Aviation spring precise shape control surface cleaning method

Abstract

The invention belongs to the field of aviation precision spring manufacturing, particularly relates to a precision surface cleaning method for cleaning dirt such as rust, oxidation color and sinter on the surface of a spring part, and belongs to the field of material engineering. The device has a good wire full-surface cleaning effect, gets rid of the influence of the sand blowing process on the geometric dimension and load performance of the spring part, and meanwhile avoids the problems of environmental pollution and health harm caused by the sand blowing process. The chemical plating surface of the part is cleaned by using the prepared grinding material and the cleaning solution, so that the effects of removing surface oxidation color, cleaning sinter and cleaning smudginess of the part are achieved, and the subsequent surface plating effect and the size and appearance of the part are ensured. The device is easy and convenient to operate and free of pollution problems such as noise and dust, and has a good production operation environment.

Description

Technical Field

[0001] The present invention belongs to the field of manufacturing of aerospace precision springs, and particularly relates to a precision surface cleaning method for cleaning dirt such as rust, oxidation color, and sintered substances on the surface of spring parts, belonging to the field of materials engineering. Background Art

[0002] In the field of manufacturing of aerospace parts, spring parts are mainly small-sized and high-precision springs, which have characteristics such as thin wire diameter, small overall size of the spring, high precision of the applied load, and harsh use environment. The processing and manufacturing of high-precision springs involve more than 10 materials such as Group II (70), 65Si2MnWA, 50CrVA, 3J1, 1Cr11Ni23Ti3MoB, 1Cr18Ni9Ti, 3Cr13, Zg, QSi3-1, etc., and usually involve multiple professional processing processes such as turning, fitting, heat treatment, and surface treatment. In the entire processing process, due to the small size and high precision of the springs, each process will affect their final part dimensions and output load. Among them, most importantly, before the surface plating process, to ensure the adhesion of the coating, it is necessary to ensure that the spring parts meet the requirements specified in HB5034 "Quality Requirements for Parts (Assemblies) before Plating": Heat-treated parts (assemblies) are not allowed to have undissolved scale, saline-alkali residues, and sintered substances caused by oil stains on the surface of parts (assemblies) before heat treatment.

[0003] In response to this, for dirt such as sintered substances and oxidation color generated by heat treatment, currently, a sandblasting process is adopted to clean the surface to achieve the required surface quality before plating. The sandblasting process uses compressed air as the power to form a high-speed jet beam to spray abrasive materials (quartz sand, steel sand, alumina, etc.) onto the surface of the workpiece at high speed. Due to the impact and grinding of the abrasive on the workpiece, it plays a certain cleaning role on the surface of the workpiece. Although this process is simple and efficient, it has a high degree of manualization. The state of spring parts depends on the technical level of the operator. Changes in parameters such as the air pressure, time, sand grain size, and nozzle distance of sandblasting will all affect the size and performance of the springs, easily leading to out-of-tolerance of dimensional performance such as the free height, output load, and pitch of the springs, resulting in a very high rejection rate of spring parts. Even slight deformation requires multiple repair processes, that is, stripping the coating → straightening → tempering after straightening → sandblasting → surface plating → finished product inspection. Due to multiple sandblasting processes, it is even more difficult to guarantee the dimensional performance of the finished product, seriously affecting the product delivery cycle and increasing the production cost of parts. Summary of the Invention

[0004] The core principle of the present invention lies in grinding and processing workpieces through mechanical movement. The planetary grinding and polishing equipment adopted by this method consists of two parts: a swing basket and a polishing cylinder. Abrasives with different particle sizes and shapes and polishing liquid are added into the cylinder. After the workpiece is placed, the cylinder revolves with the swing basket, and at the same time, the cylinder rotates by itself. Due to the mass difference between the abrasives with different particle sizes and the workpiece in the cylinder, relative movement is generated between the two, that is, random collisions and frictions are generated. At the same time, the polishing liquid plays the role of dissolving oil stains and lubricating and cooling, avoiding the problem of spring deformation caused by frictional heat generated due to excessive mechanical friction and collision, so as to achieve the effect of removing dirt on the spring surface and polishing. After the cleaning and drying post-treatment processes, it can well meet the quality requirements before surface plating.

