Fixture and machining method of large-suspension-depth thin-wall shell

Abstract

The invention discloses a clamp and a machining method of a large-suspension-depth thin-wall shell. The clamp comprises a clamp head which is of an annular structure and is used for being arranged at the head end of a thin-wall shell to be machined in a sleeving mode; and the clamp body is fixedly connected with the clamp head, and the clamp body is of an arc-shaped plate-shaped structure and is used for clamping a shell body of the thin-wall shell to be machined. By means of the clamp, the head end and the shell body of the to-be-machined thin-wall shell can be accurately clamped, and the to-be-machined thin-wall shell cannot be damaged. The method comprises the steps that a to-be-machined thin-wall shell is clamped by a clamp; a staggered peeling type machining method is adopted, and the thin-wall shell to be machined is divided into a plurality of machining areas; a five-axis linkage machining center is adopted, rough machining, semi-finish machining and finish machining are conducted on each machining area, and the overhanging length of a cutter is controlled to be smaller than or equal to 65 mm in the machining process. According to the method, the machining efficiency is improved while the machining quality is guaranteed, and high-precision and high-efficiency machining is achieved.

Description

Technical Field

[0001] This invention relates to the field of mechanical manufacturing technology, and more specifically, to a method for processing a fixture and a thin-walled shell with large overhang depth. Background Technology

[0002] Thin-walled shell parts are widely used due to their advantages such as light weight and compact structure, but there are significant technical challenges in their processing: 1. Insufficient rigidity: Thin-walled parts with a wall thickness of only 1.5mm are prone to chattering under cutting forces, resulting in dimensional deviations. 2. Difficulty in controlling deformation: Uneven clamping force or accumulation of cutting heat can cause warping and deformation of the parts; 3. Long tool overhang: When the machining depth exceeds 162mm, the excessive tool overhang leads to a decrease in cutting stability and a deterioration in surface quality.

[0003] In existing technologies, when machining deep-cavity, thin-walled parts using a three-jaw chuck, the chuck strength is insufficient, easily causing deformation of the part after release, severely affecting machining accuracy. To address this issue, some domestic and international technologies have attempted to optimize tool parameters, improve machining paths, and change fixtures. However, due to the interplay of various factors, these measures have failed to fundamentally solve the stability and accuracy problems in machining deep, thin-walled parts. Therefore, there is an urgent need for a machining method that can achieve comprehensive improvements in process optimization and clamping technology to meet the machining requirements of highly complex parts. Summary of the Invention

[0004] This invention provides a method for machining a fixture and a thin-walled shell with large overhang, in order to solve the problems of part vibration, dimensional deviation and surface roughness caused by insufficient part rigidity, unstable clamping and excessive tool overhang in the prior art.

[0005] To achieve the above objectives, the present invention provides a clamp comprising: a clamp head, which is a ring-shaped structure for fitting onto the head end of a thin-walled shell to be processed; and a clamp body, which is fixedly connected to the clamp head and is an arc-shaped plate structure for clamping the shell body of the thin-walled shell to be processed.

[0006] Optionally, the outer diameter of the clamp head is at least 318 mm, and the inner diameter of the clamp head is at least 90 mm.

[0007] Optionally, the thickness of the clamp head is 20 mm.

[0008] Optionally, the length of the clamp head and the clamp body is 190mm.

[0009] Optionally, the clamp head and clamp body are made of high-strength alloy steel.

[0010] On the other hand, the present invention provides a method for machining a thin-walled shell with a large overhang, using the fixture described above. The method includes: S1, clamping the thin-walled shell to be machined with the fixture; S2, using an alternating peeling machining method to divide the thin-walled shell to be machined into multiple machining areas; S3, using a five-axis linkage machining center to perform roughing, semi-finishing and finishing on each machining area, while controlling the tool overhang length to be ≤65mm during the machining process.

[0011] Optionally, the tool tilt angle during machining can be 5° to 20°.

[0012] Optionally, S2 includes: dividing the outer surface of the thin-walled shell to be processed into processing area 1, processing area 3, processing area 5, processing area 7, and processing area 9 from top to bottom; and dividing the inner surface of the thin-walled shell to be processed into processing area 2, processing area 4, processing area 6, and processing area 8 from top to bottom; wherein the top of processing area 3 is on the same horizontal line as the center of processing area 2; the top of processing area 5 is on the same horizontal line as the center of processing area 4; the top of processing area 7 is on the same horizontal line as the center of processing area 6; and the top of processing area 9 is on the same horizontal line as the center of processing area 8.

