Quenching process for improving surface quality of plate spring and reducing oxidation and decarburization

Abstract

The invention relates to the technical field of metal heat treatment, in particular to a quenching process for improving the surface quality of a plate spring and reducing oxidation and decarburization, which comprises the following steps: putting the plate spring into a heating furnace, accelerating heating to 900-100 DEG C, and keeping the temperature for 30-35 minutes; the heated plate spring is placed in a quenching machine to be clamped and quenched; the tempering temperature is selected according to the hardness value required by the plate spring, and a continuous or periodic operation tempering furnace is adopted for tempering treatment; and the plate spring is relaxed, loaded, heated and subjected to heat preservation. By accurately controlling the heating temperature and time and combining the intelligent temperature control system to optimize the heating process, it is ensured that the plate spring is evenly heated within the optimal temperature range. In this way, the surface quality of the plate spring is improved, the performance difference caused by uneven heating is reduced, the oxidation and decarbonization phenomena are effectively reduced, the service life of the plate spring is prolonged, and the overall performance of the plate spring is improved.

Description

Technical Field

[0001] The invention relates to the technical field of metal heat treatment, in particular to a quenching process for improving the surface quality of a leaf spring and reducing oxidation and decarburization. Background Art

[0002] As an important automotive component, leaf springs are widely used in automotive suspension systems, and their performance directly affects the driving stability and safety of the vehicle. The traditional leaf spring quenching process mainly includes three main steps: heating, quenching and tempering. In the heating stage, the leaf spring is placed in a heating furnace, and the leaf spring is heated to a predetermined quenching temperature through radiation and convection from the heating source. Then, the heated leaf spring is quickly placed in a quenching medium for quenching to form a high-hardness martensitic structure. Finally, through tempering treatment, the hardness and toughness of the leaf spring are adjusted to achieve the required mechanical properties.

[0003] However, there are some problems that need to be solved in the existing leaf spring quenching process. First, the temperature control during the heating process is not precise enough, resulting in uneven heating of the leaf spring, which affects the quenching effect. Secondly, during the quenching process, due to the direct contact between the leaf spring and the quenching medium, it is easy to cause oxidation and decarburization on the surface of the leaf spring, which not only reduces the surface quality of the leaf spring, but also may affect its mechanical properties. In addition, for leaf springs with thicker thickness or complex shapes, traditional quenching processes are difficult to ensure the uniformity of their internal structure and the consistency of their mechanical properties. Summary of the invention

[0004] The present invention aims at the technical problems existing in the prior art and provides a quenching process for improving the surface quality of leaf springs and reducing oxidation and decarburization to solve the problem of uneven heating of leaf springs in the prior art quenching process.

[0005] The technical solution of the present invention to solve the above technical problem is as follows: A quenching process for improving the surface quality of a leaf spring and reducing oxidation and decarburization comprises the following steps:

[0006] Put the leaf spring into the heating furnace, accelerate the heating to 900-100℃, and keep it warm for 30-35 minutes;

[0007] Put the heated leaf spring into the quenching machine, clamp it and quench it;

[0008] The tempering temperature is selected according to the required hardness value of the leaf spring, and the tempering treatment is carried out in a continuous or periodic tempering furnace;

[0009] The leaf spring is relaxed, loaded and heated.

[0010] Based on the above technical solution, the present invention can also be improved as follows.

[0011] Furthermore, it also includes an intelligent temperature control system for controlling the heating temperature and heating time of the leaf spring, and the intelligent temperature control system for the heating time includes:

[0012] High-precision temperature sensor for real-time monitoring of the temperature inside the heating furnace;

[0013] A controller that automatically adjusts the power of the heating source according to the data fed back by the temperature sensor;

[0014] An actuator for executing the instructions of the controller to control the heating process;

[0015] Temperature prediction model for proactive adjustment of heating strategies.

