CN115157010B - Positioning processing system and method for large thin-wall workpieces of multiple varieties - Google Patents
Positioning processing system and method for large thin-wall workpieces of multiple varieties Download PDFInfo
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Abstract
The invention relates to a novel locating processing system for a large-sized thin-walled workpiece of multiple varieties, in particular to a method for realizing rapid measurement, alignment and locating processing of external station postures of the large-sized thin-walled workpiece of multiple varieties by adopting an off-machine preset workstation, a zero point positioning tool and a five-axis numerical control machine tool, and belongs to the technical field of self-adaptive processing of large-sized thin-walled workpieces. The method is characterized in that: the system comprises a server, a cantilever type coordinate measuring machine, a joint arm scanner, a zero point positioning tool, an AGV moving platform and a five-axis machine tool; the external station pose of the multi-variety large thin-wall workpiece machine can be quickly aligned and positioned. Compared with the existing processing method of the large thin-walled workpiece, the method provided by the invention can greatly improve the alignment and positioning efficiency and the production efficiency of the large thin-walled workpiece.
Description
Technical Field
The invention relates to a locating processing system for a large-sized thin-wall workpiece of multiple varieties, in particular to a method for realizing quick measurement, alignment and locating processing of external station gestures of a large-sized thin-wall workpiece machine of multiple varieties by adopting an off-machine preset workstation, a zero point quick-change tool and a five-axis numerical control machine tool, and belongs to the technical field of self-adaptive processing of large-sized thin-wall workpieces.
Background
In order to meet the requirement of aerodynamic shape precision, the outer shell of the aerospace vehicle is mostly formed by combining large thin-wall workpieces in curved surfaces, such as cylinders, cones and special-shaped curved surfaces. Furthermore, in order to realize the light weight design as much as possible while ensuring the structural strength, the large thin-wall workpiece is provided with the characteristic of 'outer wall curved surface smooth-inner wall reinforcement lattice transverse and longitudinal distribution'. The large thin-wall workpiece with the characteristics generally adopts a manufacturing route of 'blank casting/forging forming-precise numerical control machining', and the formed blank often has the problems of offset of original standard, uneven residual distribution and the like due to the large deformation and the large precise shape regulation difficulty in the blank forging/casting process, so that the great difficulty is brought to the processing process of the outer wall curved surface and the inner wall rib lattice of the large thin-wall workpiece. In order to ensure the numerical control processing quality of the large thin-wall workpiece, a technical route of measurement, gesture adjustment and processing is generally adopted, wherein gesture measurement and adjustment are relatively core process steps, and the result directly determines the processing precision of the inner wall and the outer wall of the subsequent large thin-wall workpiece. However, the conventional measurement pose adjustment process has the following two difficulties: (1) the large thin-wall workpiece has large size and weight, so that the positioning and alignment process is time-consuming and labor-consuming; (2) the special gesture adjusting tool for the large thin-wall workpiece needs to be designed, and the tool has low flexibility and high cost; in order to solve the above difficulties, the self-locating processing technology is applied. The self-locating processing technology generally refers to obtaining the actual pose of a workpiece through measuring equipment in a machine tool, and realizing the effect of 'finding the workpiece' by adjusting the pose of a cutter, thereby ensuring the correct relative position relationship between the cutter and the workpiece. For large thin-wall workpieces, the implementation process of the self-locating machining technology is obviously more convenient than the traditional measuring-posture adjusting process.
The common alignment measuring equipment mainly comprises a digital dial indicator, a coordinate measuring machine and a laser scanner. The measuring and aligning means based on the digital dial indicator is mainly suitable for large thin-wall workpieces with straight or cylindrical/conical rotation characteristics, and the method is greatly limited for large special-shaped thin-wall workpieces without obvious straight or rotation characteristics. The positioning and aligning method based on the coordinate measuring machine is mainly used for obtaining the space point coordinates of the workpiece features, and is suitable for the working condition that the processing pose can be determined through a small number of measuring points. For large-scale special-shaped thin-wall parts, a large number of measuring points are often needed to reversely calculate the actual pose, and for the working condition, the positioning and aligning method based on the coordinate measuring machine is often low in efficiency. The positioning and aligning method based on laser scanning is suitable for large thin-wall workpieces without obvious measurable characteristics, the method fits actual pose through scanning point cloud data, the pose calculation accuracy is high, and the method is particularly suitable for complex large thin-wall workpiece machining processes.