[0013] Optionally, the tool tilt angle is 5° when machining areas 1, 2, 3, 4, and 5; and the tool tilt angle is 20° when machining areas 6, 7, 8, and 9.

[0014] The beneficial effects of this invention are: This invention provides a fixture and a method for machining a thin-walled shell with large overhang. The fixture includes: a fixture head, which is a ring-shaped structure for fitting onto the head end of the thin-walled shell to be machined; and a fixture body, fixedly connected to the fixture head, which is an arc-shaped plate structure for clamping the shell body of the thin-walled shell to be machined. This fixture allows for precise clamping of the head end and shell body of the thin-walled shell to be machined without damaging it. The method includes: clamping the thin-walled shell to be machined with the fixture; dividing the thin-walled shell to be machined into multiple machining areas using a staggered peeling machining method; and using a five-axis linkage machining center to perform roughing, semi-finishing, and finishing on each machining area, controlling the tool overhang length to be ≤65mm during machining. This method improves machining efficiency while ensuring machining quality, achieving high-precision and high-efficiency machining. Attached Figure Description

[0015] Figure 1 This is a side view of a clamp provided in an embodiment of the present invention; Figure 2 This is a perspective view of the thin-walled shell to be processed provided in an embodiment of the present invention; Figure 3 This is a flowchart of a processing method for a thin-walled shell with large overhang provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of the structure of multiple processing areas of the thin-walled shell to be processed provided in an embodiment of the present invention.

[0016] Symbol explanation: Fixture head-1, fixture body-2, thin-walled shell to be processed-3, processing area one-4, processing area two-5, processing area three-6, processing area four-7, processing area five-8, processing area six-9, processing area seven-10, processing area eight-11, processing area nine-12. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0018] Figure 1 This is a side view of a clamp provided in an embodiment of the present invention; Figure 2 This is a perspective view of the thin-walled shell 3 to be processed provided in an embodiment of the present invention; as shown... Figure 1 and Figure 2 As shown, the clamp includes: 1. A clamp head 1, which is a circular ring structure and is used to be fitted onto the head end of the thin-walled shell 3 to be processed; The clamping head 1 is designed as a ring structure, with its inner wall precision-machined to ensure a perfect match in size and shape with the head end of the thin-walled housing 3 to be machined. Specifically, its inner diameter is slightly larger than the outer diameter of the housing head end, facilitating installation and ensuring a tight fit during clamping. To improve positioning accuracy and overall clamping stability, the outer side of the clamping head 1 may be provided with several positioning bosses or grooves for mating with the clamping body 2, ensuring consistent relative position during multiple clamping processes. The clamping head 1 is typically made of high-strength alloy steel or equivalent high-rigidity material and undergoes heat treatment to obtain sufficient wear resistance and deformation resistance. Structurally, to accommodate the discharge of cutting fluid and machining chips during machining, the clamping head 1 may also be designed with through holes or chip removal grooves. This not only helps maintain the cleanliness of the machining area but also reduces stress concentration problems caused by localized chip accumulation.

[0019] 2. The clamp body 2 is fixedly connected to the clamp head 1. The clamp body 2 is an arc-shaped plate structure used to clamp the shell body of the thin-walled shell 3 to be processed.

[0020] The fixture body 2 is an arc-shaped plate structure, the curvature of which is customized according to the shape characteristics of the thin-walled shell 3 to be processed, ensuring that its inner contact surface is completely fitted with the outer surface of the shell. The fixture body 2 and the fixture head 1 are combined into one unit through a fixed connection, forming an integrated clamping system. The arc-shaped plate design allows the fixture body 2 to provide uniform clamping force along the curved surface of the shell, thereby avoiding thin-wall deformation caused by uneven local force. To accommodate different workpiece sizes or slight differences caused by machining tolerances, the fixture body 2 can adopt an adjustable design, for example, by setting adjustment bolts or sliding mechanisms, allowing fine adjustment of the contact surface position during clamping to ensure that sufficient and uniform clamping force is always applied. In addition, the inner surface of the fixture body 2 is also machined with high precision, so that the part in contact with the shell has a good surface finish, thereby reducing surface damage that may be caused by friction. The entire fixture system is designed with the vibration and impact generated during the machining process in mind. Through reasonable mechanical structure design and material selection, it not only ensures stable clamping of the workpiece, but also facilitates multiple precise positioning of the workpiece during high-precision machining.

[0021] This fixture structure, through the coordinated operation of the annular fixture head 1 and the arc-shaped plate fixture body 2, achieves precise clamping of the head end and body of the thin-walled shell 3 to be machined. This not only ensures the positioning accuracy and stability during the machining process, but also helps to effectively discharge cutting fluid and chips, thereby significantly improving machining accuracy and overall process stability.

