CN109623265B - Precise machining method for complex thin-wall variable-thickness large opening cover - Google Patents
Precise machining method for complex thin-wall variable-thickness large opening cover Download PDFInfo
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- CN109623265B CN109623265B CN201811333710.0A CN201811333710A CN109623265B CN 109623265 B CN109623265 B CN 109623265B CN 201811333710 A CN201811333710 A CN 201811333710A CN 109623265 B CN109623265 B CN 109623265B
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- B—PERFORMING OPERATIONS; TRANSPORTING
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- 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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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
- C23F1/00—Etching metallic material by chemical means
- C23F1/02—Local etching
- C23F1/04—Chemical milling
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Abstract
The invention discloses a precise processing method of a complex thin-wall variable-thickness large opening cover, which comprises the following steps: according to the geometric parameters of the large opening cover, simulating flattening and calculating a minimum blank; designing and manufacturing a tool concave-convex die required by hot-press molding according to the specific structure and size of the large opening cover; hot-press molding the large opening cover by adopting a die assembly hot-press molding method; a chemical milling method is adopted to etch and process the weight-reducing cavity on the inner profile of the large opening cover; designing and manufacturing a conformal tool required by the machining of the large opening cover according to the specific structure and size of the large opening cover; clamping and fixing the large opening cover by adopting a conformal tool, and filling the gap between the large opening cover and the tool with solid paraffin so as to bond the large opening cover and the tool into a whole; and (5) performing finish machining on the large opening cover by adopting a five-axis numerical control machining center. The invention effectively controls and reduces the vibration and deformation of the large-size thin-wall part in the machining process, and obviously improves the profile and the size precision of the large opening cover.
Description
Technical Field
The invention belongs to the technical field of machining and sheet metal machining, and particularly relates to an accurate machining method for a complex thin-wall variable-thickness large opening cover.
Background
At present, in the aerospace field, along with the requirements of various aircrafts and projectiles on maneuverability and load capacity are higher, the structure of the missile also puts higher requirements on light weight and high strength, and large-scale complex variable-thickness thin-wall parts are more and more applied to the aerospace field, such as airplane wings, fuselage wall plates, variable-thickness skins and the like. However, the parts have the difficulties of large size, thin wall, variable thickness and the like, and the parts have obvious vibration and large deformation in the processing process, and the size and the profile precision are not easy to guarantee, so that the parts are always puzzled to be popularized and applied on a large scale in the aerospace field.
In the processing and manufacturing process of the parts at the present stage, part of the parts are processed by the characteristics of firstly processing a lightening cavity in a flat plate state and the like and then processed by the traditional cold forming means of bending or circling and the like, and the parts are large in size and thin in wall thickness, so that the stress release deformation of the parts is large in the processing process, the uniformity of the wall thickness cannot be ensured, the precision of a molded surface is low, and the qualification rate is low; one part adopts the relevant characteristics of bending and forming a part firstly, machining a lightening cavity by using a five-axis numerical control machining center and the like, the numerical control machining difficulty is high, the thin-wall part cannot be tightly attached to a tool due to deformation, the vibration is obvious in the machining process, the deformation is large, the size precision is not easy to guarantee, and the progress of model products is seriously influenced.
Disclosure of Invention
The invention provides an accurate processing method of the complex thin-wall variable-thickness large covering cap, aiming at the problems that the existing complex thin-wall variable-thickness large covering cap has larger size and thinner wall thickness, has obvious vibration and larger deformation in the processing process of parts, can effectively solve the problems of obvious vibration and larger deformation of the thin-wall large covering cap in the processing process, and further improves the size and the profile accuracy of the large covering cap.
The precise processing method of the complex thin-wall variable-thickness large opening cover comprises the following steps: acquiring original geometric parameters according to a specific structure of a required large opening cover, constructing a three-dimensional model of the large opening cover by using three-dimensional modeling software, performing simulated flattening on the three-dimensional model, and calculating the minimum blank size capable of enveloping the large opening cover according to parameters after flattening; designing and manufacturing a concave-convex die of a tool required by hot press molding according to the specific structure and size of the large opening cover; step three, manufacturing a large-opening-cover coarse blank by adopting a die assembly hot press molding method; corroding and processing a weight reduction cavity on the inner molded surface of the large-opening-cover coarse blank by adopting a chemical milling method; designing and manufacturing a conformal tool required by the machining of the large opening cover according to the specific structure and size of the large opening cover; clamping and fixing the large opening cover by adopting a conformal tool, and filling solid paraffin into a gap between the large opening cover and the tool to bond the large opening cover and the tool into a whole; and seventhly, performing finish machining on the large opening cover by adopting a five-axis numerical control machining center.
