Intelligent temperature control heat treatment method for alloy forging machining

Abstract

The present application relates to the technical field of forging heat treatment, and in particular to an intelligent temperature control heat treatment method for alloy forging processing. The present application obtains the geometric characteristic parameters and physical attribute parameters of the target forging, calculates the equivalent heat capacity and the core-surface temperature difference theoretical value, and provides differentiated temperature control boundaries for target forgings of different specifications and materials. Combined with the real-time collected surface temperature data set and airflow temperature data set, the heating power set value, the circulating air speed set value and the hearth pressure set value are dynamically generated, so that the temperature control parameters are matched with the actual thermal state of the target forging, and the temperature control precision is improved.

Description

Technical Field

[0001] This invention relates to the field of forging heat treatment technology, and specifically to an intelligent temperature-controlled heat treatment method for alloy forgings. Background Technology

[0002] Alloy forgings are widely used in aerospace, energy equipment, and rail transportation, and their final mechanical properties and microstructure are highly dependent on the precision and uniformity of the heat treatment process. The core of heat treatment lies in the precise control of the temperature field.

[0003] Existing technology, such as Chinese invention patent publication number CN120138301A, discloses a heat treatment device and method for aluminum alloy pistons. It obtains the workpiece weight through a weighing component and calculates the gas volume inside the furnace by combining this with temperature sensor data. This allows for the regulation of the temperature control and circulation components, solving the problem of uneven heat distribution inside the furnace caused by gas expansion.

[0004] However, after in-depth analysis, the existing technologies still have the following shortcomings: Although they can adjust the furnace gas volume based on the workpiece weight, they do not fully consider the coupled effects of the forging's geometric characteristics, physical properties, and gas flow temperature distribution, resulting in poor temperature uniformity control. Forgings of different shapes and sizes will exhibit significant differences in their internal heat conduction paths and rates under the same external thermal environment. Furthermore, they fail to achieve multi-variable dynamic optimization of heating power, circulating air velocity, and furnace pressure, making it difficult to achieve dynamic temperature equilibrium. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and solve the problems of low uniformity of internal temperature field of alloy forgings due to the lack of comprehensive consideration of the forging body temperature, geometric characteristics and airflow state in the furnace, as well as the failure to achieve multi-variable collaborative dynamic optimization of heating power, circulating wind speed and furnace pressure.

[0006] The technical solution adopted by the present invention to solve its technical problem is: an intelligent temperature-controlled heat treatment method for alloy forging processing, including the following steps: S1, obtaining the geometric feature parameters and physical property parameters of the target forging, and calculating its equivalent heat capacity and the theoretical value of the core-surface temperature difference accordingly.

[0007] S2. Real-time acquisition of surface temperature dataset of the target forging and temperature dataset of circulating airflow in the furnace.

[0008] S3. Calculate the average surface temperature and the temperature difference between the upper and lower surfaces based on the surface temperature dataset, and calculate the inlet and outlet airflow temperature difference based on the airflow temperature dataset.

[0009] S4. Based on the equivalent heat capacity, the theoretical value of the core-surface temperature difference, the average surface temperature, the temperature difference between the upper and lower surfaces, and the temperature difference between the inlet and outlet airflow, dynamically generate and output a set of control parameters; the control parameters include at least the heating power setting value, the circulating wind speed setting value, and the furnace pressure setting value.

[0010] S5. Based on the control parameters, synchronously adjust the heater output power, circulating fan speed, and pressure regulating device of the heat treatment furnace.

[0011] S6. Repeat steps S2 to S5 until the average surface temperature reaches the preset temperature and the temperature difference between the upper and lower surfaces is less than the theoretical value of the core surface temperature difference. Then, control the heat treatment process to enter the heat preservation stage.

[0012] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention obtains the geometric feature parameters and physical property parameters of the target forging, calculates the equivalent heat capacity and the theoretical value of the core-surface temperature difference, and provides differentiated temperature control boundaries for target forgings of different specifications and materials; combined with the real-time collected surface temperature dataset and airflow temperature dataset, it dynamically generates heating power setting value, circulating wind speed setting value and furnace pressure setting value, so that the temperature control parameters match the actual thermal state of the target forging and improve the temperature control accuracy.

[0013] 2. Based on the deviation of the average surface temperature, the temperature difference between the upper and lower surfaces and the theoretical value of the core surface temperature difference, the present invention simultaneously adjusts the heating power and the circulating wind speed; at the same time, it dynamically adjusts the furnace pressure according to the temperature difference of the inlet and outlet airflow and the equivalent heat capacity, so as to realize the linkage control of heating, circulation and pressure, and improve the uniformity of the overall temperature field of the target forging.

