机用锯条规律性偏锯原因分析

我厂有一台用于生产机用锯条的圆轮分齿机,由于年久失修,导致所加工的机用锯条出现规律性偏锯现象。为解决这一问题,我们对圆轮分齿机进行了维修和技术改造,并通过多次试验检测,分析探讨了机用锯条规律性偏锯的原因。1维修前检测通过对生产机用锯条的各道工序分析认为,产生规律性偏锯的最大可能性是分齿工序。我们查阅了几个月的圆轮分齿机生产记录,并从使用圆轮分齿机加工的机用锯条中抽检30支,每支锯条在有效部位250mm内检查3点,获得锯条对称度分布图见图1。从图1中明显可见,各点的实际分布中心远远偏离零线,即有96%的点偏向基面,而点合格…     

硬材料电弧穿孔

为改革刀片制造工艺,购进了一批短头机用锯条,经磨锐后制成刀片。为固定锯条刀片,在锯条上需加工两个φ6毫米的小孔。由于机用锯条一般用高速工具钢、合金工具钢或轴承钢经热处理而制造的,硬度     

锯齿角度的改进

一般手用锯条锯齿角度前角是0°,后角是30°(机用锯条也大致相同)。锯齿采用较小的前角是因为锯条用薄片金属制成(手用锯条厚度约0.64毫米,机用锯条厚度约1.2～2毫米),如果前角太大,吃刀深了,锯齿会受不住,容易崩裂。锯齿采用较大的后角是为了不影响后面一齿的齿形,同时,切下来的切屑也有“容屑空间”容纳。这样锯齿前角小,在金属上锯来锯去,本来就不耐磨,再加上后角     

双金属机用锯条

机用锯条是金属毛坯下料的主要工具,用高速钢带加工而成。从其锯条使用和破损过程分析,对锯条除要求快速切割金属和耐磨外,尚能在高负荷进给时,不发生因过度偏斜而折断。目前还没有发现一种材料做锯条时,同时能满足以上两点要求。如果我们将参加直接切削工作的、占整个锯条宽度     

废锯条的修复

(一)用钝了的机用锯条,经过合理的修复后,还可以继续使用。我厂修复废据条的方法如下。把用钝的锯条两侧,用油石磨几下,再把锯条夹在虎钳上,用平面砂轮将齿顶稍磨平。然后用碗形砂轮,将倒向两侧的锯齿磨低0.05～0.15公厘。这样,锯条分路的各齿就不一样     

废锯片铣刀及废机用锯条的再利用

废锯片铣刀及机用锯条由于其成熟的淬火工艺及其优良的材质,而使其具有很高的硬度、耐磨性及韧性。所以,我利用它们制作模具中的一些小工件,并取得了较好的效果。例举如下: 图1所示是一块薄板冲模上的凹模,我们选择了废锯片来加工。先割出凹模外形,然后用电火花打出     

退火工艺对机用锯条淬火回火硬度及锯切寿命的影响

对W9Mo3Cr4V高速钢机用锯条进行了退火工艺试验和锯切寿命试验 ,试验结果表明 ,不同退火工艺与锯条淬火回火硬度及锯切寿命之间不存在明显对应关系 ,但高温长时间退火对锯切寿命有不利影响。     

巧用手工锯条

我厂高频热处理组每年都要制造一、二十套高频淬火感应器。感应器系用纯铜制成。由于铜硬度低,塑性高,在锯制过程中,硬而脆的碳素工具钢手工锯条很易掰齿和折断,每做一次感应器都要损耗许多手工锯条。后来我们将手工锯条用硝盐炉进行中温回火(350℃),使之硬度由HRA82～84降至HRA75～76(相当于HRC48～51),这样便大大提高了它的韧性。经过使用效果极佳,一根经过中温回火的手工锯条用了整整一年,     

机用废锯条的翻新方法

机用锯条是机器制造业中切割金属不可缺少的工具,它的消耗量很大,而且价格也比较高,所以如何翻新废锯条,是一个值得研究的问题。过去我厂是采用把废锯条退火后重新磨出锯齿的方法翻新。用这种方法在热处理方面,技术要求比较高,往往由于处理的不当,翻新后锯条寿命会比原来低。同时,这种翻新方法还要经过退火、铣齿(或刨齿)等许多工序,如果翻新的锯条数量较少,则翻新后锯条的成本会比新锯条还要高,因此很不合算。     

新式锯条

<正> 目前用改磨的标准锯条(ГОСТ6645—68)锯软的韧性材料时,两牙之间的容屑槽很快就会堵塞,切屑还和锯牙粘连在一块。图示的锯条能从切削区自由排屑,因而其耐用度比标准锯条高1.5～2倍。该锯条的几何参数为:前角γ=12°,后角α=30°,齿距=8mm(靠磨掉一齿的办法来加大),刃磨部份的宽度为37mm。采用这种改变了结构的锯条能节约50%     

表面冶金高速钢机用锯条的研制

采用低碳合金钢作为基材 ,在锯条齿部渗入合金元素W Mo Cr V形成表面高合金层 ,经渗碳、高温淬火和回火处理后 ,研制出一种齿部具有高速钢锯切性能、背部具有高强韧性、成本低廉的表面冶金高速钢机用锯条。     

Prolonging the service life of shot-blaster blades made from high chromium cast iron

