There are many important processes in the bearing workshop, such as hot cleaning and rust prevention. When the product is not produced by flow, it will be stored in the intermediate warehouse after one-time sequential processing. Therefore, the bearing rings stored between processes must be rustproof.Antirust Work of Rolling Bearing
Antirust Work of Rolling Bearing
1. Soak in anti rust tank
Immersing the bearing ring in the aqueous solution of 5% sodium nitrite and 0.6% sodium carbonate has good antirust effect, but many antirust tanks and other equipment take up a lot of space and management is not convenient.Antirust Work of Rolling Bearing2. Dip coating concentrated sodium nitrite solution
After cleaning, immerse the product in a solution containing 15% – 20% sodium nitrite and 0.6% sodium carbonate, and then stack it. Using this method, the antirust period is short, which can only be maintained for 7-14 days, and in the rainy season, due to the wet weather, it can only be maintained for 2-3 days
It must be reprocessed, which requires labor and money.Antirust Work of Rolling BearingOiling
Apply antirust oil like finished products. This method must be cleaned before the next process, which is more troublesome.
Introduction of new antirust process
After tackling key problems together with relevant manufacturers, years of production practice shows that the rust prevention between processes has been improved for many times, and the rust prevention effect of spray type is better. At the beginning, the roller rust prevention was tried out.
The semi-finished products and finished products were washed with sodium nitrite aqueous solution once a day. After 3 months, no corrosion was found in the sampling inspection results. Now the semi-finished products of bearing ring are sprayed with rust prevention, and the effect is the same. Spray type antirust process is relatively simple, and its method is as follows:Antirust Work of Rolling Bearing
1. Purchase and construction of equipment
According to the storage quantity of semi-finished products, an intermediate warehouse shall be established, with cement floor on the ground, and a walkway of about 1.5m can be set in the middle to pass the trolley of bearing ring. A water tank for storing sodium nitrite aqueous solution is placed at the end of the channel.
The solution formula is 5% – 10% sodium nitrite plus 0.6% sodium carbonate. A return ditch is made on the ground, and then the bearing rings are stacked on the floors on both sides. A 0.6m walkway is reserved between each pile of bearing rings. It can be said that the design of the intermediate reservoir is about 64m2, and the water tank of sodium nitrite aqueous solution is 1m3.
2. Process method
Wash with sodium nitrite aqueous solution once every morning. The aqueous solution is sucked out of the water tank by the water pump and connected to the shower head through the rubber pipe to wash the bearing ring like spraying. The washed water solution flows back to the pool from the return ditch.
At the upper layer of the pool at the end of the return ditch, a filter screen is made of fine iron mesh and gauze to flow textile dust into the pool. The intermediate warehouse shall be kept clean.Antirust Work of Rolling Bearing
The solution in the pool is tested every two days and supplemented according to the test results. The replacement period of the solution in the pool is carried out according to different months. It is completely replaced every two weeks from April to September, and once a month from October to march of the next year.Antirust Work of Rolling Bearing
Spray type rust prevention is easy to manage and saves labor. In the past, it was impossible to use two people to prevent rust in the intermediate warehouse. Now one person can also do other work. From the perspective of rust prevention effect, it is also very significant. In March 2003, more than 4000 7002136 and 3620 rollers were sprayed for rust prevention.
It has remained very bright and free of corrosion for nearly a year. In addition, the consumption of chemicals is also greatly saved. In the past, the roller workshop used to consume more than 4000 kg of sodium nitrite per month, but now it only uses 200 kg, saving nearly half.Antirust Work of Rolling Bearing
It has been proved that the spraying method is very suitable for large-scale and semi-finished bearings in recent years.Antirust Work of Rolling Bearing
The main causes of corrosion are as follows:Antirust Work of Rolling Bearing
1. In the process of producing bearings, some enterprises did not strictly follow the requirements of cleaning and rust prevention procedures and oil seal rust prevention packaging to carry out rust prevention treatment on the bearing parts in the processing process and the finished bearing products after assembly.
For example, the turnover time of the ferrule in the turnover process is too long, and the outer circle of the outer ring is in contact with corrosive liquid or gas.Antirust Work of Rolling Bearing
2. The quality of antirust, cleaning kerosene and other products used by some enterprises in production can not meet the requirements of process and technology regulations.Antirust Work of Rolling Bearing
3. As the price of bearing steel falls again and again, the material of bearing steel gradually declines. For example, the content of non-metallic impurities in steel is high (the increase of sulfur content in steel reduces the corrosion resistance of the material itself), metallographic structure deviation, etc. At present, the sources of bearing steel used by production enterprises are miscellaneous, and the steel quality is fish dragon mixed beads.
4. The environmental conditions of some enterprises are poor, the content of harmful substances in the air is high, and the turnover site is too small to carry out effective antirust treatment. In addition, the hot weather and the violation of rust prevention regulations by production workers also exist.
5. Bearing packaging materials such as antirust paper, nylon paper (bag) and plastic cylinder of some enterprises do not meet the requirements of antirust packaging of rolling bearing oil seal, which is also one of the factors causing corrosion.
6. The turning allowance and grinding allowance of bearing rings in some enterprises are too small, and the oxide scale and decarburization layer on the outer circle cannot be completely removed is also one of the reasons.
3.2 identification of bearing corrosion
Determine the depth of rust pit, 1 visual observation: observe the corrosion state of imported bearing surface. 2. Further observe the corrosion state of the imported bearing surface with the help of a magnifying glass (5 ~ 10 times). 3 analyze the corrosion products with the help of microscope (25 ~ 100 times). Analyze and find out the causes of corrosion.
4 generally, according to the corrosion level, corrosion can be divided into three types: 5 light rust: the appearance of imported bearings loses metallic luster and appears dark gray. 6 medium rust: yellow, reddish brown, light brown or a small amount of rust powder appears on the surface of imported bearing. 7 heavy rust: the appearance of imported bearing is black flake rust layer or convex rust spot.