加工小深孔的珩磨头

(1)工件特点 某产品的液压缸筒 (图 1),材料 45号钢,调质 22～ 28HRC,总长 2000mm,内孔 20H7,深径比达 100,是典型的细长深孔零件。该零件深孔钻削加工后,为了达到内孔表面粗糙度 Ra0.4μ m的要求,我们设计制造了结构较为简单的小深孔珩磨头 (图 2),在工厂自制的深孔珩磨机上进行内孔珩磨,取得了满意的加工效果,内孔表面粗糙度低于 Ra0.4μ m,各部位尺寸误差不大于 0.01mm。 (2)珩磨头结构 由于工件为单件生产,本体采用 45号钢,调质 28～ 33HRC,珩磨杆用 16mm的 45号钢冷拉钢棒,两者之间采用铰链式联接,使本体能较…     

简易小深孔珩磨头

某产品的液压缸筒(图1),材料为45钢,调质处理硬度22～28HRC,总长2000mm,内孔为φ20H7,深径比达100,是典型的细长深孔零件。工件内孔经深孔钻削后,为了达到内孔表面粗糙度R_α0.4μm的要求,我们设计制造了小深孔珩磨头(图2),取得了满意的效果,内孔尺寸差不大于0.01mm,表面粗     

深孔的滚压加工

本厂对自卸汽车液压缸筒深孔进行滚压，经液压后的内孔表面硬度可达HB228以上，孔的尺寸精度和位置精度均能达到设计要求，粗糙度可达Ra0．2μm。一、滚压头结构设计液压缸简如图1所示。图1液压缸筒工件材料为35钢厚壁无缝钢管，其孔径与长度之比大于5，以往采用镗削和珩磨等工艺手段加工均达不到设计要求，故我厂设计制造滚压头（结构如图2所示），采用滚压加工获得成功。图2滚压夹具本滚庄头的结构采用使滚柱和心轴锥度相同的全浮式，其特点是：1．心轴5、浮动支架3、锥形滚柱11均采用GCr15轴承钢，并经高频淬火处理，以提高使用寿命；2…     

大孔径缸筒滚压

液压支架关键零件之一的缸体需要量很大。这种缸体的材料为27SiMn,调质硬度HB=240～280,内孔尺寸精度是H10,圆柱度0.046mm,表面粗糙度Ra0.8μm。图1所示为液压支架缸体之一。采用原来加工方法是精镗后珩磨,产品质量不高,效率很低。近几年来,我厂陆续研制和试验成功的φ125mm、φ160mm及φ230mm等缸筒滚压头,以滚压代替了珩磨工艺。缸体质量完全达到图纸要求,并提高工效近10倍,节省了大量的工具费用;同时操作简单、维修方便。     

在车床上抛光箱体内孔

我公司是国家生产烟草机械的定点企业,主要生产烟丝处理段的各部分机械。根据市场的要求,我公司又开发了一种新型烘丝机———微波烘丝机,其中的箱体我们采用在车床上精密抛光,解决了内孔表面粗糙度值低的难题。1·零件分析如图1所示为微波烘丝机的箱体,材料为ZG310-570,外形尺寸为1150mm×420mm×470mm,内孔尺寸为360H9,表面粗糙度值Ra=0·8μm,工件切削为断续切削;转子为焊接结构件,外圆尺寸为360d9,要求转子与箱体配合间隙为0·2mm。从工件材质来说传统加工方法内孔表面粗糙度值达到Ra=0·8μm不可能,但内孔表面粗糙度值Ra必须达…     

提高轴瓦内孔加工精度的对策（上）

大功率柴油机轴瓦(见图1)分留镗量瓦和互换瓦两种。留镗量瓦内孔的质量要求:壁厚δ公差0.03mm;内孔表面粗糙度值Ra3.2μm。互换瓦内孔的质量要求:壁厚δ公差0.15mm;内孔表面粗糙度值Ra0.4μm。在两对接面附近30°范围内逐渐减薄0.05～0.07mm。互换瓦比留镗量瓦内孔的精度要求高:壁厚δ公差从0.03mm降为0.015mm;内孔表面粗糙度值从Ra3.2μm降低到Ra0.4μm;轴瓦内孔由正圆变成椭圆。我厂原只生产留镗量轴瓦,使用时在柴油机上将轴瓦内孔镗成成品尺寸。其最大优点是减小机体轴瓦座孔之间的同轴度误差。但随着机体质量的不断提     

液压缸体的光整精加工

在我厂开发的民品中,液压缸体占据着一定的数量和位置,是重要的液压元件之一。缸体加工质量的优劣,直接影响着各种产品的使用性能和可靠性。因此,对缸体的机械加工进行探讨就很有必要。缸体的内表面要求有较高的加工精度和低表面粗糙度。尺寸一般为φ110～φ160mm,精度为H8～H10,圆柱度为0.018～0.05mm,表面粗糙度为Ra0.4μm,长度为850～1100mm,长径比为(L/D)≥8(见图1),这些缸体零件均属于筒形高精度深孔加工件。     

