Air heater for core making

Abstract

The utility model discloses an air heater, which comprises a shell, an electric heating pipe, an air inlet pipe, an air outlet pipe and an air flow channel, and is characterized in that high-temperature oil is filled in the shell, the air flow channel is a spiral pipe immersed in the high-temperature oil, and a heating part of the electric heating pipe is positioned in the high-temperature oil. According to the utility model, the fit clearance between the radiator and the heating pipe is avoided, the contact thermal resistance in the heat transfer process is reduced, the service life of the heating pipe is prolonged, the heat exchange efficiency is improved, and accurate temperature control is convenient to realize.

Description

Technical Field

[0001] The utility model relates to air heating equipment used in the casting field, in particular to an air heater used for gasifying triethylamine in a core making process. Background Art

[0002] Sand core forming is an important process step in the casting process. Sand core forming processes include inorganic processes and organic processes. Commonly used organic core making processes include hot core box method, coated sand shell method and triethylamine cold core box method. The triethylamine cold core box method is suitable for multi-variety production due to its long service life and flexible replacement of the core box at any time, especially for sand cores with high precision requirements and thicker cross-sections.

[0003] The triethylamine cold core method (cold core process) uses triethylamine as a catalyst to solidify the sand core. In order to obtain stable triethylamine gas, the compressed hot air must be heated to a set temperature, and then the high-temperature hot air vaporizes a certain amount of triethylamine liquid. The vaporized triethylamine catalytically solidifies the sand core. In addition, the inorganic process also requires the provision of stable high-temperature hot air, which acts on the sand core to dehydrate and solidify it.

[0004] Therefore, continuous and stable high-temperature compressed air is the guarantee to meet the core making process requirements of inorganic process and cold core process.

[0005] Traditional heaters generally use metal heat sinks to store heat, and then convect the heat to the compressed air. The air convection flow channel has a small heat exchange area, and the complex flow channel causes a large pressure loss on the compressed air. Chinese utility model patent CN215983229U discloses a miniaturized air heater, including a cylindrical heater core and a tubular heater shell fitted on its outer wall. The outer wall of the heater core near one end is vertically provided with an air inlet pipe, and the outer wall of the heater core near the other end is vertically provided with an air outlet pipe. The outer wall of the heater core is spirally wound to open a spiral groove connecting the air inlet pipe and the air outlet pipe. The central axis of the heater core is inserted with an electric heating rod, and the electric heating rod is also connected to a thermostat.

[0006] This technical solution reduces the air flow resistance by setting spiral grooves to form an air flow channel, and can achieve a relatively good heating effect with a smaller heater volume. However, this structure needs to store heat through a metal heat sink, and then convect the heat to the compressed air. There is a matching gap between the heating rod and the heat sink, and it cannot be eliminated. This gap causes the contact thermal resistance between the heating rod and the heat sink to increase sharply, reducing the thermal conductivity efficiency and easily causing the heating rod to run away from high temperature and be damaged, reducing the life of the heating rod. At the same time, because it is metal heat conduction, its temperature field distribution is cold on the outside and hot on the inside, and as the wall thickness of the heat sink increases, the thermal resistance increases, greatly reducing the heat transfer efficiency, and the temperature measuring element is set at one end of the electric heating rod, and the temperature detection feedback accuracy is low.

[0007] Therefore, it is necessary to improve the structure of the air heater to solve the above problems. Summary of the invention

[0008] The purpose of the invention of the utility model is to provide an air heater, which solves the thermal resistance problem caused by the matching gap between the heat sink and the heating tube in the prior art through structural design, while improving the temperature detection and control accuracy.

[0009] In order to achieve the above-mentioned purpose of the invention, the technical solution adopted by the utility model is: an air heater, including a shell, an electric heating tube, an air inlet pipe, an air outlet pipe and an air flow channel, the shell is filled with high-temperature oil, the air flow channel is a spiral tube immersed in the high-temperature oil, and the heating part of the electric heating tube is located in the high-temperature oil.

[0010] According to a preferred technical solution, the shell is composed of a cylindrical barrel and a barrel cover, and an air chamber is formed between the high-temperature oil in the barrel and the barrel cover.

[0011] In the above technical solution, the electric heating tube is installed in the center of the cylinder cover and inserted into the high-temperature oil in the cylinder body, and the spiral tube is arranged around the electric heating tube.

[0012] According to a preferred technical solution, the air inlet pipe and the air outlet pipe are arranged on the cylinder cover, the air inlet pipe is connected to the lower end of the spiral tube, and the air outlet pipe is connected to the upper end of the spiral tube.

[0013] According to a further technical solution, the outer periphery of the cylinder is coated with a heat-insulating wall.

[0014] In the above technical solution, an oil inlet is provided on the cylinder cover, and an oil outlet is provided at the bottom of the cylinder body.

[0015] Optionally, a high-temperature circulation pump is provided to force the high-temperature oil in the cylinder to circulate.

[0016] Alternatively, a high temperature oil stirring mechanism is provided in the cylinder body to force the high temperature oil to flow, thereby achieving the purpose of uniform temperature distribution of the high temperature oil.

[0017] In the above technical solution, a thermocouple is provided, and the temperature measuring part of the thermocouple is located in the high-temperature oil.

[0018] In the above technical solution, an exhaust valve is provided on the cylinder cover.

