Aluminum plate surface degreasing method

Abstract

The invention discloses an aluminum plate surface degreasing method, and relates to the technical field of plate-fin heat exchangers, and the aluminum plate surface degreasing method comprises the following steps: S1, blowing an aluminum plate by using compressed air, and then carrying out low-temperature drying; s2, preparing a first soaking solution and a second soaking solution, wherein the pH value of the first soaking solution is greater than that of the second soaking solution; s3, the aluminum plate is soaked in a soaking pool containing a first soaking solution, then the aluminum plate is transferred into a soaking pool containing a second soaking solution, and after soaking is finished, the aluminum plate is taken out and washed with deionized water; and S4, the washed aluminum plate is subjected to hot air drying. According to the aluminum plate surface degreasing method provided by the invention, a single high-concentration alkali liquor is prevented from corroding a base material in a gradient alkali washing manner, and the process stability of the aluminum plate is improved while oil stains are effectively removed.

Description

Technical Field

[0001] This invention relates to the field of plate-fin heat exchanger technology, and more particularly to a method for degreasing the surface of aluminum plates. Background Technology

[0002] The main structure of plate-fin heat exchangers, such as fins, baffles, and seals, is mostly made of aluminum alloy sheets to ensure lightweight construction and high heat exchange efficiency. The processing technology of the aluminum sheets directly affects the heat transfer efficiency, corrosion resistance, sealing performance, and service life of the plate-fin heat exchanger. Therefore, the aluminum sheets need to undergo pretreatment to address issues such as surface oxidation and oil contamination, to avoid affecting the adhesion of subsequent surface treatments (such as brazing and coating).

[0003] Chinese patent application number 201610025252.9 discloses a method for surface powder coating to achieve corrosion and weather resistance of aluminum sheet and the aluminum sheet. The patent uses an alkaline degreasing agent to perform alkaline washing on the aluminum sheet. Although process water is used for cleaning afterward, the high concentration of alkaline solution will corrode the substrate, and the single-component alkaline solution cannot remove different types of oil stains. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a method for degreasing the surface of aluminum sheets. By employing a gradient alkaline washing approach, the method avoids corrosion of the substrate by a single high-concentration alkaline solution, effectively removing oil stains while improving the process stability of the aluminum sheets.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The present invention provides a method for degreasing the surface of aluminum sheet, comprising the following steps: S1: using compressed air to purge the aluminum sheet, and then drying it at low temperature; S2: preparing a first soaking solution and a second soaking solution, wherein the pH value of the first soaking solution is greater than the pH value of the second soaking solution; S3: first immersing the aluminum sheet in a soaking tank containing the first soaking solution, and then transferring it to a soaking tank containing the second soaking solution, and after soaking, removing the aluminum sheet and rinsing it with deionized water; S4: drying the rinsed aluminum sheet with hot air.

[0006] The degreasing method for aluminum sheet surface provided by the present invention preferably includes a drying temperature of 60-80℃ and a drying time of 10-20min in step S1.

[0007] The degreasing method for aluminum sheet surface provided by the present invention preferably includes, in step S2, the components of the first soaking solution are 30-40 parts sodium hydroxide, 20-25 parts sodium carbonate and 5-8 parts chelating agent; the soaking time of the aluminum sheet in the first soaking solution is 5-8 minutes.

[0008] The aluminium plate surface degreasing method provided by the application, preferably, in step S2, the components of the second soaking solution are 10-15 parts of sodium hydroxide, 10-20 parts of trisodium phosphate and 1-2 parts of corrosion inhibitor; the aluminium plate is soaked in the second soaking solution for 3-5 min.

[0009] The aluminium plate surface degreasing method provided by the application, preferably, in step S3, high-pressure air is introduced into the soaking pool for stirring during the soaking of the aluminium plate.

[0010] The aluminium plate surface degreasing method provided by the application, preferably, in step S4, the temperature of the hot air drying is 100-120 DEG C, and the duration is 10-15 min.

