Numerical control machining method of multi-feature backing plate

Abstract

The application discloses a numerical control machining method for a multi-feature gasket plate, and comprises the following steps: auxiliary precise positioning of a part through design of a process data model, numerical control stretch forming, flexible clamping and numerical control milling, so that efficient and precise digital manufacturing of the multi-feature gasket plate part is realized. The method simplifies the process flow of the multi-feature gasket plate machining, and has good machining quality and high production efficiency. The application effectively solves the problem that the prior art cannot realize efficient and precise digital manufacturing.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of process equipment design of aviation manufacturing technology, and relates to a machining method of a multi-feature gasket plate. BACKGROUND

[0002] In the process of developing an airplane, the typical structure of a fuselage wall plate is usually a skin plus a gasket plate. In order to facilitate the smooth passing of systems and structural parts, the gasket plate is mostly designed as a multi-curvature thin-walled part containing system passing holes, irregular structure openings, complex shape contours, and skin fitting. The machining quality of such multi-feature gasket plates is of great significance to the assembly efficiency and quality of the airplane.

[0003] Since the gasket plate is mostly a double-curvature structure, it cannot be formed by roll bending, and the traditional gasket plate machining process method is to manually knock and cut the shape according to the lines engraved on the skin mold, which has low production efficiency, poor machining quality, poor curved surface forming degree, leaves part of the allowance, and has high requirements for the skill level of workers, and cannot meet the production needs of high-efficiency and precise digital manufacturing of airplane sheet metal parts. SUMMARY

[0004] The purpose of the application is to provide a multi-feature gasket plate machining method to solve the problem that the prior art cannot realize high-efficiency and precise digital manufacturing.

[0005] In order to achieve the above-mentioned task, the application adopts the following technical solutions:

[0006] A numerical control machining method of a multi-feature gasket plate, comprising the following steps:

[0007] Step 1: Design a process data model

[0008] Firstly, the forming surface of the tooling mold for machining the corresponding position skin of the multi-feature gasket plate is taken as a design reference surface;

[0009] Secondly, the normal equal-thickness offset of the theoretical shape surface of the airplane is offset to the design reference surface by means of three-dimensional software, so that it is attached to the design reference surface, then the contour line of the multi-feature gasket plate is extracted and normally projected onto the shape surface, and a supplementary connecting area sight hole is designed at the outer contour edge of the multi-feature gasket plate;

[0010] Finally, the contour line of the multi-feature gasket plate projected onto the shape surface, the supplementary connecting area sight hole, and the positioning hole information of the skin on the tooling mold are used to trim the process data model surface; then the process data model surface is thickened to a process data model three-dimensional entity, the detail round corners are edited according to the tool condition, and finally it is detected whether the positioning hole error meets the gasket plate manufacturing and assembly tolerance requirements;

[0011] Step 2: Compile a numerical control machining program

[0012] According to the process data model three-dimensional entity to complete the NC machining program and simulation processing, optimize the tool path;

[0013] Step three, blanking

[0014] After completing the pre-commissioning inspection, according to the process data model three-dimensional entity to add the excess size, shear the blank, deburring and inspection, get the gasket part blank;

[0015] Step four, solid solution treatment and stretch forming

[0016] The gasket part blank is subjected to solid solution treatment, and is stretched longitudinally into a gasket part blank by using a numerical control skin stretching machine and installing a tooling mold. At least two positioning holes are processed on the gasket part blank at corresponding positions based on the original positioning holes on the tooling mold.

[0017] Step five, marking the gasket part blank, and then performing eddy current conductivity detection and hardness testing;

[0018] Step six, flexible clamping and five-coordinate sheet metal contour milling

[0019] The five-coordinate sheet metal milling and drilling machining center adopts a multi-point positioning mode of two points and one curved surface. The gasket part blank is clamped on the five-coordinate sheet metal milling and drilling, accurately positioned according to the positioning holes, and the gasket part blank is milled according to the numerical control machining program.

