A method for quickly solving optimal rotating shaft based on inertia principal axis

Abstract

The application relates to the technical field of computer-aided design, in particular to a kind of optimal rotation axis fast solving method based on inertia principal axis, based on the inertia principal axis of part or assembly, the six extreme points of part or assembly on the three direction axes of its inertia principal axis are calculated;The length of three direction axes is calculated by the distance from extreme point to the three planes of inertia principal axis, and the direction axis with the longest length is taken as the optimal rotation axis. Through the solving method, the optimal rotation axis of a single part or assembly can be quickly solved, and the method has low complexity, short calculation time and high calculation efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of computer-aided design, in particular to a method for quickly solving optimal rotation axis based on inertia principal axis. BACKGROUND

[0002] In the production process of aviation, aerospace and large equipment, various assembly fixtures are often needed to meet the processing and assembly requirements of products. The turnover fixture is one of them. When using the turnover fixture, the product needs to be fixed on the turnover fixture to meet the processing requirements of the product in different postures. The turnover fixture structure mainly includes a support skeleton, a turnover frame, a turnover driving assembly and the like. In order to ensure the stability and reliability of the turnover frame of the turnover fixture during rotation, especially when the product is large in size and heavy in weight, the setting of the fixture turnover axis is particularly important.

[0003] At present, the design of the turnover axis of the fixture mainly follows three principles: the turnover axis is consistent with the long side direction of the rotating frame; the eccentricity between the combined center of gravity of the turnover frame, the positioner and the product and the turnover axis should not exceed 5mm during design; and the eccentricity between the combined center of gravity of the turnover frame and the positioner and the turnover axis should not exceed 10mm during manufacturing. However, this experience-based design principle is not the most reliable. The turnover fixture designed with this turnover axis may not have a moment of inertia of 0 along the axis direction after the product is assembled and rotated, causing instability during rotation, and even may cause the turnover frame to separate, resulting in product scrap. Therefore, determining a suitable rotation axis is the key to the design of the turnover axis.

[0004] From the perspective of theoretical mechanics, when an object rotates along its inertia principal axis, the moment of inertia along the principal axis direction is 0, that is, when the object rotates around a certain axis in the inertia principal axis, the force carried by the axis in the radial direction is the same. The inertia principal axis is composed of three orthogonal axes. From the perspective of the moment of inertia, the longest axis among the three axes should be taken to ensure the smallest moment of inertia, that is, when the object rotates around the longest axis in the inertia principal axis, the force carried by the axis in the radial direction is the same and the smallest. Therefore, the longest axis in the inertia principal axis can be used as the optimal rotation axis for the design of the turnover fixture axis. SUMMARY

[0005] To solve the above technical problems, the present application provides a method for quickly solving optimal rotation axis based on inertia principal axis, which can quickly solve the optimal rotation axis of a single part or assembly, and has low complexity, short calculation time and high calculation efficiency.

[0006] The present application is implemented by adopting the following technical solutions:

[0007] A method for quickly solving optimal rotation axis based on inertia principal axis, characterized by comprising the following steps:

[0008] Step S1. Based on the inertia principal axis of the part or assembly, six extreme points of the part or assembly on three direction axes of the inertia principal axis are calculated;

[0009] Step S2. The length of the three direction axes is calculated from the distance of the extreme points to the three planes of the inertia principal axis, and the direction axis with the longest length is taken as the optimal rotation axis.

[0010] The solving method uses the existing secondary development interface of CATIA to realize each step.

[0011] The step S1 specifically includes the following steps:

[0012] Step S 11 Obtain the inertia attribute of the part;

[0013] Step S 12 Calculate the origin coordinates of the inertia principal axis, and establish the origin coordinate reference;

[0014] Step S 13 Calculate the three direction vectors of the inertia principal axis, and define the X, Y, Z axes under the inertia principal axis;

[0015] Step S 14 Define the YZ, XZ, XY planes under the inertia principal axis;

[0016] Step S 15 Obtain the reference geometry of the part;

[0017] Step S 16 Calculate the six extreme points of the reference geometry in the X, Y, Z axis directions.

