Bearing ring heat treatment quality evaluation method and system

Abstract

The invention belongs to the technical field of heat treatment, and provides a bearing ring heat treatment quality evaluation method and system, according to relevant parameters of bearing ring heat treatment and a preset in-furnace temperature prediction model, an in-furnace temperature prediction value is obtained, and according to the in-furnace temperature prediction value, bearing ring heat treatment quality evaluation is carried out. Wherein the in-furnace temperature prediction model is a three-item mathematical model, and each monomial comprises a denominator item and a numerator item; the denominator item in each monomial is a squared value of a difference between the current station of the material frame and a preset constant; a molecular item in each monomial comprises a product of a corresponding fitting coefficient, a corresponding temperature zone actual temperature expression and an accumulated furnace entering time expression; by means of the mathematical model, the real in-furnace temperature of each frame of bearing ring can be predicted, and the method is more accurate and visual compared with pure checking of real-time parameters of heat treatment equipment.

Description

Technical Field

[0001] The invention belongs to the field of heat treatment technology, and in particular relates to a method and system for evaluating the heat treatment quality of a bearing ring. Background Art

[0002] Thermal stress and phase change stress during heat treatment of bearing rings are the dominant factors that determine the quality of heat treatment. Thermal stress and phase change stress are closely related to the heating temperature and holding time of the workpiece.

[0003] In actual production, workshops usually explore appropriate process parameters based on the thickness and size of the rings to be processed. Thicker rings have higher heating temperatures and longer insulation times; thinner rings have lower heating temperatures and shorter insulation times. This method of controlling heat treatment quality based on experience lacks a scientific theoretical basis. Based on this, the traditional method of evaluating heat treatment quality by checking the real-time parameters of the heat treatment equipment is inaccurate and not intuitive. In addition, when continuously producing rings of different models, in order to improve efficiency, the workshop usually does not wait for the previous model to be completely out of the furnace before letting the next model into the furnace. In this case, the impact of changing process parameters on heat treatment quality cannot be accurately evaluated. Summary of the invention

[0004] In order to solve the above problems, the present invention proposes a method and system for evaluating the quality of heat treatment of bearing rings. The present invention obtains an in-furnace temperature prediction value based on relevant parameters of the heat treatment of the bearing rings and a preset in-furnace temperature prediction model, and performs heat treatment quality evaluation of the bearing rings according to the in-furnace temperature prediction value. The mathematical model can be used to predict the actual in-furnace temperature of each frame of the bearing rings, which is more accurate and intuitive than simply checking the real-time parameters of the heat treatment equipment.

[0005] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0006] In a first aspect, the present invention provides a method for evaluating the heat treatment quality of a bearing ring, comprising:

[0007] Obtain relevant parameters of heat treatment of bearing rings;

[0008] According to the relevant parameters and the preset in-furnace temperature prediction model, a predicted value of the in-furnace temperature is obtained;

[0009] According to the predicted value of furnace temperature, the heat treatment quality of bearing rings is evaluated;

[0010] Among them, the furnace temperature prediction model is a trinomial mathematical model, each monomial includes a denominator and a numerator; the denominator in each monomial is the square value of the difference between the current workstation of the material frame and the preset constant; the numerator in each monomial includes the product of the corresponding fitting coefficient, the actual temperature expression of the corresponding temperature zone, and the cumulative furnace entry time expression.

[0011] Furthermore, the related parameters include the temperature in each temperature zone, the cumulative furnace entry time and the position of the material frame.

[0012] Furthermore, for a continuous heat treatment furnace, the furnace temperature prediction model is:

[0013]

[0014] Among them, T 代表 is the furnace temperature, a n is the fitting coefficient; T n is the actual temperature of temperature zone n; Time is the accumulated time of entering the furnace; Pos is the current position of the material frame; c n is a constant.

[0015] Furthermore, for a walking beam heat treatment furnace, the furnace temperature prediction model is:

[0016]

[0017] Furthermore, the in-furnace temperature prediction model is used to predict the in-furnace temperature curve according to the real-time parameters experienced by the ferrule during the heat treatment.

