Processing and manufacturing method of split type special-shaped thin-wall cover plate

Abstract

The invention discloses a processing and manufacturing method of a half-split special-shaped thin-wall cover plate, which comprises the following steps of: performing integral additive manufacturing on a half-split open left cover plate blank and a half-split open right cover plate blank by adopting a laser additive manufacturing method, reducing the processing area and the processing allowance of an inner cavity of a cabin, and performing feature processing on an appearance surface, an end butt-joint circulating hole, an axial butt-joint hole, a groove and the like by combining; and then the butt joint inner seam allowance and the butt joint end face are machined in a split mode, so that the profile precision is effectively controlled, the clamping alignment and reference transmission difficulty is reduced, gaps during assembly are reduced, and high-precision machining of the split cover plate is achieved.

Description

Technical Field

[0001] The invention relates to a method for processing and manufacturing a half-type special-shaped thin-wall cover plate, and belongs to the technical field of mechanical processing. Background Art

[0002] At present, various products in the fields of aerospace, defense equipment, etc. have put forward higher requirements for mobility, long endurance, and lightweight. Large, complex, special-shaped, thin-walled structural parts are widely used. They are characterized by open structure, complex curved surface, thin wall, complex structure, weak rigidity and easy deformation. These characteristics make them difficult to locate and clamp during the processing and manufacturing process, with low processing efficiency and long cycle. It is difficult to ensure the position of some features in the product relative to the overall product after assembly.

[0003] At present, most of the parts are closed rotary structures, which adopt the traditional solution of casting and machining. The problems include large casting residue, large deformation, large machining removal, poor production efficiency and cabin assembly accuracy, which seriously affect product performance and overall product progress. Summary of the invention

[0004] The technical problem solved by the present invention is: to overcome the shortcomings of the prior art, and to propose a processing and manufacturing method for a half-type special-shaped thin-walled cover plate, and to achieve high-precision processing of the cover plate through additive manufacturing of a combined blank and clamping and positioning design.

[0005] The technical solution of the present invention is:

[0006] A method for processing and manufacturing a half-shaped thin-walled cover plate, comprising:

[0007] Step 1: Design an additive blank that connects the left and right cover plates according to their structure, processing area and processing allowance;

[0008] Step 2: Draw horizontal, symmetrical reference lines and axial end surface lines on the additive blank;

[0009] Step 3: Align according to the horizontal and symmetrical reference lines, and rough-process the end faces and inner stops of the additive blank;

[0010] Step 4: Clamp and position the workpiece after rough machining, and roughly mill the outer surface to make the wall thickness meet the design requirements;

[0011] Step 5: vacuum heat treatment of the workpiece after rough milling;

[0012] Step 6: Clamp and position the workpiece, finish the outer surface, end butt-joint circulation hole, axial butt-joint hole and groove, and wire-cut the split reference groove;

[0013] Step 7: Find the end face and the split reference groove, and use wire cutting to split the additive blank to obtain the left and right cover plates;

[0014] Step 8. Position and clamp the left and right cover plates respectively, and finish the inner stoppers and end faces of the left and right cover plates.

[0015] Furthermore, in step 1, the designed weight-reducing groove in the inner cavity of the additive blank does not leave any allowance, and the end face, outer surface, inner stop, and side wall features all leave 2 to 3 mm, and the additive blank is connected by the middle ribs of the left and right cover plates;

[0016] Furthermore, in step one, process bosses are reserved on the front and rear end faces of the additive blank, and the process bosses are located within the horizontal and symmetrical reference plane of the additive blank; in step two, alignment is performed according to the process bosses, horizontal and symmetrical reference lines are drawn, and the end face lines at both ends are determined and drawn along the axial direction according to the non-processed features of the inner cavity of the cover plate.

[0017] Furthermore, in step four, a positioning tool is used to clamp and position the workpiece after rough machining; the positioning tool includes an upper blocking plate, a lower blocking plate, and a pull rod; two vertically placed pull rods connect the upper blocking plate and the lower blocking plate, the upper and lower blocking plates are placed horizontally, and their shapes are the same as the upper and lower end faces of the additive blank, the center points of the upper and lower blocking plates are located on the same axis and the two pull rods are symmetrical about this axis; after clamping the additive blank workpiece, the upper and lower blocking plates are tightly fitted to the upper and lower end faces of the additive blank; two reference grooves are opened radially on the side faces of the upper blocking plate, and the line connecting the center points of the reference grooves is perpendicular to the axis, and the workpiece is aligned according to the reference grooves.

[0018] Furthermore, in step three, the end faces and the inner stops at both ends of the additive blank are roughly machined, and the single-side allowance during rough machining is at least 1 mm.

