阅读说明：本技术 一种用于周向无基准的复材零件机械加工的方法 (Method for machining composite part without reference in circumferential direction ) 是由 潘春林 何凯 赵砚 严方超 陈志霞 黎玉钦 郭渊 杨春 华文龙 任慧敏 于 2019-09-19 设计创作，主要内容包括：本发明公开了一种用于周向无基准的复材零件机械加工的方法,包括以下步骤：步骤一：建立机加坐标系；步骤二：初定位三个辅助基准不合格的情况下验证坐标系,通过逆向反推后的三个辅助基准孔实际值建立坐标系,重新测量零件特征,保证在此坐标系下,测量结果合格,送至五轴机加且三个基准孔实际值作为正式基准孔作为机加坐标系的基准；步骤三：机加；步骤四：最终测量,以四个基准孔建立坐标系。测量所有立筋轴线度,腹板表面立筋的轴线度要求为±1mm,测量腹板和外缘翻边轮廓度,轮廓度要求为0.75mm,测量装配定位孔位置度,定位孔位置度要求为0.3mm,测量工艺孔孔径,孔径大小公差要求参考HB7741标准。(The invention discloses a method for machining a composite part without reference in the circumferential direction, which comprises the following steps: the method comprises the following steps: establishing a machine-to-machine coordinate system; step two: verifying a coordinate system under the condition that the three auxiliary references are unqualified in initial positioning, establishing the coordinate system through the actual values of the three auxiliary reference holes subjected to reverse back-pushing, re-measuring the characteristics of the part, ensuring that the measurement result is qualified in the coordinate system, and sending the measured result to a five-axis machining tool and taking the actual values of the three reference holes as formal reference holes as references of the machining tool coordinate system; step three: machining; step four: and finally, measuring, and establishing a coordinate system by using four reference holes. The axial degree of all studs is measured, the axial degree requirement of studs on the surface of a web is +/-1 mm, the profile degree requirement of flanges on the web and the outer edge is 0.75mm, the position degree of an assembly positioning hole is measured, the position degree of the positioning hole is required to be 0.3mm, the aperture of a process hole is measured, and the requirement of aperture size tolerance is referred to HB7741 standard.)

1. A method for machining a circumferentially-dawless composite part, comprising the steps of:

the method comprises the following steps: establishing a machine-to-coordinate system, comprising the following detailed steps: 1. positioning the composite material part by adopting an auxiliary primary positioning device of a cutting and drilling tool, performing primary positioning through web ribs, and finally performing primary verification through scribing lines on the surface of the part; 2. placing the part position under a cutting and drilling tool coordinate system, and combining the part position with the machining addend simulation; 3. machining three auxiliary reference holes outside the allowance area of the part and giving coordinate theoretical values of the three auxiliary reference holes under the current digital analogy; 4. measuring by three coordinates, wherein the measuring reference is three auxiliary reference holes, and establishing a coordinate system by adopting an iteration method; 5. according to the qualified measurement result, the theoretical values of the three reference holes are sent to a five-axis machining device and serve as formal reference holes to serve as the reference of a machining coordinate system;

step two: verifying a coordinate system under the condition that the three auxiliary references are unqualified in initial positioning, establishing the coordinate system through the actual values of the three auxiliary reference holes subjected to reverse back-pushing, re-measuring the characteristics of the part, ensuring that the measurement result is qualified in the coordinate system, and sending the measured result to a five-axis machining tool and taking the actual values of the three reference holes as formal reference holes as references of the machining tool coordinate system;

step three: machining, namely, establishing a coordinate system through the three verified auxiliary reference holes to perform formal four reference hole machining, wherein the coordinate system is established by the formal four reference holes in the subsequent machining process to perform machining and measurement;

step four: final measurement, a coordinate system is established with four reference holes: the axial degree of all studs is measured, the axial degree requirement of studs on the surface of a web is +/-1 mm, the profile degree requirement of flanges on the web and the outer edge is 0.75mm, the position degree of an assembly positioning hole is measured, the position degree of the positioning hole is required to be 0.3mm, the aperture of a process hole is measured, and the requirement of aperture size tolerance is referred to HB7741 standard.