[0014] 3. This invention establishes a standard furnace loading method, optimizes the placement and spacing of target forgings, and ensures smooth airflow. Based on this, non-contact temperature measurement points are placed on the upper and lower surfaces and sides of the furnace, corresponding to the furnace chamber locations, and gas temperature measurement points are placed along the critical airflow paths. This provides comprehensive and accurate temperature monitoring data, laying the foundation for subsequent temperature control, and also increases the process adaptability to forgings of different shapes and loading volumes. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the temperature-controlled heat treatment method of the present invention.

[0017] Figure 2 This is a flowchart illustrating the standard furnace loading method for this invention.

[0018] Figure 3 This is a schematic diagram illustrating the process of determining the setpoint for the circulating wind speed in this invention.

[0019] Figure 4 This is a schematic diagram illustrating the process for determining the furnace pressure setpoint in this invention. Detailed Implementation

[0020] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention. Furthermore, it should be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale.

[0021] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the invention or its application or use. Techniques, methods, and apparatus known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and apparatus should be considered part of the specification.

[0022] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0024] The following description, in conjunction with the accompanying drawings, details the specific scheme of the intelligent temperature-controlled heat treatment method for alloy forgings provided by this invention.

[0025] Please see Figure 1 The flowchart of an intelligent temperature-controlled heat treatment method for alloy forging provided by the present invention is shown, which specifically includes the following steps: Step S1: Obtain the geometric feature parameters and physical property parameters of the target forging, and calculate its equivalent heat capacity and the theoretical value of the core-surface temperature difference accordingly.

[0026] Geometric features determine the heat exchange area and path between the forging and the airflow inside the furnace, directly affecting the uniformity of heat transfer. Physical properties, on the other hand, reflect the material's ability to store and conduct heat, and are key to calculating heat demand and temperature difference.

[0027] Specifically, the physical property parameters include the material's density, specific heat capacity, and thermal conductivity. The geometric feature parameters include the target forging's thickness, total surface area, total volume, and cross-sectional feature dimensions.

[0028] Among them, the characteristic dimension of the cross section refers to the maximum projected cross section dimension perpendicular to the thickness direction. For example, for a rectangular cross section forging, it is the larger value between the width and the length.

[0029] Geometric feature parameters can be obtained by directly measuring the target forging, reading its 3D CAD model data, or extracting it from process drawings.

[0030] Physical property parameters can be directly obtained from material standards or technical data sheets provided by material suppliers. If new materials are involved or parameters are incomplete, they can be determined experimentally, such as by differential scanning calorimetry to measure specific heat capacity or laser scintillation to measure thermal conductivity. These measurement methods are existing technologies and will not be described in detail in this invention.

[0031] Furthermore, based on geometric characteristic parameters and physical property parameters, the equivalent heat capacity and theoretical value of the core-surface temperature difference of the target forging are calculated.

[0032] Step S10: Multiply the density of the material by its specific heat capacity to obtain the amount of heat required to raise the temperature per unit volume of the material by one unit.

[0033] Multiplying this heat by the total volume yields the total heat required to raise the temperature of the target forging by a unit, i.e., the equivalent heat capacity.

[0034] Step S11: Select the maximum thickness of the target forging as the heat transfer path length. This is because the core at the maximum thickness heats up the slowest and has the largest temperature difference. Simultaneously, the thermal diffusivity is obtained by dividing the thermal conductivity by the product of density and specific heat capacity.

[0035] Then, the initial temperature, target temperature, and planned duration of the heating stage of the heat treatment process are obtained. The heating rate is then calculated by performing a ratio based on the difference between the target temperature and the initial temperature and the planned duration.

[0036] The initial temperature is generally room temperature or the furnace loading temperature. The heating stage refers to the process in the heat treatment process from the initial temperature until the target temperature is reached. The target temperature is the final homogenization temperature required by the process, usually determined based on the phase transformation point and tempering temperature window of the alloy material.

[0037] For example, the austenitizing temperature of 42CrMo alloy structural steel is usually in the range of 850±10℃, and 850℃ can be used as an example in this invention; for Inconel 718 high-temperature alloy, the solution temperature window is 950-980℃, and 960℃ can be used as an example in this invention.

[0038] The planned duration is the total heating time set by the process, which can be derived by the maximum allowable heating rate of the material used for the target forging, i.e., by dividing the difference between the target temperature and the initial temperature by the maximum allowable heating rate.

[0039] The maximum permissible heating rate can be determined based on industry standards or recommendations from material suppliers. For example, for Inconel 718 high-temperature alloy, the maximum permissible heating rate is 3-6°C / min; for 42CrMo alloy structural steel, the maximum permissible heating rate is 8-15°C / min.

[0040] It is important to note that the planned duration is determined in advance during the heat treatment process preparation stage and remains fixed throughout the heating phase.

