Method for confirming hardening depth of carburized bearing steel

Abstract

The application relates to the technical field of bearing machining, in particular to a carburizing bearing steel heat treatment hardened layer depth confirmation method, which comprises the following steps: obtaining a base material yield limit; inputting load working condition information data; simulating actual working conditions to calculate the contact stress of the bearing in the actual working condition running process; converting the contact stress of each point on the bearing contact surface into an equivalent stress and drawing an equivalent stress curve; drawing a base material capacity curve; determining a base material yield critical point; determining a bearing material safety factor; drawing a material heat treatment performance curve to determine the safety range of the bearing critical point; performing hardness evaluation on the material heat treatment performance curve drawn in step S8 to further confirm the heat treatment hardened layer depth. According to the performance requirement of the material confirmed according to the actual working condition of the bearing, the material heat treatment processing is guided, the product process is optimized, the product performance is more suitable for the actual application scene, and a more accurate calculation method is provided.

Description

Technical Field

[0001] This invention relates to the field of bearing processing technology, specifically a method for confirming the depth of the hardened layer after heat treatment of carburized bearing steel. Background Technology

[0002] The carburizing heat treatment standard in the bearing processing industry specifies the minimum hardened layer depth of carburized bearing steel after carburizing heat treatment in conventional application scenarios. However, special application scenarios such as impact, vibration, and off-center load often occur in bearing applications.

[0003] When faced with special working conditions, if the carburized bearing steel is treated according to the minimum hardened layer depth after carburizing heat treatment in conventional application scenarios, it will not be able to adapt to special application scenarios such as impact, vibration, and eccentric load. Summary of the Invention

[0004] In view of the deficiencies of the prior art, the present invention provides a method for confirming the depth of the hardened layer of carburized bearing steel after heat treatment. It draws the performance limit of the base material by confirming the equivalent contact stress and the critical point of the material's yield limit under special working conditions, thereby measuring the performance gap of the original material. This gap can be resolved by carburizing heat treatment of the material.

[0005] To achieve the above objectives, the present invention provides a method for confirming the depth of the hardened layer after heat treatment of carburized bearing steel, the steps of which include: S1. Obtain the yield strength of the basic material; S2, Input load condition information data; S3. Simulate the actual working conditions based on the load condition information data, and calculate the contact stress of the bearing during operation under the actual working conditions; S4. Convert the contact stress at each point on the bearing contact surface into equivalent stress and plot it as an equivalent stress curve; S5. Based on the yield strength of the basic material described in step S1 and the contact stress described in step S3, plot the capacity curve of the basic material. S6. Determine the intersection point P0 of the equivalent stress curve and the basic material capacity curve as the critical yield point of the basic material. S7. Determine the safety factor for bearing materials; S8. Plot the heat treatment performance curve of the material, and determine the safe range of the bearing critical point according to the bearing material safety factor mentioned in step S7. S9. The hardness is evaluated by plotting the heat treatment performance curve of the material in step S8, thereby confirming the depth of the heat-treated hardened layer.

[0006] Further, step S1 includes obtaining the yield strength of the base material through material property testing.

[0007] Furthermore, step S2 includes the load condition information data, which includes one or more of the following: load information data, speed information data, lubrication information data, clearance information data, and impact information data from the bearing testing equipment.

[0008] Furthermore, steps S3 and S4 are processed using a finite element model and / or an analytical model.

[0009] Further, step S5 includes combining the contact stress in step S3 with the yield strength of the base material in step S1 through stress values ​​to obtain and plot the capacity curve of the base material.

[0010] Furthermore, the determination of the bearing material safety factor in step S7 includes calculating the bearing under impact and non-impact conditions to determine the bearing material safety factor.

[0011] Furthermore, the step S8 of plotting the material heat treatment performance curve includes determining and plotting the heat treatment performance curve based on the basic material yield critical point P0 obtained in step S6, the bearing material safety factor obtained in step S7, and the heat treatment process route.

[0012] The beneficial effects of this invention are as follows: It confirms the material performance requirements based on the actual operating conditions of the bearing, thereby guiding the material's heat treatment process, promoting the optimization of product processes, making product performance more aligned with actual application scenarios, and providing a more accurate calculation method. This method precisely improves the depth of the carburized heat-treated hardened layer of bearing steel under special heavy-load application scenarios, effectively improving the fatigue resistance of bearing materials and extending bearing service life. This method considers numerous factors within the calculation scope, including basic material properties, part contact deformation, micro-shaping of parts during machining, lubrication conditions of rolling contact, and bearing clearance, and uses finite element technology for comprehensive analysis, resulting in higher accuracy. Attached Figure Description

