1. The processing of steel balls is also different according to the state of raw materials. Among them, the process before chipping or polishing can be divided into the following three types, and the process before heat treatment can be divided into the following two types. The whole processing process is: cold stamping of bars or wires (some bars need to be punched and annealed after cold stamping)-chipping, rough grinding, soft grinding or polishing.
2. Processing technology of roller The processing of roller is different according to different raw materials, and the process before heat treatment can be divided into the following two types. The whole processing process is as follows: lathing bar or cold heading wire, soft grinding of endless belt string-heat treatment-soft spot string-rough grinding of outer diameter-rough grinding of end face-final grinding of end face-fine grinding.
Rolling bearing knowledge
Section 1 Basic Structure of Rolling Bearing
Rolling bearing is developed on the basis of sliding bearing, and its working principle is to replace sliding friction with rolling friction. Generally, it consists of two rings, a group of rolling bodies and a cage, and it is a mechanical basic part with high universality, standardization and serialization. Due to the different working conditions of various machines, different requirements are put forward for the bearing capacity, structure and performance of rolling bearings. Therefore, rolling bearings need to have various structures. But the most basic structure is composed of inner ring, outer ring, roller and cage.
The functions of each part in the bearing are as follows:
For radial bearings, the inner ring usually works closely with the shaft, and the outer ring usually works with the hole of the bearing seat or mechanical shell to play a supporting role. But in some cases, there is also an outer ring running, and the inner ring is fixedly supported or the inner ring and the outer ring run at the same time. For thrust bearings, the shaft ring that closely matches with the shaft and moves together, and the seat ring that transitional matches with the hole of the bearing seat or the mechanical housing and plays a supporting role. Rolling bodies (steel balls, rollers or needle rollers) are usually evenly arranged between two rings in the bearing in the form of cages for rolling motion, and their shape, size and quantity directly affect the bearing capacity and service performance of the bearing. The cage can not only separate the rolling elements evenly, but also guide the rolling elements to rotate and improve the internal lubrication performance of the bearing.
Section 2 Classification of Rolling Bearings
1. According to the structural types of rolling bearings.
(1) bearings can be divided into:
1) radial bearing-it is mainly used to bear radial load, and its nominal contact angle ranges from 0 to 45. According to the difference of nominal contact angle, it can be divided into: radial contact bearing-radial bearing with nominal contact angle of 0; Radial angular contact bearing-a radial bearing with a nominal contact angle greater than 0 to 45.
2) Thrust bearing-a rolling bearing mainly used for bearing axial load, whose nominal contact angle is greater than 45 to 90. According to the different nominal contact angles, it can be divided into: axial contact bearing with a nominal contact angle of 90-thrust bearing; Thrust angular contact bearing-a thrust bearing with a nominal contact angle greater than 45 but less than 90.
(2) The bearing is divided into:
1) ball bearing-the rolling body is a sphere;
2) Roller bearing-The roller is a roller. Roller bearings are divided into: cylindrical roller bearings-bearings with cylindrical rollers, and the length-diameter ratio of cylindrical rollers is less than or equal to 3; Needle roller bearing-the rolling body is a needle roller bearing, and the ratio of the length to the diameter of the needle roller is greater than 3, but the diameter is less than or equal to 5mm-the rolling element is a tapered roller bearing; Self-aligning roller bearing-The roller is a spherical roller bearing.
(3) Bearings can be divided into:
1) Self-aligning bearing-the raceway is spherical and can adapt to the angular deviation and angular movement between the two raceway axes;
2) Non-self-aligning bearing (rigid bearing)-a bearing that can resist the axis angle deviation between raceways.
(4) The bearing is divided into:
1) single row bearing-bearing with a row of rolling elements;
2) Double row bearing-bearing with two rows of rolling elements;
3) Multi-row bearings-bearings with more than two rows of rolling elements, such as three rows and four rows of bearings.
(5) Bearings can be divided into:
1) separable bearing-bearing with separable parts;
2) Non-separable bearing-bearing whose rings cannot be separated at will after the bearing is finally assembled.
(6) Bearings can be divided into various structural types according to their structural shapes (such as whether there is a filling groove, whether there is an inner ring, an outer ring, the shape of a ring, the structure of a flange, and even whether there is a cage).
2. According to the size of the rolling bearing, the bearing can be divided into:
(1) miniature bearing-bearing with nominal outside diameter less than 26 mm;
(2) Small bearings-bearings with a nominal outer diameter of 28-55 mm;
(3) Small and medium-sized bearings-bearings with a nominal outer diameter of 60- 1 15mm;
(4) Medium and large bearings-bearings with nominal outside diameters ranging from 120 to190mm.
(5) Large bearings-bearings with a nominal outer diameter of 200-430mm;
(6) Extra-large bearing-bearing with nominal outer diameter exceeding 440mm. ..
