A method for designing a die for precision extrusion of an aluminum alloy

Abstract

This invention discloses a precision aluminum alloy extrusion die, belonging to the field of aluminum alloy extrusion technology. By setting a stress discontinuity surface within the extrusion die and combining it with a minimum forming pressure criterion to design the shape of the guide section of the forming section die, this invention can produce precision aluminum alloy profiles with dimensional accuracy tolerances below ±0.05mm. The principle of this invention is to utilize the stress discontinuity surface to eliminate the lateral stress of the pre-forming section die on the forming section die, and to minimize the lateral stress of the billet on the forming section die based on the minimum forming pressure criterion. This reduces the lateral stress experienced by the forming section die during extrusion to a lower level, resulting in smaller dimensional tolerances. The die design method proposed in this invention can control the dimensional accuracy of aluminum extruded materials to below ±0.05mm, achieving the level of precision machining of aluminum alloys. Furthermore, when the forming section die is damaged, production can resume simply by replacing it, reducing die costs by 30-50%.

Description

Technical Field

[0001] This invention relates to a die design method for precision extrusion of aluminum alloys, belonging to the field of aluminum alloy extrusion technology. Background Technology

[0002] Aluminum alloy extrusion accounts for approximately 30%-40% of global aluminum production, making it the second largest form of aluminum material after rolled sheets. Its applications range from building doors, windows, and curtain walls to the booming lightweight transportation industry, high-end equipment manufacturing, and the rapidly growing market for photovoltaic new energy frames and brackets, showing a significant trend of diversification.

[0003] However, it is worth noting that during the extrusion process, the extrusion die will undergo elastic deformation when subjected to extrusion pressure of hundreds of megapascals. Due to the uneven stress distribution within the extrusion die, the amount of elastic deformation is difficult to calculate, which makes it impossible to compensate for the precise dimensions at the sizing zone through calculation. As a result, the dimensional accuracy tolerance of aluminum extrusions is generally above ±0.08mm, which is difficult to meet the increasingly high precision requirements of users for aluminum alloy extrusions and restricts their further promotion and application. Summary of the Invention

[0004] The purpose of this invention is to provide a precision extrusion die for aluminum alloys. The die body includes a pre-forming section and a forming section arranged sequentially along the extrusion direction. The pre-forming section and the forming section are separated from each other by a parting surface to form a discontinuous stress transmission interface, thereby eliminating the influence of the lateral elastic deformation of the pre-forming section caused by extrusion on the forming section and blocking the transmission of lateral stress from the pre-forming section to the forming section.

[0005] Preferably, the preformed section and the formed section of the present invention are connected by a number of separable positioning elements to constrain their radial relative displacement.

[0006] Preferably, the extrusion ratio of the forming section mold in this invention is set as e, where e is the base of the natural logarithm.

[0007] Preferably, the die angle α in the forming section mold of the present invention is 60°.

[0008] The principle of this invention is to eliminate the transverse stress of the preforming die on the forming die by utilizing the stress discontinuity surface, and to reduce the transverse stress of the billet on the forming die to the minimum based on the minimum forming pressure criterion, so that the transverse stress of the forming die during the extrusion process is reduced to a lower level, thereby obtaining smaller dimensional tolerances.

[0009] The beneficial effects of this invention are: (1) The mold design method proposed in this invention can control the dimensional accuracy of aluminum extrusion material to below ±0.05mm, reaching the level of precision machining of aluminum alloy. There are two reasons for this: First, the pre-forming section undergoes elastic deformation after bearing high extrusion pressure during extrusion. The setting of the stress discontinuity surface in this invention will block the transmission of this deformation to the forming section, greatly reducing the lateral deformation of the forming section mold. Second, based on the minimum forming pressure criterion, the lateral stress of the billet on the forming section mold can be reduced to the minimum, further reducing the lateral deformation of the forming section mold. The two work together to obtain a smaller dimensional tolerance.

[0010] (2) In this invention, the extrusion mold is divided into two parts: a preforming section and a forming section. Any damaged part can be replaced separately, which can reduce the mold cost by 30-50%. Attached Figure Description

[0011] Figure 1 Schematic diagram of a die for precision extrusion of aluminum alloy; In the figure: 1-Pre-forming section; 2-Forming section; 3-Positioning pin; 4-Discontinuous stress transfer interface.

