A processing method for rapid milling of a profile part with complex structure and shape

Abstract

The present application relates to the fast milling processing method of the complex structure and shape section parts of the airplane, and belongs to the field of aviation sheet metal forming technology. The present application solves the one-time processing of the appearance milling and drilling of the traditional complex cross-section shape and different size section parts, discards the drilling precision ensured by the drilling jig for the hole making of the section part, improves the surface quality of the section part, improves the manufacturing precision of the appearance, notch, bevel and hole, improves the processing efficiency, completes a set of tooling capable of processing different specifications of section parts through the pneumatic universal drilling and milling jig, realizes the efficient and accurate manufacturing of the section part, realizes the group milling of the workpiece, and further reduces the raw material cost, tooling manufacturing cost and shortens the process flow.

Description

Technical Field

[0001] This invention relates to a rapid milling method for complex structural and shaped profile parts of aircraft, belonging to the field of aerospace sheet metal forming technology. Background Technology

[0002] Long strings, arms, and supports serve as connecting components for the aircraft's fuselage, beams, control systems, fuel systems, and other skeletal structures. Their manufacturing precision and surface quality directly affect the overall aircraft's shape accuracy and aerodynamic performance. These profiled parts with varying shapes are widely used in the longitudinal and transverse components of aircraft. Due to their diverse shapes, cross-sectional forms, and dimensions, the commonly used machining method is conventional vertical milling. Currently in China's aviation industry, the shapes, notches, and bevels of aluminum alloy profiled parts are machined using semi-automatic hand-cranked milling, with a shape tolerance of approximately 0.5 mm. Because the process involves first marking lines according to a template and then visually milling along those lines on a vertical milling machine, it is impossible to guarantee that the manufacturing precision of all parts is within 0.5 mm. This method restricts the production efficiency and quality of profiled parts. With the iteration and upgrading of aircraft, the number of these small-sized profiled parts is gradually increasing, and conventional milling methods cannot meet the demands of quantity and batch production, resulting in high manufacturing costs and low production efficiency.

[0003] This invention proposes a method for rapidly milling and drilling profile parts and holes in groups. Based on CATIA software for drawing and projection analysis, a two-dimensional unfolded digital model of the profile is created. The edge lines of the projection surface of the pre-milled profile part are extracted to generate closed curves. The machining path is set, and a CNC milling program for the closed curves is compiled. A three-axis CNC milling machine is used to perform one-time milling and drilling of profile parts with various specifications, complex cross-sectional shapes, and different sizes. This method eliminates the need to use drilling jigs to ensure drilling accuracy in profile parts, improves the surface quality of profile parts, and enhances the manufacturing accuracy and processing efficiency of the shape, notches, bevels, and holes. Through a series of explorations and experiments, efficient and precise profile manufacturing is achieved, thereby reducing raw material costs, tooling manufacturing costs, and shortening the process flow.

[0004] As the machinery manufacturing industry is transforming towards intelligent manufacturing, there are higher demands for the shape precision and service life of various types of aircraft materials. Traditional single processing methods can no longer meet performance requirements, and there is an urgent need for new processing methods to iterate, optimize and improve aircraft parts manufacturing technology. Summary of the Invention

[0005] This invention addresses a series of problems associated with conventional milling methods for complex structures and shapes, including their reliance on single-piece milling, low dimensional accuracy, poor continuity, and limited application. It proposes a rapid milling and drilling method for profile parts, enabling efficient and precise manufacturing of profile parts with various specifications, complex shapes, and variable cross-sections. This method can also be used for milling the shapes and holes of formed aircraft aluminum alloy sheet metal profiles, as well as for milling the shapes of complex sheet metal parts after forming. Examples of typical profile parts with different specifications and shapes are provided.

[0006] The technical solution of the present invention is as follows:

[0007] A method for rapid milling of profile parts with complex structures and shapes, comprising the following steps:

[0008] Step 1: Sawing

[0009] Sawing is widely used for cutting various materials, such as wood, metal, and plastic. The specific operation involves using a high-speed band saw to cut raw materials or semi-finished products. Through the high-frequency vibration of the saw blade, the material is effectively cut into the required shape and size. The cutting of materials is mainly achieved through the movement of the saw.

