Method for manufacturing high-strength aluminum foil for curtain by digesting brazing foil waste

Abstract

The invention relates to a method for manufacturing a high-strength aluminum foil for a curtain by digesting brazing foil waste, which comprises the following steps of: strictly controlling the chemical components of the waste, namely 0.9-1.3% of Si, 0.2-0.75% of Fe, less than or equal to 0.05% of Cu, 0.9-1.4% of Mn, 2.2-2.8% of Mg, less than or equal to 0.8% of Zn, less than or equal to 0.03% of Ti and the balance of Al, and by taking smelting, casting, soaking, hot rolling, cold rolling and finishing as main processes, optimizing the aluminum alloy ratio and the rolling process; and the problems of cast ingot cracking and rolling edge cracking caused by high impurities of the waste materials are innovatively solved. During smelting, 100% of waste materials are used, and aluminum ingots are not added; hot rolling adopts a staged vertical roll binding technology, so that edge cracking is reduced; cold rolling is combined with intermediate annealing to optimize a work-hardening curve, and stable performance of a finished product is ensured. The thickness of the finished aluminum foil is 0.10-0.3 mm, the tensile strength reaches 330-360 MPa, the ductility is larger than or equal to 1.5%, and the performance requirements of the curtain aluminum foil are met. According to the invention, 100% utilization of waste materials is realized, the cost is obviously reduced, the resource utilization efficiency is improved, and the method has wide market application prospects.

Description

Technical Field

[0001] The invention relates to the field of aluminum foil preparation, and more specifically to a method for manufacturing high-strength aluminum foil for curtains by digesting brazing foil waste. Background Art

[0002] In the automotive industry, the main alloys of radiator fins, tubes and plates include AA3003 (containing manganese), AA4343 (containing silicon) and AA7072 (containing zinc). These materials will generate a lot of waste during the production and processing, and these wastes contain a high proportion of manganese (Mn), silicon (Si) and zinc (Zn). However, there is a lack of products on the market that can directly digest these high-manganese, high-silicon and high-zinc wastes. Usually, these wastes can only be handled by takeout, but this treatment method has the following significant problems:

[0003] Large economic losses: The takeaway price of scrap is usually calculated with a discount, which is usually 20% or even lower, resulting in a lower utilization rate of raw material costs, which directly increases the economic losses of the company.

[0004] Long turnover cycle: The turnover cycle of waste takeout is relatively long. The waste needs to occupy storage space during the turnover process, and the metal stacking problem further affects the production efficiency of the enterprise.

[0005] Therefore, it is particularly important to develop a new product that can efficiently digest these high-manganese, high-silicon, and high-zinc wastes. On the one hand, the product needs to achieve 100% digestion of the waste to ensure the improvement of production efficiency and the timeliness of metal flow; on the other hand, by making full use of the waste, the production cost can be greatly reduced, creating higher economic value for the enterprise. Summary of the invention

[0006] In order to solve the shortcomings of the prior art, a method for manufacturing high-strength aluminum foil for curtains by digesting brazing foil waste is provided. The specific scheme is as follows:

[0007] A method for manufacturing high-strength aluminum foil for curtains by digesting brazing foil waste, the manufacturing method comprising the following steps:

[0008] S1. Smelting: Select brazing foil scrap with high manganese, high silicon and high zinc content, and control the chemical composition to be Si 0.9-1.3%, Fe 0.2-0.75%, Cu≤0.05%, Mn 0.9-1.4%, Mg 2.2-2.8%, Zn≤0.8%, Ti≤0.03%, and the balance is Al for smelting;

[0009] S2, casting, soaking, milling, sawing: use 450×1450mm specification crystallizer for casting, casting speed is 30~50mm / min, crystallizer liquid level height is 40±5mm, aluminum liquid temperature is 690~730℃ during casting; soaking, sawing, milling treatment is carried out after casting;

[0010] S3, hot rolling: preheating treatment is performed before hot rolling; the ingot is preheated to 490-510℃, and 19 passes of repeated reversible rolling are adopted, and the final rolling temperature is controlled at 280-320℃. At the same time, the rolling technology of large vertical roll and small vertical roll is combined to reduce edge cracking;

[0011] S4, cold rolling: During the cold rolling process, after rolling to a thickness of 1.5 mm, intermediate annealing is performed at an annealing temperature of 220-280°C, and finally the finished product thickness is rolled to 0.10-0.3 mm;

[0012] S5. Finishing: The finishing process uses coiling and curling technology to cut into finished product width, and the waste edges are recycled by winding.

