JOJI bearings produce all kinds of ball bearings and roller bearings with outside diameters ranging from 3mm to 4.25m, including standard products according to samples and non-standard products according to users' special requirements.JOJI bearings provide customers with a series of comprehensive and perfect services and technical support, including: inspection, maintenance and mounting and dismounting of bearings and bearing systems.
As a forward-looking enterprise, JOJI bearings have also invested a lot of money in research and development. Modern simulation technology, testing equipment and special materials laboratories provide reliable support for the continuous development and improvement of individual product lines, as well as for maintaining JOJI Bearing's strong innovation capability.
Application Areas
JOJI has a complete range of products in the rolling bearing industry. It covers all applications in the production machinery, power transmission and railway, heavy industry and consumer goods industries.
Deep groove ball bearings
JOJI Deep Groove Ball Bearings
JOJI deep groove ball bearings are universal, self-retaining bearings with solid outer and inner rings and ball and cage assemblies. These products are simple in design, have a long service life and are easy to maintain; they are available in single and double row designs as well as open and sealed designs. Due to the production technology used, open bearings can still be turned into recesses on the outer ring for sealing or protection.
Due to their low friction torque, they are suitable for high speeds.
Contact ball bearings
Single row angular contact ball bearings are self-retaining units with solid inner and outer rings, as well as balls and cage assemblies made of nylon, steel or brass. The inner and outer raceways are offset from each other in the axial direction of the bearing. There are open and sealed bearings. They have very little self-aligning capability.
Many sizes of angular contact ball bearings are of JOJI design. These bearings are shown in the dimension tables.JOJI quality bearings have an improved raceway shape and optimised surfaces. This results in a significant increase in the fatigue limit loads of the bearings. In the corrected service life calculation, the life values are increased by more than 50 per cent. As a result, smaller bearings can be used where necessary for specific applications.
Double row angular contact ball bearings are units consisting of solid inner and outer rings, and balls and cages made of polyamide, pressed steel sheet, or brass. They are structurally similar to single row angular contact ball bearings with a pair of O-shaped arrangements, but are more compact. They are available with different sizes of contact angles and designs of bearing rings.
The bearings can be open and sealed. Due to the production technology used, open bearings have cut grooves in the outer ring for seals or dust caps. Sealed bearings require no maintenance and are particularly suitable for economical bearing applications. Angular contact ball bearings have a small self-aligning range.
Roller bearings
JOJI cylindrical roller bearings
Single row cylindrical roller bearings with cage are a combination of an integral inner and outer ring, cylindrical roller and cage assembly. The outer ring has rigid retaining edges or no retaining edges on both sides, and the inner ring has one or two rigid retaining edges or no design retaining edges. The cage prevents the cylindrical rollers from coming into contact with each other while rolling.
Cylindrical roller bearings are rigid enough to support high radial loads and have cages that make them more suitable for high speeds than full complement designs. Bearings with the suffix E have a larger set of rollers and are designed for extra high load carrying capacity.
The bearings are detachable, which makes mounting and dismounting easier. The two bearing rings therefore have an interference fit.
Single row cylindrical roller bearings with cages can be used as non-locating bearings, semi-locating bearings and locating bearings.
High-precision cylindrical roller bearings are double row precision bearings for machine tools. Allows radial stiffness and high precision bearing configurations, primarily for spindle radial support.
Includes an integral outer ring with no retaining edges, an integral inner ring with three retaining edges, cylindrical rollers and a cage assembly with brass cages. In order to achieve Z-optimal assembly for radial internal clearance, the inner ring is designed with a tapered bore with a taper of 1:12. The cylindrical roller bearings are dismountable and thus designed for easy removal. The two bearing rings thus have an interference fit.
Full complement cylindrical roller bearings have integral inner and outer rings and edge-guided cylindrical rollers. Due to the large number of rolling elements, these bearings have an extremely high centripetal load carrying capacity, high rigidity and are suitable for particularly compact designs. Due to the kinematic conditions, they cannot reach the high speeds possible with cylindrical roller bearings with cages.
Full complement cylindrical roller bearings can be used as non-locating bearings, semi-locating bearings and locating bearings. They are available in single-row and double-row designs.
