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In this paper, the temperature change curve of the casting and frozen sand mould during the solidification process of the A356 aluminum alloy in the frozen sand mould is tested. According to the actual temperature change curve of the casting surface and the sand mould surface, the interface heat transfer coefficient between the frozen sand mould and the A356 aluminum alloy could be reversed analysis. The results show that when the casting temperature is lower than 550 °C, the interface heat transfer coefficient remains about 750 W.(m2.K)-1; When the casting temperature is between 550 °C and 610 °C, the interface heat transfer coefficient increases significantly; when the casting temperature is higher than 610 °C, the interface heat transfer coefficient reaches the maximum value, which is about 2300W. (m2.K) -1. At this time, this study simulates the solidification temperature field of aluminum alloy hub parts in the frozen sand mould according to the interface heat transfer coefficient calculated by inverse analysis, and the temperature field of resin sand mould casting was used as for comparison. The results show that: under the same solidification time, the temperature field of A356 aluminum alloy hub parts in frozen sand mould is lower than that of resin sand casting, freezing casting can realize the high-speed solidification process of different parts of complex castings.

Metal bonded diamond grinding wheels are very important for precision grinding operations of hard and brittle materials especially like ceramics or cemented carbides. But the trueing and dressing problem has affected its wide use. In this paper, a new EDD (Electrical discharge dressing) device was developed for the dressing of metal bonded diamond arc grinding wheels. The EDD experiments were carried out with the new dressing device. The influence of dressing parameters on the dressing efficiency and precision was studied. Experimental results shown that the increase of pulse period and duty period helped improve the dressing efficiency in a certain range. The higher electrical parameters could get better dressing efficiency. The detection results revealed that the error of the arc profile after EDD could reach to around 3μm. mazhaokai2014

A process for grinding deep profiled slots in a nickel-based alloy with electroplated cubic boron nitride (CBN) wheels and straight oil is presented. These slots were prepared by this process for further grinding with electroplated CBN quills to generate the final fir-tree slots in gas turbine disks. Fir-tree slots are usually machined using broaching. The application of broaching, however, is limited in the case of nickel-based powder metal alloys due to short life of broaching tools and the effect on machined surface integrity. Grinding tests were first conducted on rectangular blocks to grind slots without inclinations at a fixed wheel speed vs = 60 m/s to identify the combinations of depths of cut, workspeed, and up/down grinding satisfying the requirements of ground surface quality and material removal rate. Inclined slots were then ground with the identified condition on a block representing a segment of an actual turbine disk to validate the condition. The wheel life was finally tested by grinding all the slots on the actual disk. Grinding power was measured, and the ground surfaces were inspected for any sign of burning. Preset target material removal rate and wheel life were obtained. It was found that electroplated CBN wheels are capable of grinding deep profiled slots on the difficult-to-cut nickel-based alloy.

Ultra High Strength Steel (UHSS) hot stamping technology is a special process which can enhance the steel tensile strength to 1500MPa. Appling this technology in producing vehicle structure parts can make car lighter and safer. In China there are more and more automobile enterprises adopt this technology. To master and extend the skill, China Academy of Machinery Science & Technology (CAM) have done systematic research, such as the strengthen mechanism of the steel, hot stamping key devices designing, forming and quenching integrated mould designing, stamping process parameters optimization, etc.. By now, CAM has mastered the mass production technology of vehicle parts, which can guarantee its shape and tensile strength, and produced such typical parts as door-beam, B pillar, etc.. The paper is an introduction of the research work and achievement about UHSS hot stamping developed by CAM.

Due to the yield strength σs, tensile strength σb of high-strength steel is much higher than original one, it is applied in making auto’s structure parts to improve the security of passengers and reduce the weight of auto. To make the production of the cold-stamp parts easier, the paper analyzed the structure of a classical part, door-beam, and found that the surface of the part should be G1 continuity at least, rather than G0 continuity. The G1 continuity part has more uniform thickness, less inner strain, and more safety from cracking.

