Method for analyzing vibration characteristics of holder

Abstract

The invention provides a cage vibration characteristic analysis method which comprises the following steps: firstly, carrying out modal analysis on a cage by adopting finite element analysis software, extracting first 20-order inherent frequencies and vibration mode diagrams, then drawing a Campbell diagram of the cage according to the vibration frequency in the ring surface of the cage, and calculating the vibration characteristic of the cage according to the Campbell diagram; and the impact frequency of the rolling body on the retainer is used as an excitation condition, so that resonance is judged not to occur under the working condition.

Description

Technical Field

[0001] The present invention relates to a bearing component analysis method, and more particularly to a cage vibration characteristic analysis method. Background Art

[0002] The cage is a very important part of the rolling bearing, which serves to separate and retain the rolling elements and guide the rolling elements to roll in the predetermined raceway of the bearing. Due to the development of new energy vehicles, drive motors are gradually replacing traditional fuel vehicle engines. They are characterized by high speed, large load, and the ability to work in an environment of frequent starting and rapid acceleration and deceleration. Therefore, high speed has become a trend in bearings. In addition, during the working process, the cage will have friction, wear and violent collision with the rolling elements, which may cause motion instability or fatigue fracture, causing early failure of the bearing. The design of rolling bearings usually adopts the fatigue life model. For high-speed bearings, the instability of its parts can cause abnormal operation and premature failure. At this time, the actual life of the bearing may be one or several orders of magnitude lower than the expected fatigue life. In this case, it is not enough to consider the fatigue life of the bearing alone, but it is also necessary to examine the dynamic performance of the bearing. This requires the analysis of the vibration characteristics of the cage to avoid resonance. Summary of the invention

[0003] In view of the deficiencies in the prior art, an object of the present invention is to provide a method for analyzing vibration characteristics of a cage, which is used to analyze the vibration characteristics of the cage and optimize the cage structure in advance to avoid resonance under external excitation conditions.

[0004] To achieve the above object, the present invention provides the following technical solution: a method for analyzing vibration characteristics of a cage, characterized in that it comprises the following steps: Step 1: Use finite element analysis software to perform modal analysis on the cage and extract the first 20 natural frequencies and vibration mode diagrams; Step 2, drawing a Campbell diagram of the cage according to the vibration frequency within the cage ring surface; Step three, using the impact frequency of the rolling element on the cage as the excitation condition to determine whether the cage will resonate under this condition, and analyzing the vibration characteristics of the cage based on whether resonance occurs.

[0005] As a further improvement of the present invention, the specific method of using finite element analysis software to perform modal analysis on the retaining frame in step one is: first, a three-dimensional digital model of the retaining frame is established in the three-dimensional digital model software and an intermediate format is generated, and then meshing is performed in the finite element analysis software, a finite element model is established, and material properties of the retaining frame are assigned, and then the modal analysis is submitted for operation.

[0006] As a further improvement of the present invention, the specific steps of drawing the Campbell diagram of the cage according to the vibration frequency in the cage ring surface in step 2 are as follows: Step 21, calculate the forward and backward wave frequencies of the cage in combination with the fixed frequency extracted in step 1, then calculate the dynamic frequency coefficient, and then obtain the vibration frequency of the cage according to each vibration form; Step 22, drawing a Campbell diagram of the cage with different rotation speeds of the cage as the horizontal coordinate and the frequency under different states as the vertical coordinate; Step 2 and 3, draw a straight line perpendicular to the horizontal axis with the actual rotation speed of the cage as the horizontal axis and different frequencies as the vertical axis to observe whether the curve has an intersection with other straight lines. If there is no intersection, it means that there will be no working point under this working condition, and vice versa.

[0007] As a further improvement of the present invention, the forward wave frequency and the backward wave frequency of the cage in step 21 are calculated by the following formula: in, is the forward wave frequency, is the frequency of the backward wave, Ω is the angular velocity of the cage rotation; m is the number of circumferential waves, The natural frequency of the rotating cage taking into account the influence of centrifugal force.

[0008] As a further improvement of the present invention, the natural frequency of the rotating cage in step 21 when considering the influence of centrifugal force is expressed by the following formula: ; in, is the natural frequency of the rotating cage when the centrifugal force is taken into account. is the natural frequency of the cage when it is not rotating, Ω is the angular velocity of the cage rotation; B is the dynamic frequency coefficient.

[0009] As a further improvement of the present invention, the dynamic frequency coefficient is calculated by the following formula: .

[0010] The beneficial effect of the present invention is that it only needs to perform modal analysis on the cage to extract the frequencies and vibration modes of each order, and then draw a Campbell diagram to identify whether the cage has the risk of resonance. This is simple and convenient, and is very practical in the early stage of cage design, which improves design efficiency and can quickly avoid risk points. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 is a list of natural frequencies; Figure 2It is the vibration diagram of the cage; Figure 3 For Campbell diagram. DETAILED DESCRIPTION

[0012] The present invention will be further described below in detail with reference to the embodiments shown in the accompanying drawings.

[0013] Reference Figures 1 to 3 As shown, a cage vibration characteristic analysis method of this embodiment includes the following steps: First, the finite element analysis software is used to perform modal analysis on the cage, and the first 20 natural frequencies and vibration mode diagrams are extracted. Then, the Campbell diagram of the cage is drawn according to the vibration frequency within the cage ring surface. The impact frequency of the rolling element on the cage is used as the excitation condition to determine whether resonance will occur under this working condition.