Four-row cylindrical roller bearings are used as a specialised bearing with high load carrying capacity and high limiting speeds in a limited space. Featuring no retaining edge of the inner ring and simple structure, they can therefore be manufactured with higher accuracy levels and can be fitted with inner and outer ring assemblies separately. It is suitable for the work rolls and support rolls of all kinds of cold and hot rolling mills where the replacement of rolls is frequent. It is the preferred type of bearing for all types of mill rolls.
1.Structure type
Four rows of cylindrical roller bearings have four basic structure types as shown below.
FC type: (an inner ring) four rows of cylindrical roller bearings.
FCE type: FC type of improvement, the outer ring without the edge of the block (roller length lengthening), keep frame for the window structure, can make the load carrying capacity than FC type is about 20% higher, so also known as strengthened type.
FCD type: double inner circle four rows of cylindrical roller bearings.
FCDP type: outer ring with flat retaining ring double inner circle four rows of cylindrical roller bearings.
The basic structure of the four rows of cylindrical roller bearings its outer ring and FCDP type spacer radial diameter are lubricating oil groove, oil holes.
2.Cage
JOJI tapered roller bearings
Bearing outside diameter less than 400 keep frame generally for brass car system entity type, bearing outside diameter more than 400 FCDP type generally for steel through the rod type (also known as pin shape, because can be loaded into more roller and than with brass car system entity type keep frame bearing capacity).
Manufacturing tolerances are available in grades 0, 6 and 5.
4.Radial clearance
General radial clearance for 3 or 4 groups, some special conditions also choose 0 or 2 groups.
Tapered roller bearings
Tapered roller bearings are made up of solid outer and inner rings with tapered groove plates and tapered rollers with cage. The bearings are not self-retaining. Therefore the inner ring with rollers and cage can be separated from the outer ring. Tapered roller bearings can support axial loads originating from the same direction as well as high radial loads. They usually have to be axially adjusted in a mirror image arrangement to match the second bearing.
Drum roller bearings
Drum roller bearings are single row, self-aligning roller bearings. They consist of a solid outer ring with spherical raceways, a solid inner ring with two flanges and a cylindrical or tapered bore, and drum rollers with cages. The bearings are not detachable.
Drum roller bearings are particularly suitable for use where high radial shock loads occur and misalignments must be compensated. See Compensation of misalignments. Their axial load carrying capacity is small. [2]
Bearing housings
JOJI Bearing Units and Bearing Boxes
JOJI bearing units and bearing housings have been successfully used in machinery, plants and other equipment in tried and tested applications.JOJI bearing housings are generally made of grey cast iron material. Cast steel and spheroidal graphite cast iron housings are also available on request. Most housings do not have lubrication holes because the bearings are usually lubricated with lubricating oil, which can be maintained for a long time after the initial greasing. However, the housings are marked so that lubrication holes can be drilled if required. When relubricating, it is important to ensure that any excess lubricant can be spilled.
The housing bore is usually machined to allow the bearing to move within it and can be used as a non-locating bearing. Locating bearing configurations can be achieved by inserting locating rings, if listed in the tables. Locating rings must be specially ordered. Housings without locating rings are used in non-locating bearing versions (L) or locating bearing versions (F).
All unprocessed external surfaces of JOJI housings and housing parts are coated with a universal paint (colour RAL 7031, blue-grey) which can be covered with all resins, polyurethanes, acrylics, epoxy resins, chlorinated rubbers, cellulose as well as acid-hardening hammered grey magnetic paints. The corrosion protection of the processed inner and outer surfaces can be easily removed. Depending on the operating conditions, contact seals, non-contact seals and combinations thereof are available for sealing bearing housings.
JOJI spherical plain bearings, rod end bearings
Maintenance-free JOJI spherical plain bearings / cylindrical plain bearings
JOJI spherical plain bearings require maintenance.
Maintenance-free JOJI rod end bearings
JOJI rod end bearings require maintenance
JOJI rod-end bearings for hydraulic applications
Measures
Damage condition:When JOJI bearings are rotated under load, the raceway surface or rolling face of the inner ring and outer ring show fish scale-like peeling phenomenon due to rolling fatigue.
