Effects of micromilled NiP mold surface topography on the optical characteristics of injection molded prismatic retroreflectors

Automotive lighting applications require mold micro-features with increasingly better surface finishing, especially for optical lenses and retroreflectors. In this work innovative micromilling experiments were conducted on electroless-plated nickel phosphorous (NiP) surfaces to fabricate a mold for prismatic retroreflectors. Cutting parameters effects on surface topography of mold micro-features were experimentally characterized and optimized, monitoring moreover the cutting forces generated by NiP micromilling. Furthermore, the mold surface topography was replicated on polycarbonate injection molded retroreflectors and its effects on their optical performance was characterized by means of a dedicated spectrophotometric technique. The obtained results show that micromilling of electroless-plated NiP can substitute polishing in the fabrication of high surface finish mold micro-features.     

Simulation of rubber isostatic pressing and shape optimization of rubber mold

An elastic–plastic FEM is developed to study the fundamental features of rubber isostatic pressing of powder with a view to performing a net-shape process. Experiments are also performed. It is thus shown that the properties of the rubber, in particular Poisson's ratio, give a great influence on the shape of compact and density distribution. The thickness of the rubber mold is also influential; the thicker the mold, the closer is the shape of compact to the cavity shape. An optimization scheme is also developed, so that one is able to determine the cavity shape that gives a desired shape of compact.     

The study of chip characteristics and tool wear in milling of SKD61 mold steel

In recent years, many machining applications have used dry cutting for high-speed cutting, for which, tool life prediction and research are important issues. In this study, a tungsten carbide tool cutting steel SKD61 was used, and the actual value of the chip shooting and the wear of the flank were determined using an industrial camera. The chip type and chip color are also discussed. After color calibration and chromaticity conversion, the model was trained through the neural network and the results were predicted. The tool wear curve and the theoretical curve were found to be closely related, and the chip color changed regularly. In the CIE XY chromaticity coordinate value, when the initial cutting was observed, the chip chromaticity coordinate point range was small, but as the wear amount increased, the chip chromaticity coordinate point range expanded gradually. The tool wear prediction established in this study was determined from the experimental results. The maximum errors of the test and verification were 0.031 mm and 0.022 mm. After calculation, the mean absolute percentage error (MAPE) was within 3 % and the accuracy level is MAPE is less than 10 %, so it has a high accurate prediction ability. Established tool wear predictions are also provided.

     

模具CATS系统中半精铣刀具直径决策算法

在加工含有自由曲面的复杂高精度模具时,常在粗铣和精铣加工之间安排半精铣加工工序.为了合理选择半精铣的刀具直径,在分析了相铣加工所得实体模型的结构特性基础上,提出了适合于半精铣刀具直径决策的算法.实例验证了该算法的可行性和有效性.     

Precision surface finish of the mold steel PDS5 using an innovative ball burnishing tool embedded with a load cell

A load-cell-embedded burnishing tool has been newly developed and integrated with a machining center, to improve the surface roughness of the PDS5 plastic injection mold steel. Either the rolling-contact type or the sliding-contact type was possible for the developed ball burnishing tool. The characteristic curves of burnishing force vs. surface roughness for the PDS5 plastic injection mold steel using the developed burnishing tool for both the rolling-contact type and the sliding-contact type, have been investigated and constructed, based on the test results. The optimal plane surface burnishing force for the PDS5 plastic injection mold steel was about 420 N for the rolling-contact type and about 470 N for the sliding-contact type, based on the results of experiments. A force compensation strategy that results in the constant optimal normal force for burnishing an inclined surface or a curved surface, has also been proposed to improve the surface roughness of the test objects in this study. The surface roughness of a fine milled inclined surface of 60 degrees can be improved from R_a 3.0 μm on average to R_a 0.08 μm (R_max 0.79 μm) on average using force compensation, whereas the surface roughness was R_a 0.35 μm (R_max 4.56 μm) on average with no force compensation.     

面向网络化制造的注塑模具报价工具研究

针对已有注塑模具报价较多采用经验系数方法的局限性,着眼于分析性的价格计算模型,本文在掌握一般工业产品估价过程和注塑模具设计制造特点的基础上,根据其功能结构,将注塑模具的核心成本划分为18个成本项,利用分项求和的思想建立了模具价格的分析性算法模型,并基于此算法开发了注塑模具网络化报价系统,从而为用户提供了切实、灵活的注塑模具报价工具.     

