Design method of gantry machining center beam and beam structure

Abstract

This invention relates to the field of machine tool equipment technology, and discloses a design method and structure for the crossbeam of a gantry machining center. The design method includes the following steps: constructing a finite element analysis model of the gantry machining center, the model including a crossbeam, column, spindle, guide rail, slide saddle, slide block, slider, and lead screw nut; constructing a topology optimization analysis working condition and obtaining the analysis results; the working condition includes crossbeam assembly deformation caused by gravity and crossbeam deformation caused by cutting force; constructing a topology optimization model and performing topology optimization on the working condition; designing the crossbeam parameters of the finite element analysis model; calculating the sensitivity of each parameter to crossbeam deformation and obtaining the optimal parameter values. Simultaneously considering the crossbeam assembly deformation caused by gravity and the crossbeam deformation caused by cutting force, weighted performance parameters for evaluating the comprehensive performance of the crossbeam are constructed. After verification and iterative optimization, the stiffness and accuracy of the crossbeam are controlled, thus improving the machining capability and accuracy of the gantry machining center.

Description

Technical Field

[0001] This invention relates to the field of machine tool equipment technology, specifically to a design method and structure for a crossbeam of a gantry machining center. Background Technology

[0002] A gantry machining center, also known as a metal gantry machining center or CNC machine tool, is a highly efficient and automated machine tool. Its spindle Z-axis is perpendicular to the worktable, and the overall structure is a large machining center with a gantry frame consisting of two columns and a top beam, with a crossbeam in the middle of the two columns. This structure makes gantry machining centers particularly suitable for machining large and complex-shaped workpieces.

[0003] Gantry machining centers can be classified into fixed-beam, moving-beam, moving-column, and bridge types according to their structure. The most common type is the fixed-beam type. A fixed-beam gantry machining center mainly consists of a base, worktable, column, crossbeam, carriage, ram, saddle, spindle, guide rails, lead screw nut, lead screw socket, tool magazine, and drive system. The crossbeam is one of the key components, and its accuracy directly affects the machine tool's accuracy; therefore, the design of the crossbeam is particularly important.

[0004] The crossbeam of a gantry machining center must consider both the assembly deformation caused by gravity and the deformation caused by cutting force. Originally, the analysis of these two load conditions was done by directly superimposing them. The condition with significantly larger deformation would mask the condition with smaller deformation. As a result, one aspect of the crossbeam's stiffness or accuracy was ignored, and it was impossible to achieve a balance between the two. Summary of the Invention

[0005] In view of this, the present invention provides a design method and structure for a crossbeam of a gantry machining center, in order to solve the problem that the design of the crossbeam of a gantry machining center in related technologies cannot simultaneously take into account the rigidity and accuracy of the crossbeam.

[0006] In a first aspect, the present invention provides a method for designing a crossbeam for a gantry machining center, comprising the following steps:

[0007] A finite element analysis model of a gantry machining center is constructed. The model includes a crossbeam, column, spindle, guide rail, saddle, ram, slider, and lead screw nut.

[0008] Construct topology optimization analysis conditions and obtain analysis results; the conditions include beam assembly deformation caused by gravity and beam deformation caused by cutting force.

[0009] Construct a topology optimization model and perform topology optimization for the described working condition;

[0010] Design the structural layout of the beam in the finite element analysis model;

[0011] Sensitivity analysis was performed on the beam parameters to obtain the optimal parameter values.

[0012] Beneficial effects: This invention considers both the beam assembly deformation caused by gravity and the beam deformation caused by cutting force, constructs weighted performance parameters to evaluate the comprehensive performance of the beam, lays out the beam structure, and performs sensitivity analysis on the beam parameters to ensure the rigidity and accuracy of the beam. Compared with related technologies that ignore either rigidity or accuracy, this invention ensures both the rigidity and accuracy of the beam, optimizes the beam design, and improves the machining capability and accuracy of the gantry machining center.

[0013] In one optional implementation, the boundary conditions of the finite element analysis model include:

[0014] A fixed constraint is set on the joint surface of the beam and the column;

[0015] The crossbeam and the guide rail are bound together; the slide, the guide rail and the main shaft are bound together; the slide saddle and the slider are bound together; the slide saddle and the lead screw nut are bound together; the lead screw nut and the slide saddle are connected by a lead screw; and the guide rail and the slider are slidably connected.

[0016] Beneficial effects: By setting constraints on the model based on the structure and connection relationships of the gantry machining center, more accurate optimization parameters can be obtained. The extracted loads are applied to the crossbeams for subsequent topology optimization analysis, significantly reducing the computational load.

