A method for predicting flow, temperature and tissue fields at different locations

Abstract

The present invention discloses a method for predicting flow fields, temperature fields, and tissue fields at different locations. An integrated signal collector is designed that can simultaneously collect medium flow rate and temperature. The integrated signal collector is installed in a quenching tank at a predetermined workstation at a complex location on the casting structure and numbered. A multi-channel data acquisition instrument is used to collect and record the data. The collected data is processed to calculate the heat transfer coefficient at different locations, establishing a relationship between medium flow rate, temperature, and the heat transfer coefficient. Thermodynamic parameters and the heat transfer coefficient are calculated, and the initial medium temperature and the casting heat treatment temperature are collected to establish a finite element numerical model. A quenching model is established using the actual medium flow rate and temperature, combined with finite element numerical simulation, to obtain the flow field, temperature field, and tissue field at different locations. The heat transfer coefficient obtained by the present invention through reverse heat transfer calculation can further improve the accuracy of the numerical simulation results of the quenching process. Heat treatment parameters set based on the tissue field predicted by this model can achieve a more uniform tissue in the casting.

Description

Technical Field

[0001] The invention relates to a method for predicting flow fields, temperature fields and tissue fields at different positions, and belongs to the field of heat treatment process parameter measurement and result prediction. Background Art

[0002] Metal heat treatment is a key process in mechanical manufacturing. Compared to other machining processes, heat treatment generally does not alter the workpiece's shape or overall chemical composition. Instead, it modifies the workpiece's internal microstructure or surface chemical composition to impart or improve its performance. Its hallmark is improvement in the workpiece's intrinsic quality, which is generally invisible to the naked eye. To ensure that metal workpieces possess the desired mechanical, physical, and chemical properties, heat treatment is often essential, in addition to the appropriate selection of materials and various forming techniques. Heat treatment generally involves three steps: heating, holding, and cooling, or sometimes just heating and cooling. These processes are interconnected and inseparable. Cooling is the most critical step in heat treatment, and the precise measurement and prediction of temperature curves during the cooling process has long been a research hotspot.

[0003] Quenching is a heat treatment process in which a metal workpiece is heated to a suitable temperature, held for a period of time, and then rapidly cooled by immersion in a quenching medium to achieve a high-strength, high-hardness martensitic structure. During the quenching process, standardized thermocouples are often fixed inside the workpiece to record the temperature. Multiple cooling temperature curves are then integrated to provide a general description of the temperature field during the quenching process.

[0004] At present, people have conducted in-depth research on temperature fields, using the finite difference method and the finite element method to perform numerical simulations of temperature fields. However, these simulations cannot accurately reflect actual temperature changes. This is because the simulation process generally does not consider the factors of medium changes with temperature, but simplifies it to a fixed heat transfer coefficient and medium temperature. However, in actual production, the medium temperature will change significantly with the workpiece temperature. When a certain temperature is reached, the medium will boil. According to the size of the boiling bubbles, it is divided into three stages: film boiling, transition boiling, and nucleate boiling, which are reflected in different heat transfer coefficients.

[0005] Using flow rate and temperature collectors to collect data on the heat transfer states of the three stages and conduct joint analysis can obtain curves of heat transfer coefficients at different positions changing with temperature. Summary of the Invention

[0006] The present invention addresses the problem that the quenching process cannot be accurately measured and predicted at present, and provides a method for predicting the flow field, temperature field and structure field at different positions, which specifically includes the following steps:

[0007] (1) An integrated signal collector that can simultaneously collect medium flow rate and temperature is used and installed in the quenching tank of a set workstation, preferably at the complex structure of the casting, and numbered. The integrated signal collector is connected to the temperature transmitter, and the temperature transmitter is connected to the multi-channel data acquisition instrument to collect and record data.