The three pose measuring methods are respectively suitable for different types of large-scale thin special-shaped wall pieces, wherein the measuring method based on laser scanning not only has higher pose calculating precision, but also is suitable for various types of large-scale thin-wall pieces. Therefore, the combination of the laser scanning measurement method and the self-locating processing method is an effective solution for realizing high-precision and high-efficiency processing of various large-scale thin-wall workpieces. However, when the method is applied to large-scale special-shaped thin-wall parts, the following problems still exist to be solved. (1) The pose measurement process is often carried out in the machine tool, and the process occupies a large amount of machine tool use time, so that the utilization rate of the machine tool is reduced. (2) For large thin-wall workpieces, multiple station transfer measurements are often needed, and the process is labor-consuming and labor-consuming, so that the alignment efficiency is severely limited. The prior patent (CN 2021113756977) discloses an automatic skin curved surface measurement data acquisition system based on laser scanning and a visual sensor. A point laser measuring device and a method of a four-axis blade laser measuring platform (patent number: CN 2020114934731) disclose a blade measuring system based on four-axis measuring equipment and point laser equipment. The system applies laser measurement to pose and quality detection of the special-shaped thin-wall part, but does not discuss application of the special-shaped thin-wall part in machining. The patent of self-locating device and processing method for high-precision polishing machine tool (patent number: CN 2015106615061) discloses a workpiece locating processing system based on a high-precision measuring head, the method realizes the conversion between measurement data and processing program, the processed workpiece is only clamped on the machine tool without the need of marking a table for positioning, and the processing efficiency is greatly improved. However, the method is suitable for small-sized workpiece processing, and for large-sized thin-wall workpieces, the pose measurement efficiency is low, and the utilization rate of a machine tool is reduced.
Disclosure of Invention
The invention aims to provide a large thin-wall workpiece locating processing system and method based on an off-machine preset workstation, a zero point quick-change tool and a five-axis machine tool. And (3) measuring the actual pose of the large thin-wall workpiece by adopting an off-machine preset workstation, and calculating the conversion relation between the large thin-wall workpiece and the theoretical pose through registration. The zero point quick-change tool is utilized to realize quick change of the large thin-wall workpiece between the off-machine preset workstation and the five-axis numerical control machine tool, and the five-axis machine tool processing coordinate system is corrected based on the pose conversion relation, so that the position-searching processing of the large thin-wall workpiece is realized.
The invention comprises the following technical scheme that the large thin-wall workpiece locating processing system based on an off-machine preset workstation, a zero point quick-change tool and a five-axis machine tool comprises a server, a cantilever type coordinate measuring machine, a numerical control rotary table, a measuring tail end interface, a joint arm type laser scanner, a digital dial indicator, a zero point quick-change tool, a large thin-wall workpiece, an AGV moving platform and a five-axis numerical control machine tool.
The server is provided with control software of an external preset workstation and point cloud scanning measurement software of the laser scanner, the control software is utilized to calculate the conversion relation between the actual pose and the theoretical pose of the workpiece, and accordingly, the adjustment quantity of the machining coordinate system, the adjustment sequence and the adjustment quantity of each movement axis of the five-axis machine tool are obtained.
The off-machine preset workstation comprises a cantilever type coordinate measuring machine (X axis, Y axis and Z axis), a numerical control rotary table (C axis), a laser scanner and a digital dial indicator. The off-board preset workstation adopts a set of control system to drive the four-axis motion. Meanwhile, the cantilever type coordinate measuring machine adopts a magnetic grating ruler, and the rotary table adopts a grating encoder to match with a controller to realize double-feedback accurate motion control in the four-axis motion process, so that accurate positioning is realized.