[0019] Furthermore, in step four, a round nose milling cutter is used to process the outer surface with a small cutting depth, and the cutting depth is not more than 0.3mm; the wall thickness is measured multiple times during the processing, and the processing zero point is fine-tuned according to the wall thickness data to make the overall wall thickness of the outer shape uniform; finally, the front and rear end face stops are corrected according to the new zero point to determine the final processing finishing benchmark.

[0020] Furthermore, in step seven, the workpiece is clamped horizontally, and the workpiece is separated by wire cutting based on the end face of the workpiece and the reference groove.

[0021] Furthermore, in step eight, a clamping tool is used to position and clamp the left cover plate or the right cover plate; the clamping tool includes a positioning pin, a pressure ring and a clamping screw; wherein, the positioning pin is used to position and align the cover plate, and the pressure ring and the clamping screw are used to firmly fix the cover plate, so that the outer surface of the cover plate fits in place with the surface of the clamping tool, and the positioning pins at both ends are used for precise positioning, and finally the butt end faces at both ends and the inner stop of the inner cavity are finely processed.

[0022] Furthermore, in step six, a five-axis machining center is used for fine machining, and the end process positioning holes are used for accurate positioning of the left and right cover plates and the clamping tooling after separation.

[0023] The advantages of the present invention compared with the prior art are:

[0024] (1) The present invention adopts a laser additive manufacturing method to perform integral additive manufacturing on the half-type thin-walled cover plate blank, and direct additive molding without leaving any allowance is adopted for the non-processing area of ​​the inner cavity, thereby reducing the processing area and processing allowance as a whole.

[0025] (2) The present invention first combines the outer surface, end butt circular hole, axial butt hole and bevel and other feature processing, and then performs separate processing on the butt inner stop and butt end face, thereby effectively controlling the surface accuracy, reducing the difficulty of clamping and alignment, and reference transfer, reducing the gap during assembly, and realizing high-precision processing and assembly of the cover plate.

[0026] (3) The present invention adopts a reserved process boss for rough machining datum alignment, and effectively positions and transfers datums by designing positioning tooling, thereby reducing the difficulty of clamping and alignment, improving the overall rigidity of the workpiece, and ensuring the surface accuracy and wall thickness index requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Moreover, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0028] Figure 1 This is a schematic diagram of the split structure of a half-type special-shaped thin-walled cover plate according to an embodiment of the present invention;

[0029] Figure 2 This is a schematic diagram of a cover plate combined additive blank according to an embodiment of the present invention;

[0030] Figure 3 This is a schematic diagram of a milling machine fixture for processing a cover plate assembly according to an embodiment of the present invention;

[0031] Figure 4 Schematic diagram of the cover plate assembly processing structure according to the embodiment of the present invention

[0032] Figure 5 It is a schematic diagram of the split processing structure of the cover plate according to an embodiment of the present invention. DETAILED DESCRIPTION

[0033] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0034] The present invention proposes a processing and manufacturing method for a half-type special-shaped thin-walled cover plate. A new laser additive manufacturing scheme is adopted for the blank, and the processing area and processing allowance of the cover plate are reduced. The outer surface, end butt circulation holes, axial butt holes and bevels are first combined for feature processing, and then the butt inner stop and butt end surface are processed separately, thereby effectively controlling the surface accuracy, reducing the difficulty of clamping and alignment, and reference transfer, reducing the gap during assembly, and realizing high-precision processing and assembly of the cover plate.

[0035] The present invention is further described below by way of examples. The test workpiece in the examples is a cover plate of a certain product, such as Figure 2 As shown, the part is made of TA15 titanium alloy, the blank is formed by laser additive manufacturing, the cover plate is a free-form curved surface, the major axis is about 350mm, the minor axis is about 275mm, the height is about 520mm, the thinnest wall thickness is 2mm, and the left and right cover plate ends and side axial distribution mounting hole features are as follows: Figure 1 As shown, the assembled left and right cover plates and other end frames can be installed smoothly, and the step difference is no more than 0.2mm.

[0036] The manufacturing method specifically comprises:

[0037] Step 1: Design an additive blank that connects the left and right cover plates according to their structure, processing area, and distribution of processing allowance.

[0038] The machining allowance is reasonably distributed according to the technical requirements. The non-matching assembly surface adopts the form of direct additive molding without setting the allowance. The machining surface allowance is 2mm to reduce the machining cycle as much as possible. The combined additive blank is connected by the 10mm rib in the middle of the left and right cover plates to avoid the risk of deformation during additive manufacturing due to excessive combined size. At the same time, a reference groove is opened on the rib to facilitate the alignment of the machining reference in the later stage. Process bosses are reserved on the front and rear end faces. The process bosses are located in the horizontal and symmetrical reference plane of the blank. At the same time, the additive model needs to be designed with ribs, lattices, etc. to prevent excessive deformation of the workpiece during the additive process.

