Applied Mechanics and Materials Vols. 446-447

Abstract: This paper presents an investigation into the losses and thermal characteristics of induction motors operated from pulse width-modulated (PWM) voltage supply in comparison to that operated from sinusoidal voltage supply. It was concluded that due to the abundant harmonics in the PWM waveforms, significant losses are induced in the motor by the inverter supply. The temperature ascends correspondingly. Experiments were conducted with no load and with load conditions. The losses and thermal characteristics were calculated using finite element analysis (FEA) and validated by the experiments.

Abstract: Machine tool is the foundation of manufacture，then, five-axis CNC machine is the sophisticated equipment of CNC machine. During the practical work，there is an thermal deformation in a CNC machine because of many kinds of heat sources . This deformation affects the relative displacement between the work piece and the cutter, caused the manufacturing errors, and influences the machining accuracy of the part. So is of great importance to research the thermal characteristics. In this paper, thermal characteristics of CNC milling machine are simulated by analyzing the thermal boundary condition and using the finite element software-ANASYS Workbench. Get the temperature field cloud picture of A/C axes bi-rotary mill head of five-axis CNC machine. Weakness of Thermal Characteristics will be found out. This research provides the theoretical fundamentals for improving the accuracy of the mill head.

Abstract: Under the background that modern machine tools have higher requirements to the spindle system, the accuracy, stiffness, critical speed and dynamic stability of the spindle bearing also put forward higher requirements. Traditional steel spindle has been difficult to meet the needs, because of its inherent characteristics. Advanced ceramics have excellent performance, such as low density, low thermal expansion coefficient, high stiffness, wear resistance and good chemical and thermal stability, which can meet the requirements of modern machine tool spindle to the performance of bearing material. The longest fatigue life is the objective function, the calculation method of the ceramic bearing optimal design is the external point method of penalty function, and the all-ceramic bearings without inner rings are successfully manufactured by the advanced manufacturing technology. Finally, the high-speed ceramic motorized spindle prototype was assembled with high precision successfully, and its performance test and analysis were finished, the results show that using the all-ceramic bearing can effectively improve the rotation accuracy and rotational stiffness of the spindle-bearing system.

Abstract: Roll bending plays an important role in elimination of non-uniform transverse internal stress and improvement quality of plate shape in leveling process. Taken the wedge adjustment bending device on a 11-roll cold leveler in a cross cut line as research object, in order to studying its bending characteristic, three-dimensional assembly model contained roll system, roller bending frame and upper beam has been built based on the finite element method. With the model, the necessity and function of the bending device has been verified. Different plate width, leveling force and roll bending value effects on working roll gap curve have been discussed. The result could serve as theoretical base for online set model and provide more precise parameters, accordingly maximize the potential ability of levelers.

Abstract: The traditional method and mechanisms used for dehulling, cracking, shelling, squeezing or pressing of nuts in the post harvesting operation, is constrained to single platform with multi-operational facilities due to the oil splash ,wound making, poisonous material causing a health hazards hence the vertical cut plane with easy exchange facility by chuck mechanism for cutting tool as well as fixture for material for minimum throughput time and human comfort has been considered in the new design called Multi-Nut dehulling machine. The average product material efficiency was 85.29%, mechanical damage was 14.71% out of 100% shelling and the throughput capacity was 0.60 kg/hr for marking nut. This performance was better than the traditional dehulling, notch and curved blade type dehulling. Splashing of the BSL in marking nut dehulling with multi nut dehuller was observed negligible. The Product material efficiency 72.23% , mechanical damage 27.77% and the throughput capacity was 2.48 Kg/hr for walnut. Machine can cut areca nut 1 kg /hr of the size 10-15 mm.

Abstract: To solve the problem of the traditional drill rig in its designs and applies, the concept of the rodless drilling rig was put forward. The working and structural principles of the rodless drilling set were introduced. The three-dimensional models of the rodless drilling rig and rodless drilling set were built based on virtual prototype technology. A detailed analysis of the rodless drilling sets force was made, and the force statuses of one bearing board of the rodless drilling set in all directions were given out. By the rodless drilling sets prototype test, the displacement curve was achieved, which indicates the working and structural principles of the rodless drilling set are correct, and its operation is reliable as well.

Abstract: We show that there always exists a globally and exponentially convergent state-observer for a class of nonlinear systems with nonlinearities that need not satisfy locally Lipschitz condition. So it can be applied to a mechanical system with discontinuous nonlinearities such as Coulomb friction. We not only provide a rigorous proof of convergence of our proposed observer but also how to systematically design it. Through simulation results, the validity of the proposed observer is verified.

Abstract: Finish Match Grinding is amongst the most demanding of all high precision grinding tasks and there are very few grinding machines capable of carrying out this process and delivering the tolerances required on a high volume production basis. In the present work experiments were conducted on Bahmuller finish match grinding machine with L9 Orthogonal array. The important machining variables considered were air grind feed, rough grind feed, fine rough grind feed and input stock of material. The developed model can be used across various industries using the same operation to select right combination of machining parameters to achieve an optimal cycle time, surface roughness (Ra) and roundness. The confirmatory tests gave very good results and with a cycle time reduction of 20%.

Abstract: To ensure the safe use of single shear hydraulic lift platform for processing and manufacturing railway vehicles. This paper analyzes the use conditions of single shear hydraulic lift platform, and makes a contact nonlinear finite element analysis on various typical use conditions. The positions of parts subject to danger can be found out through the results of static strength analysis, which finds out the weaknesses and prejudges the failure trend of parts, and which provides guidance for prejudging the faults in actual production and can prevent occurrence of accidents.

Abstract: The Spiral Coil pump is a non-conventional water pump which can be powered by wind energy or flow energy of river water. It can also be hand driven. It is very useful especially in rural areas for farming and irrigation purposes. Spiral Coil pump comes under the category of a low to moderate lift pump. In the present study, the hand operated experimental setup is designed and constructed to analyze the performance of the spiral coil pump under different parameters. The parameters considered are submerged ratios, rotational speed, layers of coils. For setup of 0.8 m wheel diameter with 7 number of coils, the maximum head obtained is in between 4.3 m to 5 m with maximum discharge 1200 lit/hr for single layer and 2280 lit/hr for double layer of the coil with efficiency range 20% to 74%.