Aluminum profile mold pressure balancing and shaping enhancing process

Abstract

The invention relates to the technical field of aluminum profile forming, in particular to an aluminum profile mold pressure balancing and shaping enhancing process which comprises the following steps: S1, preheating an aluminum bar, preheating the aluminum bar in three stages and increasing the temperature in sequence, S2, extruding and forming, putting the aluminum bar into an extruding machine and extruding the aluminum bar into an aluminum profile mold, the extrusion process of an initial stage and a stable stage is carried out, and compared with the initial stage, the propelling speed and the heating temperature of an aluminum bar are increased in the stable stage, and S3, cooling is carried out, specifically, a formed extrudate is subjected to a three-stage cooling process which comprises front-section air cooling, middle-section pulse type water mist cooling and rear-section natural cooling combined with auxiliary air cooling, the aluminum profile die comprises the upper die and the lower die, the upper die comprises the feeding port, the feeding port is sunk by 7 mm and is chamfered, the internal pressure of the aluminum profile die can be more balanced, and the shaping effect of a product is finally improved.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum profile forming, in particular to the process of pressure balance and shape setting enhancement for aluminum profile molds. Background Art

[0002] As an important industrial material, the production process of aluminum profiles mainly includes processes such as melting and casting, extrusion forming, heat treatment, and surface treatment. Among them, extrusion forming is the core process. By applying high pressure to a heated aluminum rod through a mold, its plastic deformation is made into the required cross-sectional shape, which is widely used in fields such as construction, transportation, and electronics. The efficiency and product quality of this process highly depend on parameters such as mold design, extrusion speed, and temperature control. Among them, the rationality of the mold structure is particularly crucial, directly affecting the dimensional accuracy, surface quality, and production energy consumption of the profiles.

[0003] An aluminum profile mold usually consists of an upper mold (manifold die) and a lower mold (working belt die). The upper mold evenly distributes aluminum metal to the mold cavity through manifold holes, and the lower mold shapes the final cross-sectional shape through the working belt. In traditional mold design, due to problems such as the relatively thick upper mold, uneven internal structure of the aluminum rod, large pressure fluctuations during extrusion, and poor cooling effect of the aluminum profile after exiting the mold resulting in reverse heat conduction, heat is easily locally accumulated and difficult to dissipate inside the mold, thus leading to temperature accumulation. The local temperature accumulation in the aluminum profile mold not only causes internal pressure imbalance but also easily leads to thermal deformation and even cracking of the mold, ultimately affecting the final shape setting effect of the profile. Summary of the Invention

[0004] In order to solve the problems existing in the above-mentioned prior art, the present application provides a process for pressure balance and shape setting enhancement of aluminum profile molds.

[0005] The process for pressure balance and shape setting enhancement of aluminum profile molds provided by the present invention adopts the following technical solutions:

[0006] The process for pressure balance and shape setting enhancement of aluminum profile molds includes the following steps:

[0007] S1 Aluminum rod preheating, the aluminum rod undergoes a preheating process in three stages and the temperatures of the three stages increase sequentially;

[0008] S2 Extrusion forming, the pretreated aluminum rod is placed into an extruder and extruded into an aluminum profile mold under the action of the extruder. The aluminum rod undergoes an extrusion process in two stages, including an initial stage and a stable stage. The stable stage increases the propulsion speed of the aluminum rod and the heating temperature of the aluminum rod compared to the initial stage;

[0009] S3 Cooling, the formed extrudate undergoes a cooling process in three stages, including front-stage air cooling, middle-stage pulsed water mist cooling, and rear-stage natural cooling combined with auxiliary air cooling.

[0010] Preferably, in S2, the aluminum profile die includes an upper die and a lower die. The upper die includes a feed inlet. At the feed inlet, the upper die is sunk by 7 mm and rounded to form a sunk structure.

[0011] Preferably, the sunk structure of the upper die is a three - stage stepped sunk structure. The depth of the first - stage sunk is 3 mm, the depth of the second - stage sunk is 2 mm, and the depth of the third - stage sunk is 2 mm. A 15° gradual rounding is provided between each stage.

[0012] Preferably, the aluminum rod is 6063 aluminum alloy with a diameter of Φ150 - 200 mm. The extruded product is a harmonica tube with 9 parallel holes, a hole diameter of 23*23 mm, a wall thickness of 1.8 mm, and a continuous extrusion length of 6 m.

[0013] Preferably, in S1, the pre - heating of the aluminum rod in three stages includes:

[0014] The first stage: 380°C for 20 min, insulation for 20 ± 2 min;

[0015] The second stage: 460°C for 15 min, insulation for 15 ± 1 min and including a 5 - min constant - temperature platform;

[0016] The third stage: 510°C for 5 min, insulation for 5 ± 0.5 min.

