CN110926112B

CN110926112B - Lost foam pattern drying method and drying room

Info

Publication number: CN110926112B
Application number: CN201911143922.7A
Authority: CN
Inventors: 鲍志敏; 张堃
Original assignee: Hubei Guanghui Energy Saving Technology Co ltd
Current assignee: Hubei Guanghui Energy Saving Technology Co ltd
Priority date: 2019-11-20
Filing date: 2019-11-20
Publication date: 2021-03-05
Anticipated expiration: 2039-11-20
Also published as: CN110926112A

Abstract

The invention provides a drying method and a drying room for a lost foam pattern, which comprise the following steps: step S1, placing the lost foam pattern in a drying room, heating the drying room to dry the lost foam pattern at 40-45 ℃, and dehumidifying while drying to reduce the humidity to 30-33% to obtain a pre-dried lost foam pattern; step S2, raising the temperature in the drying room to 48-50 ℃, reducing the humidity in the drying room to 25-28%, and then carrying out constant temperature and constant humidity to obtain a first drying lost foam pattern; step S3, raising the temperature in the drying room to 50-60 ℃ to reduce the humidity in the drying room to 12-15% to obtain a second drying lost foam pattern; in steps S1 to S3, the temperature is raised and the dehumidification is performed by hot air. Compared with the prior art, the control of the heating capacity, the air quantity and the air outlet temperature can meet the requirements of production, and the investment cost of enterprise equipment is reduced; the drying time is greatly shortened under the condition of ensuring the low deformation rate of the lost foam pattern.

Description

Lost foam pattern drying method and drying room

Technical Field

The invention belongs to the field of lost foam manufacturing processes, and particularly relates to a lost foam pattern drying method and a drying room.

Background

The drying method of the white mold pattern commonly adopted in the lost foam casting industry is natural ventilation drying or heating ventilation drying, the drying method generally has a long drying period, and the moisture in the white mold can be reduced to the minimum level only after the white mold is dried for 7 to 30 days.

The main causes of the inefficient drying are:

the heat conduction efficiency is low, and air is adopted as a heat medium to carry out heat transfer in the mode. Heating is done from the surface of the white mold gradually towards the inside, since the heat transfer efficiency is usually low for the model material used in either EPS or STMMA or other lost foam casting. Tests show that when the glass is heated for 1 hour by using air circulation at the temperature of 45 ℃, the internal temperature of the glass with the depth of more than 10 millimeters is still the initial temperature before heating. The white mould structure is inseparable, and the speed that the moisture analysis goes out is slower, and the drying is carried out middle and later stage, and the migration distance of drying interface and the inside moisture of model constantly prolongs, and drying rate constantly reduces, causes the drying process to consume long time.

Disclosure of Invention

The invention provides a lost foam pattern drying method and a drying room, aiming at solving the problems of low efficiency and excessive energy consumption of a lost foam pattern drying mode in the prior art.

The specific technical scheme is as follows:

step S1, placing the lost foam pattern in a drying room, heating the drying room to dry the lost foam pattern at 40-45 ℃, and dehumidifying while drying to reduce the humidity to 30-33% to obtain a pre-dried lost foam pattern;

step S2, raising the temperature in the drying room to 48-50 ℃, reducing the humidity in the drying room to 25-28%, and then carrying out constant temperature and constant humidity to obtain a first drying lost foam pattern;

step S3, raising the temperature in the drying room to 50-60 ℃ to reduce the humidity in the drying room to 12-15% to obtain a second drying lost foam pattern;

in steps S1 to S3, the temperature is raised and the moisture is removed by hot air.

Compared with the prior art, the invention has the advantages that the energy consumption in the drying process is low, and meanwhile, the best white mold drying environment can be created by artificially controlling reasonable air moisture by adopting a closed dehumidification drying scheme; the heating capacity, the air volume and the air outlet temperature can meet the requirements of production, and the investment cost of enterprise equipment is reduced; the drying time is greatly shortened under the condition of ensuring the low deformation rate of the lost foam.

