Hot method sand mixing equipment with temperature control heating function

Abstract

The application discloses a hot method sand mixing equipment with temperature control heating function and belongs to the field of casting equipment. The equipment comprises a base, a sand mixing cylinder and a sand mixing rotor in the cylinder. The sand mixing cylinder is divided into three heating zones, i.e. a preheating zone, a sand mixing zone and a heat preservation zone along the axial direction. The equipment is provided with an electric heating system, including partition heating elements and temperature sensors corresponding to the three zones, and a PLC intelligent temperature control unit. The sand mixing zone is provided with infrared temperature measuring sensors integrated with a miniature black body calibration module and an ultrasonic oscillation dust removal ring, and the signals are connected to the PLC unit. The hot air circulation system comprises a hot air generator, a hot type composite guide plate in the cylinder and a top air return pipeline. The hollow ventilation cavity of the guide plate is embedded with a serpentine electric heating wire. The sand inlet preheating device adopts a jacket type heat exchanger, and an outer annular waste heat passage is connected in parallel with the air return pipeline through a three-way valve. The application realizes double-mode coupled heat exchange of "hot air convection + radiation heat conduction", self-calibration and pollution prevention of temperature measurement and waste heat gradient recovery, and significantly improves the temperature control precision and energy utilization rate.

Description

Technical Field

[0001] This invention relates to the field of casting equipment technology, and specifically to a thermal sand mixing equipment with temperature control heating function. Background Technology

[0002] In casting production, the temperature control of molding sand and core sand has a significant impact on casting quality. Traditional sand mixing equipment mainly uses room temperature mixing processes, which cannot meet the sand temperature requirements of certain special processes. To solve the sand temperature control problem, some sand mixing equipment with temperature control functions has emerged in the existing technology.

[0003] A Chinese patent with publication number CN107971457B discloses a continuous sand mixer and a sand mixing process. This design involves installing a temperature control cylinder outside the sand conveying and mixing mechanism and the final mixing mechanism, with a temperature control medium flowing through the gap between the temperature control cylinder and the mixing mechanism to regulate the sand temperature. However, this design uses indirect heating with a temperature control medium, resulting in low heat exchange efficiency and slow sand temperature regulation. Furthermore, it cannot independently control the temperature of different areas of the mixing cylinder, leading to uneven sand temperature distribution.

[0004] A Chinese patent with publication number CN204321085U discloses a sand temperature regulating device for a sand mixer. This solution involves setting up a heat exchange pipeline inside the boiling sand hopper, and circulating a temperature-controlling medium through the pipeline to regulate the temperature of the raw sand. However, this solution also uses an indirect heat exchange method, resulting in low heating efficiency; it lacks a hot air circulation system, leading to poor heating uniformity; and it lacks a real-time online sand temperature detection and feedback control mechanism, resulting in low temperature control accuracy.

[0005] Furthermore, in existing sand mixing equipment with hot air circulation systems, the guide plate only serves to guide the hot air, and its function is disconnected from the heating element on the cylinder wall, thus limiting the heat exchange efficiency. The dust concentration in the foundry workshop can reach 10mg / m³, and the infrared temperature measurement error is prone to exceed ±5℃. The infrared temperature sensor has a temperature drift problem in high-temperature dust environments, and it only relies on compressed air to blow the lens, which cannot solve the problem of inaccurate temperature measurement. The preheating device at the sand inlet uses an independent electric heating tube, which does not utilize the waste heat of the high-temperature exhaust gas discharged from the sand mixing cylinder. The hot air temperature in the return air duct is about 120℃, and about 30% of the heat is still not utilized, resulting in low energy utilization. Summary of the Invention

[0006] The purpose of this invention is to provide a thermal sand mixing device with temperature control heating function to solve the following technical problems existing in the prior art: existing sand mixing devices use indirect heating with temperature control medium, resulting in low heat exchange efficiency and slow sand temperature adjustment speed; they cannot implement independent temperature control for different areas of the sand mixing cylinder, leading to uneven sand temperature distribution; they lack a real-time online sand temperature detection and feedback control mechanism, resulting in low temperature control accuracy; the functions of the guide plate and heating element are disconnected, limiting heat exchange efficiency; infrared temperature sensors suffer from temperature drift in industrial dust environments and have high maintenance costs; and the preheating device at the sand inlet has low energy utilization.

[0007] To solve the above problems, the technical solution provided by the present invention is as follows:

[0008] A thermal sand mixing device with temperature control heating function includes a base, a sand mixing cylinder, and a sand mixing rotor disposed inside the sand mixing cylinder. One end of the sand mixing cylinder is provided with a sand inlet, and the other end is provided with a sand outlet. The sand mixing rotor is rotatably connected to the sand mixing cylinder through a bearing, and one end of the sand mixing rotor is connected to a drive motor.

