Intermediate-frequency heating control device for engine connecting rod forgings

Abstract

The invention discloses a medium-frequency heating control device for engine connecting rod forgings, and relates to the technical field of medium-frequency heating. The medium-frequency heating control device for the engine connecting rod forgings comprises a data processing unit; the skin effect strength of a high-temperature area of the connecting rod forged piece is weakened by reducing the output frequency, the surface heat input rate is directly reduced, so that local oxidation reaction is restrained, current output is synchronously improved through a current compensation mechanism at the moment that the frequency is reduced, and it is ensured that the total power of a heating system is stable and unchanged; however, current compensation timely supplements energy loss caused by frequency change, so that the overall energy supply of the intermediate frequency heating control device is kept in a balanced state. The problems that the surface of the connecting rod forge piece is concave inwards, marks are fuzzy and internal stress deforms due to a fixed power mode of an intermediate frequency heating control device are fundamentally solved.

Description

Technical Field

[0001] This invention relates to the field of medium-frequency heating technology, and in particular to a medium-frequency heating control device for engine connecting rod forgings. Background Technology

[0002] As a core component of the engine, the connecting rod is often heated using medium-frequency heating, which involves heating the surface of the connecting rod forging to conduct heat into the interior of the forging.

[0003] In existing technologies, if the output power of a medium-frequency heating system is fixed, the inconsistent or uneven distribution of metal elements on the surface of the connecting rod forging will lead to differences in the heat absorption and conduction efficiency of different areas of the forging. When the temperature in a local area is too high, it is very easy to cause excessive metal oxidation, which manifests as defects such as concavity, blurred markings, and uneven edges on the surface of the forging.

[0004] In other words, the existing medium-frequency fixed-power heating mode cannot adjust the heating according to the real-time temperature changes on the surface of the connecting rod forging, making it difficult to control the oxidation phenomenon and thus affecting the forming quality of the connecting rod forging. Summary of the Invention

[0005] The purpose of this invention is to solve the problem that the existing medium-frequency fixed-power heating mode cannot adjust the heating according to the real-time temperature changes of the connecting rod forging surface, resulting in difficulty in controlling oxidation and thus affecting the forming quality of the connecting rod forging.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a medium-frequency heating control device for engine connecting rod forgings, comprising a temperature monitoring unit disposed outside the heating coil, and a power adjustment unit connected to the heating coil.

[0007] The temperature monitoring unit, which is connected to the data processing unit, is configured to collect the surface temperature data of the connecting rod forging in real time and transmit it to the data processing unit.

[0008] The data processing unit is configured to receive temperature data and determine whether a preset oxidation temperature threshold has been reached. When the oxidation threshold is reached, a coordinated control signal containing a frequency down-adjustment command and a current up-adjustment command is generated.

[0009] The power regulation unit, which is communicatively connected to the data processing unit, is configured to respond to the control signal by reducing the output frequency to suppress heat input and increasing the current output to maintain a constant total power.

[0010] In the above technical solution, during use, the temperature monitoring unit collects real-time surface temperature data of the connecting rod forging and transmits it to the data processing unit via a communication link. The data processing unit compares the received temperature data, i.e., the real-time temperature value, with a preset oxidation temperature threshold (e.g., 80%-95% of the phase transformation temperature of the metal material). When the temperature of a certain area of ​​the connecting rod forging reaches or exceeds the threshold (high-temperature area), a coordinated control signal containing a frequency reduction command and a current increase command is generated. After receiving this signal, the power adjustment unit immediately reduces the output frequency of the intermediate frequency heating system to reduce the heat input rate in the high-temperature area (suppressing surface overheating caused by the skin effect), and simultaneously increases the current output according to the formula power = voltage × current to ensure that the total power remains constant. Thus, the surface oxidation rate is suppressed due to the temperature reduction, while the overall heating energy remains unchanged to avoid insufficient heating in other areas.

[0011] The beneficial effects of this invention are:

[0012] This invention reduces the skin effect intensity in the high-temperature region of the connecting rod forging by lowering the output frequency, directly reducing the surface heat input rate and thus suppressing local oxidation reactions. Simultaneously, a current compensation mechanism synchronously increases the current output at the instant the frequency decreases, ensuring the total power of the heating system remains stable. While the frequency reduction decreases local heat input, the current compensation promptly replenishes the energy loss caused by the frequency change, maintaining a balanced energy supply for the overall medium-frequency heating control device. This fundamentally solves the problems of surface concavity, blurred markings, and internal stress deformation of the connecting rod forging caused by the fixed power mode of the medium-frequency heating control device.

