CN112453829A - Method for accurately machining variable-curvature C-shaped aviation sheet metal part - Google Patents
Method for accurately machining variable-curvature C-shaped aviation sheet metal part Download PDFInfo
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- CN112453829A CN112453829A CN202011001080.4A CN202011001080A CN112453829A CN 112453829 A CN112453829 A CN 112453829A CN 202011001080 A CN202011001080 A CN 202011001080A CN 112453829 A CN112453829 A CN 112453829A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23P—METAL-WORKING NOT OTHERWISE PROVIDED FOR; COMBINED OPERATIONS; UNIVERSAL MACHINE TOOLS
- B23P15/00—Making specific metal objects by operations not covered by a single other subclass or a group in this subclass
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Abstract
The invention discloses a variable-curvature C-shaped aviation sheet metal part accurate machining method, and belongs to the field of part machining and manufacturing. The processing method comprises the steps of 1) spreading the wool; 2) processing of wool; 3) bending and forming; 4) roll bending and forming; 5) quenching treatment; 6) correcting stretch bending; 7) the clamping ends are removed. The processing method is particularly suitable for forming and processing the C-shaped aviation sheet metal part with local thinning, roll bending forming is adopted for performing preforming and springback compensation before stretch bending correction, only compensation drawing is needed during stretch bending, the internal stress of the formed part is small, and the die attaching effect is good.
Description
Technical Field
The invention relates to the field of machining and manufacturing, in particular to a method for accurately machining a variable-curvature C-shaped aviation sheet metal part.
Background
Aviation sheet metal parts mainly use aluminum alloy as a main part, and because the requirements on the strength, rigidity and the like of the part performance are higher, the aviation sheet metal parts are more difficult to process compared with aluminum alloys in other industries such as automobiles. Aviation aluminum alloy sheet metal parts are divided into plates, profiles and pipes according to material types, wherein the sheet metal parts of the plate types are mainly divided into skin/wall plate type parts used for the exterior of an airplane and structural parts used for the interior. In order to meet the flight performance of the airplane, the structural sheet metal part of the internal support not only meets the performance requirements of the structure but also meets the assembly requirements of the airplane, so that the aviation sheet metal part is various and complex in shape. The variable-curvature C-shaped aviation sheet metal component is mainly used for supporting an aircraft outer skin part, the shape of the variable-curvature C-shaped aviation sheet metal component is changed along with the appearance of an aircraft, the curvature is not fixed, and meanwhile, the variable-curvature C-shaped aviation sheet metal component is designed to be C-shaped in order to guarantee the supporting strength and rigidity requirements of the part. The lightweight is the subject of eternal invariance in the field of aviation, and in order to improve the performances of the aircraft such as flight economy, operational indexes and the like, most parts need to be subjected to weight reduction treatment, and common treatment methods include local thinning or application of novel composite materials and the like. In consideration of manufacturability and economy of part manufacturing, the variable-curvature C-shaped aviation sheet metal component adopts a weight reduction treatment mode of local thinning, the typical part shape is as shown in figure 1, a large-curvature corner is arranged at the bottom end of the part, curvatures of all areas are different, the middle part of a web plate surface is divided into different thicknesses by taking a boundary, the heights of the bent edges at two sides are equal, and the whole part is longer (generally more than 1000 m).
Because the part is the variable camber, all parts kick-backs inequality after the shaping, and the uneven condition such as the internal stress of material that leads to the part thickness inequality in addition for the part is difficult to laminating the mould after shaping, needs a large amount of manual correction work. In order to ensure the strength of the parts, the aviation aluminum alloy parts also need to be quenched, and the parts are deformed after quenching and need to be corrected manually for the second time. The general 0.5mm of appearance precision of aviation sheet metal part, because the precision of this type of taking shape is difficult to guarantee, the part can't carry out accurate unloading before taking shape, need carry out manual truing appearance after correcting the completion, the pruning degree of difficulty is big, the precision is poor, inefficiency.
Disclosure of Invention
Aiming at the conditions of multiple processing technological processes, low efficiency, poor precision and large manual correction value of a variable-curvature C-shaped aviation sheet metal part (particularly a type with local thinning), the invention provides a method for realizing the accurate processing of the part, which replaces the original manual work with mechanical processing and improves the processing efficiency and quality of the part.
