Experimental study of rigidity of a technological system on the basis of industrial robot Kuka KR 300R2500 Ultra

In modern machine-building production, there are many parts that have both significant overall dimensions and complex hard-to-reach surfaces for processing. The manufacture of such parts is carried out on specialized equipment, which has the same significant overall dimensions. However, the complexity of the design of a number of parts, such as the body of a rocket engine, large volume tanks, non-separable metal structures, etc., as well as their inaccessibility, level the technological capabilities of this equipment. Currently, industrial robots equipped with tool spindles are used to process such parts. The presence of a large number of degrees of freedom of this equipment, the relatively small overall dimensions and the vastness of the working area allow them to be effectively used in this field of mechanical engineering. However, the insufficiently studied rigidity of this equipment, the lack of specific recommendations for their use significantly limit the scope of their application. Thus, the issues related to the mutual influence of the rigidity of the technological system, cutting forces and cutting conditions in the manufacture of large parts using industrial robots are relevant and require a comprehensive study. In order to study dynamic processes in the manufacture of large-sized parts using an industrial robot, experiments were carried out to determine the amplitude-frequency characteristics of vibrations that occur during processing. An experimental study made it possible to establish that the rigidity of the technological system varies over a wide range. At the same time, the rigidity of the part under an impulse load differs from the rigidity during milling by at least an order of magnitude, and the rigidity of the spindle during milling differs from the rigidity of the part by at least 2 orders of magnitude. Based on this, in the process of designing the machining of large-sized non-rigid parts using industrial robots, it is necessary to take into account the worst conditions for rigidity. It is advisable to base further recommendations on the appointment of cutting conditions under changing processing conditions on the basis of mathematical modeling of the rigidity of the elements of the technological system. Also, to automate the process of removing the parameters of the rigidity of the technological system, an urgent task is to determine by test determination of vibrations on the spindle of an industrial robot and indirect assessment of microdisplacements on the part.