[0013] Furthermore, in this embodiment of the invention, the total power of the power adjustment unit is kept constant at the rated power of the medium-frequency heating control device, and the formula for calculating the total power is:

[0014] Total power = Output current × Output voltage, where:

[0015] The output current is the effective value of the alternating current output by the power regulation unit.

[0016] The output voltage is the effective value of the voltage output by the power regulation unit.

[0017] Furthermore, in this embodiment of the invention, the preset oxidation threshold value ranges from 80% to 95% of the phase transformation temperature of the metallic material.

[0018] Furthermore, in this embodiment of the invention, the data processing unit achieves communication connection through an industrial bus network, thereby realizing signal transmission. The industrial bus network is one of EtherCAT bus, PROFINET bus, or RS485 bus.

[0019] Furthermore, in this embodiment of the invention, the temperature monitoring unit is a far-infrared camera, whose monitoring angle covers the heating area of ​​the connecting rod forging.

[0020] Furthermore, in this embodiment of the invention, the spatial distribution of the number of turns of the heating coil is from dense to sparse, corresponding to a gradient distribution of electromagnetic induction intensity from strong to weak in different regions of the connecting rod forging.

[0021] Furthermore, in this embodiment of the invention, the heating coil comprises multiple connected coil windings, which are disposed within a nested telescopic cylinder, with the front and rear ends of the telescopic cylinder fixedly connected to the front and rear ends of each coil winding segment.

[0022] The telescopic cylinder is equipped with a sealed pressure chamber, which is connected to an external air source. By controlling the air pressure in the pressure chamber, the telescopic cylinder is driven to extend and retract axially, thereby adjusting the density of the coil windings and increasing or decreasing the spacing between the coil winding turns, thus changing the density of the magnetic field distribution.

[0023] Another beneficial effect of this invention is:

[0024] The axial movement of the telescopic cylinder is directly driven by the air pressure difference within the sealed pressure chamber, without the need for electrical components or magnetic elements. In a medium-frequency heating strong magnetic field environment, the air pressure drive will not experience fluctuations in driving force due to changes in the magnetic field (unlike electromagnetic drives which may experience torque attenuation due to magnetic field interference), ensuring the stability of the coil turn spacing adjustment and maintaining the consistency of the magnetic field distribution.

[0025] The telescopic cylinder structure enables dynamic adjustment of the heating coil, allowing its magnetic field distribution to change the spatial distribution of electromagnetic induction intensity in real time according to the actual heating needs of different areas of the connecting rod forging (such as geometric differences and temperature variations in the large end, small end, and rod body). This weakens the magnetic field intensity in high-temperature areas to reduce heat input and suppress oxidation, while strengthening the magnetic field intensity in low-temperature areas to improve heating efficiency, thus achieving adaptive matching of the temperature field during the heating process. This adjustment method avoids the problems of local overheating or underheating caused by a fixed magnetic field distribution, ensuring temperature uniformity in all areas of the forging. Simultaneously, it forms a closed-loop control system with the temperature monitoring system, accurately addressing differences in heat absorption caused by uneven distribution of metal elements and material fluctuations. This improves the forging quality while effectively reducing the difficulty of subsequent processing and the risk of oxidation defects.

[0026] Furthermore, in this embodiment of the invention, the telescopic cylinder is made of a high-temperature resistant insulating material, which includes mica sheet material.

[0027] Furthermore, in this embodiment of the invention, the inlet and outlet of the pressure chamber are connected to an external air source, through which circulating air is supplied to the pressure chamber to remove the heat generated by the heating coil and maintain the stability of the inductance parameters of the heating coil.

[0028] Furthermore, in this embodiment of the invention, the external air source is communicatively connected to the data processing unit. The data processing unit generates an air pressure adjustment command based on the surface temperature data of the connecting rod forging, and controls the external air source to adjust the air pressure delivered to the pressure chamber, thereby changing the spatial distribution of the number of turns of the heating coil and dynamically adjusting the electromagnetic induction intensity distribution in different areas of the connecting rod forging. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the medium-frequency heating control device for engine connecting rod forgings according to an embodiment of the present invention.

