A processing and manufacturing method of a split half-shaped thin-wall cover plate

Abstract

The application discloses a processing and manufacturing method of a split half-shaped special-shaped thin-wall cover plate, and adopts a laser additive manufacturing method to integrally additively manufacture a split half-shaped open left and right cover plate blank, reduces a cabin inner cavity processing area and a processing allowance, and first carries out split body processing to process features such as an outer shape surface, an end part butt joint circulating hole, an axial butt joint hole and a bevel, then carries out split body processing to butt joint an inner stopper and a butt joint end surface, thereby effectively controlling profile precision, reducing clamping alignment, reducing difficulty in transferring a reference, reducing a gap during assembly, and realizing high-precision processing of the split half-shaped cover plate.

Description

TECHNICAL FIELD

[0001] The application relates to a processing and manufacturing method of a split half-shaped thin-wall cover plate and belongs to the technical field of machining. BACKGROUND

[0002] At present, various products in the fields of aerospace, defense equipment and the like have higher requirements for mobility, long endurance and light weight, and large-scale complex shaped thin-wall structural parts are widely applied. The parts are characterized by open structure, composite curved surface, thin wall, complex structure, weak rigidity and easy deformation and the like. The characteristics result in that the parts are difficult to position and clamp during the processing and manufacturing process, the processing efficiency is low, the cycle is long, and the positions of part features after assembly are difficult to guarantee relative to the overall product.

[0003] At present, most parts are mainly closed rotary structures, and the traditional scheme of casting and machining is adopted. The casting has large allowance and large deformation, the machining has large removal amount, the production efficiency and cabin assembly precision are poor, and the like, which seriously affect the product performance and overall progress of the product. SUMMARY

[0004] The application solves the technical problem that the prior art is not enough, and provides a processing and manufacturing method of a split half-shaped thin-wall cover plate. The method realizes high-precision machining of the cover plate through additive manufacturing of a combined blank and clamping positioning design.

[0005] The technical solution of the application is as follows.

[0006] A processing and manufacturing method of a split half-shaped thin-wall cover plate comprises the following steps.

[0007] Step one, an additive blank of a combined left and right cover plate is designed according to the structure, processing area and processing allowance of the left and right cover plates.

[0008] Step two, a horizontal and symmetrical reference line and an axial end surface line are drawn on the additive blank.

[0009] Step three, the two end surfaces and the two end inner stops of the additive blank are coarsely machined according to the horizontal and symmetrical reference line.

[0010] Step four, the coarsely machined workpiece is clamped and positioned, and the outer surface is coarsely milled to make the wall thickness meet the design requirements.

[0011] Step five, the coarsely milled workpiece is subjected to vacuum heat treatment.

[0012] Step six, the workpiece is clamped and positioned, the outer surface, the end portion, the circular hole, the axial joint hole and the groove are finely machined, and the split reference groove is cut by wire cutting.

[0013] Step seven, the end surface and the split reference groove are aligned, the additive blank is split by wire cutting, and the left and right cover plates are obtained.

[0014] Step eight, respectively positioning clamping left and right cover plate, finishing left and right cover plate butt joint inner stop, butt joint end face.

[0015] Further, in step one, the designed additive blank inner cavity weight reduction groove does not leave a margin, the end face, the outer shape surface, the inner stop, and the side wall feature all leave a margin of 2-3mm, the additive blank is connected through the middle rib of the left and right cover plate;

[0016] Further, in step one, the front and rear end faces of the additive blank are both pre-processed bosses, and the process bosses are located in the horizontal and symmetrical reference plane of the additive blank; in step two, the horizontal and symmetrical reference line is drawn according to the process boss, and the two end face lines are determined and drawn according to the non-machining features of the cover plate inner cavity in the axial direction.

[0017] Further, in step four, a positioning tool is used to clamp the rough machined workpiece; the positioning tool includes an upper plug disc, a lower plug disc, and a pull rod; two vertically placed pull rods connect the upper plug disc and the lower plug disc, and the upper and lower plug discs are both horizontally placed and have the same shape as the upper and lower end faces of the additive blank, and the center points of the upper and lower plug discs are located on the same axis and the two pull rods are symmetrical about the axis; after clamping the additive blank workpiece, the upper and lower plug discs are tightly attached to the upper and lower end faces of the additive blank; two reference grooves are respectively opened on the side surface of the upper plug disc along the radial direction, the center points of the reference grooves are connected to a line that is perpendicular to the axis, and the workpiece is aligned according to the reference grooves.