Combined numerical simulations and experimentally measured data, the relationship between the initial temperature of the workpiece was described, the stamping speed, and the required forming force. Air cooling was included to determine the temperature of the part within the mold, and the required stamping force was optimized by studying the impact of the cooling time on the temperature of the part. The optimized model was verified and validated by comparing simulated data for an anti-collision beam with the experimental results of the hot-forming process. The results showed that the model provides a useful description of the hot-forming process; however, an empirical factor of 0.95 was required to achieve agreement between the simulated and experimentally measured data.

The filling and solidification process of casting that is closely related to lots of casting defects and has significant effect on the mechanical properties of castings. In this paper, the research status and development direction of numerical simulation technology of casting, especially of lost foam casting were reviewed and discussed. Also a brief introduction of the basic situations and product characteristics of several outstanding cast filling and solidification simulation softwares were summarized. In addition, the actual domestic application status of numerical simulation technology of lost foam casting in the foundry enterprises was analyzed and some suggestions were given as well.

Numerical control (NC, for short) forming machine is kind of digital forming equipment, which is based on the development of manufacturing technology without pattern, and can get mold by processing module directly, and its mechanical structure is mainly composed of the main structure, moving system, tool system and other components. The main structure is not only the foundation and framework of the entire machine, but also the most important component bearing pressure. The moving system is the most critical part of forming machine to achieve its fundamental function. Therefore, the design and development of the main structure and moving system have directly impact on the performance and service life of the forming machine, which is an important factor to reflect the level of the overall design. In this paper, structural static analysis of the main structure and moving system was made through finite element numerical simulation, the more reasonable scheme was optimized, by which the safety and reliability of forming machine was ensured. The research results can provide the necessary technical support for the structural design of NC forming machine.

During the casting of expendable pattern complex parts, the pattern accuracy is the key in determining the quality of expendable pattern. The paper conducts research on 5-axis CNC processing technology of multiple axes rotary spindle head expendable pattern, which is applied in processing experiments of complex parts expendable pattern. The results show that it is feasible to directly process expendable pattern with 5-axis CNC machine technology, which will have good promotional value.

In this work, a systematic study was carried out on the cutting process of expendable pattern, and the impact of process parameters, such as spindle speed, feed rate and cutting depth on the dimensional accuracy of expendable pattern was discussed. The results show that the dimensional accuracy at length and width directions of expendable pattern is less affected by the cutting process, while the machining accuracy at height direction of expendable pattern is greatly influenced by the cutting process. With the increase of spindle speed, the height error reduced undulately; with the increase of feed rate, the height error increases gradually; the selection of cutting depth has a reasonable range, above or below this range will cause the increase of the dimension error.

The finite element method (FEM) has been used for an independent analysis of forklift truck components. However, the accuracy of such an analysis may not be reliable because it does not in view of the interaction of the forces transferred between components. Here, we analyze the mast system as a whole using an FEM based on a simulation chain method employing MPC184 units, as well as a method to analyze components independently. Both methods are used to simulate the stress of the upper beam of the inner mast. We then compare the maximum stresses calculated using the two different methods under three sets of working conditions. The data show that, in comparison with theoretical results, the average error rate of the overall analysis method was 4.71%, while that of the independent analysis was 33.3%.

In this study, fundamental research, including material selection and structure design of guide sleeves in 3D weaving composites were investigated by three-point bending test, compression test and SEM observation. The results showed that carbon fiber composite guide sleeves had much higher interface bonding strength than titanium alloy guide sleeves, while worse flexural strength. There were three kind of structure design of the guide sleeves that were groove, rough surface and untreated surface. Compared with the structure of untreated surface, guide sleeves with grooves and with rough surface exhibited higher interface bonding strength, due to increasing the contact area between the guide sleeve and resin. But the guide sleeves with rough surface took the advantages of more simple to preparation and lower cost than those with the grooves. Furthermore the structure of groove could damage the flexural behavior of the guide sleeves.

In this paper, based on the experiments of high speed dry cutting nickel alloyed ductile iron with different nickel contents by graded ceramic tool, the cutting performance and wear mechanisms of graded ceramic tool were investigated. Results reveal that with the increase of cutting speed and nickel content the wear of graded ceramic tool is increased, wear mechanisms are transformated spalling and cohesive wear from abrasive wear, and chip shapes are turned into long arc segment from short segment.