[0011] The aluminium plate surface degreasing method provided by the application has the following advantages or beneficial effects: The aluminium plate surface degreasing method provided by the application relates to the technical field of plate-fin heat exchangers and comprises the following steps: S1: compressed gas is used to blow the aluminium plate, and then low-temperature drying is performed; S2: a first soaking solution and a second soaking solution are configured, and the pH value of the first soaking solution is greater than that of the second soaking solution; S3: the aluminium plate is first soaked in a soaking pool provided with the first soaking solution, and then transferred into a soaking pool provided with the second soaking solution, and after the soaking is completed, the aluminium plate is taken out and washed with deionized water; and S4: the washed aluminium plate is dried by hot air. The aluminium plate surface degreasing method provided by the application avoids corrosion of the base material by single high-concentration alkali solution through gradient alkali washing, effectively removes oil stains, and improves the process stability of the aluminium plate. BRIEF DESCRIPTION OF DRAWINGS

[0012] The accompanying drawings, which are incorporated herein and constitute part of the specification, illustrate embodiments consistent with the application and, together with the description, serve to explain the principles of the application.

[0013] Figure 1 A process flow chart of the aluminium plate surface degreasing method provided for the embodiment 1 of the application. DETAILED DESCRIPTION

[0014] The exemplary embodiments will be described in detail hereinbelow with reference to the drawings. The following description refers to the accompanying drawings that show embodiments of the application by way of example. Where the description refers to the accompanying drawings, the same numbers in different drawings refer to the same or similar elements unless otherwise stated. The following exemplary embodiments described are not representative of all embodiments consistent with the application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of the application as detailed in the appended claims.

[0015] Embodiment 1: As Figure 1 shown: The application provides an aluminum plate surface degreasing method, which comprises the following steps: S1: using compressed air to blow the aluminum plate, and then performing low-temperature drying; S2: configuring a first soaking liquid and a second soaking liquid, the pH value of the first soaking liquid being greater than the pH value of the second soaking liquid; S3: first soaking the aluminum plate in a soaking pool provided with the first soaking liquid, and then transferring the aluminum plate into a soaking pool provided with the second soaking liquid, taking out the aluminum plate after the soaking is completed, and performing flushing with deionized water; and S4: performing hot air drying on the aluminum plate after the flushing.

[0016] In steps S2 and S3, the first soaking liquid and the second soaking liquid are used to gradiently perform alkali cleaning on the aluminum plate, so that different oil stains on the surface of the aluminum plate can be cleaned. The first soaking liquid provides a strong alkaline environment, can accelerate the saponification reaction of mineral oil, and can strengthen the emulsification of synthetic oil, so that oil droplets are wrapped and dispersed in water by a surfactant. The alkaline component in the composition can hydrolyze to generate hydroxyl groups, which can assist in enhancing alkalinity, and can maintain the stability of the overall pH value, avoiding the consumption of too much hydroxyl groups by oil stains to cause a decrease in concentration. The second soaking liquid can remove residual oil stains, protect the base material and optimize the surface state of the aluminum plate. The low-alkaline environment can reduce the corrosion rate of the aluminum plate. The low-concentration alkali solution can reduce the corrosion rate of the aluminum substrate, and the hydrolysis of trisodium phosphate and the reaction with aluminum ions can generate a dense aluminum phosphate protective film, which can further inhibit corrosion. In order to avoid a sharp decrease in the concentration of a single tank, the first soaking liquid and the second soaking liquid are arranged in two different tanks, and the two tanks are arranged in series.

[0017] After the soaking is completed, the aluminum plate can be etched with an acidic solution before being flushed with deionized water. The acidic solution can contain low-concentration fluorine ions, which can dissolve the oxide film on the surface of the aluminum plate and a small amount of aluminum hydroxide remaining after alkali cleaning. The fresh aluminum substrate is exposed after etching, the organic components in the residual oil stains are oxidized by an oxidizing agent, so that the organic components are more easily removed by flushing, and the secondary oxidation of the surface of the aluminum plate is inhibited.