[0017] In one optional implementation, the construction of the topology optimization analysis case includes:

[0018] Construct the first working condition, apply the standard Earth gravity vertically downward to the crossbeam, and extract the force Load1 of each slider on the guide rail and the strain energy U1 of the crossbeam;

[0019] Construct a second working condition, calculate the component of the cutting force under the maximum torque when the slide is located at the lowest position of the Z-axis, apply the calculated cutting force to the end face of the spindle, and extract the force Load2 of each slider on the guide rail and the strain energy U2 of the crossbeam.

[0020] Beneficial Effects: Applying standard Earth gravity vertically downwards, neglecting the beam's own weight in this working condition, and setting the beam's material density to 0, the forces on each slider on the beam guide rail, including the components in the X, Y, and Z axes, are extracted and denoted as Load1. The strain energy of the beam under the first working condition is extracted and denoted as U1. This allows analysis of the beam's deformation and load under the gravity of the Y-axis moving components (i.e., the saddle and ram). The ram is located at the lowest position on the Z-axis. The X, Y, and Z components of the cutting force are calculated under maximum torque. The cutting force is applied to the spindle end face, and the forces on each slider on the beam guide rail, including the X, Y, and Z-axis components, are extracted and denoted as Load2. The strain energy of the beam under the second working condition is extracted and denoted as U2. This allows analysis of the beam's deformation and stress under the cutting force. By analyzing the assembly deformation and cutting deformation under gravity, the rigidity and accuracy of the beam can be fully considered, improving the machining capability and accuracy of the gantry machining center.

[0021] In one optional implementation, the construction of the topology optimization model includes:

[0022] A topology optimization method using the variable density method is adopted, and only the crossbeam is retained, while the loads applied to the crossbeam by other parts are replaced by Load1 and Load2;

[0023] Load1 is applied discretely to the guide rail surface of the crossbeam. The load application points are distributed within the range that the sliders on the guide rail can move to, and the distance between the load application points is equal to the distance between each slider on the guide rail.

[0024] Load2 is applied discretely to the guide rail surface of the crossbeam. The load application points are distributed within the range that the sliders on the guide rail can move to, and the distance between the load application points is equal to the distance between the sliders on the guide rail.

[0025] Beneficial effects: The topology optimization method using the variable density method removes material from non-force transmission paths while retaining material from force transmission paths. Only the crossbeam is retained, and the loads on the crossbeam from other components are replaced by the extracted loads Load1 and Load2, thereby simplifying the model under the first and second working conditions and facilitating the analysis of the reasonable layout of the crossbeam material when the saddle is at different positions on the Y-axis.

[0026] In one alternative implementation, the interior of the beam is filled with a solid structure, and the resulting solid structure is used as the optimization area.

[0027] The weighting coefficient for the first working condition is C1 = U2 / (U1+U2), and the weighting coefficient for the second working condition is C2 = U1 / (U1+U2). Then the weighted strain energy is U = C1*U1 + C2*U2.

[0028] Set manufacturing constraints to determine the thickness of the stiffeners; the constraints include symmetry constraints, maximum member size constraints, and minimum member size constraints.

[0029] Beneficial effects: Considering the assembly deformation and cutting deformation of the crossbeam, weighted performance parameters for evaluating the overall performance of the crossbeam are constructed. After verification and iteration, the stiffness and accuracy of the crossbeam are controlled. The parameter optimization considers the influence of the parameters on the weighted performance index, and the result is determined in one step, simplifying the optimization method.

[0030] In one optional implementation, the structural layout of the beam in the finite element analysis model includes:

[0031] Without considering the material removal direction, a first topological density cloud map is obtained; the location of the main weight reduction window is planned based on the first topological density cloud map.

[0032] The material is removed in the forward and backward directions to obtain the second topological density cloud map; the layout of the reinforcing ribs is planned according to the second topological density cloud map;

[0033] The material is removed to the left and right to obtain the third topological density cloud map; the shape of the reinforcing rib is designed based on the third topological density cloud map.

[0034] Beneficial effects: By performing main force transmission path analysis without considering the material removal direction, and then setting different material removal directions, manufacturing constraints are applied to the internal reinforcing ribs to obtain a detailed layout scheme for the internal reinforcing ribs; that is, by setting different constraint conditions, different topology density cloud maps are obtained, and then the position of the weight reduction window and the layout and shape of the reinforcing ribs are planned and designed.

[0035] In one optional implementation, the sensitivity analysis of the beam parameters includes:

[0036] The range of thicknesses t1, t2, t3, t4, and t5 for the front wall, upper wall, lower wall, rear wall, and internal reinforcing ribs of the crossbeam is determined. Sensitivity analysis is performed within this range to obtain sensitivity curves, and parameter values ​​are determined based on the sensitivity of each parameter.

[0037] Beneficial effects: Optimizing the wall thickness and stiffener thickness based on sensitivity design improves the rigidity and precision of the beam.