[0041] Finally, by substituting the heating rate, heat transfer path length, and thermal diffusivity into the theoretical calculation formula for the core-surface temperature difference, the temperature difference between the core and surface of the target forging is obtained, i.e., the theoretical value of the core-surface temperature difference. This theoretical value provides a safety boundary for temperature control.

[0042] The theoretical calculation formulas used here are derived from the one-dimensional unsteady-state heat conduction approximation solution, which is based on the analytical approximation of the Fourier heat conduction equation at a constant heating rate, and its typical form is as follows: .

[0043] in, The theoretical value of the core temperature difference ( ); For the heating rate ( ); For the maximum thickness ( ); Thermal diffusivity ( ).

[0044] Step S2: Real-time acquisition of surface temperature data of the target forging and temperature data of the circulating airflow inside the furnace. This enables precise sensing of the internal temperature field of the target forging.

[0045] Step S20: Determine the standard loading method for the target forging in the furnace based on the geometric characteristic parameters and the furnace chamber dimensions of the heat treatment furnace.

[0046] This is because different charging methods will change the relative positions of the target forging surface and the furnace wall, as well as the airflow, thereby affecting the symmetry of the temperature field and the uniformity of airflow, and thus directly affecting the accuracy of temperature control.

[0047] Please see Figure 2 The standard furnace loading method is determined as follows: the internal volume of the furnace is calculated based on its internal length, width, and height. Simultaneously, the projected area of ​​each outer surface of the target forging can be calculated by extracting from a 3D CAD model or reconstructing from a laser scanning point cloud, and then the outer surface with the largest area in the target forging is identified as the main bearing surface.

[0048] When loading the target forging into the furnace, the main bearing surface should face downwards and be parallel to the bottom of the furnace to ensure stable placement. At this time, the main bearing surface is the lower surface, the outer surface that actually faces upwards is the upper surface, and the remaining exposed surfaces are the side surfaces.

[0049] Then, the ratio of the total volume of the target forging to the internal volume of the furnace is calculated. If the ratio is less than or equal to the preset process threshold, the target forging is placed in the center of the furnace bottom surface to reduce the adverse effects of furnace wall effects such as uneven radiation and airflow stagnation at the edges on the temperature uniformity of the target forging.

[0050] If the ratio is greater than the preset process threshold, multiple target forgings are evenly arranged on the bottom surface of the furnace at a preset safety distance. This avoids the formation of airflow blockage zones due to excessively small distances between target forgings or between target forgings and the furnace wall, ensuring that the circulating airflow can effectively flow over the surface of all target forgings.

[0051] The preset process threshold takes into account the uniformity requirements of airflow inside the furnace, and is usually set to 0.1 to 0.3. For example, for precision alloy forgings that require high uniformity, a threshold of 0.15 can be used, meaning that the volume of a single forging does not exceed 15% of the internal volume of the furnace, in order to avoid excessive obstruction of airflow.

[0052] The predetermined safety clearance must ensure that airflow can pass smoothly through the gap of the target forging. Typically, it is taken as 0.5 to 1.5 times the maximum thickness of the target forging; in this invention, it can be 0.8 times the maximum thickness of the target forging. If the target forging is a high thermal conductivity material, the predetermined safety clearance can be reduced to 0.6 times the maximum thickness of the target forging; if the target forging is a low thermal conductivity high-temperature alloy, it is increased to 1.2 times the maximum thickness of the target forging to ensure that the airflow fully penetrates the gap.

[0053] Furthermore, the orientation of the target forging needs to be adjusted again so that its projected length on the bottom surface of the furnace is parallel to the dominant flow direction of the circulating airflow inside the furnace. This minimizes airflow resistance, improves heat transfer uniformity, and reduces flow dead zones. If the long axis of the target forging is perpendicular to the airflow, a wake vortex will be formed, creating a low-temperature zone on the leeward side.

[0054] Among them, the projection length direction refers to the projection vector of the target forging on the horizontal plane along its longest extension direction, which can be obtained by extracting the principal axis direction from the bottom contour point cloud of the target forging through principal component analysis.

[0055] The dominant flow direction of the circulating airflow inside the furnace is usually determined by the location of the blower outlet and the furnace structure. The average main direction can be taken as the dominant flow direction after measuring the airflow vector field with a hot-wire anemometer under no-load conditions.

[0056] Step S21: After the standard furnace loading method is determined, non-contact temperature measurement points are set at the top and bottom positions of the furnace corresponding to the upper and lower surfaces, and at the furnace side wall position directly opposite at least one side surface.

[0057] Meanwhile, gas temperature measurement points for circulating airflow are set up at key locations inside the furnace, such as the circulating fan outlet pipe, return air pipe, near the heating element, above the target forging, downstream of the fan outlet, upstream of the return air inlet, and at both ends of the transverse centerline of the furnace center height.

[0058] All non-contact temperature measurement points and gas temperature measurement points synchronously collect temperatures at a uniform fixed time interval, forming surface temperature datasets and airflow temperature datasets respectively.