[0018] The aluminum plate surface degreasing method provided by the application can simultaneously process mineral oil, synthetic oil, mixed oil, and various complex forms such as floating oil, attached oil and gap oil; for the multi-process processing scene of the aluminum plate of the plate-fin heat exchanger, the method can realize efficient oil removal without adjusting the formula, and solves the problem that the traditional process needs to frequently adjust the alkali concentration according to the type of oil stains.

[0019] In one preferred scheme of the embodiment, in step S1, the drying temperature of the aluminum plate is 60-80 DEG C, and the drying time is 10-20 min.

[0020] In one preferred embodiment of the present embodiment, in step S2, the components of the first soaking solution are 30-40 parts of sodium hydroxide, 20-25 parts of sodium carbonate and 5-8 parts of chelating agent; the aluminum plate is soaked in the first soaking solution for 5-8 min. The high-concentration lye generates soluble sodium fatty acid through saponification reaction of mineral oil, and emulsification reaction disperses the oil droplets of synthetic oil; the low-concentration lye further removes residual oil stains, and the chelating agent can avoid the formation of insoluble soap scum attached to the surface.

[0021] In one preferred embodiment of the present embodiment, in step S2, the components of the second soaking solution are 10-15 parts of sodium hydroxide, 10-20 parts of trisodium phosphate and 1-2 parts of corrosion inhibitor; the aluminum plate is soaked in the second soaking solution for 3-5 min. The trisodium phosphate can react with aluminum ions to form a dense aluminum phosphate protective film, which can further inhibit corrosion. The corrosion inhibitor forms a monomolecular corrosion film on the surface of the aluminum plate through adsorption, which cooperates with the aluminum phosphate film to reduce the corrosion rate.

[0022] In one preferred embodiment of the present embodiment, in step S3, high-pressure air is introduced into the soaking tank for stirring during the soaking process, which can avoid local non-uniform concentration of the lye.

[0023] In one preferred embodiment of the present embodiment, in step S4, the temperature of the hot air drying is 100-120°C, and the duration is 10-15 min.

[0024] Other embodiments of the application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. It is intended that the specification and examples be considered as exemplary only, with the true scope and spirit of the application being indicated by the following claims.

[0025] It should be understood that the application is not limited to the precise construction that has been described above and illustrated in the accompanying drawings, and that various modifications and changes can be made by those skilled in the art without departing from the scope of the application. The scope of the application is limited only by the appended claims.

Claims

1. A method for degreasing the surface of an aluminum sheet, characterized by, The method comprises the following steps, S1: using compressed air to blow the aluminum plate, and then low-temperature drying; S2: configuring a first soaking liquid and a second soaking liquid, the pH value of the first soaking liquid being greater than that of the second soaking liquid; S3: first soaking the aluminum plate in a soaking pool provided with the first soaking liquid, then transferring into a soaking pool provided with the second soaking liquid, taking out the aluminum plate after ending the soaking, and washing with deionized water; S4: hot air drying the washed aluminum plate.

2. The aluminum sheet surface degreasing method according to claim 1, characterized by, In the step S1, the drying temperature of the aluminum plate is 60-80℃, and the drying time is 10-20min.

3. The aluminum sheet surface degreasing method according to claim 1, characterized by, In the step S2, the components of the first soaking liquid are 30-40 parts of sodium hydroxide, 20-25 parts of sodium carbonate and 5-8 parts of chelating agent; the aluminum plate is soaked in the first soaking liquid for 5-8min.

4. The aluminum sheet surface degreasing method according to claim 1, characterized by, In the step S2, the components of the second soaking liquid are 10-15 parts of sodium hydroxide, 10-20 parts of trisodium phosphate and 1-2 parts of corrosion inhibitor; the aluminum plate is soaked in the second soaking liquid for 3-5min.

5. The aluminum sheet surface degreasing method according to claim 1, characterized by, In the step S3, high-pressure air is introduced into the soaking pool to stir the aluminum plate during the soaking process.

6. The aluminum sheet surface degreasing method according to claim 1, characterized by, In the step S4, the temperature of the hot air drying is 100-120℃, and the duration is 10-15min.

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