JP2006330917A - Method for designing shape of machine structure having rolling element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for designing the shape of a machine structure having a rolling element that makes it possible to achieve maximum rigidity with minimum volume without depending on expertise, while providing stresses that meet evaluation criteria. <P>SOLUTION: Topology optimization or region shape optimization is carried out in order to achieve either rigidity maximization or weight reduction, and the structural configuration of the relative positions of a bearing and a rib on a hub wheel is determined (SP1-SP5). A basic shape is determined by approximating an optimal structural configuration, a dimensional parameter is set for the basic shape, and finite element analysis associated with the set dimensional parameter is carried out (SP6-SP12). The dimension of the element of each part is optimized (SP13, SP14). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a shape design method for a machine structure having rolling elements, for example, a shape design method for a machine structure having rolling elements such as a hub bearing that is a bearing for a wheel of an automobile.

  FIG. 10 is a longitudinal sectional view of a conventional hub bearing. The hub bearing shown in FIG. 10 is used for a drive wheel of a vehicle, and includes a hub wheel 1 and a double-row rolling bearing 2. The hub wheel 1 has a hollow structure, and a radially outward flange portion 11 is formed by forging at an axially intermediate portion of the outer peripheral surface, and a spline is formed in a predetermined region in the hollow hole 40. ing. The inner ring raceway surface 12 of the ball group 22 on the other side (vehicle outer side) of the double row rolling bearing 2 is integrally formed on the outer peripheral surface on one side (vehicle inner side) of the flange portion 11. A shaft body (not shown) is splined to the hollow hole 40.

  The double row rolling bearing 2 includes a single outer ring 21 having two rows of raceway grooves, a plurality of ball groups 22, 24 as rolling elements arranged in two rows, two cages 23, and a seal 26. The inner ring 25 relating to the ball group 24 on the vehicle inner side and the raceway surface 12 provided on the hub wheel 1 are configured.

  A double row rolling bearing 2 is attached to the outer peripheral surface of the hub wheel 1. A vehicle inner side end portion of the hub wheel 1 is bent radially outward and is caulked against a vehicle inner side end surface of the inner ring 25 of the double row rolling bearing 2. This caulking portion is indicated with a symbol A.

  Then, the disc rotor 4 of the disc brake device and a wheel (not shown) are guided to the flange portion 11 of the hub wheel 1 by the pilot portion 14 and attached by a plurality of bolts 13. A radially outward mounting piece 27 provided on the outer ring 21 of the double row rolling bearing 2 is fixed to the vehicle body 5 with bolts 39.

  The hub bearing that is the wheel bearing for automobiles shown in FIG. 10 is required to reduce the weight of the bearing and reduce the torque of the bearing. This is because resource saving can be achieved by reducing weight and fuel efficiency can be reduced by reducing torque. For this purpose, “Monthly Tribology” (Non-Patent Document 1) introduces analysis technology using the finite element method by changing the dimensional values such as the thickness of the flange and the arc radius of the joint, and stress analysis and rigidity analysis. And a method for determining a shape satisfying the stress value, rigidity, and weight by trial and error is described.

  Here, the finite element method is an approximate analysis method for analyzing the deformation and stress of a structure by a computer, approximating by dividing a complex shape / property object into simple small parts. Is intended to predict the behavior of

  In order to analyze the optimum shape of a structure, various methods have been proposed in the past. For example, Japanese Patent Laid-Open No. 2002-7487 (Patent Document 1) discloses a shape that maximizes rigidity for a plurality of constrained volumes. Detecting the response amount for evaluating each shape and determining the correlation between the constrained volume and the response amount, and detecting the minimum volume that satisfies the design conditions from this correlation Is described.