[0018] Further, in step three, the two end faces and the two end inner stops of the additive blank are rough machined, and at least 1mm of single-sided allowance is left during rough machining.

[0019] Further, in step four, a small cutting depth circular nose milling cutter is used to process the outer shape surface, and the cutting depth is not greater than 0.3mm; the wall thickness is measured multiple times during the machining process, the machining zero point is adjusted according to the wall thickness data to make the overall wall thickness of the shape uniform; finally, the front and rear end face stops are corrected according to the new zero point to determine the final machining and finishing reference.

[0020] Further, in step seven, the workpiece is clamped horizontally, the workpiece end face and the reference groove are used as the reference, and the workpiece is cut into parts using a wire cutting machine.

[0021] Further, 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 tightening screw; the cover plate is positioned and aligned using the positioning pin, the cover plate is firmly fixed using the pressure ring and the tightening screw, the cover plate shape surface is attached to the clamping tool surface in place, the two end positioning pins are used for precise positioning, and finally the two end butt faces and the inner cavity butt inner stops are finished.

[0022] Further, in step six, a five-axis machining center is used for finishing, and the end process positioning hole is used for accurate positioning of the left and right cover plates after being cut into parts and the clamping tool.

[0023] The present application has the advantages compared with the prior art:

[0024] (1) The present application adopts laser additive manufacturing method to integrally manufacture the split half thin-wall cover plate blank, and the inner cavity non-processing area is directly additive formed without allowance, thereby reducing the processing area and processing allowance.

[0025] (2) The present application first processes the features such as the contour surface, the end butt joint circulating hole, the axial butt joint hole and the bevel, and then processes the split body processing butt joint inner stop and butt joint end surface, thereby effectively controlling the profile accuracy, reducing the clamping alignment difficulty, the reference transmission difficulty, the gap during assembly, realizing the high-precision processing and assembly of the cover plate.

[0026] (3) The present application adopts the reserved process boss to perform rough machining reference alignment, effectively positions and transmits the reference through the design of positioning tooling, reduces the clamping alignment difficulty, improves the overall rigidity of the workpiece, and ensures the profile accuracy and wall thickness index requirements. BRIEF DESCRIPTION OF DRAWINGS

[0027] Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The accompanying drawings are included to provide a description of the preferred embodiments and are not intended to limit the scope of the application. Moreover, the same reference numerals are intended to denote the same components throughout the accompanying drawings. In the drawings:

[0028] Figure 1 is a split half special-shaped thin-wall cover plate split body structure schematic diagram of an embodiment of the present application;

[0029] Figure 2 is a cover plate split body additive blank schematic diagram of an embodiment of the present application;

[0030] Figure 3 is a cover plate split body processing milling machine clamp schematic diagram of an embodiment of the present application;

[0031] Figure 4 is a cover plate split body processing structure schematic diagram of an embodiment of the present application

[0032] Figure 5 is a cover plate split body processing structure schematic diagram of an embodiment of the present application. DETAILED DESCRIPTION

[0033] Exemplary embodiments of the present disclosure will be described below in greater detail with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the 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. Rather, these embodiments are provided so that the present disclosure can be more thoroughly understood and the scope of the present disclosure can be accurately conveyed to those skilled in the art.

[0034] This invention proposes a method for processing and manufacturing a split-type irregular thin-walled cover plate. The blank adopts a new laser additive manufacturing scheme to reduce the processing area and processing allowance of the cover plate. First, the outer surface, end docking circulation holes, axial docking holes and bevels are processed by assembling the blank. Then, the inner stop and docking end face are processed separately. This effectively controls the surface accuracy, reduces the difficulty of clamping and alignment and datum transfer, reduces the gap during assembly, and realizes high-precision processing and assembly of the cover plate.

[0035] The invention will be further illustrated below by means of embodiments. The test workpiece in the embodiments 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 using laser additive manufacturing. The cover plate has a free-form irregular curved surface shape, with a major axis of approximately 350mm, a minor axis of approximately 275mm, a height of approximately 520mm, and a minimum wall thickness of 2mm. Mounting holes are distributed axially on the ends and sides of the left and right cover plates, as shown in the image. Figure 1 As shown, the assembled left and right cover plates can be smoothly installed with other end frames, with a step difference of no more than 0.2mm.

