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(最好)不要某宝,不要个人,一定要选一个正规的润色机构——服务有保障,有售后,北京译顶科技做的不错,可以联系他们一下 终身满意。

297 评论

hsx1314520

毕业论文外文翻译:将外文参考文献翻译成中文版本。翻译要求:1、选定外文文献后先给指导老师看,得到老师的确认通过后方可翻译。2、选择外文翻译时一定选择外国作者写的文章,可从学校中知网或者外文数据库下载。3、外文翻译字数要求3000字以上,从外文文章起始处开始翻译,不允许从文章中间部分开始翻译,翻译必须结束于文章的一个大段落。参考文献是在学术研究过程中,对某一著作或论文的整体的参考或借鉴.征引过的文献在注释中已注明,不再出现于文后参考文献中。外文参考文献就是指论文是引用的文献原文是国外的,并非中国的。 原文就是指原作品,原件,即作者所写作品所用的语言。如莎士比亚的《罗密欧与朱丽叶》原文是英语。译文就是翻译过来的文字,如在中国也可以找到莎士比亚《罗密欧与朱丽叶》的中文版本,这个中文版本就称为译文。扩展资料:外文翻译需要注意的问题1、外文文献的出处不要翻译成中文,且写在中文译文的右上角(不是放在页眉处);会议要求:名称、地点、年份、卷(期),等 。2、作者姓名以及作者的工作单位也不用必须翻译。3、abstract翻译成“摘要”,不要翻译成“文章摘要”等其他词语。4、Key words翻译成“关键词” 。5、introduction 翻译成“引言”(不是导言)。6、各节的标号I、II等可以直接使用,不要再翻译成“第一部分”“第二部分”,等。 7、注意排版格式,都是单排版,行距1.25,字号小4号,等(按照格式要求)。8、里面的图可以拷贝粘贴,但要将图标、横纵指标的英文标注翻译成中文。 9、里面的公式、表不可以拷贝粘贴,要自己重新录入、重新画表格。

262 评论

沈阳宜家装饰

哇!你是哪个学校的?

