球墨铸铁耙片挤压铸造新工艺

给出了挤压铸造球墨铸铁耙片的新型模具结构、工艺参数和应用效果.模具设有冷却水道和铁水溢流槽.为在耙片上铸出通孔,凸模和凹模分别设有浮动型芯.经试验,挤压铸造的球墨铸铁耙片力学性能好,生产成本低.     

铸态贝氏体钢耙片组织与性能的研究

通过对所研制的铸态贝氏体钢CCT曲线的测定，采用液态挤压铸造法成形耙片，使耙片的不同部位获得与其工作条件相适应的不同形态的贝氏体组织和性能，试验表明，铸态贝氏体钢具有较高的硬度，韧性和较好的耐磨性。为耙片生产提供了新的材料。     

涂料在半固态钢挤压成形中的应用

在半固态钢挤压铸造成形过程中,主要由模具型腔表面涂层承受高温半固态钢浆料的热冲击,从而降低了浆料对模具的热损伤,提高了模具使用寿命。根据半固态钢挤压铸造涂料的工作环境和特点,通过大量试验对涂料配方、配比、制备工艺、涂敷工艺进行分析研究,确定了诸因素在半固态钢挤压铸造过程中的影响。     

锻模模块的挤压铸造模具设计

挤压铸造近年来得到较大的发展，正在成为制造模块的有效方法。给出了挤压铸造锻模模块的实用模具结构、工艺参数和应用效果。该模具的凸模和凹模均采用组合结构，设有冷却水道。为适用于无下顶料装置的通用液压机，模具设置了自动复位的下顶料装置。模具寿命满足生产要求。挤压铸造的模块内部无空洞。试验表明，对4Cr5W2SiV，5CrMnMo，5CrNiMo，3Cr2W8V等模具钢的挤压铸造，压力超过150MPa即可消除挤压铸造缺陷，并获得完全的细晶组织，挤铸钢的力学性能基本达到锻钢水平。     

用CCT图研究Mo-Nb钢铸态贝氏体组织的形成

所研究的铸态贝氏体钢是通过合金化和控制冷却速度的方法在铸态下直接得到贝氏体组织的，不需热处理即可获得所需的组织和性能。为真实反映贝氏体钢铸态组织的形成过程，用CCT图模拟铸态条件，找出连续冷却速度与各种组织形成的规律，为Mo-Nb钢铸态下获得贝氏体组织提供了理论依据。     

H11钢锻模挤压铸造模具设计及成形工艺

为了减少热锻模的加工量,节省模具钢,采用挤压铸造方法生产H11钢热锻模。给出了挤压铸造锻模合理的模具结构和合适的工艺参数。为了取件方便,成形模具的凸模和凹模均采用组合结构。结果表明,得到的挤压铸造件的尺寸和性能都达到了设计要求,加工工时减少了1/3,降低了加工成本。     

7001高强铝合金挤压铸造过程的数值模拟分析

针对轻量化铝合金零件力学性能、质量和精度要求高等问题,建立了铝合金挤压铸造有限元分析模型。对挤压模具在实际工况下的力学性能进行了分析,对其结构进行了优化,分析了不同浇注温度、模具温度、挤压速度及挤压力对铝合金挤压铸造缩松缩孔特性的影响。结果表明,设计的挤压铸造模具满足强度和变形要求,铝合金最佳挤压铸造工艺参数为浇注温度650℃,模具温度200℃,挤压速度0.01m/s,挤压压力50 MPa;优化的模具结构其力学性能及铸造特性更优良。     

原位纳米高强韧贝氏体钢轨的组织

采用真空熔炼+离心铸造和真空熔炼+普通铸造的方法制备了两组贝氏体钢,随后对两组钢进行了相同的轧制和热处理工艺,采用光学显微镜、扫描电镜和透射电镜等观察分析了两组试验钢的显微组织。结果表明:相比于普通铸造方法,通过离心铸造方法获得的试验钢的组织中有均匀细小的原位纳米析出相且基本消除了钢在铸造过程中的偏析现象;经不同的退火工艺处理后,试验钢获得了粒状贝氏体和板条状无碳化物贝氏体。     