[0036] The manufacturing method specifically includes:

[0037] Step 1: Design the additive blank that connects the left and right cover plates into a whole, based on the structure, processing area and processing allowance distribution of the left and right cover plates.

[0038] According to the technical requirements, the machining allowance is reasonably distributed. Non-fitting assembly surfaces are directly additively formed without setting allowances. The machining allowance is 2mm to minimize the machining cycle. The combined additive blank is connected by a 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 later. 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. Meanwhile, the additive model needs to be designed with ribs, dot matrix, etc. to prevent excessive workpiece deformation during additive manufacturing.

[0039] Step 2: Align the additive manufacturing pre-reserved process bosses and draw horizontal and symmetrical baselines and axial end face lines.

[0040] The lack of planes and circles as easy references after the left and right cover plates are combined makes it difficult to transfer references between processes. Process bosses with a height of 5mm and a width of 5mm are reserved on the front and rear ends of the combined additive blank. The overall horizontal and symmetrical reference lines of the cover plate are drawn based on the process bosses. The end face lines of both ends are determined and drawn along the axial direction based on the non-machined features (ring rib surface) inside the cover plate, thereby determining the rough machining reference.

[0041] Step three, according to the reference line, the rough machining of the end face of the cabin body and the two end inner stop, rough machining when the single side allowance 1.5mm, ensure the uniformity of the inner type, rough machining of the two end inner stop need to try to install the upper and lower stop disc, prevent the gap between the stop disc and the workpiece, which can not be accurately positioned.

[0042] Step four, the workpiece is clamped and positioned by using positioning tooling, as shown in Figure 3 , including the upper stop disc, the lower stop disc, the pull rod, the two vertical pull rods connecting the upper stop disc and the lower stop disc, the upper and lower stop discs are horizontally placed, the shape is the same as the upper and lower end face of the additive blank, and the center points of the upper and lower stop discs are located on the same axis and the two pull rods are symmetrical about the axis. After clamping the additive blank workpiece, the upper and lower stop discs are tightly fitted with the upper and lower end face of the additive blank, which plays a supporting role. Two reference grooves are respectively opened on the side surface of the upper stop disc along the radial direction, and the center points of the reference grooves are perpendicular to the axis.

[0043] The additive blank workpiece is aligned according to the reference groove of the upper and lower stop discs and the position of the rib on the workpiece, as shown in Figure 4 , and the outer shape is further machined, the wall thickness is measured, and the program zero point is adjusted according to the wall thickness, to ensure that the wall thickness meets the technical requirements. According to the new program zero point, the inner stop of the upper and lower end is corrected

[0044] When machining the overall outer shape of the cover plate, the positioning tooling is used for positioning and alignment, and a small diameter nose milling cutter with small cutting depth is used for machining the outer shape. During the machining process, the wall thickness is measured several times, the machining zero point is adjusted according to the wall thickness data, the overall wall thickness of the shape is ensured to be uniform, and finally the front and rear end face stop is corrected according to the new zero point to determine the final machining and finishing reference. After correction, the single side allowance is 0.8mm. When machining the surface, the cutting depth is not greater than 0.3mm, to prevent the deformation of the surface caused by excessive cutting force, and the outer shape allowance is 1mm during rough machining.

[0045] Step five, after rough machining, the workpiece is vacuum heat treated to eliminate the internal residual stress of the workpiece and reduce the deformation of the workpiece during subsequent line cutting of the cover plate.

[0046] Step six, the cover plate is clamped and positioned by using tooling to position the workpiece for finishing the outer shape, according to the reference groove of the upper and lower stop disc. The end mounting hole, the axial mounting hole and the bevel, and the line cutting split reference groove.

[0047] The tooling is used for positioning and alignment, and the five-axis machining center is used for finishing the outer shape, the end mounting hole, the axial mounting hole and the bevel, and the line cutting split reference groove under the condition of one clamping. The split reference groove is located on the rib, which ensures that the relative position of the outer shape of the left and right cover plates and the butt joint hole is more accurate. The end process positioning hole is used for accurate positioning of the cover plate and the tooling after splitting.

[0048] Step 7: Clamp the workpiece horizontally, align the end face and the split reference groove. Using the workpiece end face and the wire EDM reference groove as references, use wire EDM to symmetrically cut the left and right cover plates to separate them, preventing large deformation during the separation process.

[0049] Step 8: In the split state, use clamping fixtures for positioning and clamping, and then perform precision machining on the inner stop and the mating end face of the left and right cover plates.

