Method for preparing foaming products in microwave heating mode

Abstract

The invention relates to the technical field of foamed product preparation, and discloses a method for preparing a foamed product in a microwave heating mode, which comprises the following steps: S1, a 3D printing technology is adopted, ABS (Acrylonitrile Butadiene Styrene) plastic is used as a material to prepare a mold initial blank, the thickness of a printing layer is 0.1-0.2 mm, the printing temperature is 230-250 DEG C, and the printing speed is 30-50 mm / s; and S2, numerical control finish machining is conducted on the mold initial blank, the machining precision is controlled to be + / -0.05 mm, and the mold is obtained. According to the method for preparing the foamed product in the microwave heating mode, a mold is prepared by combining a 3D printing technology with numerical control finish machining, ABS plastic is used as a mold material, high-precision forming of a mold initial blank is ensured by accurately controlling parameters such as the thickness of a printing layer, the temperature and the speed, and then the precision requirement of + / -0.05 mm is met through numerical control finish machining; the waste of a large amount of aluminum materials is avoided, and a complex steam heating system and related equipment thereof are omitted, so that the production cost is reduced, the production process is simplified, and the production efficiency is improved.

Description

Technical Field

[0001] The invention relates to the technical field of foaming product preparation, in particular to a method for preparing a foaming product by microwave heating. Background Art

[0002] In the production of foam products, the traditional process relies on steam to heat the foaming raw materials to prepare products. After the foaming raw materials expand, they fill the mold cavity to obtain products that meet the shape and size of the drawings.

[0003] However, the steam heating method leads to the disadvantages of existing production:

[0004] Disadvantage 1: The foam raw materials need to be pre-foamed once in a pre-expander before they can be expanded by water vapor;

[0005] Disadvantage 2: Water steam requires a boiler. The fuel burned by the boiler (such as natural gas, biomass) requires a large investment in related equipment. At the same time, the boiler is a special safety equipment that requires professional certified personnel to use. There are many safety precautions during production. Fuel needs to be burned and exhaust gas needs to be discharged, which makes environmental protection approval difficult.

[0006] Disadvantage 3: The mold is in a high-temperature steam environment, and the manual operation environment is harsh;

[0007] Disadvantage 4: The water produced after the water vapor is cooled needs to be discharged in accordance with environmental standards, and environmental protection needs to meet the standards;

[0008] Disadvantage 5: The final product produced in a water vapor environment will absorb and carry a lot of water. The product needs to be specially built in an electrical drying room or a heating drying room to drain the water from the final product, which is actually an equipment investment;

[0009] Disadvantage 6: Because the mold is used in a water environment, it can only be made of aluminum, a metal material that will not rust. Aluminum is expensive. The aluminum is processed into the shape of the mold cavity using a CNC machine tool. The process of digging (processing) the cavity will consume about 30% of the raw material, which is wasted in aluminum cutting;

[0010] Disadvantage 7: After the mold is made of aluminum, considering that steam is needed to heat the foaming raw materials, the mold must be equipped with a steam plug. Considering that the mold needs to be cooled after heating, cold water is also needed to cool the mold. High-temperature steam and cold water appear alternately, and the production environment is full of water. Workers wear raincoats and rubber shoes to work.

[0011] Disadvantage 8: If there are many production links, the production cycle will be long. Currently, people in the industry are complaining about the long production cycle and long waiting time.

[0012] The current production method of foaming products, although the core purpose is only to expand the foaming raw materials to fill the mold cavity, but due to the reliance on water vapor heating, it causes many problems. The generation of water vapor depends on boilers, which are explosive special equipment and require professional certified personnel to operate. In addition, the large storage of combustion raw materials also hides safety hazards. Not only that, the production process of water vapor heating is complicated and covers many links. Each link requires the purchase of special equipment, such as pre-expanders, steam boilers, cooling systems, etc., which greatly increases the equipment investment cost. Moreover, the operation and maintenance of each link require the employment of full-time personnel, and the labor cost increases accordingly. The accumulation of a large number of production links has greatly extended the production cycle, seriously restricted production efficiency, and reduced the competitiveness of products in the market. Therefore, we proposed a method for preparing foaming products by microwave heating. Summary of the invention

