Manufacturing of multi-functional micro parts by two-component metal injection moulding

Several metals and alloys can be used to enhance the mechanical and physical properties of micro parts and components for micromechanical, micro-chemical or sensor applications. Such parts can be produced in series by the powder metallurgical process of micro metal injection moulding (μ-MIM). This paper describes a novel manufacturing route for metallic multi-material micro components, two-component micro metal injection moulding (2C-μ-MIM). Similar to “two-colour” injection moulding of plastics, the process allows the integration of multiple functions in a micro part by simultaneously injecting and joining two materials in one mould. Net-shape parts with solid material interfaces are obtained. In this paper, the 2C-μ-MIM process is exemplified for the combination of a non-magnetic and a ferromagnetic stainless steel (316 L and 17-4PH). It is shown that intact material interfaces of less than 500×500 μm² can be achieved by careful selection and tailoring of metal powders, injection moulding and co-sintering parameters.     

A scaffolding architecture for conformal cooling design in rapid plastic injection moulding

Cooling design of plastic injection mould is important because it not only affects part quality but also the injection moulding cycle time. Traditional injection mould cooling layout is based on a conventional machining process. As the conventional drilling method limits the geometric complexity of the cooling layout, the mobility of cooling fluid within the injection mould is confined. Advanced rapid tooling technologies based on solid freeform fabrications have been exploited to provide a time-effective solution for low-volume production. In addition, research has made attempts to incorporate conformal cooling channel in different rapid tooling technologies. However, the cooling performance does not meet the mould engineer’s expectations. This paper proposes a novel scaffold cooling for the design of a more conformal and hence more uniform cooling channel. CAD model for constructing the scaffolding structure is examined and cooling performances are validated by computer-aided engineering (CAE) and computer fluid dynamics (CFD) analysis. An erratum to this article can be found at     

微注射成型技术的最新进展与展望

简述了微注射成型技术的产生背景、应用范围和最新进展,详细介绍了微注射成型机、微注射工艺的发展现状,分析了微型腔和微型芯的制造技术及存在的问题,归纳总结了微注射常用的材料及模具成型零件能够达到的最大纵横比和最小结构壁厚,展望了微注射成型的发展趋势.     

A precision robot system with modular actuators and MEMS micro gripper for micro system assembly

A robotic system which consists of a precision manipulator and a micro gripper for a micro system assembly is presented. The developed P-R-R type 3 DOF robot is actuated by newly proposed modular revolute and prismatic actuators. As an end-effector of this manipulator, a micro gripper is designed and fabricated with MEMS technology, and the displacement of the jaw is up to 142.8 μm. A real gripping test is conducted to evaluate the robotic system.     

微型齿轮箱五维装配系统的结构设计

为了解决目前机械制造业中装配部分所占的劳动与制造成本较高的问题,通过对微型齿轮箱的生产装配过程进行研究,而设计了一套针对微型齿轮箱的五维装配系统。该五维装配系统具有X、Y、Z三方向直线移动功能和两个绕Z向旋转功能,并且可实现相互间准确的空间位置关系,可精确控制动作的位置和高度,完成零件从一个位置抓取、运送并准确装入到另一个待装位置进行装配。主要设计了自动夹紧装配机构、气动机械手机构和实现五维运动的传动结构等机械传动部分。设计还对五维装配系统的总体布局及其组成部分进行了详细设计,并给出了五维装配系统结构的主要性能规格参数。该装配系统可大大降低生产成本和减轻装配工人的劳动力。     

A computational system for process design of injection moulding: Combining blackboard-based expert system and case-based reasoning approach

The process design of injection moulding involves the selection of the injection moulding machine, mould design, production scheduling, cost estimation, and determination of injection moulding parameters. Expert system approaches have been attempted to derive the process solution for injection moulding in the past few years. However, this approach has been found to be incapable of determining the injection moulding parameters owing to the difficulty in setting the moulding parameters. In addition, the existing expert systems for process design lack the proper architecture for organising a heterogeneous knowledge source. In this paper, the combination of a blackboard-based expert system and case-based reasoning approach is introduced to make up the deficiencies of the existing expert-system approach to the process design, from which a computational system for process design of injection moulding, named CSPD, was developed and described. CSPD first derives the process solution including the selection of injection moulding machine and mould base, tooling cost, and processing cost estimation, and production scheduling based on the blackboard-based expert-system approach. It is then followed by the determination of the injection moulding parameters based on the case-based reasoning approach and the previously derived partial solution.     

