共查询到20条相似文献,搜索用时 31 毫秒
1.
To prevent galling in backward extrusion of deep holes, an extrusion method utilizing a servo press and a punch having an internal channel for supplying liquid lubricant is proposed. On the servo press, the punch is pushed into the billet in a manner combining pulsed and stepwise modes. The lubricant is sucked into the formed hole through the internal channel during the retreat motion of the punch. Appropriate punch ram motions for preventing galling are determined from the surface observation of the formed hole. The maximum aspect ratio of the hole attained by the proposed method is discussed. 相似文献
2.
Ryo Matsumoto Jae-Yeol Jeon Hiroshi Utsunomiya 《Journal of Materials Processing Technology》2013,213(5):770-778
A method for keeping lubrication in the backward extrusion of deep holes for lightweight structural components is proposed utilizing a servo press and a punch with an internal channel for liquid lubricant supply. The punch is pushed into the specimen with a servo press in a manner that combines pulsed and stepwise modes. Sufficient liquid lubricant is periodically supplied to the deformation zone through the internal channel upon the retreat of the punch. The appropriate punch motions for prevention of galling of the formed hole for extrusion ratios in the range 1.07–1.80 were determined in the proposed forming method using a servo press. Furthermore, the proposed method was found to produce the formed holes with high shape accuracy. The shape accuracy of the formed hole is discussed with experimental and finite element simulation results in terms of lubrication state and temperature change. 相似文献
3.
Ductility of a magnesium alloy in warm forging with controlled forming speed using a CNC servo press
The influence of press ram motion on forging performance for magnesium alloys was examined at elevated temperatures using an upsettability test on a CNC servo press. The forging limit of a wrought AZ31B (Mg–3 mass%Al–1 mass%Zn) magnesium specimen, forged using applied deceleration of the press ram motion, was found to be 30% higher than the forging limit achieved without press ram motion control. A finite element analysis was conducted to model the experimental results. The calculated temperature distribution was relatively uniform during upsetting with decelerated ram motion, and the maximum equivalent strain was maintained at a low level. Experimental and simulation results suggested that the influence of the press ram motion on the ductility of the Mg specimen could be described by a strain localization model. Furthermore, the ductility of Mg specimens during decelerated ram motion was improved in backward extrusion. 相似文献
4.
Ryo Matsumoto Takahiro Chida Shinji Hanami Hiroshi Utsunomiya 《Journal of Materials Processing Technology》2014,214(10):1995-2001
A plastic joining method for fixing bars and hot plates, called “indentation plastic joining”, was carried out using a servo press with press ram speed control. The influence of the press ram motion control on the indentation joining characteristics of an aluminum alloy bar and plate was examined. The accelerated ram motion was effective in reducing the bar indentation pressure by approximately 15% and the bonding strength of the indented bar–plate was improved by approximately 7%. The bonding mechanism underlying the indention joining method under press ram motion control is discussed in terms of the seizure of the plate and the mechanical clamping associated with the process. It is found that the accelerated ram motion produces heavier seizure at the indented bar–plate interface, whereas the decelerated ram motion reduces the degree of the seizure. 相似文献
5.
基于伺服压力机的AZ31镁合金反挤压成形 总被引:1,自引:0,他引:1
为探讨挤压速度模式对AZ31镁合金杯形件反挤压成形的影响,对伺服压力机反挤压成形进行有限元分析与实验,并与普通曲柄压力机和液压机反挤压成形进行比较。有限元分析结果表明,反挤压终了阶段,伺服挤压和液压挤压最大损伤值分别为3.41和3.30,远低于普通挤压的最大损伤值6.08;挤压过程中杯形件最大温差伺服挤压为45℃,而普通挤压和液压挤压分别为127℃和70℃。实验结果表明,在1100kN伺服压力机上,采用伺服挤压模式,可成功获得壁厚为3mm的AZ31镁合金反挤压杯形件,而采用普通挤压模式,在杯形件边缘则出现破裂。实验与有限元分析结果基本吻合。 相似文献
6.
