A process for the spray coating of a tensile spring component

Abstract

The application belongs to the technical field of surface treatment and particularly relates to a draw spring part Dacromet spraying process, which comprises the following steps: S1, draw spring oil removal, the draw spring is cleaned and dried after oil removal operation in an ultrasonic cleaning tank; S2, Dacromet spraying, the draw spring is installed on a draw spring special tool, and the tool is adjusted for spraying. The application applies the Dacromet spraying technology to the draw spring parts, completely solves the hydrogen embrittlement problem of the high-strength draw spring, improves the corrosion resistance of the draw spring, and ensures that no redundant materials are generated in the draw spring stretching process, thereby eliminating the quality hidden danger of the redundant materials.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of surface treatment, and particularly relates to a pull spring part Dacromet spraying process. BACKGROUND

[0002] Dacromet technology is to uniformly coat a water-based paint containing flaky zinc powder, aluminum powder and hexavalent chromium on the surface of a pretreated workpiece, and to form an inorganic coating layer through drying and baking. Dacromet technology has characteristics that traditional electroplating does not have, such as extremely strong corrosion resistance, no hydrogen embrittlement, etc., so the technology is widely popularized and applied in the fields of aerospace, military industry, etc. in China. According to the requirements of aerospace process substitution, parts prone to hydrogen embrittlement after galvanizing are gradually replaced by Dacromet process.

[0003] At present, as a widely used component in the aerospace industry, the pull spring is mostly processed by galvanizing and bluing process. The Rockwell hardness value of the pull spring part is relatively high, and there is a great risk of hydrogen embrittlement after the galvanizing or bluing surface treatment. The use of Dacromet treatment can avoid the influence of hydrogen embrittlement, but according to the existing Dacromet process: degreasing - coating (spraying / immersion coating) - pre-drying (100-120 DEG C) - baking (320-340 DEG C) - cooling - repeating coating and baking - qualified product, there are three problems in the Dacromet treatment of the pull spring part: (1) The Dacromet coating liquid will accumulate on the spring coils when immersed or conventionally sprayed because the spring coils are tightly closed. After the coating is baked, the coating will be broken during the stretching process of the pull spring, not only reducing the performance of the coating, but also producing excess material, which has a great quality risk in the flight of the aerospace product. In addition, the spring coils cannot be completely coated or the coating thickness is very thin when immersed or conventionally sprayed, and the corrosion resistance between the spring coils cannot be guaranteed. (2) Spraying and baking in the open state of the pull spring may cause the force value of the pull spring to decay. The Dacromet treatment needs to be baked at about 300 DEG C for more than 30 min, and the pull spring is easy to soften at high temperature. Under the combined action of external tensile stress and internal compressive stress, irreversible deformation of the pull spring occurs. (3) Spraying in the open state and baking in the loose state. The coating between the spring coils will be in contact after the pull spring is immediately loosened after spraying in the open state, and will be adhered during baking, which will cause the coating to be broken during the stretching process of the pull spring. SUMMARY

[0004] The purpose of the present application is to overcome the shortcomings of the prior art, and to provide a pull spring part Dacromet spraying process. The Dacromet spraying technology is applied to pull spring parts, and the problem of hydrogen embrittlement of high-strength pull springs is completely solved.

[0005] In order to achieve the above purpose, the following technical scheme is adopted in the present application:

[0006] A pull spring part Dacromet spraying process comprises the following steps:

[0007] S1, oil removal of the tension spring, after the oil removal of the tension spring in the ultrasonic cleaning tank, cleaning and drying;

[0008] S2, Dacromet spraying, the tension spring is installed on the special tooling for the tension spring, and the tooling is adjusted for spraying.

[0009] Preferably, the S1 tension spring oil removal specifically includes cleaning with hot water at 50-70°C after ultrasonic cleaning for 10 minutes, and finally blowing the surface of the tension spring dry with compressed air, and placing the tension spring in an oven for drying at 80-100°C for 10 minutes.

[0010] Preferably, in S2, the tooling is adjusted to stretch the length of the tension spring from 29mm to 39mm.

[0011] Preferably, the spraying step specifically includes:

[0012] S21, first spraying, hanging the special tooling for the tension spring on the spraying hanging rod in the feeding area for spraying;

[0013] S22, first baking, after the first spraying, hanging the special tooling for the tension spring on the transport rack car to start baking, conveying the rack car to the baking area through the conveying chain, and conveying the rack car to the cooling area after the baking is completed, and cooling the spring to room temperature;

[0014] S23, second spraying, reinstalling the tension spring after the first baking on the special tooling for the tension spring, and adjusting the tooling for the second spraying;

[0015] S24, second baking, conveying the tension spring after the second spraying to the oven for baking;

[0016] S25, third spraying, taking the tension spring after the second baking off the special tooling and placing it on a tray, and supplementally spraying the contact points between the tension ring and the tooling;

[0017] S26, third baking, conveying the tension spring after the third spraying to the baking area, and conveying the rack car to the cooling area after the baking is completed, and cooling the spring to room temperature.

