Reciprocating type hot-extrusion upsetting solid-phase regeneration method for aluminum skimmings and deformation die thereof

Abstract

The invention discloses an aluminum scrap reciprocating type hot extrusion upsetting solid phase regeneration method which is characterized in that recycled aluminum scraps are cleaned and mechanically crushed to obtain aluminum scraps with the length smaller than 5 mm, and the aluminum scraps are subjected to mold pressing at the room temperature to obtain a preformed blank. And then the preformed blank is subjected to high-temperature reciprocating type hot extrusion upsetting deformation, the required deformed form secondary aluminum blank with the hardness being 38.3-44.2 HV, the yield strength being 72-92 MPa, the tensile strength being 113-144 MPa and the ductility being 24.5-28.4% is obtained, and after subsequent solution aging heat treatment, the secondary aluminum blank with the hardness being 118.1-122 HV and the tensile strength being 224-284 MPa is obtained. According to the method, the aluminum scrap solid-phase regeneration process can be obviously simplified, scrap regeneration and remelting are avoided, the machining efficiency is improved, meanwhile, it is ensured that a produced product has the large size, and the requirement for batch production can be met.

Description

Technical Field

[0001] The present invention relates to the technical field of metal material preparation, and in particular to a method for regenerating aluminum by utilizing aluminum chips. Background Art

[0002] The cutting process of aluminum alloy products generates a large amount of aluminum chips. This type of aluminum chips is produced in large quantities, contains few impurities, and is easily recyclable. Recycling it not only reduces the waste of aluminum ore resources, but also eases energy consumption during the production process and reduces the cost of aluminum products, with significant economic and social benefits. However, traditional aluminum chip recycling methods primarily rely on remelting, which results in high energy consumption and oxidation losses during the process, resulting in low recovery rates and high manufacturing costs. Solid-state recycling methods, on the other hand, avoid the high energy consumption, pollution, and loss rates associated with melting aluminum chips. Through plastic deformation, aluminum chips can be converted into profiles or component products with similar composition and performance to the original aluminum alloy. Therefore, solid-state recycling technology for aluminum chips has become a highly valued topic in various countries.

[0003] In the prior art, Chinese invention patent CN 105525150 B discloses a solid-state recycled aluminum alloy and its preparation method. Specifically, the method involves crushing and molding aluminum alloy chips to produce prefabricated blocks, then heating with an induction coil and using hot extrusion to deform the prefabricated blocks into aluminum alloy profiles of various cross-sections and sizes. The advantages of this invention are that the resulting solid-state recycled aluminum alloy has a tensile strength of 160-280 MPa, a yield strength of 70-120 MPa, and an elongation of 15-30%. Chinese invention patent CN 115287486 B discloses a method for preparing a mixed aluminum chip solid-state recycled aluminum alloy. Specifically, the method involves sequentially cold-pressing, hot-pressing, homogenizing, extruding, cooling, and aging a uniformly mixed aluminum chip and aluminum powder to produce a mixed aluminum chip solid-state recycled deformed aluminum alloy. The advantages of this invention are that the resulting solid-state recycled aluminum alloy is uniformly dense, has low porosity, and achieves mechanical properties equivalent to smelted aluminum alloy extruded profiles. However, these traditional solid-state regeneration of aluminum chips usually adopts hot extrusion process, and the porosity of the recycled aluminum produced is relatively large. Reducing the porosity often means increasing the extrusion ratio. This results in highly densified solid-state recycled aluminum billets usually having small cross-sectional dimensions and low production efficiency, making it difficult to achieve mass production.