[0022] In one optional embodiment, the outer diameter of the clamp head 1 is at least 318 mm, and the inner diameter of the clamp head 1 is at least 90 mm. The thickness of the clamp head 1 is 20 mm. The length of the clamp head 1 and the clamp body 2 is 190 mm.

[0023] The outer diameter of the clamping head 1 is at least 318 mm. This size ensures that the clamping head 1 has sufficient external support surface to evenly distribute clamping force during clamping. A larger outer diameter helps to improve the rigidity and deformation resistance of the overall structure, effectively resisting vibrations caused by cutting forces during machining. At the same time, an outer diameter of 318 mm or more also provides sufficient allowance for interference between the tool and the workpiece during machining, ensuring a safe and stable machining environment.

[0024] The inner diameter of the clamp head 1 is at least 90mm. A Φ90mm through hole is opened in the center of the clamp head 1. On the one hand, this can effectively reduce the weight of the clamp head itself, and on the other hand, it can make the stress more evenly distributed inside the structure, reducing the risk of deformation caused by local stress concentration.

[0025] The clamp head 1 has a thickness of 20mm. This thickness ensures sufficient structural strength without increasing processing difficulty or manufacturing costs due to excessive thickness. This thickness effectively resists deformation caused by vibration, impact, and localized stress concentration during processing. Furthermore, the appropriate thickness design helps achieve high-precision machining positioning and maintains dimensional stability and wear resistance during long-term use.

[0026] This fixture design, with its reasonable dimensional parameters—outer diameter 318mm, inner diameter 90mm, thickness 20mm, and total length 190mm—not only meets the requirements for stable clamping and positioning of workpieces in high-precision machining, but also exhibits significant advantages in vibration resistance, deformation resistance, and machining adaptability. These parameters were determined after comprehensively considering the machining process, workpiece dimensions, and the structural characteristics of the clamping system, ensuring efficient support during machining and providing reliable assurance for subsequent machining steps.

[0027] On the other hand, the present invention provides a method for processing a deep, thin-walled shell using the aforementioned fixture. Figure 3 This is a flowchart of a processing method for a large-depth thin-walled shell provided in an embodiment of the present invention, as shown below. Figure 3 As shown, the method includes: S1. Clamp the thin-walled shell 3 to be processed with the fixture; The thin-walled shell 3 to be processed is fixed by using the fixture described above (for example, a fixture head 1 with an outer diameter of Φ318mm, a thickness of 20mm, a total length of 190mm and a through hole of Φ90mm in the middle combined with the corresponding fixture body 2).

[0028] The fixture is designed to secure the workpiece firmly, ensuring that it does not shift or deform during subsequent machining. Especially for parts with a wall thickness of only 1.5mm and a machining depth exceeding 162mm, stable clamping significantly reduces vibration and stress concentration caused by cutting forces.

[0029] The fixture uses a circular chuck and an arc-shaped fixture body 2 to precisely clamp the head end and body of the housing respectively. At the same time, the Φ90mm through hole in the middle not only reduces the stress concentration of the fixture itself, but also provides a smooth channel for chip and cutting fluid to drain during internal machining, thereby improving the machining environment.

[0030] S2. Using an alternating peeling process, the thin-walled shell to be processed is divided into multiple processing areas. This step employs an alternating peeling process, dividing the overall thin-walled shell into multiple processing areas. These areas are typically divided based on the local wall thickness, surface shape, and processing depth of the workpiece.

[0031] The principle of area division: By dividing the workpiece into several smaller areas, each area can adopt a targeted processing strategy, so that the cutting amount is uniform and the cutting force is dispersed, reducing the local stress concentration caused by large-area processing at one time.

[0032] The staggered peeling process involves completing a semi-finishing of one area, followed immediately by finishing, and then using the same method to process adjacent areas. This alternating processing method helps to minimize vibration and deformation caused by excessive tool load during the overall machining process while ensuring machining efficiency.

[0033] By adopting partitioned processing, machining parameters (such as cutting speed, feed rate, and depth of cut) can be optimized for each region, achieving a balance between local accuracy and overall stability. At the same time, due to the smaller size of the region, the load on the tool in each region is lower, which helps to improve surface finish and dimensional accuracy.

