阅读说明：本技术 一种零件表面缺损区域模块化增减材复合修复方法 (Modular material-increasing and material-decreasing composite repair method for defect area of part surface ) 是由 卞荣 黄家才 丁文政 史建军 黄亚洲 侯军明 陈勇 牟娟 于 2019-10-28 设计创作，主要内容包括：一种零件表面缺损模块化增减材复合修复方法,涉及机械加工的技术领域。其主要过程包括对零件表面缺损区域进行三维扫描,获取待修复区域的点云数据；根据点云数据计算缺损区域的特征参数；根据特征参数选取相应的几何模块；对缺损区域进行模块化铣削去除加工,获得规则待修复区域；对待修复区域进行模块化激光熔敷修复；对激光修复表面进行精密铣削加工,完成修复。本发明通过增减材复合方式,将复杂不规则的缺损形貌修整为规则几何体,在此基础上对模块化的待修复几何体进行激光熔敷修复,路径规划方便快捷,从而整体提高修复效率。此外,对激光熔敷区域的精密铣削加工可以保持修复表面形状轮廓的修复精度,同时也提高修复表面的使用性能。(A modularized material-increasing and material-decreasing composite repair method for part surface defect relates to the technical field of machining. The method mainly comprises the steps of carrying out three-dimensional scanning on a defective area on the surface of a part to obtain point cloud data of an area to be repaired; calculating characteristic parameters of the defect area according to the point cloud data; selecting a corresponding geometric module according to the characteristic parameters; carrying out modular milling removal processing on the defect area to obtain a regular area to be repaired; performing modular laser cladding repair on an area to be repaired; and (5) carrying out precision milling processing on the laser repairing surface to finish repairing. According to the method, the complex and irregular defect appearance is trimmed into the regular geometric body in a material increasing and decreasing composite mode, the modular geometric body to be repaired is repaired by laser deposition on the basis, the path planning is convenient and fast, and therefore the repairing efficiency is integrally improved. In addition, the precision milling processing of the laser cladding area can maintain the repair precision of the shape and the outline of the repair surface and simultaneously improve the service performance of the repair surface.)

1. A modular material-increasing and material-decreasing composite repairing method for part surface defect comprises the following steps:

(1) placing the part to be repaired on a workbench, and enabling the surface of the area I to be repaired to be upward;

(2) carrying out laser three-dimensional scanning on the area I to be repaired and the periphery thereof to obtain point cloud data of the defect part and the peripheral area, and scanning a coordinate reference point;

(3) calculating the point cloud data of the defect part and the surrounding area obtained in the step (2) to obtain characteristic parameters of the defect part;

(4) estimating the normal vector of the original surface of the defect region according to the point cloud data of the defect part and the surrounding region obtained in the step (2); selecting a regular envelope geometric module suitable for the defect region according to the characteristic parameters in the step (3), wherein the envelope geometric module is used as a characteristic module;

(5) milling the area I to be repaired, and processing the defect area into the shape of the characteristic module selected in the step (4) to obtain a repair area II;

(6) performing laser 3D printing repair on the repair area II obtained in the step (5), wherein the repair height is slightly higher than the peripheral surface to form a repair area III;

(7) and (5) carrying out precision milling on the surface of the repair area III in the step (6), removing redundant repair materials, obtaining a smooth surface, obtaining a repair surface IV, and completing repair.

2. The modular material-increasing and material-decreasing composite repairing method for the surface defect of the part according to claim 1, characterized in that: in the step (3), when the characteristic parameters of the defect part are obtained, calculating the diameter D of the circumscribed circle according to the size of the normal projection area of the defect area along the curved surface; and calculating the repair depth h according to the normal maximum depth of the defect area along the curved surface.

3. The method for repairing surface defects of parts by composite increase and decrease as claimed in claim 1 or 2, wherein: in the step (5), the milling tool is a ball-end milling cutter, the diameter D ' of the milling area is lambda times of the diameter D of the circumcircle of the defect part, the lambda is 1.2-1.5, the milling depth is h ', and the h ' is lambda times of the repairing depth h.

4. The method for repairing surface defects of parts by composite increase and decrease as set forth in claim 3, wherein: in the step (6), 3D printing repair is carried out on the repair area II, and a powder spraying laser cladding material increase processing method is adopted; the repair depth is slightly higher than the milling depth h' by 0.8mm to 1.5 mm.

5. The method for repairing surface defects of parts by increasing or decreasing composite method according to claim 1, wherein: in the step (7), the precision milling tool is a ball end mill.

Technical Field

The invention relates to the technical field of machining, in particular to the technical field of a material increasing and decreasing composite repairing method for a defective area of a part surface.