In JP 2003-288373 A (Patent Document 2), in a model creation software such as a mesh generator or a preprocessor, a unit macro file that defines a unit macro operation for creating a unit shape model of a specific part is created in advance. It describes a method for creating a shape model for analysis that creates a shape model having a plurality of specific parts by repeatedly executing this unit macro file.
Japanese Patent Laid-Open No. 2002-7487 (paragraph number 0027, FIG. 2) JP 2003-288373 A (paragraph numbers 0020 to 0031, FIG. 4) “Monthly Tribology” Shinkisha, published in April 2003, p. 12-15

  In the method described in Non-Patent Document 1, the shape of some parts of the hub bearing is partially changed. However, the structure of a member in which a material is attached to a necessary portion and the material is scraped from the unnecessary portion. No study has been made on the form, and only an improvement study has been made on the basis of the existing shape or some initial shape.

  For this reason, a truly optimal shape was not obtained, and it was possible to further optimize and reduce the weight, but wasteful material remained as meat. In particular, when the required levels of stress value, weight, and rigidity are severe, there is a problem that the objective cannot be achieved and the basic shape is not appropriate.

  Further, even when the shape is changed, the dimensions are not changed on the basis of some reason, but the method is such that the dimensions are changed discretely by trial and error, and thus the obtained value is not an optimum value. The obtained value is discrete and so-called discrete, so it does not capture the optimum value, and if each part dimension is intertwined and has a complicated response, only the local optimum value is obtained There is a problem that there is. That is, even if the shape is an appropriate shape designed to optimize the structure, it is not suitable as a study method. Therefore, in the conventional method, there is a problem with a method for determining a truly optimum dimension.

  Even if the techniques described in Patent Documents 1 and 2 are applied to the shape optimization design of the hub bearing, it is not possible to examine the optimization of the accurate form. In other words, in the hub bearing, stress and displacement are greatly affected by the mounting condition with the mating surface, so it is necessary to consider contact with the mating surface when performing topology optimization or region shape optimization, Regarding the part to be processed by forging, it is necessary to analyze so that the shape considering the workability at the time of forging is created, and the shape obtained by topology optimization or region shape optimization is a free-form surface Therefore, it is necessary to replace it with an approximate shape that is easy to process, and it is necessary to perform dimension optimization analysis on the approximate shape. Hardened parts and parts with low hardness that are not heat-treated are mixed, and dimension optimization analysis that takes this into account is necessary. There is a unique circumstance that is.

  Accordingly, an object of the present invention is to provide a shape design method of a machine structure having a rolling element that can obtain the maximum rigidity with the minimum volume without experience and that can satisfy the evaluation criteria.

  The present invention is a shape design method for obtaining the shape of a machine structure having a plurality of elements including rolling elements, and topology optimization or region shape optimization is performed to maximize the rigidity and weight of the machine structure. To obtain the structural form optimized shape of the machine structure, determine the basic shape by approximating the obtained structural form optimized shape, set the dimensional parameter for the basic shape, and set the dimensional parameter Performing a coupled finite element analysis to determine dimensions in order to achieve maximum stiffness and light weight of the mechanical structure.

  By performing topology optimization or region shape optimization and finite element analysis linked to dimensional parameters, it is possible to design a mechanical structure having a maximum volume and a minimum rigidity without experience.

  Preferably, the step of obtaining the structural form optimization shape is set separately for each element of the initial shape in the mechanical structure, a region where the shape can be changed and a region where the shape cannot be changed, It includes performing topology optimization or region shape optimization in accordance with the setting of the load and constraint conditions. Thereby, the optimal shape can be obtained for the region where the shape can be changed.

  Preferably, the step of obtaining the structural form optimized shape includes performing topology optimization or region shape optimization by a method based on a homogenization method, a density method, a force method, or the like.

  Preferably, the mechanical structure having a rolling element includes a disk-like shape that contacts the mating member as an element or a flange portion that is partially cut away, and the step of obtaining a structure configuration optimized shape applies a load to the flange portion. In consideration of the fact that the mating member and the flange portion are in contact with each other, topology optimization or region shape optimization is performed. In this case, the analysis considering the contact can be easily performed by setting the area corresponding to one layer of the mesh dividing element on the contact surface side of the flange portion as the area where the shape cannot be changed due to the capability of the current analysis software. By considering the contact, the analysis can be performed in consideration of a mode in which the rotor and the flange part are partially separated by deformation when a load is applied.