[0039] Step 2: Align according to the reserved process boss of the additive manufacturing process, and draw the horizontal, symmetrical reference lines and axial end surface lines.

[0040] After the left and right cover plates are combined, their outer shapes have no flat surfaces or circles that are easy to use as datums, which makes it difficult to transfer datums between processes. Process bosses with a height of 5 mm and a width of 5 mm are reserved on the front and rear end faces of the combined additive blank. The overall horizontal and symmetrical datum lines of the cover plates are aligned and drawn according to the process bosses. The end surface lines at both ends are determined and drawn along the axial direction according to the non-machined features inside the cover plates (ring rib surface), thereby determining the rough machining datum.

[0041] Step 3. Align according to the marked reference line, and rough-process the end faces and inner stoppers of the cabin body. During rough processing, leave 1.5mm on one side to ensure uniform removal of the inner shape. When rough processing the inner stoppers at both ends, the upper and lower plugging plates need to be tested to prevent the large gap between the plugging plate and the workpiece from causing inaccurate positioning.

[0042] Step 4: Use the positioning fixture to clamp and position the workpiece. The positioning fixture is as follows: Figure 3 As shown, it includes an upper blocking plate, a lower blocking plate, and a pull rod. Two vertically placed pull rods connect the upper blocking plate and the lower blocking plate. The upper and lower blocking plates are placed horizontally, and their shapes are the same as the upper and lower end faces of the additive blank. The center points of the upper and lower blocking plates are located on the same axis and the two pull rods are symmetrical with this axis. After clamping the additive blank workpiece, the upper and lower blocking plates fit tightly with the upper and lower end faces of the additive blank to play a supporting role. Two reference grooves are opened radially on the side of the upper blocking plate, and the line connecting the center points of the reference grooves is perpendicular to the axis.

[0043] The additive blank workpiece is aligned according to the reference grooves of the upper and lower blocking plates and the rib positions on the workpiece, such as Figure 4 As shown, rough-process the outer surface, measure the wall thickness, and fine-tune the program zero point according to the wall thickness to ensure that the wall thickness meets the technical requirements. Correct the inner stop at the upper and lower ends according to the new program zero point

[0044] When machining the overall outer surface of the cover plate, the positioning fixture is used for positioning and alignment, and a small diameter round nose milling cutter is used to machine the outer surface with a small cutting depth. The wall thickness is measured several times during the machining process, and the machining zero point is fine-tuned according to the wall thickness data to ensure that the overall wall thickness of the outer shape is uniform. Finally, the front and rear end stoppers are corrected according to the new zero point to determine the final machining and finishing benchmark. The single-side allowance after correction is 0.8mm. At the same time, the cutting depth is not more than 0.3mm when machining the surface to prevent the surface from being deformed due to excessive cutting force. The outer surface allowance is 1mm during rough machining.

[0045] Step 5: After rough machining, the assembly is vacuum heat treated to eliminate residual stress inside the workpiece and reduce deformation during subsequent wire cutting and separation of the cover plate.

[0046] Step 6: When the cover is assembled, use the tooling to clamp the positioning workpiece and position the fine-machined outer surface, and align it according to the upper and lower plugging plate reference grooves. End mounting holes, axial mounting holes and grooves, wire cutting split reference grooves.

[0047] Using the tooling to locate and align, a five-axis machining center is used to finely process the external surface, end mounting holes, axial mounting holes and grooves, and wire-cut split reference grooves in one clamping condition. The split reference grooves are located on the ribs to ensure that the relative positions of the left and right cover plate external surfaces and the docking holes are more accurate. The end process positioning holes are used to accurately position the split rear cover plate and the tooling.

[0048] Step 7. Clamp the workpiece horizontally, locate the end face and the split reference groove, and use the end face of the workpiece and the wire cutting reference groove as the reference to separate the left and right cover plates by wire cutting symmetrically to prevent large deformation during the separation process of the left and right cover plates.

[0049] Step 8. Use the clamping tool to position and clamp the split state, and fine-process the inner stop and end faces of the left and right cover plates.

[0050] The clamping tooling includes positioning pins, pressure rings and clamping screws. Figure 5 As shown, the workpiece and the tooling are accurately positioned and aligned using locating pins, and the workpiece is firmly fixed to the tooling using a pressure ring and a clamping screw to ensure that the part's outer surface fits in place with the pressure ring's surface. The locating pins at both ends are used for accurate positioning, and the butt end faces at both ends and the inner stop of the inner cavity are finely machined.

