Anhui IFAG Hardware Accessories Technology Co., Ltd.
The manufacturing process of the coiled product determines the existence of the open seam, so that the product does not have a good roundness in the free state, and the outer diameter of the sleeve and the seat hole are interference fit, so it cannot be directly in the free state. Measure the inner and outer diameters of the product and use special measuring instruments and equipment to detect; including:
• Inspection method A: Haf gauge inspection outer diameter;
• Inspection method B: check the outer diameter of the gauge;
• Inspection method C: check the inner diameter of the gauge;
• Inspection method D: The measuring ruler measures the outer diameter of the large-size product and the wall thickness inspection method of the alternative inspection method C. The wall thickness inspection method and the inspection method C cannot be used at the same time.
Outer diameter inspection method
Safety Inspection Method A (ISO3547-2: Test A)
The outer diameter is inspected using the upper and lower half gauges as shown in the right view. The inspection opening is applied with the inspection load Fch facing the upper haf gauge, which enables the rolled sleeve to be located in the inspection mode in a satisfactory manner. In the test, the outer diameter of the rolled sleeve is reduced due to the elastic deformation, but no permanent deformation occurs. The outer diameter of the product can be calculated by examining the amount of change Δz of the distance z between the dies.
Inspection Method B (ISO3547-2: Test B)
The inspection adopts two ring gauges, namely the general rules and the stop gauges. The force can be pushed into the through-hand by the force of 250N and pass through the general rules; under the same circumstances, it is impossible to enter and pass the stop gauge. In some cases, the accuracy of the test may be affected. For example, if the bushing is not round or the force of closing the open seam itself exceeds 250N, it is recommended to use the test method A or the test method combining the pressure input force and the wall thickness.
Inspection Method D (ISO3547-2: TestＤ)
The measuring rod is used to measure the outer diameter, and is generally detected for the outer diameter of the large-sized bushing.
Inner diameter inspection method
Safety Inspection Method C (ISO3547-2: Test C)
After the bushing is pressed into the reference ring gauge, the inner diameter of the bushing is checked. The inner diameter can be detected by a three-point measuring device or a through-and-stop gauge. It is generally recommended to use the pass and stop plug gauges for practical use. At this time, when the hand thrust does not exceed 250N, the plug gauge can pass through the bore of the bushing. In the same situation, the plug gauge should not pass through the bore of the bushing. . When the bushing is pressed into the reference ring gauge, the outer diameter of the bushing may be deformed and cannot be used normally.
In addition to thickness tolerances, the parallelism of the gasket is equally important to the gasket and the life of the workpiece. We use a more effective test method to detect the parallelism of the gasket, allowing the gasket to pass through two parallel blocks by its own weight; of course, the parallel block must be larger than the specifications of the gasket itself.
Wall thickness detection method
As an alternative to the detection method C, two cannot be used at the same time, and the wall thickness is measured in the axial direction according to the size of the sleeve.
Straight sleeve installation
Flange sleeve installation
Pressing force calculation
For some special applications, such as the application of the IFAG 650# bushing on the injection molding machine, the method of press-fitting can be adopted, which is the press-fit method when the seat hole and the bushing are in an interference fit. The liquid nitrogen should be completely covered and cooled for at least two hours during the press-fitting, and the sleeve should be pressed immediately after removing the liquid nitrogen. There is no need to apply force during the press-fit process, and the self-weight of the sleeve itself can meet the smooth realization of the assembly.
At the initial operation, the contact surface between the bearing and the dual shaft is smooth enough, but after a period of operation, the contact surface will inevitably produce a slight irregular shape, and the shaft and the sleeve are not possible. Fully reach the theoretical concentric coaxial, the contact surface may form incomplete contact, so it is not recommended to load and run when starting operation, resulting in damage to the bearing surface and shortening the service life of the bearing. Therefore, in the initial operation phase, it should be started gradually and slowly accelerated. First, the fine irregular shape of the surface is gradually smoothed, so that the contact surface is worn in, and the damage to the contact surface of the bearing and the shaft is alleviated.
Storage
The bearing packaging provided by Iver Aiji is divided into bulk into cartons and plastic bags into cartons. Bearings should be stored in a clean, moisture-proof place. Thin-walled bearings such as EPB should be protected from deformation during storage. Never store the product in high temperature, humidity, or sunlight. Stacking should be avoided too high and too heavy during storage.
Gasket and skateboard installation
It is recommended that the gasket and the slide plate be installed in the recessed seat hole. In order to avoid movement, it is recommended to fix it with a locating pin.