The articulated arm type laser scanner is fixed to the tail end of the cross beam of the cantilever type coordinate measuring machine through threaded connection, a threaded interface of the tail end of the cross beam has quick-change characteristics, and measuring instruments or equipment such as the laser scanner, a digital dial indicator and the like can be installed.
Quick-change tools are placed on the numerical control rotary table and comprise a base plate, a zero point positioning tool and a clamp plate. The zero point positioning tool comprises a blind rivet and a chuck, and accurate positioning is realized through cooperation of the blind rivet and the chuck. The foundation plate is fixedly connected with the rotary table through bolts and T-shaped blocks, the zero positioning chuck is fixed on the foundation plate, the zero positioning blind rivet is fixed on the clamp plate, and the large thin-wall workpiece is fixed on the clamp plate through the clamp. The cooperation of the universal zero point positioning blind rivet and the chuck realizes the pre-positioning of the large thin-wall workpiece on the rotary table.
And acquiring actual pose point cloud data of the large thin-wall workpiece by using an articulated arm type laser scanner, and further calculating the adjustment sequence and adjustment quantity of the machine tool motion axis based on management and control software in [0007 ]. After that, the workpiece and the clamp plate are integrally transported to the five-axis gantry machine tool through the AGV moving platform, and the workpiece is quickly positioned on the machine tool working platform through the cooperation of the zero positioning blind rivet on the clamp plate and the zero positioning chuck on the five-axis machine tool working platform.
Based on the machine tool motion axis adjustment sequence and adjustment amount obtained in [0011], the zero point of a machining coordinate system is quickly corrected in a numerical control system, so that the cutter can quickly find the actual position of a large thin-wall workpiece, the accuracy of the relative position between the two is ensured, and machining is started.
The method for locating and processing the large thin-wall workpiece based on the off-machine preset workstation, the zero point quick-change tool and the five-axis numerical control machine tool can be divided into six steps: the workpiece is pressed on a fixture plate of a numerical control rotary table, the workpiece is scanned by an articulated arm type laser scanner, point cloud is registered with a theoretical model, the conversion quantity of a processing coordinate system is calculated, the workpiece is rapidly positioned in a machine tool, the processing coordinate system is modified, and the processing is started, and the method mainly comprises the following steps:
the first step: the fixture plate is connected and matched with the base plate on the numerical control rotary table by utilizing the zero point positioning tool, the large thin-wall workpiece is fixed on the fixture plate of the numerical control rotary table through the fixture such as the pressing plate, and the workpiece is not required to be accurately positioned at the moment, but the good clamping state is ensured so as to reduce vibration in the machining process as much as possible;
and a second step of: scanning the outer wall, the inner wall ribs and the clamp plate of the large thin-wall workpiece by using a joint arm type scanner, obtaining point cloud data of the actual pose of the workpiece, and storing the point cloud data;
and a third step of: introducing theoretical model and scanning point cloud data into management and control software, firstly registering an actual clamp plate obtained by scanning with the theoretical clamp plate, registering an actual workpiece obtained by scanning with the theoretical workpiece on the basis, calculating a pose conversion matrix, calculating the adjustment sequence and adjustment quantity of each motion axis of the five-axis machine tool on the basis, and storing;
fourth step: the fixture plate and the workpiece are transported to a five-axis machine tool station through an AGV moving platform, and quick positioning of the fixture plate and the workpiece on a machine tool working platform is realized by utilizing a zero point positioning tool;
fifth step: correcting a machining coordinate system in a numerical control system of the machine tool according to the adjustment sequence and the adjustment quantity of each movement axis of the machine tool obtained in the step [0016 ];
sixth step: starting to process the large thin-wall workpiece by taking the corrected processing coordinate system as a zero point;
the technical scheme of the invention has the following advantages or beneficial effects:
(1) The locating processing system realizes the rapid alignment of the large thin-wall workpiece based on the idea of off-machine measurement-on-machine adjustment. Compared with the traditional in-machine alignment, the machine tool operation time is not occupied, the utilization rate of the machine tool is greatly improved, and the production efficiency of the whole production line is further improved. In addition, the actual adjustment of the processing pose of the large thin-wall workpiece is not needed, the design of a special pose adjustment tool can be avoided, the whole operation is more convenient, and the cost is lower.
