A numerical control machining method for composite forming die based on dynamic tool changing strategy

Abstract

The application discloses a kind of based on dynamic tool changing strategy's composite forming die numerical control processing method, it includes the following steps: S1: parameter setting;S2: using new tool along die profile finish machining one round or two sides, form the reference band of 15±2mm width, 0.03±0.01mm excess allowance;S3: with reference band as reference, layer by layer from outside to inside extension processing area, after each new tool, excess allowance of reference band is processed preferentially;S4: excess allowance detection of reference band: if excess allowance is completely removed, continue to process remaining area;If there is residual in excess allowance of reference band, immediately replace new tool, and repeat steps S2-S3;S3, S4 in:" first lift then drop " toolpath: tool is processed while descending.This application judges tool wear by the excess allowance of reference band, reduces invalid tool changing frequency, reduces cost;" first lift then drop " path eliminates tool joint step.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of numerical control machining, in particular to a composite forming die numerical control machining method based on a dynamic tool changing strategy. BACKGROUND

[0002] In the field of aerospace molds and the like, numerical control machining of composite forming molds often faces the following problems:

[0003] (1) Rapid tool wear: large profile size (such as length exceeding 20 m), long machining time, tool wear, and frequent tool changing leading to low machining efficiency.

[0004] (2) Tool joint step problem: there is a small deviation between the machining tracks of the new and old tools after tool changing, a step (height difference of about 0.05-0.1 mm) is easily generated at the tool joint, and secondary finishing by a fitter is required, affecting the surface quality and precision. Manual finishing of the step: depending on the experience of the fitter to polish the tool joint mark, which is low in efficiency and easy to damage the profile precision.

[0005] (3) Difficulty in controlling the allowance: the traditional method uses a fixed tool changing period, which cannot be adjusted according to the actual wear state, leading to residual allowance or overcut. Fixed period or frequency tool changing strategy: tool changing is forced according to time or machining length, but the actual tool wear state cannot be adapted, leading to unstable machining allowance. SUMMARY

[0006] The present application aims to overcome the deficiencies in the prior art and provide a composite forming die numerical control machining method based on a dynamic tool changing strategy, which is used for high-precision and low-tool joint mark machining of large composite forming die profiles, and is particularly suitable for machining of complex curved surface parts with strict profile tolerance requirements (±0.15 mm) and long machining paths.

[0007] The present application provides a machining method of dynamic tool changing and allowance self-adaptive control, which eliminates the tool joint step and reduces the workload of fitters by stage allowance machining, real-time tool wear judgment, and "first lifting and then descending" tool path; and by machining process optimization, the tool joint step caused by tool changing is reduced and the machining efficiency is improved under the premise of ensuring the ±0.15 mm tolerance.

[0008] In order to achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0009] A composite forming die numerical control machining method based on a dynamic tool changing strategy, comprising the following steps:

[0010] S1: parameter setting: the tool is a 16 mm ball nose milling cutter, the cutting speed is 3000±200 mm / min, the feed rate is 0.5±0.1 mm; the width of the reference band is 15±2 mm, and the allowance is 0.03±0.01 mm; S2: tool changing: the tool is changed according to the tool wear state, and the tool changing frequency is 1-3 times;

[0011] S2: using a new tool to process the reference strip, a margin detection area is generated;

[0012] First processing: using a new tool to finish one side or both sides along the mold profile, forming a reference strip with a width of 15±2mm and a margin of 0.03±0.01mm;

[0013] S3: subsequent processing: taking the reference strip as a reference, the processing area is expanded layer by layer from the outside to the inside, and the margin is processed first after replacing the new tool each time;

[0014] S4: detection of the margin of the reference strip: if the margin is completely removed, that is, the detected margin is <0.03mm, continue to process the remaining area; if the margin is not removed, that is, the detected margin is ≥0.03mm, it is determined that the tool has been worn out, and a new tool is immediately replaced, and steps S2-S3 are repeated.

[0015] Further, in steps S3 and S4, the "first lifting and then descending" tool path: when replacing the tool, the old tool is lifted by 0.05-0.1mm at the end of the path and then retreated; the new tool is lowered by 0.05-0.1mm from the lifting point and then cut in, and the programmed original path is repeated to process a 10mm wide processing area, and the tool is processed while descending, wherein every 2mm width is lowered by 0.01-0.02mm, so that the tool can smoothly reach the 0 position of the profile and be processed, and smooth transition at the tool replacement or joint is ensured.

[0016] Further, in step S4, the margin is monitored in real time by a laser sensor.

[0017] Further, the composite forming mold is an aircraft composite skin mold.