[0018] Furthermore, according to the furnace temperature curve, the area enclosed by the furnace temperature curve and the coordinate axis is obtained. The larger the enclosed area, the greater the thermal stress and phase change stress, and the smaller the enclosed area, the smaller the thermal stress and phase change stress.

[0019] In a second aspect, the present invention further provides a bearing ring heat treatment quality assessment system, comprising:

[0020] The data acquisition module is configured to: obtain relevant parameters of heat treatment of the bearing ring;

[0021] The prediction module is configured to: obtain a predicted value of the in-furnace temperature according to the relevant parameters and a preset in-furnace temperature prediction model;

[0022] The evaluation module is configured to: evaluate the heat treatment quality of the bearing ring according to the predicted value of the furnace temperature;

[0023] Among them, the furnace temperature prediction model is a trinomial mathematical model, each monomial includes a denominator and a numerator; the denominator in each monomial is the square value of the difference between the current workstation of the material frame and the preset constant; the numerator in each monomial includes the product of the corresponding fitting coefficient, the actual temperature expression of the corresponding temperature zone, and the cumulative furnace entry time expression.

[0024] In a third aspect, the present invention further provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the method for evaluating the heat treatment quality of a bearing ring described in the first aspect.

[0025] In a fourth aspect, the present invention further provides an electronic device comprising a memory, a processor, and a computer program stored in the memory and capable of running on the processor, wherein when the processor executes the program, the steps of the bearing ring heat treatment quality assessment method described in the first aspect are implemented.

[0026] In a fifth aspect, the present invention further provides a computer program product, which includes a computer program. When the computer program is executed by a processor, the steps of the method for evaluating the heat treatment quality of a bearing ring described in the first aspect are implemented.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1. The present invention obtains an in-furnace temperature prediction value based on relevant parameters of the bearing ring heat treatment and a preset in-furnace temperature prediction model, and performs a bearing ring heat treatment quality assessment based on the in-furnace temperature prediction value; wherein the in-furnace temperature prediction model is a three-term mathematical model, and each monomial includes a denominator and a numerator; the denominator in each monomial is the square value of the difference between the current workstation of the material frame and a preset constant; the numerator in each monomial includes the product of the corresponding fitting coefficient, the actual temperature expression of the corresponding temperature zone, and the accumulated furnace entry time expression; the mathematical model can be used to predict the actual in-furnace temperature of each frame of the bearing ring, which is more accurate and intuitive than simply checking the real-time parameters of the heat treatment equipment.

[0029] 2. The present invention can reflect the influence of heating temperature and holding time on heat treatment quality through the integral value of the furnace temperature curve (i.e. the area enclosed by the coordinate axis) on the basis of the furnace temperature prediction value obtained by the furnace temperature prediction model. When different types of rings are continuously produced, the influence of changing parameters on heat treatment quality can be evaluated by comparing the integral values. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The drawings in the specification that constitute a part of this embodiment are used to provide a further understanding of this embodiment. The schematic embodiments of this embodiment and their descriptions are used to explain this embodiment and do not constitute improper limitations on this embodiment.

[0031] Figure 1 This is a schematic diagram of a heat treatment production line according to Example 2 of the present invention;

[0032] Figure 2 This is the furnace temperature test scheme of Example 2 of the present invention;

[0033] Figure 3 This is a comparison chart of the fitting effects of the mathematical model of the heating main furnace fitting curve of Example 2 of the present invention.

[0034] Figure 4 This is a comparison chart of the fitting effects of the mathematical model of the upper fitting curve of the tempering furnace in Example 2 of the present invention. DETAILED DESCRIPTION

[0035] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0036] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0037] The roller bottom heating furnace used for heat treatment of bearing rings is a heat treatment equipment widely used in quenching and tempering. The heated material is heated on both sides, and the heating is fast and uniform. Most of the current heating furnaces have been automated and can record the position parameter data of the workpiece inside and the real-time process parameter data of the equipment, but it is impossible to know the actual temperature changes experienced by the workpiece in the furnace.