(2) The four-axis measuring equipment is matched with the articulated arm type laser scanner to realize the rapid scanning acquisition of the full-range point cloud data of the inner wall and the outer wall of the large thin-wall workpiece. The four-axis measuring equipment can realize accurate positioning (the positioning error is within +/-0.03 mm), and the position change relation before and after the movement of the four-axis measuring equipment can be directly obtained, so that the laser scanner can rapidly turn over the station based on the change quantity of the positions before and after the movement of the four-axis measuring equipment, the measurement reverse-solving process in the traditional turning over operation process can be avoided, and the turning over efficiency is higher;
(3) The measuring method of the four-axis measuring equipment matched with the articulated arm type laser scanner has higher flexibility, can be suitable for various large thin-wall workpieces such as barrels, strips and the like, and has higher flexibility and richer application scenes compared with the measuring method of the articulated arm type laser scanner.
Drawings
FIG. 1 is a general block diagram of a large thin-walled workpiece locating and machining system of the present invention;
FIG. 2 is a schematic diagram of a four-axis measurement device and an articulated arm laser scanner according to the present invention;
FIG. 3 is a schematic diagram of the zero point positioning tool structure of the invention;
FIG. 4 is a flow chart of a locating processing method of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and some points of the present invention more clear and clarified. It should be understood that the examples described herein are for illustrative purposes only and are not intended to limit the present invention.
As shown in FIG. 1, the invention provides a locating and processing system for a large thin-wall workpiece based on four-axis measuring equipment, a zero locating tool and a laser scanner. In this example illustration, the system configuration includes: server 1, four-axis measuring equipment (cantilever type coordinate measuring machine 2, laser scanner mounting interface 3, articulated arm type laser scanner 4), numerical control rotary table 5, zero point positioning tool 6, base plate 7, clamp plate 8, large thin-wall workpiece 9, AGV moving platform 10, five-axis numerical control machine tool 11 and operator 12. The server 1 is provided with four-axis measuring equipment management and control software and point cloud scanning measuring software, the articulated arm type laser scanner 4 is a laser scanner, and the zero point positioning tool 6 comprises an NP190 type non-directional chuck 6-1 and an NP190 type blind rivet 6-2.
The articulated arm type laser scanner 4 is fixed to the tail end of a beam of the cantilever type coordinate measuring machine 2 in a threaded connection mode, the base plate is fixed to the numerical control rotary table 5 through bolts and T-shaped nuts, the non-directional chuck 6-2 of the zero point positioning tool 6 is fixed to the base plate 7 through bolts, the base plate 7 is connected with the clamp plate 8 through the chuck 6-1 and the blind rivet 6-2, and the large thin-wall workpiece is fixed to the clamp plate through the pressing plate.
As shown in fig. 2, the four-axis measuring apparatus includes a three-axis cantilever type coordinate measuring machine (straight axis, X, Y, Z axis), a numerical control turret (rotary axis C axis) and a scanner mounting interface, the X-axis stroke is 2000mm, the y-axis stroke is 160 mm, the z-axis stroke is 3100mm, and the diameter of the numerical control turret is 1600mm and can be rotated 360 °. The positioning precision of the tail end of the cantilever type coordinate measuring machine can reach +/-0.03 mm, and the positioning precision of the rotary table can reach +/-5'.
