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对牌号为的钼管质量已研究出结果,此钼管是按下列三种不同工艺流程生产的:Ⅰ——在坯料上钻轴向孔,用芯棒压轧管坯;Ⅱ——在坯料上钻孔,管坯扩孔,再用芯棒压轧;Ⅲ——给坯料连续穿轧,再压轧(ΠΠ流程)。根据金相分析.x-射线组织分析以及对试 相似文献
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小圆钢表面耳子缺陷有两种解决方法:φ≥16 mm时,用手提砂轮机磨去耳子;φ<16 mm时,用砂轮无芯磨床研磨去除耳子.两种方法在实施前必须对待磨修产品进行一次机械矫直,以保证待修品的平直度.该方法产量低,能耗大,且带来一系列问题.经改进,设计了"三步法"工艺即二次矫直加一次磨修工艺.该方法妥善解决了中低碳和低合金结构钢表面耳子缺陷处理时间长、合格率低的生产难题,使清除小圆钢表面耳子缺陷简便快捷,生产效率高、成本低;同时,圆钢的不圆度、平直度明显改观,产品合格率达100%. 相似文献
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五、讨论(1)工艺操作方面的问题:1)穿孔机后轧卡问题:第一批30支管坯中有8支发生后卡。分析其原因有以下几种情况:第一批第二次试制10支管坯中有4支皆轧卡,推测系由于顶头在变形区的位置取的不够恰当。顶头伸出压缩带距离太短,(32~34mm),坯料后端穿孔结束时;随着轧辊与管坯接触面减小,轧辊对管坯的前进推力也降低。当推力降到无法克服穿孔阻力时,即造成管坯失去了前进的运动而仅继续转动,发生轧卡。此外,也有因坯料过长,顶头磨损过于厉害而生后轧卡的情形。Cr25Mo3Ti 后坯尾端与磨损顶头的纵剖面如图17所示。 相似文献
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针对棒材和管坯在工件表面出现轧痕和结疤缺陷,不能进行有效处理的问题,设计一种加工组合刀具,此组合刀具能随轧制棒材和轧制管坯内表面椭圆度和长度方向的弯曲度,对表面进行均匀加工。 相似文献
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为进一步提高管坯刮削效率,需对原有刮管机刮削速度进行提升,提升刮削速度后发现刮削管坯表面质量差,故对刮管机各系统进行分析与改造,以在实现快速刮削的基础上提高管坯表面刮削质量。 相似文献
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Improvement in pipe production on a longitudinal rolling mill is proposed. The tandem longitudinal pipe rolling mill in the pipe-mill aggregate (PMA)-140 at PJSC (public joint-stock company) Sinarsky Pipe Works is considered. Currently, pipe is produced both from rolled billet (diameter 120 mm) and from continuous-cast billet. To reduce costs, it would make sense to discontinue the use of rolled billet and to produce all of the pipe from continuous-cast billet in the existing PMA-140. In order to employ continuous-cast billet, more profound reduction in the tandem mill is necessary. At present, the reduction is 1.16–1.5 in longitudinal rolling mill 1 and 1.07–1.15 in longitudinal rolling mill 2. With greater reduction, longitudinal guide marks may appear on the pipe surface. A possible approach to decreasing the pipe wall thickening in the groove taper and hence reducing the rejection rate due to longitudinal guide marks is to employ kinematic tension in rolling an oval sleeve on a short mandrel. The influence of the kinematic tension on the pipe shaping in grooves during longitudinal rolling of an oval sleeve is investigated. This method is found to diminish the thickening of the sleeve wall in the groove taper in longitudinal rolling mill 1. That lowers the likelihood of longitudinal guide marks on the pipe’s internal surface. The possibility of increasing the reduction in rolling on an automatic tandem mill is confirmed. 相似文献
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When using continuous-cast billet in pipe rolling, it is expedient to roll the billet prior to broaching, so as to improve the structure and properties of the steel. To that end, a three-high screw-rolling mill for billet reduction has been installed at the TPA-80 pipe-rolling unit at OAO Sinarskii Trubnyi Zavod. Introduction of the new process was associated with increase in the rejection rate on account of indentations in the pipe. These indentations may be attributed to the depression formed at the rear of the billet in reduction and the subsequent formation of metallic semicircles on broaching; the semicircles break away and enter the deformation zone. The sources of the indentations on the rolled pipe are investigated. The broaching of the billet on a screw rolling mill is mathematically simulated. Recommendations are made with a view to reducing the surface defects on pipe produced by the TPA-80 unit with a reduction mill. 相似文献
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In response to the problems arising on introducing a new piercing mill designed by OAO EZTM, the use of continuous-cast billet
of a single diameter is proposed for the manufacture of pipe with a diameter of 219–325 mm; the working profile of the mandrel
is optimized, with the introduction of alternating curvature; and the conditions of billet heating in the annular furnace
prior to piercing are adjusted. 相似文献
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采用斜轧穿孔工艺生产大口径P92铁素体耐热无缝钢管过程中,钢管内表面易产生细小裂纹。通过金相分析、高温相变计算和高温加热试验等研究表明,内表面裂纹产生的主要原因是:中心有通孔的P92管坯在坯料加热过程中,由于加热温度过高和在炉时间过长(即表面氧化脱碳加重),导致管坯通孔近内壁产生大量的高温δ-铁素体相,管坯在随后的斜轧穿孔中,裂纹在塑性较差的高温δ-铁素体处产生和扩展。根据内表面裂纹的产生机制,通过对P92钢管化学成分的铬当量、镍当量按Creq<13%、Nieq>4%进行控制,坯料保温温度由原工艺的1220~1250℃降为1190~1220℃,对穿孔机轧辊转速、辊距和顶伸量参数优化等工艺改进措施,有效地解决了大口径P92无缝钢管内表面易产生裂纹的问题,提高了P92无缝钢管的成材率和生产效率。 相似文献
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Yu. S. Krivchenko V. F. Balakin Yu. D. Ugryumov G. N. Kushchinskii V. V. Perchanik D. Yu. Ugryumov 《Steel in Translation》2010,40(4):363-369
Means of reducing the metal consumption in the hot rolling of seamless pipe are considered. The most common is the use of
square or round continuous-cast billet. The trimming required for Pilger mills may be reduced by preparation of the front
ends of the sleeves in skew rolling and rolling of the rear end at the free section of the mandrel. To expand the range of
pipe to D/S = 15–30 for the 200 system with a three-roller mill, grooves created with special liners in the gaps between the rollers
have been adopted at OAO Interpipe Nizhnedneprovskii Truboprokatnyi Zavod. In addition, the wall thickness is regulated by
means of a hydromechanical clamp. 相似文献
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针对石油管L80-13Cr因加工特殊扣的需要,要求尺寸精度高的情况,通过试验对采用离心坯和锻造坯挤压管的尺寸精度进行了对比分析,结果表明:采用离心浇注管坯挤压钢管,在尺寸精度的控制上要远优于锻坯的挤压钢管,尤其是在壁厚偏心问题上,采用离心浇注管坯作挤压钢管能够得到很好的解决。 相似文献
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本文介绍利用磁检测方法监测无缝钢管冷轧朵芯棒断裂和轴向窜动的基本原理,并给出了实现这种原理的实例。所介绍的芯棒监可以对无缝钢管冷轧机锥形芯棒的断裂和轴向窜动进行连结监视,由于它采用了非晶态合金制成的芯棒位移位感器,因而具有很高的灵敏度和反应速度。 相似文献