Precision surface finish of the mold steel PDS5 using an innovative ball burnishing tool embedded with a load cell

A load-cell-embedded burnishing tool has been newly developed and integrated with a machining center, to improve the surface roughness of the PDS5 plastic injection mold steel. Either the rolling-contact type or the sliding-contact type was possible for the developed ball burnishing tool. The characteristic curves of burnishing force vs. surface roughness for the PDS5 plastic injection mold steel using the developed burnishing tool for both the rolling-contact type and the sliding-contact type, have been investigated and constructed, based on the test results. The optimal plane surface burnishing force for the PDS5 plastic injection mold steel was about 420 N for the rolling-contact type and about 470 N for the sliding-contact type, based on the results of experiments. A force compensation strategy that results in the constant optimal normal force for burnishing an inclined surface or a curved surface, has also been proposed to improve the surface roughness of the test objects in this study. The surface roughness of a fine milled inclined surface of 60 degrees can be improved from R_a 3.0 μm on average to R_a 0.08 μm (R_max 0.79 μm) on average using force compensation, whereas the surface roughness was R_a 0.35 μm (R_max 4.56 μm) on average with no force compensation.     

聚晶金刚石刀具切削各向同性热解石墨过程中的磨损机理

针对各向同性热解石墨切削过程中刀具磨损过快的问题,采用聚晶金刚石（PCD）刀具进行了切削加工试验。研究了切削过程中PCD刀具的磨损形式、磨损规律以及刀具磨损对表面加工质量的影响。试验结果表明：PCD刀具磨损主要发生在后刀面上,磨损形式为磨粒磨损和氧化磨损。磨损区域可以分为平行沟槽和严重磨损两种形貌。初始磨损阶段,磨损带长度急剧增大,并在切削1200m后进入正常磨损阶段。切削过程中还出现了石墨切屑在磨损区域的黏附堆积和刀具崩刃现象。切削初期,随着切削距离的增大,加工表面粗糙度值急剧增大,切削距离为600m时表面粗糙度达到最大值1.7μm。     

PCD刀具加工氮化硅基工程陶瓷的合理切削速度

从切削速度对切削力、已加工表面粗糙度、刀具耐用废、切削长度的影响的角度，探讨了聚晶金刚石刀具（PCD）切削加工氮化硅（Si_3N_4）基工程陶瓷时合理切削速度的选择问题。指出，在一定的切削条件下，当切削速度v=30～40m／min时，可获得良好的综合效益。     

PCD刀具几何参数对铝合金加工表面粗糙度的影响

文中研究了PCD刀具在不同的刀具几何参数下车削铝合金的加工表面粗糙度.分别改变刀具的前角、后角和刀尖圆弧半径3个几何参数做单因素切削试验,试验后利用表面轮廓仪测量工件的表面粗糙度,最后分析刀具几何参数对加工表面粗糙度的影响.     

Simulation of the burnishing process on real surface structures

Burnishing is a finishing manufacturing process that provides the required surface integrity of metal parts. Precise process simulation enables optimization to guarantee the quality of the product. A literature review showed that most researches in this field have used an idealized smooth surface for simulations and have not considered the influence of surface roughness on the simulation results. However, for burnishing processes, the initial roughness has a measurable effect on the simulation quality. Hence, an innovative approach for the preparation of the FEM process model was developed. The approach based on reverse engineering. Using 3D scanning, models of the workpiece and the tool were created and imported in the process model. The developed approach was validated through a case study. The results of the simulation with surface roughness demonstrate a better compatibility to the real process than the results of the same simulation on the idealized surface. Hence, using this approach, it is possible to create a precise model of the process and achieve more qualitative result of the burnishing simulations.     

聚晶金刚石刀具的断屑槽尺寸参数设计

为解决聚晶金刚石(PCD)刀具在铝合金材料切削过程中的切屑缠绕问题,在PCD刀具的前刀面上设计了断屑槽.通过对切屑受力过程和断屑槽断屑机理的分析、切削几何关系的推导和有限元切削仿真实验,提取了5个PCD刀具断屑槽参数,即棱带宽度、倾角、反屑角、槽宽和反屑面转角.建立了PCD刀具断屑槽棱带宽度和反屑角的计算公式;改进了槽...     

