塑料模具型腔的冷挤压成形

介绍了塑料模具型腔冷挤压工艺、冷挤压用模具和坯料的结构以及相关参数。     

型腔冷挤压加工技术

本文详细阐述了型腔冷挤压加工技术的原理,并提出了采用此加工技术在工艺上的要求,从而可能获得比较理想的成型模。     

旋扭压胶模的型腔冷挤压加工

我厂产品中的热固性塑料旋扭如图1所示。压胶模结构如图2所示。其中顶件器7的上平面比型腔6的底平面高0.3mm,是防止多次出模磨损而使型腔与顶件器之间间隙增大。由于型腔镶件6的型腔较复杂,故采用冷挤成形,取得了良好的效果。现将加工过程介绍如下。     

活塞销冷挤压成形工艺研究

通过对活塞销结构工艺性分析,制定了活塞销的冷挤压工艺方案并设计了挤压件图,确定了组合凹模直径及径向过盈量与轴向压合量等工艺尺寸:设计了便于调整及更换的组合凸模,保证了挤压件的同心度;根据凸模工作特点采取合适的热处理工艺,提高了模具的使用寿命.     

冷镦模工作型腔的制造工艺

介绍了冷镦模型腔的冷挤压法和电蚀性的优缺点，分析了电化学加工型腔的合理性。     

冷挤压凸模固定方式的探索

通过介绍冷挤压凸模易断裂的情况,分析了易断的主要原因。提出了在凸模与凸模固定套之间加一45钢圈,本文称之为缓冲圈,来改善凸模的受力状况,实现了保护冷挤压凸模,延长凸模寿命的目的,缓冲圈的使用效果显著。     

提高冷挤压模具寿命的工艺措施

此文分析了冷挤压凸模、凹模在使用过程中产生的磨损塑性变形、疲劳破坏和断裂、寿命不高的原因，以及采取的相应措施。分析指出，模具材料碳化物分布不均、凸模硬底偏低、机加工出现刀痕、工作部分圆角尺寸全合作、热处理工艺不当、润滑不良、未采取去除力措施、凹模配合过盈量不合适等是造成上述缺陷的主要原因。试验表明，选择合适的模具材料，进行合理的模具设计、提高模具的加工精度、防止磨削裂纹、合理润滑、经常性的消除应力     

冷挤压凸模结构的改进

研究了凸模形状、结构－工艺因素、压应力和拉应力对冷挤压凸模耐用度的影响。概述了提高凸模用度的具体途径。列出了高耐用度凸模的主要类型及其采用的条件。     

内斜齿轮冷挤压成形工艺方案

首先对内斜齿轮的几何特点进行分析,并针对内斜齿轮在冷挤压成形时存在的成形力过大、成形质量差、挤压件脱模困难等技术难点,提出了采用浮动凸模的工艺方案。利用有限元软件DEFORM-3D,对空心坯料冷挤压工艺进行数值模拟分析,分别研究了坯料内孔直径、入模半角和定径带长度对挤压成形载荷和性能的影响。研究结果表明:当坯料内孔直径尺寸为Φ72. 5 mm、入模半角选取45°、定径带长度为20 mm时,内斜齿轮齿形充填均匀,齿形饱满,成形载荷也相对较小。采用浮动凸模的工艺进行内斜齿轮冷挤压成形工艺试验,证明了该工艺方案的可行性和数值模拟结果的正确性。     

花键套冷挤压成形工艺方案分析

针对花键套在冷挤压成形内花键时出现的凸模断裂问题,建立内花键成形的有限元模型并进行数值模拟。模拟结果表明,凸模导向区与齿形区截面变化大,圆角过渡处容易产生应力集中,从而导致在过渡处发生断裂。提出去掉凸模导向区、在凹模内增加浮动芯轴作为导向的解决措施。并对改进的工艺方案进行数值模拟分析,凸模无应力集中现象,花键套无成形缺陷。工艺实验结果表明,采用改进的工艺方案可以有效避免凸模反挤压成形内花键的断裂问题,延长模具使用寿命。     

重载渐开线齿轮滚齿加工齿形误差超差原因及消除方法

通过对渐开线齿形误差超差原因的分析 ,根据本厂现有的技术和设备条件 ,提出了几种消除渐开线齿形误差超差的方法     

大型普通滚齿机插削大模数斜齿轮的技术

介绍了在大型普通滚齿机上插削大模数斜齿轮和小空刀槽人字齿轮的原理与装置。     

数控滚齿机参数化自动编程系统开发

为了提高齿轮加工效率,提出了一种基于滚齿加工的自动编程系统。在分析齿轮滚削加工工艺的基础上,建立了齿轮加工的数学模型,进而得到数控滚齿加工的NC程序。该方法仅需通过人机界面输入工件、刀具和工艺等参数,在工艺数据库和运算库的支撑下,即可自动生成NC程序。针对广州数控218MC数控系统,通过用户宏程序进行了自动编程系统的开发,实现了人机界面设计、滚齿算法设计和功能模块设计。最后,通过在工厂多台五轴滚齿机上的应用表明该系统编程效率高、加工零件精度高、算法可靠性强的特点,同时降低了机床操作人员的职业技术门槛,提升了国产齿轮数控系统的市场竞争力。     

