Common misunderstandings of standard parts:
One: in the coarse
The important couplings on the machine, such as the drive shaft, the flying shaft, etc., the bolts are mostly made of fine thread. When there is a missing piece in the repair, someone replaces it with a coarse bolt. Due to the large inner diameter of the fine bolt, the small pitch and the outer angle are small, the strength is high, the self-locking performance is good, and the ability to withstand impact, vibration and exchange load is strong; after being replaced by the coarse-toothed bolt, it is easy to loosen or take off and break. , causing mechanical accidents.
Two: pores do not match
Bolts (such as drive shaft bolts and flywheel bolts) that are subjected to lateral loads and shear forces on the machine, and their mating with the bolt holes are transition fit, and the assembly should be strong and reliable, and can withstand lateral forces. Some people do not pay attention to the inspection during assembly. When there is a large gap between the bolt and the bolt hole, it is still installed. As a result, the bolt is loose or cut off.
Three: thickened nuts
Some people often mistakenly believe that thickening the nut can increase the number of working turns of the thread, thereby improving the reliability of the coupling. In fact, the thicker the nut, the more uneven the load distribution between the threads of each ring, and the more easily the coupling is loose.
Four: one mother multi-pad
In the installation, sometimes the bolts after assembly are too long, so some people put a lot of spring washers on one bolt, so that the spring washers are unevenly stressed during the sturdy process, and some will break, so that the bolts are pre-tightened. The force is reduced; or an eccentric load is generated, which reduces the reliability of the bolt connection.
Five: the gasket is too large
Sometimes, due to the lack of a suitable gasket, someone replaces it with a gasket with a larger inner diameter. In this way, the contact area under the bolt head with the washer is small, the bearing pressure or the locking force of the washer is lowered, and the bolt is easy to loose under the action of vibration and impact load.
Six: Torque does not match
Many people think that the bolts should be “never tightâ€, so they consciously increase the tightening torque of the bolts, resulting in bolt slips. On the other hand, for the important bolts that need to be tightened by torque, there are some people who use the adjustable wrench. To unscrew, the result is often loose due to insufficient torque, resulting in mechanical failure.
Seven: improper lockup
Important bolts should be locked after installation. When using the split pin to lock, the common mistake is to use a thin open lock or a half-piece open lock; the common mistake is to lock the washer opening too small, lose the elasticity; lock with the lock piece The common mistake is to lock the locking piece at the corner of the nut; the common mistake of locking with a double nut is to put the thinner nut on the outside and not tighten it tightly.
Eight: false and solid
Bolts, nuts or screw holes have rust, scale, iron filings, sand and other impurities, or the joint surface of the coupling has burrs, sand and other impurities, which are not removed before assembly. When tightening the bolts, due to impurities Blocking effect, the surface is tightened very tightly, the torque value has reached the requirement, but in fact the coupling is not really compressed; in addition, there is a case, due to the action of the sludge, scale and other impurities in the screw hole, Although the bolt torque is in compliance, the work piece is not compressed. Under such false sturdiness, vibration, load shock and temperature changes often cause the bolt to loosen quickly.
The full ceramic ball bearings listed below are supplied with rings and balls made from zirconium dioxide (ZrO2). These zirconia bearings are available as full complement (no cage) or with cages made from PTFE, PEEK or 316 stainless steel.
These are non magnetic, non-conductive and highly corrosion resistant to most chemicals although ZrO2 bearings are not recommended for prolonged contact with steam. Full complement bearings or those with a 316 stainless cage can be used up to 400°C while bearings with a PEEK or PTFE cage can cope with temperatures of up to 250°C. For temperatures below -70°C, PTFE or 316 stainless steel cages are preferred. Standard radial clearance for full ceramic bearings is C0 but other clearances can be supplied to order.
ZrO2 ceramic bearings are generally used for their extreme temperature capabilities, excellent corrosion resistance or non-magnetic properties. Other sizes can be supplied on request.
The Description of Ceramic Bearings:
Compared to steel, Ceramic ball Bearings have many specific advantages. They offer superior corrosion and heat resistance, higher dimensional stability, and lower density, which facilitate high speed. Ceramics are superior to steel in heat and corrosion resistance, and are lightweight and extremely hard as well. Consequently, ceramic rolling bearings can be used in environments where conventional steel bearings cannot. That is to say, the superiority of these bearings makes it possible that they can be applied in some special environments.
Firstly, they can be used in corrosive environments. Compared to stainless steel bearings, hybrid and all Ceramic Bearing lasted three and twenty times longer respectively. It is presumed that water readily adheres to silicon nitride and forms a better lubrication film, leading to extended bearing life.
Secondly, they can be performed in corrosive agents. Generally, silicon nitride has excellent corrosion resistance. However, corrosion resistance varies depending on the type and quantity of sintering additives, and certain corrosive agents decrease in hardness and flexural strength. In such situation, it is can be proved that the carbide-based ceramic bearings are the most effective.
Thirdly, they can be used in high-temperature vacuum. An all-silicon nitride Ball Bearing with a self-lubricating laminated cage (mainly composed of MoS2) and with MoS2-coated rings and balls proved superior in durability in a high-temperature vacuum environment. Compared with the hybrid bearings, the all-ceramic bearing was superior in both dynamic frictional torque and life.
Fourthly, they can be performed with poor lubrication. As ceramics are extremely hard and have outstanding wear resistance, they outperform other materials in bearing life without lubrication. According to a test, the steel bearing seized within a short period while the hybrid and all 627 Ceramic Bearings, though sustaining wear, did not. And the all-ceramic bearing sustained considerably less wear than the hybrid bearing, indicating that its endurance life is much longer.
Cermic Ball Bearing,Full Ceramic Bearing,Hybrid Ceramic Bearing,Self-Aligning Full Ceramic Ball Bearing
Shijiazhuang Longshu Mechanical & Electrical Equipment Trading Co., Ltd. , https://www.lsjgbearing.com