Preferably, in the third step, according to the material and the thickness of the part, the temperature is controlled to be 300-350 ℃ during die assembly and hot pressing, and the time for die assembly of the upper die and the lower die is controlled to be 30min during hot pressing.
Preferably, in the fourth step, the large opening cover part is cleaned to remove oil, the inner surface and the outer surface of the large opening cover part are coated with strippable protective paint capable of resisting the action of corrosive solution, the large opening cover part is subjected to shape carving after being cured at room temperature, the protective paint coated on the weight-reducing cavity part is stripped in shape carving mode according to the position and the size of the weight-reducing cavity on the inner molded surface of the large opening cover part, then the large opening cover part is immersed in the corrosive solution, and the exposed surface of the weight-reducing cavity is subjected to corrosion processing.
Preferably, in the sixth step, after the large opening cover and the conformal tool are clamped, the solid paraffin is softened by an electric baking gun auxiliary heating mode, then the softened paraffin is filled into a reserved gap between the large opening cover and the tool to fill a circle, and the large opening cover and the conformal tool are bonded into a whole after the paraffin is solidified at room temperature.
Preferably, in the seventh step, the appearance characteristics of the large opening cover are subjected to finish machining programming by using a UG8.0 three-dimensional numerical control machining module, and the large opening cover is subjected to finish machining by using a five-axis numerical control machining center, so that the corresponding dimensional precision is ensured.
Preferably, the material of the large opening cover is 5A06 aluminum alloy plate.
Preferably, the length, width and thickness dimensions of the large flap in a flattened state are 1600 × 750 × 3mm respectively.
Preferably, the wall thickness of the large surface of the large opening cover is 3mm, and the wall thickness of the weight reduction cavity distributed on the inner molded surface is 1.5 mm.
Compared with the prior art, the beneficial results of the invention are as follows:
the invention can effectively control the vibration and deformation of the large opening cover in the processing process and improve the profile and dimensional accuracy of the large opening cover.
Firstly, the large opening cover is subjected to hot press forming by adopting a die assembly hot press forming method, and compared with the traditional sheet metal bending ring circular cold forming, the surface precision of the large opening cover is greatly improved.
Secondly, the chemical milling method is utilized to etch and process the characteristics of the weight-reducing cavities and the like distributed on the inner molded surface of the large opening cover, compared with the traditional numerical control milling method, the problems of warping deformation and uneven wall thickness of a large-size thin plate caused by stress release in the processing process are effectively solved, the uniformity of the wall thickness of the weight-reducing cavities is effectively ensured, and the deformation of the large opening cover is reduced.
Then, the large opening cover is fixedly clamped by adopting a conformal tool, paraffin softened by heating is filled into a reserved gap between the large opening cover and the conformal tool, and the large opening cover and the conformal tool are bonded into a whole after the paraffin is solidified at room temperature, so that the problem that the large opening cover vibrates obviously in the five-axis numerical control machining process is effectively solved.
And finally, the large opening cover is subjected to finish machining forming by adopting a five-axis numerical control machining center according to the requirement of a design drawing, so that the dimensional precision of the large opening cover is greatly improved.
Drawings
FIG. 1 is a schematic view of a complex thin-walled variable-thickness large flap structure.
FIG. 2 is a schematic view of a complex thin-wall variable-thickness large flap flattening structure.
Fig. 3 is a schematic structural diagram of a large-opening-cover die assembly hot-press molding male-female die.
FIG. 4 is a schematic view of a large opening cover and a conformal tool bonded by paraffin wax.
FIG. 5 is a schematic view of a five-axis machining clamping and fixing structure of a large-opening cover.
Detailed Description
The test part selected by the invention is a large opening cover of a certain aircraft lap joint section, the material of the part is a 5A06 aluminum alloy plate, the product structure is a large thin-wall variable-thickness part with a complex inner cavity, the wall thickness of a weight-reducing cavity of the part is 1.5mm, the wall thickness of the large surface of the large opening cover is 3mm, and the length, width and thickness dimensions of the part in a flattened state are 1600 multiplied by 750 multiplied by 3mm respectively, as shown in figures 1 and 2. The specific implementation mode is as follows:
(1) the method comprises the steps of collecting geometric parameters of an original large opening cover, constructing a three-dimensional model of the large opening cover by utilizing UG8.0 three-dimensional modeling software, performing simulated flattening on the three-dimensional model, and calculating the minimum blank size capable of enveloping the part according to parameters after flattening.
The principle is as follows: according to the specific structure and size of the required large opening cover and the characteristics of bending and circling of the flat plate metal plate, a series of reasonable geometric parameters such as plate elongation and compensation coefficients are selected, the perimeter of the central axis of the large opening cover is reasonably calculated, then the UG metal plate module is utilized to expand the three-dimensional model of the large opening cover into the state of the large opening cover under the flat plate, and the minimum blank size is calculated.