[0017] Preferably, in S2, the initial pushing speed of the aluminum rod is 0.6 - 1 mm / s. When the extrusion pressure reaches 80% - 90% of the peak pressure, it enters the stable stage. In the stable stage, the temperature of the aluminum rod is raised to 515 - 525°C, and the extrusion speed is stepped up to 1 - 1.5 mm / s.

[0018] Preferably, in S3, the front - section air cooling covers 0 - 2 m of the extrudate, with a cooling rate of 25 - 35°C / s for 18 - 22 s; the middle - section water - mist cooling covers 2 - 4 m of the extrudate, turns on for 3 ± 0.5 s and then turns off for 2 ± 0.5 s, with a cooling rate of 45 - 55°C / s; the rear - section cooling: covers the area after 4 m, and the wind speed of the auxiliary air cooling is ≤5 m / s.

[0019] Preferably, in S2, the pressure sensor of the extrusion pressure monitors the pressure value in real - time. When the pressure fluctuation amplitude exceeds ±5% of the set peak value, the temperature compensation mechanism is automatically triggered, and the heating rate is 2 - 3°C / s.

[0020] Preferably, in S2, when the remaining length of the aluminum rod is 20% - 30% of the total length, the extrusion speed is reduced to 60% - 70% of the initial speed.

[0021] Preferably, in S3, the particle size of the atomized water droplets for water mist cooling is 50 - 80 μm, and the angle between the air cooling air flow and the axis of the extrudate is 30 - 45°.

[0022] The beneficial effects of the present invention are as follows:

[0023] 1. In S1, through gradient temperature control pretreatment, the accumulated temperature caused by uneven internal flow of the material is solved. In S2, through dynamic pressure compensation, the accumulated temperature caused by external pressure fluctuations during the extrusion process is solved. In S3, through sequential partition cooling, the indirect accumulated temperature caused by residual heat after forming is solved. Finally, the three steps start from three dimensions of material uniformity, flow stability, and heat dissipation respectively, making the internal pressure of the aluminum profile die more balanced and ultimately improving the shaping effect of the product;

[0024] 2. The upper die of the aluminum profile die forms a sunken structure with a depth of 7 mm and rounded corners at the feeding port to address the problem of the relatively thick upper die, effectively reducing the breakthrough pressure during extrusion, thereby reducing the accumulated temperature and enhancing the stability of the die during extrusion Description of the Drawings

[0025] Figure 1 is a schematic top view of the upper die in the embodiment of the present application;

[0026] Figure 2 is a schematic bottom view of the upper die in the embodiment of the present application;

[0027] Figure 3 is a schematic plan view of the harmonica tube in the embodiment of the present application.

[0028] Description of the reference numerals: 1. Upper die; 2. Harmonica tube. Detailed Embodiments

[0029] The following will be combined with Figures 1-3 and embodiments to further illustrate the present invention.

[0030] This embodiment discloses a process for balancing pressure and enhancing shaping of an aluminum profile die. In this embodiment, taking the production of a harmonica tube 2 with 9 parallel holes, a hole diameter of 23 * 23 mm, a wall thickness of 1.8 mm, and a continuous extrusion length of 6 m as an example for illustration.

[0031] The process for balancing pressure and enhancing shaping of the aluminum profile die includes the following steps:

[0032] S1 Aluminum bar preheating:

[0033] After preheating, the aluminum rod can improve its plasticity, making it easier for subsequent extrusion and flow. In the present invention, the aluminum rod is 6063 aluminum alloy with a diameter of Φ150 - 200 mm. The aluminum rod undergoes three-stage preheating, including the first stage: 380 °C for 20 min, holding for 20 ± 2 min to eliminate casting stress; the second stage: 460 °C for 15 min, holding for 15 ± 1 min and including a 5-min constant-temperature platform for recrystallization softening; the third stage: 510 °C for 5 min, holding for 5 ± 0.5 min to generate a surface plastic layer. Compared with the single-stage preheating in the traditional technology, which results in a large temperature difference between the core and the surface of the aluminum rod and the core temperature not being fully melted, leading to non-uniform internal structure of the aluminum rod and obvious differences in the flow rates of the core and the surface during subsequent extrusion, exacerbating the pressure fluctuations during extrusion, the present invention can effectively reduce the temperature difference between the core and the surface to below 15 °C through three-stage preheating, making the internal structure of the aluminum rod more uniform.