[0013] Figure 1 This is a schematic diagram illustrating the steps of a method for confirming the depth of the hardened layer after heat treatment of carburized bearing steel in one embodiment of the present invention. Figure 2 The equivalent stress curve, basic material capacity curve, and material heat treatment performance curve are plotted in one embodiment of the present invention. Detailed Implementation

[0014] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0015] See Figure 1 and Figure 2 This paper presents a method for confirming the depth of the hardened layer after heat treatment of carburized bearing steel, which includes: Step S1: Obtain the yield strength of the base material. The methods for obtaining the yield strength of the base material include, but are not limited to, testing through material performance experiments. It should be noted that the base material refers to the material that has not undergone quenching treatment. Typically, the mechanical properties and hardness of the base material do not meet the requirements for bearing use, therefore surface carburizing hardening treatment is necessary. Different base materials have different yield strengths, and even the yield strength of the same material varies within a certain range. Therefore, it is necessary to obtain the yield strength of the base material through material performance experiments in the laboratory. Material performance experiments can employ testing methods known in the art, or methods conventionally selected by those skilled in the art based on actual needs. Material performance testing has corresponding international, national, and industry standards.

[0016] Step S2: Input load condition information data; this data includes one or more of the following: load information data, speed information data, lubrication information data, clearance information data, and impact information data from the bearing testing equipment. Inputting this load condition information data can be done through a pop-up interactive window or by filling it in on the interactive interface. Specifically, finite element modeling and / or analysis model processing both require finite element software, and currently available finite element analysis software typically has input options, such as selection interfaces for load size, clearance (corresponding to bearing clearance), and rotational speed. Thus, this method can consider many factors such as rolling contact lubrication conditions and bearing clearance within the calculation range, making the calculation results more accurate and reliable.

[0017] It should be noted that the lubrication conditions and bearing clearance are extracted from the input conditions in step S2. Specifically, the lubrication conditions are determined by inputting the viscosity of the lubricant, calculating the effective oil film thickness using finite element analysis, and then confirming a reliable and effective lubrication state by comparing it with the surface roughness fluctuation range of the contact parts. The bearing clearance is obtained by inputting or selecting the clearance at the interface. Bearing clearance is a prerequisite for oil film formation and falls under the category of basic contact theory. Without clearance, a lubricating oil film cannot be formed between the contact parts. If the clearance is too small, the oil film will be sheared during rolling, resulting in dry friction. If the clearance is too large, it will cause significant axial movement, leading to vibration and impact forces.

[0018] Step S3: Simulate the actual operating conditions based on the load condition information data and calculate the contact stress of the bearing during operation under actual conditions. This step S3 can be performed using finite element software to simulate the actual operating conditions and conduct calculations and analyses to obtain the contact stress during bearing operation.

[0019] Step S4: Convert the contact stress at each point on the bearing contact surface into equivalent stress and plot the equivalent stress curve; see [link to relevant documentation]. Figure 2 As shown by the solid line in the middle.

[0020] The method for confirming the hardened layer depth of the carburized bearing steel heat treatment described above, through steps S3 and S4, can take into account many factors such as part contact deformation and micro-machining modifications during part processing within the calculation range, further making the calculation results more accurate and reliable. Part contact deformation is the elastic deformation caused by contact compression of parts under load; the micro-machining modifications during part processing are the micro-structural dimensions marked on the drawings during product design, whose size can be controlled through processing, and the adjustment of modification data can change the deformation and contact stress magnitude.

[0021] Step S5: Based on the yield strength of the base material in Step S1 and the contact stress in Step S3, plot the capacity curve of the base material; see [link / reference]. Figure 2 The figure shows a straight dashed line. The method for plotting the basic material capability curve includes combining the contact stress in step S3 with the material yield strength in step S1 using stress values. Specifically, this step includes: using the yield strength value obtained from laboratory testing in step S1, establishing a horizontal and vertical coordinate system, with the horizontal axis representing distance and the vertical axis representing the yield strength value; then, marking the values ​​corresponding to the calculated contact stress curve in this coordinate system sequentially, thus forming the intersecting basic material capability curve.

[0022] Step S6: Determine the intersection point P0 of the equivalent stress curve and the basic material capacity curve as the critical yield point of the basic material. (See also...) Figure 1As shown in Figure P0. It should be noted that P0 is the yield critical point of the base material, at which the base material will yield. Therefore, the carburizing process must improve the material's properties above the yield critical point P0 of the base material in order to meet the requirements.

[0023] Step S7: Determine the bearing material safety factor. This involves calculating the bearing material safety factor under both impact and non-impact conditions. Impact conditions can be monitored on various types of equipment, and the value will be several times that of the non-impact condition. The exponentially increased impact force here requires the bearing material to operate under impact conditions; therefore, the material's performance needs to be improved to meet the impact load requirements, which is the material safety factor.