Die design is one of the key technologies for hot stamping technology, and the quality of the forming part is influenced by the structure design of the cooling system parameters. Cooling pipe size, distance between cooling pipes, and depth from cooling pipe to die surface are the most important structure parameters, and the final microstructure and property of the forming parts are influenced directly by these structural parameters. In this article, the simplified model of hot stamping die was established, and the hot stamping die cooling structural parameters were analyzed by heat transfer theory. The mathematical model of the structure parameters was set up and verified by simulation and experiment. It was shown that the mathematical model of the hot stamping die cooling structural parameters met the cooling requirements; the hot stamping parts achieved the need of the martensite structure.

In 21th century, the product upgrading becomes faster and faster. The development of varieties of production needs rapid manufacturing technology. The rapid fabrication of sand mold & core is the key of rapid casting. In this paper, the rapid manufacturing technology without pattern was applied to produce the complicated sand molds & cores of pump case. The digital precision forming technology without pattern casting was selected to mill the outer sand mold. And the Selective Laser Sintering (SLS) technology was used to print the sand core. So the complicated sand molds and cores were fabricated rapidly without pattern. As a typical digital manufacturing technology, the rapid manufacturing technology without pattern has a variety of benefits such as short cycle, low cost, flexibility and so on. The technology that combines the sand milling and SLS provides a high-efficiency method for the Single and small batch castings.

Ceramic coating was fabricated on AZ91 biomedical magnesium alloy by plasma electrolytic oxidation. The coating was then subjected to surface laser treating, and the influence of laser treating on the morphologies and corrosion resistance of the coating were investigated. The results showed that PEO coating without laser treating showed coarse and porous surface and the pores on coating surface were big. When subjected to laser treating, the pores on coating surface became little and few. The corrosion tests in SBF indicated that corrosion resistance of PEO coating on magnesium alloy sample could improve the corrosion resistance of the substrate, and surface laser treating could further increase the corrosion resistance.

In the whole process of the LFC (or evaporative pattern casting, EPC), the quality of the foam pattern play a decisive role to the final casting quality. The present processing methods for the foam pattern are discussed, including foaming molding, manual cutting, and CNC machining, rapid prototyping, also the advantages and disadvantages of these processing methods are analyzed. As CNC machining become the main trend for foam pattern processing, some CNC machine oriented tools are summarized, including the hot wire foam cutter, the hot knife foam cutter, and the modified tools based on the traditional tools.

The need for lightweight automobiles has promoted the rapid development of hot stamping. The cooling system of the hot-stamping die determines the performance of hot-stamped workpieces. By establishing a simplified hot-stamping model, we determined that the temperature-time curve of a workpiece is an exponential function. Our research results showed that the depth from the die surface to the cooling pipes has the biggest impact on the cooling rate and uniformity of the workpiece; the correct depth must be ensured to obtain a uniform quenching rate. By studying the cooling buffer flumes, we discovered that the water flow in the pipes becomes more uniform with increasing flume width. With an increase in the flume height, the water flow uniformity in the pipes first increased, and then decreased. In addition, augmenting the pipe diameter near the inlet improved the water flow uniformity in the pipes.

Impregnation quality is vital to the whole composite. To improve it a new approach-infusion from both inside and outside at same time is supposed. Some comparison simulation studies, based on PAM-RTM software, are performed in this paper about the new composite forming method and traditional infusion method including flow behavior and filling time. Filling time via the two methods are compared, and the following results are obtained-It takes less time to fill the mold with infusion from both inside and outside at same time than traditional one; higher fiber volume fraction is, more favorable the new forming method is. The new infusion method is proved to be an effective and novel forming method about parts with high-thickness or high fiber content in composite forming area. The results will contribute to researches on the whole composite forming and bring prospect to provide more usages of three dimensional composites in high rank field.

Basic principle and forming process of three dimensional printing technology were introduced. The driving technology was researched from micro transporting methods of droplet jet and direct writing with dip-pen. The choice of drive technology directly determines overall design of the driver, and decides the best performance. The direct and indirect methods were analyzed to manufacture metal parts with three dimensional printing technology, which has better developing potentialities and expansive applying foreground.

