Tomáš Martinec

Mathematical model of composite manufacture and calculation of robot trajectory

This paper discusses the problem of calculating the trajectory in a 3D environment of an industrial robot in the production of composites for the automotive industry. The used technology is based on a winding of a carbon (or a glass) filament rovings on a non-bearing polyurethane core which is a frame shape with a circular cross section. The polyurethane frame is fastened to the end-effector of the robot arm (robot-end-effector) and during the winding process goes through a fibre-processing head on the basis of the suitably determined robot-end-effector trajectory. The fibre-processing head is fixed and is composed of three guide lines (two outer lines are rotary and the middle is static) with coils of carbon rovings. The fibre-processing head winds on the frame three layers of filaments at angles of 45°, 0° and -45°. The model of a non-bearing polyurethane frame passing through the fibre-processing head is described in Euclidean space E3 of the robot. The non-bearing polyurethane frame is specified in the local Euclidean coordinate system E3, the origin of this system is in the robot-end-effector. The location of the local system of the robot-end-effector in the basic coordinate system of the robot is specified using the “tool-center-point” of the robot. We use the described mathematical model and matrix calculus to calculate the trajectory of the robot-end-effector to determine the desired passage of the frame through the fibre-processing head. The required translation and rotation matrices of the local coordinate system (of the robot-end-effector) relative to the base coordinate system of the robot are gradually calculated. Subsequently, the Euler angles of rotations are determined corresponding to the transformation matrices. The sequence of “tool-center-point” values which allows us to define the desired trajectory of the robot-end-effector and thereby the passage of the frame through the fibre-processing head is determined in this manner. The calculation of the trajectory was programmed in the Delphi development environment. A practical example of the passage of a polyurethane non-bearing frame through fibre-processing head is dealt with in the article. The calculation of the robot-end-effector trajectory was used as input values for a graphics software simulator of robot activities. We can accurately determine the trajectory of the robot-end-effector during required work activities of the robot. This approach of determining the exact trajectory is qualitatively different from the application of the principle of programming a robot by teach-in. The advantages of the described approach will be significantly enforced, for example, when we need to solve the problem of the robot-end-effector trajectory optimization. The determining calculation of the trajectory can of course be used in other applications of industrial robot use. Moreover, the described procedure for determining the trajectory brings the manufacturer almost no additional costs.

Development of fire shutters based on numerical optimizations

This article deals with a prototype concept, real experiment and numerical simulation of a layered industrial fire shutter, based on some new insulating composite materials. The real fire shutter has been developed and optimized in laboratory and subsequently tested in the certified test room. A simulation of whole concept has been carried out as the non-premixed combustion process in the commercial final volume sw Pyrosim. Model of the combustion based on a stoichiometric defined mixture of gas and the tested layered samples showed good conformity with experimental results – i.e. thermal distribution inside and heat release rate that has gone through the sample.

Composite Production and Industrial Robot Trajectory Calculation

This paper discusses the problem of composite production. Composites often supplant traditional materials such as steel, iron, wood, etc. The most important advantages of composites are their high strength and flexibility, low weight, long lifespan and minimum maintenance. The technology used in this article is based on a winding of a carbon (or a glass) filament rovings on a polyurethane core which is a frame shape in 3D space with a circular cross section. The polyurethane frame is fastened to the robot-end-effector of the robot arm and during the winding process goes through a fiber-processing head on the basis of the suitably determined robot-end-effector trajectory. The fiber-processing head is fixed in robot working space and is composed of three guide lines with coils of carbon rovings. Quality production of described type of composite depends primarily on the correct winding of fibers on a polyurethane frame. It is especially needed to ensure the correct angles of the fibers winding on a polyurethane frame and the homogeneity of individual winding layers. The polyurethane frame is specified in the local Euclidean coordinate system E3, the origin of this system is in the robot-end-effector. We use the matrix calculus to enumerate the trajectory of the robot-end-effector to determine the desired passage of the frame through the fiber-processing head. A practical example of the passage of a polyurethane frame through fiber-processing head is dealt with in the article. Of course, the determining calculation of the robot trajectory can be used in other applications of industrial robot use.

