• MATHEMATICAL MODELLING OF TECHNOLOGICAL PROCESSES AND SYSTEMS

    INVESTIGATION OF SAMPLES ACCURACY TO MODEL THE PROCESSES IN 3D PRINTING

    Mathematical Modeling, Vol. 1 (2017), Issue 4, pg(s) 192-195

    3D printing also called Layer based technology, Freeform fabrication, Additive manufacturing or Rapid Prototyping technologies has undergone significant development over the last decades. The growth is related to the expansion of the range of materials used, application areas, and range of possible sizes from nanometer to tens of meters as well as increasing machine accessibility. There is a growing consensus that 3D printing technologies will be at the heart of the next major technological revolutions. At present there are some technological specifics and associated difficulties in 3D printing one of which is the accuracy of the manufactured product. Research in this area would allow modelling of 3D printing processes.

    The article describes the possible types and sources of inaccuracies in 3D printing processes. The various types of test pieces used in practice are examined to quantify the errors in shape and sizes after building. Test pieces with predefined discrete points and methodology are provided to calculate inaccuracies. The results are presented in the terminology of “linear” and “shear” deformations. This gives opportunity to determine the variations in the shape and dimensions of the parts built by 3D printing. On the basis of the discreet results obtained, the possibility of 3D printing process modelling is discussed and presented.

  • THE PROVIDING OF THE POWER SAVING CONTROL OF ONE OUTPUT VALUE WITH TWO CONTROLLING CHANNELS HAVING DIFFERENT EFFECTIVENESS AND COST OF THE CONTROLLING RESOURCE

    Machines. Technologies. Materials., Vol. 9 (2015), Issue 9, pg(s) 50-54

    Controlling of objects with the feedback negative loop is widely used in industry, intelligent technologies, robotics and transport systems. A negative feedback loop by comparing of the prescribed value of the output value with measured value of it generates a control signal, which adjusts the output value of the object. Typically, the number of controlled output values is equal to the number of feedback channels acting on the object, but in some cases, the number of the channel can be more. This situation is especially frequent in transportation systems. In the problem of the design of regulators, they pay the most attention to ensuring the required static and dynamic control accuracy, but recently the attention to the conservation of the resource manager increased. This saves fuel or energy costs, which is especially important, for example, in space technology. The task of saving resources in the control of an object with an excess amount of control channels was not previously considered in the literature. In this paper, the problem is investigated by numerical optimization with simulation. In some cases, the cost of resource of the control by the different channels may vary. At the same time the cheaper resources can have the worst quality of the control, for example, it can has a discrete form or (and) less speed and so on. In this paper, we study such state of the problem and give its solution. It is shown that for a suitable choice of the cost function one can preserve rather high quality of the control, while ensuring saving of the controlling resources. Resource saving can reach in some cases 96%, which is illustrated by an example.

  • SUPERFINISHING FLAT AND CYLINDRICAL SURFACES OF GEAR PUMP PINIONS

    Machines. Technologies. Materials., Vol. 9 (2015), Issue 1, pg(s) 22-24

    The quality of the flat and cylindrical surfaces of the gear pump pinions is a restrictive condition for a suitable work. The required quality of these surfaces is very high, R = 0,04 – 0,08 µm. As well, there are restrictive conditions input for the form and positioning a deviations. So far, the manufacturing of these surfaces used to be achieved by grinding and no one could guarantee that the surface roughness was in accordance with the technical documentation. The presented constructive solution allows obtaining a good quality of the flat and cylindrical surfaces. It uses a superfinishing attachment that can be mounted on the engine lathe.