  Preferably, the mechanical structure having the rolling elements includes a disc-shaped contact portion that contacts the mating member or a flange portion that is partially cut away, a bearing portion that is formed to extend from one side of the flange portion, and a flange portion. A bearing for a vehicle, which is formed to extend to the other side and includes a pilot part that guides a mating member of a flange part as an element. Topology under the condition that the inner diameter becomes smaller toward the inner part of the pilot inner diameter part and the condition that the inner diameter becomes smaller as it goes from the non-contact surface part of the flange part to the bearing part in consideration of the removal of the mold. Performing optimization or region shape optimization. Considering the gradient for forging die cutting, it is possible to prevent an obstacle in manufacturing a vehicle bearing.

  Preferably, the vehicle bearing includes a contact surface between the mating member and the flange portion, a plurality of ribs extending radially from the bearing on one surface of the flange portion, a bolt hole provided on a tip side of each rib, and a bearing The process of obtaining the optimized shape of the structure including the raceway surface and the seal part as the elements is to optimize the topology or the area shape using the volume or mass as a constraint condition and the strain energy or the displacement of a point as an objective function. The step of determining the dimensions including performing the optimization includes optimizing the dimensions of the rib width and wall thickness.

  Preferably, in the step of determining the dimensions, a finite element model is created for the basic shape determined from the obtained structural form optimization shape of the mechanical structure, the stress and rigidity are analyzed, and the dimensional parameter of each element is determined. The method includes a step of creating a morphing model so that the mesh shape can be changed in response to the change of the shape, and a step of optimizing the size of each element by applying various optimization algorithms. By creating a morphing model, it is possible to easily change the shape, and it is possible to arbitrarily set a shape such as an inclined surface from the thick part to the thin part of the rib.

  Preferably, the step of determining the size includes setting an allowable value of stress separately for a portion cured by heat treatment and an original soft portion not subjected to heat treatment.

  According to the present invention, the maximum rigidity can be obtained with the minimum volume without experience by performing the shape of the machine structure having rolling elements in two stages of topology optimization or region shape optimization and parameter optimization. Furthermore, the shape of the mechanical structure that can satisfy the standard value of the stress can be obtained.

  FIG. 1 is an external perspective view showing a hub wheel included in a hub bearing as an example of a mechanical structure having rolling elements according to an embodiment of the present invention. In FIG. 1, a bearing portion 53 is formed in the center portion on the vehicle inner side, which is one surface of the hub wheel 51, and a rib 54 having a certain width and thickness is formed on the bearing portion 53 in order to increase the strength. For example, it is formed at four locations so as to extend in the radial direction from the root. Each rib 54 has a thick portion on the inner diameter side and a thin portion on the distal end portion on the outer diameter side. Bolt holes 55 are formed in the thin-walled portion on the tip side of each rib 54 in order to fasten the tire wheel to the hub wheel 51 with bolts and nuts.

  A hollow hole 59 is formed in the bearing portion 53, and an inner ring raceway surface 56 that is in contact with the rolling elements of the double row rolling bearing shown in FIG. 10 is formed over the entire circumference around the bearing portion 53. A slope is formed at a portion from the rib 54 to the inner ring raceway surface 56 so that a die during forging can be removed. A small step is set in a part of the gradient, and the part is polished to form a seal land 57 with which the seal 26 shown in FIG. 10 contacts. The pilot portion 62 is formed in a cylindrical shape. The rib 54, the bearing portion 53, and the like constitute elements in the hub wheel 51 that is an example of a mechanical structure.

  FIG. 2 is an external perspective view showing an initial shape of the hub wheel before obtaining a structural form optimized shape, (A) is a perspective view seen from one side of the flange portion, and (B) is a perspective view of the flange portion. FIG. 3 is a perspective view seen from the other side, FIG. 3 is a longitudinal sectional view taken along line AA shown in FIG. 2 (A), (A) is a diagram showing the section with a mesh, (B) is sectional drawing which showed the below-mentioned shape changeable area | region and a shape impossible area | region.

