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Vol 38, No 8 (2018)
- Year: 2018
- Articles: 16
- URL: https://journal-vniispk.ru/1068-798X/issue/view/14031
Article
573-578
579-580
Formalized Configurational Calculations of Parallel Mechanisms
Abstract
Theoretically possible configurations of parallel mechanisms are classified, taking account of the hinge arrangement at the base and the moving platform. This classification permits the formulation of computational templates for each class of configurations. The associated computational algorithms require a minimum of initial data.
581-584
Design of High-Stress Slip Bearings with Liquid Lubricant
Abstract
The design of slip bearings with liquid lubricant used in airplane engines is analyzed. The advantages and disadvantages of the bearings when used in highly stressed transmissions are considered. Means of improving the bearings by means of new materials are proposed.
585-591
Surface Nanostructuring of Steel in Electrospark Alloying with WC-Based Electrodes
Abstract
The change in cathode mass and anode erosion during electrospark alloying is investigated, with different process kinetics. With increase in pulse length, the efficiency of deep electrospark alloying increases up to some limit determined by the electrode composition.
592-598
599-603
604-609
Diagnostics of Wheel Life in Grinding
Abstract
The change in effective grinding power with change in the grinding fluid is studied experimentally, in fixed machining conditions. A method is proposed for assessing the life of the wheels. This method facilitates the choice of the tool, grinding conditions, and composition of the grinding fluid.
610-613
Contract Model with Risk Sharing in Integrated Logistical Product Support
Abstract
With transformation of the defense industry and industry in general, -cost-of-ownership models in relation to high-tech products must be modified. The model must include cost sharing between the purchaser and the manufacturer. Thus, the required characteristics of high-tech products must be ensured by the purchaser and the manufacturer in cooperation, so that both partners share the risk of failure.
614-616
Influence of Rotor Eccentricity in Ultrahigh-Speed Electrical Machines on Their Characteristics
Abstract
The influence of rotor eccentricity in high-speed and ultrahigh-speed electrical machines on their characteristics is considered. A mathematical model permits analysis of the processes in ultrahigh-speed electrical machines with an eccentric rotor. The model is verified by computer simulation and also by means of physical experiments.
617-622
Influence of Spindle Wobble in a Lathe on the Tool’s Deformational-Displacement Trajectory
Abstract
Attention focuses here on the conversion of the trajectory of spindle-group wobble in a lathe into deformational displacement of the tool and the associated modification of the shaping trajectory. This process depends on the change in dynamic properties of the system due to the wobble. On the basis of simulation and digital experiments, it may be concluded that the wobble changes the stability of the trajectories and that various attractive sets are formed in the system (such as limit cycles, invariant tori, and chaotic attractors). The wobble does not change the shaping trajectory directly, but rather through the formation of attractive deformational-displacement sets. Therefore, the attractive sets affect the geometric topology of the workpiece surface and the limiting feasible manufacturing precision.
623-631
Strength Ranking of Hard-Alloy Cutting Inserts of Different Shape
Abstract
The stress–strain state of replaceable polyhedral inserts in composite tools is calculated by the finite-element method. The influence of the insert’s design parameter, the basing and attachment configuration, and the load on the stress and strain is established. Besides the strength of the inserts, attention is paid to the positional accuracy in the tool housing. Cutting inserts of maximum strength have been developed and patented.
632-634
635-637
Individual Crater Formation in Electric Discharge Machining
Abstract
The formation of a single crater in the machining of 38Х2Н2МА steel is considered. By means of Comsol Multyphysics 4.4 software, a mathematical model of that process is derived. To verify the model, experiments are conducted on the basis of factorial planning. The theoretical and experimental results agree. The experiments indicate that the factor with the most significant influence on the crater size is the current. In the range I = 3–8 A, the disagreement of the experimental and modeling results for the crater dimensions is 22%. That permits prediction of the quality in the electric discharge machining of 38Х2Н2МА steel.
638-641
Developing a Machining Strategy for Hard-Alloy Polyhedral Inserts on CNC Grinding and Sharpening Machines
Abstract
Methods of grinding and shaping the rear surface of hard-alloy polyhedral inserts are considered. Machining of the tool’s rear surface is simulated, and several kinematic configurations for margin removal are proposed. An algorithm for kinematic shaping of the rear surface of a hard-alloy polyhedral insert in CAD systems is outlined.
642-644
Chip Formation in Constrained Cutting
Abstract
Existing approaches to chip formation in free and constrained cutting are analyzed. A new approach to description of the chip formation zone in constrained cutting with a single conditional shear surface is proposed. An analytical description of the shape of that surface is presented in general form. As an illustration, the chip formation zone is analyzed for sharp and rounded cutting edges. The results apply to the mechanics of cutting by blades.
645-650