A method of heat treating a shaft

Abstract

The present application relates to the technical field of heat treatment, in particular to a heat treatment method of a shaft. The method comprises determining a first shaft shoulder of the shaft; clamping and positioning the shaft vertically between a first center and a second center; based on the clamping and positioning being completed, controlling the first center to rotate at a first rotating speed; controlling an inductor to move to a first position to pre-heat the shaft at a first temperature; based on the pre-heating being completed, controlling the inductor to move to a second position, and controlling a spraying ring to move to a third position; based on the inductor being located at the second position and the spraying ring being located at the third position, controlling the inductor to heat the shaft at a second temperature, controlling the spraying ring to spray, and controlling the inductor and the spraying ring to ascend until the heat treatment is completed; thus, the problem of uneven hardened layer depth of the shaft surface and the problem of excessive organization of the shaft with a large diameter variation are solved.

Description

Technical Field

[0001] This invention relates to the field of heat treatment technology, and more specifically, to a heat treatment method for a shaft. Background Technology

[0002] In vehicle components, the shaft is a core component for power transmission and part positioning. The assembly end of the shaft, as a critical area connecting it to other components such as bearings, gears, and flanges, directly determines the operational stability of the entire mechanical system due to its structural design and performance indicators. Shafts, due to assembly and strength requirements, often have shoulders of varying sizes, with the shoulder end face perpendicular to the shaft axis. Shafts typically require optimization through heat treatment processes, such as quenching, to improve the overall mechanical properties of the material. When the shoulder diameter varies significantly, the heat treatment of the inner ring of the shoulder end face is much less than that of the outer ring. This results in uneven heating of the shoulder end face, even though it is part of the shaft's outer surface, affecting the consistency of the shaft's strength.

[0003] Therefore, ensuring that the hardened layer depth is uniform and the microstructure is qualified on the surface of shafts with large diameter variations is a technical problem that urgently needs to be solved. Summary of the Invention

[0004] To address the issues of uneven hardened layer depth and microstructure deviations on the surface of shafts with significant diameter variations, this invention provides a heat treatment method for shafts, comprising:

[0005] Determine the first shoulder of the shaft;

[0006] The shaft is clamped and positioned vertically between the first and second tips; wherein the second tip is located above the first tip.

[0007] Based on the completion of the clamping and positioning, the first tip is controlled to rotate at a first speed.

[0008] The sensor is moved to a first position to preheat the shaft at a first temperature; wherein, when the sensor is in the first position, the sensor is coaxial with the shaft, and the distance between the sensor and the end face of the first shaft shoulder is less than a threshold value.

[0009] Based on the completion of preheating, the sensor is controlled to move to the second position, and the spray ring is controlled to move to the third position; wherein, the third position is located below the second position; when the sensor is in the second position, the sensor is located at the bottom of the heat treatment area of ​​the shaft;

[0010] Based on the sensor being located in the second position and the spray ring being located in the third position, the sensor is controlled to heat the shaft at a second temperature, the spray ring is controlled to spray, and the sensor and the spray ring are controlled to rise until the heat treatment is completed; wherein, the second temperature is greater than the first temperature.

[0011] In some embodiments, determining the first shoulder of the shaft includes:

[0012] Obtain the diameter change of each shoulder of the shaft;

[0013] The shoulder with the largest diameter change is identified as the first shoulder.

[0014] In some embodiments, clamping and positioning the shaft vertically between the first and second centers includes:

[0015] The shaft is clamped and positioned vertically between the first and second centers in a first posture; wherein, the first posture includes the end face of the first shaft shoulder facing upward; the portion of the sensor covering the shaft is located above the end face of the first shaft shoulder.

[0016] In some embodiments, the first temperature is positively correlated with the change in diameter of the first shoulder; the threshold is positively correlated with the change in diameter of the first shoulder.

[0017] In some embodiments, prior to the steps of controlling the sensor to move to the second position and controlling the spray ring to move to the third position based on the completion of the preheating, the heat treatment method for the shaft further includes:

[0018] Based on the completion of preheating, the sensor is controlled to move to a fourth position; wherein the fourth position is located below the second position; when the sensor is in the fourth position, the sensor covers the first tip;

[0019] The sensor is controlled to heat at a third temperature at the fourth position until the first heating duration is reached.