提高缸筒加工精度及性能的研究

缸筒是液压缸的主体,是液压系统加工难度高的关键性精密零件,缸筒质量的优劣将直接影响到产品的使用性和可靠性。液压缸缸筒制造加工技术要求：缸筒内径一般采用H7或H8;表面粗糙度Ra值一般为0116～0．32μm；缸筒内径圆度、锥度、圆柱度不大于内径公差的1／2；缸简直线度公差在5mm长度上不大于0．03mm；缸筒端面对内径的垂直度在直径100mm上不大于0．04mm。     

车床用大型内孔抛光装置

在车床上进行长度为5000～6000mm,直径为230～350mm的内孔抛光,表面粗糙度值Ra=1．6μm,材料为1Cr18Ni9Yi的无缝钢管。由于毛坯的孔不圆,就设计制造了内孔抛光的工装（见附图）,在较短的时间,在车床上将内孔抛光达到了要求。     

深孔强力珩磨技术及应用

深孔珩磨是深孔精加工的主要手段,目前,存在的主要瓿是珩磨效率很低,珩磨表面粗糙度较高,在加工难切削材料时尤为突出。本研究针对钛合金材料,选用不同磨料和磨削用量对钛合金深孔珩磨机理进行了试验研究。研究结果, 粗珩磨量可达到0．003毫米／双行程（孔深为2000－3000mm),精珩磨孔表面粗糙度可达到Ra0.4μm,充分体现了该深孔强力珩磨技术磨削效率高、表面粗糙度低的特点,还介绍了深孔强力珩磨工具的改进。     

热轧钢管坯料的选择

依据热轧无缝钢管的外径和壁厚允许偏差,提出了合理选择镗滚压加工液压缸筒所用热轧无缝钢筒坯料的方法,并给出了常用缸筒坯料选择表。     

无缝钢管双向等长缩径时壁厚变化的试验研究

利用普通液压机对初始直径为φ102mm、壁厚为4.5mm的20号热轧无缝钢管试件进行四次双向等长缩径,管坯试件上端润滑,下端不润滑.通过测量试件周向四个方向上的初始壁厚以及缩径后端部及均匀区的壁厚及外径,揭示出缩径后管坯壁厚在周向上变化不均匀的现象,给出了管坯初始壁厚偏差、润滑条件对各次缩径后管坯壁厚变化的影响以及管坯法向应变与周向应变比值的变化规律,解释了缩径中出现的管坯内壁周向起皱及管端轴向开裂等特殊现象,以利于实际生产中合理限定无缝管坯的初始壁厚偏差并对其进行正确润滑,从而得到壁厚变化较为均匀的合格制件.     

冷旋压加工对高压气瓶性能的影响

钢坯冲压气瓶存在内外观质量差、壁厚偏差大、空瓶质量重、横向冲击韧性低等问题。通过对34CrMo4气瓶钢和34CrMo4－H高强度气瓶钢冲压制造的筒形料坯三轮旋压工艺分析及旋压成形试验,试验研究冷旋压对瓶坯内外表面质量和尺寸的影响;并采用调质处理,试验研究冷旋压加工对材料力学性能和金相组织的影响。试验结果表明,冷旋压气瓶的内外表面质量和尺寸精度明显优于冲压气瓶,延伸率提高约0．5％,横向冲击韧性提高10．5 J／cm2以上,带状组织结构有一定改善。     

计入粗糙度的液压缸仿生微织构耦合效应研究

在间隙密封液压缸缸筒的内表面构造仿生菱形微织构,研究计入液压缸摩擦副表面粗糙度与表面微织构对液压缸缸筒内表面摩擦润滑性能的耦合影响。利用等效流量法求解表面微织构与表面粗糙度的耦合效应,同时以液压缸常用材料45钢为试件开展摩擦学试验,并对试验结果和仿真结果进行比较。研究结果表明:液压缸摩擦副的表面粗糙度与表面微织构耦合作用非常明显,合适的表面粗糙度和表面微织构尺寸,可使液压缸缸筒内表面从混合润滑状态转变为流体润滑状态,从而增大缸筒内表面的动压润滑效应;缸筒内表面的菱形微织构形貌存在最优组合,使得液压缸缸筒内表面的摩擦因数最小、润滑性能最好。     

The break-in stage of cylinder-ring wear: A correlation between fired engines and a laboratory simulator

