快速模具技术在摩托车齿轮箱盖制造中的应用

介绍了将快速模具技术应用于摩托车齿轮箱盖零件制造的过程,研究了纸基砂型铸造模具制作的技术方案和实施步骤,并对其中的一些技术关键进行了深入的探讨.结果表明,利用快速模具技术可以取代传统的木模制作工艺,此技术具有制作周期短、成本低、尺寸精度高的特点,适用于产品开发过程中小批量样件的快速制造.     

High speed milling, electro discharge machining and direct metal laser sintering: A method to optimize these processes in hybrid rapid tooling

Prototype injection moulds for plastic parts must face two constraints: be designed and manufactured as quickly as possible and have a short lead time. Moreover, moulds have to evolve in the same way as the part does, to provide either a new functionality or a variant of this part. The current approach is based on a multi component tooling (hybrid rapid tooling) in order to more easily manufacture each component of the mould and to have a greater reactivity to each product evolution. In this paper, we propose a method to manufacture the mould in multi components. This approach is based on process capability criteria (i.e. topological and geometrical criteria). An industrial example is presented. We will focus on the choice between three processes mainly used in hybrid rapid tooling: high speed machining (HSM), electro discharging machining (EDM) and direct metal laser sintering (DMLS).     

Research on Injection Mould Intelligent Cost Estimation System and Key Technologies

The manufacturing cost of injection-moulded parts is mainly decided by the cost of the injection mould. Thus if we can ascertain the cost of the injection mould as early as possible, it will be a great contribution to an injection mould cost evaluation system and research on the economics of injected part manufacture. In this paper, related work on injection mould cost estimation has been discussed. A case-based reasoning (CBR) approach is used for evaluating the manufacturing cost of injection moulds. Case indexing, neural network-based case retrieval, knowledge-abundant case-adaptation and knowledge-absent case-adaptation strategies, and case learning are all considered. A comprehensive cost model including mould manufacturing costs, tax costs and general administrative costs is also discussed. The model is valuable for the price estimation of injection moulds. The application of the system is illustrated with an example.     

<Emphasis Type="Italic">Rapid Moulding Using Epoxy Tooling Resin</Emphasis>

Rapid prototyping (RP) is fast becoming a standard tool in today’s product design and manufacturing environment. Significant benefits in terms of lead time and cost savings have been reported with the use of RP technology. However, these benefits can be derived only during the design and planning stages of a new product where RP parts are produced in small quantities for design evaluation, form fitting, and marketing analysis. The high cost of raw material stock used in current RP systems makes them economically unsuitable even for small-batch production during the product evaluation and manufacturing stages. Further to this, the difference between the mechanical and physical properties of RP and traditional manufacturing materials limits the functionality of RP end products. Rapid tooling (RT) technology has opened up new cost-effective solutions for small-batch production. In this paper, a technique using a rapid soft-tooling approach, namely, aluminium filled epoxy resin tooling for injection mould preparation is successfully explored. An aluminium filled epoxy resin mould is evaluated and the characteristics of the injection-moulded end products are presented.     

Build orientation determination of multi-feature mechanical parts in selective laser melting via multi-objective decision making

Selective laser melting (SLM) is a unique additive manufacturing (AM) category that can be used to manufacture mechanical parts. It has been widely used in aerospace and automotive using metal or alloy powder. The build orientation is crucial in AM because it affects the as-built part, including its part accuracy, surface roughness, support structure, and build time and cost. A mechanical part is usually composed of multiple surface features. The surface features carry the production and design knowledge, which can be utilized in SLM fabrication. This study proposes a method to determine the build orientation of multi-feature mechanical parts (MFMPs) in SLM. First, the surface features of an MFMP are recognized and grouped for formulating the particular optimization objectives. Second, the estimation models of involved optimization objectives are established, and a set of alternative build orientations (ABOs) is further obtained by many-objective optimization. Lastly, a multi-objective decision making method integrated by the technique for order of preference by similarity to the ideal solution and cosine similarity measure is presented to select an optimal build orientation from those ABOs. The weights of the feature groups and considered objectives are achieved by a fuzzy analytical hierarchy process. Two case studies are reported to validate the proposed method with numerical results, and the effectiveness comparison is presented. Physical manufacturing is conducted to prove the performance of the proposed method. The measured average sampling surface roughness of the most crucial feature of the bracket in the original orientation and the orientations obtained by the weighted sum model and the proposed method are 15.82, 10.84, and 10.62 μm, respectively. The numerical and physical validation results demonstrate that the proposed method is desirable to determine the build orientations of MFMPs with competitive results in SLM.     