Short circuit impedance test is one of the important methods for the transformer winding distortion diagnose. At present the test current is too low when we using short circuit impedance method. Upon the understanding for electrical properties of the transformer we developed a device with test current up to 10 Ampere, and combined longitudinal comparison method and lateral comparison method as our criterion algorithm. The device we developed matches the requirements of related standards. It comes in a complete set and fits on-site application. Through three practical examples we can see the improvement of the current is effective for the test accuracy in the transformer winding distortion diagnose.

An experimental study is reported on the grinding of a nickel-based alloy using vitrified CBN wheels. This work was motivated by switching the grinding of fir-tree root forms of jet engine blades from creep-feed grinding with conventional abrasive wheels to vitrified CBN wheels. The objective is to explore process limits and practical grinding parameters for judging the switch in terms of overall costs and productivity. Straight surface grinding experiments were conducted with water-based fluid on rectangular blocks at a fixed wheel speed v s = 45 m/s, various depths of cut a = 0.05 - 1.0 mm, and workspeeds v w = 2 - 40 mm/s. Grinding power, forces, surface roughness, and radial wheel wear were measured. Specific material removal rate of 8 mm 3/(mm.s) was reached in rough grinding using a wheel dressed for achieving surface roughness R a = 0.8 μm in finish grinding. It was found that shallow depths of cut combined with fast workspeeds, or less creep-feed modes, are more suitable for achieving high material removal rates with vitrified CBN grinding. Rough grinding is restricted by high grinding temperatures with newly dressed wheels and by chatters with worn wheels. © (2011) Trans Tech Publications, Switzerland., 14th International Symposium on Advances in Abrasive Technology, ISAAT 2011, 18 September 2011 through 21 September 2011, Stuttgart

Based on the review of current status and development of casting CNC manufacturing technology, this paper analyzes the characteristics and studies the mechanism of casting CNC cutting, along with the processing technique. A new casting CNC forming equipment is developed and successfully applied to the product development in automobile industry, mechanical industry and so on, which is regarded as a typical application case. Research indicates that patternless casting CNC manufacturing is a technical renovation compared to the traditional casting manufacturing, with traits of green, digital, flexibility, precision, rapidity. It’s applicable to the rapid manufacturing of metal casting either in single piece or small lot, and the pattern is unneeded. This new technology brings a promising application future in the automobile and mechanical equipment industries.

International Symposium on Advances of Abrasive Technology 2008 From 9/30/2008 To 10/3/2008., Awaji/Japan, available, unclassified, unlimited

An experimental study was undertaken to explore the conditions and performance on rough and finish grinding fir-tree root forms of turbine blades made of a nickel-based alloy using vitrified CBN wheels and water-based grinding fluid. This work was motivated by switching the grinding of fir-tree root forms from grinding with conventional abrasive wheels to vitrified CBN wheels for reducing overall production cost and enhancing productivity. Grinding experiments were conducted to measure grinding forces, power, surface roughness, and stress near the blade roots under various dressing and grinding conditions. Wheel re-dressing life in terms of the total number of good parts ground between dressing was tested with the condition producing the maximum material removal rate while satisfying preset part quality and process requirements. It was found that the maximum material removal rate achievable in rough grinding was restricted by the stress limit and the wheel re-dressing life was dominated by the radial wheel wear limit. The targeting part quality and process requirements were achieved. It was proved that vitrified CBN grinding process is feasible and very promising to machine fir-tree root forms., 17th International Symposium on Advances in Abrasive Technology, ISAAT 2014, 22 September 2014 through 25 September 2014

An experimental investigation is reported on the grinding of a titanium alloy using electroplated CBN wheels with water-based grinding fluid and wheel surface cleaning fluid applied at high pressures. This work was motivated by applying grinding fluid and wheel surface cleaning fluid both at high pressures for avoiding wheel loading, which is commonly seen in titanium alloy grinding. The objective is to explore the feasibility to grind titanium alloys with electroplated CBN wheels and high pressure wheel surface cleaning fluid for enhancing material removal rates. Straight surface grinding experiments were conducted on titanium alloy blocks in both shallow depth of cut and creep-feed modes. Grinding power, forces, and surface roughness were measured. Specific material removal rates of 8 mm2/s in shallow cut mode and 3 mm2/s at a depth of cut as high as 3 mm in creep-feed mode were achieved without burning and smearing of ground surfaces. It was showed that it is feasible to grind titanium alloys with electroplated CBN wheels at enhanced removal rates by applying grinding and wheel cleaning fluid at high pressures. © (2013) Trans Tech Publications, Switzerland., 16th International Symposium on Advances in Abrasive Technology, ISAAT 2013 and 17th Chinese Conference of Abrasive Technology, CCAT 2013, 23 September 2013 through 26 September 2013, Hangzhou