[0008] (2) The collected data were processed using MATLAB-based programming software to distinguish different stages of medium boiling (the flow rate and heat transfer coefficient in different boiling states are different), calculate the heat transfer coefficient at different positions, and establish the relationship between medium flow rate, temperature and heat transfer coefficient. The formula is:

[0009] q=λ(T1-T2)V,

[0010] Where: q is the heat flux density, λ is the thermal conductivity of the material, (T1-T2) is the temperature change of the medium, where T1 is the actual temperature, T2 is the end temperature, and V is the flow rate of the medium.

[0011] (3) Use the thermodynamic parameters and heat transfer coefficients calculated by software (such as Comsol, Ansys), collect the initial temperature of the medium and the heat treatment temperature of the casting to establish a finite element numerical model.

[0012] (4) A quenching model was established by combining the medium flow rate and medium temperature recorded in actual production with finite element numerical simulation to obtain the flow field, temperature field and tissue field at different positions.

[0013] The heat transfer coefficient at different positions is repeatedly calculated according to the formula q=h(Ts-Tg), where: q is the heat flux density, h is the surface heat transfer coefficient, Ts is the surface temperature of the sample to be tested, and Tg is the medium temperature.

[0014] Preferably, the integrated signal collector described in step 1 of the present invention includes an annular thermocouple I1, an annular thermocouple II2, a compensating thermocouple 3, an induction propeller 4, a gear hinge 5, and a bracket sleeve 6; the two ends of the annular thermocouple I1 and the annular thermocouple II2 are connected to form a circle by a gear hinge 5, and a semicircular connector is provided at the lower end of the bracket sleeve 6. The two ends of the semicircular connector are connected to the annular thermocouple I1 and the annular thermocouple II2 through the gear hinge 5. The annular thermocouple I1 and the annular thermocouple II2 are in direct contact with the surface of the casting. The position of the thermocouple induction wire is adjusted by the gear hinge to adapt to castings of different shapes. The height of the thermocouple can be adjusted by rotation within the range of 25° to 335° to adapt to contact temperature measurement with the surfaces of castings of different shapes; the two ends of the induction propeller 4 are connected to the gear hinge 5, and a bracket sleeve 6 is provided directly above the induction propeller 4, and a compensating thermocouple 3 is installed at the lower end of the bracket sleeve 6.

[0015] Preferably, the compensating thermocouple 3 described in the present invention includes a thermocouple positive wire 31, a thermocouple negative wire 32, a sleeve connector 33, an induction joint 34, and an insulating medium 35; the intersection of the thermocouple positive wire 31, the thermocouple negative wire 32 and the induction joint 34 is connected, and the induction joint 34 is connected to the bracket sleeve 6 through the sleeve connector 33. The bracket sleeve 6 and the induction joint 34 are hollow structures filled with an insulating medium 35, which is used to measure the medium temperature as a compensation condition to correct the temperature data of the other two thermocouples.

[0016] Preferably, the induction joint 34 of the present invention is made of copper-aluminum alloy, the outer surface is a truncated cone structure, and the inner surface is a conical structure; the surface roughness of the induction joint 34 is Ra0.1-Ra0.3.

[0017] Preferably, the rotating shaft 44 of the induction propeller 4 described in the present invention is made of insulating material, and closed coils are provided at both ends of the rotating shaft. Corresponding insulating protrusions 43 are provided on the rotating shaft 44. When the induction propeller 4 rotates one circle, the contact point of the insulating protrusion 43 contacts the positive pole 41 and the negative pole 42 of the induction coil, pushing up the positive pole part in the closed coil, disconnecting the circuit, and the built-in signal device generates a rotation signal.

[0018] Preferably, the induction propeller 4 described in the present invention is driven by the medium flow to rotate the induction propeller rotor, and the built-in signal device generates a speed signal. The medium flow velocity is obtained by V=KN / T, where V: average flow velocity during the flow measurement time period (m / s), K: blade pitch (mm), N: number of signals during the flow measurement period, T: flow measurement duration (s), and the material of the induction propeller is graphite carbon fiber.

