine tool. In order to increase dimensional and geometric accuracy of workpieces, this study tested and evaluated methods to activate geometrical compensations such as approach to the desired position and volumetric compensations. Calibration and verification of set compensations were validated by testing geometric accuracy of machines using the devices Ballbar, Laser interferometer and LaserTRACER. Conclusions drawn from the performed study verified deployment of compensations on small CNC machine tools.

Model Based Design of Fuel Pump Control

This paper presents a co-simulation method to design of speed controller for turbojet fuel pump. Expected fuel pump is used for small turbine engine concept with reducer driven by free turbine. The amount of injected fuel into the combustion chamber is based on the speed of the fuel pump which is controlled by the engine control unit. The final flow of fuel into the combustion chamber is restricted by fuel bypass which constricts the return fuel according to pressure in the nozzles. This back fuel bypass has nonlinear and fixed characteristic determined by its structure. The only way how to control the amount of incoming fuel to the engine is the pump speed control. Effect of the bypass represents a variable component in the fuel pump load and from the view of the speed controller it is a disturbance variable. This paper describes the co-simulation model based on the use of MATLAB/Simulink and MSC Adams environment. This simulation uses interconnection of Simulink controller design and simplified model of the fuel pump dynamics in Adams (without hydraulic modelling).

Assessing the impact of mechatronic systems on the environment

The ever-increasing power consumption and the associated consumption of non-renewable natural resources lead to an overall environmental degradation. Efforts to increase the energy efficiency, to reduce greenhouse gas emissions and the sustainable use of natural resources have a significant potential for improving the environment and its preservation for future generations. To realize this potential, it is however necessary to manage the assessment of the environmental impact of product design on the environment. Mechatronic systems (e.g. machinery, manipulators, actuators, and manufacturing machines ...) form significant industrial facilities and at the same time they also represent major appliances consuming the electrical energy, and during their entire life cycle they have a considerable impact on the environment. The most demanding industry sectors are: production of iron and steel, which are materials that are often used in the construction of mechatronic systems. The present article is devoted to the methodology of assessment of the effects of general mechatronic system on the environment. The environmental burden is presented in the form of carbon dioxide emissions caused by the production of selected construction materials.