[0016] Further, the establishment of the temperature prediction model includes the following steps:

[0017] Collect heating data of the heating furnace heating process, and clean and organize the heating data;

[0018] Physical digital model based on heat conduction equation is used to train heating data;

[0019] The heat conduction equation is solved by numerical method to obtain the mapping relationship between leaf spring temperature distribution and heating strategy;

[0020] According to the material and size of the leaf spring to be heated and the thermal inertia parameters of the heating furnace, the input parameters of the physical digital model are set;

[0021] Based on the input parameters, the prediction results of the temperature distribution in the heating furnace over time are obtained;

[0022] Analyze the prediction results and obtain the temperature change trend and distribution during the heating process;

[0023] The heating strategy is adjusted based on the prediction results to ensure that the leaf spring is heated evenly within the optimal temperature range.

[0024] Furthermore, the heating data includes temperature distribution in the heating furnace, power density of the heating source, heating time, and material and size information of the leaf spring.

[0025] Furthermore, the process of establishing and solving the physical digital model based on the heat conduction equation includes:

[0026] Assume that the temperature distribution in the heating furnace is T(x, y, z, t), where x, y, z are spatial coordinates and t is time. According to the heat conduction equation, the change of temperature distribution over time can be expressed as:

[0027]

[0028] Among them, α is the thermal diffusivity, Q is the power density of the heating source, c is the specific heat capacity of the material, and ρ is the density of the material;

[0029] Assume that the temperature distribution in the heating furnace is uniform, that is, T(x,y,z,t)=T(t);

[0030] The heat conduction equation is simplified to:

[0031]

[0032] Where V is the volume of the heating furnace, A is the surface area of ​​the heating furnace, h is the convection heat transfer coefficient, and T∞ is the ambient temperature.

[0033] Furthermore, the adjusting the heating strategy includes adjusting the power density of the heating source, the heating time or the thermal insulation performance parameters of the heating furnace.

[0034] Furthermore, the furnace of the heating furnace is divided into multiple heating zones, and each heating zone is equipped with an independent intelligent temperature control system.

[0035] Furthermore, for leaf springs with larger thickness or complex shape, the steps of segmented tempering treatment are as follows;

[0036] Divide the leaf spring into several areas and set different tempering temperatures and times for each area;

[0037] For leaf springs with high strength requirements, a fast cooling rate is used to retain more quenched structures;

[0038] For leaf springs with high toughness requirements, a slow cooling rate is used to eliminate stress and improve toughness;

[0039] The tempering furnace is filled with inert gas or reducing gas to reduce oxidation and decarburization on the surface of the leaf spring.

[0040] Further, the leaf spring is relaxed, a load is added, and the leaf spring is heated and kept warm, including the following steps:

[0041] Clean the oil and dust on the surface of the leaf spring and fix it with a clamp;

[0042] Apply the determined load evenly to the leaf spring, and the direction of the load application is consistent with the working direction of the leaf spring;

[0043] The whole leaf spring is uniformly heated to a certain temperature by a heating device for heat preservation;

[0044] After the warming time is over, slowly unload the load applied to the leaf spring and let it cool naturally to room temperature.

[0045] Moreover, the quenching process for improving the surface quality of leaf springs and reducing oxidation decarburization provided by the present invention has at least the following beneficial effects compared with the prior art:

[0046] Improving the surface quality of leaf springs and reducing oxidation and decarburization:

[0047] By precisely controlling the heating temperature and time, combined with the optimization of the heating process by the intelligent temperature control system, the present invention ensures that the leaf spring is evenly heated within the optimal temperature range. This not only improves the surface quality of the leaf spring, reduces the performance differences caused by uneven heating, but also effectively reduces the oxidation and decarburization phenomenon, thereby extending the service life of the leaf spring and improving its overall performance.