[0013] Furthermore, the S1 smelting parameters are a melting temperature of 750°C, a melting furnace sampling temperature of 730-750°C, a pouring furnace temperature of 735-755°C, an aluminum liquid temperature of no more than 760°C during the entire smelting process, and a melting furnace temperature of 1050°C; the component elements Cu / Zn are controlled according to the actual values ​​of the calculated detection, and no further feeding is performed.

[0014] Furthermore, during the S2 casting process, the water pressure is controlled at 0.6-0.8 MPa; the aluminum liquid temperature in the online degassing box is 690-730°C, the casting flow plate temperature is 690-700°C, and the temperature fluctuation shall not exceed 5°C after the casting is stable. The filter plate adopts deep bed filtration plus plate filtration for double filtration to intercept impurities. The filter plate uses 40-50PPI specification filter plates, and the diversion belt uses 30-40P large-pore specifications.

[0015] Furthermore, the uniform heating temperature in S2 is 450-550°C; 6 surfaces are milled during milling, including the upper, lower, left, right and inclined surfaces; the milling amount of the upper and lower surfaces is 10±5mm respectively, and the milling amount of the left and right sides is 10±5mm respectively.

[0016] Furthermore, the preheating time in S3 is 12 to 18 hours; during hot rolling, the emulsion temperature is controlled at 50 to 60°C, and the final rolling temperature is controlled at 280 to 320°C.

[0017] Furthermore, the Ti content of the melting furnace is controlled at 0.03-0.05%. If the Ti content of the detected sample is <0.03%, Ti is supplemented to 0.03%, and if it is >0.03%, no material is supplemented; if the Ti content is >0.05%, no dilution is performed; the refining agent is a smokeless refining agent, the melting furnace (1kg / t furnace load) ±5kg, the holding furnace (2.5kg / t*furnace load) ±5kg; the actual refining time is 30min (excluding the time for changing the refining agent), the refining temperature is (720-740℃); the splashing height of the aluminum liquid is controlled to be less than 200mm; the refining medium is argon refining, and the refining is performed twice in the melting furnace and the holding furnace respectively.

[0018] Furthermore, a staged vertical roll hemming technology is adopted in the hot rolling process, with large vertical rolls used in the first stage and small vertical rolls used in the second stage, and the vertical roll gap difference is controlled within 5 mm.

[0019] Furthermore, in the cold rolling process in S4, a roughing roll with a convexity of +0.02 mm and a roughness of 0.5-0.7 μm is used; and a finishing roll with a convexity of +0.06 mm and a roughness of 0.25-0.4 μm is used during the finish rolling.

[0020] Furthermore, a vertical double-winding slitting machine is used in the finishing process of S5, and the slitting waste edges are recycled by winding the aluminum core.

[0021] Beneficial effects:

[0022] The method for manufacturing high-strength aluminum foil for curtains by digesting brazing foil waste proposed by the present invention has the following significant beneficial effects:

[0023] (1) First, 100% digestion of brazing foil waste was achieved, making full use of high-manganese, high-silicon, and high-zinc waste resources without adding aluminum ingots, reducing the cost of raw material procurement and improving the utilization efficiency of waste. Through the smelting process, the chemical composition is precisely controlled, the ratio is optimized, and the impurity elements in the waste are digested, avoiding the economic losses caused by traditional takeaway waste treatment.

[0024] (2) The aluminum foil products manufactured have excellent mechanical properties. The tensile strength of the finished product reaches 330-360MPa, and the elongation is ≥1.5%, which meets the performance requirements of high-strength curtain aluminum foil. The optimized process of intermediate annealing and work hardening is adopted to ensure that the finished product has uniform grain size, mechanical properties and surface quality.