[0010] Step 2: CNC milling of profiles

[0011] CNC milling of profiles is a metal processing method used in CNC machine tools. It uses a high-speed rotating tool to transmit cutting force to the surface of the workpiece. In the relative movement between the tool and the workpiece, excess material is quickly removed from the workpiece, so that the workpiece obtains the specified geometric parameters and surface quality.

[0012] Step 3: Assembly via CNC drilling;

[0013] CNC milling achieves high precision and surface quality. CNC drilling refers to the operation of machining holes in a workpiece using a drill bit. The advantages of CNC drilling are high precision, high speed, and high efficiency. Both profile CNC milling and CNC drilling are based on setting the coordinate origin according to the programmed settings. A set of pneumatic universal drilling and milling dies is required to achieve positioning and clamping during the milling and drilling process.

[0014] The processing method employs a positioning fixture device, which includes: a profile positioning block, a Z-shaped profile pressure plate, a rubber pad, a protective cover, a double cylinder assembly, a pneumatic cylinder positioning block, a manual directional valve assembly, a base plate, screws, a triple air source treatment assembly component, a cylinder body, an end cap, a straight head, a double-way elbow, a T-type tee, a manual directional valve, a muffler, a quick-connect external thread connector, a flow rate regulating valve, a water-resistant polyurethane hose, an air pressure regulating valve, a connecting frame, an air filter, and an oil mist lubricator. The profile positioning block is bolted to the base plate, has the same length as the base plate, a width of 96 mm, and a height of 98 mm. Its function is to position the clamping edge of the profile part. To prevent scratching the part, the inner long side of the profile positioning block is rounded with a radius of R2. The Z-shaped pressure plate has the same total length as the base plate. It is composed of 6 movable pressure plates, each measuring 295×48×100 mm. A rubber pad is adhered to the inside of each pressure plate to protect the surface of the parts from scratches. A protective cover covers all outer surfaces of the double cylinder assembly and the pneumatic cylinder positioning block. Its function is to prevent metal shavings from splashing into all connection points of the double cylinder assembly and the pneumatic cylinder positioning block, causing blockages. The double cylinder assembly consists of one cylinder body, one end cap, one straight head, and two double-bend connectors assembled with M6 screws. The cylinder body is connected to the end cap via one straight head, and the two double-bend connectors are connected to the cylinder body. There are a total of 12 double cylinder assemblies. The lower part of the pneumatic cylinder positioning block is connected to the base plate with M6 screws, and the upper part of the pneumatic cylinder positioning block is connected to the cylinder body with M6 screws. There are a total of 22 T-type tee connectors, arranged in pairs, distributed on one side of the double cylinder assembly where the double-bend connectors are installed. The manual directional valve assembly consists of a manual directional valve, a silencer, a quick-connect male threaded coupling, and a flow rate regulating valve. The manual directional valve functions by rotating the handle, which moves the valve core to change the direction of compressed air flow. The silencer primarily reduces noise. The quick-connect male threaded coupling connects the manual directional valve to the water-resistant polyurethane hose. The flow rate regulating valve adjusts the compressed air flow rate, maintaining a constant pressure difference before and after the flow. The three-unit air source treatment assembly consists of an air pressure regulating valve, connecting brackets, an air filter, and an oil mist lubricator. The air pressure regulating valve ensures the system's operating pressure remains within the set range, maintaining normal system operation. The air filter removes contaminants from the air. The oil mist lubricator atomizes lubricating oil and sprays it into the compressed air pipeline, where it enters the system to lubricate the surfaces of relatively moving parts. Two connecting brackets connect the air pressure regulating valve, air filter, and oil mist lubricator, respectively. (See the pneumatic schematic diagram.) Figure 1 It uses water-resistant polyurethane hoses to connect 24 double elbows, 22 T-type tees, manual reversing valve assemblies, and triple air source treatment components.

