Spraying forming method capable of accurately controlling semi-curing degree of lining

Abstract

The invention relates to the technical field of lining forming, and particularly discloses a spraying forming method capable of accurately controlling the semi-curing degree of a lining, which comprises the following steps: S1, diluting a lining raw material with a solvent, and then adding the diluted lining raw material into a spraying system for spraying; s2, spraying equipment is adopted for automatically spraying the rotating shell, and the lining slurry is evenly sprayed to the inner surface of the product shell or the inner surface of the heat insulation layer; s3, after the lining layer is sprayed, a lining layer semi-curing process is carried out in the centrifugal rotation process of the shell; and according to the thickness of the lining layer, when multiple times of lining layer spraying and semi-curing need to be carried out, the steps from S1 to S3 are executed again. Accurate control over the thickness and the semi-curing degree of the lining in the spraying process is achieved, the problem that the semi-curing degree of the surface of the large-thickness lining after semi-curing is inconsistent with the semi-curing degree of the bottom layer is solved, and a quality control mode is provided for batch manufacturing of lining forming.

Description

Technical Field

[0001] This invention relates to the field of liner forming technology, and more specifically to a spray forming method for precisely controlling the semi-curing degree of the liner. Background Technology

[0002] The primary function of the liner is to serve as a transition layer between the ablation-resistant material and the solid propellant. In some cases, it can also act as a bonding material between the product shell and the solid propellant. Liner molding is a specialized process in production. Currently, the mainstream molding methods both domestically and internationally are liner spraying, liner scraping, liner centrifugal coating, and liner polishing. Among these, liner spraying offers advantages such as high production efficiency and uniform coating, making it suitable for mass production.

[0003] Precise control of the lining thickness is necessary to address the varying thermal loads in different areas. Since the lining is applied as a slurry during spraying, centrifugal rotation is typically used to prevent sagging or buildup. It is then cured by heating for a specific time to achieve a semi-cured state where it remains largely non-flowing but retains adhesive properties. However, as the lining thickness increases, the surface curing agent reacts too quickly during semi-curing, potentially blocking the evaporation channels of small molecules in the bottom layer. This results in a "soft-boiled egg" structure—over-cured on the surface and under-cured at the bottom. Currently, no research focuses on the precise control of the lining semi-curing process. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a spraying molding method for precisely controlling the semi-curing degree of the lining. Specifically, the lining molding area is controlled by adjusting the shell rotation speed, spraying vehicle travel speed, spraying distance, spraying angle, and lining spraying flow rate during the lining spraying process. The curing agent inside the lining undergoes a preliminary reaction through heat preservation at a certain temperature, thereby precisely controlling the semi-curing degree of the lining.

[0005] The technical solution of the present invention is a spray coating method for precisely controlling the semi-curing degree of the liner, comprising the following steps: S1. Dilute the lining material with a solvent and then add it to the spraying system in preparation for spraying; S2. Use spraying equipment to automatically spray the rotating shell, and evenly spray the lining slurry onto the inner surface of the product shell or insulation layer. S3. After the lining is sprayed, the lining undergoes a semi-curing process during the centrifugal rotation of the shell. If multiple lining spraying and semi-curing processes are required depending on the thickness of the lining, then repeat steps S1-S3.

[0006] Furthermore, the liner material in S1 is a hydroxyl-butadiene system material, and the solvent is chloroform.

[0007] Furthermore, the mass ratio of the solvent in the liner material in S1 is 1:0.8~1.8.

[0008] Furthermore, in S2, the parameters of shell rotation speed, spraying vehicle travel speed, spraying distance and spraying angle are set. Each parameter should satisfy 4 / 3*H*tan(β / 2)≥ν*(60 / n), where H is the spraying distance, that is, the height of the spray gun head perpendicular to the inner wall of the product shell or the inner insulation layer, in mm; β is the spraying angle, in °; ν is the spraying vehicle travel speed, in mm / s; and n is the shell rotation speed, in r / min.

[0009] Furthermore, during the lining spraying process in S2, it is necessary to control the lining spraying flow rate and spraying time to precisely control the lining thickness in the sprayed area. The coordination relationship must satisfy: δ=q*t / (ρ*2π*r*L)*10 3 Where δ is the lining thickness in mm; q is the lining spraying flow rate in g / min; t is the spraying time in min; and ρ is the lining density in g / cm³. 3 r is the inner radius of the product housing, in mm; L is the length of the product to be coated, in mm.