[0014] This embodiment further describes the above steps in detail: Furthermore, the modal analysis of the cage is performed using finite element analysis software. First, a three-dimensional digital model of the cage is established in the three-dimensional digital model software and an intermediate format is generated. Then, meshing is performed in the finite element analysis software, a finite element model is established, and material properties of the cage are assigned, and then the operation is submitted for modal analysis.

[0015] Furthermore, the extraction of the first 20 natural frequencies and mode shapes is mainly used to observe the vibration frequencies and mode shapes of the cage at various orders, especially the frequencies with circumferential wave numbers of 2, 3, and 4. Of course, the extracted natural frequencies may not be limited to the first 20 orders and may be more or less, as long as the calculation requirements are met.

[0016] Furthermore, the Campbell diagram of the cage is drawn according to the vibration frequency in the cage ring surface, and the steps are as follows: The cage is a ring-like part, and its vibration can be divided into forward waves and backward waves, which have the properties of traveling wave vibration, especially when the working state of the cage is rotation.

[0017] The analysis of the cage's natural frequency shows that under the combined effects of the rotation frequency, Coriolis force and centrifugal force, the forward wave frequency fq and the backward wave frequency fh of the cage can be expressed as: Where, Ω is the angular velocity of the cage rotation (rad / s); m is the circumferential wave number.

[0018] The natural frequency of the rotating cage considering the influence of centrifugal force is in, is the natural frequency of the cage when it is not rotating, B is the dynamic frequency coefficient, and the calculation formula is as follows: The vibration frequency of the cage under the same vibration mode can be obtained through the above formula, as shown in Table 1.

[0019] Table 1 Changes in the vibration frequency of the bearing cage under the same vibration mode

[0020] Then, the Campbell diagram of the cage is drawn with different rotation speeds of the cage as the horizontal axis and the frequency under different states as the vertical axis. Since the impact on the cage is more complicated, only the impact frequency of the rolling element on the cage is considered. Assuming that there are Z rolling elements, the exciting force frequency of the rolling element on the cage is Z times the rotation frequency, so the excitation line formula can be expressed as y=n cage / 60 Z.

[0021] Then draw a straight line perpendicular to the horizontal axis with the actual rotation speed of the cage as the horizontal axis and different frequencies as the vertical axis to observe whether the curve has an intersection with other straight lines. If there is no intersection, it means that no resonance point will appear under this working condition, and vice versa.

[0022] In summary, the cage vibration characteristic analysis method of the present embodiment only needs to perform modal analysis on the cage to extract the frequencies and vibration modes of each order, and then draw a Campbell diagram to identify whether the cage is at risk of resonance. This method is simple and convenient, and is very practical in the early stages of cage design, which improves design efficiency and can quickly avoid risk points.

[0023] The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A method for analyzing vibration characteristics of a cage, characterized in that: The steps include: Step 1: Use finite element analysis software to perform modal analysis on the cage and extract the first 20 natural frequencies and vibration mode diagrams; Step 2, drawing a Campbell diagram of the cage according to the vibration frequency within the cage ring surface; Step three, using the impact frequency of the rolling element on the cage as the excitation condition to determine whether the cage will resonate under this condition, and analyzing the vibration characteristics of the cage based on whether resonance occurs.

2. The method for analyzing cage vibration characteristics according to claim 1, characterized in that: The specific method of using finite element analysis software to perform modal analysis on the cage in step one is: first, a three-dimensional digital model of the cage is established in the three-dimensional digital model software and an intermediate format is generated, then meshing is performed in the finite element analysis software, a finite element model is established, and material properties of the cage are assigned, and then the operation is submitted for modal analysis.

3. The method for analyzing the vibration characteristics of a cage according to claim 1 or 2, characterized in that: The specific steps of drawing the Campbell diagram of the cage according to the vibration frequency in the cage ring surface in step 2 are as follows: Step 21, calculate the forward and backward wave frequencies of the cage in combination with the fixed frequency extracted in step 1, then calculate the dynamic frequency coefficient, and then obtain the vibration frequency of the cage according to each vibration form; Step 22, drawing a Campbell diagram of the cage with different rotation speeds of the cage as the horizontal coordinate and the frequency under different states as the vertical coordinate; Step 2 and 3, draw a straight line perpendicular to the horizontal axis with the actual rotation speed of the cage as the horizontal axis and different frequencies as the vertical axis to observe whether the curve has an intersection with other straight lines. If there is no intersection, it means that there will be no working point under this working condition, and vice versa.

4. The method for analyzing cage vibration characteristics according to claim 3, characterized in that: The forward and backward wave frequencies of the cage in step 21 are calculated by the following formula: in, is the forward wave frequency, is the frequency of the backward wave, Ω is the angular velocity of the cage rotation; m is the number of circumferential waves, The natural frequency of the rotating cage when the centrifugal force is taken into account.

5. The method for analyzing cage vibration characteristics according to claim 4, characterized in that: The natural frequency of the rotating cage in step 21 when considering the influence of centrifugal force is expressed by the following formula: ； in, is the natural frequency of the rotating cage when the centrifugal force is taken into account. is the natural frequency of the cage when it is not rotating, Ω is the angular velocity of the cage rotation; B is the dynamic frequency coefficient.

6. The method for analyzing cage vibration characteristics according to claim 5, characterized in that: The dynamic frequency coefficient is calculated by the following formula: 。

Images