CN105242639A - Numerical control machining feature customizing method - Google Patents

Abstract

A method for NC processing custom processing features, which is based on the three-dimensional CAD model of the part, and the geometric shape and processing technology plan of the processing feature are customized by the user according to the processing resources, part structure and programming habits of the enterprise. The user defines the geometric elements of the processing features and their connection relationship, and establishes the matching rules between the geometry and the processing technology according to the key process parameters of the processing features. According to the information of the custom processing features, the cutting parameter optimization model is established to realize the optimization of the cutting parameters of the custom processing features. Establish an analysis program, complete the association between the geometric elements of the custom processing features and the processing technology, realize the automatic programming of the NC machining of the custom processing features, and formulate the positions that need to be detected during the processing and the self-adaptive adjustment strategy. The invention can improve the programming efficiency and programming quality of complex structural parts, shorten the manufacturing cycle of the parts, and realize the accumulation of technological knowledge of enterprises at the same time.

Description

NC Machining Custom Machining Feature Method

technical field

The present invention relates to a programming method for NC machining of parts, in particular to a method and application for customizing the NC machining features of complex structural parts, mainly for customizing the processing features of complex structural parts according to the characteristics and requirements of user parts, and realizing A method for automatically generating tool paths belongs to the field of CAD/CAM/CAPP.

Background technique

At present, with the rapid development of my country's aerospace technology, the application of CNC machine tools to process complex structural parts is becoming more and more extensive. The NC machining process of complex structural parts is complicated, the process preparation period is long, and the complex structural parts have the characteristics of multiple varieties and small batches, which requires the NC machining of complex structural parts to have a strong rapid response ability.

A feature is a geometric shape with certain engineering semantics, which is generally related to the application field and has different connotations in different fields. In the field of NC machining of complex structural parts, machining features, as the carrier of machining process knowledge, can significantly improve the efficiency and standardization of machining process preparation, and ensure the stability of machining quality.

The International Organization for Standardization ISO released the definition standard of processing features in STEPAP224, but the feature structure defined in STEPAP224 is simple, and the processing semantics carried are simple, which cannot meet the expression requirements of complex structural parts. In the traditional manufacturing feature application system, the definition of features is fixed, and the scope of application is limited, and the addition of new features needs to modify the underlying algorithms of modules such as identification and process decision-making, which has poor scalability. , there are great differences between the parts, and the characteristics of the components are also very different. The traditional processing features with fixed meanings are not universal for complex structural parts with multiple enterprises and varieties. The definition of workpiece processing features puts forward higher requirements.

Aiming at the problems existing in actual production, there is an urgent need for a user-defined method of processing features, which allows users to define their own processing features according to their own manufacturing resources, geometric and process characteristics of parts, and enterprise programming habits, and the system can automatically analyze user-defined features. Define the data structure of the feature, automatically match the recognition algorithm, realize the association between the feature geometry and the feature process plan, automatically complete the process decision of the part feature, and generate the tool path for feature processing. This method can improve the programming efficiency and programming quality of complex structural parts, shorten the manufacturing cycle of parts, and at the same time, it can well realize the accumulation of enterprise process knowledge.

Contents of the invention

The purpose of the present invention is to solve the problems of fixed processing feature definition and limited application range in the NC machining process of complex structural parts, invent a user-defined method for NC machining features of complex structural parts, realize user-defined processing features, and improve the accuracy of processing features Applicability, improve the efficiency and quality of NC programming for complex structural parts.

Technical scheme of the present invention is:

1. The user can customize the geometric shape of the processing feature according to the manufacturing resources, part structure and programming habits of the enterprise, define the topological relationship of the geometric shape of the processing feature and the properties of the surface and edge, and define the key geometric parameter information of the processing feature and its The calculation method assigns a unique identifier to each custom processing feature, and expresses the processing feature through structured data after the user has interactively input the information of the processing feature; finally, according to the geometric relationship between the user-defined processing features Topological relationship and surface and edge attribute information are used for feature recognition, and the key geometric parameter information of the feature is extracted.