[0004] A solid-state regeneration method for aluminum chips based on processes such as high-pressure torsion, equal-diameter angular extrusion, back-pressure reciprocating extrusion, and rolling can effectively promote the metallurgical bonding of aluminum chips by utilizing the principle of severe plastic deformation. Mohamad Syahmi Shahrom et al. (Shahrom M.S., Yusoff AR, Journal of Manufacturing Processes, 29 (2017), 1-9) conducted a study on the back-pressure reciprocating extrusion deformation of 6061 alloy chips. By subjecting the aluminum chips to multiple extrusion and upsetting deformations, the solid-state regenerated 6061 aluminum ingots prepared were 12.11% denser than those prepared by conventional hot pressing, and the hardness was basically the same as that of the material before processing. Abd El Aal MI (Abd El Aal MI, Journal of Materials Research and Technology, 14 (2021), 407-427) used a high-pressure torsion process to prepare solid-state regenerated aluminum sheets of pure aluminum and its composites. The obtained materials had an ultrafine grain structure and a relative density between 99.7% and 98.3%. However, this process also limits the size of the blocks produced, and the mold structure is complex, the forming equipment requirements are high, the multi-pass material discharge and removal process is cumbersome, and production efficiency is limited. Therefore, it is necessary to design and develop a fast solid-phase regeneration method for aluminum chips with high efficiency, low energy consumption, and high recovery rate. Summary of the Invention

[0005] The first purpose of the present invention is to overcome the shortcomings of the prior art and provide a reciprocating hot extrusion and upsetting solid phase regeneration method for aluminum chips, in order to solve the problems of high production cost, low processing efficiency and size limitation.

[0006] The second purpose of the present invention is to overcome the shortcomings of the prior art and provide a deformation die used in a reciprocating hot extrusion and upsetting solid phase regeneration method for aluminum chips, which has a simple structure and is easy to produce and use.

[0007] The first object of the present invention is achieved through the following technical solutions:

[0008] A reciprocating hot extrusion and upsetting solid phase regeneration method for aluminum chips is characterized in that the preparation method is carried out in sequence according to the following steps:

[0009] (1) Recovering aluminum chips and cleaning them for later use;

[0010] (2) Mechanically crushing the cleaned aluminum chips to obtain aluminum chips with a length of less than 5 mm;

[0011] (3) Pour an appropriate amount of aluminum scrap into a steel mold and press-dry at room temperature to obtain a low-density preform;

[0012] (4) The preform is heated to 400-550°C and deformed by reciprocating hot extrusion and upsetting to obtain a deformed recycled aluminum billet.

[0013] Preferably, the recycled aluminum chips in step (1) are pure aluminum chips or aluminum alloy aluminum chips.

[0014] Preferably, the diameter of the mold for pressing the blank in step (3) is 3 to 20 cm, the pressing pressure is 150 to 300 MPa, and the holding time is 10 to 60 s.

[0015] The reciprocating hot extrusion and upsetting deformation in step (4) is to provide driving force and back pressure along the axial direction of the bar through the upper and lower punches to perform reciprocating extrusion and upsetting composite deformation on the bar.

[0016] Preferably, the cross-section of the reciprocating hot extrusion upsetting deformation die in step (4) is circular, elliptical, rectangular, square or other polygonal shapes.

[0017] Preferably, the extrusion ratio of the reciprocating hot extrusion upsetting deformation die in step (4) is ≥2.5.

[0018] Preferably, the extrusion speed of the reciprocating hot extrusion deformation in step (4) is 0.5 to 10 mm / s.

[0019] Preferably, the number of passes of the reciprocating hot extrusion deformation in step (4) is 1 to 4.

[0020] Preferably, the deformed recycled aluminum billet in step (4) can be further subjected to solution aging heat treatment, with a solution temperature of 500-550°C, a solution time of 1-4 hours, an aging temperature of 160-200°C, and an aging time of 6-12 hours.

[0021] The second object of the present invention is achieved through the following technical solutions: a deformation die in any of the above-mentioned aluminum chip reciprocating hot extrusion and upsetting solid phase regeneration methods, characterized in that it includes a left die block and a right die block that are opposite to each other on the left and right to form a deformation chamber that passes through from top to bottom. The deformation chamber has a convex ring in the middle part that gradually protrudes toward the center to promote the deformation of the rod material. An upper punch and a lower punch are distributed at the upper and lower ends of the deformation chamber to cooperate in pushing the rod material for reciprocating extrusion and upsetting.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. The aluminum chip reciprocating hot extrusion upsetting solid phase regeneration method described in the present invention can utilize aluminum chips, aluminum powder and reciprocating extrusion to reduce the size restrictions of recycled aluminum billets caused by high extrusion ratios and multi-pass hot extrusion processes, thereby producing larger products.

