Process for preparing and forming pipe blank with variable pipe diameter and equal wall thickness

Abstract

The invention provides a variable-pipe-diameter equal-wall-thickness pipe blank preparation and forming process which is characterized in that liquid expansion pre-forming, solution treatment and liquid expansion final forming are adopted for a contracted pipe blank, so that the phenomenon of nonuniform product wall thickness caused by nonuniform material flow can be eliminated on the basis of fully ensuring the forming precision; and the product quality and the long-term reliability are improved. Compared with the prior art, the process has the advantages that the heating times are reduced, the processing difficulty and the production cost are greatly reduced, and the processing requirements of high-performance complex parts can be met.

Description

Technical Field

[0001] This invention belongs to the field of metal plastic forming and heat treatment technology, and particularly relates to a process for preparing and forming a tube blank with variable diameter and constant wall thickness. Background Technology

[0002] Recently, the application of lightweight alloy irregular thin-walled components in high-tech fields such as aerospace, automotive, shipbuilding, and military industries has been rapidly and steadily increasing. However, problems in the manufacturing process and the final product are also becoming increasingly prominent. For example, existing processes still lack effective solutions for high-precision machining control, making it difficult to guarantee precise local deformation and wall thickness uniformity, resulting in inconsistent quality of complex-shaped products. On the other hand, existing forming processes easily introduce significant residual stress, leading to the risk of warping and deformation during later processing and use. More importantly, the existing forming processes are numerous and difficult to simplify, resulting in generally long production cycles, low production efficiency, and high costs for producing such components. Summary of the Invention

[0003] In view of this, and to address the technical problems existing in this field, the present invention provides a process for preparing and forming a tube blank with variable diameter and constant wall thickness, specifically including the following steps:

[0004] Step 1: For a standard circular tube blank, use a tube shrinking die to perform a bidirectional extrusion compression operation from both the inside and outside of the tube blank according to the design tube diameter requirements corresponding to different tube sections of the component, so as to prepare a tube blank with variable diameter and constant wall thickness.

[0005] Step 2: Place the pipe blank with variable diameter and equal wall thickness into the preforming mold, seal both ends of the pipe blank and perform hydraulic expansion to make part of the pipe blank expand and deform locally and fit into the mold to obtain the preformed pipe blank.

[0006] Step 3: Perform solution treatment on the preformed tube blank;

[0007] Step 4: Place the preformed tube blank that has undergone solution treatment into the final forming mold, and perform hydraulic bulging again. Precisely control the deformation of the tube blank according to the design shape requirements to prepare the irregular thin-walled tube fitting.

[0008] Step 5: Based on the material's inherent properties and the design target strength, hardness, and corrosion resistance of the finished component, perform aging treatment on the irregularly shaped thin-walled pipe fittings;

[0009] Step 6: Perform post-processing on the aging-treated irregular thin-walled pipe fittings, including precision cutting, grinding and surface treatment, to obtain the final finished pipe fittings with varying diameters and wall thicknesses.

[0010] Further, in step 1, a tube-shrinking die consisting of an upper die, a lower die, a multi-lobed extrusion die, and a support die is used to perform the bidirectional extrusion tube-shrinking operation. During the tube-shrinking process, a standard circular tube blank is placed into the upper and lower dies for fixation, and the support die is inserted into the inner cavity of the standard circular tube blank. Then, the multiple lobes of the extrusion die merge and start rotating simultaneously, extruding the outer surface of the tube blank to cause it to deform uniformly. During the extrusion process, the support die provides support and extrusion to the inner surface of the tube blank to prevent local wrinkles and breakage.

[0011] Furthermore, the above process is performed using standard round tube blanks made of aluminum alloy, magnesium alloy, or titanium alloy to manufacture corresponding variable diameter and equal wall thickness pipe fittings.

[0012] Accordingly, the present invention also provides a pipe fitting product with variable diameter and equal wall thickness, which is specifically manufactured using the process provided by the present invention described above.