SURFACE INTEGRITY OF HIGH-SPEED FACE MILLED Ti-6Al-4V ALLOY WITH PCD TOOLS

This study is focused on the machined surface integrity of Ti-6Al-4V alloy using polycrystalline diamond (PCD) tools under wet milling condition. The surface integrity in terms of surface roughness, surface topography, microhardness, microstructure, and metallurgical alternations is investigated. The observations and conclusions are primarily focused on the effect of cutting speed (250–2,000 m/min) on the surface and subsurface of the machined Ti-6Al-4V. Experimental results show that machined surface integrity of Ti-6Al-4V alloy is sensitive to the variation of cutting speeds. Obvious machining (feed) marks can be found on the machined surfaces. Micro hardness examinations showed 5–20% hardening of the top machined surfaces than the bulk material. The analyses of microstructure and metallurgical alternations reveal that slight subsurface microstructure alteration such as plastic deformation on the subsurface and no phase transformation were observed. The evolution of crystallographic texture induced by the intense plastic deformation of the machined surface should be responsible for the modifications of the peak intensity radios in XRD patterns as well as higher peak broadening crystal structures.     

适用于多种材料阵列微槽加工的聚晶金刚石铣槽刀制备

结合金刚石飞切刀具和锯片,设计了具有特定形状、尺寸和角度参数的铣槽刀,并采用电火花线切割加工方法制造出了PCD铣槽刀;利用自制PCD铣槽刀进行微细铣削试验,制备出了加工质量良好的典型阵列微槽结构。     

Application of Taguchi and response surface methodologies for surface roughness in machining glass fiber reinforced plastics by PCD tooling

This paper discusses the use of Taguchi and response surface methodologies for minimizing the surface roughness in machining glass fiber reinforced (GFRP) plastics with a polycrystalline diamond (PCD) tool. The experiments have been conducted using Taguchi’s experimental design technique. The cutting parameters used are cutting speed, feed and depth of cut. The effect of cutting parameters on surface roughness is evaluated and the optimum cutting condition for minimizing the surface roughness is determined. A second-order model has been established between the cutting parameters and surface roughness using response surface methodology. The experimental results reveal that the most significant machining parameter for surface roughness is feed followed by cutting speed. The predicted values and measured values are fairly close, which indicates that the developed model can be effectively used to predict the surface roughness in the machining of GFRP composites. The predicted values are confirmed by using validation experiments.     

聚晶金刚石复合片高频感应钎焊的试验研究

采用部分不等间隙接头设计方案和Ag Cu Zn Cd钎料 ,通过在空气中高频感应加热 (钎焊温度 6 90℃ ) ,成功实现了PCD复合片与 4 5钢刀杆的高强度焊接。根据钎焊试验结果 ,分析了钎料润湿性、钎焊温度、恒温保持时间和钎焊金属表面粗糙度对接头强度的影响     

脉冲光纤激光制备聚晶金刚石疏液表面的研究

针对聚晶金刚石（PCD）表面,提出了一种经济、高效、可控制备多种微观结构的激光加工方法,与低表面能处理技术相结合,可实现对表面特性的有效调控。利用激光表面织构化方法在PCD表面制备出含有沟槽和锥形凸起的微纳结构,并分析了单脉冲能量和扫描速度对微观结构形貌和特征尺寸参数的影响;将激光织构化的PCD表面进行氟化处理,分析PCD表面微观结构对疏水和疏油性的影响规律。结果表明：随着单脉冲能量的增加或扫描速度的降低,沟槽深度、山脊间距和表面粗糙度随之增大;低表面能处理后,PCD表面与水和乳化剂的接触角分别在93°~149°和102°~134°范围内变化,由此可实现对PCD表面不同润湿性的控制。另外,分析了PCD表面微观结构的形成机理,并探讨了微观结构参数对疏水疏油性能的影响规律。     

Automated surface finishing of plastic injection mold steel with spherical grinding and ball burnishing processes

This study investigates the possibilities of automated spherical grinding and ball burnishing surface finishing processes in a freeform surface plastic injection mold steel PDS5 on a CNC machining center. The design and manufacture of a grinding tool holder has been accomplished in this study. The optimal surface grinding parameters were determined using Taguchi’s orthogonal array method for plastic injection molding steel PDS5 on a machining center. The optimal surface grinding parameters for the plastic injection mold steel PDS5 were the combination of an abrasive material of PA Al₂O₃, a grinding speed of 18000 rpm, a grinding depth of 20 μm, and a feed of 50 mm/min. The surface roughness R_a of the specimen can be improved from about 1.60 μm to 0.35 μm by using the optimal parameters for surface grinding. Surface roughness R_a can be further improved from about 0.343 μm to 0.06 μm by using the ball burnishing process with the optimal burnishing parameters. Applying the optimal surface grinding and burnishing parameters sequentially to a fine-milled freeform surface mold insert, the surface roughness R_a of freeform surface region on the tested part can be improved from about 2.15 μm to 0.07 μm.     

