Method for controlling rod direction stress and shrinkage stress of high-strength aluminum alloy rod piece

Abstract

The invention discloses a control method for rod direction stress and shrinkage stress of a high-strength aluminum alloy rod piece, which comprises the following steps: S1, model processing; the method comprises the steps that (1) a continuous surrounding plate is arranged along the outer wall of a part, the surrounding plate and the part are connected through an inclined pull rod, and no gap exists among the surrounding plate, the part and the inclined pull rod, (2) a supporting plate and supporting feet are added to the middle position below the sudden change platform structure, the supporting plate is divided into two parts to obliquely fall on the side wall to form the supporting feet, and no gap exists among the supporting plate, the supporting feet and the part, S2, selective laser melting forming, S3, annealing and S4, linear cutting are conducted. S5, support removal; and S6, surface treatment. The method is suitable for high-quality additive manufacturing production of various high-strength aluminum alloy rod pieces with complex structures, auxiliary structures such as the surrounding plates, the pull rods, the supporting plates and the supporting feet are simple in design, the removal cost is low, and the problems that the forming process of the additive manufacturing high-strength aluminum alloy rod pieces is unstable and prone to failure, and sudden change positions of part structures are prone to cracking are solved at one stroke; and the high-strength aluminum alloy rod piece with low cost and high quality can be rapidly produced.

Description

Technical Field

[0001] This invention relates to a method for controlling the axial stress and shrinkage stress of high-strength aluminum alloy rods, and particularly to the field of laser selective melting forming 3D printing technology. Background Technology

[0002] In the field of aerospace rocket engines, significant progress has been made in utilizing the advantages of metal additive manufacturing technology, such as rapid R&D testing and verification, increased design flexibility in forming complex structures, improved process performance through integrated manufacturing, and rapid small-batch manufacturing.

[0003] The urgent need for low-cost, high-strength, and lightweight components for aerospace rocket engines places extremely high demands on additive manufacturing materials.

[0004] Compared to titanium alloys and high-temperature alloys, there are fewer mature aluminum alloy grades used in additive manufacturing, especially high-strength aluminum alloys. Recently, domestic companies have launched several high-strength aluminum alloys for additive manufacturing. The AlMgScZr high-strength aluminum alloy has nearly twice the strength of the ordinary AlSi10Mg aluminum alloy, with a tensile strength exceeding 550 MPa. However, high-strength aluminum alloys also present many challenges in application. Increasing the alloy element content and material strength significantly increases the difficulty of the forming process. High-strength aluminum alloys have high strength but low plasticity. Due to the use of high-efficiency forming parameters, the ductility and toughness of the auxiliary forming support are further reduced. During printing, the forming stress of the part itself can easily break the support, causing the forming process to be interrupted. Furthermore, for hollow, weight-reducing load-bearing members, when forming along their length, the area available for adding support at the bottom is extremely small. The limited support is insufficient to resist the stress in the forming direction, leading to cracking between the support and the substrate, part tilting, misalignment of non-solid mesh support lines, and warping at high points, interrupting printing. Simultaneously, the large shrinkage stress of high-strength aluminum alloys can cause cracking of the side walls when encountering abrupt plateaus in the member. Summary of the Invention

[0005] This invention provides a method for controlling the axial stress and shrinkage stress of high-strength aluminum alloy rods to overcome the defect in the prior art where the weak sidewalls of the platform structure crack due to the inability of the limited support to resist the stress in the forming direction during the forming process of high-strength aluminum alloy.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: This invention discloses a method for controlling the axial stress and shrinkage stress of high-strength aluminum alloy rods, comprising the following steps: S1. Model Processing: A continuous surrounding plate is provided along the outer wall of the part, and the surrounding plate is connected to the part by an oblique tie rod. There is no gap between the surrounding plate, the part and the oblique tie rod. A support plate and legs are added to the middle position below the mutation platform structure. Then the support plate is split in two and tilted to fall on the side wall to form legs. There are no gaps between the support plate, legs and parts. S2. Laser selective melting forming: The forming process parameters of the surrounding plate, tie rod, support plate and support leg are different from the forming process parameters of the part. The forming efficiency is high and it is also easier to remove. S3, Annealing: The parts and the substrate are annealed together to reduce the overall stress of the parts and slow down the deformation during subsequent wire cutting. S4. Wire EDM: After heat treatment, wire EDM is used to separate the parts from the substrate; S5. Support Removal: Manually remove the supports of the parts, and remove the enclosure, tie rod, support plate and support leg structure by manual or mechanical processing. S6. Surface treatment: After the parts are removed from the support, they are surface treated according to requirements to obtain the final product.

[0007] Furthermore, the distance between the enclosure and the part is 30~50mm, and the thickness of the enclosure is ≥2.5mm.

[0008] Furthermore, the diameter of the diagonal tie rod is ≥1mm, and the diagonal tie rod forms an angle of ≤50° with the part.

[0009] Furthermore, the oblique tie rod has a spacing of ≥5mm along the rod direction of the part and a spacing of ≥5mm along the circumferential direction of the part.

[0010] Furthermore, the thickness of the support plate is ≥ 0.3 times the thickness of the side wall and not less than 1 mm, and the height of the support plate is ≥ 1 mm.

[0011] Furthermore, the support leg forms an angle of ≤50° with the part, and the thickness of the support leg is ≥0.3 times the thickness of the support plate, and not less than 0.5mm.