[0009] The sand mixing cylinder is divided into a preheating zone, a sand mixing zone, and a heat preservation zone along the axial direction.

[0010] The electric heating system includes zoned heating elements respectively located in the preheating zone, sand mixing zone and heat preservation zone, as well as temperature sensors arranged for each heating zone;

[0011] The PLC intelligent temperature control unit has its signal input terminal connected to the temperature sensor and its power output terminal connected to the power input terminal of each zone heating element.

[0012] The sand temperature online detection device includes an infrared temperature sensor installed in the sand mixing zone. The signal output terminal of the infrared temperature sensor is connected to the signal input terminal of the PLC intelligent temperature control unit. The detection terminal of the infrared temperature sensor integrates a miniature blackbody calibration module and an ultrasonic oscillation dust removal ring.

[0013] A hot air circulation system includes a hot air generator, an internally heated composite baffle plate disposed inside a sand mixing cylinder, and a return air duct disposed at the top of the sand mixing cylinder. The bottom of the sand mixing cylinder has an air inlet, and the air outlet of the hot air generator is connected to the air inlet via the air inlet duct. The air inlet is connected to the hollow ventilation cavity of the internally heated composite baffle plate. Hot air is guided by the internally heated composite baffle plate and returns to the hot air generator through the return air duct, forming a circulation. An electric heating wire is embedded in the hollow ventilation cavity of the internally heated composite baffle plate, and a ceramic valve is provided at the air outlet of the internally heated composite baffle plate.

[0014] The sand inlet preheating device includes a sand inlet preheating channel with a shell-and-tube heat exchange structure. The inner layer of the sand inlet preheating channel is a sand inlet channel, and the outer layer is an annular waste heat channel. The annular waste heat channel is connected in parallel with the return air duct through a three-way valve.

[0015] A comprehensive architecture for a thermal sand mixing equipment with zoned temperature control, online temperature measurement, hot air circulation, and waste heat recovery is constructed. This architecture achieves precise sand temperature control and energy efficiency improvement from multiple dimensions, including structure, heating, temperature measurement, airflow, and waste heat utilization. The principle is to divide the sand mixing cylinder into three functional zones along the axial direction: preheating, sand mixing, and heat preservation. Independent closed-loop temperature control circuits are formed by zoned heating elements and PLC intelligent temperature control units. At the same time, an infrared temperature sensor with integrated micro blackbody calibration and ultrasonic dust removal is configured in the sand mixing zone to directly collect sand temperature data. The internal heating composite guide plate with hollow heating wire and ceramic valve plate realizes coupled heat exchange of "hot air convection + radiation heat conduction". The waste heat of return air is introduced through the sand inlet sleeve heat exchanger to preheat the new sand. The multi-system collaborative approach solves the problems of low heating efficiency, poor temperature control accuracy, and low energy utilization rate of traditional sand mixing equipment.

[0016] Optionally, the internally heated composite baffle plate has an arc-shaped structure and is arranged at intervals along the circumferential side of the inner wall of the sand mixing cylinder; the outlet of the return air channel is connected to the air inlet of the hot air generator through a return air pipe.

[0017] Optimize the flow field distribution and loop integrity of the hot air circulation system to improve the uniformity of hot air heating. The principle is to design the internal heating composite guide plate as an arc-shaped structure that fits the cylinder wall and is arranged at intervals along the circumference. This can guide the hot air to diffuse evenly along the inner wall of the cylinder and fully contact the sand material, avoiding local hot air dead zones. At the same time, the hot air is directly sent back to the air inlet of the hot air generator through the return air duct, forming a complete closed circulation loop and reducing heat loss to the outside.

[0018] Optionally, the control strategy of the PLC intelligent temperature control unit is as follows: at the internal heating composite guide plate corresponding to the preheating zone, the ceramic valve is controlled to open, with hot air convection as the main method and electric heating wire radiation as the auxiliary method; at the internal heating composite guide plate corresponding to the sand mixing zone, the ceramic valve is controlled to close, and the sand is directly radiated and heated by electric heating wire.

[0019] Different heat exchange modes are matched for different process zones, taking into account both the heating rate in the preheating stage and the temperature control stability in the sand mixing stage. The principle is based on the preset strategy of the PLC intelligent temperature control unit. In the preheating zone, the ceramic valve is opened, and the main heating method is hot air convection heat exchange, supplemented by electric heating wire radiation heat conduction. The large-scale flow of hot air is used to quickly increase the temperature of the new sand. In the sand mixing zone, the ceramic valve is closed to block the hot air outflow. The electric heating wire close to the sand flow directly radiates heat, avoiding the hot air flow from carrying away heat and ensuring the accuracy and stability of the sand temperature during the sand mixing process.