[0018] Further preferably, in S21, the first spraying process is as follows: the spraying gun pressure is 0.3-0.5MPa, the gun distance is 200-300mm, and the spraying gun moving speed is 300-600mm / s.

[0019] Further preferably, in S22, the first baking process is as follows: first, increasing the temperature to 80°C and keeping it for 10 minutes, then conveying the rack car to the feeding area, restoring the tension spring to a free state, and then conveying the rack car to the baking area, increasing the temperature to 120°C and keeping it for 15 minutes; and then increasing the temperature to 320°C and keeping it for 30 minutes.

[0020] Preferably, the second spraying process is the same as the first spraying process.

[0021] Preferably, the second baking process is the same as the first baking process.

[0022] Further preferably, in S26, the third baking process is as follows: the third-sprayed tension spring is sent to a baking area, heated to 120 DEG C, and kept for 15 min; then heated to 320 DEG C, and kept for 30 min.

[0023] Preferably, the special tooling comprises a fixed support, a plurality of uniformly distributed clamping hooks are arranged on the upper and lower horizontal rods of the fixed support respectively, the clamping hooks and the hook structures at the two ends of the spring form clamping, and the spring is stretched and fixed on the fixed support.

[0024] The present application has the following advantages:

[0025] The present application provides a kind of tension spring part of dacromet spraying process, by changing the traditional dacromet processing flow and parameter and designing tension spring spraying special tooling, make tension spring surface and spring ring are completely and evenly coated and thickness meets the requirement, greatly improve the corrosion resistance of tension spring, while guarantee that no redundant material is generated in the tension process of tension spring, eliminate the quality hidden danger of redundant material, ensure the successful flight of aerospace product, the performance of dacromet coating such as salt spray resistance, moisture resistance is far superior to the performance of galvanized layer, guarantee the normal use of tension spring in extreme environment. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 It is the structural schematic diagram of tension spring special tooling of the embodiment of the present application;

[0027] Figure 2 It is the schematic diagram of tension spring when spraying in free state of the embodiment of the present application;

[0028] Figure 3 It is the schematic diagram of tension spring when spraying in stretched state of the embodiment of the present application;

[0029] Figure 4 It is the schematic diagram of finished product of tension spring after dacromet treatment of the embodiment of the present application;

[0030] Figure 5 It is the schematic diagram of coating appearance detection between spring rings of the embodiment of the present application;

[0031] In the figure, 1 is fixed support;2 is horizontal rod;3, clamping hook. DETAILED DESCRIPTION

[0032] The present application will be described in detail below with reference to the accompanying drawings.

[0033] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application is further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and not to limit the present application.

[0034] A spring part Dacromet spraying process, comprising the following steps:

[0035] S1, oil removal of the spring, placing the spring in a cleaning frame, ultrasonic cleaning for 10 minutes, after ultrasonic cleaning, cleaning with hot water at 50-70 DEG C, and finally blowing the surface of the spring dry with compressed air, placing the spring in an oven, drying at 80-100 DEG C for 10 minutes;

[0036] S2, Dacromet spraying, as shown in Figures 1-3 The special tooling for the spring includes a fixed support 1, a plurality of evenly distributed hooks 3 are arranged on the upper and lower cross bars 2 of the fixed support 1 respectively, the hooks 3 and the hook structure at both ends of the spring form a clamping connection, and the spring is stretched and fixed on the fixed support 1. Adjust the distance between the cross bars 2 to stretch the length of the spring from 29 mm to 39 mm, and fix the position of the cross bars 2 with bolts, and then spray.

[0037] The spraying step specifically includes:

[0038] S21, first spraying, hanging the special tooling for the spring on the spraying hanging rod in the feeding area for spraying; the pressure of the spray gun is 0.3-0.5 MPa, the gun distance is 200-300 mm, and the moving speed of the spray gun is 300-600 mm / s.

[0039] S22, first baking, after the first spraying, hanging the special tooling for the spring on the transport rack car, conveying the rack car to the baking area through the conveying chain, heating to 80 DEG C, keeping warm for 10 minutes, then conveying the rack car to the feeding area, restoring the spring to a free state, conveying the rack car to the baking area again, heating to 120 DEG C, keeping warm for 15 minutes, then heating to 320 DEG C, keeping warm for 30 minutes, after the baking is completed, conveying the rack car to the cooling area, and cooling the spring to room temperature;

[0040] S23, second spraying, re-installing the spring after the first baking to the special tooling for the spring, adjusting the length of the spring in the tooling from 29 mm to 39 mm, and performing the second spraying; the second spraying process is the same as the first spraying process.