挤压铸造设备的研究进展与发展趋势

挤压铸造设备是完成挤压铸造工艺的主要平台,挤压铸造设备的性能直接影响挤压铸造产品的质量.本研究针对VV型结构、HV型结构、HH型结构挤压铸造压力机介绍了挤压铸造机的关键技术和发展状况.在外围系统部分,主要介绍了挤压铸造模具和浇注系统的研究进展.随着挤压铸造工艺日趋完善和应用范围不断扩大,今后挤压铸造设备上的发展方向主要是大吨位挤压铸造机的研制、浇注系统的改进、模具温度控制这三个方面.     

45钢阀体挤压铸造模具设计

45钢阀体挤压铸造模具设计为组合式模具。模具的模芯和冲头采用性能较高的H13钢，模套及定位结构部分采用45钢或40Cr钢。成形设备采用专用的挤压铸造液压机，最大挤压力为1500kN，最大锁模力为2000kN。上、下冲头取2。的起模斜度，侧冲头取了0．5。的起模斜度，冲头速度为0．30～0．35m／s。顶出方式采用下冲头上行直接顶出，冲头与模具之间的单边配合间隙取0．16～0．2mm。采用管道式冷却和插管式冷却相结合，对模具受到较大热应力的部分进行冷却。为了保证制件高度方向的精度，在分型面十字方位上开设有4个溢流槽。为了提高模具的抗熔焊能力，采用自制的硅藻土类绝热涂料，喷涂厚度为0．2～0．5mm。     

Experimental determination of heat transfer coefficients during squeeze casting of aluminium

Heat transfer coefficients during squeeze cast of commercial aluminium were determined, by using the solidification temperature versus time curves obtained for varying applied pressures during squeeze casting process. The steel mould/cast aluminium metal interface temperatures versus times curve obtained through polynomial curves fitting and extrapolation was compared with the numerically obtained temperatures versus times curve. Interfacial heat transfer coefficients were determined experimentally from measured values of heating and cooling temperatures of steel mould and cast metal and compared with the numerically obtained values and found to be fairly close in values. The values of the heat transfer coefficients were found to increase with increase in applied pressures and to decrease with fall of solidifying temperatures corresponding to three distinct solidification stages namely, liquidus, liquidus–solidus and solidus stages. Below temperatures of 500 °C, the effect of the increase in heat transfer coefficients with applied pressure application becomes less significant and the drop in values of the heat transfer coefficients with solidification temperatures at any applied pressures remains fairly constant. The peak values of heat transfer coefficients obtained for as-cast (no pressure application) and squeeze cast (pressure application) of aluminium are 2975.14 and 3351.08 W/(m² K), respectively. Empirical equations, relating the interfacial heat transfer coefficients to the cast aluminium surface temperatures and applied pressures at three distinct temperature range intervals, were also derived and presented.     

连铸和模铸轴承钢性能的比较

检验了连铸和模铸轴承钢棒材的低倍组织,非金属夹杂物级别,碳化物形状和分布及疲劳寿命。结果表明,模铸材的氧化物夹杂的含量、平均尺寸和最大尺寸均小于连铸材,模铸材的碳化物均匀性和接触疲劳寿命也优于连铸材,但其生产成本高于连铸材。     

钢铁零件挤压铸造的工业化应用

我国钢铁零件挤压铸造目前已经进入针对具体零件推广应用的新时期,主要生产设备和工艺技术正在向专业化方向发展,轮盘盖、叉架座和箱体类钢铁零件的挤压铸造都已获得成功应用。实践证明,该工艺适用性强、成本低、绿色度高,适于生产高品质要求的中小工件。今后的研究重点是钢铁零件挤压铸造工艺设计准则研究和从热.力.材三方耦合的角度进行专用涂料的系列化研究、模具设计的科学化和模具材料的最优化研究。     