[0038] Embodiment 1:

[0039] As described in the background technology, the traditional method of evaluating the heat treatment quality by checking the real-time parameters of the heat treatment equipment is inaccurate and not intuitive. In addition, when continuously producing different types of rings, in order to improve efficiency, the workshop usually does not wait for the previous model to be completely out of the furnace before letting the next model into the furnace. In this case, the impact of changing the process parameters on the heat treatment quality cannot be accurately evaluated.

[0040] In order to solve at least one of the above problems, this embodiment provides a method for evaluating the heat treatment quality of a bearing ring, using the actual in-furnace temperature data measured by a furnace temperature tracker, combined with the position and process parameter data derived from the heat treatment equipment to establish a furnace temperature prediction model, and using the established in-furnace temperature prediction model to predict the actual in-furnace temperature curve of the workpiece according to the heat treatment equipment parameter data, for evaluating the heat treatment quality of the workpiece. In order to implement the heat treatment quality evaluation method of a bearing ring in the present invention, this embodiment also provides a furnace temperature testing method using a furnace temperature tracker (black box) and a thermocouple, a mathematical model for predicting the actual in-furnace temperature according to the position and process parameter data of the heat treatment equipment, and a method for evaluating the influence of heating temperature and holding time on heat treatment quality, specifically:

[0041] This embodiment provides a method for testing the temperature in a furnace using a furnace temperature tracker (black box) and a thermocouple, comprising:

[0042] S101. Use thermocouples to detect temperature. One side of the thermocouple is a temperature sensing probe, which is fixed in the material frame. The other side is inserted into the temperature measurement channel of the furnace temperature tracker. After taking heat insulation measures, it is put into the furnace together with the material frame. The furnace temperature tracker will record the temperature of the thermocouples on each channel at regular intervals. After leaving the furnace, the records can be exported to obtain the real temperature data in the furnace.

[0043] S102, analyzing the data of each point of the actual in-furnace temperature data, and finding a suitable representative point to represent the actual in-furnace temperature data of the entire material frame.

[0044] S103, exporting position parameter data corresponding to the data recorded by the furnace temperature tracker and process parameter data from the heat treatment equipment to prepare for the mathematical modeling process.

[0045] This embodiment also provides a mathematical model for predicting the actual in-furnace temperature according to the location of the heat treatment equipment and the process parameter data, and obtains the in-furnace temperature prediction model, including:

[0046] S201. For a continuous heat treatment furnace, the bearing ring moves slowly in the furnace, and its mathematical model is as follows:

[0047]

[0048] Among them, a n is the coefficient to be fitted; T n is the actual temperature of temperature zone n; Time is the cumulative time of entering the furnace from the beginning; Pos is the current position of the material frame; c n is a constant.

[0049] The mathematical model is mainly composed of three parts, and the denominator of each part can ensure that the specific workstation is affected by the actual temperature of the specific temperature zone. The structure can make the workstation only be affected by T when it is near c. n When the workstation is far away from c, the denominator will increase rapidly, T n The impact will become weaker and weaker, which is in line with the actual production scenario: a specific workstation in the furnace is affected by the actual temperature of a specific temperature zone.

[0050] The first part represents the rapid linear increase of temperature when entering the furnace. 1 is the coefficient of the item to be fitted, except for the one affected by T 1 In addition to the influence of the temperature when entering the furnace, the temperature rise is also related to the furnace entry time Time, but as the material frame moves forward, after the temperature rises to a certain extent, Time will hardly play a role. In order to ensure that Time only plays a role at the beginning, the present invention performs a logarithmic transformation on Time in the numerator of the first part, because the logarithmic function grows faster when the independent variable is small, and gradually flattens when the independent variable is large.

[0051] The second part represents the process of rapid heating followed by slow heating. 2 and a 3 is the coefficient to be fitted. Since the curve of this process is convex, To increase nonlinearity, the square root function itself is also a convex function. The purpose of taking the logarithm of Time is the same as that of taking the logarithm of Time, which is to ensure that Time will only take effect at the beginning, and the square root function is greater than the logarithmic function. Using the square root function can make the second part of T at a specific station 代表 The effect of is greater than using a logarithmic function.

