Machining method for multi-rib-groove structure complex thin-wall special-shaped cavity part

Abstract

The invention relates to a machining method for a multi-rib-groove structure complex thin-wall special-shaped cavity part. The problem that in the prior art, precision machining of inner cavity rib grooves, outer wall rib groove root angles and thin wall uniform thickness of a large complex thin-wall cavity is difficult to achieve is solved. Comprising the following steps: 1) electrode design; 2) tool design; (3) workpiece pretreatment and clamping; 4) electrode installation; 5) verifying the processing track; (6) processing parameter selection; and 7) detecting and evaluating the processing process. Aiming at thin-wall part machining and part machining with the high wall thickness uniformity requirement, the scheme that the electric spark machining technology is combined with the combined electrode is adopted, and the machining method has the beneficial effects that high-precision machining is achieved, deformation or damage is reduced, and the accessibility is good.

Description

Technical Field

[0001] This patent relates to a method for processing complex thin-walled special-shaped cavity parts with multiple rib and groove structures, and belongs to the technical field of processing complex thin-walled cavity parts. Background Art

[0002] With the rapid development of additive manufacturing technology, its application in the design and manufacturing of large thin-walled complex structural parts is becoming more and more extensive. Additive manufacturing technology has advantages in overall manufacturing and thin-wall manufacturing with its unique additive molding method, which makes it possible for complex structural parts that are difficult to process. However, with the increase in the complexity of parts, it is difficult for additive manufacturing to meet the design requirements in terms of thin-wall thickness uniformity, surface finish and dimensional accuracy, which poses many challenges to subsequent precision processing. In particular, for large-scale, multi-rib groove structure, complex and irregular thin-wall cavity parts, they are large in size and have complex rib groove structure layout, which requires high requirements for the root fillet and wall thickness uniformity of the processed rib groove. Such parts are widely used in high-end manufacturing fields such as aviation, aerospace, and automobiles, but their manufacturing difficulty is also relatively high. Due to the properties of the rib groove structure in the narrow space inside or outside the cavity, traditional mechanical processing methods have poor accessibility and cannot complete the processing. Summary of the invention

[0003] The present invention solves the problem of precise machining of inner cavity rib grooves, outer wall rib groove root angles, and uniform thickness of thin walls of large complex thin-wall cavities which are difficult to achieve in the prior art by providing a machining method for complex thin-walled special-shaped cavity parts with multiple rib groove structures.

[0004] The present invention is achieved by the following technical solutions:

[0005] A method for processing a thin-walled, irregular-shaped cavity-type part with a complex multi-rib groove structure, comprising:

[0006] 1) Electrode design: According to the three-dimensional model of multi-rib groove thin-walled structural parts, the required processing area and size of each rib groove structure are selected, and a dedicated electrode unit is designed for each rib groove structure. The shape of the electrode unit matches the rib groove structure to ensure the overlapping relationship between the split electrodes; the material of the electrode unit is mostly made of materials with good conductivity such as copper or graphite, and each electrode processing trajectory is simulated to perform effective avoidance and processing accessibility design;

[0007] 2) Tooling design: Multiple electrodes use the same type of electrode tooling. The tooling design principle should avoid the part body to prevent interference between the machine tool spindle and the part;

[0008] The electrode is connected and installed with the tooling through screws, and the tooling is connected to the machine tool through the machine tool's reference quick-change fixture; after each electrode is installed, the electrode reference surface is pulled to ensure accurate relative position with the machine tool's XYZ axis;

[0009] 3) Processing process

[0010] a) Workpiece pretreatment and clamping: Clean and wipe the parts after additive manufacturing to ensure the cleanliness and flatness of the processed surface and the cleanliness of the bottom reference surface; at the same time, clean the machine tool workbench, comprehensively consider the processing range, choose a reasonable position, align according to the part reference, and use the tooling to press the parts;

[0011] b) Electrode installation: Install the designed electrode unit on the electrode fixture in a predetermined order and posture, accurately position the electrode through the electrode reference surface to ensure the relative position accuracy between the electrode and the part, and place the reference for electrode loss detection on the machine tool workbench;

[0012] c) Processing trajectory verification: Use the electrode trajectory of computer-aided simulation to compile the processing program. After the machine tool positioning is completed, actual dry run processing is performed to verify the accuracy and feasibility of the program trajectory;

[0013] d) Processing parameter selection: According to the material, thickness and processing accuracy requirements of the parts, optimize the processing parameters of the EDM machine tool, including discharge pulse width, pulse interval, voltage, current, processing speed, etc., and finally realize the processing;

[0014] e) Process inspection and evaluation: After each electrode is processed, replace the reference quick-change fixture, use the standard ball to detect whether the processed wall thickness meets the requirements, and determine whether the processing is in place based on the size of the allowance.

