Usage of physical and mathematical simulation for improvement of the process of metal shear cutting

Chosta

Int J Adv Manuf Technol

et al. 2021

The applicability of a wedge-joint mechanism with a curving wedge in presses for the implementation of metal forming separation processes was substantiated. The paper states the fact, that the wedge-joint mechanism graph of the deformation force change is the closest to the technological typical graph of the force change during separation. At the same time, the wedge-joint mechanism with a curving wedge has a lower height of the parts in comparison with the traditional crank mechanisms, which provides less elastic deformation and press dynamics. The use of the additional wedge mechanism in a press with the wedge-joint mechanism with a curving wedge to ensure the approximation motion is proved. This makes it possible to reduce the energy consumption for elastic deformation and further reduce the dynamic force. The mathematical models of the wedge-joint mechanism with a curving wedge, presented in the form of a two-slide link mechanism, were developed, allowing to perform its structural, kinematic and dynamic analysis. Based on the analysis of the proposed mathematical models, dependencies were identified and a procedure for calculating the geometric, kinematic and power parameters of wedge-joint mechanisms with a curving wedge for separation processes was developed. Comparison of the kinematic and dynamic analyzes results carried out by analytical and graphicanalytical methods confirms the reliability of estimates, since their discrepancy is not more than 2.5%. Experimental studies have confirmed the adequacy of mathematical 2 models. The error between the calculated and measured values of the forces on the slide does not exceed 10%.

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Section: Figure: 11 Typical Force Diagrams Of Press-forging Plants: 1 -Toggle Press; 2 -Wedge-joint Press With a Curving Wedge; 3 -Typicamentioning

confidence: 99%

“…They are carried out both on specialized press-forging equipment: shears, cold breakers, etc., and on all purpose one: hydraulic and mechanical presses, hammers, press hammers, in which, as actuators, hydraulic cylinders, crank, toggle, screw mechanisms are used. They are, as a rule, multi-link and have a relatively low rigidity [2,3].…”

mentioning

confidence: 99%

Development and research of the press operating mechanism, made in the form of the wedge-joint mechanism with a curving wedge for separation operations

Chosta

Int J Adv Manuf Technol

et al. 2021

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“…The most promising of all cutting methods, in terms of productivity and waste, are cutting with a shear and bend breaking. Comprehensive studies of waste-free methods for cutting of the rolled stocks have been widely carried out [3][4][5][6][7][11][12][13][14][15][16][17][18]. During this time, a large amount of information has been accumulated on the nature, mechanisms and criteria of fracture.…”

mentioning

confidence: 99%

“…During this time, a large amount of information has been accumulated on the nature, mechanisms and criteria of fracture. The following scientists made a significant contribution to the development of this science: K. Kessler [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18].…”

mentioning

confidence: 99%

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Original Research the use of a Neural Network Classifier of Material Facture Criteria for the Rational Choice of the Method for Cutting of Rolled Stocks

Kukhar

et al. 2021

Preprint

To select a rational method for cutting of rolled stocks made from materials with different physical and mathematical properties, an engineer must have the tools to make such a choice. For this, it is proposed to use the well-known synergistic material fracture criteria. In order to find the most informative system of synergetic criteria allowing to classify materials authentically by their fracture sensitivity, the software was developed. It allows to solve the clustering problem in a multidimensional space of parameters and present the obtained information in a visual form using self-organizing Kohonen maps. The cluster analysis of the synergetic criteria of fracture material was carried out. The most informative criterion among the ones characterizing the mechanical properties of steels is the «offset yield strength», among the synergistic ones – «scale criterion». At the same time, among the traditional mechanical features of steels, a set allowing to classify materials with a given integrity by their cutting sensitivity has not been found. It was established that the synergistic criteria: «crack propagation criterion» and «brittleness criterion» are basic informative features. When adding any of the remaining complex criteria («crack nucleation criterion» or «scale criterion»), they form the most informative sets of minimal power, providing the classification of materials by their cutting sensitivity with a given integrity. In order to obtain high quality billets at a minimum conversion cost, recommendations were developed for choice of the method for cutting of rolled stocks in magnitude of criteria values: «crack propagation criterion» and «brittleness criterion». To cut materials «in plastic state», the cutting with a shear should be used, specifically – a closed cut-off scheme or an incompletely closed cut-off scheme with an active transverse clamp or a cut-off scheme with a differentiated rolling clamp. If increased requirements are imposed on the geometric accuracy of the billets, it is recommended to use complex blanking and cutting processes. For cutting materials «in elastoplastic state» there are good reasons to use a cut with a shear, and in particular – an incompletely closed cut-off scheme with an active and passive transverse clamp. Closer to the class interval, it is possible to apply cold bend breaking with the application of an effective stress concentrator. Cold bend breaking should be used to cut «brittle» materials. The carried out experiments confirmed the adequacy of theoretical conclusions and recommendations on the choice of a rational method for cutting of the rolled stocks to obtain high quality billets.

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Classification of steels according to their sensitivity to fracture using a synergetic model

Int J Adv Manuf Technol

Kukhar

et al. 2022