CN108304686B

CN108304686B - Adaptive dynamic evolution calculation method for rough machining process

Info

Publication number: CN108304686B
Application number: CN201810372957.7A
Authority: CN
Inventors: 黄瑞; 程云; 蒋俊锋; 陈正鸣
Original assignee: Hohai University HHU
Current assignee: Hohai University HHU
Priority date: 2018-04-24
Filing date: 2018-04-24
Publication date: 2021-12-10
Anticipated expiration: 2038-04-24
Also published as: CN108304686A

Abstract

The invention discloses an adaptive dynamic evolution calculation method for rough machining process, which is used for machining complex cavity parts. The method firstly establishes a local The inscribed circle moves represent the model to guide the feature through the calculation of a roughing area and rest area. The type of residual region is then identified based on its mid-axis topology. Secondly, according to the primary roughing area and residual area of the feature, a dynamic evolution model of the roughing area and residual area of the part based on the initial process plan is established. Finally, an adaptive evolution mechanism of part roughing process driven by process design intention is proposed to eliminate the interference and undercut problems in the roughing process and ensure the continuity of the roughing process situation. The invention decides the self-adaptive evolution method of the rough machining process according to the type of residue and the time at which it is located, so as to make up for the deficiency of the geometric analysis of the existing method, reduce the burden of process designers, and improve the efficiency of numerical control programming.

Description

Adaptive dynamic evolution calculation method for rough machining process

Technical Field

The invention relates to a rough machining process self-adaptive dynamic evolution calculation method for complex cavity parts, and belongs to the field of feature-based numerical control process design and reuse in the manufacturing industry.

Background

In recent years, the content-based three-dimensional CAD model retrieval technology is widely researched, and abundant research results are obtained, so that designers can be helped to effectively find similar three-dimensional geometry, and a brand-new support means is provided for refining and reusing process data. The basic principle is as follows: through the relevance of the three-dimensional geometry and the numerical control process, the similar numerical control process is found by the similar three-dimensional geometry, then through the reusability of the numerical control process, the similar numerical control process is transplanted to the query three-dimensional geometry on the part to be manufactured, and the query three-dimensional geometry is adapted through the self-adaption of the similar numerical control process. However, the existing three-dimensional CAD model retrieval and numerical control process reuse technology still stays at the discovery level of similar numerical control processes, and is mainly used for designers to refer to, and the reuse process of the technology is very dependent on the experience and knowledge of the designers. In addition, even though the existing research results can automatically set the process parameters in the commercial CAM system (such as CATIA, UG, etc.), the designer needs to perform interactive iterative modification on the similar numerical control process according to the simulation results (including undercutting and interference, etc.) of each processing stage of the commercial CAM system based on the process design intention, and particularly in the rough processing stage of the part, so as to ensure that each processing stage is a complete and through process situation (no undercutting or undercutting exists), and thus a great amount of human-computer interaction is still needed. In order to realize the process data driven adaptive numerical control process design and further reduce the burden of process designers, the following key problems need to be solved: (1) how to efficiently and dynamically calculate a machining area and a residual area of the complex cavity characteristics according to a similar numerical control process; (2) how to adaptively change the similar numerical control process according to the process design intention of each processing stage of the part and the dynamic evolution calculation of the characteristic processing region and the residual region.

Disclosure of Invention

In order to overcome the defects, the invention provides a rough machining procedure self-adaptive dynamic evolution calculation method, which is oriented to complex cavity parts and adopts a rough machining procedure self-adaptive evolution mechanism to eliminate the problems of interference and under-cut in the rough machining process and ensure the connectivity of the rough machining process situation.

In order to achieve the purpose, the technical scheme of the invention is realized as follows:

a rough machining procedure self-adaptive dynamic evolution calculation method comprises the following steps:

(a) the complex contour of the feature is divided into a plurality of simple sub-contours through dynamic evolution calculation of a complex cavity rough machining region MR and a residual region UR guided by a feature center axis, and the machining region MR is obtained through the bias of the simple sub-contours;

(b) and a self-adaptive evolution mechanism of a part rough machining process driven by a process design intention is provided to eliminate the problems of interference and under-cut in the rough machining process and ensure the connectivity of the rough machining process situation.