[0013] 1. Technical issues to be resolved

[0014] In view of the shortcomings of the prior art, the present invention provides a method for preparing foaming products by microwave heating, which has the advantages of simplifying the production process, reducing production costs, and improving production efficiency, and solves the current production method of foaming products. Although the core purpose is only to expand the foaming raw materials to fill the mold cavity, it can cause many problems due to its reliance on water vapor heating. The generation of water vapor depends on boilers, which are explosive special equipment and require professional certified personnel to operate. In addition, the large-scale storage of combustion raw materials also hides safety hazards. Moreover, the production process of water vapor heating is complicated and covers many links. Special equipment must be purchased for each link, such as pre-expanders, steam boilers, cooling systems, etc., which greatly increases the equipment investment cost. Moreover, the operation and maintenance of each link require the employment of full-time personnel, and the labor cost increases accordingly. The accumulation of a large number of production links has greatly extended the production cycle, seriously restricted the production efficiency, and reduced the competitiveness of the product in the market.

[0015] (II) Technical solution

[0016] In order to achieve the above-mentioned purpose of simplifying the production process, reducing production costs and improving production efficiency, the present invention provides the following technical solution: a method for preparing a foamed product by microwave heating, comprising the following steps:

[0017] S1. Use 3D printing technology to prepare the mold blank with ABS plastic as the material, where the printing layer thickness is 0.1mm-0.2mm, the printing temperature is 230℃-250℃, and the printing speed is 30mm / s-50mm / s;

[0018] S2, performing CNC finishing on the mold blank, with the machining accuracy controlled within ±0.05 mm, to obtain the mold;

[0019] S3, placing expandable polystyrene particles with a particle size of 0.5 mm-1.5 mm as foaming raw materials evenly in the mold;

[0020] S4, placing the mold containing the foaming raw material into a microwave heating device with a microwave frequency of 2450MHz and a power of 2kW-5kW and heating for 5min-10min, so that the foaming raw material expands and fills the mold cavity;

[0021] S5. Use air cooling to cool the mold. The air cooling speed is 3m / s-5m / s. The cooling time is 10min-15min. When the mold is cooled to below 50℃, take out the foaming product.

[0022] Preferably, the 3D printing technology adopts a combination of layered printing and a path optimization algorithm. The layered printing algorithm automatically calculates the printing thickness and contour of each layer according to the shape and size of the mold. The path optimization algorithm optimizes the movement path of the print head to reduce empty strokes during the printing process.

[0023] Preferably, before placing the foaming raw material in the mold, the foaming raw material is dried for 2h-3h in an environment with a vacuum degree of -0.08MPa--0.09MPa and a temperature of 60°C-70°C.

[0024] Preferably, a temperature sensor is provided inside the microwave heating device. When the temperature of the foaming raw material in the mold reaches 120° C.-130° C., the power of the microwave heating device is automatically reduced to 1kW-2kW, and heating is continued for 1min-2min.

[0025] Preferably, the inner surface of the mold is provided with a silicone release agent coating with a thickness of 0.01 mm-0.03 mm.

[0026] Preferably, during the air cooling process, negative ions are added to the cooling air, with a negative ion concentration of 1000 ions / cm 3 -2000ions / cm 3 .

[0027] Preferably, the microwave heating equipment is provided with a stirring device, and during the heating process, the stirring device stirs the foaming raw material in the mold at a rotation speed of 10r / min-20r / min.

[0028] Preferably, the taken-out foam products are subjected to quality inspection, and the inspection items include dimensional accuracy, density uniformity and appearance quality. When the product dimensional deviation is within ±0.5mm, the density deviation is within ±5% and there is no obvious defect in appearance, the product is judged to be qualified.

[0029] (III) Beneficial effects

[0030] Compared with the prior art, the present invention provides a method for preparing foam products by microwave heating, which has the following beneficial effects:

[0031] 1. The method of preparing foam products by microwave heating adopts 3D printing technology combined with CNC finishing to prepare molds, replacing the complex processing process of traditional aluminum molds. Specifically, ABS plastic is used as the mold material, and the high-precision molding of the mold blank is ensured by accurately controlling parameters such as printing layer thickness, temperature and speed. The precision requirement of ±0.05mm is then achieved through CNC finishing. Compared with traditional methods, this process avoids a large amount of aluminum waste and eliminates the complex steam heating system and its related equipment. Therefore, it not only reduces production costs, but also simplifies the production process and improves production efficiency.