[0020] In some embodiments, the third temperature is lower than the second temperature.

[0021] In some embodiments, the heat treatment method for the shaft further includes:

[0022] Based on the sensor being located in the second position and the spray ring being located in the third position, the first tip is controlled to rotate at a second rotation speed.

[0023] In some embodiments, the second rotational speed is greater than the first rotational speed.

[0024] In some embodiments, the difference between the second rotational speed and the first rotational speed is positively correlated with the third temperature.

[0025] In some embodiments, the distance between the first shoulder and the second position is a first distance; the duration of the preheating is positively correlated with the first distance.

[0026] To address the issues of uneven hardened layer depth and microstructural defects on shaft surfaces with large diameter variations, this invention offers the following advantages:

[0027] By controlling the inductor to move to a first position and preheat the first shoulder at a first temperature, the portion of the shaft covered by the inductor is heated, allowing heat to be transferred to the inner ring of the first shoulder. This results in the inner ring of the first shoulder having a higher temperature than the outer ring, ensuring uniform heating of the end face surface of the first shoulder during the overall heat treatment from bottom to top by the inductor. This reduces thermal stress during the quenching process and minimizes deformation. Simultaneously, it enables precise heat transfer to the first shoulder and synchronous heating and spraying of the shaft from the bottom to top of the heat treatment area, achieving uniform and sufficient pretreatment heating at the first shoulder and a uniform and stable overall hardened layer depth on the shaft. Attached Figure Description

[0028] Figure 1 A flowchart of a heat treatment method for a shaft according to one embodiment is shown;

[0029] Figure 2 A schematic diagram of the shaft during the heat treatment process is shown;

[0030] Figure 3 It shows Figure 2 A schematic diagram of the central axis;

[0031] Figure 4 It shows Figure 2 A schematic diagram of the sensor and spray pipe ring.

[0032] Reference numerals: First shoulder 10; First tip 20; Second tip 30; Spray ring 40; Sensor 50; First position 60; Second position 70; Third position 80. Detailed Implementation

[0033] The present disclosure will now be discussed with reference to several exemplary embodiments. It should be understood that these embodiments are discussed only to enable those skilled in the art to better understand and thus implement the present disclosure, and are not intended to imply any limitation on the scope of the disclosure.

[0034] As used herein, the term "comprising" and its variations are to be interpreted as open-ended terms meaning "including but not limited to". The term "based on" is to be interpreted as "at least partially based on". The terms "one embodiment" and "an embodiment" are to be interpreted as "at least one embodiment". The term "another embodiment" is to be interpreted as "at least one other embodiment". The terms "upper", "lower", "left", "right", "front", "rear", "top", "bottom", "inner", "outer", "vertical", "horizontal", "lateral", "longitudinal", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. These terms are primarily for the purpose of better describing this application and its embodiments and are not intended to limit the indicated devices, elements, or components to having a specific orientation or being constructed and operated in a specific orientation. Furthermore, some of the above terms may be used to indicate other meanings besides orientations or positional relationships; for example, the term "upper" may in some cases indicate a dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application according to the specific circumstances. In addition, the terms "installed", "set up", "equipped with", "connected", and "linked" should be interpreted broadly. For example, it can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, elements, or components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances. Furthermore, the terms "first," "second," etc., are mainly used to distinguish different devices, elements, or components (the specific types and structures may be the same or different), and are not used to indicate or imply the relative importance or quantity of the indicated devices, elements, or components. Unless otherwise stated, "a plurality of" means two or more.

[0035] In vehicle components, shafts are core components for power transmission and component positioning. The assembly end of the shaft, as a critical area connecting it to other components such as bearings, gears, and flanges, directly determines the operational stability of the entire mechanical system through its structural design and performance indicators. Due to assembly and strength requirements, shafts often have shoulders of varying sizes, with the shoulder end face perpendicular to the shaft axis. Shafts typically require optimization through heat treatment processes, such as quenching, to improve the overall mechanical properties of the material. When the shoulder diameter varies significantly, the heat treatment level of the inner ring of the shoulder end face is much lower than that of the outer ring. This results in uneven heating of the shoulder end face, which, despite being part of the shaft's outer surface, affects the consistency of shaft strength. Therefore, ensuring a uniform depth and qualified microstructure of the hardened layer on the surface of shafts with large diameter variations is a pressing technical problem that needs to be solved.

