三刃结构金刚石锯片的设计及切割特点

研制了三刃结构的金刚石圆锯片,其切割特点是锋利、耐磨、平稳。刀头沟槽深度为１．０～１．２ｍｍ,金刚石浓度４４％～４８％,采用复合基胎体。调整锯片进给速度和切深可获得高的切割效率和使用寿命。该锯片可使花岗岩的切割效率提高４０％～５０％,综合效益提高２０％～３０％。     

金刚石圆锯片刀头制造新工艺

提出一种低温电镀法与粉末冶金热压法相结合制造金刚石圆锯片刀头的新工艺。该工艺采用电镀法制造金刚石复合基块作为金刚石圆锯片刀头的骨架与磨料,再通过低熔点金属粉末粘结制成金刚石圆锯片刀头。试验表明,该工艺制备的金刚石刀头锋利耐用,并具有良好的性能价格比。     

ZL系列装载机换挡离合器故障处理2例

１．进、退挡串油 经拆检变速器,发现离合器轴端旋转密封圈端面有非正常磨损,且集中在背离进油方向（见图１ａ）。分析认为,故障原因可能是：聚四氟乙烯材料抗磨损性能差;密封圈与离合器轴、油封盖配合过紧,在油压冲击下密封圈贴紧轴槽外端,使其与轴端面之间发生相对高速转动,造成密封失效进而发生离合器串油。处理方法是,将密封圈改为用添加了石墨、二硫化钼和青铜粉的聚四氟乙烯复合材料,同时按下列参数（见图１ｂ、图２）改进结构： ｈ＝０．２～０．３ ｍｍ;Ｂ＝２～３ ｍｍ; Ｌ＝３～５ｍｍ;侧间隙ｔ＝０．０５～０．１５…     

制造金刚石圆锯片刀头的一种新方法

提出了一种制造金刚石圆居片头的新方法－电镀法制造金刚石复合片。该复合片作为金刚石圆片刀头的骨架与磨料,再通过低熔点金属粉末粘结制成金刚石圆锯片刀头。研究表明,该方法制备的新型金刚石刀头锋利耐用并具有良好的性能价格比。     

刀具材料的回顾与展望（下）

３．陶瓷陶瓷刀具材料分为３类：１）氧化铝基陶瓷　一般在Ａｌ２Ｏ３基体中加入ＴｉＣ、ＷＣ、ＳｉＣ、ＴａＣ、ＺｒＯ２等成分,经热压制成复合陶瓷。硬度达ＨＲＡ９３～９５,抗弯强度达０．７～０．９ＧＰａ。为提高韧性,常添加少量的Ｃｏ、Ｎｉ等金属。２）氮化硅基陶瓷　常用的是Ｓｉ３Ｎ４＋ＴｉＣ＋Ｃｏ的氮化硅基复合陶瓷,其韧性常高于Ａｌ２Ｏ３基陶瓷,硬度相当。３）复合氮化硅—氧化铝陶瓷　其化学成分为Ｓｉ３Ｎ４７７％,Ａｌ２Ｏ３１３％,Ｙ２Ｏ３１０％,硬度可达ＨＶ１８００,抗弯强度可达１．２０ＧＰａ。这种陶瓷…     

磨削过程模拟及磨削机理研究（下）

３磨削机理研究３．１磨削用量及参数磨削运动：外圆磨削（逆磨）,砂轮速度Ｖ＝３０×１０３ｍｍ／ｓ,工件速度ｖ＝５×１０２ｍｍ／ｓ,纵向进给速度ｓ＝８ｍｍ／ｓ,加工余量ｔ＝４０×１０－３ｍｍ;工件参数：工件半径ｒ＝５０ｍｍ;砂轮参数：砂轮半径Ｒ＝１５０ｍ...     

刀头定量伸缩的专用钻削工具

刀头定量伸缩的专用钻削工具加工图１所示零件时，由于该零件外形大，重量在１ｔ左右，很难移动，上面有很多Φ３０ｍｍ的孔，且每孔中又有两道宽３ｍｍ、深０．５ｍｍ的环形浅槽，为利用摇臂钻床加工孔中两道浅槽，研制出了如图２所示的刀头定量伸缩的专用钻削工具。图１...     

激光焊接在金刚石圆锯片制造中的应用

直径较小的金刚石圆锯片,传统的制造工艺是采用烧结方法将金刚石刀头烧结在钢基体上。但是,烧结金刚石锯片普遍存在着结合强度尤其是高温结合强度较低的缺点。采用激光焊接金刚石圆锯片,不仅能提高金刚石锯片的结合强度,而且焊接变形小,易于保证锯片的尺寸精度。此外,激光焊接过程还容易实现自动化,减轻操作者的劳动强度。一、激光器和焊接装置由于８００Ｗ基模ＣＯ２激光器可以从双面焊透直径３５０ｍｍ以下,厚度小于２．５ｍｍ的金刚石圆锯片的基体,为此特设计研制了一台８００Ｗ基模桁架式折叠型石英玻璃管ＣＯ２激光器。该激光…     

