昨天写的有关开口弹垫不能防松的文章,评论区惨不忍睹,具体参见:→开口弹簧垫圈在国外为什么被抛弃了?看完弹垫有限元分析结果后,惊出一身冷汗!,显然,嘴硬的机械工程师还有很多,今天请出NASA,放出必杀技。
NASA也是就美国宇航局,针对航空航天产品,NASA制定了自己的标准,其标准不仅包括航空器的设计,还涵盖了最基础的紧固件设计选型。其中,有关紧固件的标准为 NASA Perference Publication 1228Fastener Design Manual,详见下图:
NASA 紧固件设计手册主要内容包括Materials(材料)、Platings and Coatings(镀层和涂层)、Thread Lubricants(螺纹润滑)、Corrosion(腐蚀)、Locking Methods(防松措施)、Washers(垫片)、Inserts(嵌件)、Threads(螺纹)、Fatigue-Resistant Bolts(耐磨损螺栓) 、Fastener Torque(拧紧扭矩)、Design Criteria(设计标准),下面是部分截屏。
特别注意,NASA 紧固件设计手册针对开口弹簧垫圈做了特别说明,具体如下:
The typical helical spring washer shown in figure 14 is made of slightly trapezoidal wire formed into a helix of one coil sothat the free height is approximately twice the thickness of the washer cross section. They are usually made of hardened carbon steel, but they are also available in aluminum, silicon,brome,phosphor-bronze, stainless steel, and K-Monel.The lockwasher serves as a spring while the bolt is being tightened. However, the washer is normally flat by the time the bolt is fully torqued. At this time it is equivalent to a solid flat washer, and its locking ability is nonexistent. In summary, a Iockwasher of this type is useless for locking.
中文翻译:当螺栓拧紧后,开口弹簧垫圈相当于弹簧。然而,当螺栓按规定扭矩拧紧后,开口弹簧垫圈就会变平,此时它相当于一个坚固的平垫圈,其锁定能力(防松能力)是不存在的。总的来说, 这种类型的锁止器对于锁定(防松)是无用的。
虽然是1990年出版的标准,但看完之后,感觉不但不落后,反而遥遥领先。我很早之前就听说过NASA有关开口弹垫的说法,但一直没有证实,今天特意去NASA官网找到了Fastener Design Manual,虽然是个推荐性的标准,但其权威性不容置疑。
当我在NASA官网找到这个紧固件标准的时候,当时感觉真的是如获至宝,而且我看的也是津津有味,其实知识并不枯燥,枯燥的是教材和教我们的人。
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