[0020] Alternatively, the hot air generator is an electric hot air blower or a gas-fired hot blast stove, and the air outlet of the hot air generator is flanged to the air inlet at the bottom of the sand mixing cylinder through an air inlet pipe.

[0021] Improve the scenario adaptability and connection reliability of the hot air generating unit; the principle is to provide two heat source options of the electric hot air blower and the gas-fired hot blast stove, which can be flexibly selected according to the energy supply conditions of the foundry workshop. At the same time, the flange structure is used to connect the air inlet pipe and the air inlet at the bottom of the cylinder, and the sealing and fastening characteristics of the flange are utilized to ensure the sealing performance during the transportation of high-temperature hot air, and reduce the heat loss and safety hazards caused by hot air leakage.

[0022] Alternatively, it further includes an over-temperature alarm device and a safety protection device, the over-temperature alarm device includes an audible and visual alarm, and the audible and visual alarm is connected to the alarm output port of the PLC intelligent temperature control unit; the safety protection device includes a relay, the control end of the relay is connected to the PLC intelligent temperature control unit, and the normally closed contact of the relay is connected in series in the power supply circuit of the zoned heating element.

[0023] Construct an over-temperature safety protection system for the equipment to improve the reliability and safety of equipment operation; the principle is to connect the audible and visual alarm to the alarm port of the PLC intelligent temperature control unit, and trigger an audible and visual signal to prompt on-site personnel when the monitored regional temperature exceeds the set upper limit; at the same time, the normally closed contact of the relay is connected in series with the power supply circuit of the heating element, and the on-off of the relay is controlled by the PLC. When over-temperature occurs, the power supply of the corresponding heating zone is directly cut off, so as to avoid equipment damage and production accidents caused by over-temperature from two levels of early warning and power-off protection.

[0024] Alternatively, it further includes an automatic sand temperature adjustment system, the automatic sand temperature adjustment system includes a communication interface, the communication interface is connected to the controller of the core making machine through a communication cable, and the communication interface is connected to the data interface of the PLC intelligent temperature control unit.

[0025] Realize the linkage control of the sand mixing equipment and the downstream core making process, and improve the automation degree of the casting production line; the principle is to establish a data transmission link between the PLC intelligent temperature control unit of the sand mixing equipment and the controller of the core making machine through the communication interface. The core making machine can issue sand temperature parameters in real time according to its own production rhythm and process requirements, and the sand mixing equipment automatically matches and adjusts the temperature setting and power output of each heating zone, without manual parameter modification, so as to realize the adaptive matching of sand temperature between upstream and downstream processes.

[0026] Optionally, the miniature blackbody calibration module includes a blackbody target surface integrated into the housing of the infrared temperature sensor. The blackbody target surface is extended to the front of the lens at regular intervals under the control of a PLC intelligent temperature control unit. After comparing the measured value of the blackbody with the set value, the PLC intelligent temperature control unit automatically corrects the temperature measurement deviation, and the blackbody target surface automatically retracts after completion. The ultrasonic oscillation dust removal ring is set on the outer side of the lens of the infrared temperature sensor, and the oscillation frequency is 20-40kHz.

[0027] This system enables automatic calibration and maintenance-free cleaning of infrared temperature sensors, adapting to the high-dust and easily adhesive conditions of foundry workshops. The principle involves integrating a blackbody target surface into the sensor housing. A PLC controls the blackbody target surface to rotate in front of the lens at regular intervals. By comparing the standard temperature of the blackbody with the measured temperature, the offset is calculated and the temperature measurement data is automatically corrected. After calibration, the target surface automatically rotates back without interfering with normal temperature measurement. Simultaneously, a 20-40kHz ultrasonic oscillation dust removal ring is installed on the outer side of the infrared temperature sensor's lens. High-frequency vibration causes the attached dust and water glass adhesive particles to automatically detach, replacing the traditional compressed air purging method and extending the maintenance cycle.

[0028] Optionally, the infrared temperature sensor is a multi-point infrared temperature sensor, arranged in an array along the axial and circumferential directions of the sand mixing cylinder; the blackbody target has a diameter of 8-15 mm, a constant temperature of 80-120℃, and a calibration cycle of 20-40 minutes.