Further, in the step S1, the temperature of the drying room is increased at a rate of 5 ℃/h to 8 ℃/h until the temperature of the drying room is increased to 40 ℃ to 45 ℃, the humidity reduction rate in the drying room is 10% r.h/h to 14% r.h/h, and the duration of the step S1 is 3 hours to 4 hours.

Further, the step S2 includes the following steps:

step S2-1, heating the drying room at the speed of 2-5 ℃/h until the temperature of the drying room is raised to 48-50 ℃, and simultaneously reducing the humidity of the drying room to 25-28%;

step S2-2, performing constant temperature and humidity treatment in the drying room, changing air to remove gas generated in the drying process, and exhausting the air for 3-8 minutes;

step S2-3: stopping for 20 to 40 minutes;

and circularly performing the step S2-2 to the step S2-3, wherein the duration of the step S2 is 6-12 hours.

Further, in the step S2-2, the air is changed to remove the gas generated in the drying process, when the temperature is lower than 48 ℃ to 50 ℃, the air change is stopped, when the temperature is higher than 48 ℃ to 50 ℃, the air change is continued, the air change cumulative time reaches 3 minutes to 8 minutes, and the gas discharged in the air change process is 5 times to 6 times of the volume of the drying room.

Further, the step S3 includes the following steps:

step S3-1, heating the drying room at the speed of 2-5 ℃/h until the temperature in the drying room is raised to 50-60 ℃, exchanging air to remove gas generated in the drying process, and accumulating the air exchange time for 1-5 minutes;

step S3-2, stopping for 60-120 minutes;

step S3-1 and step S3-2 are alternately performed, and the duration of step S3 is 8 to 24 hours.

Further, in the step S3-1, when the temperature in the drying room is reduced to below 50 ℃ to 60 ℃ during air exchange, the air exchange is stopped, the air exchange is resumed after the temperature is raised back to 50 ℃ to 60 ℃ until the air exchange time of 1 minute to 5 minutes is met, and the gas discharged in the air exchange process is 2 times to 3 times of the volume of the drying room.

Further, the spacing between the lost foam patterns is 50mm to 100 mm.

Further, gas generated in the air exchange process is collected and decomposed by ultraviolet light, and then is discharged or recycled to the drying room for reuse.

Further, the wind speed of the hot wind is 0.3 m/s to 0.7 m/s.

The beneficial effect of adopting the further technical scheme is that: in the drying process, the volume size of the lost foam white mold can be changed within a certain time due to the existence of residual foaming agent components in the lost foam white mold, air exchange is carried out at a reasonable time, and fresh air outside the drying room is introduced into the drying room, so that the volume size change can be avoided. In the ventilation process, organic volatile matters are generated in white molds such as EPS or STMMA, so that exhaust air is treated by UV light and then is discharged or is sent back to a drying room again for circulation and heating.

A drying room for realizing the drying method is characterized in that the drying room comprises:

the drying room comprises a drying room body, wherein one or more material racks and a temperature and humidity sensor are arranged in the drying room body, an air inlet is formed in the drying room body, an air exchange port is formed in the upper portion of the drying room body, an axial flow fan is installed at the air exchange port, and a return air pipe is further arranged in the drying room body;

the air energy heating unit is arranged outside the drying room body;

the air inlet pipe is connected with the air energy heating unit and communicated with the interior of the drying room body, and a plurality of air outlets are formed in the air inlet pipe;

wherein, the drying room body is made of heat-insulating materials.

Compared with the prior art, the drying room has the beneficial effects that: air is supplied through the air inlet air pipe, and the air return of the air return air pipe enables the heating to be more uniform.