[0025] (3) By improving the casting process (such as optimizing the crystallizer specifications, casting temperature, filtering equipment and process parameters), the problems of ingot cracking and impurities were effectively solved. The hot rolling and cold rolling processes were optimized, especially the introduction of staged vertical roller rolling technology, which effectively reduced the edge cracking phenomenon and improved the stability and efficiency of rolling. By combining cold rolling multi-pass continuous rolling with intermediate annealing, the problem of work hardening was solved and the thickness and surface quality of the final product were guaranteed.

[0026] (4) The coiling and curling technology is used to recycle the scrap edges in the finishing process, without the need for manual processing, reducing processing pauses caused by scrap edge breakage and significantly improving production efficiency. The aluminum core recovered in the finishing process is further recycled, which improves resource utilization and reduces the waste treatment cost of the production process. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a work hardening curve established in the cold rolling process of the embodiment.

[0028] Figure 2 This is an electron microscope analysis diagram of the ingot surface layer segregation and compounds.

[0029] Figure 3 This is a physical picture of the hot rolled coil before improvement.

[0030] Figure 4 This is a physical picture of the hot-rolled coil after improvement.

[0031] Figure 5 It is the grain size after intermediate annealing after the cold rolling process in the embodiment. DETAILED DESCRIPTION

[0032] In order to deepen the understanding of the present invention, the present invention will be further described in detail below in conjunction with examples. The examples are only used to explain the present invention and do not constitute a limitation on the protection scope of the present invention.

[0033] Example:

[0034] A method for manufacturing high-strength aluminum foil for curtains by digesting brazing foil waste, the manufacturing method comprising the following steps:

[0035] Heat transfer brazing material waste is selected as the melt and smelted into aluminum liquid. The chemical composition of various alloy wastes is calculated to obtain the desired chemical composition. The components and mass percentages are: Si 0.9-1.3%, Fe0.2-0.75%, Cu≤0.05%, Mn≤0.9-1.4%, Mg 2.2-2.8%, Zn≤0.8%, Ti≤0.03%, and the balance is Al.

[0036] Its chemical composition mainly contains high Si, high Mn, and Zn. The main purpose is to digest the chemical composition of heat transfer brazing waste. Its final composition formula is adjusted, optimized and finally determined through its later rolling analysis and final product performance. It is adjusted based on the waste component elements. If the element exceeds the designed content, aluminum ingots are added for dilution. If a certain element is insufficient, intermediate alloys are added for adjustment. Among them, Mg element is mainly used to improve the strength of the product.

[0037] The invention is characterized in that 100% pure waste is added in the smelting process, no aluminum ingot is added, and all waste is digested, mainly high in Mn, Si, and Zn impurities, which are easy to crack, including ingot cracking and edge cracking during rolling. The invention solves the problem of being unable to perform deep processing. The specific steps are as follows:

[0038] Melting process: melting temperature 750℃, melting furnace sampling temperature: 730-750℃, pouring furnace temperature 735-755℃, aluminum liquid temperature during the whole melting process shall not exceed 760℃, melting furnace temperature is set to 1050℃; component elements Cu / Zn are controlled according to the actual value of the calculated detection, and no more material is added. The Ti content of the melting furnace is controlled at 0.03-0.05% (if the content of 0# sample is <0.03%, then Ti is added to 0.03%, if it is >0.03%, no material is added; >0.05%, no dilution;

[0039] The refining agent is smokeless refining agent, melting furnace (1kg / t furnace load) ±5kg, holding furnace (2.5kg / t*furnace load) ±5kg; the actual refining time is 30min (excluding the time for changing refining agent), refining temperature (720-740℃); the splash height of aluminum liquid is controlled to be less than 200mm; the refining medium is argon refining, and the refining is done twice in the melting furnace and the holding furnace respectively;

[0040] The casting process was initially debugged using a variety of mold specifications. For example, the typical specifications are 450*1450mm in thickness and 410*1850mm in width. The first typical specification is relatively narrow, while the second is relatively wide. The same process was compared with a variety of molds. The casting speed range is 30-50mm / min, the ingot length is 300-500mm, the crystallizer liquid level is 40±5mm, and the water pressure is controlled at 0.6-0.8mpa. The aluminum liquid temperature of the online degassing box is 690-730℃, the casting flow plate temperature is 690-700℃, and the temperature fluctuation shall not exceed 5℃ after the casting is stable. The filter plate adopts deep bed filtration plus plate filtration to intercept impurities. The filter plate uses 40-50PPI filter plates, and the diversion belt uses 30-40P large-pore specifications. In terms of the specifications of the ingot, multiple specifications are selected for test comparison, as shown in the following table. The ingot is too wide and is prone to cracking. Finally, the 450*1450mm casting crystallizer is selected as the best solution;