Background

The precious parts such as airplane structural parts, engine parts, precision gears and metal molds have some excessive cutting and damage on the surfaces during the production and manufacturing process, which results in the rejection. Or the bearing surface or the contact area of the parts can be damaged to different degrees after the parts are used for a period of time, so that the parts cannot be used continuously. Since these parts are generally expensive, the production process is also complicated, and the whole part is scrapped as a result of some surface damage, which often causes great economic loss and resource waste.

With the increasing progress of material technology and laser technology, additive manufacturing technology based on laser sintering, namely laser 3D printing technology, has been increasingly applied in aerospace, automobile, mold, medical and other industries. As an advanced manufacturing technique, it first needs to obtain a digitized model of the manufactured object and layer the model. And then the fractal material is sent to a target position through a powder sending mechanism, is formed through laser irradiation or sintering (the metallic material needs to be sintered), and finally forms a complete object part through layer-by-layer accumulation. The technical characteristics of the method provide a feasible solution for surface repair of metal parts. At present, laser 3D printing has more applications in the field of repair of surface damage of parts.

The authorization notice number CN105598450B discloses a laser three-dimensional copying repair method for part damage, which comprises the following steps of (1) three-dimensionally scanning the appearance of a standard part corresponding to the damaged part to establish a standard structure model, (2) three-dimensionally scanning the appearance of the damaged part to establish an actual structure model of the damaged part, (3) comparing the standard structure model and the actual structure model to obtain a repair area structure model completely corresponding to a damaged area, and (4) controlling laser three-dimensional copying equipment to perform laser cladding repair on the damaged area of the damaged part according to the repair area structure model. The method can carry out precise repair on metal or nonmetal parts under the condition of ensuring higher precision, the repair size is closer to the original size, the subsequent machining time can be saved, the repair period is shortened, and meanwhile, the repair material is metallurgically bonded with the original damaged part, so that the bonding force is strong, the performance stability is high, the yield is high, and the method has wide popularization and application prospects. However, this method needs to compare the actual model of the object with the original model to obtain the data of the region to be repaired. This approach has certain limitations when faced with repair objects that cannot provide the original model.

The publication No. CN104651832B discloses a surface repairing process for large metal parts, which mainly comprises the following steps: (1) the method comprises the steps of (1) associating process parameters of a laser cladding nozzle with a powder beam convergence length at an outlet of the laser cladding nozzle, (2) establishing a three-dimensional model, (3) generating a scanning track path of the laser cladding nozzle, determining the maximum inclination angle of the laser cladding nozzle, selecting the process parameters of the laser cladding nozzle and the powder beam convergence length according to the association relationship established in the step (1), and controlling the laser cladding nozzle to repair the surface of a metal part to be repaired according to the scanning track path generated in the step (3). In the repair process, the laser cladding nozzle can continuously move in a posture-changing manner, so that the axial direction of the laser cladding nozzle is always kept to be coincident with the normal direction of the surface of the repaired part, the surface of a large part and equipment is rapidly repaired by laser cladding, and the complex workload of carrying and clamping a workpiece before repair is reduced. However, the method does not relate to the relevant description of the pretreatment of the area to be repaired, and only refers to the establishment of a three-dimensional model. When facing a complex area to be repaired with large and frequent curvature change, the laser cladding nozzle needs to frequently swing to keep the axial direction of the nozzle coincident with the normal direction of the surface of the repaired area.

Disclosure of Invention

The invention provides a modular increase-decrease composite repair method for local damage of parts by combining technologies such as numerical control machining, three-dimensional measurement and laser deposition (laser 3D printing), and improves the repair efficiency and repair quality of part surface calculation under the condition of overcoming the defects of the prior art.

A modular material-increasing and material-decreasing composite repairing method for part surface defect comprises the following steps:

(1) placing the part to be repaired on a workbench, and enabling the surface of the area I to be repaired to be upward;

(2) carrying out laser three-dimensional scanning on the area I to be repaired and the periphery thereof to obtain point cloud data of the defect part and the peripheral area, and scanning a coordinate reference point;

(3) calculating the point cloud data of the defect part and the surrounding area obtained in the step (2) to obtain characteristic parameters of the defect part;

(4) estimating the normal vector of the original surface of the defect region according to the point cloud data of the defect part and the surrounding region obtained in the step (2); selecting a regular envelope geometric module suitable for the defect region according to the characteristic parameters in the step (3), wherein the envelope geometric module is used as a characteristic module;

(5) milling the area I to be repaired, and processing the defect area into the shape of the characteristic module selected in the step (4) to obtain a repair area II;

(6) performing laser 3D printing repair on the repair area II obtained in the step (5), wherein the repair height is slightly higher than the peripheral surface to form a repair area III;

(7) and (5) carrying out precision milling on the surface of the repair area III in the step (6), removing redundant repair materials, obtaining a smooth surface, obtaining a repair surface IV, and completing repair.