[0029] To improve the spatial coverage and calibration accuracy of sand temperature detection and reduce measurement errors, the principle is to use multi-point infrared temperature sensors arranged in an array along the axial and circumferential directions of the cylinder. This allows for the simultaneous acquisition of sand temperature data from multiple locations in the sand mixing zone, avoiding local deviations caused by single-point temperature measurement. By limiting the blackbody target surface to 8–15 mm in diameter and 80–120 °C with a calibration cycle of 20–40 minutes, a stable temperature reference is provided for infrared temperature measurement. Temperature drift is corrected periodically to ensure measurement accuracy in high-dust environments.

[0030] Optionally, the heating wires are arranged in a serpentine pattern within the hollow ventilation cavity of the internally heated composite baffle.

[0031] The heating uniformity, power supply stability, and heat exchange mode control accuracy of the internal heating composite baffle are improved. The principle is to arrange the heating wire in a serpentine shape in the hollow ventilation cavity to increase the contact area between the heating wire and the ventilation cavity, so that the baffle body and the hot air flowing through it are heated more evenly.

[0032] Optionally, the PLC intelligent temperature control unit controls the switching of the three-way valve: when the temperature of the sand mixing zone reaches the set value, part of the return air is introduced into the annular waste heat channel to preheat the new sand; when the temperature of the sand mixing zone is lower than the set value and needs to be raised, it switches back to the original circulation path, and all the return air returns to the hot air generator. The first passage of the three-way valve is connected to the return air duct, the second passage is connected to the inlet of the annular waste heat channel, and the third passage is connected to the outlet of the annular waste heat channel.

[0033] It realizes the cascade recovery of return air waste heat while ensuring the temperature control priority of the core sand mixing area. The principle is that the PLC intelligent temperature control unit controls the passage switching of the three-way valve according to the temperature state of the sand mixing zone: when the temperature of the sand mixing zone reaches the process set value, part of the high-temperature return air is diverted into the annular waste heat channel at the sand inlet, and the waste heat of the exhaust gas is used to preheat the new sand to reduce the overall energy consumption; when the temperature of the sand mixing zone is lower than the set value and needs to be raised rapidly, the circuit is switched to make all the return air return to the hot air generator for circulating heating, so as to prioritize the temperature demand of the core sand mixing area and achieve a dynamic balance between energy saving and temperature control performance.

[0034] Adopting the technical solution provided by the present invention, compared with the prior art, it has the following beneficial effects:

[0035] Compared with the prior art, the present invention adopts a direct electric heating method to replace the indirect heating of the temperature control medium, which has higher heat exchange efficiency and faster sand temperature adjustment response speed; by dividing the sand mixing cylinder into a preheating zone, a sand mixing zone and a heat preservation zone, and combining with the PLC intelligent temperature control unit to implement independent closed-loop control for each zone, the problem of uneven sand temperature distribution is solved; the infrared temperature measurement sensor feeds back the sand temperature signal in real time, and the temperature control accuracy is significantly improved; the hot air circulation system further improves the heating uniformity inside the cylinder; the heat insulation and preservation layer reduces heat loss and lowers operating energy consumption; the over-temperature alarm and safety protection device improves the operational reliability of the equipment; the sand inlet preheating device shortens the heating time inside the cylinder and improves production efficiency; the communication interface realizes linkage control with the core making machine and enhances the production automation level. Brief Description of the Drawings

[0036] Figure 1 This is one of the viewing angles of the structural schematic diagram of the thermal sand mixing equipment with temperature control and heating function proposed by the embodiment of the present invention;

[0037] Figure 2 This is the second viewing angle of the structural schematic diagram of the thermal sand mixing equipment with temperature control and heating function proposed by the embodiment of the present invention;

[0038] Figure 3 This is a cross-sectional view of the thermal sand mixing equipment with temperature control and heating function proposed by the embodiment of the present invention;

[0039] Figure 4A partial cross-sectional view of a thermal sand mixing device with temperature control heating function proposed in an embodiment of the present invention;

[0040] Figure 5 A partial cross-sectional view of a ceramic valve plate of a thermal sand mixing device with temperature control heating function, as proposed in an embodiment of the present invention;

[0041] Figure 6 A cross-sectional view of an infrared temperature sensor for a thermal sand mixing device with temperature control heating function, as proposed in an embodiment of the present invention;

[0042] Figure 7 A top view of an annular waste heat channel of a thermal sand mixing device with temperature control heating function, as proposed in an embodiment of the present invention;