1, the use of positioning pins on the gasket
2, the use of positioning pins on the skateboard
3, the use of flat head screws
When the locating pin cannot be used, it can be fixed by laser welding, adhesive and brazing (temperature <320 degrees Celsius). At this time, note that the temperature used should not exceed the temperature range that the bearing material itself can withstand, and the working face of the sleeve prevents contact with the adhesive.
When the lubricating film is present on two relatively moving surfaces, the friction conditions of the two contact faces can be divided into the following three steps:
The thickness of the lubricating film between the two contact faces is sufficient and the two contact faces are completely separated by the viscous oil film. At this time, the friction of the two contact faces is determined by the viscous resistance of the lubricant, which can be a very small value (friction factor can be 0.0001 -0.01). In this case, when the shaft rotates, the surrounding oil also rotates due to the viscosity of the lubricating oil and the oil pressure generated in the load region. This phenomenon is called the wedge effect. The change in the oil pressure P generated in the lubricating oil film is affected by the temperature and viscosity of the lubricating oil, the surface roughness of the shaft, the fitting clearance, and the rotational speed of the shaft.
Boundary lubrication
The lubricating oil film between the two contact faces is very thin, and there is no viscous hydrodynamic oil film. Only the film of the adsorbing oil molecules exists between the two contact faces. The oil molecules on the solid surface have shear properties. Far greater than the fluid film, it has a greater friction than fluid lubrication. At the frictional contact point, the oil film often breaks. This is called "boundary lubrication". Under these conditions, it is necessary to reduce the choice of friction and self-lubricating bearings.
Solid lubrication (dry friction)
Under this working condition, the two solid surfaces are in direct contact with each other without a lubricating film such as a fluid lubricating film or an adsorbing oil film. The friction is only proportional to the vertical load on the solid contact surface, the friction factor is independent of the sliding speed, and the static friction is greater than the dynamic friction. Therefore, the choice of self-lubricating bearing materials is critical.
Factors affecting service life
PV refers to the sum of the products of the bearing under certain bearing and line speed conditions. The PV value is inversely proportional to the service life of the bearing; therefore, it is recommended to use a relatively low safety PV value to ensure that the bearing will be longer. The service life; although the PV values of the various materials are specified in the sample, but these are measured under radial rotation conditions, in fact, designers need to consider many factors when designing bearing life. In addition, the parameters to be considered for the ambient temperature change due to the increase in temperature, and the matching tolerance between the bearing and the seat hole also changes.
Operation mode and calculation of PV value
The oscillating motion is considered to be one of the harsh conditions in which the speed of the bearing accelerates from zero in each cycle. The oil film is easily destroyed, the fatigue wear of the material is accelerated, and the wear particles are repeatedly rolled and extended. Ball bearings, which are mainly used for rotary motion, have a very small contact area, resulting in very high stress in the contact area, so they are not suitable for rocking motion, and the sliding bearing has a much larger contact area than the ball bearing and is generally considered to be able to accommodate this. Application conditions. IFAG self-lubricating bearing surface has good wear resistance, and the friction coefficient is greatly reduced by material modification. The solid transfer film formed on the surface can show its excellent self even when the oil is broken or the oil film is broken. Lubrication performance.
The service life of the bearing is affected by the ambient temperature and the heat generated by the friction caused by the oscillating and reciprocating motion. For high temperature applications, the PV value of the bearing should be limited to a small value. The heat resistance of plastic bearings is generally lower than that of metal bearings, especially thermoplastic resins are less resistant to heat, and their thermal expansion rates are relatively high. Therefore, in order to maintain the clearance required for operation, it is very important to specify the size control of the bearings made of these materials.
Bearing operation may be continuous or intermittent, and intermittent motion is advantageous for general types of bearings because intermittent operation allows the frictional heat to be cooled, so the PV value can be kept relatively high. The disadvantage of intermittent operation is that frequent interruptions in operation can result in insufficient formation of the transfer film, and an increase in wear is caused by restarting. In addition, the load applied by intermittent operation is liable to cause boundary lubrication conditions. In this case, choose a product with a higher safety factor.
Anhui IFAG Hardware Accessories Technology Co., Ltd. provides you with: oilless bearings, sliding bearing, self-lubricating bearings, composite bearings;
Graphite Bushings
Graphite Bronze Bushing
Ball Bearing Retainer Cage
Oilless Bearing
Self Lubricating Bearing
Sintered Bronze Bearing
Composite Bushing
Sliding Bush
Steel Bushing Sleeve
Copper Bushings
Steel Spacers Bushings
Graphite Slide Plates
Custom Steel Bushings
