Vol 36, No 10 (2016)

Methods that take account of the properties of the propulsion system and the terrain (along with their interactions) are outlined, for use in quality assessment of the locomotion system in planetary rovers in which wheels with individual electromechanical drives are mounted on a self-propelled chassis. Criteria for optimization of rigid metal wheels are determined, and selection criteria for balanced suspension systems are established.

The possibility of using data from multiplex networks on vehicles in road tests, in the development of intelligent transportation systems, and in control systems for autonomous (self-driving) vehicles is considered.

Theoretical analysis of composite blades for gas-turbine engines is based on the theory of effective moduli and the Lagrange equations. The blades are regarded as twisted rods; the flexure-approximation coefficients are adopted as generalized coordinates.

The structure of linear negative matrices for the manufacture of Fresnel lenses and prisms is analyzed. The requirements on the equipment and cutting tool for the machining of negative matrices are discussed. A manufacturing technology for the matrices is outlined, and test results are presented.

The longitudinal–transverse extrusion of hollow components from bar is studied. Strength assessment of the blank is discussed. In view of the stress–strain state of the blanks, limits must be imposed on the process in order to maintain the strength of the lateral surface and prevent critical loads on the tool.

With the goal of improving machine-tool design, attention focuses on the possibility of manufacturing the components of metal-cutting machines from effective new nonmetallic materials that not only meet all the current requirements on such machines but also in most cases improve their performance. The best results are obtained with metal–concrete structures in which the nonmetallic binder consists of modified cement with chemically active additives. Results from materials science are compared with multiyear production tests of metal-cutting machines based on metal–concrete components, which are characterized by stable performance over time. On that basis, an effective new approach is proposed for the modernization of machine tools at the end of their effective working life, without replacing the fundamental structures. The design of the basic structures is analyzed. The production of metal–concrete components in a specialized department of the manufacturing plant is recommended.

Different concepts regarding the initial instrumental surface and production surface of cutting tools are outlined. The definition of the production surface in State Standard GOST 16530–83 includes two different surfaces. That poses serious problems for the theory of shaping. Definitions are proposed for the production line and the production surface. In addition, the cutting production surface is defined as the envelope of the production surface of a tool in cutting. Depending on the type of contact between the cutting production surface and the machined surface (all points, a single line, a single point), three general methods of surface shaping by a cutting tool are described. Specific tools are considered. For each tool, the general shaping method that best describes its operation is noted. The distinction between rolling cutters for gear turning and gear milling that employ the same general shaping method is established.

The influence of the hard-alloy substrate and the composite coatings of a tool on its wear resistance in the machining of high-temperature chromium alloys is investigated. The effectiveness of the coated hardalloy tool is determined by the properties of the hard alloy and the coatings. For hard alloys characterized by relatively low strength and crack resistance, the coatings prove ineffective, on account of the brittle failure of the substrate and the consequent destruction of the coating. On alloys with low thermal stability, the coatings are ineffective on account of weakening of the binder at the high temperatures associated with machining. It makes sense to use a hard alloy with mechanical properties such that the coating may operate effectively. Better properties are not needed.

Examples are presented to illustrate the high-speed drilling of small-diameter holes (up to 10 mm) by core flat drills: holes (diameter 7 mm) in a discharge valve; and the drilling two-part holes consisting of a cylindrical section (diameter 3.8 mm) and conical section (base diameter 10 mm) in a metal housing.

A new model of the metal removal in internal grinding permits calculation of the margin actually removed, the internal radius, the time for complete removal of the margin, and other parameters. In the model, the metal removal is determined with specified machining parameters; elastic deformation and the cutting kinematics are taken into account. The calculation is based on the model of the cutting force in internal grinding, which covers most of the factors affecting the cutting force (such as changes in the programmed and actual radial supply, the mechanical properties of the workpiece, the geometry of the wheel–workpiece contact zone, the wheel characteristics, and the blunting of the abrasive grains). Types of wheel–workpiece contact with inclination of the wheel axis on account of elastic deformation of the system are noted.