碳化铌覆层模具在冷挤压过程中的温度场与磨损行为

在冷挤压模具表面制造碳化铌(Nb C)覆层,可望满足恶劣的工作环境对冷挤压模具表面性能的需求。本文以套筒零件的冷挤压为例,通过有限元建模与Archard磨损模型相结合的方法,获得了无覆层凸模和不同厚度的碳化铌覆层凸模在冷挤压过程中的温度场变化和磨损规律。研究结果表明:相对于无覆层凸模,碳化铌覆层凸模在有限元模拟冷挤压过程中服役性能良好,可降低模具内部温度,显著增强模具表面的耐磨性能;覆层厚度过厚或者过薄都会降低模具表面的耐磨性,覆层厚度为10μm时耐磨性最好。以上研究可探索碳化铌覆层在冷挤压过程中对模具的保护作用。     

Application of transparent casting moulds prepared by additive manufacturing technology in hydraulic simulation

Hydraulic simulation is one of the critical methods to research the filling mechanism of molten metal in the casting process. However, it only performs on test pieces with relatively simple structures due to the limitation of the preparation method. In this study, the method of photocuring additive manufacturing was used to prepare the complex casting mould from transparent photosensitive resin. The pouring test was carried out under different centrifugal conditions, and the filling process of the gating system, support bars and other positions in the vertical direction was recorded and analyzed. The experimental results show that the internal liquid level and the filling process of the test piece prepared by this method can be observed clearly. The angle between the liquid surface and the horizontal plane in the test piece gradually increases as the centrifugal rotational speed increases, which means the filling process is carried out from outside to inside at high rotational speed. The velocity of the fluid entering the runner increases with the increase of rotational speed, but the filling speeds is less affected by the centrifugal speed at other positions. The liquid flow is continuous and stable during the forward filling process, without splashing or interruption of liquid droplets.

     

Development of a new rapid characterization method of hob's wear resistance in gear manufacturing—Application to the evaluation of various cutting edge preparations in high speed dry gear hobbing

Gear hobbing remains a cutting technology mainly dedicated to large-scale productions of gears for the automotive industry. The improvements in hobbing tool design are problematic due to the very long duration of wear tests and due to the application of special machine tools only available in production plants. In order to overcome these limitations and to accelerate the efficiency of the investigations, a new rapid testing method called “flute hobbing” has been developed on a standard five-axes milling machine widely present in research laboratories. This testing method has been associated with a software providing the geometry of each chip in hobbing. The correlation of the chip geometry with the wear of each tooth enables to discriminate the critical teeth of a hob in order to focus the development in this area of the cutting zone. This new methodology has been used to investigate the influence of the cutting edge preparation on the wear resistance of gear hobs made of PM-HSS in the context of dry high speed manufacturing. The application of the AFM technology to generate defined edge preparation has shown its efficiency to improve the tool wear resistance and has confirmed previous results.     

Modelling of spherical mandrelling manufacturing resistance

In conventional manufacturing, the spherical mandrelling (SM) method is an alternative to the methods of cold expansion of holes: split mandrel and split sleeve. SM is performed on conventional machines, thereby broadening their manufacturing capabilities. Mathematical models of spherical mandrelling manufacturing resistance have been obtained analytically and experimentally in order to set rational operating conditions and for strength estimation of the system: machine–device–tool–workpiece.     

电磁过滤器在冷轧中的应用

针对冷轧乳化液除杂净化处理中应用的磁链式除铁器的不足, 将其更换为电磁过滤器, 并对实际应用中出现的问题进行了分析和优化, 对其运行状况的检测报告显示, 乳化液经过电磁过滤器处理前的进口铁含量为206～230 μg/L, 处理后出口铁含量为88～95 μg/L, 肉眼看不到任何颗粒, 满足冷轧乳化液铁粉含量的要求, 保证了冷轧薄板的产品质量, 节约了成本。     

开放式滚齿机数控系统开发策略及系统结构研究

在分析基于PC的开放式数控系统实现途径的基础上,结合PMAC的功能特点和滚齿加工特点,对开放式滚齿机数控系统的开发策略进行了详细的分析,并阐述了在此策略下数控系统的软、硬件结构。     

数控系统智能加工功能在大型精密模具制造中的应用

介绍了海德汉iTNC 530数控系统的智能加工功能,阐述了系统在大型精密模具制造中的应用,系统可提高模具制造效率和精度,在许多企业的实际应用中取得了良好的效果。