A robust control algorithm is proposed to focus on the non-linearity and variables of the hydraulic press machine with the proportional vatve. The proposed robust controller does not need to design stable compensator ...A robust control algorithm is proposed to focus on the non-linearity and variables of the hydraulic press machine with the proportional vatve. The proposed robust controller does not need to design stable compensator in advance, which is simple in design and has large scope of uncertainty applications. The feedback gains of the proposed robust controller are small, so it is easily implemented in engineering applications. The theoretical and experimental research on the position and speed control of the hydraulic press machine is carried out. The control requirements of the hydraulic press machine during the working process are met in the position and speed at the same time. Experimental results show that the proposed controller has better robustness subject to load variables and adaptability of parameter variations of the hydraulic press machine with the proportional valve.展开更多
On April 26th, 2005, the 5th World Intellectual Property Day, the China Association for Standardization (CAS) held the press conference on CAS standard--Household Electric Double-driver Washing Machine in Diao Yu Tai ...On April 26th, 2005, the 5th World Intellectual Property Day, the China Association for Standardization (CAS) held the press conference on CAS standard--Household Electric Double-driver Washing Machine in Diao Yu Tai State Guest House in Beijing. The topic of the press conference was to Promote Technical Innovation, to Protect Intellectual Property and to Develop International Standard. Mr. Ma Lincong, General Secretary of CAS hosted the press conference.展开更多
AZ91 Mg alloy recycled by a solid state process and equal channel angular pressing(ECAP)exhibited a superior strength. The mechanical properties of AZ91 Mg alloy recycled from machined chips by extrusion at 623 K and ...AZ91 Mg alloy recycled by a solid state process and equal channel angular pressing(ECAP)exhibited a superior strength. The mechanical properties of AZ91 Mg alloy recycled from machined chips by extrusion at 623 K and ECAP at 573 K and 623 K were compared with those of the reference alloy which was produced from an as-received AZ91 Mg alloy block under the same conditions as the recycled alloy.The recycled specimens show a higher strength at room temperature than the reference alloy.The improvement of the tensile properties is attributed not only to the small grain size,but also to the dispersed oxide contaminants.展开更多
The present work discusses the experimental study on wire-cut electric discharge machining of hot-pressed boron carbide.The effects of machining parameters,such as pulse on time(TON),peak current(IP),flushing pressure...The present work discusses the experimental study on wire-cut electric discharge machining of hot-pressed boron carbide.The effects of machining parameters,such as pulse on time(TON),peak current(IP),flushing pressure(FP) and spark voltage on material removal rate(MRR)and surface roughness(R_a) of the material,have been evaluated.These parameters are found to have an effect on the surface integrity of boron carbide machined samples.Wear rate of brass wire increases with rise in input energy in machining of hot-pressed boron carbide.The surfaces of machined samples were examined using scanning electron microscopy(SEM).The influence of machining parameters on mechanism of MRR and R_a was described.It was demonstrated that higher TON and peak current deteriorate the surface finish of boron carbide samples and result in the formation of large craters,debris and micro cracks.The generation of spherical particles was noticed and it was attributed to surface tension of molten material.Macro-ridges were also observed on the surface due to protrusion of molten material at higher discharge energy levels.展开更多
The paper shows, how the quality of workpieces to be heat treated can be improved by using the technology of fixture-quenching. Different fixture systems, like fixed mandrel, expanding mandrel and lamellar mandrel are...The paper shows, how the quality of workpieces to be heat treated can be improved by using the technology of fixture-quenching. Different fixture systems, like fixed mandrel, expanding mandrel and lamellar mandrel are described. In the next section there is a comparison between manual operation of hardening machines vs. automated lines. Since there are applications for each, manual and fully automated hardening systems, HEESS has not only focused to develop automated lines, but also refined manual operated hardening machines (SP-Series). These take advantage of the latest technology, like for example quick tool change and PLC-control with workpiece parameter database. An overview over different machine types is given.展开更多
Fast response and stable torque output are crucial to the performance of electric screw presses. This paper describes the design of a direct torque control （DTC） system for speeding up torque response and reducing t...Fast response and stable torque output are crucial to the performance of electric screw presses. This paper describes the design of a direct torque control （DTC） system for speeding up torque response and reducing the starting current of electric screw presses and its application to the J58K series of numerical control electric screw presses with a dual-motor drive. The DTC drive system encompasses speed control, torque reference control, and switching frequency control. Comparison of the DTC dual-AC induction motor drive with corresponding AC servo motor drive showed that for the J58K-315 electric screw press, the DTC drive system attains a higher maximum speed （786 r/min） within a shorter time （1.13 s） during a 250 nun stroke and undergoes smaller rise in temperature （42.0 ℃） in the motor after running for 2 h at a 12 min-1 strike frequency than the AC servo motor drive does （751 r/min within 1.19 s, and 50.6 ℃ rise）. Moreover, the DTC AC induction motor drive, with no need for a tachometer or position encoder to feed back the speed or position of the motor shaft, enjoys increased reliability in a strong-shock work environment.展开更多
Press-finishing, a plastic deformation process, can be applied to raise surface precision of a workpiece. This paper introduces a new press-finishing technique for PCD (polycrystal diamond)tool that can press finishin...Press-finishing, a plastic deformation process, can be applied to raise surface precision of a workpiece. This paper introduces a new press-finishing technique for PCD (polycrystal diamond)tool that can press finishing the residual feed trails produced by the diamond tool on the machined surface. The experiments of press-finishing of Al-alloy have been performed on an instrument lathe with the press-finishing set-up with a PCD tool. Having investigated the correlation between the surface roughness (Rα)and parameters, such as press-finishing speed (v), feed (f),depth of press (αpp), PCD sphere diameter (Dsph), rigidity coefficient of spring (Ki) etc, the optimum parameters of technology.and their laws for the press-finishing of Al-alloy have been acquired. Some mechanisms for the press-finishing of Al-alloy with a PCD tool have been discussed. With appropriate parameters chosen, the sample of Al-alloy could be press-finished to a value of Ra =0.026μm from an initial roughness of Ra =0.5μm.展开更多
基金Shanghai Municipal Natural Science Foundation of China (No.06111003)
文摘A robust control algorithm is proposed to focus on the non-linearity and variables of the hydraulic press machine with the proportional vatve. The proposed robust controller does not need to design stable compensator in advance, which is simple in design and has large scope of uncertainty applications. The feedback gains of the proposed robust controller are small, so it is easily implemented in engineering applications. The theoretical and experimental research on the position and speed control of the hydraulic press machine is carried out. The control requirements of the hydraulic press machine during the working process are met in the position and speed at the same time. Experimental results show that the proposed controller has better robustness subject to load variables and adaptability of parameter variations of the hydraulic press machine with the proportional valve.