[0032] 2. The method of preparing foamed products by microwave heating replaces the traditional steam heating method with microwave heating, and shows unique advantages in the expansion process of foaming raw materials. A temperature sensor is provided inside the microwave heating equipment to monitor the temperature change of the foaming raw materials in the mold in real time. When the temperature reaches 120℃-130℃, the equipment automatically adjusts the power to 1kW-2kW to continue heating, ensuring uniform foaming and reducing local density differences. In addition, microwaves have strong penetrability and can quickly and evenly heat the foaming raw materials, causing the raw materials to expand rapidly and fill the mold cavity. Compared with steam heating, it is more efficient and stable, effectively shortening the production cycle and improving the consistency of product quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a schematic diagram of the method flow of the present invention. DETAILED DESCRIPTION

[0034] The following will be combined with the embodiments of the present invention and the accompanying drawings to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] See also Figure 1 The method for preparing a foaming product by microwave heating comprises the following steps:

[0036] S1. Use 3D printing technology to prepare the mold blank with ABS plastic as the material, where the printing layer thickness is 0.1mm-0.2mm, the printing temperature is 230℃-250℃, and the printing speed is 30mm / s-50mm / s;

[0037] S2, performing CNC finishing on the mold blank, with the machining accuracy controlled within ±0.05 mm, to obtain the mold;

[0038] S3, placing expandable polystyrene particles with a particle size of 0.5 mm-1.5 mm as foaming raw materials evenly in the mold;

[0039] S4, placing the mold containing the foaming raw material into a microwave heating device with a microwave frequency of 2450MHz and a power of 2kW-5kW and heating for 5min-10min, so that the foaming raw material expands and fills the mold cavity;

[0040] S5. Use air cooling to cool the mold. The air cooling speed is 3m / s-5m / s. The cooling time is 10min-15min. When the mold is cooled to below 50℃, take out the foaming product.

[0041] Embodiment 1:

[0042] The mold blank is prepared by 3D printing technology, and a high-precision 3D printer is selected. Printing is carried out in a combination of layered printing and path optimization algorithm. The layered printing algorithm accurately calculates the printing thickness and contour of each layer according to the designed mold 3D model. For example, for a mold with complex shape, the algorithm automatically adjusts the printing thickness to 0.1mm in the area with large corners and arcs of the model to ensure the accurate presentation of model details; in relatively flat areas, the printing thickness is set to 0.2mm to improve printing efficiency. The path optimization algorithm intelligently plans the movement path of the print nozzle to reduce empty strokes. During the printing process, the nozzle moves quickly according to the optimized path, avoiding unnecessary round trips, and improving printing efficiency by about 20%. The printing material is ABS plastic, and the printing temperature is controlled at 230℃. At this temperature, ABS plastic has good fluidity and molding properties, which can ensure close bonding between printed layers. The printing speed is set to 30mm / s. The slower speed helps to improve printing accuracy and reduce layer patterns.

[0043] After printing is completed, the mold blank is CNC finished. High-precision CNC processing equipment is used to perform fine processing according to the preset processing accuracy of ±0.05mm. During the processing, multiple measurements and fine-tuning are performed to ensure the dimensional accuracy and surface quality of the mold. For example, a high-precision three-dimensional coordinate measuring instrument is used to measure the key dimensions of the mold in real time. Once the dimensional deviation is found, the processing parameters are adjusted immediately to ensure that the dimensional error of the mold cavity is controlled within a very small range. After processing is completed, a silicone release agent coating with a thickness of 0.01mm is evenly sprayed on the inner surface of the mold. During the spraying process, professional spray gun equipment is used to adjust the pressure and spray angle of the spray gun to ensure that the release agent evenly covers the mold surface and forms a complete and uniform coating, which provides a guarantee for the smooth demolding of the subsequent foaming raw materials.

[0044] Foaming raw material processing: expandable polystyrene particles with a particle size of 0.5mm-1.5mm are selected as foaming raw materials. Before placing them in the mold, they are dried. Use vacuum drying equipment to adjust the vacuum degree of the drying environment to -0.08MPa, set the temperature to 60℃, and dry for 2h. In a vacuum environment, moisture can evaporate more quickly from the raw material particles, avoiding moisture from affecting the foaming effect during the foaming process and ensuring the quality stability of the product.