305 评论

月想月乐

网上搜一大堆 我毕设就做的是模具

335 评论

不说客套话

Precision injection molding technology of progress Abstract: The polymer precision injection molding technology, impact on precision injection molding of factors, including the precision molds, injection molding machine control accuracy, precision injection process control and other computer control technology. These factors were discussed, and give the relevant solutions, finally introduces some advanced molding technology. Key words: precision injection; injection molding machine precision injection technology; Precision Injection Mold In recent years, as electronics, telecommunications, medical, automotive, and other industries of the rapid development of the high-precision plastic products, and high-performance requirements of growing precision molding technology to continue to progress, new technologies continue to emerge. Precision injection molding products not only require high dimensional accuracy, and low warpage, to write good, but there should also be excellent optical properties. Injection molding is the most important one of the plastic molding methods, including plastics plastics, injection, packing, cooling, and some of the basic process, thus affecting the precision injection molding of many factors. 1, precision molds To produce sophisticated products, precision molds is essential. Die Die in general, the accuracy of the temperature control, mold and die design precision manufacturing, use of plastic shrinkage rate impacts. 1.1 Precision Mold temperature control In general precision injection molding of parts, control mold temperature is to increase productivity. However mold temperature control for precision injection molding of great impact, it affects parts of the contraction, shape, crystallization, such as stress, hot and cold circuit design mold temperature distribution at the request reasonable, precise control accuracy, a die temperature of the best and Lengshuiji control. Mold temperature control and cooling time on the products and their impact on performance of the following factors: (1) melt plastic injection molds and a two-cycle time will be produced in the mold temperature difference fluctuations, and should therefore be to minimize the volatility differential peak. (2) the heat transfer Die Die Die heat through the concrete and die in the transfer out of the media, mold is changed, the media control is the key, the general import and export of its cooling water temperature difference is less than 1 ℃ Application of theory to calculate the average temperature, which can guarantee the stability of heat transfer. Media flow and heat transfer are interlinked, mould surface temperature can be used to control the media flow sensor to compensate for environmental temperature changes caused by mold temperature changes. (3) To enable stable Die Die by the heat absorption and dissemination of balance, the injection molding machine to melt injection to strictly maintain a stable temperature. Die surrounding temperature on the mold had a great impact on the general will be affected to die within the melt convection coefficient of change, so the best set up in the mold surface temperature sensor, die at any time observation of the surface temperature, and keep it stable. (4) changes in the efficiency of heat exchange with mold after a long time in the cooling water pipes and Youban appears in the scale, then the interface to reduce the thermal conductivity should furring timely clearance. 1.2 Precision Die Design and Manufacture Die design is good or bad is to ensure the dimensional accuracy of plastic parts premise, in order to enhance the accuracy of precision injection mold, in the process of designing a computer-aided analysis is necessary, especially for gating system and the flow of heat-conditioning systems mold temperature distribution the analysis. Applications should be as much as possible the use of simulation software and close to the actual loading conditions to melt in the mold simulation analysis in the pouring, cooling, and other non-steady-state process. Die manufacturing quality assurance plastic parts Size is the key to accuracy, precision die is the main characteristic of the manufacturing and assembly operations in addition to polishing, are no manual processing. Die general machining and manual processing ratio is about 6:4 to 7:3, and the machining precision molds and manual processing ratio of 9:1. Die materials and heat treatment is the protection of precision molds in the molding process, the die temperature in the state, which even the mould parts tempered by low temperature, high temperature melt production and will repeat parts tempering而使lower hardness, Consideration should also be given retained austenite caused by the volume expansion. Therefore general tempering temperature should be at least molding processing, more than double the die temperature and low-temperature processing is carried out properly in order to eliminate residual austenite. On the high-precision products for Molding precision parts, assembly accumulated precision die in the direction of the accuracy of the sub-surface as well as the parallel degree should achieve micron level. Mold should have sufficient strength, stiffness and abrasion resistance, in the injection molding deformation under the pressure of hard wear. To achieve the above processing can be three-dimensional precision machining centers, CNC machine tool and application of CAD / CAM / CAE and other new technologies. 1.3 precision molds design shrinkage rate of use Thermoplastic plastic molding shrinkage volatile, to mold design, identify and control products cavity size dimensional accuracy difficult. Therefore, in plastic mold design should understand the characteristics and contraction caused by the shape of the parts of the difference in the rate of contraction site, and then use the necessary compensation measures. On the high-precision plastic parts can be manufactured in the design before simple mold, measured molding to the various parts of the actual shrinkage rate, this can greatly enhance the dimensional accuracy of parts. 1.4, the design of precision molds gate Gate type, size, location and quantity of all affected parts dimensional accuracy. At the gate of the jet, but the effects of poor feeding, thick-walled parts do not apply. Gate position and the flow of impact melt flow distance, the longer the process of the greater contraction. Multi-gate process can be shortened, but increasing weld marks. Gate parts should be designed in accordance with the size and the choice of materials and the use of software to help finalize practical experience. 