The purpose of the invention is realized by the following technical scheme:
the precise machining method for the variable-curvature C-shaped aviation sheet metal part is characterized by comprising the following steps of:
step S1, spreading the wool: directly measuring the length of a milling line or an arc surface back ridge line of the part in a three-dimensional digital-analog model, and constructing a straight strip-shaped three-dimensional process model I according to the section and the measured length of the part; respectively adding clamping end allowance at two ends of the three-dimensional process model I to generate a three-dimensional process model II; expanding the three-dimensional process model II and converting the three-dimensional process model II into a two-dimensional blanking digital model;
step S2, wool processing: milling the shape of the blank and the thickness of the milled material on a numerical control machine according to a blanking digital model;
step S3, bending and forming: bending on a bending machine to form two side bent edges, wherein the formed shape is consistent with the three-dimensional process model II;
step S4, roll bending and forming: controlling the bending curvature of the roll bending preforming by controlling the position of the roller through a numerical control program; comparing the formed part according to the theoretical bending curvature of the part, and correcting roll bending processing parameters according to the forming condition of the part until the processing requirements are met;
step S5: quenching treatment: quenching the parts subjected to roll bending forming according to the process specification requirements;
step S6: and (3) stretch bending of parts: placing the quenched part on a stretch bending machine, and performing stretch bending through a stretch bending die;
step S7: removing the clamping end: and removing the allowance of the clamping ends added at the two ends of the part to achieve the theoretical appearance of the part.
Furthermore, the part needs to be subjected to stretch bending within 30min after quenching is finished.
Furthermore, the unilateral clearance of the stretch bending die is 0.4mm, and two ends of the stretch bending die are respectively provided with a pressing device.
Furthermore, the stretching amount of the part in the stretch bending process is 1.5-3%.
The beneficial effects of this technical scheme are as follows:
1. according to the invention, through a reasonable process flow, an excellent processing scheme is formulated, the processing process is simple, so that the method has a very high fault tolerance rate, the requirements on the operation skills and the equipment precision of workers are not high, any evidence obtaining worker can process on the existing conventional equipment, the full-mechanized processing of the C-shaped sheet metal part is realized, the manual work of the workers is greatly reduced, the labor intensity of the workers is reduced, the parts are unfolded by adopting a digital model, and the parts are not corrected or trimmed after being processed, so that the accurate processing is realized; the processing efficiency and quality of parts are greatly improved;
2. the processing method provided by the invention is based on the concept of 'soft resilience', adopts roll bending forming before a stretch bending process, provides a low-cost and quick technological parameter acquisition method, has certain flexibility, can adapt to the defect of large performance difference of aviation aluminum alloy materials, and realizes accurate processing of the parts;
3. according to the processing method, the processing fault tolerance rate is improved by adopting stretch bending correction, due to slight differences of different batches of material performance, part quenching clamping modes, water entering directions and the like, the curvature of the parts after roll bending forming is inconsistent, the parts are slightly different due to coupling factors of different degrees of quenching deformation and the like, the forming defects can be corrected by adjusting stretch bending parameters, the condition of repeatedly correcting roll bending forming processing parameters is avoided, and the working strength and difficulty are greatly reduced.
Drawings
The foregoing and following detailed description of the invention will be apparent when read in conjunction with the following drawings, in which:
FIG. 1 is a schematic view of a typical variable curvature C-type aerospace sheet metal part, with the right side (b) of the figure being an end sectional view;
FIG. 2 is a flow chart of the precise machining process of the variable-curvature C-shaped aviation sheet metal part;
FIG. 3 is a partial schematic view of a variable curvature C-type aerospace sheet metal part;
FIG. 4 is a schematic diagram of a three-dimensional process model II;
FIG. 5 is a blanking digifax of an expanded batt with the milling face facing upward;
FIG. 6 is a schematic view of roll-forming;
FIG. 7 is a schematic view of a stretch bending die;
FIG. 8 is a schematic cross-sectional view of a stretch bending die;
in the figure:
1. a dorsal ridge line; 2. milling a line; 3. milling a region; 4. a roller; 5. a part; 6. A cover plate; 7. the die body, 8, the bottom plate, 9, the pressing mechanism, 10 and the thinning area.
Detailed Description
The technical solutions for achieving the objects of the present invention are further illustrated by the following specific examples, and it should be noted that the technical solutions claimed in the present invention include, but are not limited to, the following examples.