[0030] Figure 2 This is a three-dimensional schematic diagram of the telescopic cylinder according to an embodiment of the present invention.

[0031] Figure 3 This is a schematic diagram of the side structure of the telescopic cylinder according to an embodiment of the present invention.

[0032] 1. Heating coil; 2. Temperature monitoring unit; 3. Power adjustment unit; 4. Telescopic cylinder; 5. Pressure chamber. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the present invention clear and complete, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only some, not all, embodiments of the present invention, and are merely illustrative of the embodiments of the present invention. They are not intended to limit the embodiments of the present invention. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] In the description of this invention, it should be noted that the terms "center," "middle," "upper," "lower," "left," "right," "inner," "outer," "top," "bottom," "side," "vertical," and "horizontal," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "a," "first," "second," "third," "fourth," "fifth," and "sixth" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0035] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0036] For purposes of simplicity and illustration, the principles of the embodiments are described primarily by way of example. In the following description, numerous specific details are set forth to provide a thorough understanding of the embodiments. However, it will be apparent to those skilled in the art that these embodiments may not be limited to these specific details in practice. In some instances, the structures of well-known induction heating control devices applied to engine connecting rod forgings have not been described in detail to avoid unnecessarily obscuring these embodiments. Furthermore, all embodiments can be used in combination with each other.

[0037] As a core component of the engine, the connecting rod is subject to excessive oxidation due to the inability of existing medium-frequency heating technology to dynamically adjust parameters based on the surface temperature of the connecting rod forging, caused by its fixed power mode. This invention addresses this issue by installing a far-infrared camera outside the medium-frequency heating coil to monitor the temperature in real time. When the temperature in a certain area reaches a preset oxidation threshold, the data processing unit of the data network system sends a command to the medium-frequency heating system to reduce the output frequency, thereby decreasing heat input and suppressing oxidation. Simultaneously, based on the formula power = voltage × current, the current output is increased to maintain stable total power and ensure uniform heating. Furthermore, the density of the medium-frequency heating coil is adjusted through a telescopic cylinder structure, combined with air circulation cooling in a pressure chamber, achieving the dual goals of oxidation control and uniform heating.

[0038] Example 1:

[0039] It should be noted that the accompanying drawings are part of the content of the instruction manual. The structural shapes, connections, fits, and positional relationships that can be clearly seen in the accompanying drawings should all be understood as part of the content of the instruction manual.

[0040] A medium-frequency heating control device for engine connecting rod forgings, such as Figure 1 As shown, it includes a temperature monitoring unit 2 located outside the heating coil 1, and a power adjustment unit 3 connected to the heating coil 1.

[0041] Temperature monitoring unit 2 can use a far-infrared thermal imager (such as the FLIR A65 series) to achieve non-contact temperature measurement, with a frame rate (≥50Hz) and temperature resolution (≤1℃) that meet the requirements for real-time monitoring. The monitoring field of view coverage is achieved through optimized installation angle (e.g., the camera axis forms a 45° angle with the plane of heating coil 1) and a wide-angle lens (field of view ≥60°) to ensure monitoring without blind spots.

[0042] The power regulation unit 3 can use an IGBT frequency converter module (such as Infineon FF600R12ME4) to achieve synchronous regulation of frequency and current.

[0043] Temperature monitoring unit 2, which is connected to the data processing unit, is configured to collect real-time surface temperature data of the connecting rod forging and transmit it to the data processing unit.

[0044] The data processing unit is configured to receive temperature data and determine whether a preset oxidation temperature threshold has been reached. When the oxidation threshold is reached, a coordinated control signal containing frequency down-adjustment and current up-adjustment instructions is generated.

[0045] The data processing unit can be a PLC (such as Siemens S7-1200) or an embedded controller (such as ARM Cortex-M7). The oxidation threshold calibration method can refer to the experimental data of phase transformation temperature in metal heat treatment technology.

[0046] The power regulation unit 3, which is connected in communication with the data processing unit, is configured to respond to the control signal by reducing the output frequency to suppress heat input and increasing the current output to maintain a constant total power.