Numerical model describing optimization of fibres winding process on open and closed frame

This article discusses a numerical model describing optimization of fibres winding process on open and closed frame. The quality production of said type of composite frame depends primarily on the correct winding of fibers on a polyurethane core. It is especially needed to ensure the correct angles of the fibers winding on the polyurethane core and the homogeneity of individual winding layers. The article describes mathematical model for use an industrial robot in filament winding and how to calculate the trajectory of the robot. When winding fibers on the polyurethane core which is fastened to the robot-end-effector so that during the winding process goes through a fibre-processing head on the basis of the suitably determined robot-end-effector trajectory. We use the described numerical model and matrix calculus to enumerate the trajectory of the robot-end-effector to determine the desired passage of the frame through the fibre-processing head. The calculation of the trajectory was programmed in the Delphi development environment. Relations of the numerical model are important for use a real solving of the passage of a polyurethane core through fibre-processing head.

Experimental Analysis and Optimization of Vibrations of a Clamping Device by Using Hyperelastic Elements

Nowadays composite frames can be used, for its specific properties, in many fields of industry. Lightweight composite frames can be significant structural components in some transportations, flights and military applications. The main problem is how to use automatic applications for winding filaments of the carbon fibres on a closed spatial shaped core of product frames, that has been still doing by the hand manufacturing. For automatic production could be used unique prototype of robotic technology, which allows winding of the carbon fibres on closed shape into the core of a frame. The biggest problem of the clamping device, used for the closed frames, are their vibrations and resonance caused due to the rotary motions. The vibrations and resonance negatively affect the process of carbon fibres winding. Experimental measurements were carried out to determine the acceleration on individual arms of the clamping device, which reaches to 2.5±0.6 g. Minimizing of the vibration was performed by a hyperelastic elements which reduce vibrations to 0.4±0.15g.

Analysis of Changes in the Surface Quality of a UD Prepregs Composite due to Mechanical Loading

Optimizing the mechanical properties of composites is very important for light low energy constructions. Unidirectional prepreg (UD prepreg) is an intermediate product synthesizing a unidirectional layer of carbon fibres with a matrix. This can be used in the production of continuous fibres of reinforced composites. The individual layers can be stacked on top of each other to precisely orientate the layers and attain the maximum properties in a given direction. The resulting composite is ultra thin with the highest possible fraction of fibres. Prepreg composites are very high quality and have very good mechanical properties. They can be applied in sectors where the requirements for mechanical resistance are very high. This paper presents an experimental and numerical analysis of the surface of a composite and the changes that may occur to it under the influence of loading. The Ball Drop Test (ASTM D6024-07 / DIN 52306) was used as a stress test. Test samples scanned by image analysis showed that the surface properties of the UD prepreg were not disrupted, while scanning with AXIO IMAGER M2 showed apparent surface disruptions. From the numerical simulations it was determined that a directional orientation of the fibres of +45°/0°/-45° significantly affects their elastic properties.

Heating of Mould in Manufacture of Artificial Leathers in Automotive Industry

This article focuses on a model for the creation of artificial leather production in the automotive industry. Aluminium or nickel shell moulds are used in the production of leathers. The inner mould surface is sprinkled with a special PVC powder and the outer mould surface is warmed by infrared heaters located above the mould. This is an economically advantageous way to produce artificial leathers used in car interior equipment. The article includes a description of a model that allows us to calculate the heat radiation intensity across the mould surface for every location of heaters, and to optimize the location of the heaters by using a differential evolution algorithm. The process of experimentally measuring the heat radiation intensity in the surroundings of the infrared heater by using a robot is also described in the article. The calculations were performed using a Matlab code written by the authors. The article contains a practical example including graphical outputs.