2, the best precision injection molding process parameters set Choose the best molding process parameters to reduce plastic shrinkage rate. Plastic is that the contraction of the heat shrinkable plastic, elastic recovery, plastic deformation, contraction after contraction and a comprehensive reflection of aging, usually caused by absorbent material or molecular chain rearrangement caused, the specific performance linear shrinkage rate and volume contraction rate changes in value of common contraction said. Thermoplastic plastic injection molding products shrinkage volatile, particularly for crystalline plastics injection molding products even more obvious, and not only depend on the degree of crystallinity due to the chemical structure, but also by the process of cooling parameters (cooling rate, the melt temperature, mold temperature , product thickness) the impact of the mold cavity size and design determine the size precision control products and difficulties, there is an urgent need to be aware of parameters on the injection molding of plastic shrinkage rate of the impact of the law. Part of the difference in thickness is generally believed that the two factors: First, high-pressure melt the mold cavity caused minor deformation of a die when the elastic modulus material after the expansion. Generally speaking, quality control and accuracy can be very good dimensional accuracy, and at a higher temperature, mold low melt viscosity, viscosity smaller gradient, in a certain screw back pressure, the quality of precision parts can be accurately controlled. But for liquid crystal polymer (LCP), it just needs a lower mold temperature, it is because cold LCP case will be promptly after cooling amorphous. LCP have low melting heat and orderly structure of the state, in the liquid crystalline state to change between crystalline solid, smaller changes, when fully cooling, the liquid - solid transition is almost complete in an instant. Die in the colder, when a cavity, the cavity material and the bulk of gate has been cured, it is very difficult stage compression added melt, thus parts and the size of the cavity size of the deformation is very close. Plastic amorphous than crystalline plastics low shrinkage with a mixture of contraction rate of low-polymer materials, elastomers at the same time as the increase of the content, materials shrinkage rate decrease. The enhanced or plastic filling, heat capacity decrease stiffness increased significantly reduce shrinkage and fiber filler content or higher, the smaller the rate of contraction. Crystalline precision plastic products also affected by pressure. As pressure crystallization of the role of injection pressure (P1), the packing pressure (P2) and the feeding pressure (P3) to speed up the crystallization process, crystallization of the P1, P2, P3, the increase in upward trend. For P1, the pressure to improve the crystallization of the degree of crystallinity, the contraction rate of increase rose P2 and P3, on the one hand because of the degree of crystallinity increased shrinkage rate increase, on the other hand increased to P2 more pressure to melt, the type cavity has been fully compacted plastic; P3-feed increased to increase, and effectively prevent reflux is conducive to reducing shrinkage. Therefore, the plastic parts of the shrinkage rate is the result of both, with the shrinkage of P1, P2, P3, the first increases and then decreases increased. Precision plastic parts requires not only a stable size tolerances, but also requires strict mechanical properties. These characteristics mainly depend on the cooling phase of the melt in the heat - mechanical role of the historical process. Mold temperature and cooling time on the quality of products and have a direct impact on productivity. Study found that, given the die temperature, the dimensional accuracy of products with the cooling time is not the extension has been significantly improved, and only in a certain period of time, after a prominent role. In general cooling process in such a critical point in time there are two cooling, cooling time in the first point although production products also higher accuracy, but it is not the most stable state, and the second point-in-time cooling cooling relatively long time, However, the products enable the most stable state. 3, using precision injection molding machine to replace conventional injection molding machine Precision injection molding machine generally larger injection power, in addition to such injection pressure and injection to meet the requirements in terms of speed, power itself will be on the injection products improve the accuracy of a certain role. Precision injection molding machine control systems generally have high control precision, it is requested by the products themselves. High accuracy can be guaranteed control of injection process parameters has good accuracy, precision products in order to avoid fluctuations due process parameters change. Therefore precision injection molding machine generally of the injection, injection pressure, injection rate and pressure-pressure, back-pressure and screw speed process parameters such as a multi-level feedback control. Precision Injection requirements of its modulus system has sufficient rigidity, accuracy or products will be a model for the elastic deformation decreased. Second-Die-Die of the system must be able to accurately control the size, or too large or too small a model of precision products will have an adverse impact. So in the design, it should be considered Die rigidity, stiffness, as well as a model system in order to accurately control the size of the precision products, especially flat-panel thin-wall products. When Die larger, must-oriented column deflection check. Precision injection molding machine also must be able to work in the hydraulic circuit precise temperature control, work to prevent the oil due to temperature changes caused viscosity and flow changes, further injection process parameters leading to fluctuations而使products would lose their accuracy. 