Drawings

FIG. 1 is a diagram of a baking room structure;

FIG. 2 is a top view of the drying room;

FIG. 3 is a top view of the gas recovery processing apparatus;

FIG. 4 is a block diagram of an interface drying room with VOC treatment equipment;

in the drawings, the components represented by the respective reference numerals are listed below:

the method comprises the following steps of 1-a drying room body, 2-an air inlet, 3-an air exchange port, 4-an axial flow fan, 5-a return air duct, 6-an air filter, 7-an air energy heating unit, 8-an air inlet duct, 801-an air outlet, 9-VOC (volatile organic compound) processing equipment, 10-a material rack, 101-a temperature and humidity sensor and 11-a VOC processing equipment interface.

Detailed Description

The principles and features of this invention are described below in conjunction with the following drawings, which are set forth by way of illustration only and are not intended to limit the scope of the invention.

Example one

A drying room for drying a lost foam pattern by using air energy comprises: the drying room comprises a drying room body 1, wherein one or more material racks 10 and a temperature and humidity sensor 101 are arranged inside the drying room body 1, an air inlet 2 is formed in the drying room 1, an air exchange port 3 is formed in the drying room body 1, an axial flow fan 4 is arranged at the air exchange port 3, and a return air pipe 5 and an air filter 6 are further arranged inside the drying room body 1; air can heat unit 7, air can heat unit 7 locates the baking house body 1 is outside, baking house body 1 adopts 100 millimeters polyurethane foam insulation material to found. The temperature and humidity sensor 101 in the drying room is arranged in the center of the drying room and is 2 meters away from the ground. The temperature and humidity sensor 101 has no fan or other air flow blowing.

And the air energy heating unit 7 enters from the air inlet 2 and is communicated with the air inlet pipe 8 inside the drying room body 1, and the air inlet pipe 8 is provided with a plurality of air outlets 801. Air supply of the air energy heating equipment needs to adopt an air pipe air supply mode to ensure that air leakage does not occur outside a room door of the drying room where the drying room is heated uniformly inside the drying room. And after the temperature of the drying room rises to 50 ℃ in an idle load manner, stopping heating. 30 minutes after stopping heating, the temperature in the drying room cannot be reduced to below 45 ℃.

In this embodiment, as shown in fig. 3, a VOC treatment device 9 may be additionally disposed outside the air exchanging port 3, the air energy heating unit 7 is provided with an interface of the VOC treatment device, the VOC treatment device 9 (as shown in fig. 4) is connected to the air energy heating unit 7, and the organic gas is treated by UV light and then sent to the air energy heating unit 7 to be sent to the drying room again for use.

Example two

The height of the drying room is within 2.5 meters, and the area of the drying room is preferably 50 to 80 square meters; the drying room forms an air field with the hot air speed of 0.3 m/s to 0.7 m/s by the cooperation of the hot air conveying device, the axial flow fan and the return air pipe.

The initial temperature of the drying room was 28 ℃.

And step S1, gradually heating the drying room from room temperature to the process temperature of 42 ℃, wherein the heating speed is 7 ℃ per hour, and the heating time is 2 hours.

And (4) carrying out constant-temperature dehumidification when the temperature of the drying room reaches 42 ℃, gradually reducing the humidity in the drying room at a humidity reduction speed of 12% R.H/h until the set target humidity of 30% is reached, and continuing for 4 hours in the step S1.

Step S2:

and step S2-1, gradually increasing the temperature of the drying room from 42 ℃ to 50 ℃, increasing the temperature at a speed of 4 ℃ for 2 hours, and simultaneously reducing the humidity in the drying room from 30% to 25%.

And step S2-2, performing constant temperature and humidity after the set target of 25 percent is reached. The drying room needs to be ventilated at this stage, the concentration of the organic volatile matters in the drying room is reduced, and the air exhaust time is 5 minutes. When the temperature in the drying room is reduced to be below 48 ℃ during air exchange, the air exchange is stopped. And when the temperature rises to be above 50 ℃, air exchange is resumed until the air exchange time of 5 minutes is met. The air discharged in the air exchange process is 5 to 6 times of the volume of the drying room.

And after the 5-minute air exhaust time is met, timing by the timing device again.

And step S2-3, stopping for 30 minutes.

The steps S2-2 to S2-3 are repeated, and the time of the whole step S2 is 8 hours.