[0010] Furthermore, when the lining thickness is 0.6 mm or more, multiple sprayings are applied.

[0011] Furthermore, when the S3 liner is sprayed and formed in one step, the semi-curing temperature is 50℃±5℃, and the heat preservation time is preferably 300min-640min.

[0012] Furthermore, when the S3 liner is formed by multiple sprayings, the thickness of the first spray is not less than the average thickness of a single spray; the semi-curing temperature is 50℃±5℃; the first semi-curing holding time is 300min-420min, the semi-curing time of each subsequent spray is gradually shortened, and the last semi-curing holding time is 90min-120min.

[0013] Furthermore, the degree of semi-curing of the lining is qualitatively judged by its tactile feel; it is sticky to the touch but does not string.

[0014] The present invention also relates to the application of the aforementioned spray coating method in the precise control of liner forming.

[0015] The present invention has the following beneficial effects: This invention employs a rotary spraying method to achieve precise spraying of the lining layer onto the shell surface or insulation layer surface. During the spraying process, by controlling the shell rotation speed, spraying cart travel speed, spraying flow rate, spraying distance, and spraying angle, the uniformity of the sprayed lining layer at different times along the length direction is achieved. By controlling the lining spraying flow rate and spraying time, the thickness of the lining layer in different areas can be controlled. Depending on the thickness of the lining layer to be formed, one or multiple sprayings can be used. At the same time, the semi-curing time after each spraying is controlled. Precise control of the semi-curing degree of lining layers of different thicknesses and the full release of small solvent molecules after the lining layer containing solvent dilution are ensured, so that the entire sprayed lining layer can be uniformly cured, avoiding the problem of inconsistent semi-curing degree between the surface and the bottom layer after the semi-curing of a thick lining layer. Attached Figure Description

[0016] Figure 1 This is a schematic diagram showing the corresponding parameters of the product shell and the spraying workshop during the shell spraying process. Detailed Implementation

[0017] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods. Unless otherwise specified, the raw materials or reagents used are commercially available. The embodiments of the present invention will be described in detail below with reference to the examples; however, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention.

[0018] Example 1 A 0.7mm thick liner is sprayed onto the surface of a product with a diameter of 370mm and a length of 4700mm. The butyl hydroxyl liner (density approximately 0.9g / cm³) is used. 3 After uniform mixing, the lining is diluted with chloroform solvent at a weight ratio of 1:1.55 and stirred evenly. The diluted slurry is added to the automatic lining spraying system. The spraying angle β of the spray gun head is adjusted to 60°, the vertical height of the spray gun head from the surface of the insulation layer (i.e., the spraying distance H) is 150mm, the spraying cart speed ν is 30mm / s, and the shell rotation speed n is 20r / min. The lining spraying rate is adjusted to 180g / min. The first spray is a lining layer with a thickness of 0.4mm, which is then semi-cured at 50℃±5℃ for 390min. After the first semi-curing, a second spray is a lining layer with a thickness of 0.3mm, which is then semi-cured at 50℃±5℃ for 120min. The degree of semi-curing is tested after the lining is sprayed. The surface and bottom layers are tacky to the touch and do not string. The semi-cured product was vacuumed to 1 kPa, and no bulging was observed between the insulation layer and the lining on the surface of the lining.

[0019] Comparative Example 1 A 0.7mm thick liner is sprayed onto the surface of a product with a diameter of 370mm and a length of 4700mm. The butyl hydroxyl liner (density approximately 0.9g / cm³) is used. 3 After uniform mixing, the lining was diluted with chloroform solvent at a weight ratio of 1:1.55 and stirred evenly. The diluted slurry was added to the automatic lining spraying system. The spraying angle β of the spray gun head was adjusted to 60°, the vertical height of the spray gun head from the surface of the insulation layer (i.e., the spraying distance H) was 150mm, the spraying cart speed ν was 30mm / s, and the shell rotation speed n was 20r / min. The lining spraying rate was adjusted to 180g / min. A lining thickness of 0.7mm was sprayed in one pass and then semi-cured at 50℃±5℃ for 510min. The semi-curing degree of the lining was tested after spraying. The surface lining felt sticky to the touch and did not string, while the bottom lining felt sticky to the touch and stringy, indicating that the semi-curing degree of the bottom lining was insufficient. The product was vacuumed to 1KPa, and large-area bulging occurred on the lining surface, with the largest single bulge area reaching 490cm². 2 (Approximately 250mm in diameter), the bulge area accounts for about 1 / 4 of the liner area. After vacuum air intake, bulges with a diameter greater than 100mm cracked and fell off in large areas.