<Emphasis Type="Bold">A Rapid Manufacturing Method for Water-Saving Emitters for Crop Irrigation Based on Rapid Prototyping and Manufacturing</Emphasis>

In order to build the complex built-in labyrinth design of an emitter which is a key element in water-saving devices, rapid prototyping and manufacturing (RP&M) is used to design the emitters and to manufacture corresponding rapid tooling (RT). Detailed CAD design of the emitter, CAD process design, and the generation of RT process modelling of the emitter have been carried out using parameterised design. Prototypes have been built using RP techniques to perform the rapid verification and modification of the emitter design; rapid tooling (RT) for the emitter has been fabricated using a metal spraying process to carry out trial-production. Finally, with the fabrication ofa precision mould as the basis, emitter mould design and manufacturing have been completed. As a result, the integration of design/verification/manufacturing of a mould and its products is realised.     

An economic analysis comparing the cost feasibility of replacing injection molding processes with emerging additive manufacturing techniques

Additive manufacturing (AM) has proliferated in recent years and is displacing traditional manufacturing methods in numerous applications due to improvements in process efficiencies and cost reductions related to the evolving AM processes. This study explores the cost structure and break-even points of AM versus traditional methods. The comparative analysis examined the cost requirements of AM versus injection molding to manufacture various lot sizes of parts. Break-even points based on lot sizes and the relationship to the overall cost structure were also calculated. This research concludes that break-even points may be calculated based on part mass, density, and lot size.     

快速模具技术在现代制造技术中的应用

快速模具技术随着工业化生产的发展而产生,一直受到模具界的广泛重视。文中概括地介绍了快速模具技术在现代制造技术中的应用,对于快速模具技术的应用与发展,具有重要的现实意义。     

Rapid tooling aided by reverse engineering to manufacture EDM electrodes

The present work deals with the application of indirect rapid tooling (RT) technology to manufacture electrical discharge machining (EDM) copper electrodes from investment casting, with wax prototypes made by ThermoJet 3D printing, a rapid prototyping (RP) technique. The reverse engineering (RE) method is utilised to transform the point cloud data of an object surface, obtained from 3D digitising, in a 3D CAD surface model dataset. The methodology presented is fundamental to verify the prototype’s geometry for tooling so as to assure its metrological accuracy and to optimise foundry process parameters using finite element analysis (FEA). Based on a case study, some functional conclusions are presented for the application of RT in manufacturing EDM electrodes aided by 3D digitising and RE, validating the accomplishment by the integration of these technologies and methodologies in EDM manufacturing processes.     

Material jetting additive manufacturing: An experimental study using designed metrological benchmarks

Additive manufacturing (AM) technique allows the creation of parts with a high degree of design complexity by building three-dimensional (3D) parts layer-by-layer. Many of the current restrictions of design for manufacturing (DFM) as well as design for assembly (DFA) are no longer applicable for AM due to the lack of needs for tooling. Instead, it is critical to establish the manufacturing limits and design guidelines to achieve optimal production outcomes. This can be achieved through manipulation of process parameters.The purpose of this paper is to establish a systematic methodology for investigating the process capability of material jetting AM techniques by using specially designed benchmark artifacts. In this study, three customized benchmarks were designed to characterize and establish the process capability of material jetting AM techniques. Each of the benchmarks was designed for different purposes. Using a benchmark, metrological studies were conducted to determine the effect of process parameters on the dimensional accuracy of fabricated part. The design limitations on special features such as thin walls and assembly-free parts fabricated using different build orientations were also evaluated.     