[0047] Detailed Implementation: A far-infrared thermal imager collects real-time surface temperature data of the connecting rod forging and transmits it to the data processing unit via a communication link. The data processing unit compares the received temperature data, i.e., the real-time temperature value, with a preset oxidation temperature threshold (e.g., 80%-95% of the phase transformation temperature of the metal material). When the temperature of a certain area of ​​the connecting rod forging reaches or exceeds the threshold (high-temperature area), a coordinated control signal containing frequency reduction and current increase commands is generated. Upon receiving this signal, the power adjustment unit 3 immediately reduces the output frequency of the intermediate frequency heating system to reduce the heat input rate in the high-temperature area (suppressing surface overheating caused by the skin effect), while simultaneously increasing the current output according to the formula power = voltage × current to ensure that the total power remains constant. Thus, the surface oxidation rate is suppressed due to the temperature reduction, while the overall heating energy remains unchanged to avoid insufficient heating in other areas.

[0048] If the temperature drops below the preset oxidation temperature threshold, the initial frequency and current parameters will be restored.

[0049] Medium-frequency heating relies on electromagnetic induction to generate eddy currents on the surface of the forging, and the frequency directly affects the skin effect depth. When the frequency decreases (for example, from 1000kHz to 500kHz), the skin effect weakens, the current penetration depth increases (heat distribution tends to be more towards the interior of the connecting rod forging), and the surface heat input rate decreases, thereby slowing down the oxidation reaction in the high-temperature region.

[0050] In power regulation unit 3, the total power is kept constant using the formula Total Power = Voltage × Current. A decrease in frequency leads to an increase in equivalent impedance; if the current remains constant, the power will decrease. In other words, if only the frequency is reduced without adjusting other parameters, the power will decrease due to the reduced heat input rate, resulting in uneven heating of the forging.

[0051] Therefore, the current value needs to be increased to ensure stable total power. Assuming the initial state is voltage = 100V, current = 50A, and frequency = 1000kHz, if the frequency drops to 500kHz causing the impedance to double, the current needs to be increased to 70.7A (≈50A×√2) to keep the total power = 100V×70.7A≈7kW constant.

[0052] The advantages of this invention lie in its ability to reduce the skin effect intensity in the high-temperature region of the connecting rod forging by lowering the output frequency, thereby directly reducing the surface heat input rate and suppressing local oxidation reactions. Simultaneously, a current compensation mechanism synchronously increases the current output at the instant the frequency decreases, ensuring the total power of the heating system remains stable. While the frequency reduction decreases local heat input, the current compensation promptly replenishes the energy loss caused by the frequency change, maintaining a balanced overall energy supply for the medium-frequency heating control device. This fundamentally solves the problems of surface concavity, blurred markings, and internal stress deformation in connecting rod forgings caused by the fixed power mode of the medium-frequency heating control device.

[0053] Specifically, the total power of the power adjustment unit 3 is kept constant at the rated power of the medium-frequency heating control device, and the formula for calculating the total power is:

[0054] Total power = Output current × Output voltage, where:

[0055] The output current is the effective value of the alternating current output by the power regulation unit 3.

[0056] The output voltage is the effective value of the voltage output by the power regulation unit 3.

[0057] Power regulation unit 3 ensures energy balance during the heating process by maintaining a constant total power (total power = output current × output voltage). When the data processing unit triggers a frequency reduction command, power regulation unit 3 automatically calculates the target current value based on the preset rated power value (e.g., initial P = 1000V × 50A = 50kW; when the frequency decreases to 50%, the current needs to be increased to approximately 70.7A to maintain P ≈ 70.7A × 707V = 50kW). The current and voltage in this formula are both effective values ​​of alternating signals, and their measurement method conforms to the IEC 61000-4-7 standard. Real-time acquisition is achieved through Hall effect sensors and voltage transformers to ensure the accuracy of power closed-loop control. Those skilled in the art can use pulse width modulation technology (such as SPWM) of IGBT modules to achieve coordinated regulation of current and frequency, thereby eliminating heating unevenness caused by power fluctuations.

[0058] Specifically, the preset oxidation threshold value ranges from 80% to 95% of the phase transformation temperature of the metallic material.

