Aluminum mold and machining method thereof

Abstract

The invention discloses an aluminum mold and a machining method thereof. The mold comprises a mold base, a mold cavity and a mold core, and has the beneficial effects that a set of efficient cooling system consisting of a three-dimensional conformal cooling channel and a shunting throttling structure is integrated, and a replaceable hard alloy insert is arranged at an easy-to-wear part of the mold core. The working face of the insert is subjected to micro-texturing treatment and coated with the low-surface-energy coating, and the insert has the advantages of being excellent in abrasion resistance and adhesion resistance and convenient and fast to maintain. The invention further provides a precision machining method of the die, metal additive manufacturing, topological optimization, hot isostatic pressing densification, five-axis precision machining and special surface engineering technologies are combined, the cooling uniformity of the die can be remarkably improved, the service life of the die can be remarkably prolonged, the quality of a formed product can be remarkably improved, and the life cycle cost can be reduced.

Description

Technical Field

[0001] This invention relates to the field of mold processing technology, and in particular to an aluminum mold and its processing method. Background Technology

[0002] Aluminum molds are the core process equipment for producing aluminum profiles, and they operate under harsh conditions of high temperature (400-500℃) and high pressure (hundreds of megapascals).

[0003] Currently widely used traditional extrusion dies have two major defects in their core structural design, making it difficult to meet the demands of high-precision and high-efficiency production: First, the cooling system generally uses straight or two-dimensional intersecting channels machined by drilling. These channels cannot closely fit the surface contour of complex die cores and lack precise flow distribution and throttling control structures, resulting in uneven coolant flow distribution and an unbalanced die temperature field. This not only easily leads to thermal fatigue cracking of the die but also causes poor dimensional accuracy and inconsistent microstructure of extruded products. Second, the die forming surface, especially the wear-prone areas, does not adopt modular design and special surface strengthening treatment. Most are integral structures without individually replaceable wear-resistant parts. Their working surfaces also lack micro-textured structures and low surface energy coatings for protection, making these areas prone to severe wear and aluminum adhesion. This leads to early die failure, scratches on the product surface, and the need for complete scrapping or complex repair welding after local damage, resulting in high maintenance costs. Frequent downtime for die repair also significantly reduces production efficiency.

[0004] Therefore, an aluminum mold and its processing method are proposed to solve the above problems. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings mentioned above by providing an aluminum mold and its processing method.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: This invention provides an aluminum profile mold, including a mold base, a mold cavity, and a mold core, wherein the mold core and the mold cavity together define a forming channel for the aluminum profile, and further includes: Cooling system: Includes conformal cooling channels arranged in a three-dimensional curve along the periphery of the mold core, and at least one set of flow-diverting and throttling structures connected to the cooling manifold inside the mold base. The conformal cooling channels are integrally formed inside the mold core using metal additive manufacturing technology, and their paths are optimized through thermal flow field simulation to maximize conformity to the geometry of the mold core's forming surface, achieving precise temperature control. The flow-diverting and throttling structures can be used to manually or automatically adjust the coolant flow rate of each channel branch via actuators.

[0007] Replaceable carbide inserts: These are fixed to the wear-prone areas of the mold core by positioning bolts or snap-fit ​​structures. The working surface of the insert forms part of the forming channel, and this working surface is treated with surface microtexturing (e.g., micropits, grooves), and further coated with a low surface energy composite coating (e.g., TiAlN / CrAlN) by physical vapor deposition (PVD) or plasma spraying.

[0008] Optionally, the mold may further include a vibration excitation device disposed in the non-forming area of ​​the mold cavity for applying ultrasonic or low-frequency vibration to improve metal flowability.

[0009] Optionally, the mold may also include a temperature closed-loop control system, which uses a temperature sensor embedded in the mold core and an external control unit to adjust the flow splitting and throttling structure in real time to achieve dynamic temperature balance.

[0010] This invention provides a method for processing the above-mentioned aluminum profile mold, comprising the following steps: S1. Digital Design and Simulation: Based on the product's 3D model, a digital prototype of the mold is established. Topology optimization and computational fluid dynamics (CFD) simulation are performed on the mold core to determine the optimal 3D path of the conformal cooling channel.

[0011] S2. Additive Manufacturing: Using selective laser melting (SLM) or directional energy deposition (DED) technology, mold core blanks with built-in conformal cooling channels are manufactured using mold steel powder (such as 18Ni300, H13).

[0012] S3. Densification and heat treatment: The blank is subjected to hot isostatic pressing (HIP) to eliminate internal defects, followed by aging and solution treatment to optimize its mechanical properties.

[0013] S4. Precision machining: The mold core blank is precision machined using a five-axis CNC milling machine and electrical discharge machining (EDM) / wire cutting (WEDM) processes to form the final forming surface, mounting mating surface and insert mounting groove.