梯形螺纹冷轧轧辊环形齿的精加工

使用冷轧器一次冷轧成型长达２ｍ以上的梯形螺纹丝杠工艺 ,其轧辊环形齿的精加工为关键工序。该冷轧器为三辊径向等分布置 ,螺距 ｐ＝８ｍｍ的轧辊外形尺寸见图１。三辊的４个校正齿３°３０′以右的尺寸相同 ,３°３０′以左的４个挤压齿尺寸各异（含尺寸ｌ）。校正齿螺距为７．９８８ ,中径齿厚为３．９９４ ,挤压齿螺距为８．１１９ ,中径齿厚则从３．７２９向左递减 ,有关技术条件如下：１）３个轧辊的外径尺寸差应小于０．０２ｍｍ ;２）轧辊外径、中径的径向跳动应小于０．０１ｍｍ ;３）中径圆度应小于０．０１ｍｍ ;４）４个校正齿…     

利用车床改装铣槽专机

图１为我厂产品一关键零件,材料为ＨＴ２５０。其中宽２０ｍｍ、深３．５ｍｍ槽需加工,采用在ＣＷ６１１００车床上铣削的工艺方案。 铣刀直径φｄ铣刀＝２０ｍｍ,铣刀转速ｎ＝３２０ｒ／ｍｉｎ,每齿进给量 ａｆ＝０．１ｍｍ／ｚ,铣刀齿数 ｚ＝ ６。 进给速度ｖｆ＝ａｆｚｎ＝１９２ｍｍ／ｍｉｎ。 对于工件来说,ｖｆ＝πｄ工件ｎ工件,即： 被改装的ＣＷ６ｌ１００车床的最低转速是３．１５ｒ／ｍｉｎ,为降低转速设计了如下减速机构,即将与机床主电机直接传动的大皮带盘拆下,换上装有减速轮系的专用皮带盘（见图２）。从该机构传…     

Machinability issues in turning of Al-SiC (10p) metal matrix composites

The paper presents the results of an experimental investigation on the machinability of fabricated aluminum metal matrix composite (A356/SiC/10p) during continuous turning of composite rods using medium grade polycrystalline diamond (PCD 1500) inserts. MMC’s are very difficult to machine and PCD tools are considered by far, the best choice for the machining of these materials. Experiments were conducted at LMW-CNC-LAL-2 production lathe using PCD 1500 grade insert at various cutting conditions and parameters such as surface roughness, specific power consumed, and tool wear were measured. Machining was continued till the flank wear land on the tool crossed 0.4 mm. The influences of cutting speed on the insert wear and built-up edges (BUEs) formation were studied. The present results reaffirm the suitability of PCD for machining MMCs. Though BUE formation was observed at low cutting speeds, at high cutting speeds very good surface finish and low specific power consumption could be achieved.     

EFFECT OF COATING ROUGHNESS ON PERFORMANCE OF SMALL CVD DIAMOND COATED TOOLS

□ Small milling tools for dental application were diamond coated by means of Hot Filament CVD (HFCVD). Different thicknesses were obtained by using different diamond deposition times (3 and 12 h) and seeding conditions. The surface roughness was measured for coated and uncoated mills and milling tests were performed to measure the cutting forces. A ceramic material and a polymeric matrix composite (PMC) were used as workpiece materials. The highest cutting forces were measured for the coated tool with the highest thickness of the diamond coating. Probably, roughness increase and non-optimal edge profiles affect the tool behavior during cutting. As a consequence, tool failure was observed in the case of milling of ceramic by means of the coated tool with the highest coating thickness. The coated tool with a lower thickness of the diamond coating showed an optimal behavior under cutting, above all in the case of PMC milling.     

铝合金车削工艺的研究及应用

通过多种切削试验,对影响铝合金车削加工表面质量的主要因素进行了探讨。结果表明:对于6063铝合金宜采用的刀具材料有聚晶金刚石(PCD)和YT15,当刀具的前角为10°、后角为5°-10°、切削速度为40-100m/min、进给速度为0.06-0.12mm/r、且在干车削条件进行车削时,可以获得较低的表面粗糙度。     

微细干车削硬铝合金LY12的表面粗糙度研究

采用YG类细晶粒硬质合金刀具和PCD刀具对硬铝合金LY12进行了微细干切削试验,通过单因素切削试验研究了不同刀具材料、刀具前角、刀尖圆弧半径对表面粗糙度的影响。结果表明,在微细干切削条件（v=12．6m／min,aP=0．02mm,f=0．004-0．01mm／r）下,采用PCD刀具可获得Ra0．112～0．30μm的光洁表面;采用大前角、大刀尖圆弧半径的PCD刀具,可获得最好的加工表面粗糙度。     

Research of the mechanism and development of the wear model of a diamond tool when turning aluminum-matrix composite materials

The results of a study of the wear mechanism of diamond tools for turning aluminum-matrix composite materials (ACMs) hardened by Al₂O₃, SiC, and B₄C particles are presented. The study of the posterior surface topography of a diamond tool (ASPK-2) shows the presence of parallel scratches in the direction of the vector of the cutting speed; it is characteristic of abrasive wear fatigue. Research on the mass-transfer of the elements of the tool material into the chips of the treated material is carried out; it shows the presence of particles of the tool material of a size comparable to the ACM filler microparticles. The model of the abrasive-wear fatigue of a diamond tool during the turning of ACMs, considering the power of the impact of the reinforcement particles, the hardness of the tool depending on the temperature in the cutting zone, the abrasiveness, and the mass fraction of the dispersed particles reinforcing the matrix and tool geometry is proposed.     