Cause:Excessive load. Poor installation (non-linear) moment load foreign body intrusion, water. Poor lubrication, inappropriate lubricant JOJI bearing clearance is not appropriate.JOJI bearing box precision is not good, JOJI bearing box rigidity uneven shaft deflection large rust, erosion points, abrasions and indentation (surface deformation phenomenon) caused by the development.
Measures:Check the size of the load and re-examine the use of JOJI bearings to improve the installation method to improve the sealing device, downtime rust prevention. Use lubricants of appropriate viscosity and improve lubrication methods. Check the accuracy of the shaft and JOJI bearing case. Check the clearance.
Damage condition:Presenting a dark surface with slight wear, multiple tiny cracks on the dark surface from the surface inwards as deep as 5-10m, and tiny peeling off (tiny peeling) over a wide area
Cause:The lubricant is not suitable. Foreign matter has entered the lubricant. Poor lubricant causes surface roughness. The surface finish of the matched rolling parts is not good.
Measures: Select lubricant and improve the sealing device to improve the surface finish of the paired rolling parts.
Stuck
Injury status: the so-called card injury is due to the sliding surface injury produced by the part of the tiny burns summary of the surface damage. Slideway surface, rolling surface of the circumferential direction of the line-shaped scar. Roller end face of the pendulum line scar near the roller end face of the collar surface of the jamming.
Cause:Excessive load, excessive preload. Poor lubrication. Bite of foreign matter. Tilt of inner ring outer ring, shaft deflection. Poor accuracy of shaft and JOJI bearing box.
Measures:Check the size of the load. Pre-pressure should be appropriate. Improve the lubricant and lubrication method. Check the accuracy of the shaft and JOJI bearing box.
Fracture
Damage status:The so-called fracture refers to a small part of the fracture due to the local part of the raceway wheel's retaining edge or roller angle to apply music impact or excessive load.
Reason:The mounting was hit. Excessive load. Poor use such as dropping.
Measures: Improve the installation method (hot mounting, the use of appropriate tool clamps). Correct load conditions.JOJI bearings are mounted in place so that the retaining edge is supported.
Cracks, cracks
Damage status:The so-called crack is the raceway wheel or rolling body to produce crack damage. If continue to use, will also include crack development of cracks.
Cause:Excessive overload. Excessive loads, shock loads. Stripping has developed. Heat generation and micro-vibration wear due to contact between the raceway wheel and the mounting member. Heat generation due to creep. Poor taper angle of the tapered shaft. Poor cylindricity of the shaft. The radius of the fillet of the shaft step is larger than the chamfer of the JOJI bearing, causing interference with the chamfer of the JOJI bearing.
Measures:Appropriate amount of interference. Check the load conditions. Improve the installation method. Shaft shape should be appropriate.
Indentation
Damage: Indentation on the raceway surface or rotating surface caused by the ingress of small metal powder or foreign matter. The rolling surface is indented (Brinell hardness indentation) at the pitch interval of the rolling element due to an impact during installation.
Cause:Foreign matter such as metal powder biting into the surface. Excessive impact load during assembly or transport.
Measure: Shock the bushing. Improve the sealing device. Filter the lubricant. Improve assembly and use.
Pearly pitting
Damage:Weak glossy dark pearly pitting on the raceway surface.
Cause:Biting of foreign matter during lubrication. Condensation due to moisture in the air. Poor lubrication.
Measures:Improve the sealing device. Filter the lubricant adequately. Use a suitable lubricant.
Wear
Damage status:The so-called wear is due to friction caused by the raceway surface or rolling surface, roller end face, shaft ring surface and the concave surface of the cage and other wear.
Causes:Foreign object intrusion, development caused by rust and galvanic corrosion. Poor lubrication. Slip due to irregular movement of the rolling body.
Measures:Improve the sealing device. Clean the JOJI bearing box. Filter the lubricant adequately. Check the lubricant and lubrication method. Prevent non-linearity.
Micro vibration wear
Damage state:Wear that occurs due to relatively repeated tiny sliding between two contact surfaces occurs on the contact portion of the raceway surface and the rolling element. It is also called micro-vibration wear corrosion because reddish-brown and black wear powder occurs.