The installation interfaces of the articulated arm type laser scanner and the tail end of the cross beam are connected through threads and connected to a data acquisition channel of the server 1 in a wired mode, and acquired point cloud data are displayed and stored in point cloud scanning measurement software in the server 1.
The non-directional chuck layout mode on the base plate is identical to the non-directional chuck layout mode on the working platform of the five-axis numerical control machine tool, so that the repeated positioning accuracy is less than or equal to +/-5 mu m when the clamp plate is quickly replaced between two pieces of equipment.
As shown in FIG. 3, the AGV moving platform has a rated load of 3t, and the back and forth conveying of the clamp plate and the workpiece between the four-axis measuring equipment and the five-axis numerical control machine tool is realized.
The point cloud scanning measurement software in the server 1 is responsible for collecting, displaying and storing scanning point cloud data; the control software is responsible for controlling the four-axis equipment to move according to specified requirements, calculating the conversion relation between the actual pose of the large thin-wall workpiece and the theoretical processing pose, and giving the adjustment sequence and adjustment quantity of the five-axis machine tool processing coordinate system.
As shown in fig. 4, the invention provides a large thin-wall workpiece locating and processing system based on four-axis measuring equipment, a zero point locating tool and a laser scanner, which comprises a pose measuring module, a zero point quick-changing module, a processing coordinate system adjusting module and a processing module, and specifically comprises the following implementation steps:
the first step: the clamp plate is put into place. The air source input port on the foundation plate is connected, so that the locking module on the clamp plate is loosened, the clamp plate is hoisted to the foundation plate by using the truss, and the clamp plate is matched with the chuck on the foundation plate through the blind rivet on the clamp plate to finish the clamping plate positioning;
and a second step of: and (5) positioning a blank of the large thin-wall workpiece. The truss is utilized to hoist the workpiece on the fixture plate, the large thin-wall workpiece is pre-positioned in a worker observation mode, the center line of the truss is approximately collinear with the center line of the fixture plate, and the process has low requirements on precision. The large thin-wall workpiece is pressed and assembled on the clamp plate through the three pressing plates, the pressing force is determined according to experience of workers, the workpiece is prevented from moving in the machining process, and the large thin-wall workpiece is prevented from being deformed under pressure;
and a third step of: and scanning the clamp plate and the blank. The cantilever-type coordinate measuring machine was operated to move the end to a position about 200mm directly above the workpiece, and an articulated arm scanner was mounted to the end of the beam. The method comprises the steps that a worker holds a joint arm scanner to scan the inner wall and the outer wall of a large thin-wall workpiece blank and a clamp plate, and point cloud data are obtained through measurement software in a server;
fourth step: and (5) scanner station-switching measurement. If the workpiece is large in size, a single scan cannot cover most of the features of the workpiece and the fixture plate, and a station-switching scan measurement is required. The cantilever type coordinate measuring machine of this patent design has higher terminal positioning accuracy, consequently, after accomplishing the first scanning, control coordinate measuring machine terminal moves to next measuring point, and scanner origin coordinate passes through management and control software and directly obtains around moving, can realize the quick station-turning measurement of large-scale thin wall work piece according to moving around origin coordinate.
Fifth step: and (5) processing point cloud data. After the scanning measurement is completed, the obtained point cloud data is processed by utilizing management and control software, and firstly, the point cloud data of the scanning clamp plate and the theoretical clamp plate are subjected to digital-analog registration through an ICP algorithm, so that an initial reference is determined. On the basis, the point cloud data of the scanned workpiece are registered with the theoretical digital-analog by an ICP algorithm, and an adjustment matrix TR of a machining coordinate system is calculated. Finally, calculating the adjustment sequence and adjustment quantity of each axis of the five-axis machine tool based on TR; the specific registration process and algorithm are described as follows:
and (3) acquiring and simplifying point cloud data. Based on a voxel grid downsampling method, firstly, the point cloud is subjected to voxel division, and then the centroid of a non-empty voxel is calculated to replace all points in the voxel, so that downsampling of the point cloud is realized.
