鎖固施工上 , 最最最重要的是 ~~轉速~~

空冷器的內外牙之間的間隙相當大

假如以氣動打擊板手高達 3000 rpm 的轉速"轟"一下轉進去

公牙跟母牙的旋入是非常粗暴的

每次做就每次刮傷(galling)一點

每刮傷一點 , 公牙與母牙的摩擦力就增加一點

要再拆出來就再更用力一點 !!

那時壽終正寢就要看運氣了 , 希望不是操作中..

氣動扭力板手 ; 油壓扭力板手 ; 手動扭力板手都會是比較好的選擇

總之...請斯文一點 , 溫柔一點 !!

其中氣動扭力板手又快又輕便 ; 轉速約 50 rpm ; 是其中的首選

最後就是螺牙潤滑劑 molykote 的選擇 ,

它們肩負降低摩擦力與避免刮傷的重責大任 ,

不過堵頭內外牙間的 molykote 是會浸在製程流體中的喔

在選擇上也是有特別的型號的

特別是不銹鋼的堵頭 ,

假如molykote 不好 , 抹不夠 , 或是內外螺牙清潔不夠

鎖固時磨擦力大 ,

不鏽鋼的強度低 , 抵抗摩擦力與刮傷的能力弱 ,

鎖的時候看是沒事 , 實際上已經傷痕累累 ,

下次拆就得狂出力拆 ; 拆出來也崩牙了 ~~

不鏽鋼的話我們推薦這種 :

簡單說起來

要預防崩牙

就是要注意

1 螺牙的清潔

2 正確的潤滑

3 低轉速 , 低扭力加鎖

4 鎖不住 , 整修墊圈面與螺牙 , 千萬別硬鎖

下面有段英文文章 , 我覺得寫得很好 , 轉貼一下給大家參考

Galling

Thread galling is a common, yet seldom-understood problem with threaded fasteners. Galling is often referred to as a cold-welding process, which can occur when the surfaces of male and female threads comein contact with heavy pressure. The truly annoying aspect of fastener galling is that these same nuts andbolts are found to meet all required inspections (threads, material, mechanical, etc.), but yet they are stillnot functioning together.

Stainless steel fasteners are particularly susceptible to thread galling, although it also occurs in other alloys which self-generate an oxide surface film for corrosion purposes, such as aluminum and titanium. During the tightening of the fastener, a pressure builds between the contacting thread surfaces and breaks down the protective oxides. With the absence of the oxide coating, the metal high points can shear and lock together.

Minor galling may cause only slight damage to the thread surface and the fastener may still be removed. However, in severe cases, galling can completely weld the nut and bolt together and prevent removal of the fastener. Often times, once galling begins, if the tightening process is continued, the fastener may be twisted off or its threads stripped out.

Unfortunately, even with an understanding of the mechanism of galling, little is known on how to successfully control it. However, the probability of galling occurring can be minimized with the following measures:

• Thread lubrication is one of the most effective measures to lessen the potential for galling. The lubricant reduces friction, which is a key element in thread galling. Certain material environments, such as stainless steel fasteners used in food processing equipment, preclude the use of some lubricants. Also, attention must be given to the torque-tension relationship, which will be altered with the use of lubrication.

• Use coarse threads with a 2A-2B fit instead of fine threads. Coarse threads have a larger thread allowance and are more tolerant to abuse during handling.

• Heat contributes significantly to thread galling. Installing a fastener generates heat and high-speed installation generates significantly more heat. Lowering the wrench speed during installation and removal can be helpful.

• Avoid prevailing torque locknuts. The function of a prevailing torque locknut is to add resistance to the threads. This resistance also creates friction and heat. If a prevailing torque locknut must be used, ensure a minimal amount of threads are protruding beyond the nut.

• Mating parts of the same alloy have a greater tendency to gall than parts of dissimilar alloys having different degrees of hardness. Most stainless steels are more susceptible to galling than carbon and alloy steels. However, not all ombinations of stainless steels act the same. For instance, a 400 series stainless steel nut can work well on 316 series bolts, but with a reduction in corrosion resistance.

• A smoother surface texture will lead to less frictional resistance. Rolled threads usually offer smoother surfaces than cut threads. As previously mentioned, friction increases the possibility of galling.

• Proper installation torque. If the fastener is over tightened, the threads can begin to yield which will induce friction between the mating surfaces.

回到首頁