[0014] S5. Surface Engineering: Microtexturize the working surface of the cemented carbide insert (using μ-EDM or ultrasonic vibration processing), and then deposit a low surface energy coating.

[0015] S6. Assembly and Integration: Assemble the processed inserts into the mold core and connect the cooling pipes, sensors and vibration devices.

[0016] S7. Final processing and debugging: Perform surface hardening treatment on the mold (such as nitriding), then test extrusion on the machine, and adjust the cooling and vibration parameters.

[0017] The beneficial effects of this invention are reflected in: 1. This invention achieves conformal cooling of the mold core through a three-dimensional conformal cooling channel. Combined with adjustable flow diversion and throttling, it can improve the uniformity of the working temperature field of the mold by more than 50%, significantly suppress thermal fatigue, and improve the consistency of product dimensions.

[0018] 2. This invention improves the wear resistance and anti-adhesion of the mold by more than 3 times compared with traditional molds through the synergistic effect of hard alloy inserts, micro-texture oil storage effect and low surface energy coating. Attached Figure Description

[0019] Figure 1 The flowchart of the aluminum mold processing method of the present invention. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Example 1 The aluminum profile mold of the present invention has a basic structure including a mold base, a mold cavity mounted on the mold base, and a mold core assembled in the mold cavity. The lower surface of the mold core and the inner cavity of the mold cavity together form a channel for forming the aluminum profile.

[0022] One of the core improvements of this invention lies in the cooling system. The conformal cooling channel is integrally formed during the printing of the mold core using selective laser melting technology. It is not a straight line, but rather, based on computational fluid dynamics simulation results, it tightly wraps around the outer periphery of the working part of the mold core in a spatial spiral curve, with a circular cross-section several millimeters in diameter. This channel is connected to a circulating cooling manifold machined inside the mold base through multiple flow-diverting orifices. Each orifice is equipped with a precisely adjustable needle valve, allowing for flow control via manual operation or connection to a servo motor.

[0023] Another core improvement of this invention lies in the modular design of vulnerable components. A mounting groove is precisely machined on the mold core corresponding to the wear-prone area of ​​the profile rib forming. The cemented carbide insert is secured within this groove by two high-strength positioning bolts. To ensure positioning accuracy and sealing, a self-sealing groove can be designed on the side of the insert and an O-ring can be placed there. A tiny gap is designed between the back of the insert and the bottom of the groove in the mold core; this gap forms a liquid cooling layer, which can be connected to an external micro-circulation cooling system through side inlets and outlets for secondary enhanced cooling of the insert. The working surface of the cemented carbide insert is first processed with ultrasonic vibration-assisted machining or electrical discharge micro-engraving technology to form micron-level regular textures, and then fed into a physical vapor deposition (PVD) device to deposit a low surface energy composite coating, such as a multilayer composite coating of titanium aluminum nitride / chromium aluminum nitride.

[0024] Furthermore, a vibration excitation device, such as a piezoelectric ceramic ultrasonic transducer, is embedded in the non-working area of ​​the mold cavity sidewall. Simultaneously, a temperature sensor is embedded at the location of highest heat load inside the mold core. The sensor's wires are connected to a control unit integrated on the mold base. Based on a preset temperature curve and real-time temperature feedback data, the control unit outputs signals through a control algorithm to drive actuators on the flow divider orifices, achieving automated and precise adjustment of the flow rate in each cooling circuit, forming a closed-loop temperature control.

[0025] The processing method mainly includes the following steps: S1, Digital Design and Simulation: Accurate digital models of the mold core and cavity are created using 3D computer-aided design software. Subsequently, computer-aided engineering software is used to perform topology optimization on the mold core, removing redundant material while ensuring structural strength. Next, coupled thermal flow field simulation is performed to analyze the temperature distribution of the mold during extrusion, thereby optimizing the 3D spatial path of the conformal cooling channels to make them more densely distributed in high-temperature regions.

[0026] S2, Additive Manufacturing: The optimized model is imported into a metal 3D printer. Mold steel powder is used, and appropriate process parameters such as laser power, scanning speed, and powder layer thickness are set. To reduce residual stress, a rotating checkerboard scanning strategy can be employed. After printing, a mold core blank with complex 3D conformal cooling channels is obtained.

[0027] S3, Densification and Heat Treatment: The mold core blank is placed in a hot isostatic pressing furnace and treated for several hours under a high temperature and high pressure in an inert atmosphere to effectively close internal pores and microcracks. Aging and solution treatment is then performed to give the material a high combination of strength and toughness.