[0013] Accordingly, the present invention also provides a production line for pipe fittings with variable diameter and equal wall thickness, which specifically implements the process provided by the present invention to manufacture the corresponding products.

[0014] The variable diameter, constant wall thickness tube blank preparation and forming process provided by the present invention employs a liquid expansion pre-forming—solution treatment—liquid expansion final forming method for the tube blank after tube shrinkage. This method can eliminate the problem of uneven product wall thickness caused by uneven material flow while fully ensuring forming accuracy, thereby improving product quality and long-term reliability. Compared with the prior art, this process reduces the number of heating cycles, significantly reducing processing difficulty and production costs, thus meeting the processing requirements of high-performance complex parts. Attached Figure Description

[0015] Figure 1 A flowchart of the process provided by this invention;

[0016] Figure 2 This is a schematic diagram illustrating the structure and working principle of a bidirectional extrusion compression tube mold. Detailed Implementation

[0017] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. 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.

[0018] This invention provides a process for preparing and forming a tube blank with variable diameter and constant wall thickness, such as... Figure 1 As shown, the specific steps include:

[0019] Step 1: For a standard circular tube blank, using a tube-shrinking die, a bidirectional extrusion compression operation is performed from both the inside and outside of the tube blank according to the design diameter requirements corresponding to different tube sections of the component, to prepare a tube blank with variable diameter and constant wall thickness. By adjusting the extrusion parameters, the change and transition of the tube diameter can be precisely controlled, achieving efficient and accurate tube blank preparation, providing a good foundation for subsequent forming processes.

[0020] Step 2: Place the pipe blank with variable diameter and uniform wall thickness into the preforming mold, seal both ends of the pipe blank, and perform hydraulic bulging. This causes a portion of the pipe blank to expand and deform locally, fitting into the mold, thus obtaining a preformed pipe blank. In this hydraulic bulging process, rough forming can be completed first for the parts of the component with larger deformation.

[0021] Step 3: Perform solution treatment on the preformed tube blank. Solution treatment allows the reinforcing phase in the alloy to dissolve into the matrix, thereby effectively reducing cracks and defects during the forming process, ensuring the stability of the internal microstructure of the material, and improving the plasticity in subsequent fine forming processes.

[0022] Step 4: Place the preformed tube blank that has undergone solution treatment into the final forming mold, and perform hydraulic bulging again. Precisely control the deformation of the tube blank according to the design shape requirements to prepare a special-shaped thin-walled tube with high precision indicators.

[0023] Step 5: Based on the material's own characteristics and the design target strength, hardness, and corrosion resistance of the finished component, perform aging treatment on the irregular thin-walled pipe fittings.

[0024] Step 6: Perform post-processing on the aging-treated irregular thin-walled pipe fittings, including precision cutting, grinding, and surface treatment, to obtain the final finished pipe fittings with varying diameters and wall thicknesses. Machining or wire cutting processes can precisely control the cutting accuracy, avoiding deformation or stress concentration caused by excessive cutting.

[0025] In a preferred embodiment of the present invention, step 1 specifically uses a tube-shrinking die composed of an upper die, a lower die, a multi-lobed extrusion die, and a support die to perform the bidirectional extrusion tube-shrinking operation; the tube-shrinking process is as follows: Figure 2 As shown, a standard circular tube blank is placed into the upper and lower molds for fixation, and a support mold is inserted into the inner cavity of the standard circular tube blank; then, multiple mold segments of the extrusion mold merge and start rotating simultaneously, performing extrusion on the outer surface of the tube blank to cause uniform deformation. During the extrusion process, the support mold provides support and extrusion to the inner surface of the tube blank to prevent local wrinkles and breakage.

[0026] In a preferred embodiment of the present invention, a standard circular tube blank made of aluminum alloy, magnesium alloy or titanium alloy is used to perform the above process to manufacture corresponding variable diameter and equal wall thickness pipe fittings.