[0041] S24, second baking, conveying the spring after the second spraying to the oven for baking; the second baking process is the same as the first baking process.

[0042] S25. Third spraying: After the second baking, the tension spring is removed from the special tooling and placed on a tray. The contact points between the tension ring and the tooling are then sprayed again.

[0043] S26. Third baking: Send the springs after the third coating to the baking area. After baking, transport the frame to the cooling area and let the springs cool to room temperature. Send the springs after the third coating to the baking area, raise the temperature to 120℃ and hold for 15 minutes; then raise the temperature to 320℃ and hold for 30 minutes.

[0044] Finished product unloading: Remove the finished product from the tray, such as... Figure 3 , 4 As shown, the tension spring was stretched to its extreme state to test the appearance, thickness, salt spray resistance, and other properties of the part. After this process, the surface of the tension spring was uniformly coated with a Dacromet coating, and the performance of the coating was tested. The results are shown in Table 1 below.

[0045] Table 1. Coating performance test results

[0046]

[0047] The changes in spring length and force after Dacromet treatment are shown in Table 2 below. The total length of the springs after spraying is less than 29mm, and the spring lengths under different force values ​​also meet the design requirements.

[0048] Table 2 Results of changes in tension spring length and force.

[0049]

[0050] This invention is not limited to the specific embodiments described above. The invention extends to any new feature or combination disclosed in this specification, as well as any new method or process step or combination disclosed herein.

Claims

1. A process for the spray application of a Dacromet coating to a tension spring component, characterised in that, It comprises the following steps: S1, oil removal of tension spring, after oil removal of tension spring in ultrasonic cleaning tank, cleaning and drying; Specifically, after ultrasonic cleaning for 10 minutes, cleaning with 50-70 DEG C hot water, and finally blowing the surface of the tension spring dry with compressed air, placing the tension spring in an oven, drying at 80-100 DEG C for 10 minutes; S2, Dacromet spraying, installing the tension spring on the tension spring special tool, adjusting the tool to stretch the length of the tension spring from 29mm to 39mm for spraying; The step specifically comprises: S21, first spraying, hanging the tension spring special tool on the spraying hanging rod in the feeding area for spraying; S22, first baking, after the first spraying, hanging the tension spring special tool on the transport rack car to start baking, conveying the rack car to the baking area through the conveying chain, conveying the rack car to the cooling area after baking, and cooling the spring to room temperature; The baking process is as follows: first, the temperature is raised to 80 DEG C, and then the rack car is conveyed to the feeding area, the tension spring is restored to the free state, and then the rack car is conveyed to the baking area, the temperature is raised to 120 DEG C, and the temperature is kept for 15 minutes; Then, the temperature is raised to 320 DEG C, and the temperature is kept for 40 minutes; S23, second spraying, reinstalling the tension spring after the first baking to the tension spring special tool, and adjusting the tool for second spraying; S24, second baking, conveying the tension spring after the second spraying to the oven for baking; The second baking process is the same as the first baking process; S25, third spraying, taking the tension spring after the second baking from the special tool and placing it on the tray, and supplementing the contact point between the ring and the tool; S26, third baking, conveying the tension spring after the third spraying to the baking area, conveying the rack car to the cooling area after baking, and cooling the spring to room temperature; Conveying the tension spring after the third spraying to the baking area, raising the temperature to 120 DEG C, and keeping the temperature for 15 minutes; Then, the temperature is raised to 320 DEG C, and the temperature is kept for 40 minutes.

2. A process for the spray application of a Dacromet coating to a tensile spring component as claimed in claim 1, wherein In S21, the first spraying process is as follows: the pressure of the spray gun is 0.3-0.5 MPa, the gun distance is 200-300 mm, and the moving speed of the spray gun is 300-600 mm / s.

3. A process for the spray application of a Dacromet coating to a tensile spring component as claimed in claim 2, wherein The second spraying process is the same as the first spraying process.

4. A process for the spray application of a Dacromet coating to a tensile spring component as claimed in claim 1, wherein The special tool comprises a fixed support (1), a plurality of evenly distributed hooks (3) are arranged on the upper and lower cross bars (2) of the fixed support (1) respectively, the hooks (3) and the hook structure at both ends of the spring form clamping, and the spring is stretched and fixed on the fixed support (1).

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