An overview,
In transmission system assembly, the difficulty in the cone bearing assembly is the entire assembly, cone bearing pre-tightening methods, magnitude of prestressing force directly affect the state of bevel gear transmission and the transmission precision of the drive train.
According to the size of Construction Of SKF 6004 Bearing http://www.fagbearings-hk.com/newproduct/SKF-6004-bearings-59114.html capacity, rotational speed and operating conditions such as setting reasonable bearing pre-tightening force, can ensure the service life of the drive train. If the pre-tightening force is too large, consumed power and even lead to bearing overheating, etc. Is too small, if the pre-tightening force under the action of load, the rolling element and generate space between the inner and outer ring, make the shaft jitter, channeling, reduce driving accuracy and noise increase, affect the gear mesh, serious when will damage the tooth and bearing.
Preloaded bearing is at room temperature, but under the working condition, the shaft system under the influence of oil temperature rise high produce trace elongation, bearing preloaded force will also change, therefore, set the pre-tightening force, this factor should be considered.
Second, the structure of cone bearing applications
Typical structure in the cone bearing application is nothing but the following three kinds of typical structure:
1. Direct preloaded bearing inner ring
Through the nut rotation axis compression bearing inner ring, eliminate internal and external ring clearance, bearing preload.
At present, the commonly used method to achieve this purpose: first, to a far greater than the ultimate preloaded bearing assembly of pretightening force, then return the nut to 1/4 circle.
This assembly method, the advantage is low cost, simple structure, practical, for roll bearing cones on the premise of good quality consistency, can be used.
The disadvantage is that: there is no quantitative data. Especially: roll cone poor consistency conditions, we find: according to the above method of preloaded bearing pre-tightening force is not stable, some small or large, resulting in the assembly quality is not stable.
2. The gasket preloaded
Eliminated by mat, bearing clearance, achieve the goal of axial preload.
At present, the commonly used method: first of all, to a far greater than the ultimate preloaded bearing assembly of pretightening force, axial size measurement, minus 0.2 mm of gasket are obtained. This method of assembly to the above advantages and disadvantages.
3. The corrugated sleeve deformation preloaded
By compressing corrugated sleeve bearing preloaded deformation to achieve.
At present, the commonly used methods: gas trigger twist the nut to a less than minimum torque, again through the torque wrench tightened after testing rotational torque and twist again, test, alternately repeatedly, until the two torque are qualified.
This assembly method, the advantage is low cost, simple structure, good for corrugated sleeve and bearing quality consistency, can be used.
The disadvantage is that: there is no quantitative data. Especially: corrugated sleeve and bearing under the condition of poor quality consistency, tight force is too large, often cause waste, resulting in product quality is unstable.
Third, digital assembly
According to the product the transmission of different structure forms, reasonable configuration solution, is the key to the transmission assembly. Once the plan is not reasonable, is just like the wrong direction, it is hard to get things done perfectly, incomplete assembly scheme will directly lead to bad product into the market, and repeat every day, this is also the many manufacturers after-sales costs rising every year.
In addition, the traditional assembly model, are all qualitative assembly, product assembly no accurate quantitative assessment, therefore, cannot track to improve product assembly quality. According to the above three kinds of structure forms, we put forward the digital assembly scheme, this scheme has been widely used in production line.
1. The preloaded bearing inner ring
For this kind of structure form, the typical applications are: steering knuckle screw machine, wheel hub nut screw down the machine.
Working principle: tighten the machine screw nut,
Nut torque sensor to track random change, synchronous detection, wheel hub bearing pre-tightening torque to the wheel hub bearing pre-tightening torque and nut tightening torque shall conform to the set value. Green window shows the qualified; Otherwise, the red window display is unqualified.
Tighten the sensor precision: plus or minus 1%
Rotation detection sensor accuracy: 0.1%
2. The gasket preloaded
For this kind of structure form, the typical applications are: transmission selected pad machine, main tooth pick pad machine, differential pad machine, etc.
Working principle: by servo motor load, preloaded bearing outer ring,
Synchronous detection bearing pre-tightening force, when bearing preloaded force after reaching set process scope, stop down, the axial locking; Adjust and test to confirm the torque, qualified, measuring the E1.
The accuracy of measurement, measuring accuracy: + / - 0.015 MM
Review accuracy: + / - 0.01 MM
3. The corrugated sleeve deformation preloaded
For this kind of structure form, the typical applications are: the main gear nut screw machine, transfer from tooth to tighten nut machine and so on.
The servo system working principle: differential tighten nut, random tracking nut torque changes, at the same time, through the sensor automatic detection, random track bearing rotational torque change; Show the actual bearing pre-tightening torque value and the nut tightening torque, and setting process parameters automatically, until the bearing rotational torque and torque nut tightening torque of the actual value to set limits, servo motor stalling, show a green light said.
When the nut screw to process the minimum torque, bearing rotational torque beyond the maximum of technological setting, namely sentences is unqualified, loosen, prompt spacer too soft and report to the police.
When the nut screw to process maximum moment, bearing rotational torque is still not process set the minimum value, namely sentences is unqualified, loosen, prompt spacer too hard and alarm.
Tighten the sensor precision: plus or minus 1%, rotation detection sensor accuracy: 0.1%
Four, cone bearing assembly
The development of the modern car manufacturing industry, more and more high to the requirement of assembly quality, not only to realize automation for assembly is more important is to realize the digitization. Product quality guarantee you will first need to have a unified assembly quality evaluation standard of quantitative, to achieve this standard, digital assembly become inevitable. At the same time, also for the product development, improvement, and assembly quality tracking provides one of the most important basis.
Our research for cone bearing assembly for many years, in view of the cone bearing different assembly structure developed a corresponding concept of digital assembly and equipment, through the application of the production line, improve the productivity, reduce the labor intensity, improve the assembly quality.