[0038] In one optional implementation, the designed crossbeam structure is subjected to calculation and verification of the X-direction and Z-direction deformations of the crossbeam under the first working condition; the X-direction deformation of the lower end face of the spindle is calculated and verified under the second working condition.

[0039] If the first working condition does not meet the requirements, the weight coefficient of the first working condition is increased; if the second working condition does not meet the requirements, the weight coefficient of the second working condition is increased.

[0040] Re-perform topology optimization analysis, strengthen the regions with increased topology density in the topology density cloud map, recalculate and verify, and iterate until the standard requirements are met.

[0041] Beneficial effects: Through topology optimization and verification iteration, the analysis is carried out for two specific working conditions: gravity deformation and cutting deformation. The specific analysis conditions and load application methods are given, which improves the stiffness and accuracy of the crossbeam and further improves the accuracy of the gantry machining center.

[0042] Secondly, the present invention also provides a beam structure, designed and manufactured based on the gantry machining center beam design method described in any of the above claims.

[0043] Beneficial effects: The crossbeam structure is designed and manufactured based on the crossbeam design method of the gantry machining center of this invention. The crossbeam has high rigidity and precision. After optimization, the reliability of the crossbeam is effectively improved, thereby improving the precision of the gantry machining center and ensuring the reliable operation of the gantry machining center.

[0044] In one alternative implementation, the beam structure includes:

[0045] The weight-reduction windows are located at the joint surfaces of the rear wall, left wall, and right wall of the crossbeam and the column, respectively.

[0046] The reinforcing rib structure, located around the weight-reducing window, includes a first reinforcing rib, a second reinforcing rib, a third reinforcing rib, and a fourth reinforcing rib. The first reinforcing rib is inclined, the second reinforcing rib intersects with the first reinforcing rib, the third reinforcing rib is vertically arranged at both ends of the reinforcing rib structure and intersects with the first reinforcing rib, and the fourth reinforcing rib is vertically arranged in the middle of the reinforcing rib structure.

[0047] Beneficial effects: By setting weight-reducing windows at the joint surfaces of the beam's rear, left, and right walls with the columns, and by adding reinforcing ribs around the weight-reducing windows, the beam's stiffness is improved while achieving weight reduction. The first reinforcing rib plays a primary supporting role and is inclined, allowing the load to be transferred from the middle to both ends. The second reinforcing rib is arranged intersecting with the first reinforcing rib, assisting the first reinforcing rib and reinforcing the area below the beam. The third reinforcing rib is located at both ends and is vertical, supporting the structure at both ends. The third reinforcing rib intersects with the first reinforcing rib, improving the rigidity of the main force transmission path. The fourth reinforcing rib is located in the middle and is vertical, improving torsional and shear stiffness. Attached Figure Description

[0048] To more clearly illustrate the technical solutions in the specific embodiments or related technologies of the present invention, the drawings used in the description of the specific embodiments or related technologies will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0049] Figure 1 This is a structural diagram of a finite element analysis model of a gantry machining center according to an embodiment of the present invention;

[0050] Figure 2 for Figure 1 The force diagram of the crossbeam in the first working condition;

[0051] Figure 3 for Figure 2 The force diagram of the crossbeam in the second working condition;

[0052] Figure 4 This is a force diagram of the topology optimization sub-condition of the present invention;

[0053] Figure 5 This is the first topological density cloud map;

[0054] Figure 6 This is the second topological density cloud map;

[0055] Figure 7 This is the third topological density cloud map;

[0056] Figure 8 This is a diagram showing the layout of the reinforcing ribs of the crossbeam of the present invention;

[0057] Figure 9 This is a schematic diagram of the shape of the internal reinforcing ribs of the crossbeam of the present invention;

[0058] Figure 10 This is a sensitivity analysis graph;

[0059] Figure 11 A flowchart illustrating a method for designing the crossbeam of a gantry machining center, provided as a specific embodiment of the present invention.

[0060] Explanation of reference numerals in the attached figures:

[0061] 1. Crossbeam; 11. Weight-reducing window;

[0062] 2. Spindle;

[0063] 3. Guide rail;

[0064] 4. Saddle slide;

[0065] 5. Slide pillow;

[0066] 6. Slider;

[0067] 7. The mating surface between the beam and the column;

[0068] 8. Reinforcing ribs;

[0069] 81. First reinforcing rib; 82. Second reinforcing rib; 83. Third reinforcing rib; 84. Fourth reinforcing rib. Detailed Implementation

[0070] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0071] In the description of the invention, it should be noted that, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," "outer," "front end," "rear end," "head," "tail," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0072] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0073] The following is combined Figures 1 to 11 The following describes embodiments of the present invention.