[0034] S2 Extrusion forming:

[0035] Place the pre-treated aluminum rod into an extruder and extrude it into an aluminum profile die under the action of the extruder. The extrusion process includes an initial stage and a stable stage. Initial stage: Advance at a low speed of 0.6 - 1 mm / s to establish stable flow; Stable stage: When the extrusion pressure reaches 80% - 90% of the peak pressure, raise the temperature of the aluminum rod to 515 - 525 °C and stepwise increase the extrusion speed to 1 - 1.5 mm / s. The extrusion speed increase stage is to increase by 0.03 - 0.07 mm / s every 5 - 10 seconds, and the duration of the temperature increase stage does not exceed 15% of the total extrusion time of the aluminum rod. In traditional constant-speed extrusion, pressure fluctuations during extrusion can cause sudden changes in the metal flow rate, local flow rate differences trigger turbulent heat accumulation, and the continuous rise in the die temperature will cause high-temperature aluminum to adhere to the die surface, exacerbating the flow resistance and heat accumulation. In the present invention, by dynamically adjusting the speed and temperature, when the pressure peak is relatively high, the temperature is raised to compensate for the accumulated temperature in the die, making the fluidity of the aluminum material dynamically match the die temperature, improving the fluidity of the aluminum material, reducing the probability of sticking to the die, and ultimately reducing the accumulated temperature in the die, effectively addressing the problem of extrusion pressure fluctuations during the extrusion process.

[0036] S3 Cooling:

[0037] The cooling process of the formed extrudate is divided into three sections: the front section, the middle section, and the rear section. Among them, in the front section, air cooling is used: covering 0 - 2m of the extrudate, with a cooling rate of 25 - 35°C / s for 18 - 22 seconds; in the middle section, water mist cooling is used: covering 2 - 4m of the extrudate, with pulsed spraying, turning on for 3 ± 0.5 seconds / turning off for 2 ± 0.5 seconds, and a cooling rate of 45 - 55°C / s; in the rear section, cooling is carried out: covering the area after 4m, with natural cooling plus assisted air cooling with a wind speed ≤ 5m / s. Based on the above cooling process, the air cooling in the front section can quickly take away the heat on the surface of the extrudate, avoiding the reverse conduction of heat to the mold and causing mold temperature accumulation, while the pulsed water mist in the middle section can avoid the quenching stress caused by continuous cooling.

[0038] To sum up, in S1, through gradient temperature control pretreatment, the temperature accumulation caused by the uneven internal flow of the material is solved. In S2, through dynamic pressure compensation, the temperature accumulation caused by the external pressure fluctuation during the extrusion process is solved. In S3, through time-sequenced zone cooling, the indirect temperature accumulation caused by the residual heat after forming is solved. Finally, the three steps cut in from the three dimensions of material uniformity, flow stability, and heat dissipation respectively, making the internal pressure of the aluminum profile mold more balanced and ultimately improving the shaping effect of the product.

[0039] In S2, the pressure sensor of the extrusion pressure monitors the pressure value in real time. When the pressure fluctuation amplitude exceeds ±5% of the set peak value, the temperature compensation mechanism is automatically triggered, and the heating rate is 2 - 3°C / s to further improve the effect of dynamic pressure compensation.

[0040] In S2, when the remaining length of the aluminum rod is 20 - 30% of the total length, the extrusion speed is reduced to 60 - 70% of the initial speed to avoid the instability of metal flow caused by the reduction of the volume of the aluminum rod, prevent the generation of grain boundary cracks or uneven wall thickness of the pore channel due to excessive shear of the end material, and avoid the problem of increased scrap rate at the tail end commonly seen in traditional processes.

[0041] In S3, the particle size of the atomized water droplets for water mist cooling is 50 - 80μm, ensuring that the water droplets fully cover the surface of the pipe and quickly vaporize, while avoiding the quenching stress caused by too large water droplets or uneven cooling caused by too small water droplets. The air-cooling airflow forms an angle of 30 - 45° with the axial direction of the extrudate, which can not only enhance the sweeping effect of the airflow on the surface of the pipe but also avoid local overcooling deformation caused by vertical air supply.

[0042] Refer to Figures 1 to 3 , in S2, the aluminum profile mold includes an upper mold 1 and a lower mold. The upper mold 1 includes a feeding port. In particular, in the present invention, the total thickness of the upper mold 1 is 71.5mm, and a 7mm sink and rounded corners are made downward from the feeding port to form a sink structure to deal with the problem of the relatively thick upper mold 1, effectively reducing the breakthrough pressure during extrusion, thereby reducing temperature accumulation and enhancing the stability of the mold during extrusion.