[0012] Figure 2 This is a cross-sectional view of a microchannel parallel flow tube; Figure 3 A cross-sectional view of a large skin profile used in railcars; Figure 4 This is a cross-sectional view of the Ω-channel aluminum heat pipe shell profile. Detailed Implementation

[0013] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, but the scope of protection of the present invention is not limited to the content described.

[0014] This invention provides a precision extrusion die for aluminum alloys, such as... Figure 1 As shown, the mold body includes a preforming section 1 and a forming section 2 arranged sequentially along the extrusion direction. The preforming section 1 and the forming section 2 are separated from each other by a parting surface to form a discontinuous stress transmission interface 4, thereby eliminating the influence of the transverse elastic deformation of the preforming section 1 caused by extrusion on the forming section 2 and blocking the transverse stress of the preforming section 1 from being transmitted to the forming section 2.

[0015] The pre-forming section and the forming section of this invention are connected by several separable positioning elements 3 to constrain their radial relative displacement. In this embodiment, the positioning element 3 is preferably a positioning pin. The extrusion ratio of the forming section mold described in this invention is set as e, where e is the base of the natural logarithm.

[0016] The die angle α in the forming section mold of the present invention is 60°.

[0017] Example 1 Using the design method of the aluminum alloy precision extrusion die in this invention, a 16.05×1.83 (16-hole) microchannel parallel flow tube was prepared (see product cross-sectional view). Figure 2 When ), its dimensional accuracy can be controlled within ±0.04mm.

[0018] Example 2 Using the design method of the aluminum alloy precision extrusion die in this invention, large skin profiles for rail trains are prepared (see product cross-sectional view). Figure 3 When ), its dimensional accuracy can be controlled within ±0.04mm.

[0019] Example 3 Using the design method of the aluminum alloy precision extrusion die in this invention, Ω-channel aluminum heat pipe shell profiles are prepared (see product cross-sectional view). Figure 4 When ), its dimensional accuracy can be controlled within ±0.05mm.

[0020] Comparative Example 1 The specific parameters in this embodiment are the same as those in Embodiment 1, except that no stress discontinuity surface is set.

[0021] The dimensional accuracy of the obtained aluminum extrusions is above ±0.09mm.

[0022] The comparison shows that, in the absence of stress discontinuities, the elastic deformation generated by the extrusion die under an extrusion force of hundreds of megapascals will increase the size of the sizing zone, resulting in a larger dimensional accuracy tolerance of the extruded material.

[0023] Comparative Example 2 The specific parameters in this embodiment are the same as those in Embodiment 1, except that the extrusion ratio of the forming section mold is 10.

[0024] The dimensional accuracy of the obtained aluminum extrusions is above ±0.08mm.

[0025] The comparison shows that when the extrusion ratio of the forming die is large, the extrusion pressure will increase, which in turn increases the size of the sizing zone, resulting in a larger dimensional accuracy tolerance of the extruded material.

[0026] Comparative Example 3 The specific parameters in this embodiment are the same as those in Embodiment 2, except that the forming section mold angle α is 30°.

[0027] The dimensional accuracy of the obtained aluminum extrusions is above ±0.08mm.

[0028] The comparison shows that a lower die angle α in the forming section increases the extrusion pressure, which increases the size of the sizing zone, resulting in a larger dimensional tolerance of the extruded material.

[0029] Comparative Example 4 The specific parameters in this embodiment are the same as those in Embodiment 2, except that the forming section mold angle α is 80°.

[0030] The dimensional accuracy of the obtained aluminum extrusions is above ±0.08mm.

[0031] The comparison shows that a higher die angle α in the forming section increases the extrusion pressure, which increases the size of the sizing zone, resulting in a larger dimensional tolerance of the extruded material.

[0032] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A precision extrusion die for aluminum alloys, characterized in that, The mold body includes a preforming section and a forming section arranged sequentially along the extrusion direction. The preforming section and the forming section are separated from each other by a parting surface to form a discontinuous stress transmission interface, thereby eliminating the influence of the lateral elastic deformation of the preforming section caused by extrusion on the forming section and blocking the transmission of the lateral stress of the preforming section to the forming section.

2. The precision extrusion die for aluminum alloys according to claim 1, characterized in that: The preformed section and the formed section are connected by several separable positioning elements to constrain their radial relative displacement.

3. The precision extrusion die for aluminum alloys according to claim 1, characterized in that: The extrusion ratio of the forming section mold is set as e, where e is the base of the natural logarithm.

4. The precision extrusion die for aluminum alloys according to claim 1, characterized in that: The die angle α in the forming section mold is 60°.

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