2. The self-defined feature structured expression is based on the geometric elements selected by the user, automatically calculates the key attribute information of each geometric element, the connection information and position information between the geometric elements, and constructs the attribute surface edge graph that defines the feature. And realize the expression and output of machining feature geometric elements with the tree structure of parent and child nodes.

3. To analyze the processing features and realize the recognition of the processing features, first construct the attribute surface and edge graph of the entire part, and search for the feature geometric elements that meet the conditions according to the structured hierarchical structure of the defined features, and construct the user-defined processing features, and extract the key parameter information of the feature geometric elements at the same time.

4. Realize the definition and analysis of processing technology rules through the following methods: use interpretive semantic rules to define typical processing schemes of processing features, which are typical processing schemes for defining each element set of features according to the explanatory language rules provided by the user, Define the typical machining strategy, machining allowance, machining operations, machining tools and corresponding parameters of the machining feature, and establish process rules based on key parameter information such as machining accuracy and surface quality of the feature, so as to determine each specific machining feature. The processing strategy, processing operation and corresponding parameters; the user selects the required driving geometric elements for various processing operations of the feature, and automatically records the selected driving geometric mode; establishes according to the size of the feature and the machining allowance The rules determine the tools required to process the feature; the user can define the intermediate processing state that needs to be detected for the processing feature, and the user can also define the conditions required to trigger the detection of the intermediate processing state.

5. Optimize the cutting parameters of NC machining based on the user-defined processing features through the following methods: According to the processing feature information, establish a feature-based cutting parameter optimization model, which is based on the geometric information and process information of the user-defined processing features to obtain features Intermediate processing state, according to the intermediate state information to match the mechanical model of the processing feature and calculate the cutting force, deformation, power and other constraints, considering the machine tool, tool and material information to calculate the cutting parameters required for various operations of the processing feature, including the spindle Speed, feed rate, depth of cut and width of cut.

6. Realize automatic programming of NC machining based on user-defined processing features through the following methods: According to the geometric shape of user-defined processing features and user-defined processing technology scheme, establish a user-defined processing feature analysis program, and the analysis program reads line by line Take the unique identifier of the geometric element of the custom processing feature, and analyze the relationship between the geometric shape of the user-defined processing feature and the user-defined processing technology through the judgment of the key characters, so as to ensure that the geometric elements and the processing technology are realized one by one Corresponding relationship, the cutting parameters of each feature are optimized by the cutting parameter optimization model based on processing features, the machining deformation and processing path factors are considered, the processing features are sorted, and then the machining tool path of the part is automatically generated.

8. Realize the adaptive adjustment of the processing process based on user-defined processing features through the following methods: formulate an adaptive adjustment strategy for processing problems that occur during the processing based on user-defined processing features, and adjust the processing strategy according to different detection or monitoring data , including clamping adjustment and tool path adjustment; formulate rules corresponding to different processing features and different processing operations for adaptive adjustment, and determine the adjustment strategy according to the rules.

Beneficial effects of the present invention:

Compared with the existing NC machining and programming methods based on processing features, the method proposed by the present invention allows users to define their own processing features according to their own manufacturing resources, geometric and process characteristics of parts, and enterprise programming habits, and the system can automatically analyze user Customize the data structure of the feature, automatically match the recognition algorithm, realize the association between the feature geometry and the feature process, automatically complete the process decision of the part feature, and generate the tool path of the processing feature. This method can improve the programming efficiency and programming quality of complex structural parts, shorten the manufacturing cycle of parts, and at the same time, it can well realize the accumulation of enterprise process knowledge.

Description of drawings

Fig. 1 is a flow chart of the definition and application of the processing features of the present invention.

Fig. 2 is the parts used in the embodiment of the present invention.