[0074] According to an embodiment of the present invention, a design method for a crossbeam 1 of a gantry machining center is provided, comprising the following steps:

[0075] Constructing a finite element analysis model of a gantry machining center, such as Figure 1 As shown, the model includes a crossbeam 1, a column, a main shaft 2, a guide rail 3, a sliding saddle 4, a sliding block 5, a slider 6, and a lead screw nut;

[0076] Construct topology optimization analysis conditions and obtain analysis results; the conditions include the assembly deformation of beam 1 caused by gravity and the deformation of beam 1 caused by cutting force.

[0077] Construct a topology optimization model and perform topology optimization for the operating conditions;

[0078] Design the structural layout of beam 1 in the finite element analysis model;

[0079] Sensitivity analysis was performed on the parameters of beam 1 to obtain the optimal parameter values.

[0080] This invention considers both the assembly deformation of the crossbeam 1 caused by gravity and the deformation of the crossbeam 1 caused by cutting force, constructs weighted performance parameters to evaluate the comprehensive performance of the crossbeam 1, designs and lays out the structure of the crossbeam 1, and performs sensitivity analysis on the parameters of the crossbeam 1 to ensure the stiffness and accuracy of the crossbeam 1. Compared with the related technologies that ignore either stiffness or accuracy, this invention ensures both the stiffness and accuracy of the crossbeam 1, optimizes the design of the crossbeam 1, and improves the machining capability and accuracy of the gantry machining center.

[0081] In some embodiments, the boundary conditions of the finite element analysis model include:

[0082] A fixed constraint is set on the mating surface 7 of the beam and the column;

[0083] The crossbeam 1 and the guide rail 3 are bound together. The slide ram 5, the guide rail 3 and the main shaft 2 are bound together. The slide saddle 4 and the slider 6 are bound together. The slide saddle 4 and the lead screw nut are bound together. The lead screw nut and the slide saddle 4 are connected by a lead screw. The guide rail 3 and the slider 6 are slidably connected.

[0084] Based on the structure and connection relationships of the gantry machining center, constraints were set on the model to obtain more accurate optimization parameters. Loads were extracted and applied to beam 1 for subsequent topology optimization analysis, significantly reducing the computational load.

[0085] In some embodiments, constructing the topology optimization analysis case includes:

[0086] Construct the first working condition, apply the standard Earth gravity vertically downward to the crossbeam 1, and extract the force Load1 of each slider 6 on the guide rail 3 and the strain energy U1 of the crossbeam 1.

[0087] Construct the second working condition, calculate the component of the cutting force under the maximum torque when the slide 5 is located at the lowest position of the Z axis, apply the calculated cutting force to the end face of the spindle 2, and extract the force Load2 of each slider 6 on the guide rail 3 and the strain energy U2 of the crossbeam 1.

[0088] Apply a standard downward vertical Earth gravity. In this working condition, the weight of the crossbeam 1 itself is not considered, and the material density of the crossbeam 1 is set to 0. Extract the force on each slider 6 on the crossbeam 1 guide rail 3, including the components in the X, Y, and Z axes, denoted as Load1. Extract the strain energy of the crossbeam 1 in the first working condition, denoted as U1. This allows us to analyze the deformation and load of the crossbeam 1 when subjected to the gravity of the Y-axis moving parts (i.e., the saddle 4 and the ram 5, etc.). The ram 5 is located at the lowest position on the Z-axis. Calculate the X, Y, and Z components of the cutting force under the maximum torque. Apply the cutting force to the end face of the spindle 2. Extract the force on each slider 6 on the crossbeam 1 guide rail 3, including the X, Y, and Z axis components, denoted as Load2. Extract the strain energy of the crossbeam 1 in the second working condition, denoted as U2. This allows us to analyze the deformation and stress of the crossbeam 1 when subjected to the cutting force. By analyzing the assembly deformation and cutting deformation under gravity, the rigidity and accuracy of the crossbeam 1 can be fully considered, thus improving the accuracy of the gantry machining center.

[0089] In some embodiments, constructing a topology optimization model includes:

[0090] A topology optimization method using the variable density method is adopted, and only beam 1 is retained, while the loads applied to beam 1 in other parts are replaced by Load1 and Load2;

[0091] Load1 is applied discretely to the guide rail 3 of the crossbeam 1. The load application points are distributed within the range that the sliders 6 on the guide rail 3 can move to, and the distance between the load application points is equal to the distance between each slider 6 on the guide rail 3.

[0092] Load2 is applied discretely to the guide rail 3 of the crossbeam 1. The load application points are distributed within the range that the sliders 6 on the guide rail 3 can move to, and the distance between the load application points is equal to the distance between each slider 6 on the guide rail 3.

[0093] A topology optimization method using the variable density approach is employed to remove material from non-force transmission paths while retaining material from force transmission paths. Only beam 1 is retained, and the loads on beam 1 from other components are replaced by the extracted loads Load1 and Load2, thereby simplifying the model under the first and second working conditions and facilitating the analysis of the reasonable material layout of beam 1 when saddle 4 is at different positions on the Y-axis.