(2) And carrying out hot-press molding on the large opening cover by adopting a die assembly hot-press molding process method.
According to the specific structure and size of the large opening cover, a tooling die required by hot-press molding is designed and manufactured, and the tooling die comprises an upper die and a lower die (namely a female die and a male die), and then the large opening cover is hot-press molded by adopting a die assembly hot-press molding method. In order to prevent the large opening cover from displacing in the process of die assembly and hot pressing, positioning pins and positioning holes need to be processed on the die and the large opening cover in advance, as shown in fig. 3.
The key points are as follows: the temperature is controlled during die assembly and hot pressing, the temperature of the test furnace is controlled to be 300-350 ℃ according to the material and the thickness of a part, and the die assembly time of the upper die and the lower die during hot pressing is controlled to be about 30 min.
(3) And corroding and processing the characteristics of a weight-reducing cavity on the inner molded surface of the large opening cover by adopting a chemical milling method.
The method comprises the steps of cleaning and degreasing a large-opening-cover part, coating strippable protective paint capable of resisting the action of corrosive solution on the inner surface and the outer surface of the large-opening-cover part, carving after curing at room temperature, stripping the protective paint at the position of a lightening cavity according to the position and the size of the lightening cavity on the inner molded surface of the large-opening cover, immersing the large-opening-cover part in the corrosive solution, and carrying out corrosion processing on the surface of the exposed lightening cavity.
The key points are as follows: according to the material of the part, proper corrosion solution and protective coating are selected, the test corrosion solution is selected from alkaline corrosion solution with sodium hydroxide as a main component, and the strippable protective coating is prepared from chloroprene rubber, butyl rubber, polyvinyl chloride and the like. The processing depth, the processing speed and the processed surface quality are controlled by adjusting the components, the concentration, the working temperature and the immersion time of parts of the etching solution, and the unidirectional etching processing speed of the test is controlled to be about 30 mu m/min.
(4) The large opening cover is clamped and fixed by adopting a conformal tool, and solid paraffin is filled in a gap between the large opening cover and the tool to bond the large opening cover and the tool into a whole.
According to the specific structure and size of the large opening cover, a conformal tool required by machining of the large opening cover is designed and manufactured, solid paraffin is softened in an electric baking gun auxiliary heating mode after the large opening cover and the conformal tool are clamped, then the softened paraffin is filled into a reserved gap between the large opening cover and the tool to fill a circle of circumference, and the large opening cover and the conformal tool are bonded into a whole after the paraffin is solidified at room temperature, as shown in fig. 4.
The key points are as follows: the large opening cover is placed on the outer profile of the conformal tool at first, the large opening cover is large in size and thin in wall thickness, certain deformation exists between the actual profile and the theoretical profile, the large opening cover and the conformal tool cannot be completely attached, solid paraffin is heated by the aid of an electric baking gun, softened paraffin is filled into a circle of reserved grooves in the tool, paraffin is cured at room temperature, the large opening cover and the conformal tool are tightly bonded into a whole, and finally the large opening cover is compressed and fixed by a pressing plate matched with the conformal tool.
(5) And (5) performing finish machining on the large opening cover by adopting a five-axis numerical control machining center.
And performing finish machining programming on the appearance characteristics of the large opening cover by using a UG8.0 three-dimensional numerical control machining module, and performing finish machining on the large opening cover by using a five-axis numerical control machining center to ensure the corresponding dimensional precision, as shown in figure 5.
The method for accurately processing the large complex thin-wall variable-thickness large covering cap provided by the invention can effectively ensure the uniformity of the wall thickness of the large covering cap and improve the dimensional precision and the profile precision of the large covering cap. At present, the method of the invention is applied to practical production to solve practical problems and has strong application prospect.
Claims (8)
1. The precise machining method of the complex thin-wall variable-thickness large opening cover is characterized by comprising the following steps of:
acquiring original geometric parameters according to a specific structure of a required large opening cover, constructing a three-dimensional model of the large opening cover by using three-dimensional modeling software, performing simulated flattening on the three-dimensional model, and calculating the minimum blank size capable of enveloping the large opening cover according to parameters after flattening;
designing and manufacturing a concave-convex die of a tool required by hot press molding according to the specific structure and size of the large opening cover;
thirdly, manufacturing a large-opening-cover rough blank by adopting a die-closing hot-press molding method, wherein positioning pins and positioning holes are processed on the die and the large-opening cover in advance in order to prevent the large-opening cover from displacing in the die-closing hot-press process;
corroding and processing a weight reduction cavity on the inner molded surface of the large-opening-cover coarse blank by adopting a chemical milling method;
designing and manufacturing a conformal tool required by the machining of the large opening cover according to the specific structure and size of the large opening cover;
step six, reserving a circle of groove on the tool, clamping and fixing the large opening cover by adopting a conformal tool, filling a gap between the large opening cover and the tool with solid paraffin, and filling a circle of gap to bond the large opening cover and the tool into a whole;
and seventhly, performing finish machining on the large opening cover by adopting a five-axis numerical control machining center.