Fig. 3 is the geometric element composition of the user-defined processing feature in the embodiment of the present invention, for the "groove feature" of this example, where B_i represents the geometric element family of the bottom surface; S_i represents the geometric element family of the side surface; SC_i represents the geometric element family of the corner surface .

Fig. 4 is an attribute surface-edge diagram of a user-defined processing feature in an embodiment of the present invention. The connection and positional relationship between geometric elements is expressed in the form of multi-bit coding. The first bit of the coding between geometric elements in the figure represents the connection relationship: 0 means no connection, 1 means concave connection, 2 means convex connection; The bit represents the positional relationship: 1 represents tangent, 2 represents parallel, 3 represents vertical, "··" represents other added attribute values.

Fig. 5 is the processing tool path of the "web" generated by customizing the "groove feature" in the embodiment of the present invention.

detailed description

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

As shown in Figure 1-5.

A method for customizing machining features in NC machining. The process is shown in Figure 1. Based on the 3D CAD model of the part, the user first defines the geometric shape of the machining feature according to the company's manufacturing resources, part structure, and programming habits. Click the geometric elements of the 3D model of the part in the interactive interface, and automatically record the topological relationship between the selected geometric elements, as well as the surface and edge attributes, and the key geometric parameter information and calculation method of the processing features are defined by the user, and each user-defined Each processing feature is assigned a unique identifier. After the user interactively inputs the information of the processing feature, the processing feature is expressed through structured data; the feature is identified according to the topological relationship between the user-defined processing feature geometries and the surface and edge attribute information. And extract the key geometric parameter information of the feature. In this process, the user can customize the typical process of the processing feature in the form of rules, give the typical processing strategy, machining allowance, processing operation and its parameters of the processing feature, and establish rules according to the processing accuracy and key geometric parameter information of the feature , so as to determine the processing strategy, processing operation and its parameters required for each specific processing feature; the user selects the required driving geometric elements for various processing operations of processing the feature, and automatically records the selected driving geometric mode; Determine the tool required to process the feature according to the size of the feature and the machining allowance; the user can define the intermediate processing state that needs to be detected for the processing feature, and can also define the conditions required to trigger the detection of the intermediate processing state. When establishing a cutting parameter optimization model based on processing features, it can calculate the cutting parameters required for various operations of the processing features, including spindle Speed, feed rate, depth of cut and width of cut. When performing automatic programming of NC machining based on user-defined processing features, an analysis program can be established according to the geometric shape of user-defined processing features and user-defined processing technology, and the user-defined processing feature geometry, user-defined processing Processes and their correlations are analyzed, the cutting parameters of each feature are automatically calculated by the cutting parameter optimization model based on processing features, the machining deformation and processing path factors are taken into consideration, the processing features are sorted, and then the machining tool path of the part is automatically generated . If there is a processing problem during the formulation of the processing process, an adaptive adjustment strategy should be carried out, and the processing strategy should be adjusted according to different detection or monitoring data, including clamping adjustment and tool track adjustment; different processing features should be formulated to correspond to different processing operations. According to the rules, the adjustment strategy is determined according to the rules.

The following takes the slot-featured aircraft structural part shown in Figure 2 as an example for further elaboration:

As shown in Figure 2, taking the typical groove feature in the aircraft structural part as an example, the steps of NC machining custom machining features are as follows:

1. According to the manufacturing resources of the enterprise, the structural characteristics of parts, the processing technology scheme and the programming habits of the enterprise, the user selects the geometric constituent elements of the defined features through the interactive interface, and selects all the faces contained in the area A in the figure, as shown in Figure 3 Show. At the same time, it is supplemented with the engineering semantics specification stipulated by this method for special cases.