[0018] The step S 13 specifically includes the following steps:

[0019] Step S 131 Calculate the three direction vectors (A 1x , A 1y , A 1z ), (A 2x , A 2y , A 2z ), (A 3x , A 3y , A 3z ) of the inertia principal axis;

[0020] Step S 132 Obtain the creation geometry factory object of the part, and create the corresponding direction objects DirX, DirY, DirZ according to the coordinate values of the three direction vectors in step S 131 ;

[0021] Step S 133 According to the origin coordinate reference and the direction object, define the X, Y, Z axis straight lines LineX, LineY, LineZ under the inertia principal axis, and the straight line length is arbitrary length.

[0022] The step S 14 Specifically: create a new plane in the "straight line-straight line" manner, and define the YZ, XZ, XY planes P YZ , P XZ , P XY respectively according to the X, Y, Z axis straight lines under the inertia principal axis.

[0023] The six extreme points include the X-axis maximum value point X max , the X-axis minimum value point X min , the Y-axis maximum value point Y max , the Y-axis minimum value point Y min , the Z-axis maximum value point Z max , and the Z-axis minimum value point Z min .

[0024] The step S2 specifically includes the following steps:

[0025] Step S 21 . Establish the reference planes YZRef, XZRef, XYRef of the YZ, XZ, XY planes;

[0026] Step S 22 . Establish the X, Y, Z axis direction reference extreme points;

[0027] Step S 23 . Calculate the sum Δx of the distance between the X axis direction reference extreme point and the reference plane YZRef of the YZ plane, the sum Δy of the distance between the Y axis direction reference extreme point and the reference plane XZRef of the XZ plane, and the sum Δz of the distance between the Z axis direction reference extreme point and the reference plane YZRef of the XY plane;

[0028] S 23 . Compare the sizes of Δx, Δy, and Δz, and select the direction axis corresponding to the maximum value as the optimal rotation axis.

[0029] The step S 11 Further includes the following steps:

[0030] Step S 01 . Obtain the current object, which includes the part and the assembly;

[0031] Step S 02 . Determine whether the current obtained object is an assembly, if yes, convert the assembly into a part and then enter step S 03 , if not, directly enter step S 03;

[0032] Step S 03 If the part includes multiple part geometries, all part geometries under the part are assembled into the same part geometry through Boolean operation, and then the step S is entered 11 If not, the step S is directly entered 11 .

[0033] Compared with the prior art, the application has the beneficial effects as follows:

[0034] Compared with the prior art, the application provides a rotation axis fast solving method based on inertia principal axis, which meets the rotation stability of theoretical mechanics, can quickly solve the optimal rotation axis of the part or assembly, has fast solving speed and accurate optimal rotation axis direction, and can improve the design work efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0035] The application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0036] Figure 1 The figure is a flowchart of the application;

[0037] Figure 2 The figure is a schematic diagram of the connecting angle used in example 3 of the application;

[0038] Figure 3 The figure is a schematic diagram of the effect of generating CATPart from the product in example 3 of the application;

[0039] Figure 4 The figure is a schematic diagram of the inertia principal axis origin calculated in example 3 of the application;

[0040] Figure 5 The figure is a schematic diagram of the inertia principal axis origin calculated in example 3 of the application;

[0041] Figure 6 The figure is a schematic diagram of the three direction axes of the inertia principal axis defined in example 3 of the application;

[0042] Figure 7 The figure is a schematic diagram of the three planes of the inertia principal axis defined in example 3 of the application;

[0043] Figure 8 The figure is a schematic diagram of the six extreme points calculated in example 3 of the application;

[0044] Figure 9Fig. 1 is a schematic diagram of distances from six extreme points calculated in Example 3 of the invention to three planes. DETAILED DESCRIPTION

[0045] Example 1

[0046] As a basic embodiment of the invention, the invention includes a method for quickly solving an optimal rotation axis based on an inertia principal axis, which aims to obtain an optimal rotation axis of a single part or an assembly, and includes the following steps:

[0047] Step S1. Based on the inertia principal axis of the part or the assembly, six extreme points of the part or the assembly on three directional axes of the inertia principal axis are calculated.