[0045] Microwave heating foaming: Pour the processed foaming raw materials evenly into the mold, and then put the mold with the foaming raw materials into a microwave heating device with a microwave frequency of 2450MHz and a power of 2kW. The temperature sensor inside the microwave heating device monitors the temperature changes of the foaming raw materials in the mold in real time. The working principle of microwaves is to use high-frequency electromagnetic waves to interact with polar molecules such as water molecules in the foaming raw materials, causing the polar molecules to vibrate and rub rapidly, thereby generating heat. When the temperature reaches 120°C, the power of the microwave heating device automatically drops to 1kW, and heating continues for 1 minute. During the heating process, microwaves evenly penetrate the mold and the foaming raw materials, causing the raw materials to quickly absorb energy and expand. Due to the uniformity of microwave heating, the foaming raw materials can expand more evenly in the mold, reducing local density differences.

[0046] Cooling and product removal: After foaming, the mold is cooled by air cooling. Special air cooling equipment is used to adjust the air cooling speed to 3m / s. During the cooling process, negative ions are added to the cooling air, and the negative ion concentration is controlled at 1000i ons / cm 3 Negative ions can improve the fluidity and heat dissipation of air, making the cooling of the mold more uniform. At the same time, it helps to reduce static adsorption on the surface of the product and improve the surface quality of the product. The cooling time is 10 minutes. When the mold is cooled to below 50°C, open the mold and take out the foaming product.

[0047] Quality inspection: The foam products taken out are strictly inspected for quality. High-precision measuring tools, such as calipers and micrometers, are used to measure the dimensional accuracy of the products. For example, for a product with a size requirement of 100mm×50mm×30mm, the dimensional deviations of its length, width and height are all within ±0.5mm, which meets the quality standards. The density of different parts of the product is measured and the density deviation is calculated. The density deviation of the product is within ±5%, indicating that the density uniformity of the product is good. The appearance quality of the product is evaluated by visual inspection to check whether there are obvious defects such as cracks, bubbles, deformation, etc. on the surface of the product. After inspection, the product has no obvious defects in appearance and is determined to be a qualified product.

[0048] Embodiment 2:

[0049] This example explores the effect of different drying conditions on the performance of the final foamed product, and further verifies the importance of drying in the entire preparation process and the optimal parameter range.

[0050] Experimental material preparation:

[0051] A plurality of groups of expandable polystyrene particles with a particle size of 0.5 mm-1.5 mm are selected as foaming raw materials, and a plurality of molds of the same specifications are prepared. These molds are prepared according to the 3D printing and CNC finishing process described in claim 1 to ensure the consistency of the molds. At the same time, microwave heating equipment, air cooling equipment, vacuum drying equipment and other instruments required for the experiment are prepared.

[0052] Experimental groups and treatments:

[0053] The foaming raw materials are divided into three groups. The first group is dried for 2 hours in an environment with a vacuum degree of -0.08MPa and a temperature of 60°C according to the conditions in claim 3; the second group adjusts the drying conditions and is dried for 2.5 hours in an environment with a vacuum degree of -0.085MPa and a temperature of 65°C; the third group is dried for 3 hours in an environment with a vacuum degree of -0.09MPa and a temperature of 70°C.

[0054] Preparation of foaming products:

[0055] The three groups of dried foaming raw materials are respectively placed evenly in the mold, and the foaming products are prepared according to the microwave heating, cooling and other processes described in claim 1, that is, they are placed in a microwave heating device with a microwave frequency of 2450 MHz and a power of 3 kW for heating for 7 minutes. When the temperature of the foaming raw materials in the mold reaches 125°C, the power of the microwave heating device is automatically reduced to 1.5 kW, and heating is continued for 1.5 minutes. The mold is then cooled by air cooling, the air cooling speed is 4 m / s, and the cooling time is 12 minutes. During the cooling process, negative ions are added to the cooling air, and the negative ion concentration is 1500i ons / cm.

[0056] Performance testing and result analysis: Comprehensive performance testing was conducted on three groups of foaming products. The specific test results are shown in the following table:

[0057]

[0058] From the data in the table, it can be seen that in terms of dimensional accuracy, high-precision calipers and laser measuring instruments are used to measure the key dimensions of the products. The dimensional deviations of the three groups of products are all within ±0.5mm, but there are subtle differences in the dimensions of products that have undergone different drying treatments. Among them, the dimensional accuracy of the third group of products is slightly higher than that of the other two groups. This may be because more sufficient drying reduces the effect of moisture on expansion uniformity during the foaming process. In the density uniformity test, by measuring the density of different parts of the product and calculating the deviation, the results show that with the increase of drying vacuum, the increase of temperature and the extension of time, the density uniformity of the product is improved. This is because more thorough drying removes more moisture and volatile substances that affect foaming uniformity.