Step S3:

and step S3-1, the temperature in the drying room is increased from 50 ℃ to 55 ℃, the temperature increasing speed is 5 ℃/h, and the temperature increasing time is 1 h. The drying room needs to be exhausted at this stage, so that the concentration of the organic volatile matters in the drying room is reduced, and the air exhaust time is 3 minutes. When the temperature in the drying room is reduced to below 52 ℃ during air exchange, the air exchange is stopped. And when the temperature rises to 55 ℃, air exchange is resumed until the air exchange time of 3 minutes is met. The air discharged in the air exchange process is 2 to 3 times of the volume of the drying room.

Step S3-2, after the air change is satisfied in 3 minutes, the timing device counts time again at an interval of 90 minutes;

step S3-1 to step S3-2 are alternately performed, and the duration of the whole step S3 is 24 hours.

EXAMPLE III

The height of the drying room is within 2.5 meters, and the area of the drying room is preferably 50 to 80 square meters; the drying room forms an air field with the hot air speed of 0.2 m/s to 2.0 m/s by the cooperation of the hot air conveying device, the axial flow fan and the return air pipe.

The initial temperature of the drying room was 28 ℃.

Step S1:

and step S1-1, gradually heating the drying room from room temperature to the process temperature of 45 ℃, wherein the heating speed is 7 ℃ per hour.

And (3) carrying out constant-temperature dehumidification when the temperature of the drying room reaches 45 ℃, gradually reducing the humidity in the drying room, wherein the humidity reduction speed is 12% R.H/h until the set target humidity of 30% is reached.

The drying room needs to be ventilated at this stage, the concentration of the organic volatile matters in the drying room is reduced, and when the temperature in the drying room is reduced to be lower than 45 ℃ during ventilation, the ventilation is stopped. And when the temperature rises to more than 45 ℃, air exchange is resumed until the air exchange time of 5 minutes is met.

Step S1-2, stop for 30 minutes.

Step S1-3, alternating steps S1-1 and S1-2, and making the duration of the whole step S1 12 hours.

Step S2:

and step S2-1, gradually increasing the temperature of the drying room from 45 ℃ to 50 ℃, increasing the temperature at a speed of 4 ℃ for 2 hours, and simultaneously reducing the humidity in the drying room from 30% to 15%.

And step S2-2, performing constant temperature and humidity after the set target of 15% is reached. The drying room needs to be ventilated at this stage, the concentration of the organic volatile matters in the drying room is reduced, and the air exhaust time is 5 minutes. When the temperature in the drying room is reduced to be below 48 ℃ during air exchange, the air exchange is stopped. And when the temperature rises to be above 50 ℃, air exchange is resumed until the air exchange time of 5 minutes is met. The air discharged in the air exchange process is 5 to 6 times of the volume of the drying room.

And step S2-3, stopping for 60 minutes.

The steps S2-2 to S2-3 are repeated, and the time of the whole step S2 is 12 hours.

Step S3:

and step S3-1, the temperature in the drying room is increased from 50 ℃ to 55 ℃, the temperature increasing speed is 5 ℃/h, the temperature increasing time is 1 h, meanwhile, the humidity of the drying room is reduced to 10%, the drying room needs to exhaust air at the stage, the concentration of the organic volatile matters in the drying room is reduced, and the air exhaust time is 3 min. When the temperature in the drying room is reduced to below 52 ℃ during air exchange, the air exchange is stopped. And (5) when the temperature rises to 55 ℃, air exchange is resumed until the air exchange time of 3-5 minutes is met. The air discharged in the air exchange process is 2 to 3 times of the volume of the drying room.

Step S3-2, after the air change is met in 3-5 minutes, the timing device counts the time again at an interval of 60 minutes;

step S3-1 to step S3-2 are alternately performed, and the duration of the whole step S3 is 48 hours.

Example four

The initial temperature of the drying room was 28 ℃.

And step S1, gradually heating the drying room from room temperature to the process temperature of 40 ℃, wherein the heating speed is 8 ℃/h.