2. Automatically calculate the topological relationship, positional relationship, and surface and edge geometric attributes between the selected geometric elements, and construct an attribute surface-edge graph that defines features, as shown in Figure 4, in which multi-bit codes are used to represent the geometric elements The relationship between connection and position between geometric elements, the first bit represents the connection relationship: 0 means no connection, 1 means concave connection, 2 means convex connection; the second bit represents the position relationship: 1 means tangent, 2 means parallel, 3 Represents vertical, "··" represents other added attribute values. The key geometric parameter information and calculation method of the processing feature are defined by the user using the processing semantics. If the geometric elements of the geometric element family S_i exceed 3, and the geometric element family B_i has common geometric elements with each other, it can be considered that the current two features can be Combine to form a combined feature.

3. Use the keyword "groove feature" to give a unique identifier to the custom processing feature, integrate the attribute surface edge graph of the defined feature with the information input by the user interactively, and complete the custom processing through the data model of the parent-child node tree structure expression of characteristics.

4. According to the geometric shape and characteristics of the defined features, the user defines the machining strategy, machining allowance, machining operations and parameters of each geometric element family of the "groove feature". For the "web" geometry of the "groove feature", the machining strategy of end milling is adopted, the machining allowance for finishing is set to 0mm, and the pocketing machining operation is used. The semantic definition method for the process scheme of "web" in this example is as follows:

OperationType=Pocketing;//Define the processing operation type as Pocketing

#DefineRough_Information//Specify rough machining information

Rough.Side_Allowance=3//Define the rough machining side allowance as 3mm

Rough.Bottom_Allowance=3//Define the bottom allowance of rough machining as 3mm

Rough.Tool=D32*30*80R2//Define the rough machining tool as diameter 32mm, blade length 30mm, tool length 80mm, tool bottom corner radius 2mm

#DefineTool_Information//Define machining tool information

Tool.Name=T0001//Define the tool name as T0001

Tool.Parameters=D12*30*80R1//Define the tool diameter as 12mm, the blade length as 30mm, the tool length as 80mm, and the tool bottom corner radius as 1mm

#DefineMachining_Information//Define machining information

Machining.ToolPathStyle=1//1 represents the tool path Outwardhelical

Machining.Machining.DirectionOfCut=1//1 represents the cutting method Climb

Machining.Machining.tolerance=0.01//Define the machining tolerance as 0.01

Machining.Nachining.FixAccuracy=0.01//Define the clamping accuracy as 0.01

Machining.Radial.Mode=1//1 represents the maximum distance Maximumdistance

Machining.Radial.Distance=9//Define the radial maximum distance as 9mm

Machining.Axial.Mode=1//1 represents Maximum depth of cut

Machining.Axial.MaxDepth=4//Define the maximum axial depth of cut as 4mm

#DefineFeedrate_Information//Define feed rate information

Feedrate.AutoCompute=1//1 means True

Feedrate.Approach=300//Define the feed rate as 300

Feedrate.Retract=1000//Define the retraction speed as 1000

#DefineApproachANDRetract_Information//Define the combination of advance and retreat knives

Approach=Helix+Axial+UpToPlane//Define the combination of feed

#SubDefineApproachParameters//Define the parameters of each element of the approach

Helix.radius=6//Define the spiral radius as 6mm

Helix.height=3.5//Define the spiral height as 3.5mm

Helix.angle=3//Define the helix angle as 3 degrees

Axial.Distance=5//Define the axial distance as 5mm

Retract=Circular+Axial+UpToPlane//Define the combination of retraction

#SubDefineApproachParameters//Define the parameters of each element of tool retraction

Circular. AngleSector=45//

Circular.AngleOrientation=3//

Circular.Radius=5//Define the arc radius as 5mm

Axial.Distance=10//Define the axial distance as 10mm

Clearance=ToSafetyPlane//Define the Clearance method as going to the safety plane

...

Note: The distance unit defined here is mm; the angle unit is °; the speed is mm/min;

Here users can define the required parameters according to their own needs, and some auxiliary parameters can also use the global parameters provided by the system, which need not be defined separately here.