[0041] Crystallizer Specifications Ingot thickness Ingot width Width ratio Pros and Cons Solution 1 390 1450 3.72 Small roll weight Solution 2 410 1560 3.80 Roll weight is too small Solution 3 450 1850 4.11 Ingot cracking Solution 4 390 1850 4.74 Ingot cracking Solution 5 410 1560 3.80 Roll weight is too small Solution 6 450 1450 3.22 suitable

[0042] After casting, an ingot of 450*1450mm is produced. Due to some defects such as cold shut at the head of the ingot, it needs to be removed. The ingot is subjected to high-temperature soaking annealing in a soaking furnace. The purpose of soaking is to perform homogenization annealing to make the structure more uniform. On the other hand, it reduces the brittleness of the ingot and reduces the cracking phenomenon during the sawing process. On the other hand, it improves the mechanical properties of the final product; the uniform process temperature is between 450-550℃; therefore, soaking is a very important and key process, and it is also a process finally obtained after repeated exploration; after verification, the original inherent sawing first and then soaking is changed to soaking first and then sawing.

[0043] After casting, it needs to go through the milling process, which requires 6-sided milling, upper, lower, left, right and inclined milling. Figure 2 It can be seen that the surface aluminum block sample of the ingot is taken for side electron microscope analysis, and there are different degrees of compound aggregation on the surface, so it is very important to remove the surface impurities by milling; it has a profound impact on the subsequent processing; the milling amount of the upper and lower surfaces is 10±5mm, and the milling amount of the left and right sides is 10±5mm respectively.

[0044] After casting and milling, it is hot rolled. Before hot rolling, it is preheated. The preheating temperature is controlled between 490-510℃ and the preheating time is 12-18 hours. After 19 passes of hot rolling, the coil of about 6mm is finally obtained. The emulsion temperature is controlled at 50-60℃ and the final rolling temperature is controlled at 280-320℃. The temperature is mainly controlled by the cooling of the emulsion, the temperature of the ingot during preheating and the rolling speed of each pass. The faster the rolling speed, the higher the temperature, and vice versa. The auxiliary time must be calculated to control the final rolling temperature.

[0045] The longer the auxiliary time is, the faster the temperature drops;

[0046] The hot rolling process is also one of the key processes of this product. After hot rolling, the edges are prone to cracking and the cracks are large. The hot rolling process has a certain degree of expansion after rolling. In addition, this alloy has many impurities and is prone to silicon cracking, resulting in large cracks on the finished product.

[0047] If the hot-rolled edge has a large crack, the cold-rolled process cannot be continued, and the strip is prone to breakage, which also affects production efficiency. To solve this problem, the following aspects are mainly tackled in combination with the on-site situation. On the one hand, the final rolling temperature is guaranteed. The lower the temperature, the greater the probability of silicon cracking. On the other hand, the vertical rollers are invested and optimized. The main idea is that the width is serious during the rolling process. The vertical rollers are invested in the rolling process. The vertical rollers are divided into large vertical rollers and small vertical rollers, and experiments are carried out in different passes. Secondly, the rolling passes are optimized, and the coiling is divided into 3 passes. The reduction amount of the 3 coiling passes, and the reduction amount distribution is first The reduction is 40-50% for one coiling pass, 35-40% for two coiling passes, and 25-35% for three coiling passes. Under the condition of keeping the total number of passes unchanged, the large reduction leads to high production efficiency, but too high reduction is easy to cause excessive rolling temperature, poor plate shape, silicon cracks, etc., and too low reduction and small rolling force will also cause poor plate shape. Therefore, reasonable control of reduction is very critical to rolling quality; on the other hand, most of the oxidized impurity compounds after milling are removed, which is also beneficial to controlling the cracks caused by impurities.