[0048] Step S2. The lengths of the three directional axes are calculated from the distances of the extreme points to the three planes of the inertia principal axis, and the directional axis with the longest length is taken as the optimal rotation axis.

[0049] The present application can quickly solve the optimal rotation axis of a part or an assembly, and the solving speed is fast and the direction of the optimal rotation axis obtained is accurate, which can improve the design work efficiency.

[0050] Example 2

[0051] As a preferred embodiment of the invention, the invention includes a method for quickly solving an optimal rotation axis based on an inertia principal axis, which is realized by using the existing secondary development interface of CATIA, and the detailed description is shown in the accompanying drawings Figure 1 , and specifically includes the following steps:

[0052] Step S1. Based on the inertia principal axis of the part or the assembly, six extreme points of the part or the assembly on three directional axes of the inertia principal axis are calculated. Specifically, the following steps are included:

[0053] Step S 01 . Obtain the current object, which includes parts and assemblies;

[0054] Step S 02 . Determine whether the current obtained object is an assembly. If yes, convert the assembly into a part through the "Tools-Generate CATPart from Product" command of CATIA, and then enter step S 03 . If not, directly enter step S 03 ;

[0055] Step S 03 . Determine whether the part includes multiple part geometries. If yes, assemble all part geometries under the part into the same part geometry through the AddNewAssemble() function Boolean operation, and then enter step S 11 . If not, directly enter step S 11 .

[0056] Step S 11 . Get the inertia property oInertia of the part oPartDoc through the GetTechnologicalObject ("Inertia") interface: Set oInertia = oPartDoc.Product.GetTechnologicalObject ("Inertia").

[0057] Step S 12 . Directly calculate the inertia principal axis origin coordinates (x0, y0, z0) of oInertia through the GetCOGPosition () function: oInertia.GetCOGPosition Coordinates, Coordinates is an array consisting of coordinate values (x0, y0, z0); establish the reference point P of the origin coordinates (x0, y0, z0) through the CreateReferenceFromObject () function ref .

[0058] Step S 13 . Calculate the three direction vectors of the inertia principal axis, and define the X, Y, Z axes under the inertia principal axis, which specifically includes:

[0059] Step S 131 . Directly calculate the three direction vectors (A 1x , A 1y , A 1z ), (A 2x , A 2y , A 2z ), (A 3x , A 3y , A 3z ) of oInertia through the GetPrincipalAxes () function: oInertia.GetPrincipalAxesComponents, Components is an array consisting of three direction vector values.

[0060] Step S 132 . Get the create geometry factory object oHSF of the part, and through the AddNewDirectionByCoord () function, respectively input the coordinate values of the three direction vectors in step S 131 , create direction objects DirX, DirY, DirZ, for example, create the direction object DirX of the X direction: Set DirX = oHSF.AddNewDirectionByCoord (A 1x , A 1y , A1z ).

[0061] Step S 133 . Create a new line in "point-direction" mode by the AddNewLinePtDir() function, input the origin coordinate reference point P ref and the direction object in step S 132 , define the X, Y, Z axis lines LineX, LineY, LineZ under the inertia principal axis respectively, the line length is arbitrary, for example, create a LineX with a length of 88 mm: Set LineX = oHSF.AddNewLinePtDir(P ref , DirX, -88, 0, False).

[0062] Step S 14 . Define the YZ, XZ, XY planes under the inertia principal axis: create a new plane in "line-line" mode by the AddNewPlane2Lines() function, input the axis lines in step S 133 , define the YZ, XZ, XY planes P YZ , P XZ , P XY under the inertia principal axis respectively, for example, define P YZ : Set P YZ = oHSF.AddNewPlane2Lines(LineY, LineZ).

[0063] Step S 15 . Get the part reference geometry BodyRef.