And step two, registering the clamp plates. Firstly, the measuring point cloud P is divided into a clamp plate and a workpiece. And framing a plurality of points on the upper plane of the fixture plate in a worker-assisted mode to obtain a point set Pfixture, sample, and fitting a segmentation plane S of the fixture plate and the workpiece based on the point set Pfixture.
And dividing the point cloud into an upper part and a lower part through the fitted plane S, wherein points which are closer to the plane are divided to one side of the clamp plate, so that a workpiece measurement point cloud Pwork piece and a clamp plate measurement point cloud Pfixture are obtained.
The pose transformation matrix of the clamp plate measuring point cloud Pfixture to the reference point cloud Qfixture is calculated by utilizing the traditional ICP algorithm, if two groups of point clouds can be completely matched, each point in the Pfixture is mapped into a corresponding point in the Qfixture after pose change, and the corresponding point can be expressed as a rotation matrix of Qfixture=R0.Pfixture+T0, wherein R0 is a rotation matrix of 3x3, and T0 is a translation vector of 3x 1.
After the rotation matrix R0 and the translation vector T0 from the clamp plate measurement point cloud to the reference point cloud are solved, the workpiece measurement point cloud Pwork piece can be operated through the R0 and the T0, and the workpiece measurement point cloud P' work piece under the clamp plate coordinate system is obtained, wherein the point cloud is the pose of the actual workpiece under the numerical control programming coordinate system, and is the initial state for subsequent pose adjustment.
And step three, registering the large thin-wall workpiece. And a worker interactively clicks the inner wall non-processing surface area of the workpiece reference point cloud Qworkpiece to obtain the reference point cloud Qunmachine of the inner wall non-processing surface.
Firstly, carrying out coarse registration on Pw ' orkpieces and Qunmachines, wherein the Qunmachines are target point clouds, and aligning the P ' workpiece with the Qunmachines by using a sampling consistency initial registration algorithm SAC-IA to obtain the P ' workpiece.
After rough registration is completed, the pose offset of the workpiece scanning point cloud P 'workpiece to the theoretical model inner wall point cloud Qunmachine is solved by an inner wall non-processing surface registration algorithm based on key point extraction, and the inner wall precision casting surface point cloud and the theoretical model inner wall point cloud Qunmachine are automatically extracted from the workpiece scanning point cloud P' workpiece to be registered, wherein the specific thinking is as follows:
calculating a vector: calculating normal vectors of all points pi and qi in the point cloud P' workpiece and the Qunmachine;
extracting a Qunmachine key point: estimating SIFT key points by using a normal direction as an intensity variable to obtain a key point cloud Q';
extracting an inner wall non-processing surface point cloud: extracting a point close to the point cloud Qunmachine in the scanning point cloud P 'work piece according to the nearest point distance to obtain a scanning point cloud Punmachine of the internal non-processing surface, and considering the point in the P' work piece as not being point cloud data of the internal non-processing surface if the distance between the two points is larger than a given threshold value;
extracting the key points of Punmachine: calculating a Punmachine normal vector, and estimating SIFT key points to obtain P';
matching key points: searching for a corresponding point between the point sets P 'and Q';
calculating the curvature of key points: calculating Gaussian curvatures Kpi and Kqi of all key point pairs pi and qi in the P ', Q';
eliminating false matches: if Ki= |Kpi-Kqi | > epsilon, deleting the key point pairs pi and qi;
calculating a rotation translation matrix: solving a rotation matrix R and a translation vector t between the point sets P 'and Q', Q '=rp' +t;
updating the point cloud: updating the P' work piece and the Qunmachine by using the rotation matrix R and the translation vector t;
calculating registration errors: calculating the registration error of Punmachine and Qunmachine, if the registration error change is smaller than a given value, and the iteration number does not reach the maximum iteration number, returning to [0063];
outputting a rotation translation matrix: outputting a rotation translation matrix TR obtained after iteration is finished, wherein the rotation translation matrix TR specifically comprises a rotation matrix R and a translation vector t;
and the rotation matrix R and the translation vector t are obtained through registration of the non-machined surface of the inner wall, and the updated workpiece scanning point cloud P' workpiece is obtained, so that the registration error of the inner wall of the workpiece scanning point cloud and the inner wall of the theoretical model under the pose is minimum, and the workpiece scanning point cloud is the optimal processing pose of the workpiece.