Section III Basic Production Technology of Rolling Bearings
Because the types, structural types, tolerance grades, technical requirements, materials and batches of rolling bearings are different, their basic production processes are not exactly the same.
A, all kinds of bearing main parts processing technology:
1. Processing technology of rings: According to different raw materials or blank forms, the processing of bearing inner rings and outer rings is also different. Among them, the process before turning can be divided into the following three types. The whole processing process is: bar or tube (some bars need forging, annealing and normalizing)-turning-heat treatment-grinding.
2. Steel ball processing, steel ball processing also varies with the state of raw materials. Among them, the process before chipping or polishing can be divided into the following three types, and the process before heat treatment can be divided into the following two types. The whole processing process is: cold stamping of bars or wires (some bars need to be punched and annealed after cold stamping)-chipping, rough grinding, soft grinding or polishing.
3. Processing technology of roller The processing of roller is different according to different raw materials, and the process before heat treatment can be divided into the following two types. The whole processing process is as follows: lathing bar or cold heading wire, soft grinding of endless belt string-heat treatment-soft spot string-rough grinding of outer diameter-rough grinding of end face-final grinding of end face-fine grinding.
4. Processing technology of the cage The processing technology of the cage can be divided into the following two categories according to the different design structures and raw materials:
(1) plate → cutting → punching → punching → shaping and finishing → pickling or shot blasting or stringing → final inspection → rust prevention → packaging → storage (to be assembled and assembled).
(2) Processing technology of solid cage: The processing of solid cage varies according to different raw materials or hairiness. Before turning, it can be divided into the following four blank types. The whole processing process is: bar, pipe, forging, casting-turning inner diameter, outer diameter, end face, chamfering-drilling (or broaching and boring)-.
Second, the rolling bearing assembly process:
Rolling bearing parts, such as inner ring, outer ring, roller and cage, etc. After passing the inspection, enter the assembly workshop for assembly. The process is as follows:
Demagnetization cleaning of parts → grouping selection of internal and external rolling groove dimensions → assembly → checking clearance → riveting cage → final inspection → demagnetization cleaning → rust prevention and packaging → entering finished product warehouse (packaging and delivery).
Section 4 Characteristics of Rolling Bearing
Compared with sliding bearings, rolling bearings have the following advantages:
1. The friction coefficient of rolling bearing is smaller than that of sliding bearing, and the transmission efficiency is high. Generally, the friction coefficient of sliding bearing is 0.08-0. 12, while that of rolling bearing is only 0.00 1-0.005.
2. Rolling bearings have been standardized, serialized and generalized, which are suitable for mass production and supply, and are very convenient to use and maintain;
3. Rolling bearing is made of bearing steel and heat treated. Therefore, rolling bearings not only have higher mechanical properties and longer service life, but also can save more expensive non-ferrous metals used in manufacturing sliding bearings;
4. The internal clearance of the rolling bearing is very small, and the machining accuracy of each part is high, so the running accuracy is high. At the same time, the stiffness of the bearing can be increased by preloading. This is very important for precision machinery;
5. Some rolling bearings can bear radial load and axial load at the same time, so the structure of bearing seat can be simplified;
6. Because the rolling bearing has high transmission efficiency and low calorific value, it can reduce the consumption of lubricating oil and save the trouble of lubrication and maintenance;
7. Rolling bearings can be conveniently applied to uranium in any direction in space.
However, everything is divided into two, and rolling bearings also have certain shortcomings, mainly:
1. The bearing capacity of rolling bearing is much smaller than that of sliding bearing with the same volume, so the radial dimension of rolling bearing is larger. Therefore, sliding bearings are often used in occasions (such as crankshaft bearings of internal combustion engines) that bear heavy loads and require small radial size and compact structure.
2. The vibration and noise of rolling bearings are relatively large, especially in the later period of use. Therefore, it is difficult for rolling bearings to be competent when high precision is required and vibration is not allowed. Generally, sliding bearings are better.
3. Rolling bearings are particularly sensitive to foreign bodies such as metal chips. Once a foreign object enters the bearing, it will produce intermittent large vibration and noise, and it will also cause early damage. In addition, rolling bearings are also prone to early damage due to metal inclusions. Even without early damage, the life of rolling bearings is limited. In a word, the life of rolling bearing is shorter than that of sliding bearing.
However, compared with sliding bearings, rolling bearings have their own advantages and disadvantages, and each has its own applicable occasions. Therefore, the two cannot completely replace each other, and each develops in a certain direction and expands its own field. However, due to the outstanding advantages of rolling bearings, the latecomers have great potential to catch up. At present, rolling bearing has developed into the main supporting type of machinery, and its application is more and more extensive.