Cause:Poor lubrication. Small amplitude rocking motion. Insufficient interference.
Measures:Use appropriate lubricant. Apply preload. Check the amount of interference. Apply lubricant to mating surfaces.
False Brinell indentation
Damage condition:During micro vibration, wear develops in the contact part of the rolling element and raceway wheel due to vibration and shaking, producing marks that are similar to Brinell's indentations.
Reason: Vibration and oscillation of JOJI bearings during transport, etc. at the time of stopping. Oscillating motion with small amplitude. Poor lubrication.
Measures: transport process bite on the shaft and JOJI bearing box to be fixed. When transporting the inner ring and outer ring to separate packaging. Add pre-pressure to reduce vibration. Use appropriate lubricants.
Creep
Damage state: the so-called creep is the JOJI bearing with the surface of the gap, in the fit between the surface of the relative occurrence of sliding, the occurrence of creep with the surface of the mirror bright or dark surface, and sometimes with the page with the card injury wear and tear generated.
Reason: insufficient interference or clearance fit. Tightening sleeve fastening is not enough.
Measures: Check the amount of interference, the implementation of measures to stop the rotation. Tighten the retaining sleeve appropriately. Study the accuracy of the shaft and JOJI bearing box. Axial preload. Tighten the raceway wheel sideways. Bond the mating surfaces. Apply a sliding agent to the mating surfaces. Slip agent.
Burns
Damage status: Raceway wheels, rolling elements and cages heat up sharply during rotation until they become discoloured, softened, melted and broken.
Cause:Poor lubrication. Excessive load (excessive preload). Excessive rotation speed. Too small a clearance. Intrusion of water and foreign matter. Poor accuracy of the shaft, JOJI bearing box, and large deflection of the shaft.
Measures:Study the lubricant and lubrication method. Correct the selection of JOJI bearing. Study fit, JOJI bearing clearance and preload. Improve the sealing device. Check the accuracy of the shaft and JOJI bearing box. Improve mounting methods.
Galvanic corrosion
Damage state: the so-called galvanic corrosion refers to the current in the cycle of the weight of the JOJI bearing raceway wheel and rolling body contact part of the flow, through the thin film of lubricant sparks, the surface of the local melt and bump phenomenon.
Cause: Ground potential difference between the outer ring and inner ring.
Measures: When setting up the circuit, the current should not flow through the JOJI bearing part. Insulate the JOJI bearing.
Rust and corrosion
Damage status: Rust and corrosion of JOJI bearings include pitted rust on the surface of the raceway wheel and rolling element, and full-scale rust and corrosion.
Cause:Intrusion of water, corrosive substances (paint, gas, etc.). Inappropriate lubricant. Attachment of water droplets due to condensation of water vapour. Stopping at high temperature and humidity. Poor rust prevention during transport. Unsuitable storage condition. Inappropriate use.
Measures:Improve the sealing device. Research on lubrication method. Rust prevention measures during stoppage. Improve storage method. Use with care.
Installation marks
Damage status: Axial linear scars on the raceway surface and rolling surface caused by use during installation and disassembly.
Cause:The inner ring and outer ring are tilted during installation and disassembly, and the shock load is applied during installation and disassembly.
Measures: Prevent shock loads by using appropriate tools and presses. Centring of each other during mounting.
Discolouration
Damage: The raceway wheel, rolling element and cage become discoloured due to temperature rise and lubricant reaction.
Cause:Poor lubrication. The reaction with the lubricant causes a hot dip in the oil. Temperature rise is large.
Measure: Improve the lubrication method.
Cause of Failure
According to the mechanism of the formation of the grinding deterioration layer on the working surface of the JOJI bearing, the main factors affecting the grinding deterioration layer are the action of the grinding heat and the grinding force. Here we will analyse the reasons about the failure of JOJI bearings.