Sixth step: and (5) rapidly turning the workpiece. After the measurement and calculation of the workpiece are completed, the workpiece is transferred to a machine tool workbench for processing. Firstly, the air source of the foundation plate is connected to make the locking fast released. And then placing the clamp plate and the workpiece on an AGV moving platform tray by utilizing a truss car, so that the AGV moving platform tray is transferred to a five-axis machine tool cargo buffer area. Finally, placing the fixture plate and the workpiece on a basic plate on a five-axis machine tool workbench by utilizing a truss, and completing a workpiece quick-change transfer station by matching the locking speed and the positioning pin;
seventh step: and (5) adjusting a machining coordinate system. According to the rotation matrix and the translation vector calculated in [0069], the original machining coordinate system is quickly corrected, so that a cutter can quickly find a workpiece, and alignment and positioning of the workpiece are completed;
eighth step: processing is started. After the above steps are completed, a machining program is executed, and machining is started.
The above examples of the present invention are merely illustrative of the present invention and are not intended to limit the embodiments of the present invention. Those skilled in the art will appreciate that the invention may be embodied in many other forms without departing from the spirit or scope thereof. The present invention may be embodied with various modifications and substitutions without departing from the spirit and scope of the invention as defined in the appended claims.
Claims (12)
1. A locating processing method for a large-scale thin-wall workpiece of multiple varieties is characterized by comprising the following steps: the locating processing process comprises six steps: the workpiece is pressed on a fixture plate of a numerical control rotary table, the workpiece is scanned by an articulated arm type laser scanner, point cloud is registered with a theoretical model, the conversion quantity of a processing coordinate system is calculated, the workpiece is rapidly positioned in a machine tool, the processing coordinate system is modified, and the processing is started, and the method comprises the following steps: the first step: the fixture plate (8) is connected and matched with the base plate (7) on the numerical control rotary table by utilizing the zero point positioning tool (6), the large thin-wall workpiece (9) is fixed on the fixture plate of the numerical control rotary table through the fixture, and the workpiece is not required to be accurately positioned at the moment, but the good clamping state is ensured so as to reduce vibration in the machining process as much as possible;
and a second step of: scanning the outer wall, the inner wall and the clamp plate of the large thin-wall workpiece by using an articulated arm type scanner (4), obtaining point cloud data of the actual pose of the workpiece, and storing the point cloud data;
and a third step of: introducing a theoretical model and scanning point cloud data into management and control software, firstly registering a scanned clamp plate with the theoretical clamp plate, registering a scanned workpiece with the theoretical workpiece on the basis, and calculating a pose conversion matrix; calculating the adjustment sequence and adjustment quantity of each motion axis of the five-axis machine tool based on the matrix, and storing;
fourth step: the clamp plate (8) and the workpiece (9) are transported to a five-axis machine tool (11) through an AGV moving platform (10), and the clamp plate (8) and the workpiece (9) are rapidly positioned in the machine tool by utilizing a zero point positioning tool (6);
fifth step: correcting a machining coordinate system in a numerical control system of the machine tool according to the machine tool movement axis adjustment sequence and the adjustment quantity obtained in the third step;
sixth step: and starting to process the large thin-wall workpiece by taking the corrected processing coordinate system as a zero point.
2. The locating machining method for large thin-walled workpieces of various kinds according to claim 1, wherein in the first step, the large thin-walled workpiece (9) is fixed to the jig plate (8) by a jig.