[0048] Optimize quenching and tempering processes to meet diverse needs:

[0049] The present invention adopts segmented tempering treatment for leaf springs with large thickness or complex shapes, and flexibly adjusts the cooling rate and tempering temperature according to the hardness and toughness requirements of the leaf springs. In addition, the additional load and heating and heat preservation measures in the relaxation process further improve the internal stress distribution and microstructure of the leaf springs. These optimization measures enable the present invention to meet the quenching and tempering process requirements of leaf springs with different materials, sizes and performance requirements, and improve the flexibility and applicability of the process. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 It is a schematic diagram of the process flow of the present invention;

[0051] Figure 2 It is a schematic diagram of the principle of the intelligent temperature control system of the present invention. DETAILED DESCRIPTION

[0052] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0053] It should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integrally formed structure. For ordinary technicians in this field, the specific meanings of such terms in this patent can be understood according to specific circumstances.

[0054] like Figure 1 and Figure 2 As shown, the quenching process designed by the present invention to improve the surface quality of the leaf spring and reduce oxidation and decarburization includes the following steps:

[0055] Put the leaf spring into the heating furnace, accelerate the heating to 900-100℃, and keep it warm for 30-35 minutes;

[0056] Put the heated leaf spring into the quenching machine, clamp it and quench it;

[0057] The tempering temperature is selected according to the required hardness value of the leaf spring, and the tempering treatment is carried out in a continuous or periodic tempering furnace;

[0058] The leaf spring is relaxed, loaded and heated.

[0059] In this embodiment, the leaf spring is rapidly heated to 900-1000°C (preferably 950°C) and kept warm for a certain period of time (30-35 minutes, preferably 30 minutes) by precisely controlling the heating temperature and time, and then rapidly quenched to form a high-hardness structure. Afterwards, a suitable tempering temperature is selected according to the required hardness for tempering treatment to adjust the hardness and toughness of the leaf spring. Finally, the internal stress distribution and overall performance of the leaf spring are further improved by relaxing the additional load and heating and keeping warm, thereby achieving the purpose of improving surface quality and reducing oxidation and decarburization.

[0060] As an embodiment, an intelligent temperature control system for controlling the heating temperature and heating time of the leaf spring is also included, and the intelligent temperature control system for the heating time includes:

[0061] High-precision temperature sensor for real-time monitoring of the temperature inside the heating furnace;

[0062] A controller that automatically adjusts the power of the heating source according to the data fed back by the temperature sensor;

[0063] An actuator for executing the instructions of the controller to control the heating process;

[0064] Temperature prediction model for proactive adjustment of heating strategies.

[0065] Specifically, the establishment of the temperature prediction model includes the following steps:

[0066] Collect heating data of the heating furnace heating process, and clean and organize the heating data;

[0067] Physical digital model based on heat conduction equation is used to train heating data;

[0068] The heat conduction equation is solved by numerical method to obtain the mapping relationship between leaf spring temperature distribution and heating strategy;

[0069] According to the material and size of the leaf spring to be heated and the thermal inertia parameters of the heating furnace, the input parameters of the physical digital model are set;

[0070] Based on the input parameters, the prediction results of the temperature distribution in the heating furnace over time are obtained;

[0071] Analyze the prediction results and obtain the temperature change trend and distribution during the heating process;

[0072] The heating strategy is adjusted based on the prediction results to ensure that the leaf spring is heated evenly within the optimal temperature range.

[0073] First, the system collects detailed data from the heating furnace during the heating process, and cleans and organizes the data to ensure the accuracy and completeness of the data. Then, the physical digital model based on the heat conduction equation is used to train these heating data to establish a mapping relationship between the leaf spring temperature distribution and the heating strategy. This mapping relationship can be further refined by using numerical methods to solve the heat conduction equation.

[0074] In the process of model building, it is necessary to set the input parameters of the physical digital model according to the material and size of the leaf spring to be heated and the thermal inertia parameters of the heating furnace, etc. These parameters are crucial to the accuracy of the prediction results.

[0075] Based on the set input parameters, the model can predict the change of temperature distribution in the heating furnace over time. By deeply analyzing the prediction results, the temperature change trend and distribution during the heating process can be obtained, thereby understanding the dynamic characteristics of the heating process.