5. Define the processing technology plan according to the key geometric elements and geometric parameters, and form the process rules. According to the key parameters such as processing accuracy and surface roughness required by the part design, establish processing parameters that meet the requirements of the rules. If the processing accuracy is less than 0.01, then the cutting depth of processing is 2mm, the feed rate is 8000, and the rest of the geometries that do not meet the rule conditions Elements will adopt the machining parameters set globally. The program for some of the rules defined in this example is expressed as:

#Definerules

IFMachining.accuracy<0.1//Definition rule condition: machining accuracy is less than 0.1

THENMachining.Axial.MaxDepth=2//The maximum axial depth of cut is 2mm

Feedrate.Machining=8000//Machining feed rate is 8000mm/min

...

IFGeoElementsDepth>20//Define the rule condition: the depth of geometric elements is greater than 20mm

THENLayeredMachining=TRUE//The layered machining method is TRUE

LayerHeight=20//Set layer height to 20mm

...

6. For the defined machining operation, the user defines the driving geometric element corresponding to the operation and the calculation method of the driving element. For the pocketing operation of the "web" in the "groove feature", define the driving geometry as the outer ring edge of the "web surface" as the driving geometric element. After the definition is completed, the corresponding driving geometry of the "groove feature" can be automatically obtained in the process decision module Elements; for the Profile operation of the "inner shape" in the "groove feature", define the driving geometry as the geometric elements that constitute the "inner shape", that is, the side geometry set of the "groove feature":

#DefineDriveGeometryforpocketing//Define pocketing drive geometry

Machining.DriveGeometry=FaceListOfBottom[1].Outloop//The driving geometry is the outer edge of the bottom surface

#DefineDriveGeometryforprofile//Define profile drive geometry

Machining.DriveGeometry=FaceListOfSide//The drive geometry is the side geometry element.

7. Aiming at the problem that the processing quality needs to be inspected during the part processing, the processing feature is used as the carrier to define the detection method and detection position corresponding to the feature. The intermediate processing state detection of the groove feature is to detect the thickness of the web surface after rough machining.

8. According to the user-defined processing feature type, size and parameters, the cutting parameters are optimized based on the processing features, and the cutting of the defined feature processing operations is performed according to the geometric shape and size of the feature, intermediate state, machine tool information, tool and material information. parameters are optimized. For the specific method, please refer to the Chinese invention patent: "Optimization Method of Cutting Parameters for NC Machining of Aircraft Structural Parts Based on Intermediate Features".

9. Through the interactive operation of the craftsmen and the analysis program, the analysis program reads the unique identification of the geometric elements of the custom processing features line by line, and through the judgment of the key characters, matches it with the typical process rule scheme of the processing features, and establishes user-defined The association between the geometric elements of the processing features and the custom processing technology makes each geometric element family correspond to a unique processing technology scheme.

For the determined geometric elements and processing technology plan, by extracting the geometric elements required to generate the machining tool path and the processing parameters in the corresponding operation, and realizing the automatic assignment of each processing parameter, and then automatically generating the machining tool path of the processing feature, realizing the user The automatic programming of custom machining features, the generated tool path is shown in Figure 5.

10. Formulate user-defined processing features to adapt to the processing problems that occur during the processing process, and adjust the processing strategies according to different detection or monitoring data, including clamping adjustments and tool path adjustments; formulate different processing features and different processing operations Adaptively adjust the corresponding rules, and determine the adjustment strategy according to the rules. For the specific method, please refer to the Chinese invention patent application with the application number: 201310173715.2 and the name. "Method for Triggering Detection of Feature-Based CNC Machining Monitoring".

The parts not involved in the present invention are the same as the prior art or can be realized by adopting the prior art.