[0094] In some embodiments, the interior of the beam 1 is filled with a solid structure, and the resulting solid structure is used as the optimization region.

[0095] The weighting coefficient for the first working condition is C1 = U2 / (U1+U2), and the weighting coefficient for the second working condition is C2 = U1 / (U1+U2). Therefore, the weighted strain energy U = C1*U1 + C2*U2.

[0096] Set manufacturing constraints to determine the thickness of stiffener 8; the constraints include symmetry constraints, maximum member size constraints, and minimum member size constraints.

[0097] Considering the assembly deformation and cutting deformation of beam 1, weighted performance parameters for evaluating the overall performance of beam 1 are constructed. After verification and iteration, the stiffness and accuracy of beam 1 are controlled. The parameter optimization considers the influence of the parameters on the weighted performance index, and the result is determined in one step, simplifying the optimization method.

[0098] It should be noted that when manufacturing constraints, the maximum member size constraint is set to the maximum allowable stiffener thickness of 8, and the minimum member size constraint is set to the minimum allowable stiffener thickness of 8.

[0099] In some embodiments, the structural layout of the beam 1 in the finite element analysis model includes:

[0100] Without considering the material removal direction, a first topological density cloud map is obtained; the position of the main weight reduction window 11 is planned based on the first topological density cloud map.

[0101] The material is removed in the forward and backward directions to obtain the second topological density cloud map; the layout of the reinforcing rib 8 is planned according to the second topological density cloud map;

[0102] The material is removed to the left and right to obtain the third topological density cloud map; the shape of the reinforcing rib 8 is designed based on the third topological density cloud map.

[0103] Without considering the material removal direction, the main force transmission path is analyzed, and then different material removal directions are set to apply manufacturing constraints to the internal reinforcing rib 8, resulting in a detailed layout scheme for the internal reinforcing rib 8; that is, by setting different constraint conditions, different topology density cloud maps are obtained, and then the position of the weight reduction window 11 and the layout and shape of the reinforcing rib 8 are planned and designed.

[0104] In some embodiments,

[0105] Sensitivity analysis of the parameters of beam 1 includes:

[0106] Determine the range of thicknesses t1, t2, t3, t4, and t5 for the front wall, upper wall, lower wall, rear wall, and internal reinforcing rib 8 of the crossbeam. Perform sensitivity analysis within this range to obtain sensitivity curves, and determine the parameter values ​​based on the sensitivity of each parameter.

[0107] The wall thickness and the thickness of the reinforcing rib 8 are optimized based on sensitivity design to improve the rigidity and accuracy of the crossbeam 1.

[0108] In some embodiments, the X-direction deformation and Z-direction deformation of the designed beam 1 structure are calculated and verified according to the first working condition; the X-direction deformation of the lower end face of the spindle 2 is calculated and verified according to the second working condition.

[0109] If the first working condition does not meet the requirements, the weight coefficient of the first working condition is increased; if the second working condition does not meet the requirements, the weight coefficient of the second working condition is increased.

[0110] Re-perform topology optimization analysis, strengthen the regions with increased topology density in the topology density cloud map, recalculate and verify, and iterate until the standard requirements are met.

[0111] Through topology optimization and verification iteration, the analysis was conducted on two specific working conditions: gravity deformation and cutting deformation. The specific analysis conditions and load application methods were given, which improved the stiffness and accuracy of beam 1 and further improved the accuracy of the gantry machining center.

[0112] like Figure 11 As shown in the figure, an embodiment of the present invention provides a design method for a crossbeam 1 of a gantry machining center, comprising the following steps:

[0113] S1. Establish the finite element analysis model

[0114] Machine tool components: such as Figure 1 As shown, the model includes a crossbeam 1, a sliding saddle 4, a sliding block 5, a main shaft 2, a guide rail 3, a slider 6, a lead screw nut, and a lead screw seat;

[0115] Boundary conditions: Apply fixed constraints to the mounting surfaces of beam 1 and column;

[0116] Connections between components: Fixed constraints are set at the joint surface 7 of the beam and column. The beam 1 and the guide rail 3 are bound together. The slide 5, the guide rail 3, and the main shaft 2 are bound together. The slide saddle 4 and the slider 6 are bound together. The slide saddle 4 and the lead screw nut are bound together. The lead screw nut and the slide saddle 4 are connected by the lead screw. The guide rail 3 and the slider 6 are connected without separation.

[0117] S2. Analysis and Result Extraction of Key Operating Conditions

[0118] First operating condition:

[0119] Function: To analyze the deformation and load on the crossbeam 1 when it is subjected to gravity by the moving parts (i.e., saddle 4, bolster 5, etc.) on the Y-axis;

[0120] Load: Apply standard Earth gravity vertically downwards. In this case, the weight of beam 1 itself is not considered, and the material density of beam 1 is set to 0.