[0064] Step S 16 . Calculate the six extreme points of the reference geometry in the X, Y, Z axis directions: input the part reference geometry BodyRef and the planes defined in step S 14 by the AddNewExtremum() function, calculate the six extreme points of the reference geometry in the X, Y, Z axis directions respectively: the X axis maximum point X max , the X axis minimum point X min , the Y axis maximum point Y max , the Y axis minimum point Y min , the Z axis maximum point Z max , and the Z axis minimum point Z min .

[0065] The calculation method of X max is as follows:

[0066] Set X max= oHSF.AddNewExtremum (BodyRef, DirX, 1)

[0067] X max .Direction2 = DirY

[0068] X max .ExtremumType2 = 1

[0069] X max .Direction3 = DirZ

[0070] X max .ExtremumType3 = 1

[0071] X min The calculation method is as follows:

[0072] Set X min = oHSF.AddNewExtremum (BodyRef, DirX, 0)

[0073] X min .Direction2 = DirY

[0074] X min .ExtremumType2 = 0

[0075] X min .Direction3 = DirZ

[0076] X min .ExtremumType3 = 0.

[0077] Step S2. Calculate the lengths of the three direction axes from the distances of the extremum points to the three planes of the principal axis of inertia, and take the direction axis with the longest length as the optimal rotation axis. Specifically, the following steps are included:

[0078] Step S 21 . Establish the reference planes YZRef, XZRef, XYRef of the YZ, XZ, XY planes. The reference planes YZRef, XZRef, XYRef of P YZ , P XZ , P XY are established by the CreateReferenceFromObject () function, for example, YZRef is established as follows: Set YZRef = oPartDoc.Part.CreateReferenceFromObject (P YZ ).

[0079] Step S 22. Establish reference extreme points in X, Y, Z axis direction: through CreateReferenceFromObject() function to establish step S 16 Reference extreme points of 6 extreme points in middle 6: X maxRef , X minRef , Y maxRef , Y minRef , Z maxRef , Z minRef , for example, establish X maxRef : Set X maxRef = oPartDoc.Part.CreateReferenceFromObject(X max ).

[0080] Step S 23 . Calculate the sum Δx of the distance between X axis direction reference extreme point and reference plane YZRef of YZ plane, calculate the sum Δy of the distance between Y axis direction reference extreme point and reference plane XZRef of XZ plane, calculate the sum Δz of the distance between Z axis direction reference extreme point and reference plane YZRef of XY plane.

[0081] Through GetMeasurable() function to obtain the measurable attribute M maxRef and M minRef of X Xmax and X Xmin , for example, Set M Xmax = TheSPAWorkbench.GetMeasurable(X maxRef ), wherein TheSPAWorkbench is Workbench object: Set TheSPAWorkbench = oPartDoc.GetWorkbench("SPAWorkbench"); and through GetMinimumDistance() function to calculate the distance of M Xmax and M Xmin to reference plane YZRef respectively: Δx1 = M Xmax .GetMinimumDistance(YZRef), Δx2 = M Xmin .GetMinimumDistance(YZRef), and the sum Δx of the distance = Δx1 + Δx2.

[0082] Through GetMeasurable() function to obtain the measurable attribute M maxRef and M minRef of Y Ymax and Y Ymin , for example, Set M Ymax= TheSPAWorkbench.GetMeasurable(Y maxRef ) ; and then the distances of M Ymax and M Ymin to the reference plane XZRef are calculated respectively by the GetMinimumDistance() function: Δy1 = M Ymax .GetMinimumDistance(XZRef), Δy2 = M Ymin .GetMinimumDistance(XZRef), and the sum of the distances Δy = Δy1 + Δy2.

[0083] The measurement properties M maxRef and M minRef of Z Zmax and Z Zmin are obtained by the GetMeasurable() function, for example, SetM Zmax = TheSPAWorkbench.GetMeasurable(Z maxRef ) ; and then the distances of M Zmax and M Zmin to the reference plane XYRef are calculated respectively by the GetMinimumDistance() function: Δz1 = M Zmax .GetMinimumDistance(XYRef), Δz2 = M Zmin .GetMinimumDistance(XYRef), and the sum of the distances Δz = Δz1 + Δz2.