Preferably, the dynamic evolution calculation of the rough machining region MR and the residual region UR of the complex cavity guided by the characteristic central axis includes the following specific steps:

1.1: introducing a local inscribed circle moving representation model, and calculating a primary rough machining region MR based on a characteristic central axis;

1.2: constructing an attribute adjacency graph according to the local inscribed circle moving representation model in the step 1.1, and classifying and calculating the primary rough machining residual region UR;

1.3: and (3) according to the processing region MR and the residual region UR calculated in the steps 1.1 and 1.2, realizing the construction of a dynamic evolution model of the characteristic rough processing region MR and the residual region UR.

Preferably, the specific calculation steps of the primary rough machining region MR based on the characteristic central axis in step 1.1 are as follows:

1.1.1: moving representation model r of each local inscribed circle of feature central axis MA (F) of traversing complex cavity feature F_i(s) calculating a local inscribed circle movement representation model r_i(s) and the horizontal line (R + delta) of the radius of the inscribed arc_r) Is the center of the inscribed arc and is according to r_i(s) and R + delta_rComparing the sizes of the characteristic axes MA (F) with the side e of the characteristic axis MA (F)_iDivided into multiple inscribed arcs s_iDividing the machining area constrained by the machining allowance into a zone association area machinable M and a zone association area non-machinable U;

1.1.2: representing the model r by local inscribed circle movement_i(s) and its class, construct r_i(s) attribute adjacency graph G;

1.1.3: the machinable M of the interval related area is taken as constraint and the depth is takenR in step 1.1.2_i(s) obtaining a plurality of connected subgraphs G from the attribute adjacency graph G_iEach connectivity sub-graph G_iCorresponding to a simple sub-contour, i.e. connected sub-graph G_iThe number is consistent with the number of the simple sub-outlines;

1.1.4: according to the connected subgraph G obtained in 1.1.3_iOffset distance delta by feature profile_rAnd calculating to obtain a processing area MR required by the complex cavity characteristic F in a primary rough processing stage.

Preferably, the specific calculation steps of the primary rough machining residual region UR in step 1.2 are as follows:

1.2.1: and (5) traversing r in the depth direction 1.1.2 by taking the unmanageable U of the interval association region as a constraint_i(s) obtaining a plurality of connected subgraphs G from the attribute adjacency graph G_iEach connectivity sub-graph g_iCorresponding to a sub-process residual SUR_iI.e. process residue UR^P＝∪SUR_i；

1.2.2: due to each connectivity graph g_iDifferent topological structures are provided, and each topological structure corresponds to one type of process residues; thus, according to the connectivity sub-graph g in 1.2.1_iThe topology of (1.2.1), the process residues in (1.2.1) are divided into fillet residues F-UR^PResidual B-UR in single bottle neck^PResidual MB-UR in multiple bottle necks^PAnd composite residual C-UR^P；

1.2.3: the process residue UR in step 1.2.2^PThe range is controlled by the radius R of the tool, when R approaches 0, only the residual UR remains^AIt is recorded as

Therefore, UR^PThe calculation of (d) translates into a machining region MR (0, delta) with a tool radius of 0_r) With a machining region MR (R, delta) of tool radius R_r) Between Boolean operations, i.e. UR^P＝MR(0,δ_r)－MR(R,δ_r)；

1.2.4: according to the inscribed arc s in step 1.1.1_iAnd connectivity sub-graph g in 1.2.1_iThe corresponding relation between the vertexes of (1) and the establishment of the SUR of the sub-process residue_iAnd g_iIn betweenCorrelation relationship by which and in 1.2.2 according to g_iThe process residue classification of the topological structure of (1) judges the SUR of the sub-process residue_iType (c) of the cell.