Experimental assessment of textured tools with nano-lubricants in orthogonal cutting of titanium alloy

In this study, we investigated the effects of composite nano-Cu/WS₂ lubricating oil and single-point diamond indentation-textures on improving the cutting performance of YG8 cemented carbide tools, which is crucial for textures tool applications. The aims of the study were to improve wear resistance and reduce chip adhesion at the tool’s rake face in cutting of titanium alloys. Dot textures with different spacings were fabricated on the surface of YG8 cemented carbide tools through the single-point diamond indentation method, and composite nano-Cu/WS₂ lubricating oil was prepared. Orthogonal cutting tests were carried out under dry cutting and minimal quantity lubricated (MQL) conditions. Investigate the effect of different texture spacing on the cutting performance in the light of cutting forces, friction coefficient, the deformed chip thickness, tool adhesions, and chip morphology. The results show that the dot texture effectively improved the lubrication conditions in machining titanium alloys under the MQL conditions. The dot texture is effective at low speed in the dry cutting conditions. With the increase of cutting speed, the friction coefficient of dot texture tool is affected by texture spacing, and the friction coefficient of DT-200 tool is the smallest. In addition, composite nano Cu/WS₂ lubricating oil forms a lubricating film on the wear path by atomizing the lubricating oil and stores it in the dot texture, which enhances the anti-wear performance in the cutting process and reduces the cutting force and friction coefficient at the tool chip interface. By evaluating cutting force, friction coefficient, chip and tool morphology, it is concluded that DT-100 tool is more effective in improving lubrication conditions.

     

陶瓷轴向磨削加工实验分析及砂轮磨损研究

轴向磨削加工是以金刚石小砂轮的端部磨粒作为主切削刃来去除材料,用圆周部分内圆或外圆表面磨粒作为副切削刃对已加工圆柱面进行修磨的一种磨削加工技术。从轴向对工程陶瓷进行外圆或内孔加工时,一次切削的径向磨削深度(即背吃刀量)与进给速度分别可达5～10mm和200mm/min以上,实现了工程陶瓷外圆的高效低成本加工。利用该方法对陶瓷材料制成的发动机精密偶件出油阀套筒进行内孔加工,通过单因素试验,分析了不同参数组合下的砂轮磨损情况及各参数对砂轮磨损的影响,试验表明:砂轮磨损程度随磨削深度的增加而呈非线性增加;为使砂轮磨损最小化,主轴转速和工件转速应匹配,即二者的比值应控制在一定的范围内。     

Effect of machining parameters on surface roughness and tool wear for 7075 Al alloy SiC composite

In the present study, an attempt has been made to investigate the influence of cutting speed, depth of cut, and feed rate on surface roughness during machining of 7075 Al alloy and 10 wt.% SiC particulate metal-matrix composites. The experiments were conducted on a CNC Turning Machine using tungsten carbide and polycrystalline diamond (PCD) inserts. Surface roughness of 7075Al alloy with 10 wt.% SiC composite during machining by tungsten carbide tool was found to be lower in the feed range of 0.1 to 0.3 mm/rev and depth of cut (DOC) range of 0.5 to 1.5 mm as compared to surface roughness at other process parameters considered. Above cutting speed of 220 m/min surface roughness of SiC composite during machining by PCD tool was less as compared to surface roughness at other values of cutting speed considered. Wear of tungsten carbide and PCD inserts was analyzed using a metallurgical microscope and scanning electron microscope. Flanks wear of carbide tool increased by a factor of 2.4 with the increase of cutting speed from 180 to 240 m/min at a feed of 0.1 mm/rev and a DOC of 0.5 mm. On the other hand, flanks wear of PCD insert increased by only a factor of 1.3 with the increase of cutting speed from 180 to 240 m/min at feed of 0.1 mm/rev and DOC 0.5 mm.     

Influence de la découpe d'éprouvettes en composite sur leur tenue mécanique

The preparation of composite coupons by cutting alters their mechanical properties according to the composite specificities, cutting conditions and test methods. This study shows this dependence through the coupons preparation, made from three polymer matrix composites, by different edge machining techniques (routing, endmilling, grinding or sawing) and using number of cutting tools (PCD, carbide, coated carbide and diamond wheel). The mechanical responses of both the tensile test on a ring specimens and the Iosipecu test coupons (ASTM D 5379) are correlated to the cutting conditions and the microscopic damage observations due to the cutting actions.