[0005] In order to solve the above technical problems, the present invention innovatively provides a precision surface cleaning method for cleaning dirt such as rust, oxidation color and sintered matter on the surface of spring parts, which is used to improve the surface state of parts before surface chemical plating treatment. The invention adopts the planetary grinding and polishing process method to clean the surface of spring parts after heat treatment; uses the configured dry polishing abrasives and grinding liquid to clean and polish the spring surface; designs and manufactures a set of grinding and polishing stringing tooling for stringing spring parts during the grinding and polishing process to avoid spring winding and knotting.

[0006] According to one aspect of the present application, there is provided a method for precision shape control surface cleaning of aviation springs, including the following steps:

[0007] (1) Preliminary grinding: Place the spring on the stringing tooling in the cylinder, add No. 1 abrasive and cleaning agent to completely cover the spring, and perform grinding I to obtain a spring after preliminary grinding;

[0008] (2) Fine polishing: Place the spring after preliminary grinding on the stringing tooling in the cylinder, add No. 2 abrasive and cleaning agent, and perform grinding II to complete the precision shape control surface cleaning of the spring.

[0009] The proportion of the No. 1 abrasive is as follows:

[0010] Silicon carbide regular triangular prism abrasive (a3×(3 - 6)) 16wt% - 17.5wt%

[0011] Silicon carbide cuboid abrasive (3×2×(3 - 6)) 16wt% - 17.5wt%

[0012] Aluminum oxide spherical abrasive (SR0.3) 28.5wt% - 31wt%

[0013] Aluminum oxide spherical abrasive (SR0.5) 28.5wt% - 31wt%

[0014] The rest is aluminum oxide cylindrical abrasive.

[0015] The abrasive No. 2 is aluminum oxide cylindrical abrasive.

[0016] The proportion of the cleaning agent is as follows:

[0017] Sodium hydroxide: 15 g / L - 40 g / L;

[0018] Sodium phosphate: 30 g / L - 50 g / L;

[0019] Sodium carbonate: 20 g / L - 40 g / L;

[0020] Sodium silicate: 25 g / L - 35 g / L;

[0021] The rest is water.

[0022] The first grinding includes three stages;

[0023] First-stage rotational speed: 60 r / min - 80 r / min, time: 2 min - 3 min;

[0024] Second-stage rotational speed: 120 r / min - 140 r / min, time: 3 min - 5 min;

[0025] Third-stage rotational speed: 180 r / min, time: 25 min - 30 min.

[0026] The second grinding includes three stages;

[0027] First-stage rotational speed: 60 r / min - 80 r / min, time: 2 min - 3 min;

[0028] Second-stage rotational speed: 120 r / min - 140 r / min, time: 3 min - 5 min;

[0029] The third-stage rotational speed and time are determined according to the removal state of the surface of the spring after preliminary grinding. If there are no visible contaminants such as sintered substances, oxidation colors, and spots on the surface, the third-stage rotational speed: 120 r / min - 140 r / min, time: 5 min - 10 min. If there are still visible contaminants such as sintered substances, oxidation colors, and spots on the surface, the third-stage rotational speed: 180 r / min, time: 8 min - 15 min.

[0030] The springs can be stacked on the hanging fixture in the barrel.

[0031] The height of the spring is 7 / 10 of the height of the barrel;

[0032] After adding abrasive No. 1 or abrasive No. 2, 8 / 10 of the solvent in the barrel is occupied, and then a cleaning agent is added to make the liquid level in the barrel reach 9 / 10 of the height of the barrel.

[0033] The hanging tooling is a vertical rod arranged at the bottom of the barrel.