The embodiment discloses an accurate machining method for a variable-curvature C-shaped aviation sheet metal part, aiming at the variable-curvature C-shaped aviation sheet metal part (particularly a type with local thinning), the original manual manufacturing is replaced by machining, and the machining efficiency and the quality of a part 5 are improved.
Please refer to fig. 1, which is a schematic diagram of a typical variable curvature C-type aviation sheet metal part. Referring to fig. 2, the implementation process of the method mainly includes seven steps: firstly, spreading woollen; secondly, processing the rough material; thirdly, bending and forming; fourthly, roll bending forming; fifthly, quenching treatment; sixthly, bending correction is carried out; and seventhly, removing the clamping end.
Step one, spreading the wool
The size of the rough material affects the whole processing process flow of the part 5, the step is of great importance, the key elements of the step are that the size in the length direction is not required to be accurate (because the allowance of a clamping end needs to be added), the size in the width direction is required to be accurate (the size accuracy of the height of a bent edge is affected), and the implementation process is as follows: in the rough material unfolding stage, as shown in fig. 3, measuring the lengths of a back ridge line 1 and a milling line 2 of a part 5, constructing a three-dimensional process model I according to the cross section of the end face on the right side of the part 1 and the measured lengths, and increasing the allowance of clamping ends of 150-300 mm on the basis of the three-dimensional process model I, so as to generate a three-dimensional process model II shown in fig. 4; and then expanding the three-dimensional process model II to generate a two-dimensional blanking digital model shown in figure 5, and marking a milling line 2, a milling surface and a milling area 3. This step ensures accurate blanking of the part 5 before forming.
Step two, processing the rough material
And (4) processing the blank in a three-axis numerical control milling machine according to the blanking digifax in the step one, milling the shape of the blank and milling the thickness of the material.
Step three, bending and forming
And bending and forming are carried out on a bending machine to form two side bent edges, and the blank shape of the formed part 5 is consistent with that of the three-dimensional process model II shown in the figure 4.
Step four, roll bending forming
This step is critical to the precise formation of the part 5. Due to the characteristics of variable curvature, unequal thickness and the like of the part 5, the rebound generated in the subsequent stretch-bending forming process is difficult to accurately predict and compensate. Even if the springback correction is carried out after a large number of tests, due to the difference of the properties of each batch of materials, the springback needs to be corrected again when the next batch of parts 5 are processed, which wastes time and labor and has poor effect. If the part 5 is preformed and subjected to springback compensation before stretch bending, only compensation drawing is needed during stretch bending (namely, the compensation is only equivalent to stretch bending correction), so that the formed part 5 has small internal stress and good die attaching effect. Based on the idea of the "preforming and springback correction", the method of the "soft forming and springback correction" is adopted, and the forming and springback correction of the part 5 is realized without using a die. As shown in fig. 6, this step is implemented as follows:
1) controlling the bending curvature of the roll bending preforming by controlling the position of the roller 4 through a numerical control program;
2) according to the theoretical bending curvature ratio of the part 5, correcting roll bending processing parameters according to the forming condition of the formed part 5 until the processing requirements are met;
3) and (3) solidifying roll bending processing parameters, and facilitating the roll bending forming of the subsequent part 5 blank.
Step five, quenching treatment: and quenching the roll-formed part 5 according to the process specification requirement.
Sixthly, correcting the stretch bending
Compared with roll bending forming/correction, stretch bending correction has very excellent fault tolerance rate. Due to slight differences of different batches of materials in performance, quenching clamping modes of the parts 5, water entering directions and the like, curvature of the parts 5 after roll bending forming is inconsistent, quenching deformation in different degrees and the like are slightly different, the forming defects can be corrected by adjusting stretch bending parameters, the condition of repeatedly correcting roll bending forming processing parameters is avoided, and working strength and difficulty are greatly reduced.
Performing stretch bending correction on a stretch bending die as shown in FIGS. 7-8, wherein the part 5 needs to be subjected to stretch bending within 30min after quenching is completed;
the stretch bending die comprises a cover plate 6, a die body 7, a bottom plate 8 and a pressing mechanism 9. As shown in fig. 8, which is a schematic cross-sectional view of a stretch bending die, a single-side gap of the stretch bending die is 0.4mm (i.e., a gap between components 6 and 7 in fig. 8, and a gap between components 7 and 8 is δ +0.4 mm), and two end heads are additionally provided with pressing mechanisms 9; the stretch bending parameters are adjusted according to the die attaching condition, and the compensation stretch amount is generally 1.5-3%.