[0015] The beneficial effects of this invention:

[0016] The combined milling method for complex-shaped profile parts solves the problem of one-time processing of milling and drilling of profile parts with complex cross-sections and different sizes. It eliminates the need to ensure drilling accuracy by using drilling jigs to make holes in profile parts, improves the surface quality of profile parts, and enhances the manufacturing accuracy and processing efficiency of the shape, notches, bevels and holes. By using a pneumatic universal drilling and milling jig, it meets the requirement that a set of tooling can process profile parts of different specifications, realizes efficient and precise profile manufacturing, and reduces raw material costs, tooling manufacturing costs and shortens the process flow by grouping and milling workpieces. Attached Figure Description

[0017] Figure 1 Pneumatic principle diagram.

[0018] Figure 2 Isometric view of a triple air source treatment component assembly.

[0019] Figure 3 Axonometric drawing of a pneumatic universal drilling and milling die (with protective cover).

[0020] Figure 4 Axonometric drawing of a pneumatic universal drilling and milling die (without protective cover).

[0021] In the diagram: 1. Profile positioning block; 2. Z-profile pressure plate; 3. Rubber pad; 4. Protective cover; 5. Double cylinder assembly; 6. Pneumatic cylinder positioning block; 7. Manual directional valve assembly; 8. Base plate; 9. Screw; 10. Triple air source treatment assembly components; 11. Cylinder body; 12. End; 13. Straight connector; 14. Double bend connector; 15. T-type tee connector; 16. Manual directional valve; 17. Silencer; 18. Quick external thread connector; 19. Flow rate regulating valve; 20. Water-resistant polyurethane hose; 21. Air pressure regulating valve; 22. Connecting bracket; 23. Air filter; 24. Oil mist lubricator. Detailed Implementation

[0022] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. The following examples are used to illustrate the present invention, but are not intended to limit the scope of application of the present invention.

[0023] Based on the structural characteristics of complex-shaped profile parts, a rapid milling process flow is formulated. Taking a typical grooved profile part as an example, the implementation steps of the combined forming method are as follows:

[0024] Example 1:

[0025] A method for rapid milling of profile parts with complex structures and shapes, comprising the following steps:

[0026] Step 1: Connect 24 double elbows 14, 22 T-type tee connectors 15, manual reversing valve assembly 7, and triple air source treatment assembly component 10 using water-resistant polyurethane hose 20.

[0027] Step 2: Install the pneumatic universal drilling and milling die on the CNC milling equipment and fix the pneumatic universal drilling and milling die to the equipment with 10 M6 screws.

[0028] Step 3: Determine the workpiece to be processed based on the requirements of the workpiece to be processed.

[0029] Step 4: Create a 2D unfolded digital model of the profile part, extract the edge lines of the pre-milled projection surface of the profile part to generate a closed curve, set the machining path, and compile the CNC milling program for the closed curve.

[0030] Step 5: Select appropriate milling cutters and drill bits according to the characteristics and requirements of the workpiece.

[0031] Step 6: Select appropriate cutting conditions based on the material and dimensions of the object being machined.

[0032] Step 7: Determine the machining coordinate system, including determining the machining directions of the milling machine in the x, y, and z directions.

[0033] Step 8: Fix the workpiece between the profile positioning block 1 and the Z-profile pressure plate 2, rotate the manual reversing valve 16, and compressed air enters the double cylinder assembly 5 through the water-resistant polyurethane hose 20 to push the end head 12, clamping the workpiece to ensure that it will not move or slide down.

[0034] Step 9: Adjust the position of the cutting tool according to the requirements of the workpiece and the clamping position of the workpiece so that it can cut the material correctly during processing.

[0035] Step 10: Turn on the milling machine and the cutting fluid, and begin milling or drilling.

[0036] Step 11: Inspect the condition of the semi-finished product. Check the surface quality of the semi-finished product. The surface of the semi-finished product should be free of oil stains, rust, dents, scratches, etc.