[0121] Results extraction: a. Extract the force on each slider 6 on the guide rail 3 of beam 1, including the X, Y, and Z axis components, denoted as Load1; b. Extract the strain energy of beam 1 under the first working condition, denoted as U1.

[0122] Figure 2 The force diagram for the first working condition is given.

[0123] Second working condition:

[0124] Purpose: To analyze the deformation and stress state of crossbeam 1 under cutting force;

[0125] Load: The slide 5 is located at the bottom of the Z-axis. The maximum torque is calculated by taking the x, y, and z components of the cutting force and applying the cutting force to the end face of the spindle 2.

[0126] Results extraction: a. Extract the force on each slider 6 on the guide rail 3 of beam 1, including the X, Y, and Z axis components, denoted as Load2; b. Extract the strain energy of beam 1 under the second working condition, denoted as U2.

[0127] Figure 3 The force diagram for the second working condition is given.

[0128] S3, Topology Optimization Settings

[0129] Topology optimization method: The topology optimization method using the variable density method is used to remove material in non-force transmission paths and retain material in force transmission paths;

[0130] Topology optimization analysis model: In order to analyze the reasonable layout of the material of the crossbeam 1 when the saddle 4 is at different positions on the Y-axis, the models of the first and second working conditions are simplified, only the crossbeam 1 is retained, and the loads of other components on the crossbeam 1 are replaced by the extracted loads Load1 and Load2.

[0131] Topology optimization sub-condition 1: The load Load1 extracted from the first condition is applied to the guide rail 3 surface of the beam 1 in a discrete form. The load application points are distributed within the range that the slider 6 of the Y-axis guide rail 3 can move. The spacing between the load application points is equal to the spacing between the sliders 6 of the Y-axis guide rail 3. The load at each application point is equal to the load on the slider 6 extracted from the first condition.

[0132] Topology optimization sub-condition 2: Load2 extracted from the second condition is applied to the guide rail 3 of the crossbeam 1 in the same way as the first condition.

[0133] Optimization area: Fill the interior of beam 1 with solid material, and the resulting solid structure is the optimization area;

[0134] Optimization objective: Minimize weighted strain energy. Weighted strain energy refers to the weighted value of strain energies U1 and U2 in the first and second working conditions. Weighted strain energy is used as the comprehensive performance evaluation index of beam 1; First working condition weight coefficient: C1 = U2 / (U1+U2), First working condition weight coefficient: C2 = U1 / (U1+U2), Weighted strain energy: U = C1*U1 + C2*U2;

[0135] Manufacturing constraints: (a) Symmetry constraint: left and right symmetrical; (b) Maximum member size constraint: set to the maximum stiffening thickness allowed by the structure; (c) Minimum member size constraint: set to the minimum stiffening thickness allowed by the structure.

[0136] Figure 4 The force diagrams for the topology optimization sub-conditions are presented.

[0137] S4. Optimization Analysis:

[0138] S41. First-level optimization analysis: Main force transmission path analysis

[0139] Response constraint: The retained material weight fraction is 10%–20%;

[0140] The direction of material removal is not considered;

[0141] The first topological density cloud map was obtained, see [link / reference]. Figure 5 .

[0142] S42, Second-level optimization analysis: Internal stiffener topology analysis

[0143] Objective: To impose manufacturing constraints on internal stiffeners to obtain a detailed internal stiffener layout scheme;

[0144] Response constraint: The retained material weight fraction is equal to the estimated weight of beam 1 / the weight of solid beam 1;

[0145] Set the material removal direction: Set the material to be removed in a forward or backward direction to obtain the second topology optimization density cloud map. See [link / reference]. Figure 6 The material is removed to the left and right to obtain the third topology-optimized density cloud map. See [link / reference]. Figure 7 .

[0146] S5, Structural Design

[0147] According to the first topological density cloud map, the location of the main weight reduction window 11 is located on the rear wall, left wall and right wall of the crossbeam 1, and at the joint surface of the crossbeam 1 and the column.

[0148] The reinforcing ribs 8 are planned according to the second topological density cloud map. The first reinforcing rib 81 plays a primary supporting role, transferring the load from the middle to both ends; the first reinforcing rib 81 is inclined. The second reinforcing rib 82 intersects with the first reinforcing rib 81, assisting the first reinforcing rib 81 and reinforcing the area below the beam 1. The third reinforcing rib 83 is located at the left and right ends, vertically oriented, supporting the structure at both ends; the third reinforcing rib 83 intersects with the first reinforcing rib 81, improving the rigidity of the main force transmission path. The fourth reinforcing rib 84 is located in the middle, vertically oriented, improving torsional and shear stiffness. See [reference needed for the reinforcing rib layout of beam 1] for details. Figure 8 .

