Fabrication of piezoelectric ceramicpolymer composites by injection molding.pdf
手机充电器注塑模具设计[抽芯]【含全套11张CAD图纸和毕业论文】【优秀资料】
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文档包括:
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图纸共11张:
A0-整体图.dwg
A0-装配图.dwg
A1-凹模.dwg
A1-支撑板.dwg
A2-定模座板.dwg
A2-动模座板.dwg
A2-凸模.dwg
A2-型芯.dwg
A3-充电器外形.dwg
A4-定位圈.dwg
A4-浇口套.dwg
摘 要
摘 要
分析了手机充电器外壳的工艺特点，介绍了手机充电器外壳上盖注射模结构及模具的工作过程。重点介绍了手机充电器外壳注射模结构的设计
方法。分析和阐述了模具型芯零件及各标准件的选材、热处理工艺，手机充电器外壳的塑件的结构要素，塑件的尺寸公差和精度的选择，塑件
的体积和质量的计算方法以及注射机的选择和校核。此手机充电器外壳注射模设计的结构特点是点浇口形式的单分型面的注射模。该模具结构
设计巧妙，操作方便，使用寿命长，塑件达到技术要求。
关键词：手机充电器外壳；注射模；型芯；型腔
Abstract
Has analyzed the handset battery charger outer covering craft characteristic, introduced the handset battery charger outer
covering top head injection mold structure and the mold work process. Introduced the handset battery charger outer covering
injection mold structure design method with emphasis. Analyzed and elaborated the mold core components selection, the heat
treatment craft, the handset battery charger outer covering model the member, model the size common difference and the
precision choice, model a volume and the quality computational method. This handset battery charger outer covering injection
mold designs the unique feature is the runner form three minute profiles injection molds, is lateral pulls out the core
injection mold. After production confirmation, this mold structural design ingenious, the ease of operation, the service life
is long, models to achieve the specification.
Key words: handset battery charger outer；covering injection mold；slide；core.
目 录
第1章 绪 论 - 1 -
1.1 模具工业在国民经济中的地位 - 1 -
2.2 国模具技术的现状及发展趋势 - 1 -
第2章 塑件工艺分析 - 3 -
2.1 塑件的结构要素 - 3 -
2.1.1 ABS的使用性能 - 3 -
2.1.2 ABS材料的成形特点 - 3 -
2.1.3 ABS的成型工艺 - 4 -
2.2 注射成型工艺 - 4 -
第3章 塑件几何形状的设计 - 6 -
3.1 塑件几何形状的设计 - 6 -
3.1.1 脱模斜度 - 6 -
3.1.2 加强筋 - 6 -
3.1.3 塑件的圆角 - 7 -
3.1.4 塑件的壁厚 - 7 -
3.1.5 孔 - 7 -
3.1.6 支承面 - 7 -
3.2 塑件尺寸公差与精度 - 7 -
第4章 分型面及型腔数目的确定 - 9 -
4.1 型腔分型面及型腔数目 - 9 -
4.2 型腔、型芯的结构 - 9 -
4.2.1 型腔的结构设计 - 10 -
4.2.2 型芯的结构设计 - 10 -
第5章 注射机的选取和校核 - 11 -
5.1 根据型腔数选择注射机 - 11 -
5.1.1 根据塑件形状估算其体积和重量 - 11 -
5.1.2 选择注射机 - 11 -
5.2 校核注射机有关工艺参数 - 12 -
5.2.1 注射量的校核 - 12 -
5.2.2 锁模力的校核 - 12 -
5.2.3 开模行程的校核 - 13 -
第6章 成型零件的设计 - 13 -
6.1 成型零件的结构设计 - 13 -
6.1.1 凹模的结构设计 - 14 -
6.1.2凸模和型芯的结构设计 - 14 -
6.2 成型零件工作尺寸的计算 - 14 -
6.2.1凹模与凸模工作尺寸 - 15 -
6.2.2凹模与凸模尺寸计算 - 15 -
6.2.3型腔的强度设计 - 16 -
第7章 浇注系统的设计 - 17 -
7.1 主浇道的设计 - 17 -
7.2 分浇道的设计 - 17 -
7.3 浇口的设计 - 18 -
7.4 冷料穴的设计 - 18 -
第8章 结构零件的设计 - 19 -
8.1 脱模机构的设计 - 19 -
8.1.1 机构的设计原则 - 19 -
8.1.2 脱模机构分类 - 19 -
8.2 脱模机构的导向与复位 - 20 -
8.2.1导向零件 - 20 -
8.2.2 复位零件 - 20 -
第9章 塑料模具钢的选用 - 21 -
9.1 塑料模具材料应具有的性能 - 21 -
9.2 模具选材原则 - 21 -
第10章 模具结构及其工作过程 - 24 -
9.1 模架的选择 - 24 -
9.2 模具工作过程 - 24 -
结 论 - 26 -
致 谢 - 27 -
参 考 文 献 - 28 -
- 内容简介：
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FABRICATION OF PIEZOELECTRIC CERAMlClPOLYMER COMPOSITES BY INJECTION MOLDING. Leslie J. Bowen and Kenneth W. French, Materials Systems Inc. 53 Hillcrest Road, Concord, MA 01742 Abstract Research at the Materials Research Laboratory, Pennsylvania State University has demonstrated the potential for improving hydrophone performance using piezoelectric ceramic/polymer composites. As part of an ONR-funded initiative to develop cost-effective manufacturing technology for these composites, Materials Systems is pursuing an injection molding ceramic fabrication approach. This paper briefly overviews key features of the ceramic injection molding process, then describes the approach and methodology being used to fabricate PZT ceramic/polymer composites. Properties and applications of injection molded PZT ceramics are compared with conventionally processed material. Introduction Piezoelectric ceramic/polymer composites offer design versatility and performance advantages over both single phase ceramic