[0027] Accordingly, the present invention also provides a pipe fitting product with variable diameter and equal wall thickness, which is specifically manufactured using the process provided by the present invention described above.

[0028] Accordingly, the present invention also provides a production line for pipe fittings with variable diameter and equal wall thickness, which specifically implements the process provided by the present invention to manufacture the corresponding products.

[0029] In one embodiment of the present invention, 6061 aluminum alloy was used to manufacture a certain type of variable diameter, constant wall thickness pipe fitting. The specific steps are as follows:

[0030] (1) The standard round tube blank is selected based on the required maximum diameter. The tube blank with equal wall thickness is prepared by bidirectional extrusion compression tube technology. The tube blank diameter is uniformly transitioned from 8mm to 13mm.

[0031] (2) The tube blank after shrinking is hydraulically expanded to form a preformed structure with an appearance close to the final product shape.

[0032] (3) The preformed components are subjected to solution treatment and kept at 500℃ for 1 hour to ensure the stability of the material structure;

[0033] (4) After solution treatment, hydraulic bulging is performed again, and the bulging pressure and time are adjusted to obtain a component that meets the accuracy requirements.

[0034] (5) Enhance the strength of materials through aging treatment;

[0035] (6) Remove excess parts, burrs, barbs, etc. by wire cutting, machining, etc., and clean surface dirt to obtain the finished product.

[0036] It should be understood that the sequence number of each step in the embodiments of the present invention does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0037] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A process for preparing and forming a tube blank with variable diameter and constant wall thickness, characterized in that: Specifically, the following steps are included: Step 1: For a standard circular tube blank, use a tube shrinking die to perform a bidirectional extrusion compression operation from both the inside and outside of the tube blank according to the design tube diameter requirements corresponding to different tube sections of the component, so as to prepare a tube blank with variable diameter and constant wall thickness. Step 2: Place the pipe blank with variable diameter and equal wall thickness into the preforming mold, seal both ends of the pipe blank and perform hydraulic expansion to make part of the pipe blank expand and deform locally and fit into the mold to obtain the preformed pipe blank. Step 3: Perform solution treatment on the preformed tube blank; Step 4: Place the preformed tube blank that has undergone solution treatment into the final forming mold, and perform hydraulic bulging again. Precisely control the deformation of the tube blank according to the design shape requirements to prepare the irregular thin-walled tube fitting. Step 5: Based on the material's own characteristics and the design target strength, hardness, and corrosion resistance of the finished component, perform aging treatment on the irregularly shaped thin-walled pipe fittings; Step 6: Perform post-processing on the aging-treated irregular thin-walled pipe fittings, including precision cutting, grinding and surface treatment, to obtain the final finished pipe fittings with variable diameter and equal wall thickness.

2. The process as described in claim 1, characterized in that: In step 1, a tube-shrinking die consisting of an upper die, a lower die, a multi-lobed extrusion die, and a support die is used to perform the bidirectional extrusion tube compression operation. During the tube-shrinking process, a standard circular tube blank is placed into the upper and lower dies for fixation, and the support die is inserted into the inner cavity of the standard circular tube blank. Then, the multiple lobes of the extrusion die merge and start rotating simultaneously, extruding the outer surface of the tube blank to cause uniform deformation. During the extrusion process, the support die provides support and extrusion to the inner surface of the tube blank to prevent local wrinkles and breakage.

3. The process as described in claim 1, characterized in that: Specifically, standard round tube blanks made of aluminum alloy, magnesium alloy, or titanium alloy are used to manufacture corresponding variable diameter and equal wall thickness pipe fittings using the above process.

4. A pipe fitting product with variable diameter and constant wall thickness, characterized in that: Specifically, it is manufactured by performing the process described in any one of claims 1-3.

5. A production line for pipe fittings with variable diameter and constant wall thickness, characterized in that: The product is manufactured by specifically implementing the process described in any one of claims 1-3.

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