  In the embodiment of the present invention, the rigidity is maximized and the weight is reduced by cutting unnecessary meat that has little influence on rigidity and deflection from the initial shape of the hub wheel 51 shown in FIG. 2 by topology optimization. The shape of the hub wheel 51 shown in FIG. 1 is obtained by obtaining the optimized shape of the structure, and then determining the basic shape so that it can be easily drawn, and optimizing the dimensional parameters such as the thickness and width of the rib 54. Is to decide.

  For this reason, the hub wheel 51 shown in FIG. 2 has an initial shape before the rib 54 shown in FIG. 1 is formed. That is, as shown in FIG. 2A, the flange portion 52a has a thick flat disk shape, and the shape is not fixed. Further, as shown in FIG. 3B, in relation to attachment with a mating surface such as a disk rotor, the flange portion 52b corresponding to one row in the thickness direction element of the mesh of the flange portion 52a, and the mounting bolt hole 55 The pilot 62 is a place where the shape cannot be changed, and these are places where the shape of the inner ring raceway surface 56 cannot be changed because of the load capacity with respect to the load, and are set as a shape-unchangeable region. Further, in the flange portion 52a, a region 63 indicated by a cross hatch in FIG. 3B and a region 64 indicated by a cross hatch that is an inner peripheral surface of the hollow hole 59 on the pilot 62 side are set as shape changeable regions. Is done. Further, in consideration of the detachment of the mold during forging, the flange portion 52a is in the B direction shown in FIG. 3 (B) under the condition that the inner diameter becomes smaller toward the bearing portion 53 on the non-contact surface side with the counterpart member 60. In addition, the pilot inner diameter portion is set so that the molds can be easily removed in the C direction shown in FIG. 3B under the condition that the inner diameter becomes smaller toward the inner diameter portion of the pilot 62.

  One end side of the hollow hole 59 shown in FIG. 3A is shown by integrating the inner ring 25 and the caulking portion A described with reference to FIG. A gap element 61 is defined on the contact surface between the flange portion 52 b that is a part of the flange portion 52 a and the mating member 60.

  The gap element 61 is used to express that the flange portion 52a and the mating member 60 are in contact with each other when modeling the analysis of the hub bearing. If the hub bearing is modeled as one that is integral with the mating material or the contact surface cannot be deformed at all without defining the contact state, proper analysis cannot be performed.

  This is because, when a load is applied, the flange portion 52a of the hub wheel 51 and the mating member 60 are in a restrained and stuck state, resulting in an analysis result different from the actual state. In order to correct this, a contact analysis is performed using the gap element 61. However, in FIG. 3, a gap is shown between the flange portion 52 a and the mating member 60, but in fact, the distance between the flange portion 52 a and the mating member 60 is 0, and thus the length of the gap element 61 Is 0. The gap element 61 has no restriction when the two members are separated from each other, but generates a reaction force with a certain rigidity when approaching.

  In addition to the gap element 61, the contact analysis includes a non-linear element and a master-slave method. These methods may be used, but in one embodiment of the present invention, the gap element 61 is used. Topology optimization considering contact.

  In addition, as described above, in FIGS. 3A and 3B, the flange portion 52b, which is a part of the flange portion 52a, is defined as a non-changeable region.

  In FIG. 3 (A), a measurement point y1 is used as an example for measuring the deflection of the hub wheel 51 when a load is applied to the bearing portion 53 at the raceway shoulders on one side and the other side of the bearing portion 53. , Y2 are defined. The difference in displacement between these measurement points y1 and y2 is obtained as an inclination. The inclination angle θ is obtained as tan δ / L from the displacement δ with respect to the interval L between y1 and y2. In addition, the measurement points y1 and y2 may be provided at four positions shifted by 90 degrees in the circumferential direction with respect to the central axis of the hollow hole 59 of the bearing portion 53, and the deflection may be measured at each measurement point.