[0012] The beneficial effects achieved by this invention are: it is applicable to the high-quality additive manufacturing of various high-strength aluminum alloy rods with complex structures; the auxiliary structures such as the surrounding plate, tie rod, support plate, and support leg are simple in design and have low removal costs; it solves the problems of unstable and easy failure in the forming process of additive manufacturing of high-strength aluminum alloy rods and easy cracking at the abrupt changes in the part structure; and enables the additive manufacturing process to achieve rapid production of low-cost, high-quality high-strength aluminum alloy rods. Detailed Implementation

[0013] The following description, in conjunction with preferred embodiments of the present invention, should be understood as follows. These preferred embodiments are for illustration and explanation only and are not intended to limit the scope of the invention.

[0014] Example 1 A method for controlling the axial stress and shrinkage stress of high-strength aluminum alloy rods includes the following steps: S1. Model Processing: A continuous surrounding plate is designed along the outer wall of the part. The distance between the surrounding plate and the part is 30~50mm. The thickness of the surrounding plate is ≥2.5mm. The surrounding plate and the part are connected by diagonal tie rods with a diameter ≥1mm. The angle between the tie rod and the part's rod direction is ≤50°. The gap between the tie rods along the part's rod direction is ≥5mm. The gap between the tie rods along the part's circumference is ≥5mm. The gap between the surrounding plate, the part and the tie rod is 0. A support plate and a support leg are added at the middle position below the mutation platform structure. The thickness of the support plate is ≥ 0.3 times the thickness of the side wall and not less than 1 mm. The height of the support plate is ≥ 1 mm. Then the support plate is split into two and tilted to fall on the side wall to form a support leg. The angle between the support leg and the part rod direction is ≤ 50°. The thickness of the support leg is ≥ 0.3 times the thickness of the support plate and not less than 0.5 mm. The gap between the support plate / support leg and the part is 0. S2. Laser selective melting forming: The forming process parameters of the surrounding plate, tie rod, support plate and support leg are different from the forming process parameters of the part. The forming efficiency is high and it is also easier to remove. S3, Annealing: The parts and the substrate are annealed together to reduce the overall stress of the parts and slow down the deformation during subsequent wire cutting. S4. Wire EDM: After heat treatment, wire EDM is used to separate the parts from the substrate; S5. Support Removal: Manually remove the supports of the parts, and remove the enclosure, tie rod, support plate and support leg structure by manual or mechanical processing. S6. Surface treatment: After the parts are removed from the support, they are surface treated according to requirements to obtain the final product.

[0015] It should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. 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. The terminology used in the description of this application is only for describing specific embodiments and is not intended to limit the exemplary embodiments according to this application. Technologies, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such technologies, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0016] It should be noted that the terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those described herein, and the objects distinguished by "first," "second," etc., are generally of the same class, not limited in number; for example, the first object can be one or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0017] It should be noted that in the description of this application, the directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" are used only for the convenience of describing this application and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the scope of protection of this application. The directional terms "inner" and "outer" refer to the inner and outer contours of each component itself.

Claims

1. A method for controlling the axial stress and shrinkage stress of high-strength aluminum alloy rods, characterized in that, Includes the following steps: S1. Model Processing: A continuous surrounding plate is provided along the outer wall of the part, and the surrounding plate is connected to the part by an oblique tie rod. There is no gap between the surrounding plate, the part and the oblique tie rod. A support plate and legs are added to the middle position below the mutation platform structure. Then the support plate is split in two and tilted to fall on the side wall to form legs. There are no gaps between the support plate, legs and parts. S2. Laser selective melting forming: The forming process parameters of the surrounding plate, tie rod, support plate and support leg are different from the forming process parameters of the part. The forming efficiency is high and it is also easier to remove. S3, Annealing: The parts and the substrate are annealed together to reduce the overall stress of the parts and slow down the deformation during subsequent wire cutting. S4. Wire EDM: After heat treatment, wire EDM is used to separate the parts from the substrate; S5. Support Removal: Manually remove the supports of the parts, and remove the enclosure, tie rod, support plate and support leg shape control structure by manual or mechanical processing. S6. Surface treatment: After the parts are removed from the support, they are surface treated according to requirements to obtain the final product.

2. The method for controlling the axial stress and shrinkage stress of high-strength aluminum alloy rods according to claim 1, characterized in that, The distance between the enclosure and the part is 30~50mm, and the thickness of the enclosure is ≥2.5mm.

3. The method for controlling the axial stress and shrinkage stress of high-strength aluminum alloy rods according to claim 1, characterized in that, The diameter of the diagonal tie rod is ≥1mm, and the diagonal tie rod forms an angle of ≤50° with the part.

4. The method for controlling the axial stress and shrinkage stress of high-strength aluminum alloy rods according to claim 1, characterized in that, The oblique tie rods have a spacing of ≥5mm along the rod direction of the part and a spacing of ≥5mm along the circumferential direction of the part.

5. The method for controlling the axial stress and shrinkage stress of high-strength aluminum alloy rods according to claim 1, characterized in that, The thickness of the support plate is ≥ 0.3 times the thickness of the side wall and not less than 1 mm, and the height of the support plate is ≥ 1 mm.

6. The method for controlling the axial stress and shrinkage stress of high-strength aluminum alloy rods according to claim 1, characterized in that, The support leg forms an angle of ≤50° with the part, and the thickness of the support leg is ≥0.3 times the thickness of the support plate, and not less than 0.5mm.