Dimensional analysis of a prototype mould-making process for thermoplastic resin transfer moulding

The resin transfer moulding (RTM) process is a low-cost process for the production of parts of composite material. However, the economic convenience is lost when large components should be produced, because of the high tooling cost. The step milling of a resin master and the subsequent deposition of a nickel shell could be a valid alternative for the fabrication of an RTM mould. So far, information about the quality of this method of fabricating RTM moulds is lacking, thus more efforts are needed to quantify the error induced by the manufacturing sequence. In order to control the whole process and to assess the quality of the manufactured part, the dimensional deviation due to single manufacturing steps is evaluated for a reference part. Both traditional pointwise measurements and contactless scanning are used for dimensional inspection.     

快速模具系统工艺特点与分析

采用传统的模具加工方法,制造周期长且成本高。快速成型配合传统制模技术不仅适合单件小批的模具快速制造,而且能适应各种复杂程度的模具快速制造。介绍了基于快速成型技术的快速模具制造技术工艺原理、分类、成型方法及其技术特点以及与传统成形方式的区别。从模具的寿命,模具的制作成本,模具的生产周期等方面对几种典型快速模具制造技术系统进行了比较和归纳。分析了快速模具制造技术面临的关键问题,展望了基于快速成型原理的快速模具制造的应用前景。     

Rapid Sheet Metal Manufacturing. Part 1: Indirect Rapid Tooling

Rapid sheet metal manufacturing (RSMM) is a closed loop process for making sheet metal products which uses advanced computer-aided techniques and computer-controlled machines to produce non-ferrous tooling directly or indirectly. The tooling would be suitable for short-run production or design evaluation of sheet metal products for which prototyping cost and lead time are greatly reduced. The key aspect of this closed-loop process is the method used to fabricate and modify the sheet metal forming tool. Various approaches are adopted in the preparation of the tooling for onward embossing on a sheet metal. The three indirect approaches use selective laser sintering (SLS), stereolithography (SLA), and high-speed computer numerical controlled (CNC) milling to build the masters from computer data models. The masters are used in the vacuum casting process to generate the non-ferrous tooling. Comparisons on quality, lead time and cost are presented.     

Design for economic manufacture of small sheet metal parts

Arguments are presented for a consideration of the DEM of pressed parts on a basis of equipment and tooling used to produce the parts rather than consider a categorisation based on ‘type’ by industry. It is also suggested that a combination of both generative and variant techniques of process planning, in conjunction with a good classification system and data base, should be used by the designer to develop, store and retrieve the type of information used in cost-optimising the design of pressed parts. This paper outlines the elements of cost involved in the production of pressed parts and presents details of a computer-aided process planning system which will assist the designer to quickly obtain the information necessary to optimise the designs. Typical computer program inputs and outputs are presented together with rules that have emerged in pressing design to reduce the number of tooling stages required and therefore the component manufacturing cost.     

Robotic manufacturing of near-net-shape components utilizing stereo imaging and reconfigurable tooling

A process is described to acquire geometrical data of the target object and to utilize it to rapidly create a near-net-shape component with flexible tooling system. The topological data acquisition of the object is made possible using a robot-assisted stereo-imaging technique. Stereo-image data is translated into CAD data, and subsequently the geometric data constitutes the basis for the path planning for the tooling process. A novel, rapidly reconfigurable tooling system and tool forming technology is employed by which a six-axis robotic arm is used to shape a discretized vacuum surface. Pre-heated thermoplastic sheets are formed over the shaped vacuum tool to generate near-net-shape parts. The parts may be trimmed and used as the final component or they may be used as molds for subsequent fabrication of composite components. We demonstrate the process first in the context of an abstract reference part. One of the many applications envisaged using this process is the manufacture of custom-made braces, masks, and guards for use in healthcare products. A patient intervention can have their features acquired using stereo imaging and have corrective measures incorporated into the product prior to manufacturing. Since the geometrical data acquisition process does not require physical contact, the method can be used for patients having epidermal or skeletal damage. Furthermore, employing the rapidly reconfigurable tooling technology will significantly reduce the process cycle time and permit complete customization, benefiting the patient with a quicker and more effective administration of medical assistance. The healthcare context of the proposed integrated process is demonstrated with the manufacture of an orthopedic component with personalized fit.     