[0084] S 23 . Compare the values of Δx, Δy and Δz, and select the direction axis corresponding to the maximum value as the optimal rotation axis.

[0085] Embodiment 3

[0086] As another preferred embodiment of the present application, the present application includes a fast solving method of the optimal rotation axis based on the inertia principal axis, referring to the attached drawings of the specification, taking the connecting angle as an example, including the following steps: Figure 2

[0087] Step S1. Based on the inertia principal axis of the part or assembly, the six extreme points of the part or assembly in the three direction axes of the inertia principal axis are calculated. Specifically, the following steps are included:

[0088] Step S 01 . Obtain the current object, which includes the part and the assembly;

[0089] Step S 02 ​. Determine if the current acquisition object is an assembly, if yes, convert the assembly to a part by "Tools-From Product Generate CATPart" command, then, as shown in the accompanying drawings of the specification Figure 3 , go to step S 03 , if no, go to step S 03 ;

[0090] Step S 03 . Determine if the part includes multiple part geometries, if yes, assemble all part geometries under the part into one part geometry by AddNewAssemble() function Boolean operation, as shown in the accompanying drawings of the specification Figure 4 , go to step S 11 , if no, go to step S 11 .

[0091] Step S 11 . Get the part inertia attribute through GetTechnologicalObject("Inertia") interface.

[0092] Step S 12 . Calculate the inertia principal axis origin coordinates as (0, 47.812, 40.852) through GetCOGPosition() function, and establish the origin coordinate reference through CreateReferenceFromObject() function, as shown in the accompanying drawings of the specification Figure 5 .

[0093] Step S 13 . Calculate the inertia principal axis three direction vectors A1(1, 0, 0), A2(0, -0.775235, 0.631673), A3(0, -0.631673, -0.775235) through GetPrincipalAxes() function, and define the X, Y, Z axes under the inertia principal axis, as shown in the accompanying drawings of the specification Figure 6 .

[0094] Step S 14 . Define the YZ, XZ, XY planes under the inertia principal axis, as shown in the accompanying drawings of the specification Figure 7 .

[0095] Step S 15 . Get the part reference geometry.

[0096] Step S 16 . Calculate the 6 extreme points of the reference geometry in the X, Y, Z axis directions through AddNewExtremum() function: X axis maximum value, X axis minimum value, Y axis maximum value, Y axis minimum value, Z axis maximum value, Z axis minimum value, as shown in the accompanying drawings of the specification Figure 8 .

[0097] Step S2. Calculate the lengths of the three direction axes from the distances of the extreme points to the three planes of the principal axis of inertia, and take the direction axis with the longest length as the optimal rotation axis. Specifically, the following steps are included:

[0098] Step S 21 . Establish the reference planes YZRef, XZRef, XYRef of the YZ, XZ, XY planes through the CreateReferenceFromObject() function;

[0099] Step S 22 . Establish the reference extreme points of the six extreme points in step S16 through the CreateReferenceFromObject() function;

[0100] Step S 23 . Refer to the attached drawings of the specification Figure 9 . Calculate the sum of the distances of the two reference extreme points in the X-axis direction to YZRef through the GetMinimumDistance() function, Δx = 100 + 100 = 200. Calculate the sum of the distances of the two reference extreme points in the Y-axis direction to XZRef through the GetMinimumDistance() function, Δy = 102.853 + 112.778 = 215.631. Calculate the sum of the distances of the two reference extreme points in the Z-axis direction to XYRef through the GetMinimumDistance() function, Δz = 61.871 + 59.295 = 121.166.

[0101] S 23 . Compare the sizes of Δx, Δy, and Δz, and select the direction axis corresponding to the largest value as the optimal rotation axis. Because Δy > Δx > Δz, the Y-axis defined in step S 13 is selected as the optimal rotation axis.

[0102] In summary, after reading the present application document, the person of ordinary skill in the art can make other various corresponding transformation schemes according to the technical solutions and technical concepts of the present application without creative mental labor, and all of the transformation schemes belong to the scope protected by the present application.

