热处理解决传统车床方刀架故障的分析与探讨

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Sep．2013机 床 与 液 压Hydromechatronics Engineering V0l_41 No．18DOI：10．3969／j．issn．1001-3881．2013．18．011nalysisesolveand Discussion of the Heat Treatment Process tothe Failure of Conventional Lathe CarriageFENG Xiaofei ，ZHENG Weigang ，JIANG Litaoa．School of Energy And Power Engineering；b．Mechanical Enginering Training Center，Wuhan University ofTechnology，Wuhan 430063，ChinaAbstract：The conventional lathe carriage 0fIen appears the ofset phenomenon in use．and thereis excessive wear of pin hole sleeve of the smal skateboard，which afects the machining accura-cy and reduces the eficiency．CA61 40 lathe，for example，the pin hole sleeve is made of 45steel，whose abrasion resistance is not enough by conventional heat treatment processing．Thusit is necessary to explore the modern heat treatment process to enhance the abrasion resistanceOf 45 stee1．and resolve the actual production fault of lathe carriage.

Key words：pin hole sleeve，abrasion resistance，45 steel，subcritical quenched，surface treat·ment processLathe， an important part of the machining，plays an important role in the development of indus—tria1．The CNC lathe is in production for many yearsand with great Success， but compared traditionallathe is still irreplaceable，is important equipment inturner production．Lathe square turret is the impor—tant factor to determine the accuracy of turner，butthere is an emergence of the fault in use which seri-ously affects the accuracy，leads to a direct result ofthe decrease in eficiency．CA6140 lathe square tur-ret failure to solve the fault square turret，analyzed，and to discuss several modern heat treatment process.

comparative analysis， looking for the best way tosolve the fauit.

1．Failure analysisBefore conducting failure analysis to understandthe structure and working principle of the CA6140lathe square turret[1]as folows：1．1．The diagram of square turret structure andworking principleReceived：2013—02—16ZHENG Weigan．E—mail：zfeidiao### 126．conThe diagram of structure is Fig．1：(a17(b)41．Cam，2、6、13．Spring，3．washers，4．The outer splined of thesleeve，5．The inner splined of the sleeve，7．shaft 8．Straddlepin，9．Turret body，10．Handle，11．Pin，12．steel ball，14.

Small skateboard，15．Locating pinFig．1 The diagram of CA6140 lathe square turet structureThe working principle of square turret：Counter—clockwise rotation of the handle 1 0， to release theturet body 9，by a pin connecting turning the innersplined sleeve，and drive the rotation of the outersplined sleeve。through which the lower end of theiaw so that the cam rotation，and through the inclinedsuYface of the cam a pul out the positioning pin 15，the side of the gap b touch turret body 9 of the posi—tioning pin 15，so that the turret body is rotated，thesteel ball 1 2 slipping out of the hand to another posi—A R56 Hydromechatronics Engineeringtioning hole of the turret body early positioning，andthen clockwise rotation of the handle 10，pin align—ment and clamping sequentially.

1．2．The cause of the malfunctionLathes often need change tool in long-term use，and the traditional lathe tool change is achieved bythe rotation of the handle on the turet．Due to fre.

quent rotation of the handle portion of the tool hold—er，resuh of repeated exposure to the friction betweenpin hole sleeve on smal skateboard and locating pinhead and steel ball in square turret caused by sleeveexcessive wear and its cross—section can easily be.

come ova1．The direct impact resulting often occurs acertain amount of offset when locking square turret，ifnot noticed this offset。directly on a workpiece turn.

er，its accuracy will be greatly affected，easily cau—sing the workpiece to waste．if staffs observe this off-set，they need to manualy correct，no doubt greatlyextend the processing time，affecting the efficiency.

Manifested on a traditional lathe CA6140 wear isshown in Fig．2．From Fig．1，the pin holes sleeve itscross—section is circular before excessive wear．but inFig．2 the pin hole sleeve has severe wear whose sec.

tional has almost ova1.