[0037] Example 2:

[0038] The tooling used in the processing method is a positioning fixture device, which includes: profile positioning block 1, Z-shaped profile pressure plate 2, rubber pad 3, protective cover 4, double cylinder assembly 5, pneumatic cylinder positioning block 6, manual reversing valve assembly 7, base plate 8, screw 9, triple air source treatment assembly component 10, cylinder body 11, end head 12, straight head 13, double bend connector 14, T-type tee connector 15, manual reversing valve 16, silencer 17, quick external thread connector 18, flow rate regulating valve 19, water-resistant polyurethane hose 20, air pressure regulating valve 21, connecting bracket 22, air filter 23, and oil mist lubricator 24. The profile positioning block 1 is bolted to the base plate 8, has the same length as the base plate 8, a width of 96 mm, and a height of 98 mm. Its function is to position the clamping edge of the profile part. To prevent scratching the part, the inner long side of the profile positioning block 1 and the contact edge with the part are rounded with a radius R2. The Z-shaped pressure plate 2 has the same total length as the base plate 8. It is composed of 6 movable pressure plates, each measuring 295×48×100mm. A rubber pad 3 is adhered to the inner side of each pressure plate where it contacts the part; the rubber pad 3 protects the part surface from scratches. A protective cover 4 covers all outer surfaces of the double cylinder assembly 5 and the pneumatic cylinder positioning block 6. Its function is to prevent metal shavings from splashing into all connecting parts of the double cylinder assembly 5 and the pneumatic cylinder positioning block 6, causing blockages. The double cylinder assembly 5 consists of one cylinder body 11, one end cap 12, one straight head 13, and two double-through bend connectors 14 assembled with M6 screws. The cylinder body 11 is connected to the end cap 12 via one straight head 13, and the two double-through bend connectors 14 are connected to the cylinder body 11. There are a total of 12 double cylinder assemblies 5. The lower part of the pneumatic cylinder positioning block 6 is connected to the base plate 8 with M6 screws, and the upper part of the pneumatic cylinder positioning block 6 is connected to the cylinder body 11 with M6 screws. There are a total of 22 T-type three-way connectors 15, with each pair forming a combination, distributed on one side of the double cylinder assembly 5 where the double-way elbow connector 14 is installed. The manual reversing valve assembly 7 consists of a manual reversing valve 16, a muffler 17, a quick-connect external thread connector 18, and a flow rate regulating valve 19. The function of the manual reversing valve 16 is to change the flow direction of compressed air by rotating the handle and moving the valve core. The muffler 17 is mainly used to reduce noise. The quick-connect external thread connector 18 connects the manual reversing valve 16 to the water-resistant polyurethane hose 20. The flow rate regulating valve 19 is responsible for regulating the flow rate of compressed air and maintaining a constant pressure difference before and after the flow. The triple air source treatment assembly component 10 is assembled from an air pressure regulating valve 21, a connecting bracket 22, an air filter 23, and an oil mist lubricator 24. The air pressure regulating valve 21 ensures that the system's operating pressure remains within the set range, maintaining normal system operation. The air filter 23 removes contaminants from the air. The lubricant mist lubricator 24 atomizes lubricating oil and sprays it into the compressed air pipeline, where it enters the system to lubricate the surfaces of relatively moving parts. Two connecting brackets 22 connect the air pressure regulating valve 21, the air filter 23, and the lubricant mist lubricator 24, respectively. (See the pneumatic schematic diagram.) Figure 1 The system uses water-resistant polyurethane hoses 20 to connect 24 double-bend connectors 14, 22 T-type tee connectors 15, manual reversing valve assembly 7, and triple air source treatment assembly component 10.