[0020] Step seven, manually trimming the area of the gasket part blank that is not milled to the line, and then performing semi-inspection;

[0021] Step eight, surface treatment, paint spraying, marking and inspection, to get the processed multi-feature gasket.

[0022] Further, the reference surface is the surface for forming the inner surface of the skin.

[0023] Further, in the normal projection, the contour line of the multi-feature gasket should include the contour lines of all features on the multi-feature gasket, including system through holes, irregular structure openings, and inner and outer contour lines.

[0024] Further, the design principle of the additional connection area sight hole is: for non-linear contour change areas, contour lines that are straight lines or approximately straight lines, and areas with contour notches, additional connection area sight holes are set, and reinforcing structures are set between adjacent additional connection area sight holes.

[0025] Further, the width of the additional connection area sight hole is not less than 25mm; the chord height between adjacent additional connection area sight holes is not greater than 0.3mm.

[0026] Furthermore, the process data model surface should completely encompass the shape surface, and the two sides of the process data model surface along its length direction should extend to the positioning hole areas on the left and right sides of the tooling mold.

[0027] Furthermore, the distance between the two sides of the curved surface of the process data model and the edge of the outline of the multi-feature pad should not be less than 300mm, but should not exceed the maximum shape of the tooling mold.

[0028] Furthermore, the requirement for the positioning hole error is that the deviation between the positioning hole and the projection point on the tooling mold or the process data model surface should be less than 0.15mm.

[0029] Furthermore, the remaining dimensions are 1.5m in the length direction and 0.2-0.3m in the width direction.

[0030] Furthermore, in the "two points and one surface" part, the two points are any two positioning holes machined on the blank of the pad part in step four, and the one surface refers to the surface of the tooling mold.

[0031] Furthermore, the five-axis sheet metal milling and drilling machining center adopts a two-point, one-surface multi-point flexible tooling positioning method and online detection of the vacuum adsorption of the multi-point flexible tooling.

[0032] Compared with the prior art, the present invention has the following technical features:

[0033] This method replaces the traditional manual cutting and forming process with allowance, realizing efficient and precise digital manufacturing of multi-feature pad parts. The process data model design, CNC stretching forming, flexible clamping, and CNC contour milling scheme in the method simplify the process flow of multi-feature pad machining, and achieve good machining quality and high production efficiency. Attached Figure Description

[0034] Figure 1 It is a multi-feature pad part;

[0035] Figure 2 It is a process data model;

[0036] Figure 3 It involves coordinating the process data model with the tooling mold positioning;

[0037] Figure 4 It is to add a connection area;

[0038] Figure 5 This is a schematic diagram of the chord height.

[0039] The labels in the diagram are as follows: 1-Tooling mold, 2-Process data model surface, 3-Multi-feature pad, 4-Positioning hole, 5-Additional connection area viewing hole. Detailed Implementation

[0040] Referring to the accompanying drawings, this invention provides a CNC machining method for a multi-feature pad. Analyzing the contour features of this pad: direct CNC machining not only lacks a positioning reference and suffers from poor local adhesion, making stretching impossible, but also easily leads to overcutting due to part vibration during flexible clamping. Therefore, a three-dimensional process data model needs to be designed before CNC machining to assist in the coordinated positioning, local reinforcement, flexible clamping, and CNC programming of the multi-feature pad. After the process data model is designed, the multi-feature pad is stretched into shape using a CNC skin stretching machine, then coordinated with the skin mold for positioning, and then the inner and outer contour features of the pad are CNC milled using a sheet metal contour milling machine. Finally, the connecting areas are manually trimmed and supplemented. A CNC machining method for a multi-feature pad includes the following steps:

[0041] Step 1: Design the process data model.

[0042] First, the forming surface of the tooling mold used to process the skin at the corresponding position of the multi-feature pad is taken as the design reference surface; wherein, the reference surface is the surface on which the inner shape of the skin is formed.