3.1 parts molding cycle time consistency General typical injection molding machine with three modes: manual, semi-automatic and fully automatic. As the influence of various factors, each of the previous two models molding cycle time may be different, it would affect the temperature and materials to die in the Liaodong stay, thereby affecting the accuracy of parts, in precision Molding should try to use the automatic mode. 3.2 precision injection molding machine screw temperature control and the design of new Injection Molding Machine cylinder automatic thermostat on the cycle of opening and customs led to the Liaodong, melting material density and viscosity changes, thereby affecting the quality and dimensional accuracy of parts of the cyclical fluctuations in the injection molding machine nozzle close to Die Therefore, the temperature of the nozzle molded parts also have a significant impact on. Modern injection molding machine equipped with a special process control software to control temperature fluctuation, which is proportional integral differential (P ID) control. At least from the barrel temperature difference galvanic point perspective, the P ID parameter optimization can completely eliminate temperature fluctuations. To the quality and stability of the plastic parts, plastics injection molding machine unit is very important. To the plastics unit is an important standard to judge: injection volume, plastics rate, injection rate, the polymers in the plastics unit at the time. As the quality of plastic parts for the dimensional accuracy error of a very important impact, and it should be precise injection control of the injection molding machine. Improve measurement precision injection molding machine of the most effective ways is to use technology to achieve the smallest screw diameter, especially for the light parts especially. The measurement of the relative screw length and the overall length of screw smaller, in the plastics materials unit at the time also become shorter. Screw thread is similar to widening the materials can be avoided stay longer so that the screw and stable operation. Lo deep groove width than correspondingly smaller, which create a lot of engineering plastics parts of the small diameter screw particularly effective. Melt homogeneity and are not small compression ratio decreases, it is because from the very shallow groove Lo caused very strong result of the shear rate. Feeding the difficulty of the design, it must ensure that all aggregates can be fed into evenly. Considering the need to shorter cycles, plastics rate must also be big enough, in the design of the feed must be effectively resolved the contradiction between. In addition, if adopted by a two-stage injection screw to achieve precise control injection error, which requires the measurement of the melt through spherical valve detected by injection to injection molding machine in the Detroit injection molding machine. Before microprocessor controlled by the injection molding process can not be obtained through injection precision voltage comparator has been successfully resolved. Voltage comparator allows Transmitter and other sensitive came with the very precise voltage signal passed, and when the set point appears to be following the true value of a timely signal immediately transmitted to the microprocessor control of the order, by order of the cycle of operational procedures Asynchronous from time to time through a direct transfer of the signal process to eliminate, greatly improving the control accuracy. 4, precision molding technology 4.1 in the mold injection-compression molding applications (ICM) technology ICM technology is the means to open a certain distance die under the conditions of the beginning injection, injection to a certain amount, the mold cavity beginning of the closure of the melt compression, injection mold completely closed at the termination, and then packing, cooling until the removal products. Through injection-compression molding of compression products to compaction, making products on the surface of uniform pressure distribution, the compaction products such size high accuracy and stability, small deformation. It is in the mould open circumstances melt into the cavity and, therefore, mobile channel, for the low pressure injection molding, and reduce or eliminate the pressure caused by the resin-molecular orientation of the stress and products, which improve products, dimensional stability. ICM technology and flexible control capability than the injection mould has greatly improved. Therefore use of this technology can produce more precision parts, especially the high-precision cylindrical-shaped parts. 4.2 high-speed injection molding High-speed injection molding method of filling melts faster rate than the traditional 10 to 100 times, melt in the mold cavity to produce high shear flow, decrease viscosity, injection speed, slow down plastic surface hardening, thus improving thin Forming products wall thickness limit, inhibit excessive molding pressure, as well as because of the low-voltage mobile mode, the products reduce stress. The thin-wall precision products, we can use the injection screw at the forward from the melt energy absorption in the screw after the cessation of movement through the expansion of high-speed melt full cavity to achieve. 4.3 no-pressure injection molding No-pressure injection molding technology refers to the plastic melt high-speed, high-pressure filling into the mold, and then close in the nozzle needle to melt the plastic mold cavity products automatically compensate for different parts of the contract, such products can be greatly reduced warpage. However, this method requires prior estimate packing contraction added, hence the need for the injection of a higher cavity pressure value, and we need clamping force also high. 4.4 Other Intelligent Control Technology Precision injection molding processing conditions in the process of continuous monitoring and implementation of precise control is very important. With the development of computer technology, computerized injection molding has been widely used. Among them, statistical process control (SPC), P ID technology, fuzzy logic control (FCC), network control center (NNC) method and the processing model based on the reverse of the backbone network size control. 5. Conclusion On the high-precision plastic products, and high-performance requirements of the growing precision injection molding technology is the impetus for moving forward, people on the principle of precision injection molding, the constant deepening of understanding of precision injection molding technology is the basis for progress. With new materials, new processes and new equipment has emerged, particularly in the plastics processing computer is the wide application of the precision injection technology to create good conditions. As long as a reasonable use of these technologies, we will be able to produce sophisticated products.