[0034] In one optional implementation, Figure 4 This is a schematic diagram of the structure of multiple processing areas of the thin-walled shell 3 to be processed according to an embodiment of the present invention, as shown below. Figure 4 As shown, S2 includes: S21. Divide the outer surface of the thin-walled shell 3 to be processed into processing area 1, processing area 3, processing area 6, processing area 5, processing area 8, processing area 7, processing area 9, and processing area 9 from top to bottom. S22. Divide the inner surface of the thin-walled shell 3 to be processed into processing area 2 (5), processing area 4 (7), processing area 6 (9), and processing area 8 (11) from top to bottom. Among them, the top of processing area 3 6 is on the same horizontal line as the center of processing area 2 5; the top of processing area 5 8 is on the same horizontal line as the center of processing area 4 7; the top of processing area 7 10 is on the same horizontal line as the center of processing area 6 9; and the top of processing area 9 12 is on the same horizontal line as the center of processing area 8 11.

[0035] External Surface Zoning: The outer surface of the thin-walled shell 3 to be processed is divided into processing area 1 (4), processing area 3 (6), processing area 5 (8), processing area 7 (10), and processing area 9 (12) from top to bottom. These areas are divided based on the external curved surface shape, thickness variations, and different distributions affected by cutting forces. Zoning allows for localized processing, thereby reducing overall cutting forces and the risk of localized deformation.

[0036] Inner surface partitioning: The inner surface of the thin-walled shell 3 to be processed is divided into processing area 2 (5), processing area 4 (7), processing area 6 (9), and processing area 8 (11) from top to bottom. The partitioning of the inner surface areas mainly considers the processing depth of the inner cavity surface and the ease of tool entry, so as to achieve precise control for the special requirements of the inner wall.

[0037] To ensure coordinated processing of the inner and outer surfaces and smooth transitions between areas, this embodiment specifies the following alignment relationship: The top of processing area 3, 6 is on the same horizontal line as the center of processing area 2, 5; The top of processing area 5 (8) and the center of processing area 4 (7) are on the same horizontal line; The top of processing area 710 is on the same horizontal line as the center of processing area 69; The top of processing area 912 is on the same horizontal line as the center of processing area 811.

[0038] This design allows the machining areas of the outer and inner surfaces to overlap and transition in the longitudinal direction, ensuring that the tool travel and cutting path can be organically connected during machining on the inner and outer surfaces, and avoiding local machining errors caused by mismatch in the partitions.

[0039] In one optional implementation, the tool tilt angle is 5° to 20° during machining.

[0040] Specifically, the tool tilt angle is 5° when machining areas 1-4, 2-5, 3-6, 4-7, and 5-8; and the tool tilt angle is 20° when machining areas 6-9, 7-10, 8-11, and 9-12.

[0041] To further optimize machining parameters, this embodiment also proposes an optional solution: for machining areas 1 (4), 2 (5), 3 (6), 4 (7), and 5 (8), a smaller tool tilt angle of 5° is used during machining. This setting is mainly for the upper or weaker areas of the workpiece. Using a smaller tilt angle helps to reduce cutting forces, reduce vibration and thermal effects during machining, and ensure that the workpiece surface meets high-quality requirements.

[0042] For machining zones 6 (9), 7 (10), 8 (11), and 9 (12), a larger tool tilt angle of 20° is used. A larger tilt angle helps improve machining conditions when the tool enters deep cavity regions, increases cutting efficiency, ensures stable machining in deeper or more confined areas, and compensates for tool contact angle issues caused by deeper machining.

[0043] By using the above-mentioned zone and tilt angle differentiation settings, the following effects can be achieved: 1. Zoned machining makes the cutting conditions in each zone more balanced, reduces the amount of material removed in a single zone, and thus reduces workpiece deformation caused by excessive local cutting forces.

[0044] 2. The regional alignment design of the inner and outer surfaces ensures the coordination of machining on both sides, making the machining path transition smoothly and effectively improving the overall machining accuracy.

[0045] 3. Using a 5° tilt angle for the upper or vibration-prone areas can reduce vibration and tool load during cutting; while using a 20° tilt angle for deeper areas helps improve the efficiency and tool stability of deep cavity machining.

[0046] 4. The partitioning and differentiated tool tilt angle settings further optimize the cutting parameters, providing a more ideal machining state for the entire thin-walled shell, thereby significantly improving the surface finish and dimensional accuracy after machining.

[0047] S3. A five-axis linkage machining center is used to perform roughing, semi-finishing and finishing on each machining area. During the machining process, the tool overhang length is controlled to be ≤65mm.

[0048] In a five-axis machining center, the following three processes are performed sequentially on each of the above machining areas: roughing: Using appropriate cutting tools (such as Φ10 ball end mills or other suitable tools), a large area of ​​material is removed from the current machining area to form the preliminary geometry of the workpiece.

