A high-precision machining method for a four-claw overhanging special-shaped thin-wall aluminum alloy part

Abstract

The present application relates to aluminum alloy processing technical field, specifically to a kind of four-claw overhanging special-shaped thin-walled aluminum alloy part high-precision processing method, solve the existing four-claw overhanging special-shaped thin-walled aluminum alloy part during processing, process stress release is not sufficient, clamping is prone to thin-walled deformation, overhanging part is prone to flutter let knife, finishing cutting stress is big, and precision stability is poor, difficult to support batch production problem, including the following steps: S1: rough milling and high-temperature aging, the profile of plate is rough milling to obtain aluminum alloy parts, and 1mm processing allowance is reserved on single side, integral process platform is retained, after first heat preservation treatment, with furnace cooling;S2: semi-finishing milling and medium-temperature aging, semi-finishing milling is carried out on aluminum alloy part to form A reference surface, and 0.3mm finishing allowance is reserved on single side.The present application guarantees size long-term stability by two-stage aging, solves thin-walled vibration let knife phenomenon by combined support, precision reaches precision level, adapts batch production, is widely applicable and process is easy to land.

Description

Technical Field

[0001] This invention relates to the field of aluminum alloy processing technology, specifically a high-precision machining method for four-jaw suspended irregular-shaped thin-walled aluminum alloy parts. Background Technology

[0002] In the aerospace and semiconductor equipment fields, irregularly shaped thin-walled aluminum alloy parts are widely used due to their advantages of lightweight, high specific strength, and high structural integration. Among them, 7075 series aluminum alloys are the preferred manufacturing material for such parts due to their excellent tensile strength and fatigue resistance. These parts typically have composite structural features such as irregular outer contours, ultra-thin wall thickness, multiple claws suspended, and partial hollowing. The typical wall thickness is only 1-3mm, and the four claw functional areas are in an unsupported suspended state. At the same time, they have extremely high requirements for dimensional accuracy, geometric tolerances, and surface quality, and are typical difficult-to-machine structural parts in the field of precision machining.

[0003] In the current process of machining thin-walled aluminum alloy parts with irregular shapes using four-jaw chucks, the process stress is not fully released, clamping easily leads to deformation of the thin wall, the suspended parts are prone to chatter and tool deflection, the cutting stress during finishing is large, and the accuracy stability is poor, making it difficult to support mass production. Therefore, it does not meet the current requirements. In response, we propose a high-precision machining method for thin-walled aluminum alloy parts with irregular shapes using four-jaw chucks. Summary of the Invention

[0004] The purpose of this invention is to provide a high-precision machining method for four-jaw suspended irregular thin-walled aluminum alloy parts, in order to solve the problems mentioned in the background art, such as insufficient release of process stress, easy deformation of thin walls due to clamping, easy chatter and tool deflection in the suspended part, large cutting stress in finishing, poor accuracy stability, and difficulty in supporting mass production.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a high-precision machining method for four-jaw suspended irregular-shaped thin-walled aluminum alloy parts, comprising the following steps: S1: Rough milling and high-temperature aging. The aluminum alloy parts are obtained by rough milling the shape of the sheet metal, with a 1mm machining allowance reserved on one side. The integrated process table is retained, and the parts are cooled with the furnace after the first heat preservation treatment. S2: Semi-finish milling and medium-temperature aging. The aluminum alloy parts are semi-finish milled to form the A reference surface, and a 0.3mm finishing allowance is reserved on one side. M4 assembly holes are machined on the process table, and the parts are cooled with the furnace after the second heat preservation treatment. S3: Clamping and auxiliary reinforcement: The process table and positioning fixture are attached and locked with bolts, and reinforced with AB glue. The thin-walled suspended area and the four-claw hollow area are densely filled and supported with plaster. S4: Layered precision finishing, using two end mills to perform layered cutting, finishing in the order of reference surface A, front and back, removing 0.3mm of allowance from the aluminum alloy part to the drawing requirements; S5: Post-processing and molding. The aluminum alloy parts are removed from the process table, plaster and glue residue are cleaned, deburred and cleaned, and then three-coordinate measuring machine is used for three-coordinate inspection to obtain the finished product.