[0043] Secondly, using 3D software such as CATIA, the normal thickness of the aircraft's theoretical shape surface is offset to the design reference plane, ensuring it aligns with it. Then, the contour lines of the multi-feature pad are extracted and projected normally onto the shape surface. Additional connection area view holes are designed at the outer contour edge of the multi-feature pad. During normal projection, the contour lines of the multi-feature pad should include the contour lines of all features on the pad, including system through holes, irregular structural openings, and internal and external contours. The design principles for the additional connection area view holes are: additional connection area view holes are set for non-linear contour change areas, areas with straight or nearly straight contour lines, and areas with shape gaps; reinforcement structures, such as reinforcing ribs, are set between adjacent additional connection area view holes; the width of the additional connection area view holes is not less than 25mm; the chord height between adjacent additional connection area view holes is not greater than 0.3mm, making adjacent additional connection area view holes approximately a straight line for easy processing and cutting.

[0044] Finally, the process data model surface is trimmed by using the contour lines projected onto the outer surface of the multi-feature pad, the added connection area viewing holes, and the positioning hole information of the skin on the tooling mold; then the process data model surface is thickened to become a three-dimensional solid of the process data model, and the detailed fillets are edited according to the tooling situation (the fillet radius should not be less than the tool radius). Finally, the positioning hole error is checked to see if it meets the pad manufacturing and assembly tolerance requirements.

[0045] The process data model surface should completely encompass the shape surface, and the length of the process data model surface should extend to the positioning hole areas on the left and right sides of the tooling mold. The width of the process data model surface should be at least 300mm away from the edge of the outline of the multi-feature pad, but should not exceed the maximum shape of the tooling mold, so as to ensure that there is a sufficient adsorption and fixing area during subsequent five-axis sheet metal milling and prevent vibration overcutting caused by insufficient adsorption.

[0046] The positioning hole error is: the deviation between the positioning hole and the projection point on the tooling mold or the curved surface of the process data model should be less than 0.15mm.

[0047] Step 2: Compile CNC machining programs.

[0048] Based on the 3D solid model of the process data, complete the CNC machining program and simulate the machining process to optimize the tool path;

[0049] Step 3: Feeding.

[0050] After completing the pre-work inspection, the blank material is cut, deburred, and inspected according to the three-dimensional solid of the process data model after adding the allowance, to obtain the blank material of the pad plate part; the allowance dimension is 1.5m in the length direction and 0.2-0.3m in the width direction.

[0051] Step 4: Solution treatment and stretching.

[0052] The blank material of the pad plate part is subjected to solution treatment. Using a CNC skin stretching machine, the blank material is stretched longitudinally to form a blank plate part by installing a tooling die. Based on the original positioning holes on the tooling die, at least two positioning holes are machined on the blank plate part at corresponding positions for positioning in the subsequent five-axis sheet metal contour milling process.

[0053] Step 5: Mark the blank of the pad part, and then perform eddy current conductivity test and hardness test. After passing the test, proceed to the next step.

[0054] Step 6: Flexible clamping and five-axis sheet metal contour milling.

[0055] The five-axis sheet metal milling and drilling machining center adopts a two-point and one-curved-surface multi-point flexible tooling positioning method. The blank of the pad plate is clamped on the equipment, the vacuum adsorption of the multi-point flexible tooling is detected online, and the precise positioning is performed according to the positioning holes. The shape of the blank of the pad plate is milled according to the CNC machining program.

[0056] In the context of "two points and one surface", the two points refer to any two positioning holes machined on the blank of the pad part in step four, and the one surface refers to the curved surface of the tooling mold.

[0057] Step 7: After manually trimming the areas on the blank of the pad plate part that have not been milled to the line, perform a semi-inspection.

[0058] Step 8: Surface treatment, painting, marking and inspection to obtain the processed multi-feature pad.