Step seven, removing the clamping end
And removing the allowance of the clamping ends added by the two end heads to reach the theoretical appearance of the part 5.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention in any way, and all simple modifications and equivalent variations of the above embodiments according to the technical spirit of the present invention are included in the scope of the present invention.
Claims (4)
1. The precise machining method for the variable-curvature C-shaped aviation sheet metal part is characterized by comprising the following steps of:
step S1, spreading the wool: directly measuring the length of a milling line or an arc surface back ridge line of the part in a three-dimensional digital-analog model, and constructing a straight strip-shaped three-dimensional process model I according to the section and the measured length of the part; respectively adding clamping end allowance at two ends of the three-dimensional process model I to generate a three-dimensional process model II; expanding the three-dimensional process model II and converting the three-dimensional process model II into a two-dimensional blanking digital model;
step S2, wool processing: milling the shape of the blank and the thickness of the milled material on a numerical control machine according to a blanking digital model;
step S3, bending and forming: bending on a bending machine to form two side bent edges, wherein the formed shape is consistent with the three-dimensional process model II;
step S4, roll bending and forming: controlling the bending curvature of the roll bending preforming by controlling the position of the roller through a numerical control program; comparing the formed part according to the theoretical bending curvature of the part, and correcting roll bending processing parameters according to the forming condition of the part until the processing requirements are met;
step S5: quenching treatment: quenching the parts subjected to roll bending forming according to the process specification requirements;
step S6: and (3) stretch bending of parts: placing the quenched part on a stretch bending machine, and performing stretch bending through a stretch bending die;
step S7: removing the clamping end: and removing the allowance of the clamping ends added at the two ends of the part to achieve the theoretical appearance of the part.
2. The method for precisely machining the variable-curvature C-shaped aviation sheet metal part as claimed in claim 1, wherein in the step S6, the part needs to be subjected to stretch bending within 30min after quenching.
3. The method for accurately machining the variable-curvature C-shaped aviation sheet metal part according to claim 2, wherein in the step S6, the single-side gap of the stretch bending die is 0.4mm, and two ends of the stretch bending die are respectively provided with a pressing device.
4. The method for accurately machining the variable-curvature C-shaped aviation sheet metal part as claimed in claim 3, wherein in the step S6, the part stretching amount in the stretch bending process is 1.5% -3%.
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113059322A (en) * | 2021-03-26 | 2021-07-02 | 陕西飞机工业有限责任公司 | Variable-thickness frame edge processing method |
| CN113714735A (en) * | 2021-07-30 | 2021-11-30 | 江西昌河航空工业有限公司 | Auxiliary method suitable for controlling heat treatment deformation of large aluminum alloy plate |
| CN114154926A (en) * | 2021-11-22 | 2022-03-08 | 成都飞机工业（集团）有限责任公司 | Intelligent logistics system and method suitable for sheet metal part manufacturing |
| CN114986174A (en) * | 2022-04-29 | 2022-09-02 | 沈阳飞机工业（集团）有限公司 | Processing die and processing method for ultra-long variable-curvature special-shaped section part |
| CN115090733A (en) * | 2022-07-08 | 2022-09-23 | 江西洪都航空工业集团有限责任公司 | Forming method and positioning machining method of cabin door sealing frame type part |
| WO2024093248A1 (en) * | 2022-10-31 | 2024-05-10 | 天津航天长征火箭制造有限公司 | Roll-bending forming method for hollow inequilateral profile frame |
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Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113059322A (en) * | 2021-03-26 | 2021-07-02 | 陕西飞机工业有限责任公司 | Variable-thickness frame edge processing method |
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| CN114986174A (en) * | 2022-04-29 | 2022-09-02 | 沈阳飞机工业（集团）有限公司 | Processing die and processing method for ultra-long variable-curvature special-shaped section part |
| CN114986174B (en) * | 2022-04-29 | 2024-03-08 | 沈阳飞机工业（集团）有限公司 | Machining die and machining method for ultralong variable-curvature special-shaped profile part |
| CN115090733A (en) * | 2022-07-08 | 2022-09-23 | 江西洪都航空工业集团有限责任公司 | Forming method and positioning machining method of cabin door sealing frame type part |
| WO2024093248A1 (en) * | 2022-10-31 | 2024-05-10 | 天津航天长征火箭制造有限公司 | Roll-bending forming method for hollow inequilateral profile frame |
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Application publication date: 20210309 |