Preferably, the representation method of the local inscribed circle movement representation model is as follows: giving a complex cavity characteristic F, wherein the central axis MA is composed of a plurality of central axis edges e_iComposition, i.e. MA (F) { e_i}，1≤i≤n_mWherein n is_mCharacteristic middle shaft edge e of complex cavity characteristic F_iQuantity, characteristic axial edge e_iAt an arbitrary point v on_i(s)，s∈[s_min,s_max]Where s is a characteristic arc length parameter corresponding to a point on the axial edge, there being one or more points each having a length v_i(s) is a circle center O_i(s) local inscribed circle LIC, when LIC is along e_iWhile moving, its radius r_i(s) changing continuously, i.e. using r_i(s) characterization of e_iBalance r_i(s) is e_iThe LIC moving representation model of (1) is recorded as

The characteristic central axis of the complex cavity characteristic F is represented as MA (F) ═ r_i(s)}，1≤i≤n_m。

Preferably, said r_i(s) attribute adjacency graph G vertices correspond to

The attribute of the endpoint is taken as the attribute of the vertex; r is_i(s) Attribute adjacency graph G characteristic Axis edge e_iThe corresponding movement representation model is

Class of which is characteristic of medial axis edge e_iWherein the category includes a machinable M section associated region and a non-machinable U section associated region.

Preferably, said step 1.2.2 is according to g_iThe topology of (2) implements residual region classification, which is expressed as formula (1):

wherein a is_iDenotes g_iVertex v in (1)_iDegree, | G in G_i| represents attribute adjacency graph g_iNumber of vertices of (1), T (g)_i) Denotes g_iCorresponding to the type of process residue.

Preferably, the dynamic evolution model of step 1.3 is denoted as M_k,jDynamically evolving model F from multiple features_i.M_k,jConstitution F_i.M_k,jDriven by parameters reflecting the design intention of the process and realized by the process of removing the margin between adjacent processes in a dynamic evolution model, i.e.

F_i.M_k,j＝F_i.M_k,j-1-F_i.M_k,j

MR(F_i.M_k,j)＝f(F_i.M_k,j-1,R,δ_r)

F_i.M_k,j＝(MR,z_t,z_b,n)

UR(F_i.M_k,j)＝UR(F_i.M_k,j-1)-MR(F_i.M_k,j)

Wherein the parameters comprise a tool T and a radial allowance delta_rAxial margin delta_aN is F_iIn the axial direction of the tool, MR (F)_i.M_k,j) A processing area F (F) obtained by projecting the characteristic dynamic evolution model to an XY plane along the Z-axis direction in a local coordinate system_i.M_k,j-1,R,δ_r) Constructing a function for the effective machining area, R being the radius of the tool T, z_t、z_bAre respectively F_i.M_k,jTop and bottom surface constraint of UR (F)_i.M_k,j) And representing a residual region obtained by projecting the characteristic dynamic evolution model to an XY plane along the Z-axis direction in a local coordinate system.

Preferably, the adaptive evolution mechanism of the part rough machining process driven by the process design intent is divided into the following two types:

the first method comprises the following steps: longitudinal adaptation, in one process step, the complex cavity features F of which are machined in sequence, and each machining operation only machines one feature, given any one machining operation op_iSuppose op_iFor feature F_nOf the machining region MR_niProcessing is carried out when feature F_mAnd feature F_nWhen the formula (2) is satisfied, MR in the processing region is required_niFeature F from top to bottom before cutting_mThe layers of (2) are left to be cut off, and the formula (2) is as follows:

wherein, F_mAnd F_nRepresenting two features with a longitudinal dependency between them, i.e. F_m→F_nAnd which are machined in the roughing stage using different tools, UR_mj(j-1, 2) represents F_mTwo-layer residue of (1), MR_niIs represented by F_nI th of (1)^thCutting the secondary machining area;

and the second method comprises the following steps: lateral adaptation, assuming t₁Each feature of time F_mIs URm₁For any of its sub-residual SURs_iIf SUR is not_iThe type of the (D) is fillet residue, so that the treatment is not needed; if SUR_iIf the type of (d) is non-fillet residue, then according to its corresponding sub-graph g_iEach side e_iSelecting a tool T satisfying the condition shown in formula (3):

where R is the radius of the tool T, where T is along g_iWith each edge moving without interference, T being a tool, by adding a new roughing step to cut off the SUR_i。

Has the advantages that: the invention provides a rough machining process self-adaptive dynamic evolution calculation method, which is applied to the machining of complex cavity parts and has the following advantages:

(1) establishing a local inscribed circle movement representation model to calculate a rough machining area and a residual area of the cutter considering the radial allowance, and judging the type of the residual according to the middle shaft topological structure of the residual area;

(2) a self-adaptive evolution mechanism of the rough machining process is provided, and the connectivity of the rough machining process situation of the part is ensured through the longitudinal and transverse self-adaptation of the step correlation characteristics in the rough machining stage of the part, so that the process design intention of the rough machining of the part is realized.