[0076] Finally, based on the prediction results, the system can intelligently adjust the heating strategy to ensure that the leaf spring is evenly heated within the optimal temperature range. This can not only improve the surface quality of the leaf spring, but also effectively reduce oxidation and decarburization, thereby improving the effect of the entire quenching process.

[0077] The heating data includes the temperature distribution in the heating furnace, the power density of the heating source, the heating time, and the material and size information of the leaf spring.

[0078] The temperature distribution in the heating furnace, which reflects the temperature difference at different positions in the furnace; the power density of the heating source, which determines the intensity and efficiency of the heating; the heating time, that is, the length of time the leaf spring is heated in the furnace; and the material and size information of the leaf spring, these parameters have an important influence on the heat conduction and temperature distribution during the heating process.

[0079] Specifically, the process of establishing and solving the physical digital model based on the heat conduction equation includes:

[0080] Assume that the temperature distribution in the heating furnace is T(x, y, z, t), where x, y, z are spatial coordinates and t is time. According to the heat conduction equation, the change of temperature distribution over time can be expressed as:

[0081]

[0082] Among them, α is the thermal diffusivity, Q is the power density of the heating source, c is the specific heat capacity of the material, and ρ is the density of the material;

[0083] Assume that the temperature distribution in the heating furnace is uniform, that is, T(x,y,z,t)=T(t);

[0084] The heat conduction equation is simplified to:

[0085]

[0086] Where V is the volume of the heating furnace, A is the surface area of ​​the heating furnace, h is the convection heat transfer coefficient, and T∞ is the ambient temperature.

[0087] The principle of establishing and solving the physical digital model based on the heat conduction equation can be summarized as follows:

[0088] First, we set the temperature distribution in the heating furnace to be a function T(x,y,z,t) about the spatial coordinates (x,y,z) and time t. This function describes the temperature at any position in the furnace at any time.

[0089] We then use the heat conduction equation to describe how the temperature distribution changes over time. The heat conduction equation is a partial differential equation that takes into account the effects of thermal diffusivity, the power density of the heating source, the specific heat capacity and density of the material on the temperature distribution.

[0090] To simplify the problem, we assume that the temperature distribution in the heating furnace is uniform, that is, the temperature does not change with the spatial coordinates (x, y, z), but only with time t. In this way, the heat conduction equation is simplified to an ordinary differential equation that only contains time t.

[0091] In this simplified heat conduction equation, we also need to consider the heat exchange between the heating furnace and the environment. This is usually expressed by the convection heat transfer coefficient h and the ambient temperature. The volume V and surface area A of the heating furnace are also important factors affecting heat exchange.

[0092] Finally, we use numerical methods to solve this simplified heat conduction equation and obtain the predicted results of the temperature distribution in the heating furnace over time. This result can be used to guide the adjustment of the heating strategy to ensure that the leaf spring is heated evenly within the optimal temperature range.

[0093] Through this process, we established a physical digital model based on the heat conduction equation and solved it to obtain the predicted results of the temperature distribution in the heating furnace. This model can help us better understand the temperature changes during the heating process, optimize the heating strategy, and improve the quality and efficiency of the quenching process.

[0094] As an implementation method, the process of adjusting the heating strategy covers multiple aspects of optimization, including but not limited to adjusting the power density of the heating source to control the intensity and rate of heating; adjusting the heating time, that is, the length of time the leaf spring is heated in the heating furnace, to ensure that the leaf spring can reach the predetermined temperature and is heated evenly; and adjusting the insulation performance parameters of the heating furnace, such as the insulation material and thickness of the furnace wall, to reduce heat loss and maintain a stable temperature in the furnace.

[0095] As an implementation mode, the furnace of the heating furnace is divided into multiple heating zones, and each heating zone is equipped with an independent intelligent temperature control system.

[0096] This not only ensures that the leaf springs in each area are evenly heated within the optimal temperature range, but also allows for personalized temperature settings and adjustments based on the different materials, sizes and heating requirements of the leaf springs.