[0015] The present invention aims at machining thin-walled parts with high requirements for wall thickness uniformity, and adopts the scheme of combining electric spark machining technology with combined electrodes, which has the beneficial effects of high-precision machining, reduced deformation or damage, good accessibility, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is an isometric view of the combined electrode design of the present invention;

[0017] Figure 2 This is a disassembled diagram of electrodes in a specific embodiment of the present invention, in which the serial numbers represent 22 different electrodes;

[0018] Figure 3 It is a schematic diagram of electrode processing of the present invention;

[0019] Figure 4 It is the installation diagram of the electrode and tooling of the present invention. DETAILED DESCRIPTION

[0020] In order to solve the problem of weak rigidity and high machining accuracy of complex rib-groove thin-walled parts manufactured by additive manufacturing, the present invention proposes a non-contact and macro-force-free precision electrospark machining method, which effectively solves the problem of cutting deformation during mechanical machining.

[0021] Aiming at the problem of narrow space, inner corner fillet characteristics of rib groove, uniform wall thickness and poor machining accessibility, we designed tooling and multiple split electrodes, and completed the machining of rib grooves with poor accessibility through the split electrode method and ingenious trajectory movement.

[0022] The multi-ribbed and grooved structured thin-walled irregular cavity parts are additively manufactured parts. They are large in size and consist of many ribbed grooves and thin walls. The thickness of the thin wall after additive processing is uneven, and the fillet size of the rib groove root varies, which cannot meet the design accuracy requirements. Due to the narrow position of the rib groove and the weak rigidity of the thin wall, the accessibility of mechanical processing is poor. Therefore, the combination of multiple split electrodes or local fillet electrode processing can meet the requirements.

[0023] The present invention will be further described below in conjunction with the accompanying drawings:

[0024] like Figure 1-4 As shown, the present invention is a processing method for a multi-rib-groove structured, complex, thin-walled, and irregular cavity-type part, specifically comprising:

[0025] 1) Electrode design. According to the three-dimensional model of multi-rib groove thin-walled structural parts, select the required processing area and size of each rib groove structure. Design a dedicated electrode unit for each rib groove structure, not only to ensure that the shape of the electrode unit matches the rib groove structure, but also to ensure the overlap relationship between the split electrodes ( Figure 1 , Figure 2 The electrode unit is made of materials with good conductivity such as copper or graphite. According to the distribution and processing sequence of the rib-groove structure on this part, a total of 11 pairs of 22 split electrodes are designed ( Figure 2 ), and simulate each electrode processing trajectory to effectively avoid and ensure processing accessibility.

[0026] 2) Tooling design. The workpiece is placed on the workbench of the four-axis linkage EDM forming machine with the bottom surface as the reference, and the center is pressed by the pressure plate to achieve stable clamping of the workpiece. For the convenience of common use, multiple electrodes use the same type of electrode tooling, such as Figure 3 , Figure 4 The tooling design principle should avoid the part body to prevent the machine tool spindle from interfering with the part;

[0027] The electrode is connected to the tooling through screws and installed, and the tooling is then connected to the machine tool using the machine tool's reference quick-change fixture; after each electrode is installed, the electrode reference surface must be pulled to ensure accurate relative position with the machine tool's XYZ axis.

[0028] 3) Processing process

[0029] a) Workpiece pretreatment and clamping: Perform necessary pretreatment such as cleaning and wiping on the parts after additive manufacturing to ensure the cleanliness and flatness of the processed surface and the cleanliness of the bottom reference surface. At the same time, clean the machine tool table, consider the processing range comprehensively, choose a reasonable position, align according to the part reference, and use the tooling to press the part tightly.

[0030] b) Electrode installation: Install the designed electrode unit on the electrode fixture in a predetermined order and posture. Through the precise positioning of the electrode reference surface, ensure the relative position accuracy between the electrode and the part, and place the reference for electrode wear detection on the machine tool workbench.