2. The method for precisely processing the complex thin-wall cover with the variable thickness and the large opening cover according to claim 1, wherein the method comprises the following steps: and in the third step, according to the material and the thickness of the part, controlling the temperature to be 300-350 ℃ during die assembly and hot pressing, and controlling the die assembly time of an upper die and a lower die to be 30min during hot pressing.
3. The method for precisely processing the complex thin-wall cover with the variable thickness and the large opening cover according to claim 1, wherein the method comprises the following steps: and in the fourth step, cleaning and removing oil from the large opening cover part, coating strippable protective paint capable of resisting the action of corrosive solution on the inner surface and the outer surface of the large opening cover part, carving the large opening cover part after curing at room temperature, stripping the protective paint at the position of the weight-reducing cavity according to the position and the size of the weight-reducing cavity on the inner molded surface of the large opening cover part, immersing the large opening cover part in the corrosive solution, and corroding the surface of the exposed weight-reducing cavity.
4. The method for precisely processing the complex thin-wall cover with the variable thickness and the large opening cover according to claim 1, wherein the method comprises the following steps: and sixthly, after the large opening cover and the conformal tool are clamped, softening the solid paraffin in an electric baking gun auxiliary heating mode, filling the softened paraffin into a reserved gap between the large opening cover and the tool, filling a circle of the gap, and bonding the large opening cover and the conformal tool into a whole after the paraffin is solidified at room temperature.
5. The method for precisely processing the complex thin-wall cover with the variable thickness and the large opening cover according to claim 1, wherein the method comprises the following steps: and seventhly, performing finish machining programming on the appearance characteristics of the large opening cover by using a UG8.0 three-dimensional numerical control machining module, and performing finish machining on the large opening cover by using a five-axis numerical control machining center.
6. The method for precisely processing the complex thin-wall cover with the variable thickness and the large opening cover according to claim 1, wherein the method comprises the following steps: the material of big flap is 5A06 aluminum alloy plate.
7. The precise processing method of the complex thin-wall variable-thickness large opening cover according to any one of claims 1 to 6, characterized in that: the length, width and thickness of the large opening cover in a flattened state are 1600 multiplied by 750 multiplied by 3 mm.
8. The precise processing method of the complex thin-wall variable-thickness large opening cover according to any one of claims 1 to 6, characterized in that: the wall thickness of the large surface of the large opening cover is 3mm, and the wall thickness of the weight reducing cavity distributed on the inner molded surface is 1.5 mm.
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| CN110625344B (en) * | 2019-11-21 | 2020-03-17 | 中国航空制造技术研究院 | Method for manufacturing curved surface component with unequal wall thickness |
| CN113001127B (en) * | 2021-04-29 | 2022-11-15 | 北京航星机器制造有限公司 | Method and device for machining skin with active cooling channel |
| CN113601108B (en) * | 2021-06-28 | 2022-09-02 | 北京航星机器制造有限公司 | Processing method of double-sided large-opening variable-thickness titanium alloy thin-wall shell |
| CN114523266B (en) * | 2022-02-25 | 2023-11-17 | 沈阳万航机械制造有限公司 | Precise forming method and die for non-uniform-thickness titanium alloy flap |
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| CN105436823A (en) * | 2015-11-24 | 2016-03-30 | 沈阳黎明航空发动机(集团)有限责任公司 | Method for controlling machining deformation of thin-walled part |
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| US20040035979A1 (en) * | 2002-08-23 | 2004-02-26 | Mccoskey William Robert | Integrally stiffened axial load carrying skin panels for primary aircraft structure and closed loop manufacturing methods for making the same |
| FR3015328B1 (en) * | 2013-12-19 | 2016-05-27 | Aerolia | METHOD AND SYSTEM FOR ASSEMBLING A PLURALITY OF PANELS |
| CN105397423B (en) * | 2015-12-09 | 2017-06-20 | 北京航星机器制造有限公司 | The manufacture method of the large thin-wall covering with interior muscle and complex-shaped surface mould |
| CN108326512B (en) * | 2017-12-29 | 2019-12-31 | 山东豪迈机械制造有限公司 | Machining method and machining device for curved surface workpiece |
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| CN105436823A (en) * | 2015-11-24 | 2016-03-30 | 沈阳黎明航空发动机(集团)有限责任公司 | Method for controlling machining deformation of thin-walled part |
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