[0034] Specifically,

[0035] Initial grinding:

[0036] Auxiliary material preparation: Prepare a cleaning solution by mixing abrasive with water in accordance with a ratio, and prepare No. 1 mixed abrasive by mixing abrasive powder in accordance with a ratio. During the preparation process, the abrasives are added in order from large to small particle size to ensure that the small-sized abrasives can be fully mixed into the gaps of the large-sized abrasives.

[0037] Part loading: Place the parts on the hanging tooling in a 1.5L - 2.5L barrel and arrange them layer by layer (after completing the single-layer spring arrangement, add No. 1 mixed abrasive to completely cover the springs, then place the second-layer springs and add abrasive, and so on), ensuring the spring spacing. Through this loading method, the problem of part deformation caused by mutual entanglement between springs after grinding and polishing can be avoided. The total height of the stacked spring heads and tails is 7 / 10 of the barrel height, the total amount of No. 1 mixed abrasive and parts added is 8 / 10 of the barrel volume, and then slowly add the prepared cleaning solvent until the liquid level scale is at 9 / 10 of the barrel.

[0038] Grinding and removal: Seal the barrel tightly, install it in the cradle, and fasten the lock. Set the first-stage rotation speed: 60r / min - 80r / min, time: 2min - 3min; second-stage rotation speed: 120r / min - 140r / min, time: 3min - 5min; third-stage rotation speed: 180r / min, time: 25min - 30min, and gradually increase the equipment rotation speed.

[0039] Part unloading: After the equipment rotation speed returns to zero, remove the barrel cover and unload the parts and abrasive. Pour the abrasive and parts into the sieve basket, sieve out and separate the parts, and wait for the next process.

[0040] Fine polishing:

[0041] Part loading: Place the parts on the hanging tooling in a 1.5L - 2.5L barrel and arrange them layer by layer (after completing the single-layer spring arrangement, add No. 2 fine polishing abrasive to completely cover the springs, then place the second-layer springs and add abrasive, and so on), ensuring the spring spacing. Through this loading method, the problem of part deformation caused by mutual entanglement between springs after grinding and polishing can be avoided. The total height of the stacked spring heads and tails is 7 / 10 of the barrel height, the total amount of No. 2 fine polishing abrasive and parts added is 8 / 10 of the barrel volume, and then slowly add the prepared cleaning solvent until the liquid level scale is at 9 / 10 of the barrel.

[0042] Remove by grinding. Seal the barrel tightly and install it in the cradle, then fasten the locking buckle. Set the first-stage rotation speed: 60 r / min to 80 r / min, time: 2 min to 3 min; the second-stage rotation speed: 120 r / min to 140 r / min, time: 3 min to 5 min; determine the third-stage rotation speed and time according to the removal state of the part surface. (a) If there are no visible contaminants such as sintered substances, oxidation colors, and spots on the part surface, set the third-stage rotation speed: 120 r / min to 140 r / min, time: 5 min to 10 min. (b) If there are the above-mentioned contaminants on the part surface, set the third-stage rotation speed: 180 r / min, time: 8 min to 15 min. Gradually increase the equipment rotation speed.

[0043] Part unloading: After the equipment rotation speed returns to zero, remove the barrel cover and unload the parts and abrasives. Pour the abrasives and parts into the sieve basket, sieve out and separate the parts, and wait for the next process.

[0044] Drying: Set the heating temperature: 100 °C, heat preservation time: 20 min, until the parts are dry.

[0045] The grinding and polishing hanging tooling is used to string spring parts during the grinding and polishing process to prevent the springs from winding and knotting with each other during the rolling grinding and polishing process, and to avoid large changes in the dimensional performance of the parts beyond the tolerance during disassembly. The overall tooling is as Figure 1 shown, and it is composed of two parts: a polishing barrel and a hanging tooling.

[0046] The polishing barrel is as Figure 2 shown, including the barrel body 1, the barrel cover 2, and the wedge pin 3.

[0047] The barrel body 1, as Figure 2 shown, is used to load parts for grinding and polishing. The barrel handle not only facilitates hand-held loading and unloading, but also can fasten the barrel to the cradle through the handle to prevent it from falling during the grinding and polishing process. The inside of the barrel is lined with polytetrafluoroethylene, which has excellent chemical inertness and stability.