Claims

1. A method for rapid milling of profile parts with complex structures and shapes, characterized in that, The steps are as follows: Step 1: Connect 24 double elbows (14), 22 T-type tee joints (15), manual reversing valve assembly (7), and triple air source treatment assembly component (10) using water-resistant polyurethane hoses (20); Step 2: Install the pneumatic universal drilling and milling die on the CNC milling equipment and fix the pneumatic universal drilling and milling die on the equipment with 10 M6 screws (9); Step 3: Determine the workpiece to be processed; Step 4: Create a 2D unfolded digital model of the profile part, extract the edge lines of the pre-milled projection surface of the profile part to generate a closed curve, set the machining path, and compile the CNC milling program for the closed curve; Step 5: Select the end mill and drill bit; Step 6: Select cutting conditions based on the material and dimensions of the workpiece; Step 7: Determine the machining coordinate system, including determining the machining directions of the milling machine in the x, y, and z directions; Step 8: Fix the workpiece between the profile positioning block (1) and the Z-profile pressure plate (2), rotate the manual reversing valve (16), and compressed air enters the double cylinder assembly (5) through the water-resistant polyurethane hose (20) to push the end (12), clamp the workpiece, and ensure that it will not move or slide down. Step 9: Adjust the position of the cutting tool according to the requirements of the workpiece and the clamping position of the workpiece so that it can cut the material correctly during processing; Step 10: Turn on the milling machine and the cutting fluid, and begin milling or drilling; Step 11: Check the condition of the semi-finished products; check the surface quality of the semi-finished products. The surface of the semi-finished products should be free of oil stains, rust, dents, and scratches.

2. The machining method for rapid milling of complex structure and shape profile parts as described in claim 1, characterized in that, The tooling used in the processing method is a positioning fixture device, which includes: profile positioning block (1), Z-shaped pressure plate (2), rubber pad (3), protective cover (4), double cylinder assembly (5), pneumatic cylinder positioning block (6), manual reversing valve assembly (7), base plate (8), screw (9), triple air source treatment assembly component (10), cylinder body (11), end head (12), straight head (13), double bend connector (14), T-type tee connector (15), manual reversing valve (16), silencer (17), quick external thread connector (18), flow rate regulating valve (19), water-resistant polyurethane hose (20), air pressure regulating valve (21), connecting frame (22), air filter (23), and oil mist lubricator (24).

3. The machining method for rapid milling of complex structure and shape profile parts as described in claim 2, characterized in that, The profile positioning block (1) is connected to the base plate (8) by bolts, and its length is the same as that of the base plate (8). The long inner side of the profile positioning block (1) is rounded with a radius R2.

4. The machining method for rapid milling of complex structure and shape profile parts as described in claim 2, characterized in that, The Z-shaped pressure plate (2) has the same total length as the base plate (8) and is composed of 6 movable pressure plates. Each pressure plate is 295×48×100 (mm) in size, and a rubber pad (3) is glued to the inner side (the side in contact with the part) of each pressure plate.

5. The machining method for rapid milling of complex structure and shape profile parts as described in claim 2, characterized in that, The protective cover (4) covers all the outer surfaces of the double cylinder assembly (5) and the pneumatic cylinder positioning block (6). The double cylinder assembly (5) is composed of one cylinder body (11), one end head (12), one straight head (13), and two double-through bend connectors (14) assembled by M6 screws. The cylinder body (11) and the end head (12) are connected by one straight head (13), and the two double-through bend connectors (14) are connected to the cylinder body (11). There are a total of 12 double cylinder assemblies (5).

6. The machining method for rapid milling of complex structure and shape profile parts as described in claim 2, characterized in that, The pneumatic cylinder positioning block (6) is connected to the base plate (8) at the bottom by M6 screws, and the pneumatic cylinder positioning block (6) is connected to the cylinder body (11) at the top by M6 screws; there are a total of 22 T-type three-way connectors (15), with 2 of them forming a combination, distributed on the side of the double cylinder assembly (5) where the double-way elbow connector (14) is installed; the manual reversing valve assembly (7) consists of a manual reversing valve (16), a muffler (17), a quick external thread connector (18), and a flow rate regulating valve (19).

7. The machining method for rapid milling of complex structure and shape profile parts as described in claim 2, characterized in that, The quick-connect external thread connector (18) connects the manual reversing valve (16) and the water-resistant polyurethane hose (20), and the flow rate regulating valve (19) is responsible for regulating the flow rate of the compressed air and keeping the pressure difference before and after the flow rate constant.

8. The machining method for rapid milling of complex structure and shape profile parts as described in claim 2, characterized in that, The three-unit air source treatment assembly (10) is assembled from an air pressure regulating valve (21), a connecting frame (22), an air filter (23), and an oil mist lubricator (24); the two connecting frames (22) are respectively connected to the air pressure regulating valve (21), the air filter (23), and the oil mist lubricator (24).

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