and polymer piezoelectric materials in both sensing and actuating applications. These composites have found use in high resolution medical ultrasound as well as developmental Navy applications. Many composite configurations have been constructed and evaluated on a laboratory scale over the past thirteen years. One of the most successful combinations, designated 1-3 composite in Newnhams notation l 1, has a one-dimensionally connected ceramic phase (PZT fibers) contained within a three-dimensionally connected organic polymer phase. Hydrophone figures of merit for this composite can be made over 10,000 times greater than those of solid PZT ceramic by appropriately selecting the phase characteristics and composite structure. The Penn State composites were fabricated l by hand-aligning extruded PZT ceramic rods in a jig and encapsulating in epoxy resin, followed by slicing to the appropriate thickness and poling the ceramic. Aside from demonstrating the performance advantages of this material, the Penn State work highlighted the difficulties involved in fabricating 1-3 composites on a large scale, or even for prototype purposes. These are: 11 The requirement to align and support large numbers of PZT fibers during encapsulation by the polymer. 2) The high incidence of dielectric breakdown during poling arising from the significant probability of encountering one or more defective fibers in a typical large array. Over the past five years several attempts have been made to simplify the assembly process for 1-3 transducers with the intention of improving manufacturing viability and lowering the material cost. Early attempts involved dicing solid blocks of PZT ceramic into the desired configuration and back-filling the spaces with a polymer phase. This technique has found wide acceptance in the medical ultrasound industry for manufacturing high frequency transducers 2. More recently, Fiber Materials Corp. has demonstrated the applicability of its weaving technology for fiber-reinforced composites to the assembly of piezoelectric composites 31. Another exploratory technique involves replicating porous fabrics having the appropriate connectivity 41. For extremely fine scale composites, fibers having diameters in the order of 25 to 100 pn and aspect ratios in excess of five are required to meet device performance objectives. As a result, these difficulties are compounded by the additional challenge of forming and handling extremely fine fibers in large quantities without defects. Recently, researchers at Siemens Corp. have shown that very fine scale composites can be produced by a fugitive mold technique. However, this method requires fabricating a new mold for every part 51. This paper describes a new approach to piezoelectric composite fabrication, viz: Ceramic injection molding. Ceramic injection molding is a cost- effective fabrication approach for both Navy piezoelectric ceramic/polymer composites and for the fabrication of ultrafine scale piezoelectric composites, such as those required for high frequency medical ultrasound and nondestructive evaluation. The injection molding process overcomes the difficulty of assembling oriented ceramic fibers into composite transducers by net-shape preforming ceramic fiber arrays. Aside from this advantage, the process makes possible the construction of composite transducers having more complex ceramic element geometries than those previously envisioned, leading to greater design flexibility for improved acoustic impedance matching and lateral mode cancellation. Process Descriotion Injection molding is widely used in the plastics industry as a means for rapid mass production of complex shapes at low cost. Its application to ceramics has been most successful for small cross- section shapes, e.g. thread guides, and large, complex shapes which