分析了金属反挤压时内部各质点的流动规律与空心六角法兰面螺栓的结构特征,其最大特点是在保证同心度为0.2 mm的前提下,成形孔径比高达6.5的深孔,并初步设计4工位冷挤压成形工艺。运用DEFORM-3D重点研究了工序3深孔预成形过程,在刚性平移区选取4个点,利用点追踪方法,以所选点的径向偏移量为评价标准,研究了圆锥凸模、平底锥形凸模、球头凸模和平底凸模4种凸模结构对深孔同心度的影响程度。同时,对比成形初期金属流动情况、行程载荷,综合结果表明:圆锥凸模能在较低的成形载荷下得到良好的金属流线,有利于提高制件同心度。最后,通过JBF-19B-4S螺栓冷镦机进行试模,生产出成形饱满、无缺陷,且同心度达到设计要求的制件,为深孔类零件冷挤压成形提供了一种参考。 相似文献
7.
《金属学报(英文版)》2017,(11)
The paper presents a new extrusion method,alternate forward extrusion,in which the punch was replaced with double-split structures so as to achieve the grain refinement for material near the interface of double-split structures.The results showed that the unique loading mode made metal flow sequence and behavior significantly changed during alternate forward extrusion.The additional shear deformation produced by the double-split punch structures resulted in a refining effect on the microstructure of the blank,which was then further refined during flow through the die orifice owing to shear deformation.Compared with the conventional extrusion,the recrystallization process in the alternate forward extrusion process produced grains that were smaller and more homogeneous in size.The recrystallization process was more abundant,and the dislocation density was significantly increased.It can be concluded that the alternate forward extrusion process could achieve fine-grained strengthening,which provided technical support and scientific guidance for the engineering application of magnesium alloy extrusion forming technology. 相似文献
8.
Springback behaviour in bending of ultra-high-strength steel sheets using CNC servo press 总被引:4,自引:0,他引:4
The springback behaviour of ultra-high-strength steel sheets in bending was investigated under controlled conditions using a CNC servo press. Although the ultra-high-strength steel sheets are attractive in reducing weight of cars, the amount of springback of the ultra-high-strength steel sheets in the forming is very large due to high strength. The CNC servo press has the function of accurately controlling the motion by two servo motors. The effects of the material, the finishing reduction in thickness, the forming speed and the holding time at the bottom dead centre on the amount of springback in V-shaped bending were examined. The scatter of the springback for the ultra-high-strength steel sheets was improved by using real thickness and not nominal thickness of each individual sheet in the control of the punch stroke. The amount of springback for the ultra-high-strength steel sheet in the V-shaped bending was much larger than that for the mild steel sheet, and the amount was decreased by the finishing reduction in thickness direction because of uniform stress distribution. The effects of the forming speed and the holding time at the bottom dead centre were small. The amount of springback for the steel sheets was almost proportional to the ratio of the tensile strength to the elastic modulus. 相似文献
9.
伺服压力机是近年来塑性成形领域最重大的创新之一,将伺服压力机以及基于伺服压力机的成形工艺统称为伺服成形技术.简要介绍了伺服成形技术的特点和目前的应用情况,重点论述了该技术当前的若干发展新动向,包括伺服压力机设计方法的研究、新型功能部件和储能技术开发、滑块运动路径设计与优化、伺服成形机理及成形过程的数值模拟、智能制造中的... 相似文献
10.
Mechanical servo press technology for metal forming 总被引:3,自引:0,他引:3
Recently several press builders developed gap and straight-sided metal forming presses that utilise the mechanical servo-drive technology. The mechanical servo-drive press offers the flexibility of a hydraulic press (infinite slide (ram) speed and position control, availability of press force at any slide position) with the speed, accuracy and reliability of a mechanical press. Servo drive presses have capabilities to improve process conditions and productivity in metal forming. This paper reviews the servo press designs, servo-motor and the related technologies, and introduces major applications in sheet metal forming and bulk metal forming. 相似文献
11.
