As a veteran product design company, IDC is increasing its design and development work in the field of robotics, and one of the key engineering elements in these projects is bearings.
In this article, we share with you the importance of its bearing system, examine the relevant design considerations, and provide in-depth insights into achieving optimal performance.
Bearings are critical components in a motion assembly, allowing two loaded surfaces to move relative to each other. We can find bearings in almost any product with moving components.
The motion of the bearing can be rotary or linear and can be achieved by rolling elements, sliding contacts, or fluid films.
A well-designed bearing system can meet service life, efficiency, load and speed requirements, while a system can lead to a series of problems that are difficult to solve. For example, free play beyond the required range of motion, premature damage to the system, and excessive noise. These phenomena can lead to a number of potential problems that ultimately affect the success of the product.
In order for the rolling element bearing to reach its rated load and speed, it must be installed correctly.
For example, if the bore size to accommodate the bearing is too small and the pressure fit is too tight, the bearing will feel obstructed when the inner ring is rotated by hand and its life may be significantly shortened. Similarly, if a bearing is pressed against an oversized shaft, the deformation and stresses of the bearing can alter the internal clearance, leading to poor performance and premature failure.
When using plain bearings (bushings), it should be noted that the shaft rotating in the bushing is actually the inner ring, so it should not only be within a specific tolerance, but it must also have a sufficiently fine surface finish (usually less than ra 0.).3) and appropriate hardness.
In the case of multiple bearings supporting a shaft, there must be appropriate tolerances for the concentricity, cylindricity and alignment of the housing and shaft. Poor tolerance control can lead to difficult assembly, uneven load distribution within the bearing, excessive noise and premature failure of rolling element bearings, and frequent jamming of polymer bushings.
Bearings come in a wide range of sizes, from bronze bushings to rolling element bearings optimized to support stresses in specific directions. The bearing selection process is closely related to the design of the wider system, which involves an understanding of the magnitude and direction of the force.
For rotating shafts without axial forces, the range of bearings is relatively narrow, i.e. between ball bearings and sliding bushings. In the presence of significant moment loads, radial and axial forces, the range of suitable bearing options increases significantly.
In more complex cases, the impact of certain bearing combinations on system function or performance is more important.
Complex bearing systems may include shafts, gears, and motors at the same time, and they should be sufficiently constrained to ensure that they only move in the desired manner.
When a large number of fixed bearings are present in the system, there is a danger that the individual bearings will be overloaded, causing a bearing to be subjected to a higher than expected load, or that it will be pressured during assembly. For example, misalignment of the motor and shaft can cause the internal bearings of the motor to be subjected to unusually high loads.
In some cases, this can be avoided by using a flexible coupling between the motor, gearbox and shaft, while in others tighter tolerance control is required and fixed and floating bearings are used to accommodate this misalignment.
The service life and cycle of the bearing can be estimated by calculation. ISO281 specifies a basic life rating associated with 90% reliability.
For more complex bearing arrangements or for greater certainty of bearing life in critical applications, there are many more advanced techniques available for estimating bearing life.
In general, the complexity of an actual engineered system will be higher than the simple cases covered by the basic life rating, which means that the assumptions in these calculations are not representative of the actual system.
In the actual case, due consideration needs to be given to the "adjusted rated life", which includes variables such as adjusting lubrication conditions, lubrication contamination, belt drive systems, fatigue loads, and load conditions and speed variations.
Alternatively, bearing life can be calculated according to ISO16281. The standard takes into account the load distribution within the bearing and therefore the effects of bearing clearance, inclination angle or centrifugal force.
A well-designed bearing system can be customized according to the needs of the product as follows:
Runs silently. Highest precision.
Extend the life of products that cannot be serviced regularly.
Reduces vibration. Eliminate the disturbance of the motor system and the risk of locking.
Functionality in harsh environments.
Easy to assemble. Security.
Reduce friction and increase efficiency.
High speed. Low cost.
Applicability. The product is too loud? We will make the noise motion system silent with the right bearing selection and proper part tolerances.
Need reliable performance with minimal maintenance? We have designed, tested and validated bearing systems that operate continuously for more than 5 years without maintenance under different conditions.
Accuracy and backlash issues? We have designed joints that use rolling element bearings to support significant moment loads without free clearance, improving the precision and precision of the joints, eliminating noise and increasing life.
If you want to know more about the design elements of mechanical structure and noise reduction in other product designs, you can continue to read our following articles: Several Suggestions for Product Design and Noise ReductionAppearance Design in Product Design (3) - Relationship with Mechanical Structure.
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