[0149] The internal reinforcing ribs are designed in shape 8 based on the third topological density cloud map. The ribs surround the inside of the wall, with a large rounded corner at the upper left. (See also...) Figure 9 .

[0150] S6. Third-level optimization analysis: Parameter optimization analysis

[0151] Determine the range of values ​​for the thicknesses t1, t2, t3, t4, and t5 of the front wall, upper wall, lower wall, rear wall, and internal reinforcing ribs 8 of the crossbeam 1, and perform sensitivity analysis within this range to obtain sensitivity curves.

[0152] Sensitivity calculation formula: Si=ΔU / Δmi, where S is the sensitivity of the i-th parameter, ΔU is the change in weighted strain energy under the first and second working conditions, and Δmi is the change in mass of beam 1 caused by the change in parameters.

[0153] Get as Figure 10 The sensitivity analysis graph shown has the mass of beam 1 on the horizontal axis and the weighted strain energy of the first and second working conditions on the vertical axis. Each curve corresponds to a parameter, and the slope of the curve is the parameter sensitivity. The wall thickness parameters are then designed based on the sensitivity.

[0154] S7. Result Verification

[0155] First working condition verification: Using the designed structure, calculate and verify the X-direction deformation and Z-direction deformation of beam 1 according to the first working condition in S2;

[0156] Second working condition verification: Calculate and verify the X-direction deformation of the lower end face of spindle 2 according to the method of the second working condition in S2;

[0157] S8, Iterative Optimization

[0158] If the first working condition does not meet the requirements, the weighting coefficient of the first working condition is increased; if the second working condition does not meet the requirements, the weighting coefficient of the second working condition is increased.

[0159] A new topology optimization analysis was performed. The regions with increased topology density were strengthened in the previous topology density cloud map. The results were recalculated and verified, and iterative optimization was carried out until the standard requirements were met.

[0160] According to an embodiment of the present invention, another aspect provides a beam 1 structure, which is designed and manufactured based on the gantry machining center beam 1 design method of the present invention.

[0161] The crossbeam 1 structure is designed and manufactured based on the crossbeam 1 design method of the gantry machining center of the present invention. The crossbeam 1 has high rigidity and precision. After optimization, the reliability of the crossbeam 1 is effectively improved, thereby improving the precision of the gantry machining center and ensuring the reliable operation of the gantry machining center.

[0162] In some embodiments, the beam 1 structure includes:

[0163] Weight reduction windows 11 are located at the joint surfaces of the rear wall, left wall and right wall of the crossbeam 1 and the column, respectively.

[0164] The reinforcing rib structure is located around the weight reduction window 11 and includes a first reinforcing rib 81, a second reinforcing rib 82, a third reinforcing rib 83 and a fourth reinforcing rib 84. The first reinforcing rib 81 is inclined, the second reinforcing rib 82 is intersected with the first reinforcing rib 81, the third reinforcing rib 83 is vertically arranged at both ends of the reinforcing rib structure and intersected with the first reinforcing rib 81, and the fourth reinforcing rib 84 is vertically arranged in the middle of the reinforcing rib structure.

[0165] Weight-reducing windows 11 are respectively set at the joint surfaces of the rear wall, left wall, and right wall of the crossbeam 1 with the column. At the same time, reinforcing ribs 8 are set around the weight-reducing windows 11 to improve the stiffness of the crossbeam 1 and achieve weight reduction. The first reinforcing rib 81 plays the main supporting role. The first reinforcing rib 81 is inclined so that the load is transferred from the middle to both ends. The second reinforcing rib 82 is arranged to cross the first reinforcing rib 81 and plays an auxiliary role to the first reinforcing rib 81, while strengthening the area below the crossbeam 1. The third reinforcing rib 83 is located at the left and right ends and is vertical. It plays a supporting role at both ends of the structure. The third reinforcing rib 83 crosses the first reinforcing rib 81 to improve the rigidity of the main force transmission path. The fourth reinforcing rib 84 is located in the middle and is vertical. It plays a role in improving torsional stiffness and shear stiffness.