[0059] The fixed time interval is typically between 10 and 60 seconds; too short an interval will lead to large data fluctuations and frequent control oscillations, while too long an interval will result in control lag. For small and medium-sized forgings, which have a faster thermal response, a fixed time interval of 30 seconds is appropriate. For large forgings, which have a slower temperature change, the fixed time interval can be appropriately extended to 60 seconds.

[0060] It is important to ensure that the sensors deployed at non-contact temperature measurement points and gas temperature measurement points have unobstructed lines of sight to avoid interference from high-temperature radiation.

[0061] Step S3: Calculate the average surface temperature and the temperature difference between the upper and lower surfaces based on the surface temperature dataset, and calculate the inlet airflow temperature difference based on the airflow temperature dataset.

[0062] After the target forging is loaded into the furnace according to the corresponding standard loading method, the normal direction of each of the upper surface, lower surface, and side surface in the furnace space can be determined according to the parallel or perpendicular relationship between them and the coordinate axis of the furnace.

[0063] For example, the normal to the lower surface is vertically upward, the normal to the upper surface is vertically downward, and the normal to the side surface is horizontally pointing towards the side wall of the furnace.

[0064] Next, the absolute value of the cosine of the spatial angle between each normal direction and the dominant flow vector is calculated as the effective coefficient of airflow direction; the effective coefficient of airflow direction reflects the degree of frontal scouring of each surface by the airflow, and it is between 0 and 1.

[0065] Then, the geometric areas of the upper and lower surfaces are calculated based on the geometric characteristic parameters. For regularly shaped forgings, the formula can be used directly; for example, for a cuboid forging, the geometric areas of the upper and lower surfaces are obtained by multiplying the length by the width. For curved surfaces, the geometric areas can be obtained through triangular mesh integration.

[0066] The geometric area of ​​the side surface is obtained by subtracting the sum of the geometric areas of the upper and lower surfaces from the total surface area.

[0067] Considering that the contribution of different surfaces to the overall heat transfer depends not only on their area but also on their relative direction to the airflow, weighting by geometric area alone would overestimate the contribution of the leeward side. Therefore, an effective airflow direction coefficient correction is introduced. The effective windward heat transfer area is obtained by multiplying the geometric area of ​​the upper surface, lower surface, and each side surface by the corresponding effective airflow direction coefficient, and used as the heat transfer weight.

[0068] Then, based on the surface temperature dataset, the arithmetic mean of the temperatures corresponding to the upper surface, lower surface, and side surface can be calculated respectively.

[0069] Multiply each average temperature by its corresponding heat transfer weight, sum them up, and then divide by the sum of all heat transfer weights to obtain the average surface temperature.

[0070] The absolute value of the difference between the average temperatures of the upper and lower surfaces is taken as the temperature difference between the upper and lower surfaces. The temperature difference between the upper and lower surfaces reflects the temperature gradient caused by the asymmetry between gravitational convection and radiation.

[0071] Simultaneously, based on the airflow temperature dataset, the temperature difference between the gas at the outlet duct of the circulating fan and the gas at the return duct is calculated to obtain the inlet airflow temperature difference. The inlet airflow temperature difference reflects the temperature rise of the airflow after flowing through the heater and the target forging area, indirectly characterizing the utilization efficiency of the heating power and the heat absorption of the target forging.

[0072] Step S4: Based on the equivalent heat capacity, the theoretical value of the core-surface temperature difference, the average surface temperature, the temperature difference between the upper and lower surfaces, and the temperature difference between the inlet and outlet airflow, a set of control parameters is dynamically generated and output.

[0073] The control parameters include at least the heating power setting, the circulating air speed setting, and the furnace pressure setting.

[0074] Step S41: Determine the heating power setting value. This process specifically involves calculating the difference between the target temperature and the current average surface temperature.

[0075] If the difference is greater than zero, then based on the law of conservation of energy, the product of the equivalent heat capacity and the temperature deviation is divided by the remaining heating time to obtain the heating power setting value, so as to ensure that sufficient heat is provided in the remaining time to make the target forging reach the target temperature; otherwise, the heating power setting value is zero.

[0076] The remaining heating time refers to the time from the current moment to the planned end of the heating phase. It is the difference between the planned duration and the heating time already executed. The executed heating time is accumulated from the start of the heating phase.

[0077] Please see Figure 3Step S42: Determine the circulating air velocity setpoint. This process involves first calculating the cross-sectional area by multiplying the internal width and height of the furnace.

[0078] Then, based on the cross-sectional characteristic dimensions of the target forging, its maximum projected area in the airflow direction is determined. The difference between the cross-sectional area and the maximum projected area is taken as the effective flow area.