The effect of casting temperature on the properties of squeeze cast aluminium and zinc alloys

Gravity casting and squeeze casting were carried out on an aluminium alloy with 13.5% silicon and a zinc alloy with 4.6% aluminium with different temperatures, 660, 690 and 720 °C for the former and 440, 460 and 480 °C for the latter. A top-loading crucible furnace was used to melt the alloys. The die-preheat temperatures used were 200–220 °C for the aluminium alloy and 150–165 °C for the zinc alloy. A K-type thermocouples with digital indicator were used to measure the die surface temperature and the molten metal temperature; while a 25 t hydraulic press with a die-set containing a steel mould was used to perform the squeeze casting with a pressure of 62 MPa. Tensile, impact and density tests were carried out on the specimens. It was found that casting temperature had an effect on the mechanical properties of both gravity cast and squeeze cast aluminium and zinc alloys. The best temperatures to gravity cast the aluminium alloy and the zinc alloy were 720 and 460 °C, respectively. For the squeeze casting of the aluminium alloy, the best temperature to use was either 690 or 660 °C; the former would give a better property at the top of the casting while the latter, at the bottom of the casting. However, for the squeeze casting of the zinc alloy, the best temperature was again 460 °C.     

非合金奥贝球铁耙片的研究与应用

研究了采用非合金奥贝球铁 ,经二次孕育处理、等温淬火等工艺措施生产耙片。耙片材质的组织为下贝氏体、残余奥氏体和少量马氏体。经装机实际耕作考核表明 ,使用寿命明显高于 6 5Mn耙片 ,而生产成本却大为降低 ,经济效益和社会效益明显。     

一种铁屑挤压机设计

铁屑挤压机是一种将CNC车床加工下来的铁屑、钢屑、铝屑等挤压成固定尺寸、便于转运的包块的专用设备.要求机器具有轻便、移动方便、挤压成型铁屑块便于堆放、节省空间等特点.设计中采用实验方法确定了挤压力大小.机器具有液压推出成型铁屑块功能.采用整体焊接机身,强度高,稳定性好.     

Effects of solidification control on structure and mechanical properties of cast Zn-12Al-xCu alloy blocks

ZA12 alloy is known as a high strength version of zinc alloys; however, it is difficult to produce sound cast blocks from the alloy for moulding tools by the conventional sand cast method because of its heavy gravity segregation. For a newly developed Z1208(Zn-12Al-8Cu-0.031Mg) and a convention Z1202 alloy (ZA12 alloy), two cast methods using cooling systems were adopted to produce a 700 × 500 × 300 mm³ cast block, i.e. (i) a water cooling method from outside a steel box mould, and (ii) a chill cooling method of a sand mould (bottom-opened resin bonded mould set on a large steel chilling base). The developed cast alloy produced by (i), cooled from a temperature with superheat of 20 K, showed the maximum tensile strength of 340 to 350 MPa which is equivalent t 126 to 130% of that of the highest region of the ca Z1202 alloy produced by (ii) and at the same time the minimum and acceptable porosity content was obtained. The cast Z1202 alloys produced by (i) and (ii), and the cast Z1208 alloy produced by (ii) showed severe drops in tensile strength as well as aluminium content in the regions around 100 mm from the bottom; however, the drop was minimised in the Z1208 alloys by the method (i).     

21CrMo10钢离心铸造管坯的热疲劳性能研究

系统研究了21CrMo10钢离心铸造管坯的耐热疲劳性能。结果表明,21CrMo10钢离心铸造管坯由于其热疲劳性能较差而不宜用作管模。此外,还分析了锻制管模与离心铸造管坯热疲劳性能存在差异的原因。