  FIG. 4 is a block diagram of a control device for realizing a shape design method for a machine structure having rolling elements according to an embodiment of the present invention. In FIG. 4, the control device 70 includes an input unit 72 connected to the control unit 71, a display unit 73, and a printing unit 74. The control unit 71 executes a program for realizing the shape design method, and the input unit 72 includes a mouse and a keyboard for inputting various conditions. The display unit 73 displays the initial shape of the hub wheel 51, the model image formed by calculation, and the like, and the printing unit 74 prints the model image and the like.

  FIG. 5 is a flowchart for executing a structure shape designing method according to an embodiment of the present invention.

  When the control unit 71 executes the program based on the flowchart shown in FIG. 5, the image of the initial shape and cross-sectional shape of the hub wheel shown in FIG. 2 and FIG. Is displayed so as to be input from the input unit 72. The operator looks at the display and operates the input unit 72 to set an area where the shape cannot be changed and an area where the shape cannot be changed in steps SP1 and SP2 shown in FIG.

  That is, in the hub wheel 51 shown in FIG. 2, the shape changeable region and the shape changeable region are set for the mesh shown in FIG. 3A as described in FIG. 3B. In step SP3, the operator sets a load condition, a constraint condition, a contact condition, and a forging draft. An input load applied to the hub wheel 51 from the road surface is defined as a load condition, and a gap element 61 is defined as a contact condition at a contact portion between the mating member 60 shown in FIG. 3 and the flange portion 52a. At this time, as described with reference to FIG. 3A due to the capability of the current analysis software, one row of elements on the flange portion 52a side at the contact portion between the mating member 60 and the flange portion 52a (one element in the flange thickness direction). Is an area where the shape cannot be changed. 3B, the flange portion 52a is set in the B direction, and the inner diameter portion of the pilot 62 is set in the C direction.

  In step SP4, a stiffness maximizing function (deflection angle minimization) and strain energy minimization are defined as objective functions, and the volume or mass of the member is defined as a constraint condition. Furthermore, in order to consider the rotational symmetry, the symmetry in the circumferential direction is taken into consideration about the axis of the hollow hole 59 of the bearing portion 53 for each bolt hole 55. For example, when four bolt holes 55 are provided, each bolt hole 55 is provided on the other surface of the hub wheel 51 at intervals of 90 degrees in the circumferential direction. After these definitions are made, in step SP5, the control unit 71 obtains a basic shape by performing topology optimization analysis or region shape optimization by a method based on a homogenization method or a method based on a force method.

  Here, the topology optimization analysis refers to a technique for obtaining a phase shape having an optimal structure form in a space, and is an analysis for determining how members are arranged to obtain an optimal structure. This is a method of setting a space that is slightly larger than the analysis target and extracting the necessary parts. The area shape optimization analysis is also the same as the topology optimization, but is different from the topology optimization analysis in that it is obtained by changing the region (shape) of the structure.

  As a topology optimization method, for example, Bendsoe, M. et al. P. and Kikuchi, N .; , “Generating optimal topologies in structural design a homogenization method”, Comput. Methods Appl. Mech Engrg. 71 (1988). pp. There is a method based on the homogenization method proposed by 197-224. Moreover, as an optimization method by the force method, for example, Hideyuki Kurakami, Shishi Kure, “Area Optimization Analysis in Linear Elasticity Problem (Approach by Force Method)”, Japanese Society of Mechanical Science, A, 60 (578), 1994, pp. 2312-2318. There is.

  Furthermore, in order to perform topology optimization, software such as OptiStruct (Altern Engineering), OptiShape, GENESIS (VDOC), NASTRAN, and OptiShape for area shape optimization are used. Can be used.

  FIG. 6 is a diagram when the volume is changed as a constraint condition in order to explain the topology optimization, and FIG. 7 is a diagram showing the relationship between the volume ratio of the hub wheel and the deflection.

  The volume ratio of the hub wheel 51 shown in FIG. On the other hand, the hub wheel 51 has a volume ratio of 1.15 in FIG. 6A, a volume ratio of 1.0 in FIG. 6B, and a volume ratio of 0.85 in FIG. The surplus part is cut and rigidity is improved. FIGS. 6A to 6C are represented by straight lines in the drawing of the drawings, but are actually curved surfaces.