[0059] During the appearance quality inspection, a magnifying glass and visual inspection equipment were used to observe the product surface. The first group of products had a small number of tiny pores on the surface, the second group had fewer pores, and the third group of products had the smoothest and flattest surface. This further proves that appropriate drying treatment can optimize the foaming process and reduce product surface defects.

[0060] Embodiment three:

[0061] This example explores the effects of different rotation speeds of a stirring device in a microwave heating device on the foaming uniformity of a foamed product, and clarifies the mechanism of action and the optimal rotation speed range of the stirring device in the microwave heating foaming process.

[0062] Experimental materials and equipment preparation:

[0063] Prepare multiple groups of expandable polystyrene particles with a particle size of 0.5mm-1.5mm, multiple molds of the same specifications (made according to the mold preparation process), microwave heating equipment (the speed of the stirring device of the equipment can be accurately adjusted), air cooling equipment, etc.

[0064] Experimental grouping and condition setting:

[0065] The experiment was divided into three groups. In the first group, during the microwave heating process, the stirring device stirred the foaming raw materials in the mold at a speed of 10 r / min; the stirring device speed of the second group was set to 15 r / min; the speed of the third group was 20 r / min. Other preparation conditions were set in accordance with claim 1, that is, the microwave frequency was 2450 MHz, the power was 4 kW, and the heating time was 8 min. When the temperature of the foaming raw materials in the mold reached 128°C, the power of the microwave heating equipment was automatically reduced to 1.8 kW, and heating was continued for 1.8 min. During cooling, the wind speed was 4.5 m / s, the cooling time was 13 min, and the negative ion concentration in the cooling air was 1800i ons / cm 3 .

[0066] Foaming product preparation process:

[0067] The foaming raw materials are evenly placed in the mold, and then the mold is placed in a microwave heating device for heating and foaming according to the set conditions. After completion, it is cooled and the foamed product is taken out.

[0068] Foaming uniformity detection and analysis:

[0069] The internal structure of three groups of foam products was inspected by industrial CT scanning technology to observe the distribution of pores. The products were compressed using a universal material testing machine to measure the compression strength and elastic modulus of the products. The specific data are shown in the following table:

[0070]

[0071]

[0072] From the data in the table, we can see that there is a certain degree of unevenness in the internal pore distribution of the first group of products; the uniformity of the pore distribution of the second group of products has improved; the pore distribution of the third group of products is the most uniform. From the perspective of the physical properties of the products, the differences in the compression strength and elastic modulus of the third group of products in different parts are the smallest, indicating that their internal structure has the best uniformity; the differences in the compression strength and elastic modulus of different parts of the first group of products are large, reflecting that their foaming uniformity is poor, which fully proves that the rotation speed of the stirring device has a significant effect on the foaming uniformity of the foaming product. Within a certain range, increasing the rotation speed of the stirring device helps to make the foaming raw materials more evenly heated during microwave heating, promote the uniform formation and growth of bubbles, and improve product quality.

[0073] In summary, the method of preparing foam products by microwave heating adopts 3D printing technology combined with CNC finishing to prepare molds, replacing the complex processing process of traditional aluminum molds. Specifically, ABS plastic is used as the mold material, and the high-precision molding of the mold blank is ensured by precisely controlling parameters such as printing layer thickness, temperature and speed, and then CNC finishing is performed to achieve the accuracy requirement of ±0.05mm. Compared with traditional methods, this process avoids a large amount of aluminum waste and eliminates the complex steam heating system and its related equipment. Therefore, it not only reduces production costs, but also simplifies the production process and improves production efficiency.

