PROBLEM APPROACH TO TEACHING “DESIGN OF WOODWORKING ENTERPRISES” FOR FUTURE SPECIALISTS OF PROFESSIONAL EDUCATION

Abstract

The problem approach in teaching the course “Designing of Woodworking Enterprises” for future specialists of professional education on the examples of investigation of constructions and their elements that deals with bending is considered. The purpose of teaching the discipline is to form students’ knowledge and skills in designing enterprises, taking into account rational and integrated use of forest resources, improving product quality, increasing productivity on the basis of safety and environmental friendliness of production.The major task of capital building and modern mechanical engineering is saving of materials. And one of the main directions of the solution of this problem is the choice of rational forms of cross-section of beams and optimal arrangement of supports on conditions of strength and rigidity, which will significantly reduce the cost of manufac- turing the constructions of woodworking enterprises. The author examines the Emerson’s paradox when the strength of the bending beams increases with diminution of their cross-sectional area; Paran’s task is solved for rational sawing of logs to obtain bars with the largest strength and rigidity; the optimal arrangement of supports is proposed in conditions of strength and stiffness. Under the condition of strength, the maximum normal pressure can be reduced in two ways: by reducing the bending moment (due to the optimal arrangement of the supports) or by increasing the axial moment of the resistance (due to the rational form of the beam’s cross-section). The optimal arrangement of supports allows to reduce the bending moment for two-console beams in almost six times, and for single-console in almost three times more compared to the conventional non-console beam. On the condition of rigidity, the optimal length of consoles allows to reduce the largest deflection of the two-console beams by almost 14 times compared to a non-console beam with a uniformly distributed load over its entire length.In addition to designing rational forms of cross-sections and optimal arrangement of beam seats, material saving is achieved in other ways, namely: application of variable cross-section beams on their length; the creation of predetermined displacement of the supports of an indistinguishable beam to convert it into one-moment; using hinges in statically uncertain beams, which convert them into statically defined and one-dimensional stable ones; the previous rotation of the hardened girder cross-sections to the given angle.