(3) The self-adaptive evolution method of the rough machining process is decided according to the type of the residue and the time of the residue, and the process design intention is used as a drive, so that the defects of the existing method from the geometric analysis are overcome;

(4) the burden of process designers is reduced, and the numerical control programming efficiency is improved.

Drawings

FIG. 1 is a general block diagram of the method of the present invention;

FIG. 2 is a schematic diagram of the calculation of the primary rough machining area based on the characteristics of the middle axis transformation in the method of the present invention;

FIG. 3 is a schematic illustration of the classification of process residues according to the method of the present invention;

FIG. 4 is a schematic illustration of a calculation of a primary rough process residue according to the method of the present invention;

FIG. 5 is a schematic diagram of the longitudinal adaptation of the roughing process of the present invention.

Detailed Description

In order to make those skilled in the art better understand the technical solutions in the present application, the technical solutions in the embodiments of the present application are clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

1.1.2: according to local inscribed circle movementRepresentation model r_i(s) and its class, construct r_i(s) attribute adjacency graph G;

1.1.3: traversing r in step 1.1.2 in depth by taking machinable M of the interval associated region as constraint_i(s) obtaining a plurality of connected subgraphs G from the attribute adjacency graph G_iEach connectivity sub-graph G_iCorresponding to a simple sub-contour, i.e. connected sub-graph G_iThe number is consistent with the number of the simple sub-outlines;

1.2.3: the process residue UR in step 1.2.2^PMainly due to the capability of the tool, the extent of which is governed by the radius R of the tool, UR being the greater R^PThe more, and when R is smaller, UR^PThe less, and thus when R goes to 0, there is only a residual UR^AIt is recorded as

Therefore, UR^PThe calculation of (d) translates into a machining region MR (0, delta) with a tool radius of 0_r) With a machining region MR (R, delta) of tool radius R_r) BetweenBy Boolean operation of, i.e. UR^P＝MR(0,δ_r)－MR(R,δ_r)；

1.2.4: according to the inscribed arc s in step 1.1.1_iAnd connectivity sub-graph g in 1.2.1_iThe corresponding relation between the vertexes of (1) and the establishment of the SUR of the sub-process residue_iAnd g_iThe correlation between the two and the g in 1.2.2_iThe process residue classification of the topological structure of (1) judges the SUR of the sub-process residue_iType (c) of the cell.

Preferably, said r_i(s) attribute adjacency graph G vertices correspond to

Class of which is characteristic of medial axis edge e_iWherein the categories includeThe section related area can be processed by M and the section related area can not be processed by U.

From the formula (1), the fillet residue F-UR^PHas only one edge and contains a vertex with a degree of 1, indicating a F-UR^PPresent at concave corners of the feature profile; for bottleneck residual B-UR^PAnd MB-UR^PEach of the edges of (a) having a degree of each vertex of not less than 2, such that they are generated primarily from non-concave corner elongate regions of the feature profile; and compound residual C-UR^PConsists of fillet remnants and bottleneck remnants, so that at least one vertex with the degree of 1 and a vertex with the degree of not less than 2 exist, and the 2 vertexes need a vertex with the degree of not less than 3 to connect the 2 vertexes together, so that the 2 vertexes mainly exist in an elongated area adjacent to the concave corner.

F_i.M_k,j＝F_i.M_k,j-1-F_i.M_k,j

MR(F_i.M_k,j)＝f(F_i.M_k,j-1,R,δ_r)

F_i.M_k,j＝(MR,z_t,z_b,n)

UR(F_i.M_k,j)＝UR(F_i.M_k,j-1)-MR(F_i.M_k,j)

