Recent Patents on Mechanical Engineering - Volume 12, Issue 1, 2019

Background: Short carbon fibre reinforced epoxy composites have many advantages such as high strength-to-weight ratio, corrosion resistance, low cost, short fabrication time and easy manufacturing. Researches on the mechanical performance of the composites are mainly carried out by means of experimental techniques and numerical calculation. Objective: The study aims to report the latest progress in the studies of mechanical properties of short carbon fibre reinforced epoxy composites. Methods: Based on recently published patents and journal papers, the experimental studies of short carbon fibre reinforced epoxy composites are reviewed and the effects of short carbon fibre on the mechanical properties of the composites are discussed. Numerical studies using representative volume element in simulating macroscopic mechanical properties of the short fibre reinforced composites are also reviewed. Finally, future research of short carbon fibre reinforced epoxy composites is proposed. Results: Experimental techniques, experimental results and numerical simulating methods are discussed. Conclusion: Mechanical properties of epoxy can be improved by adding short carbon fibres. Fiber surface treatment and matrix modification are effective in enhancing interfacial adhesion between fiber and matrix, and as a result, better mechanical performance is achieved. Compared to the studies on equivalent mechanical properties of the composites, researches on the micro-mechanism of interaction between fiber and matrix are still in infancy due to the complexity of both the internal structure and reinforcing mechanism.

Background: Electromachining technology is widely used in micro manufacturing of microshafts, micro-holes, micro-grooves and other micro three-dimensional structures, which contributes to the giant demands for tool electrode. More and more attention has been paid on the electromachining of microelectrodes. Objective: To meet the increasing requirement of machining quality and machining efficiency of electromachining of microelectrodes, the processing devices and processing methods of electromachining of microelectrodes are continuously improved. Methods: This paper reviews various current representative patents related to the processing devices and processing methods of electromachining of microelectrodes. Results: Through comparing different kinds of processing devices and processing methods of electromachining of microelectrodes, the main problems in the current development such as machining efficiency and machining quality of electromachining of micro electrode are concluded and analyzed, and the future development trends of processing devices and processing methods of electromachining of microelectrodes are discussed. Conclusion: The optimization of processing devices and processing methods of electromachining of microelectrodes is advantageous for solving the problems of machining efficiency and machining quality, and more relevant patents will be invented in the future.

Background: Additive Manufacturing (AM) enables the accurate fabrication of designed parts in a short time without the need for specific molds and tools. Although polymers are the most widely used raw materials for AM, the products printed by them are inherently weak, unable to sustain large tension or bending stresses. A need for the manufacturing of fiber reinforced composites, especially continuous fiber as reinforcement, has attracted great attention in recent years. Objective: Identifying the progress of the AM of continuous carbon fiber reinforced composites over time and therefore establishing a foundation on which current research can be based. Methods: Elaborating the most related patents regarding the AM techniques for fabricating continuous fiber reinforced composites in the top three institutions, including Markforged company, Xi’an Jiaotong University and President and Fellows of Harvard College. Results: The recent patents in AM of continuous fiber reinforced composites are classified into two aspects: patents related to novel technique methods and patents related to novel structures. The current issues and future development of AM-based composites are given. Conclusion: New structures and techniques have been introduced into conventional 3D printers to enable the printing of continuous fiber reinforced composites. However, until now, Markforged is the only company commercializing the fabrication of this kind of composites based on AM technique. Numerous challenges and issues need to be solved so that AM of continuous fiber reinforced composites can be a new manufacturing method.

Background: With the improvement of environment protection awareness, human beings have gradually become aware of that the plastic products, waste are harmful to the human living environment. Therefore, research and application of biodegradable materials that do not rely on petroleum resources have become hot topics. Researchers have accelerated the development and promotion of plant fiber because they are good flexibility, relatively rough surface and biodegradable. Objective: The development of plant fiber composites is reviewed, including composition ratio, interfacial modification, processing technology, and the effects of these technologies on the properties of plant fiber composites. Methods: The paper reviews various patents and research developments about plant fiber composite materials. It also analyzes the advantages and disadvantages of various patents and technologies from the aspects of biodegradable ability, mechanical properties, dispersing performance, processing properties, cost, and so on. Results: The component proportion, interface modification, and processing technology of plant fiber composite materials are prospected to improve the quality and application of the plant fiber composite materials in the future development. Conclusion: The considerable attention has been paid on the technology of biodegradable plant fiber composite. The recent patents and technologies have shown us a wider application in biodegradable plant fiber composite. The problems how to improve the mechanical properties of plant fibers, the dispersion properties of plant fibers and resins, and the processing properties of composite materials, will need more and more methods and equipment to solve or simplify.