[0019] In the utility model, the high-temperature oil is immersed in the heating section of the heating tube during operation, and a certain volume of air chamber is reserved. The purpose of the air chamber is to use the high-pressure property of the air to compensate for the volume changes of the liquid, air spiral tube, heating tube, etc. in the heater at high temperature. After power is turned on, the heat released by the heating tube is directly convected to the high-temperature oil, and then the heat stored in the high-temperature oil is transferred to the air spiral tube through which the compressed air flows. In the air spiral tube, the compressed air and the air spiral tube wall perform convective heat exchange, thereby achieving the purpose of heating the air. The electric heating tube can be a resistive heating tube.

[0020] Due to the application of the above technical solution, the utility model has the following advantages compared with the prior art:

[0021] 1. The utility model uses high-temperature oil as the medium, avoids the matching gap between the radiator and the heating tube, reduces the contact thermal resistance during the heat transfer process, and thus increases the life of the heating tube.

[0022] 2. The utility model replaces the traditional grooved air flow channel with a spiral tube structure. The air flows in the spiral tube, and the air is heated by heat exchange between the spiral tube wall and the high-temperature oil, which reduces the air flow resistance and improves the heat exchange efficiency.

[0023] 3. The utility model uses high-temperature oil as the medium, avoids the problem of uneven temperature field distribution caused by the external structure of the heat sink, and improves the heat exchange efficiency.

[0024] 4. The utility model can immerse the thermocouple in high-temperature oil, thereby improving the temperature detection accuracy and facilitating accurate temperature control. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a structural schematic diagram of an embodiment of the utility model.

[0026] Among them: 1. Cylinder body; 2. Cylinder cover; 3. High-temperature oil; 4. Air chamber; 5. Electric heating tube; 6. Spiral tube; 7. Air inlet pipe; 8. Air outlet pipe; 9. Insulation wall; 10. Oil inlet; 11. Oil outlet; 12. Exhaust valve; 13. Thermocouple. DETAILED DESCRIPTION

[0027] The utility model is further described below in conjunction with the accompanying drawings and embodiments:

[0028] Example 1: See Figure 1As shown, an air heater comprises a shell, an electric heating tube 5, an air inlet tube 7, an air outlet tube 8 and an air flow channel.

[0029] In this embodiment, the shell is composed of a cylindrical barrel 1 and a barrel cover 2. High-temperature oil 3 is poured into the barrel 1. An air chamber 4 is formed between the high-temperature oil 3 and the barrel cover 2. The outer periphery of the barrel 1 is covered with a heat-insulating wall 9. The electric heating tube 5 is installed in the center of the barrel cover 2, and the heating part of the electric heating tube 5 is inserted into the high-temperature oil 3 in the barrel.

[0030] The main body of the air flow channel in this embodiment is a spiral tube 6. The spiral tube 6 is arranged around the electric heating tube 5, and the air inlet tube 7 and the air outlet tube 8 are arranged on the cylinder cover 2. The air inlet tube 7 is connected to the lower end of the spiral tube 6, and the air outlet tube 8 is connected to the upper end of the spiral tube 6. Therefore, the air to be heated enters from the air inlet tube 7, goes down to the bottom of the high-temperature oil 3, enters the spiral tube 6, exchanges heat during the upward movement, and finally flows out through the air outlet tube 8.

[0031] In this embodiment, the cylinder cover is provided with an oil inlet 10 and an exhaust valve 12, and the bottom of the cylinder body is provided with an oil outlet 11. A thermocouple 13 can be installed on the cylinder cover, and the temperature measuring part of the thermocouple 13 is located in the high-temperature oil.

[0032] According to needs, mechanical agitation or high-temperature circulation pump can be selected to force the high-temperature oil to flow, so as to achieve the purpose of uniform distribution of the high-temperature oil temperature.

[0033] This embodiment uses oil as the heat transfer medium, avoids contact gaps, improves temperature detection accuracy, improves heat exchange efficiency, and increases the service life of the heating tube. At the same time, a spiral tube is used to guide air flow, reduce air flow resistance, and improve heat exchange efficiency.

Claims

1. An air heater, comprising a housing, an electric heating tube, an air inlet tube, an air outlet tube and an air flow channel, characterized in that: The shell is filled with high-temperature oil, the air flow channel is a spiral tube immersed in the high-temperature oil, and the heating part of the electric heating tube is located in the high-temperature oil.

2. The air heater according to claim 1, characterized in that: The shell is composed of a cylindrical barrel and a barrel cover, and an air chamber is formed between the high-temperature oil in the barrel and the barrel cover.

3. The air heater according to claim 2, characterized in that: The electric heating tube is installed in the center of the cylinder cover and inserted into the high-temperature oil in the cylinder body. The spiral tube is arranged around the electric heating tube.

4. The air heater according to claim 2, characterized in that: The air inlet pipe and the air outlet pipe are arranged on the cylinder cover, the air inlet pipe is connected to the lower end of the spiral pipe, and the air outlet pipe is connected to the upper end of the spiral pipe.

5. The air heater according to claim 2, characterized in that: The outer periphery of the cylinder is coated with a heat-insulating wall.

6. The air heater according to claim 2, characterized in that: An oil inlet is arranged on the cylinder cover, and an oil outlet is arranged at the bottom of the cylinder body.

7. The air heater according to claim 6, characterized in that: A high-temperature circulation pump is provided to force the high-temperature oil in the cylinder to circulate.

8. The air heater according to claim 6, characterized in that: A high-temperature oil stirring mechanism is arranged in the cylinder.

9. The air heater according to claim 1, characterized in that: A thermocouple is provided, and a temperature measuring portion of the thermocouple is located in the high-temperature oil.

10. The air heater according to claim 2, characterized in that: The cylinder cover is provided with an exhaust valve.

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