[0059] The oxidation threshold is set at 80%-95% of the phase transformation temperature. The technical basis for this is that the metal oxidation rate increases exponentially when it approaches the phase transformation temperature (refer to the "Metal Heat Treatment Handbook"). Controlling this threshold below the phase transformation critical point can effectively suppress the oxidation reaction.

[0060] Specifically, the data processing unit achieves communication connection through an industrial bus network to realize signal transmission. The industrial bus network is one of EtherCAT bus, PROFINET bus or RS485 bus.

[0061] Specifically, the spatial distribution of the number of turns of the heating coil 1 is from dense to sparse, and the electromagnetic induction intensity of different areas of the connecting rod forging shows a gradient distribution from strong to weak.

[0062] The gradient distribution design of heating coil 1 from dense to sparse is based on the positive correlation between electromagnetic induction intensity and turns density. The dense region (e.g., the first 20 turns / cm) generates a high-intensity magnetic field, causing the surface of the connecting rod forging to heat up rapidly, while the sparse region (the latter 10 turns / cm) weakens the magnetic field to facilitate heat conduction to the interior.

[0063] More specifically, such as Figure 2 , Figure 3 As shown, the heating coil 1 includes multiple connected coil windings, which are housed within a nested telescopic cylinder 4. The front and rear ends of the telescopic cylinder 4 are fixedly connected to the front and rear ends of each coil winding segment.

[0064] The telescopic cylinder 4 is equipped with a sealed pressure chamber 5, which is connected to an external air source. By controlling the air pressure in the pressure chamber 5, the telescopic cylinder 4 is driven to extend and retract axially, thereby adjusting the density of the coil windings and increasing or decreasing the spacing between the coil winding turns, thus changing the density of the magnetic field distribution.

[0065] The axial movement of the telescopic cylinder 4 is directly driven by the air pressure difference within the sealed pressure chamber 5, without the need for electrical components or magnetic elements. In a medium-frequency heating strong magnetic field environment, the air pressure drive will not cause fluctuations in driving force due to changes in the magnetic field (as electromagnetic drives may experience torque attenuation due to magnetic field interference), ensuring the stability of the coil turn spacing adjustment and maintaining the consistency of the magnetic field distribution.

[0066] Another advantage of this invention is that the telescopic cylinder 4 structure enables dynamic adjustment of the heating coil 1, allowing its magnetic field distribution to change the spatial distribution of electromagnetic induction intensity in real time according to the actual heating needs of different areas of the connecting rod forging (such as the geometric differences and temperature changes of the large end, small end, and rod body). This weakens the magnetic field intensity in high-temperature areas to reduce heat input and suppress oxidation, while strengthening the magnetic field intensity in low-temperature areas to improve heating efficiency, thus achieving adaptive matching of the temperature field during the heating process. This adjustment method avoids the problem of local overheating or underheating caused by a fixed magnetic field distribution, ensuring the temperature uniformity of each area of ​​the forging. Simultaneously, it forms a closed-loop control with the temperature monitoring system, accurately addressing differences in heat absorption caused by uneven distribution of metal elements and material fluctuations. This improves the forming quality of the forging while effectively reducing the difficulty of subsequent processing and the risk of oxidation defects.

[0067] Those skilled in the art can set the target air pressure value based on the physical relationship between the number of coil turns and the magnetic field to achieve regional control of the heating intensity without requiring creative effort.

[0068] More specifically, the telescopic cylinder 4 is made of high-temperature resistant insulating material, including mica sheet material. The telescopic cylinder 4 made of mica sheet can withstand temperatures ≥1000℃ and has a dielectric strength ≥20kV / mm, ensuring insulation safety.

[0069] More specifically, the inlet and outlet of the pressure chamber 5 are connected to an external air source, through which circulating air is supplied to the pressure chamber 5 to remove the heat generated by the heating coil 1 and maintain the stability of the inductance parameters of the heating coil 1.

[0070] The compressed air required for pneumatic drive also has a heat dissipation function during the circulation process, avoiding the structural complexity of designing a separate cooling channel.

[0071] More specifically, the external air source is connected to the data processing unit. The data processing unit generates an air pressure adjustment command based on the surface temperature data of the connecting rod forging, controls the external air source to adjust the air pressure delivered to the pressure chamber 5, thereby changing the spatial distribution of the number of turns of the heating coil 1 and dynamically adjusting the electromagnetic induction intensity distribution in different areas of the connecting rod forging.

