The materials used in the manufacture of bearing housings and gearboxes

The materials used in the manufacture of bearing seats and reducers are generally gray cast iron.

Gray iron is the first stage of graphitization process and the formation of cast iron, all or most of the carbon in the form of flake graphite, the fracture is gray and dark, hence the name, it includes general gray cast iron (referred to as gray cast iron), ductile iron, hemp cast iron, inoculated cast iron, rare earth gray cast iron, etc. The appearance of the fracture of gray cast iron is light gray, so it is called gray cast iron (gray iron). This is cheap and widely used, and gray cast iron accounts for more than 80% of the total output of cast iron.

It is mainly used in machine tool bed, gearbox, pulley, base, cylinder block, cover, handwheel and other parts that are not stressed, wear-resistant, and shock-absorbing.

The structure of the box is not very complicated, it is recommended to use cast iron, HT250 is used for half of the requirements, and ductile iron can be used for the high point of the requirements.

The structure is complex, it is recommended to use welded parts, and the box is welded with 45 steel plates, and the thickness is determined according to the size of the box.

Half of the bearing housing of the welded gearbox housing is cut from steel castings.

In casting, as we all know, gray cast iron has good shock absorption and is suitable for bearing static loads. At the same time, the flake graphite structure in the material can use the graphite itself to lubricate and store grease, which helps lubricate. In practice, HT250 grades are commonly used, especially the inner cavity of the reducer is mostly casting.

Reducer. The main material of the spindle is carbon steel.

Such as 45 steel. or alloy steel (such as 40cr), which can withstand both bending moment and torque when working, and needs to have high strength and good toughness. Its working capacity is generally determined by strength and stiffness, and at high speeds, by vibration stability.

The selection of spindle and shaft materials and heat treatment must take into account the amount of force, bearing type and spindle shape, as well as possible heat treatment defects. The shaft rotates in rolling bearings, the journal does not require a particularly high hardness, 45 steel and 45cr steel can be used, and the final hardness after heat treatment is 220 250HB.

The axial positioning of the parts on the shaft is guaranteed by the shaft shoulder, sleeve, round nut, shaft end ring and bearing end cover, etc., as follows:

1. Shaft shoulder: divided into two categories: positioning shaft shoulder and non-positioning shaft shoulder, the use of shaft shoulder positioning is the most convenient and reliable method, but the use of shaft shoulder will inevitably increase the diameter of the shaft, and the shaft shoulder will be caused by the sudden change of cross-section and cause stress concentration. In addition, when there are too many shoulders, it is not conducive to machining.

Therefore, shoulder positioning is mostly used in the occasion of large axial force.

2. Sleeve positioning: simple structure, reliable positioning, no need to slot, drill and cut threads on the shaft, so it does not affect the fatigue strength of the shaft, and is generally used for positioning between two parts on the shaft.

3. Round nut: the positioning can withstand large axial force, but there is a large stress concentration at the thread on the shaft, which will reduce the fatigue strength of the shaft, so it is generally used for the parts that lack Huqing to fix the shaft end, and there are two types of double round nut and round nut and stop gasket. When the distance between the two parts on the shaft is large and it is not suitable to use the sleeve positioning, the round nut is also often used for positioning.

4. Shaft end retaining ring: suitable for fixing shaft end parts, which can withstand large axial force.

5. Bearing end cover: the outer ring of the rolling bearing is axially positioned by connecting with the box with screws or tongues and grooves.

In general, the axial positioning of the entire shaft is also often achieved by means of bearing end covers. The use of elastic retaining rings, set screws and locking rings for axial positioning is only suitable for places where the axial force on the part is not large. Set screws and locking rings are commonly used for the positioning of parts on optical shafts.

The general shaft is made of 45 steel, and the good point is 40cr, and iron cannot be used to make the shaft, and the material of the shaft must be tough, and the quenching hardness can meet the requirements of use. Unimportant shafts can be turned with round bars, and the shafts of the general reducer are forged blanks and then turned, quenched and then grinded.

The materials used for the transmission shaft are mostly 40cr, quenched and tempered. There are also 35crmo's. For individual requirements, 38crmoal can be used.

Slewing plate bearing housing is a kind of large and extra-large bearing housing that can accept comprehensive load and special structure, which has the characteristics of compact structure, sensitive rotation and convenient device maintenance. Where there is a bearing, there must be a support point, the inner support point of the bearing is the shaft, and the external support is the bearing seat that is often said.

Because a bearing can choose different bearing housings, and a bearing housing can also choose different types of bearings, therefore, there are many varieties of bearing housings. Bearing seats are included in the fast and easy to be excellent, and many large foreign bearing companies also have their own bearing housing catalogs. However, the same housing model is not exactly the same in different company samples.

For different applications with standard housings, housings of different materials such as grey cast iron, ductile iron and special housings of cast steel, stainless steel and plastic are available.

According to the different requirements of bearings and bearing seats, the classification of bearing seats is not exactly the same, and it is necessary to carefully check the selection of pins according to the design when using.

1. Classification according to the shape of the bearing seat:

1. Outer spherical mounted bearing, also known as bearing unit (SKF's term). When there is no bearing, it is called an outer spherical bearing seat. The outer spherical bearing housing is divided into 200 series according to the series of bearings.

500 series. 300 series. 600 series.

XOO series.

2. The outer spherical bearing seat is divided into vertical seat (P seat Hedoupai), square seat (F seat), diamond seat (FL seat), round seat (C seat), boss round seat (FC seat), boss square seat (FS seat), dark hole seat (PA seat), hanging seat (FA seat).

3. Integral (i.e., non-separate) plummer block housing with screw-fastened bearing cover. These plummer block housings were originally developed as axle cases for light rail trucks, but can also be used in conventional plummer block housings. Non-separating plummer block housings are more rigid than split housings and some can withstand heavier loads.

The outer spherical bearing housing is also a monolithic housing.

Second, split bearing housing.

Split bearing housing, according to the different optional bearings and the requirements of the shaft, SNL2, SNL5, SD have

Bearing housings are divided into: split bearing housings, sliding bearing housings, rolling bearing housings, bearing housings with flanges, outer spherical bearing housings, etc.

There are many types of bearing housings and gearboxes, mainly depending on the application. The manufacturing material is selected according to the purpose of the gearbox.

The general shaft is made of 45 steel, and the good point of the reputation is 40cr, and iron cannot be used to make the shaft, and the material of the shaft must be tough, and the quenching hardness can meet the requirements of use. The important shaft can be turned with round steel, and the shaft of the general reducer and silver is forged blank and then turned, quenched and then grinded.

The commonly used materials for transmission gears are:

Forged steel. 1. Forged steel.

According to the hardness of the tooth surface, it is divided into two categories.

hb<350

, it is called a soft tooth surface.

h8>350

, it is called a hard tooth surface.

l Tooth surface hardness.

hb<350

Process: forging blank. Normalizing.

Rough turning. Quenching and tempering, finishing.

commonly used materials; #

35simn

40cr40crni

40mnb Features:

It has good comprehensive performance, the tooth surface has high strength and hardness, and the tooth core has good toughness.

After heat treatment, the cutting accuracy can be reached.

Level. The manufacturing is simple, economical, and the productivity is high, and the precision requirements are not high.