[0079] Taking a cuboid forging as an example, if the airflow is along its length, then the windward surface is a rectangle composed of its width and height, and its area is the product of the cross-sectional feature dimension and the height.

[0080] Next, the reference furnace gas flow rate is obtained by multiplying the heating power setpoint and the reference air volume coefficient per unit heat load. Then, the basic circulating air velocity is obtained by dividing the reference furnace gas flow rate by the effective flow area.

[0081] The reference airflow coefficient per unit heat load characterizes the furnace gas flow rate required under standard conditions per unit heating power. To ensure that the airflow can effectively remove heat without causing excessive temperature rise, it can be determined by the following formula: .

[0082] in, The reference air volume coefficient per unit heat load ( ); Furnace gas density ( ); The specific heat capacity of the furnace gas ( ).

[0083] At atmospheric pressure, the furnace gas is a mixture of air and combustion products, and can be treated approximately as dry air. At this time, , It equals the current absolute pressure of the gas inside the furnace divided by the product of the absolute temperature and the air gas constant. The air gas constant is a fixed physical constant, which is 287. .

[0084] The maximum allowable airflow temperature rise is typically set between 20-50°C. Too high a temperature rise will reduce the temperature difference between the airflow and the forging, decreasing heat exchange efficiency; too low a temperature rise will require excessive airflow, resulting in high energy consumption and potentially causing vibration. In this invention, 30°C can be used as an example; for forgings requiring high-precision temperature control, it can be reduced to 20°C; for rough-machined forgings, it can be relaxed to 50°C.

[0085] Then, calculate the difference between the temperature difference between the upper and lower surfaces and the theoretical value of the core surface temperature difference. If the difference is greater than zero, it indicates that the temperature non-uniformity caused by gravity or airflow organization has exceeded the range that the material itself can withstand in terms of heat transfer. It is necessary to increase the circulating air velocity to promote heat exchange between the furnace gas and the surface of the target forging.

[0086] If the difference is less than or equal to zero, it means that the current uniformity is within an acceptable range, no additional intervention is needed, and the wind speed increment is zero.

[0087] For cases where uniformity needs to be improved by enhancing convective heat transfer, the following steps are taken: First, calculate the gas temperature difference between the outlet pipe and the return air pipe of the circulating fan to obtain the measured temperature rise of the airflow.

[0088] Then, based on the difference between the temperature difference between the upper and lower surfaces and the theoretical value of the core surface temperature difference. Equivalent heat capacity and preset temperature difference adjustment time Calculate the additional heat consumption. The additional heat consumption is the additional heat that needs to be carried away by the airflow within the preset temperature difference adjustment time.

[0089] Additional heat consumption The specific calculation formula is as follows: .

[0090] in, It represents the time constant for eliminating the expected temperature difference. Too short a timeframe may lead to sudden changes in wind speed demand and unstable control; too long a timeframe will result in a slow adjustment effect. Generally, the planned duration is taken. to In this invention, 600 seconds can be used as an example.

[0091] In real-time control, to avoid insufficient remaining time at the end of the heating phase, which could prevent the adjustment target from being achieved, the actual effective adjustment time used to calculate the additional heat consumption is taken as... The smaller of the remaining time for the current temperature rise.

[0092] Based on additional heat consumption Actual temperature rise of airflow Furnace gas specific heat capacity And furnace gas density Calculate the additional furnace gas flow rate. The additional furnace gas flow rate represents the extra gas flow rate required to remove the additional heat by the gas flow.

[0093] Additional furnace gas flow The specific calculation formula is as follows: .

[0094] Then, the additional furnace gas flow rate is compared with the effective flow area to obtain the wind speed increment. It should be noted that if the wind speed increment fails to reduce the temperature difference between the upper and lower surfaces in three consecutive iterations, the wind speed increment calculation is paused and manual intervention or alarm is initiated.

[0095] Finally, the base circulating wind speed and wind speed increment are superimposed, and the limit is applied according to the allowable wind speed range of the circulating fan to obtain the circulating wind speed set value.

[0096] The purpose of limiting the airflow is to ensure the normal and safe operation of the circulating fan, prevent overload or surge, and ensure that the airflow is within the effective heat exchange range.

[0097] The permissible operating wind speed range can be determined based on the rated performance parameters of the circulating fan. Typically, it is taken as 30%-120% of the rated wind speed of the circulating fan, that is, the lower limit of the permissible operating wind speed range is 30% of the rated wind speed of the circulating fan, and the upper limit is 120% of the rated wind speed of the circulating fan.

[0098] In actual control, if the sum of the basic circulating wind speed and the wind speed increment is less than the lower limit of the allowable operating wind speed range, the lower limit is used as the final circulating wind speed setting. If it is greater than the upper limit of the allowable operating wind speed range, the upper limit is used as the final circulating wind speed setting. Otherwise, the sum of the basic circulating wind speed and the wind speed increment is used as the final circulating wind speed setting.