  In addition, the horizontal axis of FIG. 7 indicates the volume ratio, and the vertical axis indicates the deflection. In FIG. 7, a to c indicate deflection values with respect to the volume ratios of the hub wheels 51 having the respective shapes illustrated in FIGS. Comparing FIGS. 6B and 6D, the volume ratio is the same, but FIG. 6B is a preferable shape with less deflection.

  As is apparent from FIGS. 6 and 7, the value of deflection increases as the volume ratio decreases. This deflection is a difference in displacement between the measurement points y1 and y2 as described with reference to FIG. It can be seen that when the thickness of the thin portion and the thick portion is reduced by reducing the thickness of the thin portion and the thick portion, and the width is reduced to reduce the weight, the deflection is increased and the rigidity is reduced. The thickness of the surplus portion is shaved so that the deflection does not become a predetermined value or less, the rigidity is improved, and the topology is optimized. In this embodiment, the purpose is to make the rigidity equal to or more than the current shape of FIG. 6D without changing the weight, so the finally obtained hub bearing 51 has the shape of FIG. 6B.

  The structural form optimized shape obtained by the topology optimization analysis shown in FIG. 6B is generally complicated and is a free-form surface, so that it is difficult to process the shape as it is. For this reason, in step SP6, the operator obtains a shape approximated by a flat surface, a cylindrical surface, or a conical surface so as to be easily processed based on the shape of FIG. 6B, and determines this as a basic shape. In step SP7, the determined basic shape is displayed on the display unit 73 as a three-dimensional CAD image. At this time, printing may be performed by the printing unit 74 as necessary.

  In step SP6 described above, since the basic shape is approximated by a flat surface and a cylindrical surface and the like is deviated from the optimum value, the dimensions of each part are appropriately changed to obtain the optimum dimensions. That is, in conjunction with the creation of the mesh model for size optimization analysis in step SP7, in step SP8, the operator determines the size to be changed and the size not to be changed.

  In step SP9, the morphing technique is applied to the dimension change portion determined in step SP8 to create a morphing model whose shape can be varied with respect to design variables such as thickness.

  FIG. 8 shows an example of a morphing model, which shows a cross section of a slope between a thin wall portion and a thick wall portion from the tip portion of the rib 54 to the seal land, and (A) inflates the slope of the rib 54. (B) shows a flat slope, and (C) shows a concave slope. Thus, the morphing model can easily change the mesh using the existing mesh model. Such a morphing model can be created using morphing software such as MeshWorks / Morpher (Ibaraki Hitachi Information Service), HyperMorph (Altar Engineering), Soft (MSC), and the like.

  In step SP10, the operator defines a load condition, a constraint condition, and the like for the created morphing model, and creates a finite element analysis model. In step SP11, the structural analysis is performed by calculating the stress and displacement of each part using finite element analysis software such as ABAQUS, Marc, and NASTRAN. In finite element analysis, non-linear analysis considering contact and the like may be performed, and a domain decomposition method may be used for large-scale problems.

  When the analysis result is obtained in step SP12, the result is taken in, and whether or not the size is optimized in step SP13 by size optimization software such as HyperStudy (Altern Engineering), iSIGTH (Engineering), Optimus (Cybernet), or the like. Is determined.

If not optimized, in step SP14, the dimensions are changed by an optimization method. As an algorithm of the optimization method, a mathematical method, an approximate method such as a response surface method, an experimental design method, a search method such as a genetic algorithm (GA) simulated annealing (SA) can be applied. The changed dimensions are reflected in the morphing model in step SP9, and the following steps SP10 to SP14 are repeated. FIG. 9 shows an example in which seven dimension parameters h, b, y ₁ , x ₂ , y ₂ , x ₃ , y ₃ are set.

  9A is an external perspective view of a model in which the hub wheel is cut in half, and FIG. 9B is a model from the thick part of the rib to the thin part of the tip shown in FIG. (C) is a cross-sectional view of the gradient of the model from the thick portion of the rib shown in (A) to the thin portion of the tip, and (D) is shown in (A). FIG. 6 is a partially broken perspective view in which a gradient portion of a model from a thick portion of the rib 54 to a thin portion at the tip is extracted. In FIG. 9, the model cut in half is used for analysis with a reduced amount of calculation. When there is symmetry, such a method is usually used.