[0074] Moreover, the method of preparing foam products by microwave heating replaces the traditional steam heating method with microwave heating, and shows unique advantages in the expansion process of foaming raw materials. A temperature sensor is provided inside the microwave heating equipment to monitor the temperature change of the foaming raw materials in the mold in real time. When the temperature reaches 120°C-130°C, the equipment automatically adjusts the power to 1kW-2kW to continue heating, ensuring uniform foaming and reducing local density differences. In addition, microwaves have strong penetrability and can quickly and evenly heat the foaming raw materials, so that the raw materials expand rapidly to fill the mold cavity. Compared with steam heating, it is more efficient and stable, effectively shortens the production cycle and improves the consistency of product quality, and solves the current production method of foaming products. Although the core purpose is only to expand the foaming material to fill the mold cavity, it relies on steam heating, which causes many problems. The generation of steam depends on boilers, which are explosive special equipment and require professional certified personnel to operate. In addition, the large storage of combustion raw materials also hides safety hazards. Not only that, the production process of steam heating is complicated and covers many links. Special equipment must be purchased for each link, such as pre-expanders, steam boilers, cooling systems, etc., which greatly increases the equipment investment cost. Moreover, the operation and maintenance of each link require the employment of full-time personnel, and the labor cost increases accordingly. The accumulation of a large number of production links has greatly extended the production cycle, seriously restricted production efficiency, and reduced the competitiveness of products in the market.

[0075] The relevant modules involved in this system are all hardware system modules or functional modules that combine computer software programs or protocols with hardware in the prior art. The computer software programs or protocols involved in the functional modules are themselves technologies that are well known to those skilled in the art and are not improvements of this system. The improvements of this system are the interaction or connection relationships between the modules, that is, improvements to the overall structure of the system to solve the corresponding technical problems to be solved by this system.

[0076] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a foamed product by microwave heating, characterized in that: The following steps are involved: S1. Use 3D printing technology to prepare the mold blank with ABS plastic as the material, where the printing layer thickness is 0.1mm-0.2mm, the printing temperature is 230℃-250℃, and the printing speed is 30mm / s-50mm / s; S2, performing CNC finishing on the mold blank, with the machining accuracy controlled within ±0.05 mm, to obtain the mold; S3, placing expandable polystyrene particles with a particle size of 0.5 mm-1.5 mm as foaming raw materials evenly in the mold; S4, placing the mold containing the foaming raw material into a microwave heating device with a microwave frequency of 2450MHz and a power of 2kW-5kW and heating for 5min-10min, so that the foaming raw material expands and fills the mold cavity; S5. Use air cooling to cool the mold. The air cooling speed is 3m / s-5m / s. The cooling time is 10min-15min. When the mold is cooled to below 50℃, take out the foaming product.

2. The method for preparing a foamed product by microwave heating according to claim 1, characterized in that: The 3D printing technology adopts a combination of layered printing and path optimization algorithm. The layered printing algorithm automatically calculates the printing thickness and contour of each layer according to the shape and size of the mold. The path optimization algorithm optimizes the movement path of the printing nozzle to reduce the empty stroke during the printing process.

3. The method for preparing a foamed product by microwave heating according to claim 1, characterized in that: Before placing the foaming raw material in the mold, the foaming raw material is dried for 2h-3h in an environment with a vacuum degree of -0.08MPa--0.09MPa and a temperature of 60℃-70℃.

4. The method for preparing a foamed product by microwave heating according to claim 1, characterized in that: A temperature sensor is provided inside the microwave heating device. When the temperature of the foaming raw material in the mold reaches 120°C-130°C, the power of the microwave heating device is automatically reduced to 1kW-2kW, and heating is continued for 1min-2min.

5. The method for preparing a foamed product by microwave heating according to claim 1, characterized in that: The inner surface of the mold is provided with a silicone release agent coating with a thickness of 0.01 mm to 0.03 mm.

6. The method for preparing a foamed product by microwave heating according to claim 1, characterized in that: During the air cooling process, negative ions are added to the cooling air with a negative ion concentration of 1000i ons / cm 3 -2000i ons / cm 3 .

7. The method for preparing a foamed product by microwave heating according to claim 1, characterized in that: The microwave heating equipment is provided with a stirring device. During the heating process, the stirring device stirs the foaming raw materials in the mold at a rotation speed of 10r / min-20r / min.

8. The method for preparing a foamed product by microwave heating according to claim 1, characterized in that: The foam products taken out are subjected to quality inspection, and the inspection items include dimensional accuracy, density uniformity and appearance quality. When the product size deviation is within ±0.5mm, the density deviation is within ±5% and there are no obvious defects in appearance, the product is judged to be qualified.

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