2. The method for machining a circumferential non-reference composite material part as claimed in claim 1, wherein the detailed step of establishing the machining coordinate system in the step one is to measure the axial degree of the stud, the axial degree of the stud is required to be +/-1 mm, and the profile degree of the web plate or the outer edge flanging is required to be 0.75 mm.

3. The method for machining a circumferential non-reference composite material part as claimed in claim 1, wherein in the detailed step five of establishing the machining coordinate system in the step one, if the measurement result is unqualified, the coordinate system is rotated and biased according to the deviation of the stud and the deviation value of the profile tolerance, reverse calculation is performed to ensure that the measurement result is qualified, and then the actual values of the three auxiliary reference holes are measured under the current coordinate system.

Technical Field

The invention relates to the technical field of advanced composite material manufacturing, in particular to machining and manufacturing of high-performance carbon fiber composite material structural parts in the industries of aircrafts, spacecrafts and automobiles.

Background

The resin-based carbon fiber composite material has the advantages of high specific strength and specific stiffness, high structural integration, strong designability, good fatigue fracture resistance, corrosion resistance, good dimensional stability and the like, and is a high-performance structural material widely applied in the fields of aviation, aerospace, traffic and the like.

With the increasing requirements on the strength and rigidity of composite material parts, the structures of the parts are more and more complex, wherein a circular frame with a circumferential disc and a stud structure is one of typical structural members. The processing and detection benchmark of product can not be made in the compound material forming process in this kind of part, has stud or turn-ups structure on circumference compound material flat plate, and when making this kind of part, the position of stud each other, because of the assembly accuracy requirement, the relative position degree requirement of locating hole and other fabrication holes that machine adds to the stud is more strict usually.

The traditional metal processing mode is that a datum is directly processed on a metal body, the metal body is cut according to the datum and a digital-analog program, and the metal body is directly cut and formed. All features are machined. The composite material is characterized in that the composite material is formed, and the machining part only cuts off the redundant parts except the clean side line and the allowance line of the surface of the part without cutting the surface of the part. The features of the part are not machined but are directly molded. So the composite material machining and metal machining processes are different.

In a general composite material machining mode, a part product is manufactured through a drilling die hole on a composite material forming tool and is placed in a positioning pin hole on a machining device for positioning, and the part product and the machining device are overlapped. And establishing a coordinate system by adopting a datum hole of a machining tool, and machining.

The circumferential non-reference composite material part has 79 frames and 80 frames, and is a general name of 919 airplanes and a general name in the industry, and two important key parts. The main structures of the two parts belong to the type of a plane web plate with ribs, and when the composite material of the parts is paved and formed, a drill die hole cannot be additionally formed on a web plate forming tool for ensuring the air tightness of the forming tool. The datum hole features cannot be established during and after the composite material forming process.

At present, a method of adding ribs and part surface lines is adopted to verify a coordinate system. However, the accuracy requirement of the ribs is that the profile tolerance is +/-1 mm, and when the position is limited, a part of the ribs are adopted, so that the actual positions of all the ribs cannot be completely reflected, and the phenomenon of approximate completion exists. The score lines on the surface of the part will also vary in position as the coefficient of expansion of the part varies. Therefore, the repeated precision of the positioning mode is very poor, and the positioning is inaccurate, and in this case, the reference hole processed by positioning causes great errors to the machining positioning and measuring results in the later period.

Disclosure of Invention

The invention aims to provide a method for reversely determining a datum positioning machining of a circumferential non-datum composite part, the main structure of the circumferential non-datum composite part belongs to a type of a plane web plate and ribs, and when the composite material of the part is paved and molded, a drilling die hole cannot be formed on a web plate molding tool in order to ensure the air tightness of the molding tool, so that the datum hole characteristic cannot be established in and after the composite material molding process. The accurate processing of the reference hole is completed by using three-coordinate measurement or machining online measurement, so that the problem that the product is scrapped due to no reference of parts or subsequent machining errors caused by reference errors is solved.