And (3) carrying out constant-temperature dehumidification when the temperature of the drying room reaches 40 ℃, and gradually reducing the humidity in the drying room at a humidity reduction speed of 12% R.H/h until the set target humidity of 32% is reached.

Step S1 was performed for 3 hours.

Step S2:

and step S2-1, gradually raising the temperature of the drying room from 40 ℃ to 48 ℃, and reducing the humidity in the drying room from 30% to 26% while the temperature is raised for 4 hours.

And step S2-2, performing constant temperature and humidity after the set target of 26 percent is reached. The drying room needs to be ventilated at this stage, the concentration of the organic volatile matters in the drying room is reduced, and the air exhaust time is 5 minutes. When the temperature in the drying room is reduced to below 46 ℃ during air exchange, the air exchange is stopped. And when the temperature rises to more than 48 ℃, air exchange is resumed until the air exchange time of 5 minutes is met. The air discharged in the air exchange process is 5 to 6 times of the volume of the drying room.

And step S2-3, stopping for 40 minutes.

Step S3:

and step S3-1, the temperature in the drying room is increased from 48 ℃ to 52 ℃, the temperature increasing speed is 4 ℃/h, and the temperature increasing time is 1 h. The drying room needs to be exhausted at this stage, so that the concentration of the organic volatile matters in the drying room is reduced, and the air exhaust time is 3 minutes. When the temperature in the drying room is reduced to below 50 ℃ during air exchange, the air exchange is stopped. And when the temperature rises to 52 ℃, air exchange is resumed until the air exchange time of 3 minutes is met. The air discharged in the air exchange process is 2 to 3 times of the volume of the drying room.

Step S3-2, after the air change is satisfied in 3 minutes, the timing device counts time again at an interval of 60 minutes;

step S3-1 to step S3-2 are alternately performed, and the duration of the whole step S3 is 20 hours.

EXAMPLE five

The initial temperature of the drying room was 28 ℃.

And step S1, gradually heating the drying room from room temperature to the process temperature of 44 ℃ at the heating speed of 5 ℃ per hour.

And (4) carrying out constant-temperature dehumidification when the temperature of the drying room reaches 44 ℃, gradually reducing the humidity in the drying room, wherein the humidity reduction speed is 12% R.H/h until the set target humidity of 33% is reached, and maintaining the step S1 for 3.5 hours.

Step S2:

and step S2-1, gradually increasing the temperature of the drying room from 44 ℃ to 50 ℃, increasing the temperature at a speed of 4 ℃ for 2 hours, and simultaneously reducing the humidity in the drying room from 30% to 28%.

And step S2-2, performing constant temperature and humidity after the set target of 28 percent is reached. The drying room needs to be ventilated at this stage, the concentration of the organic volatile matters in the drying room is reduced, and the air exhaust time is 5 minutes. When the temperature in the drying room is reduced to be below 48 ℃ during air exchange, the air exchange is stopped. And when the temperature rises to be above 50 ℃, air exchange is resumed until the air exchange time of 5 minutes is met. The air discharged in the air exchange process is 5 to 6 times of the volume of the drying room.

And step S2-3, stopping for 30 minutes.

Step S3:

In the second to fifth embodiments, during the exhaust process, the exhaust air is collected and then is collected and processed by the gas recovery processing device in the second to fifth embodiments.

Comparative example 1

And (3) carrying out constant-temperature dehumidification when the temperature of the drying room reaches 42 ℃, gradually reducing the humidity in the drying room, wherein the humidity reduction speed is 12% R.H/h until the set target humidity of 30% is reached, and the whole step S1 is maintained for 4 hours.

Step S2:

and step S2-1, gradually increasing the temperature of the drying room from 42 ℃ to 55 ℃, wherein the temperature increasing speed is 4 ℃ per hour, the temperature increasing time is 3 hours, and meanwhile, the humidity in the drying room is reduced from 30% to below 28%.