[0006] Preferably, the plate material is 7075-T651 aluminum alloy, and the aluminum alloy parts are rough milled and semi-finish milled respectively by a vertical CNC machining center of model VMC850.

[0007] Preferably, the vertical CNC machining center uses the following rough milling parameters for aluminum alloy parts: spindle speed S1500r / min, feed rate F800mm / min, radial cutting width ae=12mm and axial cutting depth ap=2mm, and performs layered cutting on the contour of the aluminum alloy parts.

[0008] Preferably, the semi-finish milling parameters for aluminum alloy parts by the vertical CNC machining center are spindle speed S2500r / min, feed rate F600mm / min and axial depth of cut ap=0.5mm, and the flatness of the reference surface is controlled to be ≤0.05mm.

[0009] Preferably, the aluminum alloy parts are subjected to a first heat preservation treatment and a second heat preservation treatment respectively using a box-type resistance furnace of model SX2-12-12. The first heat preservation treatment is performed at 300℃ for 3-4 hours, and the second heat preservation treatment is performed at 185℃-195℃ for 4-6 hours.

[0010] Preferably, the A and B components of the AB adhesive are in a 1:1 mass ratio, the AB adhesive placement points are spaced 30mm apart, and the AB adhesive has a static curing time of not less than 30 minutes.

[0011] Preferably, the positioning fixture is a positioning plate, the plaster in the thin-walled suspended area is two thin-walled supporting plaster blocks, the plaster in the four-claw hollow area is four claw supporting plaster blocks, and the positioning plate and the aluminum alloy part are fixedly connected by the two thin-walled supporting plaster blocks and the four claw supporting plaster blocks, respectively.

[0012] Preferably, the two end mills are made of D6 carbide and D4 carbide, respectively. The depth of cut of each layer of the end mill is 0.05-0.1 mm. The rotational speed of the two end mills is S6000 r / min and the feed rate is F1200 mm / min.

[0013] Preferably, the aluminum alloy parts are removed from the process table using a DK7732 slow wire EDM machine, the aluminum alloy parts are cleaned using a KQ-250DE CNC ultrasonic cleaner, and the coordinate measuring machine is a Zeiss CONTURA, which is used to measure the form and position tolerances of the aluminum alloy parts.

[0014] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention utilizes a two-stage aging process of high-temperature stress relief and medium-temperature stabilization to release residual cutting stress generated at each processing stage in a stepwise and thorough manner, stabilize the internal metallographic structure of the parts, effectively prevent deformation phenomena such as springback and warping after the parts are processed, and ensure the long-term stability of the parts' dimensions and their reliability in use. 2. This invention relies on a combination of integrated process table clamping, AB glue point reinforcement, and plaster filling support to avoid tool deflection and cutting vibration in thin-walled suspended parts. Combined with a layered precision milling process with a unified benchmark, it can stably control the size and form and position tolerances of parts to a precision level. The process has strong consistency and is suitable for mass production needs. It can be widely used in the high-precision machining of various irregular, thin-walled, multi-claw, and hollow complex structural parts of aluminum alloys, with a high degree of process standardization. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the A-reference plane of the aluminum alloy part of the present invention; Figure 2 This is a schematic diagram of the positioning plate of the present invention; Figure 3 This is a schematic diagram of the clamping of the aluminum alloy parts of the present invention; Figure 4 This is a schematic diagram of the overall process of the present invention.

[0016] In the diagram: 1. Positioning plate; 2. Claw-supported plaster block; 3. Thin-walled supporting plaster block. Detailed Implementation