[0018] The composite forming mold numerical control machining method based on a dynamic tool replacement strategy is a machining method of dynamic tool replacement and margin self-adaptive control, which eliminates the joint steps and reduces the workload of benchwork through phased margin processing, real-time tool wear judgment (dynamic tool replacement strategy) and "first lifting and then descending" tool path; through process optimization, the joint steps caused by tool replacement are reduced and the machining efficiency is improved under the premise of ensuring a ±0.15mm tolerance.

[0019] In the present application, the margin control of the reference strip: by fixing the width of the margin strip as the tool wear detection area, the real-time judgment of the wear state is realized; the dynamic tool replacement trigger mechanism: taking whether the margin is removed as the basis for tool replacement, replacing the fixed period tool replacement, reducing the number of invalid tool replacement times. Z-axis lifting and lowering path optimization: by lifting and lowering, the height mutation at the tool replacement point is eliminated, and the joint step is avoided.

[0020] This invention presents a CNC machining method for composite forming molds based on a dynamic tool change strategy. This method uses the margin to dynamically determine tool wear, reducing ineffective tool changes and lowering costs. A "lift-first, then lower" approach eliminates tool-jointing steps. This method is suitable for high-precision machining of large composite molds and aerospace components, achieving surface roughness Ra ≤ 1.6 μm and a tolerance of ±0.15 mm for workpieces as large as 20 mm. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Schematic diagram of the reference band of the composite forming mold surface of the present invention;

[0022] Figure 2 This is a schematic diagram of the principle of the composite forming die surface processing tool of the present invention when it is not worn;

[0023] Figure 3 This is a schematic diagram showing the principle of wear of the tool used in machining the composite forming die surface of the present invention;

[0024] Figure 4 This is a schematic diagram of the principle of tool change during surface machining of a composite forming die according to the present invention;

[0025] Figure 5 This is a schematic diagram of the principle of the composite forming mold surface processing results of the present invention;

[0026] Figure 6 It is a schematic diagram of the principle of the surface processing results of the composite forming mold in the prior art. DETAILED DESCRIPTION

[0027] To make the technical solution and its advantages of the present invention more clear, the technical solution of the present invention will be further described in detail below in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only some embodiments of the present invention and are only used to explain the present invention, not to limit the present invention. It should be noted that, for ease of description, the accompanying drawings only show the parts or structures related to the present invention. Other related parts can refer to the general design. In the absence of conflict, the embodiments of the present invention and the technical features in the embodiments can be combined with each other to obtain new embodiments.

[0028] All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort shall fall within the scope of protection of the present invention. Furthermore, unless otherwise defined, technical or scientific terms used in the description of the present invention shall have the same meanings as those generally understood by persons of ordinary skill in the art to which the present invention belongs.

[0029] The present invention will be described in further detail below with reference to the accompanying drawings.

[0030] like Figure 1-6As shown, a CNC machining method for a composite forming mold based on a dynamic tool change strategy includes the following steps:

[0031] S1: Parameter setting: Tool is 16mm ball end mill, cutting speed about 3000mm / min (2800-3200mm / min), feed rate about 0.5mm (0.4-0.6mm); the width of the reference band is about 15mm (15±2), and the allowance is about 0.03mm (0.03±0.01);

[0032] S2: Use the new tool to process the reference zone and generate the allowance detection area;

[0033] First processing: Use a new tool to finish machining along the outer contour of the mold surface for one circle or two sides to form a reference band with a width of 15±2mm and a margin of 0.03±0.01mm;

[0034] S3: Subsequent processing: With the reference band as a reference, the processing area or profile is expanded layer by layer from the outside to the inside, and the allowance is processed or cut first after each new tool is replaced;

[0035] S4: Detection of the reference band allowance: If the allowance is completely removed, that is, the detection allowance is less than 0.03mm, continue processing the remaining area or surface; if the allowance is not removed and there is a residual allowance, that is, the detection allowance is ≥0.03mm, it is determined that the tool is worn, and a new tool is immediately replaced, and steps S2-S3 are repeated.

[0036] In steps S3 and S4: "Lift first and then lower" tool path: when changing the tool, the old tool is lifted 0.05-0.1mm at the end point of the path and then retracted; the new tool is lowered 0.05-0.1mm from the lifting point and then cuts in, and repeats the processing of a processing area with a width of about 10mm according to the original programmed path. The tool descends while processing, and descends 0.01-0.02mm for every 2mm of width processed, so that it can slide evenly and smoothly to the 0 position of the mold surface and process, ensuring a smooth transition at the tool change or tool connection.

[0037] In step S4: the remaining amount of the reference tape is monitored in real time by a laser sensor.

[0038] The composite forming mold is an aircraft composite skin mold.

