Yu Hou Wu

Research on Optimal Design and Processing of High-Speed Ceramic Ball Bearings without Inner Rings

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.

The Detection and Analysis of Straightness Errors on Pillar and Guide Rail of Alien Stone Turning-Milling Compound Machining Center

The alien stone turning-milling compound machining center is a new generation gap multifunctional compound machining center. It is used to process rotating part of alien stone products and three-dimensional sculpture products. The pillar and guiding rail are the key parts of the machining center. The straightness error of the pillar and guide rail seriously impacts the linear motion precision of beam parts. Comparison the straightness of guiding rail with pillar or without pillar, it shows that the results meet the standard of GB/T16462-1996. So it ensures the accuracy of the linear motion precision of beam parts. It lays a solid foundation for achieving the design function and machining precision.

High-Efficiency and Precision Grinding Technology of HIPSN All-Ceramic Bearing Race

This paper deals with the development of a high-efficiency and precision grinding technology for producing HIPSN ceramic bearing races. A new high-speed CNC grinding machine has been developed, which is equipped with a high-speed ceramic spindle with a built-in motor. Extensive experiments have been performed with this new machine to investigate the influence of various process parameters such as wheel speed, work speed, depth of cut, and wheel grit size on material removal rate, surface finish, grinding forces, and so on. The results of these investigations are presented in this paper. With the application of this technology, a low cost production of ceramic bearings race was realized with the most optimized process parameter.

Parameter Optimization for Oil/Air Lubrication of High Speed Ceramic Motorized Spindle without Bearing Inner Rings

Recently, hybrid ceramic bearings and oil/air lubrication have been used more and more on high speed spindles. However, applying an appropriate lubrication and the hybrid bearings can’t be overemphasized, and the oil/air supply with inadequate parameters is undesirable. In this study, a high speed ceramic spindle equipped with HIPSN (Hot Isostatically Pressed Silicon Nitride) full-ceramic ball bearing and Y-TZP (Yttria partially stabilized Tetragonal Zirconia Polycrystal) ceramic spindle shaft was designed for higher speed, stiffness, precision and longer operating life. Furthermore, the performance of a high-speed ceramic motorized spindle under different lubrication parameters was investigated. The optimum lubrication conditions that create the smallest temperature increase were obtained by the applying of the Taguchi method. The results show that oil volume per lubrication cycle, interval time per lubrication cycle and air pressure are three pacing factors that affect the temperature increase most significantly in ceramic motorized spindle with oil/air lubrication.

Design on High-Speed Precision Grinder

As one of the modern manufacture technology, high-speed precision grinding takes an important part in the modern manufacture field. With the development of the technology on high-speed spindle unit, linear precision high-speed feed unit, manufacture of grinding wheel, measurement etc, a great deal of research achievements make it possible for high-speed precision grinding. In this paper, using PMAC (Programmable Multi-Axis Controller)—PC as the central controller, a new kind of high-speed precision grinder is designed and manufactured. The servo control technology of linear motor is investigated. The dynamic performances of the machine are analyzed according to the experimental results. Elliptical workpieces have been machined with this new high-speed precision grinder. Based on these research results, a very helpful approach is provided for the precision grinding of complicated workpieces, and these results promote the development of high speed grinding too.

Structure Optimum Design Based on Maintenance and Lifting Equipment for Wind Turbine

To meet the urgent demand of maintenance and lifting equipment for wind turbine, combined with designation demand, two kinds of primary structure of the maintenance and lifting equipment has been proposed, analyzed and compared. By means of the Solid Works software the initial design on the two kind of the machine, the self-climbing crane and the trailed hoisting platform, have been conducted, the static analysis has been performed based on the mechanics model, and the advantages and disadvantages of these methods have been pointed out and compared in the paper. Compared with the self-climbing crane, the mechanical structure of the trailed hoisting platform is simpler, the control system presented more reliable, simple, easier realized etc, and the cost is lower. The self-climbing crane is high-automatic, but the design of crane high in the free degree and high in difficulty, and the climbing force focused on the wind turbine tower is too large. Conclusion The trailed hoisting platform is determined as the main design method to design the maintenance and lifting equipment for wind turbine.

The Topological Optimization Design of Cross Beams Structure of Shaped Stone Turning-Milling CNC (HTM50200)

To reduce the overall mass of the machine tools, this paper made the structural lightweight design to crossbeams of the HTM series gantry machine by topology optimization. The topology optimization mathematical model was built by taking the quality as the constraint, overall stiffness to the maximum (complicance to the minimum) as the design goals. It also took HTM50200 Turning Milling Center as an example, put forward an asymmetric layout structure of auxiliary hole according to the optimization results by numerical simulation and calculation of ANSYS. By verified, the mass of the structure was 2.76% lower than traditional structure, and the maximum deformation decreased by 16.07%. By applying the topology optimization method to the design process of the HTM series machining center, the utilization of materials will be improved and the production costs will be reduced.

Analysis about the Influence of Load on Loss of the Ceramic Spindle

The increase of loss causes the temperature rise in motor, reducing the using life of spindle, which can seriously affect the performance of motor. Thus, accurate calculating of loss is meaningful to optimal design of electric spindle. In this paper, the losses both with load and without load were analyzed by time-step finite element method. As the result of simulation analysis, the spindle losses with load are higher than those without load. Comparison analysis indicates that losses are various with different load. And the load impacts on core loss mostly in ceramic spindle. In addition, in asynchronous ceramic spindle with 4N•m rated load, the core loss, solid loss and stranded loss are least when the load change from 1.8 N•m to 3.8N•m. Accordingly, the best operation condition under the influence of load in electric spindle is gained.

Research on the Rock Breaking by Double Disc Cutter Test-Bed

Rock tunnel boring machine is one of the main machineries and equipments for underground engineering, and the failure of tool systems is its main failure form. Rock hob test-bed is the only testing equipment for tool failure and wear. In this paper, the breaking rock by the double disc cutter is simulated and four kinds of rocks are selected to test the influece of rock characteristics and spacing between two disc cutters on the rock breaking by the double disc cutter test-bed. The results show that there is different optimal spacing between two disc cutters for different rock; the optimal spacing is inversely proportional to the hardness of the rocks; the maximum stress appears the boundary between the disc cutter and rock.

Research on Automatic Control System of Suspended Access Platform Based on PIC16F877A

The design of automatic control system mounted on the suspended access platform is put forward. With advantages of the microcontroller in real time data acquisition and data processing, PIC16F877A is applied as controller of the system. Angle sensor and pull sensor are applied as measuring elements of the system. The control system can implement functions of automatic leveling and overload protection. The new automatic control device is tested to be easy to operate and high reliability. It completely meets requirements and suits for multi-series specifications suspended access platforms, worth to be widely extended in applications.