[0052] The third part represents the process of temperature tending to level off after the temperature rises to a certain level, which corresponds to the heat preservation process during the heat treatment process. Affected by the actual temperature of different temperature zones, the temperature may fluctuate slightly, but it tends to be stable overall. i+1 is the coefficient to be fitted.

[0053] S202. For a step-beam heat treatment furnace, the bearing ring moves one station at a certain interval, so the mathematical model is simpler than that of a continuous heat treatment furnace. The mathematical model is as follows:

[0054]

[0055] The first and second parts belong to the linear heating process. The quadratic term in the second part can increase the nonlinearity of the heating stage. The third part is the same as the continuous heat treatment furnace and represents the insulation process.

[0056] This embodiment also provides a method for evaluating the influence of heating temperature and holding time on heat treatment quality, including:

[0057] S301, use the representative data of the furnace temperature tracker recorded data and the corresponding heat treatment equipment position and process parameter data to fit the above mathematical model, and use Matlab to determine the value of the coefficient to be fitted. In this embodiment, Matlab can be used to determine the value of the coefficient to be fitted. Of course, in other embodiments, other tools can be selected according to the situation to determine the value of the coefficient to be fitted, such as Excel and Python (NumPy, SciPy), etc.

[0058] S302. The real temperature curve in the furnace can be predicted based on the real-time parameter data of each frame ring in the heat treatment equipment through the fitted mathematical model. The area enclosed by the curve and the coordinate axis can express the influence of thermal stress and phase change stress associated with heating temperature and holding time: the higher the temperature, the longer the holding time, the larger the enclosed area, and the greater the thermal stress and phase change stress; the lower the temperature, the shorter the holding time, the smaller the enclosed area, and the smaller the thermal stress and phase change stress. In this way, the influence of heating temperature and holding time on the heat treatment quality is evaluated. It can be understood that when the enclosed area is within the preset range during the assessment, it means that the quality assessment result meets the standard; when the enclosed area exceeds the preset range, it means that the quality assessment result does not meet the standard. For example, the enclosed area is less than the minimum value of the preset range, and the enclosed area is too small, indicating that the heating temperature and the holding time are not enough, which will cause the ring to not be hardened through the quenching process, the core structure has not changed, and the ring structure does not meet the standard; during the tempering process, it will cause insufficient stress elimination in the ring, and the hardness, brittleness and other properties will decrease; the enclosed area is greater than the maximum value of the preset range, and the enclosed area is too large, indicating that the heating temperature and the holding time are excessive, which will cause over-quenching during the quenching process, the austenite grains are too large, and the organizational properties are reduced; during the tempering process, it will cause an increase in carbides and a decrease in hardness.

[0059] The present invention combines the data measured by the furnace temperature tracker and the data derived from the heat treatment equipment for mathematical modeling. The mathematical model can predict the actual furnace temperature curve of each frame bearing ring, which is more accurate and intuitive than simply checking the real-time parameters of the heat treatment equipment.

[0060] Through the present invention, the integral value of the furnace temperature curve (i.e., the area enclosed by the coordinate axis) can reflect the influence of the heating temperature and the holding time on the heat treatment quality. When different types of rings are continuously produced, the influence of changing the parameters on the heat treatment quality can be evaluated by comparing the integral values.

[0061] Embodiment 2:

[0062] In order to illustrate and supplement Example 1, this example provides a method for evaluating the heat treatment quality of a bearing ring. Figure 1 As shown, the workshop heat treatment production line of this embodiment includes a continuous heating main furnace and a step-type three-layer tempering furnace. The entire production line can be controlled by a PLC or other controller, and its upper computer can export the position parameter changes experienced by a frame of bearing rings with a certain number and the corresponding heat treatment equipment process parameter data.

[0063] The furnace temperature tracker and thermocouple related instruments can be realized by conventional equipment, and the test scheme is as follows Figure 2 As shown, this embodiment carried out three test experiments on the main heating furnace and the upper layer of the three-layer tempering furnace of the heat treatment production line for subsequent mathematical modeling.