[0028] S4, Precision Machining: On a multi-axis CNC machining center, carbide cutting tools are used to precision mill the densified mold core blank to machine the mounting surfaces and precision grooves for mounting carbide inserts. For micro-structures, slow wire EDM or EDM can be used. During machining, an online measurement system can be used for real-time measurement and toolpath error compensation.

[0029] S5, Surface Engineering: The working surface of the cemented carbide insert is microtextured, for example, by using electrical discharge machining or ultrasonic vibration processing technology to form a regular surface texture with a size at the micrometer level. Subsequently, the microtextured insert is sent to a coating equipment, and after cleaning, an adhesive layer and a working layer are deposited sequentially to form a low surface energy hardening coating.

[0030] S6, Assembly and Integration: Precisely place the coated carbide insert into the mounting slot of the mold core, and tighten the positioning bolts to the specified torque using a torque wrench. Connect the micro-pipeline of the liquid cooling layer, and reliably connect the cables of the temperature sensor, vibration excitation device, and control unit.

[0031] S7, Final Processing and Debugging: The assembled mold undergoes surface hardening treatment, such as ion nitriding. Finally, the mold is installed on the extruder for trial extrusion. Temperature data at each measuring point is observed through the control unit, and the flow divider and throttling structures are fine-tuned to ensure uniform temperature across all areas of the mold core. The vibration excitation device can be activated to observe the surface of the extruded profile. After adjustment, the mold operates stably, the extruded profile surface is smooth and free of scratches, and the dimensional accuracy fully meets design requirements.

[0032] After continuous production testing, the key performance data comparison is shown in the table below:

[0033] The significant improvement in product surface quality and yield directly stems from the optimization of metal flow and precise temperature field control achieved through vibration-assisted molding. The substantial reduction in maintenance frequency and the ability to quickly replace inserts demonstrate the immense value of modular design, effectively improving production efficiency and reducing overall costs.

[0034] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0035] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0036] Additionally, "multiple" refers to two or more.

[0037] The above description 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 within the protection scope of the present invention.

Claims

1. An aluminum profile mold, comprising an aluminum profile mold base, a mold cavity, and a mold core, wherein the mold core and the mold cavity together define a forming channel for the aluminum profile, characterized in that, Also includes: The cooling system includes a conformal cooling channel arranged in a three-dimensional curve along the periphery of the mold core, and at least one set of diversion and throttling structures connected to the cooling manifold inside the mold base; A replaceable carbide insert is fixed to the wear-prone area of ​​the mold core by a positioning structure. The working surface of the carbide insert forms part of the forming channel, and the working surface is micro-textured and coated with a low surface energy coating.

2. The aluminum mold according to claim 1, characterized in that: The conformal cooling channel is equipped with alternating flow balancing guide vanes.

3. The aluminum mold according to claim 1, characterized in that: The flow splitting and throttling structure includes a throttling valve with an independently adjustable opening, used to precisely control the flow rate of coolant flowing into each section of the conformal cooling channel.

4. The aluminum mold according to claim 1, characterized in that: A sealed liquid cooling layer is formed between the cemented carbide insert and the mold core.

5. The aluminum mold according to claim 1, characterized in that: The mold also includes a vibration excitation device disposed in the non-forming area of ​​the mold cavity, for applying ultrasonic or low-frequency vibration during the extrusion process.

6. The aluminum mold according to claim 1, characterized in that: The mold also includes a temperature closed-loop control system, which includes a temperature sensor embedded in the mold core and a control unit that adjusts the flow splitting and throttling structure according to the sensor signal.

7. A method for processing an aluminum mold, characterized in that: Includes the following steps: S1. Based on the cross-section of the aluminum profile, establish a three-dimensional model of the mold core and mold cavity, and perform topology optimization and cooling channel layout design; S2. A mold core blank containing the conformal cooling channel is formed using metal additive manufacturing technology; S3. Perform hot isostatic pressing and aging heat treatment on the mold core blank; S4. The heat-treated mold core blank is precision machined to form the final mounting mating surface and the mounting groove for fixing the hard alloy insert; S5. The working surface of the cemented carbide insert is microtextured and a low surface energy coating is deposited; S6. Assemble the processed carbide inserts into the mold core and complete the integration of the cooling system and control unit; S7. Perform mold assembly, debugging, and parameter calibration.

8. The processing method according to claim 7, characterized in that: The additive manufacturing technology used in step S2 is selective laser melting or directional energy deposition.

9. The processing method according to claim 7, characterized in that: The precision machining in step S4 includes five-axis milling and electrical discharge machining, and online measurement is used for error compensation.

10. The processing method according to claim 7, characterized in that: The microtexturing process in step S5 is performed by electrical discharge micro-engraving or ultrasonic vibration processing, and the resulting microtexture size is between 0.5μm and 50μm.

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