[0043] In other embodiments, based on the 7mm sunken platform foundation at the feeding port of the upper die 1, it is further designed as a three-level stepped sunken platform structure. The depth of the first-level sunken platform is 3mm, the depth of the second-level sunken platform is 2mm, and the depth of the third-level sunken platform is 2mm. A 15° gradual fillet is set between each level. Through the hierarchical pressure relief design, the flow of aluminum material forms a pressure gradient transition. The multi-level stepped structure can change the metal flow direction from a straight-line impact to a broken-line buffer, reducing the temperature accumulation points caused by turbulence.

[0044] The above are all the preferred embodiments of the present invention, and the protection scope of this application is not limited thereby. Therefore, all equivalent changes made according to the structure, shape, and principle of this application should be covered within the protection scope of this application.

Claims

1. Aluminum profile mold pressure balance and shape enhancement process, characterized by: The following steps are involved: S1: preheating the aluminum rod, wherein the aluminum rod undergoes a three-stage preheating process and the temperatures of the three stages are increased sequentially; S2 extrusion molding, placing the pretreated aluminum rod into an extruder, and extruding it into an aluminum profile mold under the action of the extruder, the aluminum rod undergoes a two-stage extrusion process, including an initial stage and a stable stage, and the stable stage increases the pushing speed of the aluminum rod and the heating temperature of the aluminum rod compared to the initial stage; S3 cooling: the formed extrudate undergoes a three-stage cooling process, including front-stage air cooling, middle-stage pulsed water mist cooling, and rear-stage natural cooling combined with auxiliary air cooling.

2. The aluminum profile mold pressure equalization and shaping enhancement process according to claim 1, characterized in that: In S2, the aluminum profile mold comprises an upper mold (1) and a lower mold, the upper mold (1) comprises an inlet, and the upper mold (1) is sunken 7 mm at the inlet and rounded to form a sunken platform structure.

3. The aluminum profile mold pressure equalization and shaping enhancement process according to claim 2, characterized in that: The sinking platform structure of the upper mold (1) is a three-level stepped sinking platform structure, with a first-level sinking platform depth of 3 mm, a second-level sinking platform depth of 2 mm, and a third-level sinking platform depth of 2 mm, and a 15° gradient fillet is set between each level.

4. The aluminum profile mold pressure equalization and shaping enhancement process according to claim 1, characterized in that: The aluminum rod is a 6063 aluminum alloy with a diameter of Φ150-200 mm, and the extruded product is a harmonica tube (2) with 9 parallel holes, a hole diameter of 23*23 mm, a wall thickness of 1.8 mm, and a continuous extrusion length of 6 m.

5. The aluminum profile mold pressure equalization and shaping enhancement process according to claim 4, characterized in that: In S1, the three-stage preheating of the aluminum bar includes: The first stage: 380℃x20min, keep warm for 20±2min; The second stage: 460℃x15min, keep warm for 15±1min and include a 5min constant temperature platform; The third stage: 510℃x5min, keep warm for 5±0.5min.

6. The aluminum profile mold pressure equalization and shaping enhancement process according to claim 4, characterized in that: In S2, the pushing speed of the aluminum rod is 0.6-1 mm / s in the initial stage. When the extrusion pressure reaches 80%-90% of the peak pressure, it enters a stable stage. In the stable stage, the temperature of the aluminum rod is increased to 515-525°C, and the extrusion speed is increased stepwise to 1-1.5 mm / s.

7. The aluminum profile mold pressure equalization and shaping enhancement process according to claim 4, characterized in that: In S3, the front section air cooling covers 0-2m of the extrudate, with a cooling rate of 25-35℃ / s, and lasts for 18-22 seconds; the middle section water mist cooling covers 2-4m of the extrudate, is turned on for 3±0.5 seconds and then closed for 2±0.5 seconds, with a cooling rate of 45-55℃ / s; the rear section cooling: covers the area after 4m, and the wind speed of the auxiliary air cooling is ≤5m / s.

8. The aluminum profile mold pressure equalization and shaping enhancement process according to claim 5, characterized in that: In S2, the extrusion pressure sensor monitors the pressure value in real time. When the pressure fluctuation amplitude exceeds ±5% of the set peak value, the temperature compensation mechanism is automatically triggered, and the heating rate is 2-3℃ / s.

9. The aluminum profile mold pressure equalization and shaping enhancement process according to claim 6, characterized in that: In S2, when the remaining length of the aluminum rod is 20-30% of the total length, the extrusion speed is reduced to 60-70% of the initial speed.

10. The aluminum profile mold pressure equalization and shaping enhancement process according to claim 7, characterized in that: In S3, the atomized water droplet size of the water mist cooling is 50-80 μm, and the air cooling airflow forms an angle of 30-45° with the axial direction of the extrudate.

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