[0048] The barrel cover 2, as Figure 2 shown, after the parts are loaded into the barrel body, the barrel cover 2 is locked and closed through the wedge pin 3.

[0049] The hanging tooling 4, as Figure 3 shown, is used to string the springs on the tooling with the head and tail end faces connected and stacked, avoiding the overlap between two spring coils.

[0050] The advantages of the present invention are as follows: The present invention provides a planetary grinding and polishing surface cleaning process method for springs after heat treatment. This grinding and polishing process replaces the sandblasting surface cleaning process for springs, having a good cleaning effect on the entire surface of the wire. It gets rid of the influence of the sandblasting process on the geometric dimensions and load performance of the spring parts themselves, and at the same time avoids the environmental pollution and health hazards brought by the sandblasting process itself. On the contrary, the planetary grinding process mainly relies on the revolution of the barrel along with the swing basket, and at the same time the barrel rotates itself. Due to the mass difference between the abrasive of different particle sizes and the workpieces in the barrel, relative movement occurs between the two, that is, random collisions and frictions occur, so as to achieve the effect of removing surface dirt. The chemical plating surface of the parts is cleaned by using the configured abrasive and cleaning solution, which plays a role in removing the surface oxidation color, cleaning the sintered matter and cleaning the dirt of the parts, and ensuring the subsequent surface plating effect and the size and shape of the parts. The operation of the present invention is simple, without pollution problems such as noise and dust, and has a good production operation environment. Description of the Drawings

[0051] Figure 1 It is a schematic diagram of the grinding and hanging tooling, where a is the front view, b is the left view, and c is the top view;

[0052] Figure 2 It is an axonometric view of the grinding and hanging tooling, where a is the state when the barrel cover is open and b is the state when the barrel cover is closed;

[0053] Figure 3 It is a schematic diagram of the hanging tooling, where a is the top view and b is the front view.

[0054] Among them, 1 is the barrel body, 2 is the barrel cover, 3 is the wedge pin, and 4 is the hanging tooling. Detailed Embodiment

[0055] The following describes the present application in detail with reference to the embodiments, but the present application is not limited to these embodiments.

[0056] Embodiment 1

[0057] The surface cleaning method for a 65Si2MnWA compression spring before cadmium plating.

[0058] 1) Inspection: Check all dimensions, perpendicularity ⊥ and number of turns of the spring 100% according to the process drawings. Detect that the load of the spring under the specified stroke meets the process requirements, avoid the spring dimensions and force values being at the upper and lower limits of the tolerance zone, and strictly ensure that the dimensions, stroke and force values of the spring meet the requirements of the process drawings before grinding and polishing.

[0059] 2) Grinding and removal:

[0060] ① Auxiliary material preparation: Prepare a cleaning solution by mixing abrasive with water according to a ratio, and prepare a No. 1 mixed abrasive by mixing abrasive materials according to a ratio. During the preparation process, add abrasive materials in order from large to small particle size, and place them in a mixing container and stir.

[0061] ② Part loading: Make the head and tail end faces of the compression springs contact each other, string them on the stringing tooling (4) inside the cartridge (1 - 3), place them layer by layer, ensure the spring spacing to avoid the springs being entangled with each other after grinding and polishing. Among them, the size of the cartridge is Φ89mm×230mm, the solvent is 1.5L, the total height of the stacked head and tail of the springs is 7 / 10 of the height of the cartridge, the total amount of the mixed abrasive and parts added is 8 / 10 of the volume of the cartridge, and then slowly add the prepared cleaning solvent until the liquid level scale is at 9 / 10 of the cartridge.

[0062] ③ Grinding and removal: Seal the cartridge (1 - 3) and install it in the cradle. Set the first - order rotation speed: 80r / min, time: 2min; second - order rotation speed: 140r / min, time: 3min; third - order rotation speed: 180r / min, time: 25min.