By adopting the technical scheme, compared with the prior art, the invention has the following advantages:

1. different from the prior art, the method obtains the characteristic data of the damaged area on the surface of the part by means of the three-dimensional measurement technology, modularly removes the original damaged area with irregular shape and complex appearance according to the characteristics, and forms the to-be-repaired geometric body with simple shape and modularization. On the basis, the modularized geometric body to be repaired is repaired by laser deposition, and the path planning is convenient and fast, so that the repairing efficiency is integrally improved.

2. The invention can preset milling programs and laser cladding programs of various geometric modules, can directly call the preset programs aiming at different repair modules, can realize the repair process of rapid material increase and decrease only by modifying the characteristic parameters of the modules, and improves the repair efficiency.

3. The invention utilizes the milling cutter to carry out precise milling and removal on redundant repair protruding areas, can keep the repair precision of the shape and the outline of the repair surface, simultaneously obtains high quality of the processed surface, and removes the thermal stress influence on the material in the laser cladding process. The material in the surface repairing area is mechanically rolled in the precise milling process, so that a certain compressive stress is formed on the surface, the geometric precision of the repaired surface is ensured, and the service performance of the repaired surface is improved.

Drawings

FIG. 1 is a flow chart of the repair method of the present invention.

Fig. 2 a-2 d are schematic diagrams of an implementation process of a spherical surface repairing module as an example by using the modification method of the present invention.

Fig. 2a is a schematic cross-sectional view of a defect surface.

Fig. 2b is a schematic cross-sectional view of a spherical modular milling trim.

Fig. 2c is a schematic cross-sectional view of the milled area after laser cladding repair.

FIG. 2d is a schematic cross-sectional view of the repaired surface after precision milling.

Fig. 3a is a schematic view of a defect surface repair using a spherical module.

Fig. 3b is a schematic cross-sectional view of fig. 3 a.

Figure 4a is a schematic view of the repair of a defect surface using a slot module.

Fig. 4b is a schematic cross-sectional view of fig. 4 a.

Wherein: 101-original surface, 102-defect area cross section morphology, 103-defect area circumcircle diameter D, 104-defect area maximum depth h, 201-milling surface, 202-milled surface area diameter D ', 203-milled area depth h', 204-milled spherical radius R, 205-milled spherical center, 301-to-be-repaired sphere module, 302-repair protrusion height t, 303-laser cladding repair surface, 401-peripheral intact area surface, 402-precisely milled repair surface; 501-length parameter of defect area, 502-width parameter of defect area, 601-length parameter of groove after milling, 602-width parameter of groove after milling.

Detailed Description

A modular material-increasing and material-decreasing composite repairing method for part surface defect comprises the following steps:

(1) placing the part to be repaired on a workbench, and enabling the surface of the area I to be repaired to be upward;

(2) carrying out laser three-dimensional scanning on the area I to be repaired and the periphery thereof to obtain point cloud data of the defect part and the peripheral area, and scanning a coordinate reference point;

(3) calculating the point cloud data of the defect part and the surrounding area obtained in the step (2) to obtain characteristic parameters of the defect part;

(4) estimating the normal vector of the original surface of the defect region according to the point cloud data of the defect part and the surrounding region obtained in the step (2); selecting a regular envelope geometric module suitable for the defect region according to the characteristic parameters in the step (3), wherein the envelope geometric module is used as a characteristic module;

(5) milling the area I to be repaired, and processing the defect area into the shape of the characteristic module selected in the step (4) to obtain a repair area II;

(6) performing laser 3D printing repair on the repair area II obtained in the step (5), wherein the repair height is slightly higher than the peripheral surface to form a repair area III;

(7) and (5) carrying out precision milling on the surface of the repair area III in the step (6), removing redundant repair materials, obtaining a smooth surface, obtaining a repair surface IV, and completing repair.

In the step (3), when the characteristic parameters of the defect part are obtained, the diameter D of the circumscribed circle is calculated according to the size of a normal projection area of the defect area along the curved surface; and calculating the repair depth h according to the normal maximum depth of the defect area along the curved surface.

In the step (5), a cutter used for milling is a ball-end milling cutter, the diameter D ' of a milling area is lambda times of the diameter D of a circumcircle of a defect part, the lambda is 1.2-1.5, the milling depth is h ', and the h ' is lambda times of the repair depth h.

In the step (6), 3D printing repair is carried out on the repair area II, and a powder spraying laser cladding material increase processing method is adopted; the repair depth is slightly higher than the milling depth h' by 0.8mm to 1.5 mm.