[0019] The beneficial effects of the present invention compared to the prior art are:

[0020] (1) The integrated thermocouple and induction propeller simultaneously measure the medium temperature and flow rate at the same position. The ring thermocouple and the frustum contact mode can be changed to achieve a rapid response to the temperature. At the same time, the data of the three thermocouples are mutually corrected to obtain more accurate temperature data.

[0021] (2) A variety of signal detection equipment is used to record and analyze the quenching process from multiple aspects, especially the three stages of medium boiling, where the flow rate has obvious changes; the heat transfer coefficient calculated by the reverse heat transfer method can further improve the accuracy of the numerical simulation results of the quenching process. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the structure of the integrated signal collector capable of simultaneously collecting medium flow velocity and temperature according to the present invention;

[0023] Figure 2 Schematic diagram of the movement of the annular thermocouple;

[0024] Figure 3 This is a schematic diagram of the structure of the compensation temperature measurement thermocouple of the present invention.

[0025] Figure 4 This is a schematic diagram of the installation location of the integrated signal collector;

[0026] Figure 5 Schematic diagram of the induction propeller structure, A is the disconnected diagram, and B is the closed circuit diagram;

[0027] Figure 6 This is the actual measurement map;

[0028] Figure 7 is the collected medium flow velocity curve;

[0029] Figure 8 To compensate and correct the temperature curve for the measured thermocouple;

[0030] Figure 9 To simulate the temperature curve of the corresponding point;

[0031] Figure 10 is the temperature field obtained by simulation.

[0032] Figure 1 Middle: 1-annular thermocouple I; 2-annular thermocouple II; 3-compensating thermocouple; 4-induction propeller; 5-gear hinge; 6-bracket sleeve;

[0033] Figure 3 Middle: 31- thermocouple positive electrode wire, 32- thermocouple negative electrode wire, 33- sleeve connector, 34- induction joint, 35- insulating medium.

[0034] Figure 5 Middle: 41 - positive pole of induction coil, 42 - negative pole of induction coil, 43 - insulating protrusion; 44 - rotating shaft. DETAILED DESCRIPTION

[0035] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited to the contents described above.

[0036] Example 1

[0037] A method for predicting flow fields, temperature fields, and tissue fields at different locations comprises the following steps:

[0038] (1) An integrated signal collector that can simultaneously collect medium flow rate and temperature is installed in the quenching tank of the set workstation at the complex structure of the casting, and is numbered. It is connected to the multi-channel data acquisition instrument through a temperature transmitter to collect and record data.

[0039] (2) The collected data were processed using MATLAB-based programming software to distinguish the different stages of medium boiling, calculate the heat transfer coefficient at different positions, and establish the relationship between medium flow rate, temperature and heat transfer coefficient.

[0040] (3) Using the thermodynamic parameters and heat transfer coefficients calculated by the software, the initial temperature of the medium and the heat treatment temperature of the casting are collected to establish a finite element numerical model.

[0041] (4) A quenching model was established by combining the medium flow rate and medium temperature recorded in actual production with finite element numerical simulation to obtain the flow field, temperature field and tissue field at different positions.

[0042] Application Cases:

[0043] Select two integrated signal collectors and fix them in the quenching tank where the casting structure is complex. They are numbered 1 and 2. The installation position is as follows: Figure 4 As shown;

[0044] The casting is sent into a resistance furnace and heated to 1000°C. It is kept warm for 2 hours to make the internal temperature uniform. The water circulation system of the quenching tank is turned on.

[0045] Turn on the multi-channel data acquisition instrument, wait for the water flow to stabilize, take out the casting from the resistance furnace, use the crane basket to put it into the quenching tank for quenching, such as Figure 6 As shown, the collector starts to collect the quenching casting temperature, medium temperature and medium flow rate signals.

[0046] When the casting temperature collected by the two integrated signal collectors reaches about 20℃, remove the casting and turn off the multi-channel data collector. Export the data to the computer through the USB flash drive and use the origin data processing software to enter the formula V=KN / T to convert it. Figure 7 Data shown.