Grinding heat
In the grinding process of JOJI bearings, the grinding wheel and workpiece contact area, consume a lot of energy, generate a lot of grinding heat, resulting in local instantaneous high temperature in the grinding area. The use of linear motion heat source heat transfer theory formula deduction, calculation or application of infrared method and thermocouple method of measurement of the experimental conditions of the instantaneous temperature, can be found in 0.1 ~ 0.001ms within the grinding zone of the instantaneous temperature can be as high as 1000 ~ 1500 ℃. Such instantaneous high temperatures, enough to make the surface of the work surface of a certain depth of the surface layer of high-temperature oxidation, amorphous organisation, high-temperature tempering, secondary quenching, and even burns cracking and other changes.
(1) surface oxidation layer
Instantaneous high temperature effect of the steel surface and the role of oxygen in the air, rise into a very thin (20 ~ 30nm) thin layer of iron oxides. It is worth noting that the thickness of the oxide layer and the total thickness of the surface grinding deterioration layer test results are in a corresponding relationship. This indicates that the thickness of the oxide layer is directly related to the grinding process and is an important symbol of grinding quality.
(2) Amorphous layer
When the instantaneous high temperature in the grinding area makes the surface of the workpiece reach the molten state, the molten metal molecular flow is uniformly coated on the working surface, and is cooled by the base metal at a very fast speed, forming a very thin layer of amorphous tissue layer. It has high hardness and toughness, but it is only about 10nm and is easily removed in precision grinding processes.
(3) High temperature tempering layer
The instantaneous high temperature in the grinding zone can make the surface within a certain depth (10 to 100nm) be heated to a temperature higher than the tempering heating of the workpiece. In the absence of austenitising temperature, with the increase in the heated temperature, the surface layer by layer will be generated with the heating temperature corresponding to the re-tempering or high temperature tempering of the organisational transition, the hardness also declined. The higher the heating temperature, the greater the decline in hardness.
(4) Two quenching layer
When the grinding zone of the instantaneous high temperature of the surface layer of the workpiece heated to the austenitising temperature (Ac1) above, the layer of austenitic organisation in the subsequent cooling process, and was re-quenched into martensitic organisation. Where there is a second quenching burns the workpiece, the second quenching layer must be extremely low hardness under the high temperature tempering layer.
(5) grinding cracks
Secondary quenching burns will make the surface layer of the workpiece stress changes. The secondary quenching area is in a state of pressure, the high temperature tempering area below the material exists Z large tensile stress, here is Z likely to crack the core of the place. Cracks Z tend to propagate along the original austenite grain boundaries. Severe burns can lead to cracks (mostly in the form of cracks) on the entire grinding surface resulting in scrapping of the workpiece.
Deterioration layer
During the grinding process, the surface layer of the workpiece will be subjected to the cutting force, compression force and friction force of the grinding wheel. Especially the role of the latter two, so that the surface layer of the workpiece to form a strong direction of plastic deformation layer and work hardening layer. These metamorphic layers will inevitably affect the surface layer residual stress changes.
(1) Cold plastic deformation layer
In the grinding process, each moment of the abrasive grain is equivalent to a cutting edge. However, in many cases, the cutting edge of the front angle is negative, in addition to the cutting role of the abrasive grain is to make the surface of the workpiece to withstand extrusion (ploughing role), leaving the surface of the workpiece obvious plastic deformation layer. The degree of deformation of this deformation layer will increase with the degree of dullness of the grinding wheel and the increase in grinding feed.
(2) thermoplastic deformation (or high temperature deformation) layer
Grinding heat in the work surface of the formation of the instantaneous temperature, so that a certain depth of the surface layer of the workpiece elastic limit of a sharp decline, and even to the extent of the disappearance of elasticity. At this time, the work surface layer in the grinding force, especially compression and friction, caused by the free stretching, by the base metal restrictions, the surface is compressed (more plough), in the surface layer caused by plastic deformation. High-temperature plastic deformation in the case of grinding process is unchanged, with the increase in surface temperature of the workpiece.
(3) Work hardening layer
Sometimes with the microhardness method and metallographic method can be found, due to processing deformation caused by the surface layer hardness increases.
Residue on the surface of the workpiece
In addition to grinding, casting and heat treatment caused by the heating of the surface decarburisation layer, and then later in the processing if not completely removed, residual on the surface of the workpiece will also cause the surface of the softening deterioration, contributing to the early failure of the bearing.