文摘On April 26th, 2005, the 5th World Intellectual Property Day, the China Association for Standardization (CAS) held the press conference on CAS standard--Household Electric Double-driver Washing Machine in Diao Yu Tai State Guest House in Beijing. The topic of the press conference was to Promote Technical Innovation, to Protect Intellectual Property and to Develop International Standard. Mr. Ma Lincong, General Secretary of CAS hosted the press conference.
基金Projects(50201005,50571031)supported by the National Natural Science Foundation of ChinaProject(2009DFA51830)supported by the Ministry of Science and Technology,China
文摘AZ91 Mg alloy recycled by a solid state process and equal channel angular pressing(ECAP)exhibited a superior strength. The mechanical properties of AZ91 Mg alloy recycled from machined chips by extrusion at 623 K and ECAP at 573 K and 623 K were compared with those of the reference alloy which was produced from an as-received AZ91 Mg alloy block under the same conditions as the recycled alloy.The recycled specimens show a higher strength at room temperature than the reference alloy.The improvement of the tensile properties is attributed not only to the small grain size,but also to the dispersed oxide contaminants.
文摘The present work discusses the experimental study on wire-cut electric discharge machining of hot-pressed boron carbide.The effects of machining parameters,such as pulse on time(TON),peak current(IP),flushing pressure(FP) and spark voltage on material removal rate(MRR)and surface roughness(R_a) of the material,have been evaluated.These parameters are found to have an effect on the surface integrity of boron carbide machined samples.Wear rate of brass wire increases with rise in input energy in machining of hot-pressed boron carbide.The surfaces of machined samples were examined using scanning electron microscopy(SEM).The influence of machining parameters on mechanism of MRR and R_a was described.It was demonstrated that higher TON and peak current deteriorate the surface finish of boron carbide samples and result in the formation of large craters,debris and micro cracks.The generation of spherical particles was noticed and it was attributed to surface tension of molten material.Macro-ridges were also observed on the surface due to protrusion of molten material at higher discharge energy levels.
文摘The paper shows, how the quality of workpieces to be heat treated can be improved by using the technology of fixture-quenching. Different fixture systems, like fixed mandrel, expanding mandrel and lamellar mandrel are described. In the next section there is a comparison between manual operation of hardening machines vs. automated lines. Since there are applications for each, manual and fully automated hardening systems, HEESS has not only focused to develop automated lines, but also refined manual operated hardening machines (SP-Series). These take advantage of the latest technology, like for example quick tool change and PLC-control with workpiece parameter database. An overview over different machine types is given.
基金Funded by the Natural Science Foundation of Hubei Province (No. 2004AA101E04)
文摘Fast response and stable torque output are crucial to the performance of electric screw presses. This paper describes the design of a direct torque control （DTC） system for speeding up torque response and reducing the starting current of electric screw presses and its application to the J58K series of numerical control electric screw presses with a dual-motor drive. The DTC drive system encompasses speed control, torque reference control, and switching frequency control. Comparison of the DTC dual-AC induction motor drive with corresponding AC servo motor drive showed that for the J58K-315 electric screw press, the DTC drive system attains a higher maximum speed （786 r/min） within a shorter time （1.13 s） during a 250 nun stroke and undergoes smaller rise in temperature （42.0 ℃） in the motor after running for 2 h at a 12 min-1 strike frequency than the AC servo motor drive does （751 r/min within 1.19 s, and 50.6 ℃ rise）. Moreover, the DTC AC induction motor drive, with no need for a tachometer or position encoder to feed back the speed or position of the motor shaft, enjoys increased reliability in a strong-shock work environment.
文摘Press-finishing, a plastic deformation process, can be applied to raise surface precision of a workpiece. This paper introduces a new press-finishing technique for PCD (polycrystal diamond)tool that can press finishing the residual feed trails produced by the diamond tool on the machined surface. The experiments of press-finishing of Al-alloy have been performed on an instrument lathe with the press-finishing set-up with a PCD tool. Having investigated the correlation between the surface roughness (Rα)and parameters, such as press-finishing speed (v), feed (f),depth of press (αpp), PCD sphere diameter (Dsph), rigidity coefficient of spring (Ki) etc, the optimum parameters of technology.and their laws for the press-finishing of Al-alloy have been acquired. Some mechanisms for the press-finishing of Al-alloy with a PCD tool have been discussed. With appropriate parameters chosen, the sample of Al-alloy could be press-finished to a value of Ra =0.026μm from an initial roughness of Ra =0.5μm.