[0050] The clamping fixture includes locating pins, pressure rings, and clamping screws. For example... Figure 5 As shown, positioning pins are used to accurately position and align the workpiece with the tooling. The workpiece is then firmly fixed to the tooling using a pressure ring and clamping screws to ensure that the outer surface of the part fits properly with the surface of the pressure ring. Positioning pins at both ends are used for precise positioning, and the mating end faces and inner locating surfaces of the inner cavity are precision machined.

[0051] The embodiments described above are merely preferred embodiments of the present invention. Ordinary variations and substitutions made by those skilled in the art within the scope of the technical solution of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for manufacturing a split profile thin-walled cover plate, characterized in that, The application relates to a method for manufacturing left and right cover plates. Step one: designing an additive blank for connecting the left and right cover plates into a whole body according to the structure, processing area and processing allowance of the left and right cover plates; wherein the additive blank of the whole body is connected through the middle rib of the left and right cover plates, a reference groove is arranged on the rib, process bosses are reserved on the front and back end faces of the additive blank, and the process bosses are located in the horizontal and symmetrical reference plane of the blank; Step two: finding the reference according to the process bosses, drawing a horizontal and symmetrical reference line and an axial end face line on the additive blank, determining and drawing two end face lines according to the non-processing features of the inner cavity of the cover plate in the axial direction, and determining a rough machining reference; Step three: finding the reference according to the drawn horizontal and symmetrical reference line, and rough machining the two end faces and the two end inner stoppers of the additive blank; Step four: clamping and positioning the machined workpiece by using a positioning tool; the positioning tool comprises an upper blocking disc, a lower blocking disc and a pull rod; the two vertically arranged pull rods connect the upper blocking disc and the lower blocking disc; the upper and lower blocking discs are horizontally arranged and have the same shapes as the upper and lower end faces of the additive blank respectively; the center points of the upper and lower blocking discs are located on the same axis, and the two pull rods are symmetrically arranged about the axis; after the additive blank workpiece is clamped, the upper and lower blocking discs are tightly attached to the upper and lower end faces of the additive blank; two reference grooves are respectively arranged on the side surface of the upper blocking disc in the radial direction, and the center points of the reference grooves are connected to form a line which is perpendicular to the axis; the workpiece is found by using the reference grooves, the outer profile is coarsely milled, and the wall thickness is made to meet the design requirements; Step five: performing vacuum heat treatment on the workpiece after coarse milling; Step six: clamping and positioning the workpiece by using a positioning tool, and precisely machining the outer profile, the end mounting hole, the axial mounting hole and the bevel, and cutting the split reference groove by using a wire cutting machine; Step seven: horizontally clamping the workpiece, taking the end face and the reference groove of the workpiece as the reference, and cutting the workpiece by using a wire cutting machine to obtain the left and right cover plates; Step eight: clamping and positioning the left cover plate or the right cover plate by using a clamping tool; the clamping tool comprises a positioning pin, a pressing ring and a pressing screw; the cover plate is positioned and found by using the positioning pin, the cover plate is firmly fixed by using the pressing ring and the pressing screw, the outer profile of the cover plate is attached to the clamping tool profile in place, the two end positioning pins are used for precise positioning, and finally the two end butt faces and the inner cavity butt inner stoppers are precisely machined.

2. The method of claim 1, wherein the half-split shaped thin-walled cover plate is manufactured by the steps of: In step one, the weight-reducing groove in the inner cavity of the designed additive blank does not have an allowance, and the end face, the outer profile, the inner stopper and the side wall features all have an allowance of 2-3 mm.

3. The method of claim 1, wherein the method further comprises: In step three, the two end faces and the two end inner stoppers of the additive blank are coarsely machined, and the single-side allowance is at least 1 mm during coarse machining.

4. The method of claim 1, wherein the half-split shaped thin-walled cover plate is manufactured by the steps of: In step four, the outer profile is processed by using a circular nose milling cutter with a small cutting depth, and the cutting depth is not greater than 0.3 mm; the wall thickness is measured multiple times during the processing, the processing zero point is adjusted according to the wall thickness data, the overall wall thickness of the outer profile is made uniform, the front and back end face stoppers are finally corrected according to the new zero point, and the final machining and precise machining reference is determined.

5. The method of claim 1, wherein the method further comprises: In step six, a five-axis machining center is used for precise machining, and the end process positioning hole is used for accurately positioning the left and right cover plates after splitting and the clamping tool.

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