[0099] Please see Figure 4 Step S43: Determine the furnace pressure setpoint. This process specifically involves: based on the ideal gas law, calculating the total mass of the gas according to the current absolute pressure, absolute temperature, and net volume of the gas in the furnace.

[0100] The specific formula for calculating the total mass of the gas is as follows: .

[0101] in, The total mass of the gas ( ); The pressure is obtained by superimposing the local atmospheric pressure onto the gauge pressure measured by the furnace pressure sensor; the unit is... .

[0102] Indicates the average thermodynamic temperature of the gas inside the furnace ( The result can be obtained by averaging the thermocouple measurements from multiple points in the furnace and then summing them up to 273.15.

[0103] Net furnace volume ( The value is obtained by subtracting the total volume of the target forging from the internal volume of the furnace.

[0104] The gas constant of the furnace gas If the furnace is filled with air, This is the air gas constant; if the furnace atmosphere is protective, it is obtained by dividing the general gas constant by the molar mass of the mixed gas, where the general gas constant is 8314. .

[0105] Next, the effective heat supply is obtained by multiplying the heating power setting, the executed heating time, and the heater thermal efficiency.

[0106] Heater thermal efficiency refers to the proportion of heat generated by the heater that is actually absorbed by the furnace gas. It is an inherent constant of the equipment and is usually provided by the equipment manufacturer.

[0107] Then, the effective heat supply is divided by the product of the total gas mass and the specific heat capacity of the furnace gas to obtain the theoretical gas temperature rise. The absolute pressure is multiplied by the theoretical gas temperature rise and then divided by the absolute temperature to obtain the thermal expansion pressure increment, which reflects the natural increase in pressure caused by the thermal expansion of the gas.

[0108] Simultaneously, the static pressure increment is obtained by multiplying the circulating wind speed setpoint with the furnace unit wind speed flow resistance coefficient.

[0109] Among them, the flow resistance coefficient per unit wind speed in the furnace characterizes the resistance characteristics of the furnace structure to airflow.

[0110] The following method can be used to determine the relationship between pressure loss and wind speed: In the empty furnace state, set the fan speed to 20%, 40%, 60%, ..., 120% of the rated value in sequence, measure and record the corresponding static pressure difference between the furnace inlet and outlet, and then use the least squares method or other fitting methods to obtain the curve of pressure loss and wind speed. The slope or fitting coefficient is the flow resistance coefficient per unit wind speed in the furnace.

[0111] Ultimately, it was considered that the total furnace pressure needed to overcome the thermal expansion effect, maintain the basic positive pressure, and compensate for flow resistance in order to ensure that the furnace could maintain a stable, sealed, slightly positive pressure environment under dynamic changes.

[0112] Therefore, the sum of the thermal expansion pressure increment, the furnace micro-positive pressure reference value, and the static pressure increment is used as the furnace pressure setpoint.

[0113] The reference value for the slight positive pressure in the furnace can be set according to the industrial furnace sealing standard, typically 10-30. 15 preferred The furnace micro-positive pressure reference value is less than 10. It may not be sufficient to resist slight negative pressure fluctuations that cause cold air to seep in; greater than 30 This could increase the burden on the furnace door seal or cause unnecessary heat loss.

[0114] S5. Based on the control parameters, synchronously adjust the heater output power, circulating fan speed, and pressure regulating device of the heat treatment furnace to achieve closed-loop control.

[0115] The reason for simultaneously adjusting the heater output power, circulating fan speed, and pressure regulating device is that heating power, air volume, and furnace pressure are interdependent. For example, increasing the heating power requires a corresponding increase in air volume to remove excess heat and prevent localized overheating; increasing the air volume will change the furnace pressure distribution; and pressure changes may affect the airflow organization.

[0116] The specific adjustment process is as follows: the heating power setting value is input into the heater's power controller. The power controller adjusts the voltage or current applied to the heating element by changing the conduction angle or on / off ratio, thereby precisely controlling its heating power.

[0117] Furthermore, based on the fan characteristic curves provided by the manufacturer, the circulating air velocity setpoint is converted into fan speed. The fan characteristic curves describe the relationship between airflow, speed, and air pressure under specific system resistance.

[0118] The fan speed is then sent as a given value to the variable frequency drive of the circulating fan. The variable frequency drive changes the fan motor speed by adjusting the frequency of the output power supply, thereby controlling the circulating air speed.

[0119] Simultaneously, the deviation between the furnace pressure setpoint and the current furnace pressure is calculated. Based on the magnitude and accumulation of the deviation, the proportional-integral controller outputs an analog control signal to control the opening or rotation speed of the pressure regulating device, thereby changing the exhaust volume or air supply volume, so that the actual furnace pressure quickly and smoothly tracks the furnace pressure setpoint.