By using chill technology in the sand mold and improved heat treatment technology, superior shot-blaster blades were made from high chromium cast iron near eutectic composition. When steel pellets are shot, the service life of this kind of blade was 670 h, about twice the 328 h of the GF blades (made in Switzerland). Under the condition of shooting white iron pellets, the service life of this kind of blade was 380 h, about 1.5 times the 245 h of the domestic high quality blades.It was shown by performing a worn surface analysis of discarded blades and by a trial run of pilot blades that the wear of blades when shooting steel pellets was mainly caused by spalling, and there was little microcutting. Decreasing the amount of retained austenite and improving the toughness of martensitic matrix increased the wear resistance of these blades effectively. The wear of blades was mainly caused by microcutting when shooting white iron pellets, but spalling also contributed to wear. Increasing the hardness and decreasing the amount of retained austenite were beneficial to wear resistance of these blades. Unidirectional carbide arrangement perpendicular to the wearing surface also improved wear resistance of both types of blades.     

高硬刀片干切削淬硬GCr15轴承钢的表面粗糙度预测

采用陶瓷刀片和CBN刀片干切削淬硬GCr15轴承钢,测量了不同切削参数下切削后工件的表面粗糙度;基于微粒群优化算法建立了表面粗糙度预测模型,并与线性回归法建立的经验公式进行了比较;用扫描电子显微镜观察了切屑形态。结果表明:采用微粒群优化算法建立的表面粗糙度预测模型具有一定的可靠性,与线性回归法相比,能更精确地预测出加工工件的表面粗糙度;切削参数中对表面粗糙度影响最大的是进给量,其次是背吃刀量,切削速度的影响最小;锯齿状切屑能降低切削温度,提高工件表面质量;用陶瓷刀片和CBN刀片切削获得的最低表面粗糙度分别可达0.48μm和0.56μm。     

Fabricating hollow turbine blades using short carbon fiber-reinforced SiC composite

The development of hollow turbine blades fabricated by nickel-base superalloy is limited by its high density and low operating temperature (<1,100 °C). A new technology for fabricating hollow turbine blades of fiber-reinforced SiC composite was put forward. The chemical corrosion process of DSM Somos 19120 resin mold was investigated, and the pyrolysis of phenolic resin and the infiltration of liquid silicon were analyzed by using scanning electron microscope and X-ray diffraction. The influence of carbon fiber content on fracture strength and fracture toughness of fiber-reinforced SiC composite was investigated using the measurement of three-point flexural strength test. Results showed that stereolithography molds of photosensitive resin were corroded perfectly using KOH alcohol water solution. The porous carbon preforms were obtained after phenolic resin was pyrolyzed from 400 to 800 °C, which were then infiltrated with molten silicon to gain SiC matrix at the temperature of 1,450 °C in 1 h. The fracture strength and fracture toughness of SiC ceramic matrix were enhanced with the increase of short carbon fiber content. The maximum fracture strength and fracture toughness of samples were about 270 MPa and 5.1 MPa m^1/2, respectively. Finally, hollow turbine blades were successfully fabricated using short carbon fiber-reinforced SiC composite.     

如何提高高速钢机用锯条的锯切性能

讨论了有关检验机用锯条锯切性能的方法,介绍了有关锯条磨损的研究成果,分析了锯条材料的化学成分、锯条用热轧带钢在轧制过程中的加热温度以及热处理工艺对锯条锯切性能的影响。     

基于ANSYS的抛丸器叶片的设计参数对应力的影响分析

针对抛丸器的叶片的结构参数进行了分析,并对其对应力的影响进行了理论研究,计算了相同抛打速度和叶片转速条件下直线叶片、前曲叶片、后曲叶片的不同的结构参数,对三种不同结构叶片的受力情况进行了比较,分析了底座长度、叶片厚度、曲率半径三个结构参数以及不同结构的叶片对应力分布的影响,通过分析,得到相同结构条件下,直线叶片底座越长,厚度越大,其应力集中程度越小以及前曲叶片曲率越大,应力集中程度越小的结论.     

后向式离心通风机长短叶片的数值研究

为了研究短叶片对后向式离心通风机性能的影响,对某风机厂的JMF No4.3A型离心风机加短叶片的叶轮模型进行了数值研究.数值方法采用RNG k-ε湍流模型和SIMPLEC算法.主要研究了长短叶片数、短叶片长度、短叶片周向位置以及短叶片的安装角度对后向式离心通风机性能的影响.为方便比较,计算结果做成了无因次曲线的形式.结果表明:对后向式离心通风机而言,短叶片长度影响风机的做功能力和效率:短叶片的周向位置则对压力和效率均有较大影响.特别是对效率的影响最大;而短叶片的安装角度则对风机的性能影响较小.     

Turbine blade vibration due to partial admission

A method is given for analyzing the vibrations of turbine blades during partial admission. The combined effects of shock loading as the blades enter and leave the arc of admission, and nozzle wake loading in the arc of admission are included. By separating these two effects, the dependence of blade stress on natural frequencies, running speed, number of nozzles, number of blades per row, number of blades per group and damping is illustrated. Apparatus for determining experimentally the exact nature of the steam loading acting on the blades is described.     

喷丸对TC4钛合金材料叶片的影响研究

文章主要通过试验的方式,研究喷丸对钛合金材料(Ti-6Al-4V)长叶片的疲劳寿命、表面粗糙度、表面完整性、渗入Fe元素含量等的影响,为确定合理的钛合金材料长叶片喷丸方式提供一定的帮助.