Fig．2 The wear of pin hole sleeve on the smallskateboard of CA6140 lathe2．Solutions and DiscussionThe wear is one of the main failure modes of themechanical parts．The wear resistance of steel is theability to resist wear on certain working conditionsl 2 1．S0 far，the scientific community does not havea concise and reliable wear law． For certain wearconditions，there are many factors that affect the steelabrasion resistance，including the operating condi-tions(1oad，speed，sport，etc．)，lubrication state，environmental factors(temperature，humidity，andthe surounding medium，etc．)，material factors(component，microstructure，mechanical properties，etc．)，the quality of the surface of the part and thephysical chemical characteristics[3]．Traditionallathe，a smal slide pin hole sleeve material is usually45 stee1．In order to improve its surface hardness andwear resistance， the traditional practice is thequenching and tempering approach[4]．Through thepin hole sleeve wear analysis，ordinary heat treatmentobviously does not satisfy the requirements for long-term use．According to wear mechanism discuss thistwo heat treatment to improve the hardness and wearresistance of 45 steel，as to improve the performanceof pin hole sleeve on the small skateboard，and im—prove production eficiency.

2．1．Subcritical quenchedIt is well known that the wear resistance of thesteel has much to do with the hardness，strength andtoughness of the stee1．Steel organization，all factorsthat can increase the hardness，strength and tough—ness of the steel can improve the wear resistance ofthe steel『5]． Subcritical quenched due to thequenching temperature range is below in the Ac3 two—phase region(austenite+ferite phase region)，be—cause the presence of the ferrite phase，so that theworkpiece has good toughness and ductility afterquenching，the quench cracking tend to be greatlyreduced to[6]；the quenching temperature is lower，the austenite formed in the heating of high carboncontent，the hardness of the martensite after quench·ing is higher than the martensite formed by the tradi-tional quenching． Subcritical quenched usually re·quire preheating，and quenching and high temperaturetempering preheating is stronger than the traditionalannealing or normalizing[7]．Therefore，it can guar—antee to improve the strength and toughness of thesteel in the hardness of the same case if taking appro-priate preheating+subcritical quenched process，so asto improve the wear resistance.

the comparison of the mechanical properties of45 steel subcritical quenched process with traditionalquenching process is shown in Table 1[7]．Figure 3[7]gives XJL-02 Vertical metalurgical microscopeobservation using the 730 oC subcritical quenched，770 oC after 45 subcritical quenched process handlingsteel microstructure． Diferent subcritical quenchedtemperatures have same preheating conditions(850℃ quenched +550oC tempered)．Table 1shows that the strength，ductility and toughness of 45FENG Xiaofei，et al：Analysis and Discussion of the Heat Treatment Process toResolve the Failure of Conventional Lathe Carriage 57steel by sub．temperature quenched，770 clC +200 oCtempered is much higher than at 850℃ traditionaluuenched + 200 oC tempered； in addition thestrength and toughness of 45 steel by 730 oC subcriti-cal quenched +200 ℃ tempered is higher than at850 oC traditional quenched + tempered at 560 c【二.

This shows the strength and toughness of the 45 steelobtained by the appropriate sub—temperaturequenched superior to traditional quenched strengthand toughness，and its application to the pin holesleeve can signifcantly improve the wear resistance.

(a)730℃ (b)770℃Fig．3 Microstructure of 45 steel subcritical quenchedfPre．heat treatment：quenched at 85O℃+tempered at 550 oC)2．2．Surface treatmentThe part surface quality is one of important fac—tors to affect its wear resistance． Surface treatmentcan be a good solution to the problem of wear of pinhole sleeve．The surface treatment technique by heat—ing or mechanical processing method does not changethe chemical composition of the materia1 surface，butthe structure is changed，as well as its properties.

Surface treatment enables parts to obtain the surface—hardened layer of a certain depth．and its centralportion to maintain good toughness，and thereby im—prove the wear resistance[3].