[0043] 1. Base; 2. Sand mixing cylinder; 3. Sand mixing rotor; 4. Drive motor; 5. Sand inlet; 6. Sand outlet; 7. Air inlet; 8. Preheating zone; 9. Sand mixing zone; 10. Insulation zone; 11. Zoned heating element; 12. Temperature sensor; 13. PLC intelligent temperature control unit; 14. Infrared temperature sensor; 15. Hot air generator; 16. Internally heated composite guide plate; 17. Return air channel; 18. Return air duct; 19. Rotor shaft; 20. Spiral blade; 21. Stirring blade; 22. Heat insulation layer; 23. Sand inlet preheating channel; 24. Preheating heating element; 25. Air outlet; 26. Guide plate air outlet hole; 27. Heating wire; 28. Ceramic valve plate; 29. ​​Blackbody target surface; 30. Ultrasonic oscillation dust removal ring; 31. Annular waste heat channel; 32. Three-way valve. Detailed Implementation

[0044] To further understand the content of this invention, a detailed description of the invention will be provided in conjunction with the accompanying drawings and embodiments.

[0045] Example 1

[0046] like Figure 1-4 As shown, a thermal sand mixing device with temperature control heating function includes a base 1, a sand mixing cylinder 2 fixed on the base 1, and a sand mixing rotor 3 disposed inside the sand mixing cylinder 2. The sand mixing cylinder 2 has a cylindrical structure with a sand inlet 5 at one end, a sand outlet 6 at the other end, and an air inlet 7 at the bottom. The sand mixing rotor 3 includes a rotor shaft 19, which is rotatably connected to the end caps at both ends of the sand mixing cylinder 2 via bearings at both ends. One end of the rotor shaft 19 extends out of the end cap and is connected to a drive motor 4 via a coupling.

[0047] The sand mixing cylinder 2 is divided into three zones along the axial direction: a preheating zone 8 near the sand inlet 5, a middle sand mixing zone 9, and a heat preservation zone 10 near the sand outlet 6. The preheating zone 8 is used to preheat the incoming raw sand, the sand mixing zone 9 is used to maintain a suitable sand temperature during the sand mixing process, and the heat preservation zone 10 is used to keep the sand temperature stable after mixing.

[0048] The electric heating system includes zoned heating elements 11, respectively located on the inner walls of the preheating zone 8, sand mixing zone 9, and insulation zone 10. Each zone's heating element 11 is an electric heating tube assembly, evenly distributed along the circumference of the cylinder. The heating tube assemblies are mounted on the inner wall of the cylinder via fixed brackets. A wear-resistant protective mesh cover is fitted around the outer side of each zone's heating element, and the mesh cover is bolted to the inner wall of the cylinder. The mesh opening is smaller than the sand particle size to prevent direct impact and wear on the heating element from the sand. Each zone is equipped with a corresponding temperature sensor 12, which is a thermocouple installed on the cylinder wall with its probe extending into the cylinder to monitor the ambient temperature of that zone in real time.

[0049] The online sand temperature detection device includes an infrared temperature sensor 14 installed in the sand mixing zone 9. The signal output terminal of the infrared temperature sensor 14 is connected to the signal input terminal of the PLC intelligent temperature control unit 13, and is used to directly detect the actual temperature of the sand during the sand mixing process.

[0050] like Figure 6 As shown, the infrared temperature sensor 14 integrates a miniature blackbody calibration module and an ultrasonic oscillation dust removal ring 30 at its detection end. The miniature blackbody calibration module includes a blackbody target surface 29, which is integrated into the sensor housing and has a diameter of 10mm. It has a built-in constant-temperature heating element to maintain its temperature at 100℃. The PLC intelligent temperature control unit 13 sends a command every 30 minutes to drive the blackbody target surface 29 to automatically rotate in front of the lens, collect the measured blackbody value, compare it with the set value, calculate the offset, and automatically correct subsequent temperature measurement data. After completion, the blackbody target surface 29 automatically retracts. The blackbody target surface 29 is connected to a motor, which is electrically connected to and controlled by the PLC intelligent temperature control unit 13. The ultrasonic oscillation dust removal ring 30 is located on the outer side of the lens of the infrared temperature sensor 14, with an oscillation frequency of 28kHz. Through high-frequency vibration, it removes dust and water glass adhesive particles adhering to the lens surface, replacing the original simple compressed air blowing method and extending the maintenance-free period to more than 3 months.

[0051] The PLC intelligent temperature control unit 13 includes a PLC controller host, signal input ports, and power output ports. The signal lines of the three temperature sensors 12 are respectively connected to the three channels of the signal input port, and the power input terminals of the three groups of zoned heating elements 11 are respectively connected to the three output channels of the power output port. Based on the temperature signals received from the signal input ports and the sand temperature data fed back by the infrared temperature sensors 14, the PLC controller host adjusts the output voltage of each power output port through a built-in control program, thereby controlling the heating power of each zone's heating element 11 and achieving independent and precise closed-loop control of the sand temperature in each zone.