[0024] 2. The aluminum chip reciprocating hot extrusion and upsetting solid phase regeneration method described in the present invention is simple to operate, can achieve multiple hot extrusion deformations through one heating, has a short processing cycle, high production efficiency, and is easy to apply in industry;

[0025] 2. The aluminum scrap reciprocating hot extrusion solid-phase regeneration method described in the present invention has a closed cavity and can use the deformation heat generated by the reciprocating hot extrusion process to promote the bonding of mixed materials and pore closure, thereby improving the mechanical properties of the recycled aluminum billet, reducing the heat input during the preparation process, and reducing the impact of high-temperature oxidation;

[0026] 3. The deformed recycled aluminum billet obtained by the aluminum chip reciprocating hot extrusion and upsetting solid phase regeneration method described in the present invention has a hardness of 38.3~44.2HV, a yield strength of 72~92MPa, a tensile strength of 113~144MPa, and an elongation of 24.5~28.4%; the aged recycled aluminum billet has a hardness of 118.1~122HV and a tensile strength of 224~284MPa. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a process principle diagram of the reciprocating hot extrusion deformation;

[0028] Figure 2 This is a physical picture of the recycled aluminum billet obtained in Example 1;

[0029] Figure 3 This is a microstructure photograph of the recycled aluminum billet obtained in Example 1;

[0030] Figure 4 This is a microstructure photograph of the recycled aluminum billet obtained in Example 3. DETAILED DESCRIPTION

[0031] The present invention will be described in further detail below with reference to the accompanying drawings and embodiments.

[0032] Example 1

[0033] The 6061 aluminum alloy chips were cleaned and mechanically crushed by reciprocating hot extrusion and solid phase regeneration method to obtain aluminum chips with a length of less than 5mm. The aluminum chips were cold pressed under a pressing pressure of 300MPa to obtain The preform was loaded into a reciprocating hot extrusion die with an extrusion ratio of 4 and subjected to 4 reciprocating hot extrusion deformations at 520°C and an extrusion speed of 1 mm / s to obtain Recycled aluminum billets, such as Figure 2 shown.

[0034] In this embodiment, there are no obvious holes in the microstructure of the recycled aluminum billet. Figure 3 As shown, the hardness is 44.2HV, the yield strength is 92MPa, the tensile strength is 144MPa, and the elongation is 24.5%.

[0035] Example 2

[0036] The 6061 aluminum alloy chips were cleaned and mechanically crushed by reciprocating hot extrusion and solid phase regeneration method to obtain aluminum chips with a length of less than 5mm. The aluminum chips were cold pressed under a pressing pressure of 300MPa to obtain The preform was loaded into a reciprocating hot extrusion die with an extrusion ratio of 4 and subjected to 4 reciprocating hot extrusion deformations at 520°C and an extrusion speed of 1 mm / s to obtain The aluminum billet is then subjected to a solution treatment at 525°C for 1 hour and an aging treatment at 175°C for 8 hours to obtain an aged recycled aluminum billet.

[0037] In this embodiment, the hardness of the aged recycled aluminum billet is 122HV and the tensile strength is 284MPa.

[0038] Example 3

[0039] The 6061 aluminum alloy chips were cleaned and mechanically crushed by reciprocating hot extrusion and solid phase regeneration method to obtain aluminum chips with a length of less than 5mm. The aluminum chips were cold pressed under a pressing pressure of 300MPa to obtain The preform was loaded into a reciprocating hot extrusion die with an extrusion ratio of 4 and subjected to two reciprocating hot extrusion deformations at 520°C and an extrusion speed of 1 mm / s to obtain Recycled aluminum billets.

[0040] In this embodiment, there are only a few tiny pores in the microstructure of the recycled aluminum billet, such as Figure 4 As shown, the hardness is 40.7HV, the yield strength is 72MPa, the tensile strength is 135MPa, and the elongation is 28.4%.

[0041] Example 4

[0042] The 6061 aluminum alloy chips were cleaned and mechanically crushed by reciprocating hot extrusion and solid phase regeneration method to obtain aluminum chips with a length of less than 5mm. The aluminum chips were cold pressed under a pressing pressure of 300MPa to obtain The preform was loaded into a reciprocating hot extrusion die with an extrusion ratio of 4 and subjected to two reciprocating hot extrusion deformations at 520°C and an extrusion speed of 1 mm / s to obtain The aluminum billet is then subjected to a solution treatment at 525°C for 1 hour and an aging treatment at 175°C for 8 hours to obtain an aged recycled aluminum billet.