[0097] As an implementation method, for leaf springs with a large thickness or a complex shape, the following steps are used for the segmented tempering treatment:

[0098] Divide the leaf spring into several areas and set different tempering temperatures and times for each area;

[0099] For leaf springs with high strength requirements, a fast cooling rate is used to retain more quenched structures;

[0100] For leaf springs with high toughness requirements, a slow cooling rate is used to eliminate stress and improve toughness;

[0101] The tempering furnace is filled with inert gas or reducing gas to reduce oxidation and decarburization on the surface of the leaf spring.

[0102] First, the leaf spring is divided into several areas according to its thickness and shape. These areas may have different thermal conductivity and quenching microstructure distribution, so different tempering temperatures and times need to be set separately to ensure that each area can achieve the ideal balance of hardness and toughness.

[0103] For leaf springs with high strength requirements, a fast cooling rate is required to retain more quenched structures. Rapid cooling helps maintain the high hardness state after quenching while reducing the structural changes during tempering, thereby meeting high strength requirements.

[0104] On the contrary, for leaf springs with high toughness requirements, a slow cooling rate is required. Slow cooling helps to eliminate the internal stress and brittle structure generated during the quenching process, improve the toughness and plasticity of the leaf spring, and meet the high toughness requirements.

[0105] In addition, filling the tempering furnace with inert gas or reducing gas is also an important measure. These gases can effectively reduce the oxidation and decarburization of the leaf spring surface at high temperature, protect the surface quality of the leaf spring, and also help improve the stability and controllability of the tempering process.

[0106] As an implementation method, relaxing the leaf spring, adding a load and heating and keeping warm include the following steps:

[0107] Clean the oil and dust on the surface of the leaf spring and fix it with a clamp;

[0108] Apply the determined load evenly to the leaf spring, and the direction of the load application is consistent with the working direction of the leaf spring;

[0109] The whole leaf spring is uniformly heated to a certain temperature by a heating device for heat preservation;

[0110] After the warming time is over, slowly unload the load applied to the leaf spring and let it cool naturally to room temperature.

[0111] First, to ensure the treatment effect and avoid contamination, the oil and dust on the surface of the leaf spring need to be thoroughly cleaned. After cleaning, the leaf spring is fixed with a special clamp to ensure the stability and safety of the leaf spring in the subsequent steps.

[0112] Next, according to the actual working conditions and requirements of the leaf spring, determine the appropriate load size and apply it evenly to the leaf spring. The direction of load application should be consistent with the actual working direction of the leaf spring to simulate the stress state in the actual working scenario.

[0113] Subsequently, the entire leaf spring is evenly heated by a heating device until it reaches a predetermined temperature. During the heating process, it is necessary to ensure that the temperature is evenly distributed to avoid deformation or uneven performance of the leaf spring caused by uneven temperature. After heating to the predetermined temperature, a heat preservation treatment is performed to keep the leaf spring at this temperature for a period of time to fully release internal stress and improve the microstructure.

[0114] After the holding time is over, slowly unload the load applied to the leaf spring to avoid stress concentration and deformation caused by sudden unloading. After unloading, let the leaf spring cool naturally to room temperature to ensure that its internal stress is fully released and the microstructure is stable.

[0115] It should be noted that, in this article, the terms "include", "comprising" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. Unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0116] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0117] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A quenching process for improving the surface quality of leaf springs and reducing oxidation and decarburization, characterized in that: The following steps are involved: Put the leaf spring into the heating furnace, accelerate the heating to 900-100℃, and keep it warm for 30-35 minutes; Put the heated leaf spring into the quenching machine, clamp it and quench it; The tempering temperature is selected according to the required hardness value of the leaf spring, and the tempering treatment is carried out in a continuous or periodic tempering furnace; The leaf spring is relaxed, loaded and heated.