12.
13.
14.
15.
重型汽车推力杆球头的精密挤压工艺是一项新工艺,为改善球头挤压成形时的整体质量,利用Deform-3D数值模拟软件,研究模具间隙大小d及模口圆角r对球头变形过程中的流动特性及成形效果的影响,并对两者进行优化。在有限元分析过程中,改变凸凹模间隙大小及模口圆角尺寸,模拟在一定的边界条件(毛坯温度、模具温度、冲头速度)下,模具结构(凸凹模间隙、模口圆角)变化对球头挤压力、成形效果、应力分布及模口处金属流速等因素的影响,并通过物理模拟试验验证。研究结果表明:当凸凹模间隙d=2.5mm,模口圆角尺寸r=6mm时,球头整体质量最佳。 相似文献
16.
K. Durst S. HofmannB. Backes J. MuellerM. Göken 《Journal of Materials Processing Technology》2010,210(13):1787-1793
The microimprinting behaviour of a wide variety of materials with grain sizes ranging from 25 nm up to a few mm was studied, using a flat punch indenter with a circular cavity with a diameter of 5 μm and a cavity line width of 350 nm. The flat punch die was fabricated by focussed ion beam machining. The imprinted ring geometry has been evaluated using atomic force microscopy in terms of extrusion height, relative to residual imprinting depth. The experimental work was complemented by Finite Element Analysis (FEA) of the forming process, using experimentally determined stress–strain data of the imprinted materials as input for the finite element simulations. Even so only macroscopic properties of the materials have been used for the modelling, both experiment and simulation yield comparable results. However, the relative extrusion height from FEA are much larger compared to the experimental results. It is found that grain size and the subsequent work hardening behaviour of the material has a strong influence on the local flow behaviour during imprinting. Nanocrystalline materials with nearly ideal-plastic deformation behaviour exhibit the best formability. The influence of the work hardening behaviour on the local flow of the material during microimprinting is moreover confirmed by imprinting of a pre-strained material. A reduction in the work hardenability of the material leads to an increasing microflow during microimprinting. 相似文献
17.
针对锚固装置中的锚套典型件,设计了自动化热挤压工艺。试生产中出现锻件质量不稳定和模具寿命太低等问题,导致难以实现自动化生产。质量不稳定的表现是锻件同轴度超差且无规律,模拟分析了预锻同轴度对成形凸模等效应力和偏移量的影响,并通过提高坯料尺寸精度和调整镦粗高度解决了同轴度的问题,使锻件同轴度从最大Φ0.86 mm减小到Φ0.4 mm以内,确保了锻件质量稳定合格。成形凸模失效的表现是磨损,模拟分析了不同材料、润滑系数、凸模长径比对模具磨损量的影响,并通过实验确定:润滑剂采用水基石墨,凸模材料采用3Cr2W8V钢,将模具寿命从1500件提高到10000件以上,可以连续生产20 h以上。最终实现班产不换模具且无废品,达到自动化生产的要求。 相似文献
18.
《Journal of Materials Processing Technology》2014,214(7):1379-1387
Load pulsation using a servo press was applied to a forging process of a stainless steel sheet having high flow stress and adhesive bond. The effect of the load pulsation on the deformation behaviour of a stepped stainless steel part was examined. The cavity and rollover formed on the upper surface and on the bottom boss surface, respectively, are also decreased by the load pulsation. In the load pulsation, gaps for feeding a liquid lubricant are formed around edges and corner of the deforming plate by a difference in elastic recovery between the die and plate in each release of load, and thus these regions are automatically re-lubricated. The re-lubrication function was improved by immersing the plate in the lubricant during forging. The re-lubrication function for low-cost tool steel was higher than that high-cost tungsten carbide because of smaller Young's modulus. 相似文献
19.