[0043] In this embodiment, the hardness of the aged recycled aluminum billet is 118.1HV and the tensile strength is 224MPa.

[0044] Example 5

[0045] The 6061 aluminum alloy chips were cleaned and mechanically crushed by reciprocating hot extrusion solid phase regeneration method to obtain aluminum chips with a length of less than 5mm. The aluminum chips were cold pressed under a pressing pressure of 150MPa to obtain The preform was loaded into a reciprocating hot extrusion die with an extrusion ratio of 4 and subjected to two reciprocating hot extrusion deformations at 400°C and an extrusion speed of 0.5 mm / s to obtain Recycled aluminum billets.

[0046] In this embodiment, there are many pores in the microstructure of the recycled aluminum billet, the hardness is 38.3HV, and the tensile strength is 113MPa.

Claims

1. A reciprocating hot extrusion and upsetting solid phase regeneration method for aluminum chips, characterized in that: The preparation method is carried out in the following steps: (1) Recovering aluminum chips and cleaning them for later use; (2) Mechanically crushing the cleaned aluminum chips to obtain aluminum chips with a length of less than 5 mm; (3) Pour an appropriate amount of aluminum scrap into a steel mold and press-dry at room temperature to obtain a low-density preform; (4) The preform is heated to 400-550°C and deformed by reciprocating hot extrusion and upsetting to obtain a deformed recycled aluminum billet.

2. The aluminum chip reciprocating hot extrusion upsetting solid phase regeneration method according to claim 1, characterized in that The recycled aluminum chips in step (1) are pure aluminum chips or aluminum alloy aluminum chips.

3. The aluminum chip reciprocating hot extrusion solid phase regeneration method according to claim 1, characterized in that The diameter of the mold for pressing the blank in step (3) is 3 to 20 cm, the pressing pressure is 150 to 300 MPa, and the holding time is 10 to 60 s.

4. The aluminum chip reciprocating hot extrusion solid phase regeneration method according to claim 1, characterized in that The reciprocating hot extrusion upsetting deformation in step (4) is a method of providing driving force and back pressure along the axial direction of the bar through the upper and lower punches, thereby performing reciprocating extrusion and upsetting composite deformation on the bar.

5. The aluminum chip reciprocating hot extrusion upsetting solid phase regeneration method according to claim 4, characterized in that The cross-section of the reciprocating hot extrusion upsetting deformation die in step (4) is circular, elliptical, rectangular, square or other polygonal shapes.

6. The aluminum chip reciprocating hot extrusion solid phase regeneration method according to claim 4, characterized in that The extrusion ratio of the reciprocating hot extrusion upsetting deformation die in step (4) is ≥2.

5.

7. The aluminum chip reciprocating hot extrusion solid phase regeneration method according to claim 1, characterized in that The extrusion speed of the reciprocating hot extrusion deformation in step (4) is 0.5 to 10 mm / s.

8. The aluminum chip reciprocating hot extrusion solid phase regeneration method according to claim 4, characterized in that The number of passes of the reciprocating hot extrusion deformation in step (4) is 1 to 4.

9. The aluminum chip reciprocating hot extrusion solid phase regeneration method according to claim 1, characterized in that The deformed recycled aluminum billet in step (4) is further subjected to solution aging heat treatment, with a solution temperature of 500-550°C, a solution time of 1-4h, an aging temperature of 160-200°C, and an aging time of 6-12h to obtain an aged recycled aluminum billet.

10. A deformation die in the solid phase regeneration method of aluminum chips by reciprocating hot extrusion upsetting according to any one of claims 1 to 9, characterized in that It includes a left mold block and a right mold block that are matched on the left and right to form a cylindrical deformation chamber that runs through from top to bottom. The deformation chamber has a convex ring in the middle that gradually protrudes toward the center to promote the deformation of the bar. Upper and lower punches are distributed at the upper and lower ends of the deformation chamber to cooperate in pushing the bar to reciprocate and extrude.

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