The Prognostic and Health Management (PHM) technology plays an important role in improving the security of aviation equipment, decreasing the life cycle cost and improving the logistics efficiency. According to the technique characteristics and the requirements on logistics of certain aviation gyroscope, we put forward to setting up the Integrated Grounds Health Management(IGHM) system for Aviation equipment using the historical failure information, current status information and current environmental information on the basis of integrated logistics information system in existence. On the basis of analyzing PHM technology, the system structure and key technologies to realize IGHM system are discussed in detail. Research shows that the IGHM system is open and universal, which is easy to upgrade and to apply on other logistics systems.

In this paper, gating and riser system of large complicated steel casting of the studied were designed firstly, then temperature and flow fields of this casting in a casting process were simulated and analyzed, and generation of shrinkage and porosity during solidification process was predicted. Finally, a more reasonable gating and riser system was obtained by analysis of simulation results. The research results in this paper have certain guiding significances for the determination of casting technology of large complicated steel castings in practical productions.

The material feeding in hot stamping is quite different from traditional cold stamping. This paper described some key issues of automatic high-temperature steel plate feeding, some analysis and studies were done about gripping method, clamping force, local and whole plate temperature drop in transferring process, and some ideas about robot manipulator' design were proposed with that.

Thrust bearing is a key component of large-scale water turbine. It closely relates to the efficiency of large-scale water turbines, and even determines whether the large-scale turbine can operate normally. With the development of the capacitance of water turbines, thrust bearing will develop to the direction of high speed and heavy load. The structure, strength, lubrication and the characteristic of heat radiation of large-scale thrust bearing were often researched in the past. To study the flow condition of the large-scale thrust bearing and analyze the load characteristics, CFD simulation was carried out on the model of thrust bearing. In this study, CFD method was used to simulate the internal flow field of the large-scale thrust bearing. The model researched was a thrust bearing for 1000MW water turbines. The diameter of the thrust bearing was over 5.8 meters, and the maximum thrust load of the bearing can reach to 60MN. The thin gap between the runner and the pad was usually neglected in the published CFD calculations of thrust bearing. But the thin gap was taken into account in this investigation. 1/12 of the model was used as the computational field and periodic boundary was used in the calculation. The standard κ-ε turbulence model was used to simulate the thrust bearing model, and the flow field in the thrust bearing was obtained. The thin gap between the runner and the pad is a wedge. The pressure and velocity distribution in the thrust bearing and thin gap was calculated respectively with conditions of different thin gaps and different rotational speeds of runner. After that, the relationship between carrying capacity and the size of clearance or the speed of the runner through analyzing the data has been obtained from the results of the calculation.

In order to study crack and springback phenomena of hot stamping parts, experiment researches were done through home-made hot stamping die. The following results were found: friction of plate and die was the main reason of crack during hot stamping, and reducing of friction was effective method to deal with crack; blank holder force (BHF) wasn't needed, and blank holder wasn't needed for hot stamping die.

In this paper, we fabricated an integrated circuit with silicon-on-diamond (SOD) structured wafer. The total-dose radiation characteristics of this SOD circuit was studied using a cobalt-60 radiation source. Comparison with the same circuit using bulk silicon wafer, showed that total-dose radiation introduces a small decrease in threshold voltage and drain current to the SOD circuit.

A distributed multiple warships bearings-only tracking algorithm is presented. By attribute association and space association, this algorithm can do the location association of multiple warships passive ESM sensors, it also adopts the time-varying sampling modified gain extended Kalman filter (MGEKF), and shipborne ESM equipment of multiple warships is used to distributed bearings-only tracking fusion of multiple maritime moving emitters. Computer simulation results proved that this algorithm can satisfy the needs of practical applications.

This paper concisely describes direct sealing of the hermetic sapphire-kovar millimeter-wave windows with active brazing alloy foil, and preliminary discusses the advantages of it.