[0072] By integrating temperature monitoring, data processing, and pneumatic drive into a single medium-frequency heating control device, the barrier of independent operation of each module in traditional heating equipment is broken, and deep coupling of heating parameters (magnetic field strength) and temperature feedback is achieved, providing technical support for intelligent forging processes.

[0073] Although the illustrative specific embodiments of the present invention have been described above to enable those skilled in the art to understand the invention, the invention is not limited to the scope of the specific embodiments. For those skilled in the art, all inventions utilizing the concept of the present invention are protected as long as various variations are within the spirit and scope of the invention as defined and determined by the appended claims.

Claims

1. A medium-frequency heating control device for engine connecting rod forgings, comprising a temperature monitoring unit disposed outside a heating coil, and a power adjustment unit connected to the heating coil; The temperature monitoring unit, which is communicatively connected to the data processing unit, is configured to collect real-time surface temperature data of the connecting rod forging and transmit it to the data processing unit. Its features are, The data processing unit is configured to receive temperature data and determine whether a preset oxidation temperature threshold has been reached. When the oxidation threshold is reached, a coordinated control signal containing a frequency down-adjustment command and a current up-adjustment command is generated. The power regulation unit, which is communicatively connected to the data processing unit, is configured to respond to the control signal by reducing the output frequency to suppress heat input and increasing the current output to maintain a constant total power.

2. The medium-frequency heating control device for engine connecting rod forgings according to claim 1, characterized in that, The total power of the power regulation unit is constant at the rated power of the medium-frequency heating control device, and the formula for calculating the total power is: Total power = Output current × Output voltage, where: The output current is the effective value of the alternating current output by the power regulation unit; The output voltage is the effective value of the voltage output by the power regulation unit.

3. The medium-frequency heating control device for engine connecting rod forgings according to claim 1, characterized in that, The preset oxidation threshold value ranges from 80% to 95% of the phase transformation temperature of the metallic material.

4. The medium-frequency heating control device for engine connecting rod forgings according to claim 1, characterized in that, The data processing unit achieves communication connection through an industrial bus network, thereby realizing signal transmission. The industrial bus network is one of EtherCAT bus, PROFINET bus or RS485 bus.

5. The medium-frequency heating control device for engine connecting rod forgings according to claim 1, characterized in that, The temperature monitoring unit is a far-infrared camera, whose monitoring angle covers the heating area of ​​the connecting rod forging.

6. The medium-frequency heating control device for engine connecting rod forgings according to claim 1, characterized in that, The spatial distribution of the number of turns of the heating coil decreases from dense to sparse, corresponding to a gradient distribution of electromagnetic induction intensity from strong to weak in different regions of the connecting rod forging.

7. The medium-frequency heating control device for engine connecting rod forgings according to claim 6, characterized in that, The heating coil comprises multiple connected coil windings, which are housed within a nested telescopic cylinder. The front and rear ends of the telescopic cylinder are fixedly connected to the front and rear ends of each coil winding segment. The telescopic cylinder is equipped with a sealed pressure chamber, which is connected to an external air source. By controlling the air pressure in the pressure chamber, the telescopic cylinder is driven to extend and retract axially, thereby adjusting the density of the coil windings and increasing or decreasing the spacing between the coil winding turns, thus changing the density of the magnetic field distribution.

8. The medium-frequency heating control device for engine connecting rod forgings according to claim 7, characterized in that, The telescopic cylinder is made of high-temperature resistant insulating material, which includes mica sheet material.

9. The engine connecting rod forging medium-frequency heating control device according to claim 7, characterized in that, The inlet and outlet of the pressure chamber are connected to an external air source. Circulating air is supplied to the pressure chamber through the external air source to remove the heat generated by the heating coil and maintain the stability of the heating coil inductance parameters.

10. The medium-frequency heating control device for engine connecting rod forgings according to claim 7, characterized in that, The external air source is communicatively connected to the data processing unit. The data processing unit generates an air pressure adjustment command based on the surface temperature data of the connecting rod forging, controls the external air source to adjust the air pressure delivered to the pressure chamber, thereby changing the spatial distribution of the number of turns of the heating coil and dynamically adjusting the electromagnetic induction intensity distribution in different areas of the connecting rod forging.

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