Claims

1. A method for quickly solving the optimal rotation axis based on the inertia principal axis, characterized by: The following steps are involved: Step S1. Based on the principal axis of inertia of the part or assembly, six extreme points of the part or assembly on the three directions of its principal axis of inertia are calculated; the six extreme points include the X-axis maximum point X max , X-axis minimum point X min , Y axis maximum point Y max , Y-axis minimum point Y min , Z axis maximum point Z max , Z-axis minimum point Z min ; Step S2. Calculate the lengths of the three directional axes from the distances of the extreme point to the three planes of the principal axis of inertia, and take the directional axis with the longest length as the optimal rotation axis; the three planes are the YZ plane, the XZ plane, and the XY plane.

2. The method for quickly determining the optimal rotation axis based on the inertia principal axis according to claim 1, characterized in that: This solution method uses CATIA's existing secondary development interface to implement each step.

3. The method for quickly determining the optimal rotation axis based on the inertia principal axis according to claim 2, characterized in that: The step S1 specifically includes the following steps: Step S 11 . Get the part inertia property; Step S 12 . Calculate the origin coordinates of the inertia principal axis and establish the origin coordinate reference; Step S 13 Calculate the three direction vectors of the principal axis of inertia and define the X, Y, and Z axes under the principal axis of inertia; Step S 14 . Define the YZ, XZ, and XY planes under the principal axes of inertia; Step S 15 . Get part reference geometry; Step S 16 . Calculate the six extreme points of the reference geometry in the X, Y, and Z axis directions.

4. The method for quickly determining the optimal rotation axis based on the inertia principal axis according to claim 3, characterized in that: The step S 13 The specific steps include: Step S 131 . Calculate the three direction vectors of the principal axis of inertia (A 1x , A 1y , A 1z )、(A 2x , A 2y , A 2z )、(A 3x , A 3y , A 3z ); Step S 132 . Get the part's geometry factory object, according to step S 131 Create corresponding direction objects DirX, DirY, and DirZ based on the coordinate values ​​of the three direction vectors; Step S 133 . Based on the origin coordinate reference and direction object, define the X, Y, and Z axis lines LineX, LineY, and LineZ under the main axis of inertia. The length of the line can be any length.

5. The method for quickly determining the optimal rotation axis based on the inertia principal axis according to claim 3, characterized in that: The step S 14 Specifically: Create a new plane in a "straight line-straight line" manner, and define the YZ, XZ, and XY planes P under the principal axis of inertia according to the X, Y, and Z axis lines. YZ 、P XZ 、P XY .

6. The method for quickly determining the optimal rotation axis based on the inertia principal axis according to claim 3, characterized in that: The step S2 specifically includes the following steps: Step S 21 . Create reference planes YZRef, XZRef, and XYRef for the YZ, XZ, and XY planes; Step S 22 . Establish reference extreme points in the X, Y, and Z axis directions; Step S 23 Calculate the sum of the distances Δx between the reference extreme point in the X-axis direction and the reference plane YZRef of the YZ plane, calculate the sum of the distances Δy between the reference extreme point in the Y-axis direction and the reference plane XZRef of the XZ plane, and calculate the sum of the distances Δz between the reference extreme point in the Z-axis direction and the reference plane YZRef of the XY plane. Step S 24 Compare the values ​​of Δx, Δy, and Δz, and select the direction axis corresponding to the largest value as the optimal rotation axis.

7. A method for quickly determining the optimal rotation axis based on the inertia principal axis according to claim 3 or 6, characterized in that: The step S 11 The previous steps also included: Step S 01 Get the current object, which includes parts and assemblies; Step S 02 . Determine whether the current object is an assembly. If so, convert the assembly into a part and proceed to step S 03 If not, go directly to step S 03 ; Step S 03 . Determine whether the part includes multiple part geometries. If so, assemble all the part geometries under the part into the same part geometries through Boolean operations, and then proceed to step S 11 If not, go directly to step S 11 .

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