[0052] Example 2

[0053] Based on Embodiment 1, the hot air circulation system includes a hot air generator 15, an air inlet duct, an internally heated composite baffle plate 16, and a return air channel 17. The air outlet 25 of the hot air generator 15 is connected to the air inlet 7 at the bottom of the sand mixing cylinder 2 through an air inlet duct flange, and hot air enters from the bottom of the cylinder.

[0054] The internally heated composite baffle plate 16 has a hollow arc-shaped structure with internal ventilation chambers, arranged circumferentially along the inner wall of the cylinder. Baffle plate outlet holes 26 are spaced apart on the side of the baffle plate facing the center of the cylinder. Air inlets 7 are connected to the ventilation chambers of each baffle plate and to the hollow ventilation chambers of the internally heated composite baffle plate 16. Within the hollow ventilation chambers of the internally heated composite baffle plate 16, serpentine heating wires 27 are embedded. The specifications of the heating wires 27 are the same as those of the original zone heating elements 11. Ceramic valve plates 28 are provided at the air outlet holes 26 of the baffle plate. The opening degree of the ceramic valve plates 28 is adjusted by the PLC intelligent temperature control unit 13 through a control actuator.

[0055] like Figure 5 As shown, the control strategy of the PLC intelligent temperature control unit 13 for the internally heated composite guide plate 16 is as follows: At the guide plate corresponding to the preheating zone 8, the ceramic valve 28 is opened, and hot air is blown out from the air outlet 26. The hot air convection is the main method, and the electric heating wire 27 provides radiative heat conduction as a supplement, to preheat the sand. At the guide plate corresponding to the sand mixing zone 9, the ceramic valve 28 is closed, and the electric heating wire 27 directly radiates heat to the sand, avoiding the hot air from carrying away heat and improving the heating efficiency of the sand mixing zone. Since the internally heated composite guide plate 16 is close to the sand flow (distance ≤ 5cm), the temperature response speed is significantly improved compared to the indirect heat transfer of the original cylinder wall heating element. A rotating shaft is provided in the middle of the ceramic valve 28, which is connected to a micro motor controlled by the PLC intelligent temperature control unit 13. When the signal is triggered, the micro motor is started by the PLC intelligent temperature control unit 13 and rotates to open or close the ceramic valve 28.

[0056] The return air duct 17 is located at the top of the sand mixing cylinder 2. The outlet of the return air duct 17 is connected to the air inlet of the hot air generator 15 through the return air pipe 18. The hot air returns to the hot air generator 15 through the return air duct 17 and the return air pipe 18, forming a hot air circulation loop.

[0057] Example 3

[0058] Based on Embodiment 2, the sand-mixing rotor 3 further includes helical blades 20 and stirring blades 21 disposed on the rotor shaft 19. The helical blades 20 are located in the preheating zone 8 and the sand-mixing zone 9, and are distributed in a spiral shape along the rotor shaft 19 to propel the material forward and perform preliminary mixing. The stirring blades 21 are located in the sand-mixing zone 9 and the heat preservation zone 10, and are evenly distributed circumferentially along the rotor shaft 19 to enhance the mixing effect.

[0059] The infrared temperature sensor 14 is a multi-point infrared temperature sensor. Three sets of detection units are set at axial intervals on the top of the cylinder in the sand mixing zone 9. Each set of detection units has two temperature probes evenly distributed along the circumference of the cylinder. The whole is arranged in an array along the axial and circumference, which can simultaneously collect sand temperature data at different locations in the sand mixing zone, providing multi-dimensional temperature feedback for the PLC intelligent temperature control unit 13.

[0060] The outer wall of the sand mixing cylinder 2 is covered with a heat insulation layer 22, which is made of aluminum silicate fiber felt with a thickness of 50 mm and is fixed to the outer wall of the sand mixing cylinder 2 with a high-temperature resistant adhesive. A stainless steel protective plate is provided on the outside of the heat insulation layer 22.

[0061] The equipment also includes an over-temperature alarm device and a safety protection device. The over-temperature alarm device includes an audible and visual alarm, which is installed on the control cabinet panel, and its input terminal is connected to the alarm output port of the PLC intelligent temperature control unit 13. The safety protection device includes three relays, each corresponding to one of the three heating zones. The normally closed contact of each relay is connected in series in the power supply circuit of the corresponding zone's heating element 11. When the temperature of a certain zone exceeds the set upper limit, the PLC intelligent temperature control unit 13 controls the corresponding relay to activate and cut off the power supply to the heating element 11 of that zone.

[0062] Example 4

[0063] Based on Example 3, the equipment also includes an automatic sand temperature regulation system and an improved sand inlet preheating device.