[0166] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A gantry machining center crossbeam design method, characterized in that, Includes the following steps: A finite element analysis model of a gantry machining center is constructed. The model includes a crossbeam (1), a column, a spindle (2), a guide rail (3), a slide saddle (4), a slide block (5), a slider (6), and a lead screw nut. Construct topology optimization analysis conditions and obtain analysis results information; the conditions include the assembly deformation of the beam (1) caused by gravity and the deformation of the beam (1) caused by cutting force; Construct a topology optimization model and perform topology optimization for the described working condition; Design the structural layout of the beam (1) in the finite element analysis model; Sensitivity analysis was performed on the parameters of the beam (1) to obtain the optimal parameter values; The topology optimization analysis conditions include: Construct the first working condition, apply the standard Earth gravity vertically downward to the crossbeam (1), and extract the force Load1 of each slider (6) on the guide rail (3) and the strain energy U1 of the crossbeam (1); Construct a second working condition, calculate the component of the cutting force under the maximum torque when the slide block (5) is located at the lowest position of the Z axis, apply the calculated cutting force to the end face of the spindle (2), and extract the force Load2 of each slider (6) on the guide rail (3) and the strain energy U2 of the crossbeam (1); The construction of the topology optimization model includes: A topology optimization method using the variable density method is adopted, and only the crossbeam (1) is retained, while the loads applied to the crossbeam (1) by other parts are replaced by Load1 and Load2; Load1 is applied discretely to the guide rail (3) surface of the crossbeam (1). The load application points are distributed within the range that the sliders (6) on the guide rail (3) can move to. The distance between the load application points is equal to the distance between each slider (6) on the guide rail (3). Load2 is applied discretely to the guide rail (3) surface of the crossbeam (1). The load application points are distributed within the range that the sliders (6) on the guide rail (3) can move to. The distance between the load application points is equal to the distance between each slider (6) on the guide rail (3). The interior of the beam (1) is filled with solid material, and the resulting solid structure is used as the optimization area. The weighting coefficient for the first working condition is C1 = U2 / (U1+U2), and the weighting coefficient for the second working condition is C2 = U1 / (U1+U2). Therefore, the weighted strain energy U = C1*U1 + C2*U2. Set manufacturing constraints to determine the thickness of the stiffener (8); the constraints include symmetry constraints, maximum member size constraints and minimum member size constraints.

2. The method for designing the crossbeam of a gantry machining center according to claim 1, characterized in that, The boundary conditions of the finite element analysis model include: A fixed constraint is set on the joint surface of the crossbeam (1) and the column; The crossbeam (1) is bound to the guide rail (3), the slide block (5), the guide rail (3) and the main shaft (2) are bound to each other, the slide saddle (4) and the slider (6) are bound to each other, the slide saddle (4) and the lead screw nut are bound to each other, the lead screw nut and the slide saddle (4) are connected by a lead screw, and the guide rail (3) and the slider (6) are slidably connected.

3. The method for designing the crossbeam of a gantry machining center according to claim 1, characterized in that, The structural layout of the beam (1) in the finite element analysis model includes: Without considering the material removal direction, the first topological density cloud map is obtained; the position of the main weight reduction window (11) is planned according to the first topological density cloud map; The material is removed in the forward and backward directions to obtain the second topological density cloud map; the layout of the reinforcing ribs (8) is planned according to the second topological density cloud map; The material is removed to the left and right to obtain the third topological density cloud map; the shape of the reinforcing rib (8) is designed according to the third topological density cloud map.

4. The method for designing the crossbeam of a gantry machining center according to claim 3, characterized in that, The sensitivity analysis of the parameters of the beam (1) includes: Determine the range of thicknesses t1, t2, t3, t4 and t5 of the front wall, upper wall, lower wall, rear wall and internal reinforcing ribs (8) of the crossbeam (1), perform sensitivity analysis within this range, obtain sensitivity curves, and determine parameter values ​​based on the sensitivity of each parameter.

5. The method for designing the crossbeam of a gantry machining center according to claim 4, characterized in that, The designed beam (1) structure is calculated and verified according to the first working condition in terms of X-direction deformation and Z-direction deformation; the lower end face of the main shaft (2) is calculated and verified according to the second working condition in terms of X-direction deformation. If the first working condition does not meet the requirements, the weight coefficient of the first working condition is increased; if the second working condition does not meet the requirements, the weight coefficient of the second working condition is increased. Re-perform topology optimization analysis, strengthen the regions with increased topology density in the topology density cloud map, recalculate and verify, and iterate until the standard requirements are met.

6. A beam structure, characterized in that, The gantry machining center beam (1) is designed and manufactured based on the design method of any one of claims 1-5.

7. The beam structure according to claim 6, characterized in that, include: Weight reduction windows (11) are located at the joint surfaces of the rear wall, left wall and right wall of the crossbeam (1) and the column, respectively; The reinforcing rib structure is located around the weight reduction window (11) and includes a first reinforcing rib (81), a second reinforcing rib (82), a third reinforcing rib (83) and a fourth reinforcing rib (84). The first reinforcing rib (81) is inclined, the second reinforcing rib (82) is intersected with the first reinforcing rib (81), the third reinforcing rib (83) is vertically arranged at both ends of the reinforcing rib structure and intersected with the first reinforcing rib (81), and the fourth reinforcing rib (84) is vertically arranged in the middle of the reinforcing rib structure.

Images