Claims

1. A CNC machining method for a multi-feature pad, characterized in that, Includes the following steps: Step 1: Design process data model First, the forming surface of the tooling mold used to process the skin at the corresponding position of the multi-feature pad is taken as the design reference surface; Secondly, using 3D software, the normal thickness of the aircraft's theoretical shape surface is offset to the design reference plane so that it fits the design reference plane. Then, the outline of the multi-feature pad is extracted and projected onto the shape surface. Additional connecting area viewing holes are designed on the outer contour edge of the multi-feature pad. Finally, the process data model surface is trimmed by using the contour lines projected onto the outer surface of the multi-feature pad, the added connection area viewing holes, and the positioning hole information of the skin on the tooling mold; then the process data model surface is thickened to form a three-dimensional solid of the process data model, and the detailed fillets are edited according to the tooling situation. Finally, the positioning hole error is checked to see if it meets the pad manufacturing and assembly tolerance requirements. Step 2: Compile CNC machining programs Based on the 3D solid model of the process data, complete the CNC machining program and simulate the machining process to optimize the tool path; Step 3: Feeding After completing the pre-work inspection, the blank material is cut according to the dimensions of the three-dimensional solid of the process data model after adding the allowance, deburring and inspecting to obtain the blank material of the pad plate part. Step 4: Solution treatment and stretching. The blank material of the pad plate part is subjected to solution treatment. Using a CNC skin stretching machine, the blank material of the pad plate part is stretched longitudinally to form a blank material of the pad plate part by installing a tooling die. Based on the original positioning holes on the tooling die, at least two positioning holes are machined on the blank material of the pad plate part at the corresponding positions. Step 5: Mark the blank of the pad part, and then perform eddy current conductivity test and hardness test; Step Six: Flexible Clamping and Five-Axis Sheet Metal Contour Milling The five-axis sheet metal milling and drilling machining center adopts a two-point and one-surface multi-point positioning method. The blank of the pad part is clamped on the five-axis sheet metal milling and drilling machine, and the precise positioning is performed according to the positioning holes. The shape of the blank of the pad part is milled according to the CNC machining program. Step 7: After manually trimming the areas on the blank of the pad plate part that have not been milled to the line, perform a partial inspection; Step 8: Surface treatment, painting, marking and inspection to obtain the processed multi-feature pad.

2. The CNC machining method for a multi-feature pad according to claim 1, characterized in that, The reference surface is the surface used to shape the inner surface of the skin.

3. The CNC machining method for a multi-feature pad according to claim 1, characterized in that, When projected in the normal direction, the outline of the multi-feature pad should include the outlines of all features on the multi-feature pad, including system through holes, irregular structure openings, and internal and external outlines.

4. The CNC machining method for a multi-feature pad according to claim 1, characterized in that, The design principle of the supplementary connecting area viewing hole is as follows: supplementary connecting area viewing holes are set for non-linear contour change areas, areas with straight or nearly straight contour lines, and areas with shape gaps; and reinforcement structures are set between adjacent supplementary connecting area viewing holes.

5. The CNC machining method for a multi-feature pad according to claim 1, characterized in that, The width of the viewing hole in the supplementary connection area shall not be less than 25mm; the chord height between adjacent viewing holes in the supplementary connection area shall not be greater than 0.3mm.

6. The CNC machining method for a multi-feature pad according to claim 1, characterized in that, The process data model surface should completely encompass the outer shape surface, and the two sides of the process data model surface along its length should extend to the positioning hole areas on the left and right sides of the tooling mold.

7. The CNC machining method for a multi-feature pad according to claim 1, characterized in that, The distance between the two sides of the curved surface of the process data model and the edge of the outline of the multi-feature pad should not be less than 300mm, but should not exceed the maximum shape of the tooling mold.

8. The CNC machining method for a multi-feature pad according to claim 1, characterized in that, The requirement for the positioning hole error is that the deviation between the positioning hole and the projection point on the tooling mold or the curved surface of the process data model should be less than 0.15mm.

9. The CNC machining method for a multi-feature pad according to claim 1, characterized in that, The dimensions after the allowance are 1.5m in length and 0.2-0.3m in width.

10. The CNC machining method for a multi-feature pad according to claim 1, characterized in that, In the "two points and one surface" part, the two points are any two positioning holes machined on the blank of the pad part in step four, and the one surface refers to the curved surface of the tooling mold.

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