[0024] Step S8, as follows Figure 2 As shown by the dashed line, the performance curve of the heat treatment is determined and plotted based on the yield critical point P0 of the base material obtained in step S6, the safety factor of the bearing material obtained in step S7, and the heat treatment process route. Specifically, the safety factor of the bearing material in step S7 is multiplied by the yield critical point P0 of the base material to determine the safe range of the bearing's critical point. The method of obtaining the performance curve of the heat treatment based on the yield critical point P0 of the base material and the safety factor of the bearing material can be achieved using conventional techniques in this field. It should be noted that, depending on the safety factor of the bearing material, the heat treatment performance curve and the yield critical point P0 of the base material will be improved to varying degrees. Figure 2 The dotted line drawn in the middle represents the improved heat treatment performance curve of the material.

[0025] Step S9: Hardness is evaluated using the material heat treatment performance curve plotted in step S8 to confirm the depth of the heat-treated hardened layer. Methods for confirming the depth of the heat-treated hardened layer include reading rules: Figure 2 The distance from the intersection point m0 ​​of the straight dashed line in the upper middle part, which is the evaluation standard "510HV", and the performance curve of the improved material, to the vertical axis is the hardened layer depth (this value is the minimum hardened layer depth).

[0026] It should be noted that, Figure 2 The curve intersecting the performance curves after heat treatment represents the hardness evaluation standard. 510 HV is the hardness evaluation standard in the diagram. The depth of the hardened layer after heat treatment is evaluated based on the hardness value. Hardness gradually decreases from the surface of the part towards the interior, and the depth at which a certain hardness value is reached represents the unhardened layer depth. In this embodiment, the depth evaluation standard is the depth when the hardness value reaches 510 HV. However, the hardness evaluation standard is not the only standard; different hardness values ​​can be considered for different application scenarios. The commonly used range is 510 HV to 550 HV.

[0027] Preferably, step S4 is performed using a finite element model and / or an analytical model.

[0028] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0029] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0030] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0031] In this invention, unless otherwise explicitly specified and limited, "above" or "below" a second feature can mean that the first and second features are in direct contact, or that they are in indirect contact through an intermediate medium. Furthermore, "above," "over," and "on top" of a second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" a second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature. It should be noted that when an element is referred to as "fixed to" or "set on" another element, it can be directly on the other element or there may be an intermediate element present. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be an intermediate element present. The terms "vertical," "horizontal," "above," "below," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible embodiments.

Claims

1. A method for confirming the depth of the hardened layer after heat treatment of carburized bearing steel, characterized in that: Including steps S1. Obtain the yield strength of the basic material; S2, Input load condition information data; S3. Simulate the actual working conditions based on the load condition information data, and calculate the contact stress of the bearing during operation under the actual working conditions; S4. Convert the contact stress at each point on the bearing contact surface into equivalent stress and plot it as an equivalent stress curve; S5. Based on the yield strength of the base material in step S1 and the contact stress in step S3, plot the capacity curve of the base material. Step S5 includes combining the contact stress in step S3 and the yield strength of the base material in step S1 through stress values ​​to obtain and plot the capacity curve of the base material. S6. Determine the intersection point of the equivalent stress curve and the basic material capacity curve as the basic material yield critical point P0. S7. Determine the safety factor for bearing materials; S8. Plot the material heat treatment performance curve, and determine the safe range of the bearing critical point according to the bearing material safety factor in step S7. The plotting of the material heat treatment performance curve in step S8 includes determining and plotting the heat treatment performance curve according to the basic material yield critical point P0 obtained in step S6, the bearing material safety factor obtained in step S7, and the heat treatment process route. S9. Hardness evaluation is performed on the heat treatment performance curve of the material plotted in step S8 to confirm the depth of the heat-treated hardened layer.

2. The method for confirming the depth of the hardened layer after heat treatment of carburized bearing steel according to claim 1, characterized in that: Step S1 includes obtaining the yield strength of the basic material through material property testing.

3. The method for confirming the depth of the hardened layer after heat treatment of carburized bearing steel according to claim 1, characterized in that: The load condition information data mentioned in step S2 includes one or more of the following: load information data, speed information data, lubrication information data, clearance information data, and impact information data of the actual application equipment of the bearing.

4. The method for confirming the depth of the hardened layer after heat treatment of carburized bearing steel according to claim 1, characterized in that: Steps S3 and S4 are processed using finite element models and / or analytical models.

5. The method for confirming the depth of the hardened layer after heat treatment of carburized bearing steel according to claim 1, characterized in that: The determination of the bearing material safety factor in step S7 includes calculating the bearing under impact and non-impact conditions to determine the bearing material safety factor.

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