[0020] Comparative Example 2 A 0.7mm thick liner is sprayed onto the surface of a product with a diameter of 370mm and a length of 4700mm. The butyl hydroxyl liner (density approximately 0.9g / cm³) is used. 3 After uniform mixing, the lining is diluted with chloroform solvent at a weight ratio of 1:1.55 and stirred evenly. The diluted slurry is added to the automatic lining spraying system. The spraying angle β of the spray gun head is adjusted to 60°, the vertical height of the spray gun head from the surface of the insulation layer (i.e., the spraying distance H) is 150mm, the spraying cart speed ν is 30mm / s, and the shell rotation speed n is 20r / min. The lining spraying rate is adjusted to 180g / min. The first spray is a lining layer with a thickness of 0.35mm, which is then semi-cured at 50℃±5℃ for 120min. After the first semi-curing, a second lining layer with a thickness of 0.35mm is sprayed, and then semi-cured at 50℃±5℃ for 390min. The degree of semi-curing is tested after the lining is sprayed. The surface lining feels sticky to the touch without stringing, and the bottom lining also feels sticky to the touch without stringing. After the semi-cured product was vacuumed to 1 kPa, numerous small bulges appeared on the lining surface, with the largest single bulge measuring approximately 50 cm². 2 (Approximately 80mm in diameter), the bulge area accounts for about 1 / 6 of the total liner area. After vacuum air intake, the bulge leaked air but no cracking or falling off was observed.

[0021] Example 2 A 0.56mm thick liner is sprayed onto the surface of a product with a diameter of 400mm and a length of 3400mm. The butyl hydroxyl liner (density approximately 0.9g / cm³) is used. 3 After uniform mixing, the lining is diluted with chloroform solvent at a weight ratio of 1:1.5 and stirred evenly. The diluted slurry is added to the automatic lining spraying system. The spraying angle β of the spray gun head is adjusted to 60°, the vertical height of the spray gun head from the surface of the insulation layer (i.e., the spraying distance H) is 200mm, the travel speed of the spraying cart is ν = 30mm / s, and the rotation speed of the shell is n = 20r / min (satisfying the condition 4 / 3*H*tan(β / 2)≥ν*(60 / n)). The lining spraying rate is adjusted to 190g / min (satisfying δ=q*t / (ρ*2π*r*L)*10). 3 (Conditions). The lining is formed by one-time spraying and then semi-cured at 50℃±5℃ for 300 minutes. The degree of semi-curing of the lining is tested after spraying. The surface and bottom layers are tacky to the touch and do not string. The thickness of the lining is measured after peeling off the surface of the insulation layer after spraying. The results show that the lining thickness is uniform. The thickness measurement results are shown in Table 1.

[0022] Comparative Example 3 A 0.56mm thick liner is sprayed onto the surface of a product with a diameter of 400mm and a length of 3400mm. The butyl hydroxyl liner (density approximately 0.9g / cm³) is used. 3 After uniform mixing, the lining is diluted with chloroform solvent at a weight ratio of 1:1.5 and stirred evenly. The diluted slurry is added to the automatic lining spraying system. The spraying angle β of the spray gun head is adjusted to 60°, the vertical height of the spray gun head from the surface of the insulation layer (i.e., the spraying distance H) is 200mm, the travel speed of the spraying cart is ν = 30mm / s, and the rotation speed of the shell is n = 10r / min (the rotation speed does not meet the condition 4 / 3*H*tan(β / 2)≥ν*(60 / n)). The lining spraying rate is adjusted to 190g / min (satisfying δ=q*t / (ρ*2π*r*L)*10). 3 (Conditions). The lining is formed by one-time spraying and then semi-cured at 50℃±5℃ for 300 minutes. The degree of semi-curing was tested after spraying. The surface and bottom layers were tacky to the touch and did not string. The thickness was measured after peeling the lining from the insulation layer surface. The results showed that the lining thickness was extremely uneven, exhibiting a spiral pattern in the circumferential direction. The thickness measurement results are shown in Table 2.