A study on helical surface generated by the primary peripheral surfaces of ring tool

Often in the engineering practice, cutting tools bounded by primary peripheral surfaces of revolution are used because of their effectiveness. Among these, ring and tangential tools can be used for the generation of constant pitch cylindrical helical surfaces. In this paper, we present an algorithm for the profiling of these types of tools. The algorithm is based on the topological representation of the tool’s primary peripheral surface. The main goal is to devise a methodology for the profiling of tools whose surfaces are reciprocally enveloping with cylindrical helical surfaces. We present a numerical example for the numerical determination of the axial section form for this type of tools. The application method for this algorithm was developed in the CATIA graphical design environment within which the procedure is developed as a vertical application. In addition, we present a solution for the shape correction of the tool’s axial cross-section by considering the existence of singular points on the profile of the helical surface to be generated where multiple normals to the surface exist.     

不可展开空间曲面模具表面精密加工方法研究

弧面凸轮轮廓为复杂而不可展开的空间曲面,在毛坯等温挤压过程中,为使材料顺利地充满凹模型腔以及成形后脱模顺利,通过在弧面凸轮曲面上加盖敷料及在各连接处采取圆弧过渡,以制得高精度的近似净形零件毛坯件;并通过对弧面凸轮HALF凹模型腔表面加工方法的研究,以提高等温挤压工艺模具在弧面凸轮毛坯成形的使用寿命.     

A study of the Taguchi optimization method for surface roughness in finish milling of mold surfaces

The objective of this paper is to develop a Taguchi optimization method for low surface roughness in terms of process parameters when milling the mold surfaces of 7075-T6 aluminum material. Considering the process parameters of feed, cutting speed, axial-radial depth of cut, and machining tolerance, a series of milling experiments were performed to measure the roughness data. A regression analysis was applied to determine the fitness of data used in the Taguchi optimization method using milling experiments based on a full factorial design. Taguchi orthogonal arrays, signal-to-noise (S/N) ratio, and analysis of variance (ANOVA) are used to find the optimal levels and the effect of the process parameters on surface roughness. A confirmation experiment with the optimal levels of process parameters was carried out in order to demonstrate the effectiveness of the Taguchi method. It can be concluded that Taguchi method is very suitable in solving the surface quality problem of mold surfaces.     

模具失效形式判定依据与技术应用性研究

阐述模具一般表面失效形式和失效机理,并且依据失效形式总结了模具失效判据以及给出描述性失效判据,为进一步研究模具失效提供了基本思考路线.     

面向网络化制造的注塑模具报价工具研究

针对已有注塑模具报价较多采用经验系数方法的局限性,着眼于分析性的价格计算模型,本文在掌握一般工业产品估价过程和注塑模具设计制造特点的基础上,根据其功能结构,将注塑模具的核心成本划分为18个成本项,利用分项求和的思想建立了模具价格的分析性算法模型,并基于此算法开发了注塑模具网络化报价系统,从而为用户提供了切实、灵活的注塑模具报价工具.     

Experimental study on mechanical behaviors of injection molded PC/PMMA blends

Journal of Mechanical Science and Technology - Mechanical property is one of the quite important factors of optical articles. Most of pure plastics materials are rarely found to have both high...     

Effects of molding conditions on injection molded direct joining using a metal with nano-structured surface

Injection molded direct joining (IMDJ) is one of the metal-plastic direct joining processes and is based on a combination of a special surface treatment of a metal piece and an insert molding. This study employed a chemical processing as the special surface treatment to form nano-structures on the metal piece. We investigated relationship between joining strengths and molding conditions; we focused on pressure of a mold cavity and injection speed as molding conditions in this work. To evaluate the IMDJ samples processed under various molding conditions, we carried out tensile-shear tests. Then we compared the results of the tests to discuss how much each condition variation affected the joining strength. From the discussion, we found an interesting effect of the injection speed, which is unique to the IMDJ using a metal piece with nano-structures. The findings of this study will promote a better understanding of the IMDJ.     