[0064] There are many test points each time, and it is necessary to find representative points to characterize the overall in-furnace temperature curve of the material frame. In this embodiment, the average value T of the temperature of each point is selected. Mean As a representative point, this is because the integral of the curve of each point in each test experiment is consistent with T Mean The curve integral ratios of all fall within [0.97, 1.03], with little difference. The original intention of the design of the heat treatment equipment is to heat the materials evenly, so T is selected. Mean It is suitable as a representative point, and the specific numerical calculation will not be elaborated here.

[0065] The real-time parameter data of the heating main furnace exported by the host computer has 7 columns, namely, time stamp (Time), position (Pos), actual temperature of heating zone I (T 1 ), actual temperature of heating zone II (T 2 ), actual temperature of heating zone III (T 3 ), actual temperature of heating zone IV (T 4 ) and the actual temperature of heating zone V (T 5 ). Before mathematical modeling, this embodiment transforms Time, and the first Time of each set of data is replaced by 1, the next one is 2, and so on. The mean value of the heating main furnace point T Mean The mathematical model is as follows:

[0066] T Mean =F 1 +F 2 +F 3 ;

[0067]

[0068] Table 1 Average value T of main heating furnace point Mean The value of the coefficient to be fitted in the mathematical model

[0069]

[0070] The upper layer real-time parameter data of the tempering furnace exported by the host computer has 6 columns, namely time stamp (Time), position (Pos), actual temperature of heating zone I (T 1 ), actual temperature of heating zone II (T 2 ), actual temperature of heating zone III (T 3 ) and the actual temperature of heating zone IV (T 4 ). Time is numerically processed as in the main heating furnace, and the average value of the tempering furnace point is T Mean The mathematical model is as follows:

[0071] T Mean =F 1 +F 2 ;

[0072]

[0073] Table 2 Tempering furnace point average T Mean The value of the coefficient to be fitted in the mathematical model

[0074]

[0075] The fitting process of the main heating furnace and the upper layer of the tempering furnace uses 2 of the 3 test experiments respectively, and the other one is used to verify the fitting effect of the mathematical model. The real-time parameter data of the heat treatment equipment of the verification data is input into the fitted mathematical model, and the model will output the predicted value of its actual in-furnace temperature. The comparison between the predicted value and the actual in-furnace temperature value of the verification data is shown in the figure. Figure 3 and Figure 4 By comparing the predicted value and the true value, it can be seen that the model prediction effect is good. This embodiment is only used as an example, so the middle and lower layers of the tempering furnace are not mathematically modeled.

[0076] By integrating the actual in-furnace temperature curve predicted by the mathematical model, the value of the area enclosed by the curve and the coordinate axis can be obtained, which can be used to evaluate the influence of heating temperature and holding time on the quality of heat treatment.

[0077] Embodiment 3:

[0078] This embodiment provides a method for evaluating the heat treatment quality of a bearing ring, comprising:

[0079] The data acquisition module is configured to: obtain relevant parameters of heat treatment of the bearing ring;

[0080] The prediction module is configured to: obtain a predicted value of the in-furnace temperature according to the relevant parameters and a preset in-furnace temperature prediction model;

[0081] The evaluation module is configured to: evaluate the heat treatment quality of the bearing ring according to the predicted value of the furnace temperature;

[0082] Among them, the furnace temperature prediction model is a trinomial mathematical model, each monomial includes a denominator and a numerator; the denominator in each monomial is the square value of the difference between the current workstation of the material frame and the preset constant; the numerator in each monomial includes the product of the corresponding fitting coefficient, the actual temperature expression of the corresponding temperature zone, and the cumulative furnace entry time expression.

[0083] The working method of the system is the same as the bearing ring heat treatment quality assessment method of Example 1, and will not be repeated here.

[0084] Embodiment 4:

[0085] This embodiment provides a computer-readable storage medium on which a computer program is stored. When the program is executed by a processor, the steps of the method for evaluating the heat treatment quality of a bearing ring described in Example 1 are implemented.