[0051] The above-described embodiments are only preferred specific implementations of the present invention. Common changes and substitutions made by those skilled in the art within the scope of the technical solution of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for processing and manufacturing a half-shaped thin-walled cover plate, characterized in that: include: Step 1: Design an additive blank that connects the left and right cover plates according to their structure, processing area and processing allowance; Step 2: Draw horizontal, symmetrical reference lines and axial end surface lines on the additive blank; Step 3: Align according to the horizontal and symmetrical reference lines, and rough-process the end faces and inner stops of the additive blank; Step 4: Clamp and position the workpiece after rough machining, and roughly mill the outer surface to make the wall thickness meet the design requirements; Step 5: vacuum heat treatment of the workpiece after rough milling; Step 6: Clamp and position the workpiece, finish the outer surface, end butt-joint circulation hole, axial butt-joint hole and groove, and wire-cut the split reference groove; Step 7: Find the end face and the split reference groove, and use wire cutting to split the additive blank to obtain the left and right cover plates; Step 8. Position and clamp the left and right cover plates respectively, and finish the inner stoppers and end faces of the left and right cover plates.

2. The method for manufacturing the half-shaped thin-walled cover plate according to claim 1, characterized in that: In step one, the designed inner cavity weight reduction groove of the additive blank does not leave any allowance, and the end face, outer surface, inner stop, and side wall features all leave 2 to 3 mm. The additive blank is connected by the middle ribs of the left and right cover plates.

3. The method for manufacturing the half-shaped thin-walled cover plate according to claim 1, characterized in that: In step one, process bosses are reserved on the front and rear end faces of the additive blank, and the process bosses are located within the horizontal and symmetrical reference plane of the additive blank; in step two, alignment is performed according to the process bosses, horizontal and symmetrical reference lines are drawn, and the end face lines at both ends are determined and drawn along the axial direction according to the non-processed features of the inner cavity of the cover plate.

4. The method for manufacturing the half-shaped thin-walled cover plate according to claim 1, characterized in that: In step four, a positioning tool is used to clamp and position the workpiece after rough machining; the positioning tool includes an upper blocking plate, a lower blocking plate, and a pull rod; two vertically placed pull rods connect the upper blocking plate and the lower blocking plate, the upper and lower blocking plates are placed horizontally, and their shapes are the same as the upper and lower end faces of the additive blank, the center points of the upper and lower blocking plates are located on the same axis and the two pull rods are symmetrical about this axis; after clamping the additive blank workpiece, the upper and lower blocking plates fit tightly with the upper and lower end faces of the additive blank; two reference grooves are opened radially on the side faces of the upper blocking plate, and the line connecting the center points of the reference grooves is perpendicular to the axis, and the workpiece is aligned according to the reference grooves.

5. The method for manufacturing the half-shaped thin-walled cover plate according to claim 1, characterized in that: In step three, the end faces and the inner stoppers at both ends of the additive blank are roughly machined, and the single-side allowance during rough machining is at least 1 mm.

6. The method for manufacturing the half-shaped thin-walled cover plate according to claim 1, characterized in that: In step four, a round nose milling cutter is used to process the outer surface with a small cutting depth of no more than 0.3 mm; the wall thickness is measured multiple times during the processing, and the processing zero point is fine-tuned according to the wall thickness data to make the overall wall thickness of the outer shape uniform; finally, the front and rear end face stops are corrected according to the new zero point to determine the final processing finishing benchmark.

7. The method for manufacturing the half-shaped thin-walled cover plate according to claim 1, characterized in that: In step seven, the workpiece is clamped horizontally, and the workpiece is separated by wire cutting based on the end face of the workpiece and the reference groove.

8. The method for manufacturing the half-shaped thin-walled cover plate according to claim 1, characterized in that: In step eight, a clamping tool is used to position and clamp the left cover or the right cover; the clamping tool includes a positioning pin, a pressure ring and a clamping screw; wherein, the positioning pin is used to position and align the cover, and the pressure ring and the clamping screw are used to firmly fix the cover so that the outer surface of the cover fits in place with the surface of the clamping tool, and the positioning pins at both ends are used for precise positioning, and finally the butt end faces at both ends and the inner stop of the inner cavity are finely processed.

9. The method for manufacturing the half-shaped thin-walled cover plate according to claim 1, characterized in that: In step six, a five-axis machining center is used for finishing, and the end process positioning holes are used to accurately position the left and right cover plates and the clamping tooling after separation.

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