285 评论

lisabaobao99

Punching die has been widely used in industrial production.In the traditional industrial production,the worker work very hard,and there are too much work,so the efficiency is low.With the development of the science and technology nowadays,the use of punching die in the industial production gain more attention, and be used in the industrial production more and more.Self-acting feed technology of punching die is also used in production, punching die could increase the efficience of production and could alleviate the work burden,so it has significant meaning in technologic progress and economic value.The article mainly discussed the classification,feature and the developmental direction of the pnnching technology. Elaborated the punching components formation principle, the basic dies structure and the rate process and the principle of design; and designed some conventional punching die:the die for big diameter three direction pipe which solved the problom of traditional machining,the drawing and punching compound die with float punch-matrix,the drawing and cutting compound dies with unaltered press,the compound die for the back bowl of the noise keeper,the design of the compound die which could produce two workpieces in one punching,the bending die for the ring shape part ,the bending die which used the gemel ,automate loading die for cutting, the drawing,punching and burring compound dies with sliding automated loading,the punching die for the long pipe with two row of hole,the drawing die for the square box shape workpiece and the burring die for the box shape workpiece.The punching dies that utilized the feature of the normal punch shaped the workpiece in the room temperature,and its efficiency and economic situation is excellent.The dies here discussed can be easily made,conveniently used, and safely operated.And it could be used as the reference in the large scale production of similar workpieces.CAD and CAM are widely applied in mould design and mould making. CAD allows you to draw a model on screen, then view it from every angle using 3-D animation and, finally, to test it by introducing various parameters into the digital simulation models(pressure, temperature, impact, etc.) CAM, on the other hand, allows you to control the manufacturing quality. The advantages of these computer technologies are legion: shorter design times(modifications can be made at the speed of the computer),lower cost, faster manufacturing, etc. This new approach also allows shorter production runs, and to make last-minute changes to the mould for a particular part. Finally, also, these new processes can be used to make complex parts.Computer-Aided Design(CAD)of MouldTraditionally, the creation of drawings of mould tools has been a time-consuming task that is not part of the creative process. Drawings are an organizational necessity rather than a desired part of the process.Computer-Aided Design(CAD) means using the computer and peripheral devices to simplify and enhance the design process .CAD systems offer an efficient means of design, and can be used to create inspection programs when used in conjunction with coordinate measuring machines and other inspection equipment.CAD data also can play a critical role in selecting process sequence.A CAD system consists of three basic components: hardware, software, users. The hardware components of a typical CAD system include a processor, a system display, a keyboard, a digitizer, and a plotter. The software component of a CAD system consists of the programs which allow it to perform design and drafting functions. The user is the tool designer who uses the hardware and software to perform the design process.Based on the 3-D data of the product, the core and cavity have to be designed first. Usually the designer begins with a preliminary part design, which means the work around the core and the cavity could change. Modern CAD systems can support this with calculating a split line for a defined draft direction, splitting the part in the core and cavity side and generating the run-off or shut-off surfaces. After the calculation of the optimal draft of the part, the position and direction of the cavity, slides and inserts have to be defined .Then in the conceptual stage, the positions and the geometry of the mould components---such as slides, ejection system, etc.----are roughly defined. With this information, the size and thickness of the plates can be defined and the corresponding standard mould can be chosen from the standard catalog. If no standard mould fits these needs, the standard mould that comes nearest to the requirements is chosen and changed accordingly---by adjusting the constraints and parameters so that any number of plates with any size can be used in the mould. Detailing the functional components and adding the standard components complete the mould(Fig.23.1).This all happens in 3-D. Moreover, the mould system provides functions for the checking, modifying and detailing of the part .Already in this early stage, drawings and bill of materials can be created automatically.Through the use of 3-D and the intelligence of the mould design system, typical 2-D mistakes---such as a collision between cooling and components/cavities or the wrong position of a hole---can be eliminated at the beginning. At any stage a bill of materials and drawings can be created---allowing the material to be ordered on time and always having an actual document to discuss with the customer or a bid for a mould base manufacturer.The use of a special 3-D mould design system can shorten development cycles, improve mould quality, enhance teamwork and free the designer from tedious routine work. The economical success, however, is highly dependent upon the organization of the workflow. The development cycles can be shortened only when organizational and personnel measures are taken. The part design, mould design, electric design and mould manufacturing departments have no consistently work together in a tight relationship.Computer-Aided Manufacturing(CAM)of MouldOne way to reduce the cost of manufacturing and reduce lead-time is by setting up a manufacturing system that uses equipment and personnel to their fullest potential. The foundation for this type of manufacturing system is the use of CAD data to help in making key process decisions that ultimately improve machining precision and reduce non-productive time. This is called as computer -aided manufacturing (CAM).The objective of CAM is to produce, if possible, sections of a mould without intermediate steps by initiating machining operations from the computer workstation.With a good CAM system , automation does not just occur within individual features. Automation of machining processes also occurs between all of the features that make up a part, resulting in tool-path optimization. As you create features ,the CAM system constructs a process plan for you .Operations are ordered based on a system analysis to reduce tool changes and the number of tools used.On the CAM side, the trend is toward newer technologies and processes such as milling to support the manufacturing of high-precision injection moulds with 3-D structures and high surface qualities. CAM software will continue to add to the depth and breadth of the machining intelligence inherent in the software until the CNC programming process becomes completely automatic. This is especially true for advanced multifunction machine tools that require a more flexible combination of machining operations. CAM software will continue to automate more and more of manufacturing's redundant work that can be handled faster and more accurately by computers , while retaining the control that machinists need.With the emphasis in the mould making industry today on producing moulds in the most efficient manner while still maintaining quality, moludmakers need to keep up with the latest software technologies-packages that will allow them to program and cut complex moulds quickly so that mould production time can be reduced. In a nutshell, the industry is moving toward improving the quality of data exchange between CAD and CAM as well as CAM to the CNC, and CAM software is becoming more "intelligent" as it relates to machining processes_resulting in reduction in both cycle time and overall machining time. Five-axis machining also is emerging as a "must-have" on the shop floor-especially when dealing with deep cavities.And with the introduction of electronic data processing(EDP)into the mould making industry, new opportunities have arisenin mould-making to shorten production time, improve cost efficiencies and higher quality.

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