do not require sintering to high density, such as turbine blade casting inserts. More recently, the process has been investigated as a production technology for heat-engine turbine components 6,71. The injection molding process used for PZT molding is shown schematically in Figure 1. By injecting a hot thermoplastic mixture of ceramic powder and organic binder into a cooled mold, complex shapes can be formed with the ease and rapidity normally associated with plastics molding. Precautions, such as hard-facing the metal contact surfaces, are important to minimize metallic contamination from the compounding and molding machinery. For ceramics, the binder must be removed nondestructively, necessitating high solids loading, careful control of the binder removal Powder Process i ng -r- 4 CERAMIC PREFORM Organic Binder - - - - I Granulate I - - - - - - PREFORM LAY-UP TO FORM LARGER ARRAYS -_Lu-i_- 1-1 and apply electrodes Figure 1 : Injection Molding Process Route. process, and proper fixturing. Once the binder is removed, the subsequent firing, poling and epoxy encapsulation processes are similar to those used for conventional PZTipolymer composites 11 I . Thus, the process offers the following advantages over alternative fabrication routes: Complex, near net-shape capability for handling many fibers simultaneously; rapid throughput (typically seconds per part); compatibility with statistical process control; low material waste; flexibility with respect to transducer design (allows variation in PZT element spacing and shape); and low cost in moderate to high volumes. In general, because of the high initial tooling cost, the ceramics injection molding process is best applied to complex-shaped components which require low cost in high volumes. Comoosite Fabrication and Evaluation The approach taken to fabricate 1-3 piezoelectric composites is shown in Figure 2a, which illustrates a PZT ceramic preform concept in which fiber positioning is achieved using a co-molded integral ceramic base. After polymer encapsulation the ceramic base is removed by grinding. Aside from easlng the handling of many fibers, this preform approach allows broad latitude in the selection of piezoelectric ceramic element geometry for composite performance optimization. Tool design is important for successful injection molding of piezoelectric composites. The approach shown in Figure 2b uses shaped tool inserts to allow changes in part design without incurring excessive retooling costs. Figure 2c shows how individual preforms are configured to form larger arrays. Figure 2a: Preform Configuration (Approx. 400 ceramic elements) REMOVABLE INSERT : CAVITY TOOL BODY U * S P R U E Figure 2b: Injection Molding Tool Configuration Figure 2c: Large Area Composite Arrays made from Preforms Figure 2: Preform Approach to Composite Fabrication. In practice, material and molding parameters must be optimized and integrated with injection molding tool design to realize intact preform ejection after molding. Key parameters include: PZT/binder ratio, PZT element diameter and taper, PZT base thickness, tool surface finish, and the molded part ejection mechanism design. In order to evaluate these process parameters without incurring excessive tool cost, a tool design having only two rows of 19 PZT elements each has been adopted for experimental purposes. Each row contains elements having three taper angles (0, 1 and 2 degrees) and two diameters (0.5 and lmm). To accommodate molding shrinkage, the size of the preform is maintained at 5Ox50mm to minimize the possibility of shearing off the outermost fibers during the cooling portion of the molding cycle. Figure 3: Injection Molded 1-3 Composite Preforms. 