Advanced Materials Research Vols. 418-420

Abstract: Eight kinds of materials with diverse pore-forming mechanism were added into the ceramic ingredient of superfinish grinding tool with the same amount, and the specimens were prepared and sintered in the same condition. Their pore-forming abilities in the sintered bodies were compared through several performance tests. By measuring the porosity, bulk density, water absorption and flexural strength of these sintered bodies, and observing the SEM images, pore-forming agents with the best working mechanism was identified. It is proved that those pore-forming agents which have pore structures in themselves process the best pore-forming ability, and they can maintain relatively high porosity and high mechanical strength, which is good for the superfinish grinding tools.

Abstract: Change detection of landscape patterns has become a fundamental research theme in urban and rural studies due to its scientific importance in understanding the connection of global environment changes to social-economic dynamics. Landscape patterns can be directly represented and visualized by landuse maps, and they can also be further abstracted and mathematically quantified by landscape metrics. This paper examines the changes in coastal landscape patterns of Tianjin Binhai New Area using landuse datasets of 1981, 1990 and 2000. The results show that the coastline played a controlling role in shaping landscape patterns across the study area. As a result, the rate of urban expansion in the north-south direction was much faster than that in the east-west direction. During the period of 1981-2000, most changes occurred on urban land, forestland, wetland and agricultural land, while the change on water bodies remained insignificant.

Abstract: In this paper a combined modeling method using digitized points measured by multiple-sensor integrated measuring system with a touch probe and a optical scanning probe is presented. The optical scanning data in the form of triangulated mesh and the high precision data captured by a touch probe on an integrated measuring system are transformed into a common coordinate system by the worktable for registration and improved ICP algorithm. A data merging method is used to keep the high precision of feature surfaces.The merging data is unified into a precise 3D model in CAD software environment based on the strategy for optimization reconstruction. Experimental results demonstrate the efficiency of the proposed method, which enhances the flexibility of digitizing while maintaining the accuracy of feature surfaces.

Abstract: This paper describes on the influence of thermal behavior of spindle on machining accuracy in micro-endmilling. In order to make clear the reasons why the depth of slot varies during slotting repeated, temperatures around the spindle head and the thermal expansion of spindle axis were investigated. The machine tool used for experiment was a small type of vertical machining center. The spindle used for experiment was a ball bearing spindle which rotated at 10000-40000 min-1. The spindle head made of aluminum alloy had various cooling systems for spindle motor and ball bearings, and the temperature of spindle head changed only a few degrees C. Therefore it seems difficult to assume that the primary cause was thermal deformation of spindle head structure, even though the coefficient of thermal expansion of aluminum alloy is approximately twice of that of steel. Finally the thermal expansion of spindle axis was partly measured and relation between the thermal expansion and the variation of depth of slots was investigated. The main results obtained are as follows, (1) Slotting after a long period warming-up of spindle resulted in a small change of depth of slot, but slotting without any warming-up caused an initial rapid increase and then saturation of depth of slot, (2) Temperature rise of spindle head and adjacent structure seemed out of relation to the variation of depth of slot, (3) The partially measured thermal expansion of spindle as well as temperature of lower flange of spindle showed qualitatively similar change corresponding to depth of slot.

Abstract: The theory of electrochemical jet machining was introduced, and effect of different parameters on anodic electric field intensity is finite element analyzed by ANSYS software. The Simulation results show that, the electric field shares the same distribution under different electrolysis voltage, which generally contains three parts, uniform distribution area, gradually weakened area, scattered area. In the uniform distribution area, electric field shows comparative uniformity. The anode electric field generated by different jet distance is also obvious distribution areas, the electric field intensity shows decreasing trend. Electric field intensity is found to have a close relationship with electro jet nozzle diameter, in which a faster jet velocity would bring more concentrated distribution of the electric field as well as a smaller size of electric field.

Abstract: The coupling degree and structure factor of mechanism are the important parameters for the research of principle of mechanism structure, kinematics and dynamics in the ordinal single opened chain method, This article presents the algorithm of coupling degree for the kinematic chain with compound hinges on the basis of that for the kinematic chain without compound hinges and the dual-color topology graph, through which the mechanism with compound hinges can be decomposed into basic kinematic chains, the correctness of the algorithm has been verified by the practical example.

Abstract: The head frame is a key component which plays a supportive and accommodative role in the spindle system of CNC machine tool. Improving the static and dynamic characteristics has profound significance to the development of machine tool and product performance. The simplified finite element modal is established with ANSYS to carry out the static and modal analysis. The results showed that the maximum deformation of the head frame was 0.0066mm, the maximum stress was 3.94Mpa, the deformation of most region was no more than 0.0007mm, which all verified that the head frame had a good stiffness and deforming resistance; several improvement measures for dynamic performance were also proposed by analyzing the mode shapes, and the 1st order natural frequency increased 7.33% while the head frame mass only increased 1.58% applying the optimal measure, which improved the dynamic characteristics of the head frame effectively.

Abstract: In this paper, the gear acceleration noise model is first built up. The theoretical formula for calculating meshing acceleration noise is developed by dynamic analysis. Base on the impact theory, we first treat the gear meshing behavior as two variable radius cylinders, construct dynamics model, and then according to the industry standard to calculate sound pressure value one meter away by simulation,. Finally, we obtain the optimize equation according to the relation of parameters and noise.

Abstract: The transplanting device is the key component of a sugar beet paper pot seedling transplanting machine. The parallel four-bar framework is composed of active and passive disc, connecting rod and the duckbill-type linkage, which could ensure duckbill-type device always moving perpendicular to the ground, and its trajectory is trochoid. When the device rotated to near the lowest position, the duckbill’s absolute speed is close to zero, at this time the paper pot seedlings were given out to drop into the trench smoothly through opening the beak, while the role of duckbill transfered from loading to helping the paper pot seedlings to avoid dumping, and the planting process is finished through earth up and suppression. The parameters of a duckbill-type transplanting device are obtained through optimization and simulation, which could meet the requirements of duckbill-type device for transplanting paper pot seedling of sugar beet.

Abstract: In order to improve kinematics performance of high-speed spatial PCMM(parallel coordinate measuring machine), the comprehensive dexterity coefficient, which are defined to evaluate the whole dexterity of various configurations, was applied to the kinematics performance optimization of PCMM. By analyzing three dexterity measures, including conditional number, the smallest singular value and operation of PCMM, the comprehensive dexterity coefficient was proposed. The influence law of the distribution position angle of the joints on the stationary platform and moving platform, the distribution position radius of the joints on the stationary platform and moving platform on the comprehensive dexterity coefficient were discussed. On these grounds, the distribution position angle of the joints on the stationary platform and moving platform, the distribution position radius of the joints on the stationary platform and moving platform were optimized. The simulation results show obvious improvement of the kinematics performance for PCMM, so that the powerful theoretical basis and method of optimization design for the PCMM are provided.