The technical scheme of the invention is as follows: a method for machining a circumferentially-dawless composite part, comprising the steps of:

the method comprises the following steps: establishing a machine-to-machine coordinate system,

the detailed steps are as follows: 1. positioning the composite material part by adopting an auxiliary primary positioning device of a cutting and drilling tool, performing primary positioning through web ribs, and finally performing primary verification through scribing lines on the surface of the part; 2. placing the part position under a cutting and drilling tool coordinate system, and combining the part position with the machining addend simulation; 3. machining three auxiliary reference holes outside the allowance area of the part and giving coordinate theoretical values of the three auxiliary reference holes under the current digital analogy; 4. measuring by three coordinates, wherein the measuring reference is three auxiliary reference holes, and establishing a coordinate system by adopting an iteration method; 5. and (4) according to the qualified measurement result, sending the theoretical values of the three reference holes to a five-axis machining machine as a formal reference hole as a reference of a machining coordinate system.

Step two: and verifying a coordinate system under the condition that the three auxiliary references are unqualified in initial positioning, establishing the coordinate system through the actual values of the three auxiliary reference holes subjected to reverse backward thrust, re-measuring the characteristics of the part, ensuring that the measurement result is qualified in the coordinate system, and sending the measured result to a five-axis machining tool and taking the actual values of the three reference holes as formal reference holes as references of the machining coordinate system.

Step three: and machining, namely establishing a coordinate system through the verified three auxiliary reference holes to perform formal four reference hole machining. The subsequent machining process is to establish a coordinate system by the formal four reference holes for machining and measurement.

Step four: final measurement, a coordinate system is established with four reference holes: the axial degree of all studs is measured, the axial degree requirement of studs on the surface of a web is +/-1 mm, the profile degree requirement of flanges on the web and the outer edge is 0.75mm, the position degree of an assembly positioning hole is measured, the position degree of the positioning hole is required to be 0.3mm, the aperture of a process hole is measured, and the requirement of aperture size tolerance is referred to HB7741 standard.

And in the detailed step four of establishing the machine-added coordinate system in the step one, the axial degree of the stud needs to be measured, the requirement of the stud is +/-1 mm, and the requirement of the profile degree of the web plate or the profile degree of the flange at the outer edge and the profile degree of the flange at the outer edge is 0.75 mm.

And in the detailed step five of establishing the machine-machining coordinate system in the step one, if the measurement result is unqualified, rotating and biasing the coordinate system according to the deviation of the stud and the deviation value of the profile tolerance, and performing reverse calculation. And ensuring that the measurement result is qualified, and then measuring the actual values of the three auxiliary reference holes in the current coordinate system.

The invention aims to finish the accurate processing of the reference hole by using three-coordinate measurement or machine-on-line measurement, and has the following advantages:

(1) the situations of poor positioning accuracy, poor repeatability, low processing precision and low product percent of pass in the prior art are eliminated.

(2) Need not to add the inspection frock, later stage accessible on-line measuring is fixed a position fast, and fixes a position accurately, and the precision is high.

(3) And an auxiliary inspection datum hole is added in the product allowance area, so that the final structure and the shape of the product are not damaged.

(4) The measurement verification can be repeated, and the datamation, the scientization and the rationalization are realized.

Drawings

FIG. 179 is a schematic view of the initial positioning of an auxiliary tool on a cutting and drilling tool;

FIG. 279 is a schematic view of three auxiliary reference holes in the margin area and four common reference positions machined after verifying that the coordinates are correct;

FIG. 379 is a digital-analog diagram of the rear course stud and web assembly after machining of the product;

FIG. 479 is a schematic view of a front course face stud and web integral digital-analog after machining of the product;

FIG. 580 is a schematic view of the initial positioning of the cutting and drilling tool using the auxiliary tool;

FIG. 680 is a schematic diagram of reference positions of three auxiliary reference primary holes and a final hole machined after verifying that coordinates are correct, as shown in FIG. 1;

FIG. 780 is a schematic view of a reference position of three auxiliary reference primary holes and a final hole machined after verifying that the coordinates are correct, as shown in FIG. 2;

FIG. 880 is a schematic diagram of the product after all machining processes are completed.

Detailed Description

The invention is further illustrated with reference to the accompanying drawings. A method for reversely determining a datum positioning machining of a composite material part without a datum in the circumferential direction enables a product which cannot accurately establish a datum to establish an accurate datum mode through primary positioning and measurement reverse engineering, and lays a foundation for machining precision.