PCD刀具金刚石砂轮刃磨表面质量及其对加工工件表面质量的影响

对树脂结合剂、金属结合剂和陶瓷结合剂金刚石砂轮刃磨PCD刀具的过程特点进行了比较分析,认为陶瓷结合剂金刚石砂轮刃磨PCD刀具可以得到较好的刃磨表面质量且刃磨效率最高;同时对加工工件表面的形成过程进行了分析,认为PCD刀具的后刀面表面质量是最重要的影响因素。     

PCD刀具几何参数对铝合金切削力的影响

研究了不同几何参数的PCD刀具车削铝合金时切削力的变化规律。分别改变刀具的前角、后角和刀尖圆弧半径三个几何参数进行单因素切削试验,通过Kistler测力仪获取三向切削力,通过所获试验数据分析了金属切削过程和PCD刀具几何参数对切削力的影响。     

粗粒度人造多晶金刚石用作超精切削加工刀具材料的可能性

用粗粒度的人造多晶金刚石刀具进行车削试验．从理论和实验两方面对此种刀具切削形成超精密加工表面的机理进行了研究，提出了＂微量切削过程中．人造多晶金刚石刀具多点切削、单点成形＂的观点。在与天然单晶金刚石刀具的切削试验结果以及天然单晶金刚石刀具超精切削加工生产条件进行对比之后，验证了粗粒度人造多晶金刚石用作超精切削加工刀具材料的可能性。     

PCD刀具车削超硬铝合金的切削性能研究

以Al7075-T6为加工对象,通过车削试验对PCD刀具车削超硬铝合金的三向动态切削力和表面粗糙度展开研究,建立基于BP神经网络的切削力和表面粗糙度预测模型。结果表明:随着切削用量三要素的变化,切削力变化显著;对于表面粗糙度而言,背吃刀量、进给量和切削速度之间无交互作用;基于L-M优化算法的BP神经网络对样本的拟合度高,且对切削力和表面粗糙度的预测精度高。     

聚晶金刚石的超声振动研磨机理研究

在分析聚晶金刚石 (PCD)材料的微观结构和去除机理的基础上 ,对PCD材料的超声振动研磨机理进行了深入研究。通过试验证明 ,采用超声振动研磨PCD可显著提高研磨效率 ,认为研磨轨迹的加长和超声振动的脉冲力作用是提高研磨效率的主要原因。     

特种材料深孔精加工工艺研究

为解决特种材料在深孔加工过程中出现振动较大且排屑不畅、而导致表面精糙度值达不列要求的问题,着重对影响表面粗糙度值的刀具前角、后角、走刀量、切削速度四个因素进行分析并通过实验进行验证,得到了刀具几何角参数和切削用量范围.结果表明,刀具的前角20°～35°、后角6°～12°、走刀量为0.07 ～ 0.12 mm且切削速度小于225 r/min时,可以保证特种材料深孔精加工的表面精糙度值.     

T6热处理对SiC_p/Al复合材料高速铣削加工性的影响

使用聚晶金刚石(PCD)刀具,在切削速度为1200m/min下对碳化硅颗粒增强铝基(SiCp/Al)复合材料进行铣削加工试验,研究SiCp/Al复合材料经T6热处理后对其高速铣削加工性的影响。结果表明:经T6热处理后,切削力/切削温度明显高于未热处理材料,切屑锯齿形明显,加工过程不稳定性增加,刀具承受冲击作用增大,导致PCD刀具发生较严重的崩刃、剥落、冲击裂纹等磨损形式,从而刀具使用寿命显著低于高速铣削未热处理材料。T6热处理材料高速铣削表面粗糙度Ra/Rz值一般低于未热处理材料,其加工表面变质层深度也显著低于未热处理材料,加工表面存在较少的坑洞、微裂纹、基体撕裂、基体涂覆等加工所致缺陷。     

Effect of a combined machining/burnishing tool on the roughness and mechanical properties

Burnishing is a cold working surface treatment process in which plastic deformation of surface irregularities occurs by exerting pressure through a very hard and a very smooth roller or ball on a surface to generate a uniform and work‐hardened surface. This treatment occurs generally after the machining process. In this study, a new combined machining/burnishing tool is designed and is fabricated. This tool allows for generating simultaneously the machining (turning) and the burnishing of the cylindrical surface using a turning machine. First, turned surfaces at different conditions, sketches, finishing and half finishing were performed using only the cutting tool. The evolutions of a surface roughness parameter and the technological time relative to every test condition have been investigated. Second, using the combined machining/burnishing tool at coarse conditions, the evolutions of the surface roughness and the technological time have been also investigated. A comparison among the parameters obtained under different machining conditions and those obtained using the combined machining/burnishing tool has been carried out. Moreover, the analyses of the layers obtained on the combined machined/burnished surface have shown that the burnishing process induces compressive residual stresses on the subsurface treated specimens. Copyright © 2013 John Wiley & Sons, Ltd.