161 Figure 3 shows green ceramic preforms fabricated using this tool configuration. Note that all of the PZT elements ejected intact after molding, including those having no longitudinal tapering to facilitate ejection. Slow heating in air has been found to be a suitable method for organic binder removal. Finally, the burned-out preforms are sintered in a PbO- rich atmosphere to 97-98% of the theoretical density. No problems have been encountered with controlling the weight loss during sintering of these composite preforms, even for those fine-scale, high-surface area preforms which are intended for high frequency ultrasound. . .- . . -. . L. . Figure 4: Scanning Electron Micrographs of As-molded (Upper) and As-sintered (Lower) Surfaces of PZT Fibers. Figure 4 illustrates the surfaces of as-molded and as-sintered fibers, showing the presence of shallow fold lines approximately 10pm wide, which are characteristic of the injection molding process. The fibers exhibit minor grooving along their length due to ejection from the tool. Figure 5 shows the capability of near net-shape molding for fabricating very fine scale preforms; PZT element dimensions only 30pm wide have been demonstrated. The as-sintered surface of these elements indicates that the PZT ceramic microstructure is dense and uniform, consisting of equiaxed grains 2-3pm in diameter. Figure 5: Fine-scale 2-2 Composite formed by Near Net- shape Molding (Upper Micrograph). As-sintered Surface (Lower Micrograph). In order to demonstrate the lay-up approach for composite fabrication, composites of approximately 10 volume percent PZT-5H fibers and Spurrs epoxy resin were fabricated by epoxy encapsulating laid-up pairs of injection molded and sintered fiber rows followed by grinding away the PZT ceramic stock used to mold the composite preform. Figure 6 shows composite samples made from freshly-compounded PZT/binder mixture and from reused material. Recycling of the compounded and molded material appears to be entirely feasible and results in greatly enhanced material utilization. Table 1 compares the piezoelectric and dielectric properties of injection molded PZT ceramic specimens with those reported for pressed PZT-5H samples prepared by the powder manufacturer. When the sintering conditions are optimized for the PZT-5H formulation, the piezoelectric and dielectric properties are comparable for both materials. Since the donor- doped PZT-5H formulation is expected to be particularly sensitive to iron contamination from the injection molding equipment, the implication of these measurements is that such contamination is negligible in this injection molded PZT material. *Powder supplied by Morgan Matroc, Inc., Bedford, Ohio; Lot 105A. 162 Table 1 : Properties of Injection Molded Piezoelectric Ceramics. Specimen Relative Dielectric d33 TY Pe Permittivity Loss (1 kHz1 (pC/N) Die-Pressed 3584 0.01 8 745 Inj. Molded* 3588 0.01 8 755 *Aged 24 hours before measuremegt. *Poling conditions: 2.4kV/mm, 60 C, 2 minutes. Figure 6: Injection Molded PZT Fiber/Epoxy Resin Composites prepared by the Preform Lay-up Method. Summarv Ceramic injection molding has been shown to be a viable process for fabricating both PZT ceramics and piezoelectric ceramic/polymer transducers. The electrical properties of injection molded PZT ceramics are comparable with those prepared by conventional powder pressing, with no evidence of deleterious effects from metallic contamination arising from contact with the compounding and molding equipment. By using ceramic injection molding to fabricate composite preforms, and then laying up the preforms to form larger composite arrays, an approach has been demonstrated for net-shape manufacturing of piezoelectric composite transducers in large quantities. Ac knowledaements This work was funded by the Office of Naval Research under the direction of Mr. Stephen E. Newfield. The auth
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