[0036] In this embodiment, to solve the above problems, this application provides a heat treatment method for a shaft, such as... Figure 1 As shown, the heat treatment method for the shaft includes steps S10 to S60. Steps S10 to S60 will be described in detail below:

[0037] Step S10: Determine the first shoulder 10 of the shaft.

[0038] Step S20 involves clamping and positioning the shaft vertically between the first center 20 and the second center 30. This ensures the shaft maintains a stable posture during subsequent rotation, heating, and spraying, preventing positional deviations in the heat treatment process due to shaft offset or shaking, thus guaranteeing the accuracy of the heat treatment operation. For example, Figure 2 As shown, the second apex 30 is located above the first apex 20.

[0039] In step S30, based on the completion of clamping and positioning, the first tip 20 is controlled to rotate at the first speed, so that the shaft rotates at a uniform speed around its own axis, ensuring that the shaft can be evenly contacted by the heat transferred by the subsequent sensor 50 in the circumferential direction, and avoiding the problem of uneven local heating of the shaft.

[0040] In step S40, the sensor 50 is moved to the first position 60 to preheat the shaft at a first temperature. This ensures that the heat from the sensor 50 is precisely applied to the area near the first shaft shoulder 10. The heat can be transferred through the shaft to the inner diameter of the first shaft shoulder 10 (a concave, difficult-to-heat area), and then to the outer ring of the first shaft shoulder 10 (a convex area), thus achieving uniform preheating of the first shaft shoulder 10. Simultaneously, preheating reduces the thermal stress during the quenching process of the first shaft shoulder 10, thereby minimizing deformation. For example... Figure 3 , Figure 4 As shown, when sensor 50 is in the first position 60, sensor 50 is coaxial with the shaft, and the distance between sensor 50 and the end face of the first shoulder 10 is less than a threshold value, i.e. Figure 3 As shown, G represents the distance.

[0041] Step S50: Based on the completion of preheating, control the sensor 50 to move to the second position 70, and control the spray ring 40 to move to the third position 80, so that the sensor 50 and the spray ring 40 form a vertically corresponding arrangement, ensuring that after the sensor 50 heats the shaft, the spray ring 40 can spray water onto the shaft in a timely manner. Wherein, as... Figure 3 As shown, the third position 80 is located below the second position 70. When the sensor 50 is in the second position 70, the sensor 50 is located at the bottom of the heat treatment area of ​​the shaft, thereby enabling the heat treatment to cover the entire heat treatment area of ​​the shaft.

[0042] In step S60, based on the sensor 50 being located at the second position 70 and the spray ring 40 being located at the third position 80, the sensor 50 is controlled to heat the shaft at a second temperature, the spray ring 40 is controlled to spray, and the sensor 50 and the spray ring 40 are controlled to rise, so as to achieve sufficient heating and cooling of the heat treatment area of ​​the shaft from bottom to top. At the same time, the second temperature can meet the temperature requirements of the shaft heat treatment, and during the rising process, it is ensured that the entire shaft can be heated and cooled sufficiently, thereby ensuring the overall heat treatment effect of the shaft, until the heat treatment is completed. The second temperature is greater than the first temperature.

[0043] Further, step S10 includes steps S11 and S12, and the heat treatment method for the shaft is performed sequentially through steps S11, S12, S20, S30, S40, S50, and S60. Steps S11 and S12 will be described in detail below:

[0044] Step S11: Obtain the diameter change of each shoulder of the shaft to provide data for the subsequent accurate selection of the first shoulder 10.

[0045] Step S12: The shoulder with the largest diameter change is identified as the first shoulder 10. This allows for precise location of the area with the most significant structural abrupt change on the shaft, namely the assembly end with the largest diameter and the most obvious ridge. Since the strength of this area needs to be guaranteed, the target of the subsequent targeted preheating operation is clearly defined.