[0064] The automatic sand temperature control system includes a communication interface module, which is installed in the control cabinet. One end of the module is connected to the PLC controller of the core-making machine via an RS485 communication cable, and the other end is connected to the data interface of the PLC intelligent temperature control unit 13 of this equipment. The core-making machine sends the required sand temperature parameters to the PLC intelligent temperature control unit 13 of the sand mixing equipment via the communication interface according to the actual production process needs. The PLC intelligent temperature control unit 13 automatically adjusts the temperature setpoint and heating power of each zone based on the received sand temperature parameters, achieving intelligent adaptive control of the sand temperature.

[0065] like Figure 7 As shown, the sand inlet preheating channel 23 of the sand inlet preheating device is modified into a shell-and-tube heat exchange structure: the inner layer is the sand inlet channel (keeping the original structure unchanged, the original preheating heating element 24 is retained as auxiliary heating), and the outer layer is the annular waste heat channel 31. The total length of the shell is the same as the original sand inlet preheating channel 23. The annular waste heat channel 31 is connected in parallel with the return air duct 18 through a three-way valve 32, which is controlled and switched by the PLC intelligent temperature control unit 13. When the temperature of the sand mixing zone 9 reaches the standard, the PLC intelligent temperature control unit 13 controls the three-way valve 32 to introduce part of the return air (temperature about 120°C) into the annular waste heat channel 31 to preheat the raw material sand in the inner sand inlet channel, so that the temperature of the new sand entering the cylinder is stabilized at 50-60°C; when the temperature of the sand mixing zone 9 is lower than the set value and needs to be heated, the three-way valve 32 switches back to the original circulation path, and all the return air returns to the hot air generator 15. The waste heat recovery rate is ≥25%, reducing energy consumption per ton of sand by 8-10 kWh, while the temperature fluctuation inside the cylinder is reduced from ±10℃ to ≤±3℃. The first passage of the three-way valve 32 is connected to the return air duct 18, the second passage is connected to the inlet of the annular waste heat channel 31, and the third passage is connected to the outlet of the annular waste heat channel 31.

[0066] The hot air generator 15 can be either an electric hot air blower or a gas-fired hot air furnace. When using an electric hot air blower, the blower has a power of 15 kW, an air volume of 1000 cubic meters per hour, and an adjustable outlet air temperature range of 50 to 150 degrees Celsius. When using a gas-fired hot air furnace, the furnace has a thermal power of 50 kW, an air volume of 1500 cubic meters per hour, and an adjustable outlet air temperature range of 80 to 200 degrees Celsius.

[0067] During operation, raw sand enters the mixing cylinder 2 after being preheated through the sand inlet 5 and the sand preheating channel 23. The drive motor 4 drives the mixing rotor 3 to rotate, mixing the materials. The heating elements 11 in the preheating zone 8 and the heating wires 27 of the corresponding internally heated composite guide plate 16 preheat the materials. In the mixing zone 9, the ceramic valve plate 28 of the corresponding internally heated composite guide plate 16 is closed, and the heating wires 27 directly radiate heat to the sand, maintaining a stable temperature during the mixing process. The heating elements 11 in the insulation zone 10 maintain the temperature of the material after mixing. An infrared temperature sensor 14 monitors the sand temperature in real time, a micro blackbody calibration module performs periodic self-calibration, an ultrasonic oscillation dust removal ring 30 continuously cleans the lens, and a PLC intelligent temperature control unit 13 adjusts the heating power of each zone according to the real-time temperature signal to achieve precise control of the sand temperature. The mixed material is discharged from the sand outlet 6.