3. The locating processing method for the large-scale thin-wall workpieces with multiple varieties, according to claim 1, wherein in the second step, in order to ensure a good registration effect, the characteristics of the inner wall and the outer wall of the clamp plate and the large-scale thin-wall workpieces need to be scanned in the measuring process of the joint arm.
4. The locating processing method for large thin-walled workpieces of multiple varieties according to claim 1, wherein the second and third steps are adapted to the large thin-walled workpieces of multiple varieties.
5. A noodle according to claim 1The locating processing method for large thin-wall workpiece with multiple kinds includes the third and fifth steps, and the calculation of the regulating sequence and regulating amount of each axis of five-axis machine tool based on the specific machine tool, and the Siemens 840D numerical control system has the regulating sequence of each axis of。
6. The locating processing method for the large-scale thin-wall workpieces with multiple varieties, according to claim 1, wherein in the fourth step, the rated load of the AGV moving platform is required to be higher than 3t, and the normal circulation of the large-scale thin-wall workpieces and the clamp plates is ensured.
7. A multi-species large thin-walled workpiece oriented locating processing system for implementing the multi-species large thin-walled workpiece oriented locating processing method according to any of claims 1-6, characterized in that: the automatic measuring device comprises a server (1), four-axis measuring equipment, a numerical control rotary table (5), a zero point positioning tool (6), a base plate (7), a clamp plate (8), a large thin-wall workpiece (9), an AGV moving platform (10), a five-axis numerical control machine tool (11) and an operator (12); the four-axis measuring equipment comprises a cantilever type coordinate measuring machine (2), a laser scanner mounting interface (3) and an articulated arm type laser scanner (4);
the server (1) is provided with control software of a cantilever type coordinate measuring machine (2), controls the four-axis motion of the coordinate measuring machine, is provided with point cloud measuring software which is communicated with the laser scanner (4), and acquires scanning point cloud data of a large thin-wall workpiece in real time;
the articulated arm type laser scanner (4) is mounted on a terminal interface (3) of the coordinate measuring machine by adopting a threaded connection, and other measuring equipment is also mounted on the interface: a digital dial indicator;
the foundation plate (7) is respectively fixed on a rotary table working plane, an AGV moving platform and a five-axis machine tool working platform in a bolt connection mode, the clamp plate (8) is connected with the foundation plate (7) at each station through a zero point positioning tool (6), and the large thin-wall workpiece (9) is fixed on the clamp plate (8) through a clamp.
8. The locating and machining system for large thin-walled workpieces of multiple varieties according to claim 7, wherein: and the quick alignment of the processing pose of the large thin-wall workpiece is realized based on the out-of-machine measurement alignment-in-machine processing.
9. The locating and machining system for large thin-walled workpieces of multiple varieties according to claim 7, wherein: combining four-axis measuring equipment with an articulated arm type laser scanner to realize rapid scanning acquisition of point cloud data of the whole range of the inner wall and the outer wall of a large thin-wall workpiece; the four-axis measuring equipment realizes accurate positioning, and the position change relation before and after the movement of the four-axis measuring equipment can be directly obtained, so that the rapid station turning of the laser scanner is realized based on the change amount of the position before and after the movement of the four-axis measuring equipment.
10. The locating and machining system for large thin-walled workpieces of multiple varieties according to claim 7, wherein: the measuring method of the shaft measuring equipment matched with the articulated arm type laser scanner is suitable for large thin-wall workpieces such as drums and strips.
11. The locating and machining system for large thin-walled workpieces of multiple varieties according to claim 7, wherein: the tail end of the four-axis measuring equipment is provided with a quick-change interface to realize quick-change of the joint arm scanner and the digital dial indicator.
12. The locating and machining system for large thin-walled workpieces of multiple varieties according to claim 7, wherein: after the cross beam of the cantilever type coordinate measuring machine (2) extends to the most far end, the end deformation is required to be smaller than 0.01mm/100N before and after the joint arm scanner is installed, so that the base of the joint arm scanner is ensured to move without influencing the scanning and measuring process.
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