The dimensional parameter h is the height of the thin portion at the tip of the rib 54 as shown in FIGS. 9C and 9D, and the dimensional parameter b is the rib 54 as shown in FIGS. 9B and 9D. a half of the width, dimensional parameters f ₀ is a fixed value a thick portion tangent end points of the ribs 54, as shown in FIG. 9 (B). The dimension parameters f _{1 to} f ₈ are the values of the respective parts from the thick part to the thin part in the rib 54 as shown in FIG. 9D. The symbols x _{n in} parentheses of the dimension parameters f _{1 to} f ₆ are the X axis. The height _n indicates the position of the rib 54 on the Y axis. X ₄ and Y ₄ are predetermined fixed values at the stepped portion extending from the seal land 57. When fixed values f ₀ , X ₄ , and Y ₄ are input from the input unit 12, seven dimension parameters h, b, y ₁ , x ₂ , y ₂ , x ₃ , y ₃ are obtained by the processing in steps SP10 to SP14. Is set and the dimensional parameters f _{1 to} f ₈ are determined, so that the shape of the thin portion and the thick portion of the rib 54 is determined.

  Further, as shown in FIG. 9A, the surfaces of the inner ring raceway surface 56 and the seal land 57 of the bearing portion 53 are defined as a quenching region 58 indicated by a cross hatch, and the other regions are defined as non-quenching regions. Has been. In some cases, an upper limit value of stress is obtained as a constraint condition for optimization, but a relatively high allowable stress is set in the quenching region 58 relative to the non-quenching region so that the capacity of the material is fully used.

  In step SP13, when it is determined that the shape is optimal based on the set dimensional parameters, the finite element analysis input model in step SP10 is determined and output as the optimal shape.

  As described above, according to this embodiment, the width and thickness of the ribs 54 of the hub wheel 51 are determined without experience, by performing shape optimization in two stages of topology optimization and parameter optimization. An optimum shape can be obtained. As a result, it is possible to cut the excess meat, to obtain the maximum rigidity with the minimum volume while reducing the weight, and to obtain the hub wheel 51 in which the stress satisfies the standard value.

  In the above description, the present invention is applied to the case where the optimum shape of the hub wheel 51 is obtained. However, the present invention is not limited thereto, and other rolling elements such as a constant velocity joint and a rocker arm are provided. The present invention can also be applied to obtaining an optimum shape of a machine structure having elements.

  As mentioned above, although embodiment of this invention was described with reference to drawings, this invention is not limited to the thing of embodiment shown in figure. Various modifications and variations can be made to the illustrated embodiment within the same range or equivalent range as the present invention.

  The shape design method for a mechanical structure having rolling elements according to the present invention is used for designing a hub wheel, a constant velocity joint, a rocker arm and the like in a hub bearing which is a bearing for an automobile.

It is an external appearance perspective view which shows the hub wheel contained in the hub bearing of an example of the mechanical structure which has a rolling element in one Embodiment of this invention. It is an external appearance perspective view which shows the initial shape of the hub wheel before calculating | requiring topology optimal shape, (A) is an external appearance perspective view seen from the one surface side of a flange part, (B) is from the other surface side of a flange part. FIG. FIG. 3 is a longitudinal sectional view taken along line AA shown in FIG. It is a block diagram of a control device for realizing a shape design method of a machine structure having rolling elements in one embodiment of this invention. It is a flowchart for performing the shape design method of the machine structure which has a rolling element in one Embodiment of this invention. It is a figure when changing the volume as a constraint condition in order to explain topology optimization. It is a figure which shows the relationship between the deflection | deviation of a hub wheel, and volume ratio. An example of the morphing model is shown, and a cross section from the tip of the rib to the seal land is shown. It is a figure which shows the model for demonstrating dimension optimization. It is a longitudinal cross-sectional view of the conventional hub bearing.