[0047] The collected data were processed using Matlab-based programming software to remove abnormal data and obtain Figure 8 The temperature cooling curve distinguishes the three stages of boiling by the temperature change amplitude and flow rate, calculates the heat transfer coefficient at two positions, and establishes the relationship between medium flow rate, temperature and heat transfer coefficient through the formula q=h(Ts-Tg) and q=λ(T1-T2)V in the inverse heat transfer method.

[0048] Thermodynamic parameters and heat transfer coefficients calculated by software were used to establish a finite element numerical model and obtain Figure 9 The temperature cooling curve at the corresponding position shown has a high degree of fit with the actual curve.

[0049] pass Figure 10The numerical model of the temperature field can obtain the temperature gradient change value and the distribution gradient of the microstructure transformation variable, and can analyze and determine the main factors and change range that affect the temperature cooling curve during the quenching process, and then simulate and calculate the microstructure field of the entire process. In batch production, the microstructure distribution of the entire casting after quenching heat treatment can be predicted by simply placing the integrated signal collector designed by the present invention at a specific position.

[0050] As a preferred embodiment of the present invention, the integrated signal collector capable of simultaneously collecting the flow rate and temperature of the medium is as follows: Figures 1 to 4 As shown, it includes an annular thermocouple Ⅰ1, an annular thermocouple Ⅱ2, a compensating thermocouple 3, an induction propeller 4, a gear hinge 5, and a bracket sleeve 6; the two ends of the annular thermocouple Ⅰ1 and the annular thermocouple Ⅱ2 are connected to form a circle through the gear hinge 5, and the lower end of the bracket sleeve 6 is provided with a semicircular connector, and the two ends of the semicircular connector are connected to the annular thermocouple Ⅰ1 and the annular thermocouple Ⅱ2 through the gear hinge 5. The annular thermocouple Ⅰ1 and the annular thermocouple Ⅱ2 are in direct contact with the surface of the casting. The position of the thermocouple induction wire is adjusted by the gear hinge to adapt to castings of different shapes. The thermocouple height can be adjusted by rotating within the range of 25° to 335° to adapt to castings of different shapes. Surface contact temperature measurement of the component; both ends of the induction propeller 4 are connected to the gear hinge 5, and a bracket sleeve 6 is provided just above the induction propeller 4, and a compensating thermocouple 3 is installed at the lower end of the bracket sleeve 6; the compensating thermocouple 3 includes a thermocouple positive wire 31, a thermocouple negative wire 32, a sleeve connector 33, an induction joint 34, and an insulating medium 35; the intersection of the thermocouple positive wire 31, the thermocouple negative wire 32 and the induction joint 34 is connected, and the induction joint 34 is connected to the bracket sleeve 6 through the sleeve connector 33. The bracket sleeve 6 and the induction joint 34 are hollow structures filled with an insulating medium 35, which is used to measure the medium temperature as a compensation condition to correct the temperature data of the other two thermocouples. The induction joint 34 is made of copper-aluminum alloy, with an outer surface shape of a truncated cone structure and an inner surface shape of a conical structure; the surface roughness of the induction joint 34 is Ra0.1-Ra0.3; the rotating shaft 44 of the induction propeller 4 is made of insulating material, and closed coils are provided at both ends of the rotating shaft. Corresponding insulating protrusions 43 are provided on the rotating shaft 44. When the induction propeller 4 rotates one circle, the contact point of the insulating protrusion 43 contacts the positive pole 41 and the negative pole 42 of the induction coil, pushing up the positive pole part of the closed coil, disconnecting the circuit, and the built-in signal device generates a rotation signal.