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

[0018] Please see Figures 1 to 4 The present invention provides an embodiment of a high-precision machining method for a four-jaw suspended irregular-shaped thin-walled aluminum alloy part, comprising the following steps: S1: Rough milling and high-temperature aging. A vertical CNC machining center is used to rough mill the outer contour of the part with parameters of spindle speed S1500r / min, feed rate F800mm / min, radial cutting width ae=12mm and axial cutting depth ap=2mm to obtain aluminum alloy parts. Throughout the machining process, an integrated process table with an outer width of 15mm is retained as a clamping and positioning carrier for subsequent processes. Finally, a 1mm machining allowance is reserved on each side. After rough milling, the part is placed in an SX2-12-12 type box-type resistance furnace and heated to 300℃ at a heating rate of 5℃ / min for the first heat preservation treatment. Then, it is cooled to below 50℃ in the furnace and removed from the furnace to fully eliminate the residual internal stress generated by rough machining and suppress dimensional deformation in subsequent processes. S2: Semi-finish milling and medium-temperature aging. The aluminum alloy part is semi-finish milled on the A reference surface in a vertical CNC machining center. The cutting parameters are S2500r / min, feed rate F600mm / min and axial depth of cut ap=0.5mm, and the flatness of the reference surface is controlled to be ≤0.05mm. After machining, a 0.3mm finishing allowance is reserved on each side. At the same time, M4 bolt assembly holes are machined evenly in the corresponding position on the process table for subsequent locking and fixing with positioning fixtures. After semi-finish milling, the aluminum alloy part is transferred into the SX2-12-12 box-type resistance furnace, heated to 185℃ at 3℃ / min and subjected to a second heat treatment. After cooling to room temperature in the furnace, it is taken out of the furnace to further release the semi-finish milling cutting stress and stabilize the metallographic structure and dimensional accuracy of the aluminum alloy part. S3: Clamping and auxiliary reinforcement: Fix the positioning fixture to the machining center worktable, use a dial indicator to calibrate the flatness of the positioning fixture's reference surface to ≤0.02mm, then align the process table with the positioning surface of the positioning fixture and insert the positioning pin to complete the process. Next, mix AB glue in a 1:1 ratio and apply it at 30mm intervals along the mating surfaces of the process table and the positioning fixture to increase the rigidity of the clamping connection. At the same time, mix and vibrate the plaster to remove air bubbles, then inject it into the thin-walled suspended areas and four-claw hollow areas of the aluminum alloy parts for dense filling and support. After standing and curing for no less than 30 minutes, it will offset the cutting force of the finishing process and prevent thin-walled vibration, tool deflection, and machining deformation. S4: Layered precision machining. Two end mills, one made of D6 carbide and the other of D4 carbide, are used for layered cutting. The cutting depth of each layer is 0.05-0.1mm. First, the A datum surface is precision milled to ensure that the flatness is ≤0.02mm. This datum surface is used as the only unified positioning datum for the entire process. Then, the front contour of the aluminum alloy part is precision milled sequentially with the A datum surface in place. Finally, the part is flipped over and repositioned. After ensuring that the repetitive alignment accuracy is ≤0.01mm, the reverse side of the aluminum alloy part is precision milled. The 0.3mm finishing allowance is completely removed at a speed of S6000r / min and a feed rate of F1200mm / min to ensure that the parallelism, positional tolerances and other geometric tolerances of the part and the accuracy of key dimensions meet the requirements of the drawing. S5: Post-processing and shaping. A DK7732 slow wire EDM machine is used to cut and separate the aluminum alloy parts from the process table. Then, the internal plaster filling is peeled off by tapping, and the AB glue stains are removed by wiping with adhesive remover. All edges are then ground and rounded to remove burrs and flash. After cleaning, the parts are placed in a KQ-250DE CNC ultrasonic cleaner for further cleaning. Then, a Zeiss CONTURA coordinate measuring machine is used to check the key dimensions, flatness, parallelism, positional tolerances, and other geometric tolerances of the parts. Once all indicators meet the drawing requirements, the parts are considered qualified finished products.

[0019] The sheet metal is made of 7075-T651 aluminum alloy. The aluminum alloy parts are rough milled and semi-finish milled by a VMC850 vertical CNC machining center. The first heat preservation treatment is to keep the temperature at 300℃ for 3-4 hours, and the second heat preservation treatment is to keep the temperature at 185℃-195℃ for 4-6 hours.

[0020] Please see Figure 2 and Figure 3 The positioning fixture is a positioning plate 1. The plaster in the thin-walled suspended area is two thin-walled support plaster blocks 3. The plaster in the four-claw hollow area is four claw support plaster blocks 2. The positioning plate 1 and the aluminum alloy parts are fixedly connected by two thin-walled support plaster blocks 3 and four claw support plaster blocks 2 respectively.