Explanation of symbols

  51 Hub wheel, 52, 52a Flange part, 53 Bearing part, 54 Rib, 55 Bolt hole, 56 Inner ring raceway surface, 57 Seal land, 58 Hardened area, 59 Hollow hole, 60 Mating member, 61 Gap element, 62 Pilot, 70 Control device, 71 control unit, 72 input unit, 73 display unit, 74 printing unit.

Claims (8)

A shape design method for obtaining a shape of a machine structure having a plurality of elements including rolling elements,
Performing topology optimization or area shape optimization for maximizing rigidity and weight reduction of the mechanical structure to obtain a structural form optimized shape of the mechanical structure;
The basic shape is determined by approximating the obtained structural form optimization shape, dimensional parameters are set for the basic shape, and finite element analysis is performed in conjunction with the set dimensional parameters to determine the rigidity of the mechanical structure. A method for designing a shape of a machine structure having rolling elements, the method comprising: determining a dimension to achieve maximization and weight reduction.   The step of obtaining the structural form optimization shape is divided into a region in which the shape can be changed and a region in which the shape cannot be changed among the elements of the initial shape in the mechanical structure, and a load, The shape design method for a machine structure having rolling elements according to claim 1, comprising performing the topology optimization or the region shape optimization in response to a constraint condition being set.   The step of obtaining the structural form optimized shape includes performing the topology optimization or the region shape optimization by a method based on a homogenization method, a density method, a force method, or the like. A shape design method for a machine structure having a moving body. The mechanical structure having the rolling elements includes a disk-like shape that contacts a mating member as the element or a flange portion in which a part thereof is cut out.
The step of obtaining the structural form optimized shape is performed in the topology optimization or the region while considering that the counterpart member and the flange portion are in contact with each other when a load is applied to the flange portion. The shape design method for a machine structure having a rolling element according to claim 1, comprising performing shape optimization. The mechanical structure having the rolling element includes a disc-shaped contact portion that contacts the mating member or a flange portion that is partially cut away, a bearing portion that is formed to extend from one side of the flange portion, and the flange portion. A vehicle bearing that is formed to extend to the other side and includes a pilot portion that guides a mating member of the flange portion as the element;
The step of obtaining the structure configuration optimized shape is based on the condition that the inner diameter becomes smaller toward the inner side of the pilot inner diameter part in consideration of the detachment of the mold at the time of forging, and the bearing part from the non-contact surface part of the flange part The shape design of the machine structure having a rolling element according to claim 1, wherein the topology optimization or the region shape optimization is performed under a condition that an inner diameter becomes smaller toward the head. Method. The vehicle bearing includes a contact surface between the mating member and the flange portion, a plurality of ribs extending in a radial direction from the bearing on one surface of the flange portion, and a bolt hole provided on a distal end side of each rib. And the raceway surface and the seal portion of the bearing as the element,
In the step of obtaining the optimized shape of the structure, the contact surface of the flange portion, the raceway surface of the bearing, the seal, the bolt hole, and the pilot are set as regions in which the shape cannot be changed. The contact surface side is set as a region where the shape can be changed, and the topology optimization or the region shape optimization is performed using the volume or mass as a constraint condition and the strain energy or the displacement of a certain point as an objective function. Including
6. The shape design method for a machine structure having rolling elements according to claim 5, wherein the step of determining the dimensions includes optimizing at least the width and thickness of the ribs of the flange portion. Determining the dimensions comprises:
A finite element model is created for the basic shape in response to a change in the dimensional parameter of each element in the structural form optimized shape of the obtained mechanical structure, stress and stiffness analysis is performed, and the dimensional parameter Creating a morphing model so that the mesh shape can be changed in response to
A method for designing a shape of a machine structure having rolling elements according to any one of claims 1 to 6, including a step of optimizing the dimensions of each element by applying various optimization algorithms.   The rolling element according to any one of claims 1 to 7, wherein in the step of determining the dimensions, the evaluation criteria are set separately for a portion cured by heat treatment and an original soft portion not subjected to heat treatment. A method for designing the shape of a mechanical structure.

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