[0046] Further, step S20 includes step S21, in which the heat treatment method for the shaft is performed sequentially through steps S10, S21, S30, S40, S50, and S60. Step S21 will be described in detail below:

[0047] Step S21: The shaft is vertically clamped and positioned between the first tip 20 and the second tip 30 in a first posture. This first posture includes the end face of the first shoulder 10 facing upwards, with the portion of the shaft covered by the sensor 50 positioned above the end face of the first shoulder 10. This means that the heat from the sensor 50 is applied more precisely to the area near the first shoulder 10, facilitating heat transfer downwards along the shaft to the smaller diameter (recessed) and harder-to-heat area of ​​the first shoulder 10, while simultaneously ensuring heat can be further transferred to the larger diameter (protruding) area, thus achieving a uniform hardened layer depth at the first shoulder 10. Furthermore, the upward-facing end face of the first shoulder allows the subsequent spray ring 40 to precisely cover the surface of the first shoulder 10, ensuring the effectiveness of the quenching process.

[0048] Furthermore, the first temperature is positively correlated with the diameter change of the first shoulder 10. This should be understood as follows: the larger the diameter change of the first shoulder 10, the more obvious the assembly end bend of the corresponding shaft and the more significant the diameter difference. Therefore, the preheating temperature is adjusted accordingly. The first shoulder 10 with a large diameter change is preheated with a higher first temperature to ensure that its small and difficult-to-heat parts can fully absorb heat and avoid insufficient preheating due to insufficient temperature.

[0049] The threshold is positively correlated with the diameter change of the first shoulder 10. This should be understood as follows: the larger the diameter change of the first shoulder 10, the larger the spacing, ensuring that heat is effectively transferred to the critical area. This avoids the first shoulder 10 being too close to the sensor 50, which would cause the sensor 50 to directly heat the outer ring of the first shoulder, resulting in uneven preheating of the first shoulder 10. A first shoulder 10 with a small diameter change achieves precise heat transfer through a smaller spacing, thus ensuring that the first shoulder 10 can all undergo uniform preheating.

[0050] Furthermore, prior to step S50, the heat treatment method for the shaft also includes step S70, which comprises steps S71 and S72. The heat treatment method for the shaft executes steps S10, S20, S30, S40, S71, S72, S50, and S60 sequentially. Steps S71 and S72 will be described in detail below:

[0051] In step S71, based on the completion of preheating, the sensor 50 is moved to the fourth position. The fourth position is located below the second position 70. In the fourth position, the sensor 50 covers the first tip 20. This allows the sensor 50 to target the first tip 20 and the surrounding shaft area, preventing heat loss due to shaft clamping and positioning from creating a temperature difference with other areas.

[0052] In step S72, the control sensor 50 is heated at the third temperature in the fourth position until the first heating time is reached. This should be understood as the shaft's hardness decreasing after being heated near the first tip 20, causing the end of the first tip 20 to embed more deeply into the shaft. This allows the first tip 20 and the second tip 30 to stably clamp the shaft, preventing it from shifting during the heat treatment process.

[0053] Furthermore, the third temperature is lower than the second temperature, which can prevent the fourth position from becoming overly softened due to excessive temperature, thereby damaging the shaft.

[0054] In some embodiments, the heat treatment method for the shaft further includes step S80. The heat treatment method for the shaft sequentially executes steps S10, S20, S30, S40, S71, S72, S50, S60, and S80. Step S80 will be described in detail below:

[0055] In step S80, based on the sensor 50 being located at the second position 70 and the spray ring 40 being located at the third position 80, the first tip 20 is controlled to rotate at the second rotation speed. This enables the shaft to rotate at a uniform speed around its own axis during the heat treatment process, ensuring that all parts of the shaft in the circumferential direction can uniformly contact the heat transferred by the sensor 50 and the cooling medium of the spray ring 40, thereby ensuring that the overall hardened layer depth of the shaft is uniform.

[0056] Furthermore, the second rotational speed is greater than the first rotational speed. This should be understood as follows: during the formal heat treatment stage when the inductor 50 is in the second position 70 and the spray ring 40 is in the third position 80, the shaft can rotate around its own axis at a faster speed. This allows for more frequent and thorough contact between the various parts of the shaft in the circumferential direction and the second temperature heat transferred by the inductor 50 and the cooling medium of the spray ring 40. This effectively reduces the temperature difference and cooling difference caused by the difference in contact time in different parts of the shaft, thereby achieving a more uniform heating and cooling effect for the entire shaft and further ensuring the uniform depth of the hardened layer of the shaft.