According to Gu’s abrasion resistance studies of45 stee1 using several surface treatment l 8 J，it canbe drawn the difference in performance of 45 steelunder different surface treatment conditions．Use theexperimental conditions of the diffe rent surface treat-ment work to 45 steel sample f quenched and tern—pered state)，such as shown in Table 2．For ease ofcomparison，the datas were norm alized，and gives acomparison between the sample perform ance of sever-al enhanced process，as shown in Table 3．Includingcarbonitriding in RRJJ25-9T pit gas carburizing fur—nace，kerosene decomposition gas as a carbunzing a。

gent，liquid ammonia(after gasifcation，drying)asa nitriding agent，direct quenched after carbonitrid—ing．Laser as GJ一1 transverse flow lasers．the outputpower of 500～2 000 W，continuously adjustable，and a spot diameter of 3 mm．Phosphating processingof the sample surface before the laser hardening．InTab．2．尸 and V are the laser power and the scan-ning speed；P1 and P2，respectively，are the pres—sure of the oxygen and acetylene gas；Q1 and Q2 areoxygen and acetylene gas flow．Comprehensive coefi_clent in Tab．3 is multiplied by the three values??of hardness。wear resistance，corrosion resistance di—vided by the cost values obtained.

From Tab．2 can be seen by the hardened layerdepth and hardened rang for 45 steel under the re—spective surface treatment process，using the surfacetreatment improve the depth of the hardened layer ofthe sample.

From Tab．3，it greatly improved the propertiesof the s to have used surface treatment，and improvedthe hardness and wear resistance of the samples．Theimprovements are different by diferent snrface heattreatment process．Laser cladding improves the wearresistance of the sample largest，but also with thehighest cost；High—frequency quenching improves the58 Hydromechatr0nics Engineeringwear resistance of the sample smallest，but the cost islowest compared to the other processes．To the pinhole sleeve of small skateboard for conventionallathe，the applications of these several surface treat.

ment processes theoreticaly could improve the abra-sion resistance of the sleeve，thereby extending thelife，overcoming the malfunction in the production.

Tab．2 The test conditions of the surface treatment process3．Conclusions1)After a tool change，the conventional lathecarriage often appears a certain amount of ofsetcaused by excessive wear of pin hole sleeve of thesmall skateboard．The material of the pin hole sleevefor the 45 steel after traditional quenched and tem。

pered，whose wear resistance do not reach productionrequirements.

2) Compared with the traditional quenched.

subcritical quenched can significantly improve the 45steel strength，hardness，toughness，SO it can im—prove the wear resistance of the 45 steel，and greatlyimprove its life cycle if apply this to the pin holesleeve heat treatment.

3)Using surface heat treatment can improve thewear resistance of 45 stee1．in addition the improve.

ment and the cost are different by different surfaceheat treatment process，SO manufacturers can chooseappropriate surface treatment process to produce thepin hole sleeve of small skateboard according to thespecific needs.

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基于形态小波的轴承故障信号去噪和特征提取王李立 ，熊静琪，韩 星，秦枭品电子科技大学，成都 611731摘要：针对传统小波阈值去噪所产生的 Pseudo—Gibbs现象，已发展 出各种改进的小波去噪方法，基于相关原则优化阈值方法就是其中的一种。介绍了该方法的原理，证明其优于传统阈值去噪的特性。

与以往的对阈值进行改进不同，将形态小波用于信号处理当中，对轴承早期故障特征进行提取，并经过数据仿真和故障轴承实例分析 ，将该方法的去噪效果和基于相关原则优化 阈值方法进行对比，验证了该方法的有效性和先进性。

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热处理解决传统车床方刀架故障的分析与探讨冯小飞 ，郑卫刚 ，江丽桃武汉理工大学 a．能源与动力工程学院．b．工程训练中心，武汉 430063摘要：传统车床方刀架在使用中经常出现偏移现象，存在小滑板上销孔套筒磨损过大的问题，影响了h．x-精度，降低了工作效率。以 CA6140车床为例进行研究发现，其销孔套筒的材料为45号钢，按传统热处理方式对其进行处理后耐磨度不够。通过现代热处理工艺来强化45号钢的耐磨性能，从而解决了实际生产中车床方刀架的故障。

关键词 ：销孔套筒；磨损；45号钢 ；亚温淬火；表面热处理中图分类号：TH16