[0039] When the method of the present invention is not used: according to existing experience, the tool is changed every 2 hours, or the tool sharpening amount is manually re-checked (the Z value benchmark is re-compared with the original Z value before processing, if it is less than 0.03mm, continue processing, if it is greater than 0.03mm, change the tool).

[0040] After using the method of the present invention: using this method to visually detect tool change, whenever the margin of the reference band has not been milled off, the tool is changed, and the average tool change time is about 3-4.5 hours, which reduces manual intervention and also reduces the tool connection step and error of the profile.

[0041] The present invention provides a CNC machining method for composite forming molds based on a dynamic tool change strategy. It is a machining method that combines dynamic tool change with adaptive allowance control. Through staged allowance machining, real-time judgment of tool wear (dynamic tool change strategy), and a "lift first, then lower" tool path, it eliminates tool connection steps and reduces the workload of fitter finishing. Through machining process optimization, it reduces tool connection steps caused by tool change and improves machining efficiency while ensuring a tolerance of ±0.15mm.

[0042] In this invention, the reference band stock control utilizes a fixed-width stock band as a tool wear detection zone, enabling real-time assessment of tool wear status. A dynamic tool change trigger mechanism uses the removal of the reference band stock as the basis for tool change, replacing fixed-cycle tool changes and reducing ineffective tool changes. Z-axis lift-and-drop path optimization eliminates sudden height changes at the tool change point and avoids tool-connection steps by utilizing tool lift avoidance and tool lowering.

[0043] This invention presents a CNC machining method for composite forming molds based on a dynamic tool-changing strategy. This method dynamically determines tool wear by measuring the residual thickness of a reference band, reducing ineffective tool changes and lowering costs. A "lift-then-lower" approach eliminates tool-jointing steps. This method is suitable for high-precision machining of large composite molds and aerospace components, achieving surface roughness Ra ≤ 1.6 μm and a tolerance of ±0.15 mm for workpieces as large as 20 mm.

[0044] The above-mentioned embodiments are illustrative of the present invention, not limiting thereof. It is understood that various changes, modifications, substitutions and variations may be made to these embodiments without departing from the principles and spirit of the present invention. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A CNC machining method for a composite forming mold based on a dynamic tool change strategy, comprising the following steps: S1: Parameter setting: Tool is 16mm ball end mill, cutting speed 3000±200mm / min, feed 0.5±0.1mm; width of reference band 15±2mm, allowance 0.03±0.01mm; S2: Use the new tool to process the reference zone and generate the allowance detection area; First processing: Use a new tool to finish process one circle or both sides along the outer contour of the mold surface to form a reference band with a width of 15±2mm and a margin of 0.03±0.01mm; S3: Subsequent processing: With the reference band as a reference, the processing area is expanded from the outside to the inside layer by layer, and the allowance is processed first after each new tool is replaced; S4: Check the allowance of the reference belt: If the allowance is completely removed, that is, the allowance is less than 0.03mm, continue processing the remaining area; if the allowance is not removed and there is some residual allowance, that is, the allowance is greater than or equal to 0.03mm, it is determined that the tool is worn, and a new tool is immediately replaced, and steps S2-S3 are repeated. Among them, in steps S3 and S4: "First lift, then lower" tool path: When changing the tool, the old tool is lifted 0.05-0.1mm at the end point of the path and then retracted; the new tool is lowered 0.05-0.1mm from the lifting point and then cuts in, repeating the processing of the 10mm wide processing area according to the original programmed path. The tool is lowered while processing, and it is lowered 0.01-0.02mm for every 2mm of width processed. It can slide evenly and smoothly to the 0 position of the mold surface and process, ensuring a smooth transition at the tool change or tool connection.

2. A CNC machining method for composite forming molds based on a dynamic tool change strategy according to claim 1, characterized in that: In step S4: the residual amount is monitored in real time by a laser sensor.

3. A CNC machining method for composite forming molds based on a dynamic tool change strategy according to claim 2, characterized in that: The composite forming mold is an aircraft composite skin mold.

4. A CNC machining method for composite forming molds based on a dynamic tool change strategy as claimed in claim 3, characterized in that: Reference band margin control: The margin is used as a tool wear detection area to achieve real-time judgment of the wear status; dynamic tool change trigger mechanism: The tool change is based on whether the margin is cut off, replacing the fixed cycle tool change and reducing the number of ineffective tool changes; Optimization of the Z-axis lifting and lowering path: By lifting the tool to avoid and lowering the tool to cut in, the sudden change in height of the tool change point is eliminated and the tool connection step is avoided.

5. The CNC machining method for composite forming molds based on a dynamic tool change strategy according to claim 4, characterized in that: It is suitable for high-precision processing of large composite material molds and aerospace structural parts, and can achieve the processing requirements of 20m large workpiece surface roughness Ra≤1.6μm and tolerance ±0.15mm.

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