利用ANSYS的模具线切割加工表面变质层分析

分析了线切割(WEDM)加工表面变质层的影响因素,根据DK7732机床在模具加工中的应用,用有限元软件AN-SYS对线切割加工过程进行温度分布计算,在采用与真实加工相类似的边界条件下,模拟电参数(脉冲宽度)的变化对线切割加工工件表面变质层的影响,得出在实验条件下,按DK7732机床各档脉冲宽度加工时变质层的分布数据,以及其高温层和低温层区域相对较宽、中温区域很窄的结论,有利于后续的工艺探究。同时提出了减少变质层的相应措施。     

基于UG MoldWizard软件注塑模分型面设计初探

注塑模具分型面设计是模具设计中的重要部分,首先介绍模具分型面的选择原则,通过典型案例介绍UGMoldWizard四种分型面的创建方法.提出注塑模分型面设计的关键是判斯创建的分型线是否在同一个平面或是曲面内,再采用相应创建曲面的方法创建分型面.目的是为类似注塑件分型面的创建提供参考.     

Iso-parametric tool path generation from triangular meshes for free-form surface machining

The polyhedral model is widely used in the manufacturing industry. However, apart from the iso-planar method, the tool path generation methods for polyhedral machining are very limited. In such a case, the given tool paths are no longer boundary-conformed or efficient. This paper presents a new approach to iso-parametric tool path generation for triangular meshes. The strategy proposed herein first parameterizes the triangular faces via a harmonic map. The cutter-contact (CC) points and the path interval are then calculated based on the machining tolerance requirements and the iso-parametric tool paths are finally generated. The method is implemented on a computer and some illustrative examples are provided to show the effectiveness of the developed algorithm. The main advantage of the proposed method is that the tool paths can be generated naturally along the boundary of a polyhedral model, thus eliminating internal tight-radius corners in conventional paths. This leads to substantial reductions of tool wear and machining time. In addition, the proposed method can also be used in other non-iso-parametric tool path planning methods for triangular meshes and compound surfaces machining.     

The dependence of tool overhang on surface quality and tool wear in the turning process

In the turning process, the importance of machining parameter choice is increased, as it controls the surface quality required. Tool overhang is a cutting tool parameter that has not been investigated in as much detail as some of the better known ones. It is appropriate to keep the tool overhang as short as possible; however, a longer tool overhang may be required depending on the geometry of the workpiece and when using the hole-turning process in particular. In this study, we investigate the effects of changes in the tool overhang in the external turning process on both the surface quality of the workpiece and tool wear. For this purpose, we used workpieces of AISI 1050 material with diameters of 20, 30, and 40 mm; and the surface roughness of the workpiece and tool wear were determined through experiments using constant cutting speed and feed rates with different depth of cuts (DOCs) and tool overhangs. We observed that the effect of the DOC on the surface roughness is negligible, but tool overhang is more important. The deflection of the cutting tool increases with tool overhang. Two different analytical methods were compared to determine the dependence of tool deflection on the tool overhang. Also, the real tool deflection values were determined using a comparator. We observed that the tool deflection values were quite compatible with the tool deflection results obtained using the second analytical method.     

基于RE的复杂曲面零件模具的快速设计与制造

随着现代计算机技术和测试技术的发展,利用逆向工程技术对产品进行建模、仿真、优化及新产品开发成为现代设计的一大热点,并已成为CAD/CAM领域特别是模具设计和制造的重要技术之一。以油壶切边模为例,采用逆向工程技术通过实物原型获取了油壶的三维轮廓数据,然后利用Pro/E等软件将得到的轮廓数据三维重构,得到了实物原型的三维数字模型,实现了油壶切边模具的设计与制造。采用逆向工程技术可以快速实现模具的设计与制造,大大缩短产品设计周期,提高产品竞争力。     

An analytical study of the wear pattern of an abraded rubber surface: the interaction model

ABSTRACT

The relationship between the volume loss rate and the wear pattern along an abraded rubber surface has been confirmed. Experimentally, long and short pattern spacings are formed along the abraded direction that, respectively, represent the initial and final pattern spacings. By modelling the abrasion, or the sliding contact, as a vibration system, an analytical study to identify the pattern spacing is carried out. There are two proposed interaction models of the contact between the rubber surface and the abrader, i.e. separation and unification, thus, the interaction along the sliding contact is a combination of both. It is confirmed that the separation model is correlated to the initial pattern spacing. The results are obtained that the final pattern spacing not only depends on the static load of the abrader but also depends on the dynamic load due to the inertia effect of the moving parts of abrasion apparatus.