[0086] Embodiment 5:

[0087] This embodiment provides an electronic device, including a memory, a processor, and a computer program stored in the memory and capable of running on the processor. When the processor executes the program, the steps of the bearing ring heat treatment quality assessment method described in Example 1 are implemented.

[0088] Embodiment 6:

[0089] This embodiment provides a computer program product, which includes a computer program. When the computer program is executed by a processor, the steps of the method for evaluating the heat treatment quality of a bearing ring described in Example 1 are implemented.

[0090] The above description is only a preferred embodiment of the present embodiment and is not intended to limit the present embodiment. For those skilled in the art, the present embodiment may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present embodiment shall be included in the protection scope of the present embodiment.

Claims

1. A method for evaluating the quality of heat treatment of a bearing ring, characterized in that: include: Obtain relevant parameters of heat treatment of bearing rings; According to the relevant parameters and the preset in-furnace temperature prediction model, a predicted value of the in-furnace temperature is obtained; According to the predicted value of furnace temperature, the heat treatment quality of bearing rings is evaluated; Among them, the furnace temperature prediction model is a trinomial mathematical model, each monomial includes a denominator and a numerator; the denominator in each monomial is the square value of the difference between the current workstation of the material frame and the preset constant; the numerator in each monomial includes the product of the corresponding fitting coefficient, the actual temperature expression of the corresponding temperature zone, and the cumulative furnace entry time expression.

2. A method for evaluating the heat treatment quality of a bearing ring according to claim 1, characterized in that: The related parameters include the temperature in each temperature zone, the cumulative furnace entry time and the position of the material frame.

3. A method for evaluating the heat treatment quality of a bearing ring according to claim 1, characterized in that: For a continuous heat treatment furnace, the furnace temperature prediction model is: Among them, T 代表 is the furnace temperature, a n is the fitting coefficient; T n is the actual temperature of temperature zone n; Time is the accumulated time of entering the furnace; Pos is the current position of the material frame; c n is a constant.

4. A method for evaluating the heat treatment quality of a bearing ring according to claim 3, characterized in that: For a walking beam heat treatment furnace, the furnace temperature prediction model is:

5. A method for evaluating the heat treatment quality of a bearing ring according to claim 1, characterized in that: The in-furnace temperature prediction model is used to predict the in-furnace temperature curve according to the real-time parameters experienced by the ferrule during heat treatment.

6. A method for evaluating the heat treatment quality of a bearing ring according to claim 5, characterized in that: According to the furnace temperature curve, the area enclosed by the furnace temperature curve and the coordinate axis is obtained. The larger the enclosed area, the greater the thermal stress and phase change stress, and the smaller the enclosed area, the smaller the thermal stress and phase change stress.

7. A method for evaluating the quality of heat treatment of a bearing ring, characterized in that: include: The data acquisition module is configured to: obtain relevant parameters of heat treatment of the bearing ring; The prediction module is configured to: obtain a predicted value of the in-furnace temperature according to the relevant parameters and a preset in-furnace temperature prediction model; The evaluation module is configured to: evaluate the heat treatment quality of the bearing ring according to the predicted value of the furnace temperature; Among them, the furnace temperature prediction model is a trinomial mathematical model, each monomial includes a denominator and a numerator; the denominator in each monomial is the square value of the difference between the current workstation of the material frame and the preset constant; the numerator in each monomial includes the product of the corresponding fitting coefficient, the actual temperature expression of the corresponding temperature zone, and the cumulative furnace entry time expression.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the steps of the method for evaluating the heat treatment quality of a bearing ring as described in any one of claims 1 to 6 are implemented.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and capable of running on the processor, characterized in that: When the processor executes the program, the steps of the method for evaluating the heat treatment quality of a bearing ring according to any one of claims 1 to 6 are implemented.

10. A computer program product, characterized in that The computer program product comprises a computer program, and when the computer program is executed by a processor, the steps of the method for evaluating the heat treatment quality of a bearing ring according to any one of claims 1 to 6 are implemented.

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