[0049] During the roughing stage, a certain allowance (e.g., about 2mm allowance) is reserved to compensate for machining errors in subsequent semi-finishing and finishing processes.

[0050] Semi-finished: Based on rough machining, the current machining area is semi-finished using five-axis linkage technology. At this time, the machining allowance is reduced to 0.5mm, further improving the local shape and size of the workpiece.

[0051] During the semi-finishing process, by optimizing the tool path and machining parameters, the cutting force is distributed smoothly, and tool vibration is controlled, laying a stable foundation for finishing.

[0052] finishing: On the semi-finished workpiece, the finishing process is used to perform final processing on the current processing area, gradually removing the remaining material to achieve the geometric accuracy and surface finish required by the design.

[0053] The finishing process uses a staggered peeling method to remove material layer by layer, ensuring that the force on the workpiece is evenly distributed during each cutting process, thereby reducing the risk of local stress concentration and processing vibration.

[0054] Furthermore, throughout the entire five-axis machining process, the tool overhang length is strictly controlled to within 65mm. A shorter tool overhang effectively improves cutting stability, reduces the risk of bending deformation or vibration caused by a long overhang, and ensures high-precision machining and surface quality in all areas during the process. This control requirement is particularly important for deep-cavity and thin-walled workpieces, as a longer tool overhang can easily lead to a decrease in tool rigidity, thereby affecting the workpiece machining accuracy.

[0055] In one optional implementation, the cutting fluid is cooled under high pressure during machining, with a pressure ≥5MPa, to ensure smooth chip removal.

[0056] In one optional implementation, dimensional inspection is performed after machining, with a tolerance of ±0.05 mm and a surface roughness Ra≤1.6 μm.

[0057] This machining method provides a comprehensive solution to the challenging problem of machining thin-walled shells with large overhangs. It involves securely clamping the thin-walled shell 3 in a fixture, employing a staggered peeling process to divide the shell 3 into sections, and performing roughing, semi-finishing, and finishing in these sections on a five-axis machining center. Simultaneously, it strictly controls the tool overhang length. The entire process ensures both clamping stability and workpiece accuracy during machining, while effectively reducing cutting forces and vibration risks through layer-by-layer machining, thus improving production efficiency while ensuring high machining quality. This method is particularly suitable for machining irregularly shaped shells with extremely thin walls, large depths, and high machining difficulty, offering significant technical advantages and broad application prospects.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A clamp, characterized in that, include: A clamping head, which has a circular structure, is used to be fitted onto the head end of the thin-walled shell to be processed; The clamp body is fixedly connected to the clamp head. The clamp body is an arc-shaped plate structure used to clamp the shell body of the thin-walled shell to be processed.

2. The clamp according to claim 1, characterized in that: The outer diameter of the clamp head is at least 318 mm, and the inner diameter of the clamp head is at least 90 mm.

3. The clamp according to claim 1, characterized in that: The thickness of the clamp head is 20mm.

4. The clamp according to claim 1, characterized in that: The length of the clamp head and the clamp body is 190mm.

5. The clamp according to claim 1, characterized in that: The clamp head and clamp body are made of high-strength alloy steel.

6. A method for processing a thin-walled shell with large overhang, using the fixture described in any one of claims 1-5, the method comprising: S1. Clamp the thin-walled shell to be processed using the fixture; S2. The thin-walled shell to be processed is divided into multiple processing areas using an alternating peeling process. S3. A five-axis linkage machining center is used to perform roughing, semi-finishing and finishing on each machining area. During the machining process, the tool overhang length is controlled to be ≤65mm.

7. The method according to claim 6, characterized in that: The tool tilt angle during machining is 5°~20°.

8. The method according to claim 6, characterized in that, S2 includes: The outer surface of the thin-walled shell to be processed is divided into processing area 1, processing area 3, processing area 5, processing area 7, and processing area 9 from top to bottom; The inner surface of the thin-walled shell to be processed is divided into processing area 2, processing area 4, processing area 6, and processing area 8 from top to bottom; Among them, the top of processing area 3 is on the same horizontal line as the center of processing area 2; the top of processing area 5 is on the same horizontal line as the center of processing area 4; the top of processing area 7 is on the same horizontal line as the center of processing area 6; and the top of processing area 9 is on the same horizontal line as the center of processing area 8.

9. The method according to claim 7, characterized in that: During machining in machining areas 1, 2, 3, 4, and 5, the tool tilt angle is 5°. During machining in machining areas six, seven, eight, and nine, the tool tilt angle is 20°.

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