[0057] Furthermore, the difference between the second rotational speed and the first rotational speed is positively correlated with the third temperature. This should be understood as follows: when the third temperature is higher, it indicates that the first tip 20 is embedded deeper, and therefore the first tip 20 and the second tip 30 can clamp the shaft more tightly. Consequently, the difference between the second rotational speed and the first rotational speed is also greater. The first rotational speed is essentially a constant, meaning that the higher the third temperature, the faster the second rotational speed. This ensures shaft stability and allows for a more uniform hardened layer on the shaft during heat treatment.

[0058] Furthermore, the distance between the first shoulder 10 and the second position 70 is called the first distance, and the duration of preheating is positively correlated with the first distance. When the first distance is large, the preheating time can be extended to ensure that the heat has enough time to be transferred to the first shoulder 10, avoiding insufficient preheating due to long distance and large heat loss. When the first distance is small, the shorter preheating time can ensure that the first shoulder 10 is fully heated while avoiding energy waste or local overheating of the shaft due to excessive heating time. This ensures that the first shoulder 10 can obtain uniform and sufficient preheating under different first distances, laying a good foundation for subsequent heat treatment and further ensuring the strength of the assembly end of the shaft, i.e., the first shoulder 10.

[0059] Those skilled in the art will understand that the above embodiments are specific examples of implementing this disclosure, and in practical applications, various changes can be made in form and detail without departing from the scope of this disclosure.

Claims

1. A method of heat treating a shaft, characterized by, The shaft heat treatment method comprises: determining a first shoulder of the shaft; clamping and positioning the shaft vertically between a first center and a second center; wherein the second center is above the first center; controlling the first center to rotate at a first rotating speed based on the clamping and positioning being completed; controlling an inductor to move to a first position to pre-heat the shaft at a first temperature; wherein, in the state that the inductor is at the first position, the inductor is coaxial with the shaft, and the distance between the inductor and the end face of the first shoulder is less than a threshold value; controlling the inductor to move to a second position and controlling a spraying ring to move to a third position based on the pre-heating being completed; wherein the third position is below the second position; in the state that the inductor is at the second position, the inductor is at the bottom end of the heat treatment area of the shaft; controlling the inductor to heat the shaft at a second temperature, controlling the spraying ring to spray, and controlling the inductor and the spraying ring to rise until the heat treatment is completed based on the inductor being at the second position and the spraying ring being at the third position; wherein the second temperature is greater than the first temperature. The determining a first shoulder of the shaft comprises: obtaining a diameter variation of each shoulder of the shaft; determining the shoulder with the largest diameter variation as the first shoulder. The clamping and positioning the shaft vertically between a first center and a second center comprises: clamping and positioning the shaft vertically between a first center and a second center in a first posture; wherein the first posture comprises that the end face of the first shoulder is arranged upward; and the part of the shaft covered by the inductor is above the end face of the first shoulder.

2. The shaft heat treatment method according to claim 1, wherein: the first temperature is positively correlated with the diameter variation of the first shoulder; and the threshold value is positively correlated with the diameter variation of the first shoulder.

3. The shaft heat treatment method according to claim 1, wherein: before the step of controlling the inductor to move to a second position and controlling a spraying ring to move to a third position based on the pre-heating being completed, the shaft heat treatment method further comprises: controlling the inductor to move to a fourth position based on the pre-heating being completed; wherein the fourth position is below the second position; and in the state that the inductor is at the fourth position, the inductor covers the first center; controlling the inductor to heat at a third temperature at the fourth position until a first heating time is reached.

4. The shaft heat treatment method according to claim 3, wherein: the third temperature is less than the second temperature.

5. The shaft heat treatment method according to claim 3, wherein: the shaft heat treatment method further comprises: controlling the first center to rotate at a second rotating speed based on the inductor being at the second position and the spraying ring being at the third position.

6. The shaft heat treatment method according to claim 5, wherein: the second rotating speed is greater than the first rotating speed.

7. The method of claim 6, wherein: a difference between the second rotational speed and the first rotational speed is positively correlated with the third temperature.

8. The method of claim 1, wherein: a distance between the first shoulder and the second position is a first distance; and a duration of the pre-heating is positively correlated with the first distance.

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