Wherein the parameters comprise a tool T and a radial allowance delta_rAxial margin delta_aN is F_iIn the axial direction of the tool, MR (F)_i.M_k,j) A processing area F (F) obtained by projecting the characteristic dynamic evolution model to an XY plane along the Z-axis direction in a local coordinate system_i.M_k,j-1,R,δ_r) Constructing a function for the effective machining area, R being the radius of the tool T, z_t、z_bAre respectively F_i.M_k,jTop and bottom surface constraint of UR (F)_i.M_k,j) And (3) representing a residual region obtained by projecting the characteristic dynamic evolution model to an XY plane along the Z-axis direction in a local coordinate system (Z ═ -n).

wherein, F_mAnd F_nRepresenting two features with a longitudinal dependency between them, i.e. F_m→F_nAnd which are machined in the roughing stage using different tools, UR_mj(j＝1,2) Is represented by F_mTwo-layer residue of (1), MR_niIs represented by F_nI th of (1)^thCutting the secondary machining area;

FIG. 1 is a general block diagram of a rough machining process adaptive dynamic evolution calculation method for complex cavity parts, and the working flow of the invention is as follows: firstly, according to the corresponding relation between the central axis of the characteristic and the circle center of an inscribed circular arc of a processing area, a local inscribed circle movement representation model is established to guide the calculation of the characteristic primary rough processing area MR and a residual area UR; then identifying the type of the middle shaft topological structure according to the residual region; secondly, establishing a dynamic evolution model of the rough machining area and the residual area of the part based on the initial process scheme according to the characteristic primary rough machining area and the residual area; and finally, providing a self-adaptive evolution mechanism of the rough machining process of the part driven by the process design intention so as to eliminate the problems of interference and under-cut in the rough machining process and ensure the connectivity of the rough machining process situation.

FIG. 2 is a schematic diagram of MR calculation of a characteristic primary rough machining region based on medial axis transformation, and FIG. 2(a) is a characteristic F_iCentral axis MA (white line). FIG. 2(b) is a middle axis edge e₁When F represents the model_iWhen a rough machining (2 mm radial allowance) is carried out once by using a cutter with the radius of 13mm, e₁Is divided into two intersection points v₄(s₁) And v₅(s₂) Divided into 3 sections, i.e. v₃-v₄，v₄-v₅，v₅-v₆Wherein v is₃-v₄And v₅-v₆Is located at a horizontal line l₁Top, indicating that these regions are workable; and v is₄-v₅At l₁Below, it is indicated that these areas are not machinable. Similarly, for other middle axle edge e_i(i is 1,2, …,11), and the attribute of the corresponding side of each subinterval is determined. R as shown in FIG. 2c can be constructed from the segmented medial axis edges_iAnd the attribute connection graph G is formed, wherein the attribute of the black line segment is M, and the attribute of the white line segment is U. Obtaining 2 connected subgraphs G through depth traversal G₁And G₂. FIG. 2d is a schematic representation of_i(i 1,2) with the vertex with the intersection point as the attribute value as the center (e.g., v)₂，v₄，v₃Etc.) build radius R + δ_rInscribed arc of (F)_iIs divided into 2 simple sub-profiles L₁And L₂. At this time, simple sub-profile L₁And L₂At delta_rIs an offset of the distance to obtain F _i2 sub-machining regions C to be cut off at one rough machining stage₁And C₂I.e. MR_i＝C₁∪C₂As shown in fig. 2 e.

FIG. 3 is a schematic diagram showing the classification of UR residues in a process, wherein 4F-UR residues are contained in Case^P2B-UR^PWith 1C-UR^P。

FIG. 4 shows feature F_iSchematic diagram of the primary rough machining process residue calculation. In fig. 4a, the radius of the tool is 0, and 1 machining area C is obtained by the method of step 1₃(white line), FIG. 4b shows 2 sub-machining regions C with a tool radius R₁And C₂From equation (2), 7 sub-residual regions (closed black lines) can be calculated, as shown in fig. 4 c. Due to g₄Vertex v of₁₈Is an inscribed arc s₁Is at the center of the circle of₁Belong to SUR₄Thus SUR₄And g₄Correlation, SUR is known from the formula (1)₄Is of type B-UR^P。

Fig. 5 is a schematic diagram of longitudinal adaptation of a rough machining process. Suppose F₂Is absent, F₁After longitudinal adaptation, if non-fillet residuals (e.g., SUR) are still present₁) Then a suitable tool T is selected according to equation (3), at T₁A secondary rough machining step is added at any moment to cut off the SUR₁So that F₁To achieve radial allowance (delta) at rough machining stage_r2) and axial margin (δ)_a2) as a processing target.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Two modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. a rough machining procedure self-adaptive dynamic evolution calculation method, is characterized in that: the method comprises the following steps:

(a) Through the dynamic evolution calculation of the rough machining area MR and the residual area UR of the complex cavity guided by the feature center axis, the complex contour of the feature is divided into multiple simple sub-contours, and then the machining area MR is obtained by the offset of the simple sub-contours ;

The specific steps for the dynamic evolution calculation of the rough machining area MR and the residual area UR of the complex cavity guided by the central axis of the feature are as follows:

1.1: Introduce the local inscribed circle movement representation model, and calculate the rough machining area MR based on the central axis of the feature;

The specific calculation steps of the rough machining area MR based on the central axis of the feature in the step 1.1 are as follows:

1.1.1: Traverse the movement of each local inscribed circle of the feature axis MA(F) of the complex cavity feature F to represent the model ri ( _s ), and calculate the movement of the local inscribed circle to represent the relationship between the model ri ( _s ) and the inscribed circle. The intersection of the arc radius horizontal line R+δ _r , the intersection is the center of the inscribed arc, and according to the size comparison between ri (s) and R+δ _r , the edge e _i of the feature central axis MA (F ₎ is divided It is a plurality of inscribed arcs s _i , and the machining area constrained by the machining allowance is divided into the interval associated area M that can be machined and the interval associated area unmachinable U;

1.1.2: According to the movement of the local inscribed circle to represent the model ri ( _s ) and its category, construct the ri ( _s ) attribute adjacency graph G;

1.1.3: Taking the machinable M of the interval associated area as the constraint, traverse the r _i (s) attribute adjacency graph G in step 1.1.2 in depth to obtain multiple connected subgraphs G _i , each connected subgraph G _i corresponds to a simple Sub-contours, that is, the number of connected sub-graphs G _i is consistent with the number of simple sub-contours;

1.1.4: According to the connected subgraph G _i obtained in 1.1.3, calculate the machining area MR required by the complex cavity feature F in the rough machining stage with the offset distance δ _r of the feature contour;

1.2: According to the local inscribed circle movement representation model in step 1.1, construct its attribute adjacency graph, and classify and calculate the residual area UR of a rough machining;

The specific calculation steps of the residual area UR of a rough machining in the step 1.2 are as follows:

1.2.1: Constrained by the unprocessable U of the interval associated area, deeply traverse the ri (s) attribute adjacency graph G in 1.1.2 to obtain multiple connected subgraphs g _i , and each connected subgraph _{g i} _corresponds to a subgraph Process residue SUR _i , that is, process residue UR ^P =∪SUR _i ;

1.2.2: Since each connected subgraph _gi has a different topology, each topology corresponds to a type of process residue; therefore, according to the topology of the connected subgraph _gi in 1.2.1, the Process residues are divided into fillet residue F-UR ^P , single-bottleneck residue B-UR ^P , multi-bottleneck residue MB-UR ^P and compound residue C-UR ^P ;

In the step 1.2.2, the residual region classification is realized according to the topological structure of _gi , and its expression is shown in formula (1):

where a _i represents the degree of the vertex vi in _gi in G, | _gi | represents the number of vertices in the attribute adjacency graph _gi , and T( _gi ₎ represents the type of process residue corresponding to _gi ;

1.2.3: The range of the process residual UR ^P in the step 1.2.2 is controlled by the tool radius R. When R tends to 0, there is only the residual residual UR ^A , which is recorded as

Therefore, the calculation of UR ^P is transformed into a Boolean operation between the machining area MR(0,δ _r ) with the tool radius 0 and the machining area MR(R,δ _r ) with the tool radius R, that is, UR ^P =MR(0 ,δ _r )-MR(R,δ _r );

1.2.4: According to the corresponding relationship between the inscribed arc _si in step 1.1.1 and the vertices of the connected subgraph _gi in 1.2.1, establish the relationship between the sub-process residual SUR _i and _gi , the type of sub-process residual SUR _i is judged by this relationship and the classification of process residues according to the topology of g _i in 1.2.2;