[0120] The current pressure value in the furnace is obtained directly by a pressure sensor installed on the furnace.

[0121] S6. Repeat steps S2 to S5 until the average surface temperature reaches the preset temperature and the temperature difference between the upper and lower surfaces is less than the theoretical value of the core-surface temperature difference. Then, control the heat treatment process to enter the heat preservation stage. The preset temperature is the target temperature determined in step S11.

[0122] The above embodiments can be implemented, in whole or in part, by software, hardware, firmware, or any other combination thereof. When implemented using software, the above embodiments can be implemented, in whole or in part, in the form of a computer program product.

[0123] Those skilled in the art will recognize that the modules and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0124] In addition, the functional modules in the various embodiments of the present invention can be integrated into one processing module, or each module can exist physically separately, or two or more modules can be integrated into one module.

[0125] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

[0126] Finally, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An intelligent temperature control heat treatment method for alloy forging processing, characterized in that, The method comprises the following steps: S1, obtaining the geometric characteristic parameters and physical property parameters of the target forging, and calculating the equivalent heat capacity and the theoretical value of the core-surface temperature difference thereof according to the parameters; S2, collecting the surface temperature data set of the target forging and the temperature data set of the circulating airflow in the furnace in real time; S3, calculating the surface average temperature and the upper-lower surface temperature difference according to the surface temperature data set, and calculating the inlet-outlet airflow temperature difference according to the airflow temperature data set; S4, based on the equivalent heat capacity, the theoretical value of the core-surface temperature difference, the surface average temperature, the upper-lower surface temperature difference and the inlet-outlet airflow temperature difference, a set of control parameters is dynamically generated and output; the control parameters at least include the heating power set value, the circulating air speed set value and the furnace pressure set value; S5, according to the control parameters, the output power of the heater, the circulating fan speed and the pressure adjusting device of the heat treatment furnace are synchronously adjusted; S6, steps S2 to S5 are repeatedly executed until the surface average temperature reaches the preset temperature and the upper-lower surface temperature difference is less than the theoretical value of the core-surface temperature difference, then the control of the heat treatment process is transferred to the holding stage; The geometric characteristic parameters include the thickness, total surface area, total volume and cross-sectional characteristic size of the target forging; the physical property parameters include the density, specific heat capacity and thermal conductivity of the material; and the cross-sectional characteristic size is the maximum projection cross-sectional size perpendicular to the thickness direction.

2. The intelligent temperature control heat treatment method for alloy forging machining according to claim 1, characterized in that, The process of calculating the equivalent heat capacity is: The density and specific heat capacity of the material are multiplied, and then multiplied by the total volume to obtain the total heat required for the target forging to rise by a unit temperature, that is, the equivalent heat capacity.

3. The intelligent temperature-controlled heat treatment method for alloy forging machining according to claim 1, characterized in that, The process of calculating the theoretical value of the core-surface temperature difference is: The maximum thickness of the target forging is selected as the heat transfer path length; the thermal diffusivity is obtained by dividing the thermal conductivity by the product of the density and the specific heat capacity; The initial temperature, target temperature and planned duration of the temperature rising stage of the heat treatment process are obtained; The temperature rising rate is calculated according to the difference between the target temperature and the initial temperature and the planned duration; The temperature rising rate, heat transfer path length and thermal diffusivity are substituted into the theoretical calculation relationship of the core-surface temperature difference to obtain the temperature difference between the core and the surface of the forging, that is, the theoretical value of the core-surface temperature difference.

4. The intelligent temperature-controlled heat treatment method for alloy forging machining according to claim 1, characterized in that, The step S2 is specifically: According to the geometric characteristic parameters and the size of the furnace chamber of the heat treatment furnace, the standard loading mode of the target forging in the furnace chamber is determined; Based on the determined standard loading mode, the upper surface, lower surface and side surface of the target forging are defined; Non-contact temperature measurement points are set up at the top and bottom positions of the furnace chamber corresponding to the upper surface and the lower surface, and at least one side surface opposite the side wall position of the furnace chamber; Gas temperature measurement points for the circulating airflow are set up at the outlet pipeline, return pipeline and key positions in the furnace chamber of the circulating fan of the heat treatment furnace; All non-contact temperature measurement points and gas temperature measurement points are synchronously collected at a uniform fixed time interval to form the surface temperature data set and the airflow temperature data set, respectively.

5. The intelligent temperature-controlled heat treatment method for alloy forging machining according to claim 4, characterized in that, The determination process of the standard loading mode is: The internal volume of the furnace chamber is calculated from the internal length, width and height of the furnace chamber; The largest area of the outer surface in the target forging is identified as the main bearing surface; when loading, the main bearing surface is made to face downward and be parallel to the bottom surface of the furnace chamber; At this time, the main bearing surface is the lower surface, the actually upward outer surface is the upper surface, and the remaining exposed surface is the side surface; If the ratio of the total volume of the target forgings to the internal volume of the furnace is less than or equal to a preset process threshold, the target forgings are centrally placed in the center area of the furnace bottom surface; otherwise, a plurality of target forgings are uniformly arranged on the furnace bottom surface with a preset safety interval; The orientation of the target forgings is adjusted so that the projection length direction of the target forgings on the furnace bottom surface is parallel to the main flow direction of the circulating gas flow in the furnace.

