In the dissertation work the actual scientific and technical problem of the increase of efficiency for the control of automated laser welding process under conditions of unforeseen factors by the creation of: specialized information bases of knowledge on the basis of relations of parameters of laser welding modes by experimental results; metallographic images of macro-, microstructures of the weld and the seam zone according to the results of computer-experimental modeling; specialized information database due to information technology of objective evaluation of hardware components of data collection and control through the formation of coefficients for issuing relevant information (CIRI) on the examples of laser emitters, fiber laser modules, scanning elements of weld joint position sensors of thin-walled structures is solved.
For the first time, a specialized information base of knowledge has been expanded by creating high-quality metallographic images of fine-grained macro-, microstructures of welds and the seam zone of butt joints of thin-walled structures under conditions of unforeseen factors through the use of developed new and improved methods of crystallization control by laser radiation pulses of complex shape. The complexity is to create conditions for crystallization control, which ensure the emergence of the maximum number of crystallization centers while minimizing the linear growth rate of crystals. Three methods of crystallization control are proposed: by additional thermal effect on molten metal, the control of modulating pulses of combined laser-ultrasonic radiation due to the change of their frequency, amplitude and their formation by pulse-width modulation method, which creates a fine-grained structure in cast metal of the seams at the macro- and microlevels and provides high operational reliability due to high mechanical properties of connection of thin-walled structures.
The information technology for objective estimation of multiparametric components of data collection hardware (CDCH) and control in creating a specialized information database through the proposed criteria for issuing relevant information (CIRI), the peculiarity of which is that the value of the priority of coefficients (penalty functions, et etc.) is equal to one, has received the further development. The visualization of CIRI at the comparative analysis accelerates the process of a choice of the best hardware components of data collection and control, and also the procedure of creation of the specialized information database at the corresponding enterprise. The verification is confirmed by calculations of the synthesized CIRIs on the examples of laser emitters, fiber modules and scanning elements of weld joint position sensors of thin-walled structures.
The use of specialized information base of knowledge (mathematical models, generalized criteria for issuing relevant information) and CDCH database, which are used at the stage of technological preparation of information to control the process of automated laser welding of thin-walled structures under conditions of unforeseen factors, reduces material and energy time costs due to the reduction of costs for the corresponding preliminary labor-intensive research of manufacture technological preparation, this is especially noticeable in small-scale production and, as a result, expenses decrease by almost 50 %.
Given that the most promising and the least developed are information technologies of analysis under conditions of unforeseen factors to determine the best: control modes of the processes of automated laser welding of thin-walled structures; crystallization control methods at the levels of macro-, microstructures of welds and seam zones; hardware components for data collection and control, it is proposed to transfer the stored information to the developer from specialized information databases and data in the form of graphs, histograms, which accelerates the reception of information by 3, .., 4 orders.
The method for determining the best information parameters of the mode of laser welding of thin-walled structures to achieve the maximum value of the use of laser radiation power, the efficiency of which is 33%, is formulated.
The scheme of relations of metallographic weld images and the frequency of modulated laser pulses which provides their qualitative structures at macro- and microlevels is created. On the example of welding of steel structures of grade 1.4541 and thickness δ=0.2 mm, the results of the experiment determine the relationship between the value of frequency range of modulated laser pulses and the best value, namely: 2.0 ..., 3.0 kHz, while the size of austenitic grain is about 3 3 microns. This increases the ductility and strength of the welded joint of thin-walled structures.