2. The quenching process for improving the surface quality of leaf springs and reducing oxidation decarburization according to claim 1 is characterized in that: It also includes an intelligent temperature control system for controlling the heating temperature and heating time of the leaf spring, and the intelligent temperature control system for the heating time includes: High-precision temperature sensor for real-time monitoring of the temperature inside the heating furnace; A controller that automatically adjusts the power of the heating source according to the data fed back by the temperature sensor; An actuator for executing the instructions of the controller to control the heating process; Temperature prediction model for proactive adjustment of heating strategies.

3. The quenching process for improving the surface quality of leaf springs and reducing oxidation decarburization according to claim 2 is characterized in that: The establishment of the temperature prediction model comprises the following steps: Collect heating data of the heating furnace heating process, and clean and organize the heating data; Physical digital model based on heat conduction equation is used to train heating data; The heat conduction equation is solved by numerical method to obtain the mapping relationship between leaf spring temperature distribution and heating strategy; According to the material and size of the leaf spring to be heated and the thermal inertia parameters of the heating furnace, the input parameters of the physical digital model are set; Based on the input parameters, the prediction results of the temperature distribution in the heating furnace over time are obtained; Analyze the prediction results and obtain the temperature change trend and distribution during the heating process; The heating strategy is adjusted based on the prediction results to ensure that the leaf spring is heated evenly within the optimal temperature range.

4. The quenching process for improving the surface quality of leaf springs and reducing oxidation decarburization according to claim 3 is characterized in that: The heating data includes the temperature distribution in the heating furnace, the power density of the heating source, the heating time, and the material and size information of the leaf spring.

5. The quenching process for improving the surface quality of leaf springs and reducing oxidation decarburization according to claim 3 is characterized in that: The process of establishing and solving the physical digital model based on the heat conduction equation includes: Assume that the temperature distribution in the heating furnace is T(x, y, z, t), where x, y, z are spatial coordinates and t is time. According to the heat conduction equation, the change of temperature distribution over time can be expressed as: Among them, α is the thermal diffusivity, Q is the power density of the heating source, c is the specific heat capacity of the material, and ρ is the density of the material; Assume that the temperature distribution in the heating furnace is uniform, that is, T(x,y,z,t)=T(t); The heat conduction equation is simplified to: Where V is the volume of the heating furnace, A is the surface area of ​​the heating furnace, h is the convection heat transfer coefficient, and T∞ is the ambient temperature.

6. The quenching process for improving the surface quality of leaf springs and reducing oxidation decarburization according to claim 3 is characterized in that: The adjusting heating strategy includes adjusting the power density of the heating source, the heating time or the heat preservation performance parameters of the heating furnace.

7. The quenching process for improving the surface quality of leaf springs and reducing oxidation decarburization according to claim 2 is characterized in that: The furnace of the heating furnace is divided into multiple heating zones, and each heating zone is equipped with an independent intelligent temperature control system.

8. The quenching process for improving the surface quality of leaf springs and reducing oxidation decarburization according to claim 1, characterized in that: For leaf springs with larger thickness or complex shape, the steps of segmented tempering treatment are as follows; Divide the leaf spring into several areas and set different tempering temperatures and times for each area; For leaf springs with high strength requirements, a fast cooling rate is used to retain more quenched structures; For leaf springs with high toughness requirements, slow cooling rates are used to eliminate stress and improve toughness; The tempering furnace is filled with inert gas or reducing gas to reduce oxidation and decarburization on the surface of the leaf spring.

9. The quenching process for improving the surface quality of leaf springs and reducing oxidation and decarburization according to claim 1, characterized in that: The following steps are involved in relaxing the leaf spring, applying a load and heating the leaf spring: Clean the oil and dust on the surface of the leaf spring and fix it with a clamp; Apply the determined load evenly to the leaf spring, and the direction of the load application is consistent with the working direction of the leaf spring; The whole leaf spring is uniformly heated to a certain temperature by a heating device for heat preservation; After the warming time is over, slowly unload the load applied to the leaf spring and let it cool naturally to room temperature.

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