Claims (7)

1. A method for custom processing features of numerical control processing, which is characterized in that the geometric shape of the processing feature is defined by the user according to the manufacturing resources, part structure and programming habits of the enterprise, and the topological relationship and surface and edge attributes of the processing feature geometric shape are defined. And the key geometric parameter information and calculation method of the processing feature are defined by the user, and each customized processing feature is given a unique identifier. After the user completes the interactive input of the processing feature information, the processing feature is expressed through structured data; Finally, feature recognition is carried out according to the topological relationship between the user-defined machining feature geometries and the attribute information of faces and edges, and the key geometric parameter information of the features is extracted. 2. A kind of numerical control processing custom processing feature method as claimed in claim 1, it is characterized in that described self-defining feature structured expression, is to automatically calculate the key attribute information and the key attribute information of each geometric element according to the geometric element selected by the user The connection information and position information between geometric elements are used to construct the attribute surface edge graph that defines the features, and the expression and output of the geometric elements of the processing features are realized in the tree structure of parent and child nodes. 3. A kind of numerically controlled processing custom processing characteristic method as claimed in claim 1, it is characterized in that described processing characteristic is analyzed, realizes the recognition of processing characteristic, is at first to construct the attribute face-edge diagram of whole part, according to definition Structured hierarchical structure of features, search for feature geometric elements that meet the conditions, construct user-defined processing features, and extract key parameter information of feature geometric elements. 4. A kind of numerical control processing custom processing characteristic method as claimed in claim 1, it is characterized in that realize the definition and analysis of processing technology rule by the following method: use the typical technological scheme of definition processing characteristic of interpretation type semantic rule, it is user according to The explanatory language rules provided by this method define the typical processing technology scheme of each element set of the feature, define the typical machining strategy, machining allowance, machining operation, machining tool and corresponding parameters of the machining feature, and at the same time, according to the machining accuracy of the feature, Key parameter information such as surface quality establishes process rules to determine the processing strategy, processing operation and corresponding parameters corresponding to each specific processing feature; the user selects the required driving geometry for various processing operations of the feature Elements, automatically record the selected driving geometry mode; establish rules based on the size of the feature and the machining allowance to determine the tool required for machining the feature; the user can define the intermediate processing state that needs to be detected for the machining feature, and can also be customized by the user Define the conditions required to trigger detection of intermediate machining states. 5. A method for custom processing features of numerical control machining, which is characterized in that the cutting parameters of numerical control machining are optimized based on user-defined processing features by the following method: according to the processing feature information, a feature-based cutting parameter optimization model is established, which is based on user-defined Define the geometric information and process information of the processing feature, obtain the intermediate processing state of the feature, match the mechanical model of the processing feature according to the intermediate state information and calculate the cutting force, deformation, power and other constraints, and consider the machine tool, tool and material information to calculate the processing The cutting parameters required for various operations of the feature, including spindle speed, feed rate, depth of cut, and width of cut. 6. A method for custom processing features of numerical control processing, characterized in that the automatic programming of numerical control processing based on custom processing features is realized by the following method: according to the geometric shape of the user-defined processing features and the user-defined processing technology scheme, establish Custom processing feature analysis program, the analysis program reads the unique identification of the custom processing feature geometric elements line by line, and judges the relationship between the user-defined processing feature geometry and user-defined processing technology through the judgment of key characters The relationship is analyzed to ensure the one-to-one correspondence between geometric elements and processing technology. The cutting parameters of each feature are optimized by the cutting parameter optimization model based on processing features, and the processing features are sorted by considering the processing deformation and processing path factors, and then Automatically generate machining tool paths for parts. 7. A method for custom processing features of numerical control machining, characterized in that the following method is used to realize the adaptive adjustment of the processing process based on the user-defined processing features: making adaptive adjustments based on the processing problems that occur during the processing process based on the user-defined processing features Strategy, adjust the processing strategy according to different detection or monitoring data, including clamping adjustment and tool path adjustment; formulate rules corresponding to different processing features and different processing operations for adaptive adjustment, and determine the adjustment strategy according to the rules.