Review of materials used in laser-aided additive manufacturing processes to produce metallic products

Rapid prototyping (RP) or layered manufacturing (LM) technologies have been extensively used to manufacture prototypes composed mainly of plastics, polymers, paper, and wax due to the short product development time and low costs of these technologies. However, such technologies, with the exception of selective laser melting and sintering, are not used to fabricate metallic products because of the resulting poor life, short cycle, poor surface finish, and low structural integrity of the fabricated parts. The properties endowed by these parts do not match those of functional parts. Therefore, extensive research has been conducted to develop new additive manufacturing (AM) technologies by extending existing RP technologies. Several AM technologies have been developed for the fabrication of metallic objects. These technologies utilize materials, such as Ni-, Al-, and Ti-based alloys and stainless steel powders, to fabricate high-quality functional components. The present work reviews the type of materials used in laser-based AM processes for the manufacture of metallic products. The advantages and disadvantages of processes and different materials are summarized, and future research directions are discussed in the final section. This review can help experts select the ideal type of process or technology for the manufacturing of elements composed of a given alloy or material (Ni, Ti, Al, Pb, and stainless steel).     

基于Pro/E的节流阀体压铸模CAD/CAM

以节流阀体压铸模的设计及制造为例,论述了Pro/E软件在模具设计和制造中的应用。Pro/E软件可缩短压铸模的设计与制造周期,提高压铸模质量,降低生产成本,而且促进设计的标准化与数据库化。     

Manufacture of an injection mould with rapid and uniform cooling characteristics for the fan parts using a DMT process

The aims of the present study is to manufacture an injection mould with a pair of conformal cooling channels in each blade of the mould for a plastic fan part via laser-aided direct metal tooling (DMT) process to achieve both rapid and uniform cooling characteristics. The features of the design and the manufacturing process for the injection mould as well as the characteristics of the manufactured mould were discussed. Three-dimensional injection moulding analyses were performed to obtain a proper design of the conformal cooling channels. Injection moulding experiments were carried out to investigate the practical applicability of the fabricated mould and the influence of the cooling time on the qualities of the moulded product. The results of the experiments showed that a plastic fan part with superior qualities can be fabricated from the designed mould when the cooling time is 13 s. The efficiency of the designed mould was examined through a comparison of the product from the newly designed mould and that from a previously designed mould with linear cooling channels in terms of product qualities as well as the cooling and cycle times. The results of the comparison showed that the newly designed mould can remarkably reduce the positional error distributions and the eccentricity of the moulded product. In addition, it was shown that the cooling and cycle times of the designed mould can be shortened to 35.0 % and 25.7 % of those of the previously designed mould, respectively.     

Instant tools [rapid tooling]

Rapid prototyping (RP) technology has attracted a lot of attention as an effective tool to compress the new product development process and hence decrease the time to market. As RP technology continues to develop, other systems and processes, such as computer integrated manufacturing and metal injection moulding, are becoming available to industry. One such technology, driven by RP, is rapid tooling (RT) which has the potential to reduce product lead times. RT can be broken into two broad classifications: indirect and direct tooling. In producing a mould tool, for example, indirect tooling would use a master pattern, such as an RP model, to produce the mould cavity, whereas direct tooling would build the mould tool directly from CAD data. The paper reviews the prospects of creating a mould tool directly from a computer model     

影响单点金刚石切削表面质量的因素

单点金刚石切削(single point diamond turning,简称SPDT)是一种使用纳米金刚石刀具进行加工的生产过程。而纳米单晶金刚石刀具具有刃口锋利、可反复成形和耐磨性高等特点。该方法能够使微米至亚微米级制造组件的形状精度和表面粗糙度控制在纳米级的范围内。单点金刚石切削优异的表面成形质量和面形精度,使该技术被广泛地应用于制造各种精密机械和光学部件,如注射成型塑料镜头和扫描反射镜。虽然单点金刚石切削满足了很多高精密零件的制造需求,但目前所了解的影响因素和表面生成的机制仍不完善,在生产中有很多因素会影响到单点金刚石的表面质量和面形精度,如主轴转速、进给速度和切削深度等,本文对此进行了分析。