[0068] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A thermal sand mixing device with temperature control heating function, comprising a base, a sand mixing cylinder, and a sand mixing rotor disposed within the sand mixing cylinder, wherein one end of the sand mixing cylinder has a sand inlet and the other end has a sand outlet, the sand mixing rotor is rotatably connected to the sand mixing cylinder via bearings, and one end of the sand mixing rotor is connected to a drive motor; characterized in that, The sand mixing cylinder is divided into a preheating zone, a sand mixing zone, and a heat preservation zone along the axial direction. The electric heating system includes zoned heating elements respectively located in the preheating zone, sand mixing zone and heat preservation zone, as well as temperature sensors arranged for each heating zone; The PLC intelligent temperature control unit has its signal input terminal connected to the temperature sensor and its power output terminal connected to the power input terminal of each zone heating element. The sand temperature online detection device includes an infrared temperature sensor installed in the sand mixing zone. The signal output terminal of the infrared temperature sensor is connected to the signal input terminal of the PLC intelligent temperature control unit. The detection terminal of the infrared temperature sensor integrates a miniature blackbody calibration module and an ultrasonic oscillation dust removal ring. A hot air circulation system includes a hot air generator, an internally heated composite baffle plate disposed inside a sand mixing cylinder, and a return air duct disposed at the top of the sand mixing cylinder. The bottom of the sand mixing cylinder has an air inlet, and the air outlet of the hot air generator is connected to the air inlet via the air inlet duct. The air inlet is connected to the hollow ventilation cavity of the internally heated composite baffle plate. Hot air is guided by the internally heated composite baffle plate and returns to the hot air generator through the return air duct, forming a circulation. An electric heating wire is embedded in the hollow ventilation cavity of the internally heated composite baffle plate, and a ceramic valve is provided at the air outlet of the internally heated composite baffle plate. The sand inlet preheating device includes a sand inlet preheating channel with a shell-and-tube heat exchange structure. The inner layer of the sand inlet preheating channel is a sand inlet channel, and the outer layer is an annular waste heat channel. The annular waste heat channel is connected in parallel with the return air duct through a three-way valve.

2. The thermal sand mixing equipment with temperature control heating function according to claim 1, characterized in that, The internally heated composite baffle plate has an arc-shaped structure and is arranged at intervals along the circumference of the inner wall of the sand mixing cylinder; the outlet of the return air channel is connected to the air inlet of the hot air generator through a return air pipe.

3. The thermal sand mixing equipment with temperature control heating function according to claim 1, characterized in that, The control strategy of the PLC intelligent temperature control unit is as follows: at the internal heating composite guide plate corresponding to the preheating zone, the ceramic valve is controlled to open, with hot air convection as the main method and electric heating wire radiation as the auxiliary method; at the internal heating composite guide plate corresponding to the sand mixing zone, the ceramic valve is controlled to close, and the sand is directly radiated and heated by electric heating wire.

4. The thermal sand mixing equipment with temperature control heating function according to claim 1 or 2, characterized in that, The hot air generator is an electric hot air blower or a gas-fired hot air furnace, and the air outlet of the hot air generator is connected to the air inlet at the bottom of the sand mixing cylinder through an air inlet pipe flange.

5. The thermal sand mixing equipment with temperature control heating function according to claim 1, characterized in that, It also includes an over-temperature alarm device and a safety protection device. The over-temperature alarm device includes an audible and visual alarm, which is connected to the alarm output port of the PLC intelligent temperature control unit. The safety protection device includes a relay, the control terminal of which is connected to the PLC intelligent temperature control unit, and the normally closed contact of which is connected in series in the power supply circuit of the zone heating element.

6. The thermal sand mixing equipment with temperature control heating function according to claim 1, characterized in that, It also includes an automatic sand temperature control system, which includes a communication interface. The communication interface is connected to the controller of the core-making machine via a communication cable, and the communication interface is connected to the data interface of the PLC intelligent temperature control unit.

7. The thermal sand mixing equipment with temperature control heating function according to claim 1, characterized in that, The miniature blackbody calibration module includes a blackbody target surface, which is integrated into the housing of the infrared temperature sensor and extends to the front of the lens at regular intervals under the control of a PLC intelligent temperature control unit. After comparing the measured value of the blackbody with the set value, the PLC intelligent temperature control unit automatically corrects the temperature measurement deviation, and the blackbody target surface automatically retracts after completion. The ultrasonic oscillation dust removal ring is set on the outside of the lens of the infrared temperature sensor, and the oscillation frequency is 20-40kHz.

8. The thermal sand mixing equipment with temperature control heating function according to claim 7, characterized in that, The infrared temperature sensor is a multi-point infrared temperature sensor, arranged in an array along the axial and circumferential directions of the sand mixing cylinder; the blackbody target has a diameter of 8-15 mm, a constant temperature of 80-120℃, and a calibration cycle of 20-40 minutes.

9. The thermal sand mixing equipment with temperature control heating function according to claim 1, characterized in that, The heating wires are arranged in a serpentine pattern inside the hollow ventilation cavity of the internally heated composite guide plate.

10. The thermal sand mixing equipment with temperature control heating function according to claim 1, characterized in that, The PLC intelligent temperature control unit controls the switching of the three-way valve: when the temperature in the sand mixing zone reaches the set value, part of the return air is introduced into the annular waste heat channel to preheat the new sand; when the temperature in the sand mixing zone is lower than the set value and needs to be raised, the valve switches back to the original circulation path, and all the return air returns to the hot air generator. The first passage of the three-way valve is connected to the return air pipe, the second passage is connected to the inlet of the annular waste heat channel, and the third passage is connected to the outlet of the annular waste heat channel.

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