And step S2-2, performing constant temperature and humidity after the set target of 25 percent is reached. The drying room needs to be ventilated at this stage, the concentration of the organic volatile matters in the drying room is reduced, and the air exhaust time is 5 minutes. When the temperature in the drying room is reduced to be below 48 ℃ during air exchange, the air exchange is stopped. And when the temperature rises to more than 50 ℃, air exchange is resumed until the air exchange time of 5 minutes is met. The air discharged in the air exchange process is 5 to 6 times of the volume of the drying room.

And after the 5-minute air change time is met, the timing device counts again.

And step S2-3, stopping for 90 minutes.

The steps S2-2 to S2-3 are repeated, and the time of the whole step S2 is 32 hours.

Comparative example No. two

And (3) carrying out constant-temperature dehumidification when the temperature of the drying room reaches 42 ℃, gradually reducing the humidity in the drying room at a humidity reduction speed of 12% R.H/h until the set target humidity of 30% is reached, and maintaining the temperature of the whole step S1 for 4 hours.

Step S2:

and step S2-1, gradually increasing the temperature of the drying room from 42 ℃ to 50 ℃, wherein the temperature increasing speed is 4 ℃ per hour, the temperature increasing time is 2 hours, and meanwhile, the humidity in the drying room is reduced from 30% to below 28%.

And step S2-2, performing constant temperature and humidity after the set target of 25 percent is reached.

The time of the entire step S2 was 8 hours.

And step S3, drying for 12-48 hours, wherein the temperature in the drying room is increased from 50 ℃ to 55 ℃, the temperature increasing speed is 5 ℃ per hour, and the temperature increasing time is 1 hour. The entire step S3 duration is 24 hours.

Comparative example No. three

The height of the drying room is within 2.5 meters, and the area of the drying room is preferably 50 to 80 square meters; the drying room forms an air field with the hot air speed of 1.3 m/s to 1.5 m/s by the cooperation of the hot air conveying device, the axial flow fan and the return air pipe.

The initial temperature of the drying room was 28 ℃.

And (3) carrying out constant-temperature dehumidification when the temperature of the drying room reaches 42 ℃, gradually reducing the humidity in the drying room, wherein the humidity reduction speed is 12% R.H/h until the set target humidity of 30% is reached. Step S1 was maintained for 4 hours.

Step S2:

and step S2-1, gradually increasing the temperature of the drying room from 42 ℃ to 50 ℃, increasing the temperature at a speed of 4 ℃/h for 2 h, and simultaneously reducing the humidity in the drying room from 30% to below 28%.

And step S2-2, performing constant temperature and humidity after the set target of 25 percent is reached. The drying room needs to be ventilated at this stage, the concentration of the organic volatile matters in the drying room is reduced, the ventilation interval is 30 minutes, and the air exhaust time is 5 minutes. When the temperature in the drying room is reduced to be below 48 ℃ during air exchange, the air exchange is stopped. And when the temperature rises to more than 50 ℃, air exchange is resumed until the air exchange time of 5 minutes is met.

And after the 5-minute air change time is met, the timing device counts again. The air discharged in the air exchange process is 5 to 6 times of the volume of the drying room.

And step S2-3, stopping for 30 minutes.

Step S3:

and step S3-1, the temperature in the drying room is increased from 50 ℃ to 55 ℃, the temperature rising speed is 5 ℃ per hour, and the temperature rising time is 1 hour. The drying room needs to be ventilated at this stage, the concentration of the organic volatile matters in the drying room is reduced, the ventilation interval is 90 minutes, and the air exhaust time is 3 minutes. When the temperature in the drying room is reduced to be lower than 52 ℃ during air exchange, the air exchange is stopped. And (5) when the temperature rises to 55 ℃, air exchange is resumed until the air exchange time of 3 minutes is met. The air discharged in the air exchange process is 2 to 3 times of the volume of the drying room.