[0031] c) Processing trajectory verification: Use computer-aided simulation of the electrode trajectory to compile a processing program. After the machine tool is positioned, actual dry run processing is performed to verify the accuracy and feasibility of the program trajectory.

[0032] d) Processing parameter selection: According to the material, thickness, processing accuracy and other requirements of the aluminum alloy of the part, the processing parameters of the EDM machine tool are optimized, including discharge pulse width, pulse interval, voltage, current, processing speed, etc., and finally the processing is realized.

[0033] e) Process inspection and evaluation: After each electrode is processed, the reference quick-change fixture is replaced, and the standard ball is used to detect whether the processing wall thickness meets the requirements, and whether the processing is in place is determined based on the size of the allowance.

[0034] The present invention aims at machining thin-walled parts with high requirements for wall thickness uniformity, and adopts the scheme of combining electric spark machining technology with combined electrodes, which can bring the following beneficial effects:

[0035] 1) Precision machining of the rib groove root in a narrow space

[0036] The EDM technology itself has the characteristics of high precision. By optimizing the pulse power supply parameters and adopting precise control system for precise discharge control, it can better guarantee the uniformity of wall thickness.

[0037] 2) Reduce deformation and damage

[0038] Compared with traditional machining methods, the EDM process has no macro-cutting force, which helps to reduce the deformation or damage of thin-walled parts during machining and maintain the stability of their shape and size.

[0039] 3) Flexibility and accessibility solve the inaccessibility of traditional processing

[0040] The split electrode design provides greater flexibility and accessibility, making it possible to process complex shapes and hard-to-reach areas. For thin-walled parts, this means that more complex shapes and structures can be achieved while maintaining high precision.

[0041] These advantages make this solution have broad application prospects and market potential in the field of high-end aerospace manufacturing for thin-walled, multi-ribbed and grooved complex parts.

Claims

1. A method for processing parts with complex thin-walled and irregular shaped cavities with multiple ribs and grooves, characterized by: include: 1) Electrode design: According to the three-dimensional model of multi-rib groove thin-walled structural parts, the required processing area and size of each rib groove structure are selected, and a dedicated electrode unit is designed for each rib groove structure. The shape of the electrode unit matches the rib groove structure to ensure the overlap relationship between the split electrodes; Simulate each electrode processing trajectory to perform effective avoidance and processing accessibility design; 2) Tooling design: Multiple electrodes use the same type of electrode tooling. The tooling design principle should avoid the part body to prevent interference between the machine tool spindle and the part; The electrode is connected and installed with the tooling through screws, and the tooling is connected to the machine tool through the machine tool's reference quick-change fixture; after each electrode is installed, the electrode reference surface is pulled to ensure accurate relative position with the machine tool's XYZ axis; 3) Processing process a) Workpiece pretreatment and clamping: Clean and wipe the parts after additive manufacturing to ensure the cleanliness and flatness of the processed surface and the cleanliness of the bottom reference surface; at the same time, clean the machine tool workbench, comprehensively consider the processing range, choose a reasonable position, align according to the part reference, and use the tooling to press the parts; b) Electrode installation: Install the designed electrode unit on the electrode fixture in a predetermined order and posture, accurately position the electrode through the electrode reference surface to ensure the relative position accuracy between the electrode and the part, and place the reference for electrode loss detection on the machine tool workbench; c) Processing trajectory verification: Use the electrode trajectory of computer-aided simulation to compile the processing program. After the machine tool positioning is completed, actual dry run processing is performed to verify the accuracy and feasibility of the program trajectory; d) Processing parameter selection: According to the material, thickness and processing accuracy requirements of the parts, optimize the processing parameters of the EDM machine tool and finally realize the processing; e) Process inspection and evaluation: After each electrode is processed, replace the reference quick-change fixture, use the standard ball to detect whether the processed wall thickness meets the requirements, and determine whether the processing is in place based on the size of the allowance.

2. According to claim 1, a method for processing a multi-rib-groove structured, complex, thin-walled, and irregular cavity-like part, characterized in that: The electrode unit is made of copper or graphite.

3. The method for processing a multi-rib-groove structured, complex, thin-walled, irregular-shaped cavity-type part according to claim 1, characterized in that: The optimization of EDM machine tool processing parameters includes discharge pulse width, pulse interval, voltage, current and processing speed.

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