6. The intelligent temperature-controlled heat treatment method for alloy forging machining according to claim 1, characterized in that, The process of calculating the surface average temperature and the temperature difference between the upper and lower surfaces is as follows: According to the standard charging mode, the normal directions of the upper surface, the lower surface and each side surface in the furnace space are determined; The absolute value of the cosine of the spatial angle between each normal direction and the main flow direction vector is calculated as the effective coefficient of the gas flow direction; The geometric areas of the upper surface and the lower surface are calculated according to the geometric characteristic parameters; The geometric area of the side surface is obtained by subtracting the sum of the geometric areas of the upper surface and the lower surface from the total surface area; The geometric areas of the upper surface, the lower surface and each side surface are multiplied by the corresponding effective coefficients of the gas flow direction to obtain the effective windward heat exchange areas as the heat exchange weights; Based on the surface temperature data set, the arithmetic mean values of the temperatures corresponding to the upper surface, the lower surface and the side surface are respectively calculated; The surface average temperature is obtained by summing the products of each average temperature and the corresponding heat exchange weight, and then dividing the sum by the sum of all heat exchange weights; The absolute value of the difference between the average temperatures of the upper surface and the lower surface is taken as the temperature difference between the upper and lower surfaces.

7. The intelligent temperature-controlled heat treatment method for alloy forging machining according to claim 1, characterized in that, The determination process of the heating power set value and the circulating air speed set value is as follows: If the difference between the target temperature and the current surface average temperature is greater than zero, the product of the equivalent heat capacity and the temperature deviation is divided by the remaining time to obtain the heating power set value; otherwise, the heating power set value is zero; The cross-sectional area is calculated from the internal width and height of the furnace; and the maximum projected area of the target forgings in the gas flow direction is determined according to the characteristic dimensions of the cross section of the target forgings; The difference between the cross-sectional area and the maximum projected area is taken as the effective flow area; The reference furnace gas flow rate is calculated according to the heating power set value and the unit heat load reference air volume coefficient, and then divided by the effective flow area to obtain the basic circulating air speed; If the difference between the temperature difference between the upper and lower surfaces and the theoretical value of the core-surface temperature difference is greater than zero, the gas temperature difference at the outlet pipe of the circulating fan and the return air pipe is calculated to obtain the measured temperature rise of the gas flow; Based on the difference, the equivalent heat capacity and the preset temperature difference adjustment time, the additional heat consumption is calculated; and according to the additional heat consumption, the measured temperature rise of the gas flow, the specific heat capacity of the furnace gas and the density of the furnace gas, the additional furnace gas flow rate is calculated; The wind speed increment is obtained by dividing the additional furnace gas flow rate by the effective flow area; otherwise, the wind speed increment is zero; The circulating air speed set value is obtained by superimposing the basic circulating air speed and the wind speed increment, and then limiting the amplitude according to the allowable wind speed interval of the circulating fan.

8. The intelligent temperature-controlled heat treatment method for alloy forging machining according to claim 7, characterized in that, The determination process of the furnace pressure set value is as follows: Based on the ideal gas state equation, the total mass of the gas in the furnace is calculated according to the current absolute pressure, the absolute temperature and the net volume of the furnace; The effective heat supply is obtained by multiplying the heating power set value, the executed heating time and the heater thermal efficiency; The theoretical gas temperature rise is obtained by dividing the effective heat supply by the product of the total mass of the gas and the specific heat capacity of the furnace gas; The thermal expansion pressure increment is obtained by multiplying the absolute pressure and the theoretical gas temperature rise, and then dividing by the absolute temperature. According to the circulating air speed setting value and the furnace unit air speed flow resistance coefficient, the static pressure increment is calculated; The sum of the thermal expansion pressure increment, the furnace micro-positive pressure reference value and the static pressure increment is taken as the furnace pressure setting value.

9. The intelligent temperature-controlled heat treatment method for alloy forging machining according to claim 1, characterized in that, The step S5 is specifically: The heating power setting value is input into the power controller of the heater to drive the heater to adjust the output power; The circulating air speed setting value is converted into the fan rotating speed and sent to the frequency converter driver of the circulating fan to adjust the rotating speed; According to the deviation of the furnace pressure setting value and the current pressure value of the furnace, the control signal is generated through the proportional integral regulator to drive the pressure adjusting device to adjust the furnace pressure.

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