Step S3-2, after the air exhaust for 3 minutes is met, the timing device counts the time again at intervals of 90 minutes;

Comparative example No. four

Drying for 72 hours under the conditions that the temperature of the drying room is 45 ℃ and the humidity of the drying room is 10%, and carrying out air exchange during the drying period, wherein the air exchange time is 3 minutes, and the air exchange interval is 30 minutes.

Comparative example five

Drying for 120 hours at a drying room temperature of 50 ℃ and a drying room humidity of 12%.

The spacing between the lost foam patterns described in each of examples and comparative examples was 50mm to 100 mm.

The properties of the lost foam pattern after drying were examined for each example and each comparative example, as shown in table 1.

TABLE 1 detection of lost foam pattern Properties after drying

	Water content (%)	Amount of change in size (%)
			Example two	0.4～0.7	0.37～0.48
EXAMPLE III	0.4～1.0	0.37～0.48
			Example four	0.4-0.7	0.37～0.48
EXAMPLE five	0.4～0.7	0.37～0.48
			Comparative example 1	0.7～1.0	0.45～0.52
Comparative example No. two	0.7～1.0	1.24～1.38
			Comparative example No. three	0.7～1.0	0.82～1.25
Comparative example No. four	1.0～1.5	1.50～2.60
			Comparative example five	1.0～1.5	1.80～3.20

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims

1. A drying method of a lost foam pattern is characterized by comprising the following steps:

in steps S1 to S3, the temperature is raised and the moisture is removed by hot air;

in the step S1, the temperature of the drying room is increased at a speed of 5-8 ℃/h until the temperature of the drying room is increased to 40-45 ℃, the humidity reduction rate in the drying room is 10-14% R.H/h, and the duration of the step S1 is 3-4 hours.

2. The drying method of the lost foam pattern of claim 1, wherein the step S2 comprises the steps of:

step S2-3: stopping for 20 to 40 minutes;

3. The method for drying an evaporative pattern as defined in claim 2, wherein in step S2-2, the air is changed to remove the air generated during the drying process, the air change is stopped when the temperature is lower than 48 ℃ to 50 ℃, the air change is continued when the temperature is higher than 48 ℃ to 50 ℃, the cumulative time of the air change reaches 3 minutes to 8 minutes, and the air discharged during the air change is 5 times to 6 times the volume of the drying room.

4. The drying method of the lost foam pattern of claim 1, wherein the step S3 comprises the steps of:

step S3-2, stopping for 60-120 minutes;

5. The method for drying the lost foam pattern according to claim 4, wherein in the step S3-1, when the temperature in the drying room is reduced to below 50-60 ℃ during air exchange, the air exchange is stopped, the air exchange is resumed after the temperature is raised back to 50-60 ℃ until the air exchange time of 1-5 minutes is met, and the air discharged in the air exchange process is 2-3 times of the volume of the drying room.

6. A method of drying a lost foam pattern according to claim 1, wherein the spacing between the lost foam patterns is 50mm to 100 mm.

7. The method for drying a lost foam pattern according to claim 2 or 4, wherein the gas generated in the air exchange process is collected, decomposed by ultraviolet light, and then discharged or recycled to the drying room for reuse.

8. The drying method of the lost foam pattern according to claim 1, wherein the wind speed of the hot wind is 0.3 m/s to 0.7 m/s.

9. A drying room for implementing the drying method of claim 1, wherein the drying room comprises:

the drying room comprises a drying room body (1), wherein one or more material racks (10) and a temperature and humidity sensor (101) are arranged inside the drying room body (1), an air inlet (2) is formed in the drying room body (1), an air exchange port (3) is formed in the upper portion of the drying room body (1), an axial flow fan (4) is installed at the air exchange port (3), and a return air pipe (5) is further arranged inside the drying room body (1);

the air energy heating unit (7), the air energy heating unit (7) is arranged outside the drying room body (1);

the air inlet pipe (8) is connected with the air energy heating unit (7) and communicated with the interior of the drying room body (1), and a plurality of air outlets (801) are formed in the air inlet pipe (8);

the drying room body (1) is made of heat-insulating materials.