How is the contact angle of the angular contact ball bearing determined?

Jun 25, 2024

The contact angle of an angular contact ball bearing is a crucial design and operating parameter. It not only affects the bearing's load capacity, operating accuracy, and stability but also determines the distribution of the bearing's internal load and friction characteristics. When determining the contact angle of an angular contact ball bearing, we need to consider multiple aspects, including the bearing's geometry, operating conditions, and design requirements. The following is a detailed description of the contact angle determination process for angular contact ball bearings.

1. Definition of contact angle

The contact angle of an angular contact ball bearing is the angle between the line connecting the contact points of the steel ball and the raceway and the vertical axis of the bearing on the radial plane. The size of this angle directly reflects the bearing's ability to withstand axial loads. Generally, the larger the contact angle, the stronger the bearing's ability to withstand axial loads.

2. Classification of contact angles

According to the different working conditions of the bearing, the bearing contact angle can be divided into initial contact angle, installation contact angle, and working contact angle.

Initial contact angle: This refers to the contact angle of the angular contact ball bearing in a stationary state when it is not subjected to external loads. It is an inherent parameter of the angular contact ball bearing and an important indicator for bearing classification. The size of the initial contact angle is usually determined by the clearance when there is no load and the curvature of the raceway groove.

Installation contact angle: During the installation process, the clearance of the bearing will change due to the effect of the preload, resulting in a corresponding change in the contact angle. The size of the installation contact angle is related to the size of the preload and the geometric structure of the bearing.

Working contact angle: When the bearing is subjected to an external load, the contact state between the ball and the raceway will change, resulting in a corresponding change in the contact angle. The size of the working contact angle is not only related to the geometric structure of the bearing but also to the size and direction of the external load.

The above figure is a double-row angular contact ball bearing 305264D produced by FV.

3. Methods for determining the contact angle

Determining the contact angle of an angular contact ball bearing requires consideration of multiple factors, including the geometric structure of the bearing, material properties, working conditions, and design requirements. The following are some commonly used methods for determining the contact angle:

Geometric calculation method: By measuring the geometric parameters such as the inner and outer ring diameters of the bearing, the ball diameter, and the curvature of the raceway groove, the size of the initial contact angle is calculated using a mathematical formula. This method requires precise measurement and calculation, but the result is relatively accurate.

Finite element analysis method: Use finite element analysis software to model and simulate the bearing and calculate the size of the contact angle by simulating the force of the bearing under different working conditions. This method can take into account factors such as material nonlinearity and friction of the contact surface, and the result is closer to the actual situation.

Experimental measurement method: Measure the contact angle of the bearing under actual working conditions by experimental means. This method can directly reflect the performance of the bearing under real working conditions, but the experimental conditions need to be strictly controlled, and the measurement process is relatively complicated.

4. Factors affecting the contact angle

The contact angle of angular contact ball bearings is affected by multiple factors, including the geometric structure of the bearing, material properties, working conditions, and lubrication status.

The above picture is a single-row angular contact ball bearing Z-517458.01

Geometry: The geometric parameters such as the inner and outer ring diameters, ball diameters, and raceway groove curvature of the bearing directly affect the size of the contact angle.

Material properties: The material properties of the bearing, such as elastic modulus and Poisson's ratio, will also affect the size of the contact angle.

Working conditions: The size and direction of the external load, speed, temperature, and other working conditions will also affect the dimension of the contact angle.

Lubrication status: The lubrication status of the bearing also has a certain influence on the size of the contact angle. Good lubrication can reduce the friction coefficient and wear rate, thereby reducing the range of contact angle variation.

In summary, the contact angle of angular contact ball bearings is a complex and important parameter, and its determination needs to consider multiple factors. In practical applications, we need to select a suitable determination method based on specific working conditions and design requirements and comprehensively consider the influence of various influencing factors to ensure the performance and reliability of the bearing.