Background: Wheelchair mounted robotic arm is a typical assistive robot, which is widely used to help the elders and the disabled to complete the activities of daily life. But limited by the restrictions of the users’ athletic ability and cognitive ability, how to flexibly manipulate such robot is still a problem in front of them. The human-computer interaction technology is the core technology of the robot. Its performance directly affects the user's acceptability, satisfaction and promotion of intelligent wheelchairs. Objective: The study aims to give a general summary of recent human-robot interface of wheelchair mounted robotic arm and introduce their respective characteristics. Methods: Based on various patents and research developments about the human-robot interface of the assistive robot at home and abroad, this paper puts forward the basic principle of designing the humanrobot interaction mode, divides the man-robot interface into two categories based on the perspective of user control robot arm, and describes in detail, the typical human-robot interface and its related characteristics contained in each classification. Results: The development trends of the human-robot interface in future are predicted, so as to provide some research reference for the related scientific researchers. Conclusion: Wheelchair mounted robotic arm has important practical significance. Further improvements are needed in the design of the human-robot interface. It can effectively improve the operation performance of the WMRA, and take full advantage of the user’s existing movement ability to meet the requirement of dominating the control process. Furthermore, these improvements in the human-robot interface will allow more and more users to accept the WMRA, manipulate the WMRA, and enjoy improvements in the quality of their life for these assistive robots.

Background: With the development of natural gas and shale gas worldwide, the consumption of gas will continue to increase in the future. Natural gas is flammable and explosive, and the exhaust gas produced during the combustion of natural gas in boiler burners is one of the main sources of NOx in the air. Objective: This paper introduces patents and researches of natural gas boiler burners to improve the safety of natural gas boiler burners and reduce the emission of nitrogen oxides. Methods: In summarizing the existing boiler burner for natural gas, this paper introduces three new patents of natural gas boiler burner: the low-nitrogen burner, the energy-saving leakage-detecting burner and the small boiler burner. Results: The low-nitrogen burner identifies the fixed control of gas flow, enhances the gas flow's antiinterference ability, and achieves a relatively accurate ratio of the fuel-air flow. The energy-saving leakage-detecting burner enhances the natural gas and air flow stability and improves combustion efficiency and the safety and reliability by optimizing the ratio of natural gas to air. The small boiler burner improves the safety and reliability of the natural gas boiler burner, prolongs the service life of the igniter, and makes up for the shortcomings of high stability in the gas pressure. Conclusion: On the basis of ensuring the safety of the burner, the low-nitrogen transformation of the boiler burner is as energy-efficient as possible in order to maximize the advantages of natural gas resources.

Background: Machining is an important method for manufacturing parts. It is characterized by high cutting speed with a considerable influence of high-frequency vibration. Various relevant papers and patents have studied vibration transmission and isolation in the machining process. Objective: To investigate vibration transmission and isolation in the machining process, and simplify the cutting process of a machine tool. Methods: Firstly single-layer and double-layer vibration isolation models are established, the substructure matrix analysis method is adopted and the vibration power flow transmission characteristics of double-layer vibration isolation system under complex excitation are analyzed. Secondly, the optimal control strategy based on the minimum power flow inputted into the base is proposed. Then the control effect of the active actuator under different installation modes is analysed and compared. Results: It has been proved that low-frequency coupling is characterized by the rigid mode of the workpiece or the grinding wheel when cutting, whereas high-frequency coupling exhibits the dynamic characteristics of the machine tool bed. A good vibration isolation effect can be achieved for three types of installation modes in a double-layer vibration isolation system, and only the actuators installed between the vibration source and the middle mass exhibit the best control effect. Conclusion: The vibration isolation model has been established and the optimal installation mode of the actuator in the double-layer vibration isolation system has been found. And the paper provides a reference for the study of vibration transmission, control of machine tools and the elimination of grinding chatter.

Background: The nutation drive is being extensively interested due to its ability to achieve a high reduction ratio with a compact structure and the potential for low vibration, high efficiency and design flexibility, while many problems including the difficulty to process the inner bevel gear and less number of teeth in engagement have restricted the development of it. Objective: The purpose of this paper was to propose and analyze a patent about a new nutation drive with movable taper teeth, in which rolling substitutes tooth meshing, the bevel gear processing difficulties and other issues can be avoided. Methods: Based on geometry transformation and the meshing theory, the meshing surface and mathematical equations of the tooth profiles for both the stator and the rotor were developed, enabling the pressure angle to be analyzed in detail. Results: These mathematical models were then verified by kinematics simulation and interference detection in a virtual simulation environment. Further, the verification of the working process of the nutation drive showed that all the simulation values were approximate to the desired value of the designed nutation drive. Conclusion: The study proposed an approach for generating stator and rotor in the nutation drive to provide superior performance in terms of load sharing and contact intensity. Simulation and manufacturing technology of the mechanism were carried out to prove the theoretical equations. The prototype of it has been illustrated to verify the theory and the computer simulation model at the end of this paper.