[0063] ④ Part unloading: After the equipment speed returns to zero and stops stably, remove the cartridge cover and unload the parts and abrasive, waiting for the next process.

[0064] 3) Fine polishing:

[0065] ① Part loading: Make the head and tail end faces of the compression springs contact each other, string them on the stringing tooling (4) inside the cartridge (1 - 3), and add No. 2 fine polishing abrasive (the added amount is 7 / 10 of the volume of the cartridge). Then add the prepared cleaning solvent (until the liquid level scale is at 9 / 10 of the cartridge).

[0066] ② Grinding and removal: Seal the cartridge and install it in the cradle. Set the first - order rotation speed: 80r / min, time: 2min; second - order rotation speed: 140r / min, time: 3min; third - order rotation speed and time: Determine according to the surface removal state of the parts in the previous stage.

[0067] ③ Part unloading: After the equipment speed returns to zero and stops stably, remove the cartridge cover and unload the parts and abrasive, waiting for the next process.

[0068] 4) Drying: Set the heating temperature: 100℃, holding time: 20min until the parts are dry.

[0069] The above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can make several deformations or substitutions, which should all be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A method for cleaning the precision-shaped surface of an aviation spring, characterized in that: It includes the following steps: (1) Preliminary grinding: Place the spring on the hanging fixture in the barrel, add abrasive No. 1 and cleaning agent to completely cover the spring, and perform grinding I to obtain a preliminarily ground spring; (2) Fine polishing: Place the preliminarily ground spring on the hanging fixture in the barrel, add abrasive No. 2 and cleaning agent, and perform grinding II to complete the cleaning of the precision-shaped surface of the spring.

2. The method according to claim 1, characterized in that: The proportion of the abrasive No. 1 is as follows: Silicon carbide regular triangular prism abrasive: 16wt% - 17.5wt%; Silicon carbide cuboid abrasive: 16wt% - 17.5wt%; Aluminum oxide spherical abrasive: 28.5wt% - 31wt%; Aluminum oxide spherical abrasive: 28.5wt% - 31wt%; The rest is aluminum oxide cylindrical abrasive.

3. The method according to claim 1, characterized in that: The abrasive No. 2 is aluminum oxide cylindrical abrasive.

4. The method according to claim 1, characterized in that: The proportion of the cleaning agent is as follows: Sodium hydroxide: 15g / L - 40g / L; Sodium phosphate: 30g / L - 50g / L; Sodium carbonate: 20g / L - 40g / L; Sodium silicate: 25g / L - 35g / L; The rest is water.

5. The method according to claim 1, characterized in that: The grinding I includes three stages; First-stage rotation speed: 60r / min - 80r / min, time: 2min - 3min; Second-stage rotation speed: 120r / min - 140r / min, time: 3min - 5min; Third-stage rotation speed: 180r / min, time: 25min - 30min.

6. The method according to claim 1, characterized in that: The grinding II includes three stages; First-stage rotation speed: 60r / min - 80r / min, time: 2min - 3min; Second-stage rotation speed: 120r / min - 140r / min, time: 3min - 5min; Determine the third-stage rotation speed time according to the removal state of the surface of the preliminarily ground spring. If there are no visible contaminants such as sintered substances, oxidation colors, and spots on the surface, the third-stage rotation speed: 120r / min - 140r / min, time: 5min - 10min. If there are still visible contaminants such as sintered substances, oxidation colors, and spots on the surface, the third-stage rotation speed: 180r / min, time: 8min - 15min.

7. The method according to claim 1, characterized in that: The springs can be stacked on the hanging fixture in the barrel.

8. The method according to claim 1, characterized in that: The height of the spring is 7 / 10 of the height of the barrel; After adding abrasive No. 1 or abrasive No. 2, 8 / 10 of the solvent in the barrel is occupied, and then add cleaning agent to make the liquid level in the barrel reach 9 / 10 of the barrel height.

9. The method according to claim 1, characterized in that: The hanging fixture is a vertical rod arranged at the bottom of the barrel.

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