The representation method of the local inscribed circle movement representation model is as follows: Given a complex cavity feature F, the feature central axis MA is composed of multiple central axis edges e _i , that is, MA(F)={e _i }, 1 ≤i≤n _m , where n _m is the number of feature axis edges e _i of the complex cavity feature F, any point vi ( _s ) on the feature axis edge e _i , s∈[s _min ,s _max ] , where s is the arc length parameter corresponding to the point on the edge of the feature axis, there is a local inscribed circle LIC with vi (s) as the center O _i ₍ s), when LIC moves along e _i , its The radius ri ( _s ) changes continuously, that is, ri ( _s ) is used to characterize _ei , and ri ( _s ) is called the LIC movement representation model of _ei , which is denoted as

The feature center axis of the complex cavity feature F is expressed as MA(F)={r _i (s)}, 1≤i≤n _m ;

The r _i (s) attribute adjacency graph G vertices correspond to

The end point of , the attribute of the end point is used as the attribute of the vertex; the movement representation model corresponding to the axis edge e _i in the feature of the adjacency graph G of the attribute ri (s) is as follows _:

The category to which it belongs is used as the attribute of the axis edge e _i of the feature, and the category includes the machinable M in the interval associated area and the unmachinable U in the interval associated area;

1.3: According to the processing area MR and residual area UR calculated in steps 1.1 and 1.2, realize the dynamic evolution model construction of the characteristic rough machining area MR and residual area UR;

The dynamic evolution model in the step 1.3 is denoted as M _k,j , which is composed of multiple feature dynamic evolution models F _i .M _k,j , and F _i .M _k,j In the evolution model, the process of allowance removal between adjacent processes is realized, that is,

F _i .M _k,j =F _i .M _k,j-1 -F _i .M _k,j

MR(F _i .M _k,j )=f(F _i .M _k,j-1 ,R,δ _r )

F _i .M _k,j =(MR,z _t ,z _b ,n)

UR(Fi.Mk _,j ₎ =UR(Fi.Mk, _j _-1 )-MR(Fi.Mk _,j ₎

Wherein, the parameters include tool T, radial allowance δ _r , axial allowance δ _a , n is the tool axial direction of F _i , and MR(F _i .M _k,j ) represents the feature dynamic evolution model in local coordinates It is the machining area obtained by projecting the XY plane along the Z-axis direction, f(F _i .M _k,j-1 ,R,δ _r ) is the construction function of the effective machining area, R is the radius of the tool T, z _t , z _b are the top and bottom constraints of F _i .M _k,j respectively, and UR(Fi .M _k,j ₎ represents the residual area obtained by projecting the feature dynamic evolution model along the Z axis to the XY plane in the local coordinate system;

(b) Propose an adaptive evolution mechanism of rough machining process driven by process design intent to eliminate interference and undercut problems during rough machining and ensure the continuity of rough machining process scenarios;

The self-adaptive evolution mechanism of the rough machining process of the parts driven by the process design intent is divided into the following two types:

The first type: longitudinal self-adaptation, in one step, its complex cavity features F are processed in sequence, and each processing operation only processes one feature, given any processing operation op _i , assuming that op _i is paired with The processing area MR _ni of the feature F _n is processed. When the relationship between the feature F _m and the feature F _n satisfies the formula (2), it is necessary to remove the residual layers of the feature F _m from top to bottom before cutting the processing area MR _ni . , the formula (2) is as follows:

Among them, F _m and F _n represent two features, when there is a longitudinal dependence between them, that is, F _m →F _n , and they are processed by different tools in the roughing stage, UR _mj (j=1,2) represents the two-layer residue of F _m , MR _ni represents the cutting of the ^ith machining area of F _n ,

The second type: lateral adaptation, assuming that the first layer residue of each feature F _m at time t ₁ is URm ₁ , for any of its sub-process residues SUR _i , if the type of SUR _i is rounded residue, no processing is required; If the type of SUR _i is non-rounded residual, select a tool T that satisfies the conditions shown in formula (3) according to the minimum radius of each edge e _i of its corresponding subgraph g _i :

Where R is the radius of the tool T, at this time, T moves along each edge of _gi without interference, T is the tool, and a new roughing step is added to remove SUR _i .