[0048] Vertical roller hemming mainly starts from the 2nd or 3rd pass before coiling. The first pass uses a large vertical roller, and the second pass uses a small vertical roller. The hemming is performed by combining large and small vertical rollers. The data of vertical roller usage on site are as follows:

[0049]

[0050]

[0051] It was found on site that different process settings of roll gaps resulted in different hemming effects, i.e., different cracking effects of hot-rolled finished coils. From the data, it can be seen that the process set the roll gap (i.e., the process setting), while the actual measured roll gap value of the vertical roll has a large difference, so the actual material width cannot reach the process setting effect. During the execution of the vertical roll, it is difficult to reach the precise value due to the influence of hydraulic pressure and accuracy, resulting in the actual position of the vertical roll being difficult to reach the position set by the process, so the vertical roll is maintained and repaired; and from the data, it can be seen that the difference between the process setting value and the actual roll gap is basically qualified if it is more than 5mm, so normal production can be achieved by controlling the difference between the vertical roll parameter setting and the actual value within 5mm;

[0052] Many attempts have been made in the selection of the final thickness of the hot rolling product. On the basis of ensuring the edge of the vertical roll, and on the basis of the heating furnace temperature and the final rolling temperature of the finished product, different final rolling thicknesses have been tried. According to the on-site summary, the edge cracking of the 6.0mm hot rolled coil is relatively better than that of the 5.0mm hot rolled coil under the same rolling process. The hot rolled coils before and after the improvement are as follows: Figure 3 , 4 shown.

[0053] Cold rolling process, cold rolling adopts 2-3 continuous rolling. Due to the serious work hardening of the material, the subsequent work hardening strength increases, and the reduction gradually decreases. The edge is cut after 2-4 rolling passes. The cold rolling is rolled to about 1.5mm for intermediate annealing. Annealing is mainly to relieve work hardening and remove stress; after annealing, it is rolled to the finished product thickness through 4-6 passes; the cold rough rolling roll adopts +0.02mm convexity and 0.5-0.7um roughness, and the cold finishing roll adopts +0.06mm convexity and 0.25-0.4um roughness. The finished product thickness is between 0.10-0.3mm, state H19, tensile strength 330-360mpa, elongation ≧1.5%; it meets the product standards of curtain materials; the final determination of the annealing temperature is explored on site, and the work hardening curve is compiled as follows Figure 1 , determine the intermediate annealing thickness, intermediate annealing thickness and intermediate annealing temperature determine the performance of the final product, and also consider the work hardening, the site also according to each pass of the work hardening degree of work hardening curve is developed such as Figure 1 As shown in the curve, it can be concluded that in order to achieve the customer's requirement of a tensile strength of more than 330 MPa, the processing rate after annealing must reach more than 82%, so the thickness range of the intermediate annealing is determined; the grain size after the intermediate annealing is as follows Figure 5 shown.

[0054] The finishing process is the trimming and stripping of the finished product. The slitting is carried out according to the specifications of the customer's finished product order. According to the width of the final finished product, it is slit into about 1 to 6 strips. There is no stripping between each strip. There are waste edges at both ends of the knife shaft. The waste edges are initially pulled to the waste edge machine by traction rollers for winding, but the waste is brittle and easy to break, which seriously affects the production efficiency; finally, the coiling type coiling method is adopted, and the rolled waste edge also uses aluminum core as a sleeve, which is coiled together with the coil. The generated waste does not need to be manually handled, and the aluminum core and waste edge are directly returned to the melting furnace for melting; the slitting machine is a vertical double coiling slitting machine with two expansion shafts at the front and back. The expansion shaft is a gas expansion shaft. The diameter increases during operation and shrinks when unloading to achieve the purpose of rolling up and down; the performance observations of the product in terms of performance and plate shape are as follows:

[0055]

[0056] In summary, the present invention not only solves the problem of waste brazing foil treatment and successfully realizes efficient waste digestion, but also improves the economic value and performance of the finished product, opens up a new feasible path for the manufacture of high-strength aluminum foil products, and has broad industrial application value and market prospects.