[0021] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A high-precision machining method for a four-jaw suspended irregularly shaped thin-walled aluminum alloy part, characterized in that, Includes the following steps: S1: Rough milling and high-temperature aging. The aluminum alloy parts are obtained by rough milling the shape of the sheet metal, with a 1mm machining allowance reserved on one side. The integrated process table is retained, and the parts are cooled with the furnace after the first heat preservation treatment. S2: Semi-finish milling and medium-temperature aging. The aluminum alloy parts are semi-finish milled to form the A reference surface, and a 0.3mm finishing allowance is reserved on one side. M4 assembly holes are machined on the process table, and the parts are cooled with the furnace after the second heat preservation treatment. S3: Clamping and auxiliary reinforcement: The process table and positioning fixture are attached and locked with bolts, and reinforced with AB glue. The thin-walled suspended area and the four-claw hollow area are densely filled and supported with plaster. S4: Layered precision finishing, using two end mills to perform layered cutting, finishing in the order of reference surface A, front and back, removing 0.3mm of allowance from the aluminum alloy part to the drawing requirements; S5: Post-processing and molding. The aluminum alloy parts are removed from the process table, plaster and glue residue are cleaned, deburred and cleaned, and then three-coordinate measuring machine is used for three-coordinate inspection to obtain the finished product.

2. The high-precision machining method for a four-jaw suspended irregularly shaped thin-walled aluminum alloy part according to claim 1, characterized in that: The plate material is 7075-T651 aluminum alloy, and the aluminum alloy parts are rough milled and semi-finish milled respectively by a VMC850 vertical CNC machining center.

3. The high-precision machining method for a four-jaw suspended irregularly shaped thin-walled aluminum alloy part according to claim 2, characterized in that: The vertical CNC machining center uses the following rough milling parameters for aluminum alloy parts: spindle speed S1500r / min, feed rate F800mm / min, radial cutting width ae=12mm and axial cutting depth ap=2mm, and performs layered cutting on the contour of the aluminum alloy parts.

4. The high-precision machining method for a four-jaw suspended irregularly shaped thin-walled aluminum alloy part according to claim 3, characterized in that: The vertical CNC machining center uses the following semi-finish milling parameters for aluminum alloy parts: spindle speed S2500r / min, feed rate F600mm / min, and axial depth of cut ap=0.5mm, while controlling the flatness of the reference surface to ≤0.05mm.

5. A high-precision machining method for a four-jaw suspended irregularly shaped thin-walled aluminum alloy part according to claim 4, characterized in that: The aluminum alloy parts are subjected to a first heat preservation treatment and a second heat preservation treatment respectively in a box-type resistance furnace of model SX2-12-12. The first heat preservation treatment is to keep the parts at 300℃ for 3-4 hours, and the second heat preservation treatment is to keep the parts at 185℃-195℃ for 4-6 hours.

6. A high-precision machining method for a four-jaw suspended irregularly shaped thin-walled aluminum alloy part according to claim 5, characterized in that: The A and B components of the AB adhesive are in a 1:1 mass ratio, the AB adhesive placement points are spaced 30mm apart, and the static curing time of the AB adhesive is not less than 30 minutes.

7. A high-precision machining method for a four-jaw suspended irregularly shaped thin-walled aluminum alloy part according to claim 6, characterized in that: The positioning fixture is a positioning plate (1), the plaster in the thin-walled suspended area is two thin-walled supporting plaster blocks (3), the plaster in the four-claw hollow area is four claw supporting plaster blocks (2), and the positioning plate (1) and the aluminum alloy parts are fixedly connected by two thin-walled supporting plaster blocks (3) and four claw supporting plaster blocks (2) respectively.

8. A high-precision machining method for a four-jaw suspended irregularly shaped thin-walled aluminum alloy part according to claim 7, characterized in that: The two end mills are made of D6 carbide and D4 carbide, respectively. The depth of cut of each end mill is 0.05-0.1 mm. The rotational speed of the two end mills is S6000 r / min and the feed rate is F1200 mm / min.

9. A high-precision machining method for a four-jaw suspended irregularly shaped thin-walled aluminum alloy part according to claim 8, characterized in that: The aluminum alloy parts are removed from the process table using a DK7732 slow wire EDM machine. The aluminum alloy parts are cleaned using a KQ-250DE CNC ultrasonic cleaner. The coordinate measuring machine is a Zeiss CONTURA, used to measure the form and position tolerances of the aluminum alloy parts.

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