In the step (7), the precision milling uses a cutter which is a ball end milling cutter.

The following is a detailed description of the process of spherical damage modification:

(1) and placing the part on a working table, carrying out three-dimensional measurement on the part surface local damage part, and acquiring point cloud data of a local damage area, a peripheral intact surface and a reference point. The current mature non-contact laser three-dimensional scanning measurement method can be adopted for point cloud collection.

(2) And calculating characteristic parameters of the damaged area according to the acquired point cloud data. The process requires the calculation of characteristic parameters from normal projections and cross-sectional projections of the lesion site. As shown in fig. 2a as a spherical module, the characteristic parameters include a diameter D of the damage region (corresponding to 103 in fig. 2 a), a depth h (corresponding to 104 in fig. 2 a), and the like. Specifically, the average normal vector of the damaged surface can be calculated through point cloud data of the complete surface around the damaged area, and then the section data of the damaged area is calculated.

(3) And carrying out modular numerical control machining on the damaged area according to the characteristic parameters of the damaged area. When the original surface (corresponding to 101 in fig. 2 a) is damaged, the original shape of the damaged area, i.e. the area to be repaired I (corresponding to 102 in fig. 2 a), is often complex and irregular, which is not favorable for direct laser deposition repair. Therefore, in this step, the original surface of the damaged area is milled (belonging to material reduction processing) by using a ball end mill, so that the damaged area is transformed into a regular-shaped geometric body, which is a spherical module in this embodiment, and the spherical shape is calculated according to the geometric characteristic parameters of the damaged area.

(3-1) when the milling module characteristic parameters are calculated in the step (3), taking fig. 2 as an example, measuring the diameter D (corresponding to 103 in fig. 2 a) of the circumscribed circle of the long end of the defect region from the normal projection plane of the defect region; the maximum depth h of the defect area is then measured from a cross-sectional direction perpendicular to the normal (corresponding to 104 in fig. 2 a). In the actual machining, the characteristic parameters are amplified by λ times (λ is 1.2 to 1.5 in this example), i.e., D '(corresponding to 202 in fig. 2 b) and h' (corresponding to 203 in fig. 2 b) in fig. 2b, so that micro defects such as a defect region and an internal crack thereof can be removed as much as possible.

And (3-2), calculating the sphere radius R (corresponding to 204 in fig. 2 a) and the sphere center coordinate O (corresponding to 205 in fig. 2 a) of the milled spherical surface according to the geometric relation according to the enlarged characteristic parameters D '(corresponding to 202 in fig. 2 a) and h' (corresponding to 203 in fig. 2 a) to help generate the milling track.

And (3-3) selecting a proper ball-end milling cutter, and performing modular milling on the defect area to form a milling surface 201 to obtain a repair area II.

(4) And generating modular laser deposition repair according to the characteristic parameters of the machined part, and performing laser 3D printing on the milled area to be repaired. The process adopts a powder-spraying laser 3D printing technology, and specific powder materials are sent to an area to be repaired, sintered and solidified under the action of laser and integrated with parts.

(4-1) in the step 4, the modular repair geometry (corresponding to 301 in fig. 2 c) (taking a spherical surface as an example) is slightly higher than the surrounding intact surface by a certain height t (corresponding to 302 in fig. 2 c), and the value of t is 0.5 mm-1 mm, so that a certain margin is reserved for subsequent milling.

And (4-2) layering the repair geometry according to requirements, selecting a proper layer thickness and a laser deposition path, and repairing to form a laser deposition repair area III (corresponding to 303 in fig. 2 c).

(5) According to the point cloud data of the good surface (corresponding to 401 in fig. 2 d) around the defect region, fitting a sewing surface (corresponding to 101 in fig. 2 a) of the defect region according to a curvature change rule, namely an original good surface, performing precision milling on the surface, and removing excess allowance of laser cladding repair to form a repair surface iv (corresponding to 402 in fig. 2 d).

(5-1) the surface fitting process ensures the smoothness of the surface as much as possible and restores the original intact surface with high precision.

And (5-2) adopting a ball-end milling cutter in the precision milling process, and designing processing parameters and a feed path according to the surface quality requirement.

In addition, as shown in fig. 3a, 3b, 4a, 4b, different geometric modules can be designed according to the shape characteristics of the defect region, and the spherical module of fig. 3a, 3b can be selected when the major axis and the minor axis of the defect region are close to each other; wherein 501 corresponds to the length parameter of the defect area, and 502 corresponds to the width parameter of the defect area; when the difference between the two is large, the slot module of fig. 4a and 4b can be selected, where 601 corresponds to the milled slot length parameter and 602 corresponds to the milled slot width parameter.

The above is only one embodiment of the present invention, and the present invention is not limited thereto.