Effects of machined cavity texture on ejection force in micro injection molding

The friction force developed in the demolding phase of the micro injection molding process is mainly determined by mold surface finish, which affects the tribological phenomena occurring at the polymer–tool interface. In this work, the effects on the ejection force of two cavity surfaces machined with different technologies (viz. micro milling and micro electro discharge machining), but with similar value of Ra, were investigated. The relations between different surface topography parameters and the ejection force were then analyzed, in order to identify the parameters that most appropriately describe the friction at the polymer–tool interface. The experimental results showed the strong interactions between the mold surface texture and the micro injection molding process parameters that promote the replication, such as mold temperature and holding pressure. The different machining technologies generated two mold textures that have a similar value of Ra, but their influence on friction can be properly described only using several other surface topography parameters.     

A computational system for process design of injection moulding: Combining a blackboard-based expert system and a case-based reasoning approach

Process design of injection moulding involves the selection of the injection moulding machine, mould design, production scheduling, cost estimation, and determination of injection moulding parameters. An expert system approach has been used to derive the process solution for injection moulding over the past few years. However, this approach is found to be incapable of determining the injection moulding parameters owing to the fragile nature of the knowledge for setting the moulding parameters. In addition, the existing expert systems for process design lack proper architecture for organising heterogeneous knowledge sources. In this paper, the combination of a blackboard-based expert system and a case-based reasoning approach is introduced to eliminate the deficiency of the existing expert-system approach to process design, from which a computational system for the process design of injection moulding, named CSPD, has been developed. CSPD first derives the process solution including the selection of the injection moulding machine and the mould base, tooling cost, processing cost estimation, and production scheduling based on the blackboard-based expert-system approach. It is then followed by the determination of the injection moulding parameters based on the case-based reasoning approach and the previously derived partial solution.     

The concurrent implementation of high velocity control performance and high energy efficiency for hydraulic injection moulding machines

A high servo control response and a high energy efficiency, which are difficult to achieve simultaneously, are requested in hydraulic servo systems of current hydraulic injection moulding machines. This investigation develops new solutions to concurrently implement energy-saving control and velocity control for simultaneously realising high velocity control response and high energy efficiency for injection moulding machines. Two different hydraulic pump systems, including a variable displacement pump and a variable rotational speed pump, are developed and in each one of them two different energy-saving control concepts, such as load-sensing control and constant supply pressure control, are implemented. Thus, for verifying the feasibility of the integrated control systems and comparing the energy-saving effects, velocity control of the hydraulic cylinder can be integrated with four different energy-saving control systems (ESCSs) and also the conventional hydraulic system without energy-saving control. A fuzzy sliding mode control that can simplify the complex fuzzy rule bases is used for solving the complex two-input two-output systems. The experimental results show the excellent performance of the integrated concurrent control systems.     

Integrated control of clamping force and energy-saving in hydraulic injection moulding machines using decoupling fuzzy sliding-mode control

The objective of this research is to implement a novel parallel control of clamping force and energy-saving in hydraulic injection moulding machines (HIMMs) in order to simultaneously achieve accurate force control response and high energy efficiency. In order to verify the feasibility of the integrated control system and compare energy-saving effects, the clamping force control of HIMMs can be integrated with two different energy-saving control systems or integrated with a conventional hydraulic system without energy-saving control. The overall control system is a coupled two-input two-output system. Therefore, a decoupling fuzzy sliding-mode control (DFSMC) strategy, which can reduce the fuzzy rule numbers and counteract the coupling effects, is developed for the integrated control of HIMMs. The experimental results show the outstanding performance of the parallel control in HIMMs with DFSMC .     

喷油泵柱塞偶件密封性试验相对角度计算式推导

利用几何方法推导柱塞偶件密封性试验中相对回转角度的计算式。在密封性试验中,可藉此角度设计、调整夹具。