[0023] Comparative Example 4 A 0.56mm thick liner is sprayed onto the surface of a product with a diameter of 400mm and a length of 3400mm. The butyl hydroxyl liner (density approximately 0.9g / cm³) is used. 3After uniform mixing, the lining is diluted with chloroform solvent at a weight ratio of 1:1.5 and stirred evenly. The diluted slurry is added to the automatic lining spraying system. The spraying angle β of the spray gun head is adjusted to 60°, the vertical height of the spray gun head from the surface of the insulation layer (i.e., the spraying distance) H = 100 mm, the travel speed of the spraying cart ν = 30 mm / s, and the rotation speed of the shell n = 20 r / min (the spraying distance does not meet the condition 4 / 3*H*tan(β / 2)≥ν*(60 / n)). The lining spraying rate is adjusted to 190 g / min (satisfying δ=q*t / (ρ*2π*r*L)*10). 3 (Conditions). The lining is formed by one-time spraying and then semi-cured at 50℃±5℃ for 300 minutes. The degree of semi-curing was tested after spraying. The surface and bottom layers were tacky to the touch and did not string. The thickness was measured after peeling the lining from the insulation layer surface. The results showed that the lining thickness was extremely uneven, exhibiting a spiral pattern in the circumferential direction. The thickness measurement results are shown in Table 3.

[0024] The results of the coating thickness test after spraying in Example 2, Comparative Example 3, and Comparative Example 4 are shown in Tables 1 to 3, where the coating thickness was measured using vernier calipers.

[0025] Table 1. Test results of lining thickness after spraying in Example 2

[0026] Table 2. Thickness test results of the liner after spraying in Comparative Example 3

[0027] Table 3. Thickness test results of the liner after spraying in Comparative Example 4

[0028] The results above show that when the coating parameters do not meet the condition 4 / 3*H*tan(β / 2)≥ν*(60 / n), the coating layer exhibits a spiral-shaped, highly uneven appearance in the circumferential direction. If the condition is met, a more uniform coating layer can be obtained.

[0029] The above embodiments describe preferred embodiments of the present invention, but the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other way. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention. Therefore, the protection scope of this patent should be determined by the appended claims.

Claims

1. A spray-up method for precisely controlling the degree of semi-curing of a backing layer, characterized in that, It comprises the following steps: S1, dilute the lining raw material with solvent, and then add it to the spraying system for spraying; S2, use the spraying equipment to automatically spray the rotating shell, and uniformly spray the lining slurry on the inner surface of the product shell or the thermal insulation layer; S3, perform the lining semi-curing process during the centrifugal rotation of the shell after lining spraying; According to the thickness of the lining, multiple lining spraying and semi-curing are required, and the steps S1-S3 are executed again.

2. The spray forming method of claim 1, wherein: The lining material in S1 is a hydroxyl system material, and the solvent is chloroform.

3. The spray forming method of claim 1, wherein: The mass ratio of the lining material solvent in S1 is 1:0.8-1.

8.

4. The spray forming method of claim 1 wherein: In S2, the shell rotation speed, spraying car travel speed, spraying distance and spraying angle parameters are set, and each parameter should meet 4 / 3*H*tan(β / 2)≥ν*(60 / n), wherein H is the spraying distance, that is, the height of the spray gun head vertically to the inner wall or inner thermal insulation layer of the product shell, unit mm; β is the spraying angle, unit °; ν is the spraying car travel speed, unit mm / s; n is the shell rotation speed, unit r / min.

5. The spray forming method of claim 1, wherein: The lining spraying flow and spraying time in the lining spraying process in S2 need to be controlled to accurately control the lining thickness of the spraying area, and the matching relationship needs to meet: δ=q*t / (p*2π*r*L)*10 3 , wherein δ is the lining thickness, unit: mm; q is the lining spraying flow, unit: g / min; t is the spraying required time, unit: min; p is the lining density, unit: g / cm 3 , r is the radius of the inner cavity of the product shell, unit: mm; L is the length of the product to be sprayed, unit: mm.

6. The spray forming method according to any one of claims 1 to 5, characterized in that: When the lining thickness is more than 0.6 mm, multiple spraying is performed.

7. The spray forming method of claim 6, wherein: In S3, when the lining is sprayed once, the semi-curing temperature is 50℃±5℃, and the preferred holding time is 300min-640min.

8. The spray forming method of claim 6, wherein: In S3, when the lining is sprayed multiple times, the thickness of the first spraying is not less than the average single spraying thickness; the semi-curing temperature is 50℃±5℃; the first semi-curing holding time is 300min-420min, and the semi-curing time is gradually shortened each time, and the last semi-curing holding time is 90min-120min.

9. The spray forming method of claim 6 wherein: The semi-curing degree of the lining is qualitatively determined by hand contact, sticky but not stringy.

10. The application of the spraying forming method according to any one of claims 1-9 in precise control of lining forming.

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