The wear of the piston ring-cylinder wall contact area in fired engines has not been satisfactorily simulated in bench testers so far. This paper reports the development of a successful test device in which the same progression of surface change occurs as in fired engines. These changes were observed by microscopy, by hardness indentations and by the use of the stylus roughness tracer. The test device uses ring and cylinder segments and it oscillates at 350 cycles min^-1 over a stroke of 19 mm. It is apparently not necessary to duplicate the temperature, atmosphere, fluid film thickness and other obvious conditions in an engine to achieve simulation. At least, the materials in the engine were not affected by the conditions in the engine that were not duplicated in the laboratory tester.The purpose in developing the tester was to study the role of the honed roughness pattern found on most cylinder walls. Several engine manufacturers attempt to achieve “fplateau honing”. No manufacturer polishes new cylinder walls. The reason for the honed roughness is to allow a high wear rate, without catastrophic scuffing, in locations of high stress between poorly conforming parts.     

Experimental and numerical research on magnetic pulse forming of DP600 high-strength steel with driver sheet

This study aims to investigate the effect of the three cutting parameters (rotation, feed rate, and number of tool strokes) on the values of roughness (Rk, Rpk, Rvk, Mr1, Mr2, Rp/Rt ratio, and Vo) in flexible honed crankcase cylinder of hermetic compressors. The study was based on a full factorial design 2 × 2 × 3, where the rotation and the feed rate were investigated in two levels and the number of tool strokes in three levels. The cylinders were initially honed using a multi-spindle honing machine, Gehring model. A set of three honing tools was used each with two strokes, the first for roughing (120 mesh), the second for semi-finishing (270 mesh), and the third for finishing (600 mesh). For conventional honing (CH), the depth of the cut and the feed rate were kept constant. The flexible honing process was carried out after conventional honing (C+FH) in a CNC milling machine using a Silicon Carbide flex hone tool 800 mesh and 24.2 mm nominal diameter considering 12 different cutting conditions. An electromechanical surface roughness tester was used to carry out roughness measurements. The measurement uncertainty was assessed following the recommendations of the GUM-JCGM 101. The analysis of variance (ANOVA) technique was applied, and it was observed that the number of the tool strokes was the factor that contributed the most to the improvement of the surface finish of the cylinders.     

The Effects of Roughness on Piston Ring Lubrication—Part II: The Relationship between Cylinder Wall Surface Topography and Oil Film Thickness

In this investigation, a theoretical piston ring/cylinder wall model has been utilized to study the dependence of the oil film thickness on surface roughness shape and amplitude, as well as on engine operating conditions. For a given roughness, a plateau honed cylinder wall surface was found to produce a thinner oil film. It has also been shown that the small crosshatch angle used when honing the cylinder wall produces surfaces that enhance hydrodynamic action.     

哑铃型高精度筒体制造工艺研究

介绍了液力机械产品关键零件高精度哑铃型双相不锈钢筒体的制造工艺研究内容,重点解决了高精度筒体制造的四大工艺难点,即确定筒体內孔离子氮化后的最大变形量;在变形的筒体上创建一个科学合理的高精度工序基准;最大限度地克服加工过程中相关干扰因素的影响;保证筒体外圆和内孔的同轴度、内孔圆柱度及表面粗糙度等精度要求。     

双向热定心机的设计及其热定心误差分析

介绍了无缝轧管机组管坯双向热定心机的设计原理和定心误差分析。所设计的双向热定心机的主要特点是：采用全液压驱动，高强度机架，具有适应不同定尺长度的能力，首次实现了定心孔深度可调、定心速度可调，双向定心精度达到4mm。该双向热定心机及其技术，为国内外生产无缝钢管管坯热定心提供了成功的经验，具有重大效益和推广使用价值。     

Roughness variability in the honing process of steel cylinders with CBN metal bonded tools

Herein are presented roughness results of honing of steel cylinders with cubic boron nitride (CBN) abrasive tools. Different honing parameters such as honing stone pressure against the workpiece, tangential speed of the honing head as well as grain size of the abrasive stone were varied in order to determine their influence on the surface roughness of cylinders. Four different strategies were implemented to measure and characterise roughness of inner surfaces of honed steel cylinders. The variability in results obtained with each strategy is compared. The first three strategies consist in measuring roughness at one, three or nine points, respectively, which are uniformly distributed over a circumference located at one of the cylinder ends. The fourth strategy is based on the third one: it entails measuring roughness at nine points, and then subsequently filtering results to eliminate any extreme roughness value lying outside the boundaries set by Chauvenet's criterion. At each point of measurement, roughness is measured in the direction of the cylinder generatrix. It was verified that the larger the number of measurement points, the lower the variability in roughness values obtained. Therefore, it is recommended to make at least nine measurements per cylinder and to filter values to avoid any non-representative, outlier value. The variability in these values was quantified firstly according to relative differences. Secondly, variability was quantified by means of the coefficient of variation which provides smaller values than the relative difference, although less intuitive and less direct.