[0057] As a further improvement, the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for producing high-strength aluminum foil for curtains by digesting brazing foil waste, characterized in that: The manufacturing method comprises the following steps: S1. Smelting: Select brazing foil scrap with high manganese, high silicon and high zinc content, and control the chemical composition to be Si 0.9-1.3%, Fe 0.2-0.75%, Cu≤0.05%, Mn 0.9-1.4%, Mg 2.2-2.8%, Zn≤0.8%, Ti≤0.03%, and the balance is Al for smelting; S2, casting, soaking, milling, sawing: use 450×1450mm specification crystallizer for casting, casting speed is 30~50mm / min, crystallizer liquid level height is 40±5mm, aluminum liquid temperature is 690~730℃ during casting; soaking, sawing, milling treatment is carried out after casting; S3, hot rolling: preheating treatment is performed before hot rolling; the ingot is preheated to 490-510℃, 19 passes of repeated reversible rolling are adopted, and the final rolling temperature is controlled at 280-320℃. At the same time, the rolling technology of large vertical roll and small vertical roll is combined to reduce edge cracking; S4, cold rolling: During the cold rolling process, after rolling to a thickness of 1.5 mm, intermediate annealing is performed at an annealing temperature of 220-280°C, and finally the finished product thickness is rolled to 0.10-0.3 mm; S5. Finishing: The finishing process uses coiling and curling technology to cut into finished product width, and the waste edges are recycled by winding.

2. The method for manufacturing high-strength aluminum foil for curtains by digesting brazing foil waste according to claim 1, characterized in that: The S1 smelting parameters are melting temperature of 750℃, melting furnace sampling temperature of 730-750℃, pouring furnace temperature of 735-755℃, aluminum liquid temperature shall not exceed 760℃ during the whole smelting process, and the melting furnace temperature is set to 1050℃; the component elements Cu / Zn are controlled according to the actual values ​​of the calculated detection, and no more feeding is performed.

3. The method for manufacturing high-strength aluminum foil for curtains by digesting brazing foil waste according to claim 1, characterized in that: During the S2 casting process, the water pressure is controlled at 0.6-0.8 MPa; the aluminum liquid temperature in the online degassing box is 690-730°C, the casting flow plate temperature is 690-700°C, and the temperature fluctuation shall not exceed 5°C after the casting is stable. The filter plate adopts deep bed filtration plus plate filtration to intercept impurities. The filter plate uses 40-50PPI specification filter plates, and the diversion belt uses 30-40P large-pore specifications.

4. The method for manufacturing high-strength aluminum foil for curtains by digesting brazing foil waste according to claim 1, characterized in that: The uniform heating temperature in S2 is 450-550°C; when milling, 6 surfaces are milled, including the upper, lower, left, right and inclined surfaces; the milling amount of the upper and lower surfaces is 10±5mm respectively, and the milling amount of the left and right sides is 10±5mm respectively.

5. The method for manufacturing high-strength aluminum foil for curtains by digesting brazing foil waste according to claim 1, characterized in that: The preheating time in S3 is 12 to 18 hours; during hot rolling, the emulsion temperature is controlled at 50 to 60°C, and the final rolling temperature is controlled at 280 to 320°C.

6. The method for manufacturing high-strength aluminum foil for curtains by digesting brazing foil waste according to claim 2, characterized in that: The Ti content in the melting furnace is controlled at 0.03-0.05%. If the Ti content of the tested sample is <0.03%, Ti is supplemented to 0.03%. If it is >0.03%, no material is supplemented; if the Ti content is >0.05%, no dilution is performed.

7. The method for producing high-strength aluminum foil for curtains by digesting brazing foil waste according to claim 1, characterized in that: The hot rolling process adopts the staged vertical roll hemming technology. Large vertical rolls are used in the first stage and small vertical rolls are used in the second stage. The difference in the vertical roll gap is controlled within 5mm.

8. The method for producing high-strength aluminum foil for curtains by digesting brazing foil waste according to claim 1, characterized in that: In the cold rolling process of S4, a roughing roll with a convexity of +0.02mm and a roughness of 0.5-0.7μm is used; in the finish rolling, a finishing roll with a convexity of +0.06mm and a roughness of 0.25-0.4μm is used.

9. The method for manufacturing high-strength aluminum foil for curtains by digesting brazing foil waste according to claim 1, characterized in that: In the finishing process of S5, a vertical double-winding slitting machine is used, and the slitting waste edges are recycled by aluminum core winding.

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