Claims

1. A method for predicting flow fields, temperature fields and tissue fields at different locations, characterized in that: The specific steps include: (1) Use an integrated signal collector that can simultaneously collect medium flow rate and temperature, install it in the quenching tank at the set workstation, and number it. Connect the integrated signal collector to the temperature transmitter, and the temperature transmitter is connected to the multi-channel data acquisition instrument to collect and record data. (2) The collected data were processed using MATLAB-based programming software to distinguish different stages of medium boiling, calculate the heat transfer coefficient at different positions, and establish the relationship between medium flow rate, temperature and heat transfer coefficient. The formula is: q = λ (T1-T2) V, Where: q is the heat flux density, λ is the thermal conductivity of the material, (T1-T2) is the temperature change of the medium, and V is the flow rate of the medium; (3) Using the thermodynamic parameters and heat transfer coefficients calculated by the software, the initial temperature of the medium and the heat treatment temperature of the casting are collected to establish a finite element numerical model; (4) By combining the medium flow rate and medium temperature recorded in actual production with finite element numerical simulation, a quenching model is established to obtain the flow field, temperature field and structure field at different positions; The integrated signal collector in step (1) comprises an annular thermocouple I (1), an annular thermocouple II (2), a compensating thermocouple (3), an induction propeller (4), a gear hinge (5), and a bracket sleeve (6); the two ends of the annular thermocouple I (1) and the annular thermocouple II (2) are connected to form a circle through the gear hinge (5); a semicircular connector is provided at the lower end of the bracket sleeve (6); the two ends of the semicircular connector are connected to the annular thermocouple I (1) and the annular thermocouple II (2) through the gear hinge (5); the two ends of the induction propeller (4) are connected to the gear hinge (5); a bracket sleeve (6) is provided directly above the induction propeller (4); and a compensating thermocouple (3) is installed at the lower end of the bracket sleeve (6).

2. The method for predicting flow field, temperature field and tissue field at different positions according to claim 1, characterized in that: The heat transfer coefficient at different positions is repeatedly calculated according to the formula q=h(Ts-Tg), where: q is the heat flux density, h is the surface heat transfer coefficient, Ts is the surface temperature of the sample to be tested, and Tg is the medium temperature.

3. The method for predicting flow fields, temperature fields, and tissue fields at different locations according to claim 1, characterized in that: The compensating thermocouple (3) comprises a thermocouple positive electrode wire (31), a thermocouple negative electrode wire (32), a sleeve connector (33), a sensing joint (34), and an insulating medium (35); the thermocouple positive electrode wire (31), the thermocouple negative electrode wire (32), and the sensing joint (34) are connected at an intersection; the sensing joint (34) is connected to the support sleeve (6) through the sleeve connector (33); the support sleeve (6) and the sensing joint (34) are hollow structures and are filled with the insulating medium (35).

4. The method for predicting flow fields, temperature fields, and tissue fields at different locations according to claim 3, characterized in that: The induction joint (34) is made of copper-aluminum alloy, has an outer surface shape of a truncated cone structure, and an inner surface shape of a conical structure; and the surface roughness of the induction joint (34) is Ra0.1-Ra0.

3.

5. The method for predicting flow fields, temperature fields, and tissue fields at different locations according to claim 1, characterized in that: The rotating shaft (44) of the induction propeller (4) is made of insulating material, and closed coils are provided at both ends of the rotating shaft. Insulating protrusions (43) are provided on the rotating shaft (44) accordingly. When the induction propeller (4) rotates one circle, the contact point of the insulating protrusion (43) contacts the positive pole (41) and the negative pole (42) of the induction coil, and the positive pole part in the closed coil is lifted, the circuit is disconnected, and the built-in signal device generates a rotation signal.

6. The method for predicting flow fields, temperature fields, and tissue fields at different locations according to claim 5, characterized in that: The induction propeller (4) is driven by the flow of the medium to rotate the induction propeller rotor, and a built-in signal device generates a rotation signal, and the medium flow velocity is obtained by V=KN / T, wherein V is the average flow velocity in the flow measurement time period (m / s), K is the blade pitch (mm), N is the number of signals in the flow measurement time period, and T is the flow measurement duration (s). The material of the induction propeller is graphite carbon fiber.

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